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/deoptimization.hpp"
  70 #include "runtime/frame.inline.hpp"
  71 #include "runtime/handles.inline.hpp"
  72 #include "runtime/handshake.hpp"
  73 #include "runtime/init.hpp"
  74 #include "runtime/interfaceSupport.inline.hpp"
  75 #include "runtime/java.hpp"
  76 #include "runtime/javaCalls.hpp"
  77 #include "runtime/jniHandles.inline.hpp"
  78 #include "runtime/jniPeriodicChecker.hpp"
  79 #include "runtime/memprofiler.hpp"
  80 #include "runtime/mutexLocker.hpp"
  81 #include "runtime/objectMonitor.hpp"
  82 #include "runtime/orderAccess.hpp"
  83 #include "runtime/osThread.hpp"
  84 #include "runtime/prefetch.inline.hpp"
  85 #include "runtime/safepoint.hpp"
  86 #include "runtime/safepointMechanism.inline.hpp"
  87 #include "runtime/safepointVerifiers.hpp"
  88 #include "runtime/serviceThread.hpp"
  89 #include "runtime/sharedRuntime.hpp"
  90 #include "runtime/statSampler.hpp"
  91 #include "runtime/stubRoutines.hpp"
  92 #include "runtime/sweeper.hpp"
  93 #include "runtime/task.hpp"
  94 #include "runtime/thread.inline.hpp"
  95 #include "runtime/threadCritical.hpp"
  96 #include "runtime/threadSMR.inline.hpp"
  97 #include "runtime/threadStatisticalInfo.hpp"
  98 #include "runtime/timer.hpp"
  99 #include "runtime/timerTrace.hpp"
 100 #include "runtime/vframe.inline.hpp"
 101 #include "runtime/vframeArray.hpp"
 102 #include "runtime/vframe_hp.hpp"
 103 #include "runtime/vmThread.hpp"
 104 #include "runtime/vmOperations.hpp"
 105 #include "runtime/vm_version.hpp"
 106 #include "services/attachListener.hpp"
 107 #include "services/management.hpp"
 108 #include "services/memTracker.hpp"
 109 #include "services/threadService.hpp"
 110 #include "utilities/align.hpp"
 111 #include "utilities/copy.hpp"
 112 #include "utilities/defaultStream.hpp"
 113 #include "utilities/dtrace.hpp"
 114 #include "utilities/events.hpp"
 115 #include "utilities/macros.hpp"
 116 #include "utilities/preserveException.hpp"
 117 #include "utilities/singleWriterSynchronizer.hpp"
 118 #include "utilities/vmError.hpp"
 119 #if INCLUDE_JVMCI
 120 #include "jvmci/jvmci.hpp"
 121 #include "jvmci/jvmciEnv.hpp"
 122 #endif
 123 #ifdef COMPILER1
 124 #include "c1/c1_Compiler.hpp"
 125 #endif
 126 #ifdef COMPILER2
 127 #include "opto/c2compiler.hpp"
 128 #include "opto/idealGraphPrinter.hpp"
 129 #endif
 130 #if INCLUDE_RTM_OPT
 131 #include "runtime/rtmLocking.hpp"
 132 #endif
 133 #if INCLUDE_JFR
 134 #include "jfr/jfr.hpp"
 135 #endif
 136 
 137 // Initialization after module runtime initialization
 138 void universe_post_module_init();  // must happen after call_initPhase2
 139 
 140 #ifdef DTRACE_ENABLED
 141 
 142 // Only bother with this argument setup if dtrace is available
 143 
 144   #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
 145   #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
 146 
 147   #define DTRACE_THREAD_PROBE(probe, javathread)                           \
 148     {                                                                      \
 149       ResourceMark rm(this);                                               \
 150       int len = 0;                                                         \
 151       const char* name = (javathread)->get_thread_name();                  \
 152       len = strlen(name);                                                  \
 153       HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */               \
 154         (char *) name, len,                                                \
 155         java_lang_Thread::thread_id((javathread)->threadObj()),            \
 156         (uintptr_t) (javathread)->osthread()->thread_id(),                 \
 157         java_lang_Thread::is_daemon((javathread)->threadObj()));           \
 158     }
 159 
 160 #else //  ndef DTRACE_ENABLED
 161 
 162   #define DTRACE_THREAD_PROBE(probe, javathread)
 163 
 164 #endif // ndef DTRACE_ENABLED
 165 
 166 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 167 // Current thread is maintained as a thread-local variable
 168 THREAD_LOCAL Thread* Thread::_thr_current = NULL;
 169 #endif
 170 
 171 // ======= Thread ========
 172 // Support for forcing alignment of thread objects for biased locking
 173 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
 174   if (UseBiasedLocking) {
 175     const size_t alignment = markWord::biased_lock_alignment;
 176     size_t aligned_size = size + (alignment - sizeof(intptr_t));
 177     void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
 178                                           : AllocateHeap(aligned_size, flags, CURRENT_PC,
 179                                                          AllocFailStrategy::RETURN_NULL);
 180     void* aligned_addr     = align_up(real_malloc_addr, alignment);
 181     assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
 182            ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
 183            "JavaThread alignment code overflowed allocated storage");
 184     if (aligned_addr != real_malloc_addr) {
 185       log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
 186                               p2i(real_malloc_addr),
 187                               p2i(aligned_addr));
 188     }
 189     ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
 190     return aligned_addr;
 191   } else {
 192     return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
 193                        : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
 194   }
 195 }
 196 
 197 void Thread::operator delete(void* p) {
 198   if (UseBiasedLocking) {
 199     FreeHeap(((Thread*) p)->_real_malloc_address);
 200   } else {
 201     FreeHeap(p);
 202   }
 203 }
 204 
 205 void JavaThread::smr_delete() {
 206   if (_on_thread_list) {
 207     ThreadsSMRSupport::smr_delete(this);
 208   } else {
 209     delete this;
 210   }
 211 }
 212 
 213 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
 214 // JavaThread
 215 
 216 DEBUG_ONLY(Thread* Thread::_starting_thread = NULL;)
 217 
 218 Thread::Thread() {
 219 
 220   DEBUG_ONLY(_run_state = PRE_CALL_RUN;)
 221 
 222   // stack and get_thread
 223   set_stack_base(NULL);
 224   set_stack_size(0);
 225   set_lgrp_id(-1);
 226   DEBUG_ONLY(clear_suspendible_thread();)
 227 
 228   // allocated data structures
 229   set_osthread(NULL);
 230   set_resource_area(new (mtThread)ResourceArea());
 231   DEBUG_ONLY(_current_resource_mark = NULL;)
 232   set_handle_area(new (mtThread) HandleArea(NULL));
 233   set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
 234   set_active_handles(NULL);
 235   set_free_handle_block(NULL);
 236   set_last_handle_mark(NULL);
 237   DEBUG_ONLY(_missed_ic_stub_refill_verifier = NULL);
 238 
 239   // Initial value of zero ==> never claimed.
 240   _threads_do_token = 0;
 241   _threads_hazard_ptr = NULL;
 242   _threads_list_ptr = NULL;
 243   _nested_threads_hazard_ptr_cnt = 0;
 244   _rcu_counter = 0;
 245 
 246   // the handle mark links itself to last_handle_mark
 247   new HandleMark(this);
 248 
 249   // plain initialization
 250   debug_only(_owned_locks = NULL;)
 251   NOT_PRODUCT(_no_safepoint_count = 0;)
 252   NOT_PRODUCT(_skip_gcalot = false;)
 253   _jvmti_env_iteration_count = 0;
 254   set_allocated_bytes(0);
 255   _vm_operation_started_count = 0;
 256   _vm_operation_completed_count = 0;
 257   _current_pending_monitor = NULL;
 258   _current_pending_monitor_is_from_java = true;
 259   _current_waiting_monitor = NULL;
 260   _current_pending_raw_monitor = NULL;
 261   _num_nested_signal = 0;
 262   om_free_list = NULL;
 263   om_free_count = 0;
 264   om_free_provision = 32;
 265   om_in_use_list = NULL;
 266   om_in_use_count = 0;
 267 
 268 #ifdef ASSERT
 269   _visited_for_critical_count = false;
 270 #endif
 271 
 272   _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
 273                          Monitor::_safepoint_check_sometimes);
 274   _suspend_flags = 0;
 275 
 276   // thread-specific hashCode stream generator state - Marsaglia shift-xor form
 277   _hashStateX = os::random();
 278   _hashStateY = 842502087;
 279   _hashStateZ = 0x8767;    // (int)(3579807591LL & 0xffff) ;
 280   _hashStateW = 273326509;
 281 
 282   _OnTrap   = 0;
 283   _Stalled  = 0;
 284   _TypeTag  = 0x2BAD;
 285 
 286   // Many of the following fields are effectively final - immutable
 287   // Note that nascent threads can't use the Native Monitor-Mutex
 288   // construct until the _MutexEvent is initialized ...
 289   // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
 290   // we might instead use a stack of ParkEvents that we could provision on-demand.
 291   // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
 292   // and ::Release()
 293   _ParkEvent   = ParkEvent::Allocate(this);
 294   _MuxEvent    = ParkEvent::Allocate(this);
 295 
 296 #ifdef CHECK_UNHANDLED_OOPS
 297   if (CheckUnhandledOops) {
 298     _unhandled_oops = new UnhandledOops(this);
 299   }
 300 #endif // CHECK_UNHANDLED_OOPS
 301 #ifdef ASSERT
 302   if (UseBiasedLocking) {
 303     assert(is_aligned(this, markWord::biased_lock_alignment), "forced alignment of thread object failed");
 304     assert(this == _real_malloc_address ||
 305            this == align_up(_real_malloc_address, markWord::biased_lock_alignment),
 306            "bug in forced alignment of thread objects");
 307   }
 308 #endif // ASSERT
 309 
 310   // Notify the barrier set that a thread is being created. The initial
 311   // thread is created before the barrier set is available.  The call to
 312   // BarrierSet::on_thread_create() for this thread is therefore deferred
 313   // to BarrierSet::set_barrier_set().
 314   BarrierSet* const barrier_set = BarrierSet::barrier_set();
 315   if (barrier_set != NULL) {
 316     barrier_set->on_thread_create(this);
 317   } else {
 318     // Only the main thread should be created before the barrier set
 319     // and that happens just before Thread::current is set. No other thread
 320     // can attach as the VM is not created yet, so they can't execute this code.
 321     // If the main thread creates other threads before the barrier set that is an error.
 322     assert(Thread::current_or_null() == NULL, "creating thread before barrier set");
 323   }
 324 }
 325 
 326 void Thread::initialize_thread_current() {
 327 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 328   assert(_thr_current == NULL, "Thread::current already initialized");
 329   _thr_current = this;
 330 #endif
 331   assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
 332   ThreadLocalStorage::set_thread(this);
 333   assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
 334 }
 335 
 336 void Thread::clear_thread_current() {
 337   assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
 338 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 339   _thr_current = NULL;
 340 #endif
 341   ThreadLocalStorage::set_thread(NULL);
 342 }
 343 
 344 void Thread::record_stack_base_and_size() {
 345   // Note: at this point, Thread object is not yet initialized. Do not rely on
 346   // any members being initialized. Do not rely on Thread::current() being set.
 347   // If possible, refrain from doing anything which may crash or assert since
 348   // quite probably those crash dumps will be useless.
 349   set_stack_base(os::current_stack_base());
 350   set_stack_size(os::current_stack_size());
 351 
 352 #ifdef SOLARIS
 353   if (os::is_primordial_thread()) {
 354     os::Solaris::correct_stack_boundaries_for_primordial_thread(this);
 355   }
 356 #endif
 357 
 358   // Set stack limits after thread is initialized.
 359   if (is_Java_thread()) {
 360     ((JavaThread*) this)->set_stack_overflow_limit();
 361     ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
 362   }
 363 }
 364 
 365 #if INCLUDE_NMT
 366 void Thread::register_thread_stack_with_NMT() {
 367   MemTracker::record_thread_stack(stack_end(), stack_size());
 368 }
 369 #endif // INCLUDE_NMT
 370 
 371 void Thread::call_run() {
 372   DEBUG_ONLY(_run_state = CALL_RUN;)
 373 
 374   // At this point, Thread object should be fully initialized and
 375   // Thread::current() should be set.
 376 
 377   assert(Thread::current_or_null() != NULL, "current thread is unset");
 378   assert(Thread::current_or_null() == this, "current thread is wrong");
 379 
 380   // Perform common initialization actions
 381 
 382   register_thread_stack_with_NMT();
 383 
 384   JFR_ONLY(Jfr::on_thread_start(this);)
 385 
 386   log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
 387     PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
 388     os::current_thread_id(), p2i(stack_end()),
 389     p2i(stack_base()), stack_size()/1024);
 390 
 391   // Perform <ChildClass> initialization actions
 392   DEBUG_ONLY(_run_state = PRE_RUN;)
 393   this->pre_run();
 394 
 395   // Invoke <ChildClass>::run()
 396   DEBUG_ONLY(_run_state = RUN;)
 397   this->run();
 398   // Returned from <ChildClass>::run(). Thread finished.
 399 
 400   // Perform common tear-down actions
 401 
 402   assert(Thread::current_or_null() != NULL, "current thread is unset");
 403   assert(Thread::current_or_null() == this, "current thread is wrong");
 404 
 405   // Perform <ChildClass> tear-down actions
 406   DEBUG_ONLY(_run_state = POST_RUN;)
 407   this->post_run();
 408 
 409   // Note: at this point the thread object may already have deleted itself,
 410   // so from here on do not dereference *this*. Not all thread types currently
 411   // delete themselves when they terminate. But no thread should ever be deleted
 412   // asynchronously with respect to its termination - that is what _run_state can
 413   // be used to check.
 414 
 415   assert(Thread::current_or_null() == NULL, "current thread still present");
 416 }
 417 
 418 Thread::~Thread() {
 419 
 420   // Attached threads will remain in PRE_CALL_RUN, as will threads that don't actually
 421   // get started due to errors etc. Any active thread should at least reach post_run
 422   // before it is deleted (usually in post_run()).
 423   assert(_run_state == PRE_CALL_RUN ||
 424          _run_state == POST_RUN, "Active Thread deleted before post_run(): "
 425          "_run_state=%d", (int)_run_state);
 426 
 427   // Notify the barrier set that a thread is being destroyed. Note that a barrier
 428   // set might not be available if we encountered errors during bootstrapping.
 429   BarrierSet* const barrier_set = BarrierSet::barrier_set();
 430   if (barrier_set != NULL) {
 431     barrier_set->on_thread_destroy(this);
 432   }
 433 
 434   // stack_base can be NULL if the thread is never started or exited before
 435   // record_stack_base_and_size called. Although, we would like to ensure
 436   // that all started threads do call record_stack_base_and_size(), there is
 437   // not proper way to enforce that.
 438 #if INCLUDE_NMT
 439   if (_stack_base != NULL) {
 440     MemTracker::release_thread_stack(stack_end(), stack_size());
 441 #ifdef ASSERT
 442     set_stack_base(NULL);
 443 #endif
 444   }
 445 #endif // INCLUDE_NMT
 446 
 447   // deallocate data structures
 448   delete resource_area();
 449   // since the handle marks are using the handle area, we have to deallocated the root
 450   // handle mark before deallocating the thread's handle area,
 451   assert(last_handle_mark() != NULL, "check we have an element");
 452   delete last_handle_mark();
 453   assert(last_handle_mark() == NULL, "check we have reached the end");
 454 
 455   // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
 456   // We NULL out the fields for good hygiene.
 457   ParkEvent::Release(_ParkEvent); _ParkEvent   = NULL;
 458   ParkEvent::Release(_MuxEvent); _MuxEvent    = NULL;
 459 
 460   delete handle_area();
 461   delete metadata_handles();
 462 
 463   // SR_handler uses this as a termination indicator -
 464   // needs to happen before os::free_thread()
 465   delete _SR_lock;
 466   _SR_lock = NULL;
 467 
 468   // osthread() can be NULL, if creation of thread failed.
 469   if (osthread() != NULL) os::free_thread(osthread());
 470 
 471   // Clear Thread::current if thread is deleting itself and it has not
 472   // already been done. This must be done before the memory is deallocated.
 473   // Needed to ensure JNI correctly detects non-attached threads.
 474   if (this == Thread::current_or_null()) {
 475     Thread::clear_thread_current();
 476   }
 477 
 478   CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
 479 }
 480 
 481 #ifdef ASSERT
 482 // A JavaThread is considered "dangling" if it is not the current
 483 // thread, has been added the Threads list, the system is not at a
 484 // safepoint and the Thread is not "protected".
 485 //
 486 void Thread::check_for_dangling_thread_pointer(Thread *thread) {
 487   assert(!thread->is_Java_thread() || Thread::current() == thread ||
 488          !((JavaThread *) thread)->on_thread_list() ||
 489          SafepointSynchronize::is_at_safepoint() ||
 490          ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread),
 491          "possibility of dangling Thread pointer");
 492 }
 493 #endif
 494 
 495 ThreadPriority Thread::get_priority(const Thread* const thread) {
 496   ThreadPriority priority;
 497   // Can return an error!
 498   (void)os::get_priority(thread, priority);
 499   assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
 500   return priority;
 501 }
 502 
 503 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
 504   debug_only(check_for_dangling_thread_pointer(thread);)
 505   // Can return an error!
 506   (void)os::set_priority(thread, priority);
 507 }
 508 
 509 
 510 void Thread::start(Thread* thread) {
 511   // Start is different from resume in that its safety is guaranteed by context or
 512   // being called from a Java method synchronized on the Thread object.
 513   if (!DisableStartThread) {
 514     if (thread->is_Java_thread()) {
 515       // Initialize the thread state to RUNNABLE before starting this thread.
 516       // Can not set it after the thread started because we do not know the
 517       // exact thread state at that time. It could be in MONITOR_WAIT or
 518       // in SLEEPING or some other state.
 519       java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
 520                                           java_lang_Thread::RUNNABLE);
 521     }
 522     os::start_thread(thread);
 523   }
 524 }
 525 
 526 class InstallAsyncExceptionClosure : public HandshakeClosure {
 527   Handle _throwable; // The Throwable thrown at the target Thread
 528 public:
 529   InstallAsyncExceptionClosure(Handle throwable) : HandshakeClosure("InstallAsyncException"), _throwable(throwable) {}
 530 
 531   void do_thread(Thread* thr) {
 532     JavaThread* target = (JavaThread*)thr;
 533     // Note that this now allows multiple ThreadDeath exceptions to be
 534     // thrown at a thread.
 535     // The target thread has run and has not exited yet.
 536     target->send_thread_stop(_throwable());
 537   }
 538 };
 539 
 540 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
 541   Handle throwable(Thread::current(), java_throwable);
 542   JavaThread* target = java_lang_Thread::thread(java_thread);
 543   InstallAsyncExceptionClosure vm_stop(throwable);
 544   Handshake::execute(&vm_stop, target);
 545 }
 546 
 547 
 548 // Check if an external suspend request has completed (or has been
 549 // cancelled). Returns true if the thread is externally suspended and
 550 // false otherwise.
 551 //
 552 // The bits parameter returns information about the code path through
 553 // the routine. Useful for debugging:
 554 //
 555 // set in is_ext_suspend_completed():
 556 // 0x00000001 - routine was entered
 557 // 0x00000010 - routine return false at end
 558 // 0x00000100 - thread exited (return false)
 559 // 0x00000200 - suspend request cancelled (return false)
 560 // 0x00000400 - thread suspended (return true)
 561 // 0x00001000 - thread is in a suspend equivalent state (return true)
 562 // 0x00002000 - thread is native and walkable (return true)
 563 // 0x00004000 - thread is native_trans and walkable (needed retry)
 564 //
 565 // set in wait_for_ext_suspend_completion():
 566 // 0x00010000 - routine was entered
 567 // 0x00020000 - suspend request cancelled before loop (return false)
 568 // 0x00040000 - thread suspended before loop (return true)
 569 // 0x00080000 - suspend request cancelled in loop (return false)
 570 // 0x00100000 - thread suspended in loop (return true)
 571 // 0x00200000 - suspend not completed during retry loop (return false)
 572 
 573 // Helper class for tracing suspend wait debug bits.
 574 //
 575 // 0x00000100 indicates that the target thread exited before it could
 576 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
 577 // 0x00080000 each indicate a cancelled suspend request so they don't
 578 // count as wait failures either.
 579 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
 580 
 581 class TraceSuspendDebugBits : public StackObj {
 582  private:
 583   JavaThread * jt;
 584   bool         is_wait;
 585   bool         called_by_wait;  // meaningful when !is_wait
 586   uint32_t *   bits;
 587 
 588  public:
 589   TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
 590                         uint32_t *_bits) {
 591     jt             = _jt;
 592     is_wait        = _is_wait;
 593     called_by_wait = _called_by_wait;
 594     bits           = _bits;
 595   }
 596 
 597   ~TraceSuspendDebugBits() {
 598     if (!is_wait) {
 599 #if 1
 600       // By default, don't trace bits for is_ext_suspend_completed() calls.
 601       // That trace is very chatty.
 602       return;
 603 #else
 604       if (!called_by_wait) {
 605         // If tracing for is_ext_suspend_completed() is enabled, then only
 606         // trace calls to it from wait_for_ext_suspend_completion()
 607         return;
 608       }
 609 #endif
 610     }
 611 
 612     if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
 613       if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
 614         MutexLocker ml(Threads_lock);  // needed for get_thread_name()
 615         ResourceMark rm;
 616 
 617         tty->print_cr(
 618                       "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
 619                       jt->get_thread_name(), *bits);
 620 
 621         guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
 622       }
 623     }
 624   }
 625 };
 626 #undef DEBUG_FALSE_BITS
 627 
 628 
 629 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
 630                                           uint32_t *bits) {
 631   TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
 632 
 633   bool did_trans_retry = false;  // only do thread_in_native_trans retry once
 634   bool do_trans_retry;           // flag to force the retry
 635 
 636   *bits |= 0x00000001;
 637 
 638   do {
 639     do_trans_retry = false;
 640 
 641     if (is_exiting()) {
 642       // Thread is in the process of exiting. This is always checked
 643       // first to reduce the risk of dereferencing a freed JavaThread.
 644       *bits |= 0x00000100;
 645       return false;
 646     }
 647 
 648     if (!is_external_suspend()) {
 649       // Suspend request is cancelled. This is always checked before
 650       // is_ext_suspended() to reduce the risk of a rogue resume
 651       // confusing the thread that made the suspend request.
 652       *bits |= 0x00000200;
 653       return false;
 654     }
 655 
 656     if (is_ext_suspended()) {
 657       // thread is suspended
 658       *bits |= 0x00000400;
 659       return true;
 660     }
 661 
 662     // Now that we no longer do hard suspends of threads running
 663     // native code, the target thread can be changing thread state
 664     // while we are in this routine:
 665     //
 666     //   _thread_in_native -> _thread_in_native_trans -> _thread_blocked
 667     //
 668     // We save a copy of the thread state as observed at this moment
 669     // and make our decision about suspend completeness based on the
 670     // copy. This closes the race where the thread state is seen as
 671     // _thread_in_native_trans in the if-thread_blocked check, but is
 672     // seen as _thread_blocked in if-thread_in_native_trans check.
 673     JavaThreadState save_state = thread_state();
 674 
 675     if (save_state == _thread_blocked && is_suspend_equivalent()) {
 676       // If the thread's state is _thread_blocked and this blocking
 677       // condition is known to be equivalent to a suspend, then we can
 678       // consider the thread to be externally suspended. This means that
 679       // the code that sets _thread_blocked has been modified to do
 680       // self-suspension if the blocking condition releases. We also
 681       // used to check for CONDVAR_WAIT here, but that is now covered by
 682       // the _thread_blocked with self-suspension check.
 683       //
 684       // Return true since we wouldn't be here unless there was still an
 685       // external suspend request.
 686       *bits |= 0x00001000;
 687       return true;
 688     } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
 689       // Threads running native code will self-suspend on native==>VM/Java
 690       // transitions. If its stack is walkable (should always be the case
 691       // unless this function is called before the actual java_suspend()
 692       // call), then the wait is done.
 693       *bits |= 0x00002000;
 694       return true;
 695     } else if (!called_by_wait && !did_trans_retry &&
 696                save_state == _thread_in_native_trans &&
 697                frame_anchor()->walkable()) {
 698       // The thread is transitioning from thread_in_native to another
 699       // thread state. check_safepoint_and_suspend_for_native_trans()
 700       // will force the thread to self-suspend. If it hasn't gotten
 701       // there yet we may have caught the thread in-between the native
 702       // code check above and the self-suspend. Lucky us. If we were
 703       // called by wait_for_ext_suspend_completion(), then it
 704       // will be doing the retries so we don't have to.
 705       //
 706       // Since we use the saved thread state in the if-statement above,
 707       // there is a chance that the thread has already transitioned to
 708       // _thread_blocked by the time we get here. In that case, we will
 709       // make a single unnecessary pass through the logic below. This
 710       // doesn't hurt anything since we still do the trans retry.
 711 
 712       *bits |= 0x00004000;
 713 
 714       // Once the thread leaves thread_in_native_trans for another
 715       // thread state, we break out of this retry loop. We shouldn't
 716       // need this flag to prevent us from getting back here, but
 717       // sometimes paranoia is good.
 718       did_trans_retry = true;
 719 
 720       // We wait for the thread to transition to a more usable state.
 721       for (int i = 1; i <= SuspendRetryCount; i++) {
 722         // We used to do an "os::yield_all(i)" call here with the intention
 723         // that yielding would increase on each retry. However, the parameter
 724         // is ignored on Linux which means the yield didn't scale up. Waiting
 725         // on the SR_lock below provides a much more predictable scale up for
 726         // the delay. It also provides a simple/direct point to check for any
 727         // safepoint requests from the VMThread
 728 
 729         // temporarily drops SR_lock while doing wait with safepoint check
 730         // (if we're a JavaThread - the WatcherThread can also call this)
 731         // and increase delay with each retry
 732         if (Thread::current()->is_Java_thread()) {
 733           SR_lock()->wait(i * delay);
 734         } else {
 735           SR_lock()->wait_without_safepoint_check(i * delay);
 736         }
 737 
 738         // check the actual thread state instead of what we saved above
 739         if (thread_state() != _thread_in_native_trans) {
 740           // the thread has transitioned to another thread state so
 741           // try all the checks (except this one) one more time.
 742           do_trans_retry = true;
 743           break;
 744         }
 745       } // end retry loop
 746 
 747 
 748     }
 749   } while (do_trans_retry);
 750 
 751   *bits |= 0x00000010;
 752   return false;
 753 }
 754 
 755 // Wait for an external suspend request to complete (or be cancelled).
 756 // Returns true if the thread is externally suspended and false otherwise.
 757 //
 758 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
 759                                                  uint32_t *bits) {
 760   TraceSuspendDebugBits tsdb(this, true /* is_wait */,
 761                              false /* !called_by_wait */, bits);
 762 
 763   // local flag copies to minimize SR_lock hold time
 764   bool is_suspended;
 765   bool pending;
 766   uint32_t reset_bits;
 767 
 768   // set a marker so is_ext_suspend_completed() knows we are the caller
 769   *bits |= 0x00010000;
 770 
 771   // We use reset_bits to reinitialize the bits value at the top of
 772   // each retry loop. This allows the caller to make use of any
 773   // unused bits for their own marking purposes.
 774   reset_bits = *bits;
 775 
 776   {
 777     MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
 778     is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 779                                             delay, bits);
 780     pending = is_external_suspend();
 781   }
 782   // must release SR_lock to allow suspension to complete
 783 
 784   if (!pending) {
 785     // A cancelled suspend request is the only false return from
 786     // is_ext_suspend_completed() that keeps us from entering the
 787     // retry loop.
 788     *bits |= 0x00020000;
 789     return false;
 790   }
 791 
 792   if (is_suspended) {
 793     *bits |= 0x00040000;
 794     return true;
 795   }
 796 
 797   for (int i = 1; i <= retries; i++) {
 798     *bits = reset_bits;  // reinit to only track last retry
 799 
 800     // We used to do an "os::yield_all(i)" call here with the intention
 801     // that yielding would increase on each retry. However, the parameter
 802     // is ignored on Linux which means the yield didn't scale up. Waiting
 803     // on the SR_lock below provides a much more predictable scale up for
 804     // the delay. It also provides a simple/direct point to check for any
 805     // safepoint requests from the VMThread
 806 
 807     {
 808       Thread* t = Thread::current();
 809       MonitorLocker ml(SR_lock(),
 810                        t->is_Java_thread() ? Mutex::_safepoint_check_flag : Mutex::_no_safepoint_check_flag);
 811       // wait with safepoint check (if we're a JavaThread - the WatcherThread
 812       // can also call this)  and increase delay with each retry
 813       ml.wait(i * delay);
 814 
 815       is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 816                                               delay, bits);
 817 
 818       // It is possible for the external suspend request to be cancelled
 819       // (by a resume) before the actual suspend operation is completed.
 820       // Refresh our local copy to see if we still need to wait.
 821       pending = is_external_suspend();
 822     }
 823 
 824     if (!pending) {
 825       // A cancelled suspend request is the only false return from
 826       // is_ext_suspend_completed() that keeps us from staying in the
 827       // retry loop.
 828       *bits |= 0x00080000;
 829       return false;
 830     }
 831 
 832     if (is_suspended) {
 833       *bits |= 0x00100000;
 834       return true;
 835     }
 836   } // end retry loop
 837 
 838   // thread did not suspend after all our retries
 839   *bits |= 0x00200000;
 840   return false;
 841 }
 842 
 843 // Called from API entry points which perform stack walking. If the
 844 // associated JavaThread is the current thread, then wait_for_suspend
 845 // is not used. Otherwise, it determines if we should wait for the
 846 // "other" thread to complete external suspension. (NOTE: in future
 847 // releases the suspension mechanism should be reimplemented so this
 848 // is not necessary.)
 849 //
 850 bool
 851 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) {
 852   if (this != JavaThread::current()) {
 853     // "other" threads require special handling.
 854     if (wait_for_suspend) {
 855       // We are allowed to wait for the external suspend to complete
 856       // so give the other thread a chance to get suspended.
 857       if (!wait_for_ext_suspend_completion(SuspendRetryCount,
 858                                            SuspendRetryDelay, bits)) {
 859         // Didn't make it so let the caller know.
 860         return false;
 861       }
 862     }
 863     // We aren't allowed to wait for the external suspend to complete
 864     // so if the other thread isn't externally suspended we need to
 865     // let the caller know.
 866     else if (!is_ext_suspend_completed_with_lock(bits)) {
 867       return false;
 868     }
 869   }
 870 
 871   return true;
 872 }
 873 
 874 // GC Support
 875 bool Thread::claim_par_threads_do(uintx claim_token) {
 876   uintx token = _threads_do_token;
 877   if (token != claim_token) {
 878     uintx res = Atomic::cmpxchg(&_threads_do_token, token, claim_token);
 879     if (res == token) {
 880       return true;
 881     }
 882     guarantee(res == claim_token, "invariant");
 883   }
 884   return false;
 885 }
 886 
 887 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
 888   if (active_handles() != NULL) {
 889     active_handles()->oops_do(f);
 890   }
 891   // Do oop for ThreadShadow
 892   f->do_oop((oop*)&_pending_exception);
 893   handle_area()->oops_do(f);
 894 
 895   // We scan thread local monitor lists here, and the remaining global
 896   // monitors in ObjectSynchronizer::oops_do().
 897   ObjectSynchronizer::thread_local_used_oops_do(this, f);
 898 }
 899 
 900 void Thread::metadata_handles_do(void f(Metadata*)) {
 901   // Only walk the Handles in Thread.
 902   if (metadata_handles() != NULL) {
 903     for (int i = 0; i< metadata_handles()->length(); i++) {
 904       f(metadata_handles()->at(i));
 905     }
 906   }
 907 }
 908 
 909 void Thread::print_on(outputStream* st, bool print_extended_info) const {
 910   // get_priority assumes osthread initialized
 911   if (osthread() != NULL) {
 912     int os_prio;
 913     if (os::get_native_priority(this, &os_prio) == OS_OK) {
 914       st->print("os_prio=%d ", os_prio);
 915     }
 916 
 917     st->print("cpu=%.2fms ",
 918               os::thread_cpu_time(const_cast<Thread*>(this), true) / 1000000.0
 919               );
 920     st->print("elapsed=%.2fs ",
 921               _statistical_info.getElapsedTime() / 1000.0
 922               );
 923     if (is_Java_thread() && (PrintExtendedThreadInfo || print_extended_info)) {
 924       size_t allocated_bytes = (size_t) const_cast<Thread*>(this)->cooked_allocated_bytes();
 925       st->print("allocated=" SIZE_FORMAT "%s ",
 926                 byte_size_in_proper_unit(allocated_bytes),
 927                 proper_unit_for_byte_size(allocated_bytes)
 928                 );
 929       st->print("defined_classes=" INT64_FORMAT " ", _statistical_info.getDefineClassCount());
 930     }
 931 
 932     st->print("tid=" INTPTR_FORMAT " ", p2i(this));
 933     osthread()->print_on(st);
 934   }
 935   ThreadsSMRSupport::print_info_on(this, st);
 936   st->print(" ");
 937   debug_only(if (WizardMode) print_owned_locks_on(st);)
 938 }
 939 
 940 void Thread::print() const { print_on(tty); }
 941 
 942 // Thread::print_on_error() is called by fatal error handler. Don't use
 943 // any lock or allocate memory.
 944 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
 945   assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
 946 
 947   if (is_VM_thread())                 { st->print("VMThread"); }
 948   else if (is_GC_task_thread())       { st->print("GCTaskThread"); }
 949   else if (is_Watcher_thread())       { st->print("WatcherThread"); }
 950   else if (is_ConcurrentGC_thread())  { st->print("ConcurrentGCThread"); }
 951   else                                { st->print("Thread"); }
 952 
 953   if (is_Named_thread()) {
 954     st->print(" \"%s\"", name());
 955   }
 956 
 957   st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
 958             p2i(stack_end()), p2i(stack_base()));
 959 
 960   if (osthread()) {
 961     st->print(" [id=%d]", osthread()->thread_id());
 962   }
 963 
 964   ThreadsSMRSupport::print_info_on(this, st);
 965 }
 966 
 967 void Thread::print_value_on(outputStream* st) const {
 968   if (is_Named_thread()) {
 969     st->print(" \"%s\" ", name());
 970   }
 971   st->print(INTPTR_FORMAT, p2i(this));   // print address
 972 }
 973 
 974 #ifdef ASSERT
 975 void Thread::print_owned_locks_on(outputStream* st) const {
 976   Mutex* cur = _owned_locks;
 977   if (cur == NULL) {
 978     st->print(" (no locks) ");
 979   } else {
 980     st->print_cr(" Locks owned:");
 981     while (cur) {
 982       cur->print_on(st);
 983       cur = cur->next();
 984     }
 985   }
 986 }
 987 
 988 // Checks safepoint allowed and clears unhandled oops at potential safepoints.
 989 void Thread::check_possible_safepoint() {
 990   if (!is_Java_thread()) return;
 991 
 992   if (_no_safepoint_count > 0) {
 993     print_owned_locks();
 994     fatal("Possible safepoint reached by thread that does not allow it");
 995   }
 996 #ifdef CHECK_UNHANDLED_OOPS
 997   // Clear unhandled oops in JavaThreads so we get a crash right away.
 998   clear_unhandled_oops();
 999 #endif // CHECK_UNHANDLED_OOPS
1000 }
1001 
1002 void Thread::check_for_valid_safepoint_state() {
1003   if (!is_Java_thread()) return;
1004 
1005   // Check NoSafepointVerifier, which is implied by locks taken that can be
1006   // shared with the VM thread.  This makes sure that no locks with allow_vm_block
1007   // are held.
1008   check_possible_safepoint();
1009 
1010   if (((JavaThread*)this)->thread_state() != _thread_in_vm) {
1011     fatal("LEAF method calling lock?");
1012   }
1013 
1014   if (GCALotAtAllSafepoints) {
1015     // We could enter a safepoint here and thus have a gc
1016     InterfaceSupport::check_gc_alot();
1017   }
1018 }
1019 #endif // ASSERT
1020 
1021 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
1022 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
1023 // used for compilation in the future. If that change is made, the need for these methods
1024 // should be revisited, and they should be removed if possible.
1025 
1026 bool Thread::is_lock_owned(address adr) const {
1027   return is_in_full_stack(adr);
1028 }
1029 
1030 bool Thread::set_as_starting_thread() {
1031   assert(_starting_thread == NULL, "already initialized: "
1032          "_starting_thread=" INTPTR_FORMAT, p2i(_starting_thread));
1033   // NOTE: this must be called inside the main thread.
1034   DEBUG_ONLY(_starting_thread = this;)
1035   return os::create_main_thread((JavaThread*)this);
1036 }
1037 
1038 static void initialize_class(Symbol* class_name, TRAPS) {
1039   Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
1040   InstanceKlass::cast(klass)->initialize(CHECK);
1041 }
1042 
1043 
1044 // Creates the initial ThreadGroup
1045 static Handle create_initial_thread_group(TRAPS) {
1046   Handle system_instance = JavaCalls::construct_new_instance(
1047                             SystemDictionary::ThreadGroup_klass(),
1048                             vmSymbols::void_method_signature(),
1049                             CHECK_NH);
1050   Universe::set_system_thread_group(system_instance());
1051 
1052   Handle string = java_lang_String::create_from_str("main", CHECK_NH);
1053   Handle main_instance = JavaCalls::construct_new_instance(
1054                             SystemDictionary::ThreadGroup_klass(),
1055                             vmSymbols::threadgroup_string_void_signature(),
1056                             system_instance,
1057                             string,
1058                             CHECK_NH);
1059   return main_instance;
1060 }
1061 
1062 // Creates the initial Thread
1063 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
1064                                  TRAPS) {
1065   InstanceKlass* ik = SystemDictionary::Thread_klass();
1066   assert(ik->is_initialized(), "must be");
1067   instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
1068 
1069   // Cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1070   // constructor calls Thread.current(), which must be set here for the
1071   // initial thread.
1072   java_lang_Thread::set_thread(thread_oop(), thread);
1073   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1074   thread->set_threadObj(thread_oop());
1075 
1076   Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1077 
1078   JavaValue result(T_VOID);
1079   JavaCalls::call_special(&result, thread_oop,
1080                           ik,
1081                           vmSymbols::object_initializer_name(),
1082                           vmSymbols::threadgroup_string_void_signature(),
1083                           thread_group,
1084                           string,
1085                           CHECK_NULL);
1086   return thread_oop();
1087 }
1088 
1089 char java_runtime_name[128] = "";
1090 char java_runtime_version[128] = "";
1091 char java_runtime_vendor_version[128] = "";
1092 char java_runtime_vendor_vm_bug_url[128] = "";
1093 
1094 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1095 static const char* get_java_runtime_name(TRAPS) {
1096   Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1097                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1098   fieldDescriptor fd;
1099   bool found = k != NULL &&
1100                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1101                                                         vmSymbols::string_signature(), &fd);
1102   if (found) {
1103     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1104     if (name_oop == NULL) {
1105       return NULL;
1106     }
1107     const char* name = java_lang_String::as_utf8_string(name_oop,
1108                                                         java_runtime_name,
1109                                                         sizeof(java_runtime_name));
1110     return name;
1111   } else {
1112     return NULL;
1113   }
1114 }
1115 
1116 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1117 static const char* get_java_runtime_version(TRAPS) {
1118   Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1119                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1120   fieldDescriptor fd;
1121   bool found = k != NULL &&
1122                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1123                                                         vmSymbols::string_signature(), &fd);
1124   if (found) {
1125     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1126     if (name_oop == NULL) {
1127       return NULL;
1128     }
1129     const char* name = java_lang_String::as_utf8_string(name_oop,
1130                                                         java_runtime_version,
1131                                                         sizeof(java_runtime_version));
1132     return name;
1133   } else {
1134     return NULL;
1135   }
1136 }
1137 
1138 // extract the JRE vendor version from java.lang.VersionProps.VENDOR_VERSION
1139 static const char* get_java_runtime_vendor_version(TRAPS) {
1140   Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1141                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1142   fieldDescriptor fd;
1143   bool found = k != NULL &&
1144                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_vendor_version_name(),
1145                                                         vmSymbols::string_signature(), &fd);
1146   if (found) {
1147     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1148     if (name_oop == NULL) {
1149       return NULL;
1150     }
1151     const char* name = java_lang_String::as_utf8_string(name_oop,
1152                                                         java_runtime_vendor_version,
1153                                                         sizeof(java_runtime_vendor_version));
1154     return name;
1155   } else {
1156     return NULL;
1157   }
1158 }
1159 
1160 // extract the JRE vendor VM bug URL from java.lang.VersionProps.VENDOR_URL_VM_BUG
1161 static const char* get_java_runtime_vendor_vm_bug_url(TRAPS) {
1162   Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1163                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1164   fieldDescriptor fd;
1165   bool found = k != NULL &&
1166                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_vendor_vm_bug_url_name(),
1167                                                         vmSymbols::string_signature(), &fd);
1168   if (found) {
1169     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1170     if (name_oop == NULL) {
1171       return NULL;
1172     }
1173     const char* name = java_lang_String::as_utf8_string(name_oop,
1174                                                         java_runtime_vendor_vm_bug_url,
1175                                                         sizeof(java_runtime_vendor_vm_bug_url));
1176     return name;
1177   } else {
1178     return NULL;
1179   }
1180 }
1181 
1182 // General purpose hook into Java code, run once when the VM is initialized.
1183 // The Java library method itself may be changed independently from the VM.
1184 static void call_postVMInitHook(TRAPS) {
1185   Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1186   if (klass != NULL) {
1187     JavaValue result(T_VOID);
1188     JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1189                            vmSymbols::void_method_signature(),
1190                            CHECK);
1191   }
1192 }
1193 
1194 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1195                                     bool daemon, TRAPS) {
1196   assert(thread_group.not_null(), "thread group should be specified");
1197   assert(threadObj() == NULL, "should only create Java thread object once");
1198 
1199   InstanceKlass* ik = SystemDictionary::Thread_klass();
1200   assert(ik->is_initialized(), "must be");
1201   instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1202 
1203   // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon.
1204   // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1205   // constructor calls Thread.current(), which must be set here.
1206   java_lang_Thread::set_thread(thread_oop(), this);
1207   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1208   set_threadObj(thread_oop());
1209 
1210   JavaValue result(T_VOID);
1211   if (thread_name != NULL) {
1212     Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1213     // Thread gets assigned specified name and null target
1214     JavaCalls::call_special(&result,
1215                             thread_oop,
1216                             ik,
1217                             vmSymbols::object_initializer_name(),
1218                             vmSymbols::threadgroup_string_void_signature(),
1219                             thread_group,
1220                             name,
1221                             THREAD);
1222   } else {
1223     // Thread gets assigned name "Thread-nnn" and null target
1224     // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1225     JavaCalls::call_special(&result,
1226                             thread_oop,
1227                             ik,
1228                             vmSymbols::object_initializer_name(),
1229                             vmSymbols::threadgroup_runnable_void_signature(),
1230                             thread_group,
1231                             Handle(),
1232                             THREAD);
1233   }
1234 
1235 
1236   if (daemon) {
1237     java_lang_Thread::set_daemon(thread_oop());
1238   }
1239 
1240   if (HAS_PENDING_EXCEPTION) {
1241     return;
1242   }
1243 
1244   Klass* group = SystemDictionary::ThreadGroup_klass();
1245   Handle threadObj(THREAD, this->threadObj());
1246 
1247   JavaCalls::call_special(&result,
1248                           thread_group,
1249                           group,
1250                           vmSymbols::add_method_name(),
1251                           vmSymbols::thread_void_signature(),
1252                           threadObj,          // Arg 1
1253                           THREAD);
1254 }
1255 
1256 // List of all NonJavaThreads and safe iteration over that list.
1257 
1258 class NonJavaThread::List {
1259 public:
1260   NonJavaThread* volatile _head;
1261   SingleWriterSynchronizer _protect;
1262 
1263   List() : _head(NULL), _protect() {}
1264 };
1265 
1266 NonJavaThread::List NonJavaThread::_the_list;
1267 
1268 NonJavaThread::Iterator::Iterator() :
1269   _protect_enter(_the_list._protect.enter()),
1270   _current(Atomic::load_acquire(&_the_list._head))
1271 {}
1272 
1273 NonJavaThread::Iterator::~Iterator() {
1274   _the_list._protect.exit(_protect_enter);
1275 }
1276 
1277 void NonJavaThread::Iterator::step() {
1278   assert(!end(), "precondition");
1279   _current = Atomic::load_acquire(&_current->_next);
1280 }
1281 
1282 NonJavaThread::NonJavaThread() : Thread(), _next(NULL) {
1283   assert(BarrierSet::barrier_set() != NULL, "NonJavaThread created too soon!");
1284 }
1285 
1286 NonJavaThread::~NonJavaThread() { }
1287 
1288 void NonJavaThread::add_to_the_list() {
1289   MutexLocker ml(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1290   // Initialize BarrierSet-related data before adding to list.
1291   BarrierSet::barrier_set()->on_thread_attach(this);
1292   Atomic::release_store(&_next, _the_list._head);
1293   Atomic::release_store(&_the_list._head, this);
1294 }
1295 
1296 void NonJavaThread::remove_from_the_list() {
1297   {
1298     MutexLocker ml(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1299     // Cleanup BarrierSet-related data before removing from list.
1300     BarrierSet::barrier_set()->on_thread_detach(this);
1301     NonJavaThread* volatile* p = &_the_list._head;
1302     for (NonJavaThread* t = *p; t != NULL; p = &t->_next, t = *p) {
1303       if (t == this) {
1304         *p = _next;
1305         break;
1306       }
1307     }
1308   }
1309   // Wait for any in-progress iterators.  Concurrent synchronize is not
1310   // allowed, so do it while holding a dedicated lock.  Outside and distinct
1311   // from NJTList_lock in case an iteration attempts to lock it.
1312   MutexLocker ml(NonJavaThreadsListSync_lock, Mutex::_no_safepoint_check_flag);
1313   _the_list._protect.synchronize();
1314   _next = NULL;                 // Safe to drop the link now.
1315 }
1316 
1317 void NonJavaThread::pre_run() {
1318   add_to_the_list();
1319 
1320   // This is slightly odd in that NamedThread is a subclass, but
1321   // in fact name() is defined in Thread
1322   assert(this->name() != NULL, "thread name was not set before it was started");
1323   this->set_native_thread_name(this->name());
1324 }
1325 
1326 void NonJavaThread::post_run() {
1327   JFR_ONLY(Jfr::on_thread_exit(this);)
1328   remove_from_the_list();
1329   // Ensure thread-local-storage is cleared before termination.
1330   Thread::clear_thread_current();
1331 }
1332 
1333 // NamedThread --  non-JavaThread subclasses with multiple
1334 // uniquely named instances should derive from this.
1335 NamedThread::NamedThread() :
1336   NonJavaThread(),
1337   _name(NULL),
1338   _processed_thread(NULL),
1339   _gc_id(GCId::undefined())
1340 {}
1341 
1342 NamedThread::~NamedThread() {
1343   FREE_C_HEAP_ARRAY(char, _name);
1344 }
1345 
1346 void NamedThread::set_name(const char* format, ...) {
1347   guarantee(_name == NULL, "Only get to set name once.");
1348   _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1349   va_list ap;
1350   va_start(ap, format);
1351   jio_vsnprintf(_name, max_name_len, format, ap);
1352   va_end(ap);
1353 }
1354 
1355 void NamedThread::print_on(outputStream* st) const {
1356   st->print("\"%s\" ", name());
1357   Thread::print_on(st);
1358   st->cr();
1359 }
1360 
1361 
1362 // ======= WatcherThread ========
1363 
1364 // The watcher thread exists to simulate timer interrupts.  It should
1365 // be replaced by an abstraction over whatever native support for
1366 // timer interrupts exists on the platform.
1367 
1368 WatcherThread* WatcherThread::_watcher_thread   = NULL;
1369 bool WatcherThread::_startable = false;
1370 volatile bool  WatcherThread::_should_terminate = false;
1371 
1372 WatcherThread::WatcherThread() : NonJavaThread() {
1373   assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1374   if (os::create_thread(this, os::watcher_thread)) {
1375     _watcher_thread = this;
1376 
1377     // Set the watcher thread to the highest OS priority which should not be
1378     // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1379     // is created. The only normal thread using this priority is the reference
1380     // handler thread, which runs for very short intervals only.
1381     // If the VMThread's priority is not lower than the WatcherThread profiling
1382     // will be inaccurate.
1383     os::set_priority(this, MaxPriority);
1384     if (!DisableStartThread) {
1385       os::start_thread(this);
1386     }
1387   }
1388 }
1389 
1390 int WatcherThread::sleep() const {
1391   // The WatcherThread does not participate in the safepoint protocol
1392   // for the PeriodicTask_lock because it is not a JavaThread.
1393   MonitorLocker ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1394 
1395   if (_should_terminate) {
1396     // check for termination before we do any housekeeping or wait
1397     return 0;  // we did not sleep.
1398   }
1399 
1400   // remaining will be zero if there are no tasks,
1401   // causing the WatcherThread to sleep until a task is
1402   // enrolled
1403   int remaining = PeriodicTask::time_to_wait();
1404   int time_slept = 0;
1405 
1406   // we expect this to timeout - we only ever get unparked when
1407   // we should terminate or when a new task has been enrolled
1408   OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1409 
1410   jlong time_before_loop = os::javaTimeNanos();
1411 
1412   while (true) {
1413     bool timedout = ml.wait(remaining);
1414     jlong now = os::javaTimeNanos();
1415 
1416     if (remaining == 0) {
1417       // if we didn't have any tasks we could have waited for a long time
1418       // consider the time_slept zero and reset time_before_loop
1419       time_slept = 0;
1420       time_before_loop = now;
1421     } else {
1422       // need to recalculate since we might have new tasks in _tasks
1423       time_slept = (int) ((now - time_before_loop) / 1000000);
1424     }
1425 
1426     // Change to task list or spurious wakeup of some kind
1427     if (timedout || _should_terminate) {
1428       break;
1429     }
1430 
1431     remaining = PeriodicTask::time_to_wait();
1432     if (remaining == 0) {
1433       // Last task was just disenrolled so loop around and wait until
1434       // another task gets enrolled
1435       continue;
1436     }
1437 
1438     remaining -= time_slept;
1439     if (remaining <= 0) {
1440       break;
1441     }
1442   }
1443 
1444   return time_slept;
1445 }
1446 
1447 void WatcherThread::run() {
1448   assert(this == watcher_thread(), "just checking");
1449 
1450   this->set_active_handles(JNIHandleBlock::allocate_block());
1451   while (true) {
1452     assert(watcher_thread() == Thread::current(), "thread consistency check");
1453     assert(watcher_thread() == this, "thread consistency check");
1454 
1455     // Calculate how long it'll be until the next PeriodicTask work
1456     // should be done, and sleep that amount of time.
1457     int time_waited = sleep();
1458 
1459     if (VMError::is_error_reported()) {
1460       // A fatal error has happened, the error handler(VMError::report_and_die)
1461       // should abort JVM after creating an error log file. However in some
1462       // rare cases, the error handler itself might deadlock. Here periodically
1463       // check for error reporting timeouts, and if it happens, just proceed to
1464       // abort the VM.
1465 
1466       // This code is in WatcherThread because WatcherThread wakes up
1467       // periodically so the fatal error handler doesn't need to do anything;
1468       // also because the WatcherThread is less likely to crash than other
1469       // threads.
1470 
1471       for (;;) {
1472         // Note: we use naked sleep in this loop because we want to avoid using
1473         // any kind of VM infrastructure which may be broken at this point.
1474         if (VMError::check_timeout()) {
1475           // We hit error reporting timeout. Error reporting was interrupted and
1476           // will be wrapping things up now (closing files etc). Give it some more
1477           // time, then quit the VM.
1478           os::naked_short_sleep(200);
1479           // Print a message to stderr.
1480           fdStream err(defaultStream::output_fd());
1481           err.print_raw_cr("# [ timer expired, abort... ]");
1482           // skip atexit/vm_exit/vm_abort hooks
1483           os::die();
1484         }
1485 
1486         // Wait a second, then recheck for timeout.
1487         os::naked_short_sleep(999);
1488       }
1489     }
1490 
1491     if (_should_terminate) {
1492       // check for termination before posting the next tick
1493       break;
1494     }
1495 
1496     PeriodicTask::real_time_tick(time_waited);
1497   }
1498 
1499   // Signal that it is terminated
1500   {
1501     MutexLocker mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1502     _watcher_thread = NULL;
1503     Terminator_lock->notify_all();
1504   }
1505 }
1506 
1507 void WatcherThread::start() {
1508   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1509 
1510   if (watcher_thread() == NULL && _startable) {
1511     _should_terminate = false;
1512     // Create the single instance of WatcherThread
1513     new WatcherThread();
1514   }
1515 }
1516 
1517 void WatcherThread::make_startable() {
1518   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1519   _startable = true;
1520 }
1521 
1522 void WatcherThread::stop() {
1523   {
1524     // Follow normal safepoint aware lock enter protocol since the
1525     // WatcherThread is stopped by another JavaThread.
1526     MutexLocker ml(PeriodicTask_lock);
1527     _should_terminate = true;
1528 
1529     WatcherThread* watcher = watcher_thread();
1530     if (watcher != NULL) {
1531       // unpark the WatcherThread so it can see that it should terminate
1532       watcher->unpark();
1533     }
1534   }
1535 
1536   MonitorLocker mu(Terminator_lock);
1537 
1538   while (watcher_thread() != NULL) {
1539     // This wait should make safepoint checks, wait without a timeout,
1540     // and wait as a suspend-equivalent condition.
1541     mu.wait(0, Mutex::_as_suspend_equivalent_flag);
1542   }
1543 }
1544 
1545 void WatcherThread::unpark() {
1546   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1547   PeriodicTask_lock->notify();
1548 }
1549 
1550 void WatcherThread::print_on(outputStream* st) const {
1551   st->print("\"%s\" ", name());
1552   Thread::print_on(st);
1553   st->cr();
1554 }
1555 
1556 // ======= JavaThread ========
1557 
1558 #if INCLUDE_JVMCI
1559 
1560 jlong* JavaThread::_jvmci_old_thread_counters;
1561 
1562 bool jvmci_counters_include(JavaThread* thread) {
1563   return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1564 }
1565 
1566 void JavaThread::collect_counters(jlong* array, int length) {
1567   assert(length == JVMCICounterSize, "wrong value");
1568   for (int i = 0; i < length; i++) {
1569     array[i] = _jvmci_old_thread_counters[i];
1570   }
1571   for (JavaThreadIteratorWithHandle jtiwh; JavaThread *tp = jtiwh.next(); ) {
1572     if (jvmci_counters_include(tp)) {
1573       for (int i = 0; i < length; i++) {
1574         array[i] += tp->_jvmci_counters[i];
1575       }
1576     }
1577   }
1578 }
1579 
1580 // Attempt to enlarge the array for per thread counters.
1581 jlong* resize_counters_array(jlong* old_counters, int current_size, int new_size) {
1582   jlong* new_counters = NEW_C_HEAP_ARRAY(jlong, new_size, mtJVMCI);
1583   if (old_counters == NULL) {
1584     old_counters = new_counters;
1585     memset(old_counters, 0, sizeof(jlong) * new_size);
1586   } else {
1587     for (int i = 0; i < MIN2((int) current_size, new_size); i++) {
1588       new_counters[i] = old_counters[i];
1589     }
1590     if (new_size > current_size) {
1591       memset(new_counters + current_size, 0, sizeof(jlong) * (new_size - current_size));
1592     }
1593     FREE_C_HEAP_ARRAY(jlong, old_counters);
1594   }
1595   return new_counters;
1596 }
1597 
1598 // Attempt to enlarge the array for per thread counters.
1599 void JavaThread::resize_counters(int current_size, int new_size) {
1600   _jvmci_counters = resize_counters_array(_jvmci_counters, current_size, new_size);
1601 }
1602 
1603 class VM_JVMCIResizeCounters : public VM_Operation {
1604  private:
1605   int _new_size;
1606 
1607  public:
1608   VM_JVMCIResizeCounters(int new_size) : _new_size(new_size) { }
1609   VMOp_Type type()                  const        { return VMOp_JVMCIResizeCounters; }
1610   bool allow_nested_vm_operations() const        { return true; }
1611   void doit() {
1612     // Resize the old thread counters array
1613     jlong* new_counters = resize_counters_array(JavaThread::_jvmci_old_thread_counters, JVMCICounterSize, _new_size);
1614     JavaThread::_jvmci_old_thread_counters = new_counters;
1615 
1616     // Now resize each threads array
1617     for (JavaThreadIteratorWithHandle jtiwh; JavaThread *tp = jtiwh.next(); ) {
1618       tp->resize_counters(JVMCICounterSize, _new_size);
1619     }
1620     JVMCICounterSize = _new_size;
1621   }
1622 };
1623 
1624 void JavaThread::resize_all_jvmci_counters(int new_size) {
1625   VM_JVMCIResizeCounters op(new_size);
1626   VMThread::execute(&op);
1627 }
1628 
1629 #endif // INCLUDE_JVMCI
1630 
1631 // A JavaThread is a normal Java thread
1632 
1633 void JavaThread::initialize() {
1634   // Initialize fields
1635 
1636   set_saved_exception_pc(NULL);
1637   set_threadObj(NULL);
1638   _anchor.clear();
1639   set_entry_point(NULL);
1640   set_jni_functions(jni_functions());
1641   set_callee_target(NULL);
1642   set_vm_result(NULL);
1643   set_vm_result_2(NULL);
1644   set_vframe_array_head(NULL);
1645   set_vframe_array_last(NULL);
1646   set_deferred_locals(NULL);
1647   set_deopt_mark(NULL);
1648   set_deopt_compiled_method(NULL);
1649   set_monitor_chunks(NULL);
1650   _on_thread_list = false;
1651   _thread_state = _thread_new;
1652   _terminated = _not_terminated;
1653   _array_for_gc = NULL;
1654   _suspend_equivalent = false;
1655   _in_deopt_handler = 0;
1656   _doing_unsafe_access = false;
1657   _stack_guard_state = stack_guard_unused;
1658 #if INCLUDE_JVMCI
1659   _pending_monitorenter = false;
1660   _pending_deoptimization = -1;
1661   _pending_failed_speculation = 0;
1662   _pending_transfer_to_interpreter = false;
1663   _in_retryable_allocation = false;
1664   _jvmci._alternate_call_target = NULL;
1665   assert(_jvmci._implicit_exception_pc == NULL, "must be");
1666   _jvmci_counters = NULL;
1667   if (JVMCICounterSize > 0) {
1668     resize_counters(0, (int) JVMCICounterSize);
1669   }
1670 #endif // INCLUDE_JVMCI
1671   _reserved_stack_activation = NULL;  // stack base not known yet
1672   (void)const_cast<oop&>(_exception_oop = oop(NULL));
1673   _exception_pc  = 0;
1674   _exception_handler_pc = 0;
1675   _is_method_handle_return = 0;
1676   _jvmti_thread_state= NULL;
1677   _should_post_on_exceptions_flag = JNI_FALSE;
1678   _interp_only_mode    = 0;
1679   _special_runtime_exit_condition = _no_async_condition;
1680   _pending_async_exception = NULL;
1681   _thread_stat = NULL;
1682   _thread_stat = new ThreadStatistics();
1683   _jni_active_critical = 0;
1684   _pending_jni_exception_check_fn = NULL;
1685   _do_not_unlock_if_synchronized = false;
1686   _cached_monitor_info = NULL;
1687   _parker = Parker::Allocate(this);
1688   _SleepEvent = ParkEvent::Allocate(this);
1689   // Setup safepoint state info for this thread
1690   ThreadSafepointState::create(this);
1691 
1692   debug_only(_java_call_counter = 0);
1693 
1694   // JVMTI PopFrame support
1695   _popframe_condition = popframe_inactive;
1696   _popframe_preserved_args = NULL;
1697   _popframe_preserved_args_size = 0;
1698   _frames_to_pop_failed_realloc = 0;
1699 
1700   SafepointMechanism::initialize_header(this);
1701 
1702   _class_to_be_initialized = NULL;
1703 
1704   pd_initialize();
1705 }
1706 
1707 JavaThread::JavaThread(bool is_attaching_via_jni) :
1708                        Thread() {
1709   initialize();
1710   if (is_attaching_via_jni) {
1711     _jni_attach_state = _attaching_via_jni;
1712   } else {
1713     _jni_attach_state = _not_attaching_via_jni;
1714   }
1715   assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1716 }
1717 
1718 
1719 // interrupt support
1720 
1721 void JavaThread::interrupt() {
1722   debug_only(check_for_dangling_thread_pointer(this);)
1723 
1724   // For Windows _interrupt_event
1725   osthread()->set_interrupted(true);
1726 
1727   // For Thread.sleep
1728   _SleepEvent->unpark();
1729 
1730   // For JSR166 LockSupport.park
1731   parker()->unpark();
1732 
1733   // For ObjectMonitor and JvmtiRawMonitor
1734   _ParkEvent->unpark();
1735 }
1736 
1737 
1738 bool JavaThread::is_interrupted(bool clear_interrupted) {
1739   debug_only(check_for_dangling_thread_pointer(this);)
1740 
1741   if (threadObj() == NULL) {
1742     // If there is no j.l.Thread then it is impossible to have
1743     // been interrupted. We can find NULL during VM initialization
1744     // or when a JNI thread is still in the process of attaching.
1745     // In such cases this must be the current thread.
1746     assert(this == Thread::current(), "invariant");
1747     return false;
1748   }
1749 
1750   bool interrupted = java_lang_Thread::interrupted(threadObj());
1751 
1752   // NOTE that since there is no "lock" around the interrupt and
1753   // is_interrupted operations, there is the possibility that the
1754   // interrupted flag will be "false" but that the
1755   // low-level events will be in the signaled state. This is
1756   // intentional. The effect of this is that Object.wait() and
1757   // LockSupport.park() will appear to have a spurious wakeup, which
1758   // is allowed and not harmful, and the possibility is so rare that
1759   // it is not worth the added complexity to add yet another lock.
1760   // For the sleep event an explicit reset is performed on entry
1761   // to JavaThread::sleep, so there is no early return. It has also been
1762   // recommended not to put the interrupted flag into the "event"
1763   // structure because it hides the issue.
1764   // Also, because there is no lock, we must only clear the interrupt
1765   // state if we are going to report that we were interrupted; otherwise
1766   // an interrupt that happens just after we read the field would be lost.
1767   if (interrupted && clear_interrupted) {
1768     assert(this == Thread::current(), "only the current thread can clear");
1769     java_lang_Thread::set_interrupted(threadObj(), false);
1770     osthread()->set_interrupted(false);
1771   }
1772 
1773   return interrupted;
1774 }
1775 
1776 bool JavaThread::reguard_stack(address cur_sp) {
1777   if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1778       && _stack_guard_state != stack_guard_reserved_disabled) {
1779     return true; // Stack already guarded or guard pages not needed.
1780   }
1781 
1782   if (register_stack_overflow()) {
1783     // For those architectures which have separate register and
1784     // memory stacks, we must check the register stack to see if
1785     // it has overflowed.
1786     return false;
1787   }
1788 
1789   // Java code never executes within the yellow zone: the latter is only
1790   // there to provoke an exception during stack banging.  If java code
1791   // is executing there, either StackShadowPages should be larger, or
1792   // some exception code in c1, c2 or the interpreter isn't unwinding
1793   // when it should.
1794   guarantee(cur_sp > stack_reserved_zone_base(),
1795             "not enough space to reguard - increase StackShadowPages");
1796   if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1797     enable_stack_yellow_reserved_zone();
1798     if (reserved_stack_activation() != stack_base()) {
1799       set_reserved_stack_activation(stack_base());
1800     }
1801   } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1802     set_reserved_stack_activation(stack_base());
1803     enable_stack_reserved_zone();
1804   }
1805   return true;
1806 }
1807 
1808 bool JavaThread::reguard_stack(void) {
1809   return reguard_stack(os::current_stack_pointer());
1810 }
1811 
1812 void JavaThread::block_if_vm_exited() {
1813   if (_terminated == _vm_exited) {
1814     // _vm_exited is set at safepoint, and Threads_lock is never released
1815     // we will block here forever.
1816     // Here we can be doing a jump from a safe state to an unsafe state without
1817     // proper transition, but it happens after the final safepoint has begun.
1818     set_thread_state(_thread_in_vm);
1819     Threads_lock->lock();
1820     ShouldNotReachHere();
1821   }
1822 }
1823 
1824 
1825 // Remove this ifdef when C1 is ported to the compiler interface.
1826 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1827 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1828 
1829 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1830                        Thread() {
1831   initialize();
1832   _jni_attach_state = _not_attaching_via_jni;
1833   set_entry_point(entry_point);
1834   // Create the native thread itself.
1835   // %note runtime_23
1836   os::ThreadType thr_type = os::java_thread;
1837   thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1838                                                      os::java_thread;
1839   os::create_thread(this, thr_type, stack_sz);
1840   // The _osthread may be NULL here because we ran out of memory (too many threads active).
1841   // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1842   // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1843   // the exception consists of creating the exception object & initializing it, initialization
1844   // will leave the VM via a JavaCall and then all locks must be unlocked).
1845   //
1846   // The thread is still suspended when we reach here. Thread must be explicit started
1847   // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1848   // by calling Threads:add. The reason why this is not done here, is because the thread
1849   // object must be fully initialized (take a look at JVM_Start)
1850 }
1851 
1852 JavaThread::~JavaThread() {
1853 
1854   // JSR166 -- return the parker to the free list
1855   Parker::Release(_parker);
1856   _parker = NULL;
1857 
1858   // Return the sleep event to the free list
1859   ParkEvent::Release(_SleepEvent);
1860   _SleepEvent = NULL;
1861 
1862   // Free any remaining  previous UnrollBlock
1863   vframeArray* old_array = vframe_array_last();
1864 
1865   if (old_array != NULL) {
1866     Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1867     old_array->set_unroll_block(NULL);
1868     delete old_info;
1869     delete old_array;
1870   }
1871 
1872   GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1873   if (deferred != NULL) {
1874     // This can only happen if thread is destroyed before deoptimization occurs.
1875     assert(deferred->length() != 0, "empty array!");
1876     do {
1877       jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1878       deferred->remove_at(0);
1879       // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1880       delete dlv;
1881     } while (deferred->length() != 0);
1882     delete deferred;
1883   }
1884 
1885   // All Java related clean up happens in exit
1886   ThreadSafepointState::destroy(this);
1887   if (_thread_stat != NULL) delete _thread_stat;
1888 
1889 #if INCLUDE_JVMCI
1890   if (JVMCICounterSize > 0) {
1891     if (jvmci_counters_include(this)) {
1892       for (int i = 0; i < JVMCICounterSize; i++) {
1893         _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1894       }
1895     }
1896     FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1897   }
1898 #endif // INCLUDE_JVMCI
1899 }
1900 
1901 
1902 // First JavaThread specific code executed by a new Java thread.
1903 void JavaThread::pre_run() {
1904   // empty - see comments in run()
1905 }
1906 
1907 // The main routine called by a new Java thread. This isn't overridden
1908 // by subclasses, instead different subclasses define a different "entry_point"
1909 // which defines the actual logic for that kind of thread.
1910 void JavaThread::run() {
1911   // initialize thread-local alloc buffer related fields
1912   this->initialize_tlab();
1913 
1914   // Used to test validity of stack trace backs.
1915   // This can't be moved into pre_run() else we invalidate
1916   // the requirement that thread_main_inner is lower on
1917   // the stack. Consequently all the initialization logic
1918   // stays here in run() rather than pre_run().
1919   this->record_base_of_stack_pointer();
1920 
1921   this->create_stack_guard_pages();
1922 
1923   this->cache_global_variables();
1924 
1925   // Thread is now sufficiently initialized to be handled by the safepoint code as being
1926   // in the VM. Change thread state from _thread_new to _thread_in_vm
1927   ThreadStateTransition::transition(this, _thread_new, _thread_in_vm);
1928   // Before a thread is on the threads list it is always safe, so after leaving the
1929   // _thread_new we should emit a instruction barrier. The distance to modified code
1930   // from here is probably far enough, but this is consistent and safe.
1931   OrderAccess::cross_modify_fence();
1932 
1933   assert(JavaThread::current() == this, "sanity check");
1934   assert(!Thread::current()->owns_locks(), "sanity check");
1935 
1936   DTRACE_THREAD_PROBE(start, this);
1937 
1938   // This operation might block. We call that after all safepoint checks for a new thread has
1939   // been completed.
1940   this->set_active_handles(JNIHandleBlock::allocate_block());
1941 
1942   if (JvmtiExport::should_post_thread_life()) {
1943     JvmtiExport::post_thread_start(this);
1944 
1945   }
1946 
1947   // We call another function to do the rest so we are sure that the stack addresses used
1948   // from there will be lower than the stack base just computed.
1949   thread_main_inner();
1950 }
1951 
1952 void JavaThread::thread_main_inner() {
1953   assert(JavaThread::current() == this, "sanity check");
1954   assert(this->threadObj() != NULL, "just checking");
1955 
1956   // Execute thread entry point unless this thread has a pending exception
1957   // or has been stopped before starting.
1958   // Note: Due to JVM_StopThread we can have pending exceptions already!
1959   if (!this->has_pending_exception() &&
1960       !java_lang_Thread::is_stillborn(this->threadObj())) {
1961     {
1962       ResourceMark rm(this);
1963       this->set_native_thread_name(this->get_thread_name());
1964     }
1965     HandleMark hm(this);
1966     this->entry_point()(this, this);
1967   }
1968 
1969   DTRACE_THREAD_PROBE(stop, this);
1970 
1971   // Cleanup is handled in post_run()
1972 }
1973 
1974 // Shared teardown for all JavaThreads
1975 void JavaThread::post_run() {
1976   this->exit(false);
1977   // Defer deletion to here to ensure 'this' is still referenceable in call_run
1978   // for any shared tear-down.
1979   this->smr_delete();
1980 }
1981 
1982 static void ensure_join(JavaThread* thread) {
1983   // We do not need to grab the Threads_lock, since we are operating on ourself.
1984   Handle threadObj(thread, thread->threadObj());
1985   assert(threadObj.not_null(), "java thread object must exist");
1986   ObjectLocker lock(threadObj, thread);
1987   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1988   thread->clear_pending_exception();
1989   // Thread is exiting. So set thread_status field in  java.lang.Thread class to TERMINATED.
1990   java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1991   // Clear the native thread instance - this makes isAlive return false and allows the join()
1992   // to complete once we've done the notify_all below
1993   java_lang_Thread::set_thread(threadObj(), NULL);
1994   lock.notify_all(thread);
1995   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1996   thread->clear_pending_exception();
1997 }
1998 
1999 static bool is_daemon(oop threadObj) {
2000   return (threadObj != NULL && java_lang_Thread::is_daemon(threadObj));
2001 }
2002 
2003 // For any new cleanup additions, please check to see if they need to be applied to
2004 // cleanup_failed_attach_current_thread as well.
2005 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
2006   assert(this == JavaThread::current(), "thread consistency check");
2007 
2008   elapsedTimer _timer_exit_phase1;
2009   elapsedTimer _timer_exit_phase2;
2010   elapsedTimer _timer_exit_phase3;
2011   elapsedTimer _timer_exit_phase4;
2012 
2013   if (log_is_enabled(Debug, os, thread, timer)) {
2014     _timer_exit_phase1.start();
2015   }
2016 
2017   HandleMark hm(this);
2018   Handle uncaught_exception(this, this->pending_exception());
2019   this->clear_pending_exception();
2020   Handle threadObj(this, this->threadObj());
2021   assert(threadObj.not_null(), "Java thread object should be created");
2022 
2023   // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
2024   {
2025     EXCEPTION_MARK;
2026 
2027     CLEAR_PENDING_EXCEPTION;
2028   }
2029   if (!destroy_vm) {
2030     if (uncaught_exception.not_null()) {
2031       EXCEPTION_MARK;
2032       // Call method Thread.dispatchUncaughtException().
2033       Klass* thread_klass = SystemDictionary::Thread_klass();
2034       JavaValue result(T_VOID);
2035       JavaCalls::call_virtual(&result,
2036                               threadObj, thread_klass,
2037                               vmSymbols::dispatchUncaughtException_name(),
2038                               vmSymbols::throwable_void_signature(),
2039                               uncaught_exception,
2040                               THREAD);
2041       if (HAS_PENDING_EXCEPTION) {
2042         ResourceMark rm(this);
2043         jio_fprintf(defaultStream::error_stream(),
2044                     "\nException: %s thrown from the UncaughtExceptionHandler"
2045                     " in thread \"%s\"\n",
2046                     pending_exception()->klass()->external_name(),
2047                     get_thread_name());
2048         CLEAR_PENDING_EXCEPTION;
2049       }
2050     }
2051     JFR_ONLY(Jfr::on_java_thread_dismantle(this);)
2052 
2053     // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
2054     // the execution of the method. If that is not enough, then we don't really care. Thread.stop
2055     // is deprecated anyhow.
2056     if (!is_Compiler_thread()) {
2057       int count = 3;
2058       while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
2059         EXCEPTION_MARK;
2060         JavaValue result(T_VOID);
2061         Klass* thread_klass = SystemDictionary::Thread_klass();
2062         JavaCalls::call_virtual(&result,
2063                                 threadObj, thread_klass,
2064                                 vmSymbols::exit_method_name(),
2065                                 vmSymbols::void_method_signature(),
2066                                 THREAD);
2067         CLEAR_PENDING_EXCEPTION;
2068       }
2069     }
2070     // notify JVMTI
2071     if (JvmtiExport::should_post_thread_life()) {
2072       JvmtiExport::post_thread_end(this);
2073     }
2074 
2075     // We have notified the agents that we are exiting, before we go on,
2076     // we must check for a pending external suspend request and honor it
2077     // in order to not surprise the thread that made the suspend request.
2078     while (true) {
2079       {
2080         MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2081         if (!is_external_suspend()) {
2082           set_terminated(_thread_exiting);
2083           ThreadService::current_thread_exiting(this, is_daemon(threadObj()));
2084           break;
2085         }
2086         // Implied else:
2087         // Things get a little tricky here. We have a pending external
2088         // suspend request, but we are holding the SR_lock so we
2089         // can't just self-suspend. So we temporarily drop the lock
2090         // and then self-suspend.
2091       }
2092 
2093       ThreadBlockInVM tbivm(this);
2094       java_suspend_self();
2095 
2096       // We're done with this suspend request, but we have to loop around
2097       // and check again. Eventually we will get SR_lock without a pending
2098       // external suspend request and will be able to mark ourselves as
2099       // exiting.
2100     }
2101     // no more external suspends are allowed at this point
2102   } else {
2103     assert(!is_terminated() && !is_exiting(), "must not be exiting");
2104     // before_exit() has already posted JVMTI THREAD_END events
2105   }
2106 
2107   if (log_is_enabled(Debug, os, thread, timer)) {
2108     _timer_exit_phase1.stop();
2109     _timer_exit_phase2.start();
2110   }
2111 
2112   // Capture daemon status before the thread is marked as terminated.
2113   bool daemon = is_daemon(threadObj());
2114 
2115   // Notify waiters on thread object. This has to be done after exit() is called
2116   // on the thread (if the thread is the last thread in a daemon ThreadGroup the
2117   // group should have the destroyed bit set before waiters are notified).
2118   ensure_join(this);
2119   assert(!this->has_pending_exception(), "ensure_join should have cleared");
2120 
2121   if (log_is_enabled(Debug, os, thread, timer)) {
2122     _timer_exit_phase2.stop();
2123     _timer_exit_phase3.start();
2124   }
2125   // 6282335 JNI DetachCurrentThread spec states that all Java monitors
2126   // held by this thread must be released. The spec does not distinguish
2127   // between JNI-acquired and regular Java monitors. We can only see
2128   // regular Java monitors here if monitor enter-exit matching is broken.
2129   //
2130   // ensure_join() ignores IllegalThreadStateExceptions, and so does
2131   // ObjectSynchronizer::release_monitors_owned_by_thread().
2132   if (exit_type == jni_detach) {
2133     // Sanity check even though JNI DetachCurrentThread() would have
2134     // returned JNI_ERR if there was a Java frame. JavaThread exit
2135     // should be done executing Java code by the time we get here.
2136     assert(!this->has_last_Java_frame(),
2137            "should not have a Java frame when detaching or exiting");
2138     ObjectSynchronizer::release_monitors_owned_by_thread(this);
2139     assert(!this->has_pending_exception(), "release_monitors should have cleared");
2140   }
2141 
2142   // These things needs to be done while we are still a Java Thread. Make sure that thread
2143   // is in a consistent state, in case GC happens
2144   JFR_ONLY(Jfr::on_thread_exit(this);)
2145 
2146   if (active_handles() != NULL) {
2147     JNIHandleBlock* block = active_handles();
2148     set_active_handles(NULL);
2149     JNIHandleBlock::release_block(block);
2150   }
2151 
2152   if (free_handle_block() != NULL) {
2153     JNIHandleBlock* block = free_handle_block();
2154     set_free_handle_block(NULL);
2155     JNIHandleBlock::release_block(block);
2156   }
2157 
2158   // These have to be removed while this is still a valid thread.
2159   remove_stack_guard_pages();
2160 
2161   if (UseTLAB) {
2162     tlab().retire();
2163   }
2164 
2165   if (JvmtiEnv::environments_might_exist()) {
2166     JvmtiExport::cleanup_thread(this);
2167   }
2168 
2169   // We must flush any deferred card marks and other various GC barrier
2170   // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer)
2171   // before removing a thread from the list of active threads.
2172   BarrierSet::barrier_set()->on_thread_detach(this);
2173 
2174   log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
2175     exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
2176     os::current_thread_id());
2177 
2178   if (log_is_enabled(Debug, os, thread, timer)) {
2179     _timer_exit_phase3.stop();
2180     _timer_exit_phase4.start();
2181   }
2182   // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
2183   Threads::remove(this, daemon);
2184 
2185   if (log_is_enabled(Debug, os, thread, timer)) {
2186     _timer_exit_phase4.stop();
2187     ResourceMark rm(this);
2188     log_debug(os, thread, timer)("name='%s'"
2189                                  ", exit-phase1=" JLONG_FORMAT
2190                                  ", exit-phase2=" JLONG_FORMAT
2191                                  ", exit-phase3=" JLONG_FORMAT
2192                                  ", exit-phase4=" JLONG_FORMAT,
2193                                  get_thread_name(),
2194                                  _timer_exit_phase1.milliseconds(),
2195                                  _timer_exit_phase2.milliseconds(),
2196                                  _timer_exit_phase3.milliseconds(),
2197                                  _timer_exit_phase4.milliseconds());
2198   }
2199 }
2200 
2201 void JavaThread::cleanup_failed_attach_current_thread(bool is_daemon) {
2202   if (active_handles() != NULL) {
2203     JNIHandleBlock* block = active_handles();
2204     set_active_handles(NULL);
2205     JNIHandleBlock::release_block(block);
2206   }
2207 
2208   if (free_handle_block() != NULL) {
2209     JNIHandleBlock* block = free_handle_block();
2210     set_free_handle_block(NULL);
2211     JNIHandleBlock::release_block(block);
2212   }
2213 
2214   // These have to be removed while this is still a valid thread.
2215   remove_stack_guard_pages();
2216 
2217   if (UseTLAB) {
2218     tlab().retire();
2219   }
2220 
2221   BarrierSet::barrier_set()->on_thread_detach(this);
2222 
2223   Threads::remove(this, is_daemon);
2224   this->smr_delete();
2225 }
2226 
2227 JavaThread* JavaThread::active() {
2228   Thread* thread = Thread::current();
2229   if (thread->is_Java_thread()) {
2230     return (JavaThread*) thread;
2231   } else {
2232     assert(thread->is_VM_thread(), "this must be a vm thread");
2233     VM_Operation* op = ((VMThread*) thread)->vm_operation();
2234     JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2235     assert(ret->is_Java_thread(), "must be a Java thread");
2236     return ret;
2237   }
2238 }
2239 
2240 bool JavaThread::is_lock_owned(address adr) const {
2241   if (Thread::is_lock_owned(adr)) return true;
2242 
2243   for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2244     if (chunk->contains(adr)) return true;
2245   }
2246 
2247   return false;
2248 }
2249 
2250 
2251 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2252   chunk->set_next(monitor_chunks());
2253   set_monitor_chunks(chunk);
2254 }
2255 
2256 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2257   guarantee(monitor_chunks() != NULL, "must be non empty");
2258   if (monitor_chunks() == chunk) {
2259     set_monitor_chunks(chunk->next());
2260   } else {
2261     MonitorChunk* prev = monitor_chunks();
2262     while (prev->next() != chunk) prev = prev->next();
2263     prev->set_next(chunk->next());
2264   }
2265 }
2266 
2267 // JVM support.
2268 
2269 // Note: this function shouldn't block if it's called in
2270 // _thread_in_native_trans state (such as from
2271 // check_special_condition_for_native_trans()).
2272 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2273 
2274   if (has_last_Java_frame() && has_async_condition()) {
2275     // If we are at a polling page safepoint (not a poll return)
2276     // then we must defer async exception because live registers
2277     // will be clobbered by the exception path. Poll return is
2278     // ok because the call we a returning from already collides
2279     // with exception handling registers and so there is no issue.
2280     // (The exception handling path kills call result registers but
2281     //  this is ok since the exception kills the result anyway).
2282 
2283     if (is_at_poll_safepoint()) {
2284       // if the code we are returning to has deoptimized we must defer
2285       // the exception otherwise live registers get clobbered on the
2286       // exception path before deoptimization is able to retrieve them.
2287       //
2288       RegisterMap map(this, false);
2289       frame caller_fr = last_frame().sender(&map);
2290       assert(caller_fr.is_compiled_frame(), "what?");
2291       if (caller_fr.is_deoptimized_frame()) {
2292         log_info(exceptions)("deferred async exception at compiled safepoint");
2293         return;
2294       }
2295     }
2296   }
2297 
2298   JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2299   if (condition == _no_async_condition) {
2300     // Conditions have changed since has_special_runtime_exit_condition()
2301     // was called:
2302     // - if we were here only because of an external suspend request,
2303     //   then that was taken care of above (or cancelled) so we are done
2304     // - if we were here because of another async request, then it has
2305     //   been cleared between the has_special_runtime_exit_condition()
2306     //   and now so again we are done
2307     return;
2308   }
2309 
2310   // Check for pending async. exception
2311   if (_pending_async_exception != NULL) {
2312     // Only overwrite an already pending exception, if it is not a threadDeath.
2313     if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2314 
2315       // We cannot call Exceptions::_throw(...) here because we cannot block
2316       set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2317 
2318       LogTarget(Info, exceptions) lt;
2319       if (lt.is_enabled()) {
2320         ResourceMark rm;
2321         LogStream ls(lt);
2322         ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2323           if (has_last_Java_frame()) {
2324             frame f = last_frame();
2325            ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2326           }
2327         ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2328       }
2329       _pending_async_exception = NULL;
2330       clear_has_async_exception();
2331     }
2332   }
2333 
2334   if (check_unsafe_error &&
2335       condition == _async_unsafe_access_error && !has_pending_exception()) {
2336     condition = _no_async_condition;  // done
2337     switch (thread_state()) {
2338     case _thread_in_vm: {
2339       JavaThread* THREAD = this;
2340       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2341     }
2342     case _thread_in_native: {
2343       ThreadInVMfromNative tiv(this);
2344       JavaThread* THREAD = this;
2345       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2346     }
2347     case _thread_in_Java: {
2348       ThreadInVMfromJava tiv(this);
2349       JavaThread* THREAD = this;
2350       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2351     }
2352     default:
2353       ShouldNotReachHere();
2354     }
2355   }
2356 
2357   assert(condition == _no_async_condition || has_pending_exception() ||
2358          (!check_unsafe_error && condition == _async_unsafe_access_error),
2359          "must have handled the async condition, if no exception");
2360 }
2361 
2362 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2363 
2364   // Check for pending external suspend.
2365   if (is_external_suspend_with_lock()) {
2366     frame_anchor()->make_walkable(this);
2367     java_suspend_self_with_safepoint_check();
2368   }
2369 
2370   // We might be here for reasons in addition to the self-suspend request
2371   // so check for other async requests.
2372   if (check_asyncs) {
2373     check_and_handle_async_exceptions();
2374   }
2375 
2376   JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);)
2377 }
2378 
2379 void JavaThread::send_thread_stop(oop java_throwable)  {
2380   ResourceMark rm;
2381   assert(Thread::current()->is_VM_thread() || Thread::current() == this, "should be in the vm thread");
2382 
2383   // Do not throw asynchronous exceptions against the compiler thread
2384   // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2385   if (!can_call_java()) return;
2386 
2387   {
2388     // Actually throw the Throwable against the target Thread - however
2389     // only if there is no thread death exception installed already.
2390     if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2391       // If the topmost frame is a runtime stub, then we are calling into
2392       // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2393       // must deoptimize the caller before continuing, as the compiled  exception handler table
2394       // may not be valid
2395       if (has_last_Java_frame()) {
2396         frame f = last_frame();
2397         if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2398           RegisterMap reg_map(this, false);
2399           frame compiled_frame = f.sender(&reg_map);
2400           if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2401             Deoptimization::deoptimize(this, compiled_frame);
2402           }
2403         }
2404       }
2405 
2406       // Set async. pending exception in thread.
2407       set_pending_async_exception(java_throwable);
2408 
2409       if (log_is_enabled(Info, exceptions)) {
2410          ResourceMark rm;
2411         log_info(exceptions)("Pending Async. exception installed of type: %s",
2412                              InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2413       }
2414       // for AbortVMOnException flag
2415       Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2416     }
2417   }
2418 
2419 
2420   // Interrupt thread so it will wake up from a potential wait()/sleep()/park()
2421   java_lang_Thread::set_interrupted(threadObj(), true);
2422   this->interrupt();
2423 }
2424 
2425 // External suspension mechanism.
2426 //
2427 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2428 // to any VM_locks and it is at a transition
2429 // Self-suspension will happen on the transition out of the vm.
2430 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2431 //
2432 // Guarantees on return:
2433 //   + Target thread will not execute any new bytecode (that's why we need to
2434 //     force a safepoint)
2435 //   + Target thread will not enter any new monitors
2436 //
2437 void JavaThread::java_suspend() {
2438   ThreadsListHandle tlh;
2439   if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) {
2440     return;
2441   }
2442 
2443   { MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2444     if (!is_external_suspend()) {
2445       // a racing resume has cancelled us; bail out now
2446       return;
2447     }
2448 
2449     // suspend is done
2450     uint32_t debug_bits = 0;
2451     // Warning: is_ext_suspend_completed() may temporarily drop the
2452     // SR_lock to allow the thread to reach a stable thread state if
2453     // it is currently in a transient thread state.
2454     if (is_ext_suspend_completed(false /* !called_by_wait */,
2455                                  SuspendRetryDelay, &debug_bits)) {
2456       return;
2457     }
2458   }
2459 
2460   if (Thread::current() == this) {
2461     // Safely self-suspend.
2462     // If we don't do this explicitly it will implicitly happen
2463     // before we transition back to Java, and on some other thread-state
2464     // transition paths, but not as we exit a JVM TI SuspendThread call.
2465     // As SuspendThread(current) must not return (until resumed) we must
2466     // self-suspend here.
2467     ThreadBlockInVM tbivm(this);
2468     java_suspend_self();
2469   } else {
2470     VM_ThreadSuspend vm_suspend;
2471     VMThread::execute(&vm_suspend);
2472   }
2473 }
2474 
2475 // Part II of external suspension.
2476 // A JavaThread self suspends when it detects a pending external suspend
2477 // request. This is usually on transitions. It is also done in places
2478 // where continuing to the next transition would surprise the caller,
2479 // e.g., monitor entry.
2480 //
2481 // Returns the number of times that the thread self-suspended.
2482 //
2483 // Note: DO NOT call java_suspend_self() when you just want to block current
2484 //       thread. java_suspend_self() is the second stage of cooperative
2485 //       suspension for external suspend requests and should only be used
2486 //       to complete an external suspend request.
2487 //
2488 int JavaThread::java_suspend_self() {
2489   assert(thread_state() == _thread_blocked, "wrong state for java_suspend_self()");
2490   int ret = 0;
2491 
2492   // we are in the process of exiting so don't suspend
2493   if (is_exiting()) {
2494     clear_external_suspend();
2495     return ret;
2496   }
2497 
2498   assert(_anchor.walkable() ||
2499          (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2500          "must have walkable stack");
2501 
2502   MonitorLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2503 
2504   assert(!this->is_ext_suspended(),
2505          "a thread trying to self-suspend should not already be suspended");
2506 
2507   if (this->is_suspend_equivalent()) {
2508     // If we are self-suspending as a result of the lifting of a
2509     // suspend equivalent condition, then the suspend_equivalent
2510     // flag is not cleared until we set the ext_suspended flag so
2511     // that wait_for_ext_suspend_completion() returns consistent
2512     // results.
2513     this->clear_suspend_equivalent();
2514   }
2515 
2516   // A racing resume may have cancelled us before we grabbed SR_lock
2517   // above. Or another external suspend request could be waiting for us
2518   // by the time we return from SR_lock()->wait(). The thread
2519   // that requested the suspension may already be trying to walk our
2520   // stack and if we return now, we can change the stack out from under
2521   // it. This would be a "bad thing (TM)" and cause the stack walker
2522   // to crash. We stay self-suspended until there are no more pending
2523   // external suspend requests.
2524   while (is_external_suspend()) {
2525     ret++;
2526     this->set_ext_suspended();
2527 
2528     // _ext_suspended flag is cleared by java_resume()
2529     while (is_ext_suspended()) {
2530       ml.wait();
2531     }
2532   }
2533   return ret;
2534 }
2535 
2536 // Helper routine to set up the correct thread state before calling java_suspend_self.
2537 // This is called when regular thread-state transition helpers can't be used because
2538 // we can be in various states, in particular _thread_in_native_trans.
2539 // Because this thread is external suspended the safepoint code will count it as at
2540 // a safepoint, regardless of what its actual current thread-state is. But
2541 // is_ext_suspend_completed() may be waiting to see a thread transition from
2542 // _thread_in_native_trans to _thread_blocked. So we set the thread state directly
2543 // to _thread_blocked. The problem with setting thread state directly is that a
2544 // safepoint could happen just after java_suspend_self() returns after being resumed,
2545 // and the VM thread will see the _thread_blocked state. So we must check for a safepoint
2546 // after restoring the state to make sure we won't leave while a safepoint is in progress.
2547 // However, not all initial-states are allowed when performing a safepoint check, as we
2548 // should never be blocking at a safepoint whilst in those states. Of these 'bad' states
2549 // only _thread_in_native is possible when executing this code (based on our two callers).
2550 // A thread that is _thread_in_native is already safepoint-safe and so it doesn't matter
2551 // whether the VMThread sees the _thread_blocked state, or the _thread_in_native state,
2552 // and so we don't need the explicit safepoint check.
2553 
2554 void JavaThread::java_suspend_self_with_safepoint_check() {
2555   assert(this == Thread::current(), "invariant");
2556   JavaThreadState state = thread_state();
2557   set_thread_state(_thread_blocked);
2558   java_suspend_self();
2559   set_thread_state_fence(state);
2560   // Since we are not using a regular thread-state transition helper here,
2561   // we must manually emit the instruction barrier after leaving a safe state.
2562   OrderAccess::cross_modify_fence();
2563   if (state != _thread_in_native) {
2564     SafepointMechanism::block_if_requested(this);
2565   }
2566 }
2567 
2568 #ifdef ASSERT
2569 // Verify the JavaThread has not yet been published in the Threads::list, and
2570 // hence doesn't need protection from concurrent access at this stage.
2571 void JavaThread::verify_not_published() {
2572   // Cannot create a ThreadsListHandle here and check !tlh.includes(this)
2573   // since an unpublished JavaThread doesn't participate in the
2574   // Thread-SMR protocol for keeping a ThreadsList alive.
2575   assert(!on_thread_list(), "JavaThread shouldn't have been published yet!");
2576 }
2577 #endif
2578 
2579 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2580 // progress or when _suspend_flags is non-zero.
2581 // Current thread needs to self-suspend if there is a suspend request and/or
2582 // block if a safepoint is in progress.
2583 // Async exception ISN'T checked.
2584 // Note only the ThreadInVMfromNative transition can call this function
2585 // directly and when thread state is _thread_in_native_trans
2586 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2587   assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2588 
2589   assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2590 
2591   if (thread->is_external_suspend()) {
2592     thread->java_suspend_self_with_safepoint_check();
2593   } else {
2594     SafepointMechanism::block_if_requested(thread);
2595   }
2596 
2597   JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(thread);)
2598 }
2599 
2600 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2601 // progress or when _suspend_flags is non-zero.
2602 // Current thread needs to self-suspend if there is a suspend request and/or
2603 // block if a safepoint is in progress.
2604 // Also check for pending async exception (not including unsafe access error).
2605 // Note only the native==>VM/Java barriers can call this function and when
2606 // thread state is _thread_in_native_trans.
2607 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2608   check_safepoint_and_suspend_for_native_trans(thread);
2609 
2610   if (thread->has_async_exception()) {
2611     // We are in _thread_in_native_trans state, don't handle unsafe
2612     // access error since that may block.
2613     thread->check_and_handle_async_exceptions(false);
2614   }
2615 }
2616 
2617 // This is a variant of the normal
2618 // check_special_condition_for_native_trans with slightly different
2619 // semantics for use by critical native wrappers.  It does all the
2620 // normal checks but also performs the transition back into
2621 // thread_in_Java state.  This is required so that critical natives
2622 // can potentially block and perform a GC if they are the last thread
2623 // exiting the GCLocker.
2624 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2625   check_special_condition_for_native_trans(thread);
2626 
2627   // Finish the transition
2628   thread->set_thread_state(_thread_in_Java);
2629 
2630   if (thread->do_critical_native_unlock()) {
2631     ThreadInVMfromJavaNoAsyncException tiv(thread);
2632     GCLocker::unlock_critical(thread);
2633     thread->clear_critical_native_unlock();
2634   }
2635 }
2636 
2637 // We need to guarantee the Threads_lock here, since resumes are not
2638 // allowed during safepoint synchronization
2639 // Can only resume from an external suspension
2640 void JavaThread::java_resume() {
2641   assert_locked_or_safepoint(Threads_lock);
2642 
2643   // Sanity check: thread is gone, has started exiting or the thread
2644   // was not externally suspended.
2645   ThreadsListHandle tlh;
2646   if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) {
2647     return;
2648   }
2649 
2650   MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2651 
2652   clear_external_suspend();
2653 
2654   if (is_ext_suspended()) {
2655     clear_ext_suspended();
2656     SR_lock()->notify_all();
2657   }
2658 }
2659 
2660 size_t JavaThread::_stack_red_zone_size = 0;
2661 size_t JavaThread::_stack_yellow_zone_size = 0;
2662 size_t JavaThread::_stack_reserved_zone_size = 0;
2663 size_t JavaThread::_stack_shadow_zone_size = 0;
2664 
2665 void JavaThread::create_stack_guard_pages() {
2666   if (!os::uses_stack_guard_pages() ||
2667       _stack_guard_state != stack_guard_unused ||
2668       (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) {
2669       log_info(os, thread)("Stack guard page creation for thread "
2670                            UINTX_FORMAT " disabled", os::current_thread_id());
2671     return;
2672   }
2673   address low_addr = stack_end();
2674   size_t len = stack_guard_zone_size();
2675 
2676   assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2677   assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2678 
2679   int must_commit = os::must_commit_stack_guard_pages();
2680   // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2681 
2682   if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2683     log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2684     return;
2685   }
2686 
2687   if (os::guard_memory((char *) low_addr, len)) {
2688     _stack_guard_state = stack_guard_enabled;
2689   } else {
2690     log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2691       PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2692     if (os::uncommit_memory((char *) low_addr, len)) {
2693       log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2694     }
2695     return;
2696   }
2697 
2698   log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2699     PTR_FORMAT "-" PTR_FORMAT ".",
2700     os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2701 }
2702 
2703 void JavaThread::remove_stack_guard_pages() {
2704   assert(Thread::current() == this, "from different thread");
2705   if (_stack_guard_state == stack_guard_unused) return;
2706   address low_addr = stack_end();
2707   size_t len = stack_guard_zone_size();
2708 
2709   if (os::must_commit_stack_guard_pages()) {
2710     if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2711       _stack_guard_state = stack_guard_unused;
2712     } else {
2713       log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2714         PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2715       return;
2716     }
2717   } else {
2718     if (_stack_guard_state == stack_guard_unused) return;
2719     if (os::unguard_memory((char *) low_addr, len)) {
2720       _stack_guard_state = stack_guard_unused;
2721     } else {
2722       log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2723         PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2724       return;
2725     }
2726   }
2727 
2728   log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2729     PTR_FORMAT "-" PTR_FORMAT ".",
2730     os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2731 }
2732 
2733 void JavaThread::enable_stack_reserved_zone() {
2734   assert(_stack_guard_state == stack_guard_reserved_disabled, "inconsistent state");
2735 
2736   // The base notation is from the stack's point of view, growing downward.
2737   // We need to adjust it to work correctly with guard_memory()
2738   address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2739 
2740   guarantee(base < stack_base(),"Error calculating stack reserved zone");
2741   guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2742 
2743   if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2744     _stack_guard_state = stack_guard_enabled;
2745   } else {
2746     warning("Attempt to guard stack reserved zone failed.");
2747   }
2748   enable_register_stack_guard();
2749 }
2750 
2751 void JavaThread::disable_stack_reserved_zone() {
2752   assert(_stack_guard_state == stack_guard_enabled, "inconsistent state");
2753 
2754   // Simply return if called for a thread that does not use guard pages.
2755   if (_stack_guard_state != stack_guard_enabled) return;
2756 
2757   // The base notation is from the stack's point of view, growing downward.
2758   // We need to adjust it to work correctly with guard_memory()
2759   address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2760 
2761   if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2762     _stack_guard_state = stack_guard_reserved_disabled;
2763   } else {
2764     warning("Attempt to unguard stack reserved zone failed.");
2765   }
2766   disable_register_stack_guard();
2767 }
2768 
2769 void JavaThread::enable_stack_yellow_reserved_zone() {
2770   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2771   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2772 
2773   // The base notation is from the stacks point of view, growing downward.
2774   // We need to adjust it to work correctly with guard_memory()
2775   address base = stack_red_zone_base();
2776 
2777   guarantee(base < stack_base(), "Error calculating stack yellow zone");
2778   guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2779 
2780   if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2781     _stack_guard_state = stack_guard_enabled;
2782   } else {
2783     warning("Attempt to guard stack yellow zone failed.");
2784   }
2785   enable_register_stack_guard();
2786 }
2787 
2788 void JavaThread::disable_stack_yellow_reserved_zone() {
2789   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2790   assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2791 
2792   // Simply return if called for a thread that does not use guard pages.
2793   if (_stack_guard_state == stack_guard_unused) return;
2794 
2795   // The base notation is from the stacks point of view, growing downward.
2796   // We need to adjust it to work correctly with guard_memory()
2797   address base = stack_red_zone_base();
2798 
2799   if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2800     _stack_guard_state = stack_guard_yellow_reserved_disabled;
2801   } else {
2802     warning("Attempt to unguard stack yellow zone failed.");
2803   }
2804   disable_register_stack_guard();
2805 }
2806 
2807 void JavaThread::enable_stack_red_zone() {
2808   // The base notation is from the stacks point of view, growing downward.
2809   // We need to adjust it to work correctly with guard_memory()
2810   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2811   address base = stack_red_zone_base() - stack_red_zone_size();
2812 
2813   guarantee(base < stack_base(), "Error calculating stack red zone");
2814   guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2815 
2816   if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2817     warning("Attempt to guard stack red zone failed.");
2818   }
2819 }
2820 
2821 void JavaThread::disable_stack_red_zone() {
2822   // The base notation is from the stacks point of view, growing downward.
2823   // We need to adjust it to work correctly with guard_memory()
2824   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2825   address base = stack_red_zone_base() - stack_red_zone_size();
2826   if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2827     warning("Attempt to unguard stack red zone failed.");
2828   }
2829 }
2830 
2831 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2832   // ignore is there is no stack
2833   if (!has_last_Java_frame()) return;
2834   // traverse the stack frames. Starts from top frame.
2835   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2836     frame* fr = fst.current();
2837     f(fr, fst.register_map());
2838   }
2839 }
2840 
2841 
2842 #ifndef PRODUCT
2843 // Deoptimization
2844 // Function for testing deoptimization
2845 void JavaThread::deoptimize() {
2846   StackFrameStream fst(this, false);
2847   bool deopt = false;           // Dump stack only if a deopt actually happens.
2848   bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2849   // Iterate over all frames in the thread and deoptimize
2850   for (; !fst.is_done(); fst.next()) {
2851     if (fst.current()->can_be_deoptimized()) {
2852 
2853       if (only_at) {
2854         // Deoptimize only at particular bcis.  DeoptimizeOnlyAt
2855         // consists of comma or carriage return separated numbers so
2856         // search for the current bci in that string.
2857         address pc = fst.current()->pc();
2858         nmethod* nm =  (nmethod*) fst.current()->cb();
2859         ScopeDesc* sd = nm->scope_desc_at(pc);
2860         char buffer[8];
2861         jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2862         size_t len = strlen(buffer);
2863         const char * found = strstr(DeoptimizeOnlyAt, buffer);
2864         while (found != NULL) {
2865           if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2866               (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2867             // Check that the bci found is bracketed by terminators.
2868             break;
2869           }
2870           found = strstr(found + 1, buffer);
2871         }
2872         if (!found) {
2873           continue;
2874         }
2875       }
2876 
2877       if (DebugDeoptimization && !deopt) {
2878         deopt = true; // One-time only print before deopt
2879         tty->print_cr("[BEFORE Deoptimization]");
2880         trace_frames();
2881         trace_stack();
2882       }
2883       Deoptimization::deoptimize(this, *fst.current());
2884     }
2885   }
2886 
2887   if (DebugDeoptimization && deopt) {
2888     tty->print_cr("[AFTER Deoptimization]");
2889     trace_frames();
2890   }
2891 }
2892 
2893 
2894 // Make zombies
2895 void JavaThread::make_zombies() {
2896   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2897     if (fst.current()->can_be_deoptimized()) {
2898       // it is a Java nmethod
2899       nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2900       nm->make_not_entrant();
2901     }
2902   }
2903 }
2904 #endif // PRODUCT
2905 
2906 
2907 void JavaThread::deoptimize_marked_methods() {
2908   if (!has_last_Java_frame()) return;
2909   StackFrameStream fst(this, false);
2910   for (; !fst.is_done(); fst.next()) {
2911     if (fst.current()->should_be_deoptimized()) {
2912       Deoptimization::deoptimize(this, *fst.current());
2913     }
2914   }
2915 }
2916 
2917 // If the caller is a NamedThread, then remember, in the current scope,
2918 // the given JavaThread in its _processed_thread field.
2919 class RememberProcessedThread: public StackObj {
2920   NamedThread* _cur_thr;
2921  public:
2922   RememberProcessedThread(JavaThread* jthr) {
2923     Thread* thread = Thread::current();
2924     if (thread->is_Named_thread()) {
2925       _cur_thr = (NamedThread *)thread;
2926       _cur_thr->set_processed_thread(jthr);
2927     } else {
2928       _cur_thr = NULL;
2929     }
2930   }
2931 
2932   ~RememberProcessedThread() {
2933     if (_cur_thr) {
2934       _cur_thr->set_processed_thread(NULL);
2935     }
2936   }
2937 };
2938 
2939 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2940   // Verify that the deferred card marks have been flushed.
2941   assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2942 
2943   // Traverse the GCHandles
2944   Thread::oops_do(f, cf);
2945 
2946   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2947          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2948 
2949   if (has_last_Java_frame()) {
2950     // Record JavaThread to GC thread
2951     RememberProcessedThread rpt(this);
2952 
2953     // traverse the registered growable array
2954     if (_array_for_gc != NULL) {
2955       for (int index = 0; index < _array_for_gc->length(); index++) {
2956         f->do_oop(_array_for_gc->adr_at(index));
2957       }
2958     }
2959 
2960     // Traverse the monitor chunks
2961     for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2962       chunk->oops_do(f);
2963     }
2964 
2965     // Traverse the execution stack
2966     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2967       fst.current()->oops_do(f, cf, fst.register_map());
2968     }
2969   }
2970 
2971   assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2972   // If we have deferred set_locals there might be oops waiting to be
2973   // written
2974   GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2975   if (list != NULL) {
2976     for (int i = 0; i < list->length(); i++) {
2977       list->at(i)->oops_do(f);
2978     }
2979   }
2980 
2981   // Traverse instance variables at the end since the GC may be moving things
2982   // around using this function
2983   f->do_oop((oop*) &_threadObj);
2984   f->do_oop((oop*) &_vm_result);
2985   f->do_oop((oop*) &_exception_oop);
2986   f->do_oop((oop*) &_pending_async_exception);
2987 
2988   if (jvmti_thread_state() != NULL) {
2989     jvmti_thread_state()->oops_do(f, cf);
2990   }
2991 }
2992 
2993 #ifdef ASSERT
2994 void JavaThread::verify_states_for_handshake() {
2995   // This checks that the thread has a correct frame state during a handshake.
2996   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2997          (has_last_Java_frame() && java_call_counter() > 0),
2998          "unexpected frame info: has_last_frame=%d, java_call_counter=%d",
2999          has_last_Java_frame(), java_call_counter());
3000 }
3001 #endif
3002 
3003 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
3004   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
3005          (has_last_Java_frame() && java_call_counter() > 0),
3006          "unexpected frame info: has_last_frame=%d, java_call_counter=%d",
3007          has_last_Java_frame(), java_call_counter());
3008 
3009   if (has_last_Java_frame()) {
3010     // Traverse the execution stack
3011     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3012       fst.current()->nmethods_do(cf);
3013     }
3014   }
3015 
3016   if (jvmti_thread_state() != NULL) {
3017     jvmti_thread_state()->nmethods_do(cf);
3018   }
3019 }
3020 
3021 void JavaThread::metadata_do(MetadataClosure* f) {
3022   if (has_last_Java_frame()) {
3023     // Traverse the execution stack to call f() on the methods in the stack
3024     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3025       fst.current()->metadata_do(f);
3026     }
3027   } else if (is_Compiler_thread()) {
3028     // need to walk ciMetadata in current compile tasks to keep alive.
3029     CompilerThread* ct = (CompilerThread*)this;
3030     if (ct->env() != NULL) {
3031       ct->env()->metadata_do(f);
3032     }
3033     CompileTask* task = ct->task();
3034     if (task != NULL) {
3035       task->metadata_do(f);
3036     }
3037   }
3038 }
3039 
3040 // Printing
3041 const char* _get_thread_state_name(JavaThreadState _thread_state) {
3042   switch (_thread_state) {
3043   case _thread_uninitialized:     return "_thread_uninitialized";
3044   case _thread_new:               return "_thread_new";
3045   case _thread_new_trans:         return "_thread_new_trans";
3046   case _thread_in_native:         return "_thread_in_native";
3047   case _thread_in_native_trans:   return "_thread_in_native_trans";
3048   case _thread_in_vm:             return "_thread_in_vm";
3049   case _thread_in_vm_trans:       return "_thread_in_vm_trans";
3050   case _thread_in_Java:           return "_thread_in_Java";
3051   case _thread_in_Java_trans:     return "_thread_in_Java_trans";
3052   case _thread_blocked:           return "_thread_blocked";
3053   case _thread_blocked_trans:     return "_thread_blocked_trans";
3054   default:                        return "unknown thread state";
3055   }
3056 }
3057 
3058 #ifndef PRODUCT
3059 void JavaThread::print_thread_state_on(outputStream *st) const {
3060   st->print_cr("   JavaThread state: %s", _get_thread_state_name(_thread_state));
3061 };
3062 #endif // PRODUCT
3063 
3064 // Called by Threads::print() for VM_PrintThreads operation
3065 void JavaThread::print_on(outputStream *st, bool print_extended_info) const {
3066   st->print_raw("\"");
3067   st->print_raw(get_thread_name());
3068   st->print_raw("\" ");
3069   oop thread_oop = threadObj();
3070   if (thread_oop != NULL) {
3071     st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
3072     if (java_lang_Thread::is_daemon(thread_oop))  st->print("daemon ");
3073     st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
3074   }
3075   Thread::print_on(st, print_extended_info);
3076   // print guess for valid stack memory region (assume 4K pages); helps lock debugging
3077   st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
3078   if (thread_oop != NULL) {
3079     st->print_cr("   java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
3080   }
3081 #ifndef PRODUCT
3082   _safepoint_state->print_on(st);
3083 #endif // PRODUCT
3084   if (is_Compiler_thread()) {
3085     CompileTask *task = ((CompilerThread*)this)->task();
3086     if (task != NULL) {
3087       st->print("   Compiling: ");
3088       task->print(st, NULL, true, false);
3089     } else {
3090       st->print("   No compile task");
3091     }
3092     st->cr();
3093   }
3094 }
3095 
3096 void JavaThread::print() const { print_on(tty); }
3097 
3098 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
3099   st->print("%s", get_thread_name_string(buf, buflen));
3100 }
3101 
3102 // Called by fatal error handler. The difference between this and
3103 // JavaThread::print() is that we can't grab lock or allocate memory.
3104 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
3105   st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
3106   oop thread_obj = threadObj();
3107   if (thread_obj != NULL) {
3108     if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
3109   }
3110   st->print(" [");
3111   st->print("%s", _get_thread_state_name(_thread_state));
3112   if (osthread()) {
3113     st->print(", id=%d", osthread()->thread_id());
3114   }
3115   st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
3116             p2i(stack_end()), p2i(stack_base()));
3117   st->print("]");
3118 
3119   ThreadsSMRSupport::print_info_on(this, st);
3120   return;
3121 }
3122 
3123 // Verification
3124 
3125 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
3126 
3127 void JavaThread::verify() {
3128   // Verify oops in the thread.
3129   oops_do(&VerifyOopClosure::verify_oop, NULL);
3130 
3131   // Verify the stack frames.
3132   frames_do(frame_verify);
3133 }
3134 
3135 // CR 6300358 (sub-CR 2137150)
3136 // Most callers of this method assume that it can't return NULL but a
3137 // thread may not have a name whilst it is in the process of attaching to
3138 // the VM - see CR 6412693, and there are places where a JavaThread can be
3139 // seen prior to having it's threadObj set (eg JNI attaching threads and
3140 // if vm exit occurs during initialization). These cases can all be accounted
3141 // for such that this method never returns NULL.
3142 const char* JavaThread::get_thread_name() const {
3143 #ifdef ASSERT
3144   // early safepoints can hit while current thread does not yet have TLS
3145   if (!SafepointSynchronize::is_at_safepoint()) {
3146     Thread *cur = Thread::current();
3147     if (!(cur->is_Java_thread() && cur == this)) {
3148       // Current JavaThreads are allowed to get their own name without
3149       // the Threads_lock.
3150       assert_locked_or_safepoint_or_handshake(Threads_lock, this);
3151     }
3152   }
3153 #endif // ASSERT
3154   return get_thread_name_string();
3155 }
3156 
3157 // Returns a non-NULL representation of this thread's name, or a suitable
3158 // descriptive string if there is no set name
3159 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3160   const char* name_str;
3161   oop thread_obj = threadObj();
3162   if (thread_obj != NULL) {
3163     oop name = java_lang_Thread::name(thread_obj);
3164     if (name != NULL) {
3165       if (buf == NULL) {
3166         name_str = java_lang_String::as_utf8_string(name);
3167       } else {
3168         name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3169       }
3170     } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3171       name_str = "<no-name - thread is attaching>";
3172     } else {
3173       name_str = Thread::name();
3174     }
3175   } else {
3176     name_str = Thread::name();
3177   }
3178   assert(name_str != NULL, "unexpected NULL thread name");
3179   return name_str;
3180 }
3181 
3182 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3183 
3184   assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3185   assert(NoPriority <= prio && prio <= MaxPriority, "sanity check");
3186   // Link Java Thread object <-> C++ Thread
3187 
3188   // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3189   // and put it into a new Handle.  The Handle "thread_oop" can then
3190   // be used to pass the C++ thread object to other methods.
3191 
3192   // Set the Java level thread object (jthread) field of the
3193   // new thread (a JavaThread *) to C++ thread object using the
3194   // "thread_oop" handle.
3195 
3196   // Set the thread field (a JavaThread *) of the
3197   // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3198 
3199   Handle thread_oop(Thread::current(),
3200                     JNIHandles::resolve_non_null(jni_thread));
3201   assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3202          "must be initialized");
3203   set_threadObj(thread_oop());
3204   java_lang_Thread::set_thread(thread_oop(), this);
3205 
3206   if (prio == NoPriority) {
3207     prio = java_lang_Thread::priority(thread_oop());
3208     assert(prio != NoPriority, "A valid priority should be present");
3209   }
3210 
3211   // Push the Java priority down to the native thread; needs Threads_lock
3212   Thread::set_priority(this, prio);
3213 
3214   // Add the new thread to the Threads list and set it in motion.
3215   // We must have threads lock in order to call Threads::add.
3216   // It is crucial that we do not block before the thread is
3217   // added to the Threads list for if a GC happens, then the java_thread oop
3218   // will not be visited by GC.
3219   Threads::add(this);
3220 }
3221 
3222 oop JavaThread::current_park_blocker() {
3223   // Support for JSR-166 locks
3224   oop thread_oop = threadObj();
3225   if (thread_oop != NULL) {
3226     return java_lang_Thread::park_blocker(thread_oop);
3227   }
3228   return NULL;
3229 }
3230 
3231 
3232 void JavaThread::print_stack_on(outputStream* st) {
3233   if (!has_last_Java_frame()) return;
3234   ResourceMark rm;
3235   HandleMark   hm;
3236 
3237   RegisterMap reg_map(this);
3238   vframe* start_vf = last_java_vframe(&reg_map);
3239   int count = 0;
3240   for (vframe* f = start_vf; f != NULL; f = f->sender()) {
3241     if (f->is_java_frame()) {
3242       javaVFrame* jvf = javaVFrame::cast(f);
3243       java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3244 
3245       // Print out lock information
3246       if (JavaMonitorsInStackTrace) {
3247         jvf->print_lock_info_on(st, count);
3248       }
3249     } else {
3250       // Ignore non-Java frames
3251     }
3252 
3253     // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
3254     count++;
3255     if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
3256   }
3257 }
3258 
3259 
3260 // JVMTI PopFrame support
3261 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3262   assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3263   if (in_bytes(size_in_bytes) != 0) {
3264     _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3265     _popframe_preserved_args_size = in_bytes(size_in_bytes);
3266     Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3267   }
3268 }
3269 
3270 void* JavaThread::popframe_preserved_args() {
3271   return _popframe_preserved_args;
3272 }
3273 
3274 ByteSize JavaThread::popframe_preserved_args_size() {
3275   return in_ByteSize(_popframe_preserved_args_size);
3276 }
3277 
3278 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3279   int sz = in_bytes(popframe_preserved_args_size());
3280   assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3281   return in_WordSize(sz / wordSize);
3282 }
3283 
3284 void JavaThread::popframe_free_preserved_args() {
3285   assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3286   FREE_C_HEAP_ARRAY(char, (char*)_popframe_preserved_args);
3287   _popframe_preserved_args = NULL;
3288   _popframe_preserved_args_size = 0;
3289 }
3290 
3291 #ifndef PRODUCT
3292 
3293 void JavaThread::trace_frames() {
3294   tty->print_cr("[Describe stack]");
3295   int frame_no = 1;
3296   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3297     tty->print("  %d. ", frame_no++);
3298     fst.current()->print_value_on(tty, this);
3299     tty->cr();
3300   }
3301 }
3302 
3303 class PrintAndVerifyOopClosure: public OopClosure {
3304  protected:
3305   template <class T> inline void do_oop_work(T* p) {
3306     oop obj = RawAccess<>::oop_load(p);
3307     if (obj == NULL) return;
3308     tty->print(INTPTR_FORMAT ": ", p2i(p));
3309     if (oopDesc::is_oop_or_null(obj)) {
3310       if (obj->is_objArray()) {
3311         tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3312       } else {
3313         obj->print();
3314       }
3315     } else {
3316       tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3317     }
3318     tty->cr();
3319   }
3320  public:
3321   virtual void do_oop(oop* p) { do_oop_work(p); }
3322   virtual void do_oop(narrowOop* p)  { do_oop_work(p); }
3323 };
3324 
3325 #ifdef ASSERT
3326 // Print or validate the layout of stack frames
3327 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3328   ResourceMark rm;
3329   PRESERVE_EXCEPTION_MARK;
3330   FrameValues values;
3331   int frame_no = 0;
3332   for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3333     fst.current()->describe(values, ++frame_no);
3334     if (depth == frame_no) break;
3335   }
3336   if (validate_only) {
3337     values.validate();
3338   } else {
3339     tty->print_cr("[Describe stack layout]");
3340     values.print(this);
3341   }
3342 }
3343 #endif
3344 
3345 void JavaThread::trace_stack_from(vframe* start_vf) {
3346   ResourceMark rm;
3347   int vframe_no = 1;
3348   for (vframe* f = start_vf; f; f = f->sender()) {
3349     if (f->is_java_frame()) {
3350       javaVFrame::cast(f)->print_activation(vframe_no++);
3351     } else {
3352       f->print();
3353     }
3354     if (vframe_no > StackPrintLimit) {
3355       tty->print_cr("...<more frames>...");
3356       return;
3357     }
3358   }
3359 }
3360 
3361 
3362 void JavaThread::trace_stack() {
3363   if (!has_last_Java_frame()) return;
3364   ResourceMark rm;
3365   HandleMark   hm;
3366   RegisterMap reg_map(this);
3367   trace_stack_from(last_java_vframe(&reg_map));
3368 }
3369 
3370 
3371 #endif // PRODUCT
3372 
3373 
3374 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3375   assert(reg_map != NULL, "a map must be given");
3376   frame f = last_frame();
3377   for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3378     if (vf->is_java_frame()) return javaVFrame::cast(vf);
3379   }
3380   return NULL;
3381 }
3382 
3383 
3384 Klass* JavaThread::security_get_caller_class(int depth) {
3385   vframeStream vfst(this);
3386   vfst.security_get_caller_frame(depth);
3387   if (!vfst.at_end()) {
3388     return vfst.method()->method_holder();
3389   }
3390   return NULL;
3391 }
3392 
3393 // java.lang.Thread.sleep support
3394 // Returns true if sleep time elapsed as expected, and false
3395 // if the thread was interrupted.
3396 bool JavaThread::sleep(jlong millis) {
3397   assert(this == Thread::current(),  "thread consistency check");
3398 
3399   ParkEvent * const slp = this->_SleepEvent;
3400   // Because there can be races with thread interruption sending an unpark()
3401   // to the event, we explicitly reset it here to avoid an immediate return.
3402   // The actual interrupt state will be checked before we park().
3403   slp->reset();
3404   // Thread interruption establishes a happens-before ordering in the
3405   // Java Memory Model, so we need to ensure we synchronize with the
3406   // interrupt state.
3407   OrderAccess::fence();
3408 
3409   jlong prevtime = os::javaTimeNanos();
3410 
3411   for (;;) {
3412     // interruption has precedence over timing out
3413     if (this->is_interrupted(true)) {
3414       return false;
3415     }
3416 
3417     if (millis <= 0) {
3418       return true;
3419     }
3420 
3421     {
3422       ThreadBlockInVM tbivm(this);
3423       OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
3424 
3425       this->set_suspend_equivalent();
3426       // cleared by handle_special_suspend_equivalent_condition() or
3427       // java_suspend_self() via check_and_wait_while_suspended()
3428 
3429       slp->park(millis);
3430 
3431       // were we externally suspended while we were waiting?
3432       this->check_and_wait_while_suspended();
3433     }
3434 
3435     // Update elapsed time tracking
3436     jlong newtime = os::javaTimeNanos();
3437     if (newtime - prevtime < 0) {
3438       // time moving backwards, should only happen if no monotonic clock
3439       // not a guarantee() because JVM should not abort on kernel/glibc bugs
3440       assert(!os::supports_monotonic_clock(),
3441              "unexpected time moving backwards detected in JavaThread::sleep()");
3442     } else {
3443       millis -= (newtime - prevtime) / NANOSECS_PER_MILLISEC;
3444     }
3445     prevtime = newtime;
3446   }
3447 }
3448 
3449 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3450   assert(thread->is_Compiler_thread(), "must be compiler thread");
3451   CompileBroker::compiler_thread_loop();
3452 }
3453 
3454 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3455   NMethodSweeper::sweeper_loop();
3456 }
3457 
3458 // Create a CompilerThread
3459 CompilerThread::CompilerThread(CompileQueue* queue,
3460                                CompilerCounters* counters)
3461                                : JavaThread(&compiler_thread_entry) {
3462   _env   = NULL;
3463   _log   = NULL;
3464   _task  = NULL;
3465   _queue = queue;
3466   _counters = counters;
3467   _buffer_blob = NULL;
3468   _compiler = NULL;
3469 
3470   // Compiler uses resource area for compilation, let's bias it to mtCompiler
3471   resource_area()->bias_to(mtCompiler);
3472 
3473 #ifndef PRODUCT
3474   _ideal_graph_printer = NULL;
3475 #endif
3476 }
3477 
3478 CompilerThread::~CompilerThread() {
3479   // Delete objects which were allocated on heap.
3480   delete _counters;
3481 }
3482 
3483 bool CompilerThread::can_call_java() const {
3484   return _compiler != NULL && _compiler->is_jvmci();
3485 }
3486 
3487 // Create sweeper thread
3488 CodeCacheSweeperThread::CodeCacheSweeperThread()
3489 : JavaThread(&sweeper_thread_entry) {
3490   _scanned_compiled_method = NULL;
3491 }
3492 
3493 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3494   JavaThread::oops_do(f, cf);
3495   if (_scanned_compiled_method != NULL && cf != NULL) {
3496     // Safepoints can occur when the sweeper is scanning an nmethod so
3497     // process it here to make sure it isn't unloaded in the middle of
3498     // a scan.
3499     cf->do_code_blob(_scanned_compiled_method);
3500   }
3501 }
3502 
3503 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3504   JavaThread::nmethods_do(cf);
3505   if (_scanned_compiled_method != NULL && cf != NULL) {
3506     // Safepoints can occur when the sweeper is scanning an nmethod so
3507     // process it here to make sure it isn't unloaded in the middle of
3508     // a scan.
3509     cf->do_code_blob(_scanned_compiled_method);
3510   }
3511 }
3512 
3513 
3514 // ======= Threads ========
3515 
3516 // The Threads class links together all active threads, and provides
3517 // operations over all threads. It is protected by the Threads_lock,
3518 // which is also used in other global contexts like safepointing.
3519 // ThreadsListHandles are used to safely perform operations on one
3520 // or more threads without the risk of the thread exiting during the
3521 // operation.
3522 //
3523 // Note: The Threads_lock is currently more widely used than we
3524 // would like. We are actively migrating Threads_lock uses to other
3525 // mechanisms in order to reduce Threads_lock contention.
3526 
3527 int         Threads::_number_of_threads = 0;
3528 int         Threads::_number_of_non_daemon_threads = 0;
3529 int         Threads::_return_code = 0;
3530 uintx       Threads::_thread_claim_token = 1; // Never zero.
3531 size_t      JavaThread::_stack_size_at_create = 0;
3532 
3533 #ifdef ASSERT
3534 bool        Threads::_vm_complete = false;
3535 #endif
3536 
3537 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
3538   Prefetch::read((void*)addr, prefetch_interval);
3539   return *addr;
3540 }
3541 
3542 // Possibly the ugliest for loop the world has seen. C++ does not allow
3543 // multiple types in the declaration section of the for loop. In this case
3544 // we are only dealing with pointers and hence can cast them. It looks ugly
3545 // but macros are ugly and therefore it's fine to make things absurdly ugly.
3546 #define DO_JAVA_THREADS(LIST, X)                                                                                          \
3547     for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes,                           \
3548              *MACRO_list = (JavaThread*)(LIST),                                                                           \
3549              **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(),  \
3550              **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(),                                     \
3551              *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval);                 \
3552          MACRO_current_p != MACRO_end;                                                                                    \
3553          MACRO_current_p++,                                                                                               \
3554              X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval))
3555 
3556 // All JavaThreads
3557 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X)
3558 
3559 // All NonJavaThreads (i.e., every non-JavaThread in the system).
3560 void Threads::non_java_threads_do(ThreadClosure* tc) {
3561   NoSafepointVerifier nsv;
3562   for (NonJavaThread::Iterator njti; !njti.end(); njti.step()) {
3563     tc->do_thread(njti.current());
3564   }
3565 }
3566 
3567 // All JavaThreads
3568 void Threads::java_threads_do(ThreadClosure* tc) {
3569   assert_locked_or_safepoint(Threads_lock);
3570   // ALL_JAVA_THREADS iterates through all JavaThreads.
3571   ALL_JAVA_THREADS(p) {
3572     tc->do_thread(p);
3573   }
3574 }
3575 
3576 void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) {
3577   assert_locked_or_safepoint(Threads_lock);
3578   java_threads_do(tc);
3579   tc->do_thread(VMThread::vm_thread());
3580 }
3581 
3582 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system).
3583 void Threads::threads_do(ThreadClosure* tc) {
3584   assert_locked_or_safepoint(Threads_lock);
3585   java_threads_do(tc);
3586   non_java_threads_do(tc);
3587 }
3588 
3589 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
3590   uintx claim_token = Threads::thread_claim_token();
3591   ALL_JAVA_THREADS(p) {
3592     if (p->claim_threads_do(is_par, claim_token)) {
3593       tc->do_thread(p);
3594     }
3595   }
3596   VMThread* vmt = VMThread::vm_thread();
3597   if (vmt->claim_threads_do(is_par, claim_token)) {
3598     tc->do_thread(vmt);
3599   }
3600 }
3601 
3602 // The system initialization in the library has three phases.
3603 //
3604 // Phase 1: java.lang.System class initialization
3605 //     java.lang.System is a primordial class loaded and initialized
3606 //     by the VM early during startup.  java.lang.System.<clinit>
3607 //     only does registerNatives and keeps the rest of the class
3608 //     initialization work later until thread initialization completes.
3609 //
3610 //     System.initPhase1 initializes the system properties, the static
3611 //     fields in, out, and err. Set up java signal handlers, OS-specific
3612 //     system settings, and thread group of the main thread.
3613 static void call_initPhase1(TRAPS) {
3614   Klass* klass = SystemDictionary::System_klass();
3615   JavaValue result(T_VOID);
3616   JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3617                                          vmSymbols::void_method_signature(), CHECK);
3618 }
3619 
3620 // Phase 2. Module system initialization
3621 //     This will initialize the module system.  Only java.base classes
3622 //     can be loaded until phase 2 completes.
3623 //
3624 //     Call System.initPhase2 after the compiler initialization and jsr292
3625 //     classes get initialized because module initialization runs a lot of java
3626 //     code, that for performance reasons, should be compiled.  Also, this will
3627 //     enable the startup code to use lambda and other language features in this
3628 //     phase and onward.
3629 //
3630 //     After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3631 static void call_initPhase2(TRAPS) {
3632   TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3633 
3634   Klass* klass = SystemDictionary::System_klass();
3635 
3636   JavaValue result(T_INT);
3637   JavaCallArguments args;
3638   args.push_int(DisplayVMOutputToStderr);
3639   args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3640   JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3641                                          vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3642   if (result.get_jint() != JNI_OK) {
3643     vm_exit_during_initialization(); // no message or exception
3644   }
3645 
3646   universe_post_module_init();
3647 }
3648 
3649 // Phase 3. final setup - set security manager, system class loader and TCCL
3650 //
3651 //     This will instantiate and set the security manager, set the system class
3652 //     loader as well as the thread context class loader.  The security manager
3653 //     and system class loader may be a custom class loaded from -Xbootclasspath/a,
3654 //     other modules or the application's classpath.
3655 static void call_initPhase3(TRAPS) {
3656   Klass* klass = SystemDictionary::System_klass();
3657   JavaValue result(T_VOID);
3658   JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3659                                          vmSymbols::void_method_signature(), CHECK);
3660 }
3661 
3662 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3663   TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3664 
3665   if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3666     create_vm_init_libraries();
3667   }
3668 
3669   initialize_class(vmSymbols::java_lang_String(), CHECK);
3670 
3671   // Inject CompactStrings value after the static initializers for String ran.
3672   java_lang_String::set_compact_strings(CompactStrings);
3673 
3674   // Initialize java_lang.System (needed before creating the thread)
3675   initialize_class(vmSymbols::java_lang_System(), CHECK);
3676   // The VM creates & returns objects of this class. Make sure it's initialized.
3677   initialize_class(vmSymbols::java_lang_Class(), CHECK);
3678   initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3679   Handle thread_group = create_initial_thread_group(CHECK);
3680   Universe::set_main_thread_group(thread_group());
3681   initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3682   oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3683   main_thread->set_threadObj(thread_object);
3684 
3685   // Set thread status to running since main thread has
3686   // been started and running.
3687   java_lang_Thread::set_thread_status(thread_object,
3688                                       java_lang_Thread::RUNNABLE);
3689 
3690   // The VM creates objects of this class.
3691   initialize_class(vmSymbols::java_lang_Module(), CHECK);
3692 
3693 #ifdef ASSERT
3694   InstanceKlass *k = SystemDictionary::UnsafeConstants_klass();
3695   assert(k->is_not_initialized(), "UnsafeConstants should not already be initialized");
3696 #endif
3697 
3698   // initialize the hardware-specific constants needed by Unsafe
3699   initialize_class(vmSymbols::jdk_internal_misc_UnsafeConstants(), CHECK);
3700   jdk_internal_misc_UnsafeConstants::set_unsafe_constants();
3701 
3702   // The VM preresolves methods to these classes. Make sure that they get initialized
3703   initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3704   initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3705 
3706   // Phase 1 of the system initialization in the library, java.lang.System class initialization
3707   call_initPhase1(CHECK);
3708 
3709   // get the Java runtime name, version, and vendor info after java.lang.System is initialized
3710   JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3711   JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3712   JDK_Version::set_runtime_vendor_version(get_java_runtime_vendor_version(THREAD));
3713   JDK_Version::set_runtime_vendor_vm_bug_url(get_java_runtime_vendor_vm_bug_url(THREAD));
3714 
3715   // an instance of OutOfMemory exception has been allocated earlier
3716   initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3717   initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3718   initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3719   initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3720   initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3721   initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3722   initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3723   initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3724 
3725   // Eager box cache initialization only if AOT is on and any library is loaded.
3726   AOTLoader::initialize_box_caches(CHECK);
3727 }
3728 
3729 void Threads::initialize_jsr292_core_classes(TRAPS) {
3730   TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3731 
3732   initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3733   initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3734   initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3735   initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3736 }
3737 
3738 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3739   extern void JDK_Version_init();
3740 
3741   // Preinitialize version info.
3742   VM_Version::early_initialize();
3743 
3744   // Check version
3745   if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3746 
3747   // Initialize library-based TLS
3748   ThreadLocalStorage::init();
3749 
3750   // Initialize the output stream module
3751   ostream_init();
3752 
3753   // Process java launcher properties.
3754   Arguments::process_sun_java_launcher_properties(args);
3755 
3756   // Initialize the os module
3757   os::init();
3758 
3759   // Record VM creation timing statistics
3760   TraceVmCreationTime create_vm_timer;
3761   create_vm_timer.start();
3762 
3763   // Initialize system properties.
3764   Arguments::init_system_properties();
3765 
3766   // So that JDK version can be used as a discriminator when parsing arguments
3767   JDK_Version_init();
3768 
3769   // Update/Initialize System properties after JDK version number is known
3770   Arguments::init_version_specific_system_properties();
3771 
3772   // Make sure to initialize log configuration *before* parsing arguments
3773   LogConfiguration::initialize(create_vm_timer.begin_time());
3774 
3775   // Parse arguments
3776   // Note: this internally calls os::init_container_support()
3777   jint parse_result = Arguments::parse(args);
3778   if (parse_result != JNI_OK) return parse_result;
3779 
3780   os::init_before_ergo();
3781 
3782   jint ergo_result = Arguments::apply_ergo();
3783   if (ergo_result != JNI_OK) return ergo_result;
3784 
3785   // Final check of all ranges after ergonomics which may change values.
3786   if (!JVMFlag::check_all_ranges()) {
3787     return JNI_EINVAL;
3788   }
3789 
3790   // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3791   bool constraint_result = JVMFlag::check_all_constraints(JVMFlag::AfterErgo);
3792   if (!constraint_result) {
3793     return JNI_EINVAL;
3794   }
3795 
3796   if (PauseAtStartup) {
3797     os::pause();
3798   }
3799 
3800   HOTSPOT_VM_INIT_BEGIN();
3801 
3802   // Timing (must come after argument parsing)
3803   TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3804 
3805   // Initialize the os module after parsing the args
3806   jint os_init_2_result = os::init_2();
3807   if (os_init_2_result != JNI_OK) return os_init_2_result;
3808 
3809 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT
3810   // Initialize assert poison page mechanism.
3811   if (ShowRegistersOnAssert) {
3812     initialize_assert_poison();
3813   }
3814 #endif // CAN_SHOW_REGISTERS_ON_ASSERT
3815 
3816   SafepointMechanism::initialize();
3817 
3818   jint adjust_after_os_result = Arguments::adjust_after_os();
3819   if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3820 
3821   // Initialize output stream logging
3822   ostream_init_log();
3823 
3824   // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3825   // Must be before create_vm_init_agents()
3826   if (Arguments::init_libraries_at_startup()) {
3827     convert_vm_init_libraries_to_agents();
3828   }
3829 
3830   // Launch -agentlib/-agentpath and converted -Xrun agents
3831   if (Arguments::init_agents_at_startup()) {
3832     create_vm_init_agents();
3833   }
3834 
3835   // Initialize Threads state
3836   _number_of_threads = 0;
3837   _number_of_non_daemon_threads = 0;
3838 
3839   // Initialize global data structures and create system classes in heap
3840   vm_init_globals();
3841 
3842 #if INCLUDE_JVMCI
3843   if (JVMCICounterSize > 0) {
3844     JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtJVMCI);
3845     memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3846   } else {
3847     JavaThread::_jvmci_old_thread_counters = NULL;
3848   }
3849 #endif // INCLUDE_JVMCI
3850 
3851   // Attach the main thread to this os thread
3852   JavaThread* main_thread = new JavaThread();
3853   main_thread->set_thread_state(_thread_in_vm);
3854   main_thread->initialize_thread_current();
3855   // must do this before set_active_handles
3856   main_thread->record_stack_base_and_size();
3857   main_thread->register_thread_stack_with_NMT();
3858   main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3859 
3860   if (!main_thread->set_as_starting_thread()) {
3861     vm_shutdown_during_initialization(
3862                                       "Failed necessary internal allocation. Out of swap space");
3863     main_thread->smr_delete();
3864     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3865     return JNI_ENOMEM;
3866   }
3867 
3868   // Enable guard page *after* os::create_main_thread(), otherwise it would
3869   // crash Linux VM, see notes in os_linux.cpp.
3870   main_thread->create_stack_guard_pages();
3871 
3872   // Initialize Java-Level synchronization subsystem
3873   ObjectMonitor::Initialize();
3874 
3875   // Initialize global modules
3876   jint status = init_globals();
3877   if (status != JNI_OK) {
3878     main_thread->smr_delete();
3879     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3880     return status;
3881   }
3882 
3883   JFR_ONLY(Jfr::on_create_vm_1();)
3884 
3885   // Should be done after the heap is fully created
3886   main_thread->cache_global_variables();
3887 
3888   HandleMark hm;
3889 
3890   { MutexLocker mu(Threads_lock);
3891     Threads::add(main_thread);
3892   }
3893 
3894   // Any JVMTI raw monitors entered in onload will transition into
3895   // real raw monitor. VM is setup enough here for raw monitor enter.
3896   JvmtiExport::transition_pending_onload_raw_monitors();
3897 
3898   // Create the VMThread
3899   { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3900 
3901     VMThread::create();
3902     Thread* vmthread = VMThread::vm_thread();
3903 
3904     if (!os::create_thread(vmthread, os::vm_thread)) {
3905       vm_exit_during_initialization("Cannot create VM thread. "
3906                                     "Out of system resources.");
3907     }
3908 
3909     // Wait for the VM thread to become ready, and VMThread::run to initialize
3910     // Monitors can have spurious returns, must always check another state flag
3911     {
3912       MonitorLocker ml(Notify_lock);
3913       os::start_thread(vmthread);
3914       while (vmthread->active_handles() == NULL) {
3915         ml.wait();
3916       }
3917     }
3918   }
3919 
3920   assert(Universe::is_fully_initialized(), "not initialized");
3921   if (VerifyDuringStartup) {
3922     // Make sure we're starting with a clean slate.
3923     VM_Verify verify_op;
3924     VMThread::execute(&verify_op);
3925   }
3926 
3927   // We need this to update the java.vm.info property in case any flags used
3928   // to initially define it have been changed. This is needed for both CDS and
3929   // AOT, since UseSharedSpaces and UseAOT may be changed after java.vm.info
3930   // is initially computed. See Abstract_VM_Version::vm_info_string().
3931   // This update must happen before we initialize the java classes, but
3932   // after any initialization logic that might modify the flags.
3933   Arguments::update_vm_info_property(VM_Version::vm_info_string());
3934 
3935   Thread* THREAD = Thread::current();
3936 
3937   // Always call even when there are not JVMTI environments yet, since environments
3938   // may be attached late and JVMTI must track phases of VM execution
3939   JvmtiExport::enter_early_start_phase();
3940 
3941   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3942   JvmtiExport::post_early_vm_start();
3943 
3944   initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3945 
3946   quicken_jni_functions();
3947 
3948   // No more stub generation allowed after that point.
3949   StubCodeDesc::freeze();
3950 
3951   // Set flag that basic initialization has completed. Used by exceptions and various
3952   // debug stuff, that does not work until all basic classes have been initialized.
3953   set_init_completed();
3954 
3955   LogConfiguration::post_initialize();
3956   Metaspace::post_initialize();
3957 
3958   HOTSPOT_VM_INIT_END();
3959 
3960   // record VM initialization completion time
3961 #if INCLUDE_MANAGEMENT
3962   Management::record_vm_init_completed();
3963 #endif // INCLUDE_MANAGEMENT
3964 
3965   // Signal Dispatcher needs to be started before VMInit event is posted
3966   os::initialize_jdk_signal_support(CHECK_JNI_ERR);
3967 
3968   // Start Attach Listener if +StartAttachListener or it can't be started lazily
3969   if (!DisableAttachMechanism) {
3970     AttachListener::vm_start();
3971     if (StartAttachListener || AttachListener::init_at_startup()) {
3972       AttachListener::init();
3973     }
3974   }
3975 
3976   // Launch -Xrun agents
3977   // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3978   // back-end can launch with -Xdebug -Xrunjdwp.
3979   if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3980     create_vm_init_libraries();
3981   }
3982 
3983   if (CleanChunkPoolAsync) {
3984     Chunk::start_chunk_pool_cleaner_task();
3985   }
3986 
3987   // Start the service thread
3988   // The service thread enqueues JVMTI deferred events and does various hashtable
3989   // and other cleanups.  Needs to start before the compilers start posting events.
3990   ServiceThread::initialize();
3991 
3992   // initialize compiler(s)
3993 #if defined(COMPILER1) || COMPILER2_OR_JVMCI
3994 #if INCLUDE_JVMCI
3995   bool force_JVMCI_intialization = false;
3996   if (EnableJVMCI) {
3997     // Initialize JVMCI eagerly when it is explicitly requested.
3998     // Or when JVMCILibDumpJNIConfig or JVMCIPrintProperties is enabled.
3999     force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties || JVMCILibDumpJNIConfig;
4000 
4001     if (!force_JVMCI_intialization) {
4002       // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
4003       // compilations via JVMCI will not actually block until JVMCI is initialized.
4004       force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
4005     }
4006   }
4007 #endif
4008   CompileBroker::compilation_init_phase1(CHECK_JNI_ERR);
4009   // Postpone completion of compiler initialization to after JVMCI
4010   // is initialized to avoid timeouts of blocking compilations.
4011   if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) {
4012     CompileBroker::compilation_init_phase2();
4013   }
4014 #endif
4015 
4016   // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
4017   // It is done after compilers are initialized, because otherwise compilations of
4018   // signature polymorphic MH intrinsics can be missed
4019   // (see SystemDictionary::find_method_handle_intrinsic).
4020   initialize_jsr292_core_classes(CHECK_JNI_ERR);
4021 
4022   // This will initialize the module system.  Only java.base classes can be
4023   // loaded until phase 2 completes
4024   call_initPhase2(CHECK_JNI_ERR);
4025 
4026   JFR_ONLY(Jfr::on_create_vm_2();)
4027 
4028   // Always call even when there are not JVMTI environments yet, since environments
4029   // may be attached late and JVMTI must track phases of VM execution
4030   JvmtiExport::enter_start_phase();
4031 
4032   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
4033   JvmtiExport::post_vm_start();
4034 
4035   // Final system initialization including security manager and system class loader
4036   call_initPhase3(CHECK_JNI_ERR);
4037 
4038   // cache the system and platform class loaders
4039   SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
4040 
4041 #if INCLUDE_CDS
4042   // capture the module path info from the ModuleEntryTable
4043   ClassLoader::initialize_module_path(THREAD);
4044 #endif
4045 
4046 #if INCLUDE_JVMCI
4047   if (force_JVMCI_intialization) {
4048     JVMCI::initialize_compiler(CHECK_JNI_ERR);
4049     CompileBroker::compilation_init_phase2();
4050   }
4051 #endif
4052 
4053   // Always call even when there are not JVMTI environments yet, since environments
4054   // may be attached late and JVMTI must track phases of VM execution
4055   JvmtiExport::enter_live_phase();
4056 
4057   // Make perfmemory accessible
4058   PerfMemory::set_accessible(true);
4059 
4060   // Notify JVMTI agents that VM initialization is complete - nop if no agents.
4061   JvmtiExport::post_vm_initialized();
4062 
4063   JFR_ONLY(Jfr::on_create_vm_3();)
4064 
4065 #if INCLUDE_MANAGEMENT
4066   Management::initialize(THREAD);
4067 
4068   if (HAS_PENDING_EXCEPTION) {
4069     // management agent fails to start possibly due to
4070     // configuration problem and is responsible for printing
4071     // stack trace if appropriate. Simply exit VM.
4072     vm_exit(1);
4073   }
4074 #endif // INCLUDE_MANAGEMENT
4075 
4076   if (MemProfiling)                   MemProfiler::engage();
4077   StatSampler::engage();
4078   if (CheckJNICalls)                  JniPeriodicChecker::engage();
4079 
4080   BiasedLocking::init();
4081 
4082 #if INCLUDE_RTM_OPT
4083   RTMLockingCounters::init();
4084 #endif
4085 
4086   call_postVMInitHook(THREAD);
4087   // The Java side of PostVMInitHook.run must deal with all
4088   // exceptions and provide means of diagnosis.
4089   if (HAS_PENDING_EXCEPTION) {
4090     CLEAR_PENDING_EXCEPTION;
4091   }
4092 
4093   {
4094     MutexLocker ml(PeriodicTask_lock);
4095     // Make sure the WatcherThread can be started by WatcherThread::start()
4096     // or by dynamic enrollment.
4097     WatcherThread::make_startable();
4098     // Start up the WatcherThread if there are any periodic tasks
4099     // NOTE:  All PeriodicTasks should be registered by now. If they
4100     //   aren't, late joiners might appear to start slowly (we might
4101     //   take a while to process their first tick).
4102     if (PeriodicTask::num_tasks() > 0) {
4103       WatcherThread::start();
4104     }
4105   }
4106 
4107   create_vm_timer.end();
4108 #ifdef ASSERT
4109   _vm_complete = true;
4110 #endif
4111 
4112   if (DumpSharedSpaces) {
4113     MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
4114     ShouldNotReachHere();
4115   }
4116 
4117   return JNI_OK;
4118 }
4119 
4120 // type for the Agent_OnLoad and JVM_OnLoad entry points
4121 extern "C" {
4122   typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
4123 }
4124 // Find a command line agent library and return its entry point for
4125 //         -agentlib:  -agentpath:   -Xrun
4126 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
4127 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
4128                                     const char *on_load_symbols[],
4129                                     size_t num_symbol_entries) {
4130   OnLoadEntry_t on_load_entry = NULL;
4131   void *library = NULL;
4132 
4133   if (!agent->valid()) {
4134     char buffer[JVM_MAXPATHLEN];
4135     char ebuf[1024] = "";
4136     const char *name = agent->name();
4137     const char *msg = "Could not find agent library ";
4138 
4139     // First check to see if agent is statically linked into executable
4140     if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
4141       library = agent->os_lib();
4142     } else if (agent->is_absolute_path()) {
4143       library = os::dll_load(name, ebuf, sizeof ebuf);
4144       if (library == NULL) {
4145         const char *sub_msg = " in absolute path, with error: ";
4146         size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
4147         char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4148         jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4149         // If we can't find the agent, exit.
4150         vm_exit_during_initialization(buf, NULL);
4151         FREE_C_HEAP_ARRAY(char, buf);
4152       }
4153     } else {
4154       // Try to load the agent from the standard dll directory
4155       if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
4156                              name)) {
4157         library = os::dll_load(buffer, ebuf, sizeof ebuf);
4158       }
4159       if (library == NULL) { // Try the library path directory.
4160         if (os::dll_build_name(buffer, sizeof(buffer), name)) {
4161           library = os::dll_load(buffer, ebuf, sizeof ebuf);
4162         }
4163         if (library == NULL) {
4164           const char *sub_msg = " on the library path, with error: ";
4165           const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image.";
4166 
4167           size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) +
4168                        strlen(ebuf) + strlen(sub_msg2) + 1;
4169           char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4170           if (!agent->is_instrument_lib()) {
4171             jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4172           } else {
4173             jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2);
4174           }
4175           // If we can't find the agent, exit.
4176           vm_exit_during_initialization(buf, NULL);
4177           FREE_C_HEAP_ARRAY(char, buf);
4178         }
4179       }
4180     }
4181     agent->set_os_lib(library);
4182     agent->set_valid();
4183   }
4184 
4185   // Find the OnLoad function.
4186   on_load_entry =
4187     CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
4188                                                           false,
4189                                                           on_load_symbols,
4190                                                           num_symbol_entries));
4191   return on_load_entry;
4192 }
4193 
4194 // Find the JVM_OnLoad entry point
4195 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
4196   const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
4197   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4198 }
4199 
4200 // Find the Agent_OnLoad entry point
4201 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
4202   const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
4203   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4204 }
4205 
4206 // For backwards compatibility with -Xrun
4207 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
4208 // treated like -agentpath:
4209 // Must be called before agent libraries are created
4210 void Threads::convert_vm_init_libraries_to_agents() {
4211   AgentLibrary* agent;
4212   AgentLibrary* next;
4213 
4214   for (agent = Arguments::libraries(); agent != NULL; agent = next) {
4215     next = agent->next();  // cache the next agent now as this agent may get moved off this list
4216     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4217 
4218     // If there is an JVM_OnLoad function it will get called later,
4219     // otherwise see if there is an Agent_OnLoad
4220     if (on_load_entry == NULL) {
4221       on_load_entry = lookup_agent_on_load(agent);
4222       if (on_load_entry != NULL) {
4223         // switch it to the agent list -- so that Agent_OnLoad will be called,
4224         // JVM_OnLoad won't be attempted and Agent_OnUnload will
4225         Arguments::convert_library_to_agent(agent);
4226       } else {
4227         vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
4228       }
4229     }
4230   }
4231 }
4232 
4233 // Create agents for -agentlib:  -agentpath:  and converted -Xrun
4234 // Invokes Agent_OnLoad
4235 // Called very early -- before JavaThreads exist
4236 void Threads::create_vm_init_agents() {
4237   extern struct JavaVM_ main_vm;
4238   AgentLibrary* agent;
4239 
4240   JvmtiExport::enter_onload_phase();
4241 
4242   for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4243     // CDS dumping does not support native JVMTI agent.
4244     // CDS dumping supports Java agent if the AllowArchivingWithJavaAgent diagnostic option is specified.
4245     if (Arguments::is_dumping_archive()) {
4246       if(!agent->is_instrument_lib()) {
4247         vm_exit_during_cds_dumping("CDS dumping does not support native JVMTI agent, name", agent->name());
4248       } else if (!AllowArchivingWithJavaAgent) {
4249         vm_exit_during_cds_dumping(
4250           "Must enable AllowArchivingWithJavaAgent in order to run Java agent during CDS dumping");
4251       }
4252     }
4253 
4254     OnLoadEntry_t  on_load_entry = lookup_agent_on_load(agent);
4255 
4256     if (on_load_entry != NULL) {
4257       // Invoke the Agent_OnLoad function
4258       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4259       if (err != JNI_OK) {
4260         vm_exit_during_initialization("agent library failed to init", agent->name());
4261       }
4262     } else {
4263       vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4264     }
4265   }
4266 
4267   JvmtiExport::enter_primordial_phase();
4268 }
4269 
4270 extern "C" {
4271   typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4272 }
4273 
4274 void Threads::shutdown_vm_agents() {
4275   // Send any Agent_OnUnload notifications
4276   const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4277   size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4278   extern struct JavaVM_ main_vm;
4279   for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4280 
4281     // Find the Agent_OnUnload function.
4282     Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4283                                                    os::find_agent_function(agent,
4284                                                    false,
4285                                                    on_unload_symbols,
4286                                                    num_symbol_entries));
4287 
4288     // Invoke the Agent_OnUnload function
4289     if (unload_entry != NULL) {
4290       JavaThread* thread = JavaThread::current();
4291       ThreadToNativeFromVM ttn(thread);
4292       HandleMark hm(thread);
4293       (*unload_entry)(&main_vm);
4294     }
4295   }
4296 }
4297 
4298 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4299 // Invokes JVM_OnLoad
4300 void Threads::create_vm_init_libraries() {
4301   extern struct JavaVM_ main_vm;
4302   AgentLibrary* agent;
4303 
4304   for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4305     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4306 
4307     if (on_load_entry != NULL) {
4308       // Invoke the JVM_OnLoad function
4309       JavaThread* thread = JavaThread::current();
4310       ThreadToNativeFromVM ttn(thread);
4311       HandleMark hm(thread);
4312       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4313       if (err != JNI_OK) {
4314         vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4315       }
4316     } else {
4317       vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4318     }
4319   }
4320 }
4321 
4322 
4323 // Last thread running calls java.lang.Shutdown.shutdown()
4324 void JavaThread::invoke_shutdown_hooks() {
4325   HandleMark hm(this);
4326 
4327   // Link all classes for dynamic CDS dumping before vm exit.
4328   // Same operation is being done in JVM_BeforeHalt for handling the
4329   // case where the application calls System.exit().
4330   if (DynamicDumpSharedSpaces) {
4331     MetaspaceShared::link_and_cleanup_shared_classes(this);
4332   }
4333 
4334   // We could get here with a pending exception, if so clear it now.
4335   if (this->has_pending_exception()) {
4336     this->clear_pending_exception();
4337   }
4338 
4339   EXCEPTION_MARK;
4340   Klass* shutdown_klass =
4341     SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4342                                       THREAD);
4343   if (shutdown_klass != NULL) {
4344     // SystemDictionary::resolve_or_null will return null if there was
4345     // an exception.  If we cannot load the Shutdown class, just don't
4346     // call Shutdown.shutdown() at all.  This will mean the shutdown hooks
4347     // won't be run.  Note that if a shutdown hook was registered,
4348     // the Shutdown class would have already been loaded
4349     // (Runtime.addShutdownHook will load it).
4350     JavaValue result(T_VOID);
4351     JavaCalls::call_static(&result,
4352                            shutdown_klass,
4353                            vmSymbols::shutdown_name(),
4354                            vmSymbols::void_method_signature(),
4355                            THREAD);
4356   }
4357   CLEAR_PENDING_EXCEPTION;
4358 }
4359 
4360 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4361 // the program falls off the end of main(). Another VM exit path is through
4362 // vm_exit() when the program calls System.exit() to return a value or when
4363 // there is a serious error in VM. The two shutdown paths are not exactly
4364 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4365 // and VM_Exit op at VM level.
4366 //
4367 // Shutdown sequence:
4368 //   + Shutdown native memory tracking if it is on
4369 //   + Wait until we are the last non-daemon thread to execute
4370 //     <-- every thing is still working at this moment -->
4371 //   + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4372 //        shutdown hooks
4373 //   + Call before_exit(), prepare for VM exit
4374 //      > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4375 //        currently the only user of this mechanism is File.deleteOnExit())
4376 //      > stop StatSampler, watcher thread,
4377 //        post thread end and vm death events to JVMTI,
4378 //        stop signal thread
4379 //   + Call JavaThread::exit(), it will:
4380 //      > release JNI handle blocks, remove stack guard pages
4381 //      > remove this thread from Threads list
4382 //     <-- no more Java code from this thread after this point -->
4383 //   + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4384 //     the compiler threads at safepoint
4385 //     <-- do not use anything that could get blocked by Safepoint -->
4386 //   + Disable tracing at JNI/JVM barriers
4387 //   + Set _vm_exited flag for threads that are still running native code
4388 //   + Call exit_globals()
4389 //      > deletes tty
4390 //      > deletes PerfMemory resources
4391 //   + Delete this thread
4392 //   + Return to caller
4393 
4394 bool Threads::destroy_vm() {
4395   JavaThread* thread = JavaThread::current();
4396 
4397 #ifdef ASSERT
4398   _vm_complete = false;
4399 #endif
4400   // Wait until we are the last non-daemon thread to execute
4401   { MonitorLocker nu(Threads_lock);
4402     while (Threads::number_of_non_daemon_threads() > 1)
4403       // This wait should make safepoint checks, wait without a timeout,
4404       // and wait as a suspend-equivalent condition.
4405       nu.wait(0, Mutex::_as_suspend_equivalent_flag);
4406   }
4407 
4408   EventShutdown e;
4409   if (e.should_commit()) {
4410     e.set_reason("No remaining non-daemon Java threads");
4411     e.commit();
4412   }
4413 
4414   // Hang forever on exit if we are reporting an error.
4415   if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4416     os::infinite_sleep();
4417   }
4418   os::wait_for_keypress_at_exit();
4419 
4420   // run Java level shutdown hooks
4421   thread->invoke_shutdown_hooks();
4422 
4423   before_exit(thread);
4424 
4425   thread->exit(true);
4426 
4427   // Stop VM thread.
4428   {
4429     // 4945125 The vm thread comes to a safepoint during exit.
4430     // GC vm_operations can get caught at the safepoint, and the
4431     // heap is unparseable if they are caught. Grab the Heap_lock
4432     // to prevent this. The GC vm_operations will not be able to
4433     // queue until after the vm thread is dead. After this point,
4434     // we'll never emerge out of the safepoint before the VM exits.
4435 
4436     MutexLocker ml(Heap_lock, Mutex::_no_safepoint_check_flag);
4437 
4438     VMThread::wait_for_vm_thread_exit();
4439     assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4440     VMThread::destroy();
4441   }
4442 
4443   // Now, all Java threads are gone except daemon threads. Daemon threads
4444   // running Java code or in VM are stopped by the Safepoint. However,
4445   // daemon threads executing native code are still running.  But they
4446   // will be stopped at native=>Java/VM barriers. Note that we can't
4447   // simply kill or suspend them, as it is inherently deadlock-prone.
4448 
4449   VM_Exit::set_vm_exited();
4450 
4451   // Clean up ideal graph printers after the VMThread has started
4452   // the final safepoint which will block all the Compiler threads.
4453   // Note that this Thread has already logically exited so the
4454   // clean_up() function's use of a JavaThreadIteratorWithHandle
4455   // would be a problem except set_vm_exited() has remembered the
4456   // shutdown thread which is granted a policy exception.
4457 #if defined(COMPILER2) && !defined(PRODUCT)
4458   IdealGraphPrinter::clean_up();
4459 #endif
4460 
4461   notify_vm_shutdown();
4462 
4463   // exit_globals() will delete tty
4464   exit_globals();
4465 
4466   // We are after VM_Exit::set_vm_exited() so we can't call
4467   // thread->smr_delete() or we will block on the Threads_lock.
4468   // Deleting the shutdown thread here is safe because another
4469   // JavaThread cannot have an active ThreadsListHandle for
4470   // this JavaThread.
4471   delete thread;
4472 
4473 #if INCLUDE_JVMCI
4474   if (JVMCICounterSize > 0) {
4475     FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4476   }
4477 #endif
4478 
4479   LogConfiguration::finalize();
4480 
4481   return true;
4482 }
4483 
4484 
4485 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4486   if (version == JNI_VERSION_1_1) return JNI_TRUE;
4487   return is_supported_jni_version(version);
4488 }
4489 
4490 
4491 jboolean Threads::is_supported_jni_version(jint version) {
4492   if (version == JNI_VERSION_1_2) return JNI_TRUE;
4493   if (version == JNI_VERSION_1_4) return JNI_TRUE;
4494   if (version == JNI_VERSION_1_6) return JNI_TRUE;
4495   if (version == JNI_VERSION_1_8) return JNI_TRUE;
4496   if (version == JNI_VERSION_9) return JNI_TRUE;
4497   if (version == JNI_VERSION_10) return JNI_TRUE;
4498   return JNI_FALSE;
4499 }
4500 
4501 
4502 void Threads::add(JavaThread* p, bool force_daemon) {
4503   // The threads lock must be owned at this point
4504   assert(Threads_lock->owned_by_self(), "must have threads lock");
4505 
4506   BarrierSet::barrier_set()->on_thread_attach(p);
4507 
4508   // Once a JavaThread is added to the Threads list, smr_delete() has
4509   // to be used to delete it. Otherwise we can just delete it directly.
4510   p->set_on_thread_list();
4511 
4512   _number_of_threads++;
4513   oop threadObj = p->threadObj();
4514   bool daemon = true;
4515   // Bootstrapping problem: threadObj can be null for initial
4516   // JavaThread (or for threads attached via JNI)
4517   if ((!force_daemon) && !is_daemon((threadObj))) {
4518     _number_of_non_daemon_threads++;
4519     daemon = false;
4520   }
4521 
4522   ThreadService::add_thread(p, daemon);
4523 
4524   // Maintain fast thread list
4525   ThreadsSMRSupport::add_thread(p);
4526 
4527   // Possible GC point.
4528   Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4529 }
4530 
4531 void Threads::remove(JavaThread* p, bool is_daemon) {
4532 
4533   // Reclaim the ObjectMonitors from the om_in_use_list and om_free_list of the moribund thread.
4534   ObjectSynchronizer::om_flush(p);
4535 
4536   // Extra scope needed for Thread_lock, so we can check
4537   // that we do not remove thread without safepoint code notice
4538   { MonitorLocker ml(Threads_lock);
4539 
4540     assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present");
4541 
4542     // Maintain fast thread list
4543     ThreadsSMRSupport::remove_thread(p);
4544 
4545     _number_of_threads--;
4546     if (!is_daemon) {
4547       _number_of_non_daemon_threads--;
4548 
4549       // Only one thread left, do a notify on the Threads_lock so a thread waiting
4550       // on destroy_vm will wake up.
4551       if (number_of_non_daemon_threads() == 1) {
4552         ml.notify_all();
4553       }
4554     }
4555     ThreadService::remove_thread(p, is_daemon);
4556 
4557     // Make sure that safepoint code disregard this thread. This is needed since
4558     // the thread might mess around with locks after this point. This can cause it
4559     // to do callbacks into the safepoint code. However, the safepoint code is not aware
4560     // of this thread since it is removed from the queue.
4561     p->set_terminated_value();
4562   } // unlock Threads_lock
4563 
4564   // Since Events::log uses a lock, we grab it outside the Threads_lock
4565   Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4566 }
4567 
4568 // Operations on the Threads list for GC.  These are not explicitly locked,
4569 // but the garbage collector must provide a safe context for them to run.
4570 // In particular, these things should never be called when the Threads_lock
4571 // is held by some other thread. (Note: the Safepoint abstraction also
4572 // uses the Threads_lock to guarantee this property. It also makes sure that
4573 // all threads gets blocked when exiting or starting).
4574 
4575 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4576   ALL_JAVA_THREADS(p) {
4577     p->oops_do(f, cf);
4578   }
4579   VMThread::vm_thread()->oops_do(f, cf);
4580 }
4581 
4582 void Threads::change_thread_claim_token() {
4583   if (++_thread_claim_token == 0) {
4584     // On overflow of the token counter, there is a risk of future
4585     // collisions between a new global token value and a stale token
4586     // for a thread, because not all iterations visit all threads.
4587     // (Though it's pretty much a theoretical concern for non-trivial
4588     // token counter sizes.)  To deal with the possibility, reset all
4589     // the thread tokens to zero on global token overflow.
4590     struct ResetClaims : public ThreadClosure {
4591       virtual void do_thread(Thread* t) {
4592         t->claim_threads_do(false, 0);
4593       }
4594     } reset_claims;
4595     Threads::threads_do(&reset_claims);
4596     // On overflow, update the global token to non-zero, to
4597     // avoid the special "never claimed" initial thread value.
4598     _thread_claim_token = 1;
4599   }
4600 }
4601 
4602 #ifdef ASSERT
4603 void assert_thread_claimed(const char* kind, Thread* t, uintx expected) {
4604   const uintx token = t->threads_do_token();
4605   assert(token == expected,
4606          "%s " PTR_FORMAT " has incorrect value " UINTX_FORMAT " != "
4607          UINTX_FORMAT, kind, p2i(t), token, expected);
4608 }
4609 
4610 void Threads::assert_all_threads_claimed() {
4611   ALL_JAVA_THREADS(p) {
4612     assert_thread_claimed("Thread", p, _thread_claim_token);
4613   }
4614   assert_thread_claimed("VMThread", VMThread::vm_thread(), _thread_claim_token);
4615 }
4616 #endif // ASSERT
4617 
4618 class ParallelOopsDoThreadClosure : public ThreadClosure {
4619 private:
4620   OopClosure* _f;
4621   CodeBlobClosure* _cf;
4622 public:
4623   ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {}
4624   void do_thread(Thread* t) {
4625     t->oops_do(_f, _cf);
4626   }
4627 };
4628 
4629 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4630   ParallelOopsDoThreadClosure tc(f, cf);
4631   possibly_parallel_threads_do(is_par, &tc);
4632 }
4633 
4634 void Threads::nmethods_do(CodeBlobClosure* cf) {
4635   ALL_JAVA_THREADS(p) {
4636     // This is used by the code cache sweeper to mark nmethods that are active
4637     // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4638     // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4639     if(!p->is_Code_cache_sweeper_thread()) {
4640       p->nmethods_do(cf);
4641     }
4642   }
4643 }
4644 
4645 void Threads::metadata_do(MetadataClosure* f) {
4646   ALL_JAVA_THREADS(p) {
4647     p->metadata_do(f);
4648   }
4649 }
4650 
4651 class ThreadHandlesClosure : public ThreadClosure {
4652   void (*_f)(Metadata*);
4653  public:
4654   ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4655   virtual void do_thread(Thread* thread) {
4656     thread->metadata_handles_do(_f);
4657   }
4658 };
4659 
4660 void Threads::metadata_handles_do(void f(Metadata*)) {
4661   // Only walk the Handles in Thread.
4662   ThreadHandlesClosure handles_closure(f);
4663   threads_do(&handles_closure);
4664 }
4665 
4666 // Get count Java threads that are waiting to enter the specified monitor.
4667 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
4668                                                          int count,
4669                                                          address monitor) {
4670   GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4671 
4672   int i = 0;
4673   DO_JAVA_THREADS(t_list, p) {
4674     if (!p->can_call_java()) continue;
4675 
4676     address pending = (address)p->current_pending_monitor();
4677     if (pending == monitor) {             // found a match
4678       if (i < count) result->append(p);   // save the first count matches
4679       i++;
4680     }
4681   }
4682 
4683   return result;
4684 }
4685 
4686 
4687 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
4688                                                       address owner) {
4689   // NULL owner means not locked so we can skip the search
4690   if (owner == NULL) return NULL;
4691 
4692   DO_JAVA_THREADS(t_list, p) {
4693     // first, see if owner is the address of a Java thread
4694     if (owner == (address)p) return p;
4695   }
4696 
4697   // Cannot assert on lack of success here since this function may be
4698   // used by code that is trying to report useful problem information
4699   // like deadlock detection.
4700   if (UseHeavyMonitors) return NULL;
4701 
4702   // If we didn't find a matching Java thread and we didn't force use of
4703   // heavyweight monitors, then the owner is the stack address of the
4704   // Lock Word in the owning Java thread's stack.
4705   //
4706   JavaThread* the_owner = NULL;
4707   DO_JAVA_THREADS(t_list, q) {
4708     if (q->is_lock_owned(owner)) {
4709       the_owner = q;
4710       break;
4711     }
4712   }
4713 
4714   // cannot assert on lack of success here; see above comment
4715   return the_owner;
4716 }
4717 
4718 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4719 void Threads::print_on(outputStream* st, bool print_stacks,
4720                        bool internal_format, bool print_concurrent_locks,
4721                        bool print_extended_info) {
4722   char buf[32];
4723   st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4724 
4725   st->print_cr("Full thread dump %s (%s %s):",
4726                VM_Version::vm_name(),
4727                VM_Version::vm_release(),
4728                VM_Version::vm_info_string());
4729   st->cr();
4730 
4731 #if INCLUDE_SERVICES
4732   // Dump concurrent locks
4733   ConcurrentLocksDump concurrent_locks;
4734   if (print_concurrent_locks) {
4735     concurrent_locks.dump_at_safepoint();
4736   }
4737 #endif // INCLUDE_SERVICES
4738 
4739   ThreadsSMRSupport::print_info_on(st);
4740   st->cr();
4741 
4742   ALL_JAVA_THREADS(p) {
4743     ResourceMark rm;
4744     p->print_on(st, print_extended_info);
4745     if (print_stacks) {
4746       if (internal_format) {
4747         p->trace_stack();
4748       } else {
4749         p->print_stack_on(st);
4750       }
4751     }
4752     st->cr();
4753 #if INCLUDE_SERVICES
4754     if (print_concurrent_locks) {
4755       concurrent_locks.print_locks_on(p, st);
4756     }
4757 #endif // INCLUDE_SERVICES
4758   }
4759 
4760   VMThread::vm_thread()->print_on(st);
4761   st->cr();
4762   Universe::heap()->print_gc_threads_on(st);
4763   WatcherThread* wt = WatcherThread::watcher_thread();
4764   if (wt != NULL) {
4765     wt->print_on(st);
4766     st->cr();
4767   }
4768 
4769   st->flush();
4770 }
4771 
4772 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4773                              int buflen, bool* found_current) {
4774   if (this_thread != NULL) {
4775     bool is_current = (current == this_thread);
4776     *found_current = *found_current || is_current;
4777     st->print("%s", is_current ? "=>" : "  ");
4778 
4779     st->print(PTR_FORMAT, p2i(this_thread));
4780     st->print(" ");
4781     this_thread->print_on_error(st, buf, buflen);
4782     st->cr();
4783   }
4784 }
4785 
4786 class PrintOnErrorClosure : public ThreadClosure {
4787   outputStream* _st;
4788   Thread* _current;
4789   char* _buf;
4790   int _buflen;
4791   bool* _found_current;
4792  public:
4793   PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4794                       int buflen, bool* found_current) :
4795    _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4796 
4797   virtual void do_thread(Thread* thread) {
4798     Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4799   }
4800 };
4801 
4802 // Threads::print_on_error() is called by fatal error handler. It's possible
4803 // that VM is not at safepoint and/or current thread is inside signal handler.
4804 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4805 // memory (even in resource area), it might deadlock the error handler.
4806 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4807                              int buflen) {
4808   ThreadsSMRSupport::print_info_on(st);
4809   st->cr();
4810 
4811   bool found_current = false;
4812   st->print_cr("Java Threads: ( => current thread )");
4813   ALL_JAVA_THREADS(thread) {
4814     print_on_error(thread, st, current, buf, buflen, &found_current);
4815   }
4816   st->cr();
4817 
4818   st->print_cr("Other Threads:");
4819   print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4820   print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4821 
4822   PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4823   Universe::heap()->gc_threads_do(&print_closure);
4824 
4825   if (!found_current) {
4826     st->cr();
4827     st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4828     current->print_on_error(st, buf, buflen);
4829     st->cr();
4830   }
4831   st->cr();
4832 
4833   st->print_cr("Threads with active compile tasks:");
4834   print_threads_compiling(st, buf, buflen);
4835 }
4836 
4837 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen, bool short_form) {
4838   ALL_JAVA_THREADS(thread) {
4839     if (thread->is_Compiler_thread()) {
4840       CompilerThread* ct = (CompilerThread*) thread;
4841 
4842       // Keep task in local variable for NULL check.
4843       // ct->_task might be set to NULL by concurring compiler thread
4844       // because it completed the compilation. The task is never freed,
4845       // though, just returned to a free list.
4846       CompileTask* task = ct->task();
4847       if (task != NULL) {
4848         thread->print_name_on_error(st, buf, buflen);
4849         st->print("  ");
4850         task->print(st, NULL, short_form, true);
4851       }
4852     }
4853   }
4854 }
4855 
4856 
4857 // Internal SpinLock and Mutex
4858 // Based on ParkEvent
4859 
4860 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4861 //
4862 // We employ SpinLocks _only for low-contention, fixed-length
4863 // short-duration critical sections where we're concerned
4864 // about native mutex_t or HotSpot Mutex:: latency.
4865 // The mux construct provides a spin-then-block mutual exclusion
4866 // mechanism.
4867 //
4868 // Testing has shown that contention on the ListLock guarding gFreeList
4869 // is common.  If we implement ListLock as a simple SpinLock it's common
4870 // for the JVM to devolve to yielding with little progress.  This is true
4871 // despite the fact that the critical sections protected by ListLock are
4872 // extremely short.
4873 //
4874 // TODO-FIXME: ListLock should be of type SpinLock.
4875 // We should make this a 1st-class type, integrated into the lock
4876 // hierarchy as leaf-locks.  Critically, the SpinLock structure
4877 // should have sufficient padding to avoid false-sharing and excessive
4878 // cache-coherency traffic.
4879 
4880 
4881 typedef volatile int SpinLockT;
4882 
4883 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4884   if (Atomic::cmpxchg(adr, 0, 1) == 0) {
4885     return;   // normal fast-path return
4886   }
4887 
4888   // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4889   int ctr = 0;
4890   int Yields = 0;
4891   for (;;) {
4892     while (*adr != 0) {
4893       ++ctr;
4894       if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4895         if (Yields > 5) {
4896           os::naked_short_sleep(1);
4897         } else {
4898           os::naked_yield();
4899           ++Yields;
4900         }
4901       } else {
4902         SpinPause();
4903       }
4904     }
4905     if (Atomic::cmpxchg(adr, 0, 1) == 0) return;
4906   }
4907 }
4908 
4909 void Thread::SpinRelease(volatile int * adr) {
4910   assert(*adr != 0, "invariant");
4911   OrderAccess::fence();      // guarantee at least release consistency.
4912   // Roach-motel semantics.
4913   // It's safe if subsequent LDs and STs float "up" into the critical section,
4914   // but prior LDs and STs within the critical section can't be allowed
4915   // to reorder or float past the ST that releases the lock.
4916   // Loads and stores in the critical section - which appear in program
4917   // order before the store that releases the lock - must also appear
4918   // before the store that releases the lock in memory visibility order.
4919   // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4920   // the ST of 0 into the lock-word which releases the lock, so fence
4921   // more than covers this on all platforms.
4922   *adr = 0;
4923 }
4924 
4925 // muxAcquire and muxRelease:
4926 //
4927 // *  muxAcquire and muxRelease support a single-word lock-word construct.
4928 //    The LSB of the word is set IFF the lock is held.
4929 //    The remainder of the word points to the head of a singly-linked list
4930 //    of threads blocked on the lock.
4931 //
4932 // *  The current implementation of muxAcquire-muxRelease uses its own
4933 //    dedicated Thread._MuxEvent instance.  If we're interested in
4934 //    minimizing the peak number of extant ParkEvent instances then
4935 //    we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4936 //    as certain invariants were satisfied.  Specifically, care would need
4937 //    to be taken with regards to consuming unpark() "permits".
4938 //    A safe rule of thumb is that a thread would never call muxAcquire()
4939 //    if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4940 //    park().  Otherwise the _ParkEvent park() operation in muxAcquire() could
4941 //    consume an unpark() permit intended for monitorenter, for instance.
4942 //    One way around this would be to widen the restricted-range semaphore
4943 //    implemented in park().  Another alternative would be to provide
4944 //    multiple instances of the PlatformEvent() for each thread.  One
4945 //    instance would be dedicated to muxAcquire-muxRelease, for instance.
4946 //
4947 // *  Usage:
4948 //    -- Only as leaf locks
4949 //    -- for short-term locking only as muxAcquire does not perform
4950 //       thread state transitions.
4951 //
4952 // Alternatives:
4953 // *  We could implement muxAcquire and muxRelease with MCS or CLH locks
4954 //    but with parking or spin-then-park instead of pure spinning.
4955 // *  Use Taura-Oyama-Yonenzawa locks.
4956 // *  It's possible to construct a 1-0 lock if we encode the lockword as
4957 //    (List,LockByte).  Acquire will CAS the full lockword while Release
4958 //    will STB 0 into the LockByte.  The 1-0 scheme admits stranding, so
4959 //    acquiring threads use timers (ParkTimed) to detect and recover from
4960 //    the stranding window.  Thread/Node structures must be aligned on 256-byte
4961 //    boundaries by using placement-new.
4962 // *  Augment MCS with advisory back-link fields maintained with CAS().
4963 //    Pictorially:  LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4964 //    The validity of the backlinks must be ratified before we trust the value.
4965 //    If the backlinks are invalid the exiting thread must back-track through the
4966 //    the forward links, which are always trustworthy.
4967 // *  Add a successor indication.  The LockWord is currently encoded as
4968 //    (List, LOCKBIT:1).  We could also add a SUCCBIT or an explicit _succ variable
4969 //    to provide the usual futile-wakeup optimization.
4970 //    See RTStt for details.
4971 //
4972 
4973 
4974 const intptr_t LOCKBIT = 1;
4975 
4976 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4977   intptr_t w = Atomic::cmpxchg(Lock, (intptr_t)0, LOCKBIT);
4978   if (w == 0) return;
4979   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(Lock, w, w|LOCKBIT) == w) {
4980     return;
4981   }
4982 
4983   ParkEvent * const Self = Thread::current()->_MuxEvent;
4984   assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4985   for (;;) {
4986     int its = (os::is_MP() ? 100 : 0) + 1;
4987 
4988     // Optional spin phase: spin-then-park strategy
4989     while (--its >= 0) {
4990       w = *Lock;
4991       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(Lock, w, w|LOCKBIT) == w) {
4992         return;
4993       }
4994     }
4995 
4996     Self->reset();
4997     Self->OnList = intptr_t(Lock);
4998     // The following fence() isn't _strictly necessary as the subsequent
4999     // CAS() both serializes execution and ratifies the fetched *Lock value.
5000     OrderAccess::fence();
5001     for (;;) {
5002       w = *Lock;
5003       if ((w & LOCKBIT) == 0) {
5004         if (Atomic::cmpxchg(Lock, w, w|LOCKBIT) == w) {
5005           Self->OnList = 0;   // hygiene - allows stronger asserts
5006           return;
5007         }
5008         continue;      // Interference -- *Lock changed -- Just retry
5009       }
5010       assert(w & LOCKBIT, "invariant");
5011       Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
5012       if (Atomic::cmpxchg(Lock, w, intptr_t(Self)|LOCKBIT) == w) break;
5013     }
5014 
5015     while (Self->OnList != 0) {
5016       Self->park();
5017     }
5018   }
5019 }
5020 
5021 // Release() must extract a successor from the list and then wake that thread.
5022 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
5023 // similar to that used by ParkEvent::Allocate() and ::Release().  DMR-based
5024 // Release() would :
5025 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
5026 // (B) Extract a successor from the private list "in-hand"
5027 // (C) attempt to CAS() the residual back into *Lock over null.
5028 //     If there were any newly arrived threads and the CAS() would fail.
5029 //     In that case Release() would detach the RATs, re-merge the list in-hand
5030 //     with the RATs and repeat as needed.  Alternately, Release() might
5031 //     detach and extract a successor, but then pass the residual list to the wakee.
5032 //     The wakee would be responsible for reattaching and remerging before it
5033 //     competed for the lock.
5034 //
5035 // Both "pop" and DMR are immune from ABA corruption -- there can be
5036 // multiple concurrent pushers, but only one popper or detacher.
5037 // This implementation pops from the head of the list.  This is unfair,
5038 // but tends to provide excellent throughput as hot threads remain hot.
5039 // (We wake recently run threads first).
5040 //
5041 // All paths through muxRelease() will execute a CAS.
5042 // Release consistency -- We depend on the CAS in muxRelease() to provide full
5043 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
5044 // executed within the critical section are complete and globally visible before the
5045 // store (CAS) to the lock-word that releases the lock becomes globally visible.
5046 void Thread::muxRelease(volatile intptr_t * Lock)  {
5047   for (;;) {
5048     const intptr_t w = Atomic::cmpxchg(Lock, LOCKBIT, (intptr_t)0);
5049     assert(w & LOCKBIT, "invariant");
5050     if (w == LOCKBIT) return;
5051     ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
5052     assert(List != NULL, "invariant");
5053     assert(List->OnList == intptr_t(Lock), "invariant");
5054     ParkEvent * const nxt = List->ListNext;
5055     guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
5056 
5057     // The following CAS() releases the lock and pops the head element.
5058     // The CAS() also ratifies the previously fetched lock-word value.
5059     if (Atomic::cmpxchg(Lock, w, intptr_t(nxt)) != w) {
5060       continue;
5061     }
5062     List->OnList = 0;
5063     OrderAccess::fence();
5064     List->unpark();
5065     return;
5066   }
5067 }
5068 
5069 
5070 void Threads::verify() {
5071   ALL_JAVA_THREADS(p) {
5072     p->verify();
5073   }
5074   VMThread* thread = VMThread::vm_thread();
5075   if (thread != NULL) thread->verify();
5076 }