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