1 /*
   2  * Copyright (c) 1997, 2019, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "jvm.h"
  27 #include "aot/aotLoader.hpp"
  28 #include "classfile/classLoader.hpp"
  29 #include "classfile/javaClasses.hpp"
  30 #include "classfile/moduleEntry.hpp"
  31 #include "classfile/systemDictionary.hpp"
  32 #include "classfile/vmSymbols.hpp"
  33 #include "code/codeCache.hpp"
  34 #include "code/scopeDesc.hpp"
  35 #include "compiler/compileBroker.hpp"
  36 #include "compiler/compileTask.hpp"
  37 #include "gc/shared/barrierSet.hpp"
  38 #include "gc/shared/gcId.hpp"
  39 #include "gc/shared/gcLocker.inline.hpp"
  40 #include "gc/shared/workgroup.hpp"
  41 #include "interpreter/interpreter.hpp"
  42 #include "interpreter/linkResolver.hpp"
  43 #include "interpreter/oopMapCache.hpp"
  44 #include "jfr/jfrEvents.hpp"
  45 #include "jvmtifiles/jvmtiEnv.hpp"
  46 #include "logging/log.hpp"
  47 #include "logging/logConfiguration.hpp"
  48 #include "logging/logStream.hpp"
  49 #include "memory/allocation.inline.hpp"
  50 #include "memory/metaspaceShared.hpp"
  51 #include "memory/oopFactory.hpp"
  52 #include "memory/resourceArea.hpp"
  53 #include "memory/universe.hpp"
  54 #include "oops/access.inline.hpp"
  55 #include "oops/instanceKlass.hpp"
  56 #include "oops/objArrayOop.hpp"
  57 #include "oops/oop.inline.hpp"
  58 #include "oops/symbol.hpp"
  59 #include "oops/typeArrayOop.inline.hpp"
  60 #include "oops/verifyOopClosure.hpp"
  61 #include "prims/jvm_misc.hpp"
  62 #include "prims/jvmtiExport.hpp"
  63 #include "prims/jvmtiThreadState.hpp"
  64 #include "runtime/arguments.hpp"
  65 #include "runtime/atomic.hpp"
  66 #include "runtime/biasedLocking.hpp"
  67 #include "runtime/fieldDescriptor.inline.hpp"
  68 #include "runtime/flags/jvmFlagConstraintList.hpp"
  69 #include "runtime/flags/jvmFlagRangeList.hpp"
  70 #include "runtime/flags/jvmFlagWriteableList.hpp"
  71 #include "runtime/deoptimization.hpp"
  72 #include "runtime/frame.inline.hpp"
  73 #include "runtime/handles.inline.hpp"
  74 #include "runtime/handshake.hpp"
  75 #include "runtime/init.hpp"
  76 #include "runtime/interfaceSupport.inline.hpp"
  77 #include "runtime/java.hpp"
  78 #include "runtime/javaCalls.hpp"
  79 #include "runtime/jniHandles.inline.hpp"
  80 #include "runtime/jniPeriodicChecker.hpp"
  81 #include "runtime/memprofiler.hpp"
  82 #include "runtime/mutexLocker.hpp"
  83 #include "runtime/objectMonitor.hpp"
  84 #include "runtime/orderAccess.hpp"
  85 #include "runtime/osThread.hpp"
  86 #include "runtime/prefetch.inline.hpp"
  87 #include "runtime/safepoint.hpp"
  88 #include "runtime/safepointMechanism.inline.hpp"
  89 #include "runtime/safepointVerifiers.hpp"
  90 #include "runtime/sharedRuntime.hpp"
  91 #include "runtime/statSampler.hpp"
  92 #include "runtime/stubRoutines.hpp"
  93 #include "runtime/sweeper.hpp"
  94 #include "runtime/task.hpp"
  95 #include "runtime/thread.inline.hpp"
  96 #include "runtime/threadCritical.hpp"
  97 #include "runtime/threadSMR.inline.hpp"
  98 #include "runtime/threadStatisticalInfo.hpp"
  99 #include "runtime/timer.hpp"
 100 #include "runtime/timerTrace.hpp"
 101 #include "runtime/vframe.inline.hpp"
 102 #include "runtime/vframeArray.hpp"
 103 #include "runtime/vframe_hp.hpp"
 104 #include "runtime/vmThread.hpp"
 105 #include "runtime/vmOperations.hpp"
 106 #include "runtime/vm_version.hpp"
 107 #include "services/attachListener.hpp"
 108 #include "services/management.hpp"
 109 #include "services/memTracker.hpp"
 110 #include "services/threadService.hpp"
 111 #include "utilities/align.hpp"
 112 #include "utilities/copy.hpp"
 113 #include "utilities/defaultStream.hpp"
 114 #include "utilities/dtrace.hpp"
 115 #include "utilities/events.hpp"
 116 #include "utilities/macros.hpp"
 117 #include "utilities/preserveException.hpp"
 118 #include "utilities/singleWriterSynchronizer.hpp"
 119 #include "utilities/vmError.hpp"
 120 #if INCLUDE_JVMCI
 121 #include "jvmci/jvmci.hpp"
 122 #include "jvmci/jvmciEnv.hpp"
 123 #endif
 124 #ifdef COMPILER1
 125 #include "c1/c1_Compiler.hpp"
 126 #endif
 127 #ifdef COMPILER2
 128 #include "opto/c2compiler.hpp"
 129 #include "opto/idealGraphPrinter.hpp"
 130 #endif
 131 #if INCLUDE_RTM_OPT
 132 #include "runtime/rtmLocking.hpp"
 133 #endif
 134 #if INCLUDE_JFR
 135 #include "jfr/jfr.hpp"
 136 #endif
 137 
 138 // Initialization after module runtime initialization
 139 void universe_post_module_init();  // must happen after call_initPhase2
 140 
 141 #ifdef DTRACE_ENABLED
 142 
 143 // Only bother with this argument setup if dtrace is available
 144 
 145   #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
 146   #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
 147 
 148   #define DTRACE_THREAD_PROBE(probe, javathread)                           \
 149     {                                                                      \
 150       ResourceMark rm(this);                                               \
 151       int len = 0;                                                         \
 152       const char* name = (javathread)->get_thread_name();                  \
 153       len = strlen(name);                                                  \
 154       HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */               \
 155         (char *) name, len,                                                \
 156         java_lang_Thread::thread_id((javathread)->threadObj()),            \
 157         (uintptr_t) (javathread)->osthread()->thread_id(),                 \
 158         java_lang_Thread::is_daemon((javathread)->threadObj()));           \
 159     }
 160 
 161 #else //  ndef DTRACE_ENABLED
 162 
 163   #define DTRACE_THREAD_PROBE(probe, javathread)
 164 
 165 #endif // ndef DTRACE_ENABLED
 166 
 167 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 168 // Current thread is maintained as a thread-local variable
 169 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
 170 #endif
 171 
 172 // ======= Thread ========
 173 // Support for forcing alignment of thread objects for biased locking
 174 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
 175   if (UseBiasedLocking) {
 176     const int alignment = markOopDesc::biased_lock_alignment;
 177     size_t aligned_size = size + (alignment - sizeof(intptr_t));
 178     void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
 179                                           : AllocateHeap(aligned_size, flags, CURRENT_PC,
 180                                                          AllocFailStrategy::RETURN_NULL);
 181     void* aligned_addr     = align_up(real_malloc_addr, alignment);
 182     assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
 183            ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
 184            "JavaThread alignment code overflowed allocated storage");
 185     if (aligned_addr != real_malloc_addr) {
 186       log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
 187                               p2i(real_malloc_addr),
 188                               p2i(aligned_addr));
 189     }
 190     ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
 191     return aligned_addr;
 192   } else {
 193     return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
 194                        : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
 195   }
 196 }
 197 
 198 void Thread::operator delete(void* p) {
 199   if (UseBiasedLocking) {
 200     FreeHeap(((Thread*) p)->_real_malloc_address);
 201   } else {
 202     FreeHeap(p);
 203   }
 204 }
 205 
 206 void JavaThread::smr_delete() {
 207   if (_on_thread_list) {
 208     ThreadsSMRSupport::smr_delete(this);
 209   } else {
 210     delete this;
 211   }
 212 }
 213 
 214 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
 215 // JavaThread
 216 
 217 DEBUG_ONLY(Thread* Thread::_starting_thread = NULL;)
 218 
 219 Thread::Thread() {
 220 
 221   DEBUG_ONLY(_run_state = PRE_CALL_RUN;)
 222 
 223   // stack and get_thread
 224   set_stack_base(NULL);
 225   set_stack_size(0);
 226   set_self_raw_id(0);
 227   set_lgrp_id(-1);
 228   DEBUG_ONLY(clear_suspendible_thread();)
 229 
 230   // allocated data structures
 231   set_osthread(NULL);
 232   set_resource_area(new (mtThread)ResourceArea());
 233   DEBUG_ONLY(_current_resource_mark = NULL;)
 234   set_handle_area(new (mtThread) HandleArea(NULL));
 235   set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
 236   set_active_handles(NULL);
 237   set_free_handle_block(NULL);
 238   set_last_handle_mark(NULL);
 239   DEBUG_ONLY(_missed_ic_stub_refill_verifier = NULL);
 240 
 241   // Initial value of zero ==> never claimed.
 242   _threads_do_token = 0;
 243   _threads_hazard_ptr = NULL;
 244   _threads_list_ptr = NULL;
 245   _nested_threads_hazard_ptr_cnt = 0;
 246   _rcu_counter = 0;
 247 
 248   // the handle mark links itself to last_handle_mark
 249   new HandleMark(this);
 250 
 251   // plain initialization
 252   debug_only(_owned_locks = NULL;)
 253   debug_only(_allow_allocation_count = 0;)
 254   NOT_PRODUCT(_allow_safepoint_count = 0;)
 255   NOT_PRODUCT(_skip_gcalot = false;)
 256   _jvmti_env_iteration_count = 0;
 257   set_allocated_bytes(0);
 258   _vm_operation_started_count = 0;
 259   _vm_operation_completed_count = 0;
 260   _current_pending_monitor = NULL;
 261   _current_pending_monitor_is_from_java = true;
 262   _current_waiting_monitor = NULL;
 263   _num_nested_signal = 0;
 264   omFreeList = NULL;
 265   omFreeCount = 0;
 266   omFreeProvision = 32;
 267   omInUseList = NULL;
 268   omInUseCount = 0;
 269 
 270 #ifdef ASSERT
 271   _visited_for_critical_count = false;
 272 #endif
 273 
 274   _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
 275                          Monitor::_safepoint_check_sometimes);
 276   _suspend_flags = 0;
 277 
 278   // thread-specific hashCode stream generator state - Marsaglia shift-xor form
 279   _hashStateX = os::random();
 280   _hashStateY = 842502087;
 281   _hashStateZ = 0x8767;    // (int)(3579807591LL & 0xffff) ;
 282   _hashStateW = 273326509;
 283 
 284   _OnTrap   = 0;
 285   _Stalled  = 0;
 286   _TypeTag  = 0x2BAD;
 287 
 288   // Many of the following fields are effectively final - immutable
 289   // Note that nascent threads can't use the Native Monitor-Mutex
 290   // construct until the _MutexEvent is initialized ...
 291   // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
 292   // we might instead use a stack of ParkEvents that we could provision on-demand.
 293   // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
 294   // and ::Release()
 295   _ParkEvent   = ParkEvent::Allocate(this);
 296   _SleepEvent  = ParkEvent::Allocate(this);
 297   _MuxEvent    = ParkEvent::Allocate(this);
 298 
 299 #ifdef CHECK_UNHANDLED_OOPS
 300   if (CheckUnhandledOops) {
 301     _unhandled_oops = new UnhandledOops(this);
 302   }
 303 #endif // CHECK_UNHANDLED_OOPS
 304 #ifdef ASSERT
 305   if (UseBiasedLocking) {
 306     assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
 307     assert(this == _real_malloc_address ||
 308            this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment),
 309            "bug in forced alignment of thread objects");
 310   }
 311 #endif // ASSERT
 312 
 313   // Notify the barrier set that a thread is being created. The initial
 314   // thread is created before the barrier set is available.  The call to
 315   // BarrierSet::on_thread_create() for this thread is therefore deferred
 316   // to BarrierSet::set_barrier_set().
 317   BarrierSet* const barrier_set = BarrierSet::barrier_set();
 318   if (barrier_set != NULL) {
 319     barrier_set->on_thread_create(this);
 320   } else {
 321     // Only the main thread should be created before the barrier set
 322     // and that happens just before Thread::current is set. No other thread
 323     // can attach as the VM is not created yet, so they can't execute this code.
 324     // If the main thread creates other threads before the barrier set that is an error.
 325     assert(Thread::current_or_null() == NULL, "creating thread before barrier set");
 326   }
 327 }
 328 
 329 void Thread::initialize_thread_current() {
 330 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 331   assert(_thr_current == NULL, "Thread::current already initialized");
 332   _thr_current = this;
 333 #endif
 334   assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
 335   ThreadLocalStorage::set_thread(this);
 336   assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
 337 }
 338 
 339 void Thread::clear_thread_current() {
 340   assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
 341 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 342   _thr_current = NULL;
 343 #endif
 344   ThreadLocalStorage::set_thread(NULL);
 345 }
 346 
 347 void Thread::record_stack_base_and_size() {
 348   // Note: at this point, Thread object is not yet initialized. Do not rely on
 349   // any members being initialized. Do not rely on Thread::current() being set.
 350   // If possible, refrain from doing anything which may crash or assert since
 351   // quite probably those crash dumps will be useless.
 352   set_stack_base(os::current_stack_base());
 353   set_stack_size(os::current_stack_size());
 354 
 355 #ifdef SOLARIS
 356   if (os::is_primordial_thread()) {
 357     os::Solaris::correct_stack_boundaries_for_primordial_thread(this);
 358   }
 359 #endif
 360 
 361   // Set stack limits after thread is initialized.
 362   if (is_Java_thread()) {
 363     ((JavaThread*) this)->set_stack_overflow_limit();
 364     ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
 365   }
 366 }
 367 
 368 #if INCLUDE_NMT
 369 void Thread::register_thread_stack_with_NMT() {
 370   MemTracker::record_thread_stack(stack_end(), stack_size());
 371 }
 372 #endif // INCLUDE_NMT
 373 
 374 void Thread::call_run() {
 375   DEBUG_ONLY(_run_state = CALL_RUN;)
 376 
 377   // At this point, Thread object should be fully initialized and
 378   // Thread::current() should be set.
 379 
 380   assert(Thread::current_or_null() != NULL, "current thread is unset");
 381   assert(Thread::current_or_null() == this, "current thread is wrong");
 382 
 383   // Perform common initialization actions
 384 
 385   register_thread_stack_with_NMT();
 386 
 387   JFR_ONLY(Jfr::on_thread_start(this);)
 388 
 389   log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
 390     PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
 391     os::current_thread_id(), p2i(stack_base() - stack_size()),
 392     p2i(stack_base()), stack_size()/1024);
 393 
 394   // Perform <ChildClass> initialization actions
 395   DEBUG_ONLY(_run_state = PRE_RUN;)
 396   this->pre_run();
 397 
 398   // Invoke <ChildClass>::run()
 399   DEBUG_ONLY(_run_state = RUN;)
 400   this->run();
 401   // Returned from <ChildClass>::run(). Thread finished.
 402 
 403   // Perform common tear-down actions
 404 
 405   assert(Thread::current_or_null() != NULL, "current thread is unset");
 406   assert(Thread::current_or_null() == this, "current thread is wrong");
 407 
 408   // Perform <ChildClass> tear-down actions
 409   DEBUG_ONLY(_run_state = POST_RUN;)
 410   this->post_run();
 411 
 412   // Note: at this point the thread object may already have deleted itself,
 413   // so from here on do not dereference *this*. Not all thread types currently
 414   // delete themselves when they terminate. But no thread should ever be deleted
 415   // asynchronously with respect to its termination - that is what _run_state can
 416   // be used to check.
 417 
 418   assert(Thread::current_or_null() == NULL, "current thread still present");
 419 }
 420 
 421 Thread::~Thread() {
 422 
 423   // Attached threads will remain in PRE_CALL_RUN, as will threads that don't actually
 424   // get started due to errors etc. Any active thread should at least reach post_run
 425   // before it is deleted (usually in post_run()).
 426   assert(_run_state == PRE_CALL_RUN ||
 427          _run_state == POST_RUN, "Active Thread deleted before post_run(): "
 428          "_run_state=%d", (int)_run_state);
 429 
 430   // Notify the barrier set that a thread is being destroyed. Note that a barrier
 431   // set might not be available if we encountered errors during bootstrapping.
 432   BarrierSet* const barrier_set = BarrierSet::barrier_set();
 433   if (barrier_set != NULL) {
 434     barrier_set->on_thread_destroy(this);
 435   }
 436 
 437   // stack_base can be NULL if the thread is never started or exited before
 438   // record_stack_base_and_size called. Although, we would like to ensure
 439   // that all started threads do call record_stack_base_and_size(), there is
 440   // not proper way to enforce that.
 441 #if INCLUDE_NMT
 442   if (_stack_base != NULL) {
 443     MemTracker::release_thread_stack(stack_end(), stack_size());
 444 #ifdef ASSERT
 445     set_stack_base(NULL);
 446 #endif
 447   }
 448 #endif // INCLUDE_NMT
 449 
 450   // deallocate data structures
 451   delete resource_area();
 452   // since the handle marks are using the handle area, we have to deallocated the root
 453   // handle mark before deallocating the thread's handle area,
 454   assert(last_handle_mark() != NULL, "check we have an element");
 455   delete last_handle_mark();
 456   assert(last_handle_mark() == NULL, "check we have reached the end");
 457 
 458   // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
 459   // We NULL out the fields for good hygiene.
 460   ParkEvent::Release(_ParkEvent); _ParkEvent   = NULL;
 461   ParkEvent::Release(_SleepEvent); _SleepEvent  = NULL;
 462   ParkEvent::Release(_MuxEvent); _MuxEvent    = NULL;
 463 
 464   delete handle_area();
 465   delete metadata_handles();
 466 
 467   // SR_handler uses this as a termination indicator -
 468   // needs to happen before os::free_thread()
 469   delete _SR_lock;
 470   _SR_lock = NULL;
 471 
 472   // osthread() can be NULL, if creation of thread failed.
 473   if (osthread() != NULL) os::free_thread(osthread());
 474 
 475   // Clear Thread::current if thread is deleting itself and it has not
 476   // already been done. This must be done before the memory is deallocated.
 477   // Needed to ensure JNI correctly detects non-attached threads.
 478   if (this == Thread::current_or_null()) {
 479     Thread::clear_thread_current();
 480   }
 481 
 482   CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
 483 }
 484 
 485 #ifdef ASSERT
 486 // A JavaThread is considered "dangling" if it is not the current
 487 // thread, has been added the Threads list, the system is not at a
 488 // safepoint and the Thread is not "protected".
 489 //
 490 void Thread::check_for_dangling_thread_pointer(Thread *thread) {
 491   assert(!thread->is_Java_thread() || Thread::current() == thread ||
 492          !((JavaThread *) thread)->on_thread_list() ||
 493          SafepointSynchronize::is_at_safepoint() ||
 494          ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread),
 495          "possibility of dangling Thread pointer");
 496 }
 497 #endif
 498 
 499 ThreadPriority Thread::get_priority(const Thread* const thread) {
 500   ThreadPriority priority;
 501   // Can return an error!
 502   (void)os::get_priority(thread, priority);
 503   assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
 504   return priority;
 505 }
 506 
 507 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
 508   debug_only(check_for_dangling_thread_pointer(thread);)
 509   // Can return an error!
 510   (void)os::set_priority(thread, priority);
 511 }
 512 
 513 
 514 void Thread::start(Thread* thread) {
 515   // Start is different from resume in that its safety is guaranteed by context or
 516   // being called from a Java method synchronized on the Thread object.
 517   if (!DisableStartThread) {
 518     if (thread->is_Java_thread()) {
 519       // Initialize the thread state to RUNNABLE before starting this thread.
 520       // Can not set it after the thread started because we do not know the
 521       // exact thread state at that time. It could be in MONITOR_WAIT or
 522       // in SLEEPING or some other state.
 523       java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
 524                                           java_lang_Thread::RUNNABLE);
 525     }
 526     os::start_thread(thread);
 527   }
 528 }
 529 
 530 // Enqueue a VM_Operation to do the job for us - sometime later
 531 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
 532   VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
 533   VMThread::execute(vm_stop);
 534 }
 535 
 536 
 537 // Check if an external suspend request has completed (or has been
 538 // cancelled). Returns true if the thread is externally suspended and
 539 // false otherwise.
 540 //
 541 // The bits parameter returns information about the code path through
 542 // the routine. Useful for debugging:
 543 //
 544 // set in is_ext_suspend_completed():
 545 // 0x00000001 - routine was entered
 546 // 0x00000010 - routine return false at end
 547 // 0x00000100 - thread exited (return false)
 548 // 0x00000200 - suspend request cancelled (return false)
 549 // 0x00000400 - thread suspended (return true)
 550 // 0x00001000 - thread is in a suspend equivalent state (return true)
 551 // 0x00002000 - thread is native and walkable (return true)
 552 // 0x00004000 - thread is native_trans and walkable (needed retry)
 553 //
 554 // set in wait_for_ext_suspend_completion():
 555 // 0x00010000 - routine was entered
 556 // 0x00020000 - suspend request cancelled before loop (return false)
 557 // 0x00040000 - thread suspended before loop (return true)
 558 // 0x00080000 - suspend request cancelled in loop (return false)
 559 // 0x00100000 - thread suspended in loop (return true)
 560 // 0x00200000 - suspend not completed during retry loop (return false)
 561 
 562 // Helper class for tracing suspend wait debug bits.
 563 //
 564 // 0x00000100 indicates that the target thread exited before it could
 565 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
 566 // 0x00080000 each indicate a cancelled suspend request so they don't
 567 // count as wait failures either.
 568 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
 569 
 570 class TraceSuspendDebugBits : public StackObj {
 571  private:
 572   JavaThread * jt;
 573   bool         is_wait;
 574   bool         called_by_wait;  // meaningful when !is_wait
 575   uint32_t *   bits;
 576 
 577  public:
 578   TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
 579                         uint32_t *_bits) {
 580     jt             = _jt;
 581     is_wait        = _is_wait;
 582     called_by_wait = _called_by_wait;
 583     bits           = _bits;
 584   }
 585 
 586   ~TraceSuspendDebugBits() {
 587     if (!is_wait) {
 588 #if 1
 589       // By default, don't trace bits for is_ext_suspend_completed() calls.
 590       // That trace is very chatty.
 591       return;
 592 #else
 593       if (!called_by_wait) {
 594         // If tracing for is_ext_suspend_completed() is enabled, then only
 595         // trace calls to it from wait_for_ext_suspend_completion()
 596         return;
 597       }
 598 #endif
 599     }
 600 
 601     if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
 602       if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
 603         MutexLocker ml(Threads_lock);  // needed for get_thread_name()
 604         ResourceMark rm;
 605 
 606         tty->print_cr(
 607                       "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
 608                       jt->get_thread_name(), *bits);
 609 
 610         guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
 611       }
 612     }
 613   }
 614 };
 615 #undef DEBUG_FALSE_BITS
 616 
 617 
 618 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
 619                                           uint32_t *bits) {
 620   TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
 621 
 622   bool did_trans_retry = false;  // only do thread_in_native_trans retry once
 623   bool do_trans_retry;           // flag to force the retry
 624 
 625   *bits |= 0x00000001;
 626 
 627   do {
 628     do_trans_retry = false;
 629 
 630     if (is_exiting()) {
 631       // Thread is in the process of exiting. This is always checked
 632       // first to reduce the risk of dereferencing a freed JavaThread.
 633       *bits |= 0x00000100;
 634       return false;
 635     }
 636 
 637     if (!is_external_suspend()) {
 638       // Suspend request is cancelled. This is always checked before
 639       // is_ext_suspended() to reduce the risk of a rogue resume
 640       // confusing the thread that made the suspend request.
 641       *bits |= 0x00000200;
 642       return false;
 643     }
 644 
 645     if (is_ext_suspended()) {
 646       // thread is suspended
 647       *bits |= 0x00000400;
 648       return true;
 649     }
 650 
 651     // Now that we no longer do hard suspends of threads running
 652     // native code, the target thread can be changing thread state
 653     // while we are in this routine:
 654     //
 655     //   _thread_in_native -> _thread_in_native_trans -> _thread_blocked
 656     //
 657     // We save a copy of the thread state as observed at this moment
 658     // and make our decision about suspend completeness based on the
 659     // copy. This closes the race where the thread state is seen as
 660     // _thread_in_native_trans in the if-thread_blocked check, but is
 661     // seen as _thread_blocked in if-thread_in_native_trans check.
 662     JavaThreadState save_state = thread_state();
 663 
 664     if (save_state == _thread_blocked && is_suspend_equivalent()) {
 665       // If the thread's state is _thread_blocked and this blocking
 666       // condition is known to be equivalent to a suspend, then we can
 667       // consider the thread to be externally suspended. This means that
 668       // the code that sets _thread_blocked has been modified to do
 669       // self-suspension if the blocking condition releases. We also
 670       // used to check for CONDVAR_WAIT here, but that is now covered by
 671       // the _thread_blocked with self-suspension check.
 672       //
 673       // Return true since we wouldn't be here unless there was still an
 674       // external suspend request.
 675       *bits |= 0x00001000;
 676       return true;
 677     } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
 678       // Threads running native code will self-suspend on native==>VM/Java
 679       // transitions. If its stack is walkable (should always be the case
 680       // unless this function is called before the actual java_suspend()
 681       // call), then the wait is done.
 682       *bits |= 0x00002000;
 683       return true;
 684     } else if (!called_by_wait && !did_trans_retry &&
 685                save_state == _thread_in_native_trans &&
 686                frame_anchor()->walkable()) {
 687       // The thread is transitioning from thread_in_native to another
 688       // thread state. check_safepoint_and_suspend_for_native_trans()
 689       // will force the thread to self-suspend. If it hasn't gotten
 690       // there yet we may have caught the thread in-between the native
 691       // code check above and the self-suspend. Lucky us. If we were
 692       // called by wait_for_ext_suspend_completion(), then it
 693       // will be doing the retries so we don't have to.
 694       //
 695       // Since we use the saved thread state in the if-statement above,
 696       // there is a chance that the thread has already transitioned to
 697       // _thread_blocked by the time we get here. In that case, we will
 698       // make a single unnecessary pass through the logic below. This
 699       // doesn't hurt anything since we still do the trans retry.
 700 
 701       *bits |= 0x00004000;
 702 
 703       // Once the thread leaves thread_in_native_trans for another
 704       // thread state, we break out of this retry loop. We shouldn't
 705       // need this flag to prevent us from getting back here, but
 706       // sometimes paranoia is good.
 707       did_trans_retry = true;
 708 
 709       // We wait for the thread to transition to a more usable state.
 710       for (int i = 1; i <= SuspendRetryCount; i++) {
 711         // We used to do an "os::yield_all(i)" call here with the intention
 712         // that yielding would increase on each retry. However, the parameter
 713         // is ignored on Linux which means the yield didn't scale up. Waiting
 714         // on the SR_lock below provides a much more predictable scale up for
 715         // the delay. It also provides a simple/direct point to check for any
 716         // safepoint requests from the VMThread
 717 
 718         // temporarily drops SR_lock while doing wait with safepoint check
 719         // (if we're a JavaThread - the WatcherThread can also call this)
 720         // and increase delay with each retry
 721         if (Thread::current()->is_Java_thread()) {
 722           SR_lock()->wait(i * delay);
 723         } else {
 724           SR_lock()->wait_without_safepoint_check(i * delay);
 725         }
 726 
 727         // check the actual thread state instead of what we saved above
 728         if (thread_state() != _thread_in_native_trans) {
 729           // the thread has transitioned to another thread state so
 730           // try all the checks (except this one) one more time.
 731           do_trans_retry = true;
 732           break;
 733         }
 734       } // end retry loop
 735 
 736 
 737     }
 738   } while (do_trans_retry);
 739 
 740   *bits |= 0x00000010;
 741   return false;
 742 }
 743 
 744 // Wait for an external suspend request to complete (or be cancelled).
 745 // Returns true if the thread is externally suspended and false otherwise.
 746 //
 747 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
 748                                                  uint32_t *bits) {
 749   TraceSuspendDebugBits tsdb(this, true /* is_wait */,
 750                              false /* !called_by_wait */, bits);
 751 
 752   // local flag copies to minimize SR_lock hold time
 753   bool is_suspended;
 754   bool pending;
 755   uint32_t reset_bits;
 756 
 757   // set a marker so is_ext_suspend_completed() knows we are the caller
 758   *bits |= 0x00010000;
 759 
 760   // We use reset_bits to reinitialize the bits value at the top of
 761   // each retry loop. This allows the caller to make use of any
 762   // unused bits for their own marking purposes.
 763   reset_bits = *bits;
 764 
 765   {
 766     MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
 767     is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 768                                             delay, bits);
 769     pending = is_external_suspend();
 770   }
 771   // must release SR_lock to allow suspension to complete
 772 
 773   if (!pending) {
 774     // A cancelled suspend request is the only false return from
 775     // is_ext_suspend_completed() that keeps us from entering the
 776     // retry loop.
 777     *bits |= 0x00020000;
 778     return false;
 779   }
 780 
 781   if (is_suspended) {
 782     *bits |= 0x00040000;
 783     return true;
 784   }
 785 
 786   for (int i = 1; i <= retries; i++) {
 787     *bits = reset_bits;  // reinit to only track last retry
 788 
 789     // We used to do an "os::yield_all(i)" call here with the intention
 790     // that yielding would increase on each retry. However, the parameter
 791     // is ignored on Linux which means the yield didn't scale up. Waiting
 792     // on the SR_lock below provides a much more predictable scale up for
 793     // the delay. It also provides a simple/direct point to check for any
 794     // safepoint requests from the VMThread
 795 
 796     {
 797       Thread* t = Thread::current();
 798       MonitorLocker ml(SR_lock(),
 799                        t->is_Java_thread() ? Mutex::_safepoint_check_flag : Mutex::_no_safepoint_check_flag);
 800       // wait with safepoint check (if we're a JavaThread - the WatcherThread
 801       // can also call this)  and increase delay with each retry
 802       ml.wait(i * delay);
 803 
 804       is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 805                                               delay, bits);
 806 
 807       // It is possible for the external suspend request to be cancelled
 808       // (by a resume) before the actual suspend operation is completed.
 809       // Refresh our local copy to see if we still need to wait.
 810       pending = is_external_suspend();
 811     }
 812 
 813     if (!pending) {
 814       // A cancelled suspend request is the only false return from
 815       // is_ext_suspend_completed() that keeps us from staying in the
 816       // retry loop.
 817       *bits |= 0x00080000;
 818       return false;
 819     }
 820 
 821     if (is_suspended) {
 822       *bits |= 0x00100000;
 823       return true;
 824     }
 825   } // end retry loop
 826 
 827   // thread did not suspend after all our retries
 828   *bits |= 0x00200000;
 829   return false;
 830 }
 831 
 832 // Called from API entry points which perform stack walking. If the
 833 // associated JavaThread is the current thread, then wait_for_suspend
 834 // is not used. Otherwise, it determines if we should wait for the
 835 // "other" thread to complete external suspension. (NOTE: in future
 836 // releases the suspension mechanism should be reimplemented so this
 837 // is not necessary.)
 838 //
 839 bool
 840 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) {
 841   if (this != JavaThread::current()) {
 842     // "other" threads require special handling.
 843     if (wait_for_suspend) {
 844       // We are allowed to wait for the external suspend to complete
 845       // so give the other thread a chance to get suspended.
 846       if (!wait_for_ext_suspend_completion(SuspendRetryCount,
 847                                            SuspendRetryDelay, bits)) {
 848         // Didn't make it so let the caller know.
 849         return false;
 850       }
 851     }
 852     // We aren't allowed to wait for the external suspend to complete
 853     // so if the other thread isn't externally suspended we need to
 854     // let the caller know.
 855     else if (!is_ext_suspend_completed_with_lock(bits)) {
 856       return false;
 857     }
 858   }
 859 
 860   return true;
 861 }
 862 
 863 #ifndef PRODUCT
 864 void JavaThread::record_jump(address target, address instr, const char* file,
 865                              int line) {
 866 
 867   // This should not need to be atomic as the only way for simultaneous
 868   // updates is via interrupts. Even then this should be rare or non-existent
 869   // and we don't care that much anyway.
 870 
 871   int index = _jmp_ring_index;
 872   _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
 873   _jmp_ring[index]._target = (intptr_t) target;
 874   _jmp_ring[index]._instruction = (intptr_t) instr;
 875   _jmp_ring[index]._file = file;
 876   _jmp_ring[index]._line = line;
 877 }
 878 #endif // PRODUCT
 879 
 880 void Thread::interrupt(Thread* thread) {
 881   debug_only(check_for_dangling_thread_pointer(thread);)
 882   os::interrupt(thread);
 883 }
 884 
 885 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
 886   debug_only(check_for_dangling_thread_pointer(thread);)
 887   // Note:  If clear_interrupted==false, this simply fetches and
 888   // returns the value of the field osthread()->interrupted().
 889   return os::is_interrupted(thread, clear_interrupted);
 890 }
 891 
 892 
 893 // GC Support
 894 bool Thread::claim_par_threads_do(uintx claim_token) {
 895   uintx token = _threads_do_token;
 896   if (token != claim_token) {
 897     uintx res = Atomic::cmpxchg(claim_token, &_threads_do_token, token);
 898     if (res == token) {
 899       return true;
 900     }
 901     guarantee(res == claim_token, "invariant");
 902   }
 903   return false;
 904 }
 905 
 906 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
 907   active_handles()->oops_do(f);
 908   // Do oop for ThreadShadow
 909   f->do_oop((oop*)&_pending_exception);
 910   handle_area()->oops_do(f);
 911 
 912   // We scan thread local monitor lists here, and the remaining global
 913   // monitors in ObjectSynchronizer::oops_do().
 914   ObjectSynchronizer::thread_local_used_oops_do(this, f);
 915 }
 916 
 917 void Thread::metadata_handles_do(void f(Metadata*)) {
 918   // Only walk the Handles in Thread.
 919   if (metadata_handles() != NULL) {
 920     for (int i = 0; i< metadata_handles()->length(); i++) {
 921       f(metadata_handles()->at(i));
 922     }
 923   }
 924 }
 925 
 926 void Thread::print_on(outputStream* st, bool print_extended_info) const {
 927   // get_priority assumes osthread initialized
 928   if (osthread() != NULL) {
 929     int os_prio;
 930     if (os::get_native_priority(this, &os_prio) == OS_OK) {
 931       st->print("os_prio=%d ", os_prio);
 932     }
 933 
 934     st->print("cpu=%.2fms ",
 935               os::thread_cpu_time(const_cast<Thread*>(this), true) / 1000000.0
 936               );
 937     st->print("elapsed=%.2fs ",
 938               _statistical_info.getElapsedTime() / 1000.0
 939               );
 940     if (is_Java_thread() && (PrintExtendedThreadInfo || print_extended_info)) {
 941       size_t allocated_bytes = (size_t) const_cast<Thread*>(this)->cooked_allocated_bytes();
 942       st->print("allocated=" SIZE_FORMAT "%s ",
 943                 byte_size_in_proper_unit(allocated_bytes),
 944                 proper_unit_for_byte_size(allocated_bytes)
 945                 );
 946       st->print("defined_classes=" INT64_FORMAT " ", _statistical_info.getDefineClassCount());
 947     }
 948 
 949     st->print("tid=" INTPTR_FORMAT " ", p2i(this));
 950     osthread()->print_on(st);
 951   }
 952   ThreadsSMRSupport::print_info_on(this, st);
 953   st->print(" ");
 954   debug_only(if (WizardMode) print_owned_locks_on(st);)
 955 }
 956 
 957 void Thread::print() const { print_on(tty); }
 958 
 959 // Thread::print_on_error() is called by fatal error handler. Don't use
 960 // any lock or allocate memory.
 961 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
 962   assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
 963 
 964   if (is_VM_thread())                 { st->print("VMThread"); }
 965   else if (is_GC_task_thread())       { st->print("GCTaskThread"); }
 966   else if (is_Watcher_thread())       { st->print("WatcherThread"); }
 967   else if (is_ConcurrentGC_thread())  { st->print("ConcurrentGCThread"); }
 968   else                                { st->print("Thread"); }
 969 
 970   if (is_Named_thread()) {
 971     st->print(" \"%s\"", name());
 972   }
 973 
 974   st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
 975             p2i(stack_end()), p2i(stack_base()));
 976 
 977   if (osthread()) {
 978     st->print(" [id=%d]", osthread()->thread_id());
 979   }
 980 
 981   ThreadsSMRSupport::print_info_on(this, st);
 982 }
 983 
 984 void Thread::print_value_on(outputStream* st) const {
 985   if (is_Named_thread()) {
 986     st->print(" \"%s\" ", name());
 987   }
 988   st->print(INTPTR_FORMAT, p2i(this));   // print address
 989 }
 990 
 991 #ifdef ASSERT
 992 void Thread::print_owned_locks_on(outputStream* st) const {
 993   Monitor *cur = _owned_locks;
 994   if (cur == NULL) {
 995     st->print(" (no locks) ");
 996   } else {
 997     st->print_cr(" Locks owned:");
 998     while (cur) {
 999       cur->print_on(st);
1000       cur = cur->next();
1001     }
1002   }
1003 }
1004 
1005 static int ref_use_count  = 0;
1006 
1007 bool Thread::owns_locks_but_compiled_lock() const {
1008   for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
1009     if (cur != Compile_lock) return true;
1010   }
1011   return false;
1012 }
1013 
1014 
1015 #endif
1016 
1017 #ifndef PRODUCT
1018 
1019 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially
1020 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that
1021 // no locks which allow_vm_block's are held
1022 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
1023   // Check if current thread is allowed to block at a safepoint
1024   if (!(_allow_safepoint_count == 0)) {
1025     fatal("Possible safepoint reached by thread that does not allow it");
1026   }
1027   if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
1028     fatal("LEAF method calling lock?");
1029   }
1030 
1031 #ifdef ASSERT
1032   if (potential_vm_operation && is_Java_thread()
1033       && !Universe::is_bootstrapping()) {
1034     // Make sure we do not hold any locks that the VM thread also uses.
1035     // This could potentially lead to deadlocks
1036     for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
1037       // Threads_lock is special, since the safepoint synchronization will not start before this is
1038       // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
1039       // since it is used to transfer control between JavaThreads and the VMThread
1040       // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
1041       if ((cur->allow_vm_block() &&
1042            cur != Threads_lock &&
1043            cur != Compile_lock &&               // Temporary: should not be necessary when we get separate compilation
1044            cur != VMOperationRequest_lock &&
1045            cur != VMOperationQueue_lock) ||
1046            cur->rank() == Mutex::special) {
1047         fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
1048       }
1049     }
1050   }
1051 
1052   if (GCALotAtAllSafepoints) {
1053     // We could enter a safepoint here and thus have a gc
1054     InterfaceSupport::check_gc_alot();
1055   }
1056 #endif
1057 }
1058 #endif
1059 
1060 bool Thread::is_in_stack(address adr) const {
1061   assert(Thread::current() == this, "is_in_stack can only be called from current thread");
1062   address end = os::current_stack_pointer();
1063   // Allow non Java threads to call this without stack_base
1064   if (_stack_base == NULL) return true;
1065   if (stack_base() >= adr && adr >= end) return true;
1066 
1067   return false;
1068 }
1069 
1070 bool Thread::is_in_usable_stack(address adr) const {
1071   size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
1072   size_t usable_stack_size = _stack_size - stack_guard_size;
1073 
1074   return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
1075 }
1076 
1077 
1078 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
1079 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
1080 // used for compilation in the future. If that change is made, the need for these methods
1081 // should be revisited, and they should be removed if possible.
1082 
1083 bool Thread::is_lock_owned(address adr) const {
1084   return on_local_stack(adr);
1085 }
1086 
1087 bool Thread::set_as_starting_thread() {
1088   assert(_starting_thread == NULL, "already initialized: "
1089          "_starting_thread=" INTPTR_FORMAT, p2i(_starting_thread));
1090   // NOTE: this must be called inside the main thread.
1091   DEBUG_ONLY(_starting_thread = this;)
1092   return os::create_main_thread((JavaThread*)this);
1093 }
1094 
1095 static void initialize_class(Symbol* class_name, TRAPS) {
1096   Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
1097   InstanceKlass::cast(klass)->initialize(CHECK);
1098 }
1099 
1100 
1101 // Creates the initial ThreadGroup
1102 static Handle create_initial_thread_group(TRAPS) {
1103   Handle system_instance = JavaCalls::construct_new_instance(
1104                             SystemDictionary::ThreadGroup_klass(),
1105                             vmSymbols::void_method_signature(),
1106                             CHECK_NH);
1107   Universe::set_system_thread_group(system_instance());
1108 
1109   Handle string = java_lang_String::create_from_str("main", CHECK_NH);
1110   Handle main_instance = JavaCalls::construct_new_instance(
1111                             SystemDictionary::ThreadGroup_klass(),
1112                             vmSymbols::threadgroup_string_void_signature(),
1113                             system_instance,
1114                             string,
1115                             CHECK_NH);
1116   return main_instance;
1117 }
1118 
1119 // Creates the initial Thread
1120 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
1121                                  TRAPS) {
1122   InstanceKlass* ik = SystemDictionary::Thread_klass();
1123   assert(ik->is_initialized(), "must be");
1124   instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
1125 
1126   // Cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1127   // constructor calls Thread.current(), which must be set here for the
1128   // initial thread.
1129   java_lang_Thread::set_thread(thread_oop(), thread);
1130   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1131   thread->set_threadObj(thread_oop());
1132 
1133   Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1134 
1135   JavaValue result(T_VOID);
1136   JavaCalls::call_special(&result, thread_oop,
1137                           ik,
1138                           vmSymbols::object_initializer_name(),
1139                           vmSymbols::threadgroup_string_void_signature(),
1140                           thread_group,
1141                           string,
1142                           CHECK_NULL);
1143   return thread_oop();
1144 }
1145 
1146 char java_runtime_name[128] = "";
1147 char java_runtime_version[128] = "";
1148 
1149 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1150 static const char* get_java_runtime_name(TRAPS) {
1151   Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1152                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1153   fieldDescriptor fd;
1154   bool found = k != NULL &&
1155                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1156                                                         vmSymbols::string_signature(), &fd);
1157   if (found) {
1158     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1159     if (name_oop == NULL) {
1160       return NULL;
1161     }
1162     const char* name = java_lang_String::as_utf8_string(name_oop,
1163                                                         java_runtime_name,
1164                                                         sizeof(java_runtime_name));
1165     return name;
1166   } else {
1167     return NULL;
1168   }
1169 }
1170 
1171 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1172 static const char* get_java_runtime_version(TRAPS) {
1173   Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1174                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1175   fieldDescriptor fd;
1176   bool found = k != NULL &&
1177                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1178                                                         vmSymbols::string_signature(), &fd);
1179   if (found) {
1180     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1181     if (name_oop == NULL) {
1182       return NULL;
1183     }
1184     const char* name = java_lang_String::as_utf8_string(name_oop,
1185                                                         java_runtime_version,
1186                                                         sizeof(java_runtime_version));
1187     return name;
1188   } else {
1189     return NULL;
1190   }
1191 }
1192 
1193 // General purpose hook into Java code, run once when the VM is initialized.
1194 // The Java library method itself may be changed independently from the VM.
1195 static void call_postVMInitHook(TRAPS) {
1196   Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1197   if (klass != NULL) {
1198     JavaValue result(T_VOID);
1199     JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1200                            vmSymbols::void_method_signature(),
1201                            CHECK);
1202   }
1203 }
1204 
1205 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1206                                     bool daemon, TRAPS) {
1207   assert(thread_group.not_null(), "thread group should be specified");
1208   assert(threadObj() == NULL, "should only create Java thread object once");
1209 
1210   InstanceKlass* ik = SystemDictionary::Thread_klass();
1211   assert(ik->is_initialized(), "must be");
1212   instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1213 
1214   // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon.
1215   // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1216   // constructor calls Thread.current(), which must be set here.
1217   java_lang_Thread::set_thread(thread_oop(), this);
1218   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1219   set_threadObj(thread_oop());
1220 
1221   JavaValue result(T_VOID);
1222   if (thread_name != NULL) {
1223     Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1224     // Thread gets assigned specified name and null target
1225     JavaCalls::call_special(&result,
1226                             thread_oop,
1227                             ik,
1228                             vmSymbols::object_initializer_name(),
1229                             vmSymbols::threadgroup_string_void_signature(),
1230                             thread_group,
1231                             name,
1232                             THREAD);
1233   } else {
1234     // Thread gets assigned name "Thread-nnn" and null target
1235     // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1236     JavaCalls::call_special(&result,
1237                             thread_oop,
1238                             ik,
1239                             vmSymbols::object_initializer_name(),
1240                             vmSymbols::threadgroup_runnable_void_signature(),
1241                             thread_group,
1242                             Handle(),
1243                             THREAD);
1244   }
1245 
1246 
1247   if (daemon) {
1248     java_lang_Thread::set_daemon(thread_oop());
1249   }
1250 
1251   if (HAS_PENDING_EXCEPTION) {
1252     return;
1253   }
1254 
1255   Klass* group =  SystemDictionary::ThreadGroup_klass();
1256   Handle threadObj(THREAD, this->threadObj());
1257 
1258   JavaCalls::call_special(&result,
1259                           thread_group,
1260                           group,
1261                           vmSymbols::add_method_name(),
1262                           vmSymbols::thread_void_signature(),
1263                           threadObj,          // Arg 1
1264                           THREAD);
1265 }
1266 
1267 // List of all NonJavaThreads and safe iteration over that list.
1268 
1269 class NonJavaThread::List {
1270 public:
1271   NonJavaThread* volatile _head;
1272   SingleWriterSynchronizer _protect;
1273 
1274   List() : _head(NULL), _protect() {}
1275 };
1276 
1277 NonJavaThread::List NonJavaThread::_the_list;
1278 
1279 NonJavaThread::Iterator::Iterator() :
1280   _protect_enter(_the_list._protect.enter()),
1281   _current(OrderAccess::load_acquire(&_the_list._head))
1282 {}
1283 
1284 NonJavaThread::Iterator::~Iterator() {
1285   _the_list._protect.exit(_protect_enter);
1286 }
1287 
1288 void NonJavaThread::Iterator::step() {
1289   assert(!end(), "precondition");
1290   _current = OrderAccess::load_acquire(&_current->_next);
1291 }
1292 
1293 NonJavaThread::NonJavaThread() : Thread(), _next(NULL) {
1294   assert(BarrierSet::barrier_set() != NULL, "NonJavaThread created too soon!");
1295 }
1296 
1297 NonJavaThread::~NonJavaThread() { }
1298 
1299 void NonJavaThread::add_to_the_list() {
1300   MutexLocker ml(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1301   // Initialize BarrierSet-related data before adding to list.
1302   BarrierSet::barrier_set()->on_thread_attach(this);
1303   OrderAccess::release_store(&_next, _the_list._head);
1304   OrderAccess::release_store(&_the_list._head, this);
1305 }
1306 
1307 void NonJavaThread::remove_from_the_list() {
1308   {
1309     MutexLocker ml(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1310     // Cleanup BarrierSet-related data before removing from list.
1311     BarrierSet::barrier_set()->on_thread_detach(this);
1312     NonJavaThread* volatile* p = &_the_list._head;
1313     for (NonJavaThread* t = *p; t != NULL; p = &t->_next, t = *p) {
1314       if (t == this) {
1315         *p = _next;
1316         break;
1317       }
1318     }
1319   }
1320   // Wait for any in-progress iterators.  Concurrent synchronize is not
1321   // allowed, so do it while holding a dedicated lock.  Outside and distinct
1322   // from NJTList_lock in case an iteration attempts to lock it.
1323   MutexLocker ml(NonJavaThreadsListSync_lock, Mutex::_no_safepoint_check_flag);
1324   _the_list._protect.synchronize();
1325   _next = NULL;                 // Safe to drop the link now.
1326 }
1327 
1328 void NonJavaThread::pre_run() {
1329   add_to_the_list();
1330 
1331   // This is slightly odd in that NamedThread is a subclass, but
1332   // in fact name() is defined in Thread
1333   assert(this->name() != NULL, "thread name was not set before it was started");
1334   this->set_native_thread_name(this->name());
1335 }
1336 
1337 void NonJavaThread::post_run() {
1338   JFR_ONLY(Jfr::on_thread_exit(this);)
1339   remove_from_the_list();
1340   // Ensure thread-local-storage is cleared before termination.
1341   Thread::clear_thread_current();
1342 }
1343 
1344 // NamedThread --  non-JavaThread subclasses with multiple
1345 // uniquely named instances should derive from this.
1346 NamedThread::NamedThread() :
1347   NonJavaThread(),
1348   _name(NULL),
1349   _processed_thread(NULL),
1350   _gc_id(GCId::undefined())
1351 {}
1352 
1353 NamedThread::~NamedThread() {
1354   if (_name != NULL) {
1355     FREE_C_HEAP_ARRAY(char, _name);
1356     _name = NULL;
1357   }
1358 }
1359 
1360 void NamedThread::set_name(const char* format, ...) {
1361   guarantee(_name == NULL, "Only get to set name once.");
1362   _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1363   guarantee(_name != NULL, "alloc failure");
1364   va_list ap;
1365   va_start(ap, format);
1366   jio_vsnprintf(_name, max_name_len, format, ap);
1367   va_end(ap);
1368 }
1369 
1370 void NamedThread::print_on(outputStream* st) const {
1371   st->print("\"%s\" ", name());
1372   Thread::print_on(st);
1373   st->cr();
1374 }
1375 
1376 
1377 // ======= WatcherThread ========
1378 
1379 // The watcher thread exists to simulate timer interrupts.  It should
1380 // be replaced by an abstraction over whatever native support for
1381 // timer interrupts exists on the platform.
1382 
1383 WatcherThread* WatcherThread::_watcher_thread   = NULL;
1384 bool WatcherThread::_startable = false;
1385 volatile bool  WatcherThread::_should_terminate = false;
1386 
1387 WatcherThread::WatcherThread() : NonJavaThread() {
1388   assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1389   if (os::create_thread(this, os::watcher_thread)) {
1390     _watcher_thread = this;
1391 
1392     // Set the watcher thread to the highest OS priority which should not be
1393     // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1394     // is created. The only normal thread using this priority is the reference
1395     // handler thread, which runs for very short intervals only.
1396     // If the VMThread's priority is not lower than the WatcherThread profiling
1397     // will be inaccurate.
1398     os::set_priority(this, MaxPriority);
1399     if (!DisableStartThread) {
1400       os::start_thread(this);
1401     }
1402   }
1403 }
1404 
1405 int WatcherThread::sleep() const {
1406   // The WatcherThread does not participate in the safepoint protocol
1407   // for the PeriodicTask_lock because it is not a JavaThread.
1408   MonitorLocker ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1409 
1410   if (_should_terminate) {
1411     // check for termination before we do any housekeeping or wait
1412     return 0;  // we did not sleep.
1413   }
1414 
1415   // remaining will be zero if there are no tasks,
1416   // causing the WatcherThread to sleep until a task is
1417   // enrolled
1418   int remaining = PeriodicTask::time_to_wait();
1419   int time_slept = 0;
1420 
1421   // we expect this to timeout - we only ever get unparked when
1422   // we should terminate or when a new task has been enrolled
1423   OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1424 
1425   jlong time_before_loop = os::javaTimeNanos();
1426 
1427   while (true) {
1428     bool timedout = ml.wait(remaining);
1429     jlong now = os::javaTimeNanos();
1430 
1431     if (remaining == 0) {
1432       // if we didn't have any tasks we could have waited for a long time
1433       // consider the time_slept zero and reset time_before_loop
1434       time_slept = 0;
1435       time_before_loop = now;
1436     } else {
1437       // need to recalculate since we might have new tasks in _tasks
1438       time_slept = (int) ((now - time_before_loop) / 1000000);
1439     }
1440 
1441     // Change to task list or spurious wakeup of some kind
1442     if (timedout || _should_terminate) {
1443       break;
1444     }
1445 
1446     remaining = PeriodicTask::time_to_wait();
1447     if (remaining == 0) {
1448       // Last task was just disenrolled so loop around and wait until
1449       // another task gets enrolled
1450       continue;
1451     }
1452 
1453     remaining -= time_slept;
1454     if (remaining <= 0) {
1455       break;
1456     }
1457   }
1458 
1459   return time_slept;
1460 }
1461 
1462 void WatcherThread::run() {
1463   assert(this == watcher_thread(), "just checking");
1464 
1465   this->set_active_handles(JNIHandleBlock::allocate_block());
1466   while (true) {
1467     assert(watcher_thread() == Thread::current(), "thread consistency check");
1468     assert(watcher_thread() == this, "thread consistency check");
1469 
1470     // Calculate how long it'll be until the next PeriodicTask work
1471     // should be done, and sleep that amount of time.
1472     int time_waited = sleep();
1473 
1474     if (VMError::is_error_reported()) {
1475       // A fatal error has happened, the error handler(VMError::report_and_die)
1476       // should abort JVM after creating an error log file. However in some
1477       // rare cases, the error handler itself might deadlock. Here periodically
1478       // check for error reporting timeouts, and if it happens, just proceed to
1479       // abort the VM.
1480 
1481       // This code is in WatcherThread because WatcherThread wakes up
1482       // periodically so the fatal error handler doesn't need to do anything;
1483       // also because the WatcherThread is less likely to crash than other
1484       // threads.
1485 
1486       for (;;) {
1487         // Note: we use naked sleep in this loop because we want to avoid using
1488         // any kind of VM infrastructure which may be broken at this point.
1489         if (VMError::check_timeout()) {
1490           // We hit error reporting timeout. Error reporting was interrupted and
1491           // will be wrapping things up now (closing files etc). Give it some more
1492           // time, then quit the VM.
1493           os::naked_short_sleep(200);
1494           // Print a message to stderr.
1495           fdStream err(defaultStream::output_fd());
1496           err.print_raw_cr("# [ timer expired, abort... ]");
1497           // skip atexit/vm_exit/vm_abort hooks
1498           os::die();
1499         }
1500 
1501         // Wait a second, then recheck for timeout.
1502         os::naked_short_sleep(999);
1503       }
1504     }
1505 
1506     if (_should_terminate) {
1507       // check for termination before posting the next tick
1508       break;
1509     }
1510 
1511     PeriodicTask::real_time_tick(time_waited);
1512   }
1513 
1514   // Signal that it is terminated
1515   {
1516     MutexLocker mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1517     _watcher_thread = NULL;
1518     Terminator_lock->notify_all();
1519   }
1520 }
1521 
1522 void WatcherThread::start() {
1523   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1524 
1525   if (watcher_thread() == NULL && _startable) {
1526     _should_terminate = false;
1527     // Create the single instance of WatcherThread
1528     new WatcherThread();
1529   }
1530 }
1531 
1532 void WatcherThread::make_startable() {
1533   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1534   _startable = true;
1535 }
1536 
1537 void WatcherThread::stop() {
1538   {
1539     // Follow normal safepoint aware lock enter protocol since the
1540     // WatcherThread is stopped by another JavaThread.
1541     MutexLocker ml(PeriodicTask_lock);
1542     _should_terminate = true;
1543 
1544     WatcherThread* watcher = watcher_thread();
1545     if (watcher != NULL) {
1546       // unpark the WatcherThread so it can see that it should terminate
1547       watcher->unpark();
1548     }
1549   }
1550 
1551   MonitorLocker mu(Terminator_lock);
1552 
1553   while (watcher_thread() != NULL) {
1554     // This wait should make safepoint checks, wait without a timeout,
1555     // and wait as a suspend-equivalent condition.
1556     mu.wait(0, Mutex::_as_suspend_equivalent_flag);
1557   }
1558 }
1559 
1560 void WatcherThread::unpark() {
1561   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1562   PeriodicTask_lock->notify();
1563 }
1564 
1565 void WatcherThread::print_on(outputStream* st) const {
1566   st->print("\"%s\" ", name());
1567   Thread::print_on(st);
1568   st->cr();
1569 }
1570 
1571 // ======= JavaThread ========
1572 
1573 #if INCLUDE_JVMCI
1574 
1575 jlong* JavaThread::_jvmci_old_thread_counters;
1576 
1577 bool jvmci_counters_include(JavaThread* thread) {
1578   return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1579 }
1580 
1581 void JavaThread::collect_counters(jlong* array, int length) {
1582   assert(length == JVMCICounterSize, "wrong value");
1583   for (int i = 0; i < length; i++) {
1584     array[i] = _jvmci_old_thread_counters[i];
1585   }
1586   for (JavaThreadIteratorWithHandle jtiwh; JavaThread *tp = jtiwh.next(); ) {
1587     if (jvmci_counters_include(tp)) {
1588       for (int i = 0; i < length; i++) {
1589         array[i] += tp->_jvmci_counters[i];
1590       }
1591     }
1592   }
1593 }
1594 
1595 // Attempt to enlarge the array for per thread counters.
1596 jlong* resize_counters_array(jlong* old_counters, int current_size, int new_size) {
1597   jlong* new_counters = NEW_C_HEAP_ARRAY(jlong, new_size, mtJVMCI);
1598   if (new_counters == NULL) {
1599     return NULL;
1600   }
1601   if (old_counters == NULL) {
1602     old_counters = new_counters;
1603     memset(old_counters, 0, sizeof(jlong) * new_size);
1604   } else {
1605     for (int i = 0; i < MIN2((int) current_size, new_size); i++) {
1606       new_counters[i] = old_counters[i];
1607     }
1608     if (new_size > current_size) {
1609       memset(new_counters + current_size, 0, sizeof(jlong) * (new_size - current_size));
1610     }
1611     FREE_C_HEAP_ARRAY(jlong, old_counters);
1612   }
1613   return new_counters;
1614 }
1615 
1616 // Attempt to enlarge the array for per thread counters.
1617 bool JavaThread::resize_counters(int current_size, int new_size) {
1618   jlong* new_counters = resize_counters_array(_jvmci_counters, current_size, new_size);
1619   if (new_counters == NULL) {
1620     return false;
1621   } else {
1622     _jvmci_counters = new_counters;
1623     return true;
1624   }
1625 }
1626 
1627 class VM_JVMCIResizeCounters : public VM_Operation {
1628  private:
1629   int _new_size;
1630   bool _failed;
1631 
1632  public:
1633   VM_JVMCIResizeCounters(int new_size) : _new_size(new_size), _failed(false) { }
1634   VMOp_Type type()                  const        { return VMOp_JVMCIResizeCounters; }
1635   bool allow_nested_vm_operations() const        { return true; }
1636   void doit() {
1637     // Resize the old thread counters array
1638     jlong* new_counters = resize_counters_array(JavaThread::_jvmci_old_thread_counters, JVMCICounterSize, _new_size);
1639     if (new_counters == NULL) {
1640       _failed = true;
1641       return;
1642     } else {
1643       JavaThread::_jvmci_old_thread_counters = new_counters;
1644     }
1645 
1646     // Now resize each threads array
1647     for (JavaThreadIteratorWithHandle jtiwh; JavaThread *tp = jtiwh.next(); ) {
1648       if (!tp->resize_counters(JVMCICounterSize, _new_size)) {
1649         _failed = true;
1650         break;
1651       }
1652     }
1653     if (!_failed) {
1654       JVMCICounterSize = _new_size;
1655     }
1656   }
1657 
1658   bool failed() { return _failed; }
1659 };
1660 
1661 bool JavaThread::resize_all_jvmci_counters(int new_size) {
1662   VM_JVMCIResizeCounters op(new_size);
1663   VMThread::execute(&op);
1664   return !op.failed();
1665 }
1666 
1667 #endif // INCLUDE_JVMCI
1668 
1669 // A JavaThread is a normal Java thread
1670 
1671 void JavaThread::initialize() {
1672   // Initialize fields
1673 
1674   set_saved_exception_pc(NULL);
1675   set_threadObj(NULL);
1676   _anchor.clear();
1677   set_entry_point(NULL);
1678   set_jni_functions(jni_functions());
1679   set_callee_target(NULL);
1680   set_vm_result(NULL);
1681   set_vm_result_2(NULL);
1682   set_vframe_array_head(NULL);
1683   set_vframe_array_last(NULL);
1684   set_deferred_locals(NULL);
1685   set_deopt_mark(NULL);
1686   set_deopt_compiled_method(NULL);
1687   clear_must_deopt_id();
1688   set_monitor_chunks(NULL);
1689   _on_thread_list = false;
1690   set_thread_state(_thread_new);
1691   _terminated = _not_terminated;
1692   _array_for_gc = NULL;
1693   _suspend_equivalent = false;
1694   _in_deopt_handler = 0;
1695   _doing_unsafe_access = false;
1696   _stack_guard_state = stack_guard_unused;
1697 #if INCLUDE_JVMCI
1698   _pending_monitorenter = false;
1699   _pending_deoptimization = -1;
1700   _pending_failed_speculation = 0;
1701   _pending_transfer_to_interpreter = false;
1702   _in_retryable_allocation = false;
1703   _jvmci._alternate_call_target = NULL;
1704   assert(_jvmci._implicit_exception_pc == NULL, "must be");
1705   _jvmci_counters = NULL;
1706   if (JVMCICounterSize > 0) {
1707     resize_counters(0, (int) JVMCICounterSize);
1708   }
1709 #endif // INCLUDE_JVMCI
1710   _reserved_stack_activation = NULL;  // stack base not known yet
1711   (void)const_cast<oop&>(_exception_oop = oop(NULL));
1712   _exception_pc  = 0;
1713   _exception_handler_pc = 0;
1714   _is_method_handle_return = 0;
1715   _jvmti_thread_state= NULL;
1716   _should_post_on_exceptions_flag = JNI_FALSE;
1717   _interp_only_mode    = 0;
1718   _special_runtime_exit_condition = _no_async_condition;
1719   _pending_async_exception = NULL;
1720   _thread_stat = NULL;
1721   _thread_stat = new ThreadStatistics();
1722   _blocked_on_compilation = false;
1723   _jni_active_critical = 0;
1724   _pending_jni_exception_check_fn = NULL;
1725   _do_not_unlock_if_synchronized = false;
1726   _cached_monitor_info = NULL;
1727   _parker = Parker::Allocate(this);
1728 
1729 #ifndef PRODUCT
1730   _jmp_ring_index = 0;
1731   for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1732     record_jump(NULL, NULL, NULL, 0);
1733   }
1734 #endif // PRODUCT
1735 
1736   // Setup safepoint state info for this thread
1737   ThreadSafepointState::create(this);
1738 
1739   debug_only(_java_call_counter = 0);
1740 
1741   // JVMTI PopFrame support
1742   _popframe_condition = popframe_inactive;
1743   _popframe_preserved_args = NULL;
1744   _popframe_preserved_args_size = 0;
1745   _frames_to_pop_failed_realloc = 0;
1746 
1747   if (SafepointMechanism::uses_thread_local_poll()) {
1748     SafepointMechanism::initialize_header(this);
1749   }
1750 
1751   _class_to_be_initialized = NULL;
1752 
1753   pd_initialize();
1754 }
1755 
1756 JavaThread::JavaThread(bool is_attaching_via_jni) :
1757                        Thread() {
1758   initialize();
1759   if (is_attaching_via_jni) {
1760     _jni_attach_state = _attaching_via_jni;
1761   } else {
1762     _jni_attach_state = _not_attaching_via_jni;
1763   }
1764   assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1765 }
1766 
1767 bool JavaThread::reguard_stack(address cur_sp) {
1768   if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1769       && _stack_guard_state != stack_guard_reserved_disabled) {
1770     return true; // Stack already guarded or guard pages not needed.
1771   }
1772 
1773   if (register_stack_overflow()) {
1774     // For those architectures which have separate register and
1775     // memory stacks, we must check the register stack to see if
1776     // it has overflowed.
1777     return false;
1778   }
1779 
1780   // Java code never executes within the yellow zone: the latter is only
1781   // there to provoke an exception during stack banging.  If java code
1782   // is executing there, either StackShadowPages should be larger, or
1783   // some exception code in c1, c2 or the interpreter isn't unwinding
1784   // when it should.
1785   guarantee(cur_sp > stack_reserved_zone_base(),
1786             "not enough space to reguard - increase StackShadowPages");
1787   if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1788     enable_stack_yellow_reserved_zone();
1789     if (reserved_stack_activation() != stack_base()) {
1790       set_reserved_stack_activation(stack_base());
1791     }
1792   } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1793     set_reserved_stack_activation(stack_base());
1794     enable_stack_reserved_zone();
1795   }
1796   return true;
1797 }
1798 
1799 bool JavaThread::reguard_stack(void) {
1800   return reguard_stack(os::current_stack_pointer());
1801 }
1802 
1803 
1804 void JavaThread::block_if_vm_exited() {
1805   if (_terminated == _vm_exited) {
1806     // _vm_exited is set at safepoint, and Threads_lock is never released
1807     // we will block here forever
1808     Threads_lock->lock_without_safepoint_check();
1809     ShouldNotReachHere();
1810   }
1811 }
1812 
1813 
1814 // Remove this ifdef when C1 is ported to the compiler interface.
1815 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1816 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1817 
1818 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1819                        Thread() {
1820   initialize();
1821   _jni_attach_state = _not_attaching_via_jni;
1822   set_entry_point(entry_point);
1823   // Create the native thread itself.
1824   // %note runtime_23
1825   os::ThreadType thr_type = os::java_thread;
1826   thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1827                                                      os::java_thread;
1828   os::create_thread(this, thr_type, stack_sz);
1829   // The _osthread may be NULL here because we ran out of memory (too many threads active).
1830   // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1831   // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1832   // the exception consists of creating the exception object & initializing it, initialization
1833   // will leave the VM via a JavaCall and then all locks must be unlocked).
1834   //
1835   // The thread is still suspended when we reach here. Thread must be explicit started
1836   // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1837   // by calling Threads:add. The reason why this is not done here, is because the thread
1838   // object must be fully initialized (take a look at JVM_Start)
1839 }
1840 
1841 JavaThread::~JavaThread() {
1842 
1843   // JSR166 -- return the parker to the free list
1844   Parker::Release(_parker);
1845   _parker = NULL;
1846 
1847   // Free any remaining  previous UnrollBlock
1848   vframeArray* old_array = vframe_array_last();
1849 
1850   if (old_array != NULL) {
1851     Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1852     old_array->set_unroll_block(NULL);
1853     delete old_info;
1854     delete old_array;
1855   }
1856 
1857   GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1858   if (deferred != NULL) {
1859     // This can only happen if thread is destroyed before deoptimization occurs.
1860     assert(deferred->length() != 0, "empty array!");
1861     do {
1862       jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1863       deferred->remove_at(0);
1864       // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1865       delete dlv;
1866     } while (deferred->length() != 0);
1867     delete deferred;
1868   }
1869 
1870   // All Java related clean up happens in exit
1871   ThreadSafepointState::destroy(this);
1872   if (_thread_stat != NULL) delete _thread_stat;
1873 
1874 #if INCLUDE_JVMCI
1875   if (JVMCICounterSize > 0) {
1876     if (jvmci_counters_include(this)) {
1877       for (int i = 0; i < JVMCICounterSize; i++) {
1878         _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1879       }
1880     }
1881     FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1882   }
1883 #endif // INCLUDE_JVMCI
1884 }
1885 
1886 
1887 // First JavaThread specific code executed by a new Java thread.
1888 void JavaThread::pre_run() {
1889   // empty - see comments in run()
1890 }
1891 
1892 // The main routine called by a new Java thread. This isn't overridden
1893 // by subclasses, instead different subclasses define a different "entry_point"
1894 // which defines the actual logic for that kind of thread.
1895 void JavaThread::run() {
1896   // initialize thread-local alloc buffer related fields
1897   this->initialize_tlab();
1898 
1899   // Used to test validity of stack trace backs.
1900   // This can't be moved into pre_run() else we invalidate
1901   // the requirement that thread_main_inner is lower on
1902   // the stack. Consequently all the initialization logic
1903   // stays here in run() rather than pre_run().
1904   this->record_base_of_stack_pointer();
1905 
1906   this->create_stack_guard_pages();
1907 
1908   this->cache_global_variables();
1909 
1910   // Thread is now sufficiently initialized to be handled by the safepoint code as being
1911   // in the VM. Change thread state from _thread_new to _thread_in_vm
1912   ThreadStateTransition::transition(this, _thread_new, _thread_in_vm);
1913   // Before a thread is on the threads list it is always safe, so after leaving the
1914   // _thread_new we should emit a instruction barrier. The distance to modified code
1915   // from here is probably far enough, but this is consistent and safe.
1916   OrderAccess::cross_modify_fence();
1917 
1918   assert(JavaThread::current() == this, "sanity check");
1919   assert(!Thread::current()->owns_locks(), "sanity check");
1920 
1921   DTRACE_THREAD_PROBE(start, this);
1922 
1923   // This operation might block. We call that after all safepoint checks for a new thread has
1924   // been completed.
1925   this->set_active_handles(JNIHandleBlock::allocate_block());
1926 
1927   if (JvmtiExport::should_post_thread_life()) {
1928     JvmtiExport::post_thread_start(this);
1929 
1930   }
1931 
1932   // We call another function to do the rest so we are sure that the stack addresses used
1933   // from there will be lower than the stack base just computed.
1934   thread_main_inner();
1935 }
1936 
1937 void JavaThread::thread_main_inner() {
1938   assert(JavaThread::current() == this, "sanity check");
1939   assert(this->threadObj() != NULL, "just checking");
1940 
1941   // Execute thread entry point unless this thread has a pending exception
1942   // or has been stopped before starting.
1943   // Note: Due to JVM_StopThread we can have pending exceptions already!
1944   if (!this->has_pending_exception() &&
1945       !java_lang_Thread::is_stillborn(this->threadObj())) {
1946     {
1947       ResourceMark rm(this);
1948       this->set_native_thread_name(this->get_thread_name());
1949     }
1950     HandleMark hm(this);
1951     this->entry_point()(this, this);
1952   }
1953 
1954   DTRACE_THREAD_PROBE(stop, this);
1955 
1956   // Cleanup is handled in post_run()
1957 }
1958 
1959 // Shared teardown for all JavaThreads
1960 void JavaThread::post_run() {
1961   this->exit(false);
1962   // Defer deletion to here to ensure 'this' is still referenceable in call_run
1963   // for any shared tear-down.
1964   this->smr_delete();
1965 }
1966 
1967 static void ensure_join(JavaThread* thread) {
1968   // We do not need to grab the Threads_lock, since we are operating on ourself.
1969   Handle threadObj(thread, thread->threadObj());
1970   assert(threadObj.not_null(), "java thread object must exist");
1971   ObjectLocker lock(threadObj, thread);
1972   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1973   thread->clear_pending_exception();
1974   // Thread is exiting. So set thread_status field in  java.lang.Thread class to TERMINATED.
1975   java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1976   // Clear the native thread instance - this makes isAlive return false and allows the join()
1977   // to complete once we've done the notify_all below
1978   java_lang_Thread::set_thread(threadObj(), NULL);
1979   lock.notify_all(thread);
1980   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1981   thread->clear_pending_exception();
1982 }
1983 
1984 static bool is_daemon(oop threadObj) {
1985   return (threadObj != NULL && java_lang_Thread::is_daemon(threadObj));
1986 }
1987 
1988 // For any new cleanup additions, please check to see if they need to be applied to
1989 // cleanup_failed_attach_current_thread as well.
1990 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1991   assert(this == JavaThread::current(), "thread consistency check");
1992 
1993   elapsedTimer _timer_exit_phase1;
1994   elapsedTimer _timer_exit_phase2;
1995   elapsedTimer _timer_exit_phase3;
1996   elapsedTimer _timer_exit_phase4;
1997 
1998   if (log_is_enabled(Debug, os, thread, timer)) {
1999     _timer_exit_phase1.start();
2000   }
2001 
2002   HandleMark hm(this);
2003   Handle uncaught_exception(this, this->pending_exception());
2004   this->clear_pending_exception();
2005   Handle threadObj(this, this->threadObj());
2006   assert(threadObj.not_null(), "Java thread object should be created");
2007 
2008   // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
2009   {
2010     EXCEPTION_MARK;
2011 
2012     CLEAR_PENDING_EXCEPTION;
2013   }
2014   if (!destroy_vm) {
2015     if (uncaught_exception.not_null()) {
2016       EXCEPTION_MARK;
2017       // Call method Thread.dispatchUncaughtException().
2018       Klass* thread_klass = SystemDictionary::Thread_klass();
2019       JavaValue result(T_VOID);
2020       JavaCalls::call_virtual(&result,
2021                               threadObj, thread_klass,
2022                               vmSymbols::dispatchUncaughtException_name(),
2023                               vmSymbols::throwable_void_signature(),
2024                               uncaught_exception,
2025                               THREAD);
2026       if (HAS_PENDING_EXCEPTION) {
2027         ResourceMark rm(this);
2028         jio_fprintf(defaultStream::error_stream(),
2029                     "\nException: %s thrown from the UncaughtExceptionHandler"
2030                     " in thread \"%s\"\n",
2031                     pending_exception()->klass()->external_name(),
2032                     get_thread_name());
2033         CLEAR_PENDING_EXCEPTION;
2034       }
2035     }
2036     JFR_ONLY(Jfr::on_java_thread_dismantle(this);)
2037 
2038     // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
2039     // the execution of the method. If that is not enough, then we don't really care. Thread.stop
2040     // is deprecated anyhow.
2041     if (!is_Compiler_thread()) {
2042       int count = 3;
2043       while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
2044         EXCEPTION_MARK;
2045         JavaValue result(T_VOID);
2046         Klass* thread_klass = SystemDictionary::Thread_klass();
2047         JavaCalls::call_virtual(&result,
2048                                 threadObj, thread_klass,
2049                                 vmSymbols::exit_method_name(),
2050                                 vmSymbols::void_method_signature(),
2051                                 THREAD);
2052         CLEAR_PENDING_EXCEPTION;
2053       }
2054     }
2055     // notify JVMTI
2056     if (JvmtiExport::should_post_thread_life()) {
2057       JvmtiExport::post_thread_end(this);
2058     }
2059 
2060     // We have notified the agents that we are exiting, before we go on,
2061     // we must check for a pending external suspend request and honor it
2062     // in order to not surprise the thread that made the suspend request.
2063     while (true) {
2064       {
2065         MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2066         if (!is_external_suspend()) {
2067           set_terminated(_thread_exiting);
2068           ThreadService::current_thread_exiting(this, is_daemon(threadObj()));
2069           break;
2070         }
2071         // Implied else:
2072         // Things get a little tricky here. We have a pending external
2073         // suspend request, but we are holding the SR_lock so we
2074         // can't just self-suspend. So we temporarily drop the lock
2075         // and then self-suspend.
2076       }
2077 
2078       ThreadBlockInVM tbivm(this);
2079       java_suspend_self();
2080 
2081       // We're done with this suspend request, but we have to loop around
2082       // and check again. Eventually we will get SR_lock without a pending
2083       // external suspend request and will be able to mark ourselves as
2084       // exiting.
2085     }
2086     // no more external suspends are allowed at this point
2087   } else {
2088     assert(!is_terminated() && !is_exiting(), "must not be exiting");
2089     // before_exit() has already posted JVMTI THREAD_END events
2090   }
2091 
2092   if (log_is_enabled(Debug, os, thread, timer)) {
2093     _timer_exit_phase1.stop();
2094     _timer_exit_phase2.start();
2095   }
2096 
2097   // Capture daemon status before the thread is marked as terminated.
2098   bool daemon = is_daemon(threadObj());
2099 
2100   // Notify waiters on thread object. This has to be done after exit() is called
2101   // on the thread (if the thread is the last thread in a daemon ThreadGroup the
2102   // group should have the destroyed bit set before waiters are notified).
2103   ensure_join(this);
2104   assert(!this->has_pending_exception(), "ensure_join should have cleared");
2105 
2106   if (log_is_enabled(Debug, os, thread, timer)) {
2107     _timer_exit_phase2.stop();
2108     _timer_exit_phase3.start();
2109   }
2110   // 6282335 JNI DetachCurrentThread spec states that all Java monitors
2111   // held by this thread must be released. The spec does not distinguish
2112   // between JNI-acquired and regular Java monitors. We can only see
2113   // regular Java monitors here if monitor enter-exit matching is broken.
2114   //
2115   // ensure_join() ignores IllegalThreadStateExceptions, and so does
2116   // ObjectSynchronizer::release_monitors_owned_by_thread().
2117   if (exit_type == jni_detach) {
2118     // Sanity check even though JNI DetachCurrentThread() would have
2119     // returned JNI_ERR if there was a Java frame. JavaThread exit
2120     // should be done executing Java code by the time we get here.
2121     assert(!this->has_last_Java_frame(),
2122            "should not have a Java frame when detaching or exiting");
2123     ObjectSynchronizer::release_monitors_owned_by_thread(this);
2124     assert(!this->has_pending_exception(), "release_monitors should have cleared");
2125   }
2126 
2127   // These things needs to be done while we are still a Java Thread. Make sure that thread
2128   // is in a consistent state, in case GC happens
2129   JFR_ONLY(Jfr::on_thread_exit(this);)
2130 
2131   if (active_handles() != NULL) {
2132     JNIHandleBlock* block = active_handles();
2133     set_active_handles(NULL);
2134     JNIHandleBlock::release_block(block);
2135   }
2136 
2137   if (free_handle_block() != NULL) {
2138     JNIHandleBlock* block = free_handle_block();
2139     set_free_handle_block(NULL);
2140     JNIHandleBlock::release_block(block);
2141   }
2142 
2143   // These have to be removed while this is still a valid thread.
2144   remove_stack_guard_pages();
2145 
2146   if (UseTLAB) {
2147     tlab().retire();
2148   }
2149 
2150   if (JvmtiEnv::environments_might_exist()) {
2151     JvmtiExport::cleanup_thread(this);
2152   }
2153 
2154   // We must flush any deferred card marks and other various GC barrier
2155   // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer)
2156   // before removing a thread from the list of active threads.
2157   BarrierSet::barrier_set()->on_thread_detach(this);
2158 
2159   log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
2160     exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
2161     os::current_thread_id());
2162 
2163   if (log_is_enabled(Debug, os, thread, timer)) {
2164     _timer_exit_phase3.stop();
2165     _timer_exit_phase4.start();
2166   }
2167   // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
2168   Threads::remove(this, daemon);
2169 
2170   if (log_is_enabled(Debug, os, thread, timer)) {
2171     _timer_exit_phase4.stop();
2172     ResourceMark rm(this);
2173     log_debug(os, thread, timer)("name='%s'"
2174                                  ", exit-phase1=" JLONG_FORMAT
2175                                  ", exit-phase2=" JLONG_FORMAT
2176                                  ", exit-phase3=" JLONG_FORMAT
2177                                  ", exit-phase4=" JLONG_FORMAT,
2178                                  get_thread_name(),
2179                                  _timer_exit_phase1.milliseconds(),
2180                                  _timer_exit_phase2.milliseconds(),
2181                                  _timer_exit_phase3.milliseconds(),
2182                                  _timer_exit_phase4.milliseconds());
2183   }
2184 }
2185 
2186 void JavaThread::cleanup_failed_attach_current_thread(bool is_daemon) {
2187   if (active_handles() != NULL) {
2188     JNIHandleBlock* block = active_handles();
2189     set_active_handles(NULL);
2190     JNIHandleBlock::release_block(block);
2191   }
2192 
2193   if (free_handle_block() != NULL) {
2194     JNIHandleBlock* block = free_handle_block();
2195     set_free_handle_block(NULL);
2196     JNIHandleBlock::release_block(block);
2197   }
2198 
2199   // These have to be removed while this is still a valid thread.
2200   remove_stack_guard_pages();
2201 
2202   if (UseTLAB) {
2203     tlab().retire();
2204   }
2205 
2206   BarrierSet::barrier_set()->on_thread_detach(this);
2207 
2208   Threads::remove(this, is_daemon);
2209   this->smr_delete();
2210 }
2211 
2212 JavaThread* JavaThread::active() {
2213   Thread* thread = Thread::current();
2214   if (thread->is_Java_thread()) {
2215     return (JavaThread*) thread;
2216   } else {
2217     assert(thread->is_VM_thread(), "this must be a vm thread");
2218     VM_Operation* op = ((VMThread*) thread)->vm_operation();
2219     JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2220     assert(ret->is_Java_thread(), "must be a Java thread");
2221     return ret;
2222   }
2223 }
2224 
2225 bool JavaThread::is_lock_owned(address adr) const {
2226   if (Thread::is_lock_owned(adr)) return true;
2227 
2228   for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2229     if (chunk->contains(adr)) return true;
2230   }
2231 
2232   return false;
2233 }
2234 
2235 
2236 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2237   chunk->set_next(monitor_chunks());
2238   set_monitor_chunks(chunk);
2239 }
2240 
2241 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2242   guarantee(monitor_chunks() != NULL, "must be non empty");
2243   if (monitor_chunks() == chunk) {
2244     set_monitor_chunks(chunk->next());
2245   } else {
2246     MonitorChunk* prev = monitor_chunks();
2247     while (prev->next() != chunk) prev = prev->next();
2248     prev->set_next(chunk->next());
2249   }
2250 }
2251 
2252 // JVM support.
2253 
2254 // Note: this function shouldn't block if it's called in
2255 // _thread_in_native_trans state (such as from
2256 // check_special_condition_for_native_trans()).
2257 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2258 
2259   if (has_last_Java_frame() && has_async_condition()) {
2260     // If we are at a polling page safepoint (not a poll return)
2261     // then we must defer async exception because live registers
2262     // will be clobbered by the exception path. Poll return is
2263     // ok because the call we a returning from already collides
2264     // with exception handling registers and so there is no issue.
2265     // (The exception handling path kills call result registers but
2266     //  this is ok since the exception kills the result anyway).
2267 
2268     if (is_at_poll_safepoint()) {
2269       // if the code we are returning to has deoptimized we must defer
2270       // the exception otherwise live registers get clobbered on the
2271       // exception path before deoptimization is able to retrieve them.
2272       //
2273       RegisterMap map(this, false);
2274       frame caller_fr = last_frame().sender(&map);
2275       assert(caller_fr.is_compiled_frame(), "what?");
2276       if (caller_fr.is_deoptimized_frame()) {
2277         log_info(exceptions)("deferred async exception at compiled safepoint");
2278         return;
2279       }
2280     }
2281   }
2282 
2283   JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2284   if (condition == _no_async_condition) {
2285     // Conditions have changed since has_special_runtime_exit_condition()
2286     // was called:
2287     // - if we were here only because of an external suspend request,
2288     //   then that was taken care of above (or cancelled) so we are done
2289     // - if we were here because of another async request, then it has
2290     //   been cleared between the has_special_runtime_exit_condition()
2291     //   and now so again we are done
2292     return;
2293   }
2294 
2295   // Check for pending async. exception
2296   if (_pending_async_exception != NULL) {
2297     // Only overwrite an already pending exception, if it is not a threadDeath.
2298     if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2299 
2300       // We cannot call Exceptions::_throw(...) here because we cannot block
2301       set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2302 
2303       LogTarget(Info, exceptions) lt;
2304       if (lt.is_enabled()) {
2305         ResourceMark rm;
2306         LogStream ls(lt);
2307         ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2308           if (has_last_Java_frame()) {
2309             frame f = last_frame();
2310            ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2311           }
2312         ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2313       }
2314       _pending_async_exception = NULL;
2315       clear_has_async_exception();
2316     }
2317   }
2318 
2319   if (check_unsafe_error &&
2320       condition == _async_unsafe_access_error && !has_pending_exception()) {
2321     condition = _no_async_condition;  // done
2322     switch (thread_state()) {
2323     case _thread_in_vm: {
2324       JavaThread* THREAD = this;
2325       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2326     }
2327     case _thread_in_native: {
2328       ThreadInVMfromNative tiv(this);
2329       JavaThread* THREAD = this;
2330       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2331     }
2332     case _thread_in_Java: {
2333       ThreadInVMfromJava tiv(this);
2334       JavaThread* THREAD = this;
2335       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2336     }
2337     default:
2338       ShouldNotReachHere();
2339     }
2340   }
2341 
2342   assert(condition == _no_async_condition || has_pending_exception() ||
2343          (!check_unsafe_error && condition == _async_unsafe_access_error),
2344          "must have handled the async condition, if no exception");
2345 }
2346 
2347 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2348   //
2349   // Check for pending external suspend.
2350   // If JNIEnv proxies are allowed, don't self-suspend if the target
2351   // thread is not the current thread. In older versions of jdbx, jdbx
2352   // threads could call into the VM with another thread's JNIEnv so we
2353   // can be here operating on behalf of a suspended thread (4432884).
2354   bool do_self_suspend = is_external_suspend_with_lock();
2355   if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2356     frame_anchor()->make_walkable(this);
2357     java_suspend_self_with_safepoint_check();
2358   }
2359 
2360   // We might be here for reasons in addition to the self-suspend request
2361   // so check for other async requests.
2362   if (check_asyncs) {
2363     check_and_handle_async_exceptions();
2364   }
2365 
2366   JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);)
2367 }
2368 
2369 void JavaThread::send_thread_stop(oop java_throwable)  {
2370   assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2371   assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2372   assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2373 
2374   // Do not throw asynchronous exceptions against the compiler thread
2375   // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2376   if (!can_call_java()) return;
2377 
2378   {
2379     // Actually throw the Throwable against the target Thread - however
2380     // only if there is no thread death exception installed already.
2381     if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2382       // If the topmost frame is a runtime stub, then we are calling into
2383       // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2384       // must deoptimize the caller before continuing, as the compiled  exception handler table
2385       // may not be valid
2386       if (has_last_Java_frame()) {
2387         frame f = last_frame();
2388         if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2389           // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2390           RegisterMap reg_map(this, UseBiasedLocking);
2391           frame compiled_frame = f.sender(&reg_map);
2392           if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2393             Deoptimization::deoptimize(this, compiled_frame, &reg_map);
2394           }
2395         }
2396       }
2397 
2398       // Set async. pending exception in thread.
2399       set_pending_async_exception(java_throwable);
2400 
2401       if (log_is_enabled(Info, exceptions)) {
2402          ResourceMark rm;
2403         log_info(exceptions)("Pending Async. exception installed of type: %s",
2404                              InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2405       }
2406       // for AbortVMOnException flag
2407       Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2408     }
2409   }
2410 
2411 
2412   // Interrupt thread so it will wake up from a potential wait()
2413   Thread::interrupt(this);
2414 }
2415 
2416 // External suspension mechanism.
2417 //
2418 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2419 // to any VM_locks and it is at a transition
2420 // Self-suspension will happen on the transition out of the vm.
2421 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2422 //
2423 // Guarantees on return:
2424 //   + Target thread will not execute any new bytecode (that's why we need to
2425 //     force a safepoint)
2426 //   + Target thread will not enter any new monitors
2427 //
2428 void JavaThread::java_suspend() {
2429   ThreadsListHandle tlh;
2430   if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) {
2431     return;
2432   }
2433 
2434   { MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2435     if (!is_external_suspend()) {
2436       // a racing resume has cancelled us; bail out now
2437       return;
2438     }
2439 
2440     // suspend is done
2441     uint32_t debug_bits = 0;
2442     // Warning: is_ext_suspend_completed() may temporarily drop the
2443     // SR_lock to allow the thread to reach a stable thread state if
2444     // it is currently in a transient thread state.
2445     if (is_ext_suspend_completed(false /* !called_by_wait */,
2446                                  SuspendRetryDelay, &debug_bits)) {
2447       return;
2448     }
2449   }
2450 
2451   if (Thread::current() == this) {
2452     // Safely self-suspend.
2453     // If we don't do this explicitly it will implicitly happen
2454     // before we transition back to Java, and on some other thread-state
2455     // transition paths, but not as we exit a JVM TI SuspendThread call.
2456     // As SuspendThread(current) must not return (until resumed) we must
2457     // self-suspend here.
2458     ThreadBlockInVM tbivm(this);
2459     java_suspend_self();
2460   } else {
2461     VM_ThreadSuspend vm_suspend;
2462     VMThread::execute(&vm_suspend);
2463   }
2464 }
2465 
2466 // Part II of external suspension.
2467 // A JavaThread self suspends when it detects a pending external suspend
2468 // request. This is usually on transitions. It is also done in places
2469 // where continuing to the next transition would surprise the caller,
2470 // e.g., monitor entry.
2471 //
2472 // Returns the number of times that the thread self-suspended.
2473 //
2474 // Note: DO NOT call java_suspend_self() when you just want to block current
2475 //       thread. java_suspend_self() is the second stage of cooperative
2476 //       suspension for external suspend requests and should only be used
2477 //       to complete an external suspend request.
2478 //
2479 int JavaThread::java_suspend_self() {
2480   assert(thread_state() == _thread_blocked, "wrong state for java_suspend_self()");
2481   int ret = 0;
2482 
2483   // we are in the process of exiting so don't suspend
2484   if (is_exiting()) {
2485     clear_external_suspend();
2486     return ret;
2487   }
2488 
2489   assert(_anchor.walkable() ||
2490          (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2491          "must have walkable stack");
2492 
2493   MonitorLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2494 
2495   assert(!this->is_ext_suspended(),
2496          "a thread trying to self-suspend should not already be suspended");
2497 
2498   if (this->is_suspend_equivalent()) {
2499     // If we are self-suspending as a result of the lifting of a
2500     // suspend equivalent condition, then the suspend_equivalent
2501     // flag is not cleared until we set the ext_suspended flag so
2502     // that wait_for_ext_suspend_completion() returns consistent
2503     // results.
2504     this->clear_suspend_equivalent();
2505   }
2506 
2507   // A racing resume may have cancelled us before we grabbed SR_lock
2508   // above. Or another external suspend request could be waiting for us
2509   // by the time we return from SR_lock()->wait(). The thread
2510   // that requested the suspension may already be trying to walk our
2511   // stack and if we return now, we can change the stack out from under
2512   // it. This would be a "bad thing (TM)" and cause the stack walker
2513   // to crash. We stay self-suspended until there are no more pending
2514   // external suspend requests.
2515   while (is_external_suspend()) {
2516     ret++;
2517     this->set_ext_suspended();
2518 
2519     // _ext_suspended flag is cleared by java_resume()
2520     while (is_ext_suspended()) {
2521       ml.wait();
2522     }
2523   }
2524   return ret;
2525 }
2526 
2527 // Helper routine to set up the correct thread state before calling java_suspend_self.
2528 // This is called when regular thread-state transition helpers can't be used because
2529 // we can be in various states, in particular _thread_in_native_trans.
2530 // Because this thread is external suspended the safepoint code will count it as at
2531 // a safepoint, regardless of what its actual current thread-state is. But
2532 // is_ext_suspend_completed() may be waiting to see a thread transition from
2533 // _thread_in_native_trans to _thread_blocked. So we set the thread state directly
2534 // to _thread_blocked. The problem with setting thread state directly is that a
2535 // safepoint could happen just after java_suspend_self() returns after being resumed,
2536 // and the VM thread will see the _thread_blocked state. So we must check for a safepoint
2537 // after restoring the state to make sure we won't leave while a safepoint is in progress.
2538 // However, not all initial-states are allowed when performing a safepoint check, as we
2539 // should never be blocking at a safepoint whilst in those states. Of these 'bad' states
2540 // only _thread_in_native is possible when executing this code (based on our two callers).
2541 // A thread that is _thread_in_native is already safepoint-safe and so it doesn't matter
2542 // whether the VMThread sees the _thread_blocked state, or the _thread_in_native state,
2543 // and so we don't need the explicit safepoint check.
2544 
2545 void JavaThread::java_suspend_self_with_safepoint_check() {
2546   assert(this == Thread::current(), "invariant");
2547   JavaThreadState state = thread_state();
2548   set_thread_state(_thread_blocked);
2549   java_suspend_self();
2550   set_thread_state_fence(state);
2551   // Since we are not using a regular thread-state transition helper here,
2552   // we must manually emit the instruction barrier after leaving a safe state.
2553   OrderAccess::cross_modify_fence();
2554   if (state != _thread_in_native) {
2555     SafepointMechanism::block_if_requested(this);
2556   }
2557 }
2558 
2559 #ifdef ASSERT
2560 // Verify the JavaThread has not yet been published in the Threads::list, and
2561 // hence doesn't need protection from concurrent access at this stage.
2562 void JavaThread::verify_not_published() {
2563   // Cannot create a ThreadsListHandle here and check !tlh.includes(this)
2564   // since an unpublished JavaThread doesn't participate in the
2565   // Thread-SMR protocol for keeping a ThreadsList alive.
2566   assert(!on_thread_list(), "JavaThread shouldn't have been published yet!");
2567 }
2568 #endif
2569 
2570 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2571 // progress or when _suspend_flags is non-zero.
2572 // Current thread needs to self-suspend if there is a suspend request and/or
2573 // block if a safepoint is in progress.
2574 // Async exception ISN'T checked.
2575 // Note only the ThreadInVMfromNative transition can call this function
2576 // directly and when thread state is _thread_in_native_trans
2577 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2578   assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2579 
2580   JavaThread *curJT = JavaThread::current();
2581   bool do_self_suspend = thread->is_external_suspend();
2582 
2583   assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2584 
2585   // If JNIEnv proxies are allowed, don't self-suspend if the target
2586   // thread is not the current thread. In older versions of jdbx, jdbx
2587   // threads could call into the VM with another thread's JNIEnv so we
2588   // can be here operating on behalf of a suspended thread (4432884).
2589   if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2590     thread->java_suspend_self_with_safepoint_check();
2591   } else {
2592     SafepointMechanism::block_if_requested(curJT);
2593   }
2594 
2595   JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(thread);)
2596 }
2597 
2598 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2599 // progress or when _suspend_flags is non-zero.
2600 // Current thread needs to self-suspend if there is a suspend request and/or
2601 // block if a safepoint is in progress.
2602 // Also check for pending async exception (not including unsafe access error).
2603 // Note only the native==>VM/Java barriers can call this function and when
2604 // thread state is _thread_in_native_trans.
2605 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2606   check_safepoint_and_suspend_for_native_trans(thread);
2607 
2608   if (thread->has_async_exception()) {
2609     // We are in _thread_in_native_trans state, don't handle unsafe
2610     // access error since that may block.
2611     thread->check_and_handle_async_exceptions(false);
2612   }
2613 }
2614 
2615 // This is a variant of the normal
2616 // check_special_condition_for_native_trans with slightly different
2617 // semantics for use by critical native wrappers.  It does all the
2618 // normal checks but also performs the transition back into
2619 // thread_in_Java state.  This is required so that critical natives
2620 // can potentially block and perform a GC if they are the last thread
2621 // exiting the GCLocker.
2622 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2623   check_special_condition_for_native_trans(thread);
2624 
2625   // Finish the transition
2626   thread->set_thread_state(_thread_in_Java);
2627 
2628   if (thread->do_critical_native_unlock()) {
2629     ThreadInVMfromJavaNoAsyncException tiv(thread);
2630     GCLocker::unlock_critical(thread);
2631     thread->clear_critical_native_unlock();
2632   }
2633 }
2634 
2635 // We need to guarantee the Threads_lock here, since resumes are not
2636 // allowed during safepoint synchronization
2637 // Can only resume from an external suspension
2638 void JavaThread::java_resume() {
2639   assert_locked_or_safepoint(Threads_lock);
2640 
2641   // Sanity check: thread is gone, has started exiting or the thread
2642   // was not externally suspended.
2643   ThreadsListHandle tlh;
2644   if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) {
2645     return;
2646   }
2647 
2648   MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2649 
2650   clear_external_suspend();
2651 
2652   if (is_ext_suspended()) {
2653     clear_ext_suspended();
2654     SR_lock()->notify_all();
2655   }
2656 }
2657 
2658 size_t JavaThread::_stack_red_zone_size = 0;
2659 size_t JavaThread::_stack_yellow_zone_size = 0;
2660 size_t JavaThread::_stack_reserved_zone_size = 0;
2661 size_t JavaThread::_stack_shadow_zone_size = 0;
2662 
2663 void JavaThread::create_stack_guard_pages() {
2664   if (!os::uses_stack_guard_pages() ||
2665       _stack_guard_state != stack_guard_unused ||
2666       (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) {
2667       log_info(os, thread)("Stack guard page creation for thread "
2668                            UINTX_FORMAT " disabled", os::current_thread_id());
2669     return;
2670   }
2671   address low_addr = stack_end();
2672   size_t len = stack_guard_zone_size();
2673 
2674   assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2675   assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2676 
2677   int must_commit = os::must_commit_stack_guard_pages();
2678   // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2679 
2680   if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2681     log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2682     return;
2683   }
2684 
2685   if (os::guard_memory((char *) low_addr, len)) {
2686     _stack_guard_state = stack_guard_enabled;
2687   } else {
2688     log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2689       PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2690     if (os::uncommit_memory((char *) low_addr, len)) {
2691       log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2692     }
2693     return;
2694   }
2695 
2696   log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2697     PTR_FORMAT "-" PTR_FORMAT ".",
2698     os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2699 }
2700 
2701 void JavaThread::remove_stack_guard_pages() {
2702   assert(Thread::current() == this, "from different thread");
2703   if (_stack_guard_state == stack_guard_unused) return;
2704   address low_addr = stack_end();
2705   size_t len = stack_guard_zone_size();
2706 
2707   if (os::must_commit_stack_guard_pages()) {
2708     if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2709       _stack_guard_state = stack_guard_unused;
2710     } else {
2711       log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2712         PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2713       return;
2714     }
2715   } else {
2716     if (_stack_guard_state == stack_guard_unused) return;
2717     if (os::unguard_memory((char *) low_addr, len)) {
2718       _stack_guard_state = stack_guard_unused;
2719     } else {
2720       log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2721         PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2722       return;
2723     }
2724   }
2725 
2726   log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2727     PTR_FORMAT "-" PTR_FORMAT ".",
2728     os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2729 }
2730 
2731 void JavaThread::enable_stack_reserved_zone() {
2732   assert(_stack_guard_state == stack_guard_reserved_disabled, "inconsistent state");
2733 
2734   // The base notation is from the stack's point of view, growing downward.
2735   // We need to adjust it to work correctly with guard_memory()
2736   address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2737 
2738   guarantee(base < stack_base(),"Error calculating stack reserved zone");
2739   guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2740 
2741   if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2742     _stack_guard_state = stack_guard_enabled;
2743   } else {
2744     warning("Attempt to guard stack reserved zone failed.");
2745   }
2746   enable_register_stack_guard();
2747 }
2748 
2749 void JavaThread::disable_stack_reserved_zone() {
2750   assert(_stack_guard_state == stack_guard_enabled, "inconsistent state");
2751 
2752   // Simply return if called for a thread that does not use guard pages.
2753   if (_stack_guard_state != stack_guard_enabled) return;
2754 
2755   // The base notation is from the stack's point of view, growing downward.
2756   // We need to adjust it to work correctly with guard_memory()
2757   address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2758 
2759   if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2760     _stack_guard_state = stack_guard_reserved_disabled;
2761   } else {
2762     warning("Attempt to unguard stack reserved zone failed.");
2763   }
2764   disable_register_stack_guard();
2765 }
2766 
2767 void JavaThread::enable_stack_yellow_reserved_zone() {
2768   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2769   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2770 
2771   // The base notation is from the stacks point of view, growing downward.
2772   // We need to adjust it to work correctly with guard_memory()
2773   address base = stack_red_zone_base();
2774 
2775   guarantee(base < stack_base(), "Error calculating stack yellow zone");
2776   guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2777 
2778   if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2779     _stack_guard_state = stack_guard_enabled;
2780   } else {
2781     warning("Attempt to guard stack yellow zone failed.");
2782   }
2783   enable_register_stack_guard();
2784 }
2785 
2786 void JavaThread::disable_stack_yellow_reserved_zone() {
2787   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2788   assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2789 
2790   // Simply return if called for a thread that does not use guard pages.
2791   if (_stack_guard_state == stack_guard_unused) return;
2792 
2793   // The base notation is from the stacks point of view, growing downward.
2794   // We need to adjust it to work correctly with guard_memory()
2795   address base = stack_red_zone_base();
2796 
2797   if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2798     _stack_guard_state = stack_guard_yellow_reserved_disabled;
2799   } else {
2800     warning("Attempt to unguard stack yellow zone failed.");
2801   }
2802   disable_register_stack_guard();
2803 }
2804 
2805 void JavaThread::enable_stack_red_zone() {
2806   // The base notation is from the stacks point of view, growing downward.
2807   // We need to adjust it to work correctly with guard_memory()
2808   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2809   address base = stack_red_zone_base() - stack_red_zone_size();
2810 
2811   guarantee(base < stack_base(), "Error calculating stack red zone");
2812   guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2813 
2814   if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2815     warning("Attempt to guard stack red zone failed.");
2816   }
2817 }
2818 
2819 void JavaThread::disable_stack_red_zone() {
2820   // The base notation is from the stacks point of view, growing downward.
2821   // We need to adjust it to work correctly with guard_memory()
2822   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2823   address base = stack_red_zone_base() - stack_red_zone_size();
2824   if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2825     warning("Attempt to unguard stack red zone failed.");
2826   }
2827 }
2828 
2829 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2830   // ignore is there is no stack
2831   if (!has_last_Java_frame()) return;
2832   // traverse the stack frames. Starts from top frame.
2833   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2834     frame* fr = fst.current();
2835     f(fr, fst.register_map());
2836   }
2837 }
2838 
2839 
2840 #ifndef PRODUCT
2841 // Deoptimization
2842 // Function for testing deoptimization
2843 void JavaThread::deoptimize() {
2844   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2845   StackFrameStream fst(this, UseBiasedLocking);
2846   bool deopt = false;           // Dump stack only if a deopt actually happens.
2847   bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2848   // Iterate over all frames in the thread and deoptimize
2849   for (; !fst.is_done(); fst.next()) {
2850     if (fst.current()->can_be_deoptimized()) {
2851 
2852       if (only_at) {
2853         // Deoptimize only at particular bcis.  DeoptimizeOnlyAt
2854         // consists of comma or carriage return separated numbers so
2855         // search for the current bci in that string.
2856         address pc = fst.current()->pc();
2857         nmethod* nm =  (nmethod*) fst.current()->cb();
2858         ScopeDesc* sd = nm->scope_desc_at(pc);
2859         char buffer[8];
2860         jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2861         size_t len = strlen(buffer);
2862         const char * found = strstr(DeoptimizeOnlyAt, buffer);
2863         while (found != NULL) {
2864           if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2865               (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2866             // Check that the bci found is bracketed by terminators.
2867             break;
2868           }
2869           found = strstr(found + 1, buffer);
2870         }
2871         if (!found) {
2872           continue;
2873         }
2874       }
2875 
2876       if (DebugDeoptimization && !deopt) {
2877         deopt = true; // One-time only print before deopt
2878         tty->print_cr("[BEFORE Deoptimization]");
2879         trace_frames();
2880         trace_stack();
2881       }
2882       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2883     }
2884   }
2885 
2886   if (DebugDeoptimization && deopt) {
2887     tty->print_cr("[AFTER Deoptimization]");
2888     trace_frames();
2889   }
2890 }
2891 
2892 
2893 // Make zombies
2894 void JavaThread::make_zombies() {
2895   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2896     if (fst.current()->can_be_deoptimized()) {
2897       // it is a Java nmethod
2898       nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2899       nm->make_not_entrant();
2900     }
2901   }
2902 }
2903 #endif // PRODUCT
2904 
2905 
2906 void JavaThread::deoptimize_marked_methods(bool in_handshake) {
2907   if (!has_last_Java_frame()) return;
2908   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2909   StackFrameStream fst(this, UseBiasedLocking);
2910   for (; !fst.is_done(); fst.next()) {
2911     if (fst.current()->should_be_deoptimized()) {
2912       Deoptimization::deoptimize(this, *fst.current(), fst.register_map(), in_handshake);
2913     }
2914   }
2915 }
2916 
2917 // If the caller is a NamedThread, then remember, in the current scope,
2918 // the given JavaThread in its _processed_thread field.
2919 class RememberProcessedThread: public StackObj {
2920   NamedThread* _cur_thr;
2921  public:
2922   RememberProcessedThread(JavaThread* jthr) {
2923     Thread* thread = Thread::current();
2924     if (thread->is_Named_thread()) {
2925       _cur_thr = (NamedThread *)thread;
2926       _cur_thr->set_processed_thread(jthr);
2927     } else {
2928       _cur_thr = NULL;
2929     }
2930   }
2931 
2932   ~RememberProcessedThread() {
2933     if (_cur_thr) {
2934       _cur_thr->set_processed_thread(NULL);
2935     }
2936   }
2937 };
2938 
2939 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2940   // Verify that the deferred card marks have been flushed.
2941   assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2942 
2943   // Traverse the GCHandles
2944   Thread::oops_do(f, cf);
2945 
2946   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2947          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2948 
2949   if (has_last_Java_frame()) {
2950     // Record JavaThread to GC thread
2951     RememberProcessedThread rpt(this);
2952 
2953     // traverse the registered growable array
2954     if (_array_for_gc != NULL) {
2955       for (int index = 0; index < _array_for_gc->length(); index++) {
2956         f->do_oop(_array_for_gc->adr_at(index));
2957       }
2958     }
2959 
2960     // Traverse the monitor chunks
2961     for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2962       chunk->oops_do(f);
2963     }
2964 
2965     // Traverse the execution stack
2966     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2967       fst.current()->oops_do(f, cf, fst.register_map());
2968     }
2969   }
2970 
2971   // callee_target is never live across a gc point so NULL it here should
2972   // it still contain a methdOop.
2973 
2974   set_callee_target(NULL);
2975 
2976   assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2977   // If we have deferred set_locals there might be oops waiting to be
2978   // written
2979   GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2980   if (list != NULL) {
2981     for (int i = 0; i < list->length(); i++) {
2982       list->at(i)->oops_do(f);
2983     }
2984   }
2985 
2986   // Traverse instance variables at the end since the GC may be moving things
2987   // around using this function
2988   f->do_oop((oop*) &_threadObj);
2989   f->do_oop((oop*) &_vm_result);
2990   f->do_oop((oop*) &_exception_oop);
2991   f->do_oop((oop*) &_pending_async_exception);
2992 
2993   if (jvmti_thread_state() != NULL) {
2994     jvmti_thread_state()->oops_do(f);
2995   }
2996 }
2997 
2998 #ifdef ASSERT
2999 void JavaThread::verify_states_for_handshake() {
3000   // This checks that the thread has a correct frame state during a handshake.
3001   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
3002          (has_last_Java_frame() && java_call_counter() > 0),
3003          "unexpected frame info: has_last_frame=%d, java_call_counter=%d",
3004          has_last_Java_frame(), java_call_counter());
3005 }
3006 #endif
3007 
3008 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
3009   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
3010          (has_last_Java_frame() && java_call_counter() > 0),
3011          "unexpected frame info: has_last_frame=%d, java_call_counter=%d",
3012          has_last_Java_frame(), java_call_counter());
3013 
3014   if (has_last_Java_frame()) {
3015     // Traverse the execution stack
3016     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3017       fst.current()->nmethods_do(cf);
3018     }
3019   }
3020 }
3021 
3022 void JavaThread::metadata_do(MetadataClosure* f) {
3023   if (has_last_Java_frame()) {
3024     // Traverse the execution stack to call f() on the methods in the stack
3025     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3026       fst.current()->metadata_do(f);
3027     }
3028   } else if (is_Compiler_thread()) {
3029     // need to walk ciMetadata in current compile tasks to keep alive.
3030     CompilerThread* ct = (CompilerThread*)this;
3031     if (ct->env() != NULL) {
3032       ct->env()->metadata_do(f);
3033     }
3034     CompileTask* task = ct->task();
3035     if (task != NULL) {
3036       task->metadata_do(f);
3037     }
3038   }
3039 }
3040 
3041 // Printing
3042 const char* _get_thread_state_name(JavaThreadState _thread_state) {
3043   switch (_thread_state) {
3044   case _thread_uninitialized:     return "_thread_uninitialized";
3045   case _thread_new:               return "_thread_new";
3046   case _thread_new_trans:         return "_thread_new_trans";
3047   case _thread_in_native:         return "_thread_in_native";
3048   case _thread_in_native_trans:   return "_thread_in_native_trans";
3049   case _thread_in_vm:             return "_thread_in_vm";
3050   case _thread_in_vm_trans:       return "_thread_in_vm_trans";
3051   case _thread_in_Java:           return "_thread_in_Java";
3052   case _thread_in_Java_trans:     return "_thread_in_Java_trans";
3053   case _thread_blocked:           return "_thread_blocked";
3054   case _thread_blocked_trans:     return "_thread_blocked_trans";
3055   default:                        return "unknown thread state";
3056   }
3057 }
3058 
3059 #ifndef PRODUCT
3060 void JavaThread::print_thread_state_on(outputStream *st) const {
3061   st->print_cr("   JavaThread state: %s", _get_thread_state_name(_thread_state));
3062 };
3063 void JavaThread::print_thread_state() const {
3064   print_thread_state_on(tty);
3065 }
3066 #endif // PRODUCT
3067 
3068 // Called by Threads::print() for VM_PrintThreads operation
3069 void JavaThread::print_on(outputStream *st, bool print_extended_info) const {
3070   st->print_raw("\"");
3071   st->print_raw(get_thread_name());
3072   st->print_raw("\" ");
3073   oop thread_oop = threadObj();
3074   if (thread_oop != NULL) {
3075     st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
3076     if (java_lang_Thread::is_daemon(thread_oop))  st->print("daemon ");
3077     st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
3078   }
3079   Thread::print_on(st, print_extended_info);
3080   // print guess for valid stack memory region (assume 4K pages); helps lock debugging
3081   st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
3082   if (thread_oop != NULL) {
3083     st->print_cr("   java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
3084   }
3085 #ifndef PRODUCT
3086   _safepoint_state->print_on(st);
3087 #endif // PRODUCT
3088   if (is_Compiler_thread()) {
3089     CompileTask *task = ((CompilerThread*)this)->task();
3090     if (task != NULL) {
3091       st->print("   Compiling: ");
3092       task->print(st, NULL, true, false);
3093     } else {
3094       st->print("   No compile task");
3095     }
3096     st->cr();
3097   }
3098 }
3099 
3100 void JavaThread::print() const { print_on(tty); }
3101 
3102 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
3103   st->print("%s", get_thread_name_string(buf, buflen));
3104 }
3105 
3106 // Called by fatal error handler. The difference between this and
3107 // JavaThread::print() is that we can't grab lock or allocate memory.
3108 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
3109   st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
3110   oop thread_obj = threadObj();
3111   if (thread_obj != NULL) {
3112     if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
3113   }
3114   st->print(" [");
3115   st->print("%s", _get_thread_state_name(_thread_state));
3116   if (osthread()) {
3117     st->print(", id=%d", osthread()->thread_id());
3118   }
3119   st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
3120             p2i(stack_end()), p2i(stack_base()));
3121   st->print("]");
3122 
3123   ThreadsSMRSupport::print_info_on(this, st);
3124   return;
3125 }
3126 
3127 // Verification
3128 
3129 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
3130 
3131 void JavaThread::verify() {
3132   // Verify oops in the thread.
3133   oops_do(&VerifyOopClosure::verify_oop, NULL);
3134 
3135   // Verify the stack frames.
3136   frames_do(frame_verify);
3137 }
3138 
3139 // CR 6300358 (sub-CR 2137150)
3140 // Most callers of this method assume that it can't return NULL but a
3141 // thread may not have a name whilst it is in the process of attaching to
3142 // the VM - see CR 6412693, and there are places where a JavaThread can be
3143 // seen prior to having it's threadObj set (eg JNI attaching threads and
3144 // if vm exit occurs during initialization). These cases can all be accounted
3145 // for such that this method never returns NULL.
3146 const char* JavaThread::get_thread_name() const {
3147 #ifdef ASSERT
3148   // early safepoints can hit while current thread does not yet have TLS
3149   if (!SafepointSynchronize::is_at_safepoint()) {
3150     Thread *cur = Thread::current();
3151     if (!(cur->is_Java_thread() && cur == this)) {
3152       // Current JavaThreads are allowed to get their own name without
3153       // the Threads_lock.
3154       assert_locked_or_safepoint(Threads_lock);
3155     }
3156   }
3157 #endif // ASSERT
3158   return get_thread_name_string();
3159 }
3160 
3161 // Returns a non-NULL representation of this thread's name, or a suitable
3162 // descriptive string if there is no set name
3163 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3164   const char* name_str;
3165   oop thread_obj = threadObj();
3166   if (thread_obj != NULL) {
3167     oop name = java_lang_Thread::name(thread_obj);
3168     if (name != NULL) {
3169       if (buf == NULL) {
3170         name_str = java_lang_String::as_utf8_string(name);
3171       } else {
3172         name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3173       }
3174     } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3175       name_str = "<no-name - thread is attaching>";
3176     } else {
3177       name_str = Thread::name();
3178     }
3179   } else {
3180     name_str = Thread::name();
3181   }
3182   assert(name_str != NULL, "unexpected NULL thread name");
3183   return name_str;
3184 }
3185 
3186 
3187 const char* JavaThread::get_threadgroup_name() const {
3188   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3189   oop thread_obj = threadObj();
3190   if (thread_obj != NULL) {
3191     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3192     if (thread_group != NULL) {
3193       // ThreadGroup.name can be null
3194       return java_lang_ThreadGroup::name(thread_group);
3195     }
3196   }
3197   return NULL;
3198 }
3199 
3200 const char* JavaThread::get_parent_name() const {
3201   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3202   oop thread_obj = threadObj();
3203   if (thread_obj != NULL) {
3204     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3205     if (thread_group != NULL) {
3206       oop parent = java_lang_ThreadGroup::parent(thread_group);
3207       if (parent != NULL) {
3208         // ThreadGroup.name can be null
3209         return java_lang_ThreadGroup::name(parent);
3210       }
3211     }
3212   }
3213   return NULL;
3214 }
3215 
3216 ThreadPriority JavaThread::java_priority() const {
3217   oop thr_oop = threadObj();
3218   if (thr_oop == NULL) return NormPriority; // Bootstrapping
3219   ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3220   assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3221   return priority;
3222 }
3223 
3224 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3225 
3226   assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3227   // Link Java Thread object <-> C++ Thread
3228 
3229   // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3230   // and put it into a new Handle.  The Handle "thread_oop" can then
3231   // be used to pass the C++ thread object to other methods.
3232 
3233   // Set the Java level thread object (jthread) field of the
3234   // new thread (a JavaThread *) to C++ thread object using the
3235   // "thread_oop" handle.
3236 
3237   // Set the thread field (a JavaThread *) of the
3238   // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3239 
3240   Handle thread_oop(Thread::current(),
3241                     JNIHandles::resolve_non_null(jni_thread));
3242   assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3243          "must be initialized");
3244   set_threadObj(thread_oop());
3245   java_lang_Thread::set_thread(thread_oop(), this);
3246 
3247   if (prio == NoPriority) {
3248     prio = java_lang_Thread::priority(thread_oop());
3249     assert(prio != NoPriority, "A valid priority should be present");
3250   }
3251 
3252   // Push the Java priority down to the native thread; needs Threads_lock
3253   Thread::set_priority(this, prio);
3254 
3255   // Add the new thread to the Threads list and set it in motion.
3256   // We must have threads lock in order to call Threads::add.
3257   // It is crucial that we do not block before the thread is
3258   // added to the Threads list for if a GC happens, then the java_thread oop
3259   // will not be visited by GC.
3260   Threads::add(this);
3261 }
3262 
3263 oop JavaThread::current_park_blocker() {
3264   // Support for JSR-166 locks
3265   oop thread_oop = threadObj();
3266   if (thread_oop != NULL) {
3267     return java_lang_Thread::park_blocker(thread_oop);
3268   }
3269   return NULL;
3270 }
3271 
3272 
3273 void JavaThread::print_stack_on(outputStream* st) {
3274   if (!has_last_Java_frame()) return;
3275   ResourceMark rm;
3276   HandleMark   hm;
3277 
3278   RegisterMap reg_map(this);
3279   vframe* start_vf = last_java_vframe(&reg_map);
3280   int count = 0;
3281   for (vframe* f = start_vf; f != NULL; f = f->sender()) {
3282     if (f->is_java_frame()) {
3283       javaVFrame* jvf = javaVFrame::cast(f);
3284       java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3285 
3286       // Print out lock information
3287       if (JavaMonitorsInStackTrace) {
3288         jvf->print_lock_info_on(st, count);
3289       }
3290     } else {
3291       // Ignore non-Java frames
3292     }
3293 
3294     // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
3295     count++;
3296     if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
3297   }
3298 }
3299 
3300 
3301 // JVMTI PopFrame support
3302 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3303   assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3304   if (in_bytes(size_in_bytes) != 0) {
3305     _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3306     _popframe_preserved_args_size = in_bytes(size_in_bytes);
3307     Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3308   }
3309 }
3310 
3311 void* JavaThread::popframe_preserved_args() {
3312   return _popframe_preserved_args;
3313 }
3314 
3315 ByteSize JavaThread::popframe_preserved_args_size() {
3316   return in_ByteSize(_popframe_preserved_args_size);
3317 }
3318 
3319 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3320   int sz = in_bytes(popframe_preserved_args_size());
3321   assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3322   return in_WordSize(sz / wordSize);
3323 }
3324 
3325 void JavaThread::popframe_free_preserved_args() {
3326   assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3327   FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3328   _popframe_preserved_args = NULL;
3329   _popframe_preserved_args_size = 0;
3330 }
3331 
3332 #ifndef PRODUCT
3333 
3334 void JavaThread::trace_frames() {
3335   tty->print_cr("[Describe stack]");
3336   int frame_no = 1;
3337   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3338     tty->print("  %d. ", frame_no++);
3339     fst.current()->print_value_on(tty, this);
3340     tty->cr();
3341   }
3342 }
3343 
3344 class PrintAndVerifyOopClosure: public OopClosure {
3345  protected:
3346   template <class T> inline void do_oop_work(T* p) {
3347     oop obj = RawAccess<>::oop_load(p);
3348     if (obj == NULL) return;
3349     tty->print(INTPTR_FORMAT ": ", p2i(p));
3350     if (oopDesc::is_oop_or_null(obj)) {
3351       if (obj->is_objArray()) {
3352         tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3353       } else {
3354         obj->print();
3355       }
3356     } else {
3357       tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3358     }
3359     tty->cr();
3360   }
3361  public:
3362   virtual void do_oop(oop* p) { do_oop_work(p); }
3363   virtual void do_oop(narrowOop* p)  { do_oop_work(p); }
3364 };
3365 
3366 
3367 static void oops_print(frame* f, const RegisterMap *map) {
3368   PrintAndVerifyOopClosure print;
3369   f->print_value();
3370   f->oops_do(&print, NULL, (RegisterMap*)map);
3371 }
3372 
3373 // Print our all the locations that contain oops and whether they are
3374 // valid or not.  This useful when trying to find the oldest frame
3375 // where an oop has gone bad since the frame walk is from youngest to
3376 // oldest.
3377 void JavaThread::trace_oops() {
3378   tty->print_cr("[Trace oops]");
3379   frames_do(oops_print);
3380 }
3381 
3382 
3383 #ifdef ASSERT
3384 // Print or validate the layout of stack frames
3385 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3386   ResourceMark rm;
3387   PRESERVE_EXCEPTION_MARK;
3388   FrameValues values;
3389   int frame_no = 0;
3390   for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3391     fst.current()->describe(values, ++frame_no);
3392     if (depth == frame_no) break;
3393   }
3394   if (validate_only) {
3395     values.validate();
3396   } else {
3397     tty->print_cr("[Describe stack layout]");
3398     values.print(this);
3399   }
3400 }
3401 #endif
3402 
3403 void JavaThread::trace_stack_from(vframe* start_vf) {
3404   ResourceMark rm;
3405   int vframe_no = 1;
3406   for (vframe* f = start_vf; f; f = f->sender()) {
3407     if (f->is_java_frame()) {
3408       javaVFrame::cast(f)->print_activation(vframe_no++);
3409     } else {
3410       f->print();
3411     }
3412     if (vframe_no > StackPrintLimit) {
3413       tty->print_cr("...<more frames>...");
3414       return;
3415     }
3416   }
3417 }
3418 
3419 
3420 void JavaThread::trace_stack() {
3421   if (!has_last_Java_frame()) return;
3422   ResourceMark rm;
3423   HandleMark   hm;
3424   RegisterMap reg_map(this);
3425   trace_stack_from(last_java_vframe(&reg_map));
3426 }
3427 
3428 
3429 #endif // PRODUCT
3430 
3431 
3432 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3433   assert(reg_map != NULL, "a map must be given");
3434   frame f = last_frame();
3435   for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3436     if (vf->is_java_frame()) return javaVFrame::cast(vf);
3437   }
3438   return NULL;
3439 }
3440 
3441 
3442 Klass* JavaThread::security_get_caller_class(int depth) {
3443   vframeStream vfst(this);
3444   vfst.security_get_caller_frame(depth);
3445   if (!vfst.at_end()) {
3446     return vfst.method()->method_holder();
3447   }
3448   return NULL;
3449 }
3450 
3451 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3452   assert(thread->is_Compiler_thread(), "must be compiler thread");
3453   CompileBroker::compiler_thread_loop();
3454 }
3455 
3456 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3457   NMethodSweeper::sweeper_loop();
3458 }
3459 
3460 // Create a CompilerThread
3461 CompilerThread::CompilerThread(CompileQueue* queue,
3462                                CompilerCounters* counters)
3463                                : JavaThread(&compiler_thread_entry) {
3464   _env   = NULL;
3465   _log   = NULL;
3466   _task  = NULL;
3467   _queue = queue;
3468   _counters = counters;
3469   _buffer_blob = NULL;
3470   _compiler = NULL;
3471 
3472   // Compiler uses resource area for compilation, let's bias it to mtCompiler
3473   resource_area()->bias_to(mtCompiler);
3474 
3475 #ifndef PRODUCT
3476   _ideal_graph_printer = NULL;
3477 #endif
3478 }
3479 
3480 CompilerThread::~CompilerThread() {
3481   // Delete objects which were allocated on heap.
3482   delete _counters;
3483 }
3484 
3485 bool CompilerThread::can_call_java() const {
3486   return _compiler != NULL && _compiler->is_jvmci();
3487 }
3488 
3489 // Create sweeper thread
3490 CodeCacheSweeperThread::CodeCacheSweeperThread()
3491 : JavaThread(&sweeper_thread_entry) {
3492   _scanned_compiled_method = NULL;
3493 }
3494 
3495 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3496   JavaThread::oops_do(f, cf);
3497   if (_scanned_compiled_method != NULL && cf != NULL) {
3498     // Safepoints can occur when the sweeper is scanning an nmethod so
3499     // process it here to make sure it isn't unloaded in the middle of
3500     // a scan.
3501     cf->do_code_blob(_scanned_compiled_method);
3502   }
3503 }
3504 
3505 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3506   JavaThread::nmethods_do(cf);
3507   if (_scanned_compiled_method != NULL && cf != NULL) {
3508     // Safepoints can occur when the sweeper is scanning an nmethod so
3509     // process it here to make sure it isn't unloaded in the middle of
3510     // a scan.
3511     cf->do_code_blob(_scanned_compiled_method);
3512   }
3513 }
3514 
3515 
3516 // ======= Threads ========
3517 
3518 // The Threads class links together all active threads, and provides
3519 // operations over all threads. It is protected by the Threads_lock,
3520 // which is also used in other global contexts like safepointing.
3521 // ThreadsListHandles are used to safely perform operations on one
3522 // or more threads without the risk of the thread exiting during the
3523 // operation.
3524 //
3525 // Note: The Threads_lock is currently more widely used than we
3526 // would like. We are actively migrating Threads_lock uses to other
3527 // mechanisms in order to reduce Threads_lock contention.
3528 
3529 int         Threads::_number_of_threads = 0;
3530 int         Threads::_number_of_non_daemon_threads = 0;
3531 int         Threads::_return_code = 0;
3532 uintx       Threads::_thread_claim_token = 1; // Never zero.
3533 size_t      JavaThread::_stack_size_at_create = 0;
3534 
3535 #ifdef ASSERT
3536 bool        Threads::_vm_complete = false;
3537 #endif
3538 
3539 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
3540   Prefetch::read((void*)addr, prefetch_interval);
3541   return *addr;
3542 }
3543 
3544 // Possibly the ugliest for loop the world has seen. C++ does not allow
3545 // multiple types in the declaration section of the for loop. In this case
3546 // we are only dealing with pointers and hence can cast them. It looks ugly
3547 // but macros are ugly and therefore it's fine to make things absurdly ugly.
3548 #define DO_JAVA_THREADS(LIST, X)                                                                                          \
3549     for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes,                           \
3550              *MACRO_list = (JavaThread*)(LIST),                                                                           \
3551              **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(),  \
3552              **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(),                                     \
3553              *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval);                 \
3554          MACRO_current_p != MACRO_end;                                                                                    \
3555          MACRO_current_p++,                                                                                               \
3556              X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval))
3557 
3558 // All JavaThreads
3559 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X)
3560 
3561 // All NonJavaThreads (i.e., every non-JavaThread in the system).
3562 void Threads::non_java_threads_do(ThreadClosure* tc) {
3563   NoSafepointVerifier nsv(!SafepointSynchronize::is_at_safepoint(), false);
3564   for (NonJavaThread::Iterator njti; !njti.end(); njti.step()) {
3565     tc->do_thread(njti.current());
3566   }
3567 }
3568 
3569 // All JavaThreads
3570 void Threads::java_threads_do(ThreadClosure* tc) {
3571   assert_locked_or_safepoint(Threads_lock);
3572   // ALL_JAVA_THREADS iterates through all JavaThreads.
3573   ALL_JAVA_THREADS(p) {
3574     tc->do_thread(p);
3575   }
3576 }
3577 
3578 void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) {
3579   assert_locked_or_safepoint(Threads_lock);
3580   java_threads_do(tc);
3581   tc->do_thread(VMThread::vm_thread());
3582 }
3583 
3584 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system).
3585 void Threads::threads_do(ThreadClosure* tc) {
3586   assert_locked_or_safepoint(Threads_lock);
3587   java_threads_do(tc);
3588   non_java_threads_do(tc);
3589 }
3590 
3591 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
3592   uintx claim_token = Threads::thread_claim_token();
3593   ALL_JAVA_THREADS(p) {
3594     if (p->claim_threads_do(is_par, claim_token)) {
3595       tc->do_thread(p);
3596     }
3597   }
3598   VMThread* vmt = VMThread::vm_thread();
3599   if (vmt->claim_threads_do(is_par, claim_token)) {
3600     tc->do_thread(vmt);
3601   }
3602 }
3603 
3604 // The system initialization in the library has three phases.
3605 //
3606 // Phase 1: java.lang.System class initialization
3607 //     java.lang.System is a primordial class loaded and initialized
3608 //     by the VM early during startup.  java.lang.System.<clinit>
3609 //     only does registerNatives and keeps the rest of the class
3610 //     initialization work later until thread initialization completes.
3611 //
3612 //     System.initPhase1 initializes the system properties, the static
3613 //     fields in, out, and err. Set up java signal handlers, OS-specific
3614 //     system settings, and thread group of the main thread.
3615 static void call_initPhase1(TRAPS) {
3616   Klass* klass =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3617   JavaValue result(T_VOID);
3618   JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3619                                          vmSymbols::void_method_signature(), CHECK);
3620 }
3621 
3622 // Phase 2. Module system initialization
3623 //     This will initialize the module system.  Only java.base classes
3624 //     can be loaded until phase 2 completes.
3625 //
3626 //     Call System.initPhase2 after the compiler initialization and jsr292
3627 //     classes get initialized because module initialization runs a lot of java
3628 //     code, that for performance reasons, should be compiled.  Also, this will
3629 //     enable the startup code to use lambda and other language features in this
3630 //     phase and onward.
3631 //
3632 //     After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3633 static void call_initPhase2(TRAPS) {
3634   TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3635 
3636   Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3637 
3638   JavaValue result(T_INT);
3639   JavaCallArguments args;
3640   args.push_int(DisplayVMOutputToStderr);
3641   args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3642   JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3643                                          vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3644   if (result.get_jint() != JNI_OK) {
3645     vm_exit_during_initialization(); // no message or exception
3646   }
3647 
3648   universe_post_module_init();
3649 }
3650 
3651 // Phase 3. final setup - set security manager, system class loader and TCCL
3652 //
3653 //     This will instantiate and set the security manager, set the system class
3654 //     loader as well as the thread context class loader.  The security manager
3655 //     and system class loader may be a custom class loaded from -Xbootclasspath/a,
3656 //     other modules or the application's classpath.
3657 static void call_initPhase3(TRAPS) {
3658   Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3659   JavaValue result(T_VOID);
3660   JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3661                                          vmSymbols::void_method_signature(), CHECK);
3662 }
3663 
3664 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3665   TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3666 
3667   if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3668     create_vm_init_libraries();
3669   }
3670 
3671   initialize_class(vmSymbols::java_lang_String(), CHECK);
3672 
3673   // Inject CompactStrings value after the static initializers for String ran.
3674   java_lang_String::set_compact_strings(CompactStrings);
3675 
3676   // Initialize java_lang.System (needed before creating the thread)
3677   initialize_class(vmSymbols::java_lang_System(), CHECK);
3678   // The VM creates & returns objects of this class. Make sure it's initialized.
3679   initialize_class(vmSymbols::java_lang_Class(), CHECK);
3680   initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3681   Handle thread_group = create_initial_thread_group(CHECK);
3682   Universe::set_main_thread_group(thread_group());
3683   initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3684   oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3685   main_thread->set_threadObj(thread_object);
3686 
3687   // Set thread status to running since main thread has
3688   // been started and running.
3689   java_lang_Thread::set_thread_status(thread_object,
3690                                       java_lang_Thread::RUNNABLE);
3691 
3692   // The VM creates objects of this class.
3693   initialize_class(vmSymbols::java_lang_Module(), CHECK);
3694 
3695 #ifdef ASSERT
3696   InstanceKlass *k = SystemDictionary::UnsafeConstants_klass();
3697   assert(k->is_not_initialized(), "UnsafeConstants should not already be initialized");
3698 #endif
3699 
3700   // initialize the hardware-specific constants needed by Unsafe
3701   initialize_class(vmSymbols::jdk_internal_misc_UnsafeConstants(), CHECK);
3702   jdk_internal_misc_UnsafeConstants::set_unsafe_constants();
3703 
3704   // The VM preresolves methods to these classes. Make sure that they get initialized
3705   initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3706   initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3707 
3708   // Phase 1 of the system initialization in the library, java.lang.System class initialization
3709   call_initPhase1(CHECK);
3710 
3711   // get the Java runtime name after java.lang.System is initialized
3712   JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3713   JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3714 
3715   // an instance of OutOfMemory exception has been allocated earlier
3716   initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3717   initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3718   initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3719   initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3720   initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3721   initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3722   initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3723   initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3724 
3725   // Eager box cache initialization only if AOT is on and any library is loaded.
3726   AOTLoader::initialize_box_caches(CHECK);
3727 }
3728 
3729 void Threads::initialize_jsr292_core_classes(TRAPS) {
3730   TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3731 
3732   initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3733   initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3734   initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3735   initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3736 }
3737 
3738 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3739   extern void JDK_Version_init();
3740 
3741   // Preinitialize version info.
3742   VM_Version::early_initialize();
3743 
3744   // Check version
3745   if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3746 
3747   // Initialize library-based TLS
3748   ThreadLocalStorage::init();
3749 
3750   // Initialize the output stream module
3751   ostream_init();
3752 
3753   // Process java launcher properties.
3754   Arguments::process_sun_java_launcher_properties(args);
3755 
3756   // Initialize the os module
3757   os::init();
3758 
3759   // Record VM creation timing statistics
3760   TraceVmCreationTime create_vm_timer;
3761   create_vm_timer.start();
3762 
3763   // Initialize system properties.
3764   Arguments::init_system_properties();
3765 
3766   // So that JDK version can be used as a discriminator when parsing arguments
3767   JDK_Version_init();
3768 
3769   // Update/Initialize System properties after JDK version number is known
3770   Arguments::init_version_specific_system_properties();
3771 
3772   // Make sure to initialize log configuration *before* parsing arguments
3773   LogConfiguration::initialize(create_vm_timer.begin_time());
3774 
3775   // Parse arguments
3776   // Note: this internally calls os::init_container_support()
3777   jint parse_result = Arguments::parse(args);
3778   if (parse_result != JNI_OK) return parse_result;
3779 
3780   os::init_before_ergo();
3781 
3782   jint ergo_result = Arguments::apply_ergo();
3783   if (ergo_result != JNI_OK) return ergo_result;
3784 
3785   // Final check of all ranges after ergonomics which may change values.
3786   if (!JVMFlagRangeList::check_ranges()) {
3787     return JNI_EINVAL;
3788   }
3789 
3790   // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3791   bool constraint_result = JVMFlagConstraintList::check_constraints(JVMFlagConstraint::AfterErgo);
3792   if (!constraint_result) {
3793     return JNI_EINVAL;
3794   }
3795 
3796   JVMFlagWriteableList::mark_startup();
3797 
3798   if (PauseAtStartup) {
3799     os::pause();
3800   }
3801 
3802   HOTSPOT_VM_INIT_BEGIN();
3803 
3804   // Timing (must come after argument parsing)
3805   TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3806 
3807   // Initialize the os module after parsing the args
3808   jint os_init_2_result = os::init_2();
3809   if (os_init_2_result != JNI_OK) return os_init_2_result;
3810 
3811 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT
3812   // Initialize assert poison page mechanism.
3813   if (ShowRegistersOnAssert) {
3814     initialize_assert_poison();
3815   }
3816 #endif // CAN_SHOW_REGISTERS_ON_ASSERT
3817 
3818   SafepointMechanism::initialize();
3819 
3820   jint adjust_after_os_result = Arguments::adjust_after_os();
3821   if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3822 
3823   // Initialize output stream logging
3824   ostream_init_log();
3825 
3826   // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3827   // Must be before create_vm_init_agents()
3828   if (Arguments::init_libraries_at_startup()) {
3829     convert_vm_init_libraries_to_agents();
3830   }
3831 
3832   // Launch -agentlib/-agentpath and converted -Xrun agents
3833   if (Arguments::init_agents_at_startup()) {
3834     create_vm_init_agents();
3835   }
3836 
3837   // Initialize Threads state
3838   _number_of_threads = 0;
3839   _number_of_non_daemon_threads = 0;
3840 
3841   // Initialize global data structures and create system classes in heap
3842   vm_init_globals();
3843 
3844 #if INCLUDE_JVMCI
3845   if (JVMCICounterSize > 0) {
3846     JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtJVMCI);
3847     memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3848   } else {
3849     JavaThread::_jvmci_old_thread_counters = NULL;
3850   }
3851 #endif // INCLUDE_JVMCI
3852 
3853   // Attach the main thread to this os thread
3854   JavaThread* main_thread = new JavaThread();
3855   main_thread->set_thread_state(_thread_in_vm);
3856   main_thread->initialize_thread_current();
3857   // must do this before set_active_handles
3858   main_thread->record_stack_base_and_size();
3859   main_thread->register_thread_stack_with_NMT();
3860   main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3861 
3862   if (!main_thread->set_as_starting_thread()) {
3863     vm_shutdown_during_initialization(
3864                                       "Failed necessary internal allocation. Out of swap space");
3865     main_thread->smr_delete();
3866     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3867     return JNI_ENOMEM;
3868   }
3869 
3870   // Enable guard page *after* os::create_main_thread(), otherwise it would
3871   // crash Linux VM, see notes in os_linux.cpp.
3872   main_thread->create_stack_guard_pages();
3873 
3874   // Initialize Java-Level synchronization subsystem
3875   ObjectMonitor::Initialize();
3876 
3877   // Initialize global modules
3878   jint status = init_globals();
3879   if (status != JNI_OK) {
3880     main_thread->smr_delete();
3881     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3882     return status;
3883   }
3884 
3885   JFR_ONLY(Jfr::on_vm_init();)
3886 
3887   // Should be done after the heap is fully created
3888   main_thread->cache_global_variables();
3889 
3890   HandleMark hm;
3891 
3892   { MutexLocker mu(Threads_lock);
3893     Threads::add(main_thread);
3894   }
3895 
3896   // Any JVMTI raw monitors entered in onload will transition into
3897   // real raw monitor. VM is setup enough here for raw monitor enter.
3898   JvmtiExport::transition_pending_onload_raw_monitors();
3899 
3900   // Create the VMThread
3901   { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3902 
3903   VMThread::create();
3904     Thread* vmthread = VMThread::vm_thread();
3905 
3906     if (!os::create_thread(vmthread, os::vm_thread)) {
3907       vm_exit_during_initialization("Cannot create VM thread. "
3908                                     "Out of system resources.");
3909     }
3910 
3911     // Wait for the VM thread to become ready, and VMThread::run to initialize
3912     // Monitors can have spurious returns, must always check another state flag
3913     {
3914       MonitorLocker ml(Notify_lock);
3915       os::start_thread(vmthread);
3916       while (vmthread->active_handles() == NULL) {
3917         ml.wait();
3918       }
3919     }
3920   }
3921 
3922   assert(Universe::is_fully_initialized(), "not initialized");
3923   if (VerifyDuringStartup) {
3924     // Make sure we're starting with a clean slate.
3925     VM_Verify verify_op;
3926     VMThread::execute(&verify_op);
3927   }
3928 
3929   // We need this to update the java.vm.info property in case any flags used
3930   // to initially define it have been changed. This is needed for both CDS and
3931   // AOT, since UseSharedSpaces and UseAOT may be changed after java.vm.info
3932   // is initially computed. See Abstract_VM_Version::vm_info_string().
3933   // This update must happen before we initialize the java classes, but
3934   // after any initialization logic that might modify the flags.
3935   Arguments::update_vm_info_property(VM_Version::vm_info_string());
3936 
3937   Thread* THREAD = Thread::current();
3938 
3939   // Always call even when there are not JVMTI environments yet, since environments
3940   // may be attached late and JVMTI must track phases of VM execution
3941   JvmtiExport::enter_early_start_phase();
3942 
3943   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3944   JvmtiExport::post_early_vm_start();
3945 
3946   initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3947 
3948   quicken_jni_functions();
3949 
3950   // No more stub generation allowed after that point.
3951   StubCodeDesc::freeze();
3952 
3953   // Set flag that basic initialization has completed. Used by exceptions and various
3954   // debug stuff, that does not work until all basic classes have been initialized.
3955   set_init_completed();
3956 
3957   LogConfiguration::post_initialize();
3958   Metaspace::post_initialize();
3959 
3960   HOTSPOT_VM_INIT_END();
3961 
3962   // record VM initialization completion time
3963 #if INCLUDE_MANAGEMENT
3964   Management::record_vm_init_completed();
3965 #endif // INCLUDE_MANAGEMENT
3966 
3967   // Signal Dispatcher needs to be started before VMInit event is posted
3968   os::initialize_jdk_signal_support(CHECK_JNI_ERR);
3969 
3970   // Start Attach Listener if +StartAttachListener or it can't be started lazily
3971   if (!DisableAttachMechanism) {
3972     AttachListener::vm_start();
3973     if (StartAttachListener || AttachListener::init_at_startup()) {
3974       AttachListener::init();
3975     }
3976   }
3977 
3978   // Launch -Xrun agents
3979   // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3980   // back-end can launch with -Xdebug -Xrunjdwp.
3981   if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3982     create_vm_init_libraries();
3983   }
3984 
3985   if (CleanChunkPoolAsync) {
3986     Chunk::start_chunk_pool_cleaner_task();
3987   }
3988 
3989 
3990   // initialize compiler(s)
3991 #if defined(COMPILER1) || COMPILER2_OR_JVMCI
3992 #if INCLUDE_JVMCI
3993   bool force_JVMCI_intialization = false;
3994   if (EnableJVMCI) {
3995     // Initialize JVMCI eagerly when it is explicitly requested.
3996     // Or when JVMCILibDumpJNIConfig or JVMCIPrintProperties is enabled.
3997     force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties || JVMCILibDumpJNIConfig;
3998 
3999     if (!force_JVMCI_intialization) {
4000       // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
4001       // compilations via JVMCI will not actually block until JVMCI is initialized.
4002       force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
4003     }
4004   }
4005 #endif
4006   CompileBroker::compilation_init_phase1(CHECK_JNI_ERR);
4007   // Postpone completion of compiler initialization to after JVMCI
4008   // is initialized to avoid timeouts of blocking compilations.
4009   if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) {
4010     CompileBroker::compilation_init_phase2();
4011   }
4012 #endif
4013 
4014   // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
4015   // It is done after compilers are initialized, because otherwise compilations of
4016   // signature polymorphic MH intrinsics can be missed
4017   // (see SystemDictionary::find_method_handle_intrinsic).
4018   initialize_jsr292_core_classes(CHECK_JNI_ERR);
4019 
4020   // This will initialize the module system.  Only java.base classes can be
4021   // loaded until phase 2 completes
4022   call_initPhase2(CHECK_JNI_ERR);
4023 
4024   // Always call even when there are not JVMTI environments yet, since environments
4025   // may be attached late and JVMTI must track phases of VM execution
4026   JvmtiExport::enter_start_phase();
4027 
4028   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
4029   JvmtiExport::post_vm_start();
4030 
4031   // Final system initialization including security manager and system class loader
4032   call_initPhase3(CHECK_JNI_ERR);
4033 
4034   // cache the system and platform class loaders
4035   SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
4036 
4037 #if INCLUDE_CDS
4038   // capture the module path info from the ModuleEntryTable
4039   ClassLoader::initialize_module_path(THREAD);
4040 #endif
4041 
4042 #if INCLUDE_JVMCI
4043   if (force_JVMCI_intialization) {
4044     JVMCI::initialize_compiler(CHECK_JNI_ERR);
4045     CompileBroker::compilation_init_phase2();
4046   }
4047 #endif
4048 
4049   // Always call even when there are not JVMTI environments yet, since environments
4050   // may be attached late and JVMTI must track phases of VM execution
4051   JvmtiExport::enter_live_phase();
4052 
4053   // Make perfmemory accessible
4054   PerfMemory::set_accessible(true);
4055 
4056   // Notify JVMTI agents that VM initialization is complete - nop if no agents.
4057   JvmtiExport::post_vm_initialized();
4058 
4059   JFR_ONLY(Jfr::on_vm_start();)
4060 
4061 #if INCLUDE_MANAGEMENT
4062   Management::initialize(THREAD);
4063 
4064   if (HAS_PENDING_EXCEPTION) {
4065     // management agent fails to start possibly due to
4066     // configuration problem and is responsible for printing
4067     // stack trace if appropriate. Simply exit VM.
4068     vm_exit(1);
4069   }
4070 #endif // INCLUDE_MANAGEMENT
4071 
4072   if (MemProfiling)                   MemProfiler::engage();
4073   StatSampler::engage();
4074   if (CheckJNICalls)                  JniPeriodicChecker::engage();
4075 
4076   BiasedLocking::init();
4077 
4078 #if INCLUDE_RTM_OPT
4079   RTMLockingCounters::init();
4080 #endif
4081 
4082   call_postVMInitHook(THREAD);
4083   // The Java side of PostVMInitHook.run must deal with all
4084   // exceptions and provide means of diagnosis.
4085   if (HAS_PENDING_EXCEPTION) {
4086     CLEAR_PENDING_EXCEPTION;
4087   }
4088 
4089   {
4090     MutexLocker ml(PeriodicTask_lock);
4091     // Make sure the WatcherThread can be started by WatcherThread::start()
4092     // or by dynamic enrollment.
4093     WatcherThread::make_startable();
4094     // Start up the WatcherThread if there are any periodic tasks
4095     // NOTE:  All PeriodicTasks should be registered by now. If they
4096     //   aren't, late joiners might appear to start slowly (we might
4097     //   take a while to process their first tick).
4098     if (PeriodicTask::num_tasks() > 0) {
4099       WatcherThread::start();
4100     }
4101   }
4102 
4103   create_vm_timer.end();
4104 #ifdef ASSERT
4105   _vm_complete = true;
4106 #endif
4107 
4108   if (DumpSharedSpaces) {
4109     MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
4110     ShouldNotReachHere();
4111   }
4112 
4113   return JNI_OK;
4114 }
4115 
4116 // type for the Agent_OnLoad and JVM_OnLoad entry points
4117 extern "C" {
4118   typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
4119 }
4120 // Find a command line agent library and return its entry point for
4121 //         -agentlib:  -agentpath:   -Xrun
4122 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
4123 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
4124                                     const char *on_load_symbols[],
4125                                     size_t num_symbol_entries) {
4126   OnLoadEntry_t on_load_entry = NULL;
4127   void *library = NULL;
4128 
4129   if (!agent->valid()) {
4130     char buffer[JVM_MAXPATHLEN];
4131     char ebuf[1024] = "";
4132     const char *name = agent->name();
4133     const char *msg = "Could not find agent library ";
4134 
4135     // First check to see if agent is statically linked into executable
4136     if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
4137       library = agent->os_lib();
4138     } else if (agent->is_absolute_path()) {
4139       library = os::dll_load(name, ebuf, sizeof ebuf);
4140       if (library == NULL) {
4141         const char *sub_msg = " in absolute path, with error: ";
4142         size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
4143         char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4144         jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4145         // If we can't find the agent, exit.
4146         vm_exit_during_initialization(buf, NULL);
4147         FREE_C_HEAP_ARRAY(char, buf);
4148       }
4149     } else {
4150       // Try to load the agent from the standard dll directory
4151       if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
4152                              name)) {
4153         library = os::dll_load(buffer, ebuf, sizeof ebuf);
4154       }
4155       if (library == NULL) { // Try the library path directory.
4156         if (os::dll_build_name(buffer, sizeof(buffer), name)) {
4157           library = os::dll_load(buffer, ebuf, sizeof ebuf);
4158         }
4159         if (library == NULL) {
4160           const char *sub_msg = " on the library path, with error: ";
4161           const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image.";
4162 
4163           size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) +
4164                        strlen(ebuf) + strlen(sub_msg2) + 1;
4165           char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4166           if (!agent->is_instrument_lib()) {
4167             jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4168           } else {
4169             jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2);
4170           }
4171           // If we can't find the agent, exit.
4172           vm_exit_during_initialization(buf, NULL);
4173           FREE_C_HEAP_ARRAY(char, buf);
4174         }
4175       }
4176     }
4177     agent->set_os_lib(library);
4178     agent->set_valid();
4179   }
4180 
4181   // Find the OnLoad function.
4182   on_load_entry =
4183     CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
4184                                                           false,
4185                                                           on_load_symbols,
4186                                                           num_symbol_entries));
4187   return on_load_entry;
4188 }
4189 
4190 // Find the JVM_OnLoad entry point
4191 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
4192   const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
4193   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4194 }
4195 
4196 // Find the Agent_OnLoad entry point
4197 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
4198   const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
4199   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4200 }
4201 
4202 // For backwards compatibility with -Xrun
4203 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
4204 // treated like -agentpath:
4205 // Must be called before agent libraries are created
4206 void Threads::convert_vm_init_libraries_to_agents() {
4207   AgentLibrary* agent;
4208   AgentLibrary* next;
4209 
4210   for (agent = Arguments::libraries(); agent != NULL; agent = next) {
4211     next = agent->next();  // cache the next agent now as this agent may get moved off this list
4212     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4213 
4214     // If there is an JVM_OnLoad function it will get called later,
4215     // otherwise see if there is an Agent_OnLoad
4216     if (on_load_entry == NULL) {
4217       on_load_entry = lookup_agent_on_load(agent);
4218       if (on_load_entry != NULL) {
4219         // switch it to the agent list -- so that Agent_OnLoad will be called,
4220         // JVM_OnLoad won't be attempted and Agent_OnUnload will
4221         Arguments::convert_library_to_agent(agent);
4222       } else {
4223         vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
4224       }
4225     }
4226   }
4227 }
4228 
4229 // Create agents for -agentlib:  -agentpath:  and converted -Xrun
4230 // Invokes Agent_OnLoad
4231 // Called very early -- before JavaThreads exist
4232 void Threads::create_vm_init_agents() {
4233   extern struct JavaVM_ main_vm;
4234   AgentLibrary* agent;
4235 
4236   JvmtiExport::enter_onload_phase();
4237 
4238   for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4239     // CDS dumping does not support native JVMTI agent.
4240     // CDS dumping supports Java agent if the AllowArchivingWithJavaAgent diagnostic option is specified.
4241     if (DumpSharedSpaces || DynamicDumpSharedSpaces) {
4242       if(!agent->is_instrument_lib()) {
4243         vm_exit_during_cds_dumping("CDS dumping does not support native JVMTI agent, name", agent->name());
4244       } else if (!AllowArchivingWithJavaAgent) {
4245         vm_exit_during_cds_dumping(
4246           "Must enable AllowArchivingWithJavaAgent in order to run Java agent during CDS dumping");
4247       }
4248     }
4249 
4250     OnLoadEntry_t  on_load_entry = lookup_agent_on_load(agent);
4251 
4252     if (on_load_entry != NULL) {
4253       // Invoke the Agent_OnLoad function
4254       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4255       if (err != JNI_OK) {
4256         vm_exit_during_initialization("agent library failed to init", agent->name());
4257       }
4258     } else {
4259       vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4260     }
4261   }
4262 
4263   JvmtiExport::enter_primordial_phase();
4264 }
4265 
4266 extern "C" {
4267   typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4268 }
4269 
4270 void Threads::shutdown_vm_agents() {
4271   // Send any Agent_OnUnload notifications
4272   const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4273   size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4274   extern struct JavaVM_ main_vm;
4275   for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4276 
4277     // Find the Agent_OnUnload function.
4278     Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4279                                                    os::find_agent_function(agent,
4280                                                    false,
4281                                                    on_unload_symbols,
4282                                                    num_symbol_entries));
4283 
4284     // Invoke the Agent_OnUnload function
4285     if (unload_entry != NULL) {
4286       JavaThread* thread = JavaThread::current();
4287       ThreadToNativeFromVM ttn(thread);
4288       HandleMark hm(thread);
4289       (*unload_entry)(&main_vm);
4290     }
4291   }
4292 }
4293 
4294 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4295 // Invokes JVM_OnLoad
4296 void Threads::create_vm_init_libraries() {
4297   extern struct JavaVM_ main_vm;
4298   AgentLibrary* agent;
4299 
4300   for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4301     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4302 
4303     if (on_load_entry != NULL) {
4304       // Invoke the JVM_OnLoad function
4305       JavaThread* thread = JavaThread::current();
4306       ThreadToNativeFromVM ttn(thread);
4307       HandleMark hm(thread);
4308       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4309       if (err != JNI_OK) {
4310         vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4311       }
4312     } else {
4313       vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4314     }
4315   }
4316 }
4317 
4318 
4319 // Last thread running calls java.lang.Shutdown.shutdown()
4320 void JavaThread::invoke_shutdown_hooks() {
4321   HandleMark hm(this);
4322 
4323   // We could get here with a pending exception, if so clear it now.
4324   if (this->has_pending_exception()) {
4325     this->clear_pending_exception();
4326   }
4327 
4328   EXCEPTION_MARK;
4329   Klass* shutdown_klass =
4330     SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4331                                       THREAD);
4332   if (shutdown_klass != NULL) {
4333     // SystemDictionary::resolve_or_null will return null if there was
4334     // an exception.  If we cannot load the Shutdown class, just don't
4335     // call Shutdown.shutdown() at all.  This will mean the shutdown hooks
4336     // won't be run.  Note that if a shutdown hook was registered,
4337     // the Shutdown class would have already been loaded
4338     // (Runtime.addShutdownHook will load it).
4339     JavaValue result(T_VOID);
4340     JavaCalls::call_static(&result,
4341                            shutdown_klass,
4342                            vmSymbols::shutdown_name(),
4343                            vmSymbols::void_method_signature(),
4344                            THREAD);
4345   }
4346   CLEAR_PENDING_EXCEPTION;
4347 }
4348 
4349 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4350 // the program falls off the end of main(). Another VM exit path is through
4351 // vm_exit() when the program calls System.exit() to return a value or when
4352 // there is a serious error in VM. The two shutdown paths are not exactly
4353 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4354 // and VM_Exit op at VM level.
4355 //
4356 // Shutdown sequence:
4357 //   + Shutdown native memory tracking if it is on
4358 //   + Wait until we are the last non-daemon thread to execute
4359 //     <-- every thing is still working at this moment -->
4360 //   + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4361 //        shutdown hooks
4362 //   + Call before_exit(), prepare for VM exit
4363 //      > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4364 //        currently the only user of this mechanism is File.deleteOnExit())
4365 //      > stop StatSampler, watcher thread, CMS threads,
4366 //        post thread end and vm death events to JVMTI,
4367 //        stop signal thread
4368 //   + Call JavaThread::exit(), it will:
4369 //      > release JNI handle blocks, remove stack guard pages
4370 //      > remove this thread from Threads list
4371 //     <-- no more Java code from this thread after this point -->
4372 //   + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4373 //     the compiler threads at safepoint
4374 //     <-- do not use anything that could get blocked by Safepoint -->
4375 //   + Disable tracing at JNI/JVM barriers
4376 //   + Set _vm_exited flag for threads that are still running native code
4377 //   + Call exit_globals()
4378 //      > deletes tty
4379 //      > deletes PerfMemory resources
4380 //   + Delete this thread
4381 //   + Return to caller
4382 
4383 bool Threads::destroy_vm() {
4384   JavaThread* thread = JavaThread::current();
4385 
4386 #ifdef ASSERT
4387   _vm_complete = false;
4388 #endif
4389   // Wait until we are the last non-daemon thread to execute
4390   { MonitorLocker nu(Threads_lock);
4391     while (Threads::number_of_non_daemon_threads() > 1)
4392       // This wait should make safepoint checks, wait without a timeout,
4393       // and wait as a suspend-equivalent condition.
4394       nu.wait(0, Mutex::_as_suspend_equivalent_flag);
4395   }
4396 
4397   EventShutdown e;
4398   if (e.should_commit()) {
4399     e.set_reason("No remaining non-daemon Java threads");
4400     e.commit();
4401   }
4402 
4403   // Hang forever on exit if we are reporting an error.
4404   if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4405     os::infinite_sleep();
4406   }
4407   os::wait_for_keypress_at_exit();
4408 
4409   // run Java level shutdown hooks
4410   thread->invoke_shutdown_hooks();
4411 
4412   before_exit(thread);
4413 
4414   thread->exit(true);
4415 
4416   // Stop VM thread.
4417   {
4418     // 4945125 The vm thread comes to a safepoint during exit.
4419     // GC vm_operations can get caught at the safepoint, and the
4420     // heap is unparseable if they are caught. Grab the Heap_lock
4421     // to prevent this. The GC vm_operations will not be able to
4422     // queue until after the vm thread is dead. After this point,
4423     // we'll never emerge out of the safepoint before the VM exits.
4424 
4425     MutexLocker ml(Heap_lock, Mutex::_no_safepoint_check_flag);
4426 
4427     VMThread::wait_for_vm_thread_exit();
4428     assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4429     VMThread::destroy();
4430   }
4431 
4432   // Now, all Java threads are gone except daemon threads. Daemon threads
4433   // running Java code or in VM are stopped by the Safepoint. However,
4434   // daemon threads executing native code are still running.  But they
4435   // will be stopped at native=>Java/VM barriers. Note that we can't
4436   // simply kill or suspend them, as it is inherently deadlock-prone.
4437 
4438   VM_Exit::set_vm_exited();
4439 
4440   // Clean up ideal graph printers after the VMThread has started
4441   // the final safepoint which will block all the Compiler threads.
4442   // Note that this Thread has already logically exited so the
4443   // clean_up() function's use of a JavaThreadIteratorWithHandle
4444   // would be a problem except set_vm_exited() has remembered the
4445   // shutdown thread which is granted a policy exception.
4446 #if defined(COMPILER2) && !defined(PRODUCT)
4447   IdealGraphPrinter::clean_up();
4448 #endif
4449 
4450   notify_vm_shutdown();
4451 
4452   // exit_globals() will delete tty
4453   exit_globals();
4454 
4455   // We are after VM_Exit::set_vm_exited() so we can't call
4456   // thread->smr_delete() or we will block on the Threads_lock.
4457   // Deleting the shutdown thread here is safe because another
4458   // JavaThread cannot have an active ThreadsListHandle for
4459   // this JavaThread.
4460   delete thread;
4461 
4462 #if INCLUDE_JVMCI
4463   if (JVMCICounterSize > 0) {
4464     FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4465   }
4466 #endif
4467 
4468   LogConfiguration::finalize();
4469 
4470   return true;
4471 }
4472 
4473 
4474 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4475   if (version == JNI_VERSION_1_1) return JNI_TRUE;
4476   return is_supported_jni_version(version);
4477 }
4478 
4479 
4480 jboolean Threads::is_supported_jni_version(jint version) {
4481   if (version == JNI_VERSION_1_2) return JNI_TRUE;
4482   if (version == JNI_VERSION_1_4) return JNI_TRUE;
4483   if (version == JNI_VERSION_1_6) return JNI_TRUE;
4484   if (version == JNI_VERSION_1_8) return JNI_TRUE;
4485   if (version == JNI_VERSION_9) return JNI_TRUE;
4486   if (version == JNI_VERSION_10) return JNI_TRUE;
4487   return JNI_FALSE;
4488 }
4489 
4490 
4491 void Threads::add(JavaThread* p, bool force_daemon) {
4492   // The threads lock must be owned at this point
4493   assert(Threads_lock->owned_by_self(), "must have threads lock");
4494 
4495   BarrierSet::barrier_set()->on_thread_attach(p);
4496 
4497   // Once a JavaThread is added to the Threads list, smr_delete() has
4498   // to be used to delete it. Otherwise we can just delete it directly.
4499   p->set_on_thread_list();
4500 
4501   _number_of_threads++;
4502   oop threadObj = p->threadObj();
4503   bool daemon = true;
4504   // Bootstrapping problem: threadObj can be null for initial
4505   // JavaThread (or for threads attached via JNI)
4506   if ((!force_daemon) && !is_daemon((threadObj))) {
4507     _number_of_non_daemon_threads++;
4508     daemon = false;
4509   }
4510 
4511   ThreadService::add_thread(p, daemon);
4512 
4513   // Maintain fast thread list
4514   ThreadsSMRSupport::add_thread(p);
4515 
4516   // Possible GC point.
4517   Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4518 }
4519 
4520 void Threads::remove(JavaThread* p, bool is_daemon) {
4521 
4522   // Reclaim the ObjectMonitors from the omInUseList and omFreeList of the moribund thread.
4523   ObjectSynchronizer::omFlush(p);
4524 
4525   // Extra scope needed for Thread_lock, so we can check
4526   // that we do not remove thread without safepoint code notice
4527   { MonitorLocker ml(Threads_lock);
4528 
4529     assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present");
4530 
4531     // Maintain fast thread list
4532     ThreadsSMRSupport::remove_thread(p);
4533 
4534     _number_of_threads--;
4535     if (!is_daemon) {
4536       _number_of_non_daemon_threads--;
4537 
4538       // Only one thread left, do a notify on the Threads_lock so a thread waiting
4539       // on destroy_vm will wake up.
4540       if (number_of_non_daemon_threads() == 1) {
4541         ml.notify_all();
4542       }
4543     }
4544     ThreadService::remove_thread(p, is_daemon);
4545 
4546     // Make sure that safepoint code disregard this thread. This is needed since
4547     // the thread might mess around with locks after this point. This can cause it
4548     // to do callbacks into the safepoint code. However, the safepoint code is not aware
4549     // of this thread since it is removed from the queue.
4550     p->set_terminated_value();
4551   } // unlock Threads_lock
4552 
4553   // Since Events::log uses a lock, we grab it outside the Threads_lock
4554   Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4555 }
4556 
4557 // Operations on the Threads list for GC.  These are not explicitly locked,
4558 // but the garbage collector must provide a safe context for them to run.
4559 // In particular, these things should never be called when the Threads_lock
4560 // is held by some other thread. (Note: the Safepoint abstraction also
4561 // uses the Threads_lock to guarantee this property. It also makes sure that
4562 // all threads gets blocked when exiting or starting).
4563 
4564 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4565   ALL_JAVA_THREADS(p) {
4566     p->oops_do(f, cf);
4567   }
4568   VMThread::vm_thread()->oops_do(f, cf);
4569 }
4570 
4571 void Threads::change_thread_claim_token() {
4572   if (++_thread_claim_token == 0) {
4573     // On overflow of the token counter, there is a risk of future
4574     // collisions between a new global token value and a stale token
4575     // for a thread, because not all iterations visit all threads.
4576     // (Though it's pretty much a theoretical concern for non-trivial
4577     // token counter sizes.)  To deal with the possibility, reset all
4578     // the thread tokens to zero on global token overflow.
4579     struct ResetClaims : public ThreadClosure {
4580       virtual void do_thread(Thread* t) {
4581         t->claim_threads_do(false, 0);
4582       }
4583     } reset_claims;
4584     Threads::threads_do(&reset_claims);
4585     // On overflow, update the global token to non-zero, to
4586     // avoid the special "never claimed" initial thread value.
4587     _thread_claim_token = 1;
4588   }
4589 }
4590 
4591 #ifdef ASSERT
4592 void assert_thread_claimed(const char* kind, Thread* t, uintx expected) {
4593   const uintx token = t->threads_do_token();
4594   assert(token == expected,
4595          "%s " PTR_FORMAT " has incorrect value " UINTX_FORMAT " != "
4596          UINTX_FORMAT, kind, p2i(t), token, expected);
4597 }
4598 
4599 void Threads::assert_all_threads_claimed() {
4600   ALL_JAVA_THREADS(p) {
4601     assert_thread_claimed("Thread", p, _thread_claim_token);
4602   }
4603   assert_thread_claimed("VMThread", VMThread::vm_thread(), _thread_claim_token);
4604 }
4605 #endif // ASSERT
4606 
4607 class ParallelOopsDoThreadClosure : public ThreadClosure {
4608 private:
4609   OopClosure* _f;
4610   CodeBlobClosure* _cf;
4611 public:
4612   ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {}
4613   void do_thread(Thread* t) {
4614     t->oops_do(_f, _cf);
4615   }
4616 };
4617 
4618 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4619   ParallelOopsDoThreadClosure tc(f, cf);
4620   possibly_parallel_threads_do(is_par, &tc);
4621 }
4622 
4623 void Threads::nmethods_do(CodeBlobClosure* cf) {
4624   ALL_JAVA_THREADS(p) {
4625     // This is used by the code cache sweeper to mark nmethods that are active
4626     // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4627     // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4628     if(!p->is_Code_cache_sweeper_thread()) {
4629       p->nmethods_do(cf);
4630     }
4631   }
4632 }
4633 
4634 void Threads::metadata_do(MetadataClosure* f) {
4635   ALL_JAVA_THREADS(p) {
4636     p->metadata_do(f);
4637   }
4638 }
4639 
4640 class ThreadHandlesClosure : public ThreadClosure {
4641   void (*_f)(Metadata*);
4642  public:
4643   ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4644   virtual void do_thread(Thread* thread) {
4645     thread->metadata_handles_do(_f);
4646   }
4647 };
4648 
4649 void Threads::metadata_handles_do(void f(Metadata*)) {
4650   // Only walk the Handles in Thread.
4651   ThreadHandlesClosure handles_closure(f);
4652   threads_do(&handles_closure);
4653 }
4654 
4655 // Get count Java threads that are waiting to enter the specified monitor.
4656 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
4657                                                          int count,
4658                                                          address monitor) {
4659   GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4660 
4661   int i = 0;
4662   DO_JAVA_THREADS(t_list, p) {
4663     if (!p->can_call_java()) continue;
4664 
4665     address pending = (address)p->current_pending_monitor();
4666     if (pending == monitor) {             // found a match
4667       if (i < count) result->append(p);   // save the first count matches
4668       i++;
4669     }
4670   }
4671 
4672   return result;
4673 }
4674 
4675 
4676 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
4677                                                       address owner) {
4678   // NULL owner means not locked so we can skip the search
4679   if (owner == NULL) return NULL;
4680 
4681   DO_JAVA_THREADS(t_list, p) {
4682     // first, see if owner is the address of a Java thread
4683     if (owner == (address)p) return p;
4684   }
4685 
4686   // Cannot assert on lack of success here since this function may be
4687   // used by code that is trying to report useful problem information
4688   // like deadlock detection.
4689   if (UseHeavyMonitors) return NULL;
4690 
4691   // If we didn't find a matching Java thread and we didn't force use of
4692   // heavyweight monitors, then the owner is the stack address of the
4693   // Lock Word in the owning Java thread's stack.
4694   //
4695   JavaThread* the_owner = NULL;
4696   DO_JAVA_THREADS(t_list, q) {
4697     if (q->is_lock_owned(owner)) {
4698       the_owner = q;
4699       break;
4700     }
4701   }
4702 
4703   // cannot assert on lack of success here; see above comment
4704   return the_owner;
4705 }
4706 
4707 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4708 void Threads::print_on(outputStream* st, bool print_stacks,
4709                        bool internal_format, bool print_concurrent_locks,
4710                        bool print_extended_info) {
4711   char buf[32];
4712   st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4713 
4714   st->print_cr("Full thread dump %s (%s %s):",
4715                VM_Version::vm_name(),
4716                VM_Version::vm_release(),
4717                VM_Version::vm_info_string());
4718   st->cr();
4719 
4720 #if INCLUDE_SERVICES
4721   // Dump concurrent locks
4722   ConcurrentLocksDump concurrent_locks;
4723   if (print_concurrent_locks) {
4724     concurrent_locks.dump_at_safepoint();
4725   }
4726 #endif // INCLUDE_SERVICES
4727 
4728   ThreadsSMRSupport::print_info_on(st);
4729   st->cr();
4730 
4731   ALL_JAVA_THREADS(p) {
4732     ResourceMark rm;
4733     p->print_on(st, print_extended_info);
4734     if (print_stacks) {
4735       if (internal_format) {
4736         p->trace_stack();
4737       } else {
4738         p->print_stack_on(st);
4739       }
4740     }
4741     st->cr();
4742 #if INCLUDE_SERVICES
4743     if (print_concurrent_locks) {
4744       concurrent_locks.print_locks_on(p, st);
4745     }
4746 #endif // INCLUDE_SERVICES
4747   }
4748 
4749   VMThread::vm_thread()->print_on(st);
4750   st->cr();
4751   Universe::heap()->print_gc_threads_on(st);
4752   WatcherThread* wt = WatcherThread::watcher_thread();
4753   if (wt != NULL) {
4754     wt->print_on(st);
4755     st->cr();
4756   }
4757 
4758   st->flush();
4759 }
4760 
4761 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4762                              int buflen, bool* found_current) {
4763   if (this_thread != NULL) {
4764     bool is_current = (current == this_thread);
4765     *found_current = *found_current || is_current;
4766     st->print("%s", is_current ? "=>" : "  ");
4767 
4768     st->print(PTR_FORMAT, p2i(this_thread));
4769     st->print(" ");
4770     this_thread->print_on_error(st, buf, buflen);
4771     st->cr();
4772   }
4773 }
4774 
4775 class PrintOnErrorClosure : public ThreadClosure {
4776   outputStream* _st;
4777   Thread* _current;
4778   char* _buf;
4779   int _buflen;
4780   bool* _found_current;
4781  public:
4782   PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4783                       int buflen, bool* found_current) :
4784    _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4785 
4786   virtual void do_thread(Thread* thread) {
4787     Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4788   }
4789 };
4790 
4791 // Threads::print_on_error() is called by fatal error handler. It's possible
4792 // that VM is not at safepoint and/or current thread is inside signal handler.
4793 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4794 // memory (even in resource area), it might deadlock the error handler.
4795 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4796                              int buflen) {
4797   ThreadsSMRSupport::print_info_on(st);
4798   st->cr();
4799 
4800   bool found_current = false;
4801   st->print_cr("Java Threads: ( => current thread )");
4802   ALL_JAVA_THREADS(thread) {
4803     print_on_error(thread, st, current, buf, buflen, &found_current);
4804   }
4805   st->cr();
4806 
4807   st->print_cr("Other Threads:");
4808   print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4809   print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4810 
4811   PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4812   Universe::heap()->gc_threads_do(&print_closure);
4813 
4814   if (!found_current) {
4815     st->cr();
4816     st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4817     current->print_on_error(st, buf, buflen);
4818     st->cr();
4819   }
4820   st->cr();
4821 
4822   st->print_cr("Threads with active compile tasks:");
4823   print_threads_compiling(st, buf, buflen);
4824 }
4825 
4826 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen, bool short_form) {
4827   ALL_JAVA_THREADS(thread) {
4828     if (thread->is_Compiler_thread()) {
4829       CompilerThread* ct = (CompilerThread*) thread;
4830 
4831       // Keep task in local variable for NULL check.
4832       // ct->_task might be set to NULL by concurring compiler thread
4833       // because it completed the compilation. The task is never freed,
4834       // though, just returned to a free list.
4835       CompileTask* task = ct->task();
4836       if (task != NULL) {
4837         thread->print_name_on_error(st, buf, buflen);
4838         st->print("  ");
4839         task->print(st, NULL, short_form, true);
4840       }
4841     }
4842   }
4843 }
4844 
4845 
4846 // Internal SpinLock and Mutex
4847 // Based on ParkEvent
4848 
4849 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4850 //
4851 // We employ SpinLocks _only for low-contention, fixed-length
4852 // short-duration critical sections where we're concerned
4853 // about native mutex_t or HotSpot Mutex:: latency.
4854 // The mux construct provides a spin-then-block mutual exclusion
4855 // mechanism.
4856 //
4857 // Testing has shown that contention on the ListLock guarding gFreeList
4858 // is common.  If we implement ListLock as a simple SpinLock it's common
4859 // for the JVM to devolve to yielding with little progress.  This is true
4860 // despite the fact that the critical sections protected by ListLock are
4861 // extremely short.
4862 //
4863 // TODO-FIXME: ListLock should be of type SpinLock.
4864 // We should make this a 1st-class type, integrated into the lock
4865 // hierarchy as leaf-locks.  Critically, the SpinLock structure
4866 // should have sufficient padding to avoid false-sharing and excessive
4867 // cache-coherency traffic.
4868 
4869 
4870 typedef volatile int SpinLockT;
4871 
4872 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4873   if (Atomic::cmpxchg (1, adr, 0) == 0) {
4874     return;   // normal fast-path return
4875   }
4876 
4877   // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4878   int ctr = 0;
4879   int Yields = 0;
4880   for (;;) {
4881     while (*adr != 0) {
4882       ++ctr;
4883       if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4884         if (Yields > 5) {
4885           os::naked_short_sleep(1);
4886         } else {
4887           os::naked_yield();
4888           ++Yields;
4889         }
4890       } else {
4891         SpinPause();
4892       }
4893     }
4894     if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4895   }
4896 }
4897 
4898 void Thread::SpinRelease(volatile int * adr) {
4899   assert(*adr != 0, "invariant");
4900   OrderAccess::fence();      // guarantee at least release consistency.
4901   // Roach-motel semantics.
4902   // It's safe if subsequent LDs and STs float "up" into the critical section,
4903   // but prior LDs and STs within the critical section can't be allowed
4904   // to reorder or float past the ST that releases the lock.
4905   // Loads and stores in the critical section - which appear in program
4906   // order before the store that releases the lock - must also appear
4907   // before the store that releases the lock in memory visibility order.
4908   // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4909   // the ST of 0 into the lock-word which releases the lock, so fence
4910   // more than covers this on all platforms.
4911   *adr = 0;
4912 }
4913 
4914 // muxAcquire and muxRelease:
4915 //
4916 // *  muxAcquire and muxRelease support a single-word lock-word construct.
4917 //    The LSB of the word is set IFF the lock is held.
4918 //    The remainder of the word points to the head of a singly-linked list
4919 //    of threads blocked on the lock.
4920 //
4921 // *  The current implementation of muxAcquire-muxRelease uses its own
4922 //    dedicated Thread._MuxEvent instance.  If we're interested in
4923 //    minimizing the peak number of extant ParkEvent instances then
4924 //    we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4925 //    as certain invariants were satisfied.  Specifically, care would need
4926 //    to be taken with regards to consuming unpark() "permits".
4927 //    A safe rule of thumb is that a thread would never call muxAcquire()
4928 //    if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4929 //    park().  Otherwise the _ParkEvent park() operation in muxAcquire() could
4930 //    consume an unpark() permit intended for monitorenter, for instance.
4931 //    One way around this would be to widen the restricted-range semaphore
4932 //    implemented in park().  Another alternative would be to provide
4933 //    multiple instances of the PlatformEvent() for each thread.  One
4934 //    instance would be dedicated to muxAcquire-muxRelease, for instance.
4935 //
4936 // *  Usage:
4937 //    -- Only as leaf locks
4938 //    -- for short-term locking only as muxAcquire does not perform
4939 //       thread state transitions.
4940 //
4941 // Alternatives:
4942 // *  We could implement muxAcquire and muxRelease with MCS or CLH locks
4943 //    but with parking or spin-then-park instead of pure spinning.
4944 // *  Use Taura-Oyama-Yonenzawa locks.
4945 // *  It's possible to construct a 1-0 lock if we encode the lockword as
4946 //    (List,LockByte).  Acquire will CAS the full lockword while Release
4947 //    will STB 0 into the LockByte.  The 1-0 scheme admits stranding, so
4948 //    acquiring threads use timers (ParkTimed) to detect and recover from
4949 //    the stranding window.  Thread/Node structures must be aligned on 256-byte
4950 //    boundaries by using placement-new.
4951 // *  Augment MCS with advisory back-link fields maintained with CAS().
4952 //    Pictorially:  LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4953 //    The validity of the backlinks must be ratified before we trust the value.
4954 //    If the backlinks are invalid the exiting thread must back-track through the
4955 //    the forward links, which are always trustworthy.
4956 // *  Add a successor indication.  The LockWord is currently encoded as
4957 //    (List, LOCKBIT:1).  We could also add a SUCCBIT or an explicit _succ variable
4958 //    to provide the usual futile-wakeup optimization.
4959 //    See RTStt for details.
4960 //
4961 
4962 
4963 const intptr_t LOCKBIT = 1;
4964 
4965 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4966   intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4967   if (w == 0) return;
4968   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4969     return;
4970   }
4971 
4972   ParkEvent * const Self = Thread::current()->_MuxEvent;
4973   assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4974   for (;;) {
4975     int its = (os::is_MP() ? 100 : 0) + 1;
4976 
4977     // Optional spin phase: spin-then-park strategy
4978     while (--its >= 0) {
4979       w = *Lock;
4980       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4981         return;
4982       }
4983     }
4984 
4985     Self->reset();
4986     Self->OnList = intptr_t(Lock);
4987     // The following fence() isn't _strictly necessary as the subsequent
4988     // CAS() both serializes execution and ratifies the fetched *Lock value.
4989     OrderAccess::fence();
4990     for (;;) {
4991       w = *Lock;
4992       if ((w & LOCKBIT) == 0) {
4993         if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4994           Self->OnList = 0;   // hygiene - allows stronger asserts
4995           return;
4996         }
4997         continue;      // Interference -- *Lock changed -- Just retry
4998       }
4999       assert(w & LOCKBIT, "invariant");
5000       Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
5001       if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
5002     }
5003 
5004     while (Self->OnList != 0) {
5005       Self->park();
5006     }
5007   }
5008 }
5009 
5010 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
5011   intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
5012   if (w == 0) return;
5013   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
5014     return;
5015   }
5016 
5017   ParkEvent * ReleaseAfter = NULL;
5018   if (ev == NULL) {
5019     ev = ReleaseAfter = ParkEvent::Allocate(NULL);
5020   }
5021   assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
5022   for (;;) {
5023     guarantee(ev->OnList == 0, "invariant");
5024     int its = (os::is_MP() ? 100 : 0) + 1;
5025 
5026     // Optional spin phase: spin-then-park strategy
5027     while (--its >= 0) {
5028       w = *Lock;
5029       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
5030         if (ReleaseAfter != NULL) {
5031           ParkEvent::Release(ReleaseAfter);
5032         }
5033         return;
5034       }
5035     }
5036 
5037     ev->reset();
5038     ev->OnList = intptr_t(Lock);
5039     // The following fence() isn't _strictly necessary as the subsequent
5040     // CAS() both serializes execution and ratifies the fetched *Lock value.
5041     OrderAccess::fence();
5042     for (;;) {
5043       w = *Lock;
5044       if ((w & LOCKBIT) == 0) {
5045         if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
5046           ev->OnList = 0;
5047           // We call ::Release while holding the outer lock, thus
5048           // artificially lengthening the critical section.
5049           // Consider deferring the ::Release() until the subsequent unlock(),
5050           // after we've dropped the outer lock.
5051           if (ReleaseAfter != NULL) {
5052             ParkEvent::Release(ReleaseAfter);
5053           }
5054           return;
5055         }
5056         continue;      // Interference -- *Lock changed -- Just retry
5057       }
5058       assert(w & LOCKBIT, "invariant");
5059       ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
5060       if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
5061     }
5062 
5063     while (ev->OnList != 0) {
5064       ev->park();
5065     }
5066   }
5067 }
5068 
5069 // Release() must extract a successor from the list and then wake that thread.
5070 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
5071 // similar to that used by ParkEvent::Allocate() and ::Release().  DMR-based
5072 // Release() would :
5073 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
5074 // (B) Extract a successor from the private list "in-hand"
5075 // (C) attempt to CAS() the residual back into *Lock over null.
5076 //     If there were any newly arrived threads and the CAS() would fail.
5077 //     In that case Release() would detach the RATs, re-merge the list in-hand
5078 //     with the RATs and repeat as needed.  Alternately, Release() might
5079 //     detach and extract a successor, but then pass the residual list to the wakee.
5080 //     The wakee would be responsible for reattaching and remerging before it
5081 //     competed for the lock.
5082 //
5083 // Both "pop" and DMR are immune from ABA corruption -- there can be
5084 // multiple concurrent pushers, but only one popper or detacher.
5085 // This implementation pops from the head of the list.  This is unfair,
5086 // but tends to provide excellent throughput as hot threads remain hot.
5087 // (We wake recently run threads first).
5088 //
5089 // All paths through muxRelease() will execute a CAS.
5090 // Release consistency -- We depend on the CAS in muxRelease() to provide full
5091 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
5092 // executed within the critical section are complete and globally visible before the
5093 // store (CAS) to the lock-word that releases the lock becomes globally visible.
5094 void Thread::muxRelease(volatile intptr_t * Lock)  {
5095   for (;;) {
5096     const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT);
5097     assert(w & LOCKBIT, "invariant");
5098     if (w == LOCKBIT) return;
5099     ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
5100     assert(List != NULL, "invariant");
5101     assert(List->OnList == intptr_t(Lock), "invariant");
5102     ParkEvent * const nxt = List->ListNext;
5103     guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
5104 
5105     // The following CAS() releases the lock and pops the head element.
5106     // The CAS() also ratifies the previously fetched lock-word value.
5107     if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) {
5108       continue;
5109     }
5110     List->OnList = 0;
5111     OrderAccess::fence();
5112     List->unpark();
5113     return;
5114   }
5115 }
5116 
5117 
5118 void Threads::verify() {
5119   ALL_JAVA_THREADS(p) {
5120     p->verify();
5121   }
5122   VMThread* thread = VMThread::vm_thread();
5123   if (thread != NULL) thread->verify();
5124 }