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