1 /*
   2  * Copyright (c) 1997, 2023, Oracle and/or its affiliates. All rights reserved.
   3  * Copyright (c) 2021, Azul Systems, Inc. All rights reserved.
   4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   5  *
   6  * This code is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License version 2 only, as
   8  * published by the Free Software Foundation.
   9  *
  10  * This code is distributed in the hope that it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  13  * version 2 for more details (a copy is included in the LICENSE file that
  14  * accompanied this code).
  15  *
  16  * You should have received a copy of the GNU General Public License version
  17  * 2 along with this work; if not, write to the Free Software Foundation,
  18  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  19  *
  20  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  21  * or visit www.oracle.com if you need additional information or have any
  22  * questions.
  23  *
  24  */
  25 
  26 #include "precompiled.hpp"
  27 #include "cds/cds_globals.hpp"
  28 #include "cds/metaspaceShared.hpp"
  29 #include "classfile/classLoader.hpp"
  30 #include "classfile/javaClasses.hpp"
  31 #include "classfile/javaThreadStatus.hpp"
  32 #include "classfile/systemDictionary.hpp"
  33 #include "classfile/vmClasses.hpp"
  34 #include "classfile/vmSymbols.hpp"
  35 #include "compiler/compileBroker.hpp"
  36 #include "compiler/compileTask.hpp"
  37 #include "compiler/compilerThread.hpp"
  38 #include "gc/shared/barrierSet.hpp"
  39 #include "gc/shared/barrierSetNMethod.hpp"
  40 #include "gc/shared/gcVMOperations.hpp"
  41 #include "gc/shared/oopStorage.hpp"
  42 #include "gc/shared/oopStorageSet.hpp"
  43 #include "gc/shared/stringdedup/stringDedup.hpp"
  44 #include "jfr/jfrEvents.hpp"
  45 #include "jvm.h"
  46 #include "jvmtifiles/jvmtiEnv.hpp"
  47 #include "logging/log.hpp"
  48 #include "logging/logAsyncWriter.hpp"
  49 #include "logging/logConfiguration.hpp"
  50 #include "memory/allocation.inline.hpp"
  51 #include "memory/iterator.hpp"
  52 #include "memory/oopFactory.hpp"
  53 #include "memory/resourceArea.hpp"
  54 #include "memory/universe.hpp"
  55 #include "oops/instanceKlass.hpp"
  56 #include "oops/klass.inline.hpp"
  57 #include "oops/oop.inline.hpp"
  58 #include "oops/symbol.hpp"
  59 #include "prims/jvm_misc.hpp"
  60 #include "runtime/arguments.hpp"
  61 #include "runtime/fieldDescriptor.inline.hpp"
  62 #include "runtime/flags/jvmFlagLimit.hpp"
  63 #include "runtime/handles.inline.hpp"
  64 #include "runtime/globals.hpp"
  65 #include "runtime/interfaceSupport.inline.hpp"
  66 #include "runtime/java.hpp"
  67 #include "runtime/javaCalls.hpp"
  68 #include "runtime/javaThread.inline.hpp"
  69 #include "runtime/jniHandles.inline.hpp"
  70 #include "runtime/jniPeriodicChecker.hpp"
  71 #include "runtime/monitorDeflationThread.hpp"
  72 #include "runtime/mutexLocker.hpp"
  73 #include "runtime/nonJavaThread.hpp"
  74 #include "runtime/objectMonitor.inline.hpp"
  75 #include "runtime/osThread.hpp"
  76 #include "runtime/safepoint.hpp"
  77 #include "runtime/safepointMechanism.inline.hpp"
  78 #include "runtime/safepointVerifiers.hpp"
  79 #include "runtime/serviceThread.hpp"
  80 #include "runtime/sharedRuntime.hpp"
  81 #include "runtime/statSampler.hpp"
  82 #include "runtime/stubCodeGenerator.hpp"
  83 #include "runtime/thread.inline.hpp"
  84 #include "runtime/threads.hpp"
  85 #include "runtime/threadSMR.inline.hpp"
  86 #include "runtime/timer.hpp"
  87 #include "runtime/timerTrace.hpp"
  88 #include "runtime/vmOperations.hpp"
  89 #include "runtime/vm_version.hpp"
  90 #include "services/attachListener.hpp"
  91 #include "services/management.hpp"
  92 #include "services/memTracker.hpp"
  93 #include "services/threadIdTable.hpp"
  94 #include "services/threadService.hpp"
  95 #include "utilities/dtrace.hpp"
  96 #include "utilities/events.hpp"
  97 #include "utilities/macros.hpp"
  98 #include "utilities/systemMemoryBarrier.hpp"
  99 #include "utilities/vmError.hpp"
 100 #if INCLUDE_JVMCI
 101 #include "jvmci/jvmci.hpp"
 102 #include "jvmci/jvmciEnv.hpp"
 103 #endif
 104 #ifdef COMPILER2
 105 #include "opto/idealGraphPrinter.hpp"
 106 #endif
 107 #if INCLUDE_RTM_OPT
 108 #include "runtime/rtmLocking.hpp"
 109 #endif
 110 #if INCLUDE_JFR
 111 #include "jfr/jfr.hpp"
 112 #endif
 113 
 114 // Initialization after module runtime initialization
 115 void universe_post_module_init();  // must happen after call_initPhase2
 116 
 117 
 118 static void initialize_class(Symbol* class_name, TRAPS) {
 119   Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
 120   InstanceKlass::cast(klass)->initialize(CHECK);
 121 }
 122 
 123 
 124 // Creates the initial ThreadGroup
 125 static Handle create_initial_thread_group(TRAPS) {
 126   Handle system_instance = JavaCalls::construct_new_instance(
 127                             vmClasses::ThreadGroup_klass(),
 128                             vmSymbols::void_method_signature(),
 129                             CHECK_NH);
 130   Universe::set_system_thread_group(system_instance());
 131 
 132   Handle string = java_lang_String::create_from_str("main", CHECK_NH);
 133   Handle main_instance = JavaCalls::construct_new_instance(
 134                             vmClasses::ThreadGroup_klass(),
 135                             vmSymbols::threadgroup_string_void_signature(),
 136                             system_instance,
 137                             string,
 138                             CHECK_NH);
 139   return main_instance;
 140 }
 141 
 142 // Creates the initial Thread, and sets it to running.
 143 static void create_initial_thread(Handle thread_group, JavaThread* thread,
 144                                  TRAPS) {
 145   InstanceKlass* ik = vmClasses::Thread_klass();
 146   assert(ik->is_initialized(), "must be");
 147   instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
 148 
 149   // Cannot use JavaCalls::construct_new_instance because the java.lang.Thread
 150   // constructor calls Thread.current(), which must be set here for the
 151   // initial thread.
 152   java_lang_Thread::set_thread(thread_oop(), thread);
 153   thread->set_threadOopHandles(thread_oop());
 154 
 155   Handle string = java_lang_String::create_from_str("main", CHECK);
 156 
 157   JavaValue result(T_VOID);
 158   JavaCalls::call_special(&result, thread_oop,
 159                           ik,
 160                           vmSymbols::object_initializer_name(),
 161                           vmSymbols::threadgroup_string_void_signature(),
 162                           thread_group,
 163                           string,
 164                           CHECK);
 165 
 166   // Set thread status to running since main thread has
 167   // been started and running.
 168   java_lang_Thread::set_thread_status(thread_oop(),
 169                                       JavaThreadStatus::RUNNABLE);
 170 }
 171 
 172 // Extract version and vendor specific information from
 173 // java.lang.VersionProps fields.
 174 // Returned char* is allocated in the thread's resource area
 175 // so must be copied for permanency.
 176 static const char* get_java_version_info(InstanceKlass* ik,
 177                                          Symbol* field_name) {
 178   fieldDescriptor fd;
 179   bool found = ik != nullptr &&
 180                ik->find_local_field(field_name,
 181                                     vmSymbols::string_signature(), &fd);
 182   if (found) {
 183     oop name_oop = ik->java_mirror()->obj_field(fd.offset());
 184     if (name_oop == nullptr) {
 185       return nullptr;
 186     }
 187     const char* name = java_lang_String::as_utf8_string(name_oop);
 188     return name;
 189   } else {
 190     return nullptr;
 191   }
 192 }
 193 
 194 // ======= Threads ========
 195 
 196 // The Threads class links together all active threads, and provides
 197 // operations over all threads. It is protected by the Threads_lock,
 198 // which is also used in other global contexts like safepointing.
 199 // ThreadsListHandles are used to safely perform operations on one
 200 // or more threads without the risk of the thread exiting during the
 201 // operation.
 202 //
 203 // Note: The Threads_lock is currently more widely used than we
 204 // would like. We are actively migrating Threads_lock uses to other
 205 // mechanisms in order to reduce Threads_lock contention.
 206 
 207 int         Threads::_number_of_threads = 0;
 208 int         Threads::_number_of_non_daemon_threads = 0;
 209 int         Threads::_return_code = 0;
 210 uintx       Threads::_thread_claim_token = 1; // Never zero.
 211 
 212 #ifdef ASSERT
 213 bool        Threads::_vm_complete = false;
 214 #endif
 215 
 216 // General purpose hook into Java code, run once when the VM is initialized.
 217 // The Java library method itself may be changed independently from the VM.
 218 static void call_postVMInitHook(TRAPS) {
 219   Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
 220   if (klass != nullptr) {
 221     JavaValue result(T_VOID);
 222     JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
 223                            vmSymbols::void_method_signature(),
 224                            CHECK);
 225   }
 226 }
 227 
 228 // All NonJavaThreads (i.e., every non-JavaThread in the system).
 229 void Threads::non_java_threads_do(ThreadClosure* tc) {
 230   NoSafepointVerifier nsv;
 231   for (NonJavaThread::Iterator njti; !njti.end(); njti.step()) {
 232     tc->do_thread(njti.current());
 233   }
 234 }
 235 
 236 // All JavaThreads
 237 #define ALL_JAVA_THREADS(X) \
 238   for (JavaThread* X : *ThreadsSMRSupport::get_java_thread_list())
 239 
 240 // All JavaThreads
 241 void Threads::java_threads_do(ThreadClosure* tc) {
 242   assert_locked_or_safepoint(Threads_lock);
 243   // ALL_JAVA_THREADS iterates through all JavaThreads.
 244   ALL_JAVA_THREADS(p) {
 245     tc->do_thread(p);
 246   }
 247 }
 248 
 249 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system).
 250 void Threads::threads_do(ThreadClosure* tc) {
 251   assert_locked_or_safepoint(Threads_lock);
 252   java_threads_do(tc);
 253   non_java_threads_do(tc);
 254 }
 255 
 256 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
 257   assert_at_safepoint();
 258 
 259   uintx claim_token = Threads::thread_claim_token();
 260   ALL_JAVA_THREADS(p) {
 261     if (p->claim_threads_do(is_par, claim_token)) {
 262       tc->do_thread(p);
 263     }
 264   }
 265   for (NonJavaThread::Iterator njti; !njti.end(); njti.step()) {
 266     Thread* current = njti.current();
 267     if (current->claim_threads_do(is_par, claim_token)) {
 268       tc->do_thread(current);
 269     }
 270   }
 271 }
 272 
 273 // The system initialization in the library has three phases.
 274 //
 275 // Phase 1: java.lang.System class initialization
 276 //     java.lang.System is a primordial class loaded and initialized
 277 //     by the VM early during startup.  java.lang.System.<clinit>
 278 //     only does registerNatives and keeps the rest of the class
 279 //     initialization work later until thread initialization completes.
 280 //
 281 //     System.initPhase1 initializes the system properties, the static
 282 //     fields in, out, and err. Set up java signal handlers, OS-specific
 283 //     system settings, and thread group of the main thread.
 284 static void call_initPhase1(TRAPS) {
 285   Klass* klass = vmClasses::System_klass();
 286   JavaValue result(T_VOID);
 287   JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
 288                                          vmSymbols::void_method_signature(), CHECK);
 289 }
 290 
 291 // Phase 2. Module system initialization
 292 //     This will initialize the module system.  Only java.base classes
 293 //     can be loaded until phase 2 completes.
 294 //
 295 //     Call System.initPhase2 after the compiler initialization and jsr292
 296 //     classes get initialized because module initialization runs a lot of java
 297 //     code, that for performance reasons, should be compiled.  Also, this will
 298 //     enable the startup code to use lambda and other language features in this
 299 //     phase and onward.
 300 //
 301 //     After phase 2, The VM will begin search classes from -Xbootclasspath/a.
 302 static void call_initPhase2(TRAPS) {
 303   TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
 304 
 305   Klass* klass = vmClasses::System_klass();
 306 
 307   JavaValue result(T_INT);
 308   JavaCallArguments args;
 309   args.push_int(DisplayVMOutputToStderr);
 310   args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
 311   JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
 312                                          vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
 313   if (result.get_jint() != JNI_OK) {
 314     vm_exit_during_initialization(); // no message or exception
 315   }
 316 
 317   universe_post_module_init();
 318 }
 319 
 320 // Phase 3. final setup - set security manager, system class loader and TCCL
 321 //
 322 //     This will instantiate and set the security manager, set the system class
 323 //     loader as well as the thread context class loader.  The security manager
 324 //     and system class loader may be a custom class loaded from -Xbootclasspath/a,
 325 //     other modules or the application's classpath.
 326 static void call_initPhase3(TRAPS) {
 327   Klass* klass = vmClasses::System_klass();
 328   JavaValue result(T_VOID);
 329   JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
 330                                          vmSymbols::void_method_signature(), CHECK);
 331 }
 332 
 333 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
 334   TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
 335 
 336   if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
 337     create_vm_init_libraries();
 338   }
 339 
 340   initialize_class(vmSymbols::java_lang_String(), CHECK);
 341 
 342   // Inject CompactStrings value after the static initializers for String ran.
 343   java_lang_String::set_compact_strings(CompactStrings);
 344 
 345   // Initialize java_lang.System (needed before creating the thread)
 346   initialize_class(vmSymbols::java_lang_System(), CHECK);
 347   // The VM creates & returns objects of this class. Make sure it's initialized.
 348   initialize_class(vmSymbols::java_lang_Class(), CHECK);
 349   initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
 350   Handle thread_group = create_initial_thread_group(CHECK);
 351   Universe::set_main_thread_group(thread_group());
 352   initialize_class(vmSymbols::java_lang_Thread(), CHECK);
 353   create_initial_thread(thread_group, main_thread, CHECK);
 354 
 355   // The VM creates objects of this class.
 356   initialize_class(vmSymbols::java_lang_Module(), CHECK);
 357 
 358 #ifdef ASSERT
 359   InstanceKlass *k = vmClasses::UnsafeConstants_klass();
 360   assert(k->is_not_initialized(), "UnsafeConstants should not already be initialized");
 361 #endif
 362 
 363   // initialize the hardware-specific constants needed by Unsafe
 364   initialize_class(vmSymbols::jdk_internal_misc_UnsafeConstants(), CHECK);
 365   jdk_internal_misc_UnsafeConstants::set_unsafe_constants();
 366 
 367   // The VM preresolves methods to these classes. Make sure that they get initialized
 368   initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
 369   initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
 370 
 371   // Phase 1 of the system initialization in the library, java.lang.System class initialization
 372   call_initPhase1(CHECK);
 373 
 374   // Get the Java runtime name, version, and vendor info after java.lang.System is initialized.
 375   // Some values are actually configure-time constants but some can be set via the jlink tool and
 376   // so must be read dynamically. We treat them all the same.
 377   InstanceKlass* ik = SystemDictionary::find_instance_klass(THREAD, vmSymbols::java_lang_VersionProps(),
 378                                                             Handle(), Handle());
 379   {
 380     ResourceMark rm(main_thread);
 381     JDK_Version::set_java_version(get_java_version_info(ik, vmSymbols::java_version_name()));
 382 
 383     JDK_Version::set_runtime_name(get_java_version_info(ik, vmSymbols::java_runtime_name_name()));
 384 
 385     JDK_Version::set_runtime_version(get_java_version_info(ik, vmSymbols::java_runtime_version_name()));
 386 
 387     JDK_Version::set_runtime_vendor_version(get_java_version_info(ik, vmSymbols::java_runtime_vendor_version_name()));
 388 
 389     JDK_Version::set_runtime_vendor_vm_bug_url(get_java_version_info(ik, vmSymbols::java_runtime_vendor_vm_bug_url_name()));
 390   }
 391 
 392   // an instance of OutOfMemory exception has been allocated earlier
 393   initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
 394   initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
 395   initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
 396   initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
 397   initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
 398   initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
 399   initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
 400   initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
 401 }
 402 
 403 void Threads::initialize_jsr292_core_classes(TRAPS) {
 404   TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
 405 
 406   initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
 407   initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
 408   initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
 409   initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
 410 }
 411 
 412 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
 413   extern void JDK_Version_init();
 414 
 415   // Preinitialize version info.
 416   VM_Version::early_initialize();
 417 
 418   // Check version
 419   if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
 420 
 421   // Initialize library-based TLS
 422   ThreadLocalStorage::init();
 423 
 424   // Initialize the output stream module
 425   ostream_init();
 426 
 427   // Process java launcher properties.
 428   Arguments::process_sun_java_launcher_properties(args);
 429 
 430   // Initialize the os module
 431   os::init();
 432 
 433   MACOS_AARCH64_ONLY(os::current_thread_enable_wx(WXWrite));
 434 
 435   // Record VM creation timing statistics
 436   TraceVmCreationTime create_vm_timer;
 437   create_vm_timer.start();
 438 
 439   // Initialize system properties.
 440   Arguments::init_system_properties();
 441 
 442   // So that JDK version can be used as a discriminator when parsing arguments
 443   JDK_Version_init();
 444 
 445   // Update/Initialize System properties after JDK version number is known
 446   Arguments::init_version_specific_system_properties();
 447 
 448   // Make sure to initialize log configuration *before* parsing arguments
 449   LogConfiguration::initialize(create_vm_timer.begin_time());
 450 
 451   // Parse arguments
 452   // Note: this internally calls os::init_container_support()
 453   jint parse_result = Arguments::parse(args);
 454   if (parse_result != JNI_OK) return parse_result;
 455 
 456   // Initialize NMT right after argument parsing to keep the pre-NMT-init window small.
 457   MemTracker::initialize();
 458 
 459   os::init_before_ergo();
 460 
 461   jint ergo_result = Arguments::apply_ergo();
 462   if (ergo_result != JNI_OK) return ergo_result;
 463 
 464   // Final check of all ranges after ergonomics which may change values.
 465   if (!JVMFlagLimit::check_all_ranges()) {
 466     return JNI_EINVAL;
 467   }
 468 
 469   // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
 470   bool constraint_result = JVMFlagLimit::check_all_constraints(JVMFlagConstraintPhase::AfterErgo);
 471   if (!constraint_result) {
 472     return JNI_EINVAL;
 473   }
 474 
 475   if (PauseAtStartup) {
 476     os::pause();
 477   }
 478 
 479   HOTSPOT_VM_INIT_BEGIN();
 480 
 481   // Timing (must come after argument parsing)
 482   TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
 483 
 484   // Initialize the os module after parsing the args
 485   jint os_init_2_result = os::init_2();
 486   if (os_init_2_result != JNI_OK) return os_init_2_result;
 487 
 488 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT
 489   // Initialize assert poison page mechanism.
 490   if (ShowRegistersOnAssert) {
 491     initialize_assert_poison();
 492   }
 493 #endif // CAN_SHOW_REGISTERS_ON_ASSERT
 494 
 495   SafepointMechanism::initialize();
 496 
 497   jint adjust_after_os_result = Arguments::adjust_after_os();
 498   if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
 499 
 500   // Initialize output stream logging
 501   ostream_init_log();
 502 
 503   // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
 504   // Must be before create_vm_init_agents()
 505   if (Arguments::init_libraries_at_startup()) {
 506     convert_vm_init_libraries_to_agents();
 507   }
 508 
 509   // Launch -agentlib/-agentpath and converted -Xrun agents
 510   if (Arguments::init_agents_at_startup()) {
 511     create_vm_init_agents();
 512   }
 513 
 514   // Initialize Threads state
 515   _number_of_threads = 0;
 516   _number_of_non_daemon_threads = 0;
 517 
 518   // Initialize global data structures and create system classes in heap
 519   vm_init_globals();
 520 
 521 #if INCLUDE_JVMCI
 522   if (JVMCICounterSize > 0) {
 523     JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtJVMCI);
 524     memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
 525   } else {
 526     JavaThread::_jvmci_old_thread_counters = nullptr;
 527   }
 528 #endif // INCLUDE_JVMCI
 529 
 530   // Initialize OopStorage for threadObj
 531   JavaThread::_thread_oop_storage = OopStorageSet::create_strong("Thread OopStorage", mtThread);
 532 
 533   // Attach the main thread to this os thread
 534   JavaThread* main_thread = new JavaThread();
 535   main_thread->set_thread_state(_thread_in_vm);
 536   main_thread->initialize_thread_current();
 537   // must do this before set_active_handles
 538   main_thread->record_stack_base_and_size();
 539   main_thread->register_thread_stack_with_NMT();
 540   main_thread->set_active_handles(JNIHandleBlock::allocate_block());
 541   MACOS_AARCH64_ONLY(main_thread->init_wx());
 542 
 543   if (!main_thread->set_as_starting_thread()) {
 544     vm_shutdown_during_initialization(
 545                                       "Failed necessary internal allocation. Out of swap space");
 546     main_thread->smr_delete();
 547     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
 548     return JNI_ENOMEM;
 549   }
 550 
 551   // Enable guard page *after* os::create_main_thread(), otherwise it would
 552   // crash Linux VM, see notes in os_linux.cpp.
 553   main_thread->stack_overflow_state()->create_stack_guard_pages();
 554 
 555   if (UseSystemMemoryBarrier) {
 556     if (!SystemMemoryBarrier::initialize()) {
 557       vm_shutdown_during_initialization("Failed to initialize the requested system memory barrier synchronization.");
 558       return JNI_EINVAL;
 559     }
 560     log_debug(os)("Using experimental system memory barrier synchronization");
 561   }
 562 
 563   // Initialize Java-Level synchronization subsystem
 564   ObjectMonitor::Initialize();
 565   ObjectSynchronizer::initialize();
 566 
 567   // Initialize global modules
 568   jint status = init_globals();
 569   if (status != JNI_OK) {
 570     main_thread->smr_delete();
 571     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
 572     return status;
 573   }
 574 
 575   JFR_ONLY(Jfr::on_create_vm_1();)
 576 
 577   // Should be done after the heap is fully created
 578   main_thread->cache_global_variables();
 579 
 580   { MutexLocker mu(Threads_lock);
 581     Threads::add(main_thread);
 582   }
 583 
 584   // Any JVMTI raw monitors entered in onload will transition into
 585   // real raw monitor. VM is setup enough here for raw monitor enter.
 586   JvmtiExport::transition_pending_onload_raw_monitors();
 587 
 588   // Create the VMThread
 589   { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
 590 
 591     VMThread::create();
 592     VMThread* vmthread = VMThread::vm_thread();
 593 
 594     if (!os::create_thread(vmthread, os::vm_thread)) {
 595       vm_exit_during_initialization("Cannot create VM thread. "
 596                                     "Out of system resources.");
 597     }
 598 
 599     // Wait for the VM thread to become ready, and VMThread::run to initialize
 600     // Monitors can have spurious returns, must always check another state flag
 601     {
 602       MonitorLocker ml(Notify_lock);
 603       os::start_thread(vmthread);
 604       while (!vmthread->is_running()) {
 605         ml.wait();
 606       }
 607     }
 608   }
 609 
 610   assert(Universe::is_fully_initialized(), "not initialized");
 611   if (VerifyDuringStartup) {
 612     // Make sure we're starting with a clean slate.
 613     VM_Verify verify_op;
 614     VMThread::execute(&verify_op);
 615   }
 616 
 617   // We need this to update the java.vm.info property in case any flags used
 618   // to initially define it have been changed. This is needed for both CDS
 619   // since UseSharedSpaces may be changed after java.vm.info
 620   // is initially computed. See Abstract_VM_Version::vm_info_string().
 621   // This update must happen before we initialize the java classes, but
 622   // after any initialization logic that might modify the flags.
 623   Arguments::update_vm_info_property(VM_Version::vm_info_string());
 624 
 625   JavaThread* THREAD = JavaThread::current(); // For exception macros.
 626   HandleMark hm(THREAD);
 627 
 628   // Always call even when there are not JVMTI environments yet, since environments
 629   // may be attached late and JVMTI must track phases of VM execution
 630   JvmtiExport::enter_early_start_phase();
 631 
 632   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
 633   JvmtiExport::post_early_vm_start();
 634 
 635   initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
 636 
 637   quicken_jni_functions();
 638 
 639   // No more stub generation allowed after that point.
 640   StubCodeDesc::freeze();
 641 
 642   // Set flag that basic initialization has completed. Used by exceptions and various
 643   // debug stuff, that does not work until all basic classes have been initialized.
 644   set_init_completed();
 645 
 646   LogConfiguration::post_initialize();
 647   Metaspace::post_initialize();
 648   MutexLocker::post_initialize();
 649 
 650   HOTSPOT_VM_INIT_END();
 651 
 652   // record VM initialization completion time
 653 #if INCLUDE_MANAGEMENT
 654   Management::record_vm_init_completed();
 655 #endif // INCLUDE_MANAGEMENT
 656 
 657   // Signal Dispatcher needs to be started before VMInit event is posted
 658   os::initialize_jdk_signal_support(CHECK_JNI_ERR);
 659 
 660   // Start Attach Listener if +StartAttachListener or it can't be started lazily
 661   if (!DisableAttachMechanism) {
 662     AttachListener::vm_start();
 663     if (StartAttachListener || AttachListener::init_at_startup()) {
 664       AttachListener::init();
 665     }
 666   }
 667 
 668   // Launch -Xrun agents
 669   // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
 670   // back-end can launch with -Xdebug -Xrunjdwp.
 671   if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
 672     create_vm_init_libraries();
 673   }
 674 
 675   Chunk::start_chunk_pool_cleaner_task();
 676 
 677   // Start the service thread
 678   // The service thread enqueues JVMTI deferred events and does various hashtable
 679   // and other cleanups.  Needs to start before the compilers start posting events.
 680   ServiceThread::initialize();
 681 
 682   // Start the monitor deflation thread:
 683   MonitorDeflationThread::initialize();
 684 
 685   // initialize compiler(s)
 686 #if defined(COMPILER1) || COMPILER2_OR_JVMCI
 687 #if INCLUDE_JVMCI
 688   bool force_JVMCI_intialization = false;
 689   if (EnableJVMCI) {
 690     // Initialize JVMCI eagerly when it is explicitly requested.
 691     // Or when JVMCILibDumpJNIConfig or JVMCIPrintProperties is enabled.
 692     force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties || JVMCILibDumpJNIConfig;
 693 
 694     if (!force_JVMCI_intialization) {
 695       // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
 696       // compilations via JVMCI will not actually block until JVMCI is initialized.
 697       force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
 698     }
 699   }
 700 #endif
 701   CompileBroker::compilation_init_phase1(CHECK_JNI_ERR);
 702   // Postpone completion of compiler initialization to after JVMCI
 703   // is initialized to avoid timeouts of blocking compilations.
 704   if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) {
 705     CompileBroker::compilation_init_phase2();
 706   }
 707 #endif
 708 
 709   // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
 710   // It is done after compilers are initialized, because otherwise compilations of
 711   // signature polymorphic MH intrinsics can be missed
 712   // (see SystemDictionary::find_method_handle_intrinsic).
 713   initialize_jsr292_core_classes(CHECK_JNI_ERR);
 714 
 715   // This will initialize the module system.  Only java.base classes can be
 716   // loaded until phase 2 completes
 717   call_initPhase2(CHECK_JNI_ERR);
 718 
 719   JFR_ONLY(Jfr::on_create_vm_2();)
 720 
 721   // Always call even when there are not JVMTI environments yet, since environments
 722   // may be attached late and JVMTI must track phases of VM execution
 723   JvmtiExport::enter_start_phase();
 724 
 725   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
 726   JvmtiExport::post_vm_start();
 727 
 728   // Final system initialization including security manager and system class loader
 729   call_initPhase3(CHECK_JNI_ERR);
 730 
 731   // cache the system and platform class loaders
 732   SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
 733 
 734 #if INCLUDE_CDS
 735   // capture the module path info from the ModuleEntryTable
 736   ClassLoader::initialize_module_path(THREAD);
 737   if (HAS_PENDING_EXCEPTION) {
 738     java_lang_Throwable::print(PENDING_EXCEPTION, tty);
 739     vm_exit_during_initialization("ClassLoader::initialize_module_path() failed unexpectedly");
 740   }
 741 #endif
 742 
 743 #if INCLUDE_JVMCI
 744   if (force_JVMCI_intialization) {
 745     JVMCI::initialize_compiler(CHECK_JNI_ERR);
 746     CompileBroker::compilation_init_phase2();
 747   }
 748 #endif
 749 
 750   // Always call even when there are not JVMTI environments yet, since environments
 751   // may be attached late and JVMTI must track phases of VM execution
 752   JvmtiExport::enter_live_phase();
 753 
 754   // Make perfmemory accessible
 755   PerfMemory::set_accessible(true);
 756 
 757   // Notify JVMTI agents that VM initialization is complete - nop if no agents.
 758   JvmtiExport::post_vm_initialized();
 759 
 760   JFR_ONLY(Jfr::on_create_vm_3();)
 761 
 762 #if INCLUDE_MANAGEMENT
 763   Management::initialize(THREAD);
 764 
 765   if (HAS_PENDING_EXCEPTION) {
 766     // management agent fails to start possibly due to
 767     // configuration problem and is responsible for printing
 768     // stack trace if appropriate. Simply exit VM.
 769     vm_exit(1);
 770   }
 771 #endif // INCLUDE_MANAGEMENT
 772 
 773   StatSampler::engage();
 774   if (CheckJNICalls)                  JniPeriodicChecker::engage();
 775 
 776 #if INCLUDE_RTM_OPT
 777   RTMLockingCounters::init();
 778 #endif
 779 
 780   call_postVMInitHook(THREAD);
 781   // The Java side of PostVMInitHook.run must deal with all
 782   // exceptions and provide means of diagnosis.
 783   if (HAS_PENDING_EXCEPTION) {
 784     CLEAR_PENDING_EXCEPTION;
 785   }
 786 
 787   {
 788     MutexLocker ml(PeriodicTask_lock);
 789     // Make sure the WatcherThread can be started by WatcherThread::start()
 790     // or by dynamic enrollment.
 791     WatcherThread::make_startable();
 792     // Start up the WatcherThread if there are any periodic tasks
 793     // NOTE:  All PeriodicTasks should be registered by now. If they
 794     //   aren't, late joiners might appear to start slowly (we might
 795     //   take a while to process their first tick).
 796     if (PeriodicTask::num_tasks() > 0) {
 797       WatcherThread::start();
 798     }
 799   }
 800 
 801   create_vm_timer.end();
 802 #ifdef ASSERT
 803   _vm_complete = true;
 804 #endif
 805 
 806   if (DumpSharedSpaces) {
 807     MetaspaceShared::preload_and_dump();
 808     ShouldNotReachHere();
 809   }
 810 
 811   return JNI_OK;
 812 }
 813 
 814 // type for the Agent_OnLoad and JVM_OnLoad entry points
 815 extern "C" {
 816   typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
 817 }
 818 // Find a command line agent library and return its entry point for
 819 //         -agentlib:  -agentpath:   -Xrun
 820 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
 821 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
 822                                     const char *on_load_symbols[],
 823                                     size_t num_symbol_entries) {
 824   OnLoadEntry_t on_load_entry = nullptr;
 825   void *library = nullptr;
 826 
 827   if (!agent->valid()) {
 828     char buffer[JVM_MAXPATHLEN];
 829     char ebuf[1024] = "";
 830     const char *name = agent->name();
 831     const char *msg = "Could not find agent library ";
 832 
 833     // First check to see if agent is statically linked into executable
 834     if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
 835       library = agent->os_lib();
 836     } else if (agent->is_absolute_path()) {
 837       library = os::dll_load(name, ebuf, sizeof ebuf);
 838       if (library == nullptr) {
 839         const char *sub_msg = " in absolute path, with error: ";
 840         size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
 841         char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
 842         jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
 843         // If we can't find the agent, exit.
 844         vm_exit_during_initialization(buf, nullptr);
 845         FREE_C_HEAP_ARRAY(char, buf);
 846       }
 847     } else {
 848       // Try to load the agent from the standard dll directory
 849       if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
 850                              name)) {
 851         library = os::dll_load(buffer, ebuf, sizeof ebuf);
 852       }
 853       if (library == nullptr) { // Try the library path directory.
 854         if (os::dll_build_name(buffer, sizeof(buffer), name)) {
 855           library = os::dll_load(buffer, ebuf, sizeof ebuf);
 856         }
 857         if (library == nullptr) {
 858           const char *sub_msg = " on the library path, with error: ";
 859           const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image.";
 860 
 861           size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) +
 862                        strlen(ebuf) + strlen(sub_msg2) + 1;
 863           char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
 864           if (!agent->is_instrument_lib()) {
 865             jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
 866           } else {
 867             jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2);
 868           }
 869           // If we can't find the agent, exit.
 870           vm_exit_during_initialization(buf, nullptr);
 871           FREE_C_HEAP_ARRAY(char, buf);
 872         }
 873       }
 874     }
 875     agent->set_os_lib(library);
 876     agent->set_valid();
 877   }
 878 
 879   // Find the OnLoad function.
 880   on_load_entry =
 881     CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
 882                                                           false,
 883                                                           on_load_symbols,
 884                                                           num_symbol_entries));
 885   return on_load_entry;
 886 }
 887 
 888 // Find the JVM_OnLoad entry point
 889 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
 890   const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
 891   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
 892 }
 893 
 894 // Find the Agent_OnLoad entry point
 895 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
 896   const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
 897   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
 898 }
 899 
 900 // For backwards compatibility with -Xrun
 901 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
 902 // treated like -agentpath:
 903 // Must be called before agent libraries are created
 904 void Threads::convert_vm_init_libraries_to_agents() {
 905   AgentLibrary* agent;
 906   AgentLibrary* next;
 907 
 908   for (agent = Arguments::libraries(); agent != nullptr; agent = next) {
 909     next = agent->next();  // cache the next agent now as this agent may get moved off this list
 910     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
 911 
 912     // If there is an JVM_OnLoad function it will get called later,
 913     // otherwise see if there is an Agent_OnLoad
 914     if (on_load_entry == nullptr) {
 915       on_load_entry = lookup_agent_on_load(agent);
 916       if (on_load_entry != nullptr) {
 917         // switch it to the agent list -- so that Agent_OnLoad will be called,
 918         // JVM_OnLoad won't be attempted and Agent_OnUnload will
 919         Arguments::convert_library_to_agent(agent);
 920       } else {
 921         vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
 922       }
 923     }
 924   }
 925 }
 926 
 927 // Create agents for -agentlib:  -agentpath:  and converted -Xrun
 928 // Invokes Agent_OnLoad
 929 // Called very early -- before JavaThreads exist
 930 void Threads::create_vm_init_agents() {
 931   extern struct JavaVM_ main_vm;
 932   AgentLibrary* agent;
 933 
 934   JvmtiExport::enter_onload_phase();
 935 
 936   for (agent = Arguments::agents(); agent != nullptr; agent = agent->next()) {
 937     // CDS dumping does not support native JVMTI agent.
 938     // CDS dumping supports Java agent if the AllowArchivingWithJavaAgent diagnostic option is specified.
 939     if (Arguments::is_dumping_archive()) {
 940       if(!agent->is_instrument_lib()) {
 941         vm_exit_during_cds_dumping("CDS dumping does not support native JVMTI agent, name", agent->name());
 942       } else if (!AllowArchivingWithJavaAgent) {
 943         vm_exit_during_cds_dumping(
 944           "Must enable AllowArchivingWithJavaAgent in order to run Java agent during CDS dumping");
 945       }
 946     }
 947 
 948     OnLoadEntry_t  on_load_entry = lookup_agent_on_load(agent);
 949 
 950     if (on_load_entry != nullptr) {
 951       // Invoke the Agent_OnLoad function
 952       jint err = (*on_load_entry)(&main_vm, agent->options(), nullptr);
 953       if (err != JNI_OK) {
 954         vm_exit_during_initialization("agent library failed to init", agent->name());
 955       }
 956     } else {
 957       vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
 958     }
 959   }
 960 
 961   JvmtiExport::enter_primordial_phase();
 962 }
 963 
 964 extern "C" {
 965   typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
 966 }
 967 
 968 void Threads::shutdown_vm_agents() {
 969   // Send any Agent_OnUnload notifications
 970   const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
 971   size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
 972   extern struct JavaVM_ main_vm;
 973   for (AgentLibrary* agent = Arguments::agents(); agent != nullptr; agent = agent->next()) {
 974 
 975     // Find the Agent_OnUnload function.
 976     Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
 977                                                    os::find_agent_function(agent,
 978                                                    false,
 979                                                    on_unload_symbols,
 980                                                    num_symbol_entries));
 981 
 982     // Invoke the Agent_OnUnload function
 983     if (unload_entry != nullptr) {
 984       JavaThread* thread = JavaThread::current();
 985       ThreadToNativeFromVM ttn(thread);
 986       HandleMark hm(thread);
 987       (*unload_entry)(&main_vm);
 988     }
 989   }
 990 }
 991 
 992 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
 993 // Invokes JVM_OnLoad
 994 void Threads::create_vm_init_libraries() {
 995   extern struct JavaVM_ main_vm;
 996   AgentLibrary* agent;
 997 
 998   for (agent = Arguments::libraries(); agent != nullptr; agent = agent->next()) {
 999     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
1000 
1001     if (on_load_entry != nullptr) {
1002       // Invoke the JVM_OnLoad function
1003       JavaThread* thread = JavaThread::current();
1004       ThreadToNativeFromVM ttn(thread);
1005       HandleMark hm(thread);
1006       jint err = (*on_load_entry)(&main_vm, agent->options(), nullptr);
1007       if (err != JNI_OK) {
1008         vm_exit_during_initialization("-Xrun library failed to init", agent->name());
1009       }
1010     } else {
1011       vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
1012     }
1013   }
1014 }
1015 
1016 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
1017 // the program falls off the end of main(). Another VM exit path is through
1018 // vm_exit() when the program calls System.exit() to return a value or when
1019 // there is a serious error in VM. The two shutdown paths are not exactly
1020 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
1021 // and VM_Exit op at VM level.
1022 //
1023 // Shutdown sequence:
1024 //   + Shutdown native memory tracking if it is on
1025 //   + Wait until we are the last non-daemon thread to execute
1026 //     <-- every thing is still working at this moment -->
1027 //   + Call java.lang.Shutdown.shutdown(), which will invoke Java level
1028 //        shutdown hooks
1029 //   + Call before_exit(), prepare for VM exit
1030 //      > run VM level shutdown hooks (they are registered through JVM_OnExit(),
1031 //        currently the only user of this mechanism is File.deleteOnExit())
1032 //      > stop StatSampler, watcher thread,
1033 //        post thread end and vm death events to JVMTI,
1034 //        stop signal thread
1035 //   + Call JavaThread::exit(), it will:
1036 //      > release JNI handle blocks, remove stack guard pages
1037 //      > remove this thread from Threads list
1038 //     <-- no more Java code from this thread after this point -->
1039 //   + Stop VM thread, it will bring the remaining VM to a safepoint and stop
1040 //     the compiler threads at safepoint
1041 //     <-- do not use anything that could get blocked by Safepoint -->
1042 //   + Disable tracing at JNI/JVM barriers
1043 //   + Set _vm_exited flag for threads that are still running native code
1044 //   + Call exit_globals()
1045 //      > deletes tty
1046 //      > deletes PerfMemory resources
1047 //   + Delete this thread
1048 //   + Return to caller
1049 
1050 void Threads::destroy_vm() {
1051   JavaThread* thread = JavaThread::current();
1052 
1053 #ifdef ASSERT
1054   _vm_complete = false;
1055 #endif
1056   // Wait until we are the last non-daemon thread to execute, or
1057   // if we are a daemon then wait until the last non-daemon thread has
1058   // executed.
1059   bool daemon = java_lang_Thread::is_daemon(thread->threadObj());
1060   int expected = daemon ? 0 : 1;
1061   {
1062     MonitorLocker nu(Threads_lock);
1063     while (Threads::number_of_non_daemon_threads() > expected)
1064       // This wait should make safepoint checks, wait without a timeout.
1065       nu.wait(0);
1066   }
1067 
1068   EventShutdown e;
1069   if (e.should_commit()) {
1070     e.set_reason("No remaining non-daemon Java threads");
1071     e.commit();
1072   }
1073 
1074   // Hang forever on exit if we are reporting an error.
1075   if (ShowMessageBoxOnError && VMError::is_error_reported()) {
1076     os::infinite_sleep();
1077   }
1078   os::wait_for_keypress_at_exit();
1079 
1080   // run Java level shutdown hooks
1081   thread->invoke_shutdown_hooks();
1082 
1083   before_exit(thread);
1084 
1085   thread->exit(true);
1086 
1087   // We are no longer on the main thread list but could still be in a
1088   // secondary list where another thread may try to interact with us.
1089   // So wait until all such interactions are complete before we bring
1090   // the VM to the termination safepoint. Normally this would be done
1091   // using thread->smr_delete() below where we delete the thread, but
1092   // we can't call that after the termination safepoint is active as
1093   // we will deadlock on the Threads_lock. Once all interactions are
1094   // complete it is safe to directly delete the thread at any time.
1095   ThreadsSMRSupport::wait_until_not_protected(thread);
1096 
1097   // Stop VM thread.
1098   {
1099     // 4945125 The vm thread comes to a safepoint during exit.
1100     // GC vm_operations can get caught at the safepoint, and the
1101     // heap is unparseable if they are caught. Grab the Heap_lock
1102     // to prevent this. The GC vm_operations will not be able to
1103     // queue until after the vm thread is dead. After this point,
1104     // we'll never emerge out of the safepoint before the VM exits.
1105     // Assert that the thread is terminated so that acquiring the
1106     // Heap_lock doesn't cause the terminated thread to participate in
1107     // the safepoint protocol.
1108 
1109     assert(thread->is_terminated(), "must be terminated here");
1110     MutexLocker ml(Heap_lock);
1111 
1112     VMThread::wait_for_vm_thread_exit();
1113     assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
1114     VMThread::destroy();
1115   }
1116 
1117   // Now, all Java threads are gone except daemon threads. Daemon threads
1118   // running Java code or in VM are stopped by the Safepoint. However,
1119   // daemon threads executing native code are still running.  But they
1120   // will be stopped at native=>Java/VM barriers. Note that we can't
1121   // simply kill or suspend them, as it is inherently deadlock-prone.
1122 
1123   VM_Exit::set_vm_exited();
1124 
1125   // Clean up ideal graph printers after the VMThread has started
1126   // the final safepoint which will block all the Compiler threads.
1127   // Note that this Thread has already logically exited so the
1128   // clean_up() function's use of a JavaThreadIteratorWithHandle
1129   // would be a problem except set_vm_exited() has remembered the
1130   // shutdown thread which is granted a policy exception.
1131 #if defined(COMPILER2) && !defined(PRODUCT)
1132   IdealGraphPrinter::clean_up();
1133 #endif
1134 
1135   notify_vm_shutdown();
1136 
1137   // exit_globals() will delete tty
1138   exit_globals();
1139 
1140   // Deleting the shutdown thread here is safe. See comment on
1141   // wait_until_not_protected() above.
1142   delete thread;
1143 
1144 #if INCLUDE_JVMCI
1145   if (JVMCICounterSize > 0) {
1146     FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
1147   }
1148 #endif
1149 
1150   LogConfiguration::finalize();
1151 }
1152 
1153 
1154 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
1155   if (version == JNI_VERSION_1_1) return JNI_TRUE;
1156   return is_supported_jni_version(version);
1157 }
1158 
1159 
1160 jboolean Threads::is_supported_jni_version(jint version) {
1161   if (version == JNI_VERSION_1_2) return JNI_TRUE;
1162   if (version == JNI_VERSION_1_4) return JNI_TRUE;
1163   if (version == JNI_VERSION_1_6) return JNI_TRUE;
1164   if (version == JNI_VERSION_1_8) return JNI_TRUE;
1165   if (version == JNI_VERSION_9) return JNI_TRUE;
1166   if (version == JNI_VERSION_10) return JNI_TRUE;
1167   if (version == JNI_VERSION_19) return JNI_TRUE;
1168   if (version == JNI_VERSION_20) return JNI_TRUE;
1169   return JNI_FALSE;
1170 }
1171 
1172 void Threads::add(JavaThread* p, bool force_daemon) {
1173   // The threads lock must be owned at this point
1174   assert(Threads_lock->owned_by_self(), "must have threads lock");
1175 
1176   BarrierSet::barrier_set()->on_thread_attach(p);
1177 
1178   // Once a JavaThread is added to the Threads list, smr_delete() has
1179   // to be used to delete it. Otherwise we can just delete it directly.
1180   p->set_on_thread_list();
1181 
1182   _number_of_threads++;
1183   oop threadObj = p->threadObj();
1184   bool daemon = true;
1185   // Bootstrapping problem: threadObj can be null for initial
1186   // JavaThread (or for threads attached via JNI)
1187   if (!force_daemon &&
1188       (threadObj == nullptr || !java_lang_Thread::is_daemon(threadObj))) {
1189     _number_of_non_daemon_threads++;
1190     daemon = false;
1191   }
1192 
1193   ThreadService::add_thread(p, daemon);
1194 
1195   // Maintain fast thread list
1196   ThreadsSMRSupport::add_thread(p);
1197 
1198   // Increase the ObjectMonitor ceiling for the new thread.
1199   ObjectSynchronizer::inc_in_use_list_ceiling();
1200 
1201   // Possible GC point.
1202   Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
1203 
1204   // Make new thread known to active EscapeBarrier
1205   EscapeBarrier::thread_added(p);
1206 }
1207 
1208 void Threads::remove(JavaThread* p, bool is_daemon) {
1209   // Extra scope needed for Thread_lock, so we can check
1210   // that we do not remove thread without safepoint code notice
1211   { MonitorLocker ml(Threads_lock);
1212 
1213     if (ThreadIdTable::is_initialized()) {
1214       // This cleanup must be done before the current thread's GC barrier
1215       // is detached since we need to touch the threadObj oop.
1216       jlong tid = SharedRuntime::get_java_tid(p);
1217       ThreadIdTable::remove_thread(tid);
1218     }
1219 
1220     // BarrierSet state must be destroyed after the last thread transition
1221     // before the thread terminates. Thread transitions result in calls to
1222     // StackWatermarkSet::on_safepoint(), which performs GC processing,
1223     // requiring the GC state to be alive.
1224     BarrierSet::barrier_set()->on_thread_detach(p);
1225     if (p->is_exiting()) {
1226       // If we got here via JavaThread::exit(), then we remember that the
1227       // thread's GC barrier has been detached. We don't do this when we get
1228       // here from another path, e.g., cleanup_failed_attach_current_thread().
1229       p->set_terminated(JavaThread::_thread_gc_barrier_detached);
1230     }
1231 
1232     assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present");
1233 
1234     // Maintain fast thread list
1235     ThreadsSMRSupport::remove_thread(p);
1236 
1237     _number_of_threads--;
1238     if (!is_daemon) {
1239       _number_of_non_daemon_threads--;
1240 
1241       // If this is the last non-daemon thread then we need to do
1242       // a notify on the Threads_lock so a thread waiting
1243       // on destroy_vm will wake up. But that thread could be a daemon
1244       // or non-daemon, so we notify for both the 0 and 1 case.
1245       if (number_of_non_daemon_threads() <= 1) {
1246         ml.notify_all();
1247       }
1248     }
1249     ThreadService::remove_thread(p, is_daemon);
1250 
1251     // Make sure that safepoint code disregard this thread. This is needed since
1252     // the thread might mess around with locks after this point. This can cause it
1253     // to do callbacks into the safepoint code. However, the safepoint code is not aware
1254     // of this thread since it is removed from the queue.
1255     p->set_terminated(JavaThread::_thread_terminated);
1256 
1257     // Notify threads waiting in EscapeBarriers
1258     EscapeBarrier::thread_removed(p);
1259   } // unlock Threads_lock
1260 
1261   // Reduce the ObjectMonitor ceiling for the exiting thread.
1262   ObjectSynchronizer::dec_in_use_list_ceiling();
1263 
1264   // Since Events::log uses a lock, we grab it outside the Threads_lock
1265   Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
1266 }
1267 
1268 // Operations on the Threads list for GC.  These are not explicitly locked,
1269 // but the garbage collector must provide a safe context for them to run.
1270 // In particular, these things should never be called when the Threads_lock
1271 // is held by some other thread. (Note: the Safepoint abstraction also
1272 // uses the Threads_lock to guarantee this property. It also makes sure that
1273 // all threads gets blocked when exiting or starting).
1274 
1275 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
1276   ALL_JAVA_THREADS(p) {
1277     p->oops_do(f, cf);
1278   }
1279   VMThread::vm_thread()->oops_do(f, cf);
1280 }
1281 
1282 void Threads::change_thread_claim_token() {
1283   if (++_thread_claim_token == 0) {
1284     // On overflow of the token counter, there is a risk of future
1285     // collisions between a new global token value and a stale token
1286     // for a thread, because not all iterations visit all threads.
1287     // (Though it's pretty much a theoretical concern for non-trivial
1288     // token counter sizes.)  To deal with the possibility, reset all
1289     // the thread tokens to zero on global token overflow.
1290     struct ResetClaims : public ThreadClosure {
1291       virtual void do_thread(Thread* t) {
1292         t->claim_threads_do(false, 0);
1293       }
1294     } reset_claims;
1295     Threads::threads_do(&reset_claims);
1296     // On overflow, update the global token to non-zero, to
1297     // avoid the special "never claimed" initial thread value.
1298     _thread_claim_token = 1;
1299   }
1300 }
1301 
1302 #ifdef ASSERT
1303 void assert_thread_claimed(const char* kind, Thread* t, uintx expected) {
1304   const uintx token = t->threads_do_token();
1305   assert(token == expected,
1306          "%s " PTR_FORMAT " has incorrect value " UINTX_FORMAT " != "
1307          UINTX_FORMAT, kind, p2i(t), token, expected);
1308 }
1309 
1310 void Threads::assert_all_threads_claimed() {
1311   ALL_JAVA_THREADS(p) {
1312     assert_thread_claimed("JavaThread", p, _thread_claim_token);
1313   }
1314 
1315   struct NJTClaimedVerifierClosure : public ThreadClosure {
1316     uintx _thread_claim_token;
1317 
1318     NJTClaimedVerifierClosure(uintx thread_claim_token) : ThreadClosure(), _thread_claim_token(thread_claim_token) { }
1319 
1320     virtual void do_thread(Thread* thread) override {
1321       assert_thread_claimed("Non-JavaThread", VMThread::vm_thread(), _thread_claim_token);
1322     }
1323   } tc(_thread_claim_token);
1324 
1325   non_java_threads_do(&tc);
1326 }
1327 #endif // ASSERT
1328 
1329 class ParallelOopsDoThreadClosure : public ThreadClosure {
1330 private:
1331   OopClosure* _f;
1332   CodeBlobClosure* _cf;
1333 public:
1334   ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {}
1335   void do_thread(Thread* t) {
1336     t->oops_do(_f, _cf);
1337   }
1338 };
1339 
1340 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
1341   ParallelOopsDoThreadClosure tc(f, cf);
1342   possibly_parallel_threads_do(is_par, &tc);
1343 }
1344 
1345 void Threads::metadata_do(MetadataClosure* f) {
1346   ALL_JAVA_THREADS(p) {
1347     p->metadata_do(f);
1348   }
1349 }
1350 
1351 class ThreadHandlesClosure : public ThreadClosure {
1352   void (*_f)(Metadata*);
1353  public:
1354   ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
1355   virtual void do_thread(Thread* thread) {
1356     thread->metadata_handles_do(_f);
1357   }
1358 };
1359 
1360 void Threads::metadata_handles_do(void f(Metadata*)) {
1361   // Only walk the Handles in Thread.
1362   ThreadHandlesClosure handles_closure(f);
1363   threads_do(&handles_closure);
1364 }
1365 
1366 // Get count Java threads that are waiting to enter the specified monitor.
1367 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
1368                                                          int count,
1369                                                          address monitor) {
1370   GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
1371 
1372   int i = 0;
1373   for (JavaThread* p : *t_list) {
1374     if (!p->can_call_java()) continue;
1375 
1376     // The first stage of async deflation does not affect any field
1377     // used by this comparison so the ObjectMonitor* is usable here.
1378     address pending = (address)p->current_pending_monitor();
1379     if (pending == monitor) {             // found a match
1380       if (i < count) result->append(p);   // save the first count matches
1381       i++;
1382     }
1383   }
1384 
1385   return result;
1386 }
1387 
1388 
1389 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
1390                                                       address owner) {
1391   // null owner means not locked so we can skip the search
1392   if (owner == nullptr) return nullptr;
1393 
1394   for (JavaThread* p : *t_list) {
1395     // first, see if owner is the address of a Java thread
1396     if (owner == (address)p) return p;
1397   }
1398 
1399   // Cannot assert on lack of success here since this function may be
1400   // used by code that is trying to report useful problem information
1401   // like deadlock detection.
1402   if (UseHeavyMonitors) return nullptr;
1403 
1404   // If we didn't find a matching Java thread and we didn't force use of
1405   // heavyweight monitors, then the owner is the stack address of the
1406   // Lock Word in the owning Java thread's stack.
1407   //
1408   JavaThread* the_owner = nullptr;
1409   for (JavaThread* q : *t_list) {
1410     if (q->is_lock_owned(owner)) {
1411       the_owner = q;
1412       break;
1413     }
1414   }
1415 
1416   // cannot assert on lack of success here; see above comment
1417   return the_owner;
1418 }
1419 
1420 JavaThread* Threads::owning_thread_from_monitor(ThreadsList* t_list, ObjectMonitor* monitor) {
1421   address owner = (address)monitor->owner();
1422   return owning_thread_from_monitor_owner(t_list, owner);
1423 }
1424 
1425 class PrintOnClosure : public ThreadClosure {
1426 private:
1427   outputStream* _st;
1428 
1429 public:
1430   PrintOnClosure(outputStream* st) :
1431       _st(st) {}
1432 
1433   virtual void do_thread(Thread* thread) {
1434     if (thread != nullptr) {
1435       thread->print_on(_st);
1436       _st->cr();
1437     }
1438   }
1439 };
1440 
1441 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
1442 void Threads::print_on(outputStream* st, bool print_stacks,
1443                        bool internal_format, bool print_concurrent_locks,
1444                        bool print_extended_info) {
1445   char buf[32];
1446   st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
1447 
1448   st->print_cr("Full thread dump %s (%s %s):",
1449                VM_Version::vm_name(),
1450                VM_Version::vm_release(),
1451                VM_Version::vm_info_string());
1452   st->cr();
1453 
1454 #if INCLUDE_SERVICES
1455   // Dump concurrent locks
1456   ConcurrentLocksDump concurrent_locks;
1457   if (print_concurrent_locks) {
1458     concurrent_locks.dump_at_safepoint();
1459   }
1460 #endif // INCLUDE_SERVICES
1461 
1462   ThreadsSMRSupport::print_info_on(st);
1463   st->cr();
1464 
1465   ALL_JAVA_THREADS(p) {
1466     ResourceMark rm;
1467     p->print_on(st, print_extended_info);
1468     if (print_stacks) {
1469       if (internal_format) {
1470         p->trace_stack();
1471       } else {
1472         p->print_stack_on(st);
1473       }
1474     }
1475     st->cr();
1476 #if INCLUDE_SERVICES
1477     if (print_concurrent_locks) {
1478       concurrent_locks.print_locks_on(p, st);
1479     }
1480 #endif // INCLUDE_SERVICES
1481   }
1482 
1483   PrintOnClosure cl(st);
1484   cl.do_thread(VMThread::vm_thread());
1485   Universe::heap()->gc_threads_do(&cl);
1486   if (StringDedup::is_enabled()) {
1487     StringDedup::threads_do(&cl);
1488   }
1489   cl.do_thread(WatcherThread::watcher_thread());
1490   cl.do_thread(AsyncLogWriter::instance());
1491 
1492   st->flush();
1493 }
1494 
1495 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
1496                              int buflen, bool* found_current) {
1497   if (this_thread != nullptr) {
1498     bool is_current = (current == this_thread);
1499     *found_current = *found_current || is_current;
1500     st->print("%s", is_current ? "=>" : "  ");
1501 
1502     st->print(PTR_FORMAT, p2i(this_thread));
1503     st->print(" ");
1504     this_thread->print_on_error(st, buf, buflen);
1505     st->cr();
1506   }
1507 }
1508 
1509 class PrintOnErrorClosure : public ThreadClosure {
1510   outputStream* _st;
1511   Thread* _current;
1512   char* _buf;
1513   int _buflen;
1514   bool* _found_current;
1515  public:
1516   PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
1517                       int buflen, bool* found_current) :
1518    _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
1519 
1520   virtual void do_thread(Thread* thread) {
1521     Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
1522   }
1523 };
1524 
1525 // Threads::print_on_error() is called by fatal error handler. It's possible
1526 // that VM is not at safepoint and/or current thread is inside signal handler.
1527 // Don't print stack trace, as the stack may not be walkable. Don't allocate
1528 // memory (even in resource area), it might deadlock the error handler.
1529 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
1530                              int buflen) {
1531   ThreadsSMRSupport::print_info_on(st);
1532   st->cr();
1533 
1534   bool found_current = false;
1535   st->print_cr("Java Threads: ( => current thread )");
1536   ALL_JAVA_THREADS(thread) {
1537     print_on_error(thread, st, current, buf, buflen, &found_current);
1538   }
1539   st->cr();
1540 
1541   st->print_cr("Other Threads:");
1542   print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
1543   print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
1544   print_on_error(AsyncLogWriter::instance(), st, current, buf, buflen, &found_current);
1545 
1546   if (Universe::heap() != nullptr) {
1547     PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
1548     Universe::heap()->gc_threads_do(&print_closure);
1549   }
1550 
1551   if (StringDedup::is_enabled()) {
1552     PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
1553     StringDedup::threads_do(&print_closure);
1554   }
1555 
1556   if (!found_current) {
1557     st->cr();
1558     st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
1559     current->print_on_error(st, buf, buflen);
1560     st->cr();
1561   }
1562   st->cr();
1563 
1564   st->print_cr("Threads with active compile tasks:");
1565   print_threads_compiling(st, buf, buflen);
1566 }
1567 
1568 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen, bool short_form) {
1569   ALL_JAVA_THREADS(thread) {
1570     if (thread->is_Compiler_thread()) {
1571       CompilerThread* ct = (CompilerThread*) thread;
1572 
1573       // Keep task in local variable for null check.
1574       // ct->_task might be set to null by concurring compiler thread
1575       // because it completed the compilation. The task is never freed,
1576       // though, just returned to a free list.
1577       CompileTask* task = ct->task();
1578       if (task != nullptr) {
1579         thread->print_name_on_error(st, buf, buflen);
1580         st->print("  ");
1581         task->print(st, nullptr, short_form, true);
1582       }
1583     }
1584   }
1585 }
1586 
1587 void Threads::verify() {
1588   ALL_JAVA_THREADS(p) {
1589     p->verify();
1590   }
1591   VMThread* thread = VMThread::vm_thread();
1592   if (thread != nullptr) thread->verify();
1593 }