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