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/gcId.hpp"
  37 #include "gc/shared/gcLocker.inline.hpp"
  38 #include "gc/shared/workgroup.hpp"
  39 #include "interpreter/interpreter.hpp"
  40 #include "interpreter/linkResolver.hpp"
  41 #include "interpreter/oopMapCache.hpp"
  42 #include "jvmtifiles/jvmtiEnv.hpp"
  43 #include "logging/log.hpp"
  44 #include "logging/logConfiguration.hpp"
  45 #include "logging/logStream.hpp"
  46 #include "memory/allocation.inline.hpp"
  47 #include "memory/metaspaceShared.hpp"
  48 #include "memory/oopFactory.hpp"
  49 #include "memory/resourceArea.hpp"
  50 #include "memory/universe.hpp"
  51 #include "oops/instanceKlass.hpp"
  52 #include "oops/objArrayOop.hpp"
  53 #include "oops/oop.inline.hpp"
  54 #include "oops/symbol.hpp"
  55 #include "oops/typeArrayOop.inline.hpp"
  56 #include "oops/verifyOopClosure.hpp"
  57 #include "prims/jvm_misc.hpp"
  58 #include "prims/jvmtiExport.hpp"
  59 #include "prims/jvmtiThreadState.hpp"
  60 #include "prims/privilegedStack.hpp"
  61 #include "runtime/arguments.hpp"
  62 #include "runtime/atomic.hpp"
  63 #include "runtime/biasedLocking.hpp"
  64 #include "runtime/commandLineFlagConstraintList.hpp"
  65 #include "runtime/commandLineFlagWriteableList.hpp"
  66 #include "runtime/commandLineFlagRangeList.hpp"
  67 #include "runtime/deoptimization.hpp"
  68 #include "runtime/frame.inline.hpp"
  69 #include "runtime/globals.hpp"
  70 #include "runtime/handshake.hpp"
  71 #include "runtime/init.hpp"
  72 #include "runtime/interfaceSupport.inline.hpp"
  73 #include "runtime/java.hpp"
  74 #include "runtime/javaCalls.hpp"
  75 #include "runtime/jniHandles.inline.hpp"
  76 #include "runtime/jniPeriodicChecker.hpp"
  77 #include "runtime/memprofiler.hpp"
  78 #include "runtime/mutexLocker.hpp"
  79 #include "runtime/objectMonitor.hpp"
  80 #include "runtime/orderAccess.inline.hpp"
  81 #include "runtime/osThread.hpp"
  82 #include "runtime/prefetch.inline.hpp"
  83 #include "runtime/safepoint.hpp"
  84 #include "runtime/safepointMechanism.inline.hpp"
  85 #include "runtime/sharedRuntime.hpp"
  86 #include "runtime/statSampler.hpp"
  87 #include "runtime/stubRoutines.hpp"
  88 #include "runtime/sweeper.hpp"
  89 #include "runtime/task.hpp"
  90 #include "runtime/thread.inline.hpp"
  91 #include "runtime/threadCritical.hpp"
  92 #include "runtime/threadSMR.inline.hpp"
  93 #include "runtime/timer.hpp"
  94 #include "runtime/timerTrace.hpp"
  95 #include "runtime/vframe.inline.hpp"
  96 #include "runtime/vframeArray.hpp"
  97 #include "runtime/vframe_hp.hpp"
  98 #include "runtime/vmThread.hpp"
  99 #include "runtime/vm_operations.hpp"
 100 #include "runtime/vm_version.hpp"
 101 #include "services/attachListener.hpp"
 102 #include "services/management.hpp"
 103 #include "services/memTracker.hpp"
 104 #include "services/threadService.hpp"
 105 #include "trace/traceMacros.hpp"
 106 #include "trace/tracing.hpp"
 107 #include "utilities/align.hpp"
 108 #include "utilities/defaultStream.hpp"
 109 #include "utilities/dtrace.hpp"
 110 #include "utilities/events.hpp"
 111 #include "utilities/macros.hpp"
 112 #include "utilities/preserveException.hpp"
 113 #include "utilities/vmError.hpp"
 114 #if INCLUDE_ALL_GCS
 115 #include "gc/cms/concurrentMarkSweepThread.hpp"
 116 #include "gc/g1/concurrentMarkThread.inline.hpp"
 117 #include "gc/parallel/pcTasks.hpp"
 118 #endif // INCLUDE_ALL_GCS
 119 #if INCLUDE_JVMCI
 120 #include "jvmci/jvmciCompiler.hpp"
 121 #include "jvmci/jvmciRuntime.hpp"
 122 #include "logging/logHandle.hpp"
 123 #endif
 124 #ifdef COMPILER1
 125 #include "c1/c1_Compiler.hpp"
 126 #endif
 127 #ifdef COMPILER2
 128 #include "opto/c2compiler.hpp"
 129 #include "opto/idealGraphPrinter.hpp"
 130 #endif
 131 #if INCLUDE_RTM_OPT
 132 #include "runtime/rtmLocking.hpp"
 133 #endif
 134 
 135 // Initialization after module runtime initialization
 136 void universe_post_module_init();  // must happen after call_initPhase2
 137 
 138 #ifdef DTRACE_ENABLED
 139 
 140 // Only bother with this argument setup if dtrace is available
 141 
 142   #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
 143   #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
 144 
 145   #define DTRACE_THREAD_PROBE(probe, javathread)                           \
 146     {                                                                      \
 147       ResourceMark rm(this);                                               \
 148       int len = 0;                                                         \
 149       const char* name = (javathread)->get_thread_name();                  \
 150       len = strlen(name);                                                  \
 151       HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */               \
 152         (char *) name, len,                                                \
 153         java_lang_Thread::thread_id((javathread)->threadObj()),            \
 154         (uintptr_t) (javathread)->osthread()->thread_id(),                 \
 155         java_lang_Thread::is_daemon((javathread)->threadObj()));           \
 156     }
 157 
 158 #else //  ndef DTRACE_ENABLED
 159 
 160   #define DTRACE_THREAD_PROBE(probe, javathread)
 161 
 162 #endif // ndef DTRACE_ENABLED
 163 
 164 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 165 // Current thread is maintained as a thread-local variable
 166 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
 167 #endif
 168 // Class hierarchy
 169 // - Thread
 170 //   - VMThread
 171 //   - WatcherThread
 172 //   - ConcurrentMarkSweepThread
 173 //   - JavaThread
 174 //     - CompilerThread
 175 
 176 // ======= Thread ========
 177 // Support for forcing alignment of thread objects for biased locking
 178 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
 179   if (UseBiasedLocking) {
 180     const int alignment = markOopDesc::biased_lock_alignment;
 181     size_t aligned_size = size + (alignment - sizeof(intptr_t));
 182     void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
 183                                           : AllocateHeap(aligned_size, flags, CURRENT_PC,
 184                                                          AllocFailStrategy::RETURN_NULL);
 185     void* aligned_addr     = align_up(real_malloc_addr, alignment);
 186     assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
 187            ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
 188            "JavaThread alignment code overflowed allocated storage");
 189     if (aligned_addr != real_malloc_addr) {
 190       log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
 191                               p2i(real_malloc_addr),
 192                               p2i(aligned_addr));
 193     }
 194     ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
 195     return aligned_addr;
 196   } else {
 197     return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
 198                        : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
 199   }
 200 }
 201 
 202 void Thread::operator delete(void* p) {
 203   if (UseBiasedLocking) {
 204     FreeHeap(((Thread*) p)->_real_malloc_address);
 205   } else {
 206     FreeHeap(p);
 207   }
 208 }
 209 
 210 void JavaThread::smr_delete() {
 211   if (_on_thread_list) {
 212     ThreadsSMRSupport::smr_delete(this);
 213   } else {
 214     delete this;
 215   }
 216 }
 217 
 218 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
 219 // JavaThread
 220 
 221 
 222 Thread::Thread() {
 223   // stack and get_thread
 224   set_stack_base(NULL);
 225   set_stack_size(0);
 226   set_self_raw_id(0);
 227   set_lgrp_id(-1);
 228   DEBUG_ONLY(clear_suspendible_thread();)
 229 
 230   // allocated data structures
 231   set_osthread(NULL);
 232   set_resource_area(new (mtThread)ResourceArea());
 233   DEBUG_ONLY(_current_resource_mark = NULL;)
 234   set_handle_area(new (mtThread) HandleArea(NULL));
 235   set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
 236   set_active_handles(NULL);
 237   set_free_handle_block(NULL);
 238   set_last_handle_mark(NULL);
 239 
 240   // This initial value ==> never claimed.
 241   _oops_do_parity = 0;
 242   _threads_hazard_ptr = NULL;
 243   _nested_threads_hazard_ptr = NULL;
 244   _nested_threads_hazard_ptr_cnt = 0;
 245 
 246   // the handle mark links itself to last_handle_mark
 247   new HandleMark(this);
 248 
 249   // plain initialization
 250   debug_only(_owned_locks = NULL;)
 251   debug_only(_allow_allocation_count = 0;)
 252   NOT_PRODUCT(_allow_safepoint_count = 0;)
 253   NOT_PRODUCT(_skip_gcalot = false;)
 254   _jvmti_env_iteration_count = 0;
 255   set_allocated_bytes(0);
 256   _vm_operation_started_count = 0;
 257   _vm_operation_completed_count = 0;
 258   _current_pending_monitor = NULL;
 259   _current_pending_monitor_is_from_java = true;
 260   _current_waiting_monitor = NULL;
 261   _num_nested_signal = 0;
 262   omFreeList = NULL;
 263   omFreeCount = 0;
 264   omFreeProvision = 32;
 265   omInUseList = NULL;
 266   omInUseCount = 0;
 267 
 268 #ifdef ASSERT
 269   _visited_for_critical_count = false;
 270 #endif
 271 
 272   _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
 273                          Monitor::_safepoint_check_sometimes);
 274   _suspend_flags = 0;
 275 
 276   // thread-specific hashCode stream generator state - Marsaglia shift-xor form
 277   _hashStateX = os::random();
 278   _hashStateY = 842502087;
 279   _hashStateZ = 0x8767;    // (int)(3579807591LL & 0xffff) ;
 280   _hashStateW = 273326509;
 281 
 282   _OnTrap   = 0;
 283   _schedctl = NULL;
 284   _Stalled  = 0;
 285   _TypeTag  = 0x2BAD;
 286 
 287   // Many of the following fields are effectively final - immutable
 288   // Note that nascent threads can't use the Native Monitor-Mutex
 289   // construct until the _MutexEvent is initialized ...
 290   // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
 291   // we might instead use a stack of ParkEvents that we could provision on-demand.
 292   // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
 293   // and ::Release()
 294   _ParkEvent   = ParkEvent::Allocate(this);
 295   _SleepEvent  = ParkEvent::Allocate(this);
 296   _MutexEvent  = ParkEvent::Allocate(this);
 297   _MuxEvent    = ParkEvent::Allocate(this);
 298 
 299 #ifdef CHECK_UNHANDLED_OOPS
 300   if (CheckUnhandledOops) {
 301     _unhandled_oops = new UnhandledOops(this);
 302   }
 303 #endif // CHECK_UNHANDLED_OOPS
 304 #ifdef ASSERT
 305   if (UseBiasedLocking) {
 306     assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
 307     assert(this == _real_malloc_address ||
 308            this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment),
 309            "bug in forced alignment of thread objects");
 310   }
 311 #endif // ASSERT
 312 }
 313 
 314 void Thread::initialize_thread_current() {
 315 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 316   assert(_thr_current == NULL, "Thread::current already initialized");
 317   _thr_current = this;
 318 #endif
 319   assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
 320   ThreadLocalStorage::set_thread(this);
 321   assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
 322 }
 323 
 324 void Thread::clear_thread_current() {
 325   assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
 326 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 327   _thr_current = NULL;
 328 #endif
 329   ThreadLocalStorage::set_thread(NULL);
 330 }
 331 
 332 void Thread::record_stack_base_and_size() {
 333   set_stack_base(os::current_stack_base());
 334   set_stack_size(os::current_stack_size());
 335   // CR 7190089: on Solaris, primordial thread's stack is adjusted
 336   // in initialize_thread(). Without the adjustment, stack size is
 337   // incorrect if stack is set to unlimited (ulimit -s unlimited).
 338   // So far, only Solaris has real implementation of initialize_thread().
 339   //
 340   // set up any platform-specific state.
 341   os::initialize_thread(this);
 342 
 343   // Set stack limits after thread is initialized.
 344   if (is_Java_thread()) {
 345     ((JavaThread*) this)->set_stack_overflow_limit();
 346     ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
 347   }
 348 #if INCLUDE_NMT
 349   // record thread's native stack, stack grows downward
 350   MemTracker::record_thread_stack(stack_end(), stack_size());
 351 #endif // INCLUDE_NMT
 352   log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
 353     PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
 354     os::current_thread_id(), p2i(stack_base() - stack_size()),
 355     p2i(stack_base()), stack_size()/1024);
 356 }
 357 
 358 
 359 Thread::~Thread() {
 360   EVENT_THREAD_DESTRUCT(this);
 361 
 362   // stack_base can be NULL if the thread is never started or exited before
 363   // record_stack_base_and_size called. Although, we would like to ensure
 364   // that all started threads do call record_stack_base_and_size(), there is
 365   // not proper way to enforce that.
 366 #if INCLUDE_NMT
 367   if (_stack_base != NULL) {
 368     MemTracker::release_thread_stack(stack_end(), stack_size());
 369 #ifdef ASSERT
 370     set_stack_base(NULL);
 371 #endif
 372   }
 373 #endif // INCLUDE_NMT
 374 
 375   // deallocate data structures
 376   delete resource_area();
 377   // since the handle marks are using the handle area, we have to deallocated the root
 378   // handle mark before deallocating the thread's handle area,
 379   assert(last_handle_mark() != NULL, "check we have an element");
 380   delete last_handle_mark();
 381   assert(last_handle_mark() == NULL, "check we have reached the end");
 382 
 383   // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
 384   // We NULL out the fields for good hygiene.
 385   ParkEvent::Release(_ParkEvent); _ParkEvent   = NULL;
 386   ParkEvent::Release(_SleepEvent); _SleepEvent  = NULL;
 387   ParkEvent::Release(_MutexEvent); _MutexEvent  = NULL;
 388   ParkEvent::Release(_MuxEvent); _MuxEvent    = NULL;
 389 
 390   delete handle_area();
 391   delete metadata_handles();
 392 
 393   // SR_handler uses this as a termination indicator -
 394   // needs to happen before os::free_thread()
 395   delete _SR_lock;
 396   _SR_lock = NULL;
 397 
 398   // osthread() can be NULL, if creation of thread failed.
 399   if (osthread() != NULL) os::free_thread(osthread());
 400 
 401   // clear Thread::current if thread is deleting itself.
 402   // Needed to ensure JNI correctly detects non-attached threads.
 403   if (this == Thread::current()) {
 404     clear_thread_current();
 405   }
 406 
 407   CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
 408 }
 409 
 410 // NOTE: dummy function for assertion purpose.
 411 void Thread::run() {
 412   ShouldNotReachHere();
 413 }
 414 
 415 #ifdef ASSERT
 416 // A JavaThread is considered "dangling" if it is not the current
 417 // thread, has been added the Threads list, the system is not at a
 418 // safepoint and the Thread is not "protected".
 419 //
 420 void Thread::check_for_dangling_thread_pointer(Thread *thread) {
 421   assert(!thread->is_Java_thread() || Thread::current() == thread ||
 422          !((JavaThread *) thread)->on_thread_list() ||
 423          SafepointSynchronize::is_at_safepoint() ||
 424          ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread),
 425          "possibility of dangling Thread pointer");
 426 }
 427 #endif
 428 
 429 ThreadPriority Thread::get_priority(const Thread* const thread) {
 430   ThreadPriority priority;
 431   // Can return an error!
 432   (void)os::get_priority(thread, priority);
 433   assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
 434   return priority;
 435 }
 436 
 437 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
 438   debug_only(check_for_dangling_thread_pointer(thread);)
 439   // Can return an error!
 440   (void)os::set_priority(thread, priority);
 441 }
 442 
 443 
 444 void Thread::start(Thread* thread) {
 445   // Start is different from resume in that its safety is guaranteed by context or
 446   // being called from a Java method synchronized on the Thread object.
 447   if (!DisableStartThread) {
 448     if (thread->is_Java_thread()) {
 449       // Initialize the thread state to RUNNABLE before starting this thread.
 450       // Can not set it after the thread started because we do not know the
 451       // exact thread state at that time. It could be in MONITOR_WAIT or
 452       // in SLEEPING or some other state.
 453       java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
 454                                           java_lang_Thread::RUNNABLE);
 455     }
 456     os::start_thread(thread);
 457   }
 458 }
 459 
 460 // Enqueue a VM_Operation to do the job for us - sometime later
 461 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
 462   VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
 463   VMThread::execute(vm_stop);
 464 }
 465 
 466 
 467 // Check if an external suspend request has completed (or has been
 468 // cancelled). Returns true if the thread is externally suspended and
 469 // false otherwise.
 470 //
 471 // The bits parameter returns information about the code path through
 472 // the routine. Useful for debugging:
 473 //
 474 // set in is_ext_suspend_completed():
 475 // 0x00000001 - routine was entered
 476 // 0x00000010 - routine return false at end
 477 // 0x00000100 - thread exited (return false)
 478 // 0x00000200 - suspend request cancelled (return false)
 479 // 0x00000400 - thread suspended (return true)
 480 // 0x00001000 - thread is in a suspend equivalent state (return true)
 481 // 0x00002000 - thread is native and walkable (return true)
 482 // 0x00004000 - thread is native_trans and walkable (needed retry)
 483 //
 484 // set in wait_for_ext_suspend_completion():
 485 // 0x00010000 - routine was entered
 486 // 0x00020000 - suspend request cancelled before loop (return false)
 487 // 0x00040000 - thread suspended before loop (return true)
 488 // 0x00080000 - suspend request cancelled in loop (return false)
 489 // 0x00100000 - thread suspended in loop (return true)
 490 // 0x00200000 - suspend not completed during retry loop (return false)
 491 
 492 // Helper class for tracing suspend wait debug bits.
 493 //
 494 // 0x00000100 indicates that the target thread exited before it could
 495 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
 496 // 0x00080000 each indicate a cancelled suspend request so they don't
 497 // count as wait failures either.
 498 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
 499 
 500 class TraceSuspendDebugBits : public StackObj {
 501  private:
 502   JavaThread * jt;
 503   bool         is_wait;
 504   bool         called_by_wait;  // meaningful when !is_wait
 505   uint32_t *   bits;
 506 
 507  public:
 508   TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
 509                         uint32_t *_bits) {
 510     jt             = _jt;
 511     is_wait        = _is_wait;
 512     called_by_wait = _called_by_wait;
 513     bits           = _bits;
 514   }
 515 
 516   ~TraceSuspendDebugBits() {
 517     if (!is_wait) {
 518 #if 1
 519       // By default, don't trace bits for is_ext_suspend_completed() calls.
 520       // That trace is very chatty.
 521       return;
 522 #else
 523       if (!called_by_wait) {
 524         // If tracing for is_ext_suspend_completed() is enabled, then only
 525         // trace calls to it from wait_for_ext_suspend_completion()
 526         return;
 527       }
 528 #endif
 529     }
 530 
 531     if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
 532       if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
 533         MutexLocker ml(Threads_lock);  // needed for get_thread_name()
 534         ResourceMark rm;
 535 
 536         tty->print_cr(
 537                       "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
 538                       jt->get_thread_name(), *bits);
 539 
 540         guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
 541       }
 542     }
 543   }
 544 };
 545 #undef DEBUG_FALSE_BITS
 546 
 547 
 548 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
 549                                           uint32_t *bits) {
 550   TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
 551 
 552   bool did_trans_retry = false;  // only do thread_in_native_trans retry once
 553   bool do_trans_retry;           // flag to force the retry
 554 
 555   *bits |= 0x00000001;
 556 
 557   do {
 558     do_trans_retry = false;
 559 
 560     if (is_exiting()) {
 561       // Thread is in the process of exiting. This is always checked
 562       // first to reduce the risk of dereferencing a freed JavaThread.
 563       *bits |= 0x00000100;
 564       return false;
 565     }
 566 
 567     if (!is_external_suspend()) {
 568       // Suspend request is cancelled. This is always checked before
 569       // is_ext_suspended() to reduce the risk of a rogue resume
 570       // confusing the thread that made the suspend request.
 571       *bits |= 0x00000200;
 572       return false;
 573     }
 574 
 575     if (is_ext_suspended()) {
 576       // thread is suspended
 577       *bits |= 0x00000400;
 578       return true;
 579     }
 580 
 581     // Now that we no longer do hard suspends of threads running
 582     // native code, the target thread can be changing thread state
 583     // while we are in this routine:
 584     //
 585     //   _thread_in_native -> _thread_in_native_trans -> _thread_blocked
 586     //
 587     // We save a copy of the thread state as observed at this moment
 588     // and make our decision about suspend completeness based on the
 589     // copy. This closes the race where the thread state is seen as
 590     // _thread_in_native_trans in the if-thread_blocked check, but is
 591     // seen as _thread_blocked in if-thread_in_native_trans check.
 592     JavaThreadState save_state = thread_state();
 593 
 594     if (save_state == _thread_blocked && is_suspend_equivalent()) {
 595       // If the thread's state is _thread_blocked and this blocking
 596       // condition is known to be equivalent to a suspend, then we can
 597       // consider the thread to be externally suspended. This means that
 598       // the code that sets _thread_blocked has been modified to do
 599       // self-suspension if the blocking condition releases. We also
 600       // used to check for CONDVAR_WAIT here, but that is now covered by
 601       // the _thread_blocked with self-suspension check.
 602       //
 603       // Return true since we wouldn't be here unless there was still an
 604       // external suspend request.
 605       *bits |= 0x00001000;
 606       return true;
 607     } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
 608       // Threads running native code will self-suspend on native==>VM/Java
 609       // transitions. If its stack is walkable (should always be the case
 610       // unless this function is called before the actual java_suspend()
 611       // call), then the wait is done.
 612       *bits |= 0x00002000;
 613       return true;
 614     } else if (!called_by_wait && !did_trans_retry &&
 615                save_state == _thread_in_native_trans &&
 616                frame_anchor()->walkable()) {
 617       // The thread is transitioning from thread_in_native to another
 618       // thread state. check_safepoint_and_suspend_for_native_trans()
 619       // will force the thread to self-suspend. If it hasn't gotten
 620       // there yet we may have caught the thread in-between the native
 621       // code check above and the self-suspend. Lucky us. If we were
 622       // called by wait_for_ext_suspend_completion(), then it
 623       // will be doing the retries so we don't have to.
 624       //
 625       // Since we use the saved thread state in the if-statement above,
 626       // there is a chance that the thread has already transitioned to
 627       // _thread_blocked by the time we get here. In that case, we will
 628       // make a single unnecessary pass through the logic below. This
 629       // doesn't hurt anything since we still do the trans retry.
 630 
 631       *bits |= 0x00004000;
 632 
 633       // Once the thread leaves thread_in_native_trans for another
 634       // thread state, we break out of this retry loop. We shouldn't
 635       // need this flag to prevent us from getting back here, but
 636       // sometimes paranoia is good.
 637       did_trans_retry = true;
 638 
 639       // We wait for the thread to transition to a more usable state.
 640       for (int i = 1; i <= SuspendRetryCount; i++) {
 641         // We used to do an "os::yield_all(i)" call here with the intention
 642         // that yielding would increase on each retry. However, the parameter
 643         // is ignored on Linux which means the yield didn't scale up. Waiting
 644         // on the SR_lock below provides a much more predictable scale up for
 645         // the delay. It also provides a simple/direct point to check for any
 646         // safepoint requests from the VMThread
 647 
 648         // temporarily drops SR_lock while doing wait with safepoint check
 649         // (if we're a JavaThread - the WatcherThread can also call this)
 650         // and increase delay with each retry
 651         SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 652 
 653         // check the actual thread state instead of what we saved above
 654         if (thread_state() != _thread_in_native_trans) {
 655           // the thread has transitioned to another thread state so
 656           // try all the checks (except this one) one more time.
 657           do_trans_retry = true;
 658           break;
 659         }
 660       } // end retry loop
 661 
 662 
 663     }
 664   } while (do_trans_retry);
 665 
 666   *bits |= 0x00000010;
 667   return false;
 668 }
 669 
 670 // Wait for an external suspend request to complete (or be cancelled).
 671 // Returns true if the thread is externally suspended and false otherwise.
 672 //
 673 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
 674                                                  uint32_t *bits) {
 675   TraceSuspendDebugBits tsdb(this, true /* is_wait */,
 676                              false /* !called_by_wait */, bits);
 677 
 678   // local flag copies to minimize SR_lock hold time
 679   bool is_suspended;
 680   bool pending;
 681   uint32_t reset_bits;
 682 
 683   // set a marker so is_ext_suspend_completed() knows we are the caller
 684   *bits |= 0x00010000;
 685 
 686   // We use reset_bits to reinitialize the bits value at the top of
 687   // each retry loop. This allows the caller to make use of any
 688   // unused bits for their own marking purposes.
 689   reset_bits = *bits;
 690 
 691   {
 692     MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
 693     is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 694                                             delay, bits);
 695     pending = is_external_suspend();
 696   }
 697   // must release SR_lock to allow suspension to complete
 698 
 699   if (!pending) {
 700     // A cancelled suspend request is the only false return from
 701     // is_ext_suspend_completed() that keeps us from entering the
 702     // retry loop.
 703     *bits |= 0x00020000;
 704     return false;
 705   }
 706 
 707   if (is_suspended) {
 708     *bits |= 0x00040000;
 709     return true;
 710   }
 711 
 712   for (int i = 1; i <= retries; i++) {
 713     *bits = reset_bits;  // reinit to only track last retry
 714 
 715     // We used to do an "os::yield_all(i)" call here with the intention
 716     // that yielding would increase on each retry. However, the parameter
 717     // is ignored on Linux which means the yield didn't scale up. Waiting
 718     // on the SR_lock below provides a much more predictable scale up for
 719     // the delay. It also provides a simple/direct point to check for any
 720     // safepoint requests from the VMThread
 721 
 722     {
 723       MutexLocker ml(SR_lock());
 724       // wait with safepoint check (if we're a JavaThread - the WatcherThread
 725       // can also call this)  and increase delay with each retry
 726       SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 727 
 728       is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 729                                               delay, bits);
 730 
 731       // It is possible for the external suspend request to be cancelled
 732       // (by a resume) before the actual suspend operation is completed.
 733       // Refresh our local copy to see if we still need to wait.
 734       pending = is_external_suspend();
 735     }
 736 
 737     if (!pending) {
 738       // A cancelled suspend request is the only false return from
 739       // is_ext_suspend_completed() that keeps us from staying in the
 740       // retry loop.
 741       *bits |= 0x00080000;
 742       return false;
 743     }
 744 
 745     if (is_suspended) {
 746       *bits |= 0x00100000;
 747       return true;
 748     }
 749   } // end retry loop
 750 
 751   // thread did not suspend after all our retries
 752   *bits |= 0x00200000;
 753   return false;
 754 }
 755 
 756 // Called from API entry points which perform stack walking. If the
 757 // associated JavaThread is the current thread, then wait_for_suspend
 758 // is not used. Otherwise, it determines if we should wait for the
 759 // "other" thread to complete external suspension. (NOTE: in future
 760 // releases the suspension mechanism should be reimplemented so this
 761 // is not necessary.)
 762 //
 763 bool
 764 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) {
 765   if (this != JavaThread::current()) {
 766     // "other" threads require special handling.
 767     if (wait_for_suspend) {
 768       // We are allowed to wait for the external suspend to complete
 769       // so give the other thread a chance to get suspended.
 770       if (!wait_for_ext_suspend_completion(SuspendRetryCount,
 771                                            SuspendRetryDelay, bits)) {
 772         // Didn't make it so let the caller know.
 773         return false;
 774       }
 775     }
 776     // We aren't allowed to wait for the external suspend to complete
 777     // so if the other thread isn't externally suspended we need to
 778     // let the caller know.
 779     else if (!is_ext_suspend_completed_with_lock(bits)) {
 780       return false;
 781     }
 782   }
 783 
 784   return true;
 785 }
 786 
 787 #ifndef PRODUCT
 788 void JavaThread::record_jump(address target, address instr, const char* file,
 789                              int line) {
 790 
 791   // This should not need to be atomic as the only way for simultaneous
 792   // updates is via interrupts. Even then this should be rare or non-existent
 793   // and we don't care that much anyway.
 794 
 795   int index = _jmp_ring_index;
 796   _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
 797   _jmp_ring[index]._target = (intptr_t) target;
 798   _jmp_ring[index]._instruction = (intptr_t) instr;
 799   _jmp_ring[index]._file = file;
 800   _jmp_ring[index]._line = line;
 801 }
 802 #endif // PRODUCT
 803 
 804 void Thread::interrupt(Thread* thread) {
 805   debug_only(check_for_dangling_thread_pointer(thread);)
 806   os::interrupt(thread);
 807 }
 808 
 809 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
 810   debug_only(check_for_dangling_thread_pointer(thread);)
 811   // Note:  If clear_interrupted==false, this simply fetches and
 812   // returns the value of the field osthread()->interrupted().
 813   return os::is_interrupted(thread, clear_interrupted);
 814 }
 815 
 816 
 817 // GC Support
 818 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
 819   int thread_parity = _oops_do_parity;
 820   if (thread_parity != strong_roots_parity) {
 821     jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
 822     if (res == thread_parity) {
 823       return true;
 824     } else {
 825       guarantee(res == strong_roots_parity, "Or else what?");
 826       return false;
 827     }
 828   }
 829   return false;
 830 }
 831 
 832 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
 833   active_handles()->oops_do(f);
 834   // Do oop for ThreadShadow
 835   f->do_oop((oop*)&_pending_exception);
 836   handle_area()->oops_do(f);
 837 
 838   if (MonitorInUseLists) {
 839     // When using thread local monitor lists, we scan them here,
 840     // and the remaining global monitors in ObjectSynchronizer::oops_do().
 841     ObjectSynchronizer::thread_local_used_oops_do(this, f);
 842   }
 843 }
 844 
 845 void Thread::metadata_handles_do(void f(Metadata*)) {
 846   // Only walk the Handles in Thread.
 847   if (metadata_handles() != NULL) {
 848     for (int i = 0; i< metadata_handles()->length(); i++) {
 849       f(metadata_handles()->at(i));
 850     }
 851   }
 852 }
 853 
 854 void Thread::print_on(outputStream* st) const {
 855   // get_priority assumes osthread initialized
 856   if (osthread() != NULL) {
 857     int os_prio;
 858     if (os::get_native_priority(this, &os_prio) == OS_OK) {
 859       st->print("os_prio=%d ", os_prio);
 860     }
 861     st->print("tid=" INTPTR_FORMAT " ", p2i(this));
 862     osthread()->print_on(st);
 863   }
 864   if (_threads_hazard_ptr != NULL) {
 865     st->print("_threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr));
 866   }
 867   if (_nested_threads_hazard_ptr != NULL) {
 868     print_nested_threads_hazard_ptrs_on(st);
 869   }
 870   st->print(" ");
 871   debug_only(if (WizardMode) print_owned_locks_on(st);)
 872 }
 873 
 874 void Thread::print_nested_threads_hazard_ptrs_on(outputStream* st) const {
 875   assert(_nested_threads_hazard_ptr != NULL, "must be set to print");
 876 
 877   if (EnableThreadSMRStatistics) {
 878     st->print(", _nested_threads_hazard_ptr_cnt=%u", _nested_threads_hazard_ptr_cnt);
 879   }
 880   st->print(", _nested_threads_hazard_ptrs=");
 881   for (NestedThreadsList* node = _nested_threads_hazard_ptr; node != NULL;
 882        node = node->next()) {
 883     if (node != _nested_threads_hazard_ptr) {
 884       // First node does not need a comma-space separator.
 885       st->print(", ");
 886     }
 887     st->print(INTPTR_FORMAT, p2i(node->t_list()));
 888   }
 889 }
 890 
 891 // Thread::print_on_error() is called by fatal error handler. Don't use
 892 // any lock or allocate memory.
 893 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
 894   assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
 895 
 896   if (is_VM_thread())                 { st->print("VMThread"); }
 897   else if (is_GC_task_thread())       { st->print("GCTaskThread"); }
 898   else if (is_Watcher_thread())       { st->print("WatcherThread"); }
 899   else if (is_ConcurrentGC_thread())  { st->print("ConcurrentGCThread"); }
 900   else                                { st->print("Thread"); }
 901 
 902   if (is_Named_thread()) {
 903     st->print(" \"%s\"", name());
 904   }
 905 
 906   st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
 907             p2i(stack_end()), p2i(stack_base()));
 908 
 909   if (osthread()) {
 910     st->print(" [id=%d]", osthread()->thread_id());
 911   }
 912 
 913   if (_threads_hazard_ptr != NULL) {
 914     st->print(" _threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr));
 915   }
 916   if (_nested_threads_hazard_ptr != NULL) {
 917     print_nested_threads_hazard_ptrs_on(st);
 918   }
 919 }
 920 
 921 void Thread::print_value_on(outputStream* st) const {
 922   if (is_Named_thread()) {
 923     st->print(" \"%s\" ", name());
 924   }
 925   st->print(INTPTR_FORMAT, p2i(this));   // print address
 926 }
 927 
 928 #ifdef ASSERT
 929 void Thread::print_owned_locks_on(outputStream* st) const {
 930   Monitor *cur = _owned_locks;
 931   if (cur == NULL) {
 932     st->print(" (no locks) ");
 933   } else {
 934     st->print_cr(" Locks owned:");
 935     while (cur) {
 936       cur->print_on(st);
 937       cur = cur->next();
 938     }
 939   }
 940 }
 941 
 942 static int ref_use_count  = 0;
 943 
 944 bool Thread::owns_locks_but_compiled_lock() const {
 945   for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 946     if (cur != Compile_lock) return true;
 947   }
 948   return false;
 949 }
 950 
 951 
 952 #endif
 953 
 954 #ifndef PRODUCT
 955 
 956 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially
 957 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that
 958 // no threads which allow_vm_block's are held
 959 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
 960   // Check if current thread is allowed to block at a safepoint
 961   if (!(_allow_safepoint_count == 0)) {
 962     fatal("Possible safepoint reached by thread that does not allow it");
 963   }
 964   if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
 965     fatal("LEAF method calling lock?");
 966   }
 967 
 968 #ifdef ASSERT
 969   if (potential_vm_operation && is_Java_thread()
 970       && !Universe::is_bootstrapping()) {
 971     // Make sure we do not hold any locks that the VM thread also uses.
 972     // This could potentially lead to deadlocks
 973     for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 974       // Threads_lock is special, since the safepoint synchronization will not start before this is
 975       // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
 976       // since it is used to transfer control between JavaThreads and the VMThread
 977       // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
 978       if ((cur->allow_vm_block() &&
 979            cur != Threads_lock &&
 980            cur != Compile_lock &&               // Temporary: should not be necessary when we get separate compilation
 981            cur != VMOperationRequest_lock &&
 982            cur != VMOperationQueue_lock) ||
 983            cur->rank() == Mutex::special) {
 984         fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
 985       }
 986     }
 987   }
 988 
 989   if (GCALotAtAllSafepoints) {
 990     // We could enter a safepoint here and thus have a gc
 991     InterfaceSupport::check_gc_alot();
 992   }
 993 #endif
 994 }
 995 #endif
 996 
 997 bool Thread::is_in_stack(address adr) const {
 998   assert(Thread::current() == this, "is_in_stack can only be called from current thread");
 999   address end = os::current_stack_pointer();
1000   // Allow non Java threads to call this without stack_base
1001   if (_stack_base == NULL) return true;
1002   if (stack_base() >= adr && adr >= end) return true;
1003 
1004   return false;
1005 }
1006 
1007 bool Thread::is_in_usable_stack(address adr) const {
1008   size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
1009   size_t usable_stack_size = _stack_size - stack_guard_size;
1010 
1011   return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
1012 }
1013 
1014 
1015 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
1016 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
1017 // used for compilation in the future. If that change is made, the need for these methods
1018 // should be revisited, and they should be removed if possible.
1019 
1020 bool Thread::is_lock_owned(address adr) const {
1021   return on_local_stack(adr);
1022 }
1023 
1024 bool Thread::set_as_starting_thread() {
1025   // NOTE: this must be called inside the main thread.
1026   return os::create_main_thread((JavaThread*)this);
1027 }
1028 
1029 static void initialize_class(Symbol* class_name, TRAPS) {
1030   Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
1031   InstanceKlass::cast(klass)->initialize(CHECK);
1032 }
1033 
1034 
1035 // Creates the initial ThreadGroup
1036 static Handle create_initial_thread_group(TRAPS) {
1037   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
1038   InstanceKlass* ik = InstanceKlass::cast(k);
1039 
1040   Handle system_instance = ik->allocate_instance_handle(CHECK_NH);
1041   {
1042     JavaValue result(T_VOID);
1043     JavaCalls::call_special(&result,
1044                             system_instance,
1045                             ik,
1046                             vmSymbols::object_initializer_name(),
1047                             vmSymbols::void_method_signature(),
1048                             CHECK_NH);
1049   }
1050   Universe::set_system_thread_group(system_instance());
1051 
1052   Handle main_instance = ik->allocate_instance_handle(CHECK_NH);
1053   {
1054     JavaValue result(T_VOID);
1055     Handle string = java_lang_String::create_from_str("main", CHECK_NH);
1056     JavaCalls::call_special(&result,
1057                             main_instance,
1058                             ik,
1059                             vmSymbols::object_initializer_name(),
1060                             vmSymbols::threadgroup_string_void_signature(),
1061                             system_instance,
1062                             string,
1063                             CHECK_NH);
1064   }
1065   return main_instance;
1066 }
1067 
1068 // Creates the initial Thread
1069 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
1070                                  TRAPS) {
1071   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
1072   InstanceKlass* ik = InstanceKlass::cast(k);
1073   instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
1074 
1075   java_lang_Thread::set_thread(thread_oop(), thread);
1076   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1077   thread->set_threadObj(thread_oop());
1078 
1079   Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1080 
1081   JavaValue result(T_VOID);
1082   JavaCalls::call_special(&result, thread_oop,
1083                           ik,
1084                           vmSymbols::object_initializer_name(),
1085                           vmSymbols::threadgroup_string_void_signature(),
1086                           thread_group,
1087                           string,
1088                           CHECK_NULL);
1089   return thread_oop();
1090 }
1091 
1092 char java_runtime_name[128] = "";
1093 char java_runtime_version[128] = "";
1094 
1095 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1096 static const char* get_java_runtime_name(TRAPS) {
1097   Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1098                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1099   fieldDescriptor fd;
1100   bool found = k != NULL &&
1101                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1102                                                         vmSymbols::string_signature(), &fd);
1103   if (found) {
1104     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1105     if (name_oop == NULL) {
1106       return NULL;
1107     }
1108     const char* name = java_lang_String::as_utf8_string(name_oop,
1109                                                         java_runtime_name,
1110                                                         sizeof(java_runtime_name));
1111     return name;
1112   } else {
1113     return NULL;
1114   }
1115 }
1116 
1117 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1118 static const char* get_java_runtime_version(TRAPS) {
1119   Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1120                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1121   fieldDescriptor fd;
1122   bool found = k != NULL &&
1123                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1124                                                         vmSymbols::string_signature(), &fd);
1125   if (found) {
1126     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1127     if (name_oop == NULL) {
1128       return NULL;
1129     }
1130     const char* name = java_lang_String::as_utf8_string(name_oop,
1131                                                         java_runtime_version,
1132                                                         sizeof(java_runtime_version));
1133     return name;
1134   } else {
1135     return NULL;
1136   }
1137 }
1138 
1139 // General purpose hook into Java code, run once when the VM is initialized.
1140 // The Java library method itself may be changed independently from the VM.
1141 static void call_postVMInitHook(TRAPS) {
1142   Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1143   if (klass != NULL) {
1144     JavaValue result(T_VOID);
1145     JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1146                            vmSymbols::void_method_signature(),
1147                            CHECK);
1148   }
1149 }
1150 
1151 static void reset_vm_info_property(TRAPS) {
1152   // the vm info string
1153   ResourceMark rm(THREAD);
1154   const char *vm_info = VM_Version::vm_info_string();
1155 
1156   // java.lang.System class
1157   Klass* klass =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1158 
1159   // setProperty arguments
1160   Handle key_str    = java_lang_String::create_from_str("java.vm.info", CHECK);
1161   Handle value_str  = java_lang_String::create_from_str(vm_info, CHECK);
1162 
1163   // return value
1164   JavaValue r(T_OBJECT);
1165 
1166   // public static String setProperty(String key, String value);
1167   JavaCalls::call_static(&r,
1168                          klass,
1169                          vmSymbols::setProperty_name(),
1170                          vmSymbols::string_string_string_signature(),
1171                          key_str,
1172                          value_str,
1173                          CHECK);
1174 }
1175 
1176 
1177 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1178                                     bool daemon, TRAPS) {
1179   assert(thread_group.not_null(), "thread group should be specified");
1180   assert(threadObj() == NULL, "should only create Java thread object once");
1181 
1182   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1183   InstanceKlass* ik = InstanceKlass::cast(k);
1184   instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1185 
1186   java_lang_Thread::set_thread(thread_oop(), this);
1187   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1188   set_threadObj(thread_oop());
1189 
1190   JavaValue result(T_VOID);
1191   if (thread_name != NULL) {
1192     Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1193     // Thread gets assigned specified name and null target
1194     JavaCalls::call_special(&result,
1195                             thread_oop,
1196                             ik,
1197                             vmSymbols::object_initializer_name(),
1198                             vmSymbols::threadgroup_string_void_signature(),
1199                             thread_group, // Argument 1
1200                             name,         // Argument 2
1201                             THREAD);
1202   } else {
1203     // Thread gets assigned name "Thread-nnn" and null target
1204     // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1205     JavaCalls::call_special(&result,
1206                             thread_oop,
1207                             ik,
1208                             vmSymbols::object_initializer_name(),
1209                             vmSymbols::threadgroup_runnable_void_signature(),
1210                             thread_group, // Argument 1
1211                             Handle(),     // Argument 2
1212                             THREAD);
1213   }
1214 
1215 
1216   if (daemon) {
1217     java_lang_Thread::set_daemon(thread_oop());
1218   }
1219 
1220   if (HAS_PENDING_EXCEPTION) {
1221     return;
1222   }
1223 
1224   Klass* group =  SystemDictionary::ThreadGroup_klass();
1225   Handle threadObj(THREAD, this->threadObj());
1226 
1227   JavaCalls::call_special(&result,
1228                           thread_group,
1229                           group,
1230                           vmSymbols::add_method_name(),
1231                           vmSymbols::thread_void_signature(),
1232                           threadObj,          // Arg 1
1233                           THREAD);
1234 }
1235 
1236 // NamedThread --  non-JavaThread subclasses with multiple
1237 // uniquely named instances should derive from this.
1238 NamedThread::NamedThread() : Thread() {
1239   _name = NULL;
1240   _processed_thread = NULL;
1241   _gc_id = GCId::undefined();
1242 }
1243 
1244 NamedThread::~NamedThread() {
1245   if (_name != NULL) {
1246     FREE_C_HEAP_ARRAY(char, _name);
1247     _name = NULL;
1248   }
1249 }
1250 
1251 void NamedThread::set_name(const char* format, ...) {
1252   guarantee(_name == NULL, "Only get to set name once.");
1253   _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1254   guarantee(_name != NULL, "alloc failure");
1255   va_list ap;
1256   va_start(ap, format);
1257   jio_vsnprintf(_name, max_name_len, format, ap);
1258   va_end(ap);
1259 }
1260 
1261 void NamedThread::initialize_named_thread() {
1262   set_native_thread_name(name());
1263 }
1264 
1265 void NamedThread::print_on(outputStream* st) const {
1266   st->print("\"%s\" ", name());
1267   Thread::print_on(st);
1268   st->cr();
1269 }
1270 
1271 
1272 // ======= WatcherThread ========
1273 
1274 // The watcher thread exists to simulate timer interrupts.  It should
1275 // be replaced by an abstraction over whatever native support for
1276 // timer interrupts exists on the platform.
1277 
1278 WatcherThread* WatcherThread::_watcher_thread   = NULL;
1279 bool WatcherThread::_startable = false;
1280 volatile bool  WatcherThread::_should_terminate = false;
1281 
1282 WatcherThread::WatcherThread() : Thread() {
1283   assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1284   if (os::create_thread(this, os::watcher_thread)) {
1285     _watcher_thread = this;
1286 
1287     // Set the watcher thread to the highest OS priority which should not be
1288     // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1289     // is created. The only normal thread using this priority is the reference
1290     // handler thread, which runs for very short intervals only.
1291     // If the VMThread's priority is not lower than the WatcherThread profiling
1292     // will be inaccurate.
1293     os::set_priority(this, MaxPriority);
1294     if (!DisableStartThread) {
1295       os::start_thread(this);
1296     }
1297   }
1298 }
1299 
1300 int WatcherThread::sleep() const {
1301   // The WatcherThread does not participate in the safepoint protocol
1302   // for the PeriodicTask_lock because it is not a JavaThread.
1303   MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1304 
1305   if (_should_terminate) {
1306     // check for termination before we do any housekeeping or wait
1307     return 0;  // we did not sleep.
1308   }
1309 
1310   // remaining will be zero if there are no tasks,
1311   // causing the WatcherThread to sleep until a task is
1312   // enrolled
1313   int remaining = PeriodicTask::time_to_wait();
1314   int time_slept = 0;
1315 
1316   // we expect this to timeout - we only ever get unparked when
1317   // we should terminate or when a new task has been enrolled
1318   OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1319 
1320   jlong time_before_loop = os::javaTimeNanos();
1321 
1322   while (true) {
1323     bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1324                                             remaining);
1325     jlong now = os::javaTimeNanos();
1326 
1327     if (remaining == 0) {
1328       // if we didn't have any tasks we could have waited for a long time
1329       // consider the time_slept zero and reset time_before_loop
1330       time_slept = 0;
1331       time_before_loop = now;
1332     } else {
1333       // need to recalculate since we might have new tasks in _tasks
1334       time_slept = (int) ((now - time_before_loop) / 1000000);
1335     }
1336 
1337     // Change to task list or spurious wakeup of some kind
1338     if (timedout || _should_terminate) {
1339       break;
1340     }
1341 
1342     remaining = PeriodicTask::time_to_wait();
1343     if (remaining == 0) {
1344       // Last task was just disenrolled so loop around and wait until
1345       // another task gets enrolled
1346       continue;
1347     }
1348 
1349     remaining -= time_slept;
1350     if (remaining <= 0) {
1351       break;
1352     }
1353   }
1354 
1355   return time_slept;
1356 }
1357 
1358 void WatcherThread::run() {
1359   assert(this == watcher_thread(), "just checking");
1360 
1361   this->record_stack_base_and_size();
1362   this->set_native_thread_name(this->name());
1363   this->set_active_handles(JNIHandleBlock::allocate_block());
1364   while (true) {
1365     assert(watcher_thread() == Thread::current(), "thread consistency check");
1366     assert(watcher_thread() == this, "thread consistency check");
1367 
1368     // Calculate how long it'll be until the next PeriodicTask work
1369     // should be done, and sleep that amount of time.
1370     int time_waited = sleep();
1371 
1372     if (VMError::is_error_reported()) {
1373       // A fatal error has happened, the error handler(VMError::report_and_die)
1374       // should abort JVM after creating an error log file. However in some
1375       // rare cases, the error handler itself might deadlock. Here periodically
1376       // check for error reporting timeouts, and if it happens, just proceed to
1377       // abort the VM.
1378 
1379       // This code is in WatcherThread because WatcherThread wakes up
1380       // periodically so the fatal error handler doesn't need to do anything;
1381       // also because the WatcherThread is less likely to crash than other
1382       // threads.
1383 
1384       for (;;) {
1385         // Note: we use naked sleep in this loop because we want to avoid using
1386         // any kind of VM infrastructure which may be broken at this point.
1387         if (VMError::check_timeout()) {
1388           // We hit error reporting timeout. Error reporting was interrupted and
1389           // will be wrapping things up now (closing files etc). Give it some more
1390           // time, then quit the VM.
1391           os::naked_short_sleep(200);
1392           // Print a message to stderr.
1393           fdStream err(defaultStream::output_fd());
1394           err.print_raw_cr("# [ timer expired, abort... ]");
1395           // skip atexit/vm_exit/vm_abort hooks
1396           os::die();
1397         }
1398 
1399         // Wait a second, then recheck for timeout.
1400         os::naked_short_sleep(999);
1401       }
1402     }
1403 
1404     if (_should_terminate) {
1405       // check for termination before posting the next tick
1406       break;
1407     }
1408 
1409     PeriodicTask::real_time_tick(time_waited);
1410   }
1411 
1412   // Signal that it is terminated
1413   {
1414     MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1415     _watcher_thread = NULL;
1416     Terminator_lock->notify();
1417   }
1418 }
1419 
1420 void WatcherThread::start() {
1421   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1422 
1423   if (watcher_thread() == NULL && _startable) {
1424     _should_terminate = false;
1425     // Create the single instance of WatcherThread
1426     new WatcherThread();
1427   }
1428 }
1429 
1430 void WatcherThread::make_startable() {
1431   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1432   _startable = true;
1433 }
1434 
1435 void WatcherThread::stop() {
1436   {
1437     // Follow normal safepoint aware lock enter protocol since the
1438     // WatcherThread is stopped by another JavaThread.
1439     MutexLocker ml(PeriodicTask_lock);
1440     _should_terminate = true;
1441 
1442     WatcherThread* watcher = watcher_thread();
1443     if (watcher != NULL) {
1444       // unpark the WatcherThread so it can see that it should terminate
1445       watcher->unpark();
1446     }
1447   }
1448 
1449   MutexLocker mu(Terminator_lock);
1450 
1451   while (watcher_thread() != NULL) {
1452     // This wait should make safepoint checks, wait without a timeout,
1453     // and wait as a suspend-equivalent condition.
1454     Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1455                           Mutex::_as_suspend_equivalent_flag);
1456   }
1457 }
1458 
1459 void WatcherThread::unpark() {
1460   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1461   PeriodicTask_lock->notify();
1462 }
1463 
1464 void WatcherThread::print_on(outputStream* st) const {
1465   st->print("\"%s\" ", name());
1466   Thread::print_on(st);
1467   st->cr();
1468 }
1469 
1470 // ======= JavaThread ========
1471 
1472 #if INCLUDE_JVMCI
1473 
1474 jlong* JavaThread::_jvmci_old_thread_counters;
1475 
1476 bool jvmci_counters_include(JavaThread* thread) {
1477   oop threadObj = thread->threadObj();
1478   return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1479 }
1480 
1481 void JavaThread::collect_counters(typeArrayOop array) {
1482   if (JVMCICounterSize > 0) {
1483     MutexLocker tl(Threads_lock);
1484     JavaThreadIteratorWithHandle jtiwh;
1485     for (int i = 0; i < array->length(); i++) {
1486       array->long_at_put(i, _jvmci_old_thread_counters[i]);
1487     }
1488     for (; JavaThread *tp = jtiwh.next(); ) {
1489       if (jvmci_counters_include(tp)) {
1490         for (int i = 0; i < array->length(); i++) {
1491           array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1492         }
1493       }
1494     }
1495   }
1496 }
1497 
1498 #endif // INCLUDE_JVMCI
1499 
1500 // A JavaThread is a normal Java thread
1501 
1502 void JavaThread::initialize() {
1503   // Initialize fields
1504 
1505   set_saved_exception_pc(NULL);
1506   set_threadObj(NULL);
1507   _anchor.clear();
1508   set_entry_point(NULL);
1509   set_jni_functions(jni_functions());
1510   set_callee_target(NULL);
1511   set_vm_result(NULL);
1512   set_vm_result_2(NULL);
1513   set_vframe_array_head(NULL);
1514   set_vframe_array_last(NULL);
1515   set_deferred_locals(NULL);
1516   set_deopt_mark(NULL);
1517   set_deopt_compiled_method(NULL);
1518   clear_must_deopt_id();
1519   set_monitor_chunks(NULL);
1520   set_next(NULL);
1521   _on_thread_list = false;
1522   set_thread_state(_thread_new);
1523   _terminated = _not_terminated;
1524   _privileged_stack_top = NULL;
1525   _array_for_gc = NULL;
1526   _suspend_equivalent = false;
1527   _in_deopt_handler = 0;
1528   _doing_unsafe_access = false;
1529   _stack_guard_state = stack_guard_unused;
1530 #if INCLUDE_JVMCI
1531   _pending_monitorenter = false;
1532   _pending_deoptimization = -1;
1533   _pending_failed_speculation = NULL;
1534   _pending_transfer_to_interpreter = false;
1535   _adjusting_comp_level = false;
1536   _jvmci._alternate_call_target = NULL;
1537   assert(_jvmci._implicit_exception_pc == NULL, "must be");
1538   if (JVMCICounterSize > 0) {
1539     _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1540     memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1541   } else {
1542     _jvmci_counters = NULL;
1543   }
1544 #endif // INCLUDE_JVMCI
1545   _reserved_stack_activation = NULL;  // stack base not known yet
1546   (void)const_cast<oop&>(_exception_oop = oop(NULL));
1547   _exception_pc  = 0;
1548   _exception_handler_pc = 0;
1549   _is_method_handle_return = 0;
1550   _jvmti_thread_state= NULL;
1551   _should_post_on_exceptions_flag = JNI_FALSE;
1552   _jvmti_get_loaded_classes_closure = NULL;
1553   _interp_only_mode    = 0;
1554   _special_runtime_exit_condition = _no_async_condition;
1555   _pending_async_exception = NULL;
1556   _thread_stat = NULL;
1557   _thread_stat = new ThreadStatistics();
1558   _blocked_on_compilation = false;
1559   _jni_active_critical = 0;
1560   _pending_jni_exception_check_fn = NULL;
1561   _do_not_unlock_if_synchronized = false;
1562   _cached_monitor_info = NULL;
1563   _parker = Parker::Allocate(this);
1564 
1565 #ifndef PRODUCT
1566   _jmp_ring_index = 0;
1567   for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1568     record_jump(NULL, NULL, NULL, 0);
1569   }
1570 #endif // PRODUCT
1571 
1572   // Setup safepoint state info for this thread
1573   ThreadSafepointState::create(this);
1574 
1575   debug_only(_java_call_counter = 0);
1576 
1577   // JVMTI PopFrame support
1578   _popframe_condition = popframe_inactive;
1579   _popframe_preserved_args = NULL;
1580   _popframe_preserved_args_size = 0;
1581   _frames_to_pop_failed_realloc = 0;
1582 
1583   if (SafepointMechanism::uses_thread_local_poll()) {
1584     SafepointMechanism::initialize_header(this);
1585   }
1586 
1587   pd_initialize();
1588 }
1589 
1590 #if INCLUDE_ALL_GCS
1591 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1592 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1593 #endif // INCLUDE_ALL_GCS
1594 
1595 JavaThread::JavaThread(bool is_attaching_via_jni) :
1596                        Thread()
1597 #if INCLUDE_ALL_GCS
1598                        , _satb_mark_queue(&_satb_mark_queue_set),
1599                        _dirty_card_queue(&_dirty_card_queue_set)
1600 #endif // INCLUDE_ALL_GCS
1601 {
1602   initialize();
1603   if (is_attaching_via_jni) {
1604     _jni_attach_state = _attaching_via_jni;
1605   } else {
1606     _jni_attach_state = _not_attaching_via_jni;
1607   }
1608   assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1609 }
1610 
1611 bool JavaThread::reguard_stack(address cur_sp) {
1612   if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1613       && _stack_guard_state != stack_guard_reserved_disabled) {
1614     return true; // Stack already guarded or guard pages not needed.
1615   }
1616 
1617   if (register_stack_overflow()) {
1618     // For those architectures which have separate register and
1619     // memory stacks, we must check the register stack to see if
1620     // it has overflowed.
1621     return false;
1622   }
1623 
1624   // Java code never executes within the yellow zone: the latter is only
1625   // there to provoke an exception during stack banging.  If java code
1626   // is executing there, either StackShadowPages should be larger, or
1627   // some exception code in c1, c2 or the interpreter isn't unwinding
1628   // when it should.
1629   guarantee(cur_sp > stack_reserved_zone_base(),
1630             "not enough space to reguard - increase StackShadowPages");
1631   if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1632     enable_stack_yellow_reserved_zone();
1633     if (reserved_stack_activation() != stack_base()) {
1634       set_reserved_stack_activation(stack_base());
1635     }
1636   } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1637     set_reserved_stack_activation(stack_base());
1638     enable_stack_reserved_zone();
1639   }
1640   return true;
1641 }
1642 
1643 bool JavaThread::reguard_stack(void) {
1644   return reguard_stack(os::current_stack_pointer());
1645 }
1646 
1647 
1648 void JavaThread::block_if_vm_exited() {
1649   if (_terminated == _vm_exited) {
1650     // _vm_exited is set at safepoint, and Threads_lock is never released
1651     // we will block here forever
1652     Threads_lock->lock_without_safepoint_check();
1653     ShouldNotReachHere();
1654   }
1655 }
1656 
1657 
1658 // Remove this ifdef when C1 is ported to the compiler interface.
1659 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1660 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1661 
1662 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1663                        Thread()
1664 #if INCLUDE_ALL_GCS
1665                        , _satb_mark_queue(&_satb_mark_queue_set),
1666                        _dirty_card_queue(&_dirty_card_queue_set)
1667 #endif // INCLUDE_ALL_GCS
1668 {
1669   initialize();
1670   _jni_attach_state = _not_attaching_via_jni;
1671   set_entry_point(entry_point);
1672   // Create the native thread itself.
1673   // %note runtime_23
1674   os::ThreadType thr_type = os::java_thread;
1675   thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1676                                                      os::java_thread;
1677   os::create_thread(this, thr_type, stack_sz);
1678   // The _osthread may be NULL here because we ran out of memory (too many threads active).
1679   // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1680   // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1681   // the exception consists of creating the exception object & initializing it, initialization
1682   // will leave the VM via a JavaCall and then all locks must be unlocked).
1683   //
1684   // The thread is still suspended when we reach here. Thread must be explicit started
1685   // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1686   // by calling Threads:add. The reason why this is not done here, is because the thread
1687   // object must be fully initialized (take a look at JVM_Start)
1688 }
1689 
1690 JavaThread::~JavaThread() {
1691 
1692   // JSR166 -- return the parker to the free list
1693   Parker::Release(_parker);
1694   _parker = NULL;
1695 
1696   // Free any remaining  previous UnrollBlock
1697   vframeArray* old_array = vframe_array_last();
1698 
1699   if (old_array != NULL) {
1700     Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1701     old_array->set_unroll_block(NULL);
1702     delete old_info;
1703     delete old_array;
1704   }
1705 
1706   GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1707   if (deferred != NULL) {
1708     // This can only happen if thread is destroyed before deoptimization occurs.
1709     assert(deferred->length() != 0, "empty array!");
1710     do {
1711       jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1712       deferred->remove_at(0);
1713       // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1714       delete dlv;
1715     } while (deferred->length() != 0);
1716     delete deferred;
1717   }
1718 
1719   // All Java related clean up happens in exit
1720   ThreadSafepointState::destroy(this);
1721   if (_thread_stat != NULL) delete _thread_stat;
1722 
1723 #if INCLUDE_JVMCI
1724   if (JVMCICounterSize > 0) {
1725     if (jvmci_counters_include(this)) {
1726       for (int i = 0; i < JVMCICounterSize; i++) {
1727         _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1728       }
1729     }
1730     FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1731   }
1732 #endif // INCLUDE_JVMCI
1733 }
1734 
1735 
1736 // The first routine called by a new Java thread
1737 void JavaThread::run() {
1738   // initialize thread-local alloc buffer related fields
1739   this->initialize_tlab();
1740 
1741   // used to test validity of stack trace backs
1742   this->record_base_of_stack_pointer();
1743 
1744   // Record real stack base and size.
1745   this->record_stack_base_and_size();
1746 
1747   this->create_stack_guard_pages();
1748 
1749   this->cache_global_variables();
1750 
1751   // Thread is now sufficient initialized to be handled by the safepoint code as being
1752   // in the VM. Change thread state from _thread_new to _thread_in_vm
1753   ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1754 
1755   assert(JavaThread::current() == this, "sanity check");
1756   assert(!Thread::current()->owns_locks(), "sanity check");
1757 
1758   DTRACE_THREAD_PROBE(start, this);
1759 
1760   // This operation might block. We call that after all safepoint checks for a new thread has
1761   // been completed.
1762   this->set_active_handles(JNIHandleBlock::allocate_block());
1763 
1764   if (JvmtiExport::should_post_thread_life()) {
1765     JvmtiExport::post_thread_start(this);
1766   }
1767 
1768   EventThreadStart event;
1769   if (event.should_commit()) {
1770     event.set_thread(THREAD_TRACE_ID(this));
1771     event.commit();
1772   }
1773 
1774   // We call another function to do the rest so we are sure that the stack addresses used
1775   // from there will be lower than the stack base just computed
1776   thread_main_inner();
1777 
1778   // Note, thread is no longer valid at this point!
1779 }
1780 
1781 
1782 void JavaThread::thread_main_inner() {
1783   assert(JavaThread::current() == this, "sanity check");
1784   assert(this->threadObj() != NULL, "just checking");
1785 
1786   // Execute thread entry point unless this thread has a pending exception
1787   // or has been stopped before starting.
1788   // Note: Due to JVM_StopThread we can have pending exceptions already!
1789   if (!this->has_pending_exception() &&
1790       !java_lang_Thread::is_stillborn(this->threadObj())) {
1791     {
1792       ResourceMark rm(this);
1793       this->set_native_thread_name(this->get_thread_name());
1794     }
1795     HandleMark hm(this);
1796     this->entry_point()(this, this);
1797   }
1798 
1799   DTRACE_THREAD_PROBE(stop, this);
1800 
1801   this->exit(false);
1802   this->smr_delete();
1803 }
1804 
1805 
1806 static void ensure_join(JavaThread* thread) {
1807   // We do not need to grab the Threads_lock, since we are operating on ourself.
1808   Handle threadObj(thread, thread->threadObj());
1809   assert(threadObj.not_null(), "java thread object must exist");
1810   ObjectLocker lock(threadObj, thread);
1811   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1812   thread->clear_pending_exception();
1813   // Thread is exiting. So set thread_status field in  java.lang.Thread class to TERMINATED.
1814   java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1815   // Clear the native thread instance - this makes isAlive return false and allows the join()
1816   // to complete once we've done the notify_all below
1817   java_lang_Thread::set_thread(threadObj(), NULL);
1818   lock.notify_all(thread);
1819   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1820   thread->clear_pending_exception();
1821 }
1822 
1823 
1824 // For any new cleanup additions, please check to see if they need to be applied to
1825 // cleanup_failed_attach_current_thread as well.
1826 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1827   assert(this == JavaThread::current(), "thread consistency check");
1828 
1829   elapsedTimer _timer_exit_phase1;
1830   elapsedTimer _timer_exit_phase2;
1831   elapsedTimer _timer_exit_phase3;
1832   elapsedTimer _timer_exit_phase4;
1833 
1834   if (log_is_enabled(Debug, os, thread, timer)) {
1835     _timer_exit_phase1.start();
1836   }
1837 
1838   HandleMark hm(this);
1839   Handle uncaught_exception(this, this->pending_exception());
1840   this->clear_pending_exception();
1841   Handle threadObj(this, this->threadObj());
1842   assert(threadObj.not_null(), "Java thread object should be created");
1843 
1844   // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1845   {
1846     EXCEPTION_MARK;
1847 
1848     CLEAR_PENDING_EXCEPTION;
1849   }
1850   if (!destroy_vm) {
1851     if (uncaught_exception.not_null()) {
1852       EXCEPTION_MARK;
1853       // Call method Thread.dispatchUncaughtException().
1854       Klass* thread_klass = SystemDictionary::Thread_klass();
1855       JavaValue result(T_VOID);
1856       JavaCalls::call_virtual(&result,
1857                               threadObj, thread_klass,
1858                               vmSymbols::dispatchUncaughtException_name(),
1859                               vmSymbols::throwable_void_signature(),
1860                               uncaught_exception,
1861                               THREAD);
1862       if (HAS_PENDING_EXCEPTION) {
1863         ResourceMark rm(this);
1864         jio_fprintf(defaultStream::error_stream(),
1865                     "\nException: %s thrown from the UncaughtExceptionHandler"
1866                     " in thread \"%s\"\n",
1867                     pending_exception()->klass()->external_name(),
1868                     get_thread_name());
1869         CLEAR_PENDING_EXCEPTION;
1870       }
1871     }
1872 
1873     // Called before the java thread exit since we want to read info
1874     // from java_lang_Thread object
1875     EventThreadEnd event;
1876     if (event.should_commit()) {
1877       event.set_thread(THREAD_TRACE_ID(this));
1878       event.commit();
1879     }
1880 
1881     // Call after last event on thread
1882     EVENT_THREAD_EXIT(this);
1883 
1884     // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1885     // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1886     // is deprecated anyhow.
1887     if (!is_Compiler_thread()) {
1888       int count = 3;
1889       while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1890         EXCEPTION_MARK;
1891         JavaValue result(T_VOID);
1892         Klass* thread_klass = SystemDictionary::Thread_klass();
1893         JavaCalls::call_virtual(&result,
1894                                 threadObj, thread_klass,
1895                                 vmSymbols::exit_method_name(),
1896                                 vmSymbols::void_method_signature(),
1897                                 THREAD);
1898         CLEAR_PENDING_EXCEPTION;
1899       }
1900     }
1901     // notify JVMTI
1902     if (JvmtiExport::should_post_thread_life()) {
1903       JvmtiExport::post_thread_end(this);
1904     }
1905 
1906     // We have notified the agents that we are exiting, before we go on,
1907     // we must check for a pending external suspend request and honor it
1908     // in order to not surprise the thread that made the suspend request.
1909     while (true) {
1910       {
1911         MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1912         if (!is_external_suspend()) {
1913           set_terminated(_thread_exiting);
1914           ThreadService::current_thread_exiting(this);
1915           break;
1916         }
1917         // Implied else:
1918         // Things get a little tricky here. We have a pending external
1919         // suspend request, but we are holding the SR_lock so we
1920         // can't just self-suspend. So we temporarily drop the lock
1921         // and then self-suspend.
1922       }
1923 
1924       ThreadBlockInVM tbivm(this);
1925       java_suspend_self();
1926 
1927       // We're done with this suspend request, but we have to loop around
1928       // and check again. Eventually we will get SR_lock without a pending
1929       // external suspend request and will be able to mark ourselves as
1930       // exiting.
1931     }
1932     // no more external suspends are allowed at this point
1933   } else {
1934     // before_exit() has already posted JVMTI THREAD_END events
1935   }
1936 
1937   if (log_is_enabled(Debug, os, thread, timer)) {
1938     _timer_exit_phase1.stop();
1939     _timer_exit_phase2.start();
1940   }
1941   // Notify waiters on thread object. This has to be done after exit() is called
1942   // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1943   // group should have the destroyed bit set before waiters are notified).
1944   ensure_join(this);
1945   assert(!this->has_pending_exception(), "ensure_join should have cleared");
1946 
1947   if (log_is_enabled(Debug, os, thread, timer)) {
1948     _timer_exit_phase2.stop();
1949     _timer_exit_phase3.start();
1950   }
1951   // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1952   // held by this thread must be released. The spec does not distinguish
1953   // between JNI-acquired and regular Java monitors. We can only see
1954   // regular Java monitors here if monitor enter-exit matching is broken.
1955   //
1956   // Optionally release any monitors for regular JavaThread exits. This
1957   // is provided as a work around for any bugs in monitor enter-exit
1958   // matching. This can be expensive so it is not enabled by default.
1959   //
1960   // ensure_join() ignores IllegalThreadStateExceptions, and so does
1961   // ObjectSynchronizer::release_monitors_owned_by_thread().
1962   if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) {
1963     // Sanity check even though JNI DetachCurrentThread() would have
1964     // returned JNI_ERR if there was a Java frame. JavaThread exit
1965     // should be done executing Java code by the time we get here.
1966     assert(!this->has_last_Java_frame(),
1967            "should not have a Java frame when detaching or exiting");
1968     ObjectSynchronizer::release_monitors_owned_by_thread(this);
1969     assert(!this->has_pending_exception(), "release_monitors should have cleared");
1970   }
1971 
1972   // These things needs to be done while we are still a Java Thread. Make sure that thread
1973   // is in a consistent state, in case GC happens
1974   assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1975 
1976   if (active_handles() != NULL) {
1977     JNIHandleBlock* block = active_handles();
1978     set_active_handles(NULL);
1979     JNIHandleBlock::release_block(block);
1980   }
1981 
1982   if (free_handle_block() != NULL) {
1983     JNIHandleBlock* block = free_handle_block();
1984     set_free_handle_block(NULL);
1985     JNIHandleBlock::release_block(block);
1986   }
1987 
1988   // These have to be removed while this is still a valid thread.
1989   remove_stack_guard_pages();
1990 
1991   if (UseTLAB) {
1992     tlab().make_parsable(true);  // retire TLAB
1993   }
1994 
1995   if (JvmtiEnv::environments_might_exist()) {
1996     JvmtiExport::cleanup_thread(this);
1997   }
1998 
1999   // We must flush any deferred card marks and other various GC barrier
2000   // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer)
2001   // before removing a thread from the list of active threads.
2002   BarrierSet::barrier_set()->on_thread_detach(this);
2003 
2004   log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
2005     exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
2006     os::current_thread_id());
2007 
2008   if (log_is_enabled(Debug, os, thread, timer)) {
2009     _timer_exit_phase3.stop();
2010     _timer_exit_phase4.start();
2011   }
2012   // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
2013   Threads::remove(this);
2014 
2015   if (log_is_enabled(Debug, os, thread, timer)) {
2016     _timer_exit_phase4.stop();
2017     ResourceMark rm(this);
2018     log_debug(os, thread, timer)("name='%s'"
2019                                  ", exit-phase1=" JLONG_FORMAT
2020                                  ", exit-phase2=" JLONG_FORMAT
2021                                  ", exit-phase3=" JLONG_FORMAT
2022                                  ", exit-phase4=" JLONG_FORMAT,
2023                                  get_thread_name(),
2024                                  _timer_exit_phase1.milliseconds(),
2025                                  _timer_exit_phase2.milliseconds(),
2026                                  _timer_exit_phase3.milliseconds(),
2027                                  _timer_exit_phase4.milliseconds());
2028   }
2029 }
2030 
2031 void JavaThread::cleanup_failed_attach_current_thread() {
2032   if (active_handles() != NULL) {
2033     JNIHandleBlock* block = active_handles();
2034     set_active_handles(NULL);
2035     JNIHandleBlock::release_block(block);
2036   }
2037 
2038   if (free_handle_block() != NULL) {
2039     JNIHandleBlock* block = free_handle_block();
2040     set_free_handle_block(NULL);
2041     JNIHandleBlock::release_block(block);
2042   }
2043 
2044   // These have to be removed while this is still a valid thread.
2045   remove_stack_guard_pages();
2046 
2047   if (UseTLAB) {
2048     tlab().make_parsable(true);  // retire TLAB, if any
2049   }
2050 
2051   BarrierSet::barrier_set()->on_thread_detach(this);
2052 
2053   Threads::remove(this);
2054   this->smr_delete();
2055 }
2056 
2057 JavaThread* JavaThread::active() {
2058   Thread* thread = Thread::current();
2059   if (thread->is_Java_thread()) {
2060     return (JavaThread*) thread;
2061   } else {
2062     assert(thread->is_VM_thread(), "this must be a vm thread");
2063     VM_Operation* op = ((VMThread*) thread)->vm_operation();
2064     JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2065     assert(ret->is_Java_thread(), "must be a Java thread");
2066     return ret;
2067   }
2068 }
2069 
2070 bool JavaThread::is_lock_owned(address adr) const {
2071   if (Thread::is_lock_owned(adr)) return true;
2072 
2073   for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2074     if (chunk->contains(adr)) return true;
2075   }
2076 
2077   return false;
2078 }
2079 
2080 
2081 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2082   chunk->set_next(monitor_chunks());
2083   set_monitor_chunks(chunk);
2084 }
2085 
2086 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2087   guarantee(monitor_chunks() != NULL, "must be non empty");
2088   if (monitor_chunks() == chunk) {
2089     set_monitor_chunks(chunk->next());
2090   } else {
2091     MonitorChunk* prev = monitor_chunks();
2092     while (prev->next() != chunk) prev = prev->next();
2093     prev->set_next(chunk->next());
2094   }
2095 }
2096 
2097 // JVM support.
2098 
2099 // Note: this function shouldn't block if it's called in
2100 // _thread_in_native_trans state (such as from
2101 // check_special_condition_for_native_trans()).
2102 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2103 
2104   if (has_last_Java_frame() && has_async_condition()) {
2105     // If we are at a polling page safepoint (not a poll return)
2106     // then we must defer async exception because live registers
2107     // will be clobbered by the exception path. Poll return is
2108     // ok because the call we a returning from already collides
2109     // with exception handling registers and so there is no issue.
2110     // (The exception handling path kills call result registers but
2111     //  this is ok since the exception kills the result anyway).
2112 
2113     if (is_at_poll_safepoint()) {
2114       // if the code we are returning to has deoptimized we must defer
2115       // the exception otherwise live registers get clobbered on the
2116       // exception path before deoptimization is able to retrieve them.
2117       //
2118       RegisterMap map(this, false);
2119       frame caller_fr = last_frame().sender(&map);
2120       assert(caller_fr.is_compiled_frame(), "what?");
2121       if (caller_fr.is_deoptimized_frame()) {
2122         log_info(exceptions)("deferred async exception at compiled safepoint");
2123         return;
2124       }
2125     }
2126   }
2127 
2128   JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2129   if (condition == _no_async_condition) {
2130     // Conditions have changed since has_special_runtime_exit_condition()
2131     // was called:
2132     // - if we were here only because of an external suspend request,
2133     //   then that was taken care of above (or cancelled) so we are done
2134     // - if we were here because of another async request, then it has
2135     //   been cleared between the has_special_runtime_exit_condition()
2136     //   and now so again we are done
2137     return;
2138   }
2139 
2140   // Check for pending async. exception
2141   if (_pending_async_exception != NULL) {
2142     // Only overwrite an already pending exception, if it is not a threadDeath.
2143     if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2144 
2145       // We cannot call Exceptions::_throw(...) here because we cannot block
2146       set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2147 
2148       LogTarget(Info, exceptions) lt;
2149       if (lt.is_enabled()) {
2150         ResourceMark rm;
2151         LogStream ls(lt);
2152         ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2153           if (has_last_Java_frame()) {
2154             frame f = last_frame();
2155            ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2156           }
2157         ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2158       }
2159       _pending_async_exception = NULL;
2160       clear_has_async_exception();
2161     }
2162   }
2163 
2164   if (check_unsafe_error &&
2165       condition == _async_unsafe_access_error && !has_pending_exception()) {
2166     condition = _no_async_condition;  // done
2167     switch (thread_state()) {
2168     case _thread_in_vm: {
2169       JavaThread* THREAD = this;
2170       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2171     }
2172     case _thread_in_native: {
2173       ThreadInVMfromNative tiv(this);
2174       JavaThread* THREAD = this;
2175       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2176     }
2177     case _thread_in_Java: {
2178       ThreadInVMfromJava tiv(this);
2179       JavaThread* THREAD = this;
2180       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2181     }
2182     default:
2183       ShouldNotReachHere();
2184     }
2185   }
2186 
2187   assert(condition == _no_async_condition || has_pending_exception() ||
2188          (!check_unsafe_error && condition == _async_unsafe_access_error),
2189          "must have handled the async condition, if no exception");
2190 }
2191 
2192 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2193   //
2194   // Check for pending external suspend. Internal suspend requests do
2195   // not use handle_special_runtime_exit_condition().
2196   // If JNIEnv proxies are allowed, don't self-suspend if the target
2197   // thread is not the current thread. In older versions of jdbx, jdbx
2198   // threads could call into the VM with another thread's JNIEnv so we
2199   // can be here operating on behalf of a suspended thread (4432884).
2200   bool do_self_suspend = is_external_suspend_with_lock();
2201   if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2202     //
2203     // Because thread is external suspended the safepoint code will count
2204     // thread as at a safepoint. This can be odd because we can be here
2205     // as _thread_in_Java which would normally transition to _thread_blocked
2206     // at a safepoint. We would like to mark the thread as _thread_blocked
2207     // before calling java_suspend_self like all other callers of it but
2208     // we must then observe proper safepoint protocol. (We can't leave
2209     // _thread_blocked with a safepoint in progress). However we can be
2210     // here as _thread_in_native_trans so we can't use a normal transition
2211     // constructor/destructor pair because they assert on that type of
2212     // transition. We could do something like:
2213     //
2214     // JavaThreadState state = thread_state();
2215     // set_thread_state(_thread_in_vm);
2216     // {
2217     //   ThreadBlockInVM tbivm(this);
2218     //   java_suspend_self()
2219     // }
2220     // set_thread_state(_thread_in_vm_trans);
2221     // if (safepoint) block;
2222     // set_thread_state(state);
2223     //
2224     // but that is pretty messy. Instead we just go with the way the
2225     // code has worked before and note that this is the only path to
2226     // java_suspend_self that doesn't put the thread in _thread_blocked
2227     // mode.
2228 
2229     frame_anchor()->make_walkable(this);
2230     java_suspend_self();
2231 
2232     // We might be here for reasons in addition to the self-suspend request
2233     // so check for other async requests.
2234   }
2235 
2236   if (check_asyncs) {
2237     check_and_handle_async_exceptions();
2238   }
2239 #if INCLUDE_TRACE
2240   if (is_trace_suspend()) {
2241     TRACE_SUSPEND_THREAD(this);
2242   }
2243 #endif
2244 }
2245 
2246 void JavaThread::send_thread_stop(oop java_throwable)  {
2247   assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2248   assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2249   assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2250 
2251   // Do not throw asynchronous exceptions against the compiler thread
2252   // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2253   if (!can_call_java()) return;
2254 
2255   {
2256     // Actually throw the Throwable against the target Thread - however
2257     // only if there is no thread death exception installed already.
2258     if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2259       // If the topmost frame is a runtime stub, then we are calling into
2260       // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2261       // must deoptimize the caller before continuing, as the compiled  exception handler table
2262       // may not be valid
2263       if (has_last_Java_frame()) {
2264         frame f = last_frame();
2265         if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2266           // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2267           RegisterMap reg_map(this, UseBiasedLocking);
2268           frame compiled_frame = f.sender(&reg_map);
2269           if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2270             Deoptimization::deoptimize(this, compiled_frame, &reg_map);
2271           }
2272         }
2273       }
2274 
2275       // Set async. pending exception in thread.
2276       set_pending_async_exception(java_throwable);
2277 
2278       if (log_is_enabled(Info, exceptions)) {
2279          ResourceMark rm;
2280         log_info(exceptions)("Pending Async. exception installed of type: %s",
2281                              InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2282       }
2283       // for AbortVMOnException flag
2284       Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2285     }
2286   }
2287 
2288 
2289   // Interrupt thread so it will wake up from a potential wait()
2290   Thread::interrupt(this);
2291 }
2292 
2293 // External suspension mechanism.
2294 //
2295 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2296 // to any VM_locks and it is at a transition
2297 // Self-suspension will happen on the transition out of the vm.
2298 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2299 //
2300 // Guarantees on return:
2301 //   + Target thread will not execute any new bytecode (that's why we need to
2302 //     force a safepoint)
2303 //   + Target thread will not enter any new monitors
2304 //
2305 void JavaThread::java_suspend() {
2306   ThreadsListHandle tlh;
2307   if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) {
2308     return;
2309   }
2310 
2311   { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2312     if (!is_external_suspend()) {
2313       // a racing resume has cancelled us; bail out now
2314       return;
2315     }
2316 
2317     // suspend is done
2318     uint32_t debug_bits = 0;
2319     // Warning: is_ext_suspend_completed() may temporarily drop the
2320     // SR_lock to allow the thread to reach a stable thread state if
2321     // it is currently in a transient thread state.
2322     if (is_ext_suspend_completed(false /* !called_by_wait */,
2323                                  SuspendRetryDelay, &debug_bits)) {
2324       return;
2325     }
2326   }
2327 
2328   VM_ThreadSuspend vm_suspend;
2329   VMThread::execute(&vm_suspend);
2330 }
2331 
2332 // Part II of external suspension.
2333 // A JavaThread self suspends when it detects a pending external suspend
2334 // request. This is usually on transitions. It is also done in places
2335 // where continuing to the next transition would surprise the caller,
2336 // e.g., monitor entry.
2337 //
2338 // Returns the number of times that the thread self-suspended.
2339 //
2340 // Note: DO NOT call java_suspend_self() when you just want to block current
2341 //       thread. java_suspend_self() is the second stage of cooperative
2342 //       suspension for external suspend requests and should only be used
2343 //       to complete an external suspend request.
2344 //
2345 int JavaThread::java_suspend_self() {
2346   int ret = 0;
2347 
2348   // we are in the process of exiting so don't suspend
2349   if (is_exiting()) {
2350     clear_external_suspend();
2351     return ret;
2352   }
2353 
2354   assert(_anchor.walkable() ||
2355          (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2356          "must have walkable stack");
2357 
2358   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2359 
2360   assert(!this->is_ext_suspended(),
2361          "a thread trying to self-suspend should not already be suspended");
2362 
2363   if (this->is_suspend_equivalent()) {
2364     // If we are self-suspending as a result of the lifting of a
2365     // suspend equivalent condition, then the suspend_equivalent
2366     // flag is not cleared until we set the ext_suspended flag so
2367     // that wait_for_ext_suspend_completion() returns consistent
2368     // results.
2369     this->clear_suspend_equivalent();
2370   }
2371 
2372   // A racing resume may have cancelled us before we grabbed SR_lock
2373   // above. Or another external suspend request could be waiting for us
2374   // by the time we return from SR_lock()->wait(). The thread
2375   // that requested the suspension may already be trying to walk our
2376   // stack and if we return now, we can change the stack out from under
2377   // it. This would be a "bad thing (TM)" and cause the stack walker
2378   // to crash. We stay self-suspended until there are no more pending
2379   // external suspend requests.
2380   while (is_external_suspend()) {
2381     ret++;
2382     this->set_ext_suspended();
2383 
2384     // _ext_suspended flag is cleared by java_resume()
2385     while (is_ext_suspended()) {
2386       this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2387     }
2388   }
2389 
2390   return ret;
2391 }
2392 
2393 #ifdef ASSERT
2394 // verify the JavaThread has not yet been published in the Threads::list, and
2395 // hence doesn't need protection from concurrent access at this stage
2396 void JavaThread::verify_not_published() {
2397   ThreadsListHandle tlh;
2398   assert(!tlh.includes(this), "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 #if INCLUDE_TRACE
2464   if (thread->is_trace_suspend()) {
2465     TRACE_SUSPEND_THREAD(thread);
2466   }
2467 #endif
2468 }
2469 
2470 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2471 // progress or when _suspend_flags is non-zero.
2472 // Current thread needs to self-suspend if there is a suspend request and/or
2473 // block if a safepoint is in progress.
2474 // Also check for pending async exception (not including unsafe access error).
2475 // Note only the native==>VM/Java barriers can call this function and when
2476 // thread state is _thread_in_native_trans.
2477 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2478   check_safepoint_and_suspend_for_native_trans(thread);
2479 
2480   if (thread->has_async_exception()) {
2481     // We are in _thread_in_native_trans state, don't handle unsafe
2482     // access error since that may block.
2483     thread->check_and_handle_async_exceptions(false);
2484   }
2485 }
2486 
2487 // This is a variant of the normal
2488 // check_special_condition_for_native_trans with slightly different
2489 // semantics for use by critical native wrappers.  It does all the
2490 // normal checks but also performs the transition back into
2491 // thread_in_Java state.  This is required so that critical natives
2492 // can potentially block and perform a GC if they are the last thread
2493 // exiting the GCLocker.
2494 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2495   check_special_condition_for_native_trans(thread);
2496 
2497   // Finish the transition
2498   thread->set_thread_state(_thread_in_Java);
2499 
2500   if (thread->do_critical_native_unlock()) {
2501     ThreadInVMfromJavaNoAsyncException tiv(thread);
2502     GCLocker::unlock_critical(thread);
2503     thread->clear_critical_native_unlock();
2504   }
2505 }
2506 
2507 // We need to guarantee the Threads_lock here, since resumes are not
2508 // allowed during safepoint synchronization
2509 // Can only resume from an external suspension
2510 void JavaThread::java_resume() {
2511   assert_locked_or_safepoint(Threads_lock);
2512 
2513   // Sanity check: thread is gone, has started exiting or the thread
2514   // was not externally suspended.
2515   ThreadsListHandle tlh;
2516   if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) {
2517     return;
2518   }
2519 
2520   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2521 
2522   clear_external_suspend();
2523 
2524   if (is_ext_suspended()) {
2525     clear_ext_suspended();
2526     SR_lock()->notify_all();
2527   }
2528 }
2529 
2530 size_t JavaThread::_stack_red_zone_size = 0;
2531 size_t JavaThread::_stack_yellow_zone_size = 0;
2532 size_t JavaThread::_stack_reserved_zone_size = 0;
2533 size_t JavaThread::_stack_shadow_zone_size = 0;
2534 
2535 void JavaThread::create_stack_guard_pages() {
2536   if (!os::uses_stack_guard_pages() ||
2537       _stack_guard_state != stack_guard_unused ||
2538       (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) {
2539       log_info(os, thread)("Stack guard page creation for thread "
2540                            UINTX_FORMAT " disabled", os::current_thread_id());
2541     return;
2542   }
2543   address low_addr = stack_end();
2544   size_t len = stack_guard_zone_size();
2545 
2546   assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2547   assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2548 
2549   int must_commit = os::must_commit_stack_guard_pages();
2550   // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2551 
2552   if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2553     log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2554     return;
2555   }
2556 
2557   if (os::guard_memory((char *) low_addr, len)) {
2558     _stack_guard_state = stack_guard_enabled;
2559   } else {
2560     log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2561       PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2562     if (os::uncommit_memory((char *) low_addr, len)) {
2563       log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2564     }
2565     return;
2566   }
2567 
2568   log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2569     PTR_FORMAT "-" PTR_FORMAT ".",
2570     os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2571 }
2572 
2573 void JavaThread::remove_stack_guard_pages() {
2574   assert(Thread::current() == this, "from different thread");
2575   if (_stack_guard_state == stack_guard_unused) return;
2576   address low_addr = stack_end();
2577   size_t len = stack_guard_zone_size();
2578 
2579   if (os::must_commit_stack_guard_pages()) {
2580     if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2581       _stack_guard_state = stack_guard_unused;
2582     } else {
2583       log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2584         PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2585       return;
2586     }
2587   } else {
2588     if (_stack_guard_state == stack_guard_unused) return;
2589     if (os::unguard_memory((char *) low_addr, len)) {
2590       _stack_guard_state = stack_guard_unused;
2591     } else {
2592       log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2593         PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2594       return;
2595     }
2596   }
2597 
2598   log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2599     PTR_FORMAT "-" PTR_FORMAT ".",
2600     os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2601 }
2602 
2603 void JavaThread::enable_stack_reserved_zone() {
2604   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2605   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2606 
2607   // The base notation is from the stack's point of view, growing downward.
2608   // We need to adjust it to work correctly with guard_memory()
2609   address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2610 
2611   guarantee(base < stack_base(),"Error calculating stack reserved zone");
2612   guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2613 
2614   if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2615     _stack_guard_state = stack_guard_enabled;
2616   } else {
2617     warning("Attempt to guard stack reserved zone failed.");
2618   }
2619   enable_register_stack_guard();
2620 }
2621 
2622 void JavaThread::disable_stack_reserved_zone() {
2623   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2624   assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2625 
2626   // Simply return if called for a thread that does not use guard pages.
2627   if (_stack_guard_state == stack_guard_unused) return;
2628 
2629   // The base notation is from the stack's point of view, growing downward.
2630   // We need to adjust it to work correctly with guard_memory()
2631   address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2632 
2633   if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2634     _stack_guard_state = stack_guard_reserved_disabled;
2635   } else {
2636     warning("Attempt to unguard stack reserved zone failed.");
2637   }
2638   disable_register_stack_guard();
2639 }
2640 
2641 void JavaThread::enable_stack_yellow_reserved_zone() {
2642   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2643   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2644 
2645   // The base notation is from the stacks point of view, growing downward.
2646   // We need to adjust it to work correctly with guard_memory()
2647   address base = stack_red_zone_base();
2648 
2649   guarantee(base < stack_base(), "Error calculating stack yellow zone");
2650   guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2651 
2652   if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2653     _stack_guard_state = stack_guard_enabled;
2654   } else {
2655     warning("Attempt to guard stack yellow zone failed.");
2656   }
2657   enable_register_stack_guard();
2658 }
2659 
2660 void JavaThread::disable_stack_yellow_reserved_zone() {
2661   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2662   assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2663 
2664   // Simply return if called for a thread that does not use guard pages.
2665   if (_stack_guard_state == stack_guard_unused) return;
2666 
2667   // The base notation is from the stacks point of view, growing downward.
2668   // We need to adjust it to work correctly with guard_memory()
2669   address base = stack_red_zone_base();
2670 
2671   if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2672     _stack_guard_state = stack_guard_yellow_reserved_disabled;
2673   } else {
2674     warning("Attempt to unguard stack yellow zone failed.");
2675   }
2676   disable_register_stack_guard();
2677 }
2678 
2679 void JavaThread::enable_stack_red_zone() {
2680   // The base notation is from the stacks point of view, growing downward.
2681   // We need to adjust it to work correctly with guard_memory()
2682   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2683   address base = stack_red_zone_base() - stack_red_zone_size();
2684 
2685   guarantee(base < stack_base(), "Error calculating stack red zone");
2686   guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2687 
2688   if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2689     warning("Attempt to guard stack red zone failed.");
2690   }
2691 }
2692 
2693 void JavaThread::disable_stack_red_zone() {
2694   // The base notation is from the stacks point of view, growing downward.
2695   // We need to adjust it to work correctly with guard_memory()
2696   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2697   address base = stack_red_zone_base() - stack_red_zone_size();
2698   if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2699     warning("Attempt to unguard stack red zone failed.");
2700   }
2701 }
2702 
2703 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2704   // ignore is there is no stack
2705   if (!has_last_Java_frame()) return;
2706   // traverse the stack frames. Starts from top frame.
2707   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2708     frame* fr = fst.current();
2709     f(fr, fst.register_map());
2710   }
2711 }
2712 
2713 
2714 #ifndef PRODUCT
2715 // Deoptimization
2716 // Function for testing deoptimization
2717 void JavaThread::deoptimize() {
2718   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2719   StackFrameStream fst(this, UseBiasedLocking);
2720   bool deopt = false;           // Dump stack only if a deopt actually happens.
2721   bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2722   // Iterate over all frames in the thread and deoptimize
2723   for (; !fst.is_done(); fst.next()) {
2724     if (fst.current()->can_be_deoptimized()) {
2725 
2726       if (only_at) {
2727         // Deoptimize only at particular bcis.  DeoptimizeOnlyAt
2728         // consists of comma or carriage return separated numbers so
2729         // search for the current bci in that string.
2730         address pc = fst.current()->pc();
2731         nmethod* nm =  (nmethod*) fst.current()->cb();
2732         ScopeDesc* sd = nm->scope_desc_at(pc);
2733         char buffer[8];
2734         jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2735         size_t len = strlen(buffer);
2736         const char * found = strstr(DeoptimizeOnlyAt, buffer);
2737         while (found != NULL) {
2738           if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2739               (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2740             // Check that the bci found is bracketed by terminators.
2741             break;
2742           }
2743           found = strstr(found + 1, buffer);
2744         }
2745         if (!found) {
2746           continue;
2747         }
2748       }
2749 
2750       if (DebugDeoptimization && !deopt) {
2751         deopt = true; // One-time only print before deopt
2752         tty->print_cr("[BEFORE Deoptimization]");
2753         trace_frames();
2754         trace_stack();
2755       }
2756       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2757     }
2758   }
2759 
2760   if (DebugDeoptimization && deopt) {
2761     tty->print_cr("[AFTER Deoptimization]");
2762     trace_frames();
2763   }
2764 }
2765 
2766 
2767 // Make zombies
2768 void JavaThread::make_zombies() {
2769   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2770     if (fst.current()->can_be_deoptimized()) {
2771       // it is a Java nmethod
2772       nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2773       nm->make_not_entrant();
2774     }
2775   }
2776 }
2777 #endif // PRODUCT
2778 
2779 
2780 void JavaThread::deoptimized_wrt_marked_nmethods() {
2781   if (!has_last_Java_frame()) return;
2782   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2783   StackFrameStream fst(this, UseBiasedLocking);
2784   for (; !fst.is_done(); fst.next()) {
2785     if (fst.current()->should_be_deoptimized()) {
2786       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2787     }
2788   }
2789 }
2790 
2791 
2792 // If the caller is a NamedThread, then remember, in the current scope,
2793 // the given JavaThread in its _processed_thread field.
2794 class RememberProcessedThread: public StackObj {
2795   NamedThread* _cur_thr;
2796  public:
2797   RememberProcessedThread(JavaThread* jthr) {
2798     Thread* thread = Thread::current();
2799     if (thread->is_Named_thread()) {
2800       _cur_thr = (NamedThread *)thread;
2801       _cur_thr->set_processed_thread(jthr);
2802     } else {
2803       _cur_thr = NULL;
2804     }
2805   }
2806 
2807   ~RememberProcessedThread() {
2808     if (_cur_thr) {
2809       _cur_thr->set_processed_thread(NULL);
2810     }
2811   }
2812 };
2813 
2814 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2815   // Verify that the deferred card marks have been flushed.
2816   assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2817 
2818   // Traverse the GCHandles
2819   Thread::oops_do(f, cf);
2820 
2821   JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);)
2822 
2823   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2824          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2825 
2826   if (has_last_Java_frame()) {
2827     // Record JavaThread to GC thread
2828     RememberProcessedThread rpt(this);
2829 
2830     // Traverse the privileged stack
2831     if (_privileged_stack_top != NULL) {
2832       _privileged_stack_top->oops_do(f);
2833     }
2834 
2835     // traverse the registered growable array
2836     if (_array_for_gc != NULL) {
2837       for (int index = 0; index < _array_for_gc->length(); index++) {
2838         f->do_oop(_array_for_gc->adr_at(index));
2839       }
2840     }
2841 
2842     // Traverse the monitor chunks
2843     for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2844       chunk->oops_do(f);
2845     }
2846 
2847     // Traverse the execution stack
2848     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2849       fst.current()->oops_do(f, cf, fst.register_map());
2850     }
2851   }
2852 
2853   // callee_target is never live across a gc point so NULL it here should
2854   // it still contain a methdOop.
2855 
2856   set_callee_target(NULL);
2857 
2858   assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2859   // If we have deferred set_locals there might be oops waiting to be
2860   // written
2861   GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2862   if (list != NULL) {
2863     for (int i = 0; i < list->length(); i++) {
2864       list->at(i)->oops_do(f);
2865     }
2866   }
2867 
2868   // Traverse instance variables at the end since the GC may be moving things
2869   // around using this function
2870   f->do_oop((oop*) &_threadObj);
2871   f->do_oop((oop*) &_vm_result);
2872   f->do_oop((oop*) &_exception_oop);
2873   f->do_oop((oop*) &_pending_async_exception);
2874 
2875   if (jvmti_thread_state() != NULL) {
2876     jvmti_thread_state()->oops_do(f);
2877   }
2878 }
2879 
2880 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2881   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2882          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2883 
2884   if (has_last_Java_frame()) {
2885     // Traverse the execution stack
2886     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2887       fst.current()->nmethods_do(cf);
2888     }
2889   }
2890 }
2891 
2892 void JavaThread::metadata_do(void f(Metadata*)) {
2893   if (has_last_Java_frame()) {
2894     // Traverse the execution stack to call f() on the methods in the stack
2895     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2896       fst.current()->metadata_do(f);
2897     }
2898   } else if (is_Compiler_thread()) {
2899     // need to walk ciMetadata in current compile tasks to keep alive.
2900     CompilerThread* ct = (CompilerThread*)this;
2901     if (ct->env() != NULL) {
2902       ct->env()->metadata_do(f);
2903     }
2904     CompileTask* task = ct->task();
2905     if (task != NULL) {
2906       task->metadata_do(f);
2907     }
2908   }
2909 }
2910 
2911 // Printing
2912 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2913   switch (_thread_state) {
2914   case _thread_uninitialized:     return "_thread_uninitialized";
2915   case _thread_new:               return "_thread_new";
2916   case _thread_new_trans:         return "_thread_new_trans";
2917   case _thread_in_native:         return "_thread_in_native";
2918   case _thread_in_native_trans:   return "_thread_in_native_trans";
2919   case _thread_in_vm:             return "_thread_in_vm";
2920   case _thread_in_vm_trans:       return "_thread_in_vm_trans";
2921   case _thread_in_Java:           return "_thread_in_Java";
2922   case _thread_in_Java_trans:     return "_thread_in_Java_trans";
2923   case _thread_blocked:           return "_thread_blocked";
2924   case _thread_blocked_trans:     return "_thread_blocked_trans";
2925   default:                        return "unknown thread state";
2926   }
2927 }
2928 
2929 #ifndef PRODUCT
2930 void JavaThread::print_thread_state_on(outputStream *st) const {
2931   st->print_cr("   JavaThread state: %s", _get_thread_state_name(_thread_state));
2932 };
2933 void JavaThread::print_thread_state() const {
2934   print_thread_state_on(tty);
2935 }
2936 #endif // PRODUCT
2937 
2938 // Called by Threads::print() for VM_PrintThreads operation
2939 void JavaThread::print_on(outputStream *st) const {
2940   st->print_raw("\"");
2941   st->print_raw(get_thread_name());
2942   st->print_raw("\" ");
2943   oop thread_oop = threadObj();
2944   if (thread_oop != NULL) {
2945     st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
2946     if (java_lang_Thread::is_daemon(thread_oop))  st->print("daemon ");
2947     st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2948   }
2949   Thread::print_on(st);
2950   // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2951   st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2952   if (thread_oop != NULL) {
2953     st->print_cr("   java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2954   }
2955 #ifndef PRODUCT
2956   print_thread_state_on(st);
2957   _safepoint_state->print_on(st);
2958 #endif // PRODUCT
2959   if (is_Compiler_thread()) {
2960     CompileTask *task = ((CompilerThread*)this)->task();
2961     if (task != NULL) {
2962       st->print("   Compiling: ");
2963       task->print(st, NULL, true, false);
2964     } else {
2965       st->print("   No compile task");
2966     }
2967     st->cr();
2968   }
2969 }
2970 
2971 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2972   st->print("%s", get_thread_name_string(buf, buflen));
2973 }
2974 
2975 // Called by fatal error handler. The difference between this and
2976 // JavaThread::print() is that we can't grab lock or allocate memory.
2977 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2978   st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2979   oop thread_obj = threadObj();
2980   if (thread_obj != NULL) {
2981     if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2982   }
2983   st->print(" [");
2984   st->print("%s", _get_thread_state_name(_thread_state));
2985   if (osthread()) {
2986     st->print(", id=%d", osthread()->thread_id());
2987   }
2988   st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2989             p2i(stack_end()), p2i(stack_base()));
2990   st->print("]");
2991 
2992   if (_threads_hazard_ptr != NULL) {
2993     st->print(" _threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr));
2994   }
2995   if (_nested_threads_hazard_ptr != NULL) {
2996     print_nested_threads_hazard_ptrs_on(st);
2997   }
2998   return;
2999 }
3000 
3001 // Verification
3002 
3003 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
3004 
3005 void JavaThread::verify() {
3006   // Verify oops in the thread.
3007   oops_do(&VerifyOopClosure::verify_oop, NULL);
3008 
3009   // Verify the stack frames.
3010   frames_do(frame_verify);
3011 }
3012 
3013 // CR 6300358 (sub-CR 2137150)
3014 // Most callers of this method assume that it can't return NULL but a
3015 // thread may not have a name whilst it is in the process of attaching to
3016 // the VM - see CR 6412693, and there are places where a JavaThread can be
3017 // seen prior to having it's threadObj set (eg JNI attaching threads and
3018 // if vm exit occurs during initialization). These cases can all be accounted
3019 // for such that this method never returns NULL.
3020 const char* JavaThread::get_thread_name() const {
3021 #ifdef ASSERT
3022   // early safepoints can hit while current thread does not yet have TLS
3023   if (!SafepointSynchronize::is_at_safepoint()) {
3024     Thread *cur = Thread::current();
3025     if (!(cur->is_Java_thread() && cur == this)) {
3026       // Current JavaThreads are allowed to get their own name without
3027       // the Threads_lock.
3028       assert_locked_or_safepoint(Threads_lock);
3029     }
3030   }
3031 #endif // ASSERT
3032   return get_thread_name_string();
3033 }
3034 
3035 // Returns a non-NULL representation of this thread's name, or a suitable
3036 // descriptive string if there is no set name
3037 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3038   const char* name_str;
3039   oop thread_obj = threadObj();
3040   if (thread_obj != NULL) {
3041     oop name = java_lang_Thread::name(thread_obj);
3042     if (name != NULL) {
3043       if (buf == NULL) {
3044         name_str = java_lang_String::as_utf8_string(name);
3045       } else {
3046         name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3047       }
3048     } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3049       name_str = "<no-name - thread is attaching>";
3050     } else {
3051       name_str = Thread::name();
3052     }
3053   } else {
3054     name_str = Thread::name();
3055   }
3056   assert(name_str != NULL, "unexpected NULL thread name");
3057   return name_str;
3058 }
3059 
3060 
3061 const char* JavaThread::get_threadgroup_name() const {
3062   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3063   oop thread_obj = threadObj();
3064   if (thread_obj != NULL) {
3065     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3066     if (thread_group != NULL) {
3067       // ThreadGroup.name can be null
3068       return java_lang_ThreadGroup::name(thread_group);
3069     }
3070   }
3071   return NULL;
3072 }
3073 
3074 const char* JavaThread::get_parent_name() const {
3075   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3076   oop thread_obj = threadObj();
3077   if (thread_obj != NULL) {
3078     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3079     if (thread_group != NULL) {
3080       oop parent = java_lang_ThreadGroup::parent(thread_group);
3081       if (parent != NULL) {
3082         // ThreadGroup.name can be null
3083         return java_lang_ThreadGroup::name(parent);
3084       }
3085     }
3086   }
3087   return NULL;
3088 }
3089 
3090 ThreadPriority JavaThread::java_priority() const {
3091   oop thr_oop = threadObj();
3092   if (thr_oop == NULL) return NormPriority; // Bootstrapping
3093   ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3094   assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3095   return priority;
3096 }
3097 
3098 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3099 
3100   assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3101   // Link Java Thread object <-> C++ Thread
3102 
3103   // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3104   // and put it into a new Handle.  The Handle "thread_oop" can then
3105   // be used to pass the C++ thread object to other methods.
3106 
3107   // Set the Java level thread object (jthread) field of the
3108   // new thread (a JavaThread *) to C++ thread object using the
3109   // "thread_oop" handle.
3110 
3111   // Set the thread field (a JavaThread *) of the
3112   // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3113 
3114   Handle thread_oop(Thread::current(),
3115                     JNIHandles::resolve_non_null(jni_thread));
3116   assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3117          "must be initialized");
3118   set_threadObj(thread_oop());
3119   java_lang_Thread::set_thread(thread_oop(), this);
3120 
3121   if (prio == NoPriority) {
3122     prio = java_lang_Thread::priority(thread_oop());
3123     assert(prio != NoPriority, "A valid priority should be present");
3124   }
3125 
3126   // Push the Java priority down to the native thread; needs Threads_lock
3127   Thread::set_priority(this, prio);
3128 
3129   // Add the new thread to the Threads list and set it in motion.
3130   // We must have threads lock in order to call Threads::add.
3131   // It is crucial that we do not block before the thread is
3132   // added to the Threads list for if a GC happens, then the java_thread oop
3133   // will not be visited by GC.
3134   Threads::add(this);
3135 }
3136 
3137 oop JavaThread::current_park_blocker() {
3138   // Support for JSR-166 locks
3139   oop thread_oop = threadObj();
3140   if (thread_oop != NULL &&
3141       JDK_Version::current().supports_thread_park_blocker()) {
3142     return java_lang_Thread::park_blocker(thread_oop);
3143   }
3144   return NULL;
3145 }
3146 
3147 
3148 void JavaThread::print_stack_on(outputStream* st) {
3149   if (!has_last_Java_frame()) return;
3150   ResourceMark rm;
3151   HandleMark   hm;
3152 
3153   RegisterMap reg_map(this);
3154   vframe* start_vf = last_java_vframe(&reg_map);
3155   int count = 0;
3156   for (vframe* f = start_vf; f != NULL; f = f->sender()) {
3157     if (f->is_java_frame()) {
3158       javaVFrame* jvf = javaVFrame::cast(f);
3159       java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3160 
3161       // Print out lock information
3162       if (JavaMonitorsInStackTrace) {
3163         jvf->print_lock_info_on(st, count);
3164       }
3165     } else {
3166       // Ignore non-Java frames
3167     }
3168 
3169     // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
3170     count++;
3171     if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
3172   }
3173 }
3174 
3175 
3176 // JVMTI PopFrame support
3177 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3178   assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3179   if (in_bytes(size_in_bytes) != 0) {
3180     _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3181     _popframe_preserved_args_size = in_bytes(size_in_bytes);
3182     Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3183   }
3184 }
3185 
3186 void* JavaThread::popframe_preserved_args() {
3187   return _popframe_preserved_args;
3188 }
3189 
3190 ByteSize JavaThread::popframe_preserved_args_size() {
3191   return in_ByteSize(_popframe_preserved_args_size);
3192 }
3193 
3194 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3195   int sz = in_bytes(popframe_preserved_args_size());
3196   assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3197   return in_WordSize(sz / wordSize);
3198 }
3199 
3200 void JavaThread::popframe_free_preserved_args() {
3201   assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3202   FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3203   _popframe_preserved_args = NULL;
3204   _popframe_preserved_args_size = 0;
3205 }
3206 
3207 #ifndef PRODUCT
3208 
3209 void JavaThread::trace_frames() {
3210   tty->print_cr("[Describe stack]");
3211   int frame_no = 1;
3212   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3213     tty->print("  %d. ", frame_no++);
3214     fst.current()->print_value_on(tty, this);
3215     tty->cr();
3216   }
3217 }
3218 
3219 class PrintAndVerifyOopClosure: public OopClosure {
3220  protected:
3221   template <class T> inline void do_oop_work(T* p) {
3222     oop obj = oopDesc::load_decode_heap_oop(p);
3223     if (obj == NULL) return;
3224     tty->print(INTPTR_FORMAT ": ", p2i(p));
3225     if (oopDesc::is_oop_or_null(obj)) {
3226       if (obj->is_objArray()) {
3227         tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3228       } else {
3229         obj->print();
3230       }
3231     } else {
3232       tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3233     }
3234     tty->cr();
3235   }
3236  public:
3237   virtual void do_oop(oop* p) { do_oop_work(p); }
3238   virtual void do_oop(narrowOop* p)  { do_oop_work(p); }
3239 };
3240 
3241 
3242 static void oops_print(frame* f, const RegisterMap *map) {
3243   PrintAndVerifyOopClosure print;
3244   f->print_value();
3245   f->oops_do(&print, NULL, (RegisterMap*)map);
3246 }
3247 
3248 // Print our all the locations that contain oops and whether they are
3249 // valid or not.  This useful when trying to find the oldest frame
3250 // where an oop has gone bad since the frame walk is from youngest to
3251 // oldest.
3252 void JavaThread::trace_oops() {
3253   tty->print_cr("[Trace oops]");
3254   frames_do(oops_print);
3255 }
3256 
3257 
3258 #ifdef ASSERT
3259 // Print or validate the layout of stack frames
3260 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3261   ResourceMark rm;
3262   PRESERVE_EXCEPTION_MARK;
3263   FrameValues values;
3264   int frame_no = 0;
3265   for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3266     fst.current()->describe(values, ++frame_no);
3267     if (depth == frame_no) break;
3268   }
3269   if (validate_only) {
3270     values.validate();
3271   } else {
3272     tty->print_cr("[Describe stack layout]");
3273     values.print(this);
3274   }
3275 }
3276 #endif
3277 
3278 void JavaThread::trace_stack_from(vframe* start_vf) {
3279   ResourceMark rm;
3280   int vframe_no = 1;
3281   for (vframe* f = start_vf; f; f = f->sender()) {
3282     if (f->is_java_frame()) {
3283       javaVFrame::cast(f)->print_activation(vframe_no++);
3284     } else {
3285       f->print();
3286     }
3287     if (vframe_no > StackPrintLimit) {
3288       tty->print_cr("...<more frames>...");
3289       return;
3290     }
3291   }
3292 }
3293 
3294 
3295 void JavaThread::trace_stack() {
3296   if (!has_last_Java_frame()) return;
3297   ResourceMark rm;
3298   HandleMark   hm;
3299   RegisterMap reg_map(this);
3300   trace_stack_from(last_java_vframe(&reg_map));
3301 }
3302 
3303 
3304 #endif // PRODUCT
3305 
3306 
3307 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3308   assert(reg_map != NULL, "a map must be given");
3309   frame f = last_frame();
3310   for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3311     if (vf->is_java_frame()) return javaVFrame::cast(vf);
3312   }
3313   return NULL;
3314 }
3315 
3316 
3317 Klass* JavaThread::security_get_caller_class(int depth) {
3318   vframeStream vfst(this);
3319   vfst.security_get_caller_frame(depth);
3320   if (!vfst.at_end()) {
3321     return vfst.method()->method_holder();
3322   }
3323   return NULL;
3324 }
3325 
3326 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3327   assert(thread->is_Compiler_thread(), "must be compiler thread");
3328   CompileBroker::compiler_thread_loop();
3329 }
3330 
3331 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3332   NMethodSweeper::sweeper_loop();
3333 }
3334 
3335 // Create a CompilerThread
3336 CompilerThread::CompilerThread(CompileQueue* queue,
3337                                CompilerCounters* counters)
3338                                : JavaThread(&compiler_thread_entry) {
3339   _env   = NULL;
3340   _log   = NULL;
3341   _task  = NULL;
3342   _queue = queue;
3343   _counters = counters;
3344   _buffer_blob = NULL;
3345   _compiler = NULL;
3346 
3347   // Compiler uses resource area for compilation, let's bias it to mtCompiler
3348   resource_area()->bias_to(mtCompiler);
3349 
3350 #ifndef PRODUCT
3351   _ideal_graph_printer = NULL;
3352 #endif
3353 }
3354 
3355 CompilerThread::~CompilerThread() {
3356   // Delete objects which were allocated on heap.
3357   delete _counters;
3358   delete _log;
3359 }
3360 
3361 bool CompilerThread::can_call_java() const {
3362   return _compiler != NULL && _compiler->is_jvmci();
3363 }
3364 
3365 // Create sweeper thread
3366 CodeCacheSweeperThread::CodeCacheSweeperThread()
3367 : JavaThread(&sweeper_thread_entry) {
3368   _scanned_compiled_method = NULL;
3369 }
3370 
3371 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3372   JavaThread::oops_do(f, cf);
3373   if (_scanned_compiled_method != NULL && cf != NULL) {
3374     // Safepoints can occur when the sweeper is scanning an nmethod so
3375     // process it here to make sure it isn't unloaded in the middle of
3376     // a scan.
3377     cf->do_code_blob(_scanned_compiled_method);
3378   }
3379 }
3380 
3381 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3382   JavaThread::nmethods_do(cf);
3383   if (_scanned_compiled_method != NULL && cf != NULL) {
3384     // Safepoints can occur when the sweeper is scanning an nmethod so
3385     // process it here to make sure it isn't unloaded in the middle of
3386     // a scan.
3387     cf->do_code_blob(_scanned_compiled_method);
3388   }
3389 }
3390 
3391 
3392 // ======= Threads ========
3393 
3394 // The Threads class links together all active threads, and provides
3395 // operations over all threads. It is protected by the Threads_lock,
3396 // which is also used in other global contexts like safepointing.
3397 // ThreadsListHandles are used to safely perform operations on one
3398 // or more threads without the risk of the thread exiting during the
3399 // operation.
3400 //
3401 // Note: The Threads_lock is currently more widely used than we
3402 // would like. We are actively migrating Threads_lock uses to other
3403 // mechanisms in order to reduce Threads_lock contention.
3404 
3405 JavaThread* Threads::_thread_list = NULL;
3406 int         Threads::_number_of_threads = 0;
3407 int         Threads::_number_of_non_daemon_threads = 0;
3408 int         Threads::_return_code = 0;
3409 int         Threads::_thread_claim_parity = 0;
3410 size_t      JavaThread::_stack_size_at_create = 0;
3411 
3412 #ifdef ASSERT
3413 bool        Threads::_vm_complete = false;
3414 #endif
3415 
3416 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
3417   Prefetch::read((void*)addr, prefetch_interval);
3418   return *addr;
3419 }
3420 
3421 // Possibly the ugliest for loop the world has seen. C++ does not allow
3422 // multiple types in the declaration section of the for loop. In this case
3423 // we are only dealing with pointers and hence can cast them. It looks ugly
3424 // but macros are ugly and therefore it's fine to make things absurdly ugly.
3425 #define DO_JAVA_THREADS(LIST, X)                                                                                          \
3426     for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes,                           \
3427              *MACRO_list = (JavaThread*)(LIST),                                                                           \
3428              **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(),  \
3429              **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(),                                     \
3430              *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval);                 \
3431          MACRO_current_p != MACRO_end;                                                                                    \
3432          MACRO_current_p++,                                                                                               \
3433              X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval))
3434 
3435 // All JavaThreads
3436 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X)
3437 
3438 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3439 void Threads::threads_do(ThreadClosure* tc) {
3440   assert_locked_or_safepoint(Threads_lock);
3441   // ALL_JAVA_THREADS iterates through all JavaThreads
3442   ALL_JAVA_THREADS(p) {
3443     tc->do_thread(p);
3444   }
3445   // Someday we could have a table or list of all non-JavaThreads.
3446   // For now, just manually iterate through them.
3447   tc->do_thread(VMThread::vm_thread());
3448   Universe::heap()->gc_threads_do(tc);
3449   WatcherThread *wt = WatcherThread::watcher_thread();
3450   // Strictly speaking, the following NULL check isn't sufficient to make sure
3451   // the data for WatcherThread is still valid upon being examined. However,
3452   // considering that WatchThread terminates when the VM is on the way to
3453   // exit at safepoint, the chance of the above is extremely small. The right
3454   // way to prevent termination of WatcherThread would be to acquire
3455   // Terminator_lock, but we can't do that without violating the lock rank
3456   // checking in some cases.
3457   if (wt != NULL) {
3458     tc->do_thread(wt);
3459   }
3460 
3461   // If CompilerThreads ever become non-JavaThreads, add them here
3462 }
3463 
3464 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
3465   int cp = Threads::thread_claim_parity();
3466   ALL_JAVA_THREADS(p) {
3467     if (p->claim_oops_do(is_par, cp)) {
3468       tc->do_thread(p);
3469     }
3470   }
3471   VMThread* vmt = VMThread::vm_thread();
3472   if (vmt->claim_oops_do(is_par, cp)) {
3473     tc->do_thread(vmt);
3474   }
3475 }
3476 
3477 // The system initialization in the library has three phases.
3478 //
3479 // Phase 1: java.lang.System class initialization
3480 //     java.lang.System is a primordial class loaded and initialized
3481 //     by the VM early during startup.  java.lang.System.<clinit>
3482 //     only does registerNatives and keeps the rest of the class
3483 //     initialization work later until thread initialization completes.
3484 //
3485 //     System.initPhase1 initializes the system properties, the static
3486 //     fields in, out, and err. Set up java signal handlers, OS-specific
3487 //     system settings, and thread group of the main thread.
3488 static void call_initPhase1(TRAPS) {
3489   Klass* klass =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3490   JavaValue result(T_VOID);
3491   JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3492                                          vmSymbols::void_method_signature(), CHECK);
3493 }
3494 
3495 // Phase 2. Module system initialization
3496 //     This will initialize the module system.  Only java.base classes
3497 //     can be loaded until phase 2 completes.
3498 //
3499 //     Call System.initPhase2 after the compiler initialization and jsr292
3500 //     classes get initialized because module initialization runs a lot of java
3501 //     code, that for performance reasons, should be compiled.  Also, this will
3502 //     enable the startup code to use lambda and other language features in this
3503 //     phase and onward.
3504 //
3505 //     After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3506 static void call_initPhase2(TRAPS) {
3507   TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3508 
3509   Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3510 
3511   JavaValue result(T_INT);
3512   JavaCallArguments args;
3513   args.push_int(DisplayVMOutputToStderr);
3514   args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3515   JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3516                                          vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3517   if (result.get_jint() != JNI_OK) {
3518     vm_exit_during_initialization(); // no message or exception
3519   }
3520 
3521   universe_post_module_init();
3522 }
3523 
3524 // Phase 3. final setup - set security manager, system class loader and TCCL
3525 //
3526 //     This will instantiate and set the security manager, set the system class
3527 //     loader as well as the thread context class loader.  The security manager
3528 //     and system class loader may be a custom class loaded from -Xbootclasspath/a,
3529 //     other modules or the application's classpath.
3530 static void call_initPhase3(TRAPS) {
3531   Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3532   JavaValue result(T_VOID);
3533   JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3534                                          vmSymbols::void_method_signature(), CHECK);
3535 }
3536 
3537 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3538   TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3539 
3540   if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3541     create_vm_init_libraries();
3542   }
3543 
3544   initialize_class(vmSymbols::java_lang_String(), CHECK);
3545 
3546   // Inject CompactStrings value after the static initializers for String ran.
3547   java_lang_String::set_compact_strings(CompactStrings);
3548 
3549   // Initialize java_lang.System (needed before creating the thread)
3550   initialize_class(vmSymbols::java_lang_System(), CHECK);
3551   // The VM creates & returns objects of this class. Make sure it's initialized.
3552   initialize_class(vmSymbols::java_lang_Class(), CHECK);
3553   initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3554   Handle thread_group = create_initial_thread_group(CHECK);
3555   Universe::set_main_thread_group(thread_group());
3556   initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3557   oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3558   main_thread->set_threadObj(thread_object);
3559   // Set thread status to running since main thread has
3560   // been started and running.
3561   java_lang_Thread::set_thread_status(thread_object,
3562                                       java_lang_Thread::RUNNABLE);
3563 
3564   // The VM creates objects of this class.
3565   initialize_class(vmSymbols::java_lang_Module(), CHECK);
3566 
3567   // The VM preresolves methods to these classes. Make sure that they get initialized
3568   initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3569   initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3570 
3571   // Phase 1 of the system initialization in the library, java.lang.System class initialization
3572   call_initPhase1(CHECK);
3573 
3574   // get the Java runtime name after java.lang.System is initialized
3575   JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3576   JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3577 
3578   // an instance of OutOfMemory exception has been allocated earlier
3579   initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3580   initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3581   initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3582   initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3583   initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3584   initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3585   initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3586   initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3587 }
3588 
3589 void Threads::initialize_jsr292_core_classes(TRAPS) {
3590   TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3591 
3592   initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3593   initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3594   initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3595   initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3596 }
3597 
3598 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3599   extern void JDK_Version_init();
3600 
3601   // Preinitialize version info.
3602   VM_Version::early_initialize();
3603 
3604   // Check version
3605   if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3606 
3607   // Initialize library-based TLS
3608   ThreadLocalStorage::init();
3609 
3610   // Initialize the output stream module
3611   ostream_init();
3612 
3613   // Process java launcher properties.
3614   Arguments::process_sun_java_launcher_properties(args);
3615 
3616   // Initialize the os module
3617   os::init();
3618 
3619   // Record VM creation timing statistics
3620   TraceVmCreationTime create_vm_timer;
3621   create_vm_timer.start();
3622 
3623   // Initialize system properties.
3624   Arguments::init_system_properties();
3625 
3626   // So that JDK version can be used as a discriminator when parsing arguments
3627   JDK_Version_init();
3628 
3629   // Update/Initialize System properties after JDK version number is known
3630   Arguments::init_version_specific_system_properties();
3631 
3632   // Make sure to initialize log configuration *before* parsing arguments
3633   LogConfiguration::initialize(create_vm_timer.begin_time());
3634 
3635   // Parse arguments
3636   // Note: this internally calls os::init_container_support()
3637   jint parse_result = Arguments::parse(args);
3638   if (parse_result != JNI_OK) return parse_result;
3639 
3640   os::init_before_ergo();
3641 
3642   jint ergo_result = Arguments::apply_ergo();
3643   if (ergo_result != JNI_OK) return ergo_result;
3644 
3645   // Final check of all ranges after ergonomics which may change values.
3646   if (!CommandLineFlagRangeList::check_ranges()) {
3647     return JNI_EINVAL;
3648   }
3649 
3650   // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3651   bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo);
3652   if (!constraint_result) {
3653     return JNI_EINVAL;
3654   }
3655 
3656   CommandLineFlagWriteableList::mark_startup();
3657 
3658   if (PauseAtStartup) {
3659     os::pause();
3660   }
3661 
3662   HOTSPOT_VM_INIT_BEGIN();
3663 
3664   // Timing (must come after argument parsing)
3665   TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3666 
3667   // Initialize the os module after parsing the args
3668   jint os_init_2_result = os::init_2();
3669   if (os_init_2_result != JNI_OK) return os_init_2_result;
3670 
3671   SafepointMechanism::initialize();
3672 
3673   jint adjust_after_os_result = Arguments::adjust_after_os();
3674   if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3675 
3676   // Initialize output stream logging
3677   ostream_init_log();
3678 
3679   // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3680   // Must be before create_vm_init_agents()
3681   if (Arguments::init_libraries_at_startup()) {
3682     convert_vm_init_libraries_to_agents();
3683   }
3684 
3685   // Launch -agentlib/-agentpath and converted -Xrun agents
3686   if (Arguments::init_agents_at_startup()) {
3687     create_vm_init_agents();
3688   }
3689 
3690   // Initialize Threads state
3691   _thread_list = NULL;
3692   _number_of_threads = 0;
3693   _number_of_non_daemon_threads = 0;
3694 
3695   // Initialize global data structures and create system classes in heap
3696   vm_init_globals();
3697 
3698 #if INCLUDE_JVMCI
3699   if (JVMCICounterSize > 0) {
3700     JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3701     memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3702   } else {
3703     JavaThread::_jvmci_old_thread_counters = NULL;
3704   }
3705 #endif // INCLUDE_JVMCI
3706 
3707   // Attach the main thread to this os thread
3708   JavaThread* main_thread = new JavaThread();
3709   main_thread->set_thread_state(_thread_in_vm);
3710   main_thread->initialize_thread_current();
3711   // must do this before set_active_handles
3712   main_thread->record_stack_base_and_size();
3713   main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3714 
3715   if (!main_thread->set_as_starting_thread()) {
3716     vm_shutdown_during_initialization(
3717                                       "Failed necessary internal allocation. Out of swap space");
3718     main_thread->smr_delete();
3719     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3720     return JNI_ENOMEM;
3721   }
3722 
3723   // Enable guard page *after* os::create_main_thread(), otherwise it would
3724   // crash Linux VM, see notes in os_linux.cpp.
3725   main_thread->create_stack_guard_pages();
3726 
3727   // Initialize Java-Level synchronization subsystem
3728   ObjectMonitor::Initialize();
3729 
3730   // Initialize global modules
3731   jint status = init_globals();
3732   if (status != JNI_OK) {
3733     main_thread->smr_delete();
3734     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3735     return status;
3736   }
3737 
3738   if (TRACE_INITIALIZE() != JNI_OK) {
3739     vm_exit_during_initialization("Failed to initialize tracing backend");
3740   }
3741 
3742   // Should be done after the heap is fully created
3743   main_thread->cache_global_variables();
3744 
3745   HandleMark hm;
3746 
3747   { MutexLocker mu(Threads_lock);
3748     Threads::add(main_thread);
3749   }
3750 
3751   // Any JVMTI raw monitors entered in onload will transition into
3752   // real raw monitor. VM is setup enough here for raw monitor enter.
3753   JvmtiExport::transition_pending_onload_raw_monitors();
3754 
3755   // Create the VMThread
3756   { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3757 
3758   VMThread::create();
3759     Thread* vmthread = VMThread::vm_thread();
3760 
3761     if (!os::create_thread(vmthread, os::vm_thread)) {
3762       vm_exit_during_initialization("Cannot create VM thread. "
3763                                     "Out of system resources.");
3764     }
3765 
3766     // Wait for the VM thread to become ready, and VMThread::run to initialize
3767     // Monitors can have spurious returns, must always check another state flag
3768     {
3769       MutexLocker ml(Notify_lock);
3770       os::start_thread(vmthread);
3771       while (vmthread->active_handles() == NULL) {
3772         Notify_lock->wait();
3773       }
3774     }
3775   }
3776 
3777   assert(Universe::is_fully_initialized(), "not initialized");
3778   if (VerifyDuringStartup) {
3779     // Make sure we're starting with a clean slate.
3780     VM_Verify verify_op;
3781     VMThread::execute(&verify_op);
3782   }
3783 
3784   Thread* THREAD = Thread::current();
3785 
3786   // Always call even when there are not JVMTI environments yet, since environments
3787   // may be attached late and JVMTI must track phases of VM execution
3788   JvmtiExport::enter_early_start_phase();
3789 
3790   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3791   JvmtiExport::post_early_vm_start();
3792 
3793   initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3794 
3795   // We need this for ClassDataSharing - the initial vm.info property is set
3796   // with the default value of CDS "sharing" which may be reset through
3797   // command line options.
3798   reset_vm_info_property(CHECK_JNI_ERR);
3799 
3800   quicken_jni_functions();
3801 
3802   // No more stub generation allowed after that point.
3803   StubCodeDesc::freeze();
3804 
3805   // Set flag that basic initialization has completed. Used by exceptions and various
3806   // debug stuff, that does not work until all basic classes have been initialized.
3807   set_init_completed();
3808 
3809   LogConfiguration::post_initialize();
3810   Metaspace::post_initialize();
3811 
3812   HOTSPOT_VM_INIT_END();
3813 
3814   // record VM initialization completion time
3815 #if INCLUDE_MANAGEMENT
3816   Management::record_vm_init_completed();
3817 #endif // INCLUDE_MANAGEMENT
3818 
3819   // Signal Dispatcher needs to be started before VMInit event is posted
3820   os::signal_init(CHECK_JNI_ERR);
3821 
3822   // Start Attach Listener if +StartAttachListener or it can't be started lazily
3823   if (!DisableAttachMechanism) {
3824     AttachListener::vm_start();
3825     if (StartAttachListener || AttachListener::init_at_startup()) {
3826       AttachListener::init();
3827     }
3828   }
3829 
3830   // Launch -Xrun agents
3831   // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3832   // back-end can launch with -Xdebug -Xrunjdwp.
3833   if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3834     create_vm_init_libraries();
3835   }
3836 
3837   if (CleanChunkPoolAsync) {
3838     Chunk::start_chunk_pool_cleaner_task();
3839   }
3840 
3841   // initialize compiler(s)
3842 #if defined(COMPILER1) || COMPILER2_OR_JVMCI
3843   CompileBroker::compilation_init(CHECK_JNI_ERR);
3844 #endif
3845 
3846   // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3847   // It is done after compilers are initialized, because otherwise compilations of
3848   // signature polymorphic MH intrinsics can be missed
3849   // (see SystemDictionary::find_method_handle_intrinsic).
3850   initialize_jsr292_core_classes(CHECK_JNI_ERR);
3851 
3852   // This will initialize the module system.  Only java.base classes can be
3853   // loaded until phase 2 completes
3854   call_initPhase2(CHECK_JNI_ERR);
3855 
3856   // Always call even when there are not JVMTI environments yet, since environments
3857   // may be attached late and JVMTI must track phases of VM execution
3858   JvmtiExport::enter_start_phase();
3859 
3860   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3861   JvmtiExport::post_vm_start();
3862 
3863   // Final system initialization including security manager and system class loader
3864   call_initPhase3(CHECK_JNI_ERR);
3865 
3866   // cache the system and platform class loaders
3867   SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
3868 
3869 #if INCLUDE_JVMCI
3870   if (EnableJVMCI) {
3871     // Initialize JVMCI eagerly when it is explicitly requested.
3872     // Or when JVMCIPrintProperties is enabled.
3873     // The JVMCI Java initialization code will read this flag and
3874     // do the printing if it's set.
3875     bool init = EagerJVMCI || JVMCIPrintProperties;
3876 
3877     if (!init) {
3878       // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3879       // compilations via JVMCI will not actually block until JVMCI is initialized.
3880       init = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3881     }
3882 
3883     if (init) {
3884       JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
3885     }
3886   }
3887 #endif
3888 
3889   // Always call even when there are not JVMTI environments yet, since environments
3890   // may be attached late and JVMTI must track phases of VM execution
3891   JvmtiExport::enter_live_phase();
3892 
3893   // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3894   JvmtiExport::post_vm_initialized();
3895 
3896   if (TRACE_START() != JNI_OK) {
3897     vm_exit_during_initialization("Failed to start tracing backend.");
3898   }
3899 
3900 #if INCLUDE_MANAGEMENT
3901   Management::initialize(THREAD);
3902 
3903   if (HAS_PENDING_EXCEPTION) {
3904     // management agent fails to start possibly due to
3905     // configuration problem and is responsible for printing
3906     // stack trace if appropriate. Simply exit VM.
3907     vm_exit(1);
3908   }
3909 #endif // INCLUDE_MANAGEMENT
3910 
3911   if (MemProfiling)                   MemProfiler::engage();
3912   StatSampler::engage();
3913   if (CheckJNICalls)                  JniPeriodicChecker::engage();
3914 
3915   BiasedLocking::init();
3916 
3917 #if INCLUDE_RTM_OPT
3918   RTMLockingCounters::init();
3919 #endif
3920 
3921   if (JDK_Version::current().post_vm_init_hook_enabled()) {
3922     call_postVMInitHook(THREAD);
3923     // The Java side of PostVMInitHook.run must deal with all
3924     // exceptions and provide means of diagnosis.
3925     if (HAS_PENDING_EXCEPTION) {
3926       CLEAR_PENDING_EXCEPTION;
3927     }
3928   }
3929 
3930   {
3931     MutexLocker ml(PeriodicTask_lock);
3932     // Make sure the WatcherThread can be started by WatcherThread::start()
3933     // or by dynamic enrollment.
3934     WatcherThread::make_startable();
3935     // Start up the WatcherThread if there are any periodic tasks
3936     // NOTE:  All PeriodicTasks should be registered by now. If they
3937     //   aren't, late joiners might appear to start slowly (we might
3938     //   take a while to process their first tick).
3939     if (PeriodicTask::num_tasks() > 0) {
3940       WatcherThread::start();
3941     }
3942   }
3943 
3944   create_vm_timer.end();
3945 #ifdef ASSERT
3946   _vm_complete = true;
3947 #endif
3948 
3949   if (DumpSharedSpaces) {
3950     MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3951     ShouldNotReachHere();
3952   }
3953 
3954   return JNI_OK;
3955 }
3956 
3957 // type for the Agent_OnLoad and JVM_OnLoad entry points
3958 extern "C" {
3959   typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3960 }
3961 // Find a command line agent library and return its entry point for
3962 //         -agentlib:  -agentpath:   -Xrun
3963 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3964 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3965                                     const char *on_load_symbols[],
3966                                     size_t num_symbol_entries) {
3967   OnLoadEntry_t on_load_entry = NULL;
3968   void *library = NULL;
3969 
3970   if (!agent->valid()) {
3971     char buffer[JVM_MAXPATHLEN];
3972     char ebuf[1024] = "";
3973     const char *name = agent->name();
3974     const char *msg = "Could not find agent library ";
3975 
3976     // First check to see if agent is statically linked into executable
3977     if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3978       library = agent->os_lib();
3979     } else if (agent->is_absolute_path()) {
3980       library = os::dll_load(name, ebuf, sizeof ebuf);
3981       if (library == NULL) {
3982         const char *sub_msg = " in absolute path, with error: ";
3983         size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3984         char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3985         jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3986         // If we can't find the agent, exit.
3987         vm_exit_during_initialization(buf, NULL);
3988         FREE_C_HEAP_ARRAY(char, buf);
3989       }
3990     } else {
3991       // Try to load the agent from the standard dll directory
3992       if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
3993                              name)) {
3994         library = os::dll_load(buffer, ebuf, sizeof ebuf);
3995       }
3996       if (library == NULL) { // Try the library path directory.
3997         if (os::dll_build_name(buffer, sizeof(buffer), name)) {
3998           library = os::dll_load(buffer, ebuf, sizeof ebuf);
3999         }
4000         if (library == NULL) {
4001           const char *sub_msg = " on the library path, with error: ";
4002           const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image.";
4003 
4004           size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) +
4005                        strlen(ebuf) + strlen(sub_msg2) + 1;
4006           char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4007           if (!agent->is_instrument_lib()) {
4008             jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4009           } else {
4010             jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2);
4011           }
4012           // If we can't find the agent, exit.
4013           vm_exit_during_initialization(buf, NULL);
4014           FREE_C_HEAP_ARRAY(char, buf);
4015         }
4016       }
4017     }
4018     agent->set_os_lib(library);
4019     agent->set_valid();
4020   }
4021 
4022   // Find the OnLoad function.
4023   on_load_entry =
4024     CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
4025                                                           false,
4026                                                           on_load_symbols,
4027                                                           num_symbol_entries));
4028   return on_load_entry;
4029 }
4030 
4031 // Find the JVM_OnLoad entry point
4032 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
4033   const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
4034   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4035 }
4036 
4037 // Find the Agent_OnLoad entry point
4038 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
4039   const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
4040   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4041 }
4042 
4043 // For backwards compatibility with -Xrun
4044 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
4045 // treated like -agentpath:
4046 // Must be called before agent libraries are created
4047 void Threads::convert_vm_init_libraries_to_agents() {
4048   AgentLibrary* agent;
4049   AgentLibrary* next;
4050 
4051   for (agent = Arguments::libraries(); agent != NULL; agent = next) {
4052     next = agent->next();  // cache the next agent now as this agent may get moved off this list
4053     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4054 
4055     // If there is an JVM_OnLoad function it will get called later,
4056     // otherwise see if there is an Agent_OnLoad
4057     if (on_load_entry == NULL) {
4058       on_load_entry = lookup_agent_on_load(agent);
4059       if (on_load_entry != NULL) {
4060         // switch it to the agent list -- so that Agent_OnLoad will be called,
4061         // JVM_OnLoad won't be attempted and Agent_OnUnload will
4062         Arguments::convert_library_to_agent(agent);
4063       } else {
4064         vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
4065       }
4066     }
4067   }
4068 }
4069 
4070 // Create agents for -agentlib:  -agentpath:  and converted -Xrun
4071 // Invokes Agent_OnLoad
4072 // Called very early -- before JavaThreads exist
4073 void Threads::create_vm_init_agents() {
4074   extern struct JavaVM_ main_vm;
4075   AgentLibrary* agent;
4076 
4077   JvmtiExport::enter_onload_phase();
4078 
4079   for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4080     OnLoadEntry_t  on_load_entry = lookup_agent_on_load(agent);
4081 
4082     if (on_load_entry != NULL) {
4083       // Invoke the Agent_OnLoad function
4084       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4085       if (err != JNI_OK) {
4086         vm_exit_during_initialization("agent library failed to init", agent->name());
4087       }
4088     } else {
4089       vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4090     }
4091   }
4092   JvmtiExport::enter_primordial_phase();
4093 }
4094 
4095 extern "C" {
4096   typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4097 }
4098 
4099 void Threads::shutdown_vm_agents() {
4100   // Send any Agent_OnUnload notifications
4101   const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4102   size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4103   extern struct JavaVM_ main_vm;
4104   for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4105 
4106     // Find the Agent_OnUnload function.
4107     Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4108                                                    os::find_agent_function(agent,
4109                                                    false,
4110                                                    on_unload_symbols,
4111                                                    num_symbol_entries));
4112 
4113     // Invoke the Agent_OnUnload function
4114     if (unload_entry != NULL) {
4115       JavaThread* thread = JavaThread::current();
4116       ThreadToNativeFromVM ttn(thread);
4117       HandleMark hm(thread);
4118       (*unload_entry)(&main_vm);
4119     }
4120   }
4121 }
4122 
4123 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4124 // Invokes JVM_OnLoad
4125 void Threads::create_vm_init_libraries() {
4126   extern struct JavaVM_ main_vm;
4127   AgentLibrary* agent;
4128 
4129   for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4130     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4131 
4132     if (on_load_entry != NULL) {
4133       // Invoke the JVM_OnLoad function
4134       JavaThread* thread = JavaThread::current();
4135       ThreadToNativeFromVM ttn(thread);
4136       HandleMark hm(thread);
4137       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4138       if (err != JNI_OK) {
4139         vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4140       }
4141     } else {
4142       vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4143     }
4144   }
4145 }
4146 
4147 
4148 // Last thread running calls java.lang.Shutdown.shutdown()
4149 void JavaThread::invoke_shutdown_hooks() {
4150   HandleMark hm(this);
4151 
4152   // We could get here with a pending exception, if so clear it now.
4153   if (this->has_pending_exception()) {
4154     this->clear_pending_exception();
4155   }
4156 
4157   EXCEPTION_MARK;
4158   Klass* shutdown_klass =
4159     SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4160                                       THREAD);
4161   if (shutdown_klass != NULL) {
4162     // SystemDictionary::resolve_or_null will return null if there was
4163     // an exception.  If we cannot load the Shutdown class, just don't
4164     // call Shutdown.shutdown() at all.  This will mean the shutdown hooks
4165     // won't be run.  Note that if a shutdown hook was registered,
4166     // the Shutdown class would have already been loaded
4167     // (Runtime.addShutdownHook will load it).
4168     JavaValue result(T_VOID);
4169     JavaCalls::call_static(&result,
4170                            shutdown_klass,
4171                            vmSymbols::shutdown_method_name(),
4172                            vmSymbols::void_method_signature(),
4173                            THREAD);
4174   }
4175   CLEAR_PENDING_EXCEPTION;
4176 }
4177 
4178 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4179 // the program falls off the end of main(). Another VM exit path is through
4180 // vm_exit() when the program calls System.exit() to return a value or when
4181 // there is a serious error in VM. The two shutdown paths are not exactly
4182 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4183 // and VM_Exit op at VM level.
4184 //
4185 // Shutdown sequence:
4186 //   + Shutdown native memory tracking if it is on
4187 //   + Wait until we are the last non-daemon thread to execute
4188 //     <-- every thing is still working at this moment -->
4189 //   + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4190 //        shutdown hooks
4191 //   + Call before_exit(), prepare for VM exit
4192 //      > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4193 //        currently the only user of this mechanism is File.deleteOnExit())
4194 //      > stop StatSampler, watcher thread, CMS threads,
4195 //        post thread end and vm death events to JVMTI,
4196 //        stop signal thread
4197 //   + Call JavaThread::exit(), it will:
4198 //      > release JNI handle blocks, remove stack guard pages
4199 //      > remove this thread from Threads list
4200 //     <-- no more Java code from this thread after this point -->
4201 //   + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4202 //     the compiler threads at safepoint
4203 //     <-- do not use anything that could get blocked by Safepoint -->
4204 //   + Disable tracing at JNI/JVM barriers
4205 //   + Set _vm_exited flag for threads that are still running native code
4206 //   + Delete this thread
4207 //   + Call exit_globals()
4208 //      > deletes tty
4209 //      > deletes PerfMemory resources
4210 //   + Return to caller
4211 
4212 bool Threads::destroy_vm() {
4213   JavaThread* thread = JavaThread::current();
4214 
4215 #ifdef ASSERT
4216   _vm_complete = false;
4217 #endif
4218   // Wait until we are the last non-daemon thread to execute
4219   { MutexLocker nu(Threads_lock);
4220     while (Threads::number_of_non_daemon_threads() > 1)
4221       // This wait should make safepoint checks, wait without a timeout,
4222       // and wait as a suspend-equivalent condition.
4223       Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4224                          Mutex::_as_suspend_equivalent_flag);
4225   }
4226 
4227   EventShutdown e;
4228   if (e.should_commit()) {
4229     e.set_reason("No remaining non-daemon Java threads");
4230     e.commit();
4231   }
4232 
4233   // Hang forever on exit if we are reporting an error.
4234   if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4235     os::infinite_sleep();
4236   }
4237   os::wait_for_keypress_at_exit();
4238 
4239   // run Java level shutdown hooks
4240   thread->invoke_shutdown_hooks();
4241 
4242   before_exit(thread);
4243 
4244   thread->exit(true);
4245 
4246   // Stop VM thread.
4247   {
4248     // 4945125 The vm thread comes to a safepoint during exit.
4249     // GC vm_operations can get caught at the safepoint, and the
4250     // heap is unparseable if they are caught. Grab the Heap_lock
4251     // to prevent this. The GC vm_operations will not be able to
4252     // queue until after the vm thread is dead. After this point,
4253     // we'll never emerge out of the safepoint before the VM exits.
4254 
4255     MutexLocker ml(Heap_lock);
4256 
4257     VMThread::wait_for_vm_thread_exit();
4258     assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4259     VMThread::destroy();
4260   }
4261 
4262   // clean up ideal graph printers
4263 #if defined(COMPILER2) && !defined(PRODUCT)
4264   IdealGraphPrinter::clean_up();
4265 #endif
4266 
4267   // Now, all Java threads are gone except daemon threads. Daemon threads
4268   // running Java code or in VM are stopped by the Safepoint. However,
4269   // daemon threads executing native code are still running.  But they
4270   // will be stopped at native=>Java/VM barriers. Note that we can't
4271   // simply kill or suspend them, as it is inherently deadlock-prone.
4272 
4273   VM_Exit::set_vm_exited();
4274 
4275   notify_vm_shutdown();
4276 
4277   // We are after VM_Exit::set_vm_exited() so we can't call
4278   // thread->smr_delete() or we will block on the Threads_lock.
4279   // Deleting the shutdown thread here is safe because another
4280   // JavaThread cannot have an active ThreadsListHandle for
4281   // this JavaThread.
4282   delete thread;
4283 
4284 #if INCLUDE_JVMCI
4285   if (JVMCICounterSize > 0) {
4286     FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4287   }
4288 #endif
4289 
4290   // exit_globals() will delete tty
4291   exit_globals();
4292 
4293   LogConfiguration::finalize();
4294 
4295   return true;
4296 }
4297 
4298 
4299 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4300   if (version == JNI_VERSION_1_1) return JNI_TRUE;
4301   return is_supported_jni_version(version);
4302 }
4303 
4304 
4305 jboolean Threads::is_supported_jni_version(jint version) {
4306   if (version == JNI_VERSION_1_2) return JNI_TRUE;
4307   if (version == JNI_VERSION_1_4) return JNI_TRUE;
4308   if (version == JNI_VERSION_1_6) return JNI_TRUE;
4309   if (version == JNI_VERSION_1_8) return JNI_TRUE;
4310   if (version == JNI_VERSION_9) return JNI_TRUE;
4311   if (version == JNI_VERSION_10) return JNI_TRUE;
4312   return JNI_FALSE;
4313 }
4314 
4315 
4316 void Threads::add(JavaThread* p, bool force_daemon) {
4317   // The threads lock must be owned at this point
4318   assert_locked_or_safepoint(Threads_lock);
4319 
4320   BarrierSet::barrier_set()->on_thread_attach(p);
4321 
4322   p->set_next(_thread_list);
4323   _thread_list = p;
4324 
4325   // Once a JavaThread is added to the Threads list, smr_delete() has
4326   // to be used to delete it. Otherwise we can just delete it directly.
4327   p->set_on_thread_list();
4328 
4329   _number_of_threads++;
4330   oop threadObj = p->threadObj();
4331   bool daemon = true;
4332   // Bootstrapping problem: threadObj can be null for initial
4333   // JavaThread (or for threads attached via JNI)
4334   if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4335     _number_of_non_daemon_threads++;
4336     daemon = false;
4337   }
4338 
4339   ThreadService::add_thread(p, daemon);
4340 
4341   // Maintain fast thread list
4342   ThreadsSMRSupport::add_thread(p);
4343 
4344   // Possible GC point.
4345   Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4346 }
4347 
4348 void Threads::remove(JavaThread* p) {
4349 
4350   // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread.
4351   ObjectSynchronizer::omFlush(p);
4352 
4353   // Extra scope needed for Thread_lock, so we can check
4354   // that we do not remove thread without safepoint code notice
4355   { MutexLocker ml(Threads_lock);
4356 
4357     assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present");
4358 
4359     // Maintain fast thread list
4360     ThreadsSMRSupport::remove_thread(p);
4361 
4362     JavaThread* current = _thread_list;
4363     JavaThread* prev    = NULL;
4364 
4365     while (current != p) {
4366       prev    = current;
4367       current = current->next();
4368     }
4369 
4370     if (prev) {
4371       prev->set_next(current->next());
4372     } else {
4373       _thread_list = p->next();
4374     }
4375 
4376     _number_of_threads--;
4377     oop threadObj = p->threadObj();
4378     bool daemon = true;
4379     if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4380       _number_of_non_daemon_threads--;
4381       daemon = false;
4382 
4383       // Only one thread left, do a notify on the Threads_lock so a thread waiting
4384       // on destroy_vm will wake up.
4385       if (number_of_non_daemon_threads() == 1) {
4386         Threads_lock->notify_all();
4387       }
4388     }
4389     ThreadService::remove_thread(p, daemon);
4390 
4391     // Make sure that safepoint code disregard this thread. This is needed since
4392     // the thread might mess around with locks after this point. This can cause it
4393     // to do callbacks into the safepoint code. However, the safepoint code is not aware
4394     // of this thread since it is removed from the queue.
4395     p->set_terminated_value();
4396   } // unlock Threads_lock
4397 
4398   // Since Events::log uses a lock, we grab it outside the Threads_lock
4399   Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4400 }
4401 
4402 // Operations on the Threads list for GC.  These are not explicitly locked,
4403 // but the garbage collector must provide a safe context for them to run.
4404 // In particular, these things should never be called when the Threads_lock
4405 // is held by some other thread. (Note: the Safepoint abstraction also
4406 // uses the Threads_lock to guarantee this property. It also makes sure that
4407 // all threads gets blocked when exiting or starting).
4408 
4409 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4410   ALL_JAVA_THREADS(p) {
4411     p->oops_do(f, cf);
4412   }
4413   VMThread::vm_thread()->oops_do(f, cf);
4414 }
4415 
4416 void Threads::change_thread_claim_parity() {
4417   // Set the new claim parity.
4418   assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4419          "Not in range.");
4420   _thread_claim_parity++;
4421   if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4422   assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4423          "Not in range.");
4424 }
4425 
4426 #ifdef ASSERT
4427 void Threads::assert_all_threads_claimed() {
4428   ALL_JAVA_THREADS(p) {
4429     const int thread_parity = p->oops_do_parity();
4430     assert((thread_parity == _thread_claim_parity),
4431            "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4432   }
4433   VMThread* vmt = VMThread::vm_thread();
4434   const int thread_parity = vmt->oops_do_parity();
4435   assert((thread_parity == _thread_claim_parity),
4436          "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity);
4437 }
4438 #endif // ASSERT
4439 
4440 class ParallelOopsDoThreadClosure : public ThreadClosure {
4441 private:
4442   OopClosure* _f;
4443   CodeBlobClosure* _cf;
4444 public:
4445   ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {}
4446   void do_thread(Thread* t) {
4447     t->oops_do(_f, _cf);
4448   }
4449 };
4450 
4451 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4452   ParallelOopsDoThreadClosure tc(f, cf);
4453   possibly_parallel_threads_do(is_par, &tc);
4454 }
4455 
4456 #if INCLUDE_ALL_GCS
4457 // Used by ParallelScavenge
4458 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4459   ALL_JAVA_THREADS(p) {
4460     q->enqueue(new ThreadRootsTask(p));
4461   }
4462   q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4463 }
4464 
4465 // Used by Parallel Old
4466 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4467   ALL_JAVA_THREADS(p) {
4468     q->enqueue(new ThreadRootsMarkingTask(p));
4469   }
4470   q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4471 }
4472 #endif // INCLUDE_ALL_GCS
4473 
4474 void Threads::nmethods_do(CodeBlobClosure* cf) {
4475   ALL_JAVA_THREADS(p) {
4476     // This is used by the code cache sweeper to mark nmethods that are active
4477     // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4478     // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4479     if(!p->is_Code_cache_sweeper_thread()) {
4480       p->nmethods_do(cf);
4481     }
4482   }
4483 }
4484 
4485 void Threads::metadata_do(void f(Metadata*)) {
4486   ALL_JAVA_THREADS(p) {
4487     p->metadata_do(f);
4488   }
4489 }
4490 
4491 class ThreadHandlesClosure : public ThreadClosure {
4492   void (*_f)(Metadata*);
4493  public:
4494   ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4495   virtual void do_thread(Thread* thread) {
4496     thread->metadata_handles_do(_f);
4497   }
4498 };
4499 
4500 void Threads::metadata_handles_do(void f(Metadata*)) {
4501   // Only walk the Handles in Thread.
4502   ThreadHandlesClosure handles_closure(f);
4503   threads_do(&handles_closure);
4504 }
4505 
4506 void Threads::deoptimized_wrt_marked_nmethods() {
4507   ALL_JAVA_THREADS(p) {
4508     p->deoptimized_wrt_marked_nmethods();
4509   }
4510 }
4511 
4512 
4513 // Get count Java threads that are waiting to enter the specified monitor.
4514 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
4515                                                          int count,
4516                                                          address monitor) {
4517   GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4518 
4519   int i = 0;
4520   DO_JAVA_THREADS(t_list, p) {
4521     if (!p->can_call_java()) continue;
4522 
4523     address pending = (address)p->current_pending_monitor();
4524     if (pending == monitor) {             // found a match
4525       if (i < count) result->append(p);   // save the first count matches
4526       i++;
4527     }
4528   }
4529 
4530   return result;
4531 }
4532 
4533 
4534 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
4535                                                       address owner) {
4536   // NULL owner means not locked so we can skip the search
4537   if (owner == NULL) return NULL;
4538 
4539   DO_JAVA_THREADS(t_list, p) {
4540     // first, see if owner is the address of a Java thread
4541     if (owner == (address)p) return p;
4542   }
4543 
4544   // Cannot assert on lack of success here since this function may be
4545   // used by code that is trying to report useful problem information
4546   // like deadlock detection.
4547   if (UseHeavyMonitors) return NULL;
4548 
4549   // If we didn't find a matching Java thread and we didn't force use of
4550   // heavyweight monitors, then the owner is the stack address of the
4551   // Lock Word in the owning Java thread's stack.
4552   //
4553   JavaThread* the_owner = NULL;
4554   DO_JAVA_THREADS(t_list, q) {
4555     if (q->is_lock_owned(owner)) {
4556       the_owner = q;
4557       break;
4558     }
4559   }
4560 
4561   // cannot assert on lack of success here; see above comment
4562   return the_owner;
4563 }
4564 
4565 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4566 void Threads::print_on(outputStream* st, bool print_stacks,
4567                        bool internal_format, bool print_concurrent_locks) {
4568   char buf[32];
4569   st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4570 
4571   st->print_cr("Full thread dump %s (%s %s):",
4572                Abstract_VM_Version::vm_name(),
4573                Abstract_VM_Version::vm_release(),
4574                Abstract_VM_Version::vm_info_string());
4575   st->cr();
4576 
4577 #if INCLUDE_SERVICES
4578   // Dump concurrent locks
4579   ConcurrentLocksDump concurrent_locks;
4580   if (print_concurrent_locks) {
4581     concurrent_locks.dump_at_safepoint();
4582   }
4583 #endif // INCLUDE_SERVICES
4584 
4585   ThreadsSMRSupport::print_info_on(st);
4586   st->cr();
4587 
4588   ALL_JAVA_THREADS(p) {
4589     ResourceMark rm;
4590     p->print_on(st);
4591     if (print_stacks) {
4592       if (internal_format) {
4593         p->trace_stack();
4594       } else {
4595         p->print_stack_on(st);
4596       }
4597     }
4598     st->cr();
4599 #if INCLUDE_SERVICES
4600     if (print_concurrent_locks) {
4601       concurrent_locks.print_locks_on(p, st);
4602     }
4603 #endif // INCLUDE_SERVICES
4604   }
4605 
4606   VMThread::vm_thread()->print_on(st);
4607   st->cr();
4608   Universe::heap()->print_gc_threads_on(st);
4609   WatcherThread* wt = WatcherThread::watcher_thread();
4610   if (wt != NULL) {
4611     wt->print_on(st);
4612     st->cr();
4613   }
4614 
4615   st->flush();
4616 }
4617 
4618 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4619                              int buflen, bool* found_current) {
4620   if (this_thread != NULL) {
4621     bool is_current = (current == this_thread);
4622     *found_current = *found_current || is_current;
4623     st->print("%s", is_current ? "=>" : "  ");
4624 
4625     st->print(PTR_FORMAT, p2i(this_thread));
4626     st->print(" ");
4627     this_thread->print_on_error(st, buf, buflen);
4628     st->cr();
4629   }
4630 }
4631 
4632 class PrintOnErrorClosure : public ThreadClosure {
4633   outputStream* _st;
4634   Thread* _current;
4635   char* _buf;
4636   int _buflen;
4637   bool* _found_current;
4638  public:
4639   PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4640                       int buflen, bool* found_current) :
4641    _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4642 
4643   virtual void do_thread(Thread* thread) {
4644     Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4645   }
4646 };
4647 
4648 // Threads::print_on_error() is called by fatal error handler. It's possible
4649 // that VM is not at safepoint and/or current thread is inside signal handler.
4650 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4651 // memory (even in resource area), it might deadlock the error handler.
4652 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4653                              int buflen) {
4654   ThreadsSMRSupport::print_info_on(st);
4655   st->cr();
4656 
4657   bool found_current = false;
4658   st->print_cr("Java Threads: ( => current thread )");
4659   ALL_JAVA_THREADS(thread) {
4660     print_on_error(thread, st, current, buf, buflen, &found_current);
4661   }
4662   st->cr();
4663 
4664   st->print_cr("Other Threads:");
4665   print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4666   print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4667 
4668   PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4669   Universe::heap()->gc_threads_do(&print_closure);
4670 
4671   if (!found_current) {
4672     st->cr();
4673     st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4674     current->print_on_error(st, buf, buflen);
4675     st->cr();
4676   }
4677   st->cr();
4678 
4679   st->print_cr("Threads with active compile tasks:");
4680   print_threads_compiling(st, buf, buflen);
4681 }
4682 
4683 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4684   ALL_JAVA_THREADS(thread) {
4685     if (thread->is_Compiler_thread()) {
4686       CompilerThread* ct = (CompilerThread*) thread;
4687 
4688       // Keep task in local variable for NULL check.
4689       // ct->_task might be set to NULL by concurring compiler thread
4690       // because it completed the compilation. The task is never freed,
4691       // though, just returned to a free list.
4692       CompileTask* task = ct->task();
4693       if (task != NULL) {
4694         thread->print_name_on_error(st, buf, buflen);
4695         task->print(st, NULL, true, true);
4696       }
4697     }
4698   }
4699 }
4700 
4701 
4702 // Internal SpinLock and Mutex
4703 // Based on ParkEvent
4704 
4705 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4706 //
4707 // We employ SpinLocks _only for low-contention, fixed-length
4708 // short-duration critical sections where we're concerned
4709 // about native mutex_t or HotSpot Mutex:: latency.
4710 // The mux construct provides a spin-then-block mutual exclusion
4711 // mechanism.
4712 //
4713 // Testing has shown that contention on the ListLock guarding gFreeList
4714 // is common.  If we implement ListLock as a simple SpinLock it's common
4715 // for the JVM to devolve to yielding with little progress.  This is true
4716 // despite the fact that the critical sections protected by ListLock are
4717 // extremely short.
4718 //
4719 // TODO-FIXME: ListLock should be of type SpinLock.
4720 // We should make this a 1st-class type, integrated into the lock
4721 // hierarchy as leaf-locks.  Critically, the SpinLock structure
4722 // should have sufficient padding to avoid false-sharing and excessive
4723 // cache-coherency traffic.
4724 
4725 
4726 typedef volatile int SpinLockT;
4727 
4728 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4729   if (Atomic::cmpxchg (1, adr, 0) == 0) {
4730     return;   // normal fast-path return
4731   }
4732 
4733   // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4734   TEVENT(SpinAcquire - ctx);
4735   int ctr = 0;
4736   int Yields = 0;
4737   for (;;) {
4738     while (*adr != 0) {
4739       ++ctr;
4740       if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4741         if (Yields > 5) {
4742           os::naked_short_sleep(1);
4743         } else {
4744           os::naked_yield();
4745           ++Yields;
4746         }
4747       } else {
4748         SpinPause();
4749       }
4750     }
4751     if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4752   }
4753 }
4754 
4755 void Thread::SpinRelease(volatile int * adr) {
4756   assert(*adr != 0, "invariant");
4757   OrderAccess::fence();      // guarantee at least release consistency.
4758   // Roach-motel semantics.
4759   // It's safe if subsequent LDs and STs float "up" into the critical section,
4760   // but prior LDs and STs within the critical section can't be allowed
4761   // to reorder or float past the ST that releases the lock.
4762   // Loads and stores in the critical section - which appear in program
4763   // order before the store that releases the lock - must also appear
4764   // before the store that releases the lock in memory visibility order.
4765   // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4766   // the ST of 0 into the lock-word which releases the lock, so fence
4767   // more than covers this on all platforms.
4768   *adr = 0;
4769 }
4770 
4771 // muxAcquire and muxRelease:
4772 //
4773 // *  muxAcquire and muxRelease support a single-word lock-word construct.
4774 //    The LSB of the word is set IFF the lock is held.
4775 //    The remainder of the word points to the head of a singly-linked list
4776 //    of threads blocked on the lock.
4777 //
4778 // *  The current implementation of muxAcquire-muxRelease uses its own
4779 //    dedicated Thread._MuxEvent instance.  If we're interested in
4780 //    minimizing the peak number of extant ParkEvent instances then
4781 //    we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4782 //    as certain invariants were satisfied.  Specifically, care would need
4783 //    to be taken with regards to consuming unpark() "permits".
4784 //    A safe rule of thumb is that a thread would never call muxAcquire()
4785 //    if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4786 //    park().  Otherwise the _ParkEvent park() operation in muxAcquire() could
4787 //    consume an unpark() permit intended for monitorenter, for instance.
4788 //    One way around this would be to widen the restricted-range semaphore
4789 //    implemented in park().  Another alternative would be to provide
4790 //    multiple instances of the PlatformEvent() for each thread.  One
4791 //    instance would be dedicated to muxAcquire-muxRelease, for instance.
4792 //
4793 // *  Usage:
4794 //    -- Only as leaf locks
4795 //    -- for short-term locking only as muxAcquire does not perform
4796 //       thread state transitions.
4797 //
4798 // Alternatives:
4799 // *  We could implement muxAcquire and muxRelease with MCS or CLH locks
4800 //    but with parking or spin-then-park instead of pure spinning.
4801 // *  Use Taura-Oyama-Yonenzawa locks.
4802 // *  It's possible to construct a 1-0 lock if we encode the lockword as
4803 //    (List,LockByte).  Acquire will CAS the full lockword while Release
4804 //    will STB 0 into the LockByte.  The 1-0 scheme admits stranding, so
4805 //    acquiring threads use timers (ParkTimed) to detect and recover from
4806 //    the stranding window.  Thread/Node structures must be aligned on 256-byte
4807 //    boundaries by using placement-new.
4808 // *  Augment MCS with advisory back-link fields maintained with CAS().
4809 //    Pictorially:  LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4810 //    The validity of the backlinks must be ratified before we trust the value.
4811 //    If the backlinks are invalid the exiting thread must back-track through the
4812 //    the forward links, which are always trustworthy.
4813 // *  Add a successor indication.  The LockWord is currently encoded as
4814 //    (List, LOCKBIT:1).  We could also add a SUCCBIT or an explicit _succ variable
4815 //    to provide the usual futile-wakeup optimization.
4816 //    See RTStt for details.
4817 // *  Consider schedctl.sc_nopreempt to cover the critical section.
4818 //
4819 
4820 
4821 const intptr_t LOCKBIT = 1;
4822 
4823 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4824   intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4825   if (w == 0) return;
4826   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4827     return;
4828   }
4829 
4830   TEVENT(muxAcquire - Contention);
4831   ParkEvent * const Self = Thread::current()->_MuxEvent;
4832   assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4833   for (;;) {
4834     int its = (os::is_MP() ? 100 : 0) + 1;
4835 
4836     // Optional spin phase: spin-then-park strategy
4837     while (--its >= 0) {
4838       w = *Lock;
4839       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4840         return;
4841       }
4842     }
4843 
4844     Self->reset();
4845     Self->OnList = intptr_t(Lock);
4846     // The following fence() isn't _strictly necessary as the subsequent
4847     // CAS() both serializes execution and ratifies the fetched *Lock value.
4848     OrderAccess::fence();
4849     for (;;) {
4850       w = *Lock;
4851       if ((w & LOCKBIT) == 0) {
4852         if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4853           Self->OnList = 0;   // hygiene - allows stronger asserts
4854           return;
4855         }
4856         continue;      // Interference -- *Lock changed -- Just retry
4857       }
4858       assert(w & LOCKBIT, "invariant");
4859       Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4860       if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4861     }
4862 
4863     while (Self->OnList != 0) {
4864       Self->park();
4865     }
4866   }
4867 }
4868 
4869 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4870   intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4871   if (w == 0) return;
4872   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4873     return;
4874   }
4875 
4876   TEVENT(muxAcquire - Contention);
4877   ParkEvent * ReleaseAfter = NULL;
4878   if (ev == NULL) {
4879     ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4880   }
4881   assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4882   for (;;) {
4883     guarantee(ev->OnList == 0, "invariant");
4884     int its = (os::is_MP() ? 100 : 0) + 1;
4885 
4886     // Optional spin phase: spin-then-park strategy
4887     while (--its >= 0) {
4888       w = *Lock;
4889       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4890         if (ReleaseAfter != NULL) {
4891           ParkEvent::Release(ReleaseAfter);
4892         }
4893         return;
4894       }
4895     }
4896 
4897     ev->reset();
4898     ev->OnList = intptr_t(Lock);
4899     // The following fence() isn't _strictly necessary as the subsequent
4900     // CAS() both serializes execution and ratifies the fetched *Lock value.
4901     OrderAccess::fence();
4902     for (;;) {
4903       w = *Lock;
4904       if ((w & LOCKBIT) == 0) {
4905         if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4906           ev->OnList = 0;
4907           // We call ::Release while holding the outer lock, thus
4908           // artificially lengthening the critical section.
4909           // Consider deferring the ::Release() until the subsequent unlock(),
4910           // after we've dropped the outer lock.
4911           if (ReleaseAfter != NULL) {
4912             ParkEvent::Release(ReleaseAfter);
4913           }
4914           return;
4915         }
4916         continue;      // Interference -- *Lock changed -- Just retry
4917       }
4918       assert(w & LOCKBIT, "invariant");
4919       ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4920       if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4921     }
4922 
4923     while (ev->OnList != 0) {
4924       ev->park();
4925     }
4926   }
4927 }
4928 
4929 // Release() must extract a successor from the list and then wake that thread.
4930 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4931 // similar to that used by ParkEvent::Allocate() and ::Release().  DMR-based
4932 // Release() would :
4933 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4934 // (B) Extract a successor from the private list "in-hand"
4935 // (C) attempt to CAS() the residual back into *Lock over null.
4936 //     If there were any newly arrived threads and the CAS() would fail.
4937 //     In that case Release() would detach the RATs, re-merge the list in-hand
4938 //     with the RATs and repeat as needed.  Alternately, Release() might
4939 //     detach and extract a successor, but then pass the residual list to the wakee.
4940 //     The wakee would be responsible for reattaching and remerging before it
4941 //     competed for the lock.
4942 //
4943 // Both "pop" and DMR are immune from ABA corruption -- there can be
4944 // multiple concurrent pushers, but only one popper or detacher.
4945 // This implementation pops from the head of the list.  This is unfair,
4946 // but tends to provide excellent throughput as hot threads remain hot.
4947 // (We wake recently run threads first).
4948 //
4949 // All paths through muxRelease() will execute a CAS.
4950 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4951 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4952 // executed within the critical section are complete and globally visible before the
4953 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4954 void Thread::muxRelease(volatile intptr_t * Lock)  {
4955   for (;;) {
4956     const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT);
4957     assert(w & LOCKBIT, "invariant");
4958     if (w == LOCKBIT) return;
4959     ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4960     assert(List != NULL, "invariant");
4961     assert(List->OnList == intptr_t(Lock), "invariant");
4962     ParkEvent * const nxt = List->ListNext;
4963     guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4964 
4965     // The following CAS() releases the lock and pops the head element.
4966     // The CAS() also ratifies the previously fetched lock-word value.
4967     if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) {
4968       continue;
4969     }
4970     List->OnList = 0;
4971     OrderAccess::fence();
4972     List->unpark();
4973     return;
4974   }
4975 }
4976 
4977 
4978 void Threads::verify() {
4979   ALL_JAVA_THREADS(p) {
4980     p->verify();
4981   }
4982   VMThread* thread = VMThread::vm_thread();
4983   if (thread != NULL) thread->verify();
4984 }