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/vm_operations.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 
 217 Thread::Thread() {
 218   // stack and get_thread
 219   set_stack_base(NULL);
 220   set_stack_size(0);
 221   set_self_raw_id(0);
 222   set_lgrp_id(-1);
 223   DEBUG_ONLY(clear_suspendible_thread();)
 224 
 225   // allocated data structures
 226   set_osthread(NULL);
 227   set_resource_area(new (mtThread)ResourceArea());
 228   DEBUG_ONLY(_current_resource_mark = NULL;)
 229   set_handle_area(new (mtThread) HandleArea(NULL));
 230   set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
 231   set_active_handles(NULL);
 232   set_free_handle_block(NULL);
 233   set_last_handle_mark(NULL);
 234   DEBUG_ONLY(_missed_ic_stub_refill_mark = NULL);
 235 
 236   // This initial value ==> never claimed.
 237   _oops_do_parity = 0;
 238   _threads_hazard_ptr = NULL;
 239   _threads_list_ptr = NULL;
 240   _nested_threads_hazard_ptr_cnt = 0;
 241   _rcu_counter = 0;
 242 
 243   // the handle mark links itself to last_handle_mark
 244   new HandleMark(this);
 245 
 246   // plain initialization
 247   debug_only(_owned_locks = NULL;)
 248   debug_only(_allow_allocation_count = 0;)
 249   NOT_PRODUCT(_allow_safepoint_count = 0;)
 250   NOT_PRODUCT(_skip_gcalot = false;)
 251   _jvmti_env_iteration_count = 0;
 252   set_allocated_bytes(0);
 253   _vm_operation_started_count = 0;
 254   _vm_operation_completed_count = 0;
 255   _current_pending_monitor = NULL;
 256   _current_pending_monitor_is_from_java = true;
 257   _current_waiting_monitor = NULL;
 258   _num_nested_signal = 0;
 259   omFreeList = NULL;
 260   omFreeCount = 0;
 261   omFreeProvision = 32;
 262   omInUseList = NULL;
 263   omInUseCount = 0;
 264 
 265 #ifdef ASSERT
 266   _visited_for_critical_count = false;
 267 #endif
 268 
 269   _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
 270                          Monitor::_safepoint_check_sometimes);
 271   _suspend_flags = 0;
 272 
 273   // thread-specific hashCode stream generator state - Marsaglia shift-xor form
 274   _hashStateX = os::random();
 275   _hashStateY = 842502087;
 276   _hashStateZ = 0x8767;    // (int)(3579807591LL & 0xffff) ;
 277   _hashStateW = 273326509;
 278 
 279   _OnTrap   = 0;
 280   _Stalled  = 0;
 281   _TypeTag  = 0x2BAD;
 282 
 283   // Many of the following fields are effectively final - immutable
 284   // Note that nascent threads can't use the Native Monitor-Mutex
 285   // construct until the _MutexEvent is initialized ...
 286   // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
 287   // we might instead use a stack of ParkEvents that we could provision on-demand.
 288   // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
 289   // and ::Release()
 290   _ParkEvent   = ParkEvent::Allocate(this);
 291   _SleepEvent  = ParkEvent::Allocate(this);
 292   _MutexEvent  = ParkEvent::Allocate(this);
 293   _MuxEvent    = ParkEvent::Allocate(this);
 294 
 295 #ifdef CHECK_UNHANDLED_OOPS
 296   if (CheckUnhandledOops) {
 297     _unhandled_oops = new UnhandledOops(this);
 298   }
 299 #endif // CHECK_UNHANDLED_OOPS
 300 #ifdef ASSERT
 301   if (UseBiasedLocking) {
 302     assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
 303     assert(this == _real_malloc_address ||
 304            this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment),
 305            "bug in forced alignment of thread objects");
 306   }
 307 #endif // ASSERT
 308 
 309   // Notify the barrier set that a thread is being created. Note that some
 310   // threads are created before a barrier set is available. The call to
 311   // BarrierSet::on_thread_create() for these threads is therefore deferred
 312   // to BarrierSet::set_barrier_set().
 313   BarrierSet* const barrier_set = BarrierSet::barrier_set();
 314   if (barrier_set != NULL) {
 315     barrier_set->on_thread_create(this);
 316   } else {
 317     DEBUG_ONLY(Threads::inc_threads_before_barrier_set();)
 318   }
 319 }
 320 
 321 void Thread::initialize_thread_current() {
 322 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 323   assert(_thr_current == NULL, "Thread::current already initialized");
 324   _thr_current = this;
 325 #endif
 326   assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
 327   ThreadLocalStorage::set_thread(this);
 328   assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
 329 }
 330 
 331 void Thread::clear_thread_current() {
 332   assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
 333 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 334   _thr_current = NULL;
 335 #endif
 336   ThreadLocalStorage::set_thread(NULL);
 337 }
 338 
 339 void Thread::record_stack_base_and_size() {
 340   // Note: at this point, Thread object is not yet initialized. Do not rely on
 341   // any members being initialized. Do not rely on Thread::current() being set.
 342   // If possible, refrain from doing anything which may crash or assert since
 343   // quite probably those crash dumps will be useless.
 344   set_stack_base(os::current_stack_base());
 345   set_stack_size(os::current_stack_size());
 346 
 347 #ifdef SOLARIS
 348   if (os::is_primordial_thread()) {
 349     os::Solaris::correct_stack_boundaries_for_primordial_thread(this);
 350   }
 351 #endif
 352 
 353   // Set stack limits after thread is initialized.
 354   if (is_Java_thread()) {
 355     ((JavaThread*) this)->set_stack_overflow_limit();
 356     ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
 357   }
 358 }
 359 
 360 #if INCLUDE_NMT
 361 void Thread::register_thread_stack_with_NMT() {
 362   MemTracker::record_thread_stack(stack_end(), stack_size());
 363 }
 364 #endif // INCLUDE_NMT
 365 
 366 void Thread::call_run() {
 367   // At this point, Thread object should be fully initialized and
 368   // Thread::current() should be set.
 369 
 370   register_thread_stack_with_NMT();
 371 
 372   JFR_ONLY(Jfr::on_thread_start(this);)
 373 
 374   log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
 375     PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
 376     os::current_thread_id(), p2i(stack_base() - stack_size()),
 377     p2i(stack_base()), stack_size()/1024);
 378 
 379   // Invoke <ChildClass>::run()
 380   this->run();
 381   // Returned from <ChildClass>::run(). Thread finished.
 382 
 383   // Note: at this point the thread object may already have deleted itself.
 384   // So from here on do not dereference *this*.
 385 
 386   // If a thread has not deleted itself ("delete this") as part of its
 387   // termination sequence, we have to ensure thread-local-storage is
 388   // cleared before we actually terminate. No threads should ever be
 389   // deleted asynchronously with respect to their termination.
 390   if (Thread::current_or_null_safe() != NULL) {
 391     assert(Thread::current_or_null_safe() == this, "current thread is wrong");
 392     Thread::clear_thread_current();
 393   }
 394 
 395 }
 396 
 397 Thread::~Thread() {
 398   // Notify the barrier set that a thread is being destroyed. Note that a barrier
 399   // set might not be available if we encountered errors during bootstrapping.
 400   BarrierSet* const barrier_set = BarrierSet::barrier_set();
 401   if (barrier_set != NULL) {
 402     barrier_set->on_thread_destroy(this);
 403   }
 404 
 405   // stack_base can be NULL if the thread is never started or exited before
 406   // record_stack_base_and_size called. Although, we would like to ensure
 407   // that all started threads do call record_stack_base_and_size(), there is
 408   // not proper way to enforce that.
 409 #if INCLUDE_NMT
 410   if (_stack_base != NULL) {
 411     MemTracker::release_thread_stack(stack_end(), stack_size());
 412 #ifdef ASSERT
 413     set_stack_base(NULL);
 414 #endif
 415   }
 416 #endif // INCLUDE_NMT
 417 
 418   // deallocate data structures
 419   delete resource_area();
 420   // since the handle marks are using the handle area, we have to deallocated the root
 421   // handle mark before deallocating the thread's handle area,
 422   assert(last_handle_mark() != NULL, "check we have an element");
 423   delete last_handle_mark();
 424   assert(last_handle_mark() == NULL, "check we have reached the end");
 425 
 426   // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
 427   // We NULL out the fields for good hygiene.
 428   ParkEvent::Release(_ParkEvent); _ParkEvent   = NULL;
 429   ParkEvent::Release(_SleepEvent); _SleepEvent  = NULL;
 430   ParkEvent::Release(_MutexEvent); _MutexEvent  = NULL;
 431   ParkEvent::Release(_MuxEvent); _MuxEvent    = NULL;
 432 
 433   delete handle_area();
 434   delete metadata_handles();
 435 
 436   // SR_handler uses this as a termination indicator -
 437   // needs to happen before os::free_thread()
 438   delete _SR_lock;
 439   _SR_lock = NULL;
 440 
 441   // osthread() can be NULL, if creation of thread failed.
 442   if (osthread() != NULL) os::free_thread(osthread());
 443 
 444   // clear Thread::current if thread is deleting itself.
 445   // Needed to ensure JNI correctly detects non-attached threads.
 446   if (this == Thread::current()) {
 447     Thread::clear_thread_current();
 448   }
 449 
 450   CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
 451 }
 452 
 453 #ifdef ASSERT
 454 // A JavaThread is considered "dangling" if it is not the current
 455 // thread, has been added the Threads list, the system is not at a
 456 // safepoint and the Thread is not "protected".
 457 //
 458 void Thread::check_for_dangling_thread_pointer(Thread *thread) {
 459   assert(!thread->is_Java_thread() || Thread::current() == thread ||
 460          !((JavaThread *) thread)->on_thread_list() ||
 461          SafepointSynchronize::is_at_safepoint() ||
 462          ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread),
 463          "possibility of dangling Thread pointer");
 464 }
 465 #endif
 466 
 467 ThreadPriority Thread::get_priority(const Thread* const thread) {
 468   ThreadPriority priority;
 469   // Can return an error!
 470   (void)os::get_priority(thread, priority);
 471   assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
 472   return priority;
 473 }
 474 
 475 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
 476   debug_only(check_for_dangling_thread_pointer(thread);)
 477   // Can return an error!
 478   (void)os::set_priority(thread, priority);
 479 }
 480 
 481 
 482 void Thread::start(Thread* thread) {
 483   // Start is different from resume in that its safety is guaranteed by context or
 484   // being called from a Java method synchronized on the Thread object.
 485   if (!DisableStartThread) {
 486     if (thread->is_Java_thread()) {
 487       // Initialize the thread state to RUNNABLE before starting this thread.
 488       // Can not set it after the thread started because we do not know the
 489       // exact thread state at that time. It could be in MONITOR_WAIT or
 490       // in SLEEPING or some other state.
 491       java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
 492                                           java_lang_Thread::RUNNABLE);
 493     }
 494     os::start_thread(thread);
 495   }
 496 }
 497 
 498 // Enqueue a VM_Operation to do the job for us - sometime later
 499 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
 500   VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
 501   VMThread::execute(vm_stop);
 502 }
 503 
 504 
 505 // Check if an external suspend request has completed (or has been
 506 // cancelled). Returns true if the thread is externally suspended and
 507 // false otherwise.
 508 //
 509 // The bits parameter returns information about the code path through
 510 // the routine. Useful for debugging:
 511 //
 512 // set in is_ext_suspend_completed():
 513 // 0x00000001 - routine was entered
 514 // 0x00000010 - routine return false at end
 515 // 0x00000100 - thread exited (return false)
 516 // 0x00000200 - suspend request cancelled (return false)
 517 // 0x00000400 - thread suspended (return true)
 518 // 0x00001000 - thread is in a suspend equivalent state (return true)
 519 // 0x00002000 - thread is native and walkable (return true)
 520 // 0x00004000 - thread is native_trans and walkable (needed retry)
 521 //
 522 // set in wait_for_ext_suspend_completion():
 523 // 0x00010000 - routine was entered
 524 // 0x00020000 - suspend request cancelled before loop (return false)
 525 // 0x00040000 - thread suspended before loop (return true)
 526 // 0x00080000 - suspend request cancelled in loop (return false)
 527 // 0x00100000 - thread suspended in loop (return true)
 528 // 0x00200000 - suspend not completed during retry loop (return false)
 529 
 530 // Helper class for tracing suspend wait debug bits.
 531 //
 532 // 0x00000100 indicates that the target thread exited before it could
 533 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
 534 // 0x00080000 each indicate a cancelled suspend request so they don't
 535 // count as wait failures either.
 536 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
 537 
 538 class TraceSuspendDebugBits : public StackObj {
 539  private:
 540   JavaThread * jt;
 541   bool         is_wait;
 542   bool         called_by_wait;  // meaningful when !is_wait
 543   uint32_t *   bits;
 544 
 545  public:
 546   TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
 547                         uint32_t *_bits) {
 548     jt             = _jt;
 549     is_wait        = _is_wait;
 550     called_by_wait = _called_by_wait;
 551     bits           = _bits;
 552   }
 553 
 554   ~TraceSuspendDebugBits() {
 555     if (!is_wait) {
 556 #if 1
 557       // By default, don't trace bits for is_ext_suspend_completed() calls.
 558       // That trace is very chatty.
 559       return;
 560 #else
 561       if (!called_by_wait) {
 562         // If tracing for is_ext_suspend_completed() is enabled, then only
 563         // trace calls to it from wait_for_ext_suspend_completion()
 564         return;
 565       }
 566 #endif
 567     }
 568 
 569     if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
 570       if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
 571         MutexLocker ml(Threads_lock);  // needed for get_thread_name()
 572         ResourceMark rm;
 573 
 574         tty->print_cr(
 575                       "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
 576                       jt->get_thread_name(), *bits);
 577 
 578         guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
 579       }
 580     }
 581   }
 582 };
 583 #undef DEBUG_FALSE_BITS
 584 
 585 
 586 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
 587                                           uint32_t *bits) {
 588   TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
 589 
 590   bool did_trans_retry = false;  // only do thread_in_native_trans retry once
 591   bool do_trans_retry;           // flag to force the retry
 592 
 593   *bits |= 0x00000001;
 594 
 595   do {
 596     do_trans_retry = false;
 597 
 598     if (is_exiting()) {
 599       // Thread is in the process of exiting. This is always checked
 600       // first to reduce the risk of dereferencing a freed JavaThread.
 601       *bits |= 0x00000100;
 602       return false;
 603     }
 604 
 605     if (!is_external_suspend()) {
 606       // Suspend request is cancelled. This is always checked before
 607       // is_ext_suspended() to reduce the risk of a rogue resume
 608       // confusing the thread that made the suspend request.
 609       *bits |= 0x00000200;
 610       return false;
 611     }
 612 
 613     if (is_ext_suspended()) {
 614       // thread is suspended
 615       *bits |= 0x00000400;
 616       return true;
 617     }
 618 
 619     // Now that we no longer do hard suspends of threads running
 620     // native code, the target thread can be changing thread state
 621     // while we are in this routine:
 622     //
 623     //   _thread_in_native -> _thread_in_native_trans -> _thread_blocked
 624     //
 625     // We save a copy of the thread state as observed at this moment
 626     // and make our decision about suspend completeness based on the
 627     // copy. This closes the race where the thread state is seen as
 628     // _thread_in_native_trans in the if-thread_blocked check, but is
 629     // seen as _thread_blocked in if-thread_in_native_trans check.
 630     JavaThreadState save_state = thread_state();
 631 
 632     if (save_state == _thread_blocked && is_suspend_equivalent()) {
 633       // If the thread's state is _thread_blocked and this blocking
 634       // condition is known to be equivalent to a suspend, then we can
 635       // consider the thread to be externally suspended. This means that
 636       // the code that sets _thread_blocked has been modified to do
 637       // self-suspension if the blocking condition releases. We also
 638       // used to check for CONDVAR_WAIT here, but that is now covered by
 639       // the _thread_blocked with self-suspension check.
 640       //
 641       // Return true since we wouldn't be here unless there was still an
 642       // external suspend request.
 643       *bits |= 0x00001000;
 644       return true;
 645     } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
 646       // Threads running native code will self-suspend on native==>VM/Java
 647       // transitions. If its stack is walkable (should always be the case
 648       // unless this function is called before the actual java_suspend()
 649       // call), then the wait is done.
 650       *bits |= 0x00002000;
 651       return true;
 652     } else if (!called_by_wait && !did_trans_retry &&
 653                save_state == _thread_in_native_trans &&
 654                frame_anchor()->walkable()) {
 655       // The thread is transitioning from thread_in_native to another
 656       // thread state. check_safepoint_and_suspend_for_native_trans()
 657       // will force the thread to self-suspend. If it hasn't gotten
 658       // there yet we may have caught the thread in-between the native
 659       // code check above and the self-suspend. Lucky us. If we were
 660       // called by wait_for_ext_suspend_completion(), then it
 661       // will be doing the retries so we don't have to.
 662       //
 663       // Since we use the saved thread state in the if-statement above,
 664       // there is a chance that the thread has already transitioned to
 665       // _thread_blocked by the time we get here. In that case, we will
 666       // make a single unnecessary pass through the logic below. This
 667       // doesn't hurt anything since we still do the trans retry.
 668 
 669       *bits |= 0x00004000;
 670 
 671       // Once the thread leaves thread_in_native_trans for another
 672       // thread state, we break out of this retry loop. We shouldn't
 673       // need this flag to prevent us from getting back here, but
 674       // sometimes paranoia is good.
 675       did_trans_retry = true;
 676 
 677       // We wait for the thread to transition to a more usable state.
 678       for (int i = 1; i <= SuspendRetryCount; i++) {
 679         // We used to do an "os::yield_all(i)" call here with the intention
 680         // that yielding would increase on each retry. However, the parameter
 681         // is ignored on Linux which means the yield didn't scale up. Waiting
 682         // on the SR_lock below provides a much more predictable scale up for
 683         // the delay. It also provides a simple/direct point to check for any
 684         // safepoint requests from the VMThread
 685 
 686         // temporarily drops SR_lock while doing wait with safepoint check
 687         // (if we're a JavaThread - the WatcherThread can also call this)
 688         // and increase delay with each retry
 689         SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 690 
 691         // check the actual thread state instead of what we saved above
 692         if (thread_state() != _thread_in_native_trans) {
 693           // the thread has transitioned to another thread state so
 694           // try all the checks (except this one) one more time.
 695           do_trans_retry = true;
 696           break;
 697         }
 698       } // end retry loop
 699 
 700 
 701     }
 702   } while (do_trans_retry);
 703 
 704   *bits |= 0x00000010;
 705   return false;
 706 }
 707 
 708 // Wait for an external suspend request to complete (or be cancelled).
 709 // Returns true if the thread is externally suspended and false otherwise.
 710 //
 711 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
 712                                                  uint32_t *bits) {
 713   TraceSuspendDebugBits tsdb(this, true /* is_wait */,
 714                              false /* !called_by_wait */, bits);
 715 
 716   // local flag copies to minimize SR_lock hold time
 717   bool is_suspended;
 718   bool pending;
 719   uint32_t reset_bits;
 720 
 721   // set a marker so is_ext_suspend_completed() knows we are the caller
 722   *bits |= 0x00010000;
 723 
 724   // We use reset_bits to reinitialize the bits value at the top of
 725   // each retry loop. This allows the caller to make use of any
 726   // unused bits for their own marking purposes.
 727   reset_bits = *bits;
 728 
 729   {
 730     MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
 731     is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 732                                             delay, bits);
 733     pending = is_external_suspend();
 734   }
 735   // must release SR_lock to allow suspension to complete
 736 
 737   if (!pending) {
 738     // A cancelled suspend request is the only false return from
 739     // is_ext_suspend_completed() that keeps us from entering the
 740     // retry loop.
 741     *bits |= 0x00020000;
 742     return false;
 743   }
 744 
 745   if (is_suspended) {
 746     *bits |= 0x00040000;
 747     return true;
 748   }
 749 
 750   for (int i = 1; i <= retries; i++) {
 751     *bits = reset_bits;  // reinit to only track last retry
 752 
 753     // We used to do an "os::yield_all(i)" call here with the intention
 754     // that yielding would increase on each retry. However, the parameter
 755     // is ignored on Linux which means the yield didn't scale up. Waiting
 756     // on the SR_lock below provides a much more predictable scale up for
 757     // the delay. It also provides a simple/direct point to check for any
 758     // safepoint requests from the VMThread
 759 
 760     {
 761       MutexLocker ml(SR_lock());
 762       // wait with safepoint check (if we're a JavaThread - the WatcherThread
 763       // can also call this)  and increase delay with each retry
 764       SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 765 
 766       is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 767                                               delay, bits);
 768 
 769       // It is possible for the external suspend request to be cancelled
 770       // (by a resume) before the actual suspend operation is completed.
 771       // Refresh our local copy to see if we still need to wait.
 772       pending = is_external_suspend();
 773     }
 774 
 775     if (!pending) {
 776       // A cancelled suspend request is the only false return from
 777       // is_ext_suspend_completed() that keeps us from staying in the
 778       // retry loop.
 779       *bits |= 0x00080000;
 780       return false;
 781     }
 782 
 783     if (is_suspended) {
 784       *bits |= 0x00100000;
 785       return true;
 786     }
 787   } // end retry loop
 788 
 789   // thread did not suspend after all our retries
 790   *bits |= 0x00200000;
 791   return false;
 792 }
 793 
 794 // Called from API entry points which perform stack walking. If the
 795 // associated JavaThread is the current thread, then wait_for_suspend
 796 // is not used. Otherwise, it determines if we should wait for the
 797 // "other" thread to complete external suspension. (NOTE: in future
 798 // releases the suspension mechanism should be reimplemented so this
 799 // is not necessary.)
 800 //
 801 bool
 802 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) {
 803   if (this != JavaThread::current()) {
 804     // "other" threads require special handling.
 805     if (wait_for_suspend) {
 806       // We are allowed to wait for the external suspend to complete
 807       // so give the other thread a chance to get suspended.
 808       if (!wait_for_ext_suspend_completion(SuspendRetryCount,
 809                                            SuspendRetryDelay, bits)) {
 810         // Didn't make it so let the caller know.
 811         return false;
 812       }
 813     }
 814     // We aren't allowed to wait for the external suspend to complete
 815     // so if the other thread isn't externally suspended we need to
 816     // let the caller know.
 817     else if (!is_ext_suspend_completed_with_lock(bits)) {
 818       return false;
 819     }
 820   }
 821 
 822   return true;
 823 }
 824 
 825 #ifndef PRODUCT
 826 void JavaThread::record_jump(address target, address instr, const char* file,
 827                              int line) {
 828 
 829   // This should not need to be atomic as the only way for simultaneous
 830   // updates is via interrupts. Even then this should be rare or non-existent
 831   // and we don't care that much anyway.
 832 
 833   int index = _jmp_ring_index;
 834   _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
 835   _jmp_ring[index]._target = (intptr_t) target;
 836   _jmp_ring[index]._instruction = (intptr_t) instr;
 837   _jmp_ring[index]._file = file;
 838   _jmp_ring[index]._line = line;
 839 }
 840 #endif // PRODUCT
 841 
 842 void Thread::interrupt(Thread* thread) {
 843   debug_only(check_for_dangling_thread_pointer(thread);)
 844   os::interrupt(thread);
 845 }
 846 
 847 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
 848   debug_only(check_for_dangling_thread_pointer(thread);)
 849   // Note:  If clear_interrupted==false, this simply fetches and
 850   // returns the value of the field osthread()->interrupted().
 851   return os::is_interrupted(thread, clear_interrupted);
 852 }
 853 
 854 
 855 // GC Support
 856 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
 857   int thread_parity = _oops_do_parity;
 858   if (thread_parity != strong_roots_parity) {
 859     jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
 860     if (res == thread_parity) {
 861       return true;
 862     } else {
 863       guarantee(res == strong_roots_parity, "Or else what?");
 864       return false;
 865     }
 866   }
 867   return false;
 868 }
 869 
 870 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
 871   active_handles()->oops_do(f);
 872   // Do oop for ThreadShadow
 873   f->do_oop((oop*)&_pending_exception);
 874   handle_area()->oops_do(f);
 875 
 876   // We scan thread local monitor lists here, and the remaining global
 877   // monitors in ObjectSynchronizer::oops_do().
 878   ObjectSynchronizer::thread_local_used_oops_do(this, f);
 879 }
 880 
 881 void Thread::metadata_handles_do(void f(Metadata*)) {
 882   // Only walk the Handles in Thread.
 883   if (metadata_handles() != NULL) {
 884     for (int i = 0; i< metadata_handles()->length(); i++) {
 885       f(metadata_handles()->at(i));
 886     }
 887   }
 888 }
 889 
 890 void Thread::print_on(outputStream* st, bool print_extended_info) const {
 891   // get_priority assumes osthread initialized
 892   if (osthread() != NULL) {
 893     int os_prio;
 894     if (os::get_native_priority(this, &os_prio) == OS_OK) {
 895       st->print("os_prio=%d ", os_prio);
 896     }
 897 
 898     st->print("cpu=%.2fms ",
 899               os::thread_cpu_time(const_cast<Thread*>(this), true) / 1000000.0
 900               );
 901     st->print("elapsed=%.2fs ",
 902               _statistical_info.getElapsedTime() / 1000.0
 903               );
 904     if (is_Java_thread() && (PrintExtendedThreadInfo || print_extended_info)) {
 905       size_t allocated_bytes = (size_t) const_cast<Thread*>(this)->cooked_allocated_bytes();
 906       st->print("allocated=" SIZE_FORMAT "%s ",
 907                 byte_size_in_proper_unit(allocated_bytes),
 908                 proper_unit_for_byte_size(allocated_bytes)
 909                 );
 910       st->print("defined_classes=" INT64_FORMAT " ", _statistical_info.getDefineClassCount());
 911     }
 912 
 913     st->print("tid=" INTPTR_FORMAT " ", p2i(this));
 914     osthread()->print_on(st);
 915   }
 916   ThreadsSMRSupport::print_info_on(this, st);
 917   st->print(" ");
 918   debug_only(if (WizardMode) print_owned_locks_on(st);)
 919 }
 920 
 921 // Thread::print_on_error() is called by fatal error handler. Don't use
 922 // any lock or allocate memory.
 923 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
 924   assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
 925 
 926   if (is_VM_thread())                 { st->print("VMThread"); }
 927   else if (is_GC_task_thread())       { st->print("GCTaskThread"); }
 928   else if (is_Watcher_thread())       { st->print("WatcherThread"); }
 929   else if (is_ConcurrentGC_thread())  { st->print("ConcurrentGCThread"); }
 930   else                                { st->print("Thread"); }
 931 
 932   if (is_Named_thread()) {
 933     st->print(" \"%s\"", name());
 934   }
 935 
 936   st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
 937             p2i(stack_end()), p2i(stack_base()));
 938 
 939   if (osthread()) {
 940     st->print(" [id=%d]", osthread()->thread_id());
 941   }
 942 
 943   ThreadsSMRSupport::print_info_on(this, st);
 944 }
 945 
 946 void Thread::print_value_on(outputStream* st) const {
 947   if (is_Named_thread()) {
 948     st->print(" \"%s\" ", name());
 949   }
 950   st->print(INTPTR_FORMAT, p2i(this));   // print address
 951 }
 952 
 953 #ifdef ASSERT
 954 void Thread::print_owned_locks_on(outputStream* st) const {
 955   Monitor *cur = _owned_locks;
 956   if (cur == NULL) {
 957     st->print(" (no locks) ");
 958   } else {
 959     st->print_cr(" Locks owned:");
 960     while (cur) {
 961       cur->print_on(st);
 962       cur = cur->next();
 963     }
 964   }
 965 }
 966 
 967 static int ref_use_count  = 0;
 968 
 969 bool Thread::owns_locks_but_compiled_lock() const {
 970   for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 971     if (cur != Compile_lock) return true;
 972   }
 973   return false;
 974 }
 975 
 976 
 977 #endif
 978 
 979 #ifndef PRODUCT
 980 
 981 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially
 982 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that
 983 // no locks which allow_vm_block's are held
 984 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
 985   // Check if current thread is allowed to block at a safepoint
 986   if (!(_allow_safepoint_count == 0)) {
 987     fatal("Possible safepoint reached by thread that does not allow it");
 988   }
 989   if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
 990     fatal("LEAF method calling lock?");
 991   }
 992 
 993 #ifdef ASSERT
 994   if (potential_vm_operation && is_Java_thread()
 995       && !Universe::is_bootstrapping()) {
 996     // Make sure we do not hold any locks that the VM thread also uses.
 997     // This could potentially lead to deadlocks
 998     for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 999       // Threads_lock is special, since the safepoint synchronization will not start before this is
1000       // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
1001       // since it is used to transfer control between JavaThreads and the VMThread
1002       // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
1003       if ((cur->allow_vm_block() &&
1004            cur != Threads_lock &&
1005            cur != Compile_lock &&               // Temporary: should not be necessary when we get separate compilation
1006            cur != VMOperationRequest_lock &&
1007            cur != VMOperationQueue_lock) ||
1008            cur->rank() == Mutex::special) {
1009         fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
1010       }
1011     }
1012   }
1013 
1014   if (GCALotAtAllSafepoints) {
1015     // We could enter a safepoint here and thus have a gc
1016     InterfaceSupport::check_gc_alot();
1017   }
1018 #endif
1019 }
1020 #endif
1021 
1022 bool Thread::is_in_stack(address adr) const {
1023   assert(Thread::current() == this, "is_in_stack can only be called from current thread");
1024   address end = os::current_stack_pointer();
1025   // Allow non Java threads to call this without stack_base
1026   if (_stack_base == NULL) return true;
1027   if (stack_base() >= adr && adr >= end) return true;
1028 
1029   return false;
1030 }
1031 
1032 bool Thread::is_in_usable_stack(address adr) const {
1033   size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
1034   size_t usable_stack_size = _stack_size - stack_guard_size;
1035 
1036   return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
1037 }
1038 
1039 
1040 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
1041 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
1042 // used for compilation in the future. If that change is made, the need for these methods
1043 // should be revisited, and they should be removed if possible.
1044 
1045 bool Thread::is_lock_owned(address adr) const {
1046   return on_local_stack(adr);
1047 }
1048 
1049 bool Thread::set_as_starting_thread() {
1050   // NOTE: this must be called inside the main thread.
1051   return os::create_main_thread((JavaThread*)this);
1052 }
1053 
1054 static void initialize_class(Symbol* class_name, TRAPS) {
1055   Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
1056   InstanceKlass::cast(klass)->initialize(CHECK);
1057 }
1058 
1059 
1060 // Creates the initial ThreadGroup
1061 static Handle create_initial_thread_group(TRAPS) {
1062   Handle system_instance = JavaCalls::construct_new_instance(
1063                             SystemDictionary::ThreadGroup_klass(),
1064                             vmSymbols::void_method_signature(),
1065                             CHECK_NH);
1066   Universe::set_system_thread_group(system_instance());
1067 
1068   Handle string = java_lang_String::create_from_str("main", CHECK_NH);
1069   Handle main_instance = JavaCalls::construct_new_instance(
1070                             SystemDictionary::ThreadGroup_klass(),
1071                             vmSymbols::threadgroup_string_void_signature(),
1072                             system_instance,
1073                             string,
1074                             CHECK_NH);
1075   return main_instance;
1076 }
1077 
1078 // Creates the initial Thread
1079 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
1080                                  TRAPS) {
1081   InstanceKlass* ik = SystemDictionary::Thread_klass();
1082   assert(ik->is_initialized(), "must be");
1083   instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
1084 
1085   // Cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1086   // constructor calls Thread.current(), which must be set here for the
1087   // initial thread.
1088   java_lang_Thread::set_thread(thread_oop(), thread);
1089   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1090   thread->set_threadObj(thread_oop());
1091 
1092   Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1093 
1094   JavaValue result(T_VOID);
1095   JavaCalls::call_special(&result, thread_oop,
1096                           ik,
1097                           vmSymbols::object_initializer_name(),
1098                           vmSymbols::threadgroup_string_void_signature(),
1099                           thread_group,
1100                           string,
1101                           CHECK_NULL);
1102   return thread_oop();
1103 }
1104 
1105 char java_runtime_name[128] = "";
1106 char java_runtime_version[128] = "";
1107 
1108 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1109 static const char* get_java_runtime_name(TRAPS) {
1110   Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1111                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1112   fieldDescriptor fd;
1113   bool found = k != NULL &&
1114                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1115                                                         vmSymbols::string_signature(), &fd);
1116   if (found) {
1117     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1118     if (name_oop == NULL) {
1119       return NULL;
1120     }
1121     const char* name = java_lang_String::as_utf8_string(name_oop,
1122                                                         java_runtime_name,
1123                                                         sizeof(java_runtime_name));
1124     return name;
1125   } else {
1126     return NULL;
1127   }
1128 }
1129 
1130 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1131 static const char* get_java_runtime_version(TRAPS) {
1132   Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1133                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1134   fieldDescriptor fd;
1135   bool found = k != NULL &&
1136                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1137                                                         vmSymbols::string_signature(), &fd);
1138   if (found) {
1139     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1140     if (name_oop == NULL) {
1141       return NULL;
1142     }
1143     const char* name = java_lang_String::as_utf8_string(name_oop,
1144                                                         java_runtime_version,
1145                                                         sizeof(java_runtime_version));
1146     return name;
1147   } else {
1148     return NULL;
1149   }
1150 }
1151 
1152 // General purpose hook into Java code, run once when the VM is initialized.
1153 // The Java library method itself may be changed independently from the VM.
1154 static void call_postVMInitHook(TRAPS) {
1155   Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1156   if (klass != NULL) {
1157     JavaValue result(T_VOID);
1158     JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1159                            vmSymbols::void_method_signature(),
1160                            CHECK);
1161   }
1162 }
1163 
1164 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1165                                     bool daemon, TRAPS) {
1166   assert(thread_group.not_null(), "thread group should be specified");
1167   assert(threadObj() == NULL, "should only create Java thread object once");
1168 
1169   InstanceKlass* ik = SystemDictionary::Thread_klass();
1170   assert(ik->is_initialized(), "must be");
1171   instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1172 
1173   // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon.
1174   // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1175   // constructor calls Thread.current(), which must be set here.
1176   java_lang_Thread::set_thread(thread_oop(), this);
1177   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1178   set_threadObj(thread_oop());
1179 
1180   JavaValue result(T_VOID);
1181   if (thread_name != NULL) {
1182     Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1183     // Thread gets assigned specified name and null target
1184     JavaCalls::call_special(&result,
1185                             thread_oop,
1186                             ik,
1187                             vmSymbols::object_initializer_name(),
1188                             vmSymbols::threadgroup_string_void_signature(),
1189                             thread_group,
1190                             name,
1191                             THREAD);
1192   } else {
1193     // Thread gets assigned name "Thread-nnn" and null target
1194     // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1195     JavaCalls::call_special(&result,
1196                             thread_oop,
1197                             ik,
1198                             vmSymbols::object_initializer_name(),
1199                             vmSymbols::threadgroup_runnable_void_signature(),
1200                             thread_group,
1201                             Handle(),
1202                             THREAD);
1203   }
1204 
1205 
1206   if (daemon) {
1207     java_lang_Thread::set_daemon(thread_oop());
1208   }
1209 
1210   if (HAS_PENDING_EXCEPTION) {
1211     return;
1212   }
1213 
1214   Klass* group =  SystemDictionary::ThreadGroup_klass();
1215   Handle threadObj(THREAD, this->threadObj());
1216 
1217   JavaCalls::call_special(&result,
1218                           thread_group,
1219                           group,
1220                           vmSymbols::add_method_name(),
1221                           vmSymbols::thread_void_signature(),
1222                           threadObj,          // Arg 1
1223                           THREAD);
1224 }
1225 
1226 // List of all NonJavaThreads and safe iteration over that list.
1227 
1228 class NonJavaThread::List {
1229 public:
1230   NonJavaThread* volatile _head;
1231   SingleWriterSynchronizer _protect;
1232 
1233   List() : _head(NULL), _protect() {}
1234 };
1235 
1236 NonJavaThread::List NonJavaThread::_the_list;
1237 
1238 NonJavaThread::Iterator::Iterator() :
1239   _protect_enter(_the_list._protect.enter()),
1240   _current(OrderAccess::load_acquire(&_the_list._head))
1241 {}
1242 
1243 NonJavaThread::Iterator::~Iterator() {
1244   _the_list._protect.exit(_protect_enter);
1245 }
1246 
1247 void NonJavaThread::Iterator::step() {
1248   assert(!end(), "precondition");
1249   _current = OrderAccess::load_acquire(&_current->_next);
1250 }
1251 
1252 NonJavaThread::NonJavaThread() : Thread(), _next(NULL) {
1253   // Add this thread to _the_list.
1254   MutexLockerEx lock(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1255   _next = _the_list._head;
1256   OrderAccess::release_store(&_the_list._head, this);
1257 }
1258 
1259 NonJavaThread::~NonJavaThread() {
1260   JFR_ONLY(Jfr::on_thread_exit(this);)
1261   // Remove this thread from _the_list.
1262   MutexLockerEx lock(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1263   NonJavaThread* volatile* p = &_the_list._head;
1264   for (NonJavaThread* t = *p; t != NULL; p = &t->_next, t = *p) {
1265     if (t == this) {
1266       *p = this->_next;
1267       // Wait for any in-progress iterators.
1268       _the_list._protect.synchronize();
1269       break;
1270     }
1271   }
1272 }
1273 
1274 // NamedThread --  non-JavaThread subclasses with multiple
1275 // uniquely named instances should derive from this.
1276 NamedThread::NamedThread() :
1277   NonJavaThread(),
1278   _name(NULL),
1279   _processed_thread(NULL),
1280   _gc_id(GCId::undefined())
1281 {}
1282 
1283 NamedThread::~NamedThread() {
1284   if (_name != NULL) {
1285     FREE_C_HEAP_ARRAY(char, _name);
1286     _name = NULL;
1287   }
1288 }
1289 
1290 void NamedThread::set_name(const char* format, ...) {
1291   guarantee(_name == NULL, "Only get to set name once.");
1292   _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1293   guarantee(_name != NULL, "alloc failure");
1294   va_list ap;
1295   va_start(ap, format);
1296   jio_vsnprintf(_name, max_name_len, format, ap);
1297   va_end(ap);
1298 }
1299 
1300 void NamedThread::initialize_named_thread() {
1301   set_native_thread_name(name());
1302 }
1303 
1304 void NamedThread::print_on(outputStream* st) const {
1305   st->print("\"%s\" ", name());
1306   Thread::print_on(st);
1307   st->cr();
1308 }
1309 
1310 
1311 // ======= WatcherThread ========
1312 
1313 // The watcher thread exists to simulate timer interrupts.  It should
1314 // be replaced by an abstraction over whatever native support for
1315 // timer interrupts exists on the platform.
1316 
1317 WatcherThread* WatcherThread::_watcher_thread   = NULL;
1318 bool WatcherThread::_startable = false;
1319 volatile bool  WatcherThread::_should_terminate = false;
1320 
1321 WatcherThread::WatcherThread() : NonJavaThread() {
1322   assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1323   if (os::create_thread(this, os::watcher_thread)) {
1324     _watcher_thread = this;
1325 
1326     // Set the watcher thread to the highest OS priority which should not be
1327     // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1328     // is created. The only normal thread using this priority is the reference
1329     // handler thread, which runs for very short intervals only.
1330     // If the VMThread's priority is not lower than the WatcherThread profiling
1331     // will be inaccurate.
1332     os::set_priority(this, MaxPriority);
1333     if (!DisableStartThread) {
1334       os::start_thread(this);
1335     }
1336   }
1337 }
1338 
1339 int WatcherThread::sleep() const {
1340   // The WatcherThread does not participate in the safepoint protocol
1341   // for the PeriodicTask_lock because it is not a JavaThread.
1342   MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1343 
1344   if (_should_terminate) {
1345     // check for termination before we do any housekeeping or wait
1346     return 0;  // we did not sleep.
1347   }
1348 
1349   // remaining will be zero if there are no tasks,
1350   // causing the WatcherThread to sleep until a task is
1351   // enrolled
1352   int remaining = PeriodicTask::time_to_wait();
1353   int time_slept = 0;
1354 
1355   // we expect this to timeout - we only ever get unparked when
1356   // we should terminate or when a new task has been enrolled
1357   OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1358 
1359   jlong time_before_loop = os::javaTimeNanos();
1360 
1361   while (true) {
1362     bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1363                                             remaining);
1364     jlong now = os::javaTimeNanos();
1365 
1366     if (remaining == 0) {
1367       // if we didn't have any tasks we could have waited for a long time
1368       // consider the time_slept zero and reset time_before_loop
1369       time_slept = 0;
1370       time_before_loop = now;
1371     } else {
1372       // need to recalculate since we might have new tasks in _tasks
1373       time_slept = (int) ((now - time_before_loop) / 1000000);
1374     }
1375 
1376     // Change to task list or spurious wakeup of some kind
1377     if (timedout || _should_terminate) {
1378       break;
1379     }
1380 
1381     remaining = PeriodicTask::time_to_wait();
1382     if (remaining == 0) {
1383       // Last task was just disenrolled so loop around and wait until
1384       // another task gets enrolled
1385       continue;
1386     }
1387 
1388     remaining -= time_slept;
1389     if (remaining <= 0) {
1390       break;
1391     }
1392   }
1393 
1394   return time_slept;
1395 }
1396 
1397 void WatcherThread::run() {
1398   assert(this == watcher_thread(), "just checking");
1399 
1400   this->set_native_thread_name(this->name());
1401   this->set_active_handles(JNIHandleBlock::allocate_block());
1402   while (true) {
1403     assert(watcher_thread() == Thread::current(), "thread consistency check");
1404     assert(watcher_thread() == this, "thread consistency check");
1405 
1406     // Calculate how long it'll be until the next PeriodicTask work
1407     // should be done, and sleep that amount of time.
1408     int time_waited = sleep();
1409 
1410     if (VMError::is_error_reported()) {
1411       // A fatal error has happened, the error handler(VMError::report_and_die)
1412       // should abort JVM after creating an error log file. However in some
1413       // rare cases, the error handler itself might deadlock. Here periodically
1414       // check for error reporting timeouts, and if it happens, just proceed to
1415       // abort the VM.
1416 
1417       // This code is in WatcherThread because WatcherThread wakes up
1418       // periodically so the fatal error handler doesn't need to do anything;
1419       // also because the WatcherThread is less likely to crash than other
1420       // threads.
1421 
1422       for (;;) {
1423         // Note: we use naked sleep in this loop because we want to avoid using
1424         // any kind of VM infrastructure which may be broken at this point.
1425         if (VMError::check_timeout()) {
1426           // We hit error reporting timeout. Error reporting was interrupted and
1427           // will be wrapping things up now (closing files etc). Give it some more
1428           // time, then quit the VM.
1429           os::naked_short_sleep(200);
1430           // Print a message to stderr.
1431           fdStream err(defaultStream::output_fd());
1432           err.print_raw_cr("# [ timer expired, abort... ]");
1433           // skip atexit/vm_exit/vm_abort hooks
1434           os::die();
1435         }
1436 
1437         // Wait a second, then recheck for timeout.
1438         os::naked_short_sleep(999);
1439       }
1440     }
1441 
1442     if (_should_terminate) {
1443       // check for termination before posting the next tick
1444       break;
1445     }
1446 
1447     PeriodicTask::real_time_tick(time_waited);
1448   }
1449 
1450   // Signal that it is terminated
1451   {
1452     MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1453     _watcher_thread = NULL;
1454     Terminator_lock->notify();
1455   }
1456 }
1457 
1458 void WatcherThread::start() {
1459   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1460 
1461   if (watcher_thread() == NULL && _startable) {
1462     _should_terminate = false;
1463     // Create the single instance of WatcherThread
1464     new WatcherThread();
1465   }
1466 }
1467 
1468 void WatcherThread::make_startable() {
1469   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1470   _startable = true;
1471 }
1472 
1473 void WatcherThread::stop() {
1474   {
1475     // Follow normal safepoint aware lock enter protocol since the
1476     // WatcherThread is stopped by another JavaThread.
1477     MutexLocker ml(PeriodicTask_lock);
1478     _should_terminate = true;
1479 
1480     WatcherThread* watcher = watcher_thread();
1481     if (watcher != NULL) {
1482       // unpark the WatcherThread so it can see that it should terminate
1483       watcher->unpark();
1484     }
1485   }
1486 
1487   MutexLocker mu(Terminator_lock);
1488 
1489   while (watcher_thread() != NULL) {
1490     // This wait should make safepoint checks, wait without a timeout,
1491     // and wait as a suspend-equivalent condition.
1492     Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1493                           Mutex::_as_suspend_equivalent_flag);
1494   }
1495 }
1496 
1497 void WatcherThread::unpark() {
1498   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1499   PeriodicTask_lock->notify();
1500 }
1501 
1502 void WatcherThread::print_on(outputStream* st) const {
1503   st->print("\"%s\" ", name());
1504   Thread::print_on(st);
1505   st->cr();
1506 }
1507 
1508 // ======= JavaThread ========
1509 
1510 #if INCLUDE_JVMCI
1511 
1512 jlong* JavaThread::_jvmci_old_thread_counters;
1513 
1514 bool jvmci_counters_include(JavaThread* thread) {
1515   return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1516 }
1517 
1518 void JavaThread::collect_counters(typeArrayOop array) {
1519   if (JVMCICounterSize > 0) {
1520     JavaThreadIteratorWithHandle jtiwh;
1521     for (int i = 0; i < array->length(); i++) {
1522       array->long_at_put(i, _jvmci_old_thread_counters[i]);
1523     }
1524     for (; JavaThread *tp = jtiwh.next(); ) {
1525       if (jvmci_counters_include(tp)) {
1526         for (int i = 0; i < array->length(); i++) {
1527           array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1528         }
1529       }
1530     }
1531   }
1532 }
1533 
1534 #endif // INCLUDE_JVMCI
1535 
1536 // A JavaThread is a normal Java thread
1537 
1538 void JavaThread::initialize() {
1539   // Initialize fields
1540 
1541   set_saved_exception_pc(NULL);
1542   set_threadObj(NULL);
1543   _anchor.clear();
1544   set_entry_point(NULL);
1545   set_jni_functions(jni_functions());
1546   set_callee_target(NULL);
1547   set_vm_result(NULL);
1548   set_vm_result_2(NULL);
1549   set_vframe_array_head(NULL);
1550   set_vframe_array_last(NULL);
1551   set_deferred_locals(NULL);
1552   set_deopt_mark(NULL);
1553   set_deopt_compiled_method(NULL);
1554   clear_must_deopt_id();
1555   set_monitor_chunks(NULL);
1556   set_next(NULL);
1557   _on_thread_list = false;
1558   set_thread_state(_thread_new);
1559   _terminated = _not_terminated;
1560   _array_for_gc = NULL;
1561   _suspend_equivalent = false;
1562   _in_deopt_handler = 0;
1563   _doing_unsafe_access = false;
1564   _stack_guard_state = stack_guard_unused;
1565 #if INCLUDE_JVMCI
1566   _pending_monitorenter = false;
1567   _pending_deoptimization = -1;
1568   _pending_failed_speculation = 0;
1569   _pending_transfer_to_interpreter = false;
1570   _adjusting_comp_level = false;
1571   _in_retryable_allocation = false;
1572   _jvmci._alternate_call_target = NULL;
1573   assert(_jvmci._implicit_exception_pc == NULL, "must be");
1574   if (JVMCICounterSize > 0) {
1575     _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1576     memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1577   } else {
1578     _jvmci_counters = NULL;
1579   }
1580 #endif // INCLUDE_JVMCI
1581   _reserved_stack_activation = NULL;  // stack base not known yet
1582   (void)const_cast<oop&>(_exception_oop = oop(NULL));
1583   _exception_pc  = 0;
1584   _exception_handler_pc = 0;
1585   _is_method_handle_return = 0;
1586   _jvmti_thread_state= NULL;
1587   _should_post_on_exceptions_flag = JNI_FALSE;
1588   _interp_only_mode    = 0;
1589   _special_runtime_exit_condition = _no_async_condition;
1590   _pending_async_exception = NULL;
1591   _thread_stat = NULL;
1592   _thread_stat = new ThreadStatistics();
1593   _blocked_on_compilation = false;
1594   _jni_active_critical = 0;
1595   _pending_jni_exception_check_fn = NULL;
1596   _do_not_unlock_if_synchronized = false;
1597   _cached_monitor_info = NULL;
1598   _parker = Parker::Allocate(this);
1599 
1600 #ifndef PRODUCT
1601   _jmp_ring_index = 0;
1602   for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1603     record_jump(NULL, NULL, NULL, 0);
1604   }
1605 #endif // PRODUCT
1606 
1607   // Setup safepoint state info for this thread
1608   ThreadSafepointState::create(this);
1609 
1610   debug_only(_java_call_counter = 0);
1611 
1612   // JVMTI PopFrame support
1613   _popframe_condition = popframe_inactive;
1614   _popframe_preserved_args = NULL;
1615   _popframe_preserved_args_size = 0;
1616   _frames_to_pop_failed_realloc = 0;
1617 
1618   if (SafepointMechanism::uses_thread_local_poll()) {
1619     SafepointMechanism::initialize_header(this);
1620   }
1621 
1622   pd_initialize();
1623 }
1624 
1625 JavaThread::JavaThread(bool is_attaching_via_jni) :
1626                        Thread() {
1627   initialize();
1628   if (is_attaching_via_jni) {
1629     _jni_attach_state = _attaching_via_jni;
1630   } else {
1631     _jni_attach_state = _not_attaching_via_jni;
1632   }
1633   assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1634 }
1635 
1636 bool JavaThread::reguard_stack(address cur_sp) {
1637   if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1638       && _stack_guard_state != stack_guard_reserved_disabled) {
1639     return true; // Stack already guarded or guard pages not needed.
1640   }
1641 
1642   if (register_stack_overflow()) {
1643     // For those architectures which have separate register and
1644     // memory stacks, we must check the register stack to see if
1645     // it has overflowed.
1646     return false;
1647   }
1648 
1649   // Java code never executes within the yellow zone: the latter is only
1650   // there to provoke an exception during stack banging.  If java code
1651   // is executing there, either StackShadowPages should be larger, or
1652   // some exception code in c1, c2 or the interpreter isn't unwinding
1653   // when it should.
1654   guarantee(cur_sp > stack_reserved_zone_base(),
1655             "not enough space to reguard - increase StackShadowPages");
1656   if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1657     enable_stack_yellow_reserved_zone();
1658     if (reserved_stack_activation() != stack_base()) {
1659       set_reserved_stack_activation(stack_base());
1660     }
1661   } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1662     set_reserved_stack_activation(stack_base());
1663     enable_stack_reserved_zone();
1664   }
1665   return true;
1666 }
1667 
1668 bool JavaThread::reguard_stack(void) {
1669   return reguard_stack(os::current_stack_pointer());
1670 }
1671 
1672 
1673 void JavaThread::block_if_vm_exited() {
1674   if (_terminated == _vm_exited) {
1675     // _vm_exited is set at safepoint, and Threads_lock is never released
1676     // we will block here forever
1677     Threads_lock->lock_without_safepoint_check();
1678     ShouldNotReachHere();
1679   }
1680 }
1681 
1682 
1683 // Remove this ifdef when C1 is ported to the compiler interface.
1684 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1685 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1686 
1687 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1688                        Thread() {
1689   initialize();
1690   _jni_attach_state = _not_attaching_via_jni;
1691   set_entry_point(entry_point);
1692   // Create the native thread itself.
1693   // %note runtime_23
1694   os::ThreadType thr_type = os::java_thread;
1695   thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1696                                                      os::java_thread;
1697   os::create_thread(this, thr_type, stack_sz);
1698   // The _osthread may be NULL here because we ran out of memory (too many threads active).
1699   // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1700   // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1701   // the exception consists of creating the exception object & initializing it, initialization
1702   // will leave the VM via a JavaCall and then all locks must be unlocked).
1703   //
1704   // The thread is still suspended when we reach here. Thread must be explicit started
1705   // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1706   // by calling Threads:add. The reason why this is not done here, is because the thread
1707   // object must be fully initialized (take a look at JVM_Start)
1708 }
1709 
1710 JavaThread::~JavaThread() {
1711 
1712   // JSR166 -- return the parker to the free list
1713   Parker::Release(_parker);
1714   _parker = NULL;
1715 
1716   // Free any remaining  previous UnrollBlock
1717   vframeArray* old_array = vframe_array_last();
1718 
1719   if (old_array != NULL) {
1720     Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1721     old_array->set_unroll_block(NULL);
1722     delete old_info;
1723     delete old_array;
1724   }
1725 
1726   GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1727   if (deferred != NULL) {
1728     // This can only happen if thread is destroyed before deoptimization occurs.
1729     assert(deferred->length() != 0, "empty array!");
1730     do {
1731       jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1732       deferred->remove_at(0);
1733       // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1734       delete dlv;
1735     } while (deferred->length() != 0);
1736     delete deferred;
1737   }
1738 
1739   // All Java related clean up happens in exit
1740   ThreadSafepointState::destroy(this);
1741   if (_thread_stat != NULL) delete _thread_stat;
1742 
1743 #if INCLUDE_JVMCI
1744   if (JVMCICounterSize > 0) {
1745     if (jvmci_counters_include(this)) {
1746       for (int i = 0; i < JVMCICounterSize; i++) {
1747         _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1748       }
1749     }
1750     FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1751   }
1752 #endif // INCLUDE_JVMCI
1753 }
1754 
1755 
1756 // The first routine called by a new Java thread
1757 void JavaThread::run() {
1758   // initialize thread-local alloc buffer related fields
1759   this->initialize_tlab();
1760 
1761   // used to test validity of stack trace backs
1762   this->record_base_of_stack_pointer();
1763 
1764   this->create_stack_guard_pages();
1765 
1766   this->cache_global_variables();
1767 
1768   // Thread is now sufficient initialized to be handled by the safepoint code as being
1769   // in the VM. Change thread state from _thread_new to _thread_in_vm
1770   ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1771 
1772   assert(JavaThread::current() == this, "sanity check");
1773   assert(!Thread::current()->owns_locks(), "sanity check");
1774 
1775   DTRACE_THREAD_PROBE(start, this);
1776 
1777   // This operation might block. We call that after all safepoint checks for a new thread has
1778   // been completed.
1779   this->set_active_handles(JNIHandleBlock::allocate_block());
1780 
1781   if (JvmtiExport::should_post_thread_life()) {
1782     JvmtiExport::post_thread_start(this);
1783 
1784   }
1785 
1786   // We call another function to do the rest so we are sure that the stack addresses used
1787   // from there will be lower than the stack base just computed
1788   thread_main_inner();
1789 
1790   // Note, thread is no longer valid at this point!
1791 }
1792 
1793 
1794 void JavaThread::thread_main_inner() {
1795   assert(JavaThread::current() == this, "sanity check");
1796   assert(this->threadObj() != NULL, "just checking");
1797 
1798   // Execute thread entry point unless this thread has a pending exception
1799   // or has been stopped before starting.
1800   // Note: Due to JVM_StopThread we can have pending exceptions already!
1801   if (!this->has_pending_exception() &&
1802       !java_lang_Thread::is_stillborn(this->threadObj())) {
1803     {
1804       ResourceMark rm(this);
1805       this->set_native_thread_name(this->get_thread_name());
1806     }
1807     HandleMark hm(this);
1808     this->entry_point()(this, this);
1809   }
1810 
1811   DTRACE_THREAD_PROBE(stop, this);
1812 
1813   this->exit(false);
1814   this->smr_delete();
1815 }
1816 
1817 
1818 static void ensure_join(JavaThread* thread) {
1819   // We do not need to grab the Threads_lock, since we are operating on ourself.
1820   Handle threadObj(thread, thread->threadObj());
1821   assert(threadObj.not_null(), "java thread object must exist");
1822   ObjectLocker lock(threadObj, thread);
1823   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1824   thread->clear_pending_exception();
1825   // Thread is exiting. So set thread_status field in  java.lang.Thread class to TERMINATED.
1826   java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1827   // Clear the native thread instance - this makes isAlive return false and allows the join()
1828   // to complete once we've done the notify_all below
1829   java_lang_Thread::set_thread(threadObj(), NULL);
1830   lock.notify_all(thread);
1831   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1832   thread->clear_pending_exception();
1833 }
1834 
1835 static bool is_daemon(oop threadObj) {
1836   return (threadObj != NULL && java_lang_Thread::is_daemon(threadObj));
1837 }
1838 
1839 // For any new cleanup additions, please check to see if they need to be applied to
1840 // cleanup_failed_attach_current_thread as well.
1841 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1842   assert(this == JavaThread::current(), "thread consistency check");
1843 
1844   elapsedTimer _timer_exit_phase1;
1845   elapsedTimer _timer_exit_phase2;
1846   elapsedTimer _timer_exit_phase3;
1847   elapsedTimer _timer_exit_phase4;
1848 
1849   if (log_is_enabled(Debug, os, thread, timer)) {
1850     _timer_exit_phase1.start();
1851   }
1852 
1853   HandleMark hm(this);
1854   Handle uncaught_exception(this, this->pending_exception());
1855   this->clear_pending_exception();
1856   Handle threadObj(this, this->threadObj());
1857   assert(threadObj.not_null(), "Java thread object should be created");
1858 
1859   // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1860   {
1861     EXCEPTION_MARK;
1862 
1863     CLEAR_PENDING_EXCEPTION;
1864   }
1865   if (!destroy_vm) {
1866     if (uncaught_exception.not_null()) {
1867       EXCEPTION_MARK;
1868       // Call method Thread.dispatchUncaughtException().
1869       Klass* thread_klass = SystemDictionary::Thread_klass();
1870       JavaValue result(T_VOID);
1871       JavaCalls::call_virtual(&result,
1872                               threadObj, thread_klass,
1873                               vmSymbols::dispatchUncaughtException_name(),
1874                               vmSymbols::throwable_void_signature(),
1875                               uncaught_exception,
1876                               THREAD);
1877       if (HAS_PENDING_EXCEPTION) {
1878         ResourceMark rm(this);
1879         jio_fprintf(defaultStream::error_stream(),
1880                     "\nException: %s thrown from the UncaughtExceptionHandler"
1881                     " in thread \"%s\"\n",
1882                     pending_exception()->klass()->external_name(),
1883                     get_thread_name());
1884         CLEAR_PENDING_EXCEPTION;
1885       }
1886     }
1887     JFR_ONLY(Jfr::on_java_thread_dismantle(this);)
1888 
1889     // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1890     // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1891     // is deprecated anyhow.
1892     if (!is_Compiler_thread()) {
1893       int count = 3;
1894       while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1895         EXCEPTION_MARK;
1896         JavaValue result(T_VOID);
1897         Klass* thread_klass = SystemDictionary::Thread_klass();
1898         JavaCalls::call_virtual(&result,
1899                                 threadObj, thread_klass,
1900                                 vmSymbols::exit_method_name(),
1901                                 vmSymbols::void_method_signature(),
1902                                 THREAD);
1903         CLEAR_PENDING_EXCEPTION;
1904       }
1905     }
1906     // notify JVMTI
1907     if (JvmtiExport::should_post_thread_life()) {
1908       JvmtiExport::post_thread_end(this);
1909     }
1910 
1911     // We have notified the agents that we are exiting, before we go on,
1912     // we must check for a pending external suspend request and honor it
1913     // in order to not surprise the thread that made the suspend request.
1914     while (true) {
1915       {
1916         MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1917         if (!is_external_suspend()) {
1918           set_terminated(_thread_exiting);
1919           ThreadService::current_thread_exiting(this, is_daemon(threadObj()));
1920           break;
1921         }
1922         // Implied else:
1923         // Things get a little tricky here. We have a pending external
1924         // suspend request, but we are holding the SR_lock so we
1925         // can't just self-suspend. So we temporarily drop the lock
1926         // and then self-suspend.
1927       }
1928 
1929       ThreadBlockInVM tbivm(this);
1930       java_suspend_self();
1931 
1932       // We're done with this suspend request, but we have to loop around
1933       // and check again. Eventually we will get SR_lock without a pending
1934       // external suspend request and will be able to mark ourselves as
1935       // exiting.
1936     }
1937     // no more external suspends are allowed at this point
1938   } else {
1939     assert(!is_terminated() && !is_exiting(), "must not be exiting");
1940     // before_exit() has already posted JVMTI THREAD_END events
1941   }
1942 
1943   if (log_is_enabled(Debug, os, thread, timer)) {
1944     _timer_exit_phase1.stop();
1945     _timer_exit_phase2.start();
1946   }
1947   // Notify waiters on thread object. This has to be done after exit() is called
1948   // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1949   // group should have the destroyed bit set before waiters are notified).
1950   ensure_join(this);
1951   assert(!this->has_pending_exception(), "ensure_join should have cleared");
1952 
1953   if (log_is_enabled(Debug, os, thread, timer)) {
1954     _timer_exit_phase2.stop();
1955     _timer_exit_phase3.start();
1956   }
1957   // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1958   // held by this thread must be released. The spec does not distinguish
1959   // between JNI-acquired and regular Java monitors. We can only see
1960   // regular Java monitors here if monitor enter-exit matching is broken.
1961   //
1962   // ensure_join() ignores IllegalThreadStateExceptions, and so does
1963   // ObjectSynchronizer::release_monitors_owned_by_thread().
1964   if (exit_type == jni_detach) {
1965     // Sanity check even though JNI DetachCurrentThread() would have
1966     // returned JNI_ERR if there was a Java frame. JavaThread exit
1967     // should be done executing Java code by the time we get here.
1968     assert(!this->has_last_Java_frame(),
1969            "should not have a Java frame when detaching or exiting");
1970     ObjectSynchronizer::release_monitors_owned_by_thread(this);
1971     assert(!this->has_pending_exception(), "release_monitors should have cleared");
1972   }
1973 
1974   // These things needs to be done while we are still a Java Thread. Make sure that thread
1975   // is in a consistent state, in case GC happens
1976   JFR_ONLY(Jfr::on_thread_exit(this);)
1977 
1978   if (active_handles() != NULL) {
1979     JNIHandleBlock* block = active_handles();
1980     set_active_handles(NULL);
1981     JNIHandleBlock::release_block(block);
1982   }
1983 
1984   if (free_handle_block() != NULL) {
1985     JNIHandleBlock* block = free_handle_block();
1986     set_free_handle_block(NULL);
1987     JNIHandleBlock::release_block(block);
1988   }
1989 
1990   // These have to be removed while this is still a valid thread.
1991   remove_stack_guard_pages();
1992 
1993   if (UseTLAB) {
1994     tlab().retire();
1995   }
1996 
1997   if (JvmtiEnv::environments_might_exist()) {
1998     JvmtiExport::cleanup_thread(this);
1999   }
2000 
2001   // We must flush any deferred card marks and other various GC barrier
2002   // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer)
2003   // before removing a thread from the list of active threads.
2004   BarrierSet::barrier_set()->on_thread_detach(this);
2005 
2006   log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
2007     exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
2008     os::current_thread_id());
2009 
2010   if (log_is_enabled(Debug, os, thread, timer)) {
2011     _timer_exit_phase3.stop();
2012     _timer_exit_phase4.start();
2013   }
2014   // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
2015   Threads::remove(this);
2016 
2017   if (log_is_enabled(Debug, os, thread, timer)) {
2018     _timer_exit_phase4.stop();
2019     ResourceMark rm(this);
2020     log_debug(os, thread, timer)("name='%s'"
2021                                  ", exit-phase1=" JLONG_FORMAT
2022                                  ", exit-phase2=" JLONG_FORMAT
2023                                  ", exit-phase3=" JLONG_FORMAT
2024                                  ", exit-phase4=" JLONG_FORMAT,
2025                                  get_thread_name(),
2026                                  _timer_exit_phase1.milliseconds(),
2027                                  _timer_exit_phase2.milliseconds(),
2028                                  _timer_exit_phase3.milliseconds(),
2029                                  _timer_exit_phase4.milliseconds());
2030   }
2031 }
2032 
2033 void JavaThread::cleanup_failed_attach_current_thread() {
2034   if (active_handles() != NULL) {
2035     JNIHandleBlock* block = active_handles();
2036     set_active_handles(NULL);
2037     JNIHandleBlock::release_block(block);
2038   }
2039 
2040   if (free_handle_block() != NULL) {
2041     JNIHandleBlock* block = free_handle_block();
2042     set_free_handle_block(NULL);
2043     JNIHandleBlock::release_block(block);
2044   }
2045 
2046   // These have to be removed while this is still a valid thread.
2047   remove_stack_guard_pages();
2048 
2049   if (UseTLAB) {
2050     tlab().retire();
2051   }
2052 
2053   BarrierSet::barrier_set()->on_thread_detach(this);
2054 
2055   Threads::remove(this);
2056   this->smr_delete();
2057 }
2058 
2059 JavaThread* JavaThread::active() {
2060   Thread* thread = Thread::current();
2061   if (thread->is_Java_thread()) {
2062     return (JavaThread*) thread;
2063   } else {
2064     assert(thread->is_VM_thread(), "this must be a vm thread");
2065     VM_Operation* op = ((VMThread*) thread)->vm_operation();
2066     JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2067     assert(ret->is_Java_thread(), "must be a Java thread");
2068     return ret;
2069   }
2070 }
2071 
2072 bool JavaThread::is_lock_owned(address adr) const {
2073   if (Thread::is_lock_owned(adr)) return true;
2074 
2075   for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2076     if (chunk->contains(adr)) return true;
2077   }
2078 
2079   return false;
2080 }
2081 
2082 
2083 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2084   chunk->set_next(monitor_chunks());
2085   set_monitor_chunks(chunk);
2086 }
2087 
2088 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2089   guarantee(monitor_chunks() != NULL, "must be non empty");
2090   if (monitor_chunks() == chunk) {
2091     set_monitor_chunks(chunk->next());
2092   } else {
2093     MonitorChunk* prev = monitor_chunks();
2094     while (prev->next() != chunk) prev = prev->next();
2095     prev->set_next(chunk->next());
2096   }
2097 }
2098 
2099 // JVM support.
2100 
2101 // Note: this function shouldn't block if it's called in
2102 // _thread_in_native_trans state (such as from
2103 // check_special_condition_for_native_trans()).
2104 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2105 
2106   if (has_last_Java_frame() && has_async_condition()) {
2107     // If we are at a polling page safepoint (not a poll return)
2108     // then we must defer async exception because live registers
2109     // will be clobbered by the exception path. Poll return is
2110     // ok because the call we a returning from already collides
2111     // with exception handling registers and so there is no issue.
2112     // (The exception handling path kills call result registers but
2113     //  this is ok since the exception kills the result anyway).
2114 
2115     if (is_at_poll_safepoint()) {
2116       // if the code we are returning to has deoptimized we must defer
2117       // the exception otherwise live registers get clobbered on the
2118       // exception path before deoptimization is able to retrieve them.
2119       //
2120       RegisterMap map(this, false);
2121       frame caller_fr = last_frame().sender(&map);
2122       assert(caller_fr.is_compiled_frame(), "what?");
2123       if (caller_fr.is_deoptimized_frame()) {
2124         log_info(exceptions)("deferred async exception at compiled safepoint");
2125         return;
2126       }
2127     }
2128   }
2129 
2130   JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2131   if (condition == _no_async_condition) {
2132     // Conditions have changed since has_special_runtime_exit_condition()
2133     // was called:
2134     // - if we were here only because of an external suspend request,
2135     //   then that was taken care of above (or cancelled) so we are done
2136     // - if we were here because of another async request, then it has
2137     //   been cleared between the has_special_runtime_exit_condition()
2138     //   and now so again we are done
2139     return;
2140   }
2141 
2142   // Check for pending async. exception
2143   if (_pending_async_exception != NULL) {
2144     // Only overwrite an already pending exception, if it is not a threadDeath.
2145     if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2146 
2147       // We cannot call Exceptions::_throw(...) here because we cannot block
2148       set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2149 
2150       LogTarget(Info, exceptions) lt;
2151       if (lt.is_enabled()) {
2152         ResourceMark rm;
2153         LogStream ls(lt);
2154         ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2155           if (has_last_Java_frame()) {
2156             frame f = last_frame();
2157            ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2158           }
2159         ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2160       }
2161       _pending_async_exception = NULL;
2162       clear_has_async_exception();
2163     }
2164   }
2165 
2166   if (check_unsafe_error &&
2167       condition == _async_unsafe_access_error && !has_pending_exception()) {
2168     condition = _no_async_condition;  // done
2169     switch (thread_state()) {
2170     case _thread_in_vm: {
2171       JavaThread* THREAD = this;
2172       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2173     }
2174     case _thread_in_native: {
2175       ThreadInVMfromNative tiv(this);
2176       JavaThread* THREAD = this;
2177       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2178     }
2179     case _thread_in_Java: {
2180       ThreadInVMfromJava tiv(this);
2181       JavaThread* THREAD = this;
2182       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2183     }
2184     default:
2185       ShouldNotReachHere();
2186     }
2187   }
2188 
2189   assert(condition == _no_async_condition || has_pending_exception() ||
2190          (!check_unsafe_error && condition == _async_unsafe_access_error),
2191          "must have handled the async condition, if no exception");
2192 }
2193 
2194 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2195   //
2196   // Check for pending external suspend. Internal suspend requests do
2197   // not use handle_special_runtime_exit_condition().
2198   // If JNIEnv proxies are allowed, don't self-suspend if the target
2199   // thread is not the current thread. In older versions of jdbx, jdbx
2200   // threads could call into the VM with another thread's JNIEnv so we
2201   // can be here operating on behalf of a suspended thread (4432884).
2202   bool do_self_suspend = is_external_suspend_with_lock();
2203   if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2204     //
2205     // Because thread is external suspended the safepoint code will count
2206     // thread as at a safepoint. This can be odd because we can be here
2207     // as _thread_in_Java which would normally transition to _thread_blocked
2208     // at a safepoint. We would like to mark the thread as _thread_blocked
2209     // before calling java_suspend_self like all other callers of it but
2210     // we must then observe proper safepoint protocol. (We can't leave
2211     // _thread_blocked with a safepoint in progress). However we can be
2212     // here as _thread_in_native_trans so we can't use a normal transition
2213     // constructor/destructor pair because they assert on that type of
2214     // transition. We could do something like:
2215     //
2216     // JavaThreadState state = thread_state();
2217     // set_thread_state(_thread_in_vm);
2218     // {
2219     //   ThreadBlockInVM tbivm(this);
2220     //   java_suspend_self()
2221     // }
2222     // set_thread_state(_thread_in_vm_trans);
2223     // if (safepoint) block;
2224     // set_thread_state(state);
2225     //
2226     // but that is pretty messy. Instead we just go with the way the
2227     // code has worked before and note that this is the only path to
2228     // java_suspend_self that doesn't put the thread in _thread_blocked
2229     // mode.
2230 
2231     frame_anchor()->make_walkable(this);
2232     java_suspend_self();
2233 
2234     // We might be here for reasons in addition to the self-suspend request
2235     // so check for other async requests.
2236   }
2237 
2238   if (check_asyncs) {
2239     check_and_handle_async_exceptions();
2240   }
2241 
2242   JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);)
2243 }
2244 
2245 void JavaThread::send_thread_stop(oop java_throwable)  {
2246   assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2247   assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2248   assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2249 
2250   // Do not throw asynchronous exceptions against the compiler thread
2251   // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2252   if (!can_call_java()) return;
2253 
2254   {
2255     // Actually throw the Throwable against the target Thread - however
2256     // only if there is no thread death exception installed already.
2257     if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2258       // If the topmost frame is a runtime stub, then we are calling into
2259       // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2260       // must deoptimize the caller before continuing, as the compiled  exception handler table
2261       // may not be valid
2262       if (has_last_Java_frame()) {
2263         frame f = last_frame();
2264         if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2265           // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2266           RegisterMap reg_map(this, UseBiasedLocking);
2267           frame compiled_frame = f.sender(&reg_map);
2268           if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2269             Deoptimization::deoptimize(this, compiled_frame, &reg_map);
2270           }
2271         }
2272       }
2273 
2274       // Set async. pending exception in thread.
2275       set_pending_async_exception(java_throwable);
2276 
2277       if (log_is_enabled(Info, exceptions)) {
2278          ResourceMark rm;
2279         log_info(exceptions)("Pending Async. exception installed of type: %s",
2280                              InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2281       }
2282       // for AbortVMOnException flag
2283       Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2284     }
2285   }
2286 
2287 
2288   // Interrupt thread so it will wake up from a potential wait()
2289   Thread::interrupt(this);
2290 }
2291 
2292 // External suspension mechanism.
2293 //
2294 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2295 // to any VM_locks and it is at a transition
2296 // Self-suspension will happen on the transition out of the vm.
2297 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2298 //
2299 // Guarantees on return:
2300 //   + Target thread will not execute any new bytecode (that's why we need to
2301 //     force a safepoint)
2302 //   + Target thread will not enter any new monitors
2303 //
2304 void JavaThread::java_suspend() {
2305   ThreadsListHandle tlh;
2306   if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) {
2307     return;
2308   }
2309 
2310   { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2311     if (!is_external_suspend()) {
2312       // a racing resume has cancelled us; bail out now
2313       return;
2314     }
2315 
2316     // suspend is done
2317     uint32_t debug_bits = 0;
2318     // Warning: is_ext_suspend_completed() may temporarily drop the
2319     // SR_lock to allow the thread to reach a stable thread state if
2320     // it is currently in a transient thread state.
2321     if (is_ext_suspend_completed(false /* !called_by_wait */,
2322                                  SuspendRetryDelay, &debug_bits)) {
2323       return;
2324     }
2325   }
2326 
2327   VM_ThreadSuspend vm_suspend;
2328   VMThread::execute(&vm_suspend);
2329 }
2330 
2331 // Part II of external suspension.
2332 // A JavaThread self suspends when it detects a pending external suspend
2333 // request. This is usually on transitions. It is also done in places
2334 // where continuing to the next transition would surprise the caller,
2335 // e.g., monitor entry.
2336 //
2337 // Returns the number of times that the thread self-suspended.
2338 //
2339 // Note: DO NOT call java_suspend_self() when you just want to block current
2340 //       thread. java_suspend_self() is the second stage of cooperative
2341 //       suspension for external suspend requests and should only be used
2342 //       to complete an external suspend request.
2343 //
2344 int JavaThread::java_suspend_self() {
2345   int ret = 0;
2346 
2347   // we are in the process of exiting so don't suspend
2348   if (is_exiting()) {
2349     clear_external_suspend();
2350     return ret;
2351   }
2352 
2353   assert(_anchor.walkable() ||
2354          (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2355          "must have walkable stack");
2356 
2357   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2358 
2359   assert(!this->is_ext_suspended(),
2360          "a thread trying to self-suspend should not already be suspended");
2361 
2362   if (this->is_suspend_equivalent()) {
2363     // If we are self-suspending as a result of the lifting of a
2364     // suspend equivalent condition, then the suspend_equivalent
2365     // flag is not cleared until we set the ext_suspended flag so
2366     // that wait_for_ext_suspend_completion() returns consistent
2367     // results.
2368     this->clear_suspend_equivalent();
2369   }
2370 
2371   // A racing resume may have cancelled us before we grabbed SR_lock
2372   // above. Or another external suspend request could be waiting for us
2373   // by the time we return from SR_lock()->wait(). The thread
2374   // that requested the suspension may already be trying to walk our
2375   // stack and if we return now, we can change the stack out from under
2376   // it. This would be a "bad thing (TM)" and cause the stack walker
2377   // to crash. We stay self-suspended until there are no more pending
2378   // external suspend requests.
2379   while (is_external_suspend()) {
2380     ret++;
2381     this->set_ext_suspended();
2382 
2383     // _ext_suspended flag is cleared by java_resume()
2384     while (is_ext_suspended()) {
2385       this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2386     }
2387   }
2388 
2389   return ret;
2390 }
2391 
2392 #ifdef ASSERT
2393 // Verify the JavaThread has not yet been published in the Threads::list, and
2394 // hence doesn't need protection from concurrent access at this stage.
2395 void JavaThread::verify_not_published() {
2396   // Cannot create a ThreadsListHandle here and check !tlh.includes(this)
2397   // since an unpublished JavaThread doesn't participate in the
2398   // Thread-SMR protocol for keeping a ThreadsList alive.
2399   assert(!on_thread_list(), "JavaThread shouldn't have been published yet!");
2400 }
2401 #endif
2402 
2403 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2404 // progress or when _suspend_flags is non-zero.
2405 // Current thread needs to self-suspend if there is a suspend request and/or
2406 // block if a safepoint is in progress.
2407 // Async exception ISN'T checked.
2408 // Note only the ThreadInVMfromNative transition can call this function
2409 // directly and when thread state is _thread_in_native_trans
2410 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2411   assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2412 
2413   JavaThread *curJT = JavaThread::current();
2414   bool do_self_suspend = thread->is_external_suspend();
2415 
2416   assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2417 
2418   // If JNIEnv proxies are allowed, don't self-suspend if the target
2419   // thread is not the current thread. In older versions of jdbx, jdbx
2420   // threads could call into the VM with another thread's JNIEnv so we
2421   // can be here operating on behalf of a suspended thread (4432884).
2422   if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2423     JavaThreadState state = thread->thread_state();
2424 
2425     // We mark this thread_blocked state as a suspend-equivalent so
2426     // that a caller to is_ext_suspend_completed() won't be confused.
2427     // The suspend-equivalent state is cleared by java_suspend_self().
2428     thread->set_suspend_equivalent();
2429 
2430     // If the safepoint code sees the _thread_in_native_trans state, it will
2431     // wait until the thread changes to other thread state. There is no
2432     // guarantee on how soon we can obtain the SR_lock and complete the
2433     // self-suspend request. It would be a bad idea to let safepoint wait for
2434     // too long. Temporarily change the state to _thread_blocked to
2435     // let the VM thread know that this thread is ready for GC. The problem
2436     // of changing thread state is that safepoint could happen just after
2437     // java_suspend_self() returns after being resumed, and VM thread will
2438     // see the _thread_blocked state. We must check for safepoint
2439     // after restoring the state and make sure we won't leave while a safepoint
2440     // is in progress.
2441     thread->set_thread_state(_thread_blocked);
2442     thread->java_suspend_self();
2443     thread->set_thread_state(state);
2444 
2445     InterfaceSupport::serialize_thread_state_with_handler(thread);
2446   }
2447 
2448   SafepointMechanism::block_if_requested(curJT);
2449 
2450   if (thread->is_deopt_suspend()) {
2451     thread->clear_deopt_suspend();
2452     RegisterMap map(thread, false);
2453     frame f = thread->last_frame();
2454     while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2455       f = f.sender(&map);
2456     }
2457     if (f.id() == thread->must_deopt_id()) {
2458       thread->clear_must_deopt_id();
2459       f.deoptimize(thread);
2460     } else {
2461       fatal("missed deoptimization!");
2462     }
2463   }
2464 
2465   JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(thread);)
2466 }
2467 
2468 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2469 // progress or when _suspend_flags is non-zero.
2470 // Current thread needs to self-suspend if there is a suspend request and/or
2471 // block if a safepoint is in progress.
2472 // Also check for pending async exception (not including unsafe access error).
2473 // Note only the native==>VM/Java barriers can call this function and when
2474 // thread state is _thread_in_native_trans.
2475 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2476   check_safepoint_and_suspend_for_native_trans(thread);
2477 
2478   if (thread->has_async_exception()) {
2479     // We are in _thread_in_native_trans state, don't handle unsafe
2480     // access error since that may block.
2481     thread->check_and_handle_async_exceptions(false);
2482   }
2483 }
2484 
2485 // This is a variant of the normal
2486 // check_special_condition_for_native_trans with slightly different
2487 // semantics for use by critical native wrappers.  It does all the
2488 // normal checks but also performs the transition back into
2489 // thread_in_Java state.  This is required so that critical natives
2490 // can potentially block and perform a GC if they are the last thread
2491 // exiting the GCLocker.
2492 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2493   check_special_condition_for_native_trans(thread);
2494 
2495   // Finish the transition
2496   thread->set_thread_state(_thread_in_Java);
2497 
2498   if (thread->do_critical_native_unlock()) {
2499     ThreadInVMfromJavaNoAsyncException tiv(thread);
2500     GCLocker::unlock_critical(thread);
2501     thread->clear_critical_native_unlock();
2502   }
2503 }
2504 
2505 // We need to guarantee the Threads_lock here, since resumes are not
2506 // allowed during safepoint synchronization
2507 // Can only resume from an external suspension
2508 void JavaThread::java_resume() {
2509   assert_locked_or_safepoint(Threads_lock);
2510 
2511   // Sanity check: thread is gone, has started exiting or the thread
2512   // was not externally suspended.
2513   ThreadsListHandle tlh;
2514   if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) {
2515     return;
2516   }
2517 
2518   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2519 
2520   clear_external_suspend();
2521 
2522   if (is_ext_suspended()) {
2523     clear_ext_suspended();
2524     SR_lock()->notify_all();
2525   }
2526 }
2527 
2528 size_t JavaThread::_stack_red_zone_size = 0;
2529 size_t JavaThread::_stack_yellow_zone_size = 0;
2530 size_t JavaThread::_stack_reserved_zone_size = 0;
2531 size_t JavaThread::_stack_shadow_zone_size = 0;
2532 
2533 void JavaThread::create_stack_guard_pages() {
2534   if (!os::uses_stack_guard_pages() ||
2535       _stack_guard_state != stack_guard_unused ||
2536       (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) {
2537       log_info(os, thread)("Stack guard page creation for thread "
2538                            UINTX_FORMAT " disabled", os::current_thread_id());
2539     return;
2540   }
2541   address low_addr = stack_end();
2542   size_t len = stack_guard_zone_size();
2543 
2544   assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2545   assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2546 
2547   int must_commit = os::must_commit_stack_guard_pages();
2548   // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2549 
2550   if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2551     log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2552     return;
2553   }
2554 
2555   if (os::guard_memory((char *) low_addr, len)) {
2556     _stack_guard_state = stack_guard_enabled;
2557   } else {
2558     log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2559       PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2560     if (os::uncommit_memory((char *) low_addr, len)) {
2561       log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2562     }
2563     return;
2564   }
2565 
2566   log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2567     PTR_FORMAT "-" PTR_FORMAT ".",
2568     os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2569 }
2570 
2571 void JavaThread::remove_stack_guard_pages() {
2572   assert(Thread::current() == this, "from different thread");
2573   if (_stack_guard_state == stack_guard_unused) return;
2574   address low_addr = stack_end();
2575   size_t len = stack_guard_zone_size();
2576 
2577   if (os::must_commit_stack_guard_pages()) {
2578     if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2579       _stack_guard_state = stack_guard_unused;
2580     } else {
2581       log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2582         PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2583       return;
2584     }
2585   } else {
2586     if (_stack_guard_state == stack_guard_unused) return;
2587     if (os::unguard_memory((char *) low_addr, len)) {
2588       _stack_guard_state = stack_guard_unused;
2589     } else {
2590       log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2591         PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2592       return;
2593     }
2594   }
2595 
2596   log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2597     PTR_FORMAT "-" PTR_FORMAT ".",
2598     os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2599 }
2600 
2601 void JavaThread::enable_stack_reserved_zone() {
2602   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2603   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2604 
2605   // The base notation is from the stack's point of view, growing downward.
2606   // We need to adjust it to work correctly with guard_memory()
2607   address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2608 
2609   guarantee(base < stack_base(),"Error calculating stack reserved zone");
2610   guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2611 
2612   if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2613     _stack_guard_state = stack_guard_enabled;
2614   } else {
2615     warning("Attempt to guard stack reserved zone failed.");
2616   }
2617   enable_register_stack_guard();
2618 }
2619 
2620 void JavaThread::disable_stack_reserved_zone() {
2621   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2622   assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2623 
2624   // Simply return if called for a thread that does not use guard pages.
2625   if (_stack_guard_state == stack_guard_unused) return;
2626 
2627   // The base notation is from the stack's point of view, growing downward.
2628   // We need to adjust it to work correctly with guard_memory()
2629   address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2630 
2631   if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2632     _stack_guard_state = stack_guard_reserved_disabled;
2633   } else {
2634     warning("Attempt to unguard stack reserved zone failed.");
2635   }
2636   disable_register_stack_guard();
2637 }
2638 
2639 void JavaThread::enable_stack_yellow_reserved_zone() {
2640   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2641   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2642 
2643   // The base notation is from the stacks point of view, growing downward.
2644   // We need to adjust it to work correctly with guard_memory()
2645   address base = stack_red_zone_base();
2646 
2647   guarantee(base < stack_base(), "Error calculating stack yellow zone");
2648   guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2649 
2650   if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2651     _stack_guard_state = stack_guard_enabled;
2652   } else {
2653     warning("Attempt to guard stack yellow zone failed.");
2654   }
2655   enable_register_stack_guard();
2656 }
2657 
2658 void JavaThread::disable_stack_yellow_reserved_zone() {
2659   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2660   assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2661 
2662   // Simply return if called for a thread that does not use guard pages.
2663   if (_stack_guard_state == stack_guard_unused) return;
2664 
2665   // The base notation is from the stacks point of view, growing downward.
2666   // We need to adjust it to work correctly with guard_memory()
2667   address base = stack_red_zone_base();
2668 
2669   if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2670     _stack_guard_state = stack_guard_yellow_reserved_disabled;
2671   } else {
2672     warning("Attempt to unguard stack yellow zone failed.");
2673   }
2674   disable_register_stack_guard();
2675 }
2676 
2677 void JavaThread::enable_stack_red_zone() {
2678   // The base notation is from the stacks point of view, growing downward.
2679   // We need to adjust it to work correctly with guard_memory()
2680   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2681   address base = stack_red_zone_base() - stack_red_zone_size();
2682 
2683   guarantee(base < stack_base(), "Error calculating stack red zone");
2684   guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2685 
2686   if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2687     warning("Attempt to guard stack red zone failed.");
2688   }
2689 }
2690 
2691 void JavaThread::disable_stack_red_zone() {
2692   // The base notation is from the stacks point of view, growing downward.
2693   // We need to adjust it to work correctly with guard_memory()
2694   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2695   address base = stack_red_zone_base() - stack_red_zone_size();
2696   if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2697     warning("Attempt to unguard stack red zone failed.");
2698   }
2699 }
2700 
2701 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2702   // ignore is there is no stack
2703   if (!has_last_Java_frame()) return;
2704   // traverse the stack frames. Starts from top frame.
2705   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2706     frame* fr = fst.current();
2707     f(fr, fst.register_map());
2708   }
2709 }
2710 
2711 
2712 #ifndef PRODUCT
2713 // Deoptimization
2714 // Function for testing deoptimization
2715 void JavaThread::deoptimize() {
2716   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2717   StackFrameStream fst(this, UseBiasedLocking);
2718   bool deopt = false;           // Dump stack only if a deopt actually happens.
2719   bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2720   // Iterate over all frames in the thread and deoptimize
2721   for (; !fst.is_done(); fst.next()) {
2722     if (fst.current()->can_be_deoptimized()) {
2723 
2724       if (only_at) {
2725         // Deoptimize only at particular bcis.  DeoptimizeOnlyAt
2726         // consists of comma or carriage return separated numbers so
2727         // search for the current bci in that string.
2728         address pc = fst.current()->pc();
2729         nmethod* nm =  (nmethod*) fst.current()->cb();
2730         ScopeDesc* sd = nm->scope_desc_at(pc);
2731         char buffer[8];
2732         jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2733         size_t len = strlen(buffer);
2734         const char * found = strstr(DeoptimizeOnlyAt, buffer);
2735         while (found != NULL) {
2736           if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2737               (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2738             // Check that the bci found is bracketed by terminators.
2739             break;
2740           }
2741           found = strstr(found + 1, buffer);
2742         }
2743         if (!found) {
2744           continue;
2745         }
2746       }
2747 
2748       if (DebugDeoptimization && !deopt) {
2749         deopt = true; // One-time only print before deopt
2750         tty->print_cr("[BEFORE Deoptimization]");
2751         trace_frames();
2752         trace_stack();
2753       }
2754       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2755     }
2756   }
2757 
2758   if (DebugDeoptimization && deopt) {
2759     tty->print_cr("[AFTER Deoptimization]");
2760     trace_frames();
2761   }
2762 }
2763 
2764 
2765 // Make zombies
2766 void JavaThread::make_zombies() {
2767   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2768     if (fst.current()->can_be_deoptimized()) {
2769       // it is a Java nmethod
2770       nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2771       nm->make_not_entrant();
2772     }
2773   }
2774 }
2775 #endif // PRODUCT
2776 
2777 
2778 void JavaThread::deoptimized_wrt_marked_nmethods() {
2779   if (!has_last_Java_frame()) return;
2780   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2781   StackFrameStream fst(this, UseBiasedLocking);
2782   for (; !fst.is_done(); fst.next()) {
2783     if (fst.current()->should_be_deoptimized()) {
2784       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2785     }
2786   }
2787 }
2788 
2789 
2790 // If the caller is a NamedThread, then remember, in the current scope,
2791 // the given JavaThread in its _processed_thread field.
2792 class RememberProcessedThread: public StackObj {
2793   NamedThread* _cur_thr;
2794  public:
2795   RememberProcessedThread(JavaThread* jthr) {
2796     Thread* thread = Thread::current();
2797     if (thread->is_Named_thread()) {
2798       _cur_thr = (NamedThread *)thread;
2799       _cur_thr->set_processed_thread(jthr);
2800     } else {
2801       _cur_thr = NULL;
2802     }
2803   }
2804 
2805   ~RememberProcessedThread() {
2806     if (_cur_thr) {
2807       _cur_thr->set_processed_thread(NULL);
2808     }
2809   }
2810 };
2811 
2812 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2813   // Verify that the deferred card marks have been flushed.
2814   assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2815 
2816   // Traverse the GCHandles
2817   Thread::oops_do(f, cf);
2818 
2819   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2820          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2821 
2822   if (has_last_Java_frame()) {
2823     // Record JavaThread to GC thread
2824     RememberProcessedThread rpt(this);
2825 
2826     // traverse the registered growable array
2827     if (_array_for_gc != NULL) {
2828       for (int index = 0; index < _array_for_gc->length(); index++) {
2829         f->do_oop(_array_for_gc->adr_at(index));
2830       }
2831     }
2832 
2833     // Traverse the monitor chunks
2834     for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2835       chunk->oops_do(f);
2836     }
2837 
2838     // Traverse the execution stack
2839     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2840       fst.current()->oops_do(f, cf, fst.register_map());
2841     }
2842   }
2843 
2844   // callee_target is never live across a gc point so NULL it here should
2845   // it still contain a methdOop.
2846 
2847   set_callee_target(NULL);
2848 
2849   assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2850   // If we have deferred set_locals there might be oops waiting to be
2851   // written
2852   GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2853   if (list != NULL) {
2854     for (int i = 0; i < list->length(); i++) {
2855       list->at(i)->oops_do(f);
2856     }
2857   }
2858 
2859   // Traverse instance variables at the end since the GC may be moving things
2860   // around using this function
2861   f->do_oop((oop*) &_threadObj);
2862   f->do_oop((oop*) &_vm_result);
2863   f->do_oop((oop*) &_exception_oop);
2864   f->do_oop((oop*) &_pending_async_exception);
2865 
2866   if (jvmti_thread_state() != NULL) {
2867     jvmti_thread_state()->oops_do(f);
2868   }
2869 }
2870 
2871 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2872   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2873          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2874 
2875   if (has_last_Java_frame()) {
2876     // Traverse the execution stack
2877     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2878       fst.current()->nmethods_do(cf);
2879     }
2880   }
2881 }
2882 
2883 void JavaThread::metadata_do(void f(Metadata*)) {
2884   if (has_last_Java_frame()) {
2885     // Traverse the execution stack to call f() on the methods in the stack
2886     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2887       fst.current()->metadata_do(f);
2888     }
2889   } else if (is_Compiler_thread()) {
2890     // need to walk ciMetadata in current compile tasks to keep alive.
2891     CompilerThread* ct = (CompilerThread*)this;
2892     if (ct->env() != NULL) {
2893       ct->env()->metadata_do(f);
2894     }
2895     CompileTask* task = ct->task();
2896     if (task != NULL) {
2897       task->metadata_do(f);
2898     }
2899   }
2900 }
2901 
2902 // Printing
2903 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2904   switch (_thread_state) {
2905   case _thread_uninitialized:     return "_thread_uninitialized";
2906   case _thread_new:               return "_thread_new";
2907   case _thread_new_trans:         return "_thread_new_trans";
2908   case _thread_in_native:         return "_thread_in_native";
2909   case _thread_in_native_trans:   return "_thread_in_native_trans";
2910   case _thread_in_vm:             return "_thread_in_vm";
2911   case _thread_in_vm_trans:       return "_thread_in_vm_trans";
2912   case _thread_in_Java:           return "_thread_in_Java";
2913   case _thread_in_Java_trans:     return "_thread_in_Java_trans";
2914   case _thread_blocked:           return "_thread_blocked";
2915   case _thread_blocked_trans:     return "_thread_blocked_trans";
2916   default:                        return "unknown thread state";
2917   }
2918 }
2919 
2920 #ifndef PRODUCT
2921 void JavaThread::print_thread_state_on(outputStream *st) const {
2922   st->print_cr("   JavaThread state: %s", _get_thread_state_name(_thread_state));
2923 };
2924 void JavaThread::print_thread_state() const {
2925   print_thread_state_on(tty);
2926 }
2927 #endif // PRODUCT
2928 
2929 // Called by Threads::print() for VM_PrintThreads operation
2930 void JavaThread::print_on(outputStream *st, bool print_extended_info) const {
2931   st->print_raw("\"");
2932   st->print_raw(get_thread_name());
2933   st->print_raw("\" ");
2934   oop thread_oop = threadObj();
2935   if (thread_oop != NULL) {
2936     st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
2937     if (java_lang_Thread::is_daemon(thread_oop))  st->print("daemon ");
2938     st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2939   }
2940   Thread::print_on(st, print_extended_info);
2941   // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2942   st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2943   if (thread_oop != NULL) {
2944     st->print_cr("   java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2945   }
2946 #ifndef PRODUCT
2947   _safepoint_state->print_on(st);
2948 #endif // PRODUCT
2949   if (is_Compiler_thread()) {
2950     CompileTask *task = ((CompilerThread*)this)->task();
2951     if (task != NULL) {
2952       st->print("   Compiling: ");
2953       task->print(st, NULL, true, false);
2954     } else {
2955       st->print("   No compile task");
2956     }
2957     st->cr();
2958   }
2959 }
2960 
2961 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2962   st->print("%s", get_thread_name_string(buf, buflen));
2963 }
2964 
2965 // Called by fatal error handler. The difference between this and
2966 // JavaThread::print() is that we can't grab lock or allocate memory.
2967 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2968   st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2969   oop thread_obj = threadObj();
2970   if (thread_obj != NULL) {
2971     if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2972   }
2973   st->print(" [");
2974   st->print("%s", _get_thread_state_name(_thread_state));
2975   if (osthread()) {
2976     st->print(", id=%d", osthread()->thread_id());
2977   }
2978   st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2979             p2i(stack_end()), p2i(stack_base()));
2980   st->print("]");
2981 
2982   ThreadsSMRSupport::print_info_on(this, st);
2983   return;
2984 }
2985 
2986 // Verification
2987 
2988 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2989 
2990 void JavaThread::verify() {
2991   // Verify oops in the thread.
2992   oops_do(&VerifyOopClosure::verify_oop, NULL);
2993 
2994   // Verify the stack frames.
2995   frames_do(frame_verify);
2996 }
2997 
2998 // CR 6300358 (sub-CR 2137150)
2999 // Most callers of this method assume that it can't return NULL but a
3000 // thread may not have a name whilst it is in the process of attaching to
3001 // the VM - see CR 6412693, and there are places where a JavaThread can be
3002 // seen prior to having it's threadObj set (eg JNI attaching threads and
3003 // if vm exit occurs during initialization). These cases can all be accounted
3004 // for such that this method never returns NULL.
3005 const char* JavaThread::get_thread_name() const {
3006 #ifdef ASSERT
3007   // early safepoints can hit while current thread does not yet have TLS
3008   if (!SafepointSynchronize::is_at_safepoint()) {
3009     Thread *cur = Thread::current();
3010     if (!(cur->is_Java_thread() && cur == this)) {
3011       // Current JavaThreads are allowed to get their own name without
3012       // the Threads_lock.
3013       assert_locked_or_safepoint(Threads_lock);
3014     }
3015   }
3016 #endif // ASSERT
3017   return get_thread_name_string();
3018 }
3019 
3020 // Returns a non-NULL representation of this thread's name, or a suitable
3021 // descriptive string if there is no set name
3022 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3023   const char* name_str;
3024   oop thread_obj = threadObj();
3025   if (thread_obj != NULL) {
3026     oop name = java_lang_Thread::name(thread_obj);
3027     if (name != NULL) {
3028       if (buf == NULL) {
3029         name_str = java_lang_String::as_utf8_string(name);
3030       } else {
3031         name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3032       }
3033     } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3034       name_str = "<no-name - thread is attaching>";
3035     } else {
3036       name_str = Thread::name();
3037     }
3038   } else {
3039     name_str = Thread::name();
3040   }
3041   assert(name_str != NULL, "unexpected NULL thread name");
3042   return name_str;
3043 }
3044 
3045 
3046 const char* JavaThread::get_threadgroup_name() const {
3047   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3048   oop thread_obj = threadObj();
3049   if (thread_obj != NULL) {
3050     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3051     if (thread_group != NULL) {
3052       // ThreadGroup.name can be null
3053       return java_lang_ThreadGroup::name(thread_group);
3054     }
3055   }
3056   return NULL;
3057 }
3058 
3059 const char* JavaThread::get_parent_name() const {
3060   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3061   oop thread_obj = threadObj();
3062   if (thread_obj != NULL) {
3063     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3064     if (thread_group != NULL) {
3065       oop parent = java_lang_ThreadGroup::parent(thread_group);
3066       if (parent != NULL) {
3067         // ThreadGroup.name can be null
3068         return java_lang_ThreadGroup::name(parent);
3069       }
3070     }
3071   }
3072   return NULL;
3073 }
3074 
3075 ThreadPriority JavaThread::java_priority() const {
3076   oop thr_oop = threadObj();
3077   if (thr_oop == NULL) return NormPriority; // Bootstrapping
3078   ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3079   assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3080   return priority;
3081 }
3082 
3083 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3084 
3085   assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3086   // Link Java Thread object <-> C++ Thread
3087 
3088   // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3089   // and put it into a new Handle.  The Handle "thread_oop" can then
3090   // be used to pass the C++ thread object to other methods.
3091 
3092   // Set the Java level thread object (jthread) field of the
3093   // new thread (a JavaThread *) to C++ thread object using the
3094   // "thread_oop" handle.
3095 
3096   // Set the thread field (a JavaThread *) of the
3097   // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3098 
3099   Handle thread_oop(Thread::current(),
3100                     JNIHandles::resolve_non_null(jni_thread));
3101   assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3102          "must be initialized");
3103   set_threadObj(thread_oop());
3104   java_lang_Thread::set_thread(thread_oop(), this);
3105 
3106   if (prio == NoPriority) {
3107     prio = java_lang_Thread::priority(thread_oop());
3108     assert(prio != NoPriority, "A valid priority should be present");
3109   }
3110 
3111   // Push the Java priority down to the native thread; needs Threads_lock
3112   Thread::set_priority(this, prio);
3113 
3114   // Add the new thread to the Threads list and set it in motion.
3115   // We must have threads lock in order to call Threads::add.
3116   // It is crucial that we do not block before the thread is
3117   // added to the Threads list for if a GC happens, then the java_thread oop
3118   // will not be visited by GC.
3119   Threads::add(this);
3120 }
3121 
3122 oop JavaThread::current_park_blocker() {
3123   // Support for JSR-166 locks
3124   oop thread_oop = threadObj();
3125   if (thread_oop != NULL &&
3126       JDK_Version::current().supports_thread_park_blocker()) {
3127     return java_lang_Thread::park_blocker(thread_oop);
3128   }
3129   return NULL;
3130 }
3131 
3132 
3133 void JavaThread::print_stack_on(outputStream* st) {
3134   if (!has_last_Java_frame()) return;
3135   ResourceMark rm;
3136   HandleMark   hm;
3137 
3138   RegisterMap reg_map(this);
3139   vframe* start_vf = last_java_vframe(&reg_map);
3140   int count = 0;
3141   for (vframe* f = start_vf; f != NULL; f = f->sender()) {
3142     if (f->is_java_frame()) {
3143       javaVFrame* jvf = javaVFrame::cast(f);
3144       java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3145 
3146       // Print out lock information
3147       if (JavaMonitorsInStackTrace) {
3148         jvf->print_lock_info_on(st, count);
3149       }
3150     } else {
3151       // Ignore non-Java frames
3152     }
3153 
3154     // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
3155     count++;
3156     if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
3157   }
3158 }
3159 
3160 
3161 // JVMTI PopFrame support
3162 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3163   assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3164   if (in_bytes(size_in_bytes) != 0) {
3165     _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3166     _popframe_preserved_args_size = in_bytes(size_in_bytes);
3167     Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3168   }
3169 }
3170 
3171 void* JavaThread::popframe_preserved_args() {
3172   return _popframe_preserved_args;
3173 }
3174 
3175 ByteSize JavaThread::popframe_preserved_args_size() {
3176   return in_ByteSize(_popframe_preserved_args_size);
3177 }
3178 
3179 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3180   int sz = in_bytes(popframe_preserved_args_size());
3181   assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3182   return in_WordSize(sz / wordSize);
3183 }
3184 
3185 void JavaThread::popframe_free_preserved_args() {
3186   assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3187   FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3188   _popframe_preserved_args = NULL;
3189   _popframe_preserved_args_size = 0;
3190 }
3191 
3192 #ifndef PRODUCT
3193 
3194 void JavaThread::trace_frames() {
3195   tty->print_cr("[Describe stack]");
3196   int frame_no = 1;
3197   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3198     tty->print("  %d. ", frame_no++);
3199     fst.current()->print_value_on(tty, this);
3200     tty->cr();
3201   }
3202 }
3203 
3204 class PrintAndVerifyOopClosure: public OopClosure {
3205  protected:
3206   template <class T> inline void do_oop_work(T* p) {
3207     oop obj = RawAccess<>::oop_load(p);
3208     if (obj == NULL) return;
3209     tty->print(INTPTR_FORMAT ": ", p2i(p));
3210     if (oopDesc::is_oop_or_null(obj)) {
3211       if (obj->is_objArray()) {
3212         tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3213       } else {
3214         obj->print();
3215       }
3216     } else {
3217       tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3218     }
3219     tty->cr();
3220   }
3221  public:
3222   virtual void do_oop(oop* p) { do_oop_work(p); }
3223   virtual void do_oop(narrowOop* p)  { do_oop_work(p); }
3224 };
3225 
3226 
3227 static void oops_print(frame* f, const RegisterMap *map) {
3228   PrintAndVerifyOopClosure print;
3229   f->print_value();
3230   f->oops_do(&print, NULL, (RegisterMap*)map);
3231 }
3232 
3233 // Print our all the locations that contain oops and whether they are
3234 // valid or not.  This useful when trying to find the oldest frame
3235 // where an oop has gone bad since the frame walk is from youngest to
3236 // oldest.
3237 void JavaThread::trace_oops() {
3238   tty->print_cr("[Trace oops]");
3239   frames_do(oops_print);
3240 }
3241 
3242 
3243 #ifdef ASSERT
3244 // Print or validate the layout of stack frames
3245 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3246   ResourceMark rm;
3247   PRESERVE_EXCEPTION_MARK;
3248   FrameValues values;
3249   int frame_no = 0;
3250   for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3251     fst.current()->describe(values, ++frame_no);
3252     if (depth == frame_no) break;
3253   }
3254   if (validate_only) {
3255     values.validate();
3256   } else {
3257     tty->print_cr("[Describe stack layout]");
3258     values.print(this);
3259   }
3260 }
3261 #endif
3262 
3263 void JavaThread::trace_stack_from(vframe* start_vf) {
3264   ResourceMark rm;
3265   int vframe_no = 1;
3266   for (vframe* f = start_vf; f; f = f->sender()) {
3267     if (f->is_java_frame()) {
3268       javaVFrame::cast(f)->print_activation(vframe_no++);
3269     } else {
3270       f->print();
3271     }
3272     if (vframe_no > StackPrintLimit) {
3273       tty->print_cr("...<more frames>...");
3274       return;
3275     }
3276   }
3277 }
3278 
3279 
3280 void JavaThread::trace_stack() {
3281   if (!has_last_Java_frame()) return;
3282   ResourceMark rm;
3283   HandleMark   hm;
3284   RegisterMap reg_map(this);
3285   trace_stack_from(last_java_vframe(&reg_map));
3286 }
3287 
3288 
3289 #endif // PRODUCT
3290 
3291 
3292 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3293   assert(reg_map != NULL, "a map must be given");
3294   frame f = last_frame();
3295   for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3296     if (vf->is_java_frame()) return javaVFrame::cast(vf);
3297   }
3298   return NULL;
3299 }
3300 
3301 
3302 Klass* JavaThread::security_get_caller_class(int depth) {
3303   vframeStream vfst(this);
3304   vfst.security_get_caller_frame(depth);
3305   if (!vfst.at_end()) {
3306     return vfst.method()->method_holder();
3307   }
3308   return NULL;
3309 }
3310 
3311 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3312   assert(thread->is_Compiler_thread(), "must be compiler thread");
3313   CompileBroker::compiler_thread_loop();
3314 }
3315 
3316 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3317   NMethodSweeper::sweeper_loop();
3318 }
3319 
3320 // Create a CompilerThread
3321 CompilerThread::CompilerThread(CompileQueue* queue,
3322                                CompilerCounters* counters)
3323                                : JavaThread(&compiler_thread_entry) {
3324   _env   = NULL;
3325   _log   = NULL;
3326   _task  = NULL;
3327   _queue = queue;
3328   _counters = counters;
3329   _buffer_blob = NULL;
3330   _compiler = NULL;
3331 
3332   // Compiler uses resource area for compilation, let's bias it to mtCompiler
3333   resource_area()->bias_to(mtCompiler);
3334 
3335 #ifndef PRODUCT
3336   _ideal_graph_printer = NULL;
3337 #endif
3338 }
3339 
3340 CompilerThread::~CompilerThread() {
3341   // Delete objects which were allocated on heap.
3342   delete _counters;
3343 }
3344 
3345 bool CompilerThread::can_call_java() const {
3346   return _compiler != NULL && _compiler->is_jvmci();
3347 }
3348 
3349 // Create sweeper thread
3350 CodeCacheSweeperThread::CodeCacheSweeperThread()
3351 : JavaThread(&sweeper_thread_entry) {
3352   _scanned_compiled_method = NULL;
3353 }
3354 
3355 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3356   JavaThread::oops_do(f, cf);
3357   if (_scanned_compiled_method != NULL && cf != NULL) {
3358     // Safepoints can occur when the sweeper is scanning an nmethod so
3359     // process it here to make sure it isn't unloaded in the middle of
3360     // a scan.
3361     cf->do_code_blob(_scanned_compiled_method);
3362   }
3363 }
3364 
3365 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3366   JavaThread::nmethods_do(cf);
3367   if (_scanned_compiled_method != NULL && cf != NULL) {
3368     // Safepoints can occur when the sweeper is scanning an nmethod so
3369     // process it here to make sure it isn't unloaded in the middle of
3370     // a scan.
3371     cf->do_code_blob(_scanned_compiled_method);
3372   }
3373 }
3374 
3375 
3376 // ======= Threads ========
3377 
3378 // The Threads class links together all active threads, and provides
3379 // operations over all threads. It is protected by the Threads_lock,
3380 // which is also used in other global contexts like safepointing.
3381 // ThreadsListHandles are used to safely perform operations on one
3382 // or more threads without the risk of the thread exiting during the
3383 // operation.
3384 //
3385 // Note: The Threads_lock is currently more widely used than we
3386 // would like. We are actively migrating Threads_lock uses to other
3387 // mechanisms in order to reduce Threads_lock contention.
3388 
3389 JavaThread* Threads::_thread_list = NULL;
3390 int         Threads::_number_of_threads = 0;
3391 int         Threads::_number_of_non_daemon_threads = 0;
3392 int         Threads::_return_code = 0;
3393 int         Threads::_thread_claim_parity = 0;
3394 size_t      JavaThread::_stack_size_at_create = 0;
3395 
3396 #ifdef ASSERT
3397 bool        Threads::_vm_complete = false;
3398 size_t      Threads::_threads_before_barrier_set = 0;
3399 #endif
3400 
3401 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
3402   Prefetch::read((void*)addr, prefetch_interval);
3403   return *addr;
3404 }
3405 
3406 // Possibly the ugliest for loop the world has seen. C++ does not allow
3407 // multiple types in the declaration section of the for loop. In this case
3408 // we are only dealing with pointers and hence can cast them. It looks ugly
3409 // but macros are ugly and therefore it's fine to make things absurdly ugly.
3410 #define DO_JAVA_THREADS(LIST, X)                                                                                          \
3411     for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes,                           \
3412              *MACRO_list = (JavaThread*)(LIST),                                                                           \
3413              **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(),  \
3414              **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(),                                     \
3415              *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval);                 \
3416          MACRO_current_p != MACRO_end;                                                                                    \
3417          MACRO_current_p++,                                                                                               \
3418              X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval))
3419 
3420 // All JavaThreads
3421 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X)
3422 
3423 // All NonJavaThreads (i.e., every non-JavaThread in the system).
3424 void Threads::non_java_threads_do(ThreadClosure* tc) {
3425   NoSafepointVerifier nsv(!SafepointSynchronize::is_at_safepoint(), false);
3426   for (NonJavaThread::Iterator njti; !njti.end(); njti.step()) {
3427     tc->do_thread(njti.current());
3428   }
3429 }
3430 
3431 // All JavaThreads
3432 void Threads::java_threads_do(ThreadClosure* tc) {
3433   assert_locked_or_safepoint(Threads_lock);
3434   // ALL_JAVA_THREADS iterates through all JavaThreads.
3435   ALL_JAVA_THREADS(p) {
3436     tc->do_thread(p);
3437   }
3438 }
3439 
3440 void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) {
3441   assert_locked_or_safepoint(Threads_lock);
3442   java_threads_do(tc);
3443   tc->do_thread(VMThread::vm_thread());
3444 }
3445 
3446 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system).
3447 void Threads::threads_do(ThreadClosure* tc) {
3448   assert_locked_or_safepoint(Threads_lock);
3449   java_threads_do(tc);
3450   non_java_threads_do(tc);
3451 }
3452 
3453 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
3454   int cp = Threads::thread_claim_parity();
3455   ALL_JAVA_THREADS(p) {
3456     if (p->claim_oops_do(is_par, cp)) {
3457       tc->do_thread(p);
3458     }
3459   }
3460   VMThread* vmt = VMThread::vm_thread();
3461   if (vmt->claim_oops_do(is_par, cp)) {
3462     tc->do_thread(vmt);
3463   }
3464 }
3465 
3466 // The system initialization in the library has three phases.
3467 //
3468 // Phase 1: java.lang.System class initialization
3469 //     java.lang.System is a primordial class loaded and initialized
3470 //     by the VM early during startup.  java.lang.System.<clinit>
3471 //     only does registerNatives and keeps the rest of the class
3472 //     initialization work later until thread initialization completes.
3473 //
3474 //     System.initPhase1 initializes the system properties, the static
3475 //     fields in, out, and err. Set up java signal handlers, OS-specific
3476 //     system settings, and thread group of the main thread.
3477 static void call_initPhase1(TRAPS) {
3478   Klass* klass =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3479   JavaValue result(T_VOID);
3480   JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3481                                          vmSymbols::void_method_signature(), CHECK);
3482 }
3483 
3484 // Phase 2. Module system initialization
3485 //     This will initialize the module system.  Only java.base classes
3486 //     can be loaded until phase 2 completes.
3487 //
3488 //     Call System.initPhase2 after the compiler initialization and jsr292
3489 //     classes get initialized because module initialization runs a lot of java
3490 //     code, that for performance reasons, should be compiled.  Also, this will
3491 //     enable the startup code to use lambda and other language features in this
3492 //     phase and onward.
3493 //
3494 //     After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3495 static void call_initPhase2(TRAPS) {
3496   TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3497 
3498   Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3499 
3500   JavaValue result(T_INT);
3501   JavaCallArguments args;
3502   args.push_int(DisplayVMOutputToStderr);
3503   args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3504   JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3505                                          vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3506   if (result.get_jint() != JNI_OK) {
3507     vm_exit_during_initialization(); // no message or exception
3508   }
3509 
3510   universe_post_module_init();
3511 }
3512 
3513 // Phase 3. final setup - set security manager, system class loader and TCCL
3514 //
3515 //     This will instantiate and set the security manager, set the system class
3516 //     loader as well as the thread context class loader.  The security manager
3517 //     and system class loader may be a custom class loaded from -Xbootclasspath/a,
3518 //     other modules or the application's classpath.
3519 static void call_initPhase3(TRAPS) {
3520   Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3521   JavaValue result(T_VOID);
3522   JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3523                                          vmSymbols::void_method_signature(), CHECK);
3524 }
3525 
3526 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3527   TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3528 
3529   if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3530     create_vm_init_libraries();
3531   }
3532 
3533   initialize_class(vmSymbols::java_lang_String(), CHECK);
3534 
3535   // Inject CompactStrings value after the static initializers for String ran.
3536   java_lang_String::set_compact_strings(CompactStrings);
3537 
3538   // Initialize java_lang.System (needed before creating the thread)
3539   initialize_class(vmSymbols::java_lang_System(), CHECK);
3540   // The VM creates & returns objects of this class. Make sure it's initialized.
3541   initialize_class(vmSymbols::java_lang_Class(), CHECK);
3542   initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3543   Handle thread_group = create_initial_thread_group(CHECK);
3544   Universe::set_main_thread_group(thread_group());
3545   initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3546   oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3547   main_thread->set_threadObj(thread_object);
3548   // Set thread status to running since main thread has
3549   // been started and running.
3550   java_lang_Thread::set_thread_status(thread_object,
3551                                       java_lang_Thread::RUNNABLE);
3552 
3553   // The VM creates objects of this class.
3554   initialize_class(vmSymbols::java_lang_Module(), CHECK);
3555 
3556   // The VM preresolves methods to these classes. Make sure that they get initialized
3557   initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3558   initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3559 
3560   // Phase 1 of the system initialization in the library, java.lang.System class initialization
3561   call_initPhase1(CHECK);
3562 
3563   // get the Java runtime name after java.lang.System is initialized
3564   JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3565   JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3566 
3567   // an instance of OutOfMemory exception has been allocated earlier
3568   initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3569   initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3570   initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3571   initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3572   initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3573   initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3574   initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3575   initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3576 }
3577 
3578 void Threads::initialize_jsr292_core_classes(TRAPS) {
3579   TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3580 
3581   initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3582   initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3583   initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3584   initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3585 }
3586 
3587 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3588   extern void JDK_Version_init();
3589 
3590   // Preinitialize version info.
3591   VM_Version::early_initialize();
3592 
3593   // Check version
3594   if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3595 
3596   // Initialize library-based TLS
3597   ThreadLocalStorage::init();
3598 
3599   // Initialize the output stream module
3600   ostream_init();
3601 
3602   // Process java launcher properties.
3603   Arguments::process_sun_java_launcher_properties(args);
3604 
3605   // Initialize the os module
3606   os::init();
3607 
3608   // Record VM creation timing statistics
3609   TraceVmCreationTime create_vm_timer;
3610   create_vm_timer.start();
3611 
3612   // Initialize system properties.
3613   Arguments::init_system_properties();
3614 
3615   // So that JDK version can be used as a discriminator when parsing arguments
3616   JDK_Version_init();
3617 
3618   // Update/Initialize System properties after JDK version number is known
3619   Arguments::init_version_specific_system_properties();
3620 
3621   // Make sure to initialize log configuration *before* parsing arguments
3622   LogConfiguration::initialize(create_vm_timer.begin_time());
3623 
3624   // Parse arguments
3625   // Note: this internally calls os::init_container_support()
3626   jint parse_result = Arguments::parse(args);
3627   if (parse_result != JNI_OK) return parse_result;
3628 
3629   os::init_before_ergo();
3630 
3631   jint ergo_result = Arguments::apply_ergo();
3632   if (ergo_result != JNI_OK) return ergo_result;
3633 
3634   // Final check of all ranges after ergonomics which may change values.
3635   if (!JVMFlagRangeList::check_ranges()) {
3636     return JNI_EINVAL;
3637   }
3638 
3639   // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3640   bool constraint_result = JVMFlagConstraintList::check_constraints(JVMFlagConstraint::AfterErgo);
3641   if (!constraint_result) {
3642     return JNI_EINVAL;
3643   }
3644 
3645   JVMFlagWriteableList::mark_startup();
3646 
3647   if (PauseAtStartup) {
3648     os::pause();
3649   }
3650 
3651   HOTSPOT_VM_INIT_BEGIN();
3652 
3653   // Timing (must come after argument parsing)
3654   TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3655 
3656 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT
3657   // Initialize assert poison page mechanism.
3658   if (ShowRegistersOnAssert) {
3659     initialize_assert_poison();
3660   }
3661 #endif // CAN_SHOW_REGISTERS_ON_ASSERT
3662 
3663   // Initialize the os module after parsing the args
3664   jint os_init_2_result = os::init_2();
3665   if (os_init_2_result != JNI_OK) return os_init_2_result;
3666 
3667   SafepointMechanism::initialize();
3668 
3669   jint adjust_after_os_result = Arguments::adjust_after_os();
3670   if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3671 
3672   // Initialize output stream logging
3673   ostream_init_log();
3674 
3675   // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3676   // Must be before create_vm_init_agents()
3677   if (Arguments::init_libraries_at_startup()) {
3678     convert_vm_init_libraries_to_agents();
3679   }
3680 
3681   // Launch -agentlib/-agentpath and converted -Xrun agents
3682   if (Arguments::init_agents_at_startup()) {
3683     create_vm_init_agents();
3684   }
3685 
3686   // Initialize Threads state
3687   _thread_list = NULL;
3688   _number_of_threads = 0;
3689   _number_of_non_daemon_threads = 0;
3690 
3691   // Initialize global data structures and create system classes in heap
3692   vm_init_globals();
3693 
3694 #if INCLUDE_JVMCI
3695   if (JVMCICounterSize > 0) {
3696     JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3697     memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3698   } else {
3699     JavaThread::_jvmci_old_thread_counters = NULL;
3700   }
3701 #endif // INCLUDE_JVMCI
3702 
3703   // Attach the main thread to this os thread
3704   JavaThread* main_thread = new JavaThread();
3705   main_thread->set_thread_state(_thread_in_vm);
3706   main_thread->initialize_thread_current();
3707   // must do this before set_active_handles
3708   main_thread->record_stack_base_and_size();
3709   main_thread->register_thread_stack_with_NMT();
3710   main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3711 
3712   if (!main_thread->set_as_starting_thread()) {
3713     vm_shutdown_during_initialization(
3714                                       "Failed necessary internal allocation. Out of swap space");
3715     main_thread->smr_delete();
3716     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3717     return JNI_ENOMEM;
3718   }
3719 
3720   // Enable guard page *after* os::create_main_thread(), otherwise it would
3721   // crash Linux VM, see notes in os_linux.cpp.
3722   main_thread->create_stack_guard_pages();
3723 
3724   // Initialize Java-Level synchronization subsystem
3725   ObjectMonitor::Initialize();
3726 
3727   // Initialize global modules
3728   jint status = init_globals();
3729   if (status != JNI_OK) {
3730     main_thread->smr_delete();
3731     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3732     return status;
3733   }
3734 
3735   JFR_ONLY(Jfr::on_vm_init();)
3736 
3737   // Should be done after the heap is fully created
3738   main_thread->cache_global_variables();
3739 
3740   HandleMark hm;
3741 
3742   { MutexLocker mu(Threads_lock);
3743     Threads::add(main_thread);
3744   }
3745 
3746   // Any JVMTI raw monitors entered in onload will transition into
3747   // real raw monitor. VM is setup enough here for raw monitor enter.
3748   JvmtiExport::transition_pending_onload_raw_monitors();
3749 
3750   // Create the VMThread
3751   { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3752 
3753   VMThread::create();
3754     Thread* vmthread = VMThread::vm_thread();
3755 
3756     if (!os::create_thread(vmthread, os::vm_thread)) {
3757       vm_exit_during_initialization("Cannot create VM thread. "
3758                                     "Out of system resources.");
3759     }
3760 
3761     // Wait for the VM thread to become ready, and VMThread::run to initialize
3762     // Monitors can have spurious returns, must always check another state flag
3763     {
3764       MutexLocker ml(Notify_lock);
3765       os::start_thread(vmthread);
3766       while (vmthread->active_handles() == NULL) {
3767         Notify_lock->wait();
3768       }
3769     }
3770   }
3771 
3772   assert(Universe::is_fully_initialized(), "not initialized");
3773   if (VerifyDuringStartup) {
3774     // Make sure we're starting with a clean slate.
3775     VM_Verify verify_op;
3776     VMThread::execute(&verify_op);
3777   }
3778 
3779   // We need this to update the java.vm.info property in case any flags used
3780   // to initially define it have been changed. This is needed for both CDS and
3781   // AOT, since UseSharedSpaces and UseAOT may be changed after java.vm.info
3782   // is initially computed. See Abstract_VM_Version::vm_info_string().
3783   // This update must happen before we initialize the java classes, but
3784   // after any initialization logic that might modify the flags.
3785   Arguments::update_vm_info_property(VM_Version::vm_info_string());
3786 
3787   Thread* THREAD = Thread::current();
3788 
3789   // Always call even when there are not JVMTI environments yet, since environments
3790   // may be attached late and JVMTI must track phases of VM execution
3791   JvmtiExport::enter_early_start_phase();
3792 
3793   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3794   JvmtiExport::post_early_vm_start();
3795 
3796   initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3797 
3798   quicken_jni_functions();
3799 
3800   // No more stub generation allowed after that point.
3801   StubCodeDesc::freeze();
3802 
3803   // Set flag that basic initialization has completed. Used by exceptions and various
3804   // debug stuff, that does not work until all basic classes have been initialized.
3805   set_init_completed();
3806 
3807   LogConfiguration::post_initialize();
3808   Metaspace::post_initialize();
3809 
3810   HOTSPOT_VM_INIT_END();
3811 
3812   // record VM initialization completion time
3813 #if INCLUDE_MANAGEMENT
3814   Management::record_vm_init_completed();
3815 #endif // INCLUDE_MANAGEMENT
3816 
3817   // Signal Dispatcher needs to be started before VMInit event is posted
3818   os::initialize_jdk_signal_support(CHECK_JNI_ERR);
3819 
3820   // Start Attach Listener if +StartAttachListener or it can't be started lazily
3821   if (!DisableAttachMechanism) {
3822     AttachListener::vm_start();
3823     if (StartAttachListener || AttachListener::init_at_startup()) {
3824       AttachListener::init();
3825     }
3826   }
3827 
3828   // Launch -Xrun agents
3829   // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3830   // back-end can launch with -Xdebug -Xrunjdwp.
3831   if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3832     create_vm_init_libraries();
3833   }
3834 
3835   if (CleanChunkPoolAsync) {
3836     Chunk::start_chunk_pool_cleaner_task();
3837   }
3838 
3839   // initialize compiler(s)
3840 #if defined(COMPILER1) || COMPILER2_OR_JVMCI
3841 #if INCLUDE_JVMCI
3842   bool force_JVMCI_intialization = false;
3843   if (EnableJVMCI) {
3844     // Initialize JVMCI eagerly when it is explicitly requested.
3845     // Or when JVMCIPrintProperties is enabled.
3846     // The JVMCI Java initialization code will read this flag and
3847     // do the printing if it's set.
3848     force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties;
3849 
3850     if (!force_JVMCI_intialization) {
3851       // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3852       // compilations via JVMCI will not actually block until JVMCI is initialized.
3853       force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3854     }
3855   }
3856 #endif
3857   CompileBroker::compilation_init_phase1(CHECK_JNI_ERR);
3858   // Postpone completion of compiler initialization to after JVMCI
3859   // is initialized to avoid timeouts of blocking compilations.
3860   if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) {
3861     CompileBroker::compilation_init_phase2();
3862   }
3863 #endif
3864 
3865   // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3866   // It is done after compilers are initialized, because otherwise compilations of
3867   // signature polymorphic MH intrinsics can be missed
3868   // (see SystemDictionary::find_method_handle_intrinsic).
3869   initialize_jsr292_core_classes(CHECK_JNI_ERR);
3870 
3871   // This will initialize the module system.  Only java.base classes can be
3872   // loaded until phase 2 completes
3873   call_initPhase2(CHECK_JNI_ERR);
3874 
3875   // Always call even when there are not JVMTI environments yet, since environments
3876   // may be attached late and JVMTI must track phases of VM execution
3877   JvmtiExport::enter_start_phase();
3878 
3879   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3880   JvmtiExport::post_vm_start();
3881 
3882   // Final system initialization including security manager and system class loader
3883   call_initPhase3(CHECK_JNI_ERR);
3884 
3885   // cache the system and platform class loaders
3886   SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
3887 
3888 #if INCLUDE_CDS
3889   if (DumpSharedSpaces) {
3890     // capture the module path info from the ModuleEntryTable
3891     ClassLoader::initialize_module_path(THREAD);
3892   }
3893 #endif
3894 
3895 #if INCLUDE_JVMCI
3896   if (force_JVMCI_intialization) {
3897     JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
3898     CompileBroker::compilation_init_phase2();
3899   }
3900 #endif
3901 
3902   // Always call even when there are not JVMTI environments yet, since environments
3903   // may be attached late and JVMTI must track phases of VM execution
3904   JvmtiExport::enter_live_phase();
3905 
3906   // Make perfmemory accessible
3907   PerfMemory::set_accessible(true);
3908 
3909   // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3910   JvmtiExport::post_vm_initialized();
3911 
3912   JFR_ONLY(Jfr::on_vm_start();)
3913 
3914 #if INCLUDE_MANAGEMENT
3915   Management::initialize(THREAD);
3916 
3917   if (HAS_PENDING_EXCEPTION) {
3918     // management agent fails to start possibly due to
3919     // configuration problem and is responsible for printing
3920     // stack trace if appropriate. Simply exit VM.
3921     vm_exit(1);
3922   }
3923 #endif // INCLUDE_MANAGEMENT
3924 
3925   if (MemProfiling)                   MemProfiler::engage();
3926   StatSampler::engage();
3927   if (CheckJNICalls)                  JniPeriodicChecker::engage();
3928 
3929   BiasedLocking::init();
3930 
3931 #if INCLUDE_RTM_OPT
3932   RTMLockingCounters::init();
3933 #endif
3934 
3935   if (JDK_Version::current().post_vm_init_hook_enabled()) {
3936     call_postVMInitHook(THREAD);
3937     // The Java side of PostVMInitHook.run must deal with all
3938     // exceptions and provide means of diagnosis.
3939     if (HAS_PENDING_EXCEPTION) {
3940       CLEAR_PENDING_EXCEPTION;
3941     }
3942   }
3943 
3944   {
3945     MutexLocker ml(PeriodicTask_lock);
3946     // Make sure the WatcherThread can be started by WatcherThread::start()
3947     // or by dynamic enrollment.
3948     WatcherThread::make_startable();
3949     // Start up the WatcherThread if there are any periodic tasks
3950     // NOTE:  All PeriodicTasks should be registered by now. If they
3951     //   aren't, late joiners might appear to start slowly (we might
3952     //   take a while to process their first tick).
3953     if (PeriodicTask::num_tasks() > 0) {
3954       WatcherThread::start();
3955     }
3956   }
3957 
3958   create_vm_timer.end();
3959 #ifdef ASSERT
3960   _vm_complete = true;
3961 #endif
3962 
3963   if (DumpSharedSpaces) {
3964     MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3965     ShouldNotReachHere();
3966   }
3967 
3968   return JNI_OK;
3969 }
3970 
3971 // type for the Agent_OnLoad and JVM_OnLoad entry points
3972 extern "C" {
3973   typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3974 }
3975 // Find a command line agent library and return its entry point for
3976 //         -agentlib:  -agentpath:   -Xrun
3977 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3978 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3979                                     const char *on_load_symbols[],
3980                                     size_t num_symbol_entries) {
3981   OnLoadEntry_t on_load_entry = NULL;
3982   void *library = NULL;
3983 
3984   if (!agent->valid()) {
3985     char buffer[JVM_MAXPATHLEN];
3986     char ebuf[1024] = "";
3987     const char *name = agent->name();
3988     const char *msg = "Could not find agent library ";
3989 
3990     // First check to see if agent is statically linked into executable
3991     if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3992       library = agent->os_lib();
3993     } else if (agent->is_absolute_path()) {
3994       library = os::dll_load(name, ebuf, sizeof ebuf);
3995       if (library == NULL) {
3996         const char *sub_msg = " in absolute path, with error: ";
3997         size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3998         char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3999         jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4000         // If we can't find the agent, exit.
4001         vm_exit_during_initialization(buf, NULL);
4002         FREE_C_HEAP_ARRAY(char, buf);
4003       }
4004     } else {
4005       // Try to load the agent from the standard dll directory
4006       if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
4007                              name)) {
4008         library = os::dll_load(buffer, ebuf, sizeof ebuf);
4009       }
4010       if (library == NULL) { // Try the library path directory.
4011         if (os::dll_build_name(buffer, sizeof(buffer), name)) {
4012           library = os::dll_load(buffer, ebuf, sizeof ebuf);
4013         }
4014         if (library == NULL) {
4015           const char *sub_msg = " on the library path, with error: ";
4016           const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image.";
4017 
4018           size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) +
4019                        strlen(ebuf) + strlen(sub_msg2) + 1;
4020           char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4021           if (!agent->is_instrument_lib()) {
4022             jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4023           } else {
4024             jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2);
4025           }
4026           // If we can't find the agent, exit.
4027           vm_exit_during_initialization(buf, NULL);
4028           FREE_C_HEAP_ARRAY(char, buf);
4029         }
4030       }
4031     }
4032     agent->set_os_lib(library);
4033     agent->set_valid();
4034   }
4035 
4036   // Find the OnLoad function.
4037   on_load_entry =
4038     CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
4039                                                           false,
4040                                                           on_load_symbols,
4041                                                           num_symbol_entries));
4042   return on_load_entry;
4043 }
4044 
4045 // Find the JVM_OnLoad entry point
4046 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
4047   const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
4048   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4049 }
4050 
4051 // Find the Agent_OnLoad entry point
4052 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
4053   const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
4054   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4055 }
4056 
4057 // For backwards compatibility with -Xrun
4058 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
4059 // treated like -agentpath:
4060 // Must be called before agent libraries are created
4061 void Threads::convert_vm_init_libraries_to_agents() {
4062   AgentLibrary* agent;
4063   AgentLibrary* next;
4064 
4065   for (agent = Arguments::libraries(); agent != NULL; agent = next) {
4066     next = agent->next();  // cache the next agent now as this agent may get moved off this list
4067     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4068 
4069     // If there is an JVM_OnLoad function it will get called later,
4070     // otherwise see if there is an Agent_OnLoad
4071     if (on_load_entry == NULL) {
4072       on_load_entry = lookup_agent_on_load(agent);
4073       if (on_load_entry != NULL) {
4074         // switch it to the agent list -- so that Agent_OnLoad will be called,
4075         // JVM_OnLoad won't be attempted and Agent_OnUnload will
4076         Arguments::convert_library_to_agent(agent);
4077       } else {
4078         vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
4079       }
4080     }
4081   }
4082 }
4083 
4084 // Create agents for -agentlib:  -agentpath:  and converted -Xrun
4085 // Invokes Agent_OnLoad
4086 // Called very early -- before JavaThreads exist
4087 void Threads::create_vm_init_agents() {
4088   extern struct JavaVM_ main_vm;
4089   AgentLibrary* agent;
4090 
4091   JvmtiExport::enter_onload_phase();
4092 
4093   for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4094     // CDS dumping does not support native JVMTI agent.
4095     // CDS dumping supports Java agent if the AllowArchivingWithJavaAgent diagnostic option is specified.
4096     if (DumpSharedSpaces) {
4097       if(!agent->is_instrument_lib()) {
4098         vm_exit_during_cds_dumping("CDS dumping does not support native JVMTI agent, name", agent->name());
4099       } else if (!AllowArchivingWithJavaAgent) {
4100         vm_exit_during_cds_dumping(
4101           "Must enable AllowArchivingWithJavaAgent in order to run Java agent during CDS dumping");
4102       }
4103     }
4104 
4105     OnLoadEntry_t  on_load_entry = lookup_agent_on_load(agent);
4106 
4107     if (on_load_entry != NULL) {
4108       // Invoke the Agent_OnLoad function
4109       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4110       if (err != JNI_OK) {
4111         vm_exit_during_initialization("agent library failed to init", agent->name());
4112       }
4113     } else {
4114       vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4115     }
4116   }
4117 
4118   JvmtiExport::enter_primordial_phase();
4119 }
4120 
4121 extern "C" {
4122   typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4123 }
4124 
4125 void Threads::shutdown_vm_agents() {
4126   // Send any Agent_OnUnload notifications
4127   const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4128   size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4129   extern struct JavaVM_ main_vm;
4130   for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4131 
4132     // Find the Agent_OnUnload function.
4133     Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4134                                                    os::find_agent_function(agent,
4135                                                    false,
4136                                                    on_unload_symbols,
4137                                                    num_symbol_entries));
4138 
4139     // Invoke the Agent_OnUnload function
4140     if (unload_entry != NULL) {
4141       JavaThread* thread = JavaThread::current();
4142       ThreadToNativeFromVM ttn(thread);
4143       HandleMark hm(thread);
4144       (*unload_entry)(&main_vm);
4145     }
4146   }
4147 }
4148 
4149 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4150 // Invokes JVM_OnLoad
4151 void Threads::create_vm_init_libraries() {
4152   extern struct JavaVM_ main_vm;
4153   AgentLibrary* agent;
4154 
4155   for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4156     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4157 
4158     if (on_load_entry != NULL) {
4159       // Invoke the JVM_OnLoad function
4160       JavaThread* thread = JavaThread::current();
4161       ThreadToNativeFromVM ttn(thread);
4162       HandleMark hm(thread);
4163       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4164       if (err != JNI_OK) {
4165         vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4166       }
4167     } else {
4168       vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4169     }
4170   }
4171 }
4172 
4173 
4174 // Last thread running calls java.lang.Shutdown.shutdown()
4175 void JavaThread::invoke_shutdown_hooks() {
4176   HandleMark hm(this);
4177 
4178   // We could get here with a pending exception, if so clear it now.
4179   if (this->has_pending_exception()) {
4180     this->clear_pending_exception();
4181   }
4182 
4183   EXCEPTION_MARK;
4184   Klass* shutdown_klass =
4185     SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4186                                       THREAD);
4187   if (shutdown_klass != NULL) {
4188     // SystemDictionary::resolve_or_null will return null if there was
4189     // an exception.  If we cannot load the Shutdown class, just don't
4190     // call Shutdown.shutdown() at all.  This will mean the shutdown hooks
4191     // won't be run.  Note that if a shutdown hook was registered,
4192     // the Shutdown class would have already been loaded
4193     // (Runtime.addShutdownHook will load it).
4194     JavaValue result(T_VOID);
4195     JavaCalls::call_static(&result,
4196                            shutdown_klass,
4197                            vmSymbols::shutdown_method_name(),
4198                            vmSymbols::void_method_signature(),
4199                            THREAD);
4200   }
4201   CLEAR_PENDING_EXCEPTION;
4202 }
4203 
4204 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4205 // the program falls off the end of main(). Another VM exit path is through
4206 // vm_exit() when the program calls System.exit() to return a value or when
4207 // there is a serious error in VM. The two shutdown paths are not exactly
4208 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4209 // and VM_Exit op at VM level.
4210 //
4211 // Shutdown sequence:
4212 //   + Shutdown native memory tracking if it is on
4213 //   + Wait until we are the last non-daemon thread to execute
4214 //     <-- every thing is still working at this moment -->
4215 //   + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4216 //        shutdown hooks
4217 //   + Call before_exit(), prepare for VM exit
4218 //      > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4219 //        currently the only user of this mechanism is File.deleteOnExit())
4220 //      > stop StatSampler, watcher thread, CMS threads,
4221 //        post thread end and vm death events to JVMTI,
4222 //        stop signal thread
4223 //   + Call JavaThread::exit(), it will:
4224 //      > release JNI handle blocks, remove stack guard pages
4225 //      > remove this thread from Threads list
4226 //     <-- no more Java code from this thread after this point -->
4227 //   + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4228 //     the compiler threads at safepoint
4229 //     <-- do not use anything that could get blocked by Safepoint -->
4230 //   + Disable tracing at JNI/JVM barriers
4231 //   + Set _vm_exited flag for threads that are still running native code
4232 //   + Call exit_globals()
4233 //      > deletes tty
4234 //      > deletes PerfMemory resources
4235 //   + Delete this thread
4236 //   + Return to caller
4237 
4238 bool Threads::destroy_vm() {
4239   JavaThread* thread = JavaThread::current();
4240 
4241 #ifdef ASSERT
4242   _vm_complete = false;
4243 #endif
4244   // Wait until we are the last non-daemon thread to execute
4245   { MutexLocker nu(Threads_lock);
4246     while (Threads::number_of_non_daemon_threads() > 1)
4247       // This wait should make safepoint checks, wait without a timeout,
4248       // and wait as a suspend-equivalent condition.
4249       Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4250                          Mutex::_as_suspend_equivalent_flag);
4251   }
4252 
4253   EventShutdown e;
4254   if (e.should_commit()) {
4255     e.set_reason("No remaining non-daemon Java threads");
4256     e.commit();
4257   }
4258 
4259   // Hang forever on exit if we are reporting an error.
4260   if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4261     os::infinite_sleep();
4262   }
4263   os::wait_for_keypress_at_exit();
4264 
4265   // run Java level shutdown hooks
4266   thread->invoke_shutdown_hooks();
4267 
4268   before_exit(thread);
4269 
4270   thread->exit(true);
4271 
4272   // Stop VM thread.
4273   {
4274     // 4945125 The vm thread comes to a safepoint during exit.
4275     // GC vm_operations can get caught at the safepoint, and the
4276     // heap is unparseable if they are caught. Grab the Heap_lock
4277     // to prevent this. The GC vm_operations will not be able to
4278     // queue until after the vm thread is dead. After this point,
4279     // we'll never emerge out of the safepoint before the VM exits.
4280 
4281     MutexLockerEx ml(Heap_lock, Mutex::_no_safepoint_check_flag);
4282 
4283     VMThread::wait_for_vm_thread_exit();
4284     assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4285     VMThread::destroy();
4286   }
4287 
4288   // Now, all Java threads are gone except daemon threads. Daemon threads
4289   // running Java code or in VM are stopped by the Safepoint. However,
4290   // daemon threads executing native code are still running.  But they
4291   // will be stopped at native=>Java/VM barriers. Note that we can't
4292   // simply kill or suspend them, as it is inherently deadlock-prone.
4293 
4294   VM_Exit::set_vm_exited();
4295 
4296   // Clean up ideal graph printers after the VMThread has started
4297   // the final safepoint which will block all the Compiler threads.
4298   // Note that this Thread has already logically exited so the
4299   // clean_up() function's use of a JavaThreadIteratorWithHandle
4300   // would be a problem except set_vm_exited() has remembered the
4301   // shutdown thread which is granted a policy exception.
4302 #if defined(COMPILER2) && !defined(PRODUCT)
4303   IdealGraphPrinter::clean_up();
4304 #endif
4305 
4306   notify_vm_shutdown();
4307 
4308   // exit_globals() will delete tty
4309   exit_globals();
4310 
4311   // We are after VM_Exit::set_vm_exited() so we can't call
4312   // thread->smr_delete() or we will block on the Threads_lock.
4313   // Deleting the shutdown thread here is safe because another
4314   // JavaThread cannot have an active ThreadsListHandle for
4315   // this JavaThread.
4316   delete thread;
4317 
4318 #if INCLUDE_JVMCI
4319   if (JVMCICounterSize > 0) {
4320     FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4321   }
4322 #endif
4323 
4324   LogConfiguration::finalize();
4325 
4326   return true;
4327 }
4328 
4329 
4330 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4331   if (version == JNI_VERSION_1_1) return JNI_TRUE;
4332   return is_supported_jni_version(version);
4333 }
4334 
4335 
4336 jboolean Threads::is_supported_jni_version(jint version) {
4337   if (version == JNI_VERSION_1_2) return JNI_TRUE;
4338   if (version == JNI_VERSION_1_4) return JNI_TRUE;
4339   if (version == JNI_VERSION_1_6) return JNI_TRUE;
4340   if (version == JNI_VERSION_1_8) return JNI_TRUE;
4341   if (version == JNI_VERSION_9) return JNI_TRUE;
4342   if (version == JNI_VERSION_10) return JNI_TRUE;
4343   return JNI_FALSE;
4344 }
4345 
4346 
4347 void Threads::add(JavaThread* p, bool force_daemon) {
4348   // The threads lock must be owned at this point
4349   assert(Threads_lock->owned_by_self(), "must have threads lock");
4350 
4351   BarrierSet::barrier_set()->on_thread_attach(p);
4352 
4353   p->set_next(_thread_list);
4354   _thread_list = p;
4355 
4356   // Once a JavaThread is added to the Threads list, smr_delete() has
4357   // to be used to delete it. Otherwise we can just delete it directly.
4358   p->set_on_thread_list();
4359 
4360   _number_of_threads++;
4361   oop threadObj = p->threadObj();
4362   bool daemon = true;
4363   // Bootstrapping problem: threadObj can be null for initial
4364   // JavaThread (or for threads attached via JNI)
4365   if ((!force_daemon) && !is_daemon((threadObj))) {
4366     _number_of_non_daemon_threads++;
4367     daemon = false;
4368   }
4369 
4370   ThreadService::add_thread(p, daemon);
4371 
4372   // Maintain fast thread list
4373   ThreadsSMRSupport::add_thread(p);
4374 
4375   // Possible GC point.
4376   Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4377 }
4378 
4379 void Threads::remove(JavaThread* p) {
4380 
4381   // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread.
4382   ObjectSynchronizer::omFlush(p);
4383 
4384   // Extra scope needed for Thread_lock, so we can check
4385   // that we do not remove thread without safepoint code notice
4386   { MutexLocker ml(Threads_lock);
4387 
4388     assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present");
4389 
4390     // Maintain fast thread list
4391     ThreadsSMRSupport::remove_thread(p);
4392 
4393     JavaThread* current = _thread_list;
4394     JavaThread* prev    = NULL;
4395 
4396     while (current != p) {
4397       prev    = current;
4398       current = current->next();
4399     }
4400 
4401     if (prev) {
4402       prev->set_next(current->next());
4403     } else {
4404       _thread_list = p->next();
4405     }
4406 
4407     _number_of_threads--;
4408     oop threadObj = p->threadObj();
4409     bool daemon = true;
4410     if (!is_daemon(threadObj)) {
4411       _number_of_non_daemon_threads--;
4412       daemon = false;
4413 
4414       // Only one thread left, do a notify on the Threads_lock so a thread waiting
4415       // on destroy_vm will wake up.
4416       if (number_of_non_daemon_threads() == 1) {
4417         Threads_lock->notify_all();
4418       }
4419     }
4420     ThreadService::remove_thread(p, daemon);
4421 
4422     // Make sure that safepoint code disregard this thread. This is needed since
4423     // the thread might mess around with locks after this point. This can cause it
4424     // to do callbacks into the safepoint code. However, the safepoint code is not aware
4425     // of this thread since it is removed from the queue.
4426     p->set_terminated_value();
4427   } // unlock Threads_lock
4428 
4429   // Since Events::log uses a lock, we grab it outside the Threads_lock
4430   Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4431 }
4432 
4433 // Operations on the Threads list for GC.  These are not explicitly locked,
4434 // but the garbage collector must provide a safe context for them to run.
4435 // In particular, these things should never be called when the Threads_lock
4436 // is held by some other thread. (Note: the Safepoint abstraction also
4437 // uses the Threads_lock to guarantee this property. It also makes sure that
4438 // all threads gets blocked when exiting or starting).
4439 
4440 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4441   ALL_JAVA_THREADS(p) {
4442     p->oops_do(f, cf);
4443   }
4444   VMThread::vm_thread()->oops_do(f, cf);
4445 }
4446 
4447 void Threads::change_thread_claim_parity() {
4448   // Set the new claim parity.
4449   assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4450          "Not in range.");
4451   _thread_claim_parity++;
4452   if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4453   assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4454          "Not in range.");
4455 }
4456 
4457 #ifdef ASSERT
4458 void Threads::assert_all_threads_claimed() {
4459   ALL_JAVA_THREADS(p) {
4460     const int thread_parity = p->oops_do_parity();
4461     assert((thread_parity == _thread_claim_parity),
4462            "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4463   }
4464   VMThread* vmt = VMThread::vm_thread();
4465   const int thread_parity = vmt->oops_do_parity();
4466   assert((thread_parity == _thread_claim_parity),
4467          "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity);
4468 }
4469 #endif // ASSERT
4470 
4471 class ParallelOopsDoThreadClosure : public ThreadClosure {
4472 private:
4473   OopClosure* _f;
4474   CodeBlobClosure* _cf;
4475 public:
4476   ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {}
4477   void do_thread(Thread* t) {
4478     t->oops_do(_f, _cf);
4479   }
4480 };
4481 
4482 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4483   ParallelOopsDoThreadClosure tc(f, cf);
4484   possibly_parallel_threads_do(is_par, &tc);
4485 }
4486 
4487 void Threads::nmethods_do(CodeBlobClosure* cf) {
4488   ALL_JAVA_THREADS(p) {
4489     // This is used by the code cache sweeper to mark nmethods that are active
4490     // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4491     // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4492     if(!p->is_Code_cache_sweeper_thread()) {
4493       p->nmethods_do(cf);
4494     }
4495   }
4496 }
4497 
4498 void Threads::metadata_do(void f(Metadata*)) {
4499   ALL_JAVA_THREADS(p) {
4500     p->metadata_do(f);
4501   }
4502 }
4503 
4504 class ThreadHandlesClosure : public ThreadClosure {
4505   void (*_f)(Metadata*);
4506  public:
4507   ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4508   virtual void do_thread(Thread* thread) {
4509     thread->metadata_handles_do(_f);
4510   }
4511 };
4512 
4513 void Threads::metadata_handles_do(void f(Metadata*)) {
4514   // Only walk the Handles in Thread.
4515   ThreadHandlesClosure handles_closure(f);
4516   threads_do(&handles_closure);
4517 }
4518 
4519 void Threads::deoptimized_wrt_marked_nmethods() {
4520   ALL_JAVA_THREADS(p) {
4521     p->deoptimized_wrt_marked_nmethods();
4522   }
4523 }
4524 
4525 
4526 // Get count Java threads that are waiting to enter the specified monitor.
4527 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
4528                                                          int count,
4529                                                          address monitor) {
4530   GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4531 
4532   int i = 0;
4533   DO_JAVA_THREADS(t_list, p) {
4534     if (!p->can_call_java()) continue;
4535 
4536     address pending = (address)p->current_pending_monitor();
4537     if (pending == monitor) {             // found a match
4538       if (i < count) result->append(p);   // save the first count matches
4539       i++;
4540     }
4541   }
4542 
4543   return result;
4544 }
4545 
4546 
4547 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
4548                                                       address owner) {
4549   // NULL owner means not locked so we can skip the search
4550   if (owner == NULL) return NULL;
4551 
4552   DO_JAVA_THREADS(t_list, p) {
4553     // first, see if owner is the address of a Java thread
4554     if (owner == (address)p) return p;
4555   }
4556 
4557   // Cannot assert on lack of success here since this function may be
4558   // used by code that is trying to report useful problem information
4559   // like deadlock detection.
4560   if (UseHeavyMonitors) return NULL;
4561 
4562   // If we didn't find a matching Java thread and we didn't force use of
4563   // heavyweight monitors, then the owner is the stack address of the
4564   // Lock Word in the owning Java thread's stack.
4565   //
4566   JavaThread* the_owner = NULL;
4567   DO_JAVA_THREADS(t_list, q) {
4568     if (q->is_lock_owned(owner)) {
4569       the_owner = q;
4570       break;
4571     }
4572   }
4573 
4574   // cannot assert on lack of success here; see above comment
4575   return the_owner;
4576 }
4577 
4578 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4579 void Threads::print_on(outputStream* st, bool print_stacks,
4580                        bool internal_format, bool print_concurrent_locks,
4581                        bool print_extended_info) {
4582   char buf[32];
4583   st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4584 
4585   st->print_cr("Full thread dump %s (%s %s):",
4586                VM_Version::vm_name(),
4587                VM_Version::vm_release(),
4588                VM_Version::vm_info_string());
4589   st->cr();
4590 
4591 #if INCLUDE_SERVICES
4592   // Dump concurrent locks
4593   ConcurrentLocksDump concurrent_locks;
4594   if (print_concurrent_locks) {
4595     concurrent_locks.dump_at_safepoint();
4596   }
4597 #endif // INCLUDE_SERVICES
4598 
4599   ThreadsSMRSupport::print_info_on(st);
4600   st->cr();
4601 
4602   ALL_JAVA_THREADS(p) {
4603     ResourceMark rm;
4604     p->print_on(st, print_extended_info);
4605     if (print_stacks) {
4606       if (internal_format) {
4607         p->trace_stack();
4608       } else {
4609         p->print_stack_on(st);
4610       }
4611     }
4612     st->cr();
4613 #if INCLUDE_SERVICES
4614     if (print_concurrent_locks) {
4615       concurrent_locks.print_locks_on(p, st);
4616     }
4617 #endif // INCLUDE_SERVICES
4618   }
4619 
4620   VMThread::vm_thread()->print_on(st);
4621   st->cr();
4622   Universe::heap()->print_gc_threads_on(st);
4623   WatcherThread* wt = WatcherThread::watcher_thread();
4624   if (wt != NULL) {
4625     wt->print_on(st);
4626     st->cr();
4627   }
4628 
4629   st->flush();
4630 }
4631 
4632 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4633                              int buflen, bool* found_current) {
4634   if (this_thread != NULL) {
4635     bool is_current = (current == this_thread);
4636     *found_current = *found_current || is_current;
4637     st->print("%s", is_current ? "=>" : "  ");
4638 
4639     st->print(PTR_FORMAT, p2i(this_thread));
4640     st->print(" ");
4641     this_thread->print_on_error(st, buf, buflen);
4642     st->cr();
4643   }
4644 }
4645 
4646 class PrintOnErrorClosure : public ThreadClosure {
4647   outputStream* _st;
4648   Thread* _current;
4649   char* _buf;
4650   int _buflen;
4651   bool* _found_current;
4652  public:
4653   PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4654                       int buflen, bool* found_current) :
4655    _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4656 
4657   virtual void do_thread(Thread* thread) {
4658     Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4659   }
4660 };
4661 
4662 // Threads::print_on_error() is called by fatal error handler. It's possible
4663 // that VM is not at safepoint and/or current thread is inside signal handler.
4664 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4665 // memory (even in resource area), it might deadlock the error handler.
4666 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4667                              int buflen) {
4668   ThreadsSMRSupport::print_info_on(st);
4669   st->cr();
4670 
4671   bool found_current = false;
4672   st->print_cr("Java Threads: ( => current thread )");
4673   ALL_JAVA_THREADS(thread) {
4674     print_on_error(thread, st, current, buf, buflen, &found_current);
4675   }
4676   st->cr();
4677 
4678   st->print_cr("Other Threads:");
4679   print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4680   print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4681 
4682   PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4683   Universe::heap()->gc_threads_do(&print_closure);
4684 
4685   if (!found_current) {
4686     st->cr();
4687     st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4688     current->print_on_error(st, buf, buflen);
4689     st->cr();
4690   }
4691   st->cr();
4692 
4693   st->print_cr("Threads with active compile tasks:");
4694   print_threads_compiling(st, buf, buflen);
4695 }
4696 
4697 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4698   ALL_JAVA_THREADS(thread) {
4699     if (thread->is_Compiler_thread()) {
4700       CompilerThread* ct = (CompilerThread*) thread;
4701 
4702       // Keep task in local variable for NULL check.
4703       // ct->_task might be set to NULL by concurring compiler thread
4704       // because it completed the compilation. The task is never freed,
4705       // though, just returned to a free list.
4706       CompileTask* task = ct->task();
4707       if (task != NULL) {
4708         thread->print_name_on_error(st, buf, buflen);
4709         st->print("  ");
4710         task->print(st, NULL, true, true);
4711       }
4712     }
4713   }
4714 }
4715 
4716 
4717 // Internal SpinLock and Mutex
4718 // Based on ParkEvent
4719 
4720 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4721 //
4722 // We employ SpinLocks _only for low-contention, fixed-length
4723 // short-duration critical sections where we're concerned
4724 // about native mutex_t or HotSpot Mutex:: latency.
4725 // The mux construct provides a spin-then-block mutual exclusion
4726 // mechanism.
4727 //
4728 // Testing has shown that contention on the ListLock guarding gFreeList
4729 // is common.  If we implement ListLock as a simple SpinLock it's common
4730 // for the JVM to devolve to yielding with little progress.  This is true
4731 // despite the fact that the critical sections protected by ListLock are
4732 // extremely short.
4733 //
4734 // TODO-FIXME: ListLock should be of type SpinLock.
4735 // We should make this a 1st-class type, integrated into the lock
4736 // hierarchy as leaf-locks.  Critically, the SpinLock structure
4737 // should have sufficient padding to avoid false-sharing and excessive
4738 // cache-coherency traffic.
4739 
4740 
4741 typedef volatile int SpinLockT;
4742 
4743 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4744   if (Atomic::cmpxchg (1, adr, 0) == 0) {
4745     return;   // normal fast-path return
4746   }
4747 
4748   // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4749   int ctr = 0;
4750   int Yields = 0;
4751   for (;;) {
4752     while (*adr != 0) {
4753       ++ctr;
4754       if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4755         if (Yields > 5) {
4756           os::naked_short_sleep(1);
4757         } else {
4758           os::naked_yield();
4759           ++Yields;
4760         }
4761       } else {
4762         SpinPause();
4763       }
4764     }
4765     if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4766   }
4767 }
4768 
4769 void Thread::SpinRelease(volatile int * adr) {
4770   assert(*adr != 0, "invariant");
4771   OrderAccess::fence();      // guarantee at least release consistency.
4772   // Roach-motel semantics.
4773   // It's safe if subsequent LDs and STs float "up" into the critical section,
4774   // but prior LDs and STs within the critical section can't be allowed
4775   // to reorder or float past the ST that releases the lock.
4776   // Loads and stores in the critical section - which appear in program
4777   // order before the store that releases the lock - must also appear
4778   // before the store that releases the lock in memory visibility order.
4779   // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4780   // the ST of 0 into the lock-word which releases the lock, so fence
4781   // more than covers this on all platforms.
4782   *adr = 0;
4783 }
4784 
4785 // muxAcquire and muxRelease:
4786 //
4787 // *  muxAcquire and muxRelease support a single-word lock-word construct.
4788 //    The LSB of the word is set IFF the lock is held.
4789 //    The remainder of the word points to the head of a singly-linked list
4790 //    of threads blocked on the lock.
4791 //
4792 // *  The current implementation of muxAcquire-muxRelease uses its own
4793 //    dedicated Thread._MuxEvent instance.  If we're interested in
4794 //    minimizing the peak number of extant ParkEvent instances then
4795 //    we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4796 //    as certain invariants were satisfied.  Specifically, care would need
4797 //    to be taken with regards to consuming unpark() "permits".
4798 //    A safe rule of thumb is that a thread would never call muxAcquire()
4799 //    if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4800 //    park().  Otherwise the _ParkEvent park() operation in muxAcquire() could
4801 //    consume an unpark() permit intended for monitorenter, for instance.
4802 //    One way around this would be to widen the restricted-range semaphore
4803 //    implemented in park().  Another alternative would be to provide
4804 //    multiple instances of the PlatformEvent() for each thread.  One
4805 //    instance would be dedicated to muxAcquire-muxRelease, for instance.
4806 //
4807 // *  Usage:
4808 //    -- Only as leaf locks
4809 //    -- for short-term locking only as muxAcquire does not perform
4810 //       thread state transitions.
4811 //
4812 // Alternatives:
4813 // *  We could implement muxAcquire and muxRelease with MCS or CLH locks
4814 //    but with parking or spin-then-park instead of pure spinning.
4815 // *  Use Taura-Oyama-Yonenzawa locks.
4816 // *  It's possible to construct a 1-0 lock if we encode the lockword as
4817 //    (List,LockByte).  Acquire will CAS the full lockword while Release
4818 //    will STB 0 into the LockByte.  The 1-0 scheme admits stranding, so
4819 //    acquiring threads use timers (ParkTimed) to detect and recover from
4820 //    the stranding window.  Thread/Node structures must be aligned on 256-byte
4821 //    boundaries by using placement-new.
4822 // *  Augment MCS with advisory back-link fields maintained with CAS().
4823 //    Pictorially:  LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4824 //    The validity of the backlinks must be ratified before we trust the value.
4825 //    If the backlinks are invalid the exiting thread must back-track through the
4826 //    the forward links, which are always trustworthy.
4827 // *  Add a successor indication.  The LockWord is currently encoded as
4828 //    (List, LOCKBIT:1).  We could also add a SUCCBIT or an explicit _succ variable
4829 //    to provide the usual futile-wakeup optimization.
4830 //    See RTStt for details.
4831 //
4832 
4833 
4834 const intptr_t LOCKBIT = 1;
4835 
4836 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4837   intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4838   if (w == 0) return;
4839   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4840     return;
4841   }
4842 
4843   ParkEvent * const Self = Thread::current()->_MuxEvent;
4844   assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4845   for (;;) {
4846     int its = (os::is_MP() ? 100 : 0) + 1;
4847 
4848     // Optional spin phase: spin-then-park strategy
4849     while (--its >= 0) {
4850       w = *Lock;
4851       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4852         return;
4853       }
4854     }
4855 
4856     Self->reset();
4857     Self->OnList = intptr_t(Lock);
4858     // The following fence() isn't _strictly necessary as the subsequent
4859     // CAS() both serializes execution and ratifies the fetched *Lock value.
4860     OrderAccess::fence();
4861     for (;;) {
4862       w = *Lock;
4863       if ((w & LOCKBIT) == 0) {
4864         if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4865           Self->OnList = 0;   // hygiene - allows stronger asserts
4866           return;
4867         }
4868         continue;      // Interference -- *Lock changed -- Just retry
4869       }
4870       assert(w & LOCKBIT, "invariant");
4871       Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4872       if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4873     }
4874 
4875     while (Self->OnList != 0) {
4876       Self->park();
4877     }
4878   }
4879 }
4880 
4881 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4882   intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4883   if (w == 0) return;
4884   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4885     return;
4886   }
4887 
4888   ParkEvent * ReleaseAfter = NULL;
4889   if (ev == NULL) {
4890     ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4891   }
4892   assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4893   for (;;) {
4894     guarantee(ev->OnList == 0, "invariant");
4895     int its = (os::is_MP() ? 100 : 0) + 1;
4896 
4897     // Optional spin phase: spin-then-park strategy
4898     while (--its >= 0) {
4899       w = *Lock;
4900       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4901         if (ReleaseAfter != NULL) {
4902           ParkEvent::Release(ReleaseAfter);
4903         }
4904         return;
4905       }
4906     }
4907 
4908     ev->reset();
4909     ev->OnList = intptr_t(Lock);
4910     // The following fence() isn't _strictly necessary as the subsequent
4911     // CAS() both serializes execution and ratifies the fetched *Lock value.
4912     OrderAccess::fence();
4913     for (;;) {
4914       w = *Lock;
4915       if ((w & LOCKBIT) == 0) {
4916         if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4917           ev->OnList = 0;
4918           // We call ::Release while holding the outer lock, thus
4919           // artificially lengthening the critical section.
4920           // Consider deferring the ::Release() until the subsequent unlock(),
4921           // after we've dropped the outer lock.
4922           if (ReleaseAfter != NULL) {
4923             ParkEvent::Release(ReleaseAfter);
4924           }
4925           return;
4926         }
4927         continue;      // Interference -- *Lock changed -- Just retry
4928       }
4929       assert(w & LOCKBIT, "invariant");
4930       ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4931       if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4932     }
4933 
4934     while (ev->OnList != 0) {
4935       ev->park();
4936     }
4937   }
4938 }
4939 
4940 // Release() must extract a successor from the list and then wake that thread.
4941 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4942 // similar to that used by ParkEvent::Allocate() and ::Release().  DMR-based
4943 // Release() would :
4944 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4945 // (B) Extract a successor from the private list "in-hand"
4946 // (C) attempt to CAS() the residual back into *Lock over null.
4947 //     If there were any newly arrived threads and the CAS() would fail.
4948 //     In that case Release() would detach the RATs, re-merge the list in-hand
4949 //     with the RATs and repeat as needed.  Alternately, Release() might
4950 //     detach and extract a successor, but then pass the residual list to the wakee.
4951 //     The wakee would be responsible for reattaching and remerging before it
4952 //     competed for the lock.
4953 //
4954 // Both "pop" and DMR are immune from ABA corruption -- there can be
4955 // multiple concurrent pushers, but only one popper or detacher.
4956 // This implementation pops from the head of the list.  This is unfair,
4957 // but tends to provide excellent throughput as hot threads remain hot.
4958 // (We wake recently run threads first).
4959 //
4960 // All paths through muxRelease() will execute a CAS.
4961 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4962 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4963 // executed within the critical section are complete and globally visible before the
4964 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4965 void Thread::muxRelease(volatile intptr_t * Lock)  {
4966   for (;;) {
4967     const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT);
4968     assert(w & LOCKBIT, "invariant");
4969     if (w == LOCKBIT) return;
4970     ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4971     assert(List != NULL, "invariant");
4972     assert(List->OnList == intptr_t(Lock), "invariant");
4973     ParkEvent * const nxt = List->ListNext;
4974     guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4975 
4976     // The following CAS() releases the lock and pops the head element.
4977     // The CAS() also ratifies the previously fetched lock-word value.
4978     if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) {
4979       continue;
4980     }
4981     List->OnList = 0;
4982     OrderAccess::fence();
4983     List->unpark();
4984     return;
4985   }
4986 }
4987 
4988 
4989 void Threads::verify() {
4990   ALL_JAVA_THREADS(p) {
4991     p->verify();
4992   }
4993   VMThread* thread = VMThread::vm_thread();
4994   if (thread != NULL) thread->verify();
4995 }