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