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 "jfr/support/jfrThreadId.hpp"
  45 #include "jvmtifiles/jvmtiEnv.hpp"
  46 #include "logging/log.hpp"
  47 #include "logging/logConfiguration.hpp"
  48 #include "logging/logStream.hpp"
  49 #include "memory/allocation.inline.hpp"
  50 #include "memory/metaspaceShared.hpp"
  51 #include "memory/oopFactory.hpp"
  52 #include "memory/resourceArea.hpp"
  53 #include "memory/universe.hpp"
  54 #include "oops/access.inline.hpp"
  55 #include "oops/instanceKlass.hpp"
  56 #include "oops/objArrayOop.hpp"
  57 #include "oops/oop.inline.hpp"
  58 #include "oops/symbol.hpp"
  59 #include "oops/typeArrayOop.inline.hpp"
  60 #include "oops/verifyOopClosure.hpp"
  61 #include "prims/jvm_misc.hpp"
  62 #include "prims/jvmtiExport.hpp"
  63 #include "prims/jvmtiThreadState.hpp"
  64 #include "prims/privilegedStack.hpp"
  65 #include "runtime/arguments.hpp"
  66 #include "runtime/atomic.hpp"
  67 #include "runtime/biasedLocking.hpp"
  68 #include "runtime/fieldDescriptor.inline.hpp"
  69 #include "runtime/flags/jvmFlagConstraintList.hpp"
  70 #include "runtime/flags/jvmFlagRangeList.hpp"
  71 #include "runtime/flags/jvmFlagWriteableList.hpp"
  72 #include "runtime/deoptimization.hpp"
  73 #include "runtime/frame.inline.hpp"
  74 #include "runtime/handshake.hpp"
  75 #include "runtime/init.hpp"
  76 #include "runtime/interfaceSupport.inline.hpp"
  77 #include "runtime/java.hpp"
  78 #include "runtime/javaCalls.hpp"
  79 #include "runtime/jniHandles.inline.hpp"
  80 #include "runtime/jniPeriodicChecker.hpp"
  81 #include "runtime/memprofiler.hpp"
  82 #include "runtime/mutexLocker.hpp"
  83 #include "runtime/objectMonitor.hpp"
  84 #include "runtime/orderAccess.hpp"
  85 #include "runtime/osThread.hpp"
  86 #include "runtime/prefetch.inline.hpp"
  87 #include "runtime/safepoint.hpp"
  88 #include "runtime/safepointMechanism.inline.hpp"
  89 #include "runtime/safepointVerifiers.hpp"
  90 #include "runtime/sharedRuntime.hpp"
  91 #include "runtime/statSampler.hpp"
  92 #include "runtime/stubRoutines.hpp"
  93 #include "runtime/sweeper.hpp"
  94 #include "runtime/task.hpp"
  95 #include "runtime/thread.inline.hpp"
  96 #include "runtime/threadCritical.hpp"
  97 #include "runtime/threadSMR.inline.hpp"
  98 #include "runtime/threadStatisticalInfo.hpp"
  99 #include "runtime/timer.hpp"
 100 #include "runtime/timerTrace.hpp"
 101 #include "runtime/vframe.inline.hpp"
 102 #include "runtime/vframeArray.hpp"
 103 #include "runtime/vframe_hp.hpp"
 104 #include "runtime/vmThread.hpp"
 105 #include "runtime/vm_operations.hpp"
 106 #include "runtime/vm_version.hpp"
 107 #include "services/attachListener.hpp"
 108 #include "services/management.hpp"
 109 #include "services/memTracker.hpp"
 110 #include "services/threadService.hpp"
 111 #include "utilities/align.hpp"
 112 #include "utilities/copy.hpp"
 113 #include "utilities/defaultStream.hpp"
 114 #include "utilities/dtrace.hpp"
 115 #include "utilities/events.hpp"
 116 #include "utilities/macros.hpp"
 117 #include "utilities/preserveException.hpp"
 118 #include "utilities/singleWriterSynchronizer.hpp"
 119 #include "utilities/vmError.hpp"
 120 #if INCLUDE_JVMCI
 121 #include "jvmci/jvmciCompiler.hpp"
 122 #include "jvmci/jvmciRuntime.hpp"
 123 #include "logging/logHandle.hpp"
 124 #endif
 125 #ifdef COMPILER1
 126 #include "c1/c1_Compiler.hpp"
 127 #endif
 128 #ifdef COMPILER2
 129 #include "opto/c2compiler.hpp"
 130 #include "opto/idealGraphPrinter.hpp"
 131 #endif
 132 #if INCLUDE_RTM_OPT
 133 #include "runtime/rtmLocking.hpp"
 134 #endif
 135 #if INCLUDE_JFR
 136 #include "jfr/jfr.hpp"
 137 #endif
 138 
 139 // Initialization after module runtime initialization
 140 void universe_post_module_init();  // must happen after call_initPhase2
 141 
 142 #ifdef DTRACE_ENABLED
 143 
 144 // Only bother with this argument setup if dtrace is available
 145 
 146   #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
 147   #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
 148 
 149   #define DTRACE_THREAD_PROBE(probe, javathread)                           \
 150     {                                                                      \
 151       ResourceMark rm(this);                                               \
 152       int len = 0;                                                         \
 153       const char* name = (javathread)->get_thread_name();                  \
 154       len = strlen(name);                                                  \
 155       HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */               \
 156         (char *) name, len,                                                \
 157         java_lang_Thread::thread_id((javathread)->threadObj()),            \
 158         (uintptr_t) (javathread)->osthread()->thread_id(),                 \
 159         java_lang_Thread::is_daemon((javathread)->threadObj()));           \
 160     }
 161 
 162 #else //  ndef DTRACE_ENABLED
 163 
 164   #define DTRACE_THREAD_PROBE(probe, javathread)
 165 
 166 #endif // ndef DTRACE_ENABLED
 167 
 168 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 169 // Current thread is maintained as a thread-local variable
 170 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
 171 #endif
 172 
 173 // ======= Thread ========
 174 // Support for forcing alignment of thread objects for biased locking
 175 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
 176   if (UseBiasedLocking) {
 177     const int alignment = markOopDesc::biased_lock_alignment;
 178     size_t aligned_size = size + (alignment - sizeof(intptr_t));
 179     void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
 180                                           : AllocateHeap(aligned_size, flags, CURRENT_PC,
 181                                                          AllocFailStrategy::RETURN_NULL);
 182     void* aligned_addr     = align_up(real_malloc_addr, alignment);
 183     assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
 184            ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
 185            "JavaThread alignment code overflowed allocated storage");
 186     if (aligned_addr != real_malloc_addr) {
 187       log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
 188                               p2i(real_malloc_addr),
 189                               p2i(aligned_addr));
 190     }
 191     ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
 192     return aligned_addr;
 193   } else {
 194     return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
 195                        : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
 196   }
 197 }
 198 
 199 void Thread::operator delete(void* p) {
 200   if (UseBiasedLocking) {
 201     FreeHeap(((Thread*) p)->_real_malloc_address);
 202   } else {
 203     FreeHeap(p);
 204   }
 205 }
 206 
 207 void JavaThread::smr_delete() {
 208   if (_on_thread_list) {
 209     ThreadsSMRSupport::smr_delete(this);
 210   } else {
 211     delete this;
 212   }
 213 }
 214 
 215 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
 216 // JavaThread
 217 
 218 
 219 Thread::Thread() {
 220   // stack and get_thread
 221   set_stack_base(NULL);
 222   set_stack_size(0);
 223   set_self_raw_id(0);
 224   set_lgrp_id(-1);
 225   DEBUG_ONLY(clear_suspendible_thread();)
 226 
 227   // allocated data structures
 228   set_osthread(NULL);
 229   set_resource_area(new (mtThread)ResourceArea());
 230   DEBUG_ONLY(_current_resource_mark = NULL;)
 231   set_handle_area(new (mtThread) HandleArea(NULL));
 232   set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
 233   set_active_handles(NULL);
 234   set_free_handle_block(NULL);
 235   set_last_handle_mark(NULL);
 236 
 237   // This initial value ==> never claimed.
 238   _oops_do_parity = 0;
 239   _threads_hazard_ptr = NULL;
 240   _threads_list_ptr = NULL;
 241   _nested_threads_hazard_ptr_cnt = 0;
 242   _rcu_counter = 0;
 243 
 244   // the handle mark links itself to last_handle_mark
 245   new HandleMark(this);
 246 
 247   // plain initialization
 248   debug_only(_owned_locks = NULL;)
 249   debug_only(_allow_allocation_count = 0;)
 250   NOT_PRODUCT(_allow_safepoint_count = 0;)
 251   NOT_PRODUCT(_skip_gcalot = false;)
 252   _jvmti_env_iteration_count = 0;
 253   set_allocated_bytes(0);
 254   _vm_operation_started_count = 0;
 255   _vm_operation_completed_count = 0;
 256   _current_pending_monitor = NULL;
 257   _current_pending_monitor_is_from_java = true;
 258   _current_waiting_monitor = NULL;
 259   _num_nested_signal = 0;
 260   omFreeList = NULL;
 261   omFreeCount = 0;
 262   omFreeProvision = 32;
 263   omInUseList = NULL;
 264   omInUseCount = 0;
 265 
 266 #ifdef ASSERT
 267   _visited_for_critical_count = false;
 268 #endif
 269 
 270   _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
 271                          Monitor::_safepoint_check_sometimes);
 272   _suspend_flags = 0;
 273 
 274   // thread-specific hashCode stream generator state - Marsaglia shift-xor form
 275   _hashStateX = os::random();
 276   _hashStateY = 842502087;
 277   _hashStateZ = 0x8767;    // (int)(3579807591LL & 0xffff) ;
 278   _hashStateW = 273326509;
 279 
 280   _OnTrap   = 0;
 281   _Stalled  = 0;
 282   _TypeTag  = 0x2BAD;
 283 
 284   // Many of the following fields are effectively final - immutable
 285   // Note that nascent threads can't use the Native Monitor-Mutex
 286   // construct until the _MutexEvent is initialized ...
 287   // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
 288   // we might instead use a stack of ParkEvents that we could provision on-demand.
 289   // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
 290   // and ::Release()
 291   _ParkEvent   = ParkEvent::Allocate(this);
 292   _SleepEvent  = ParkEvent::Allocate(this);
 293   _MutexEvent  = ParkEvent::Allocate(this);
 294   _MuxEvent    = ParkEvent::Allocate(this);
 295 
 296 #ifdef CHECK_UNHANDLED_OOPS
 297   if (CheckUnhandledOops) {
 298     _unhandled_oops = new UnhandledOops(this);
 299   }
 300 #endif // CHECK_UNHANDLED_OOPS
 301 #ifdef ASSERT
 302   if (UseBiasedLocking) {
 303     assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
 304     assert(this == _real_malloc_address ||
 305            this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment),
 306            "bug in forced alignment of thread objects");
 307   }
 308 #endif // ASSERT
 309 
 310   // Notify the barrier set that a thread is being created. Note that some
 311   // threads are created before a barrier set is available. The call to
 312   // BarrierSet::on_thread_create() for these threads is therefore deferred
 313   // to BarrierSet::set_barrier_set().
 314   BarrierSet* const barrier_set = BarrierSet::barrier_set();
 315   if (barrier_set != NULL) {
 316     barrier_set->on_thread_create(this);
 317   } else {
 318     DEBUG_ONLY(Threads::inc_threads_before_barrier_set();)
 319   }
 320 }
 321 
 322 void Thread::initialize_thread_current() {
 323 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 324   assert(_thr_current == NULL, "Thread::current already initialized");
 325   _thr_current = this;
 326 #endif
 327   assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
 328   ThreadLocalStorage::set_thread(this);
 329   assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
 330 }
 331 
 332 void Thread::clear_thread_current() {
 333   assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
 334 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 335   _thr_current = NULL;
 336 #endif
 337   ThreadLocalStorage::set_thread(NULL);
 338 }
 339 
 340 void Thread::record_stack_base_and_size() {
 341   set_stack_base(os::current_stack_base());
 342   set_stack_size(os::current_stack_size());
 343   // CR 7190089: on Solaris, primordial thread's stack is adjusted
 344   // in initialize_thread(). Without the adjustment, stack size is
 345   // incorrect if stack is set to unlimited (ulimit -s unlimited).
 346   // So far, only Solaris has real implementation of initialize_thread().
 347   //
 348   // set up any platform-specific state.
 349   os::initialize_thread(this);
 350 
 351   // Set stack limits after thread is initialized.
 352   if (is_Java_thread()) {
 353     ((JavaThread*) this)->set_stack_overflow_limit();
 354     ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
 355   }
 356 #if INCLUDE_NMT
 357   // record thread's native stack, stack grows downward
 358   MemTracker::record_thread_stack(stack_end(), stack_size());
 359 #endif // INCLUDE_NMT
 360   log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
 361     PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
 362     os::current_thread_id(), p2i(stack_base() - stack_size()),
 363     p2i(stack_base()), stack_size()/1024);
 364 }
 365 
 366 
 367 Thread::~Thread() {
 368   JFR_ONLY(Jfr::on_thread_destruct(this);)
 369 
 370   // Notify the barrier set that a thread is being destroyed. Note that a barrier
 371   // set might not be available if we encountered errors during bootstrapping.
 372   BarrierSet* const barrier_set = BarrierSet::barrier_set();
 373   if (barrier_set != NULL) {
 374     barrier_set->on_thread_destroy(this);
 375   }
 376 
 377 
 378   // stack_base can be NULL if the thread is never started or exited before
 379   // record_stack_base_and_size called. Although, we would like to ensure
 380   // that all started threads do call record_stack_base_and_size(), there is
 381   // not proper way to enforce that.
 382 #if INCLUDE_NMT
 383   if (_stack_base != NULL) {
 384     MemTracker::release_thread_stack(stack_end(), stack_size());
 385 #ifdef ASSERT
 386     set_stack_base(NULL);
 387 #endif
 388   }
 389 #endif // INCLUDE_NMT
 390 
 391   // deallocate data structures
 392   delete resource_area();
 393   // since the handle marks are using the handle area, we have to deallocated the root
 394   // handle mark before deallocating the thread's handle area,
 395   assert(last_handle_mark() != NULL, "check we have an element");
 396   delete last_handle_mark();
 397   assert(last_handle_mark() == NULL, "check we have reached the end");
 398 
 399   // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
 400   // We NULL out the fields for good hygiene.
 401   ParkEvent::Release(_ParkEvent); _ParkEvent   = NULL;
 402   ParkEvent::Release(_SleepEvent); _SleepEvent  = NULL;
 403   ParkEvent::Release(_MutexEvent); _MutexEvent  = NULL;
 404   ParkEvent::Release(_MuxEvent); _MuxEvent    = NULL;
 405 
 406   delete handle_area();
 407   delete metadata_handles();
 408 
 409   // SR_handler uses this as a termination indicator -
 410   // needs to happen before os::free_thread()
 411   delete _SR_lock;
 412   _SR_lock = NULL;
 413 
 414   // osthread() can be NULL, if creation of thread failed.
 415   if (osthread() != NULL) os::free_thread(osthread());
 416 
 417   // clear Thread::current if thread is deleting itself.
 418   // Needed to ensure JNI correctly detects non-attached threads.
 419   if (this == Thread::current()) {
 420     clear_thread_current();
 421   }
 422 
 423   CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
 424 }
 425 
 426 // NOTE: dummy function for assertion purpose.
 427 void Thread::run() {
 428   ShouldNotReachHere();
 429 }
 430 
 431 #ifdef ASSERT
 432 // A JavaThread is considered "dangling" if it is not the current
 433 // thread, has been added the Threads list, the system is not at a
 434 // safepoint and the Thread is not "protected".
 435 //
 436 void Thread::check_for_dangling_thread_pointer(Thread *thread) {
 437   assert(!thread->is_Java_thread() || Thread::current() == thread ||
 438          !((JavaThread *) thread)->on_thread_list() ||
 439          SafepointSynchronize::is_at_safepoint() ||
 440          ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread),
 441          "possibility of dangling Thread pointer");
 442 }
 443 #endif
 444 
 445 ThreadPriority Thread::get_priority(const Thread* const thread) {
 446   ThreadPriority priority;
 447   // Can return an error!
 448   (void)os::get_priority(thread, priority);
 449   assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
 450   return priority;
 451 }
 452 
 453 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
 454   debug_only(check_for_dangling_thread_pointer(thread);)
 455   // Can return an error!
 456   (void)os::set_priority(thread, priority);
 457 }
 458 
 459 
 460 void Thread::start(Thread* thread) {
 461   // Start is different from resume in that its safety is guaranteed by context or
 462   // being called from a Java method synchronized on the Thread object.
 463   if (!DisableStartThread) {
 464     if (thread->is_Java_thread()) {
 465       // Initialize the thread state to RUNNABLE before starting this thread.
 466       // Can not set it after the thread started because we do not know the
 467       // exact thread state at that time. It could be in MONITOR_WAIT or
 468       // in SLEEPING or some other state.
 469       java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
 470                                           java_lang_Thread::RUNNABLE);
 471     }
 472     os::start_thread(thread);
 473   }
 474 }
 475 
 476 // Enqueue a VM_Operation to do the job for us - sometime later
 477 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
 478   VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
 479   VMThread::execute(vm_stop);
 480 }
 481 
 482 
 483 // Check if an external suspend request has completed (or has been
 484 // cancelled). Returns true if the thread is externally suspended and
 485 // false otherwise.
 486 //
 487 // The bits parameter returns information about the code path through
 488 // the routine. Useful for debugging:
 489 //
 490 // set in is_ext_suspend_completed():
 491 // 0x00000001 - routine was entered
 492 // 0x00000010 - routine return false at end
 493 // 0x00000100 - thread exited (return false)
 494 // 0x00000200 - suspend request cancelled (return false)
 495 // 0x00000400 - thread suspended (return true)
 496 // 0x00001000 - thread is in a suspend equivalent state (return true)
 497 // 0x00002000 - thread is native and walkable (return true)
 498 // 0x00004000 - thread is native_trans and walkable (needed retry)
 499 //
 500 // set in wait_for_ext_suspend_completion():
 501 // 0x00010000 - routine was entered
 502 // 0x00020000 - suspend request cancelled before loop (return false)
 503 // 0x00040000 - thread suspended before loop (return true)
 504 // 0x00080000 - suspend request cancelled in loop (return false)
 505 // 0x00100000 - thread suspended in loop (return true)
 506 // 0x00200000 - suspend not completed during retry loop (return false)
 507 
 508 // Helper class for tracing suspend wait debug bits.
 509 //
 510 // 0x00000100 indicates that the target thread exited before it could
 511 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
 512 // 0x00080000 each indicate a cancelled suspend request so they don't
 513 // count as wait failures either.
 514 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
 515 
 516 class TraceSuspendDebugBits : public StackObj {
 517  private:
 518   JavaThread * jt;
 519   bool         is_wait;
 520   bool         called_by_wait;  // meaningful when !is_wait
 521   uint32_t *   bits;
 522 
 523  public:
 524   TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
 525                         uint32_t *_bits) {
 526     jt             = _jt;
 527     is_wait        = _is_wait;
 528     called_by_wait = _called_by_wait;
 529     bits           = _bits;
 530   }
 531 
 532   ~TraceSuspendDebugBits() {
 533     if (!is_wait) {
 534 #if 1
 535       // By default, don't trace bits for is_ext_suspend_completed() calls.
 536       // That trace is very chatty.
 537       return;
 538 #else
 539       if (!called_by_wait) {
 540         // If tracing for is_ext_suspend_completed() is enabled, then only
 541         // trace calls to it from wait_for_ext_suspend_completion()
 542         return;
 543       }
 544 #endif
 545     }
 546 
 547     if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
 548       if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
 549         MutexLocker ml(Threads_lock);  // needed for get_thread_name()
 550         ResourceMark rm;
 551 
 552         tty->print_cr(
 553                       "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
 554                       jt->get_thread_name(), *bits);
 555 
 556         guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
 557       }
 558     }
 559   }
 560 };
 561 #undef DEBUG_FALSE_BITS
 562 
 563 
 564 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
 565                                           uint32_t *bits) {
 566   TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
 567 
 568   bool did_trans_retry = false;  // only do thread_in_native_trans retry once
 569   bool do_trans_retry;           // flag to force the retry
 570 
 571   *bits |= 0x00000001;
 572 
 573   do {
 574     do_trans_retry = false;
 575 
 576     if (is_exiting()) {
 577       // Thread is in the process of exiting. This is always checked
 578       // first to reduce the risk of dereferencing a freed JavaThread.
 579       *bits |= 0x00000100;
 580       return false;
 581     }
 582 
 583     if (!is_external_suspend()) {
 584       // Suspend request is cancelled. This is always checked before
 585       // is_ext_suspended() to reduce the risk of a rogue resume
 586       // confusing the thread that made the suspend request.
 587       *bits |= 0x00000200;
 588       return false;
 589     }
 590 
 591     if (is_ext_suspended()) {
 592       // thread is suspended
 593       *bits |= 0x00000400;
 594       return true;
 595     }
 596 
 597     // Now that we no longer do hard suspends of threads running
 598     // native code, the target thread can be changing thread state
 599     // while we are in this routine:
 600     //
 601     //   _thread_in_native -> _thread_in_native_trans -> _thread_blocked
 602     //
 603     // We save a copy of the thread state as observed at this moment
 604     // and make our decision about suspend completeness based on the
 605     // copy. This closes the race where the thread state is seen as
 606     // _thread_in_native_trans in the if-thread_blocked check, but is
 607     // seen as _thread_blocked in if-thread_in_native_trans check.
 608     JavaThreadState save_state = thread_state();
 609 
 610     if (save_state == _thread_blocked && is_suspend_equivalent()) {
 611       // If the thread's state is _thread_blocked and this blocking
 612       // condition is known to be equivalent to a suspend, then we can
 613       // consider the thread to be externally suspended. This means that
 614       // the code that sets _thread_blocked has been modified to do
 615       // self-suspension if the blocking condition releases. We also
 616       // used to check for CONDVAR_WAIT here, but that is now covered by
 617       // the _thread_blocked with self-suspension check.
 618       //
 619       // Return true since we wouldn't be here unless there was still an
 620       // external suspend request.
 621       *bits |= 0x00001000;
 622       return true;
 623     } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
 624       // Threads running native code will self-suspend on native==>VM/Java
 625       // transitions. If its stack is walkable (should always be the case
 626       // unless this function is called before the actual java_suspend()
 627       // call), then the wait is done.
 628       *bits |= 0x00002000;
 629       return true;
 630     } else if (!called_by_wait && !did_trans_retry &&
 631                save_state == _thread_in_native_trans &&
 632                frame_anchor()->walkable()) {
 633       // The thread is transitioning from thread_in_native to another
 634       // thread state. check_safepoint_and_suspend_for_native_trans()
 635       // will force the thread to self-suspend. If it hasn't gotten
 636       // there yet we may have caught the thread in-between the native
 637       // code check above and the self-suspend. Lucky us. If we were
 638       // called by wait_for_ext_suspend_completion(), then it
 639       // will be doing the retries so we don't have to.
 640       //
 641       // Since we use the saved thread state in the if-statement above,
 642       // there is a chance that the thread has already transitioned to
 643       // _thread_blocked by the time we get here. In that case, we will
 644       // make a single unnecessary pass through the logic below. This
 645       // doesn't hurt anything since we still do the trans retry.
 646 
 647       *bits |= 0x00004000;
 648 
 649       // Once the thread leaves thread_in_native_trans for another
 650       // thread state, we break out of this retry loop. We shouldn't
 651       // need this flag to prevent us from getting back here, but
 652       // sometimes paranoia is good.
 653       did_trans_retry = true;
 654 
 655       // We wait for the thread to transition to a more usable state.
 656       for (int i = 1; i <= SuspendRetryCount; i++) {
 657         // We used to do an "os::yield_all(i)" call here with the intention
 658         // that yielding would increase on each retry. However, the parameter
 659         // is ignored on Linux which means the yield didn't scale up. Waiting
 660         // on the SR_lock below provides a much more predictable scale up for
 661         // the delay. It also provides a simple/direct point to check for any
 662         // safepoint requests from the VMThread
 663 
 664         // temporarily drops SR_lock while doing wait with safepoint check
 665         // (if we're a JavaThread - the WatcherThread can also call this)
 666         // and increase delay with each retry
 667         SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 668 
 669         // check the actual thread state instead of what we saved above
 670         if (thread_state() != _thread_in_native_trans) {
 671           // the thread has transitioned to another thread state so
 672           // try all the checks (except this one) one more time.
 673           do_trans_retry = true;
 674           break;
 675         }
 676       } // end retry loop
 677 
 678 
 679     }
 680   } while (do_trans_retry);
 681 
 682   *bits |= 0x00000010;
 683   return false;
 684 }
 685 
 686 // Wait for an external suspend request to complete (or be cancelled).
 687 // Returns true if the thread is externally suspended and false otherwise.
 688 //
 689 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
 690                                                  uint32_t *bits) {
 691   TraceSuspendDebugBits tsdb(this, true /* is_wait */,
 692                              false /* !called_by_wait */, bits);
 693 
 694   // local flag copies to minimize SR_lock hold time
 695   bool is_suspended;
 696   bool pending;
 697   uint32_t reset_bits;
 698 
 699   // set a marker so is_ext_suspend_completed() knows we are the caller
 700   *bits |= 0x00010000;
 701 
 702   // We use reset_bits to reinitialize the bits value at the top of
 703   // each retry loop. This allows the caller to make use of any
 704   // unused bits for their own marking purposes.
 705   reset_bits = *bits;
 706 
 707   {
 708     MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
 709     is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 710                                             delay, bits);
 711     pending = is_external_suspend();
 712   }
 713   // must release SR_lock to allow suspension to complete
 714 
 715   if (!pending) {
 716     // A cancelled suspend request is the only false return from
 717     // is_ext_suspend_completed() that keeps us from entering the
 718     // retry loop.
 719     *bits |= 0x00020000;
 720     return false;
 721   }
 722 
 723   if (is_suspended) {
 724     *bits |= 0x00040000;
 725     return true;
 726   }
 727 
 728   for (int i = 1; i <= retries; i++) {
 729     *bits = reset_bits;  // reinit to only track last retry
 730 
 731     // We used to do an "os::yield_all(i)" call here with the intention
 732     // that yielding would increase on each retry. However, the parameter
 733     // is ignored on Linux which means the yield didn't scale up. Waiting
 734     // on the SR_lock below provides a much more predictable scale up for
 735     // the delay. It also provides a simple/direct point to check for any
 736     // safepoint requests from the VMThread
 737 
 738     {
 739       MutexLocker ml(SR_lock());
 740       // wait with safepoint check (if we're a JavaThread - the WatcherThread
 741       // can also call this)  and increase delay with each retry
 742       SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 743 
 744       is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 745                                               delay, bits);
 746 
 747       // It is possible for the external suspend request to be cancelled
 748       // (by a resume) before the actual suspend operation is completed.
 749       // Refresh our local copy to see if we still need to wait.
 750       pending = is_external_suspend();
 751     }
 752 
 753     if (!pending) {
 754       // A cancelled suspend request is the only false return from
 755       // is_ext_suspend_completed() that keeps us from staying in the
 756       // retry loop.
 757       *bits |= 0x00080000;
 758       return false;
 759     }
 760 
 761     if (is_suspended) {
 762       *bits |= 0x00100000;
 763       return true;
 764     }
 765   } // end retry loop
 766 
 767   // thread did not suspend after all our retries
 768   *bits |= 0x00200000;
 769   return false;
 770 }
 771 
 772 // Called from API entry points which perform stack walking. If the
 773 // associated JavaThread is the current thread, then wait_for_suspend
 774 // is not used. Otherwise, it determines if we should wait for the
 775 // "other" thread to complete external suspension. (NOTE: in future
 776 // releases the suspension mechanism should be reimplemented so this
 777 // is not necessary.)
 778 //
 779 bool
 780 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) {
 781   if (this != JavaThread::current()) {
 782     // "other" threads require special handling.
 783     if (wait_for_suspend) {
 784       // We are allowed to wait for the external suspend to complete
 785       // so give the other thread a chance to get suspended.
 786       if (!wait_for_ext_suspend_completion(SuspendRetryCount,
 787                                            SuspendRetryDelay, bits)) {
 788         // Didn't make it so let the caller know.
 789         return false;
 790       }
 791     }
 792     // We aren't allowed to wait for the external suspend to complete
 793     // so if the other thread isn't externally suspended we need to
 794     // let the caller know.
 795     else if (!is_ext_suspend_completed_with_lock(bits)) {
 796       return false;
 797     }
 798   }
 799 
 800   return true;
 801 }
 802 
 803 #ifndef PRODUCT
 804 void JavaThread::record_jump(address target, address instr, const char* file,
 805                              int line) {
 806 
 807   // This should not need to be atomic as the only way for simultaneous
 808   // updates is via interrupts. Even then this should be rare or non-existent
 809   // and we don't care that much anyway.
 810 
 811   int index = _jmp_ring_index;
 812   _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
 813   _jmp_ring[index]._target = (intptr_t) target;
 814   _jmp_ring[index]._instruction = (intptr_t) instr;
 815   _jmp_ring[index]._file = file;
 816   _jmp_ring[index]._line = line;
 817 }
 818 #endif // PRODUCT
 819 
 820 void Thread::interrupt(Thread* thread) {
 821   debug_only(check_for_dangling_thread_pointer(thread);)
 822   os::interrupt(thread);
 823 }
 824 
 825 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
 826   debug_only(check_for_dangling_thread_pointer(thread);)
 827   // Note:  If clear_interrupted==false, this simply fetches and
 828   // returns the value of the field osthread()->interrupted().
 829   return os::is_interrupted(thread, clear_interrupted);
 830 }
 831 
 832 
 833 // GC Support
 834 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
 835   int thread_parity = _oops_do_parity;
 836   if (thread_parity != strong_roots_parity) {
 837     jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
 838     if (res == thread_parity) {
 839       return true;
 840     } else {
 841       guarantee(res == strong_roots_parity, "Or else what?");
 842       return false;
 843     }
 844   }
 845   return false;
 846 }
 847 
 848 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
 849   active_handles()->oops_do(f);
 850   // Do oop for ThreadShadow
 851   f->do_oop((oop*)&_pending_exception);
 852   handle_area()->oops_do(f);
 853 
 854   // We scan thread local monitor lists here, and the remaining global
 855   // monitors in ObjectSynchronizer::oops_do().
 856   ObjectSynchronizer::thread_local_used_oops_do(this, f);
 857 }
 858 
 859 void Thread::metadata_handles_do(void f(Metadata*)) {
 860   // Only walk the Handles in Thread.
 861   if (metadata_handles() != NULL) {
 862     for (int i = 0; i< metadata_handles()->length(); i++) {
 863       f(metadata_handles()->at(i));
 864     }
 865   }
 866 }
 867 
 868 void Thread::print_on(outputStream* st, bool print_extended_info) const {
 869   // get_priority assumes osthread initialized
 870   if (osthread() != NULL) {
 871     int os_prio;
 872     if (os::get_native_priority(this, &os_prio) == OS_OK) {
 873       st->print("os_prio=%d ", os_prio);
 874     }
 875 
 876     st->print("cpu=%.2fms ",
 877               os::thread_cpu_time(const_cast<Thread*>(this), true) / 1000000.0
 878               );
 879     st->print("elapsed=%.2fs ",
 880               _statistical_info.getElapsedTime() / 1000.0
 881               );
 882     if (is_Java_thread() && (PrintExtendedThreadInfo || print_extended_info)) {
 883       size_t allocated_bytes = (size_t) const_cast<Thread*>(this)->cooked_allocated_bytes();
 884       st->print("allocated=" SIZE_FORMAT "%s ",
 885                 byte_size_in_proper_unit(allocated_bytes),
 886                 proper_unit_for_byte_size(allocated_bytes)
 887                 );
 888       st->print("defined_classes=" INT64_FORMAT " ", _statistical_info.getDefineClassCount());
 889     }
 890 
 891     st->print("tid=" INTPTR_FORMAT " ", p2i(this));
 892     osthread()->print_on(st);
 893   }
 894   ThreadsSMRSupport::print_info_on(this, st);
 895   st->print(" ");
 896   debug_only(if (WizardMode) print_owned_locks_on(st);)
 897 }
 898 
 899 // Thread::print_on_error() is called by fatal error handler. Don't use
 900 // any lock or allocate memory.
 901 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
 902   assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
 903 
 904   if (is_VM_thread())                 { st->print("VMThread"); }
 905   else if (is_GC_task_thread())       { st->print("GCTaskThread"); }
 906   else if (is_Watcher_thread())       { st->print("WatcherThread"); }
 907   else if (is_ConcurrentGC_thread())  { st->print("ConcurrentGCThread"); }
 908   else                                { st->print("Thread"); }
 909 
 910   if (is_Named_thread()) {
 911     st->print(" \"%s\"", name());
 912   }
 913 
 914   st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
 915             p2i(stack_end()), p2i(stack_base()));
 916 
 917   if (osthread()) {
 918     st->print(" [id=%d]", osthread()->thread_id());
 919   }
 920 
 921   ThreadsSMRSupport::print_info_on(this, st);
 922 }
 923 
 924 void Thread::print_value_on(outputStream* st) const {
 925   if (is_Named_thread()) {
 926     st->print(" \"%s\" ", name());
 927   }
 928   st->print(INTPTR_FORMAT, p2i(this));   // print address
 929 }
 930 
 931 #ifdef ASSERT
 932 void Thread::print_owned_locks_on(outputStream* st) const {
 933   Monitor *cur = _owned_locks;
 934   if (cur == NULL) {
 935     st->print(" (no locks) ");
 936   } else {
 937     st->print_cr(" Locks owned:");
 938     while (cur) {
 939       cur->print_on(st);
 940       cur = cur->next();
 941     }
 942   }
 943 }
 944 
 945 static int ref_use_count  = 0;
 946 
 947 bool Thread::owns_locks_but_compiled_lock() const {
 948   for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 949     if (cur != Compile_lock) return true;
 950   }
 951   return false;
 952 }
 953 
 954 
 955 #endif
 956 
 957 #ifndef PRODUCT
 958 
 959 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially
 960 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that
 961 // no locks which allow_vm_block's are held
 962 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
 963   // Check if current thread is allowed to block at a safepoint
 964   if (!(_allow_safepoint_count == 0)) {
 965     fatal("Possible safepoint reached by thread that does not allow it");
 966   }
 967   if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
 968     fatal("LEAF method calling lock?");
 969   }
 970 
 971 #ifdef ASSERT
 972   if (potential_vm_operation && is_Java_thread()
 973       && !Universe::is_bootstrapping()) {
 974     // Make sure we do not hold any locks that the VM thread also uses.
 975     // This could potentially lead to deadlocks
 976     for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 977       // Threads_lock is special, since the safepoint synchronization will not start before this is
 978       // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
 979       // since it is used to transfer control between JavaThreads and the VMThread
 980       // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
 981       if ((cur->allow_vm_block() &&
 982            cur != Threads_lock &&
 983            cur != Compile_lock &&               // Temporary: should not be necessary when we get separate compilation
 984            cur != VMOperationRequest_lock &&
 985            cur != VMOperationQueue_lock) ||
 986            cur->rank() == Mutex::special) {
 987         fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
 988       }
 989     }
 990   }
 991 
 992   if (GCALotAtAllSafepoints) {
 993     // We could enter a safepoint here and thus have a gc
 994     InterfaceSupport::check_gc_alot();
 995   }
 996 #endif
 997 }
 998 #endif
 999 
1000 bool Thread::is_in_stack(address adr) const {
1001   assert(Thread::current() == this, "is_in_stack can only be called from current thread");
1002   address end = os::current_stack_pointer();
1003   // Allow non Java threads to call this without stack_base
1004   if (_stack_base == NULL) return true;
1005   if (stack_base() >= adr && adr >= end) return true;
1006 
1007   return false;
1008 }
1009 
1010 bool Thread::is_in_usable_stack(address adr) const {
1011   size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
1012   size_t usable_stack_size = _stack_size - stack_guard_size;
1013 
1014   return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
1015 }
1016 
1017 
1018 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
1019 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
1020 // used for compilation in the future. If that change is made, the need for these methods
1021 // should be revisited, and they should be removed if possible.
1022 
1023 bool Thread::is_lock_owned(address adr) const {
1024   return on_local_stack(adr);
1025 }
1026 
1027 bool Thread::set_as_starting_thread() {
1028   // NOTE: this must be called inside the main thread.
1029   return os::create_main_thread((JavaThread*)this);
1030 }
1031 
1032 static void initialize_class(Symbol* class_name, TRAPS) {
1033   Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
1034   InstanceKlass::cast(klass)->initialize(CHECK);
1035 }
1036 
1037 
1038 // Creates the initial ThreadGroup
1039 static Handle create_initial_thread_group(TRAPS) {
1040   Handle system_instance = JavaCalls::construct_new_instance(
1041                             SystemDictionary::ThreadGroup_klass(),
1042                             vmSymbols::void_method_signature(),
1043                             CHECK_NH);
1044   Universe::set_system_thread_group(system_instance());
1045 
1046   Handle string = java_lang_String::create_from_str("main", CHECK_NH);
1047   Handle main_instance = JavaCalls::construct_new_instance(
1048                             SystemDictionary::ThreadGroup_klass(),
1049                             vmSymbols::threadgroup_string_void_signature(),
1050                             system_instance,
1051                             string,
1052                             CHECK_NH);
1053   return main_instance;
1054 }
1055 
1056 // Creates the initial Thread
1057 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
1058                                  TRAPS) {
1059   InstanceKlass* ik = SystemDictionary::Thread_klass();
1060   assert(ik->is_initialized(), "must be");
1061   instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
1062 
1063   // Cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1064   // constructor calls Thread.current(), which must be set here for the
1065   // initial thread.
1066   java_lang_Thread::set_thread(thread_oop(), thread);
1067   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1068   thread->set_threadObj(thread_oop());
1069 
1070   Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1071 
1072   JavaValue result(T_VOID);
1073   JavaCalls::call_special(&result, thread_oop,
1074                           ik,
1075                           vmSymbols::object_initializer_name(),
1076                           vmSymbols::threadgroup_string_void_signature(),
1077                           thread_group,
1078                           string,
1079                           CHECK_NULL);
1080   return thread_oop();
1081 }
1082 
1083 char java_runtime_name[128] = "";
1084 char java_runtime_version[128] = "";
1085 
1086 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1087 static const char* get_java_runtime_name(TRAPS) {
1088   Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1089                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1090   fieldDescriptor fd;
1091   bool found = k != NULL &&
1092                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1093                                                         vmSymbols::string_signature(), &fd);
1094   if (found) {
1095     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1096     if (name_oop == NULL) {
1097       return NULL;
1098     }
1099     const char* name = java_lang_String::as_utf8_string(name_oop,
1100                                                         java_runtime_name,
1101                                                         sizeof(java_runtime_name));
1102     return name;
1103   } else {
1104     return NULL;
1105   }
1106 }
1107 
1108 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1109 static const char* get_java_runtime_version(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_version_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_version,
1123                                                         sizeof(java_runtime_version));
1124     return name;
1125   } else {
1126     return NULL;
1127   }
1128 }
1129 
1130 // General purpose hook into Java code, run once when the VM is initialized.
1131 // The Java library method itself may be changed independently from the VM.
1132 static void call_postVMInitHook(TRAPS) {
1133   Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1134   if (klass != NULL) {
1135     JavaValue result(T_VOID);
1136     JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1137                            vmSymbols::void_method_signature(),
1138                            CHECK);
1139   }
1140 }
1141 
1142 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1143                                     bool daemon, TRAPS) {
1144   assert(thread_group.not_null(), "thread group should be specified");
1145   assert(threadObj() == NULL, "should only create Java thread object once");
1146 
1147   InstanceKlass* ik = SystemDictionary::Thread_klass();
1148   assert(ik->is_initialized(), "must be");
1149   instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1150 
1151   // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon.
1152   // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1153   // constructor calls Thread.current(), which must be set here.
1154   java_lang_Thread::set_thread(thread_oop(), this);
1155   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1156   set_threadObj(thread_oop());
1157 
1158   JavaValue result(T_VOID);
1159   if (thread_name != NULL) {
1160     Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1161     // Thread gets assigned specified name and null target
1162     JavaCalls::call_special(&result,
1163                             thread_oop,
1164                             ik,
1165                             vmSymbols::object_initializer_name(),
1166                             vmSymbols::threadgroup_string_void_signature(),
1167                             thread_group,
1168                             name,
1169                             THREAD);
1170   } else {
1171     // Thread gets assigned name "Thread-nnn" and null target
1172     // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1173     JavaCalls::call_special(&result,
1174                             thread_oop,
1175                             ik,
1176                             vmSymbols::object_initializer_name(),
1177                             vmSymbols::threadgroup_runnable_void_signature(),
1178                             thread_group,
1179                             Handle(),
1180                             THREAD);
1181   }
1182 
1183 
1184   if (daemon) {
1185     java_lang_Thread::set_daemon(thread_oop());
1186   }
1187 
1188   if (HAS_PENDING_EXCEPTION) {
1189     return;
1190   }
1191 
1192   Klass* group =  SystemDictionary::ThreadGroup_klass();
1193   Handle threadObj(THREAD, this->threadObj());
1194 
1195   JavaCalls::call_special(&result,
1196                           thread_group,
1197                           group,
1198                           vmSymbols::add_method_name(),
1199                           vmSymbols::thread_void_signature(),
1200                           threadObj,          // Arg 1
1201                           THREAD);
1202 }
1203 
1204 // List of all NonJavaThreads and safe iteration over that list.
1205 
1206 class NonJavaThread::List {
1207 public:
1208   NonJavaThread* volatile _head;
1209   SingleWriterSynchronizer _protect;
1210 
1211   List() : _head(NULL), _protect() {}
1212 };
1213 
1214 NonJavaThread::List NonJavaThread::_the_list;
1215 
1216 NonJavaThread::Iterator::Iterator() :
1217   _protect_enter(_the_list._protect.enter()),
1218   _current(OrderAccess::load_acquire(&_the_list._head))
1219 {}
1220 
1221 NonJavaThread::Iterator::~Iterator() {
1222   _the_list._protect.exit(_protect_enter);
1223 }
1224 
1225 void NonJavaThread::Iterator::step() {
1226   assert(!end(), "precondition");
1227   _current = OrderAccess::load_acquire(&_current->_next);
1228 }
1229 
1230 NonJavaThread::NonJavaThread() : Thread(), _next(NULL) {
1231   // Add this thread to _the_list.
1232   MutexLockerEx lock(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1233   _next = _the_list._head;
1234   OrderAccess::release_store(&_the_list._head, this);
1235 }
1236 
1237 NonJavaThread::~NonJavaThread() {
1238   // Remove this thread from _the_list.
1239   MutexLockerEx lock(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1240   NonJavaThread* volatile* p = &_the_list._head;
1241   for (NonJavaThread* t = *p; t != NULL; p = &t->_next, t = *p) {
1242     if (t == this) {
1243       *p = this->_next;
1244       // Wait for any in-progress iterators.
1245       _the_list._protect.synchronize();
1246       break;
1247     }
1248   }
1249 }
1250 
1251 // NamedThread --  non-JavaThread subclasses with multiple
1252 // uniquely named instances should derive from this.
1253 NamedThread::NamedThread() :
1254   NonJavaThread(),
1255   _name(NULL),
1256   _processed_thread(NULL),
1257   _gc_id(GCId::undefined())
1258 {}
1259 
1260 NamedThread::~NamedThread() {
1261   if (_name != NULL) {
1262     FREE_C_HEAP_ARRAY(char, _name);
1263     _name = NULL;
1264   }
1265 }
1266 
1267 void NamedThread::set_name(const char* format, ...) {
1268   guarantee(_name == NULL, "Only get to set name once.");
1269   _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1270   guarantee(_name != NULL, "alloc failure");
1271   va_list ap;
1272   va_start(ap, format);
1273   jio_vsnprintf(_name, max_name_len, format, ap);
1274   va_end(ap);
1275 }
1276 
1277 void NamedThread::initialize_named_thread() {
1278   set_native_thread_name(name());
1279 }
1280 
1281 void NamedThread::print_on(outputStream* st) const {
1282   st->print("\"%s\" ", name());
1283   Thread::print_on(st);
1284   st->cr();
1285 }
1286 
1287 
1288 // ======= WatcherThread ========
1289 
1290 // The watcher thread exists to simulate timer interrupts.  It should
1291 // be replaced by an abstraction over whatever native support for
1292 // timer interrupts exists on the platform.
1293 
1294 WatcherThread* WatcherThread::_watcher_thread   = NULL;
1295 bool WatcherThread::_startable = false;
1296 volatile bool  WatcherThread::_should_terminate = false;
1297 
1298 WatcherThread::WatcherThread() : NonJavaThread() {
1299   assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1300   if (os::create_thread(this, os::watcher_thread)) {
1301     _watcher_thread = this;
1302 
1303     // Set the watcher thread to the highest OS priority which should not be
1304     // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1305     // is created. The only normal thread using this priority is the reference
1306     // handler thread, which runs for very short intervals only.
1307     // If the VMThread's priority is not lower than the WatcherThread profiling
1308     // will be inaccurate.
1309     os::set_priority(this, MaxPriority);
1310     if (!DisableStartThread) {
1311       os::start_thread(this);
1312     }
1313   }
1314 }
1315 
1316 int WatcherThread::sleep() const {
1317   // The WatcherThread does not participate in the safepoint protocol
1318   // for the PeriodicTask_lock because it is not a JavaThread.
1319   MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1320 
1321   if (_should_terminate) {
1322     // check for termination before we do any housekeeping or wait
1323     return 0;  // we did not sleep.
1324   }
1325 
1326   // remaining will be zero if there are no tasks,
1327   // causing the WatcherThread to sleep until a task is
1328   // enrolled
1329   int remaining = PeriodicTask::time_to_wait();
1330   int time_slept = 0;
1331 
1332   // we expect this to timeout - we only ever get unparked when
1333   // we should terminate or when a new task has been enrolled
1334   OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1335 
1336   jlong time_before_loop = os::javaTimeNanos();
1337 
1338   while (true) {
1339     bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1340                                             remaining);
1341     jlong now = os::javaTimeNanos();
1342 
1343     if (remaining == 0) {
1344       // if we didn't have any tasks we could have waited for a long time
1345       // consider the time_slept zero and reset time_before_loop
1346       time_slept = 0;
1347       time_before_loop = now;
1348     } else {
1349       // need to recalculate since we might have new tasks in _tasks
1350       time_slept = (int) ((now - time_before_loop) / 1000000);
1351     }
1352 
1353     // Change to task list or spurious wakeup of some kind
1354     if (timedout || _should_terminate) {
1355       break;
1356     }
1357 
1358     remaining = PeriodicTask::time_to_wait();
1359     if (remaining == 0) {
1360       // Last task was just disenrolled so loop around and wait until
1361       // another task gets enrolled
1362       continue;
1363     }
1364 
1365     remaining -= time_slept;
1366     if (remaining <= 0) {
1367       break;
1368     }
1369   }
1370 
1371   return time_slept;
1372 }
1373 
1374 void WatcherThread::run() {
1375   assert(this == watcher_thread(), "just checking");
1376 
1377   this->record_stack_base_and_size();
1378   this->set_native_thread_name(this->name());
1379   this->set_active_handles(JNIHandleBlock::allocate_block());
1380   while (true) {
1381     assert(watcher_thread() == Thread::current(), "thread consistency check");
1382     assert(watcher_thread() == this, "thread consistency check");
1383 
1384     // Calculate how long it'll be until the next PeriodicTask work
1385     // should be done, and sleep that amount of time.
1386     int time_waited = sleep();
1387 
1388     if (VMError::is_error_reported()) {
1389       // A fatal error has happened, the error handler(VMError::report_and_die)
1390       // should abort JVM after creating an error log file. However in some
1391       // rare cases, the error handler itself might deadlock. Here periodically
1392       // check for error reporting timeouts, and if it happens, just proceed to
1393       // abort the VM.
1394 
1395       // This code is in WatcherThread because WatcherThread wakes up
1396       // periodically so the fatal error handler doesn't need to do anything;
1397       // also because the WatcherThread is less likely to crash than other
1398       // threads.
1399 
1400       for (;;) {
1401         // Note: we use naked sleep in this loop because we want to avoid using
1402         // any kind of VM infrastructure which may be broken at this point.
1403         if (VMError::check_timeout()) {
1404           // We hit error reporting timeout. Error reporting was interrupted and
1405           // will be wrapping things up now (closing files etc). Give it some more
1406           // time, then quit the VM.
1407           os::naked_short_sleep(200);
1408           // Print a message to stderr.
1409           fdStream err(defaultStream::output_fd());
1410           err.print_raw_cr("# [ timer expired, abort... ]");
1411           // skip atexit/vm_exit/vm_abort hooks
1412           os::die();
1413         }
1414 
1415         // Wait a second, then recheck for timeout.
1416         os::naked_short_sleep(999);
1417       }
1418     }
1419 
1420     if (_should_terminate) {
1421       // check for termination before posting the next tick
1422       break;
1423     }
1424 
1425     PeriodicTask::real_time_tick(time_waited);
1426   }
1427 
1428   // Signal that it is terminated
1429   {
1430     MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1431     _watcher_thread = NULL;
1432     Terminator_lock->notify();
1433   }
1434 }
1435 
1436 void WatcherThread::start() {
1437   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1438 
1439   if (watcher_thread() == NULL && _startable) {
1440     _should_terminate = false;
1441     // Create the single instance of WatcherThread
1442     new WatcherThread();
1443   }
1444 }
1445 
1446 void WatcherThread::make_startable() {
1447   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1448   _startable = true;
1449 }
1450 
1451 void WatcherThread::stop() {
1452   {
1453     // Follow normal safepoint aware lock enter protocol since the
1454     // WatcherThread is stopped by another JavaThread.
1455     MutexLocker ml(PeriodicTask_lock);
1456     _should_terminate = true;
1457 
1458     WatcherThread* watcher = watcher_thread();
1459     if (watcher != NULL) {
1460       // unpark the WatcherThread so it can see that it should terminate
1461       watcher->unpark();
1462     }
1463   }
1464 
1465   MutexLocker mu(Terminator_lock);
1466 
1467   while (watcher_thread() != NULL) {
1468     // This wait should make safepoint checks, wait without a timeout,
1469     // and wait as a suspend-equivalent condition.
1470     Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1471                           Mutex::_as_suspend_equivalent_flag);
1472   }
1473 }
1474 
1475 void WatcherThread::unpark() {
1476   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1477   PeriodicTask_lock->notify();
1478 }
1479 
1480 void WatcherThread::print_on(outputStream* st) const {
1481   st->print("\"%s\" ", name());
1482   Thread::print_on(st);
1483   st->cr();
1484 }
1485 
1486 // ======= JavaThread ========
1487 
1488 #if INCLUDE_JVMCI
1489 
1490 jlong* JavaThread::_jvmci_old_thread_counters;
1491 
1492 bool jvmci_counters_include(JavaThread* thread) {
1493   return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1494 }
1495 
1496 void JavaThread::collect_counters(typeArrayOop array) {
1497   if (JVMCICounterSize > 0) {
1498     JavaThreadIteratorWithHandle jtiwh;
1499     for (int i = 0; i < array->length(); i++) {
1500       array->long_at_put(i, _jvmci_old_thread_counters[i]);
1501     }
1502     for (; JavaThread *tp = jtiwh.next(); ) {
1503       if (jvmci_counters_include(tp)) {
1504         for (int i = 0; i < array->length(); i++) {
1505           array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1506         }
1507       }
1508     }
1509   }
1510 }
1511 
1512 #endif // INCLUDE_JVMCI
1513 
1514 // A JavaThread is a normal Java thread
1515 
1516 void JavaThread::initialize() {
1517   // Initialize fields
1518 
1519   set_saved_exception_pc(NULL);
1520   set_threadObj(NULL);
1521   _anchor.clear();
1522   set_entry_point(NULL);
1523   set_jni_functions(jni_functions());
1524   set_callee_target(NULL);
1525   set_vm_result(NULL);
1526   set_vm_result_2(NULL);
1527   set_vframe_array_head(NULL);
1528   set_vframe_array_last(NULL);
1529   set_deferred_locals(NULL);
1530   set_deopt_mark(NULL);
1531   set_deopt_compiled_method(NULL);
1532   clear_must_deopt_id();
1533   set_monitor_chunks(NULL);
1534   set_next(NULL);
1535   _on_thread_list = false;
1536   set_thread_state(_thread_new);
1537   _terminated = _not_terminated;
1538   _privileged_stack_top = NULL;
1539   _array_for_gc = NULL;
1540   _suspend_equivalent = false;
1541   _in_deopt_handler = 0;
1542   _doing_unsafe_access = false;
1543   _stack_guard_state = stack_guard_unused;
1544 #if INCLUDE_JVMCI
1545   _pending_monitorenter = false;
1546   _pending_deoptimization = -1;
1547   _pending_failed_speculation = 0;
1548   _pending_transfer_to_interpreter = false;
1549   _adjusting_comp_level = false;
1550   _in_retryable_allocation = false;
1551   _jvmci._alternate_call_target = NULL;
1552   assert(_jvmci._implicit_exception_pc == NULL, "must be");
1553   if (JVMCICounterSize > 0) {
1554     _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1555     memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1556   } else {
1557     _jvmci_counters = NULL;
1558   }
1559 #endif // INCLUDE_JVMCI
1560   _reserved_stack_activation = NULL;  // stack base not known yet
1561   (void)const_cast<oop&>(_exception_oop = oop(NULL));
1562   _exception_pc  = 0;
1563   _exception_handler_pc = 0;
1564   _is_method_handle_return = 0;
1565   _jvmti_thread_state= NULL;
1566   _should_post_on_exceptions_flag = JNI_FALSE;
1567   _interp_only_mode    = 0;
1568   _special_runtime_exit_condition = _no_async_condition;
1569   _pending_async_exception = NULL;
1570   _thread_stat = NULL;
1571   _thread_stat = new ThreadStatistics();
1572   _blocked_on_compilation = false;
1573   _jni_active_critical = 0;
1574   _pending_jni_exception_check_fn = NULL;
1575   _do_not_unlock_if_synchronized = false;
1576   _cached_monitor_info = NULL;
1577   _parker = Parker::Allocate(this);
1578 
1579 #ifndef PRODUCT
1580   _jmp_ring_index = 0;
1581   for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1582     record_jump(NULL, NULL, NULL, 0);
1583   }
1584 #endif // PRODUCT
1585 
1586   // Setup safepoint state info for this thread
1587   ThreadSafepointState::create(this);
1588 
1589   debug_only(_java_call_counter = 0);
1590 
1591   // JVMTI PopFrame support
1592   _popframe_condition = popframe_inactive;
1593   _popframe_preserved_args = NULL;
1594   _popframe_preserved_args_size = 0;
1595   _frames_to_pop_failed_realloc = 0;
1596 
1597   if (SafepointMechanism::uses_thread_local_poll()) {
1598     SafepointMechanism::initialize_header(this);
1599   }
1600 
1601   pd_initialize();
1602 }
1603 
1604 JavaThread::JavaThread(bool is_attaching_via_jni) :
1605                        Thread() {
1606   initialize();
1607   if (is_attaching_via_jni) {
1608     _jni_attach_state = _attaching_via_jni;
1609   } else {
1610     _jni_attach_state = _not_attaching_via_jni;
1611   }
1612   assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1613 }
1614 
1615 bool JavaThread::reguard_stack(address cur_sp) {
1616   if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1617       && _stack_guard_state != stack_guard_reserved_disabled) {
1618     return true; // Stack already guarded or guard pages not needed.
1619   }
1620 
1621   if (register_stack_overflow()) {
1622     // For those architectures which have separate register and
1623     // memory stacks, we must check the register stack to see if
1624     // it has overflowed.
1625     return false;
1626   }
1627 
1628   // Java code never executes within the yellow zone: the latter is only
1629   // there to provoke an exception during stack banging.  If java code
1630   // is executing there, either StackShadowPages should be larger, or
1631   // some exception code in c1, c2 or the interpreter isn't unwinding
1632   // when it should.
1633   guarantee(cur_sp > stack_reserved_zone_base(),
1634             "not enough space to reguard - increase StackShadowPages");
1635   if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1636     enable_stack_yellow_reserved_zone();
1637     if (reserved_stack_activation() != stack_base()) {
1638       set_reserved_stack_activation(stack_base());
1639     }
1640   } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1641     set_reserved_stack_activation(stack_base());
1642     enable_stack_reserved_zone();
1643   }
1644   return true;
1645 }
1646 
1647 bool JavaThread::reguard_stack(void) {
1648   return reguard_stack(os::current_stack_pointer());
1649 }
1650 
1651 
1652 void JavaThread::block_if_vm_exited() {
1653   if (_terminated == _vm_exited) {
1654     // _vm_exited is set at safepoint, and Threads_lock is never released
1655     // we will block here forever
1656     Threads_lock->lock_without_safepoint_check();
1657     ShouldNotReachHere();
1658   }
1659 }
1660 
1661 
1662 // Remove this ifdef when C1 is ported to the compiler interface.
1663 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1664 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1665 
1666 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1667                        Thread() {
1668   initialize();
1669   _jni_attach_state = _not_attaching_via_jni;
1670   set_entry_point(entry_point);
1671   // Create the native thread itself.
1672   // %note runtime_23
1673   os::ThreadType thr_type = os::java_thread;
1674   thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1675                                                      os::java_thread;
1676   os::create_thread(this, thr_type, stack_sz);
1677   // The _osthread may be NULL here because we ran out of memory (too many threads active).
1678   // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1679   // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1680   // the exception consists of creating the exception object & initializing it, initialization
1681   // will leave the VM via a JavaCall and then all locks must be unlocked).
1682   //
1683   // The thread is still suspended when we reach here. Thread must be explicit started
1684   // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1685   // by calling Threads:add. The reason why this is not done here, is because the thread
1686   // object must be fully initialized (take a look at JVM_Start)
1687 }
1688 
1689 JavaThread::~JavaThread() {
1690 
1691   // JSR166 -- return the parker to the free list
1692   Parker::Release(_parker);
1693   _parker = NULL;
1694 
1695   // Free any remaining  previous UnrollBlock
1696   vframeArray* old_array = vframe_array_last();
1697 
1698   if (old_array != NULL) {
1699     Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1700     old_array->set_unroll_block(NULL);
1701     delete old_info;
1702     delete old_array;
1703   }
1704 
1705   GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1706   if (deferred != NULL) {
1707     // This can only happen if thread is destroyed before deoptimization occurs.
1708     assert(deferred->length() != 0, "empty array!");
1709     do {
1710       jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1711       deferred->remove_at(0);
1712       // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1713       delete dlv;
1714     } while (deferred->length() != 0);
1715     delete deferred;
1716   }
1717 
1718   // All Java related clean up happens in exit
1719   ThreadSafepointState::destroy(this);
1720   if (_thread_stat != NULL) delete _thread_stat;
1721 
1722 #if INCLUDE_JVMCI
1723   if (JVMCICounterSize > 0) {
1724     if (jvmci_counters_include(this)) {
1725       for (int i = 0; i < JVMCICounterSize; i++) {
1726         _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1727       }
1728     }
1729     FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1730   }
1731 #endif // INCLUDE_JVMCI
1732 }
1733 
1734 
1735 // The first routine called by a new Java thread
1736 void JavaThread::run() {
1737   // initialize thread-local alloc buffer related fields
1738   this->initialize_tlab();
1739 
1740   // used to test validity of stack trace backs
1741   this->record_base_of_stack_pointer();
1742 
1743   // Record real stack base and size.
1744   this->record_stack_base_and_size();
1745 
1746   this->create_stack_guard_pages();
1747 
1748   this->cache_global_variables();
1749 
1750   // Thread is now sufficient initialized to be handled by the safepoint code as being
1751   // in the VM. Change thread state from _thread_new to _thread_in_vm
1752   ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1753 
1754   assert(JavaThread::current() == this, "sanity check");
1755   assert(!Thread::current()->owns_locks(), "sanity check");
1756 
1757   DTRACE_THREAD_PROBE(start, this);
1758 
1759   // This operation might block. We call that after all safepoint checks for a new thread has
1760   // been completed.
1761   this->set_active_handles(JNIHandleBlock::allocate_block());
1762 
1763   if (JvmtiExport::should_post_thread_life()) {
1764     JvmtiExport::post_thread_start(this);
1765   }
1766 
1767   EventThreadStart event;
1768   if (event.should_commit()) {
1769     event.set_thread(JFR_THREAD_ID(this));
1770     event.commit();
1771   }
1772 
1773   // We call another function to do the rest so we are sure that the stack addresses used
1774   // from there will be lower than the stack base just computed
1775   thread_main_inner();
1776 
1777   // Note, thread is no longer valid at this point!
1778 }
1779 
1780 
1781 void JavaThread::thread_main_inner() {
1782   assert(JavaThread::current() == this, "sanity check");
1783   assert(this->threadObj() != NULL, "just checking");
1784 
1785   // Execute thread entry point unless this thread has a pending exception
1786   // or has been stopped before starting.
1787   // Note: Due to JVM_StopThread we can have pending exceptions already!
1788   if (!this->has_pending_exception() &&
1789       !java_lang_Thread::is_stillborn(this->threadObj())) {
1790     {
1791       ResourceMark rm(this);
1792       this->set_native_thread_name(this->get_thread_name());
1793     }
1794     HandleMark hm(this);
1795     this->entry_point()(this, this);
1796   }
1797 
1798   DTRACE_THREAD_PROBE(stop, this);
1799 
1800   this->exit(false);
1801   this->smr_delete();
1802 }
1803 
1804 
1805 static void ensure_join(JavaThread* thread) {
1806   // We do not need to grab the Threads_lock, since we are operating on ourself.
1807   Handle threadObj(thread, thread->threadObj());
1808   assert(threadObj.not_null(), "java thread object must exist");
1809   ObjectLocker lock(threadObj, thread);
1810   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1811   thread->clear_pending_exception();
1812   // Thread is exiting. So set thread_status field in  java.lang.Thread class to TERMINATED.
1813   java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1814   // Clear the native thread instance - this makes isAlive return false and allows the join()
1815   // to complete once we've done the notify_all below
1816   java_lang_Thread::set_thread(threadObj(), NULL);
1817   lock.notify_all(thread);
1818   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1819   thread->clear_pending_exception();
1820 }
1821 
1822 static bool is_daemon(oop threadObj) {
1823   return (threadObj != NULL && java_lang_Thread::is_daemon(threadObj));
1824 }
1825 
1826 // For any new cleanup additions, please check to see if they need to be applied to
1827 // cleanup_failed_attach_current_thread as well.
1828 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1829   assert(this == JavaThread::current(), "thread consistency check");
1830 
1831   elapsedTimer _timer_exit_phase1;
1832   elapsedTimer _timer_exit_phase2;
1833   elapsedTimer _timer_exit_phase3;
1834   elapsedTimer _timer_exit_phase4;
1835 
1836   if (log_is_enabled(Debug, os, thread, timer)) {
1837     _timer_exit_phase1.start();
1838   }
1839 
1840   HandleMark hm(this);
1841   Handle uncaught_exception(this, this->pending_exception());
1842   this->clear_pending_exception();
1843   Handle threadObj(this, this->threadObj());
1844   assert(threadObj.not_null(), "Java thread object should be created");
1845 
1846   // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1847   {
1848     EXCEPTION_MARK;
1849 
1850     CLEAR_PENDING_EXCEPTION;
1851   }
1852   if (!destroy_vm) {
1853     if (uncaught_exception.not_null()) {
1854       EXCEPTION_MARK;
1855       // Call method Thread.dispatchUncaughtException().
1856       Klass* thread_klass = SystemDictionary::Thread_klass();
1857       JavaValue result(T_VOID);
1858       JavaCalls::call_virtual(&result,
1859                               threadObj, thread_klass,
1860                               vmSymbols::dispatchUncaughtException_name(),
1861                               vmSymbols::throwable_void_signature(),
1862                               uncaught_exception,
1863                               THREAD);
1864       if (HAS_PENDING_EXCEPTION) {
1865         ResourceMark rm(this);
1866         jio_fprintf(defaultStream::error_stream(),
1867                     "\nException: %s thrown from the UncaughtExceptionHandler"
1868                     " in thread \"%s\"\n",
1869                     pending_exception()->klass()->external_name(),
1870                     get_thread_name());
1871         CLEAR_PENDING_EXCEPTION;
1872       }
1873     }
1874 
1875     // Called before the java thread exit since we want to read info
1876     // from java_lang_Thread object
1877     EventThreadEnd event;
1878     if (event.should_commit()) {
1879       event.set_thread(JFR_THREAD_ID(this));
1880       event.commit();
1881     }
1882 
1883     // Call after last event on thread
1884     JFR_ONLY(Jfr::on_thread_exit(this);)
1885 
1886     // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1887     // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1888     // is deprecated anyhow.
1889     if (!is_Compiler_thread()) {
1890       int count = 3;
1891       while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1892         EXCEPTION_MARK;
1893         JavaValue result(T_VOID);
1894         Klass* thread_klass = SystemDictionary::Thread_klass();
1895         JavaCalls::call_virtual(&result,
1896                                 threadObj, thread_klass,
1897                                 vmSymbols::exit_method_name(),
1898                                 vmSymbols::void_method_signature(),
1899                                 THREAD);
1900         CLEAR_PENDING_EXCEPTION;
1901       }
1902     }
1903     // notify JVMTI
1904     if (JvmtiExport::should_post_thread_life()) {
1905       JvmtiExport::post_thread_end(this);
1906     }
1907 
1908     // We have notified the agents that we are exiting, before we go on,
1909     // we must check for a pending external suspend request and honor it
1910     // in order to not surprise the thread that made the suspend request.
1911     while (true) {
1912       {
1913         MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1914         if (!is_external_suspend()) {
1915           set_terminated(_thread_exiting);
1916           break;
1917         }
1918         // Implied else:
1919         // Things get a little tricky here. We have a pending external
1920         // suspend request, but we are holding the SR_lock so we
1921         // can't just self-suspend. So we temporarily drop the lock
1922         // and then self-suspend.
1923       }
1924 
1925       ThreadBlockInVM tbivm(this);
1926       java_suspend_self();
1927 
1928       // We're done with this suspend request, but we have to loop around
1929       // and check again. Eventually we will get SR_lock without a pending
1930       // external suspend request and will be able to mark ourselves as
1931       // exiting.
1932     }
1933     // no more external suspends are allowed at this point
1934     { MutexLocker mu(Threads_lock);
1935       ThreadService::current_thread_exiting(this, is_daemon(threadObj()));
1936     }
1937   } else {
1938     assert(!is_terminated() && !is_exiting(), "must not be exiting");
1939     // before_exit() has already posted JVMTI THREAD_END events
1940   }
1941 
1942   if (log_is_enabled(Debug, os, thread, timer)) {
1943     _timer_exit_phase1.stop();
1944     _timer_exit_phase2.start();
1945   }
1946   // Notify waiters on thread object. This has to be done after exit() is called
1947   // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1948   // group should have the destroyed bit set before waiters are notified).
1949   ensure_join(this);
1950   assert(!this->has_pending_exception(), "ensure_join should have cleared");
1951 
1952   if (log_is_enabled(Debug, os, thread, timer)) {
1953     _timer_exit_phase2.stop();
1954     _timer_exit_phase3.start();
1955   }
1956   // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1957   // held by this thread must be released. The spec does not distinguish
1958   // between JNI-acquired and regular Java monitors. We can only see
1959   // regular Java monitors here if monitor enter-exit matching is broken.
1960   //
1961   // ensure_join() ignores IllegalThreadStateExceptions, and so does
1962   // ObjectSynchronizer::release_monitors_owned_by_thread().
1963   if (exit_type == jni_detach) {
1964     // Sanity check even though JNI DetachCurrentThread() would have
1965     // returned JNI_ERR if there was a Java frame. JavaThread exit
1966     // should be done executing Java code by the time we get here.
1967     assert(!this->has_last_Java_frame(),
1968            "should not have a Java frame when detaching or exiting");
1969     ObjectSynchronizer::release_monitors_owned_by_thread(this);
1970     assert(!this->has_pending_exception(), "release_monitors should have cleared");
1971   }
1972 
1973   // These things needs to be done while we are still a Java Thread. Make sure that thread
1974   // is in a consistent state, in case GC happens
1975   assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1976 
1977   if (active_handles() != NULL) {
1978     JNIHandleBlock* block = active_handles();
1979     set_active_handles(NULL);
1980     JNIHandleBlock::release_block(block);
1981   }
1982 
1983   if (free_handle_block() != NULL) {
1984     JNIHandleBlock* block = free_handle_block();
1985     set_free_handle_block(NULL);
1986     JNIHandleBlock::release_block(block);
1987   }
1988 
1989   // These have to be removed while this is still a valid thread.
1990   remove_stack_guard_pages();
1991 
1992   if (UseTLAB) {
1993     tlab().retire();
1994   }
1995 
1996   if (JvmtiEnv::environments_might_exist()) {
1997     JvmtiExport::cleanup_thread(this);
1998   }
1999 
2000   // We must flush any deferred card marks and other various GC barrier
2001   // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer)
2002   // before removing a thread from the list of active threads.
2003   BarrierSet::barrier_set()->on_thread_detach(this);
2004 
2005   log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
2006     exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
2007     os::current_thread_id());
2008 
2009   if (log_is_enabled(Debug, os, thread, timer)) {
2010     _timer_exit_phase3.stop();
2011     _timer_exit_phase4.start();
2012   }
2013   // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
2014   Threads::remove(this);
2015 
2016   if (log_is_enabled(Debug, os, thread, timer)) {
2017     _timer_exit_phase4.stop();
2018     ResourceMark rm(this);
2019     log_debug(os, thread, timer)("name='%s'"
2020                                  ", exit-phase1=" JLONG_FORMAT
2021                                  ", exit-phase2=" JLONG_FORMAT
2022                                  ", exit-phase3=" JLONG_FORMAT
2023                                  ", exit-phase4=" JLONG_FORMAT,
2024                                  get_thread_name(),
2025                                  _timer_exit_phase1.milliseconds(),
2026                                  _timer_exit_phase2.milliseconds(),
2027                                  _timer_exit_phase3.milliseconds(),
2028                                  _timer_exit_phase4.milliseconds());
2029   }
2030 }
2031 
2032 void JavaThread::cleanup_failed_attach_current_thread() {
2033   if (active_handles() != NULL) {
2034     JNIHandleBlock* block = active_handles();
2035     set_active_handles(NULL);
2036     JNIHandleBlock::release_block(block);
2037   }
2038 
2039   if (free_handle_block() != NULL) {
2040     JNIHandleBlock* block = free_handle_block();
2041     set_free_handle_block(NULL);
2042     JNIHandleBlock::release_block(block);
2043   }
2044 
2045   // These have to be removed while this is still a valid thread.
2046   remove_stack_guard_pages();
2047 
2048   if (UseTLAB) {
2049     tlab().retire();
2050   }
2051 
2052   BarrierSet::barrier_set()->on_thread_detach(this);
2053 
2054   Threads::remove(this);
2055   this->smr_delete();
2056 }
2057 
2058 JavaThread* JavaThread::active() {
2059   Thread* thread = Thread::current();
2060   if (thread->is_Java_thread()) {
2061     return (JavaThread*) thread;
2062   } else {
2063     assert(thread->is_VM_thread(), "this must be a vm thread");
2064     VM_Operation* op = ((VMThread*) thread)->vm_operation();
2065     JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2066     assert(ret->is_Java_thread(), "must be a Java thread");
2067     return ret;
2068   }
2069 }
2070 
2071 bool JavaThread::is_lock_owned(address adr) const {
2072   if (Thread::is_lock_owned(adr)) return true;
2073 
2074   for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2075     if (chunk->contains(adr)) return true;
2076   }
2077 
2078   return false;
2079 }
2080 
2081 
2082 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2083   chunk->set_next(monitor_chunks());
2084   set_monitor_chunks(chunk);
2085 }
2086 
2087 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2088   guarantee(monitor_chunks() != NULL, "must be non empty");
2089   if (monitor_chunks() == chunk) {
2090     set_monitor_chunks(chunk->next());
2091   } else {
2092     MonitorChunk* prev = monitor_chunks();
2093     while (prev->next() != chunk) prev = prev->next();
2094     prev->set_next(chunk->next());
2095   }
2096 }
2097 
2098 // JVM support.
2099 
2100 // Note: this function shouldn't block if it's called in
2101 // _thread_in_native_trans state (such as from
2102 // check_special_condition_for_native_trans()).
2103 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2104 
2105   if (has_last_Java_frame() && has_async_condition()) {
2106     // If we are at a polling page safepoint (not a poll return)
2107     // then we must defer async exception because live registers
2108     // will be clobbered by the exception path. Poll return is
2109     // ok because the call we a returning from already collides
2110     // with exception handling registers and so there is no issue.
2111     // (The exception handling path kills call result registers but
2112     //  this is ok since the exception kills the result anyway).
2113 
2114     if (is_at_poll_safepoint()) {
2115       // if the code we are returning to has deoptimized we must defer
2116       // the exception otherwise live registers get clobbered on the
2117       // exception path before deoptimization is able to retrieve them.
2118       //
2119       RegisterMap map(this, false);
2120       frame caller_fr = last_frame().sender(&map);
2121       assert(caller_fr.is_compiled_frame(), "what?");
2122       if (caller_fr.is_deoptimized_frame()) {
2123         log_info(exceptions)("deferred async exception at compiled safepoint");
2124         return;
2125       }
2126     }
2127   }
2128 
2129   JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2130   if (condition == _no_async_condition) {
2131     // Conditions have changed since has_special_runtime_exit_condition()
2132     // was called:
2133     // - if we were here only because of an external suspend request,
2134     //   then that was taken care of above (or cancelled) so we are done
2135     // - if we were here because of another async request, then it has
2136     //   been cleared between the has_special_runtime_exit_condition()
2137     //   and now so again we are done
2138     return;
2139   }
2140 
2141   // Check for pending async. exception
2142   if (_pending_async_exception != NULL) {
2143     // Only overwrite an already pending exception, if it is not a threadDeath.
2144     if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2145 
2146       // We cannot call Exceptions::_throw(...) here because we cannot block
2147       set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2148 
2149       LogTarget(Info, exceptions) lt;
2150       if (lt.is_enabled()) {
2151         ResourceMark rm;
2152         LogStream ls(lt);
2153         ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2154           if (has_last_Java_frame()) {
2155             frame f = last_frame();
2156            ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2157           }
2158         ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2159       }
2160       _pending_async_exception = NULL;
2161       clear_has_async_exception();
2162     }
2163   }
2164 
2165   if (check_unsafe_error &&
2166       condition == _async_unsafe_access_error && !has_pending_exception()) {
2167     condition = _no_async_condition;  // done
2168     switch (thread_state()) {
2169     case _thread_in_vm: {
2170       JavaThread* THREAD = this;
2171       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2172     }
2173     case _thread_in_native: {
2174       ThreadInVMfromNative tiv(this);
2175       JavaThread* THREAD = this;
2176       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2177     }
2178     case _thread_in_Java: {
2179       ThreadInVMfromJava tiv(this);
2180       JavaThread* THREAD = this;
2181       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2182     }
2183     default:
2184       ShouldNotReachHere();
2185     }
2186   }
2187 
2188   assert(condition == _no_async_condition || has_pending_exception() ||
2189          (!check_unsafe_error && condition == _async_unsafe_access_error),
2190          "must have handled the async condition, if no exception");
2191 }
2192 
2193 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2194   //
2195   // Check for pending external suspend. Internal suspend requests do
2196   // not use handle_special_runtime_exit_condition().
2197   // If JNIEnv proxies are allowed, don't self-suspend if the target
2198   // thread is not the current thread. In older versions of jdbx, jdbx
2199   // threads could call into the VM with another thread's JNIEnv so we
2200   // can be here operating on behalf of a suspended thread (4432884).
2201   bool do_self_suspend = is_external_suspend_with_lock();
2202   if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2203     //
2204     // Because thread is external suspended the safepoint code will count
2205     // thread as at a safepoint. This can be odd because we can be here
2206     // as _thread_in_Java which would normally transition to _thread_blocked
2207     // at a safepoint. We would like to mark the thread as _thread_blocked
2208     // before calling java_suspend_self like all other callers of it but
2209     // we must then observe proper safepoint protocol. (We can't leave
2210     // _thread_blocked with a safepoint in progress). However we can be
2211     // here as _thread_in_native_trans so we can't use a normal transition
2212     // constructor/destructor pair because they assert on that type of
2213     // transition. We could do something like:
2214     //
2215     // JavaThreadState state = thread_state();
2216     // set_thread_state(_thread_in_vm);
2217     // {
2218     //   ThreadBlockInVM tbivm(this);
2219     //   java_suspend_self()
2220     // }
2221     // set_thread_state(_thread_in_vm_trans);
2222     // if (safepoint) block;
2223     // set_thread_state(state);
2224     //
2225     // but that is pretty messy. Instead we just go with the way the
2226     // code has worked before and note that this is the only path to
2227     // java_suspend_self that doesn't put the thread in _thread_blocked
2228     // mode.
2229 
2230     frame_anchor()->make_walkable(this);
2231     java_suspend_self();
2232 
2233     // We might be here for reasons in addition to the self-suspend request
2234     // so check for other async requests.
2235   }
2236 
2237   if (check_asyncs) {
2238     check_and_handle_async_exceptions();
2239   }
2240 
2241   JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);)
2242 }
2243 
2244 void JavaThread::send_thread_stop(oop java_throwable)  {
2245   assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2246   assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2247   assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2248 
2249   // Do not throw asynchronous exceptions against the compiler thread
2250   // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2251   if (!can_call_java()) return;
2252 
2253   {
2254     // Actually throw the Throwable against the target Thread - however
2255     // only if there is no thread death exception installed already.
2256     if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2257       // If the topmost frame is a runtime stub, then we are calling into
2258       // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2259       // must deoptimize the caller before continuing, as the compiled  exception handler table
2260       // may not be valid
2261       if (has_last_Java_frame()) {
2262         frame f = last_frame();
2263         if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2264           // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2265           RegisterMap reg_map(this, UseBiasedLocking);
2266           frame compiled_frame = f.sender(&reg_map);
2267           if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2268             Deoptimization::deoptimize(this, compiled_frame, &reg_map);
2269           }
2270         }
2271       }
2272 
2273       // Set async. pending exception in thread.
2274       set_pending_async_exception(java_throwable);
2275 
2276       if (log_is_enabled(Info, exceptions)) {
2277          ResourceMark rm;
2278         log_info(exceptions)("Pending Async. exception installed of type: %s",
2279                              InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2280       }
2281       // for AbortVMOnException flag
2282       Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2283     }
2284   }
2285 
2286 
2287   // Interrupt thread so it will wake up from a potential wait()
2288   Thread::interrupt(this);
2289 }
2290 
2291 // External suspension mechanism.
2292 //
2293 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2294 // to any VM_locks and it is at a transition
2295 // Self-suspension will happen on the transition out of the vm.
2296 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2297 //
2298 // Guarantees on return:
2299 //   + Target thread will not execute any new bytecode (that's why we need to
2300 //     force a safepoint)
2301 //   + Target thread will not enter any new monitors
2302 //
2303 void JavaThread::java_suspend() {
2304   ThreadsListHandle tlh;
2305   if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) {
2306     return;
2307   }
2308 
2309   { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2310     if (!is_external_suspend()) {
2311       // a racing resume has cancelled us; bail out now
2312       return;
2313     }
2314 
2315     // suspend is done
2316     uint32_t debug_bits = 0;
2317     // Warning: is_ext_suspend_completed() may temporarily drop the
2318     // SR_lock to allow the thread to reach a stable thread state if
2319     // it is currently in a transient thread state.
2320     if (is_ext_suspend_completed(false /* !called_by_wait */,
2321                                  SuspendRetryDelay, &debug_bits)) {
2322       return;
2323     }
2324   }
2325 
2326   VM_ThreadSuspend vm_suspend;
2327   VMThread::execute(&vm_suspend);
2328 }
2329 
2330 // Part II of external suspension.
2331 // A JavaThread self suspends when it detects a pending external suspend
2332 // request. This is usually on transitions. It is also done in places
2333 // where continuing to the next transition would surprise the caller,
2334 // e.g., monitor entry.
2335 //
2336 // Returns the number of times that the thread self-suspended.
2337 //
2338 // Note: DO NOT call java_suspend_self() when you just want to block current
2339 //       thread. java_suspend_self() is the second stage of cooperative
2340 //       suspension for external suspend requests and should only be used
2341 //       to complete an external suspend request.
2342 //
2343 int JavaThread::java_suspend_self() {
2344   int ret = 0;
2345 
2346   // we are in the process of exiting so don't suspend
2347   if (is_exiting()) {
2348     clear_external_suspend();
2349     return ret;
2350   }
2351 
2352   assert(_anchor.walkable() ||
2353          (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2354          "must have walkable stack");
2355 
2356   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2357 
2358   assert(!this->is_ext_suspended(),
2359          "a thread trying to self-suspend should not already be suspended");
2360 
2361   if (this->is_suspend_equivalent()) {
2362     // If we are self-suspending as a result of the lifting of a
2363     // suspend equivalent condition, then the suspend_equivalent
2364     // flag is not cleared until we set the ext_suspended flag so
2365     // that wait_for_ext_suspend_completion() returns consistent
2366     // results.
2367     this->clear_suspend_equivalent();
2368   }
2369 
2370   // A racing resume may have cancelled us before we grabbed SR_lock
2371   // above. Or another external suspend request could be waiting for us
2372   // by the time we return from SR_lock()->wait(). The thread
2373   // that requested the suspension may already be trying to walk our
2374   // stack and if we return now, we can change the stack out from under
2375   // it. This would be a "bad thing (TM)" and cause the stack walker
2376   // to crash. We stay self-suspended until there are no more pending
2377   // external suspend requests.
2378   while (is_external_suspend()) {
2379     ret++;
2380     this->set_ext_suspended();
2381 
2382     // _ext_suspended flag is cleared by java_resume()
2383     while (is_ext_suspended()) {
2384       this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2385     }
2386   }
2387 
2388   return ret;
2389 }
2390 
2391 #ifdef ASSERT
2392 // Verify the JavaThread has not yet been published in the Threads::list, and
2393 // hence doesn't need protection from concurrent access at this stage.
2394 void JavaThread::verify_not_published() {
2395   // Cannot create a ThreadsListHandle here and check !tlh.includes(this)
2396   // since an unpublished JavaThread doesn't participate in the
2397   // Thread-SMR protocol for keeping a ThreadsList alive.
2398   assert(!on_thread_list(), "JavaThread shouldn't have been published yet!");
2399 }
2400 #endif
2401 
2402 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2403 // progress or when _suspend_flags is non-zero.
2404 // Current thread needs to self-suspend if there is a suspend request and/or
2405 // block if a safepoint is in progress.
2406 // Async exception ISN'T checked.
2407 // Note only the ThreadInVMfromNative transition can call this function
2408 // directly and when thread state is _thread_in_native_trans
2409 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2410   assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2411 
2412   JavaThread *curJT = JavaThread::current();
2413   bool do_self_suspend = thread->is_external_suspend();
2414 
2415   assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2416 
2417   // If JNIEnv proxies are allowed, don't self-suspend if the target
2418   // thread is not the current thread. In older versions of jdbx, jdbx
2419   // threads could call into the VM with another thread's JNIEnv so we
2420   // can be here operating on behalf of a suspended thread (4432884).
2421   if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2422     JavaThreadState state = thread->thread_state();
2423 
2424     // We mark this thread_blocked state as a suspend-equivalent so
2425     // that a caller to is_ext_suspend_completed() won't be confused.
2426     // The suspend-equivalent state is cleared by java_suspend_self().
2427     thread->set_suspend_equivalent();
2428 
2429     // If the safepoint code sees the _thread_in_native_trans state, it will
2430     // wait until the thread changes to other thread state. There is no
2431     // guarantee on how soon we can obtain the SR_lock and complete the
2432     // self-suspend request. It would be a bad idea to let safepoint wait for
2433     // too long. Temporarily change the state to _thread_blocked to
2434     // let the VM thread know that this thread is ready for GC. The problem
2435     // of changing thread state is that safepoint could happen just after
2436     // java_suspend_self() returns after being resumed, and VM thread will
2437     // see the _thread_blocked state. We must check for safepoint
2438     // after restoring the state and make sure we won't leave while a safepoint
2439     // is in progress.
2440     thread->set_thread_state(_thread_blocked);
2441     thread->java_suspend_self();
2442     thread->set_thread_state(state);
2443 
2444     InterfaceSupport::serialize_thread_state_with_handler(thread);
2445   }
2446 
2447   SafepointMechanism::block_if_requested(curJT);
2448 
2449   if (thread->is_deopt_suspend()) {
2450     thread->clear_deopt_suspend();
2451     RegisterMap map(thread, false);
2452     frame f = thread->last_frame();
2453     while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2454       f = f.sender(&map);
2455     }
2456     if (f.id() == thread->must_deopt_id()) {
2457       thread->clear_must_deopt_id();
2458       f.deoptimize(thread);
2459     } else {
2460       fatal("missed deoptimization!");
2461     }
2462   }
2463 
2464   JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(thread);)
2465 }
2466 
2467 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2468 // progress or when _suspend_flags is non-zero.
2469 // Current thread needs to self-suspend if there is a suspend request and/or
2470 // block if a safepoint is in progress.
2471 // Also check for pending async exception (not including unsafe access error).
2472 // Note only the native==>VM/Java barriers can call this function and when
2473 // thread state is _thread_in_native_trans.
2474 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2475   check_safepoint_and_suspend_for_native_trans(thread);
2476 
2477   if (thread->has_async_exception()) {
2478     // We are in _thread_in_native_trans state, don't handle unsafe
2479     // access error since that may block.
2480     thread->check_and_handle_async_exceptions(false);
2481   }
2482 }
2483 
2484 // This is a variant of the normal
2485 // check_special_condition_for_native_trans with slightly different
2486 // semantics for use by critical native wrappers.  It does all the
2487 // normal checks but also performs the transition back into
2488 // thread_in_Java state.  This is required so that critical natives
2489 // can potentially block and perform a GC if they are the last thread
2490 // exiting the GCLocker.
2491 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2492   check_special_condition_for_native_trans(thread);
2493 
2494   // Finish the transition
2495   thread->set_thread_state(_thread_in_Java);
2496 
2497   if (thread->do_critical_native_unlock()) {
2498     ThreadInVMfromJavaNoAsyncException tiv(thread);
2499     GCLocker::unlock_critical(thread);
2500     thread->clear_critical_native_unlock();
2501   }
2502 }
2503 
2504 // We need to guarantee the Threads_lock here, since resumes are not
2505 // allowed during safepoint synchronization
2506 // Can only resume from an external suspension
2507 void JavaThread::java_resume() {
2508   assert_locked_or_safepoint(Threads_lock);
2509 
2510   // Sanity check: thread is gone, has started exiting or the thread
2511   // was not externally suspended.
2512   ThreadsListHandle tlh;
2513   if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) {
2514     return;
2515   }
2516 
2517   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2518 
2519   clear_external_suspend();
2520 
2521   if (is_ext_suspended()) {
2522     clear_ext_suspended();
2523     SR_lock()->notify_all();
2524   }
2525 }
2526 
2527 size_t JavaThread::_stack_red_zone_size = 0;
2528 size_t JavaThread::_stack_yellow_zone_size = 0;
2529 size_t JavaThread::_stack_reserved_zone_size = 0;
2530 size_t JavaThread::_stack_shadow_zone_size = 0;
2531 
2532 void JavaThread::create_stack_guard_pages() {
2533   if (!os::uses_stack_guard_pages() ||
2534       _stack_guard_state != stack_guard_unused ||
2535       (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) {
2536       log_info(os, thread)("Stack guard page creation for thread "
2537                            UINTX_FORMAT " disabled", os::current_thread_id());
2538     return;
2539   }
2540   address low_addr = stack_end();
2541   size_t len = stack_guard_zone_size();
2542 
2543   assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2544   assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2545 
2546   int must_commit = os::must_commit_stack_guard_pages();
2547   // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2548 
2549   if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2550     log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2551     return;
2552   }
2553 
2554   if (os::guard_memory((char *) low_addr, len)) {
2555     _stack_guard_state = stack_guard_enabled;
2556   } else {
2557     log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2558       PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2559     if (os::uncommit_memory((char *) low_addr, len)) {
2560       log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2561     }
2562     return;
2563   }
2564 
2565   log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2566     PTR_FORMAT "-" PTR_FORMAT ".",
2567     os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2568 }
2569 
2570 void JavaThread::remove_stack_guard_pages() {
2571   assert(Thread::current() == this, "from different thread");
2572   if (_stack_guard_state == stack_guard_unused) return;
2573   address low_addr = stack_end();
2574   size_t len = stack_guard_zone_size();
2575 
2576   if (os::must_commit_stack_guard_pages()) {
2577     if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2578       _stack_guard_state = stack_guard_unused;
2579     } else {
2580       log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2581         PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2582       return;
2583     }
2584   } else {
2585     if (_stack_guard_state == stack_guard_unused) return;
2586     if (os::unguard_memory((char *) low_addr, len)) {
2587       _stack_guard_state = stack_guard_unused;
2588     } else {
2589       log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2590         PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2591       return;
2592     }
2593   }
2594 
2595   log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2596     PTR_FORMAT "-" PTR_FORMAT ".",
2597     os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2598 }
2599 
2600 void JavaThread::enable_stack_reserved_zone() {
2601   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2602   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2603 
2604   // The base notation is from the stack's point of view, growing downward.
2605   // We need to adjust it to work correctly with guard_memory()
2606   address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2607 
2608   guarantee(base < stack_base(),"Error calculating stack reserved zone");
2609   guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2610 
2611   if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2612     _stack_guard_state = stack_guard_enabled;
2613   } else {
2614     warning("Attempt to guard stack reserved zone failed.");
2615   }
2616   enable_register_stack_guard();
2617 }
2618 
2619 void JavaThread::disable_stack_reserved_zone() {
2620   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2621   assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2622 
2623   // Simply return if called for a thread that does not use guard pages.
2624   if (_stack_guard_state == stack_guard_unused) return;
2625 
2626   // The base notation is from the stack's point of view, growing downward.
2627   // We need to adjust it to work correctly with guard_memory()
2628   address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2629 
2630   if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2631     _stack_guard_state = stack_guard_reserved_disabled;
2632   } else {
2633     warning("Attempt to unguard stack reserved zone failed.");
2634   }
2635   disable_register_stack_guard();
2636 }
2637 
2638 void JavaThread::enable_stack_yellow_reserved_zone() {
2639   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2640   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2641 
2642   // The base notation is from the stacks point of view, growing downward.
2643   // We need to adjust it to work correctly with guard_memory()
2644   address base = stack_red_zone_base();
2645 
2646   guarantee(base < stack_base(), "Error calculating stack yellow zone");
2647   guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2648 
2649   if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2650     _stack_guard_state = stack_guard_enabled;
2651   } else {
2652     warning("Attempt to guard stack yellow zone failed.");
2653   }
2654   enable_register_stack_guard();
2655 }
2656 
2657 void JavaThread::disable_stack_yellow_reserved_zone() {
2658   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2659   assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2660 
2661   // Simply return if called for a thread that does not use guard pages.
2662   if (_stack_guard_state == stack_guard_unused) return;
2663 
2664   // The base notation is from the stacks point of view, growing downward.
2665   // We need to adjust it to work correctly with guard_memory()
2666   address base = stack_red_zone_base();
2667 
2668   if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2669     _stack_guard_state = stack_guard_yellow_reserved_disabled;
2670   } else {
2671     warning("Attempt to unguard stack yellow zone failed.");
2672   }
2673   disable_register_stack_guard();
2674 }
2675 
2676 void JavaThread::enable_stack_red_zone() {
2677   // The base notation is from the stacks point of view, growing downward.
2678   // We need to adjust it to work correctly with guard_memory()
2679   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2680   address base = stack_red_zone_base() - stack_red_zone_size();
2681 
2682   guarantee(base < stack_base(), "Error calculating stack red zone");
2683   guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2684 
2685   if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2686     warning("Attempt to guard stack red zone failed.");
2687   }
2688 }
2689 
2690 void JavaThread::disable_stack_red_zone() {
2691   // The base notation is from the stacks point of view, growing downward.
2692   // We need to adjust it to work correctly with guard_memory()
2693   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2694   address base = stack_red_zone_base() - stack_red_zone_size();
2695   if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2696     warning("Attempt to unguard stack red zone failed.");
2697   }
2698 }
2699 
2700 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2701   // ignore is there is no stack
2702   if (!has_last_Java_frame()) return;
2703   // traverse the stack frames. Starts from top frame.
2704   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2705     frame* fr = fst.current();
2706     f(fr, fst.register_map());
2707   }
2708 }
2709 
2710 
2711 #ifndef PRODUCT
2712 // Deoptimization
2713 // Function for testing deoptimization
2714 void JavaThread::deoptimize() {
2715   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2716   StackFrameStream fst(this, UseBiasedLocking);
2717   bool deopt = false;           // Dump stack only if a deopt actually happens.
2718   bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2719   // Iterate over all frames in the thread and deoptimize
2720   for (; !fst.is_done(); fst.next()) {
2721     if (fst.current()->can_be_deoptimized()) {
2722 
2723       if (only_at) {
2724         // Deoptimize only at particular bcis.  DeoptimizeOnlyAt
2725         // consists of comma or carriage return separated numbers so
2726         // search for the current bci in that string.
2727         address pc = fst.current()->pc();
2728         nmethod* nm =  (nmethod*) fst.current()->cb();
2729         ScopeDesc* sd = nm->scope_desc_at(pc);
2730         char buffer[8];
2731         jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2732         size_t len = strlen(buffer);
2733         const char * found = strstr(DeoptimizeOnlyAt, buffer);
2734         while (found != NULL) {
2735           if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2736               (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2737             // Check that the bci found is bracketed by terminators.
2738             break;
2739           }
2740           found = strstr(found + 1, buffer);
2741         }
2742         if (!found) {
2743           continue;
2744         }
2745       }
2746 
2747       if (DebugDeoptimization && !deopt) {
2748         deopt = true; // One-time only print before deopt
2749         tty->print_cr("[BEFORE Deoptimization]");
2750         trace_frames();
2751         trace_stack();
2752       }
2753       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2754     }
2755   }
2756 
2757   if (DebugDeoptimization && deopt) {
2758     tty->print_cr("[AFTER Deoptimization]");
2759     trace_frames();
2760   }
2761 }
2762 
2763 
2764 // Make zombies
2765 void JavaThread::make_zombies() {
2766   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2767     if (fst.current()->can_be_deoptimized()) {
2768       // it is a Java nmethod
2769       nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2770       nm->make_not_entrant();
2771     }
2772   }
2773 }
2774 #endif // PRODUCT
2775 
2776 
2777 void JavaThread::deoptimized_wrt_marked_nmethods() {
2778   if (!has_last_Java_frame()) return;
2779   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2780   StackFrameStream fst(this, UseBiasedLocking);
2781   for (; !fst.is_done(); fst.next()) {
2782     if (fst.current()->should_be_deoptimized()) {
2783       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2784     }
2785   }
2786 }
2787 
2788 
2789 // If the caller is a NamedThread, then remember, in the current scope,
2790 // the given JavaThread in its _processed_thread field.
2791 class RememberProcessedThread: public StackObj {
2792   NamedThread* _cur_thr;
2793  public:
2794   RememberProcessedThread(JavaThread* jthr) {
2795     Thread* thread = Thread::current();
2796     if (thread->is_Named_thread()) {
2797       _cur_thr = (NamedThread *)thread;
2798       _cur_thr->set_processed_thread(jthr);
2799     } else {
2800       _cur_thr = NULL;
2801     }
2802   }
2803 
2804   ~RememberProcessedThread() {
2805     if (_cur_thr) {
2806       _cur_thr->set_processed_thread(NULL);
2807     }
2808   }
2809 };
2810 
2811 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2812   // Verify that the deferred card marks have been flushed.
2813   assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2814 
2815   // Traverse the GCHandles
2816   Thread::oops_do(f, cf);
2817 
2818   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2819          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2820 
2821   if (has_last_Java_frame()) {
2822     // Record JavaThread to GC thread
2823     RememberProcessedThread rpt(this);
2824 
2825     // Traverse the privileged stack
2826     if (_privileged_stack_top != NULL) {
2827       _privileged_stack_top->oops_do(f);
2828     }
2829 
2830     // traverse the registered growable array
2831     if (_array_for_gc != NULL) {
2832       for (int index = 0; index < _array_for_gc->length(); index++) {
2833         f->do_oop(_array_for_gc->adr_at(index));
2834       }
2835     }
2836 
2837     // Traverse the monitor chunks
2838     for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2839       chunk->oops_do(f);
2840     }
2841 
2842     // Traverse the execution stack
2843     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2844       fst.current()->oops_do(f, cf, fst.register_map());
2845     }
2846   }
2847 
2848   // callee_target is never live across a gc point so NULL it here should
2849   // it still contain a methdOop.
2850 
2851   set_callee_target(NULL);
2852 
2853   assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2854   // If we have deferred set_locals there might be oops waiting to be
2855   // written
2856   GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2857   if (list != NULL) {
2858     for (int i = 0; i < list->length(); i++) {
2859       list->at(i)->oops_do(f);
2860     }
2861   }
2862 
2863   // Traverse instance variables at the end since the GC may be moving things
2864   // around using this function
2865   f->do_oop((oop*) &_threadObj);
2866   f->do_oop((oop*) &_vm_result);
2867   f->do_oop((oop*) &_exception_oop);
2868   f->do_oop((oop*) &_pending_async_exception);
2869 
2870   if (jvmti_thread_state() != NULL) {
2871     jvmti_thread_state()->oops_do(f);
2872   }
2873 }
2874 
2875 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2876   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2877          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2878 
2879   if (has_last_Java_frame()) {
2880     // Traverse the execution stack
2881     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2882       fst.current()->nmethods_do(cf);
2883     }
2884   }
2885 }
2886 
2887 void JavaThread::metadata_do(void f(Metadata*)) {
2888   if (has_last_Java_frame()) {
2889     // Traverse the execution stack to call f() on the methods in the stack
2890     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2891       fst.current()->metadata_do(f);
2892     }
2893   } else if (is_Compiler_thread()) {
2894     // need to walk ciMetadata in current compile tasks to keep alive.
2895     CompilerThread* ct = (CompilerThread*)this;
2896     if (ct->env() != NULL) {
2897       ct->env()->metadata_do(f);
2898     }
2899     CompileTask* task = ct->task();
2900     if (task != NULL) {
2901       task->metadata_do(f);
2902     }
2903   }
2904 }
2905 
2906 // Printing
2907 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2908   switch (_thread_state) {
2909   case _thread_uninitialized:     return "_thread_uninitialized";
2910   case _thread_new:               return "_thread_new";
2911   case _thread_new_trans:         return "_thread_new_trans";
2912   case _thread_in_native:         return "_thread_in_native";
2913   case _thread_in_native_trans:   return "_thread_in_native_trans";
2914   case _thread_in_vm:             return "_thread_in_vm";
2915   case _thread_in_vm_trans:       return "_thread_in_vm_trans";
2916   case _thread_in_Java:           return "_thread_in_Java";
2917   case _thread_in_Java_trans:     return "_thread_in_Java_trans";
2918   case _thread_blocked:           return "_thread_blocked";
2919   case _thread_blocked_trans:     return "_thread_blocked_trans";
2920   default:                        return "unknown thread state";
2921   }
2922 }
2923 
2924 #ifndef PRODUCT
2925 void JavaThread::print_thread_state_on(outputStream *st) const {
2926   st->print_cr("   JavaThread state: %s", _get_thread_state_name(_thread_state));
2927 };
2928 void JavaThread::print_thread_state() const {
2929   print_thread_state_on(tty);
2930 }
2931 #endif // PRODUCT
2932 
2933 // Called by Threads::print() for VM_PrintThreads operation
2934 void JavaThread::print_on(outputStream *st, bool print_extended_info) const {
2935   st->print_raw("\"");
2936   st->print_raw(get_thread_name());
2937   st->print_raw("\" ");
2938   oop thread_oop = threadObj();
2939   if (thread_oop != NULL) {
2940     st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
2941     if (java_lang_Thread::is_daemon(thread_oop))  st->print("daemon ");
2942     st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2943   }
2944   Thread::print_on(st, print_extended_info);
2945   // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2946   st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2947   if (thread_oop != NULL) {
2948     st->print_cr("   java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2949   }
2950 #ifndef PRODUCT
2951   print_thread_state_on(st);
2952   _safepoint_state->print_on(st);
2953 #endif // PRODUCT
2954   if (is_Compiler_thread()) {
2955     CompileTask *task = ((CompilerThread*)this)->task();
2956     if (task != NULL) {
2957       st->print("   Compiling: ");
2958       task->print(st, NULL, true, false);
2959     } else {
2960       st->print("   No compile task");
2961     }
2962     st->cr();
2963   }
2964 }
2965 
2966 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2967   st->print("%s", get_thread_name_string(buf, buflen));
2968 }
2969 
2970 // Called by fatal error handler. The difference between this and
2971 // JavaThread::print() is that we can't grab lock or allocate memory.
2972 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2973   st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2974   oop thread_obj = threadObj();
2975   if (thread_obj != NULL) {
2976     if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2977   }
2978   st->print(" [");
2979   st->print("%s", _get_thread_state_name(_thread_state));
2980   if (osthread()) {
2981     st->print(", id=%d", osthread()->thread_id());
2982   }
2983   st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2984             p2i(stack_end()), p2i(stack_base()));
2985   st->print("]");
2986 
2987   ThreadsSMRSupport::print_info_on(this, st);
2988   return;
2989 }
2990 
2991 // Verification
2992 
2993 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2994 
2995 void JavaThread::verify() {
2996   // Verify oops in the thread.
2997   oops_do(&VerifyOopClosure::verify_oop, NULL);
2998 
2999   // Verify the stack frames.
3000   frames_do(frame_verify);
3001 }
3002 
3003 // CR 6300358 (sub-CR 2137150)
3004 // Most callers of this method assume that it can't return NULL but a
3005 // thread may not have a name whilst it is in the process of attaching to
3006 // the VM - see CR 6412693, and there are places where a JavaThread can be
3007 // seen prior to having it's threadObj set (eg JNI attaching threads and
3008 // if vm exit occurs during initialization). These cases can all be accounted
3009 // for such that this method never returns NULL.
3010 const char* JavaThread::get_thread_name() const {
3011 #ifdef ASSERT
3012   // early safepoints can hit while current thread does not yet have TLS
3013   if (!SafepointSynchronize::is_at_safepoint()) {
3014     Thread *cur = Thread::current();
3015     if (!(cur->is_Java_thread() && cur == this)) {
3016       // Current JavaThreads are allowed to get their own name without
3017       // the Threads_lock.
3018       assert_locked_or_safepoint(Threads_lock);
3019     }
3020   }
3021 #endif // ASSERT
3022   return get_thread_name_string();
3023 }
3024 
3025 // Returns a non-NULL representation of this thread's name, or a suitable
3026 // descriptive string if there is no set name
3027 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3028   const char* name_str;
3029   oop thread_obj = threadObj();
3030   if (thread_obj != NULL) {
3031     oop name = java_lang_Thread::name(thread_obj);
3032     if (name != NULL) {
3033       if (buf == NULL) {
3034         name_str = java_lang_String::as_utf8_string(name);
3035       } else {
3036         name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3037       }
3038     } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3039       name_str = "<no-name - thread is attaching>";
3040     } else {
3041       name_str = Thread::name();
3042     }
3043   } else {
3044     name_str = Thread::name();
3045   }
3046   assert(name_str != NULL, "unexpected NULL thread name");
3047   return name_str;
3048 }
3049 
3050 
3051 const char* JavaThread::get_threadgroup_name() const {
3052   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3053   oop thread_obj = threadObj();
3054   if (thread_obj != NULL) {
3055     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3056     if (thread_group != NULL) {
3057       // ThreadGroup.name can be null
3058       return java_lang_ThreadGroup::name(thread_group);
3059     }
3060   }
3061   return NULL;
3062 }
3063 
3064 const char* JavaThread::get_parent_name() const {
3065   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3066   oop thread_obj = threadObj();
3067   if (thread_obj != NULL) {
3068     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3069     if (thread_group != NULL) {
3070       oop parent = java_lang_ThreadGroup::parent(thread_group);
3071       if (parent != NULL) {
3072         // ThreadGroup.name can be null
3073         return java_lang_ThreadGroup::name(parent);
3074       }
3075     }
3076   }
3077   return NULL;
3078 }
3079 
3080 ThreadPriority JavaThread::java_priority() const {
3081   oop thr_oop = threadObj();
3082   if (thr_oop == NULL) return NormPriority; // Bootstrapping
3083   ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3084   assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3085   return priority;
3086 }
3087 
3088 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3089 
3090   assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3091   // Link Java Thread object <-> C++ Thread
3092 
3093   // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3094   // and put it into a new Handle.  The Handle "thread_oop" can then
3095   // be used to pass the C++ thread object to other methods.
3096 
3097   // Set the Java level thread object (jthread) field of the
3098   // new thread (a JavaThread *) to C++ thread object using the
3099   // "thread_oop" handle.
3100 
3101   // Set the thread field (a JavaThread *) of the
3102   // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3103 
3104   Handle thread_oop(Thread::current(),
3105                     JNIHandles::resolve_non_null(jni_thread));
3106   assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3107          "must be initialized");
3108   set_threadObj(thread_oop());
3109   java_lang_Thread::set_thread(thread_oop(), this);
3110 
3111   if (prio == NoPriority) {
3112     prio = java_lang_Thread::priority(thread_oop());
3113     assert(prio != NoPriority, "A valid priority should be present");
3114   }
3115 
3116   // Push the Java priority down to the native thread; needs Threads_lock
3117   Thread::set_priority(this, prio);
3118 
3119   // Add the new thread to the Threads list and set it in motion.
3120   // We must have threads lock in order to call Threads::add.
3121   // It is crucial that we do not block before the thread is
3122   // added to the Threads list for if a GC happens, then the java_thread oop
3123   // will not be visited by GC.
3124   Threads::add(this);
3125 }
3126 
3127 oop JavaThread::current_park_blocker() {
3128   // Support for JSR-166 locks
3129   oop thread_oop = threadObj();
3130   if (thread_oop != NULL &&
3131       JDK_Version::current().supports_thread_park_blocker()) {
3132     return java_lang_Thread::park_blocker(thread_oop);
3133   }
3134   return NULL;
3135 }
3136 
3137 
3138 void JavaThread::print_stack_on(outputStream* st) {
3139   if (!has_last_Java_frame()) return;
3140   ResourceMark rm;
3141   HandleMark   hm;
3142 
3143   RegisterMap reg_map(this);
3144   vframe* start_vf = last_java_vframe(&reg_map);
3145   int count = 0;
3146   for (vframe* f = start_vf; f != NULL; f = f->sender()) {
3147     if (f->is_java_frame()) {
3148       javaVFrame* jvf = javaVFrame::cast(f);
3149       java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3150 
3151       // Print out lock information
3152       if (JavaMonitorsInStackTrace) {
3153         jvf->print_lock_info_on(st, count);
3154       }
3155     } else {
3156       // Ignore non-Java frames
3157     }
3158 
3159     // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
3160     count++;
3161     if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
3162   }
3163 }
3164 
3165 
3166 // JVMTI PopFrame support
3167 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3168   assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3169   if (in_bytes(size_in_bytes) != 0) {
3170     _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3171     _popframe_preserved_args_size = in_bytes(size_in_bytes);
3172     Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3173   }
3174 }
3175 
3176 void* JavaThread::popframe_preserved_args() {
3177   return _popframe_preserved_args;
3178 }
3179 
3180 ByteSize JavaThread::popframe_preserved_args_size() {
3181   return in_ByteSize(_popframe_preserved_args_size);
3182 }
3183 
3184 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3185   int sz = in_bytes(popframe_preserved_args_size());
3186   assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3187   return in_WordSize(sz / wordSize);
3188 }
3189 
3190 void JavaThread::popframe_free_preserved_args() {
3191   assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3192   FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3193   _popframe_preserved_args = NULL;
3194   _popframe_preserved_args_size = 0;
3195 }
3196 
3197 #ifndef PRODUCT
3198 
3199 void JavaThread::trace_frames() {
3200   tty->print_cr("[Describe stack]");
3201   int frame_no = 1;
3202   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3203     tty->print("  %d. ", frame_no++);
3204     fst.current()->print_value_on(tty, this);
3205     tty->cr();
3206   }
3207 }
3208 
3209 class PrintAndVerifyOopClosure: public OopClosure {
3210  protected:
3211   template <class T> inline void do_oop_work(T* p) {
3212     oop obj = RawAccess<>::oop_load(p);
3213     if (obj == NULL) return;
3214     tty->print(INTPTR_FORMAT ": ", p2i(p));
3215     if (oopDesc::is_oop_or_null(obj)) {
3216       if (obj->is_objArray()) {
3217         tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3218       } else {
3219         obj->print();
3220       }
3221     } else {
3222       tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3223     }
3224     tty->cr();
3225   }
3226  public:
3227   virtual void do_oop(oop* p) { do_oop_work(p); }
3228   virtual void do_oop(narrowOop* p)  { do_oop_work(p); }
3229 };
3230 
3231 
3232 static void oops_print(frame* f, const RegisterMap *map) {
3233   PrintAndVerifyOopClosure print;
3234   f->print_value();
3235   f->oops_do(&print, NULL, (RegisterMap*)map);
3236 }
3237 
3238 // Print our all the locations that contain oops and whether they are
3239 // valid or not.  This useful when trying to find the oldest frame
3240 // where an oop has gone bad since the frame walk is from youngest to
3241 // oldest.
3242 void JavaThread::trace_oops() {
3243   tty->print_cr("[Trace oops]");
3244   frames_do(oops_print);
3245 }
3246 
3247 
3248 #ifdef ASSERT
3249 // Print or validate the layout of stack frames
3250 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3251   ResourceMark rm;
3252   PRESERVE_EXCEPTION_MARK;
3253   FrameValues values;
3254   int frame_no = 0;
3255   for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3256     fst.current()->describe(values, ++frame_no);
3257     if (depth == frame_no) break;
3258   }
3259   if (validate_only) {
3260     values.validate();
3261   } else {
3262     tty->print_cr("[Describe stack layout]");
3263     values.print(this);
3264   }
3265 }
3266 #endif
3267 
3268 void JavaThread::trace_stack_from(vframe* start_vf) {
3269   ResourceMark rm;
3270   int vframe_no = 1;
3271   for (vframe* f = start_vf; f; f = f->sender()) {
3272     if (f->is_java_frame()) {
3273       javaVFrame::cast(f)->print_activation(vframe_no++);
3274     } else {
3275       f->print();
3276     }
3277     if (vframe_no > StackPrintLimit) {
3278       tty->print_cr("...<more frames>...");
3279       return;
3280     }
3281   }
3282 }
3283 
3284 
3285 void JavaThread::trace_stack() {
3286   if (!has_last_Java_frame()) return;
3287   ResourceMark rm;
3288   HandleMark   hm;
3289   RegisterMap reg_map(this);
3290   trace_stack_from(last_java_vframe(&reg_map));
3291 }
3292 
3293 
3294 #endif // PRODUCT
3295 
3296 
3297 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3298   assert(reg_map != NULL, "a map must be given");
3299   frame f = last_frame();
3300   for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3301     if (vf->is_java_frame()) return javaVFrame::cast(vf);
3302   }
3303   return NULL;
3304 }
3305 
3306 
3307 Klass* JavaThread::security_get_caller_class(int depth) {
3308   vframeStream vfst(this);
3309   vfst.security_get_caller_frame(depth);
3310   if (!vfst.at_end()) {
3311     return vfst.method()->method_holder();
3312   }
3313   return NULL;
3314 }
3315 
3316 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3317   assert(thread->is_Compiler_thread(), "must be compiler thread");
3318   CompileBroker::compiler_thread_loop();
3319 }
3320 
3321 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3322   NMethodSweeper::sweeper_loop();
3323 }
3324 
3325 // Create a CompilerThread
3326 CompilerThread::CompilerThread(CompileQueue* queue,
3327                                CompilerCounters* counters)
3328                                : JavaThread(&compiler_thread_entry) {
3329   _env   = NULL;
3330   _log   = NULL;
3331   _task  = NULL;
3332   _queue = queue;
3333   _counters = counters;
3334   _buffer_blob = NULL;
3335   _compiler = NULL;
3336 
3337   // Compiler uses resource area for compilation, let's bias it to mtCompiler
3338   resource_area()->bias_to(mtCompiler);
3339 
3340 #ifndef PRODUCT
3341   _ideal_graph_printer = NULL;
3342 #endif
3343 }
3344 
3345 CompilerThread::~CompilerThread() {
3346   // Delete objects which were allocated on heap.
3347   delete _counters;
3348 }
3349 
3350 bool CompilerThread::can_call_java() const {
3351   return _compiler != NULL && _compiler->is_jvmci();
3352 }
3353 
3354 // Create sweeper thread
3355 CodeCacheSweeperThread::CodeCacheSweeperThread()
3356 : JavaThread(&sweeper_thread_entry) {
3357   _scanned_compiled_method = NULL;
3358 }
3359 
3360 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3361   JavaThread::oops_do(f, cf);
3362   if (_scanned_compiled_method != NULL && cf != NULL) {
3363     // Safepoints can occur when the sweeper is scanning an nmethod so
3364     // process it here to make sure it isn't unloaded in the middle of
3365     // a scan.
3366     cf->do_code_blob(_scanned_compiled_method);
3367   }
3368 }
3369 
3370 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3371   JavaThread::nmethods_do(cf);
3372   if (_scanned_compiled_method != NULL && cf != NULL) {
3373     // Safepoints can occur when the sweeper is scanning an nmethod so
3374     // process it here to make sure it isn't unloaded in the middle of
3375     // a scan.
3376     cf->do_code_blob(_scanned_compiled_method);
3377   }
3378 }
3379 
3380 
3381 // ======= Threads ========
3382 
3383 // The Threads class links together all active threads, and provides
3384 // operations over all threads. It is protected by the Threads_lock,
3385 // which is also used in other global contexts like safepointing.
3386 // ThreadsListHandles are used to safely perform operations on one
3387 // or more threads without the risk of the thread exiting during the
3388 // operation.
3389 //
3390 // Note: The Threads_lock is currently more widely used than we
3391 // would like. We are actively migrating Threads_lock uses to other
3392 // mechanisms in order to reduce Threads_lock contention.
3393 
3394 JavaThread* Threads::_thread_list = NULL;
3395 int         Threads::_number_of_threads = 0;
3396 int         Threads::_number_of_non_daemon_threads = 0;
3397 int         Threads::_return_code = 0;
3398 int         Threads::_thread_claim_parity = 0;
3399 size_t      JavaThread::_stack_size_at_create = 0;
3400 
3401 #ifdef ASSERT
3402 bool        Threads::_vm_complete = false;
3403 size_t      Threads::_threads_before_barrier_set = 0;
3404 #endif
3405 
3406 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
3407   Prefetch::read((void*)addr, prefetch_interval);
3408   return *addr;
3409 }
3410 
3411 // Possibly the ugliest for loop the world has seen. C++ does not allow
3412 // multiple types in the declaration section of the for loop. In this case
3413 // we are only dealing with pointers and hence can cast them. It looks ugly
3414 // but macros are ugly and therefore it's fine to make things absurdly ugly.
3415 #define DO_JAVA_THREADS(LIST, X)                                                                                          \
3416     for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes,                           \
3417              *MACRO_list = (JavaThread*)(LIST),                                                                           \
3418              **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(),  \
3419              **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(),                                     \
3420              *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval);                 \
3421          MACRO_current_p != MACRO_end;                                                                                    \
3422          MACRO_current_p++,                                                                                               \
3423              X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval))
3424 
3425 // All JavaThreads
3426 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X)
3427 
3428 // All NonJavaThreads (i.e., every non-JavaThread in the system).
3429 void Threads::non_java_threads_do(ThreadClosure* tc) {
3430   NoSafepointVerifier nsv(!SafepointSynchronize::is_at_safepoint(), false);
3431   for (NonJavaThread::Iterator njti; !njti.end(); njti.step()) {
3432     tc->do_thread(njti.current());
3433   }
3434 }
3435 
3436 // All JavaThreads
3437 void Threads::java_threads_do(ThreadClosure* tc) {
3438   assert_locked_or_safepoint(Threads_lock);
3439   // ALL_JAVA_THREADS iterates through all JavaThreads.
3440   ALL_JAVA_THREADS(p) {
3441     tc->do_thread(p);
3442   }
3443 }
3444 
3445 void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) {
3446   assert_locked_or_safepoint(Threads_lock);
3447   java_threads_do(tc);
3448   tc->do_thread(VMThread::vm_thread());
3449 }
3450 
3451 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system).
3452 void Threads::threads_do(ThreadClosure* tc) {
3453   assert_locked_or_safepoint(Threads_lock);
3454   java_threads_do(tc);
3455   non_java_threads_do(tc);
3456 }
3457 
3458 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
3459   int cp = Threads::thread_claim_parity();
3460   ALL_JAVA_THREADS(p) {
3461     if (p->claim_oops_do(is_par, cp)) {
3462       tc->do_thread(p);
3463     }
3464   }
3465   VMThread* vmt = VMThread::vm_thread();
3466   if (vmt->claim_oops_do(is_par, cp)) {
3467     tc->do_thread(vmt);
3468   }
3469 }
3470 
3471 // The system initialization in the library has three phases.
3472 //
3473 // Phase 1: java.lang.System class initialization
3474 //     java.lang.System is a primordial class loaded and initialized
3475 //     by the VM early during startup.  java.lang.System.<clinit>
3476 //     only does registerNatives and keeps the rest of the class
3477 //     initialization work later until thread initialization completes.
3478 //
3479 //     System.initPhase1 initializes the system properties, the static
3480 //     fields in, out, and err. Set up java signal handlers, OS-specific
3481 //     system settings, and thread group of the main thread.
3482 static void call_initPhase1(TRAPS) {
3483   Klass* klass =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3484   JavaValue result(T_VOID);
3485   JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3486                                          vmSymbols::void_method_signature(), CHECK);
3487 }
3488 
3489 // Phase 2. Module system initialization
3490 //     This will initialize the module system.  Only java.base classes
3491 //     can be loaded until phase 2 completes.
3492 //
3493 //     Call System.initPhase2 after the compiler initialization and jsr292
3494 //     classes get initialized because module initialization runs a lot of java
3495 //     code, that for performance reasons, should be compiled.  Also, this will
3496 //     enable the startup code to use lambda and other language features in this
3497 //     phase and onward.
3498 //
3499 //     After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3500 static void call_initPhase2(TRAPS) {
3501   TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3502 
3503   Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3504 
3505   JavaValue result(T_INT);
3506   JavaCallArguments args;
3507   args.push_int(DisplayVMOutputToStderr);
3508   args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3509   JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3510                                          vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3511   if (result.get_jint() != JNI_OK) {
3512     vm_exit_during_initialization(); // no message or exception
3513   }
3514 
3515   universe_post_module_init();
3516 }
3517 
3518 // Phase 3. final setup - set security manager, system class loader and TCCL
3519 //
3520 //     This will instantiate and set the security manager, set the system class
3521 //     loader as well as the thread context class loader.  The security manager
3522 //     and system class loader may be a custom class loaded from -Xbootclasspath/a,
3523 //     other modules or the application's classpath.
3524 static void call_initPhase3(TRAPS) {
3525   Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3526   JavaValue result(T_VOID);
3527   JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3528                                          vmSymbols::void_method_signature(), CHECK);
3529 }
3530 
3531 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3532   TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3533 
3534   if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3535     create_vm_init_libraries();
3536   }
3537 
3538   initialize_class(vmSymbols::java_lang_String(), CHECK);
3539 
3540   // Inject CompactStrings value after the static initializers for String ran.
3541   java_lang_String::set_compact_strings(CompactStrings);
3542 
3543   // Initialize java_lang.System (needed before creating the thread)
3544   initialize_class(vmSymbols::java_lang_System(), CHECK);
3545   // The VM creates & returns objects of this class. Make sure it's initialized.
3546   initialize_class(vmSymbols::java_lang_Class(), CHECK);
3547   initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3548   Handle thread_group = create_initial_thread_group(CHECK);
3549   Universe::set_main_thread_group(thread_group());
3550   initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3551   oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3552   main_thread->set_threadObj(thread_object);
3553   // Set thread status to running since main thread has
3554   // been started and running.
3555   java_lang_Thread::set_thread_status(thread_object,
3556                                       java_lang_Thread::RUNNABLE);
3557 
3558   // The VM creates objects of this class.
3559   initialize_class(vmSymbols::java_lang_Module(), CHECK);
3560 
3561   // The VM preresolves methods to these classes. Make sure that they get initialized
3562   initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3563   initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3564 
3565   // Phase 1 of the system initialization in the library, java.lang.System class initialization
3566   call_initPhase1(CHECK);
3567 
3568   // get the Java runtime name after java.lang.System is initialized
3569   JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3570   JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3571 
3572   // an instance of OutOfMemory exception has been allocated earlier
3573   initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3574   initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3575   initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3576   initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3577   initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3578   initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3579   initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3580   initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3581 }
3582 
3583 void Threads::initialize_jsr292_core_classes(TRAPS) {
3584   TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3585 
3586   initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3587   initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3588   initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3589   initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3590 }
3591 
3592 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3593   extern void JDK_Version_init();
3594 
3595   // Preinitialize version info.
3596   VM_Version::early_initialize();
3597 
3598   // Check version
3599   if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3600 
3601   // Initialize library-based TLS
3602   ThreadLocalStorage::init();
3603 
3604   // Initialize the output stream module
3605   ostream_init();
3606 
3607   // Process java launcher properties.
3608   Arguments::process_sun_java_launcher_properties(args);
3609 
3610   // Initialize the os module
3611   os::init();
3612 
3613   // Record VM creation timing statistics
3614   TraceVmCreationTime create_vm_timer;
3615   create_vm_timer.start();
3616 
3617   // Initialize system properties.
3618   Arguments::init_system_properties();
3619 
3620   // So that JDK version can be used as a discriminator when parsing arguments
3621   JDK_Version_init();
3622 
3623   // Update/Initialize System properties after JDK version number is known
3624   Arguments::init_version_specific_system_properties();
3625 
3626   // Make sure to initialize log configuration *before* parsing arguments
3627   LogConfiguration::initialize(create_vm_timer.begin_time());
3628 
3629   // Parse arguments
3630   // Note: this internally calls os::init_container_support()
3631   jint parse_result = Arguments::parse(args);
3632   if (parse_result != JNI_OK) return parse_result;
3633 
3634   os::init_before_ergo();
3635 
3636   jint ergo_result = Arguments::apply_ergo();
3637   if (ergo_result != JNI_OK) return ergo_result;
3638 
3639   // Final check of all ranges after ergonomics which may change values.
3640   if (!JVMFlagRangeList::check_ranges()) {
3641     return JNI_EINVAL;
3642   }
3643 
3644   // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3645   bool constraint_result = JVMFlagConstraintList::check_constraints(JVMFlagConstraint::AfterErgo);
3646   if (!constraint_result) {
3647     return JNI_EINVAL;
3648   }
3649 
3650   JVMFlagWriteableList::mark_startup();
3651 
3652   if (PauseAtStartup) {
3653     os::pause();
3654   }
3655 
3656   HOTSPOT_VM_INIT_BEGIN();
3657 
3658   // Timing (must come after argument parsing)
3659   TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3660 
3661 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT
3662   // Initialize assert poison page mechanism.
3663   if (ShowRegistersOnAssert) {
3664     initialize_assert_poison();
3665   }
3666 #endif // CAN_SHOW_REGISTERS_ON_ASSERT
3667 
3668   // Initialize the os module after parsing the args
3669   jint os_init_2_result = os::init_2();
3670   if (os_init_2_result != JNI_OK) return os_init_2_result;
3671 
3672   SafepointMechanism::initialize();
3673 
3674   jint adjust_after_os_result = Arguments::adjust_after_os();
3675   if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3676 
3677   // Initialize output stream logging
3678   ostream_init_log();
3679 
3680   // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3681   // Must be before create_vm_init_agents()
3682   if (Arguments::init_libraries_at_startup()) {
3683     convert_vm_init_libraries_to_agents();
3684   }
3685 
3686   // Launch -agentlib/-agentpath and converted -Xrun agents
3687   if (Arguments::init_agents_at_startup()) {
3688     create_vm_init_agents();
3689   }
3690 
3691   // Initialize Threads state
3692   _thread_list = NULL;
3693   _number_of_threads = 0;
3694   _number_of_non_daemon_threads = 0;
3695 
3696   // Initialize global data structures and create system classes in heap
3697   vm_init_globals();
3698 
3699 #if INCLUDE_JVMCI
3700   if (JVMCICounterSize > 0) {
3701     JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3702     memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3703   } else {
3704     JavaThread::_jvmci_old_thread_counters = NULL;
3705   }
3706 #endif // INCLUDE_JVMCI
3707 
3708   // Attach the main thread to this os thread
3709   JavaThread* main_thread = new JavaThread();
3710   main_thread->set_thread_state(_thread_in_vm);
3711   main_thread->initialize_thread_current();
3712   // must do this before set_active_handles
3713   main_thread->record_stack_base_and_size();
3714   main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3715 
3716   if (!main_thread->set_as_starting_thread()) {
3717     vm_shutdown_during_initialization(
3718                                       "Failed necessary internal allocation. Out of swap space");
3719     main_thread->smr_delete();
3720     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3721     return JNI_ENOMEM;
3722   }
3723 
3724   // Enable guard page *after* os::create_main_thread(), otherwise it would
3725   // crash Linux VM, see notes in os_linux.cpp.
3726   main_thread->create_stack_guard_pages();
3727 
3728   // Initialize Java-Level synchronization subsystem
3729   ObjectMonitor::Initialize();
3730 
3731   // Initialize global modules
3732   jint status = init_globals();
3733   if (status != JNI_OK) {
3734     main_thread->smr_delete();
3735     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3736     return status;
3737   }
3738 
3739   JFR_ONLY(Jfr::on_vm_init();)
3740 
3741   // Should be done after the heap is fully created
3742   main_thread->cache_global_variables();
3743 
3744   HandleMark hm;
3745 
3746   { MutexLocker mu(Threads_lock);
3747     Threads::add(main_thread);
3748   }
3749 
3750   // Any JVMTI raw monitors entered in onload will transition into
3751   // real raw monitor. VM is setup enough here for raw monitor enter.
3752   JvmtiExport::transition_pending_onload_raw_monitors();
3753 
3754   // Create the VMThread
3755   { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3756 
3757   VMThread::create();
3758     Thread* vmthread = VMThread::vm_thread();
3759 
3760     if (!os::create_thread(vmthread, os::vm_thread)) {
3761       vm_exit_during_initialization("Cannot create VM thread. "
3762                                     "Out of system resources.");
3763     }
3764 
3765     // Wait for the VM thread to become ready, and VMThread::run to initialize
3766     // Monitors can have spurious returns, must always check another state flag
3767     {
3768       MutexLocker ml(Notify_lock);
3769       os::start_thread(vmthread);
3770       while (vmthread->active_handles() == NULL) {
3771         Notify_lock->wait();
3772       }
3773     }
3774   }
3775 
3776   assert(Universe::is_fully_initialized(), "not initialized");
3777   if (VerifyDuringStartup) {
3778     // Make sure we're starting with a clean slate.
3779     VM_Verify verify_op;
3780     VMThread::execute(&verify_op);
3781   }
3782 
3783   // We need this to update the java.vm.info property in case any flags used
3784   // to initially define it have been changed. This is needed for both CDS and
3785   // AOT, since UseSharedSpaces and UseAOT may be changed after java.vm.info
3786   // is initially computed. See Abstract_VM_Version::vm_info_string().
3787   // This update must happen before we initialize the java classes, but
3788   // after any initialization logic that might modify the flags.
3789   Arguments::update_vm_info_property(VM_Version::vm_info_string());
3790 
3791   Thread* THREAD = Thread::current();
3792 
3793   // Always call even when there are not JVMTI environments yet, since environments
3794   // may be attached late and JVMTI must track phases of VM execution
3795   JvmtiExport::enter_early_start_phase();
3796 
3797   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3798   JvmtiExport::post_early_vm_start();
3799 
3800   initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3801 
3802   quicken_jni_functions();
3803 
3804   // No more stub generation allowed after that point.
3805   StubCodeDesc::freeze();
3806 
3807   // Set flag that basic initialization has completed. Used by exceptions and various
3808   // debug stuff, that does not work until all basic classes have been initialized.
3809   set_init_completed();
3810 
3811   LogConfiguration::post_initialize();
3812   Metaspace::post_initialize();
3813 
3814   HOTSPOT_VM_INIT_END();
3815 
3816   // record VM initialization completion time
3817 #if INCLUDE_MANAGEMENT
3818   Management::record_vm_init_completed();
3819 #endif // INCLUDE_MANAGEMENT
3820 
3821   // Signal Dispatcher needs to be started before VMInit event is posted
3822   os::initialize_jdk_signal_support(CHECK_JNI_ERR);
3823 
3824   // Start Attach Listener if +StartAttachListener or it can't be started lazily
3825   if (!DisableAttachMechanism) {
3826     AttachListener::vm_start();
3827     if (StartAttachListener || AttachListener::init_at_startup()) {
3828       AttachListener::init();
3829     }
3830   }
3831 
3832   // Launch -Xrun agents
3833   // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3834   // back-end can launch with -Xdebug -Xrunjdwp.
3835   if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3836     create_vm_init_libraries();
3837   }
3838 
3839   if (CleanChunkPoolAsync) {
3840     Chunk::start_chunk_pool_cleaner_task();
3841   }
3842 
3843   // initialize compiler(s)
3844 #if defined(COMPILER1) || COMPILER2_OR_JVMCI
3845 #if INCLUDE_JVMCI
3846   bool force_JVMCI_intialization = false;
3847   if (EnableJVMCI) {
3848     // Initialize JVMCI eagerly when it is explicitly requested.
3849     // Or when JVMCIPrintProperties is enabled.
3850     // The JVMCI Java initialization code will read this flag and
3851     // do the printing if it's set.
3852     force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties;
3853 
3854     if (!force_JVMCI_intialization) {
3855       // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3856       // compilations via JVMCI will not actually block until JVMCI is initialized.
3857       force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3858     }
3859   }
3860 #endif
3861   CompileBroker::compilation_init_phase1(CHECK_JNI_ERR);
3862   // Postpone completion of compiler initialization to after JVMCI
3863   // is initialized to avoid timeouts of blocking compilations.
3864   if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) {
3865     CompileBroker::compilation_init_phase2();
3866   }
3867 #endif
3868 
3869   // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3870   // It is done after compilers are initialized, because otherwise compilations of
3871   // signature polymorphic MH intrinsics can be missed
3872   // (see SystemDictionary::find_method_handle_intrinsic).
3873   initialize_jsr292_core_classes(CHECK_JNI_ERR);
3874 
3875   // This will initialize the module system.  Only java.base classes can be
3876   // loaded until phase 2 completes
3877   call_initPhase2(CHECK_JNI_ERR);
3878 
3879   // Always call even when there are not JVMTI environments yet, since environments
3880   // may be attached late and JVMTI must track phases of VM execution
3881   JvmtiExport::enter_start_phase();
3882 
3883   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3884   JvmtiExport::post_vm_start();
3885 
3886   // Final system initialization including security manager and system class loader
3887   call_initPhase3(CHECK_JNI_ERR);
3888 
3889   // cache the system and platform class loaders
3890   SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
3891 
3892 #if INCLUDE_CDS
3893   if (DumpSharedSpaces) {
3894     // capture the module path info from the ModuleEntryTable
3895     ClassLoader::initialize_module_path(THREAD);
3896   }
3897 #endif
3898 
3899 #if INCLUDE_JVMCI
3900   if (force_JVMCI_intialization) {
3901     JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
3902     CompileBroker::compilation_init_phase2();
3903   }
3904 #endif
3905 
3906   // Always call even when there are not JVMTI environments yet, since environments
3907   // may be attached late and JVMTI must track phases of VM execution
3908   JvmtiExport::enter_live_phase();
3909 
3910   // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3911   JvmtiExport::post_vm_initialized();
3912 
3913   JFR_ONLY(Jfr::on_vm_start();)
3914 
3915 #if INCLUDE_MANAGEMENT
3916   Management::initialize(THREAD);
3917 
3918   if (HAS_PENDING_EXCEPTION) {
3919     // management agent fails to start possibly due to
3920     // configuration problem and is responsible for printing
3921     // stack trace if appropriate. Simply exit VM.
3922     vm_exit(1);
3923   }
3924 #endif // INCLUDE_MANAGEMENT
3925 
3926   if (MemProfiling)                   MemProfiler::engage();
3927   StatSampler::engage();
3928   if (CheckJNICalls)                  JniPeriodicChecker::engage();
3929 
3930   BiasedLocking::init();
3931 
3932 #if INCLUDE_RTM_OPT
3933   RTMLockingCounters::init();
3934 #endif
3935 
3936   if (JDK_Version::current().post_vm_init_hook_enabled()) {
3937     call_postVMInitHook(THREAD);
3938     // The Java side of PostVMInitHook.run must deal with all
3939     // exceptions and provide means of diagnosis.
3940     if (HAS_PENDING_EXCEPTION) {
3941       CLEAR_PENDING_EXCEPTION;
3942     }
3943   }
3944 
3945   {
3946     MutexLocker ml(PeriodicTask_lock);
3947     // Make sure the WatcherThread can be started by WatcherThread::start()
3948     // or by dynamic enrollment.
3949     WatcherThread::make_startable();
3950     // Start up the WatcherThread if there are any periodic tasks
3951     // NOTE:  All PeriodicTasks should be registered by now. If they
3952     //   aren't, late joiners might appear to start slowly (we might
3953     //   take a while to process their first tick).
3954     if (PeriodicTask::num_tasks() > 0) {
3955       WatcherThread::start();
3956     }
3957   }
3958 
3959   create_vm_timer.end();
3960 #ifdef ASSERT
3961   _vm_complete = true;
3962 #endif
3963 
3964   if (DumpSharedSpaces) {
3965     MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3966     ShouldNotReachHere();
3967   }
3968 
3969   return JNI_OK;
3970 }
3971 
3972 // type for the Agent_OnLoad and JVM_OnLoad entry points
3973 extern "C" {
3974   typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3975 }
3976 // Find a command line agent library and return its entry point for
3977 //         -agentlib:  -agentpath:   -Xrun
3978 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3979 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3980                                     const char *on_load_symbols[],
3981                                     size_t num_symbol_entries) {
3982   OnLoadEntry_t on_load_entry = NULL;
3983   void *library = NULL;
3984 
3985   if (!agent->valid()) {
3986     char buffer[JVM_MAXPATHLEN];
3987     char ebuf[1024] = "";
3988     const char *name = agent->name();
3989     const char *msg = "Could not find agent library ";
3990 
3991     // First check to see if agent is statically linked into executable
3992     if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3993       library = agent->os_lib();
3994     } else if (agent->is_absolute_path()) {
3995       library = os::dll_load(name, ebuf, sizeof ebuf);
3996       if (library == NULL) {
3997         const char *sub_msg = " in absolute path, with error: ";
3998         size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3999         char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4000         jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4001         // If we can't find the agent, exit.
4002         vm_exit_during_initialization(buf, NULL);
4003         FREE_C_HEAP_ARRAY(char, buf);
4004       }
4005     } else {
4006       // Try to load the agent from the standard dll directory
4007       if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
4008                              name)) {
4009         library = os::dll_load(buffer, ebuf, sizeof ebuf);
4010       }
4011       if (library == NULL) { // Try the library path directory.
4012         if (os::dll_build_name(buffer, sizeof(buffer), name)) {
4013           library = os::dll_load(buffer, ebuf, sizeof ebuf);
4014         }
4015         if (library == NULL) {
4016           const char *sub_msg = " on the library path, with error: ";
4017           const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image.";
4018 
4019           size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) +
4020                        strlen(ebuf) + strlen(sub_msg2) + 1;
4021           char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4022           if (!agent->is_instrument_lib()) {
4023             jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4024           } else {
4025             jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2);
4026           }
4027           // If we can't find the agent, exit.
4028           vm_exit_during_initialization(buf, NULL);
4029           FREE_C_HEAP_ARRAY(char, buf);
4030         }
4031       }
4032     }
4033     agent->set_os_lib(library);
4034     agent->set_valid();
4035   }
4036 
4037   // Find the OnLoad function.
4038   on_load_entry =
4039     CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
4040                                                           false,
4041                                                           on_load_symbols,
4042                                                           num_symbol_entries));
4043   return on_load_entry;
4044 }
4045 
4046 // Find the JVM_OnLoad entry point
4047 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
4048   const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
4049   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4050 }
4051 
4052 // Find the Agent_OnLoad entry point
4053 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
4054   const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
4055   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4056 }
4057 
4058 // For backwards compatibility with -Xrun
4059 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
4060 // treated like -agentpath:
4061 // Must be called before agent libraries are created
4062 void Threads::convert_vm_init_libraries_to_agents() {
4063   AgentLibrary* agent;
4064   AgentLibrary* next;
4065 
4066   for (agent = Arguments::libraries(); agent != NULL; agent = next) {
4067     next = agent->next();  // cache the next agent now as this agent may get moved off this list
4068     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4069 
4070     // If there is an JVM_OnLoad function it will get called later,
4071     // otherwise see if there is an Agent_OnLoad
4072     if (on_load_entry == NULL) {
4073       on_load_entry = lookup_agent_on_load(agent);
4074       if (on_load_entry != NULL) {
4075         // switch it to the agent list -- so that Agent_OnLoad will be called,
4076         // JVM_OnLoad won't be attempted and Agent_OnUnload will
4077         Arguments::convert_library_to_agent(agent);
4078       } else {
4079         vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
4080       }
4081     }
4082   }
4083 }
4084 
4085 // Create agents for -agentlib:  -agentpath:  and converted -Xrun
4086 // Invokes Agent_OnLoad
4087 // Called very early -- before JavaThreads exist
4088 void Threads::create_vm_init_agents() {
4089   extern struct JavaVM_ main_vm;
4090   AgentLibrary* agent;
4091 
4092   JvmtiExport::enter_onload_phase();
4093 
4094   for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4095     OnLoadEntry_t  on_load_entry = lookup_agent_on_load(agent);
4096 
4097     if (on_load_entry != NULL) {
4098       // Invoke the Agent_OnLoad function
4099       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4100       if (err != JNI_OK) {
4101         vm_exit_during_initialization("agent library failed to init", agent->name());
4102       }
4103     } else {
4104       vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4105     }
4106   }
4107   JvmtiExport::enter_primordial_phase();
4108 }
4109 
4110 extern "C" {
4111   typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4112 }
4113 
4114 void Threads::shutdown_vm_agents() {
4115   // Send any Agent_OnUnload notifications
4116   const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4117   size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4118   extern struct JavaVM_ main_vm;
4119   for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4120 
4121     // Find the Agent_OnUnload function.
4122     Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4123                                                    os::find_agent_function(agent,
4124                                                    false,
4125                                                    on_unload_symbols,
4126                                                    num_symbol_entries));
4127 
4128     // Invoke the Agent_OnUnload function
4129     if (unload_entry != NULL) {
4130       JavaThread* thread = JavaThread::current();
4131       ThreadToNativeFromVM ttn(thread);
4132       HandleMark hm(thread);
4133       (*unload_entry)(&main_vm);
4134     }
4135   }
4136 }
4137 
4138 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4139 // Invokes JVM_OnLoad
4140 void Threads::create_vm_init_libraries() {
4141   extern struct JavaVM_ main_vm;
4142   AgentLibrary* agent;
4143 
4144   for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4145     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4146 
4147     if (on_load_entry != NULL) {
4148       // Invoke the JVM_OnLoad function
4149       JavaThread* thread = JavaThread::current();
4150       ThreadToNativeFromVM ttn(thread);
4151       HandleMark hm(thread);
4152       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4153       if (err != JNI_OK) {
4154         vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4155       }
4156     } else {
4157       vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4158     }
4159   }
4160 }
4161 
4162 
4163 // Last thread running calls java.lang.Shutdown.shutdown()
4164 void JavaThread::invoke_shutdown_hooks() {
4165   HandleMark hm(this);
4166 
4167   // We could get here with a pending exception, if so clear it now.
4168   if (this->has_pending_exception()) {
4169     this->clear_pending_exception();
4170   }
4171 
4172   EXCEPTION_MARK;
4173   Klass* shutdown_klass =
4174     SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4175                                       THREAD);
4176   if (shutdown_klass != NULL) {
4177     // SystemDictionary::resolve_or_null will return null if there was
4178     // an exception.  If we cannot load the Shutdown class, just don't
4179     // call Shutdown.shutdown() at all.  This will mean the shutdown hooks
4180     // won't be run.  Note that if a shutdown hook was registered,
4181     // the Shutdown class would have already been loaded
4182     // (Runtime.addShutdownHook will load it).
4183     JavaValue result(T_VOID);
4184     JavaCalls::call_static(&result,
4185                            shutdown_klass,
4186                            vmSymbols::shutdown_method_name(),
4187                            vmSymbols::void_method_signature(),
4188                            THREAD);
4189   }
4190   CLEAR_PENDING_EXCEPTION;
4191 }
4192 
4193 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4194 // the program falls off the end of main(). Another VM exit path is through
4195 // vm_exit() when the program calls System.exit() to return a value or when
4196 // there is a serious error in VM. The two shutdown paths are not exactly
4197 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4198 // and VM_Exit op at VM level.
4199 //
4200 // Shutdown sequence:
4201 //   + Shutdown native memory tracking if it is on
4202 //   + Wait until we are the last non-daemon thread to execute
4203 //     <-- every thing is still working at this moment -->
4204 //   + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4205 //        shutdown hooks
4206 //   + Call before_exit(), prepare for VM exit
4207 //      > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4208 //        currently the only user of this mechanism is File.deleteOnExit())
4209 //      > stop StatSampler, watcher thread, CMS threads,
4210 //        post thread end and vm death events to JVMTI,
4211 //        stop signal thread
4212 //   + Call JavaThread::exit(), it will:
4213 //      > release JNI handle blocks, remove stack guard pages
4214 //      > remove this thread from Threads list
4215 //     <-- no more Java code from this thread after this point -->
4216 //   + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4217 //     the compiler threads at safepoint
4218 //     <-- do not use anything that could get blocked by Safepoint -->
4219 //   + Disable tracing at JNI/JVM barriers
4220 //   + Set _vm_exited flag for threads that are still running native code
4221 //   + Call exit_globals()
4222 //      > deletes tty
4223 //      > deletes PerfMemory resources
4224 //   + Delete this thread
4225 //   + Return to caller
4226 
4227 bool Threads::destroy_vm() {
4228   JavaThread* thread = JavaThread::current();
4229 
4230 #ifdef ASSERT
4231   _vm_complete = false;
4232 #endif
4233   // Wait until we are the last non-daemon thread to execute
4234   { MutexLocker nu(Threads_lock);
4235     while (Threads::number_of_non_daemon_threads() > 1)
4236       // This wait should make safepoint checks, wait without a timeout,
4237       // and wait as a suspend-equivalent condition.
4238       Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4239                          Mutex::_as_suspend_equivalent_flag);
4240   }
4241 
4242   EventShutdown e;
4243   if (e.should_commit()) {
4244     e.set_reason("No remaining non-daemon Java threads");
4245     e.commit();
4246   }
4247 
4248   // Hang forever on exit if we are reporting an error.
4249   if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4250     os::infinite_sleep();
4251   }
4252   os::wait_for_keypress_at_exit();
4253 
4254   // run Java level shutdown hooks
4255   thread->invoke_shutdown_hooks();
4256 
4257   before_exit(thread);
4258 
4259   thread->exit(true);
4260   // thread will never call smr_delete, instead of implicit cancel
4261   // in wait_for_vm_thread_exit we do it explicit.
4262   thread->cancel_handshake();
4263 
4264   // Stop VM thread.
4265   {
4266     // 4945125 The vm thread comes to a safepoint during exit.
4267     // GC vm_operations can get caught at the safepoint, and the
4268     // heap is unparseable if they are caught. Grab the Heap_lock
4269     // to prevent this. The GC vm_operations will not be able to
4270     // queue until after the vm thread is dead. After this point,
4271     // we'll never emerge out of the safepoint before the VM exits.
4272 
4273     MutexLocker ml(Heap_lock);
4274 
4275     VMThread::wait_for_vm_thread_exit();
4276     assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4277     VMThread::destroy();
4278   }
4279 
4280   // Now, all Java threads are gone except daemon threads. Daemon threads
4281   // running Java code or in VM are stopped by the Safepoint. However,
4282   // daemon threads executing native code are still running.  But they
4283   // will be stopped at native=>Java/VM barriers. Note that we can't
4284   // simply kill or suspend them, as it is inherently deadlock-prone.
4285 
4286   VM_Exit::set_vm_exited();
4287 
4288   // Clean up ideal graph printers after the VMThread has started
4289   // the final safepoint which will block all the Compiler threads.
4290   // Note that this Thread has already logically exited so the
4291   // clean_up() function's use of a JavaThreadIteratorWithHandle
4292   // would be a problem except set_vm_exited() has remembered the
4293   // shutdown thread which is granted a policy exception.
4294 #if defined(COMPILER2) && !defined(PRODUCT)
4295   IdealGraphPrinter::clean_up();
4296 #endif
4297 
4298   notify_vm_shutdown();
4299 
4300   // exit_globals() will delete tty
4301   exit_globals();
4302 
4303   // We are after VM_Exit::set_vm_exited() so we can't call
4304   // thread->smr_delete() or we will block on the Threads_lock.
4305   // Deleting the shutdown thread here is safe because another
4306   // JavaThread cannot have an active ThreadsListHandle for
4307   // this JavaThread.
4308   delete thread;
4309 
4310 #if INCLUDE_JVMCI
4311   if (JVMCICounterSize > 0) {
4312     FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4313   }
4314 #endif
4315 
4316   LogConfiguration::finalize();
4317 
4318   return true;
4319 }
4320 
4321 
4322 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4323   if (version == JNI_VERSION_1_1) return JNI_TRUE;
4324   return is_supported_jni_version(version);
4325 }
4326 
4327 
4328 jboolean Threads::is_supported_jni_version(jint version) {
4329   if (version == JNI_VERSION_1_2) return JNI_TRUE;
4330   if (version == JNI_VERSION_1_4) return JNI_TRUE;
4331   if (version == JNI_VERSION_1_6) return JNI_TRUE;
4332   if (version == JNI_VERSION_1_8) return JNI_TRUE;
4333   if (version == JNI_VERSION_9) return JNI_TRUE;
4334   if (version == JNI_VERSION_10) return JNI_TRUE;
4335   return JNI_FALSE;
4336 }
4337 
4338 
4339 void Threads::add(JavaThread* p, bool force_daemon) {
4340   // The threads lock must be owned at this point
4341   assert(Threads_lock->owned_by_self(), "must have threads lock");
4342 
4343   BarrierSet::barrier_set()->on_thread_attach(p);
4344 
4345   p->set_next(_thread_list);
4346   _thread_list = p;
4347 
4348   // Once a JavaThread is added to the Threads list, smr_delete() has
4349   // to be used to delete it. Otherwise we can just delete it directly.
4350   p->set_on_thread_list();
4351 
4352   _number_of_threads++;
4353   oop threadObj = p->threadObj();
4354   bool daemon = true;
4355   // Bootstrapping problem: threadObj can be null for initial
4356   // JavaThread (or for threads attached via JNI)
4357   if ((!force_daemon) && !is_daemon((threadObj))) {
4358     _number_of_non_daemon_threads++;
4359     daemon = false;
4360   }
4361 
4362   ThreadService::add_thread(p, daemon);
4363 
4364   // Maintain fast thread list
4365   ThreadsSMRSupport::add_thread(p);
4366 
4367   // Possible GC point.
4368   Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4369 }
4370 
4371 void Threads::remove(JavaThread* p) {
4372 
4373   // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread.
4374   ObjectSynchronizer::omFlush(p);
4375 
4376   // Extra scope needed for Thread_lock, so we can check
4377   // that we do not remove thread without safepoint code notice
4378   { MutexLocker ml(Threads_lock);
4379 
4380     assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present");
4381 
4382     // Maintain fast thread list
4383     ThreadsSMRSupport::remove_thread(p);
4384 
4385     JavaThread* current = _thread_list;
4386     JavaThread* prev    = NULL;
4387 
4388     while (current != p) {
4389       prev    = current;
4390       current = current->next();
4391     }
4392 
4393     if (prev) {
4394       prev->set_next(current->next());
4395     } else {
4396       _thread_list = p->next();
4397     }
4398 
4399     _number_of_threads--;
4400     oop threadObj = p->threadObj();
4401     bool daemon = true;
4402     if (!is_daemon(threadObj)) {
4403       _number_of_non_daemon_threads--;
4404       daemon = false;
4405 
4406       // Only one thread left, do a notify on the Threads_lock so a thread waiting
4407       // on destroy_vm will wake up.
4408       if (number_of_non_daemon_threads() == 1) {
4409         Threads_lock->notify_all();
4410       }
4411     }
4412     ThreadService::remove_thread(p, daemon);
4413 
4414     // Make sure that safepoint code disregard this thread. This is needed since
4415     // the thread might mess around with locks after this point. This can cause it
4416     // to do callbacks into the safepoint code. However, the safepoint code is not aware
4417     // of this thread since it is removed from the queue.
4418     p->set_terminated_value();
4419   } // unlock Threads_lock
4420 
4421   // Since Events::log uses a lock, we grab it outside the Threads_lock
4422   Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4423 }
4424 
4425 // Operations on the Threads list for GC.  These are not explicitly locked,
4426 // but the garbage collector must provide a safe context for them to run.
4427 // In particular, these things should never be called when the Threads_lock
4428 // is held by some other thread. (Note: the Safepoint abstraction also
4429 // uses the Threads_lock to guarantee this property. It also makes sure that
4430 // all threads gets blocked when exiting or starting).
4431 
4432 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4433   ALL_JAVA_THREADS(p) {
4434     p->oops_do(f, cf);
4435   }
4436   VMThread::vm_thread()->oops_do(f, cf);
4437 }
4438 
4439 void Threads::change_thread_claim_parity() {
4440   // Set the new claim parity.
4441   assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4442          "Not in range.");
4443   _thread_claim_parity++;
4444   if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4445   assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4446          "Not in range.");
4447 }
4448 
4449 #ifdef ASSERT
4450 void Threads::assert_all_threads_claimed() {
4451   ALL_JAVA_THREADS(p) {
4452     const int thread_parity = p->oops_do_parity();
4453     assert((thread_parity == _thread_claim_parity),
4454            "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4455   }
4456   VMThread* vmt = VMThread::vm_thread();
4457   const int thread_parity = vmt->oops_do_parity();
4458   assert((thread_parity == _thread_claim_parity),
4459          "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity);
4460 }
4461 #endif // ASSERT
4462 
4463 class ParallelOopsDoThreadClosure : public ThreadClosure {
4464 private:
4465   OopClosure* _f;
4466   CodeBlobClosure* _cf;
4467 public:
4468   ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {}
4469   void do_thread(Thread* t) {
4470     t->oops_do(_f, _cf);
4471   }
4472 };
4473 
4474 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4475   ParallelOopsDoThreadClosure tc(f, cf);
4476   possibly_parallel_threads_do(is_par, &tc);
4477 }
4478 
4479 void Threads::nmethods_do(CodeBlobClosure* cf) {
4480   ALL_JAVA_THREADS(p) {
4481     // This is used by the code cache sweeper to mark nmethods that are active
4482     // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4483     // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4484     if(!p->is_Code_cache_sweeper_thread()) {
4485       p->nmethods_do(cf);
4486     }
4487   }
4488 }
4489 
4490 void Threads::metadata_do(void f(Metadata*)) {
4491   ALL_JAVA_THREADS(p) {
4492     p->metadata_do(f);
4493   }
4494 }
4495 
4496 class ThreadHandlesClosure : public ThreadClosure {
4497   void (*_f)(Metadata*);
4498  public:
4499   ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4500   virtual void do_thread(Thread* thread) {
4501     thread->metadata_handles_do(_f);
4502   }
4503 };
4504 
4505 void Threads::metadata_handles_do(void f(Metadata*)) {
4506   // Only walk the Handles in Thread.
4507   ThreadHandlesClosure handles_closure(f);
4508   threads_do(&handles_closure);
4509 }
4510 
4511 void Threads::deoptimized_wrt_marked_nmethods() {
4512   ALL_JAVA_THREADS(p) {
4513     p->deoptimized_wrt_marked_nmethods();
4514   }
4515 }
4516 
4517 
4518 // Get count Java threads that are waiting to enter the specified monitor.
4519 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
4520                                                          int count,
4521                                                          address monitor) {
4522   GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4523 
4524   int i = 0;
4525   DO_JAVA_THREADS(t_list, p) {
4526     if (!p->can_call_java()) continue;
4527 
4528     address pending = (address)p->current_pending_monitor();
4529     if (pending == monitor) {             // found a match
4530       if (i < count) result->append(p);   // save the first count matches
4531       i++;
4532     }
4533   }
4534 
4535   return result;
4536 }
4537 
4538 
4539 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
4540                                                       address owner) {
4541   // NULL owner means not locked so we can skip the search
4542   if (owner == NULL) return NULL;
4543 
4544   DO_JAVA_THREADS(t_list, p) {
4545     // first, see if owner is the address of a Java thread
4546     if (owner == (address)p) return p;
4547   }
4548 
4549   // Cannot assert on lack of success here since this function may be
4550   // used by code that is trying to report useful problem information
4551   // like deadlock detection.
4552   if (UseHeavyMonitors) return NULL;
4553 
4554   // If we didn't find a matching Java thread and we didn't force use of
4555   // heavyweight monitors, then the owner is the stack address of the
4556   // Lock Word in the owning Java thread's stack.
4557   //
4558   JavaThread* the_owner = NULL;
4559   DO_JAVA_THREADS(t_list, q) {
4560     if (q->is_lock_owned(owner)) {
4561       the_owner = q;
4562       break;
4563     }
4564   }
4565 
4566   // cannot assert on lack of success here; see above comment
4567   return the_owner;
4568 }
4569 
4570 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4571 void Threads::print_on(outputStream* st, bool print_stacks,
4572                        bool internal_format, bool print_concurrent_locks,
4573                        bool print_extended_info) {
4574   char buf[32];
4575   st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4576 
4577   st->print_cr("Full thread dump %s (%s %s):",
4578                Abstract_VM_Version::vm_name(),
4579                Abstract_VM_Version::vm_release(),
4580                Abstract_VM_Version::vm_info_string());
4581   st->cr();
4582 
4583 #if INCLUDE_SERVICES
4584   // Dump concurrent locks
4585   ConcurrentLocksDump concurrent_locks;
4586   if (print_concurrent_locks) {
4587     concurrent_locks.dump_at_safepoint();
4588   }
4589 #endif // INCLUDE_SERVICES
4590 
4591   ThreadsSMRSupport::print_info_on(st);
4592   st->cr();
4593 
4594   ALL_JAVA_THREADS(p) {
4595     ResourceMark rm;
4596     p->print_on(st, print_extended_info);
4597     if (print_stacks) {
4598       if (internal_format) {
4599         p->trace_stack();
4600       } else {
4601         p->print_stack_on(st);
4602       }
4603     }
4604     st->cr();
4605 #if INCLUDE_SERVICES
4606     if (print_concurrent_locks) {
4607       concurrent_locks.print_locks_on(p, st);
4608     }
4609 #endif // INCLUDE_SERVICES
4610   }
4611 
4612   VMThread::vm_thread()->print_on(st);
4613   st->cr();
4614   Universe::heap()->print_gc_threads_on(st);
4615   WatcherThread* wt = WatcherThread::watcher_thread();
4616   if (wt != NULL) {
4617     wt->print_on(st);
4618     st->cr();
4619   }
4620 
4621   st->flush();
4622 }
4623 
4624 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4625                              int buflen, bool* found_current) {
4626   if (this_thread != NULL) {
4627     bool is_current = (current == this_thread);
4628     *found_current = *found_current || is_current;
4629     st->print("%s", is_current ? "=>" : "  ");
4630 
4631     st->print(PTR_FORMAT, p2i(this_thread));
4632     st->print(" ");
4633     this_thread->print_on_error(st, buf, buflen);
4634     st->cr();
4635   }
4636 }
4637 
4638 class PrintOnErrorClosure : public ThreadClosure {
4639   outputStream* _st;
4640   Thread* _current;
4641   char* _buf;
4642   int _buflen;
4643   bool* _found_current;
4644  public:
4645   PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4646                       int buflen, bool* found_current) :
4647    _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4648 
4649   virtual void do_thread(Thread* thread) {
4650     Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4651   }
4652 };
4653 
4654 // Threads::print_on_error() is called by fatal error handler. It's possible
4655 // that VM is not at safepoint and/or current thread is inside signal handler.
4656 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4657 // memory (even in resource area), it might deadlock the error handler.
4658 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4659                              int buflen) {
4660   ThreadsSMRSupport::print_info_on(st);
4661   st->cr();
4662 
4663   bool found_current = false;
4664   st->print_cr("Java Threads: ( => current thread )");
4665   ALL_JAVA_THREADS(thread) {
4666     print_on_error(thread, st, current, buf, buflen, &found_current);
4667   }
4668   st->cr();
4669 
4670   st->print_cr("Other Threads:");
4671   print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4672   print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4673 
4674   PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4675   Universe::heap()->gc_threads_do(&print_closure);
4676 
4677   if (!found_current) {
4678     st->cr();
4679     st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4680     current->print_on_error(st, buf, buflen);
4681     st->cr();
4682   }
4683   st->cr();
4684 
4685   st->print_cr("Threads with active compile tasks:");
4686   print_threads_compiling(st, buf, buflen);
4687 }
4688 
4689 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4690   ALL_JAVA_THREADS(thread) {
4691     if (thread->is_Compiler_thread()) {
4692       CompilerThread* ct = (CompilerThread*) thread;
4693 
4694       // Keep task in local variable for NULL check.
4695       // ct->_task might be set to NULL by concurring compiler thread
4696       // because it completed the compilation. The task is never freed,
4697       // though, just returned to a free list.
4698       CompileTask* task = ct->task();
4699       if (task != NULL) {
4700         thread->print_name_on_error(st, buf, buflen);
4701         task->print(st, NULL, true, true);
4702       }
4703     }
4704   }
4705 }
4706 
4707 
4708 // Internal SpinLock and Mutex
4709 // Based on ParkEvent
4710 
4711 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4712 //
4713 // We employ SpinLocks _only for low-contention, fixed-length
4714 // short-duration critical sections where we're concerned
4715 // about native mutex_t or HotSpot Mutex:: latency.
4716 // The mux construct provides a spin-then-block mutual exclusion
4717 // mechanism.
4718 //
4719 // Testing has shown that contention on the ListLock guarding gFreeList
4720 // is common.  If we implement ListLock as a simple SpinLock it's common
4721 // for the JVM to devolve to yielding with little progress.  This is true
4722 // despite the fact that the critical sections protected by ListLock are
4723 // extremely short.
4724 //
4725 // TODO-FIXME: ListLock should be of type SpinLock.
4726 // We should make this a 1st-class type, integrated into the lock
4727 // hierarchy as leaf-locks.  Critically, the SpinLock structure
4728 // should have sufficient padding to avoid false-sharing and excessive
4729 // cache-coherency traffic.
4730 
4731 
4732 typedef volatile int SpinLockT;
4733 
4734 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4735   if (Atomic::cmpxchg (1, adr, 0) == 0) {
4736     return;   // normal fast-path return
4737   }
4738 
4739   // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4740   int ctr = 0;
4741   int Yields = 0;
4742   for (;;) {
4743     while (*adr != 0) {
4744       ++ctr;
4745       if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4746         if (Yields > 5) {
4747           os::naked_short_sleep(1);
4748         } else {
4749           os::naked_yield();
4750           ++Yields;
4751         }
4752       } else {
4753         SpinPause();
4754       }
4755     }
4756     if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4757   }
4758 }
4759 
4760 void Thread::SpinRelease(volatile int * adr) {
4761   assert(*adr != 0, "invariant");
4762   OrderAccess::fence();      // guarantee at least release consistency.
4763   // Roach-motel semantics.
4764   // It's safe if subsequent LDs and STs float "up" into the critical section,
4765   // but prior LDs and STs within the critical section can't be allowed
4766   // to reorder or float past the ST that releases the lock.
4767   // Loads and stores in the critical section - which appear in program
4768   // order before the store that releases the lock - must also appear
4769   // before the store that releases the lock in memory visibility order.
4770   // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4771   // the ST of 0 into the lock-word which releases the lock, so fence
4772   // more than covers this on all platforms.
4773   *adr = 0;
4774 }
4775 
4776 // muxAcquire and muxRelease:
4777 //
4778 // *  muxAcquire and muxRelease support a single-word lock-word construct.
4779 //    The LSB of the word is set IFF the lock is held.
4780 //    The remainder of the word points to the head of a singly-linked list
4781 //    of threads blocked on the lock.
4782 //
4783 // *  The current implementation of muxAcquire-muxRelease uses its own
4784 //    dedicated Thread._MuxEvent instance.  If we're interested in
4785 //    minimizing the peak number of extant ParkEvent instances then
4786 //    we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4787 //    as certain invariants were satisfied.  Specifically, care would need
4788 //    to be taken with regards to consuming unpark() "permits".
4789 //    A safe rule of thumb is that a thread would never call muxAcquire()
4790 //    if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4791 //    park().  Otherwise the _ParkEvent park() operation in muxAcquire() could
4792 //    consume an unpark() permit intended for monitorenter, for instance.
4793 //    One way around this would be to widen the restricted-range semaphore
4794 //    implemented in park().  Another alternative would be to provide
4795 //    multiple instances of the PlatformEvent() for each thread.  One
4796 //    instance would be dedicated to muxAcquire-muxRelease, for instance.
4797 //
4798 // *  Usage:
4799 //    -- Only as leaf locks
4800 //    -- for short-term locking only as muxAcquire does not perform
4801 //       thread state transitions.
4802 //
4803 // Alternatives:
4804 // *  We could implement muxAcquire and muxRelease with MCS or CLH locks
4805 //    but with parking or spin-then-park instead of pure spinning.
4806 // *  Use Taura-Oyama-Yonenzawa locks.
4807 // *  It's possible to construct a 1-0 lock if we encode the lockword as
4808 //    (List,LockByte).  Acquire will CAS the full lockword while Release
4809 //    will STB 0 into the LockByte.  The 1-0 scheme admits stranding, so
4810 //    acquiring threads use timers (ParkTimed) to detect and recover from
4811 //    the stranding window.  Thread/Node structures must be aligned on 256-byte
4812 //    boundaries by using placement-new.
4813 // *  Augment MCS with advisory back-link fields maintained with CAS().
4814 //    Pictorially:  LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4815 //    The validity of the backlinks must be ratified before we trust the value.
4816 //    If the backlinks are invalid the exiting thread must back-track through the
4817 //    the forward links, which are always trustworthy.
4818 // *  Add a successor indication.  The LockWord is currently encoded as
4819 //    (List, LOCKBIT:1).  We could also add a SUCCBIT or an explicit _succ variable
4820 //    to provide the usual futile-wakeup optimization.
4821 //    See RTStt for details.
4822 //
4823 
4824 
4825 const intptr_t LOCKBIT = 1;
4826 
4827 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4828   intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4829   if (w == 0) return;
4830   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4831     return;
4832   }
4833 
4834   ParkEvent * const Self = Thread::current()->_MuxEvent;
4835   assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4836   for (;;) {
4837     int its = (os::is_MP() ? 100 : 0) + 1;
4838 
4839     // Optional spin phase: spin-then-park strategy
4840     while (--its >= 0) {
4841       w = *Lock;
4842       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4843         return;
4844       }
4845     }
4846 
4847     Self->reset();
4848     Self->OnList = intptr_t(Lock);
4849     // The following fence() isn't _strictly necessary as the subsequent
4850     // CAS() both serializes execution and ratifies the fetched *Lock value.
4851     OrderAccess::fence();
4852     for (;;) {
4853       w = *Lock;
4854       if ((w & LOCKBIT) == 0) {
4855         if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4856           Self->OnList = 0;   // hygiene - allows stronger asserts
4857           return;
4858         }
4859         continue;      // Interference -- *Lock changed -- Just retry
4860       }
4861       assert(w & LOCKBIT, "invariant");
4862       Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4863       if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4864     }
4865 
4866     while (Self->OnList != 0) {
4867       Self->park();
4868     }
4869   }
4870 }
4871 
4872 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4873   intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4874   if (w == 0) return;
4875   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4876     return;
4877   }
4878 
4879   ParkEvent * ReleaseAfter = NULL;
4880   if (ev == NULL) {
4881     ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4882   }
4883   assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4884   for (;;) {
4885     guarantee(ev->OnList == 0, "invariant");
4886     int its = (os::is_MP() ? 100 : 0) + 1;
4887 
4888     // Optional spin phase: spin-then-park strategy
4889     while (--its >= 0) {
4890       w = *Lock;
4891       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4892         if (ReleaseAfter != NULL) {
4893           ParkEvent::Release(ReleaseAfter);
4894         }
4895         return;
4896       }
4897     }
4898 
4899     ev->reset();
4900     ev->OnList = intptr_t(Lock);
4901     // The following fence() isn't _strictly necessary as the subsequent
4902     // CAS() both serializes execution and ratifies the fetched *Lock value.
4903     OrderAccess::fence();
4904     for (;;) {
4905       w = *Lock;
4906       if ((w & LOCKBIT) == 0) {
4907         if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4908           ev->OnList = 0;
4909           // We call ::Release while holding the outer lock, thus
4910           // artificially lengthening the critical section.
4911           // Consider deferring the ::Release() until the subsequent unlock(),
4912           // after we've dropped the outer lock.
4913           if (ReleaseAfter != NULL) {
4914             ParkEvent::Release(ReleaseAfter);
4915           }
4916           return;
4917         }
4918         continue;      // Interference -- *Lock changed -- Just retry
4919       }
4920       assert(w & LOCKBIT, "invariant");
4921       ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4922       if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4923     }
4924 
4925     while (ev->OnList != 0) {
4926       ev->park();
4927     }
4928   }
4929 }
4930 
4931 // Release() must extract a successor from the list and then wake that thread.
4932 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4933 // similar to that used by ParkEvent::Allocate() and ::Release().  DMR-based
4934 // Release() would :
4935 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4936 // (B) Extract a successor from the private list "in-hand"
4937 // (C) attempt to CAS() the residual back into *Lock over null.
4938 //     If there were any newly arrived threads and the CAS() would fail.
4939 //     In that case Release() would detach the RATs, re-merge the list in-hand
4940 //     with the RATs and repeat as needed.  Alternately, Release() might
4941 //     detach and extract a successor, but then pass the residual list to the wakee.
4942 //     The wakee would be responsible for reattaching and remerging before it
4943 //     competed for the lock.
4944 //
4945 // Both "pop" and DMR are immune from ABA corruption -- there can be
4946 // multiple concurrent pushers, but only one popper or detacher.
4947 // This implementation pops from the head of the list.  This is unfair,
4948 // but tends to provide excellent throughput as hot threads remain hot.
4949 // (We wake recently run threads first).
4950 //
4951 // All paths through muxRelease() will execute a CAS.
4952 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4953 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4954 // executed within the critical section are complete and globally visible before the
4955 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4956 void Thread::muxRelease(volatile intptr_t * Lock)  {
4957   for (;;) {
4958     const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT);
4959     assert(w & LOCKBIT, "invariant");
4960     if (w == LOCKBIT) return;
4961     ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4962     assert(List != NULL, "invariant");
4963     assert(List->OnList == intptr_t(Lock), "invariant");
4964     ParkEvent * const nxt = List->ListNext;
4965     guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4966 
4967     // The following CAS() releases the lock and pops the head element.
4968     // The CAS() also ratifies the previously fetched lock-word value.
4969     if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) {
4970       continue;
4971     }
4972     List->OnList = 0;
4973     OrderAccess::fence();
4974     List->unpark();
4975     return;
4976   }
4977 }
4978 
4979 
4980 void Threads::verify() {
4981   ALL_JAVA_THREADS(p) {
4982     p->verify();
4983   }
4984   VMThread* thread = VMThread::vm_thread();
4985   if (thread != NULL) thread->verify();
4986 }