1 /*
   2  * Copyright (c) 1997, 2020, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "jvm.h"
  27 #include "aot/aotLoader.hpp"
  28 #include "classfile/classLoader.hpp"
  29 #include "classfile/javaClasses.hpp"
  30 #include "classfile/moduleEntry.hpp"
  31 #include "classfile/systemDictionary.hpp"
  32 #include "classfile/vmSymbols.hpp"
  33 #include "code/codeCache.hpp"
  34 #include "code/scopeDesc.hpp"
  35 #include "compiler/compileBroker.hpp"
  36 #include "compiler/compileTask.hpp"
  37 #include "gc/shared/barrierSet.hpp"
  38 #include "gc/shared/gcId.hpp"
  39 #include "gc/shared/gcLocker.inline.hpp"
  40 #include "gc/shared/workgroup.hpp"
  41 #include "interpreter/interpreter.hpp"
  42 #include "interpreter/linkResolver.hpp"
  43 #include "interpreter/oopMapCache.hpp"
  44 #include "jfr/jfrEvents.hpp"
  45 #include "jvmtifiles/jvmtiEnv.hpp"
  46 #include "logging/log.hpp"
  47 #include "logging/logConfiguration.hpp"
  48 #include "logging/logStream.hpp"
  49 #include "memory/allocation.inline.hpp"
  50 #include "memory/iterator.hpp"
  51 #include "memory/metaspaceShared.hpp"
  52 #include "memory/oopFactory.hpp"
  53 #include "memory/resourceArea.hpp"
  54 #include "memory/universe.hpp"
  55 #include "oops/access.inline.hpp"
  56 #include "oops/instanceKlass.hpp"
  57 #include "oops/objArrayOop.hpp"
  58 #include "oops/oop.inline.hpp"
  59 #include "oops/symbol.hpp"
  60 #include "oops/typeArrayOop.inline.hpp"
  61 #include "oops/verifyOopClosure.hpp"
  62 #include "prims/jvm_misc.hpp"
  63 #include "prims/jvmtiExport.hpp"
  64 #include "prims/jvmtiThreadState.hpp"
  65 #include "runtime/arguments.hpp"
  66 #include "runtime/atomic.hpp"
  67 #include "runtime/biasedLocking.hpp"
  68 #include "runtime/fieldDescriptor.inline.hpp"
  69 #include "runtime/flags/jvmFlagConstraintList.hpp"
  70 #include "runtime/flags/jvmFlagRangeList.hpp"
  71 #include "runtime/deoptimization.hpp"
  72 #include "runtime/frame.inline.hpp"
  73 #include "runtime/handles.inline.hpp"
  74 #include "runtime/handshake.hpp"
  75 #include "runtime/init.hpp"
  76 #include "runtime/interfaceSupport.inline.hpp"
  77 #include "runtime/java.hpp"
  78 #include "runtime/javaCalls.hpp"
  79 #include "runtime/jniHandles.inline.hpp"
  80 #include "runtime/jniPeriodicChecker.hpp"
  81 #include "runtime/memprofiler.hpp"
  82 #include "runtime/mutexLocker.hpp"
  83 #include "runtime/objectMonitor.hpp"
  84 #include "runtime/orderAccess.hpp"
  85 #include "runtime/osThread.hpp"
  86 #include "runtime/prefetch.inline.hpp"
  87 #include "runtime/safepoint.hpp"
  88 #include "runtime/safepointMechanism.inline.hpp"
  89 #include "runtime/safepointVerifiers.hpp"
  90 #include "runtime/serviceThread.hpp"
  91 #include "runtime/sharedRuntime.hpp"
  92 #include "runtime/statSampler.hpp"
  93 #include "runtime/stubRoutines.hpp"
  94 #include "runtime/sweeper.hpp"
  95 #include "runtime/task.hpp"
  96 #include "runtime/thread.inline.hpp"
  97 #include "runtime/threadCritical.hpp"
  98 #include "runtime/threadSMR.inline.hpp"
  99 #include "runtime/threadStatisticalInfo.hpp"
 100 #include "runtime/timer.hpp"
 101 #include "runtime/timerTrace.hpp"
 102 #include "runtime/vframe.inline.hpp"
 103 #include "runtime/vframeArray.hpp"
 104 #include "runtime/vframe_hp.hpp"
 105 #include "runtime/vmThread.hpp"
 106 #include "runtime/vmOperations.hpp"
 107 #include "runtime/vm_version.hpp"
 108 #include "services/attachListener.hpp"
 109 #include "services/management.hpp"
 110 #include "services/memTracker.hpp"
 111 #include "services/threadService.hpp"
 112 #include "utilities/align.hpp"
 113 #include "utilities/copy.hpp"
 114 #include "utilities/defaultStream.hpp"
 115 #include "utilities/dtrace.hpp"
 116 #include "utilities/events.hpp"
 117 #include "utilities/macros.hpp"
 118 #include "utilities/preserveException.hpp"
 119 #include "utilities/singleWriterSynchronizer.hpp"
 120 #include "utilities/vmError.hpp"
 121 #if INCLUDE_JVMCI
 122 #include "jvmci/jvmci.hpp"
 123 #include "jvmci/jvmciEnv.hpp"
 124 #endif
 125 #ifdef COMPILER1
 126 #include "c1/c1_Compiler.hpp"
 127 #endif
 128 #ifdef COMPILER2
 129 #include "opto/c2compiler.hpp"
 130 #include "opto/idealGraphPrinter.hpp"
 131 #endif
 132 #if INCLUDE_RTM_OPT
 133 #include "runtime/rtmLocking.hpp"
 134 #endif
 135 #if INCLUDE_JFR
 136 #include "jfr/jfr.hpp"
 137 #endif
 138 
 139 // Initialization after module runtime initialization
 140 void universe_post_module_init();  // must happen after call_initPhase2
 141 
 142 #ifdef DTRACE_ENABLED
 143 
 144 // Only bother with this argument setup if dtrace is available
 145 
 146   #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
 147   #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
 148 
 149   #define DTRACE_THREAD_PROBE(probe, javathread)                           \
 150     {                                                                      \
 151       ResourceMark rm(this);                                               \
 152       int len = 0;                                                         \
 153       const char* name = (javathread)->get_thread_name();                  \
 154       len = strlen(name);                                                  \
 155       HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */               \
 156         (char *) name, len,                                                \
 157         java_lang_Thread::thread_id((javathread)->threadObj()),            \
 158         (uintptr_t) (javathread)->osthread()->thread_id(),                 \
 159         java_lang_Thread::is_daemon((javathread)->threadObj()));           \
 160     }
 161 
 162 #else //  ndef DTRACE_ENABLED
 163 
 164   #define DTRACE_THREAD_PROBE(probe, javathread)
 165 
 166 #endif // ndef DTRACE_ENABLED
 167 
 168 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 169 // Current thread is maintained as a thread-local variable
 170 THREAD_LOCAL Thread* Thread::_thr_current = NULL;
 171 #endif
 172 
 173 // ======= Thread ========
 174 // Support for forcing alignment of thread objects for biased locking
 175 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
 176   if (UseBiasedLocking) {
 177     const size_t alignment = markWord::biased_lock_alignment;
 178     size_t aligned_size = size + (alignment - sizeof(intptr_t));
 179     void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
 180                                           : AllocateHeap(aligned_size, flags, CURRENT_PC,
 181                                                          AllocFailStrategy::RETURN_NULL);
 182     void* aligned_addr     = align_up(real_malloc_addr, alignment);
 183     assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
 184            ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
 185            "JavaThread alignment code overflowed allocated storage");
 186     if (aligned_addr != real_malloc_addr) {
 187       log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
 188                               p2i(real_malloc_addr),
 189                               p2i(aligned_addr));
 190     }
 191     ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
 192     return aligned_addr;
 193   } else {
 194     return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
 195                        : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
 196   }
 197 }
 198 
 199 void Thread::operator delete(void* p) {
 200   if (UseBiasedLocking) {
 201     FreeHeap(((Thread*) p)->_real_malloc_address);
 202   } else {
 203     FreeHeap(p);
 204   }
 205 }
 206 
 207 void JavaThread::smr_delete() {
 208   if (_on_thread_list) {
 209     ThreadsSMRSupport::smr_delete(this);
 210   } else {
 211     delete this;
 212   }
 213 }
 214 
 215 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
 216 // JavaThread
 217 
 218 DEBUG_ONLY(Thread* Thread::_starting_thread = NULL;)
 219 
 220 Thread::Thread() {
 221 
 222   DEBUG_ONLY(_run_state = PRE_CALL_RUN;)
 223 
 224   // stack and get_thread
 225   set_stack_base(NULL);
 226   set_stack_size(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   NOT_PRODUCT(_no_safepoint_count = 0;)
 254   NOT_PRODUCT(_skip_gcalot = false;)
 255   _jvmti_env_iteration_count = 0;
 256   set_allocated_bytes(0);
 257   _vm_operation_started_count = 0;
 258   _vm_operation_completed_count = 0;
 259   _current_pending_monitor = NULL;
 260   _current_pending_monitor_is_from_java = true;
 261   _current_waiting_monitor = NULL;
 262   _current_pending_raw_monitor = NULL;
 263   _num_nested_signal = 0;
 264   om_free_list = NULL;
 265   om_free_count = 0;
 266   om_free_provision = 32;
 267   om_in_use_list = NULL;
 268   om_in_use_count = 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   _MuxEvent    = ParkEvent::Allocate(this);
 297 
 298 #ifdef CHECK_UNHANDLED_OOPS
 299   if (CheckUnhandledOops) {
 300     _unhandled_oops = new UnhandledOops(this);
 301   }
 302 #endif // CHECK_UNHANDLED_OOPS
 303 #ifdef ASSERT
 304   if (UseBiasedLocking) {
 305     assert(is_aligned(this, markWord::biased_lock_alignment), "forced alignment of thread object failed");
 306     assert(this == _real_malloc_address ||
 307            this == align_up(_real_malloc_address, markWord::biased_lock_alignment),
 308            "bug in forced alignment of thread objects");
 309   }
 310 #endif // ASSERT
 311 
 312   // Notify the barrier set that a thread is being created. The initial
 313   // thread is created before the barrier set is available.  The call to
 314   // BarrierSet::on_thread_create() for this thread is therefore deferred
 315   // to BarrierSet::set_barrier_set().
 316   BarrierSet* const barrier_set = BarrierSet::barrier_set();
 317   if (barrier_set != NULL) {
 318     barrier_set->on_thread_create(this);
 319   } else {
 320     // Only the main thread should be created before the barrier set
 321     // and that happens just before Thread::current is set. No other thread
 322     // can attach as the VM is not created yet, so they can't execute this code.
 323     // If the main thread creates other threads before the barrier set that is an error.
 324     assert(Thread::current_or_null() == NULL, "creating thread before barrier set");
 325   }
 326 }
 327 
 328 void Thread::initialize_thread_current() {
 329 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 330   assert(_thr_current == NULL, "Thread::current already initialized");
 331   _thr_current = this;
 332 #endif
 333   assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
 334   ThreadLocalStorage::set_thread(this);
 335   assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
 336 }
 337 
 338 void Thread::clear_thread_current() {
 339   assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
 340 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 341   _thr_current = NULL;
 342 #endif
 343   ThreadLocalStorage::set_thread(NULL);
 344 }
 345 
 346 void Thread::record_stack_base_and_size() {
 347   // Note: at this point, Thread object is not yet initialized. Do not rely on
 348   // any members being initialized. Do not rely on Thread::current() being set.
 349   // If possible, refrain from doing anything which may crash or assert since
 350   // quite probably those crash dumps will be useless.
 351   set_stack_base(os::current_stack_base());
 352   set_stack_size(os::current_stack_size());
 353 
 354 #ifdef SOLARIS
 355   if (os::is_primordial_thread()) {
 356     os::Solaris::correct_stack_boundaries_for_primordial_thread(this);
 357   }
 358 #endif
 359 
 360   // Set stack limits after thread is initialized.
 361   if (is_Java_thread()) {
 362     ((JavaThread*) this)->set_stack_overflow_limit();
 363     ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
 364   }
 365 }
 366 
 367 #if INCLUDE_NMT
 368 void Thread::register_thread_stack_with_NMT() {
 369   MemTracker::record_thread_stack(stack_end(), stack_size());
 370 }
 371 #endif // INCLUDE_NMT
 372 
 373 void Thread::call_run() {
 374   DEBUG_ONLY(_run_state = CALL_RUN;)
 375 
 376   // At this point, Thread object should be fully initialized and
 377   // Thread::current() should be set.
 378 
 379   assert(Thread::current_or_null() != NULL, "current thread is unset");
 380   assert(Thread::current_or_null() == this, "current thread is wrong");
 381 
 382   // Perform common initialization actions
 383 
 384   register_thread_stack_with_NMT();
 385 
 386   JFR_ONLY(Jfr::on_thread_start(this);)
 387 
 388   log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
 389     PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
 390     os::current_thread_id(), p2i(stack_end()),
 391     p2i(stack_base()), stack_size()/1024);
 392 
 393   // Perform <ChildClass> initialization actions
 394   DEBUG_ONLY(_run_state = PRE_RUN;)
 395   this->pre_run();
 396 
 397   // Invoke <ChildClass>::run()
 398   DEBUG_ONLY(_run_state = RUN;)
 399   this->run();
 400   // Returned from <ChildClass>::run(). Thread finished.
 401 
 402   // Perform common tear-down actions
 403 
 404   assert(Thread::current_or_null() != NULL, "current thread is unset");
 405   assert(Thread::current_or_null() == this, "current thread is wrong");
 406 
 407   // Perform <ChildClass> tear-down actions
 408   DEBUG_ONLY(_run_state = POST_RUN;)
 409   this->post_run();
 410 
 411   // Note: at this point the thread object may already have deleted itself,
 412   // so from here on do not dereference *this*. Not all thread types currently
 413   // delete themselves when they terminate. But no thread should ever be deleted
 414   // asynchronously with respect to its termination - that is what _run_state can
 415   // be used to check.
 416 
 417   assert(Thread::current_or_null() == NULL, "current thread still present");
 418 }
 419 
 420 Thread::~Thread() {
 421 
 422   // Attached threads will remain in PRE_CALL_RUN, as will threads that don't actually
 423   // get started due to errors etc. Any active thread should at least reach post_run
 424   // before it is deleted (usually in post_run()).
 425   assert(_run_state == PRE_CALL_RUN ||
 426          _run_state == POST_RUN, "Active Thread deleted before post_run(): "
 427          "_run_state=%d", (int)_run_state);
 428 
 429   // Notify the barrier set that a thread is being destroyed. Note that a barrier
 430   // set might not be available if we encountered errors during bootstrapping.
 431   BarrierSet* const barrier_set = BarrierSet::barrier_set();
 432   if (barrier_set != NULL) {
 433     barrier_set->on_thread_destroy(this);
 434   }
 435 
 436   // stack_base can be NULL if the thread is never started or exited before
 437   // record_stack_base_and_size called. Although, we would like to ensure
 438   // that all started threads do call record_stack_base_and_size(), there is
 439   // not proper way to enforce that.
 440 #if INCLUDE_NMT
 441   if (_stack_base != NULL) {
 442     MemTracker::release_thread_stack(stack_end(), stack_size());
 443 #ifdef ASSERT
 444     set_stack_base(NULL);
 445 #endif
 446   }
 447 #endif // INCLUDE_NMT
 448 
 449   // deallocate data structures
 450   delete resource_area();
 451   // since the handle marks are using the handle area, we have to deallocated the root
 452   // handle mark before deallocating the thread's handle area,
 453   assert(last_handle_mark() != NULL, "check we have an element");
 454   delete last_handle_mark();
 455   assert(last_handle_mark() == NULL, "check we have reached the end");
 456 
 457   // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
 458   // We NULL out the fields for good hygiene.
 459   ParkEvent::Release(_ParkEvent); _ParkEvent   = NULL;
 460   ParkEvent::Release(_MuxEvent); _MuxEvent    = NULL;
 461 
 462   delete handle_area();
 463   delete metadata_handles();
 464 
 465   // SR_handler uses this as a termination indicator -
 466   // needs to happen before os::free_thread()
 467   delete _SR_lock;
 468   _SR_lock = NULL;
 469 
 470   // osthread() can be NULL, if creation of thread failed.
 471   if (osthread() != NULL) os::free_thread(osthread());
 472 
 473   // Clear Thread::current if thread is deleting itself and it has not
 474   // already been done. This must be done before the memory is deallocated.
 475   // Needed to ensure JNI correctly detects non-attached threads.
 476   if (this == Thread::current_or_null()) {
 477     Thread::clear_thread_current();
 478   }
 479 
 480   CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
 481 }
 482 
 483 #ifdef ASSERT
 484 // A JavaThread is considered "dangling" if it is not the current
 485 // thread, has been added the Threads list, the system is not at a
 486 // safepoint and the Thread is not "protected".
 487 //
 488 void Thread::check_for_dangling_thread_pointer(Thread *thread) {
 489   assert(!thread->is_Java_thread() || Thread::current() == thread ||
 490          !((JavaThread *) thread)->on_thread_list() ||
 491          SafepointSynchronize::is_at_safepoint() ||
 492          ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread),
 493          "possibility of dangling Thread pointer");
 494 }
 495 #endif
 496 
 497 ThreadPriority Thread::get_priority(const Thread* const thread) {
 498   ThreadPriority priority;
 499   // Can return an error!
 500   (void)os::get_priority(thread, priority);
 501   assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
 502   return priority;
 503 }
 504 
 505 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
 506   debug_only(check_for_dangling_thread_pointer(thread);)
 507   // Can return an error!
 508   (void)os::set_priority(thread, priority);
 509 }
 510 
 511 
 512 void Thread::start(Thread* thread) {
 513   // Start is different from resume in that its safety is guaranteed by context or
 514   // being called from a Java method synchronized on the Thread object.
 515   if (!DisableStartThread) {
 516     if (thread->is_Java_thread()) {
 517       // Initialize the thread state to RUNNABLE before starting this thread.
 518       // Can not set it after the thread started because we do not know the
 519       // exact thread state at that time. It could be in MONITOR_WAIT or
 520       // in SLEEPING or some other state.
 521       java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
 522                                           java_lang_Thread::RUNNABLE);
 523     }
 524     os::start_thread(thread);
 525   }
 526 }
 527 
 528 class InstallAsyncExceptionClosure : public HandshakeClosure {
 529   Handle _throwable; // The Throwable thrown at the target Thread
 530 public:
 531   InstallAsyncExceptionClosure(Handle throwable) : HandshakeClosure("InstallAsyncException"), _throwable(throwable) {}
 532 
 533   void do_thread(Thread* thr) {
 534     JavaThread* target = (JavaThread*)thr;
 535     // Note that this now allows multiple ThreadDeath exceptions to be
 536     // thrown at a thread.
 537     // The target thread has run and has not exited yet.
 538     target->send_thread_stop(_throwable());
 539   }
 540 };
 541 
 542 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
 543   Handle throwable(Thread::current(), java_throwable);
 544   JavaThread* target = java_lang_Thread::thread(java_thread);
 545   InstallAsyncExceptionClosure vm_stop(throwable);
 546   Handshake::execute(&vm_stop, target);
 547 }
 548 
 549 
 550 // Check if an external suspend request has completed (or has been
 551 // cancelled). Returns true if the thread is externally suspended and
 552 // false otherwise.
 553 //
 554 // The bits parameter returns information about the code path through
 555 // the routine. Useful for debugging:
 556 //
 557 // set in is_ext_suspend_completed():
 558 // 0x00000001 - routine was entered
 559 // 0x00000010 - routine return false at end
 560 // 0x00000100 - thread exited (return false)
 561 // 0x00000200 - suspend request cancelled (return false)
 562 // 0x00000400 - thread suspended (return true)
 563 // 0x00001000 - thread is in a suspend equivalent state (return true)
 564 // 0x00002000 - thread is native and walkable (return true)
 565 // 0x00004000 - thread is native_trans and walkable (needed retry)
 566 //
 567 // set in wait_for_ext_suspend_completion():
 568 // 0x00010000 - routine was entered
 569 // 0x00020000 - suspend request cancelled before loop (return false)
 570 // 0x00040000 - thread suspended before loop (return true)
 571 // 0x00080000 - suspend request cancelled in loop (return false)
 572 // 0x00100000 - thread suspended in loop (return true)
 573 // 0x00200000 - suspend not completed during retry loop (return false)
 574 
 575 // Helper class for tracing suspend wait debug bits.
 576 //
 577 // 0x00000100 indicates that the target thread exited before it could
 578 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
 579 // 0x00080000 each indicate a cancelled suspend request so they don't
 580 // count as wait failures either.
 581 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
 582 
 583 class TraceSuspendDebugBits : public StackObj {
 584  private:
 585   JavaThread * jt;
 586   bool         is_wait;
 587   bool         called_by_wait;  // meaningful when !is_wait
 588   uint32_t *   bits;
 589 
 590  public:
 591   TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
 592                         uint32_t *_bits) {
 593     jt             = _jt;
 594     is_wait        = _is_wait;
 595     called_by_wait = _called_by_wait;
 596     bits           = _bits;
 597   }
 598 
 599   ~TraceSuspendDebugBits() {
 600     if (!is_wait) {
 601 #if 1
 602       // By default, don't trace bits for is_ext_suspend_completed() calls.
 603       // That trace is very chatty.
 604       return;
 605 #else
 606       if (!called_by_wait) {
 607         // If tracing for is_ext_suspend_completed() is enabled, then only
 608         // trace calls to it from wait_for_ext_suspend_completion()
 609         return;
 610       }
 611 #endif
 612     }
 613 
 614     if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
 615       if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
 616         MutexLocker ml(Threads_lock);  // needed for get_thread_name()
 617         ResourceMark rm;
 618 
 619         tty->print_cr(
 620                       "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
 621                       jt->get_thread_name(), *bits);
 622 
 623         guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
 624       }
 625     }
 626   }
 627 };
 628 #undef DEBUG_FALSE_BITS
 629 
 630 
 631 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
 632                                           uint32_t *bits) {
 633   TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
 634 
 635   bool did_trans_retry = false;  // only do thread_in_native_trans retry once
 636   bool do_trans_retry;           // flag to force the retry
 637 
 638   *bits |= 0x00000001;
 639 
 640   do {
 641     do_trans_retry = false;
 642 
 643     if (is_exiting()) {
 644       // Thread is in the process of exiting. This is always checked
 645       // first to reduce the risk of dereferencing a freed JavaThread.
 646       *bits |= 0x00000100;
 647       return false;
 648     }
 649 
 650     if (!is_external_suspend()) {
 651       // Suspend request is cancelled. This is always checked before
 652       // is_ext_suspended() to reduce the risk of a rogue resume
 653       // confusing the thread that made the suspend request.
 654       *bits |= 0x00000200;
 655       return false;
 656     }
 657 
 658     if (is_ext_suspended()) {
 659       // thread is suspended
 660       *bits |= 0x00000400;
 661       return true;
 662     }
 663 
 664     // Now that we no longer do hard suspends of threads running
 665     // native code, the target thread can be changing thread state
 666     // while we are in this routine:
 667     //
 668     //   _thread_in_native -> _thread_in_native_trans -> _thread_blocked
 669     //
 670     // We save a copy of the thread state as observed at this moment
 671     // and make our decision about suspend completeness based on the
 672     // copy. This closes the race where the thread state is seen as
 673     // _thread_in_native_trans in the if-thread_blocked check, but is
 674     // seen as _thread_blocked in if-thread_in_native_trans check.
 675     JavaThreadState save_state = thread_state();
 676 
 677     if (save_state == _thread_blocked && is_suspend_equivalent()) {
 678       // If the thread's state is _thread_blocked and this blocking
 679       // condition is known to be equivalent to a suspend, then we can
 680       // consider the thread to be externally suspended. This means that
 681       // the code that sets _thread_blocked has been modified to do
 682       // self-suspension if the blocking condition releases. We also
 683       // used to check for CONDVAR_WAIT here, but that is now covered by
 684       // the _thread_blocked with self-suspension check.
 685       //
 686       // Return true since we wouldn't be here unless there was still an
 687       // external suspend request.
 688       *bits |= 0x00001000;
 689       return true;
 690     } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
 691       // Threads running native code will self-suspend on native==>VM/Java
 692       // transitions. If its stack is walkable (should always be the case
 693       // unless this function is called before the actual java_suspend()
 694       // call), then the wait is done.
 695       *bits |= 0x00002000;
 696       return true;
 697     } else if (!called_by_wait && !did_trans_retry &&
 698                save_state == _thread_in_native_trans &&
 699                frame_anchor()->walkable()) {
 700       // The thread is transitioning from thread_in_native to another
 701       // thread state. check_safepoint_and_suspend_for_native_trans()
 702       // will force the thread to self-suspend. If it hasn't gotten
 703       // there yet we may have caught the thread in-between the native
 704       // code check above and the self-suspend. Lucky us. If we were
 705       // called by wait_for_ext_suspend_completion(), then it
 706       // will be doing the retries so we don't have to.
 707       //
 708       // Since we use the saved thread state in the if-statement above,
 709       // there is a chance that the thread has already transitioned to
 710       // _thread_blocked by the time we get here. In that case, we will
 711       // make a single unnecessary pass through the logic below. This
 712       // doesn't hurt anything since we still do the trans retry.
 713 
 714       *bits |= 0x00004000;
 715 
 716       // Once the thread leaves thread_in_native_trans for another
 717       // thread state, we break out of this retry loop. We shouldn't
 718       // need this flag to prevent us from getting back here, but
 719       // sometimes paranoia is good.
 720       did_trans_retry = true;
 721 
 722       // We wait for the thread to transition to a more usable state.
 723       for (int i = 1; i <= SuspendRetryCount; i++) {
 724         // We used to do an "os::yield_all(i)" call here with the intention
 725         // that yielding would increase on each retry. However, the parameter
 726         // is ignored on Linux which means the yield didn't scale up. Waiting
 727         // on the SR_lock below provides a much more predictable scale up for
 728         // the delay. It also provides a simple/direct point to check for any
 729         // safepoint requests from the VMThread
 730 
 731         // temporarily drops SR_lock while doing wait with safepoint check
 732         // (if we're a JavaThread - the WatcherThread can also call this)
 733         // and increase delay with each retry
 734         if (Thread::current()->is_Java_thread()) {
 735           SR_lock()->wait(i * delay);
 736         } else {
 737           SR_lock()->wait_without_safepoint_check(i * delay);
 738         }
 739 
 740         // check the actual thread state instead of what we saved above
 741         if (thread_state() != _thread_in_native_trans) {
 742           // the thread has transitioned to another thread state so
 743           // try all the checks (except this one) one more time.
 744           do_trans_retry = true;
 745           break;
 746         }
 747       } // end retry loop
 748 
 749 
 750     }
 751   } while (do_trans_retry);
 752 
 753   *bits |= 0x00000010;
 754   return false;
 755 }
 756 
 757 // Wait for an external suspend request to complete (or be cancelled).
 758 // Returns true if the thread is externally suspended and false otherwise.
 759 //
 760 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
 761                                                  uint32_t *bits) {
 762   TraceSuspendDebugBits tsdb(this, true /* is_wait */,
 763                              false /* !called_by_wait */, bits);
 764 
 765   // local flag copies to minimize SR_lock hold time
 766   bool is_suspended;
 767   bool pending;
 768   uint32_t reset_bits;
 769 
 770   // set a marker so is_ext_suspend_completed() knows we are the caller
 771   *bits |= 0x00010000;
 772 
 773   // We use reset_bits to reinitialize the bits value at the top of
 774   // each retry loop. This allows the caller to make use of any
 775   // unused bits for their own marking purposes.
 776   reset_bits = *bits;
 777 
 778   {
 779     MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
 780     is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 781                                             delay, bits);
 782     pending = is_external_suspend();
 783   }
 784   // must release SR_lock to allow suspension to complete
 785 
 786   if (!pending) {
 787     // A cancelled suspend request is the only false return from
 788     // is_ext_suspend_completed() that keeps us from entering the
 789     // retry loop.
 790     *bits |= 0x00020000;
 791     return false;
 792   }
 793 
 794   if (is_suspended) {
 795     *bits |= 0x00040000;
 796     return true;
 797   }
 798 
 799   for (int i = 1; i <= retries; i++) {
 800     *bits = reset_bits;  // reinit to only track last retry
 801 
 802     // We used to do an "os::yield_all(i)" call here with the intention
 803     // that yielding would increase on each retry. However, the parameter
 804     // is ignored on Linux which means the yield didn't scale up. Waiting
 805     // on the SR_lock below provides a much more predictable scale up for
 806     // the delay. It also provides a simple/direct point to check for any
 807     // safepoint requests from the VMThread
 808 
 809     {
 810       Thread* t = Thread::current();
 811       MonitorLocker ml(SR_lock(),
 812                        t->is_Java_thread() ? Mutex::_safepoint_check_flag : Mutex::_no_safepoint_check_flag);
 813       // wait with safepoint check (if we're a JavaThread - the WatcherThread
 814       // can also call this)  and increase delay with each retry
 815       ml.wait(i * delay);
 816 
 817       is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 818                                               delay, bits);
 819 
 820       // It is possible for the external suspend request to be cancelled
 821       // (by a resume) before the actual suspend operation is completed.
 822       // Refresh our local copy to see if we still need to wait.
 823       pending = is_external_suspend();
 824     }
 825 
 826     if (!pending) {
 827       // A cancelled suspend request is the only false return from
 828       // is_ext_suspend_completed() that keeps us from staying in the
 829       // retry loop.
 830       *bits |= 0x00080000;
 831       return false;
 832     }
 833 
 834     if (is_suspended) {
 835       *bits |= 0x00100000;
 836       return true;
 837     }
 838   } // end retry loop
 839 
 840   // thread did not suspend after all our retries
 841   *bits |= 0x00200000;
 842   return false;
 843 }
 844 
 845 // Called from API entry points which perform stack walking. If the
 846 // associated JavaThread is the current thread, then wait_for_suspend
 847 // is not used. Otherwise, it determines if we should wait for the
 848 // "other" thread to complete external suspension. (NOTE: in future
 849 // releases the suspension mechanism should be reimplemented so this
 850 // is not necessary.)
 851 //
 852 bool
 853 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) {
 854   if (this != JavaThread::current()) {
 855     // "other" threads require special handling.
 856     if (wait_for_suspend) {
 857       // We are allowed to wait for the external suspend to complete
 858       // so give the other thread a chance to get suspended.
 859       if (!wait_for_ext_suspend_completion(SuspendRetryCount,
 860                                            SuspendRetryDelay, bits)) {
 861         // Didn't make it so let the caller know.
 862         return false;
 863       }
 864     }
 865     // We aren't allowed to wait for the external suspend to complete
 866     // so if the other thread isn't externally suspended we need to
 867     // let the caller know.
 868     else if (!is_ext_suspend_completed_with_lock(bits)) {
 869       return false;
 870     }
 871   }
 872 
 873   return true;
 874 }
 875 
 876 // GC Support
 877 bool Thread::claim_par_threads_do(uintx claim_token) {
 878   uintx token = _threads_do_token;
 879   if (token != claim_token) {
 880     uintx res = Atomic::cmpxchg(&_threads_do_token, token, claim_token);
 881     if (res == token) {
 882       return true;
 883     }
 884     guarantee(res == claim_token, "invariant");
 885   }
 886   return false;
 887 }
 888 
 889 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
 890   if (active_handles() != NULL) {
 891     active_handles()->oops_do(f);
 892   }
 893   // Do oop for ThreadShadow
 894   f->do_oop((oop*)&_pending_exception);
 895   handle_area()->oops_do(f);
 896 
 897   // We scan thread local monitor lists here, and the remaining global
 898   // monitors in ObjectSynchronizer::oops_do().
 899   ObjectSynchronizer::thread_local_used_oops_do(this, f);
 900 }
 901 
 902 void Thread::metadata_handles_do(void f(Metadata*)) {
 903   // Only walk the Handles in Thread.
 904   if (metadata_handles() != NULL) {
 905     for (int i = 0; i< metadata_handles()->length(); i++) {
 906       f(metadata_handles()->at(i));
 907     }
 908   }
 909 }
 910 
 911 void Thread::print_on(outputStream* st, bool print_extended_info) const {
 912   // get_priority assumes osthread initialized
 913   if (osthread() != NULL) {
 914     int os_prio;
 915     if (os::get_native_priority(this, &os_prio) == OS_OK) {
 916       st->print("os_prio=%d ", os_prio);
 917     }
 918 
 919     st->print("cpu=%.2fms ",
 920               os::thread_cpu_time(const_cast<Thread*>(this), true) / 1000000.0
 921               );
 922     st->print("elapsed=%.2fs ",
 923               _statistical_info.getElapsedTime() / 1000.0
 924               );
 925     if (is_Java_thread() && (PrintExtendedThreadInfo || print_extended_info)) {
 926       size_t allocated_bytes = (size_t) const_cast<Thread*>(this)->cooked_allocated_bytes();
 927       st->print("allocated=" SIZE_FORMAT "%s ",
 928                 byte_size_in_proper_unit(allocated_bytes),
 929                 proper_unit_for_byte_size(allocated_bytes)
 930                 );
 931       st->print("defined_classes=" INT64_FORMAT " ", _statistical_info.getDefineClassCount());
 932     }
 933 
 934     st->print("tid=" INTPTR_FORMAT " ", p2i(this));
 935     osthread()->print_on(st);
 936   }
 937   ThreadsSMRSupport::print_info_on(this, st);
 938   st->print(" ");
 939   debug_only(if (WizardMode) print_owned_locks_on(st);)
 940 }
 941 
 942 void Thread::print() const { print_on(tty); }
 943 
 944 // Thread::print_on_error() is called by fatal error handler. Don't use
 945 // any lock or allocate memory.
 946 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
 947   assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
 948 
 949   if (is_VM_thread())                 { st->print("VMThread"); }
 950   else if (is_GC_task_thread())       { st->print("GCTaskThread"); }
 951   else if (is_Watcher_thread())       { st->print("WatcherThread"); }
 952   else if (is_ConcurrentGC_thread())  { st->print("ConcurrentGCThread"); }
 953   else                                { st->print("Thread"); }
 954 
 955   if (is_Named_thread()) {
 956     st->print(" \"%s\"", name());
 957   }
 958 
 959   st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
 960             p2i(stack_end()), p2i(stack_base()));
 961 
 962   if (osthread()) {
 963     st->print(" [id=%d]", osthread()->thread_id());
 964   }
 965 
 966   ThreadsSMRSupport::print_info_on(this, st);
 967 }
 968 
 969 void Thread::print_value_on(outputStream* st) const {
 970   if (is_Named_thread()) {
 971     st->print(" \"%s\" ", name());
 972   }
 973   st->print(INTPTR_FORMAT, p2i(this));   // print address
 974 }
 975 
 976 #ifdef ASSERT
 977 void Thread::print_owned_locks_on(outputStream* st) const {
 978   Mutex* cur = _owned_locks;
 979   if (cur == NULL) {
 980     st->print(" (no locks) ");
 981   } else {
 982     st->print_cr(" Locks owned:");
 983     while (cur) {
 984       cur->print_on(st);
 985       cur = cur->next();
 986     }
 987   }
 988 }
 989 
 990 // Checks safepoint allowed and clears unhandled oops at potential safepoints.
 991 void Thread::check_possible_safepoint() {
 992   if (!is_Java_thread()) return;
 993 
 994   if (_no_safepoint_count > 0) {
 995     print_owned_locks();
 996     fatal("Possible safepoint reached by thread that does not allow it");
 997   }
 998 #ifdef CHECK_UNHANDLED_OOPS
 999   // Clear unhandled oops in JavaThreads so we get a crash right away.
1000   clear_unhandled_oops();
1001 #endif // CHECK_UNHANDLED_OOPS
1002 }
1003 
1004 void Thread::check_for_valid_safepoint_state() {
1005   if (!is_Java_thread()) return;
1006 
1007   // Check NoSafepointVerifier, which is implied by locks taken that can be
1008   // shared with the VM thread.  This makes sure that no locks with allow_vm_block
1009   // are held.
1010   check_possible_safepoint();
1011 
1012   if (((JavaThread*)this)->thread_state() != _thread_in_vm) {
1013     fatal("LEAF method calling lock?");
1014   }
1015 
1016   if (GCALotAtAllSafepoints) {
1017     // We could enter a safepoint here and thus have a gc
1018     InterfaceSupport::check_gc_alot();
1019   }
1020 }
1021 #endif // ASSERT
1022 
1023 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
1024 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
1025 // used for compilation in the future. If that change is made, the need for these methods
1026 // should be revisited, and they should be removed if possible.
1027 
1028 bool Thread::is_lock_owned(address adr) const {
1029   return is_in_full_stack(adr);
1030 }
1031 
1032 bool Thread::set_as_starting_thread() {
1033   assert(_starting_thread == NULL, "already initialized: "
1034          "_starting_thread=" INTPTR_FORMAT, p2i(_starting_thread));
1035   // NOTE: this must be called inside the main thread.
1036   DEBUG_ONLY(_starting_thread = this;)
1037   return os::create_main_thread((JavaThread*)this);
1038 }
1039 
1040 static void initialize_class(Symbol* class_name, TRAPS) {
1041   Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
1042   InstanceKlass::cast(klass)->initialize(CHECK);
1043 }
1044 
1045 
1046 // Creates the initial ThreadGroup
1047 static Handle create_initial_thread_group(TRAPS) {
1048   Handle system_instance = JavaCalls::construct_new_instance(
1049                             SystemDictionary::ThreadGroup_klass(),
1050                             vmSymbols::void_method_signature(),
1051                             CHECK_NH);
1052   Universe::set_system_thread_group(system_instance());
1053 
1054   Handle string = java_lang_String::create_from_str("main", CHECK_NH);
1055   Handle main_instance = JavaCalls::construct_new_instance(
1056                             SystemDictionary::ThreadGroup_klass(),
1057                             vmSymbols::threadgroup_string_void_signature(),
1058                             system_instance,
1059                             string,
1060                             CHECK_NH);
1061   return main_instance;
1062 }
1063 
1064 // Creates the initial Thread
1065 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
1066                                  TRAPS) {
1067   InstanceKlass* ik = SystemDictionary::Thread_klass();
1068   assert(ik->is_initialized(), "must be");
1069   instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
1070 
1071   // Cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1072   // constructor calls Thread.current(), which must be set here for the
1073   // initial thread.
1074   java_lang_Thread::set_thread(thread_oop(), thread);
1075   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1076   thread->set_threadObj(thread_oop());
1077 
1078   Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1079 
1080   JavaValue result(T_VOID);
1081   JavaCalls::call_special(&result, thread_oop,
1082                           ik,
1083                           vmSymbols::object_initializer_name(),
1084                           vmSymbols::threadgroup_string_void_signature(),
1085                           thread_group,
1086                           string,
1087                           CHECK_NULL);
1088   return thread_oop();
1089 }
1090 
1091 char java_runtime_name[128] = "";
1092 char java_runtime_version[128] = "";
1093 char java_runtime_vendor_version[128] = "";
1094 char java_runtime_vendor_vm_bug_url[128] = "";
1095 
1096 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1097 static const char* get_java_runtime_name(TRAPS) {
1098   Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1099                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1100   fieldDescriptor fd;
1101   bool found = k != NULL &&
1102                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1103                                                         vmSymbols::string_signature(), &fd);
1104   if (found) {
1105     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1106     if (name_oop == NULL) {
1107       return NULL;
1108     }
1109     const char* name = java_lang_String::as_utf8_string(name_oop,
1110                                                         java_runtime_name,
1111                                                         sizeof(java_runtime_name));
1112     return name;
1113   } else {
1114     return NULL;
1115   }
1116 }
1117 
1118 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1119 static const char* get_java_runtime_version(TRAPS) {
1120   Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1121                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1122   fieldDescriptor fd;
1123   bool found = k != NULL &&
1124                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1125                                                         vmSymbols::string_signature(), &fd);
1126   if (found) {
1127     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1128     if (name_oop == NULL) {
1129       return NULL;
1130     }
1131     const char* name = java_lang_String::as_utf8_string(name_oop,
1132                                                         java_runtime_version,
1133                                                         sizeof(java_runtime_version));
1134     return name;
1135   } else {
1136     return NULL;
1137   }
1138 }
1139 
1140 // extract the JRE vendor version from java.lang.VersionProps.VENDOR_VERSION
1141 static const char* get_java_runtime_vendor_version(TRAPS) {
1142   Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1143                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1144   fieldDescriptor fd;
1145   bool found = k != NULL &&
1146                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_vendor_version_name(),
1147                                                         vmSymbols::string_signature(), &fd);
1148   if (found) {
1149     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1150     if (name_oop == NULL) {
1151       return NULL;
1152     }
1153     const char* name = java_lang_String::as_utf8_string(name_oop,
1154                                                         java_runtime_vendor_version,
1155                                                         sizeof(java_runtime_vendor_version));
1156     return name;
1157   } else {
1158     return NULL;
1159   }
1160 }
1161 
1162 // extract the JRE vendor VM bug URL from java.lang.VersionProps.VENDOR_URL_VM_BUG
1163 static const char* get_java_runtime_vendor_vm_bug_url(TRAPS) {
1164   Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1165                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1166   fieldDescriptor fd;
1167   bool found = k != NULL &&
1168                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_vendor_vm_bug_url_name(),
1169                                                         vmSymbols::string_signature(), &fd);
1170   if (found) {
1171     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1172     if (name_oop == NULL) {
1173       return NULL;
1174     }
1175     const char* name = java_lang_String::as_utf8_string(name_oop,
1176                                                         java_runtime_vendor_vm_bug_url,
1177                                                         sizeof(java_runtime_vendor_vm_bug_url));
1178     return name;
1179   } else {
1180     return NULL;
1181   }
1182 }
1183 
1184 // General purpose hook into Java code, run once when the VM is initialized.
1185 // The Java library method itself may be changed independently from the VM.
1186 static void call_postVMInitHook(TRAPS) {
1187   Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1188   if (klass != NULL) {
1189     JavaValue result(T_VOID);
1190     JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1191                            vmSymbols::void_method_signature(),
1192                            CHECK);
1193   }
1194 }
1195 
1196 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1197                                     bool daemon, TRAPS) {
1198   assert(thread_group.not_null(), "thread group should be specified");
1199   assert(threadObj() == NULL, "should only create Java thread object once");
1200 
1201   InstanceKlass* ik = SystemDictionary::Thread_klass();
1202   assert(ik->is_initialized(), "must be");
1203   instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1204 
1205   // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon.
1206   // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1207   // constructor calls Thread.current(), which must be set here.
1208   java_lang_Thread::set_thread(thread_oop(), this);
1209   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1210   set_threadObj(thread_oop());
1211 
1212   JavaValue result(T_VOID);
1213   if (thread_name != NULL) {
1214     Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1215     // Thread gets assigned specified name and null target
1216     JavaCalls::call_special(&result,
1217                             thread_oop,
1218                             ik,
1219                             vmSymbols::object_initializer_name(),
1220                             vmSymbols::threadgroup_string_void_signature(),
1221                             thread_group,
1222                             name,
1223                             THREAD);
1224   } else {
1225     // Thread gets assigned name "Thread-nnn" and null target
1226     // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1227     JavaCalls::call_special(&result,
1228                             thread_oop,
1229                             ik,
1230                             vmSymbols::object_initializer_name(),
1231                             vmSymbols::threadgroup_runnable_void_signature(),
1232                             thread_group,
1233                             Handle(),
1234                             THREAD);
1235   }
1236 
1237 
1238   if (daemon) {
1239     java_lang_Thread::set_daemon(thread_oop());
1240   }
1241 
1242   if (HAS_PENDING_EXCEPTION) {
1243     return;
1244   }
1245 
1246   Klass* group = SystemDictionary::ThreadGroup_klass();
1247   Handle threadObj(THREAD, this->threadObj());
1248 
1249   JavaCalls::call_special(&result,
1250                           thread_group,
1251                           group,
1252                           vmSymbols::add_method_name(),
1253                           vmSymbols::thread_void_signature(),
1254                           threadObj,          // Arg 1
1255                           THREAD);
1256 }
1257 
1258 // List of all NonJavaThreads and safe iteration over that list.
1259 
1260 class NonJavaThread::List {
1261 public:
1262   NonJavaThread* volatile _head;
1263   SingleWriterSynchronizer _protect;
1264 
1265   List() : _head(NULL), _protect() {}
1266 };
1267 
1268 NonJavaThread::List NonJavaThread::_the_list;
1269 
1270 NonJavaThread::Iterator::Iterator() :
1271   _protect_enter(_the_list._protect.enter()),
1272   _current(Atomic::load_acquire(&_the_list._head))
1273 {}
1274 
1275 NonJavaThread::Iterator::~Iterator() {
1276   _the_list._protect.exit(_protect_enter);
1277 }
1278 
1279 void NonJavaThread::Iterator::step() {
1280   assert(!end(), "precondition");
1281   _current = Atomic::load_acquire(&_current->_next);
1282 }
1283 
1284 NonJavaThread::NonJavaThread() : Thread(), _next(NULL) {
1285   assert(BarrierSet::barrier_set() != NULL, "NonJavaThread created too soon!");
1286 }
1287 
1288 NonJavaThread::~NonJavaThread() { }
1289 
1290 void NonJavaThread::add_to_the_list() {
1291   MutexLocker ml(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1292   // Initialize BarrierSet-related data before adding to list.
1293   BarrierSet::barrier_set()->on_thread_attach(this);
1294   Atomic::release_store(&_next, _the_list._head);
1295   Atomic::release_store(&_the_list._head, this);
1296 }
1297 
1298 void NonJavaThread::remove_from_the_list() {
1299   {
1300     MutexLocker ml(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1301     // Cleanup BarrierSet-related data before removing from list.
1302     BarrierSet::barrier_set()->on_thread_detach(this);
1303     NonJavaThread* volatile* p = &_the_list._head;
1304     for (NonJavaThread* t = *p; t != NULL; p = &t->_next, t = *p) {
1305       if (t == this) {
1306         *p = _next;
1307         break;
1308       }
1309     }
1310   }
1311   // Wait for any in-progress iterators.  Concurrent synchronize is not
1312   // allowed, so do it while holding a dedicated lock.  Outside and distinct
1313   // from NJTList_lock in case an iteration attempts to lock it.
1314   MutexLocker ml(NonJavaThreadsListSync_lock, Mutex::_no_safepoint_check_flag);
1315   _the_list._protect.synchronize();
1316   _next = NULL;                 // Safe to drop the link now.
1317 }
1318 
1319 void NonJavaThread::pre_run() {
1320   add_to_the_list();
1321 
1322   // This is slightly odd in that NamedThread is a subclass, but
1323   // in fact name() is defined in Thread
1324   assert(this->name() != NULL, "thread name was not set before it was started");
1325   this->set_native_thread_name(this->name());
1326 }
1327 
1328 void NonJavaThread::post_run() {
1329   JFR_ONLY(Jfr::on_thread_exit(this);)
1330   remove_from_the_list();
1331   // Ensure thread-local-storage is cleared before termination.
1332   Thread::clear_thread_current();
1333 }
1334 
1335 // NamedThread --  non-JavaThread subclasses with multiple
1336 // uniquely named instances should derive from this.
1337 NamedThread::NamedThread() :
1338   NonJavaThread(),
1339   _name(NULL),
1340   _processed_thread(NULL),
1341   _gc_id(GCId::undefined())
1342 {}
1343 
1344 NamedThread::~NamedThread() {
1345   FREE_C_HEAP_ARRAY(char, _name);
1346 }
1347 
1348 void NamedThread::set_name(const char* format, ...) {
1349   guarantee(_name == NULL, "Only get to set name once.");
1350   _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1351   va_list ap;
1352   va_start(ap, format);
1353   jio_vsnprintf(_name, max_name_len, format, ap);
1354   va_end(ap);
1355 }
1356 
1357 void NamedThread::print_on(outputStream* st) const {
1358   st->print("\"%s\" ", name());
1359   Thread::print_on(st);
1360   st->cr();
1361 }
1362 
1363 
1364 // ======= WatcherThread ========
1365 
1366 // The watcher thread exists to simulate timer interrupts.  It should
1367 // be replaced by an abstraction over whatever native support for
1368 // timer interrupts exists on the platform.
1369 
1370 WatcherThread* WatcherThread::_watcher_thread   = NULL;
1371 bool WatcherThread::_startable = false;
1372 volatile bool  WatcherThread::_should_terminate = false;
1373 
1374 WatcherThread::WatcherThread() : NonJavaThread() {
1375   assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1376   if (os::create_thread(this, os::watcher_thread)) {
1377     _watcher_thread = this;
1378 
1379     // Set the watcher thread to the highest OS priority which should not be
1380     // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1381     // is created. The only normal thread using this priority is the reference
1382     // handler thread, which runs for very short intervals only.
1383     // If the VMThread's priority is not lower than the WatcherThread profiling
1384     // will be inaccurate.
1385     os::set_priority(this, MaxPriority);
1386     if (!DisableStartThread) {
1387       os::start_thread(this);
1388     }
1389   }
1390 }
1391 
1392 int WatcherThread::sleep() const {
1393   // The WatcherThread does not participate in the safepoint protocol
1394   // for the PeriodicTask_lock because it is not a JavaThread.
1395   MonitorLocker ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1396 
1397   if (_should_terminate) {
1398     // check for termination before we do any housekeeping or wait
1399     return 0;  // we did not sleep.
1400   }
1401 
1402   // remaining will be zero if there are no tasks,
1403   // causing the WatcherThread to sleep until a task is
1404   // enrolled
1405   int remaining = PeriodicTask::time_to_wait();
1406   int time_slept = 0;
1407 
1408   // we expect this to timeout - we only ever get unparked when
1409   // we should terminate or when a new task has been enrolled
1410   OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1411 
1412   jlong time_before_loop = os::javaTimeNanos();
1413 
1414   while (true) {
1415     bool timedout = ml.wait(remaining);
1416     jlong now = os::javaTimeNanos();
1417 
1418     if (remaining == 0) {
1419       // if we didn't have any tasks we could have waited for a long time
1420       // consider the time_slept zero and reset time_before_loop
1421       time_slept = 0;
1422       time_before_loop = now;
1423     } else {
1424       // need to recalculate since we might have new tasks in _tasks
1425       time_slept = (int) ((now - time_before_loop) / 1000000);
1426     }
1427 
1428     // Change to task list or spurious wakeup of some kind
1429     if (timedout || _should_terminate) {
1430       break;
1431     }
1432 
1433     remaining = PeriodicTask::time_to_wait();
1434     if (remaining == 0) {
1435       // Last task was just disenrolled so loop around and wait until
1436       // another task gets enrolled
1437       continue;
1438     }
1439 
1440     remaining -= time_slept;
1441     if (remaining <= 0) {
1442       break;
1443     }
1444   }
1445 
1446   return time_slept;
1447 }
1448 
1449 void WatcherThread::run() {
1450   assert(this == watcher_thread(), "just checking");
1451 
1452   this->set_active_handles(JNIHandleBlock::allocate_block());
1453   while (true) {
1454     assert(watcher_thread() == Thread::current(), "thread consistency check");
1455     assert(watcher_thread() == this, "thread consistency check");
1456 
1457     // Calculate how long it'll be until the next PeriodicTask work
1458     // should be done, and sleep that amount of time.
1459     int time_waited = sleep();
1460 
1461     if (VMError::is_error_reported()) {
1462       // A fatal error has happened, the error handler(VMError::report_and_die)
1463       // should abort JVM after creating an error log file. However in some
1464       // rare cases, the error handler itself might deadlock. Here periodically
1465       // check for error reporting timeouts, and if it happens, just proceed to
1466       // abort the VM.
1467 
1468       // This code is in WatcherThread because WatcherThread wakes up
1469       // periodically so the fatal error handler doesn't need to do anything;
1470       // also because the WatcherThread is less likely to crash than other
1471       // threads.
1472 
1473       for (;;) {
1474         // Note: we use naked sleep in this loop because we want to avoid using
1475         // any kind of VM infrastructure which may be broken at this point.
1476         if (VMError::check_timeout()) {
1477           // We hit error reporting timeout. Error reporting was interrupted and
1478           // will be wrapping things up now (closing files etc). Give it some more
1479           // time, then quit the VM.
1480           os::naked_short_sleep(200);
1481           // Print a message to stderr.
1482           fdStream err(defaultStream::output_fd());
1483           err.print_raw_cr("# [ timer expired, abort... ]");
1484           // skip atexit/vm_exit/vm_abort hooks
1485           os::die();
1486         }
1487 
1488         // Wait a second, then recheck for timeout.
1489         os::naked_short_sleep(999);
1490       }
1491     }
1492 
1493     if (_should_terminate) {
1494       // check for termination before posting the next tick
1495       break;
1496     }
1497 
1498     PeriodicTask::real_time_tick(time_waited);
1499   }
1500 
1501   // Signal that it is terminated
1502   {
1503     MutexLocker mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1504     _watcher_thread = NULL;
1505     Terminator_lock->notify_all();
1506   }
1507 }
1508 
1509 void WatcherThread::start() {
1510   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1511 
1512   if (watcher_thread() == NULL && _startable) {
1513     _should_terminate = false;
1514     // Create the single instance of WatcherThread
1515     new WatcherThread();
1516   }
1517 }
1518 
1519 void WatcherThread::make_startable() {
1520   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1521   _startable = true;
1522 }
1523 
1524 void WatcherThread::stop() {
1525   {
1526     // Follow normal safepoint aware lock enter protocol since the
1527     // WatcherThread is stopped by another JavaThread.
1528     MutexLocker ml(PeriodicTask_lock);
1529     _should_terminate = true;
1530 
1531     WatcherThread* watcher = watcher_thread();
1532     if (watcher != NULL) {
1533       // unpark the WatcherThread so it can see that it should terminate
1534       watcher->unpark();
1535     }
1536   }
1537 
1538   MonitorLocker mu(Terminator_lock);
1539 
1540   while (watcher_thread() != NULL) {
1541     // This wait should make safepoint checks, wait without a timeout,
1542     // and wait as a suspend-equivalent condition.
1543     mu.wait(0, Mutex::_as_suspend_equivalent_flag);
1544   }
1545 }
1546 
1547 void WatcherThread::unpark() {
1548   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1549   PeriodicTask_lock->notify();
1550 }
1551 
1552 void WatcherThread::print_on(outputStream* st) const {
1553   st->print("\"%s\" ", name());
1554   Thread::print_on(st);
1555   st->cr();
1556 }
1557 
1558 // ======= JavaThread ========
1559 
1560 #if INCLUDE_JVMCI
1561 
1562 jlong* JavaThread::_jvmci_old_thread_counters;
1563 
1564 bool jvmci_counters_include(JavaThread* thread) {
1565   return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1566 }
1567 
1568 void JavaThread::collect_counters(jlong* array, int length) {
1569   assert(length == JVMCICounterSize, "wrong value");
1570   for (int i = 0; i < length; i++) {
1571     array[i] = _jvmci_old_thread_counters[i];
1572   }
1573   for (JavaThreadIteratorWithHandle jtiwh; JavaThread *tp = jtiwh.next(); ) {
1574     if (jvmci_counters_include(tp)) {
1575       for (int i = 0; i < length; i++) {
1576         array[i] += tp->_jvmci_counters[i];
1577       }
1578     }
1579   }
1580 }
1581 
1582 // Attempt to enlarge the array for per thread counters.
1583 jlong* resize_counters_array(jlong* old_counters, int current_size, int new_size) {
1584   jlong* new_counters = NEW_C_HEAP_ARRAY(jlong, new_size, mtJVMCI);
1585   if (old_counters == NULL) {
1586     old_counters = new_counters;
1587     memset(old_counters, 0, sizeof(jlong) * new_size);
1588   } else {
1589     for (int i = 0; i < MIN2((int) current_size, new_size); i++) {
1590       new_counters[i] = old_counters[i];
1591     }
1592     if (new_size > current_size) {
1593       memset(new_counters + current_size, 0, sizeof(jlong) * (new_size - current_size));
1594     }
1595     FREE_C_HEAP_ARRAY(jlong, old_counters);
1596   }
1597   return new_counters;
1598 }
1599 
1600 // Attempt to enlarge the array for per thread counters.
1601 void JavaThread::resize_counters(int current_size, int new_size) {
1602   _jvmci_counters = resize_counters_array(_jvmci_counters, current_size, new_size);
1603 }
1604 
1605 class VM_JVMCIResizeCounters : public VM_Operation {
1606  private:
1607   int _new_size;
1608 
1609  public:
1610   VM_JVMCIResizeCounters(int new_size) : _new_size(new_size) { }
1611   VMOp_Type type()                  const        { return VMOp_JVMCIResizeCounters; }
1612   bool allow_nested_vm_operations() const        { return true; }
1613   void doit() {
1614     // Resize the old thread counters array
1615     jlong* new_counters = resize_counters_array(JavaThread::_jvmci_old_thread_counters, JVMCICounterSize, _new_size);
1616     JavaThread::_jvmci_old_thread_counters = new_counters;
1617 
1618     // Now resize each threads array
1619     for (JavaThreadIteratorWithHandle jtiwh; JavaThread *tp = jtiwh.next(); ) {
1620       tp->resize_counters(JVMCICounterSize, _new_size);
1621     }
1622     JVMCICounterSize = _new_size;
1623   }
1624 };
1625 
1626 void JavaThread::resize_all_jvmci_counters(int new_size) {
1627   VM_JVMCIResizeCounters op(new_size);
1628   VMThread::execute(&op);
1629 }
1630 
1631 #endif // INCLUDE_JVMCI
1632 
1633 // A JavaThread is a normal Java thread
1634 
1635 void JavaThread::initialize() {
1636   // Initialize fields
1637 
1638   set_saved_exception_pc(NULL);
1639   set_threadObj(NULL);
1640   _anchor.clear();
1641   set_entry_point(NULL);
1642   set_jni_functions(jni_functions());
1643   set_callee_target(NULL);
1644   set_vm_result(NULL);
1645   set_vm_result_2(NULL);
1646   set_vframe_array_head(NULL);
1647   set_vframe_array_last(NULL);
1648   set_deferred_locals(NULL);
1649   set_deopt_mark(NULL);
1650   set_deopt_compiled_method(NULL);
1651   set_monitor_chunks(NULL);
1652   _on_thread_list = false;
1653   _thread_state = _thread_new;
1654   _terminated = _not_terminated;
1655   _array_for_gc = NULL;
1656   _suspend_equivalent = false;
1657   _in_deopt_handler = 0;
1658   _doing_unsafe_access = false;
1659   _stack_guard_state = stack_guard_unused;
1660 #if INCLUDE_JVMCI
1661   _pending_monitorenter = false;
1662   _pending_deoptimization = -1;
1663   _pending_failed_speculation = 0;
1664   _pending_transfer_to_interpreter = false;
1665   _in_retryable_allocation = false;
1666   _jvmci._alternate_call_target = NULL;
1667   assert(_jvmci._implicit_exception_pc == NULL, "must be");
1668   _jvmci_counters = NULL;
1669   if (JVMCICounterSize > 0) {
1670     resize_counters(0, (int) JVMCICounterSize);
1671   }
1672 #endif // INCLUDE_JVMCI
1673   _reserved_stack_activation = NULL;  // stack base not known yet
1674   (void)const_cast<oop&>(_exception_oop = oop(NULL));
1675   _exception_pc  = 0;
1676   _exception_handler_pc = 0;
1677   _is_method_handle_return = 0;
1678   _jvmti_thread_state= NULL;
1679   _should_post_on_exceptions_flag = JNI_FALSE;
1680   _interp_only_mode    = 0;
1681   _special_runtime_exit_condition = _no_async_condition;
1682   _pending_async_exception = NULL;
1683   _thread_stat = NULL;
1684   _thread_stat = new ThreadStatistics();
1685   _jni_active_critical = 0;
1686   _pending_jni_exception_check_fn = NULL;
1687   _do_not_unlock_if_synchronized = false;
1688   _cached_monitor_info = NULL;
1689   _parker = Parker::Allocate(this);
1690   _SleepEvent = ParkEvent::Allocate(this);
1691   // Setup safepoint state info for this thread
1692   ThreadSafepointState::create(this);
1693 
1694   debug_only(_java_call_counter = 0);
1695 
1696   // JVMTI PopFrame support
1697   _popframe_condition = popframe_inactive;
1698   _popframe_preserved_args = NULL;
1699   _popframe_preserved_args_size = 0;
1700   _frames_to_pop_failed_realloc = 0;
1701 
1702   SafepointMechanism::initialize_header(this);
1703 
1704   _class_to_be_initialized = NULL;
1705 
1706   pd_initialize();
1707 }
1708 
1709 JavaThread::JavaThread(bool is_attaching_via_jni) :
1710                        Thread() {
1711   initialize();
1712   if (is_attaching_via_jni) {
1713     _jni_attach_state = _attaching_via_jni;
1714   } else {
1715     _jni_attach_state = _not_attaching_via_jni;
1716   }
1717   assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1718 }
1719 
1720 
1721 // interrupt support
1722 
1723 void JavaThread::interrupt() {
1724   debug_only(check_for_dangling_thread_pointer(this);)
1725 
1726   // For Windows _interrupt_event
1727   osthread()->set_interrupted(true);
1728 
1729   // For Thread.sleep
1730   _SleepEvent->unpark();
1731 
1732   // For JSR166 LockSupport.park
1733   parker()->unpark();
1734 
1735   // For ObjectMonitor and JvmtiRawMonitor
1736   _ParkEvent->unpark();
1737 }
1738 
1739 
1740 bool JavaThread::is_interrupted(bool clear_interrupted) {
1741   debug_only(check_for_dangling_thread_pointer(this);)
1742 
1743   if (threadObj() == NULL) {
1744     // If there is no j.l.Thread then it is impossible to have
1745     // been interrupted. We can find NULL during VM initialization
1746     // or when a JNI thread is still in the process of attaching.
1747     // In such cases this must be the current thread.
1748     assert(this == Thread::current(), "invariant");
1749     return false;
1750   }
1751 
1752   bool interrupted = java_lang_Thread::interrupted(threadObj());
1753 
1754   // NOTE that since there is no "lock" around the interrupt and
1755   // is_interrupted operations, there is the possibility that the
1756   // interrupted flag will be "false" but that the
1757   // low-level events will be in the signaled state. This is
1758   // intentional. The effect of this is that Object.wait() and
1759   // LockSupport.park() will appear to have a spurious wakeup, which
1760   // is allowed and not harmful, and the possibility is so rare that
1761   // it is not worth the added complexity to add yet another lock.
1762   // For the sleep event an explicit reset is performed on entry
1763   // to JavaThread::sleep, so there is no early return. It has also been
1764   // recommended not to put the interrupted flag into the "event"
1765   // structure because it hides the issue.
1766   // Also, because there is no lock, we must only clear the interrupt
1767   // state if we are going to report that we were interrupted; otherwise
1768   // an interrupt that happens just after we read the field would be lost.
1769   if (interrupted && clear_interrupted) {
1770     assert(this == Thread::current(), "only the current thread can clear");
1771     java_lang_Thread::set_interrupted(threadObj(), false);
1772     osthread()->set_interrupted(false);
1773   }
1774 
1775   return interrupted;
1776 }
1777 
1778 bool JavaThread::reguard_stack(address cur_sp) {
1779   if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1780       && _stack_guard_state != stack_guard_reserved_disabled) {
1781     return true; // Stack already guarded or guard pages not needed.
1782   }
1783 
1784   if (register_stack_overflow()) {
1785     // For those architectures which have separate register and
1786     // memory stacks, we must check the register stack to see if
1787     // it has overflowed.
1788     return false;
1789   }
1790 
1791   // Java code never executes within the yellow zone: the latter is only
1792   // there to provoke an exception during stack banging.  If java code
1793   // is executing there, either StackShadowPages should be larger, or
1794   // some exception code in c1, c2 or the interpreter isn't unwinding
1795   // when it should.
1796   guarantee(cur_sp > stack_reserved_zone_base(),
1797             "not enough space to reguard - increase StackShadowPages");
1798   if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1799     enable_stack_yellow_reserved_zone();
1800     if (reserved_stack_activation() != stack_base()) {
1801       set_reserved_stack_activation(stack_base());
1802     }
1803   } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1804     set_reserved_stack_activation(stack_base());
1805     enable_stack_reserved_zone();
1806   }
1807   return true;
1808 }
1809 
1810 bool JavaThread::reguard_stack(void) {
1811   return reguard_stack(os::current_stack_pointer());
1812 }
1813 
1814 void JavaThread::block_if_vm_exited() {
1815   if (_terminated == _vm_exited) {
1816     // _vm_exited is set at safepoint, and Threads_lock is never released
1817     // we will block here forever.
1818     // Here we can be doing a jump from a safe state to an unsafe state without
1819     // proper transition, but it happens after the final safepoint has begun.
1820     set_thread_state(_thread_in_vm);
1821     Threads_lock->lock();
1822     ShouldNotReachHere();
1823   }
1824 }
1825 
1826 
1827 // Remove this ifdef when C1 is ported to the compiler interface.
1828 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1829 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1830 
1831 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1832                        Thread() {
1833   initialize();
1834   _jni_attach_state = _not_attaching_via_jni;
1835   set_entry_point(entry_point);
1836   // Create the native thread itself.
1837   // %note runtime_23
1838   os::ThreadType thr_type = os::java_thread;
1839   thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1840                                                      os::java_thread;
1841   os::create_thread(this, thr_type, stack_sz);
1842   // The _osthread may be NULL here because we ran out of memory (too many threads active).
1843   // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1844   // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1845   // the exception consists of creating the exception object & initializing it, initialization
1846   // will leave the VM via a JavaCall and then all locks must be unlocked).
1847   //
1848   // The thread is still suspended when we reach here. Thread must be explicit started
1849   // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1850   // by calling Threads:add. The reason why this is not done here, is because the thread
1851   // object must be fully initialized (take a look at JVM_Start)
1852 }
1853 
1854 JavaThread::~JavaThread() {
1855 
1856   // JSR166 -- return the parker to the free list
1857   Parker::Release(_parker);
1858   _parker = NULL;
1859 
1860   // Return the sleep event to the free list
1861   ParkEvent::Release(_SleepEvent);
1862   _SleepEvent = NULL;
1863 
1864   // Free any remaining  previous UnrollBlock
1865   vframeArray* old_array = vframe_array_last();
1866 
1867   if (old_array != NULL) {
1868     Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1869     old_array->set_unroll_block(NULL);
1870     delete old_info;
1871     delete old_array;
1872   }
1873 
1874   GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1875   if (deferred != NULL) {
1876     // This can only happen if thread is destroyed before deoptimization occurs.
1877     assert(deferred->length() != 0, "empty array!");
1878     do {
1879       jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1880       deferred->remove_at(0);
1881       // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1882       delete dlv;
1883     } while (deferred->length() != 0);
1884     delete deferred;
1885   }
1886 
1887   // All Java related clean up happens in exit
1888   ThreadSafepointState::destroy(this);
1889   if (_thread_stat != NULL) delete _thread_stat;
1890 
1891 #if INCLUDE_JVMCI
1892   if (JVMCICounterSize > 0) {
1893     if (jvmci_counters_include(this)) {
1894       for (int i = 0; i < JVMCICounterSize; i++) {
1895         _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1896       }
1897     }
1898     FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1899   }
1900 #endif // INCLUDE_JVMCI
1901 }
1902 
1903 
1904 // First JavaThread specific code executed by a new Java thread.
1905 void JavaThread::pre_run() {
1906   // empty - see comments in run()
1907 }
1908 
1909 // The main routine called by a new Java thread. This isn't overridden
1910 // by subclasses, instead different subclasses define a different "entry_point"
1911 // which defines the actual logic for that kind of thread.
1912 void JavaThread::run() {
1913   // initialize thread-local alloc buffer related fields
1914   this->initialize_tlab();
1915 
1916   // Used to test validity of stack trace backs.
1917   // This can't be moved into pre_run() else we invalidate
1918   // the requirement that thread_main_inner is lower on
1919   // the stack. Consequently all the initialization logic
1920   // stays here in run() rather than pre_run().
1921   this->record_base_of_stack_pointer();
1922 
1923   this->create_stack_guard_pages();
1924 
1925   this->cache_global_variables();
1926 
1927   // Thread is now sufficiently initialized to be handled by the safepoint code as being
1928   // in the VM. Change thread state from _thread_new to _thread_in_vm
1929   ThreadStateTransition::transition(this, _thread_new, _thread_in_vm);
1930   // Before a thread is on the threads list it is always safe, so after leaving the
1931   // _thread_new we should emit a instruction barrier. The distance to modified code
1932   // from here is probably far enough, but this is consistent and safe.
1933   OrderAccess::cross_modify_fence();
1934 
1935   assert(JavaThread::current() == this, "sanity check");
1936   assert(!Thread::current()->owns_locks(), "sanity check");
1937 
1938   DTRACE_THREAD_PROBE(start, this);
1939 
1940   // This operation might block. We call that after all safepoint checks for a new thread has
1941   // been completed.
1942   this->set_active_handles(JNIHandleBlock::allocate_block());
1943 
1944   if (JvmtiExport::should_post_thread_life()) {
1945     JvmtiExport::post_thread_start(this);
1946 
1947   }
1948 
1949   // We call another function to do the rest so we are sure that the stack addresses used
1950   // from there will be lower than the stack base just computed.
1951   thread_main_inner();
1952 }
1953 
1954 void JavaThread::thread_main_inner() {
1955   assert(JavaThread::current() == this, "sanity check");
1956   assert(this->threadObj() != NULL, "just checking");
1957 
1958   // Execute thread entry point unless this thread has a pending exception
1959   // or has been stopped before starting.
1960   // Note: Due to JVM_StopThread we can have pending exceptions already!
1961   if (!this->has_pending_exception() &&
1962       !java_lang_Thread::is_stillborn(this->threadObj())) {
1963     {
1964       ResourceMark rm(this);
1965       this->set_native_thread_name(this->get_thread_name());
1966     }
1967     HandleMark hm(this);
1968     this->entry_point()(this, this);
1969   }
1970 
1971   DTRACE_THREAD_PROBE(stop, this);
1972 
1973   // Cleanup is handled in post_run()
1974 }
1975 
1976 // Shared teardown for all JavaThreads
1977 void JavaThread::post_run() {
1978   this->exit(false);
1979   // Defer deletion to here to ensure 'this' is still referenceable in call_run
1980   // for any shared tear-down.
1981   this->smr_delete();
1982 }
1983 
1984 static void ensure_join(JavaThread* thread) {
1985   // We do not need to grab the Threads_lock, since we are operating on ourself.
1986   Handle threadObj(thread, thread->threadObj());
1987   assert(threadObj.not_null(), "java thread object must exist");
1988   ObjectLocker lock(threadObj, thread);
1989   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1990   thread->clear_pending_exception();
1991   // Thread is exiting. So set thread_status field in  java.lang.Thread class to TERMINATED.
1992   java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1993   // Clear the native thread instance - this makes isAlive return false and allows the join()
1994   // to complete once we've done the notify_all below
1995   java_lang_Thread::set_thread(threadObj(), NULL);
1996   lock.notify_all(thread);
1997   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1998   thread->clear_pending_exception();
1999 }
2000 
2001 static bool is_daemon(oop threadObj) {
2002   return (threadObj != NULL && java_lang_Thread::is_daemon(threadObj));
2003 }
2004 
2005 // For any new cleanup additions, please check to see if they need to be applied to
2006 // cleanup_failed_attach_current_thread as well.
2007 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
2008   assert(this == JavaThread::current(), "thread consistency check");
2009 
2010   elapsedTimer _timer_exit_phase1;
2011   elapsedTimer _timer_exit_phase2;
2012   elapsedTimer _timer_exit_phase3;
2013   elapsedTimer _timer_exit_phase4;
2014 
2015   if (log_is_enabled(Debug, os, thread, timer)) {
2016     _timer_exit_phase1.start();
2017   }
2018 
2019   HandleMark hm(this);
2020   Handle uncaught_exception(this, this->pending_exception());
2021   this->clear_pending_exception();
2022   Handle threadObj(this, this->threadObj());
2023   assert(threadObj.not_null(), "Java thread object should be created");
2024 
2025   // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
2026   {
2027     EXCEPTION_MARK;
2028 
2029     CLEAR_PENDING_EXCEPTION;
2030   }
2031   if (!destroy_vm) {
2032     if (uncaught_exception.not_null()) {
2033       EXCEPTION_MARK;
2034       // Call method Thread.dispatchUncaughtException().
2035       Klass* thread_klass = SystemDictionary::Thread_klass();
2036       JavaValue result(T_VOID);
2037       JavaCalls::call_virtual(&result,
2038                               threadObj, thread_klass,
2039                               vmSymbols::dispatchUncaughtException_name(),
2040                               vmSymbols::throwable_void_signature(),
2041                               uncaught_exception,
2042                               THREAD);
2043       if (HAS_PENDING_EXCEPTION) {
2044         ResourceMark rm(this);
2045         jio_fprintf(defaultStream::error_stream(),
2046                     "\nException: %s thrown from the UncaughtExceptionHandler"
2047                     " in thread \"%s\"\n",
2048                     pending_exception()->klass()->external_name(),
2049                     get_thread_name());
2050         CLEAR_PENDING_EXCEPTION;
2051       }
2052     }
2053     JFR_ONLY(Jfr::on_java_thread_dismantle(this);)
2054 
2055     // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
2056     // the execution of the method. If that is not enough, then we don't really care. Thread.stop
2057     // is deprecated anyhow.
2058     if (!is_Compiler_thread()) {
2059       int count = 3;
2060       while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
2061         EXCEPTION_MARK;
2062         JavaValue result(T_VOID);
2063         Klass* thread_klass = SystemDictionary::Thread_klass();
2064         JavaCalls::call_virtual(&result,
2065                                 threadObj, thread_klass,
2066                                 vmSymbols::exit_method_name(),
2067                                 vmSymbols::void_method_signature(),
2068                                 THREAD);
2069         CLEAR_PENDING_EXCEPTION;
2070       }
2071     }
2072     // notify JVMTI
2073     if (JvmtiExport::should_post_thread_life()) {
2074       JvmtiExport::post_thread_end(this);
2075     }
2076 
2077     // We have notified the agents that we are exiting, before we go on,
2078     // we must check for a pending external suspend request and honor it
2079     // in order to not surprise the thread that made the suspend request.
2080     while (true) {
2081       {
2082         MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2083         if (!is_external_suspend()) {
2084           set_terminated(_thread_exiting);
2085           ThreadService::current_thread_exiting(this, is_daemon(threadObj()));
2086           break;
2087         }
2088         // Implied else:
2089         // Things get a little tricky here. We have a pending external
2090         // suspend request, but we are holding the SR_lock so we
2091         // can't just self-suspend. So we temporarily drop the lock
2092         // and then self-suspend.
2093       }
2094 
2095       ThreadBlockInVM tbivm(this);
2096       java_suspend_self();
2097 
2098       // We're done with this suspend request, but we have to loop around
2099       // and check again. Eventually we will get SR_lock without a pending
2100       // external suspend request and will be able to mark ourselves as
2101       // exiting.
2102     }
2103     // no more external suspends are allowed at this point
2104   } else {
2105     assert(!is_terminated() && !is_exiting(), "must not be exiting");
2106     // before_exit() has already posted JVMTI THREAD_END events
2107   }
2108 
2109   if (log_is_enabled(Debug, os, thread, timer)) {
2110     _timer_exit_phase1.stop();
2111     _timer_exit_phase2.start();
2112   }
2113 
2114   // Capture daemon status before the thread is marked as terminated.
2115   bool daemon = is_daemon(threadObj());
2116 
2117   // Notify waiters on thread object. This has to be done after exit() is called
2118   // on the thread (if the thread is the last thread in a daemon ThreadGroup the
2119   // group should have the destroyed bit set before waiters are notified).
2120   ensure_join(this);
2121   assert(!this->has_pending_exception(), "ensure_join should have cleared");
2122 
2123   if (log_is_enabled(Debug, os, thread, timer)) {
2124     _timer_exit_phase2.stop();
2125     _timer_exit_phase3.start();
2126   }
2127   // 6282335 JNI DetachCurrentThread spec states that all Java monitors
2128   // held by this thread must be released. The spec does not distinguish
2129   // between JNI-acquired and regular Java monitors. We can only see
2130   // regular Java monitors here if monitor enter-exit matching is broken.
2131   //
2132   // ensure_join() ignores IllegalThreadStateExceptions, and so does
2133   // ObjectSynchronizer::release_monitors_owned_by_thread().
2134   if (exit_type == jni_detach) {
2135     // Sanity check even though JNI DetachCurrentThread() would have
2136     // returned JNI_ERR if there was a Java frame. JavaThread exit
2137     // should be done executing Java code by the time we get here.
2138     assert(!this->has_last_Java_frame(),
2139            "should not have a Java frame when detaching or exiting");
2140     ObjectSynchronizer::release_monitors_owned_by_thread(this);
2141     assert(!this->has_pending_exception(), "release_monitors should have cleared");
2142   }
2143 
2144   // These things needs to be done while we are still a Java Thread. Make sure that thread
2145   // is in a consistent state, in case GC happens
2146   JFR_ONLY(Jfr::on_thread_exit(this);)
2147 
2148   if (active_handles() != NULL) {
2149     JNIHandleBlock* block = active_handles();
2150     set_active_handles(NULL);
2151     JNIHandleBlock::release_block(block);
2152   }
2153 
2154   if (free_handle_block() != NULL) {
2155     JNIHandleBlock* block = free_handle_block();
2156     set_free_handle_block(NULL);
2157     JNIHandleBlock::release_block(block);
2158   }
2159 
2160   // These have to be removed while this is still a valid thread.
2161   remove_stack_guard_pages();
2162 
2163   if (UseTLAB) {
2164     tlab().retire();
2165   }
2166 
2167   if (JvmtiEnv::environments_might_exist()) {
2168     JvmtiExport::cleanup_thread(this);
2169   }
2170 
2171   // We must flush any deferred card marks and other various GC barrier
2172   // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer)
2173   // before removing a thread from the list of active threads.
2174   BarrierSet::barrier_set()->on_thread_detach(this);
2175 
2176   log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
2177     exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
2178     os::current_thread_id());
2179 
2180   if (log_is_enabled(Debug, os, thread, timer)) {
2181     _timer_exit_phase3.stop();
2182     _timer_exit_phase4.start();
2183   }
2184   // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
2185   Threads::remove(this, daemon);
2186 
2187   if (log_is_enabled(Debug, os, thread, timer)) {
2188     _timer_exit_phase4.stop();
2189     ResourceMark rm(this);
2190     log_debug(os, thread, timer)("name='%s'"
2191                                  ", exit-phase1=" JLONG_FORMAT
2192                                  ", exit-phase2=" JLONG_FORMAT
2193                                  ", exit-phase3=" JLONG_FORMAT
2194                                  ", exit-phase4=" JLONG_FORMAT,
2195                                  get_thread_name(),
2196                                  _timer_exit_phase1.milliseconds(),
2197                                  _timer_exit_phase2.milliseconds(),
2198                                  _timer_exit_phase3.milliseconds(),
2199                                  _timer_exit_phase4.milliseconds());
2200   }
2201 }
2202 
2203 void JavaThread::cleanup_failed_attach_current_thread(bool is_daemon) {
2204   if (active_handles() != NULL) {
2205     JNIHandleBlock* block = active_handles();
2206     set_active_handles(NULL);
2207     JNIHandleBlock::release_block(block);
2208   }
2209 
2210   if (free_handle_block() != NULL) {
2211     JNIHandleBlock* block = free_handle_block();
2212     set_free_handle_block(NULL);
2213     JNIHandleBlock::release_block(block);
2214   }
2215 
2216   // These have to be removed while this is still a valid thread.
2217   remove_stack_guard_pages();
2218 
2219   if (UseTLAB) {
2220     tlab().retire();
2221   }
2222 
2223   BarrierSet::barrier_set()->on_thread_detach(this);
2224 
2225   Threads::remove(this, is_daemon);
2226   this->smr_delete();
2227 }
2228 
2229 JavaThread* JavaThread::active() {
2230   Thread* thread = Thread::current();
2231   if (thread->is_Java_thread()) {
2232     return (JavaThread*) thread;
2233   } else {
2234     assert(thread->is_VM_thread(), "this must be a vm thread");
2235     VM_Operation* op = ((VMThread*) thread)->vm_operation();
2236     JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2237     assert(ret->is_Java_thread(), "must be a Java thread");
2238     return ret;
2239   }
2240 }
2241 
2242 bool JavaThread::is_lock_owned(address adr) const {
2243   if (Thread::is_lock_owned(adr)) return true;
2244 
2245   for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2246     if (chunk->contains(adr)) return true;
2247   }
2248 
2249   return false;
2250 }
2251 
2252 
2253 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2254   chunk->set_next(monitor_chunks());
2255   set_monitor_chunks(chunk);
2256 }
2257 
2258 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2259   guarantee(monitor_chunks() != NULL, "must be non empty");
2260   if (monitor_chunks() == chunk) {
2261     set_monitor_chunks(chunk->next());
2262   } else {
2263     MonitorChunk* prev = monitor_chunks();
2264     while (prev->next() != chunk) prev = prev->next();
2265     prev->set_next(chunk->next());
2266   }
2267 }
2268 
2269 // JVM support.
2270 
2271 // Note: this function shouldn't block if it's called in
2272 // _thread_in_native_trans state (such as from
2273 // check_special_condition_for_native_trans()).
2274 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2275 
2276   if (has_last_Java_frame() && has_async_condition()) {
2277     // If we are at a polling page safepoint (not a poll return)
2278     // then we must defer async exception because live registers
2279     // will be clobbered by the exception path. Poll return is
2280     // ok because the call we a returning from already collides
2281     // with exception handling registers and so there is no issue.
2282     // (The exception handling path kills call result registers but
2283     //  this is ok since the exception kills the result anyway).
2284 
2285     if (is_at_poll_safepoint()) {
2286       // if the code we are returning to has deoptimized we must defer
2287       // the exception otherwise live registers get clobbered on the
2288       // exception path before deoptimization is able to retrieve them.
2289       //
2290       RegisterMap map(this, false);
2291       frame caller_fr = last_frame().sender(&map);
2292       assert(caller_fr.is_compiled_frame(), "what?");
2293       if (caller_fr.is_deoptimized_frame()) {
2294         log_info(exceptions)("deferred async exception at compiled safepoint");
2295         return;
2296       }
2297     }
2298   }
2299 
2300   JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2301   if (condition == _no_async_condition) {
2302     // Conditions have changed since has_special_runtime_exit_condition()
2303     // was called:
2304     // - if we were here only because of an external suspend request,
2305     //   then that was taken care of above (or cancelled) so we are done
2306     // - if we were here because of another async request, then it has
2307     //   been cleared between the has_special_runtime_exit_condition()
2308     //   and now so again we are done
2309     return;
2310   }
2311 
2312   // Check for pending async. exception
2313   if (_pending_async_exception != NULL) {
2314     // Only overwrite an already pending exception, if it is not a threadDeath.
2315     if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2316 
2317       // We cannot call Exceptions::_throw(...) here because we cannot block
2318       set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2319 
2320       LogTarget(Info, exceptions) lt;
2321       if (lt.is_enabled()) {
2322         ResourceMark rm;
2323         LogStream ls(lt);
2324         ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2325           if (has_last_Java_frame()) {
2326             frame f = last_frame();
2327            ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2328           }
2329         ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2330       }
2331       _pending_async_exception = NULL;
2332       clear_has_async_exception();
2333     }
2334   }
2335 
2336   if (check_unsafe_error &&
2337       condition == _async_unsafe_access_error && !has_pending_exception()) {
2338     condition = _no_async_condition;  // done
2339     switch (thread_state()) {
2340     case _thread_in_vm: {
2341       JavaThread* THREAD = this;
2342       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2343     }
2344     case _thread_in_native: {
2345       ThreadInVMfromNative tiv(this);
2346       JavaThread* THREAD = this;
2347       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2348     }
2349     case _thread_in_Java: {
2350       ThreadInVMfromJava tiv(this);
2351       JavaThread* THREAD = this;
2352       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2353     }
2354     default:
2355       ShouldNotReachHere();
2356     }
2357   }
2358 
2359   assert(condition == _no_async_condition || has_pending_exception() ||
2360          (!check_unsafe_error && condition == _async_unsafe_access_error),
2361          "must have handled the async condition, if no exception");
2362 }
2363 
2364 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2365 
2366   // Check for pending external suspend.
2367   if (is_external_suspend_with_lock()) {
2368     frame_anchor()->make_walkable(this);
2369     java_suspend_self_with_safepoint_check();
2370   }
2371 
2372   // We might be here for reasons in addition to the self-suspend request
2373   // so check for other async requests.
2374   if (check_asyncs) {
2375     check_and_handle_async_exceptions();
2376   }
2377 
2378   JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);)
2379 }
2380 
2381 void JavaThread::send_thread_stop(oop java_throwable)  {
2382   ResourceMark rm;
2383   assert(Thread::current()->is_VM_thread() || Thread::current() == this, "should be in the vm thread");
2384 
2385   // Do not throw asynchronous exceptions against the compiler thread
2386   // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2387   if (!can_call_java()) return;
2388 
2389   {
2390     // Actually throw the Throwable against the target Thread - however
2391     // only if there is no thread death exception installed already.
2392     if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2393       // If the topmost frame is a runtime stub, then we are calling into
2394       // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2395       // must deoptimize the caller before continuing, as the compiled  exception handler table
2396       // may not be valid
2397       if (has_last_Java_frame()) {
2398         frame f = last_frame();
2399         if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2400           RegisterMap reg_map(this, false);
2401           frame compiled_frame = f.sender(&reg_map);
2402           if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2403             Deoptimization::deoptimize(this, compiled_frame);
2404           }
2405         }
2406       }
2407 
2408       // Set async. pending exception in thread.
2409       set_pending_async_exception(java_throwable);
2410 
2411       if (log_is_enabled(Info, exceptions)) {
2412          ResourceMark rm;
2413         log_info(exceptions)("Pending Async. exception installed of type: %s",
2414                              InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2415       }
2416       // for AbortVMOnException flag
2417       Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2418     }
2419   }
2420 
2421 
2422   // Interrupt thread so it will wake up from a potential wait()/sleep()/park()
2423   java_lang_Thread::set_interrupted(threadObj(), true);
2424   this->interrupt();
2425 }
2426 
2427 // External suspension mechanism.
2428 //
2429 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2430 // to any VM_locks and it is at a transition
2431 // Self-suspension will happen on the transition out of the vm.
2432 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2433 //
2434 // Guarantees on return:
2435 //   + Target thread will not execute any new bytecode (that's why we need to
2436 //     force a safepoint)
2437 //   + Target thread will not enter any new monitors
2438 //
2439 void JavaThread::java_suspend() {
2440   ThreadsListHandle tlh;
2441   if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) {
2442     return;
2443   }
2444 
2445   { MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2446     if (!is_external_suspend()) {
2447       // a racing resume has cancelled us; bail out now
2448       return;
2449     }
2450 
2451     // suspend is done
2452     uint32_t debug_bits = 0;
2453     // Warning: is_ext_suspend_completed() may temporarily drop the
2454     // SR_lock to allow the thread to reach a stable thread state if
2455     // it is currently in a transient thread state.
2456     if (is_ext_suspend_completed(false /* !called_by_wait */,
2457                                  SuspendRetryDelay, &debug_bits)) {
2458       return;
2459     }
2460   }
2461 
2462   if (Thread::current() == this) {
2463     // Safely self-suspend.
2464     // If we don't do this explicitly it will implicitly happen
2465     // before we transition back to Java, and on some other thread-state
2466     // transition paths, but not as we exit a JVM TI SuspendThread call.
2467     // As SuspendThread(current) must not return (until resumed) we must
2468     // self-suspend here.
2469     ThreadBlockInVM tbivm(this);
2470     java_suspend_self();
2471   } else {
2472     VM_ThreadSuspend vm_suspend;
2473     VMThread::execute(&vm_suspend);
2474   }
2475 }
2476 
2477 // Part II of external suspension.
2478 // A JavaThread self suspends when it detects a pending external suspend
2479 // request. This is usually on transitions. It is also done in places
2480 // where continuing to the next transition would surprise the caller,
2481 // e.g., monitor entry.
2482 //
2483 // Returns the number of times that the thread self-suspended.
2484 //
2485 // Note: DO NOT call java_suspend_self() when you just want to block current
2486 //       thread. java_suspend_self() is the second stage of cooperative
2487 //       suspension for external suspend requests and should only be used
2488 //       to complete an external suspend request.
2489 //
2490 int JavaThread::java_suspend_self() {
2491   assert(thread_state() == _thread_blocked, "wrong state for java_suspend_self()");
2492   int ret = 0;
2493 
2494   // we are in the process of exiting so don't suspend
2495   if (is_exiting()) {
2496     clear_external_suspend();
2497     return ret;
2498   }
2499 
2500   assert(_anchor.walkable() ||
2501          (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2502          "must have walkable stack");
2503 
2504   MonitorLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2505 
2506   assert(!this->is_ext_suspended(),
2507          "a thread trying to self-suspend should not already be suspended");
2508 
2509   if (this->is_suspend_equivalent()) {
2510     // If we are self-suspending as a result of the lifting of a
2511     // suspend equivalent condition, then the suspend_equivalent
2512     // flag is not cleared until we set the ext_suspended flag so
2513     // that wait_for_ext_suspend_completion() returns consistent
2514     // results.
2515     this->clear_suspend_equivalent();
2516   }
2517 
2518   // A racing resume may have cancelled us before we grabbed SR_lock
2519   // above. Or another external suspend request could be waiting for us
2520   // by the time we return from SR_lock()->wait(). The thread
2521   // that requested the suspension may already be trying to walk our
2522   // stack and if we return now, we can change the stack out from under
2523   // it. This would be a "bad thing (TM)" and cause the stack walker
2524   // to crash. We stay self-suspended until there are no more pending
2525   // external suspend requests.
2526   while (is_external_suspend()) {
2527     ret++;
2528     this->set_ext_suspended();
2529 
2530     // _ext_suspended flag is cleared by java_resume()
2531     while (is_ext_suspended()) {
2532       ml.wait();
2533     }
2534   }
2535   return ret;
2536 }
2537 
2538 // Helper routine to set up the correct thread state before calling java_suspend_self.
2539 // This is called when regular thread-state transition helpers can't be used because
2540 // we can be in various states, in particular _thread_in_native_trans.
2541 // Because this thread is external suspended the safepoint code will count it as at
2542 // a safepoint, regardless of what its actual current thread-state is. But
2543 // is_ext_suspend_completed() may be waiting to see a thread transition from
2544 // _thread_in_native_trans to _thread_blocked. So we set the thread state directly
2545 // to _thread_blocked. The problem with setting thread state directly is that a
2546 // safepoint could happen just after java_suspend_self() returns after being resumed,
2547 // and the VM thread will see the _thread_blocked state. So we must check for a safepoint
2548 // after restoring the state to make sure we won't leave while a safepoint is in progress.
2549 // However, not all initial-states are allowed when performing a safepoint check, as we
2550 // should never be blocking at a safepoint whilst in those states. Of these 'bad' states
2551 // only _thread_in_native is possible when executing this code (based on our two callers).
2552 // A thread that is _thread_in_native is already safepoint-safe and so it doesn't matter
2553 // whether the VMThread sees the _thread_blocked state, or the _thread_in_native state,
2554 // and so we don't need the explicit safepoint check.
2555 
2556 void JavaThread::java_suspend_self_with_safepoint_check() {
2557   assert(this == Thread::current(), "invariant");
2558   JavaThreadState state = thread_state();
2559   set_thread_state(_thread_blocked);
2560   java_suspend_self();
2561   set_thread_state_fence(state);
2562   // Since we are not using a regular thread-state transition helper here,
2563   // we must manually emit the instruction barrier after leaving a safe state.
2564   OrderAccess::cross_modify_fence();
2565   if (state != _thread_in_native) {
2566     SafepointMechanism::block_if_requested(this);
2567   }
2568 }
2569 
2570 #ifdef ASSERT
2571 // Verify the JavaThread has not yet been published in the Threads::list, and
2572 // hence doesn't need protection from concurrent access at this stage.
2573 void JavaThread::verify_not_published() {
2574   // Cannot create a ThreadsListHandle here and check !tlh.includes(this)
2575   // since an unpublished JavaThread doesn't participate in the
2576   // Thread-SMR protocol for keeping a ThreadsList alive.
2577   assert(!on_thread_list(), "JavaThread shouldn't have been published yet!");
2578 }
2579 #endif
2580 
2581 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2582 // progress or when _suspend_flags is non-zero.
2583 // Current thread needs to self-suspend if there is a suspend request and/or
2584 // block if a safepoint is in progress.
2585 // Async exception ISN'T checked.
2586 // Note only the ThreadInVMfromNative transition can call this function
2587 // directly and when thread state is _thread_in_native_trans
2588 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2589   assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2590 
2591   assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2592 
2593   if (thread->is_external_suspend()) {
2594     thread->java_suspend_self_with_safepoint_check();
2595   } else {
2596     SafepointMechanism::block_if_requested(thread);
2597   }
2598 
2599   JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(thread);)
2600 }
2601 
2602 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2603 // progress or when _suspend_flags is non-zero.
2604 // Current thread needs to self-suspend if there is a suspend request and/or
2605 // block if a safepoint is in progress.
2606 // Also check for pending async exception (not including unsafe access error).
2607 // Note only the native==>VM/Java barriers can call this function and when
2608 // thread state is _thread_in_native_trans.
2609 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2610   check_safepoint_and_suspend_for_native_trans(thread);
2611 
2612   if (thread->has_async_exception()) {
2613     // We are in _thread_in_native_trans state, don't handle unsafe
2614     // access error since that may block.
2615     thread->check_and_handle_async_exceptions(false);
2616   }
2617 }
2618 
2619 // This is a variant of the normal
2620 // check_special_condition_for_native_trans with slightly different
2621 // semantics for use by critical native wrappers.  It does all the
2622 // normal checks but also performs the transition back into
2623 // thread_in_Java state.  This is required so that critical natives
2624 // can potentially block and perform a GC if they are the last thread
2625 // exiting the GCLocker.
2626 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2627   check_special_condition_for_native_trans(thread);
2628 
2629   // Finish the transition
2630   thread->set_thread_state(_thread_in_Java);
2631 
2632   if (thread->do_critical_native_unlock()) {
2633     ThreadInVMfromJavaNoAsyncException tiv(thread);
2634     GCLocker::unlock_critical(thread);
2635     thread->clear_critical_native_unlock();
2636   }
2637 }
2638 
2639 // We need to guarantee the Threads_lock here, since resumes are not
2640 // allowed during safepoint synchronization
2641 // Can only resume from an external suspension
2642 void JavaThread::java_resume() {
2643   assert_locked_or_safepoint(Threads_lock);
2644 
2645   // Sanity check: thread is gone, has started exiting or the thread
2646   // was not externally suspended.
2647   ThreadsListHandle tlh;
2648   if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) {
2649     return;
2650   }
2651 
2652   MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2653 
2654   clear_external_suspend();
2655 
2656   if (is_ext_suspended()) {
2657     clear_ext_suspended();
2658     SR_lock()->notify_all();
2659   }
2660 }
2661 
2662 size_t JavaThread::_stack_red_zone_size = 0;
2663 size_t JavaThread::_stack_yellow_zone_size = 0;
2664 size_t JavaThread::_stack_reserved_zone_size = 0;
2665 size_t JavaThread::_stack_shadow_zone_size = 0;
2666 
2667 void JavaThread::create_stack_guard_pages() {
2668   if (!os::uses_stack_guard_pages() ||
2669       _stack_guard_state != stack_guard_unused ||
2670       (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) {
2671       log_info(os, thread)("Stack guard page creation for thread "
2672                            UINTX_FORMAT " disabled", os::current_thread_id());
2673     return;
2674   }
2675   address low_addr = stack_end();
2676   size_t len = stack_guard_zone_size();
2677 
2678   assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2679   assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2680 
2681   int must_commit = os::must_commit_stack_guard_pages();
2682   // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2683 
2684   if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2685     log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2686     return;
2687   }
2688 
2689   if (os::guard_memory((char *) low_addr, len)) {
2690     _stack_guard_state = stack_guard_enabled;
2691   } else {
2692     log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2693       PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2694     if (os::uncommit_memory((char *) low_addr, len)) {
2695       log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2696     }
2697     return;
2698   }
2699 
2700   log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2701     PTR_FORMAT "-" PTR_FORMAT ".",
2702     os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2703 }
2704 
2705 void JavaThread::remove_stack_guard_pages() {
2706   assert(Thread::current() == this, "from different thread");
2707   if (_stack_guard_state == stack_guard_unused) return;
2708   address low_addr = stack_end();
2709   size_t len = stack_guard_zone_size();
2710 
2711   if (os::must_commit_stack_guard_pages()) {
2712     if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2713       _stack_guard_state = stack_guard_unused;
2714     } else {
2715       log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2716         PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2717       return;
2718     }
2719   } else {
2720     if (_stack_guard_state == stack_guard_unused) return;
2721     if (os::unguard_memory((char *) low_addr, len)) {
2722       _stack_guard_state = stack_guard_unused;
2723     } else {
2724       log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2725         PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2726       return;
2727     }
2728   }
2729 
2730   log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2731     PTR_FORMAT "-" PTR_FORMAT ".",
2732     os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2733 }
2734 
2735 void JavaThread::enable_stack_reserved_zone() {
2736   assert(_stack_guard_state == stack_guard_reserved_disabled, "inconsistent state");
2737 
2738   // The base notation is from the stack's point of view, growing downward.
2739   // We need to adjust it to work correctly with guard_memory()
2740   address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2741 
2742   guarantee(base < stack_base(),"Error calculating stack reserved zone");
2743   guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2744 
2745   if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2746     _stack_guard_state = stack_guard_enabled;
2747   } else {
2748     warning("Attempt to guard stack reserved zone failed.");
2749   }
2750   enable_register_stack_guard();
2751 }
2752 
2753 void JavaThread::disable_stack_reserved_zone() {
2754   assert(_stack_guard_state == stack_guard_enabled, "inconsistent state");
2755 
2756   // Simply return if called for a thread that does not use guard pages.
2757   if (_stack_guard_state != stack_guard_enabled) return;
2758 
2759   // The base notation is from the stack's point of view, growing downward.
2760   // We need to adjust it to work correctly with guard_memory()
2761   address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2762 
2763   if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2764     _stack_guard_state = stack_guard_reserved_disabled;
2765   } else {
2766     warning("Attempt to unguard stack reserved zone failed.");
2767   }
2768   disable_register_stack_guard();
2769 }
2770 
2771 void JavaThread::enable_stack_yellow_reserved_zone() {
2772   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2773   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2774 
2775   // The base notation is from the stacks point of view, growing downward.
2776   // We need to adjust it to work correctly with guard_memory()
2777   address base = stack_red_zone_base();
2778 
2779   guarantee(base < stack_base(), "Error calculating stack yellow zone");
2780   guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2781 
2782   if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2783     _stack_guard_state = stack_guard_enabled;
2784   } else {
2785     warning("Attempt to guard stack yellow zone failed.");
2786   }
2787   enable_register_stack_guard();
2788 }
2789 
2790 void JavaThread::disable_stack_yellow_reserved_zone() {
2791   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2792   assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2793 
2794   // Simply return if called for a thread that does not use guard pages.
2795   if (_stack_guard_state == stack_guard_unused) return;
2796 
2797   // The base notation is from the stacks point of view, growing downward.
2798   // We need to adjust it to work correctly with guard_memory()
2799   address base = stack_red_zone_base();
2800 
2801   if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2802     _stack_guard_state = stack_guard_yellow_reserved_disabled;
2803   } else {
2804     warning("Attempt to unguard stack yellow zone failed.");
2805   }
2806   disable_register_stack_guard();
2807 }
2808 
2809 void JavaThread::enable_stack_red_zone() {
2810   // The base notation is from the stacks point of view, growing downward.
2811   // We need to adjust it to work correctly with guard_memory()
2812   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2813   address base = stack_red_zone_base() - stack_red_zone_size();
2814 
2815   guarantee(base < stack_base(), "Error calculating stack red zone");
2816   guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2817 
2818   if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2819     warning("Attempt to guard stack red zone failed.");
2820   }
2821 }
2822 
2823 void JavaThread::disable_stack_red_zone() {
2824   // The base notation is from the stacks point of view, growing downward.
2825   // We need to adjust it to work correctly with guard_memory()
2826   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2827   address base = stack_red_zone_base() - stack_red_zone_size();
2828   if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2829     warning("Attempt to unguard stack red zone failed.");
2830   }
2831 }
2832 
2833 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2834   // ignore is there is no stack
2835   if (!has_last_Java_frame()) return;
2836   // traverse the stack frames. Starts from top frame.
2837   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2838     frame* fr = fst.current();
2839     f(fr, fst.register_map());
2840   }
2841 }
2842 
2843 
2844 #ifndef PRODUCT
2845 // Deoptimization
2846 // Function for testing deoptimization
2847 void JavaThread::deoptimize() {
2848   StackFrameStream fst(this, false);
2849   bool deopt = false;           // Dump stack only if a deopt actually happens.
2850   bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2851   // Iterate over all frames in the thread and deoptimize
2852   for (; !fst.is_done(); fst.next()) {
2853     if (fst.current()->can_be_deoptimized()) {
2854 
2855       if (only_at) {
2856         // Deoptimize only at particular bcis.  DeoptimizeOnlyAt
2857         // consists of comma or carriage return separated numbers so
2858         // search for the current bci in that string.
2859         address pc = fst.current()->pc();
2860         nmethod* nm =  (nmethod*) fst.current()->cb();
2861         ScopeDesc* sd = nm->scope_desc_at(pc);
2862         char buffer[8];
2863         jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2864         size_t len = strlen(buffer);
2865         const char * found = strstr(DeoptimizeOnlyAt, buffer);
2866         while (found != NULL) {
2867           if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2868               (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2869             // Check that the bci found is bracketed by terminators.
2870             break;
2871           }
2872           found = strstr(found + 1, buffer);
2873         }
2874         if (!found) {
2875           continue;
2876         }
2877       }
2878 
2879       if (DebugDeoptimization && !deopt) {
2880         deopt = true; // One-time only print before deopt
2881         tty->print_cr("[BEFORE Deoptimization]");
2882         trace_frames();
2883         trace_stack();
2884       }
2885       Deoptimization::deoptimize(this, *fst.current());
2886     }
2887   }
2888 
2889   if (DebugDeoptimization && deopt) {
2890     tty->print_cr("[AFTER Deoptimization]");
2891     trace_frames();
2892   }
2893 }
2894 
2895 
2896 // Make zombies
2897 void JavaThread::make_zombies() {
2898   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2899     if (fst.current()->can_be_deoptimized()) {
2900       // it is a Java nmethod
2901       nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2902       nm->make_not_entrant();
2903     }
2904   }
2905 }
2906 #endif // PRODUCT
2907 
2908 
2909 void JavaThread::deoptimize_marked_methods() {
2910   if (!has_last_Java_frame()) return;
2911   StackFrameStream fst(this, false);
2912   for (; !fst.is_done(); fst.next()) {
2913     if (fst.current()->should_be_deoptimized()) {
2914       Deoptimization::deoptimize(this, *fst.current());
2915     }
2916   }
2917 }
2918 
2919 // If the caller is a NamedThread, then remember, in the current scope,
2920 // the given JavaThread in its _processed_thread field.
2921 class RememberProcessedThread: public StackObj {
2922   NamedThread* _cur_thr;
2923  public:
2924   RememberProcessedThread(JavaThread* jthr) {
2925     Thread* thread = Thread::current();
2926     if (thread->is_Named_thread()) {
2927       _cur_thr = (NamedThread *)thread;
2928       _cur_thr->set_processed_thread(jthr);
2929     } else {
2930       _cur_thr = NULL;
2931     }
2932   }
2933 
2934   ~RememberProcessedThread() {
2935     if (_cur_thr) {
2936       _cur_thr->set_processed_thread(NULL);
2937     }
2938   }
2939 };
2940 
2941 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2942   // Verify that the deferred card marks have been flushed.
2943   assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2944 
2945   // Traverse the GCHandles
2946   Thread::oops_do(f, cf);
2947 
2948   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2949          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2950 
2951   if (has_last_Java_frame()) {
2952     // Record JavaThread to GC thread
2953     RememberProcessedThread rpt(this);
2954 
2955     // traverse the registered growable array
2956     if (_array_for_gc != NULL) {
2957       for (int index = 0; index < _array_for_gc->length(); index++) {
2958         f->do_oop(_array_for_gc->adr_at(index));
2959       }
2960     }
2961 
2962     // Traverse the monitor chunks
2963     for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2964       chunk->oops_do(f);
2965     }
2966 
2967     // Traverse the execution stack
2968     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2969       fst.current()->oops_do(f, cf, fst.register_map());
2970     }
2971   }
2972 
2973   assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2974   // If we have deferred set_locals there might be oops waiting to be
2975   // written
2976   GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2977   if (list != NULL) {
2978     for (int i = 0; i < list->length(); i++) {
2979       list->at(i)->oops_do(f);
2980     }
2981   }
2982 
2983   // Traverse instance variables at the end since the GC may be moving things
2984   // around using this function
2985   f->do_oop((oop*) &_threadObj);
2986   f->do_oop((oop*) &_vm_result);
2987   f->do_oop((oop*) &_exception_oop);
2988   f->do_oop((oop*) &_pending_async_exception);
2989 
2990   if (jvmti_thread_state() != NULL) {
2991     jvmti_thread_state()->oops_do(f, cf);
2992   }
2993 }
2994 
2995 #ifdef ASSERT
2996 void JavaThread::verify_states_for_handshake() {
2997   // This checks that the thread has a correct frame state during a handshake.
2998   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2999          (has_last_Java_frame() && java_call_counter() > 0),
3000          "unexpected frame info: has_last_frame=%d, java_call_counter=%d",
3001          has_last_Java_frame(), java_call_counter());
3002 }
3003 #endif
3004 
3005 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
3006   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
3007          (has_last_Java_frame() && java_call_counter() > 0),
3008          "unexpected frame info: has_last_frame=%d, java_call_counter=%d",
3009          has_last_Java_frame(), java_call_counter());
3010 
3011   if (has_last_Java_frame()) {
3012     // Traverse the execution stack
3013     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3014       fst.current()->nmethods_do(cf);
3015     }
3016   }
3017 
3018   if (jvmti_thread_state() != NULL) {
3019     jvmti_thread_state()->nmethods_do(cf);
3020   }
3021 }
3022 
3023 void JavaThread::metadata_do(MetadataClosure* f) {
3024   if (has_last_Java_frame()) {
3025     // Traverse the execution stack to call f() on the methods in the stack
3026     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3027       fst.current()->metadata_do(f);
3028     }
3029   } else if (is_Compiler_thread()) {
3030     // need to walk ciMetadata in current compile tasks to keep alive.
3031     CompilerThread* ct = (CompilerThread*)this;
3032     if (ct->env() != NULL) {
3033       ct->env()->metadata_do(f);
3034     }
3035     CompileTask* task = ct->task();
3036     if (task != NULL) {
3037       task->metadata_do(f);
3038     }
3039   }
3040 }
3041 
3042 // Printing
3043 const char* _get_thread_state_name(JavaThreadState _thread_state) {
3044   switch (_thread_state) {
3045   case _thread_uninitialized:     return "_thread_uninitialized";
3046   case _thread_new:               return "_thread_new";
3047   case _thread_new_trans:         return "_thread_new_trans";
3048   case _thread_in_native:         return "_thread_in_native";
3049   case _thread_in_native_trans:   return "_thread_in_native_trans";
3050   case _thread_in_vm:             return "_thread_in_vm";
3051   case _thread_in_vm_trans:       return "_thread_in_vm_trans";
3052   case _thread_in_Java:           return "_thread_in_Java";
3053   case _thread_in_Java_trans:     return "_thread_in_Java_trans";
3054   case _thread_blocked:           return "_thread_blocked";
3055   case _thread_blocked_trans:     return "_thread_blocked_trans";
3056   default:                        return "unknown thread state";
3057   }
3058 }
3059 
3060 #ifndef PRODUCT
3061 void JavaThread::print_thread_state_on(outputStream *st) const {
3062   st->print_cr("   JavaThread state: %s", _get_thread_state_name(_thread_state));
3063 };
3064 #endif // PRODUCT
3065 
3066 // Called by Threads::print() for VM_PrintThreads operation
3067 void JavaThread::print_on(outputStream *st, bool print_extended_info) const {
3068   st->print_raw("\"");
3069   st->print_raw(get_thread_name());
3070   st->print_raw("\" ");
3071   oop thread_oop = threadObj();
3072   if (thread_oop != NULL) {
3073     st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
3074     if (java_lang_Thread::is_daemon(thread_oop))  st->print("daemon ");
3075     st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
3076   }
3077   Thread::print_on(st, print_extended_info);
3078   // print guess for valid stack memory region (assume 4K pages); helps lock debugging
3079   st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
3080   if (thread_oop != NULL) {
3081     st->print_cr("   java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
3082   }
3083 #ifndef PRODUCT
3084   _safepoint_state->print_on(st);
3085 #endif // PRODUCT
3086   if (is_Compiler_thread()) {
3087     CompileTask *task = ((CompilerThread*)this)->task();
3088     if (task != NULL) {
3089       st->print("   Compiling: ");
3090       task->print(st, NULL, true, false);
3091     } else {
3092       st->print("   No compile task");
3093     }
3094     st->cr();
3095   }
3096 }
3097 
3098 void JavaThread::print() const { print_on(tty); }
3099 
3100 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
3101   st->print("%s", get_thread_name_string(buf, buflen));
3102 }
3103 
3104 // Called by fatal error handler. The difference between this and
3105 // JavaThread::print() is that we can't grab lock or allocate memory.
3106 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
3107   st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
3108   oop thread_obj = threadObj();
3109   if (thread_obj != NULL) {
3110     if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
3111   }
3112   st->print(" [");
3113   st->print("%s", _get_thread_state_name(_thread_state));
3114   if (osthread()) {
3115     st->print(", id=%d", osthread()->thread_id());
3116   }
3117   st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
3118             p2i(stack_end()), p2i(stack_base()));
3119   st->print("]");
3120 
3121   ThreadsSMRSupport::print_info_on(this, st);
3122   return;
3123 }
3124 
3125 // Verification
3126 
3127 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
3128 
3129 void JavaThread::verify() {
3130   // Verify oops in the thread.
3131   oops_do(&VerifyOopClosure::verify_oop, NULL);
3132 
3133   // Verify the stack frames.
3134   frames_do(frame_verify);
3135 }
3136 
3137 // CR 6300358 (sub-CR 2137150)
3138 // Most callers of this method assume that it can't return NULL but a
3139 // thread may not have a name whilst it is in the process of attaching to
3140 // the VM - see CR 6412693, and there are places where a JavaThread can be
3141 // seen prior to having it's threadObj set (eg JNI attaching threads and
3142 // if vm exit occurs during initialization). These cases can all be accounted
3143 // for such that this method never returns NULL.
3144 const char* JavaThread::get_thread_name() const {
3145 #ifdef ASSERT
3146   // early safepoints can hit while current thread does not yet have TLS
3147   if (!SafepointSynchronize::is_at_safepoint()) {
3148     Thread *cur = Thread::current();
3149     if (!(cur->is_Java_thread() && cur == this)) {
3150       // Current JavaThreads are allowed to get their own name without
3151       // the Threads_lock.
3152       assert_locked_or_safepoint_or_handshake(Threads_lock, this);
3153     }
3154   }
3155 #endif // ASSERT
3156   return get_thread_name_string();
3157 }
3158 
3159 // Returns a non-NULL representation of this thread's name, or a suitable
3160 // descriptive string if there is no set name
3161 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3162   const char* name_str;
3163   oop thread_obj = threadObj();
3164   if (thread_obj != NULL) {
3165     oop name = java_lang_Thread::name(thread_obj);
3166     if (name != NULL) {
3167       if (buf == NULL) {
3168         name_str = java_lang_String::as_utf8_string(name);
3169       } else {
3170         name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3171       }
3172     } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3173       name_str = "<no-name - thread is attaching>";
3174     } else {
3175       name_str = Thread::name();
3176     }
3177   } else {
3178     name_str = Thread::name();
3179   }
3180   assert(name_str != NULL, "unexpected NULL thread name");
3181   return name_str;
3182 }
3183 
3184 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3185 
3186   assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3187   assert(NoPriority <= prio && prio <= MaxPriority, "sanity check");
3188   // Link Java Thread object <-> C++ Thread
3189 
3190   // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3191   // and put it into a new Handle.  The Handle "thread_oop" can then
3192   // be used to pass the C++ thread object to other methods.
3193 
3194   // Set the Java level thread object (jthread) field of the
3195   // new thread (a JavaThread *) to C++ thread object using the
3196   // "thread_oop" handle.
3197 
3198   // Set the thread field (a JavaThread *) of the
3199   // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3200 
3201   Handle thread_oop(Thread::current(),
3202                     JNIHandles::resolve_non_null(jni_thread));
3203   assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3204          "must be initialized");
3205   set_threadObj(thread_oop());
3206   java_lang_Thread::set_thread(thread_oop(), this);
3207 
3208   if (prio == NoPriority) {
3209     prio = java_lang_Thread::priority(thread_oop());
3210     assert(prio != NoPriority, "A valid priority should be present");
3211   }
3212 
3213   // Push the Java priority down to the native thread; needs Threads_lock
3214   Thread::set_priority(this, prio);
3215 
3216   // Add the new thread to the Threads list and set it in motion.
3217   // We must have threads lock in order to call Threads::add.
3218   // It is crucial that we do not block before the thread is
3219   // added to the Threads list for if a GC happens, then the java_thread oop
3220   // will not be visited by GC.
3221   Threads::add(this);
3222 }
3223 
3224 oop JavaThread::current_park_blocker() {
3225   // Support for JSR-166 locks
3226   oop thread_oop = threadObj();
3227   if (thread_oop != NULL) {
3228     return java_lang_Thread::park_blocker(thread_oop);
3229   }
3230   return NULL;
3231 }
3232 
3233 
3234 void JavaThread::print_stack_on(outputStream* st) {
3235   if (!has_last_Java_frame()) return;
3236   ResourceMark rm;
3237   HandleMark   hm;
3238 
3239   RegisterMap reg_map(this);
3240   vframe* start_vf = last_java_vframe(&reg_map);
3241   int count = 0;
3242   for (vframe* f = start_vf; f != NULL; f = f->sender()) {
3243     if (f->is_java_frame()) {
3244       javaVFrame* jvf = javaVFrame::cast(f);
3245       java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3246 
3247       // Print out lock information
3248       if (JavaMonitorsInStackTrace) {
3249         jvf->print_lock_info_on(st, count);
3250       }
3251     } else {
3252       // Ignore non-Java frames
3253     }
3254 
3255     // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
3256     count++;
3257     if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
3258   }
3259 }
3260 
3261 
3262 // JVMTI PopFrame support
3263 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3264   assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3265   if (in_bytes(size_in_bytes) != 0) {
3266     _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3267     _popframe_preserved_args_size = in_bytes(size_in_bytes);
3268     Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3269   }
3270 }
3271 
3272 void* JavaThread::popframe_preserved_args() {
3273   return _popframe_preserved_args;
3274 }
3275 
3276 ByteSize JavaThread::popframe_preserved_args_size() {
3277   return in_ByteSize(_popframe_preserved_args_size);
3278 }
3279 
3280 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3281   int sz = in_bytes(popframe_preserved_args_size());
3282   assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3283   return in_WordSize(sz / wordSize);
3284 }
3285 
3286 void JavaThread::popframe_free_preserved_args() {
3287   assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3288   FREE_C_HEAP_ARRAY(char, (char*)_popframe_preserved_args);
3289   _popframe_preserved_args = NULL;
3290   _popframe_preserved_args_size = 0;
3291 }
3292 
3293 #ifndef PRODUCT
3294 
3295 void JavaThread::trace_frames() {
3296   tty->print_cr("[Describe stack]");
3297   int frame_no = 1;
3298   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3299     tty->print("  %d. ", frame_no++);
3300     fst.current()->print_value_on(tty, this);
3301     tty->cr();
3302   }
3303 }
3304 
3305 class PrintAndVerifyOopClosure: public OopClosure {
3306  protected:
3307   template <class T> inline void do_oop_work(T* p) {
3308     oop obj = RawAccess<>::oop_load(p);
3309     if (obj == NULL) return;
3310     tty->print(INTPTR_FORMAT ": ", p2i(p));
3311     if (oopDesc::is_oop_or_null(obj)) {
3312       if (obj->is_objArray()) {
3313         tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3314       } else {
3315         obj->print();
3316       }
3317     } else {
3318       tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3319     }
3320     tty->cr();
3321   }
3322  public:
3323   virtual void do_oop(oop* p) { do_oop_work(p); }
3324   virtual void do_oop(narrowOop* p)  { do_oop_work(p); }
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 // java.lang.Thread.sleep support
3396 // Returns true if sleep time elapsed as expected, and false
3397 // if the thread was interrupted.
3398 bool JavaThread::sleep(jlong millis) {
3399   assert(this == Thread::current(),  "thread consistency check");
3400 
3401   ParkEvent * const slp = this->_SleepEvent;
3402   // Because there can be races with thread interruption sending an unpark()
3403   // to the event, we explicitly reset it here to avoid an immediate return.
3404   // The actual interrupt state will be checked before we park().
3405   slp->reset();
3406   // Thread interruption establishes a happens-before ordering in the
3407   // Java Memory Model, so we need to ensure we synchronize with the
3408   // interrupt state.
3409   OrderAccess::fence();
3410 
3411   jlong prevtime = os::javaTimeNanos();
3412 
3413   for (;;) {
3414     // interruption has precedence over timing out
3415     if (this->is_interrupted(true)) {
3416       return false;
3417     }
3418 
3419     if (millis <= 0) {
3420       return true;
3421     }
3422 
3423     {
3424       ThreadBlockInVM tbivm(this);
3425       OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
3426 
3427       this->set_suspend_equivalent();
3428       // cleared by handle_special_suspend_equivalent_condition() or
3429       // java_suspend_self() via check_and_wait_while_suspended()
3430 
3431       slp->park(millis);
3432 
3433       // were we externally suspended while we were waiting?
3434       this->check_and_wait_while_suspended();
3435     }
3436 
3437     // Update elapsed time tracking
3438     jlong newtime = os::javaTimeNanos();
3439     if (newtime - prevtime < 0) {
3440       // time moving backwards, should only happen if no monotonic clock
3441       // not a guarantee() because JVM should not abort on kernel/glibc bugs
3442       assert(!os::supports_monotonic_clock(),
3443              "unexpected time moving backwards detected in JavaThread::sleep()");
3444     } else {
3445       millis -= (newtime - prevtime) / NANOSECS_PER_MILLISEC;
3446     }
3447     prevtime = newtime;
3448   }
3449 }
3450 
3451 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3452   assert(thread->is_Compiler_thread(), "must be compiler thread");
3453   CompileBroker::compiler_thread_loop();
3454 }
3455 
3456 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3457   NMethodSweeper::sweeper_loop();
3458 }
3459 
3460 // Create a CompilerThread
3461 CompilerThread::CompilerThread(CompileQueue* queue,
3462                                CompilerCounters* counters)
3463                                : JavaThread(&compiler_thread_entry) {
3464   _env   = NULL;
3465   _log   = NULL;
3466   _task  = NULL;
3467   _queue = queue;
3468   _counters = counters;
3469   _buffer_blob = NULL;
3470   _compiler = NULL;
3471 
3472   // Compiler uses resource area for compilation, let's bias it to mtCompiler
3473   resource_area()->bias_to(mtCompiler);
3474 
3475 #ifndef PRODUCT
3476   _ideal_graph_printer = NULL;
3477 #endif
3478 }
3479 
3480 CompilerThread::~CompilerThread() {
3481   // Delete objects which were allocated on heap.
3482   delete _counters;
3483 }
3484 
3485 bool CompilerThread::can_call_java() const {
3486   return _compiler != NULL && _compiler->is_jvmci();
3487 }
3488 
3489 // Create sweeper thread
3490 CodeCacheSweeperThread::CodeCacheSweeperThread()
3491 : JavaThread(&sweeper_thread_entry) {
3492   _scanned_compiled_method = NULL;
3493 }
3494 
3495 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3496   JavaThread::oops_do(f, cf);
3497   if (_scanned_compiled_method != NULL && cf != NULL) {
3498     // Safepoints can occur when the sweeper is scanning an nmethod so
3499     // process it here to make sure it isn't unloaded in the middle of
3500     // a scan.
3501     cf->do_code_blob(_scanned_compiled_method);
3502   }
3503 }
3504 
3505 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3506   JavaThread::nmethods_do(cf);
3507   if (_scanned_compiled_method != NULL && cf != NULL) {
3508     // Safepoints can occur when the sweeper is scanning an nmethod so
3509     // process it here to make sure it isn't unloaded in the middle of
3510     // a scan.
3511     cf->do_code_blob(_scanned_compiled_method);
3512   }
3513 }
3514 
3515 
3516 // ======= Threads ========
3517 
3518 // The Threads class links together all active threads, and provides
3519 // operations over all threads. It is protected by the Threads_lock,
3520 // which is also used in other global contexts like safepointing.
3521 // ThreadsListHandles are used to safely perform operations on one
3522 // or more threads without the risk of the thread exiting during the
3523 // operation.
3524 //
3525 // Note: The Threads_lock is currently more widely used than we
3526 // would like. We are actively migrating Threads_lock uses to other
3527 // mechanisms in order to reduce Threads_lock contention.
3528 
3529 int         Threads::_number_of_threads = 0;
3530 int         Threads::_number_of_non_daemon_threads = 0;
3531 int         Threads::_return_code = 0;
3532 uintx       Threads::_thread_claim_token = 1; // Never zero.
3533 size_t      JavaThread::_stack_size_at_create = 0;
3534 
3535 #ifdef ASSERT
3536 bool        Threads::_vm_complete = false;
3537 #endif
3538 
3539 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
3540   Prefetch::read((void*)addr, prefetch_interval);
3541   return *addr;
3542 }
3543 
3544 // Possibly the ugliest for loop the world has seen. C++ does not allow
3545 // multiple types in the declaration section of the for loop. In this case
3546 // we are only dealing with pointers and hence can cast them. It looks ugly
3547 // but macros are ugly and therefore it's fine to make things absurdly ugly.
3548 #define DO_JAVA_THREADS(LIST, X)                                                                                          \
3549     for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes,                           \
3550              *MACRO_list = (JavaThread*)(LIST),                                                                           \
3551              **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(),  \
3552              **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(),                                     \
3553              *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval);                 \
3554          MACRO_current_p != MACRO_end;                                                                                    \
3555          MACRO_current_p++,                                                                                               \
3556              X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval))
3557 
3558 // All JavaThreads
3559 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X)
3560 
3561 // All NonJavaThreads (i.e., every non-JavaThread in the system).
3562 void Threads::non_java_threads_do(ThreadClosure* tc) {
3563   NoSafepointVerifier nsv;
3564   for (NonJavaThread::Iterator njti; !njti.end(); njti.step()) {
3565     tc->do_thread(njti.current());
3566   }
3567 }
3568 
3569 // All JavaThreads
3570 void Threads::java_threads_do(ThreadClosure* tc) {
3571   assert_locked_or_safepoint(Threads_lock);
3572   // ALL_JAVA_THREADS iterates through all JavaThreads.
3573   ALL_JAVA_THREADS(p) {
3574     tc->do_thread(p);
3575   }
3576 }
3577 
3578 void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) {
3579   assert_locked_or_safepoint(Threads_lock);
3580   java_threads_do(tc);
3581   tc->do_thread(VMThread::vm_thread());
3582 }
3583 
3584 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system).
3585 void Threads::threads_do(ThreadClosure* tc) {
3586   assert_locked_or_safepoint(Threads_lock);
3587   java_threads_do(tc);
3588   non_java_threads_do(tc);
3589 }
3590 
3591 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
3592   uintx claim_token = Threads::thread_claim_token();
3593   ALL_JAVA_THREADS(p) {
3594     if (p->claim_threads_do(is_par, claim_token)) {
3595       tc->do_thread(p);
3596     }
3597   }
3598   VMThread* vmt = VMThread::vm_thread();
3599   if (vmt->claim_threads_do(is_par, claim_token)) {
3600     tc->do_thread(vmt);
3601   }
3602 }
3603 
3604 // The system initialization in the library has three phases.
3605 //
3606 // Phase 1: java.lang.System class initialization
3607 //     java.lang.System is a primordial class loaded and initialized
3608 //     by the VM early during startup.  java.lang.System.<clinit>
3609 //     only does registerNatives and keeps the rest of the class
3610 //     initialization work later until thread initialization completes.
3611 //
3612 //     System.initPhase1 initializes the system properties, the static
3613 //     fields in, out, and err. Set up java signal handlers, OS-specific
3614 //     system settings, and thread group of the main thread.
3615 static void call_initPhase1(TRAPS) {
3616   Klass* klass = SystemDictionary::System_klass();
3617   JavaValue result(T_VOID);
3618   JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3619                                          vmSymbols::void_method_signature(), CHECK);
3620 }
3621 
3622 // Phase 2. Module system initialization
3623 //     This will initialize the module system.  Only java.base classes
3624 //     can be loaded until phase 2 completes.
3625 //
3626 //     Call System.initPhase2 after the compiler initialization and jsr292
3627 //     classes get initialized because module initialization runs a lot of java
3628 //     code, that for performance reasons, should be compiled.  Also, this will
3629 //     enable the startup code to use lambda and other language features in this
3630 //     phase and onward.
3631 //
3632 //     After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3633 static void call_initPhase2(TRAPS) {
3634   TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3635 
3636   Klass* klass = SystemDictionary::System_klass();
3637 
3638   JavaValue result(T_INT);
3639   JavaCallArguments args;
3640   args.push_int(DisplayVMOutputToStderr);
3641   args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3642   JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3643                                          vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3644   if (result.get_jint() != JNI_OK) {
3645     vm_exit_during_initialization(); // no message or exception
3646   }
3647 
3648   universe_post_module_init();
3649 }
3650 
3651 // Phase 3. final setup - set security manager, system class loader and TCCL
3652 //
3653 //     This will instantiate and set the security manager, set the system class
3654 //     loader as well as the thread context class loader.  The security manager
3655 //     and system class loader may be a custom class loaded from -Xbootclasspath/a,
3656 //     other modules or the application's classpath.
3657 static void call_initPhase3(TRAPS) {
3658   Klass* klass = SystemDictionary::System_klass();
3659   JavaValue result(T_VOID);
3660   JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3661                                          vmSymbols::void_method_signature(), CHECK);
3662 }
3663 
3664 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3665   TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3666 
3667   if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3668     create_vm_init_libraries();
3669   }
3670 
3671   initialize_class(vmSymbols::java_lang_String(), CHECK);
3672 
3673   // Inject CompactStrings value after the static initializers for String ran.
3674   java_lang_String::set_compact_strings(CompactStrings);
3675 
3676   // Initialize java_lang.System (needed before creating the thread)
3677   initialize_class(vmSymbols::java_lang_System(), CHECK);
3678   // The VM creates & returns objects of this class. Make sure it's initialized.
3679   initialize_class(vmSymbols::java_lang_Class(), CHECK);
3680   initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3681   Handle thread_group = create_initial_thread_group(CHECK);
3682   Universe::set_main_thread_group(thread_group());
3683   initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3684   oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3685   main_thread->set_threadObj(thread_object);
3686 
3687   // Set thread status to running since main thread has
3688   // been started and running.
3689   java_lang_Thread::set_thread_status(thread_object,
3690                                       java_lang_Thread::RUNNABLE);
3691 
3692   // The VM creates objects of this class.
3693   initialize_class(vmSymbols::java_lang_Module(), CHECK);
3694 
3695 #ifdef ASSERT
3696   InstanceKlass *k = SystemDictionary::UnsafeConstants_klass();
3697   assert(k->is_not_initialized(), "UnsafeConstants should not already be initialized");
3698 #endif
3699 
3700   // initialize the hardware-specific constants needed by Unsafe
3701   initialize_class(vmSymbols::jdk_internal_misc_UnsafeConstants(), CHECK);
3702   jdk_internal_misc_UnsafeConstants::set_unsafe_constants();
3703 
3704   // The VM preresolves methods to these classes. Make sure that they get initialized
3705   initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3706   initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3707 
3708   // Phase 1 of the system initialization in the library, java.lang.System class initialization
3709   call_initPhase1(CHECK);
3710 
3711   // get the Java runtime name, version, and vendor info after java.lang.System is initialized
3712   JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3713   JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3714   JDK_Version::set_runtime_vendor_version(get_java_runtime_vendor_version(THREAD));
3715   JDK_Version::set_runtime_vendor_vm_bug_url(get_java_runtime_vendor_vm_bug_url(THREAD));
3716 
3717   // an instance of OutOfMemory exception has been allocated earlier
3718   initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3719   initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3720   initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3721   initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3722   initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3723   initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3724   initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3725   initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3726 
3727   // Eager box cache initialization only if AOT is on and any library is loaded.
3728   AOTLoader::initialize_box_caches(CHECK);
3729 }
3730 
3731 void Threads::initialize_jsr292_core_classes(TRAPS) {
3732   TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3733 
3734   initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3735   initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3736   initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3737   initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3738 }
3739 
3740 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3741   extern void JDK_Version_init();
3742 
3743   // Preinitialize version info.
3744   VM_Version::early_initialize();
3745 
3746   // Check version
3747   if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3748 
3749   // Initialize library-based TLS
3750   ThreadLocalStorage::init();
3751 
3752   // Initialize the output stream module
3753   ostream_init();
3754 
3755   // Process java launcher properties.
3756   Arguments::process_sun_java_launcher_properties(args);
3757 
3758   // Initialize the os module
3759   os::init();
3760 
3761   // Record VM creation timing statistics
3762   TraceVmCreationTime create_vm_timer;
3763   create_vm_timer.start();
3764 
3765   // Initialize system properties.
3766   Arguments::init_system_properties();
3767 
3768   // So that JDK version can be used as a discriminator when parsing arguments
3769   JDK_Version_init();
3770 
3771   // Update/Initialize System properties after JDK version number is known
3772   Arguments::init_version_specific_system_properties();
3773 
3774   // Make sure to initialize log configuration *before* parsing arguments
3775   LogConfiguration::initialize(create_vm_timer.begin_time());
3776 
3777   // Parse arguments
3778   // Note: this internally calls os::init_container_support()
3779   jint parse_result = Arguments::parse(args);
3780   if (parse_result != JNI_OK) return parse_result;
3781 
3782   os::init_before_ergo();
3783 
3784   jint ergo_result = Arguments::apply_ergo();
3785   if (ergo_result != JNI_OK) return ergo_result;
3786 
3787   // Final check of all ranges after ergonomics which may change values.
3788   if (!JVMFlagRangeList::check_ranges()) {
3789     return JNI_EINVAL;
3790   }
3791 
3792   // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3793   bool constraint_result = JVMFlagConstraintList::check_constraints(JVMFlagConstraint::AfterErgo);
3794   if (!constraint_result) {
3795     return JNI_EINVAL;
3796   }
3797 
3798   if (PauseAtStartup) {
3799     os::pause();
3800   }
3801 
3802   HOTSPOT_VM_INIT_BEGIN();
3803 
3804   // Timing (must come after argument parsing)
3805   TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3806 
3807   // Initialize the os module after parsing the args
3808   jint os_init_2_result = os::init_2();
3809   if (os_init_2_result != JNI_OK) return os_init_2_result;
3810 
3811 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT
3812   // Initialize assert poison page mechanism.
3813   if (ShowRegistersOnAssert) {
3814     initialize_assert_poison();
3815   }
3816 #endif // CAN_SHOW_REGISTERS_ON_ASSERT
3817 
3818   SafepointMechanism::initialize();
3819 
3820   jint adjust_after_os_result = Arguments::adjust_after_os();
3821   if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3822 
3823   // Initialize output stream logging
3824   ostream_init_log();
3825 
3826   // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3827   // Must be before create_vm_init_agents()
3828   if (Arguments::init_libraries_at_startup()) {
3829     convert_vm_init_libraries_to_agents();
3830   }
3831 
3832   // Launch -agentlib/-agentpath and converted -Xrun agents
3833   if (Arguments::init_agents_at_startup()) {
3834     create_vm_init_agents();
3835   }
3836 
3837   // Initialize Threads state
3838   _number_of_threads = 0;
3839   _number_of_non_daemon_threads = 0;
3840 
3841   // Initialize global data structures and create system classes in heap
3842   vm_init_globals();
3843 
3844 #if INCLUDE_JVMCI
3845   if (JVMCICounterSize > 0) {
3846     JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtJVMCI);
3847     memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3848   } else {
3849     JavaThread::_jvmci_old_thread_counters = NULL;
3850   }
3851 #endif // INCLUDE_JVMCI
3852 
3853   // Attach the main thread to this os thread
3854   JavaThread* main_thread = new JavaThread();
3855   main_thread->set_thread_state(_thread_in_vm);
3856   main_thread->initialize_thread_current();
3857   // must do this before set_active_handles
3858   main_thread->record_stack_base_and_size();
3859   main_thread->register_thread_stack_with_NMT();
3860   main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3861 
3862   if (!main_thread->set_as_starting_thread()) {
3863     vm_shutdown_during_initialization(
3864                                       "Failed necessary internal allocation. Out of swap space");
3865     main_thread->smr_delete();
3866     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3867     return JNI_ENOMEM;
3868   }
3869 
3870   // Enable guard page *after* os::create_main_thread(), otherwise it would
3871   // crash Linux VM, see notes in os_linux.cpp.
3872   main_thread->create_stack_guard_pages();
3873 
3874   // Initialize Java-Level synchronization subsystem
3875   ObjectMonitor::Initialize();
3876 
3877   // Initialize global modules
3878   jint status = init_globals();
3879   if (status != JNI_OK) {
3880     main_thread->smr_delete();
3881     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3882     return status;
3883   }
3884 
3885   JFR_ONLY(Jfr::on_create_vm_1();)
3886 
3887   // Should be done after the heap is fully created
3888   main_thread->cache_global_variables();
3889 
3890   HandleMark hm;
3891 
3892   { MutexLocker mu(Threads_lock);
3893     Threads::add(main_thread);
3894   }
3895 
3896   // Any JVMTI raw monitors entered in onload will transition into
3897   // real raw monitor. VM is setup enough here for raw monitor enter.
3898   JvmtiExport::transition_pending_onload_raw_monitors();
3899 
3900   // Create the VMThread
3901   { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3902 
3903     VMThread::create();
3904     Thread* vmthread = VMThread::vm_thread();
3905 
3906     if (!os::create_thread(vmthread, os::vm_thread)) {
3907       vm_exit_during_initialization("Cannot create VM thread. "
3908                                     "Out of system resources.");
3909     }
3910 
3911     // Wait for the VM thread to become ready, and VMThread::run to initialize
3912     // Monitors can have spurious returns, must always check another state flag
3913     {
3914       MonitorLocker ml(Notify_lock);
3915       os::start_thread(vmthread);
3916       while (vmthread->active_handles() == NULL) {
3917         ml.wait();
3918       }
3919     }
3920   }
3921 
3922   assert(Universe::is_fully_initialized(), "not initialized");
3923   if (VerifyDuringStartup) {
3924     // Make sure we're starting with a clean slate.
3925     VM_Verify verify_op;
3926     VMThread::execute(&verify_op);
3927   }
3928 
3929   // We need this to update the java.vm.info property in case any flags used
3930   // to initially define it have been changed. This is needed for both CDS and
3931   // AOT, since UseSharedSpaces and UseAOT may be changed after java.vm.info
3932   // is initially computed. See Abstract_VM_Version::vm_info_string().
3933   // This update must happen before we initialize the java classes, but
3934   // after any initialization logic that might modify the flags.
3935   Arguments::update_vm_info_property(VM_Version::vm_info_string());
3936 
3937   Thread* THREAD = Thread::current();
3938 
3939   // Always call even when there are not JVMTI environments yet, since environments
3940   // may be attached late and JVMTI must track phases of VM execution
3941   JvmtiExport::enter_early_start_phase();
3942 
3943   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3944   JvmtiExport::post_early_vm_start();
3945 
3946   initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3947 
3948   quicken_jni_functions();
3949 
3950   // No more stub generation allowed after that point.
3951   StubCodeDesc::freeze();
3952 
3953   // Set flag that basic initialization has completed. Used by exceptions and various
3954   // debug stuff, that does not work until all basic classes have been initialized.
3955   set_init_completed();
3956 
3957   LogConfiguration::post_initialize();
3958   Metaspace::post_initialize();
3959 
3960   HOTSPOT_VM_INIT_END();
3961 
3962   // record VM initialization completion time
3963 #if INCLUDE_MANAGEMENT
3964   Management::record_vm_init_completed();
3965 #endif // INCLUDE_MANAGEMENT
3966 
3967   // Signal Dispatcher needs to be started before VMInit event is posted
3968   os::initialize_jdk_signal_support(CHECK_JNI_ERR);
3969 
3970   // Start Attach Listener if +StartAttachListener or it can't be started lazily
3971   if (!DisableAttachMechanism) {
3972     AttachListener::vm_start();
3973     if (StartAttachListener || AttachListener::init_at_startup()) {
3974       AttachListener::init();
3975     }
3976   }
3977 
3978   // Launch -Xrun agents
3979   // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3980   // back-end can launch with -Xdebug -Xrunjdwp.
3981   if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3982     create_vm_init_libraries();
3983   }
3984 
3985   if (CleanChunkPoolAsync) {
3986     Chunk::start_chunk_pool_cleaner_task();
3987   }
3988 
3989   // Start the service thread
3990   // The service thread enqueues JVMTI deferred events and does various hashtable
3991   // and other cleanups.  Needs to start before the compilers start posting events.
3992   ServiceThread::initialize();
3993 
3994   // initialize compiler(s)
3995 #if defined(COMPILER1) || COMPILER2_OR_JVMCI
3996 #if INCLUDE_JVMCI
3997   bool force_JVMCI_intialization = false;
3998   if (EnableJVMCI) {
3999     // Initialize JVMCI eagerly when it is explicitly requested.
4000     // Or when JVMCILibDumpJNIConfig or JVMCIPrintProperties is enabled.
4001     force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties || JVMCILibDumpJNIConfig;
4002 
4003     if (!force_JVMCI_intialization) {
4004       // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
4005       // compilations via JVMCI will not actually block until JVMCI is initialized.
4006       force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
4007     }
4008   }
4009 #endif
4010   CompileBroker::compilation_init_phase1(CHECK_JNI_ERR);
4011   // Postpone completion of compiler initialization to after JVMCI
4012   // is initialized to avoid timeouts of blocking compilations.
4013   if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) {
4014     CompileBroker::compilation_init_phase2();
4015   }
4016 #endif
4017 
4018   // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
4019   // It is done after compilers are initialized, because otherwise compilations of
4020   // signature polymorphic MH intrinsics can be missed
4021   // (see SystemDictionary::find_method_handle_intrinsic).
4022   initialize_jsr292_core_classes(CHECK_JNI_ERR);
4023 
4024   // This will initialize the module system.  Only java.base classes can be
4025   // loaded until phase 2 completes
4026   call_initPhase2(CHECK_JNI_ERR);
4027 
4028   JFR_ONLY(Jfr::on_create_vm_2();)
4029 
4030   // Always call even when there are not JVMTI environments yet, since environments
4031   // may be attached late and JVMTI must track phases of VM execution
4032   JvmtiExport::enter_start_phase();
4033 
4034   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
4035   JvmtiExport::post_vm_start();
4036 
4037   // Final system initialization including security manager and system class loader
4038   call_initPhase3(CHECK_JNI_ERR);
4039 
4040   // cache the system and platform class loaders
4041   SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
4042 
4043 #if INCLUDE_CDS
4044   // capture the module path info from the ModuleEntryTable
4045   ClassLoader::initialize_module_path(THREAD);
4046 #endif
4047 
4048 #if INCLUDE_JVMCI
4049   if (force_JVMCI_intialization) {
4050     JVMCI::initialize_compiler(CHECK_JNI_ERR);
4051     CompileBroker::compilation_init_phase2();
4052   }
4053 #endif
4054 
4055   // Always call even when there are not JVMTI environments yet, since environments
4056   // may be attached late and JVMTI must track phases of VM execution
4057   JvmtiExport::enter_live_phase();
4058 
4059   // Make perfmemory accessible
4060   PerfMemory::set_accessible(true);
4061 
4062   // Notify JVMTI agents that VM initialization is complete - nop if no agents.
4063   JvmtiExport::post_vm_initialized();
4064 
4065   JFR_ONLY(Jfr::on_create_vm_3();)
4066 
4067 #if INCLUDE_MANAGEMENT
4068   Management::initialize(THREAD);
4069 
4070   if (HAS_PENDING_EXCEPTION) {
4071     // management agent fails to start possibly due to
4072     // configuration problem and is responsible for printing
4073     // stack trace if appropriate. Simply exit VM.
4074     vm_exit(1);
4075   }
4076 #endif // INCLUDE_MANAGEMENT
4077 
4078   if (MemProfiling)                   MemProfiler::engage();
4079   StatSampler::engage();
4080   if (CheckJNICalls)                  JniPeriodicChecker::engage();
4081 
4082   BiasedLocking::init();
4083 
4084 #if INCLUDE_RTM_OPT
4085   RTMLockingCounters::init();
4086 #endif
4087 
4088   call_postVMInitHook(THREAD);
4089   // The Java side of PostVMInitHook.run must deal with all
4090   // exceptions and provide means of diagnosis.
4091   if (HAS_PENDING_EXCEPTION) {
4092     CLEAR_PENDING_EXCEPTION;
4093   }
4094 
4095   {
4096     MutexLocker ml(PeriodicTask_lock);
4097     // Make sure the WatcherThread can be started by WatcherThread::start()
4098     // or by dynamic enrollment.
4099     WatcherThread::make_startable();
4100     // Start up the WatcherThread if there are any periodic tasks
4101     // NOTE:  All PeriodicTasks should be registered by now. If they
4102     //   aren't, late joiners might appear to start slowly (we might
4103     //   take a while to process their first tick).
4104     if (PeriodicTask::num_tasks() > 0) {
4105       WatcherThread::start();
4106     }
4107   }
4108 
4109   create_vm_timer.end();
4110 #ifdef ASSERT
4111   _vm_complete = true;
4112 #endif
4113 
4114   if (DumpSharedSpaces) {
4115     MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
4116     ShouldNotReachHere();
4117   }
4118 
4119   return JNI_OK;
4120 }
4121 
4122 // type for the Agent_OnLoad and JVM_OnLoad entry points
4123 extern "C" {
4124   typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
4125 }
4126 // Find a command line agent library and return its entry point for
4127 //         -agentlib:  -agentpath:   -Xrun
4128 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
4129 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
4130                                     const char *on_load_symbols[],
4131                                     size_t num_symbol_entries) {
4132   OnLoadEntry_t on_load_entry = NULL;
4133   void *library = NULL;
4134 
4135   if (!agent->valid()) {
4136     char buffer[JVM_MAXPATHLEN];
4137     char ebuf[1024] = "";
4138     const char *name = agent->name();
4139     const char *msg = "Could not find agent library ";
4140 
4141     // First check to see if agent is statically linked into executable
4142     if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
4143       library = agent->os_lib();
4144     } else if (agent->is_absolute_path()) {
4145       library = os::dll_load(name, ebuf, sizeof ebuf);
4146       if (library == NULL) {
4147         const char *sub_msg = " in absolute path, with error: ";
4148         size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
4149         char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4150         jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4151         // If we can't find the agent, exit.
4152         vm_exit_during_initialization(buf, NULL);
4153         FREE_C_HEAP_ARRAY(char, buf);
4154       }
4155     } else {
4156       // Try to load the agent from the standard dll directory
4157       if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
4158                              name)) {
4159         library = os::dll_load(buffer, ebuf, sizeof ebuf);
4160       }
4161       if (library == NULL) { // Try the library path directory.
4162         if (os::dll_build_name(buffer, sizeof(buffer), name)) {
4163           library = os::dll_load(buffer, ebuf, sizeof ebuf);
4164         }
4165         if (library == NULL) {
4166           const char *sub_msg = " on the library path, with error: ";
4167           const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image.";
4168 
4169           size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) +
4170                        strlen(ebuf) + strlen(sub_msg2) + 1;
4171           char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4172           if (!agent->is_instrument_lib()) {
4173             jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4174           } else {
4175             jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2);
4176           }
4177           // If we can't find the agent, exit.
4178           vm_exit_during_initialization(buf, NULL);
4179           FREE_C_HEAP_ARRAY(char, buf);
4180         }
4181       }
4182     }
4183     agent->set_os_lib(library);
4184     agent->set_valid();
4185   }
4186 
4187   // Find the OnLoad function.
4188   on_load_entry =
4189     CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
4190                                                           false,
4191                                                           on_load_symbols,
4192                                                           num_symbol_entries));
4193   return on_load_entry;
4194 }
4195 
4196 // Find the JVM_OnLoad entry point
4197 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
4198   const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
4199   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4200 }
4201 
4202 // Find the Agent_OnLoad entry point
4203 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
4204   const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
4205   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4206 }
4207 
4208 // For backwards compatibility with -Xrun
4209 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
4210 // treated like -agentpath:
4211 // Must be called before agent libraries are created
4212 void Threads::convert_vm_init_libraries_to_agents() {
4213   AgentLibrary* agent;
4214   AgentLibrary* next;
4215 
4216   for (agent = Arguments::libraries(); agent != NULL; agent = next) {
4217     next = agent->next();  // cache the next agent now as this agent may get moved off this list
4218     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4219 
4220     // If there is an JVM_OnLoad function it will get called later,
4221     // otherwise see if there is an Agent_OnLoad
4222     if (on_load_entry == NULL) {
4223       on_load_entry = lookup_agent_on_load(agent);
4224       if (on_load_entry != NULL) {
4225         // switch it to the agent list -- so that Agent_OnLoad will be called,
4226         // JVM_OnLoad won't be attempted and Agent_OnUnload will
4227         Arguments::convert_library_to_agent(agent);
4228       } else {
4229         vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
4230       }
4231     }
4232   }
4233 }
4234 
4235 // Create agents for -agentlib:  -agentpath:  and converted -Xrun
4236 // Invokes Agent_OnLoad
4237 // Called very early -- before JavaThreads exist
4238 void Threads::create_vm_init_agents() {
4239   extern struct JavaVM_ main_vm;
4240   AgentLibrary* agent;
4241 
4242   JvmtiExport::enter_onload_phase();
4243 
4244   for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4245     // CDS dumping does not support native JVMTI agent.
4246     // CDS dumping supports Java agent if the AllowArchivingWithJavaAgent diagnostic option is specified.
4247     if (Arguments::is_dumping_archive()) {
4248       if(!agent->is_instrument_lib()) {
4249         vm_exit_during_cds_dumping("CDS dumping does not support native JVMTI agent, name", agent->name());
4250       } else if (!AllowArchivingWithJavaAgent) {
4251         vm_exit_during_cds_dumping(
4252           "Must enable AllowArchivingWithJavaAgent in order to run Java agent during CDS dumping");
4253       }
4254     }
4255 
4256     OnLoadEntry_t  on_load_entry = lookup_agent_on_load(agent);
4257 
4258     if (on_load_entry != NULL) {
4259       // Invoke the Agent_OnLoad function
4260       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4261       if (err != JNI_OK) {
4262         vm_exit_during_initialization("agent library failed to init", agent->name());
4263       }
4264     } else {
4265       vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4266     }
4267   }
4268 
4269   JvmtiExport::enter_primordial_phase();
4270 }
4271 
4272 extern "C" {
4273   typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4274 }
4275 
4276 void Threads::shutdown_vm_agents() {
4277   // Send any Agent_OnUnload notifications
4278   const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4279   size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4280   extern struct JavaVM_ main_vm;
4281   for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4282 
4283     // Find the Agent_OnUnload function.
4284     Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4285                                                    os::find_agent_function(agent,
4286                                                    false,
4287                                                    on_unload_symbols,
4288                                                    num_symbol_entries));
4289 
4290     // Invoke the Agent_OnUnload function
4291     if (unload_entry != NULL) {
4292       JavaThread* thread = JavaThread::current();
4293       ThreadToNativeFromVM ttn(thread);
4294       HandleMark hm(thread);
4295       (*unload_entry)(&main_vm);
4296     }
4297   }
4298 }
4299 
4300 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4301 // Invokes JVM_OnLoad
4302 void Threads::create_vm_init_libraries() {
4303   extern struct JavaVM_ main_vm;
4304   AgentLibrary* agent;
4305 
4306   for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4307     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4308 
4309     if (on_load_entry != NULL) {
4310       // Invoke the JVM_OnLoad function
4311       JavaThread* thread = JavaThread::current();
4312       ThreadToNativeFromVM ttn(thread);
4313       HandleMark hm(thread);
4314       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4315       if (err != JNI_OK) {
4316         vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4317       }
4318     } else {
4319       vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4320     }
4321   }
4322 }
4323 
4324 
4325 // Last thread running calls java.lang.Shutdown.shutdown()
4326 void JavaThread::invoke_shutdown_hooks() {
4327   HandleMark hm(this);
4328 
4329   // Link all classes for dynamic CDS dumping before vm exit.
4330   // Same operation is being done in JVM_BeforeHalt for handling the
4331   // case where the application calls System.exit().
4332   if (DynamicDumpSharedSpaces) {
4333     MetaspaceShared::link_and_cleanup_shared_classes(this);
4334   }
4335 
4336   // We could get here with a pending exception, if so clear it now.
4337   if (this->has_pending_exception()) {
4338     this->clear_pending_exception();
4339   }
4340 
4341   EXCEPTION_MARK;
4342   Klass* shutdown_klass =
4343     SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4344                                       THREAD);
4345   if (shutdown_klass != NULL) {
4346     // SystemDictionary::resolve_or_null will return null if there was
4347     // an exception.  If we cannot load the Shutdown class, just don't
4348     // call Shutdown.shutdown() at all.  This will mean the shutdown hooks
4349     // won't be run.  Note that if a shutdown hook was registered,
4350     // the Shutdown class would have already been loaded
4351     // (Runtime.addShutdownHook will load it).
4352     JavaValue result(T_VOID);
4353     JavaCalls::call_static(&result,
4354                            shutdown_klass,
4355                            vmSymbols::shutdown_name(),
4356                            vmSymbols::void_method_signature(),
4357                            THREAD);
4358   }
4359   CLEAR_PENDING_EXCEPTION;
4360 }
4361 
4362 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4363 // the program falls off the end of main(). Another VM exit path is through
4364 // vm_exit() when the program calls System.exit() to return a value or when
4365 // there is a serious error in VM. The two shutdown paths are not exactly
4366 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4367 // and VM_Exit op at VM level.
4368 //
4369 // Shutdown sequence:
4370 //   + Shutdown native memory tracking if it is on
4371 //   + Wait until we are the last non-daemon thread to execute
4372 //     <-- every thing is still working at this moment -->
4373 //   + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4374 //        shutdown hooks
4375 //   + Call before_exit(), prepare for VM exit
4376 //      > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4377 //        currently the only user of this mechanism is File.deleteOnExit())
4378 //      > stop StatSampler, watcher thread,
4379 //        post thread end and vm death events to JVMTI,
4380 //        stop signal thread
4381 //   + Call JavaThread::exit(), it will:
4382 //      > release JNI handle blocks, remove stack guard pages
4383 //      > remove this thread from Threads list
4384 //     <-- no more Java code from this thread after this point -->
4385 //   + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4386 //     the compiler threads at safepoint
4387 //     <-- do not use anything that could get blocked by Safepoint -->
4388 //   + Disable tracing at JNI/JVM barriers
4389 //   + Set _vm_exited flag for threads that are still running native code
4390 //   + Call exit_globals()
4391 //      > deletes tty
4392 //      > deletes PerfMemory resources
4393 //   + Delete this thread
4394 //   + Return to caller
4395 
4396 bool Threads::destroy_vm() {
4397   JavaThread* thread = JavaThread::current();
4398 
4399 #ifdef ASSERT
4400   _vm_complete = false;
4401 #endif
4402   // Wait until we are the last non-daemon thread to execute
4403   { MonitorLocker nu(Threads_lock);
4404     while (Threads::number_of_non_daemon_threads() > 1)
4405       // This wait should make safepoint checks, wait without a timeout,
4406       // and wait as a suspend-equivalent condition.
4407       nu.wait(0, Mutex::_as_suspend_equivalent_flag);
4408   }
4409 
4410   EventShutdown e;
4411   if (e.should_commit()) {
4412     e.set_reason("No remaining non-daemon Java threads");
4413     e.commit();
4414   }
4415 
4416   // Hang forever on exit if we are reporting an error.
4417   if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4418     os::infinite_sleep();
4419   }
4420   os::wait_for_keypress_at_exit();
4421 
4422   // run Java level shutdown hooks
4423   thread->invoke_shutdown_hooks();
4424 
4425   before_exit(thread);
4426 
4427   thread->exit(true);
4428 
4429   // Stop VM thread.
4430   {
4431     // 4945125 The vm thread comes to a safepoint during exit.
4432     // GC vm_operations can get caught at the safepoint, and the
4433     // heap is unparseable if they are caught. Grab the Heap_lock
4434     // to prevent this. The GC vm_operations will not be able to
4435     // queue until after the vm thread is dead. After this point,
4436     // we'll never emerge out of the safepoint before the VM exits.
4437 
4438     MutexLocker ml(Heap_lock, Mutex::_no_safepoint_check_flag);
4439 
4440     VMThread::wait_for_vm_thread_exit();
4441     assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4442     VMThread::destroy();
4443   }
4444 
4445   // Now, all Java threads are gone except daemon threads. Daemon threads
4446   // running Java code or in VM are stopped by the Safepoint. However,
4447   // daemon threads executing native code are still running.  But they
4448   // will be stopped at native=>Java/VM barriers. Note that we can't
4449   // simply kill or suspend them, as it is inherently deadlock-prone.
4450 
4451   VM_Exit::set_vm_exited();
4452 
4453   // Clean up ideal graph printers after the VMThread has started
4454   // the final safepoint which will block all the Compiler threads.
4455   // Note that this Thread has already logically exited so the
4456   // clean_up() function's use of a JavaThreadIteratorWithHandle
4457   // would be a problem except set_vm_exited() has remembered the
4458   // shutdown thread which is granted a policy exception.
4459 #if defined(COMPILER2) && !defined(PRODUCT)
4460   IdealGraphPrinter::clean_up();
4461 #endif
4462 
4463   notify_vm_shutdown();
4464 
4465   // exit_globals() will delete tty
4466   exit_globals();
4467 
4468   // We are after VM_Exit::set_vm_exited() so we can't call
4469   // thread->smr_delete() or we will block on the Threads_lock.
4470   // Deleting the shutdown thread here is safe because another
4471   // JavaThread cannot have an active ThreadsListHandle for
4472   // this JavaThread.
4473   delete thread;
4474 
4475 #if INCLUDE_JVMCI
4476   if (JVMCICounterSize > 0) {
4477     FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4478   }
4479 #endif
4480 
4481   LogConfiguration::finalize();
4482 
4483   return true;
4484 }
4485 
4486 
4487 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4488   if (version == JNI_VERSION_1_1) return JNI_TRUE;
4489   return is_supported_jni_version(version);
4490 }
4491 
4492 
4493 jboolean Threads::is_supported_jni_version(jint version) {
4494   if (version == JNI_VERSION_1_2) return JNI_TRUE;
4495   if (version == JNI_VERSION_1_4) return JNI_TRUE;
4496   if (version == JNI_VERSION_1_6) return JNI_TRUE;
4497   if (version == JNI_VERSION_1_8) return JNI_TRUE;
4498   if (version == JNI_VERSION_9) return JNI_TRUE;
4499   if (version == JNI_VERSION_10) return JNI_TRUE;
4500   return JNI_FALSE;
4501 }
4502 
4503 
4504 void Threads::add(JavaThread* p, bool force_daemon) {
4505   // The threads lock must be owned at this point
4506   assert(Threads_lock->owned_by_self(), "must have threads lock");
4507 
4508   BarrierSet::barrier_set()->on_thread_attach(p);
4509 
4510   // Once a JavaThread is added to the Threads list, smr_delete() has
4511   // to be used to delete it. Otherwise we can just delete it directly.
4512   p->set_on_thread_list();
4513 
4514   _number_of_threads++;
4515   oop threadObj = p->threadObj();
4516   bool daemon = true;
4517   // Bootstrapping problem: threadObj can be null for initial
4518   // JavaThread (or for threads attached via JNI)
4519   if ((!force_daemon) && !is_daemon((threadObj))) {
4520     _number_of_non_daemon_threads++;
4521     daemon = false;
4522   }
4523 
4524   ThreadService::add_thread(p, daemon);
4525 
4526   // Maintain fast thread list
4527   ThreadsSMRSupport::add_thread(p);
4528 
4529   // Possible GC point.
4530   Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4531 }
4532 
4533 void Threads::remove(JavaThread* p, bool is_daemon) {
4534 
4535   // Reclaim the ObjectMonitors from the om_in_use_list and om_free_list of the moribund thread.
4536   ObjectSynchronizer::om_flush(p);
4537 
4538   // Extra scope needed for Thread_lock, so we can check
4539   // that we do not remove thread without safepoint code notice
4540   { MonitorLocker ml(Threads_lock);
4541 
4542     assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present");
4543 
4544     // Maintain fast thread list
4545     ThreadsSMRSupport::remove_thread(p);
4546 
4547     _number_of_threads--;
4548     if (!is_daemon) {
4549       _number_of_non_daemon_threads--;
4550 
4551       // Only one thread left, do a notify on the Threads_lock so a thread waiting
4552       // on destroy_vm will wake up.
4553       if (number_of_non_daemon_threads() == 1) {
4554         ml.notify_all();
4555       }
4556     }
4557     ThreadService::remove_thread(p, is_daemon);
4558 
4559     // Make sure that safepoint code disregard this thread. This is needed since
4560     // the thread might mess around with locks after this point. This can cause it
4561     // to do callbacks into the safepoint code. However, the safepoint code is not aware
4562     // of this thread since it is removed from the queue.
4563     p->set_terminated_value();
4564   } // unlock Threads_lock
4565 
4566   // Since Events::log uses a lock, we grab it outside the Threads_lock
4567   Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4568 }
4569 
4570 // Operations on the Threads list for GC.  These are not explicitly locked,
4571 // but the garbage collector must provide a safe context for them to run.
4572 // In particular, these things should never be called when the Threads_lock
4573 // is held by some other thread. (Note: the Safepoint abstraction also
4574 // uses the Threads_lock to guarantee this property. It also makes sure that
4575 // all threads gets blocked when exiting or starting).
4576 
4577 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4578   ALL_JAVA_THREADS(p) {
4579     p->oops_do(f, cf);
4580   }
4581   VMThread::vm_thread()->oops_do(f, cf);
4582 }
4583 
4584 void Threads::change_thread_claim_token() {
4585   if (++_thread_claim_token == 0) {
4586     // On overflow of the token counter, there is a risk of future
4587     // collisions between a new global token value and a stale token
4588     // for a thread, because not all iterations visit all threads.
4589     // (Though it's pretty much a theoretical concern for non-trivial
4590     // token counter sizes.)  To deal with the possibility, reset all
4591     // the thread tokens to zero on global token overflow.
4592     struct ResetClaims : public ThreadClosure {
4593       virtual void do_thread(Thread* t) {
4594         t->claim_threads_do(false, 0);
4595       }
4596     } reset_claims;
4597     Threads::threads_do(&reset_claims);
4598     // On overflow, update the global token to non-zero, to
4599     // avoid the special "never claimed" initial thread value.
4600     _thread_claim_token = 1;
4601   }
4602 }
4603 
4604 #ifdef ASSERT
4605 void assert_thread_claimed(const char* kind, Thread* t, uintx expected) {
4606   const uintx token = t->threads_do_token();
4607   assert(token == expected,
4608          "%s " PTR_FORMAT " has incorrect value " UINTX_FORMAT " != "
4609          UINTX_FORMAT, kind, p2i(t), token, expected);
4610 }
4611 
4612 void Threads::assert_all_threads_claimed() {
4613   ALL_JAVA_THREADS(p) {
4614     assert_thread_claimed("Thread", p, _thread_claim_token);
4615   }
4616   assert_thread_claimed("VMThread", VMThread::vm_thread(), _thread_claim_token);
4617 }
4618 #endif // ASSERT
4619 
4620 class ParallelOopsDoThreadClosure : public ThreadClosure {
4621 private:
4622   OopClosure* _f;
4623   CodeBlobClosure* _cf;
4624 public:
4625   ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {}
4626   void do_thread(Thread* t) {
4627     t->oops_do(_f, _cf);
4628   }
4629 };
4630 
4631 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4632   ParallelOopsDoThreadClosure tc(f, cf);
4633   possibly_parallel_threads_do(is_par, &tc);
4634 }
4635 
4636 void Threads::nmethods_do(CodeBlobClosure* cf) {
4637   ALL_JAVA_THREADS(p) {
4638     // This is used by the code cache sweeper to mark nmethods that are active
4639     // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4640     // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4641     if(!p->is_Code_cache_sweeper_thread()) {
4642       p->nmethods_do(cf);
4643     }
4644   }
4645 }
4646 
4647 void Threads::metadata_do(MetadataClosure* f) {
4648   ALL_JAVA_THREADS(p) {
4649     p->metadata_do(f);
4650   }
4651 }
4652 
4653 class ThreadHandlesClosure : public ThreadClosure {
4654   void (*_f)(Metadata*);
4655  public:
4656   ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4657   virtual void do_thread(Thread* thread) {
4658     thread->metadata_handles_do(_f);
4659   }
4660 };
4661 
4662 void Threads::metadata_handles_do(void f(Metadata*)) {
4663   // Only walk the Handles in Thread.
4664   ThreadHandlesClosure handles_closure(f);
4665   threads_do(&handles_closure);
4666 }
4667 
4668 // Get count Java threads that are waiting to enter the specified monitor.
4669 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
4670                                                          int count,
4671                                                          address monitor) {
4672   GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4673 
4674   int i = 0;
4675   DO_JAVA_THREADS(t_list, p) {
4676     if (!p->can_call_java()) continue;
4677 
4678     address pending = (address)p->current_pending_monitor();
4679     if (pending == monitor) {             // found a match
4680       if (i < count) result->append(p);   // save the first count matches
4681       i++;
4682     }
4683   }
4684 
4685   return result;
4686 }
4687 
4688 
4689 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
4690                                                       address owner) {
4691   // NULL owner means not locked so we can skip the search
4692   if (owner == NULL) return NULL;
4693 
4694   DO_JAVA_THREADS(t_list, p) {
4695     // first, see if owner is the address of a Java thread
4696     if (owner == (address)p) return p;
4697   }
4698 
4699   // Cannot assert on lack of success here since this function may be
4700   // used by code that is trying to report useful problem information
4701   // like deadlock detection.
4702   if (UseHeavyMonitors) return NULL;
4703 
4704   // If we didn't find a matching Java thread and we didn't force use of
4705   // heavyweight monitors, then the owner is the stack address of the
4706   // Lock Word in the owning Java thread's stack.
4707   //
4708   JavaThread* the_owner = NULL;
4709   DO_JAVA_THREADS(t_list, q) {
4710     if (q->is_lock_owned(owner)) {
4711       the_owner = q;
4712       break;
4713     }
4714   }
4715 
4716   // cannot assert on lack of success here; see above comment
4717   return the_owner;
4718 }
4719 
4720 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4721 void Threads::print_on(outputStream* st, bool print_stacks,
4722                        bool internal_format, bool print_concurrent_locks,
4723                        bool print_extended_info) {
4724   char buf[32];
4725   st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4726 
4727   st->print_cr("Full thread dump %s (%s %s):",
4728                VM_Version::vm_name(),
4729                VM_Version::vm_release(),
4730                VM_Version::vm_info_string());
4731   st->cr();
4732 
4733 #if INCLUDE_SERVICES
4734   // Dump concurrent locks
4735   ConcurrentLocksDump concurrent_locks;
4736   if (print_concurrent_locks) {
4737     concurrent_locks.dump_at_safepoint();
4738   }
4739 #endif // INCLUDE_SERVICES
4740 
4741   ThreadsSMRSupport::print_info_on(st);
4742   st->cr();
4743 
4744   ALL_JAVA_THREADS(p) {
4745     ResourceMark rm;
4746     p->print_on(st, print_extended_info);
4747     if (print_stacks) {
4748       if (internal_format) {
4749         p->trace_stack();
4750       } else {
4751         p->print_stack_on(st);
4752       }
4753     }
4754     st->cr();
4755 #if INCLUDE_SERVICES
4756     if (print_concurrent_locks) {
4757       concurrent_locks.print_locks_on(p, st);
4758     }
4759 #endif // INCLUDE_SERVICES
4760   }
4761 
4762   VMThread::vm_thread()->print_on(st);
4763   st->cr();
4764   Universe::heap()->print_gc_threads_on(st);
4765   WatcherThread* wt = WatcherThread::watcher_thread();
4766   if (wt != NULL) {
4767     wt->print_on(st);
4768     st->cr();
4769   }
4770 
4771   st->flush();
4772 }
4773 
4774 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4775                              int buflen, bool* found_current) {
4776   if (this_thread != NULL) {
4777     bool is_current = (current == this_thread);
4778     *found_current = *found_current || is_current;
4779     st->print("%s", is_current ? "=>" : "  ");
4780 
4781     st->print(PTR_FORMAT, p2i(this_thread));
4782     st->print(" ");
4783     this_thread->print_on_error(st, buf, buflen);
4784     st->cr();
4785   }
4786 }
4787 
4788 class PrintOnErrorClosure : public ThreadClosure {
4789   outputStream* _st;
4790   Thread* _current;
4791   char* _buf;
4792   int _buflen;
4793   bool* _found_current;
4794  public:
4795   PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4796                       int buflen, bool* found_current) :
4797    _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4798 
4799   virtual void do_thread(Thread* thread) {
4800     Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4801   }
4802 };
4803 
4804 // Threads::print_on_error() is called by fatal error handler. It's possible
4805 // that VM is not at safepoint and/or current thread is inside signal handler.
4806 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4807 // memory (even in resource area), it might deadlock the error handler.
4808 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4809                              int buflen) {
4810   ThreadsSMRSupport::print_info_on(st);
4811   st->cr();
4812 
4813   bool found_current = false;
4814   st->print_cr("Java Threads: ( => current thread )");
4815   ALL_JAVA_THREADS(thread) {
4816     print_on_error(thread, st, current, buf, buflen, &found_current);
4817   }
4818   st->cr();
4819 
4820   st->print_cr("Other Threads:");
4821   print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4822   print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4823 
4824   PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4825   Universe::heap()->gc_threads_do(&print_closure);
4826 
4827   if (!found_current) {
4828     st->cr();
4829     st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4830     current->print_on_error(st, buf, buflen);
4831     st->cr();
4832   }
4833   st->cr();
4834 
4835   st->print_cr("Threads with active compile tasks:");
4836   print_threads_compiling(st, buf, buflen);
4837 }
4838 
4839 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen, bool short_form) {
4840   ALL_JAVA_THREADS(thread) {
4841     if (thread->is_Compiler_thread()) {
4842       CompilerThread* ct = (CompilerThread*) thread;
4843 
4844       // Keep task in local variable for NULL check.
4845       // ct->_task might be set to NULL by concurring compiler thread
4846       // because it completed the compilation. The task is never freed,
4847       // though, just returned to a free list.
4848       CompileTask* task = ct->task();
4849       if (task != NULL) {
4850         thread->print_name_on_error(st, buf, buflen);
4851         st->print("  ");
4852         task->print(st, NULL, short_form, true);
4853       }
4854     }
4855   }
4856 }
4857 
4858 
4859 // Internal SpinLock and Mutex
4860 // Based on ParkEvent
4861 
4862 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4863 //
4864 // We employ SpinLocks _only for low-contention, fixed-length
4865 // short-duration critical sections where we're concerned
4866 // about native mutex_t or HotSpot Mutex:: latency.
4867 // The mux construct provides a spin-then-block mutual exclusion
4868 // mechanism.
4869 //
4870 // Testing has shown that contention on the ListLock guarding gFreeList
4871 // is common.  If we implement ListLock as a simple SpinLock it's common
4872 // for the JVM to devolve to yielding with little progress.  This is true
4873 // despite the fact that the critical sections protected by ListLock are
4874 // extremely short.
4875 //
4876 // TODO-FIXME: ListLock should be of type SpinLock.
4877 // We should make this a 1st-class type, integrated into the lock
4878 // hierarchy as leaf-locks.  Critically, the SpinLock structure
4879 // should have sufficient padding to avoid false-sharing and excessive
4880 // cache-coherency traffic.
4881 
4882 
4883 typedef volatile int SpinLockT;
4884 
4885 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4886   if (Atomic::cmpxchg(adr, 0, 1) == 0) {
4887     return;   // normal fast-path return
4888   }
4889 
4890   // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4891   int ctr = 0;
4892   int Yields = 0;
4893   for (;;) {
4894     while (*adr != 0) {
4895       ++ctr;
4896       if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4897         if (Yields > 5) {
4898           os::naked_short_sleep(1);
4899         } else {
4900           os::naked_yield();
4901           ++Yields;
4902         }
4903       } else {
4904         SpinPause();
4905       }
4906     }
4907     if (Atomic::cmpxchg(adr, 0, 1) == 0) return;
4908   }
4909 }
4910 
4911 void Thread::SpinRelease(volatile int * adr) {
4912   assert(*adr != 0, "invariant");
4913   OrderAccess::fence();      // guarantee at least release consistency.
4914   // Roach-motel semantics.
4915   // It's safe if subsequent LDs and STs float "up" into the critical section,
4916   // but prior LDs and STs within the critical section can't be allowed
4917   // to reorder or float past the ST that releases the lock.
4918   // Loads and stores in the critical section - which appear in program
4919   // order before the store that releases the lock - must also appear
4920   // before the store that releases the lock in memory visibility order.
4921   // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4922   // the ST of 0 into the lock-word which releases the lock, so fence
4923   // more than covers this on all platforms.
4924   *adr = 0;
4925 }
4926 
4927 // muxAcquire and muxRelease:
4928 //
4929 // *  muxAcquire and muxRelease support a single-word lock-word construct.
4930 //    The LSB of the word is set IFF the lock is held.
4931 //    The remainder of the word points to the head of a singly-linked list
4932 //    of threads blocked on the lock.
4933 //
4934 // *  The current implementation of muxAcquire-muxRelease uses its own
4935 //    dedicated Thread._MuxEvent instance.  If we're interested in
4936 //    minimizing the peak number of extant ParkEvent instances then
4937 //    we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4938 //    as certain invariants were satisfied.  Specifically, care would need
4939 //    to be taken with regards to consuming unpark() "permits".
4940 //    A safe rule of thumb is that a thread would never call muxAcquire()
4941 //    if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4942 //    park().  Otherwise the _ParkEvent park() operation in muxAcquire() could
4943 //    consume an unpark() permit intended for monitorenter, for instance.
4944 //    One way around this would be to widen the restricted-range semaphore
4945 //    implemented in park().  Another alternative would be to provide
4946 //    multiple instances of the PlatformEvent() for each thread.  One
4947 //    instance would be dedicated to muxAcquire-muxRelease, for instance.
4948 //
4949 // *  Usage:
4950 //    -- Only as leaf locks
4951 //    -- for short-term locking only as muxAcquire does not perform
4952 //       thread state transitions.
4953 //
4954 // Alternatives:
4955 // *  We could implement muxAcquire and muxRelease with MCS or CLH locks
4956 //    but with parking or spin-then-park instead of pure spinning.
4957 // *  Use Taura-Oyama-Yonenzawa locks.
4958 // *  It's possible to construct a 1-0 lock if we encode the lockword as
4959 //    (List,LockByte).  Acquire will CAS the full lockword while Release
4960 //    will STB 0 into the LockByte.  The 1-0 scheme admits stranding, so
4961 //    acquiring threads use timers (ParkTimed) to detect and recover from
4962 //    the stranding window.  Thread/Node structures must be aligned on 256-byte
4963 //    boundaries by using placement-new.
4964 // *  Augment MCS with advisory back-link fields maintained with CAS().
4965 //    Pictorially:  LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4966 //    The validity of the backlinks must be ratified before we trust the value.
4967 //    If the backlinks are invalid the exiting thread must back-track through the
4968 //    the forward links, which are always trustworthy.
4969 // *  Add a successor indication.  The LockWord is currently encoded as
4970 //    (List, LOCKBIT:1).  We could also add a SUCCBIT or an explicit _succ variable
4971 //    to provide the usual futile-wakeup optimization.
4972 //    See RTStt for details.
4973 //
4974 
4975 
4976 const intptr_t LOCKBIT = 1;
4977 
4978 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4979   intptr_t w = Atomic::cmpxchg(Lock, (intptr_t)0, LOCKBIT);
4980   if (w == 0) return;
4981   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(Lock, w, w|LOCKBIT) == w) {
4982     return;
4983   }
4984 
4985   ParkEvent * const Self = Thread::current()->_MuxEvent;
4986   assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4987   for (;;) {
4988     int its = (os::is_MP() ? 100 : 0) + 1;
4989 
4990     // Optional spin phase: spin-then-park strategy
4991     while (--its >= 0) {
4992       w = *Lock;
4993       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(Lock, w, w|LOCKBIT) == w) {
4994         return;
4995       }
4996     }
4997 
4998     Self->reset();
4999     Self->OnList = intptr_t(Lock);
5000     // The following fence() isn't _strictly necessary as the subsequent
5001     // CAS() both serializes execution and ratifies the fetched *Lock value.
5002     OrderAccess::fence();
5003     for (;;) {
5004       w = *Lock;
5005       if ((w & LOCKBIT) == 0) {
5006         if (Atomic::cmpxchg(Lock, w, w|LOCKBIT) == w) {
5007           Self->OnList = 0;   // hygiene - allows stronger asserts
5008           return;
5009         }
5010         continue;      // Interference -- *Lock changed -- Just retry
5011       }
5012       assert(w & LOCKBIT, "invariant");
5013       Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
5014       if (Atomic::cmpxchg(Lock, w, intptr_t(Self)|LOCKBIT) == w) break;
5015     }
5016 
5017     while (Self->OnList != 0) {
5018       Self->park();
5019     }
5020   }
5021 }
5022 
5023 // Release() must extract a successor from the list and then wake that thread.
5024 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
5025 // similar to that used by ParkEvent::Allocate() and ::Release().  DMR-based
5026 // Release() would :
5027 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
5028 // (B) Extract a successor from the private list "in-hand"
5029 // (C) attempt to CAS() the residual back into *Lock over null.
5030 //     If there were any newly arrived threads and the CAS() would fail.
5031 //     In that case Release() would detach the RATs, re-merge the list in-hand
5032 //     with the RATs and repeat as needed.  Alternately, Release() might
5033 //     detach and extract a successor, but then pass the residual list to the wakee.
5034 //     The wakee would be responsible for reattaching and remerging before it
5035 //     competed for the lock.
5036 //
5037 // Both "pop" and DMR are immune from ABA corruption -- there can be
5038 // multiple concurrent pushers, but only one popper or detacher.
5039 // This implementation pops from the head of the list.  This is unfair,
5040 // but tends to provide excellent throughput as hot threads remain hot.
5041 // (We wake recently run threads first).
5042 //
5043 // All paths through muxRelease() will execute a CAS.
5044 // Release consistency -- We depend on the CAS in muxRelease() to provide full
5045 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
5046 // executed within the critical section are complete and globally visible before the
5047 // store (CAS) to the lock-word that releases the lock becomes globally visible.
5048 void Thread::muxRelease(volatile intptr_t * Lock)  {
5049   for (;;) {
5050     const intptr_t w = Atomic::cmpxchg(Lock, LOCKBIT, (intptr_t)0);
5051     assert(w & LOCKBIT, "invariant");
5052     if (w == LOCKBIT) return;
5053     ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
5054     assert(List != NULL, "invariant");
5055     assert(List->OnList == intptr_t(Lock), "invariant");
5056     ParkEvent * const nxt = List->ListNext;
5057     guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
5058 
5059     // The following CAS() releases the lock and pops the head element.
5060     // The CAS() also ratifies the previously fetched lock-word value.
5061     if (Atomic::cmpxchg(Lock, w, intptr_t(nxt)) != w) {
5062       continue;
5063     }
5064     List->OnList = 0;
5065     OrderAccess::fence();
5066     List->unpark();
5067     return;
5068   }
5069 }
5070 
5071 
5072 void Threads::verify() {
5073   ALL_JAVA_THREADS(p) {
5074     p->verify();
5075   }
5076   VMThread* thread = VMThread::vm_thread();
5077   if (thread != NULL) thread->verify();
5078 }