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/metaspaceShared.hpp"
  47 #include "memory/oopFactory.hpp"
  48 #include "memory/resourceArea.hpp"
  49 #include "memory/universe.inline.hpp"
  50 #include "oops/instanceKlass.hpp"
  51 #include "oops/objArrayOop.hpp"
  52 #include "oops/oop.inline.hpp"
  53 #include "oops/symbol.hpp"
  54 #include "oops/typeArrayOop.inline.hpp"
  55 #include "oops/verifyOopClosure.hpp"
  56 #include "prims/jvm_misc.hpp"
  57 #include "prims/jvmtiExport.hpp"
  58 #include "prims/jvmtiThreadState.hpp"
  59 #include "prims/privilegedStack.hpp"
  60 #include "runtime/arguments.hpp"
  61 #include "runtime/atomic.hpp"
  62 #include "runtime/biasedLocking.hpp"
  63 #include "runtime/commandLineFlagConstraintList.hpp"
  64 #include "runtime/commandLineFlagWriteableList.hpp"
  65 #include "runtime/commandLineFlagRangeList.hpp"
  66 #include "runtime/deoptimization.hpp"
  67 #include "runtime/frame.inline.hpp"
  68 #include "runtime/globals.hpp"
  69 #include "runtime/handshake.hpp"
  70 #include "runtime/init.hpp"
  71 #include "runtime/interfaceSupport.hpp"
  72 #include "runtime/java.hpp"
  73 #include "runtime/javaCalls.hpp"
  74 #include "runtime/jniPeriodicChecker.hpp"
  75 #include "runtime/memprofiler.hpp"
  76 #include "runtime/mutexLocker.hpp"
  77 #include "runtime/objectMonitor.hpp"
  78 #include "runtime/orderAccess.inline.hpp"
  79 #include "runtime/osThread.hpp"
  80 #include "runtime/prefetch.inline.hpp"
  81 #include "runtime/safepoint.hpp"
  82 #include "runtime/safepointMechanism.inline.hpp"
  83 #include "runtime/sharedRuntime.hpp"
  84 #include "runtime/statSampler.hpp"
  85 #include "runtime/stubRoutines.hpp"
  86 #include "runtime/sweeper.hpp"
  87 #include "runtime/task.hpp"
  88 #include "runtime/thread.inline.hpp"
  89 #include "runtime/threadCritical.hpp"
  90 #include "runtime/threadSMR.inline.hpp"
  91 #include "runtime/timer.hpp"
  92 #include "runtime/timerTrace.hpp"
  93 #include "runtime/vframe.hpp"
  94 #include "runtime/vframeArray.hpp"
  95 #include "runtime/vframe_hp.hpp"
  96 #include "runtime/vmThread.hpp"
  97 #include "runtime/vm_operations.hpp"
  98 #include "runtime/vm_version.hpp"
  99 #include "services/attachListener.hpp"
 100 #include "services/management.hpp"
 101 #include "services/memTracker.hpp"
 102 #include "services/threadService.hpp"
 103 #include "trace/traceMacros.hpp"
 104 #include "trace/tracing.hpp"
 105 #include "utilities/align.hpp"
 106 #include "utilities/defaultStream.hpp"
 107 #include "utilities/dtrace.hpp"
 108 #include "utilities/events.hpp"
 109 #include "utilities/macros.hpp"
 110 #include "utilities/preserveException.hpp"
 111 #include "utilities/vmError.hpp"
 112 #if INCLUDE_ALL_GCS
 113 #include "gc/cms/concurrentMarkSweepThread.hpp"
 114 #include "gc/g1/concurrentMarkThread.inline.hpp"
 115 #include "gc/parallel/pcTasks.hpp"
 116 #endif // INCLUDE_ALL_GCS
 117 #if INCLUDE_JVMCI
 118 #include "jvmci/jvmciCompiler.hpp"
 119 #include "jvmci/jvmciRuntime.hpp"
 120 #include "logging/logHandle.hpp"
 121 #endif
 122 #ifdef COMPILER1
 123 #include "c1/c1_Compiler.hpp"
 124 #endif
 125 #ifdef COMPILER2
 126 #include "opto/c2compiler.hpp"
 127 #include "opto/idealGraphPrinter.hpp"
 128 #endif
 129 #if INCLUDE_RTM_OPT
 130 #include "runtime/rtmLocking.hpp"
 131 #endif
 132 
 133 // Initialization after module runtime initialization
 134 void universe_post_module_init();  // must happen after call_initPhase2
 135 
 136 #ifdef DTRACE_ENABLED
 137 
 138 // Only bother with this argument setup if dtrace is available
 139 
 140   #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
 141   #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
 142 
 143   #define DTRACE_THREAD_PROBE(probe, javathread)                           \
 144     {                                                                      \
 145       ResourceMark rm(this);                                               \
 146       int len = 0;                                                         \
 147       const char* name = (javathread)->get_thread_name();                  \
 148       len = strlen(name);                                                  \
 149       HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */               \
 150         (char *) name, len,                                                \
 151         java_lang_Thread::thread_id((javathread)->threadObj()),            \
 152         (uintptr_t) (javathread)->osthread()->thread_id(),                 \
 153         java_lang_Thread::is_daemon((javathread)->threadObj()));           \
 154     }
 155 
 156 #else //  ndef DTRACE_ENABLED
 157 
 158   #define DTRACE_THREAD_PROBE(probe, javathread)
 159 
 160 #endif // ndef DTRACE_ENABLED
 161 
 162 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 163 // Current thread is maintained as a thread-local variable
 164 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
 165 #endif
 166 // Class hierarchy
 167 // - Thread
 168 //   - VMThread
 169 //   - WatcherThread
 170 //   - ConcurrentMarkSweepThread
 171 //   - JavaThread
 172 //     - CompilerThread
 173 
 174 // ======= Thread ========
 175 // Support for forcing alignment of thread objects for biased locking
 176 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
 177   if (UseBiasedLocking) {
 178     const int alignment = markOopDesc::biased_lock_alignment;
 179     size_t aligned_size = size + (alignment - sizeof(intptr_t));
 180     void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
 181                                           : AllocateHeap(aligned_size, flags, CURRENT_PC,
 182                                                          AllocFailStrategy::RETURN_NULL);
 183     void* aligned_addr     = align_up(real_malloc_addr, alignment);
 184     assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
 185            ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
 186            "JavaThread alignment code overflowed allocated storage");
 187     if (aligned_addr != real_malloc_addr) {
 188       log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
 189                               p2i(real_malloc_addr),
 190                               p2i(aligned_addr));
 191     }
 192     ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
 193     return aligned_addr;
 194   } else {
 195     return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
 196                        : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
 197   }
 198 }
 199 
 200 void Thread::operator delete(void* p) {
 201   if (UseBiasedLocking) {
 202     FreeHeap(((Thread*) p)->_real_malloc_address);
 203   } else {
 204     FreeHeap(p);
 205   }
 206 }
 207 
 208 void JavaThread::smr_delete() {
 209   if (_on_thread_list) {
 210     ThreadsSMRSupport::smr_delete(this);
 211   } else {
 212     delete this;
 213   }
 214 }
 215 
 216 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
 217 // JavaThread
 218 
 219 
 220 Thread::Thread() {
 221   // stack and get_thread
 222   set_stack_base(NULL);
 223   set_stack_size(0);
 224   set_self_raw_id(0);
 225   set_lgrp_id(-1);
 226   DEBUG_ONLY(clear_suspendible_thread();)
 227 
 228   // allocated data structures
 229   set_osthread(NULL);
 230   set_resource_area(new (mtThread)ResourceArea());
 231   DEBUG_ONLY(_current_resource_mark = NULL;)
 232   set_handle_area(new (mtThread) HandleArea(NULL));
 233   set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
 234   set_active_handles(NULL);
 235   set_free_handle_block(NULL);
 236   set_last_handle_mark(NULL);
 237 
 238   // This initial value ==> never claimed.
 239   _oops_do_parity = 0;
 240   _threads_hazard_ptr = NULL;
 241   _nested_threads_hazard_ptr = NULL;
 242   _nested_threads_hazard_ptr_cnt = 0;
 243 
 244   // the handle mark links itself to last_handle_mark
 245   new HandleMark(this);
 246 
 247   // plain initialization
 248   debug_only(_owned_locks = NULL;)
 249   debug_only(_allow_allocation_count = 0;)
 250   NOT_PRODUCT(_allow_safepoint_count = 0;)
 251   NOT_PRODUCT(_skip_gcalot = false;)
 252   _jvmti_env_iteration_count = 0;
 253   set_allocated_bytes(0);
 254   _vm_operation_started_count = 0;
 255   _vm_operation_completed_count = 0;
 256   _current_pending_monitor = NULL;
 257   _current_pending_monitor_is_from_java = true;
 258   _current_waiting_monitor = NULL;
 259   _num_nested_signal = 0;
 260   omFreeList = NULL;
 261   omFreeCount = 0;
 262   omFreeProvision = 32;
 263   omInUseList = NULL;
 264   omInUseCount = 0;
 265 
 266 #ifdef ASSERT
 267   _visited_for_critical_count = false;
 268 #endif
 269 
 270   _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
 271                          Monitor::_safepoint_check_sometimes);
 272   _suspend_flags = 0;
 273 
 274   // thread-specific hashCode stream generator state - Marsaglia shift-xor form
 275   _hashStateX = os::random();
 276   _hashStateY = 842502087;
 277   _hashStateZ = 0x8767;    // (int)(3579807591LL & 0xffff) ;
 278   _hashStateW = 273326509;
 279 
 280   _OnTrap   = 0;
 281   _schedctl = NULL;
 282   _Stalled  = 0;
 283   _TypeTag  = 0x2BAD;
 284 
 285   // Many of the following fields are effectively final - immutable
 286   // Note that nascent threads can't use the Native Monitor-Mutex
 287   // construct until the _MutexEvent is initialized ...
 288   // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
 289   // we might instead use a stack of ParkEvents that we could provision on-demand.
 290   // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
 291   // and ::Release()
 292   _ParkEvent   = ParkEvent::Allocate(this);
 293   _SleepEvent  = ParkEvent::Allocate(this);
 294   _MutexEvent  = ParkEvent::Allocate(this);
 295   _MuxEvent    = ParkEvent::Allocate(this);
 296 
 297 #ifdef CHECK_UNHANDLED_OOPS
 298   if (CheckUnhandledOops) {
 299     _unhandled_oops = new UnhandledOops(this);
 300   }
 301 #endif // CHECK_UNHANDLED_OOPS
 302 #ifdef ASSERT
 303   if (UseBiasedLocking) {
 304     assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
 305     assert(this == _real_malloc_address ||
 306            this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment),
 307            "bug in forced alignment of thread objects");
 308   }
 309 #endif // ASSERT
 310 }
 311 
 312 void Thread::initialize_thread_current() {
 313 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 314   assert(_thr_current == NULL, "Thread::current already initialized");
 315   _thr_current = this;
 316 #endif
 317   assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
 318   ThreadLocalStorage::set_thread(this);
 319   assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
 320 }
 321 
 322 void Thread::clear_thread_current() {
 323   assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
 324 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 325   _thr_current = NULL;
 326 #endif
 327   ThreadLocalStorage::set_thread(NULL);
 328 }
 329 
 330 void Thread::record_stack_base_and_size() {
 331   set_stack_base(os::current_stack_base());
 332   set_stack_size(os::current_stack_size());
 333   // CR 7190089: on Solaris, primordial thread's stack is adjusted
 334   // in initialize_thread(). Without the adjustment, stack size is
 335   // incorrect if stack is set to unlimited (ulimit -s unlimited).
 336   // So far, only Solaris has real implementation of initialize_thread().
 337   //
 338   // set up any platform-specific state.
 339   os::initialize_thread(this);
 340 
 341   // Set stack limits after thread is initialized.
 342   if (is_Java_thread()) {
 343     ((JavaThread*) this)->set_stack_overflow_limit();
 344     ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
 345   }
 346 #if INCLUDE_NMT
 347   // record thread's native stack, stack grows downward
 348   MemTracker::record_thread_stack(stack_end(), stack_size());
 349 #endif // INCLUDE_NMT
 350   log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
 351     PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
 352     os::current_thread_id(), p2i(stack_base() - stack_size()),
 353     p2i(stack_base()), stack_size()/1024);
 354 }
 355 
 356 
 357 Thread::~Thread() {
 358   EVENT_THREAD_DESTRUCT(this);
 359 
 360   // stack_base can be NULL if the thread is never started or exited before
 361   // record_stack_base_and_size called. Although, we would like to ensure
 362   // that all started threads do call record_stack_base_and_size(), there is
 363   // not proper way to enforce that.
 364 #if INCLUDE_NMT
 365   if (_stack_base != NULL) {
 366     MemTracker::release_thread_stack(stack_end(), stack_size());
 367 #ifdef ASSERT
 368     set_stack_base(NULL);
 369 #endif
 370   }
 371 #endif // INCLUDE_NMT
 372 
 373   // deallocate data structures
 374   delete resource_area();
 375   // since the handle marks are using the handle area, we have to deallocated the root
 376   // handle mark before deallocating the thread's handle area,
 377   assert(last_handle_mark() != NULL, "check we have an element");
 378   delete last_handle_mark();
 379   assert(last_handle_mark() == NULL, "check we have reached the end");
 380 
 381   // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
 382   // We NULL out the fields for good hygiene.
 383   ParkEvent::Release(_ParkEvent); _ParkEvent   = NULL;
 384   ParkEvent::Release(_SleepEvent); _SleepEvent  = NULL;
 385   ParkEvent::Release(_MutexEvent); _MutexEvent  = NULL;
 386   ParkEvent::Release(_MuxEvent); _MuxEvent    = NULL;
 387 
 388   delete handle_area();
 389   delete metadata_handles();
 390 
 391   // SR_handler uses this as a termination indicator -
 392   // needs to happen before os::free_thread()
 393   delete _SR_lock;
 394   _SR_lock = NULL;
 395 
 396   // osthread() can be NULL, if creation of thread failed.
 397   if (osthread() != NULL) os::free_thread(osthread());
 398 
 399   // clear Thread::current if thread is deleting itself.
 400   // Needed to ensure JNI correctly detects non-attached threads.
 401   if (this == Thread::current()) {
 402     clear_thread_current();
 403   }
 404 
 405   CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
 406 }
 407 
 408 // NOTE: dummy function for assertion purpose.
 409 void Thread::run() {
 410   ShouldNotReachHere();
 411 }
 412 
 413 #ifdef ASSERT
 414 // A JavaThread is considered "dangling" if it is not the current
 415 // thread, has been added the Threads list, the system is not at a
 416 // safepoint and the Thread is not "protected".
 417 //
 418 void Thread::check_for_dangling_thread_pointer(Thread *thread) {
 419   assert(!thread->is_Java_thread() || Thread::current() == thread ||
 420          !((JavaThread *) thread)->on_thread_list() ||
 421          SafepointSynchronize::is_at_safepoint() ||
 422          ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread),
 423          "possibility of dangling Thread pointer");
 424 }
 425 #endif
 426 
 427 ThreadPriority Thread::get_priority(const Thread* const thread) {
 428   ThreadPriority priority;
 429   // Can return an error!
 430   (void)os::get_priority(thread, priority);
 431   assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
 432   return priority;
 433 }
 434 
 435 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
 436   debug_only(check_for_dangling_thread_pointer(thread);)
 437   // Can return an error!
 438   (void)os::set_priority(thread, priority);
 439 }
 440 
 441 
 442 void Thread::start(Thread* thread) {
 443   // Start is different from resume in that its safety is guaranteed by context or
 444   // being called from a Java method synchronized on the Thread object.
 445   if (!DisableStartThread) {
 446     if (thread->is_Java_thread()) {
 447       // Initialize the thread state to RUNNABLE before starting this thread.
 448       // Can not set it after the thread started because we do not know the
 449       // exact thread state at that time. It could be in MONITOR_WAIT or
 450       // in SLEEPING or some other state.
 451       java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
 452                                           java_lang_Thread::RUNNABLE);
 453     }
 454     os::start_thread(thread);
 455   }
 456 }
 457 
 458 // Enqueue a VM_Operation to do the job for us - sometime later
 459 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
 460   VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
 461   VMThread::execute(vm_stop);
 462 }
 463 
 464 
 465 // Check if an external suspend request has completed (or has been
 466 // cancelled). Returns true if the thread is externally suspended and
 467 // false otherwise.
 468 //
 469 // The bits parameter returns information about the code path through
 470 // the routine. Useful for debugging:
 471 //
 472 // set in is_ext_suspend_completed():
 473 // 0x00000001 - routine was entered
 474 // 0x00000010 - routine return false at end
 475 // 0x00000100 - thread exited (return false)
 476 // 0x00000200 - suspend request cancelled (return false)
 477 // 0x00000400 - thread suspended (return true)
 478 // 0x00001000 - thread is in a suspend equivalent state (return true)
 479 // 0x00002000 - thread is native and walkable (return true)
 480 // 0x00004000 - thread is native_trans and walkable (needed retry)
 481 //
 482 // set in wait_for_ext_suspend_completion():
 483 // 0x00010000 - routine was entered
 484 // 0x00020000 - suspend request cancelled before loop (return false)
 485 // 0x00040000 - thread suspended before loop (return true)
 486 // 0x00080000 - suspend request cancelled in loop (return false)
 487 // 0x00100000 - thread suspended in loop (return true)
 488 // 0x00200000 - suspend not completed during retry loop (return false)
 489 
 490 // Helper class for tracing suspend wait debug bits.
 491 //
 492 // 0x00000100 indicates that the target thread exited before it could
 493 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
 494 // 0x00080000 each indicate a cancelled suspend request so they don't
 495 // count as wait failures either.
 496 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
 497 
 498 class TraceSuspendDebugBits : public StackObj {
 499  private:
 500   JavaThread * jt;
 501   bool         is_wait;
 502   bool         called_by_wait;  // meaningful when !is_wait
 503   uint32_t *   bits;
 504 
 505  public:
 506   TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
 507                         uint32_t *_bits) {
 508     jt             = _jt;
 509     is_wait        = _is_wait;
 510     called_by_wait = _called_by_wait;
 511     bits           = _bits;
 512   }
 513 
 514   ~TraceSuspendDebugBits() {
 515     if (!is_wait) {
 516 #if 1
 517       // By default, don't trace bits for is_ext_suspend_completed() calls.
 518       // That trace is very chatty.
 519       return;
 520 #else
 521       if (!called_by_wait) {
 522         // If tracing for is_ext_suspend_completed() is enabled, then only
 523         // trace calls to it from wait_for_ext_suspend_completion()
 524         return;
 525       }
 526 #endif
 527     }
 528 
 529     if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
 530       if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
 531         MutexLocker ml(Threads_lock);  // needed for get_thread_name()
 532         ResourceMark rm;
 533 
 534         tty->print_cr(
 535                       "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
 536                       jt->get_thread_name(), *bits);
 537 
 538         guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
 539       }
 540     }
 541   }
 542 };
 543 #undef DEBUG_FALSE_BITS
 544 
 545 
 546 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
 547                                           uint32_t *bits) {
 548   TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
 549 
 550   bool did_trans_retry = false;  // only do thread_in_native_trans retry once
 551   bool do_trans_retry;           // flag to force the retry
 552 
 553   *bits |= 0x00000001;
 554 
 555   do {
 556     do_trans_retry = false;
 557 
 558     if (is_exiting()) {
 559       // Thread is in the process of exiting. This is always checked
 560       // first to reduce the risk of dereferencing a freed JavaThread.
 561       *bits |= 0x00000100;
 562       return false;
 563     }
 564 
 565     if (!is_external_suspend()) {
 566       // Suspend request is cancelled. This is always checked before
 567       // is_ext_suspended() to reduce the risk of a rogue resume
 568       // confusing the thread that made the suspend request.
 569       *bits |= 0x00000200;
 570       return false;
 571     }
 572 
 573     if (is_ext_suspended()) {
 574       // thread is suspended
 575       *bits |= 0x00000400;
 576       return true;
 577     }
 578 
 579     // Now that we no longer do hard suspends of threads running
 580     // native code, the target thread can be changing thread state
 581     // while we are in this routine:
 582     //
 583     //   _thread_in_native -> _thread_in_native_trans -> _thread_blocked
 584     //
 585     // We save a copy of the thread state as observed at this moment
 586     // and make our decision about suspend completeness based on the
 587     // copy. This closes the race where the thread state is seen as
 588     // _thread_in_native_trans in the if-thread_blocked check, but is
 589     // seen as _thread_blocked in if-thread_in_native_trans check.
 590     JavaThreadState save_state = thread_state();
 591 
 592     if (save_state == _thread_blocked && is_suspend_equivalent()) {
 593       // If the thread's state is _thread_blocked and this blocking
 594       // condition is known to be equivalent to a suspend, then we can
 595       // consider the thread to be externally suspended. This means that
 596       // the code that sets _thread_blocked has been modified to do
 597       // self-suspension if the blocking condition releases. We also
 598       // used to check for CONDVAR_WAIT here, but that is now covered by
 599       // the _thread_blocked with self-suspension check.
 600       //
 601       // Return true since we wouldn't be here unless there was still an
 602       // external suspend request.
 603       *bits |= 0x00001000;
 604       return true;
 605     } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
 606       // Threads running native code will self-suspend on native==>VM/Java
 607       // transitions. If its stack is walkable (should always be the case
 608       // unless this function is called before the actual java_suspend()
 609       // call), then the wait is done.
 610       *bits |= 0x00002000;
 611       return true;
 612     } else if (!called_by_wait && !did_trans_retry &&
 613                save_state == _thread_in_native_trans &&
 614                frame_anchor()->walkable()) {
 615       // The thread is transitioning from thread_in_native to another
 616       // thread state. check_safepoint_and_suspend_for_native_trans()
 617       // will force the thread to self-suspend. If it hasn't gotten
 618       // there yet we may have caught the thread in-between the native
 619       // code check above and the self-suspend. Lucky us. If we were
 620       // called by wait_for_ext_suspend_completion(), then it
 621       // will be doing the retries so we don't have to.
 622       //
 623       // Since we use the saved thread state in the if-statement above,
 624       // there is a chance that the thread has already transitioned to
 625       // _thread_blocked by the time we get here. In that case, we will
 626       // make a single unnecessary pass through the logic below. This
 627       // doesn't hurt anything since we still do the trans retry.
 628 
 629       *bits |= 0x00004000;
 630 
 631       // Once the thread leaves thread_in_native_trans for another
 632       // thread state, we break out of this retry loop. We shouldn't
 633       // need this flag to prevent us from getting back here, but
 634       // sometimes paranoia is good.
 635       did_trans_retry = true;
 636 
 637       // We wait for the thread to transition to a more usable state.
 638       for (int i = 1; i <= SuspendRetryCount; i++) {
 639         // We used to do an "os::yield_all(i)" call here with the intention
 640         // that yielding would increase on each retry. However, the parameter
 641         // is ignored on Linux which means the yield didn't scale up. Waiting
 642         // on the SR_lock below provides a much more predictable scale up for
 643         // the delay. It also provides a simple/direct point to check for any
 644         // safepoint requests from the VMThread
 645 
 646         // temporarily drops SR_lock while doing wait with safepoint check
 647         // (if we're a JavaThread - the WatcherThread can also call this)
 648         // and increase delay with each retry
 649         SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 650 
 651         // check the actual thread state instead of what we saved above
 652         if (thread_state() != _thread_in_native_trans) {
 653           // the thread has transitioned to another thread state so
 654           // try all the checks (except this one) one more time.
 655           do_trans_retry = true;
 656           break;
 657         }
 658       } // end retry loop
 659 
 660 
 661     }
 662   } while (do_trans_retry);
 663 
 664   *bits |= 0x00000010;
 665   return false;
 666 }
 667 
 668 // Wait for an external suspend request to complete (or be cancelled).
 669 // Returns true if the thread is externally suspended and false otherwise.
 670 //
 671 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
 672                                                  uint32_t *bits) {
 673   TraceSuspendDebugBits tsdb(this, true /* is_wait */,
 674                              false /* !called_by_wait */, bits);
 675 
 676   // local flag copies to minimize SR_lock hold time
 677   bool is_suspended;
 678   bool pending;
 679   uint32_t reset_bits;
 680 
 681   // set a marker so is_ext_suspend_completed() knows we are the caller
 682   *bits |= 0x00010000;
 683 
 684   // We use reset_bits to reinitialize the bits value at the top of
 685   // each retry loop. This allows the caller to make use of any
 686   // unused bits for their own marking purposes.
 687   reset_bits = *bits;
 688 
 689   {
 690     MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
 691     is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 692                                             delay, bits);
 693     pending = is_external_suspend();
 694   }
 695   // must release SR_lock to allow suspension to complete
 696 
 697   if (!pending) {
 698     // A cancelled suspend request is the only false return from
 699     // is_ext_suspend_completed() that keeps us from entering the
 700     // retry loop.
 701     *bits |= 0x00020000;
 702     return false;
 703   }
 704 
 705   if (is_suspended) {
 706     *bits |= 0x00040000;
 707     return true;
 708   }
 709 
 710   for (int i = 1; i <= retries; i++) {
 711     *bits = reset_bits;  // reinit to only track last retry
 712 
 713     // We used to do an "os::yield_all(i)" call here with the intention
 714     // that yielding would increase on each retry. However, the parameter
 715     // is ignored on Linux which means the yield didn't scale up. Waiting
 716     // on the SR_lock below provides a much more predictable scale up for
 717     // the delay. It also provides a simple/direct point to check for any
 718     // safepoint requests from the VMThread
 719 
 720     {
 721       MutexLocker ml(SR_lock());
 722       // wait with safepoint check (if we're a JavaThread - the WatcherThread
 723       // can also call this)  and increase delay with each retry
 724       SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 725 
 726       is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 727                                               delay, bits);
 728 
 729       // It is possible for the external suspend request to be cancelled
 730       // (by a resume) before the actual suspend operation is completed.
 731       // Refresh our local copy to see if we still need to wait.
 732       pending = is_external_suspend();
 733     }
 734 
 735     if (!pending) {
 736       // A cancelled suspend request is the only false return from
 737       // is_ext_suspend_completed() that keeps us from staying in the
 738       // retry loop.
 739       *bits |= 0x00080000;
 740       return false;
 741     }
 742 
 743     if (is_suspended) {
 744       *bits |= 0x00100000;
 745       return true;
 746     }
 747   } // end retry loop
 748 
 749   // thread did not suspend after all our retries
 750   *bits |= 0x00200000;
 751   return false;
 752 }
 753 
 754 // Called from API entry points which perform stack walking. If the
 755 // associated JavaThread is the current thread, then wait_for_suspend
 756 // is not used. Otherwise, it determines if we should wait for the
 757 // "other" thread to complete external suspension. (NOTE: in future
 758 // releases the suspension mechanism should be reimplemented so this
 759 // is not necessary.)
 760 //
 761 bool
 762 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) {
 763   if (this != JavaThread::current()) {
 764     // "other" threads require special handling.
 765     if (wait_for_suspend) {
 766       // We are allowed to wait for the external suspend to complete
 767       // so give the other thread a chance to get suspended.
 768       if (!wait_for_ext_suspend_completion(SuspendRetryCount,
 769                                            SuspendRetryDelay, bits)) {
 770         // Didn't make it so let the caller know.
 771         return false;
 772       }
 773     }
 774     // We aren't allowed to wait for the external suspend to complete
 775     // so if the other thread isn't externally suspended we need to
 776     // let the caller know.
 777     else if (!is_ext_suspend_completed_with_lock(bits)) {
 778       return false;
 779     }
 780   }
 781 
 782   return true;
 783 }
 784 
 785 #ifndef PRODUCT
 786 void JavaThread::record_jump(address target, address instr, const char* file,
 787                              int line) {
 788 
 789   // This should not need to be atomic as the only way for simultaneous
 790   // updates is via interrupts. Even then this should be rare or non-existent
 791   // and we don't care that much anyway.
 792 
 793   int index = _jmp_ring_index;
 794   _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
 795   _jmp_ring[index]._target = (intptr_t) target;
 796   _jmp_ring[index]._instruction = (intptr_t) instr;
 797   _jmp_ring[index]._file = file;
 798   _jmp_ring[index]._line = line;
 799 }
 800 #endif // PRODUCT
 801 
 802 void Thread::interrupt(Thread* thread) {
 803   debug_only(check_for_dangling_thread_pointer(thread);)
 804   os::interrupt(thread);
 805 }
 806 
 807 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
 808   debug_only(check_for_dangling_thread_pointer(thread);)
 809   // Note:  If clear_interrupted==false, this simply fetches and
 810   // returns the value of the field osthread()->interrupted().
 811   return os::is_interrupted(thread, clear_interrupted);
 812 }
 813 
 814 
 815 // GC Support
 816 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
 817   int thread_parity = _oops_do_parity;
 818   if (thread_parity != strong_roots_parity) {
 819     jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
 820     if (res == thread_parity) {
 821       return true;
 822     } else {
 823       guarantee(res == strong_roots_parity, "Or else what?");
 824       return false;
 825     }
 826   }
 827   return false;
 828 }
 829 
 830 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
 831   active_handles()->oops_do(f);
 832   // Do oop for ThreadShadow
 833   f->do_oop((oop*)&_pending_exception);
 834   handle_area()->oops_do(f);
 835 
 836   if (MonitorInUseLists) {
 837     // When using thread local monitor lists, we scan them here,
 838     // and the remaining global monitors in ObjectSynchronizer::oops_do().
 839     ObjectSynchronizer::thread_local_used_oops_do(this, f);
 840   }
 841 }
 842 
 843 void Thread::metadata_handles_do(void f(Metadata*)) {
 844   // Only walk the Handles in Thread.
 845   if (metadata_handles() != NULL) {
 846     for (int i = 0; i< metadata_handles()->length(); i++) {
 847       f(metadata_handles()->at(i));
 848     }
 849   }
 850 }
 851 
 852 void Thread::print_on(outputStream* st) const {
 853   // get_priority assumes osthread initialized
 854   if (osthread() != NULL) {
 855     int os_prio;
 856     if (os::get_native_priority(this, &os_prio) == OS_OK) {
 857       st->print("os_prio=%d ", os_prio);
 858     }
 859     st->print("tid=" INTPTR_FORMAT " ", p2i(this));
 860     ext().print_on(st);
 861     osthread()->print_on(st);
 862   }
 863   if (_threads_hazard_ptr != NULL) {
 864     st->print("_threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr));
 865   }
 866   if (_nested_threads_hazard_ptr != NULL) {
 867     print_nested_threads_hazard_ptrs_on(st);
 868   }
 869   st->print(" ");
 870   debug_only(if (WizardMode) print_owned_locks_on(st);)
 871 }
 872 
 873 void Thread::print_nested_threads_hazard_ptrs_on(outputStream* st) const {
 874   assert(_nested_threads_hazard_ptr != NULL, "must be set to print");
 875 
 876   if (EnableThreadSMRStatistics) {
 877     st->print(", _nested_threads_hazard_ptr_cnt=%u", _nested_threads_hazard_ptr_cnt);
 878   }
 879   st->print(", _nested_threads_hazard_ptrs=");
 880   for (NestedThreadsList* node = _nested_threads_hazard_ptr; node != NULL;
 881        node = node->next()) {
 882     if (node != _nested_threads_hazard_ptr) {
 883       // First node does not need a comma-space separator.
 884       st->print(", ");
 885     }
 886     st->print(INTPTR_FORMAT, p2i(node->t_list()));
 887   }
 888 }
 889 
 890 // Thread::print_on_error() is called by fatal error handler. Don't use
 891 // any lock or allocate memory.
 892 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
 893   assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
 894 
 895   if (is_VM_thread())                 { st->print("VMThread"); }
 896   else if (is_GC_task_thread())       { st->print("GCTaskThread"); }
 897   else if (is_Watcher_thread())       { st->print("WatcherThread"); }
 898   else if (is_ConcurrentGC_thread())  { st->print("ConcurrentGCThread"); }
 899   else                                { st->print("Thread"); }
 900 
 901   if (is_Named_thread()) {
 902     st->print(" \"%s\"", name());
 903   }
 904 
 905   st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
 906             p2i(stack_end()), p2i(stack_base()));
 907 
 908   if (osthread()) {
 909     st->print(" [id=%d]", osthread()->thread_id());
 910   }
 911 
 912   if (_threads_hazard_ptr != NULL) {
 913     st->print(" _threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr));
 914   }
 915   if (_nested_threads_hazard_ptr != NULL) {
 916     print_nested_threads_hazard_ptrs_on(st);
 917   }
 918 }
 919 
 920 void Thread::print_value_on(outputStream* st) const {
 921   if (is_Named_thread()) {
 922     st->print(" \"%s\" ", name());
 923   }
 924   st->print(INTPTR_FORMAT, p2i(this));   // print address
 925 }
 926 
 927 #ifdef ASSERT
 928 void Thread::print_owned_locks_on(outputStream* st) const {
 929   Monitor *cur = _owned_locks;
 930   if (cur == NULL) {
 931     st->print(" (no locks) ");
 932   } else {
 933     st->print_cr(" Locks owned:");
 934     while (cur) {
 935       cur->print_on(st);
 936       cur = cur->next();
 937     }
 938   }
 939 }
 940 
 941 static int ref_use_count  = 0;
 942 
 943 bool Thread::owns_locks_but_compiled_lock() const {
 944   for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 945     if (cur != Compile_lock) return true;
 946   }
 947   return false;
 948 }
 949 
 950 
 951 #endif
 952 
 953 #ifndef PRODUCT
 954 
 955 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially
 956 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that
 957 // no threads which allow_vm_block's are held
 958 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
 959   // Check if current thread is allowed to block at a safepoint
 960   if (!(_allow_safepoint_count == 0)) {
 961     fatal("Possible safepoint reached by thread that does not allow it");
 962   }
 963   if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
 964     fatal("LEAF method calling lock?");
 965   }
 966 
 967 #ifdef ASSERT
 968   if (potential_vm_operation && is_Java_thread()
 969       && !Universe::is_bootstrapping()) {
 970     // Make sure we do not hold any locks that the VM thread also uses.
 971     // This could potentially lead to deadlocks
 972     for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 973       // Threads_lock is special, since the safepoint synchronization will not start before this is
 974       // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
 975       // since it is used to transfer control between JavaThreads and the VMThread
 976       // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
 977       if ((cur->allow_vm_block() &&
 978            cur != Threads_lock &&
 979            cur != Compile_lock &&               // Temporary: should not be necessary when we get separate compilation
 980            cur != VMOperationRequest_lock &&
 981            cur != VMOperationQueue_lock) ||
 982            cur->rank() == Mutex::special) {
 983         fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
 984       }
 985     }
 986   }
 987 
 988   if (GCALotAtAllSafepoints) {
 989     // We could enter a safepoint here and thus have a gc
 990     InterfaceSupport::check_gc_alot();
 991   }
 992 #endif
 993 }
 994 #endif
 995 
 996 bool Thread::is_in_stack(address adr) const {
 997   assert(Thread::current() == this, "is_in_stack can only be called from current thread");
 998   address end = os::current_stack_pointer();
 999   // Allow non Java threads to call this without stack_base
1000   if (_stack_base == NULL) return true;
1001   if (stack_base() >= adr && adr >= end) return true;
1002 
1003   return false;
1004 }
1005 
1006 bool Thread::is_in_usable_stack(address adr) const {
1007   size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
1008   size_t usable_stack_size = _stack_size - stack_guard_size;
1009 
1010   return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
1011 }
1012 
1013 
1014 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
1015 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
1016 // used for compilation in the future. If that change is made, the need for these methods
1017 // should be revisited, and they should be removed if possible.
1018 
1019 bool Thread::is_lock_owned(address adr) const {
1020   return on_local_stack(adr);
1021 }
1022 
1023 bool Thread::set_as_starting_thread() {
1024   // NOTE: this must be called inside the main thread.
1025   return os::create_main_thread((JavaThread*)this);
1026 }
1027 
1028 static void initialize_class(Symbol* class_name, TRAPS) {
1029   Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
1030   InstanceKlass::cast(klass)->initialize(CHECK);
1031 }
1032 
1033 
1034 // Creates the initial ThreadGroup
1035 static Handle create_initial_thread_group(TRAPS) {
1036   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
1037   InstanceKlass* ik = InstanceKlass::cast(k);
1038 
1039   Handle system_instance = ik->allocate_instance_handle(CHECK_NH);
1040   {
1041     JavaValue result(T_VOID);
1042     JavaCalls::call_special(&result,
1043                             system_instance,
1044                             ik,
1045                             vmSymbols::object_initializer_name(),
1046                             vmSymbols::void_method_signature(),
1047                             CHECK_NH);
1048   }
1049   Universe::set_system_thread_group(system_instance());
1050 
1051   Handle main_instance = ik->allocate_instance_handle(CHECK_NH);
1052   {
1053     JavaValue result(T_VOID);
1054     Handle string = java_lang_String::create_from_str("main", CHECK_NH);
1055     JavaCalls::call_special(&result,
1056                             main_instance,
1057                             ik,
1058                             vmSymbols::object_initializer_name(),
1059                             vmSymbols::threadgroup_string_void_signature(),
1060                             system_instance,
1061                             string,
1062                             CHECK_NH);
1063   }
1064   return main_instance;
1065 }
1066 
1067 // Creates the initial Thread
1068 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
1069                                  TRAPS) {
1070   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
1071   InstanceKlass* ik = InstanceKlass::cast(k);
1072   instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
1073 
1074   java_lang_Thread::set_thread(thread_oop(), thread);
1075   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1076   thread->set_threadObj(thread_oop());
1077 
1078   Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1079 
1080   JavaValue result(T_VOID);
1081   JavaCalls::call_special(&result, thread_oop,
1082                           ik,
1083                           vmSymbols::object_initializer_name(),
1084                           vmSymbols::threadgroup_string_void_signature(),
1085                           thread_group,
1086                           string,
1087                           CHECK_NULL);
1088   return thread_oop();
1089 }
1090 
1091 char java_runtime_name[128] = "";
1092 char java_runtime_version[128] = "";
1093 
1094 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1095 static const char* get_java_runtime_name(TRAPS) {
1096   Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1097                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1098   fieldDescriptor fd;
1099   bool found = k != NULL &&
1100                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1101                                                         vmSymbols::string_signature(), &fd);
1102   if (found) {
1103     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1104     if (name_oop == NULL) {
1105       return NULL;
1106     }
1107     const char* name = java_lang_String::as_utf8_string(name_oop,
1108                                                         java_runtime_name,
1109                                                         sizeof(java_runtime_name));
1110     return name;
1111   } else {
1112     return NULL;
1113   }
1114 }
1115 
1116 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1117 static const char* get_java_runtime_version(TRAPS) {
1118   Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1119                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1120   fieldDescriptor fd;
1121   bool found = k != NULL &&
1122                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1123                                                         vmSymbols::string_signature(), &fd);
1124   if (found) {
1125     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1126     if (name_oop == NULL) {
1127       return NULL;
1128     }
1129     const char* name = java_lang_String::as_utf8_string(name_oop,
1130                                                         java_runtime_version,
1131                                                         sizeof(java_runtime_version));
1132     return name;
1133   } else {
1134     return NULL;
1135   }
1136 }
1137 
1138 // General purpose hook into Java code, run once when the VM is initialized.
1139 // The Java library method itself may be changed independently from the VM.
1140 static void call_postVMInitHook(TRAPS) {
1141   Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1142   if (klass != NULL) {
1143     JavaValue result(T_VOID);
1144     JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1145                            vmSymbols::void_method_signature(),
1146                            CHECK);
1147   }
1148 }
1149 
1150 static void reset_vm_info_property(TRAPS) {
1151   // the vm info string
1152   ResourceMark rm(THREAD);
1153   const char *vm_info = VM_Version::vm_info_string();
1154 
1155   // java.lang.System class
1156   Klass* klass =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1157 
1158   // setProperty arguments
1159   Handle key_str    = java_lang_String::create_from_str("java.vm.info", CHECK);
1160   Handle value_str  = java_lang_String::create_from_str(vm_info, CHECK);
1161 
1162   // return value
1163   JavaValue r(T_OBJECT);
1164 
1165   // public static String setProperty(String key, String value);
1166   JavaCalls::call_static(&r,
1167                          klass,
1168                          vmSymbols::setProperty_name(),
1169                          vmSymbols::string_string_string_signature(),
1170                          key_str,
1171                          value_str,
1172                          CHECK);
1173 }
1174 
1175 
1176 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1177                                     bool daemon, TRAPS) {
1178   assert(thread_group.not_null(), "thread group should be specified");
1179   assert(threadObj() == NULL, "should only create Java thread object once");
1180 
1181   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1182   InstanceKlass* ik = InstanceKlass::cast(k);
1183   instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1184 
1185   java_lang_Thread::set_thread(thread_oop(), this);
1186   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1187   set_threadObj(thread_oop());
1188 
1189   JavaValue result(T_VOID);
1190   if (thread_name != NULL) {
1191     Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1192     // Thread gets assigned specified name and null target
1193     JavaCalls::call_special(&result,
1194                             thread_oop,
1195                             ik,
1196                             vmSymbols::object_initializer_name(),
1197                             vmSymbols::threadgroup_string_void_signature(),
1198                             thread_group, // Argument 1
1199                             name,         // Argument 2
1200                             THREAD);
1201   } else {
1202     // Thread gets assigned name "Thread-nnn" and null target
1203     // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1204     JavaCalls::call_special(&result,
1205                             thread_oop,
1206                             ik,
1207                             vmSymbols::object_initializer_name(),
1208                             vmSymbols::threadgroup_runnable_void_signature(),
1209                             thread_group, // Argument 1
1210                             Handle(),     // Argument 2
1211                             THREAD);
1212   }
1213 
1214 
1215   if (daemon) {
1216     java_lang_Thread::set_daemon(thread_oop());
1217   }
1218 
1219   if (HAS_PENDING_EXCEPTION) {
1220     return;
1221   }
1222 
1223   Klass* group =  SystemDictionary::ThreadGroup_klass();
1224   Handle threadObj(THREAD, this->threadObj());
1225 
1226   JavaCalls::call_special(&result,
1227                           thread_group,
1228                           group,
1229                           vmSymbols::add_method_name(),
1230                           vmSymbols::thread_void_signature(),
1231                           threadObj,          // Arg 1
1232                           THREAD);
1233 }
1234 
1235 // NamedThread --  non-JavaThread subclasses with multiple
1236 // uniquely named instances should derive from this.
1237 NamedThread::NamedThread() : Thread() {
1238   _name = NULL;
1239   _processed_thread = NULL;
1240   _gc_id = GCId::undefined();
1241 }
1242 
1243 NamedThread::~NamedThread() {
1244   if (_name != NULL) {
1245     FREE_C_HEAP_ARRAY(char, _name);
1246     _name = NULL;
1247   }
1248 }
1249 
1250 void NamedThread::set_name(const char* format, ...) {
1251   guarantee(_name == NULL, "Only get to set name once.");
1252   _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1253   guarantee(_name != NULL, "alloc failure");
1254   va_list ap;
1255   va_start(ap, format);
1256   jio_vsnprintf(_name, max_name_len, format, ap);
1257   va_end(ap);
1258 }
1259 
1260 void NamedThread::initialize_named_thread() {
1261   set_native_thread_name(name());
1262 }
1263 
1264 void NamedThread::print_on(outputStream* st) const {
1265   st->print("\"%s\" ", name());
1266   Thread::print_on(st);
1267   st->cr();
1268 }
1269 
1270 
1271 // ======= WatcherThread ========
1272 
1273 // The watcher thread exists to simulate timer interrupts.  It should
1274 // be replaced by an abstraction over whatever native support for
1275 // timer interrupts exists on the platform.
1276 
1277 WatcherThread* WatcherThread::_watcher_thread   = NULL;
1278 bool WatcherThread::_startable = false;
1279 volatile bool  WatcherThread::_should_terminate = false;
1280 
1281 WatcherThread::WatcherThread() : Thread() {
1282   assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1283   if (os::create_thread(this, os::watcher_thread)) {
1284     _watcher_thread = this;
1285 
1286     // Set the watcher thread to the highest OS priority which should not be
1287     // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1288     // is created. The only normal thread using this priority is the reference
1289     // handler thread, which runs for very short intervals only.
1290     // If the VMThread's priority is not lower than the WatcherThread profiling
1291     // will be inaccurate.
1292     os::set_priority(this, MaxPriority);
1293     if (!DisableStartThread) {
1294       os::start_thread(this);
1295     }
1296   }
1297 }
1298 
1299 int WatcherThread::sleep() const {
1300   // The WatcherThread does not participate in the safepoint protocol
1301   // for the PeriodicTask_lock because it is not a JavaThread.
1302   MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1303 
1304   if (_should_terminate) {
1305     // check for termination before we do any housekeeping or wait
1306     return 0;  // we did not sleep.
1307   }
1308 
1309   // remaining will be zero if there are no tasks,
1310   // causing the WatcherThread to sleep until a task is
1311   // enrolled
1312   int remaining = PeriodicTask::time_to_wait();
1313   int time_slept = 0;
1314 
1315   // we expect this to timeout - we only ever get unparked when
1316   // we should terminate or when a new task has been enrolled
1317   OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1318 
1319   jlong time_before_loop = os::javaTimeNanos();
1320 
1321   while (true) {
1322     bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1323                                             remaining);
1324     jlong now = os::javaTimeNanos();
1325 
1326     if (remaining == 0) {
1327       // if we didn't have any tasks we could have waited for a long time
1328       // consider the time_slept zero and reset time_before_loop
1329       time_slept = 0;
1330       time_before_loop = now;
1331     } else {
1332       // need to recalculate since we might have new tasks in _tasks
1333       time_slept = (int) ((now - time_before_loop) / 1000000);
1334     }
1335 
1336     // Change to task list or spurious wakeup of some kind
1337     if (timedout || _should_terminate) {
1338       break;
1339     }
1340 
1341     remaining = PeriodicTask::time_to_wait();
1342     if (remaining == 0) {
1343       // Last task was just disenrolled so loop around and wait until
1344       // another task gets enrolled
1345       continue;
1346     }
1347 
1348     remaining -= time_slept;
1349     if (remaining <= 0) {
1350       break;
1351     }
1352   }
1353 
1354   return time_slept;
1355 }
1356 
1357 void WatcherThread::run() {
1358   assert(this == watcher_thread(), "just checking");
1359 
1360   this->record_stack_base_and_size();
1361   this->set_native_thread_name(this->name());
1362   this->set_active_handles(JNIHandleBlock::allocate_block());
1363   while (true) {
1364     assert(watcher_thread() == Thread::current(), "thread consistency check");
1365     assert(watcher_thread() == this, "thread consistency check");
1366 
1367     // Calculate how long it'll be until the next PeriodicTask work
1368     // should be done, and sleep that amount of time.
1369     int time_waited = sleep();
1370 
1371     if (VMError::is_error_reported()) {
1372       // A fatal error has happened, the error handler(VMError::report_and_die)
1373       // should abort JVM after creating an error log file. However in some
1374       // rare cases, the error handler itself might deadlock. Here periodically
1375       // check for error reporting timeouts, and if it happens, just proceed to
1376       // abort the VM.
1377 
1378       // This code is in WatcherThread because WatcherThread wakes up
1379       // periodically so the fatal error handler doesn't need to do anything;
1380       // also because the WatcherThread is less likely to crash than other
1381       // threads.
1382 
1383       for (;;) {
1384         // Note: we use naked sleep in this loop because we want to avoid using
1385         // any kind of VM infrastructure which may be broken at this point.
1386         if (VMError::check_timeout()) {
1387           // We hit error reporting timeout. Error reporting was interrupted and
1388           // will be wrapping things up now (closing files etc). Give it some more
1389           // time, then quit the VM.
1390           os::naked_short_sleep(200);
1391           // Print a message to stderr.
1392           fdStream err(defaultStream::output_fd());
1393           err.print_raw_cr("# [ timer expired, abort... ]");
1394           // skip atexit/vm_exit/vm_abort hooks
1395           os::die();
1396         }
1397 
1398         // Wait a second, then recheck for timeout.
1399         os::naked_short_sleep(999);
1400       }
1401     }
1402 
1403     if (_should_terminate) {
1404       // check for termination before posting the next tick
1405       break;
1406     }
1407 
1408     PeriodicTask::real_time_tick(time_waited);
1409   }
1410 
1411   // Signal that it is terminated
1412   {
1413     MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1414     _watcher_thread = NULL;
1415     Terminator_lock->notify();
1416   }
1417 }
1418 
1419 void WatcherThread::start() {
1420   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1421 
1422   if (watcher_thread() == NULL && _startable) {
1423     _should_terminate = false;
1424     // Create the single instance of WatcherThread
1425     new WatcherThread();
1426   }
1427 }
1428 
1429 void WatcherThread::make_startable() {
1430   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1431   _startable = true;
1432 }
1433 
1434 void WatcherThread::stop() {
1435   {
1436     // Follow normal safepoint aware lock enter protocol since the
1437     // WatcherThread is stopped by another JavaThread.
1438     MutexLocker ml(PeriodicTask_lock);
1439     _should_terminate = true;
1440 
1441     WatcherThread* watcher = watcher_thread();
1442     if (watcher != NULL) {
1443       // unpark the WatcherThread so it can see that it should terminate
1444       watcher->unpark();
1445     }
1446   }
1447 
1448   MutexLocker mu(Terminator_lock);
1449 
1450   while (watcher_thread() != NULL) {
1451     // This wait should make safepoint checks, wait without a timeout,
1452     // and wait as a suspend-equivalent condition.
1453     Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1454                           Mutex::_as_suspend_equivalent_flag);
1455   }
1456 }
1457 
1458 void WatcherThread::unpark() {
1459   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1460   PeriodicTask_lock->notify();
1461 }
1462 
1463 void WatcherThread::print_on(outputStream* st) const {
1464   st->print("\"%s\" ", name());
1465   Thread::print_on(st);
1466   st->cr();
1467 }
1468 
1469 // ======= JavaThread ========
1470 
1471 #if INCLUDE_JVMCI
1472 
1473 jlong* JavaThread::_jvmci_old_thread_counters;
1474 
1475 bool jvmci_counters_include(JavaThread* thread) {
1476   oop threadObj = thread->threadObj();
1477   return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1478 }
1479 
1480 void JavaThread::collect_counters(typeArrayOop array) {
1481   if (JVMCICounterSize > 0) {
1482     MutexLocker tl(Threads_lock);
1483     JavaThreadIteratorWithHandle jtiwh;
1484     for (int i = 0; i < array->length(); i++) {
1485       array->long_at_put(i, _jvmci_old_thread_counters[i]);
1486     }
1487     for (; JavaThread *tp = jtiwh.next(); ) {
1488       if (jvmci_counters_include(tp)) {
1489         for (int i = 0; i < array->length(); i++) {
1490           array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1491         }
1492       }
1493     }
1494   }
1495 }
1496 
1497 #endif // INCLUDE_JVMCI
1498 
1499 // A JavaThread is a normal Java thread
1500 
1501 void JavaThread::initialize() {
1502   // Initialize fields
1503 
1504   set_saved_exception_pc(NULL);
1505   set_threadObj(NULL);
1506   _anchor.clear();
1507   set_entry_point(NULL);
1508   set_jni_functions(jni_functions());
1509   set_callee_target(NULL);
1510   set_vm_result(NULL);
1511   set_vm_result_2(NULL);
1512   set_vframe_array_head(NULL);
1513   set_vframe_array_last(NULL);
1514   set_deferred_locals(NULL);
1515   set_deopt_mark(NULL);
1516   set_deopt_compiled_method(NULL);
1517   clear_must_deopt_id();
1518   set_monitor_chunks(NULL);
1519   set_next(NULL);
1520   _on_thread_list = false;
1521   set_thread_state(_thread_new);
1522   _terminated = _not_terminated;
1523   _privileged_stack_top = NULL;
1524   _array_for_gc = NULL;
1525   _suspend_equivalent = false;
1526   _in_deopt_handler = 0;
1527   _doing_unsafe_access = false;
1528   _stack_guard_state = stack_guard_unused;
1529 #if INCLUDE_JVMCI
1530   _pending_monitorenter = false;
1531   _pending_deoptimization = -1;
1532   _pending_failed_speculation = NULL;
1533   _pending_transfer_to_interpreter = false;
1534   _adjusting_comp_level = false;
1535   _jvmci._alternate_call_target = NULL;
1536   assert(_jvmci._implicit_exception_pc == NULL, "must be");
1537   if (JVMCICounterSize > 0) {
1538     _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1539     memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1540   } else {
1541     _jvmci_counters = NULL;
1542   }
1543 #endif // INCLUDE_JVMCI
1544   _reserved_stack_activation = NULL;  // stack base not known yet
1545   (void)const_cast<oop&>(_exception_oop = oop(NULL));
1546   _exception_pc  = 0;
1547   _exception_handler_pc = 0;
1548   _is_method_handle_return = 0;
1549   _jvmti_thread_state= NULL;
1550   _should_post_on_exceptions_flag = JNI_FALSE;
1551   _jvmti_get_loaded_classes_closure = NULL;
1552   _interp_only_mode    = 0;
1553   _special_runtime_exit_condition = _no_async_condition;
1554   _pending_async_exception = NULL;
1555   _thread_stat = NULL;
1556   _thread_stat = new ThreadStatistics();
1557   _blocked_on_compilation = false;
1558   _jni_active_critical = 0;
1559   _pending_jni_exception_check_fn = NULL;
1560   _do_not_unlock_if_synchronized = false;
1561   _cached_monitor_info = NULL;
1562   _parker = Parker::Allocate(this);
1563 
1564 #ifndef PRODUCT
1565   _jmp_ring_index = 0;
1566   for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1567     record_jump(NULL, NULL, NULL, 0);
1568   }
1569 #endif // PRODUCT
1570 
1571   // Setup safepoint state info for this thread
1572   ThreadSafepointState::create(this);
1573 
1574   debug_only(_java_call_counter = 0);
1575 
1576   // JVMTI PopFrame support
1577   _popframe_condition = popframe_inactive;
1578   _popframe_preserved_args = NULL;
1579   _popframe_preserved_args_size = 0;
1580   _frames_to_pop_failed_realloc = 0;
1581 
1582   if (SafepointMechanism::uses_thread_local_poll()) {
1583     SafepointMechanism::initialize_header(this);
1584   }
1585 
1586   pd_initialize();
1587 }
1588 
1589 #if INCLUDE_ALL_GCS
1590 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1591 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1592 #endif // INCLUDE_ALL_GCS
1593 
1594 JavaThread::JavaThread(bool is_attaching_via_jni) :
1595                        Thread()
1596 #if INCLUDE_ALL_GCS
1597                        , _satb_mark_queue(&_satb_mark_queue_set),
1598                        _dirty_card_queue(&_dirty_card_queue_set)
1599 #endif // INCLUDE_ALL_GCS
1600 {
1601   initialize();
1602   if (is_attaching_via_jni) {
1603     _jni_attach_state = _attaching_via_jni;
1604   } else {
1605     _jni_attach_state = _not_attaching_via_jni;
1606   }
1607   assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1608 }
1609 
1610 bool JavaThread::reguard_stack(address cur_sp) {
1611   if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1612       && _stack_guard_state != stack_guard_reserved_disabled) {
1613     return true; // Stack already guarded or guard pages not needed.
1614   }
1615 
1616   if (register_stack_overflow()) {
1617     // For those architectures which have separate register and
1618     // memory stacks, we must check the register stack to see if
1619     // it has overflowed.
1620     return false;
1621   }
1622 
1623   // Java code never executes within the yellow zone: the latter is only
1624   // there to provoke an exception during stack banging.  If java code
1625   // is executing there, either StackShadowPages should be larger, or
1626   // some exception code in c1, c2 or the interpreter isn't unwinding
1627   // when it should.
1628   guarantee(cur_sp > stack_reserved_zone_base(),
1629             "not enough space to reguard - increase StackShadowPages");
1630   if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1631     enable_stack_yellow_reserved_zone();
1632     if (reserved_stack_activation() != stack_base()) {
1633       set_reserved_stack_activation(stack_base());
1634     }
1635   } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1636     set_reserved_stack_activation(stack_base());
1637     enable_stack_reserved_zone();
1638   }
1639   return true;
1640 }
1641 
1642 bool JavaThread::reguard_stack(void) {
1643   return reguard_stack(os::current_stack_pointer());
1644 }
1645 
1646 
1647 void JavaThread::block_if_vm_exited() {
1648   if (_terminated == _vm_exited) {
1649     // _vm_exited is set at safepoint, and Threads_lock is never released
1650     // we will block here forever
1651     Threads_lock->lock_without_safepoint_check();
1652     ShouldNotReachHere();
1653   }
1654 }
1655 
1656 
1657 // Remove this ifdef when C1 is ported to the compiler interface.
1658 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1659 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1660 
1661 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1662                        Thread()
1663 #if INCLUDE_ALL_GCS
1664                        , _satb_mark_queue(&_satb_mark_queue_set),
1665                        _dirty_card_queue(&_dirty_card_queue_set)
1666 #endif // INCLUDE_ALL_GCS
1667 {
1668   initialize();
1669   _jni_attach_state = _not_attaching_via_jni;
1670   set_entry_point(entry_point);
1671   // Create the native thread itself.
1672   // %note runtime_23
1673   os::ThreadType thr_type = os::java_thread;
1674   thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1675                                                      os::java_thread;
1676   os::create_thread(this, thr_type, stack_sz);
1677   // The _osthread may be NULL here because we ran out of memory (too many threads active).
1678   // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1679   // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1680   // the exception consists of creating the exception object & initializing it, initialization
1681   // will leave the VM via a JavaCall and then all locks must be unlocked).
1682   //
1683   // The thread is still suspended when we reach here. Thread must be explicit started
1684   // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1685   // by calling Threads:add. The reason why this is not done here, is because the thread
1686   // object must be fully initialized (take a look at JVM_Start)
1687 }
1688 
1689 JavaThread::~JavaThread() {
1690 
1691   // JSR166 -- return the parker to the free list
1692   Parker::Release(_parker);
1693   _parker = NULL;
1694 
1695   // Free any remaining  previous UnrollBlock
1696   vframeArray* old_array = vframe_array_last();
1697 
1698   if (old_array != NULL) {
1699     Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1700     old_array->set_unroll_block(NULL);
1701     delete old_info;
1702     delete old_array;
1703   }
1704 
1705   GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1706   if (deferred != NULL) {
1707     // This can only happen if thread is destroyed before deoptimization occurs.
1708     assert(deferred->length() != 0, "empty array!");
1709     do {
1710       jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1711       deferred->remove_at(0);
1712       // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1713       delete dlv;
1714     } while (deferred->length() != 0);
1715     delete deferred;
1716   }
1717 
1718   // All Java related clean up happens in exit
1719   ThreadSafepointState::destroy(this);
1720   if (_thread_stat != NULL) delete _thread_stat;
1721 
1722 #if INCLUDE_JVMCI
1723   if (JVMCICounterSize > 0) {
1724     if (jvmci_counters_include(this)) {
1725       for (int i = 0; i < JVMCICounterSize; i++) {
1726         _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1727       }
1728     }
1729     FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1730   }
1731 #endif // INCLUDE_JVMCI
1732 }
1733 
1734 
1735 // The first routine called by a new Java thread
1736 void JavaThread::run() {
1737   // initialize thread-local alloc buffer related fields
1738   this->initialize_tlab();
1739 
1740   // used to test validity of stack trace backs
1741   this->record_base_of_stack_pointer();
1742 
1743   // Record real stack base and size.
1744   this->record_stack_base_and_size();
1745 
1746   this->create_stack_guard_pages();
1747 
1748   this->cache_global_variables();
1749 
1750   // Thread is now sufficient initialized to be handled by the safepoint code as being
1751   // in the VM. Change thread state from _thread_new to _thread_in_vm
1752   ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1753 
1754   assert(JavaThread::current() == this, "sanity check");
1755   assert(!Thread::current()->owns_locks(), "sanity check");
1756 
1757   DTRACE_THREAD_PROBE(start, this);
1758 
1759   // This operation might block. We call that after all safepoint checks for a new thread has
1760   // been completed.
1761   this->set_active_handles(JNIHandleBlock::allocate_block());
1762 
1763   if (JvmtiExport::should_post_thread_life()) {
1764     JvmtiExport::post_thread_start(this);
1765   }
1766 
1767   EventThreadStart event;
1768   if (event.should_commit()) {
1769     event.set_thread(THREAD_TRACE_ID(this));
1770     event.commit();
1771   }
1772 
1773   // We call another function to do the rest so we are sure that the stack addresses used
1774   // from there will be lower than the stack base just computed
1775   thread_main_inner();
1776 
1777   // Note, thread is no longer valid at this point!
1778 }
1779 
1780 
1781 void JavaThread::thread_main_inner() {
1782   assert(JavaThread::current() == this, "sanity check");
1783   assert(this->threadObj() != NULL, "just checking");
1784 
1785   // Execute thread entry point unless this thread has a pending exception
1786   // or has been stopped before starting.
1787   // Note: Due to JVM_StopThread we can have pending exceptions already!
1788   if (!this->has_pending_exception() &&
1789       !java_lang_Thread::is_stillborn(this->threadObj())) {
1790     {
1791       ResourceMark rm(this);
1792       this->set_native_thread_name(this->get_thread_name());
1793     }
1794     HandleMark hm(this);
1795     this->entry_point()(this, this);
1796   }
1797 
1798   DTRACE_THREAD_PROBE(stop, this);
1799 
1800   this->exit(false);
1801   this->smr_delete();
1802 }
1803 
1804 
1805 static void ensure_join(JavaThread* thread) {
1806   // We do not need to grab the Threads_lock, since we are operating on ourself.
1807   Handle threadObj(thread, thread->threadObj());
1808   assert(threadObj.not_null(), "java thread object must exist");
1809   ObjectLocker lock(threadObj, thread);
1810   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1811   thread->clear_pending_exception();
1812   // Thread is exiting. So set thread_status field in  java.lang.Thread class to TERMINATED.
1813   java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1814   // Clear the native thread instance - this makes isAlive return false and allows the join()
1815   // to complete once we've done the notify_all below
1816   java_lang_Thread::set_thread(threadObj(), NULL);
1817   lock.notify_all(thread);
1818   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1819   thread->clear_pending_exception();
1820 }
1821 
1822 
1823 // For any new cleanup additions, please check to see if they need to be applied to
1824 // cleanup_failed_attach_current_thread as well.
1825 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1826   assert(this == JavaThread::current(), "thread consistency check");
1827 
1828   elapsedTimer _timer_exit_phase1;
1829   elapsedTimer _timer_exit_phase2;
1830   elapsedTimer _timer_exit_phase3;
1831   elapsedTimer _timer_exit_phase4;
1832 
1833   if (log_is_enabled(Debug, os, thread, timer)) {
1834     _timer_exit_phase1.start();
1835   }
1836 
1837   HandleMark hm(this);
1838   Handle uncaught_exception(this, this->pending_exception());
1839   this->clear_pending_exception();
1840   Handle threadObj(this, this->threadObj());
1841   assert(threadObj.not_null(), "Java thread object should be created");
1842 
1843   // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1844   {
1845     EXCEPTION_MARK;
1846 
1847     CLEAR_PENDING_EXCEPTION;
1848   }
1849   if (!destroy_vm) {
1850     if (uncaught_exception.not_null()) {
1851       EXCEPTION_MARK;
1852       // Call method Thread.dispatchUncaughtException().
1853       Klass* thread_klass = SystemDictionary::Thread_klass();
1854       JavaValue result(T_VOID);
1855       JavaCalls::call_virtual(&result,
1856                               threadObj, thread_klass,
1857                               vmSymbols::dispatchUncaughtException_name(),
1858                               vmSymbols::throwable_void_signature(),
1859                               uncaught_exception,
1860                               THREAD);
1861       if (HAS_PENDING_EXCEPTION) {
1862         ResourceMark rm(this);
1863         jio_fprintf(defaultStream::error_stream(),
1864                     "\nException: %s thrown from the UncaughtExceptionHandler"
1865                     " in thread \"%s\"\n",
1866                     pending_exception()->klass()->external_name(),
1867                     get_thread_name());
1868         CLEAR_PENDING_EXCEPTION;
1869       }
1870     }
1871 
1872     // Called before the java thread exit since we want to read info
1873     // from java_lang_Thread object
1874     EventThreadEnd event;
1875     if (event.should_commit()) {
1876       event.set_thread(THREAD_TRACE_ID(this));
1877       event.commit();
1878     }
1879 
1880     // Call after last event on thread
1881     EVENT_THREAD_EXIT(this);
1882 
1883     // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1884     // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1885     // is deprecated anyhow.
1886     if (!is_Compiler_thread()) {
1887       int count = 3;
1888       while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1889         EXCEPTION_MARK;
1890         JavaValue result(T_VOID);
1891         Klass* thread_klass = SystemDictionary::Thread_klass();
1892         JavaCalls::call_virtual(&result,
1893                                 threadObj, thread_klass,
1894                                 vmSymbols::exit_method_name(),
1895                                 vmSymbols::void_method_signature(),
1896                                 THREAD);
1897         CLEAR_PENDING_EXCEPTION;
1898       }
1899     }
1900     // notify JVMTI
1901     if (JvmtiExport::should_post_thread_life()) {
1902       JvmtiExport::post_thread_end(this);
1903     }
1904 
1905     // We have notified the agents that we are exiting, before we go on,
1906     // we must check for a pending external suspend request and honor it
1907     // in order to not surprise the thread that made the suspend request.
1908     while (true) {
1909       {
1910         MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1911         if (!is_external_suspend()) {
1912           set_terminated(_thread_exiting);
1913           ThreadService::current_thread_exiting(this);
1914           break;
1915         }
1916         // Implied else:
1917         // Things get a little tricky here. We have a pending external
1918         // suspend request, but we are holding the SR_lock so we
1919         // can't just self-suspend. So we temporarily drop the lock
1920         // and then self-suspend.
1921       }
1922 
1923       ThreadBlockInVM tbivm(this);
1924       java_suspend_self();
1925 
1926       // We're done with this suspend request, but we have to loop around
1927       // and check again. Eventually we will get SR_lock without a pending
1928       // external suspend request and will be able to mark ourselves as
1929       // exiting.
1930     }
1931     // no more external suspends are allowed at this point
1932   } else {
1933     // before_exit() has already posted JVMTI THREAD_END events
1934   }
1935 
1936   if (log_is_enabled(Debug, os, thread, timer)) {
1937     _timer_exit_phase1.stop();
1938     _timer_exit_phase2.start();
1939   }
1940   // Notify waiters on thread object. This has to be done after exit() is called
1941   // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1942   // group should have the destroyed bit set before waiters are notified).
1943   ensure_join(this);
1944   assert(!this->has_pending_exception(), "ensure_join should have cleared");
1945 
1946   if (log_is_enabled(Debug, os, thread, timer)) {
1947     _timer_exit_phase2.stop();
1948     _timer_exit_phase3.start();
1949   }
1950   // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1951   // held by this thread must be released. The spec does not distinguish
1952   // between JNI-acquired and regular Java monitors. We can only see
1953   // regular Java monitors here if monitor enter-exit matching is broken.
1954   //
1955   // Optionally release any monitors for regular JavaThread exits. This
1956   // is provided as a work around for any bugs in monitor enter-exit
1957   // matching. This can be expensive so it is not enabled by default.
1958   //
1959   // ensure_join() ignores IllegalThreadStateExceptions, and so does
1960   // ObjectSynchronizer::release_monitors_owned_by_thread().
1961   if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) {
1962     // Sanity check even though JNI DetachCurrentThread() would have
1963     // returned JNI_ERR if there was a Java frame. JavaThread exit
1964     // should be done executing Java code by the time we get here.
1965     assert(!this->has_last_Java_frame(),
1966            "should not have a Java frame when detaching or exiting");
1967     ObjectSynchronizer::release_monitors_owned_by_thread(this);
1968     assert(!this->has_pending_exception(), "release_monitors should have cleared");
1969   }
1970 
1971   // These things needs to be done while we are still a Java Thread. Make sure that thread
1972   // is in a consistent state, in case GC happens
1973   assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1974 
1975   if (active_handles() != NULL) {
1976     JNIHandleBlock* block = active_handles();
1977     set_active_handles(NULL);
1978     JNIHandleBlock::release_block(block);
1979   }
1980 
1981   if (free_handle_block() != NULL) {
1982     JNIHandleBlock* block = free_handle_block();
1983     set_free_handle_block(NULL);
1984     JNIHandleBlock::release_block(block);
1985   }
1986 
1987   // These have to be removed while this is still a valid thread.
1988   remove_stack_guard_pages();
1989 
1990   if (UseTLAB) {
1991     tlab().make_parsable(true);  // retire TLAB
1992   }
1993 
1994   if (JvmtiEnv::environments_might_exist()) {
1995     JvmtiExport::cleanup_thread(this);
1996   }
1997 
1998   BarrierSet::barrier_set()->on_thread_detach(this);
1999 
2000   log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
2001     exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
2002     os::current_thread_id());
2003 
2004   if (log_is_enabled(Debug, os, thread, timer)) {
2005     _timer_exit_phase3.stop();
2006     _timer_exit_phase4.start();
2007   }
2008   // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
2009   Threads::remove(this);
2010 
2011   if (log_is_enabled(Debug, os, thread, timer)) {
2012     _timer_exit_phase4.stop();
2013     ResourceMark rm(this);
2014     log_debug(os, thread, timer)("name='%s'"
2015                                  ", exit-phase1=" JLONG_FORMAT
2016                                  ", exit-phase2=" JLONG_FORMAT
2017                                  ", exit-phase3=" JLONG_FORMAT
2018                                  ", exit-phase4=" JLONG_FORMAT,
2019                                  get_thread_name(),
2020                                  _timer_exit_phase1.milliseconds(),
2021                                  _timer_exit_phase2.milliseconds(),
2022                                  _timer_exit_phase3.milliseconds(),
2023                                  _timer_exit_phase4.milliseconds());
2024   }
2025 }
2026 
2027 void JavaThread::cleanup_failed_attach_current_thread() {
2028   if (active_handles() != NULL) {
2029     JNIHandleBlock* block = active_handles();
2030     set_active_handles(NULL);
2031     JNIHandleBlock::release_block(block);
2032   }
2033 
2034   if (free_handle_block() != NULL) {
2035     JNIHandleBlock* block = free_handle_block();
2036     set_free_handle_block(NULL);
2037     JNIHandleBlock::release_block(block);
2038   }
2039 
2040   // These have to be removed while this is still a valid thread.
2041   remove_stack_guard_pages();
2042 
2043   if (UseTLAB) {
2044     tlab().make_parsable(true);  // retire TLAB, if any
2045   }
2046 
2047   BarrierSet::barrier_set()->on_thread_detach(this);
2048 
2049   Threads::remove(this);
2050   this->smr_delete();
2051 }
2052 
2053 JavaThread* JavaThread::active() {
2054   Thread* thread = Thread::current();
2055   if (thread->is_Java_thread()) {
2056     return (JavaThread*) thread;
2057   } else {
2058     assert(thread->is_VM_thread(), "this must be a vm thread");
2059     VM_Operation* op = ((VMThread*) thread)->vm_operation();
2060     JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2061     assert(ret->is_Java_thread(), "must be a Java thread");
2062     return ret;
2063   }
2064 }
2065 
2066 bool JavaThread::is_lock_owned(address adr) const {
2067   if (Thread::is_lock_owned(adr)) return true;
2068 
2069   for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2070     if (chunk->contains(adr)) return true;
2071   }
2072 
2073   return false;
2074 }
2075 
2076 
2077 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2078   chunk->set_next(monitor_chunks());
2079   set_monitor_chunks(chunk);
2080 }
2081 
2082 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2083   guarantee(monitor_chunks() != NULL, "must be non empty");
2084   if (monitor_chunks() == chunk) {
2085     set_monitor_chunks(chunk->next());
2086   } else {
2087     MonitorChunk* prev = monitor_chunks();
2088     while (prev->next() != chunk) prev = prev->next();
2089     prev->set_next(chunk->next());
2090   }
2091 }
2092 
2093 // JVM support.
2094 
2095 // Note: this function shouldn't block if it's called in
2096 // _thread_in_native_trans state (such as from
2097 // check_special_condition_for_native_trans()).
2098 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2099 
2100   if (has_last_Java_frame() && has_async_condition()) {
2101     // If we are at a polling page safepoint (not a poll return)
2102     // then we must defer async exception because live registers
2103     // will be clobbered by the exception path. Poll return is
2104     // ok because the call we a returning from already collides
2105     // with exception handling registers and so there is no issue.
2106     // (The exception handling path kills call result registers but
2107     //  this is ok since the exception kills the result anyway).
2108 
2109     if (is_at_poll_safepoint()) {
2110       // if the code we are returning to has deoptimized we must defer
2111       // the exception otherwise live registers get clobbered on the
2112       // exception path before deoptimization is able to retrieve them.
2113       //
2114       RegisterMap map(this, false);
2115       frame caller_fr = last_frame().sender(&map);
2116       assert(caller_fr.is_compiled_frame(), "what?");
2117       if (caller_fr.is_deoptimized_frame()) {
2118         log_info(exceptions)("deferred async exception at compiled safepoint");
2119         return;
2120       }
2121     }
2122   }
2123 
2124   JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2125   if (condition == _no_async_condition) {
2126     // Conditions have changed since has_special_runtime_exit_condition()
2127     // was called:
2128     // - if we were here only because of an external suspend request,
2129     //   then that was taken care of above (or cancelled) so we are done
2130     // - if we were here because of another async request, then it has
2131     //   been cleared between the has_special_runtime_exit_condition()
2132     //   and now so again we are done
2133     return;
2134   }
2135 
2136   // Check for pending async. exception
2137   if (_pending_async_exception != NULL) {
2138     // Only overwrite an already pending exception, if it is not a threadDeath.
2139     if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2140 
2141       // We cannot call Exceptions::_throw(...) here because we cannot block
2142       set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2143 
2144       LogTarget(Info, exceptions) lt;
2145       if (lt.is_enabled()) {
2146         ResourceMark rm;
2147         LogStream ls(lt);
2148         ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2149           if (has_last_Java_frame()) {
2150             frame f = last_frame();
2151            ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2152           }
2153         ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2154       }
2155       _pending_async_exception = NULL;
2156       clear_has_async_exception();
2157     }
2158   }
2159 
2160   if (check_unsafe_error &&
2161       condition == _async_unsafe_access_error && !has_pending_exception()) {
2162     condition = _no_async_condition;  // done
2163     switch (thread_state()) {
2164     case _thread_in_vm: {
2165       JavaThread* THREAD = this;
2166       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2167     }
2168     case _thread_in_native: {
2169       ThreadInVMfromNative tiv(this);
2170       JavaThread* THREAD = this;
2171       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2172     }
2173     case _thread_in_Java: {
2174       ThreadInVMfromJava tiv(this);
2175       JavaThread* THREAD = this;
2176       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2177     }
2178     default:
2179       ShouldNotReachHere();
2180     }
2181   }
2182 
2183   assert(condition == _no_async_condition || has_pending_exception() ||
2184          (!check_unsafe_error && condition == _async_unsafe_access_error),
2185          "must have handled the async condition, if no exception");
2186 }
2187 
2188 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2189   //
2190   // Check for pending external suspend. Internal suspend requests do
2191   // not use handle_special_runtime_exit_condition().
2192   // If JNIEnv proxies are allowed, don't self-suspend if the target
2193   // thread is not the current thread. In older versions of jdbx, jdbx
2194   // threads could call into the VM with another thread's JNIEnv so we
2195   // can be here operating on behalf of a suspended thread (4432884).
2196   bool do_self_suspend = is_external_suspend_with_lock();
2197   if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2198     //
2199     // Because thread is external suspended the safepoint code will count
2200     // thread as at a safepoint. This can be odd because we can be here
2201     // as _thread_in_Java which would normally transition to _thread_blocked
2202     // at a safepoint. We would like to mark the thread as _thread_blocked
2203     // before calling java_suspend_self like all other callers of it but
2204     // we must then observe proper safepoint protocol. (We can't leave
2205     // _thread_blocked with a safepoint in progress). However we can be
2206     // here as _thread_in_native_trans so we can't use a normal transition
2207     // constructor/destructor pair because they assert on that type of
2208     // transition. We could do something like:
2209     //
2210     // JavaThreadState state = thread_state();
2211     // set_thread_state(_thread_in_vm);
2212     // {
2213     //   ThreadBlockInVM tbivm(this);
2214     //   java_suspend_self()
2215     // }
2216     // set_thread_state(_thread_in_vm_trans);
2217     // if (safepoint) block;
2218     // set_thread_state(state);
2219     //
2220     // but that is pretty messy. Instead we just go with the way the
2221     // code has worked before and note that this is the only path to
2222     // java_suspend_self that doesn't put the thread in _thread_blocked
2223     // mode.
2224 
2225     frame_anchor()->make_walkable(this);
2226     java_suspend_self();
2227 
2228     // We might be here for reasons in addition to the self-suspend request
2229     // so check for other async requests.
2230   }
2231 
2232   if (check_asyncs) {
2233     check_and_handle_async_exceptions();
2234   }
2235 #if INCLUDE_TRACE
2236   if (is_trace_suspend()) {
2237     TRACE_SUSPEND_THREAD(this);
2238   }
2239 #endif
2240 }
2241 
2242 void JavaThread::send_thread_stop(oop java_throwable)  {
2243   assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2244   assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2245   assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2246 
2247   // Do not throw asynchronous exceptions against the compiler thread
2248   // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2249   if (!can_call_java()) return;
2250 
2251   {
2252     // Actually throw the Throwable against the target Thread - however
2253     // only if there is no thread death exception installed already.
2254     if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2255       // If the topmost frame is a runtime stub, then we are calling into
2256       // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2257       // must deoptimize the caller before continuing, as the compiled  exception handler table
2258       // may not be valid
2259       if (has_last_Java_frame()) {
2260         frame f = last_frame();
2261         if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2262           // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2263           RegisterMap reg_map(this, UseBiasedLocking);
2264           frame compiled_frame = f.sender(&reg_map);
2265           if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2266             Deoptimization::deoptimize(this, compiled_frame, &reg_map);
2267           }
2268         }
2269       }
2270 
2271       // Set async. pending exception in thread.
2272       set_pending_async_exception(java_throwable);
2273 
2274       if (log_is_enabled(Info, exceptions)) {
2275          ResourceMark rm;
2276         log_info(exceptions)("Pending Async. exception installed of type: %s",
2277                              InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2278       }
2279       // for AbortVMOnException flag
2280       Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2281     }
2282   }
2283 
2284 
2285   // Interrupt thread so it will wake up from a potential wait()
2286   Thread::interrupt(this);
2287 }
2288 
2289 // External suspension mechanism.
2290 //
2291 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2292 // to any VM_locks and it is at a transition
2293 // Self-suspension will happen on the transition out of the vm.
2294 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2295 //
2296 // Guarantees on return:
2297 //   + Target thread will not execute any new bytecode (that's why we need to
2298 //     force a safepoint)
2299 //   + Target thread will not enter any new monitors
2300 //
2301 void JavaThread::java_suspend() {
2302   ThreadsListHandle tlh;
2303   if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) {
2304     return;
2305   }
2306 
2307   { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2308     if (!is_external_suspend()) {
2309       // a racing resume has cancelled us; bail out now
2310       return;
2311     }
2312 
2313     // suspend is done
2314     uint32_t debug_bits = 0;
2315     // Warning: is_ext_suspend_completed() may temporarily drop the
2316     // SR_lock to allow the thread to reach a stable thread state if
2317     // it is currently in a transient thread state.
2318     if (is_ext_suspend_completed(false /* !called_by_wait */,
2319                                  SuspendRetryDelay, &debug_bits)) {
2320       return;
2321     }
2322   }
2323 
2324   VM_ThreadSuspend vm_suspend;
2325   VMThread::execute(&vm_suspend);
2326 }
2327 
2328 // Part II of external suspension.
2329 // A JavaThread self suspends when it detects a pending external suspend
2330 // request. This is usually on transitions. It is also done in places
2331 // where continuing to the next transition would surprise the caller,
2332 // e.g., monitor entry.
2333 //
2334 // Returns the number of times that the thread self-suspended.
2335 //
2336 // Note: DO NOT call java_suspend_self() when you just want to block current
2337 //       thread. java_suspend_self() is the second stage of cooperative
2338 //       suspension for external suspend requests and should only be used
2339 //       to complete an external suspend request.
2340 //
2341 int JavaThread::java_suspend_self() {
2342   int ret = 0;
2343 
2344   // we are in the process of exiting so don't suspend
2345   if (is_exiting()) {
2346     clear_external_suspend();
2347     return ret;
2348   }
2349 
2350   assert(_anchor.walkable() ||
2351          (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2352          "must have walkable stack");
2353 
2354   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2355 
2356   assert(!this->is_ext_suspended(),
2357          "a thread trying to self-suspend should not already be suspended");
2358 
2359   if (this->is_suspend_equivalent()) {
2360     // If we are self-suspending as a result of the lifting of a
2361     // suspend equivalent condition, then the suspend_equivalent
2362     // flag is not cleared until we set the ext_suspended flag so
2363     // that wait_for_ext_suspend_completion() returns consistent
2364     // results.
2365     this->clear_suspend_equivalent();
2366   }
2367 
2368   // A racing resume may have cancelled us before we grabbed SR_lock
2369   // above. Or another external suspend request could be waiting for us
2370   // by the time we return from SR_lock()->wait(). The thread
2371   // that requested the suspension may already be trying to walk our
2372   // stack and if we return now, we can change the stack out from under
2373   // it. This would be a "bad thing (TM)" and cause the stack walker
2374   // to crash. We stay self-suspended until there are no more pending
2375   // external suspend requests.
2376   while (is_external_suspend()) {
2377     ret++;
2378     this->set_ext_suspended();
2379 
2380     // _ext_suspended flag is cleared by java_resume()
2381     while (is_ext_suspended()) {
2382       this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2383     }
2384   }
2385 
2386   return ret;
2387 }
2388 
2389 #ifdef ASSERT
2390 // verify the JavaThread has not yet been published in the Threads::list, and
2391 // hence doesn't need protection from concurrent access at this stage
2392 void JavaThread::verify_not_published() {
2393   ThreadsListHandle tlh;
2394   assert(!tlh.includes(this), "JavaThread shouldn't have been published yet!");
2395 }
2396 #endif
2397 
2398 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2399 // progress or when _suspend_flags is non-zero.
2400 // Current thread needs to self-suspend if there is a suspend request and/or
2401 // block if a safepoint is in progress.
2402 // Async exception ISN'T checked.
2403 // Note only the ThreadInVMfromNative transition can call this function
2404 // directly and when thread state is _thread_in_native_trans
2405 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2406   assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2407 
2408   JavaThread *curJT = JavaThread::current();
2409   bool do_self_suspend = thread->is_external_suspend();
2410 
2411   assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2412 
2413   // If JNIEnv proxies are allowed, don't self-suspend if the target
2414   // thread is not the current thread. In older versions of jdbx, jdbx
2415   // threads could call into the VM with another thread's JNIEnv so we
2416   // can be here operating on behalf of a suspended thread (4432884).
2417   if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2418     JavaThreadState state = thread->thread_state();
2419 
2420     // We mark this thread_blocked state as a suspend-equivalent so
2421     // that a caller to is_ext_suspend_completed() won't be confused.
2422     // The suspend-equivalent state is cleared by java_suspend_self().
2423     thread->set_suspend_equivalent();
2424 
2425     // If the safepoint code sees the _thread_in_native_trans state, it will
2426     // wait until the thread changes to other thread state. There is no
2427     // guarantee on how soon we can obtain the SR_lock and complete the
2428     // self-suspend request. It would be a bad idea to let safepoint wait for
2429     // too long. Temporarily change the state to _thread_blocked to
2430     // let the VM thread know that this thread is ready for GC. The problem
2431     // of changing thread state is that safepoint could happen just after
2432     // java_suspend_self() returns after being resumed, and VM thread will
2433     // see the _thread_blocked state. We must check for safepoint
2434     // after restoring the state and make sure we won't leave while a safepoint
2435     // is in progress.
2436     thread->set_thread_state(_thread_blocked);
2437     thread->java_suspend_self();
2438     thread->set_thread_state(state);
2439 
2440     InterfaceSupport::serialize_thread_state_with_handler(thread);
2441   }
2442 
2443   SafepointMechanism::block_if_requested(curJT);
2444 
2445   if (thread->is_deopt_suspend()) {
2446     thread->clear_deopt_suspend();
2447     RegisterMap map(thread, false);
2448     frame f = thread->last_frame();
2449     while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2450       f = f.sender(&map);
2451     }
2452     if (f.id() == thread->must_deopt_id()) {
2453       thread->clear_must_deopt_id();
2454       f.deoptimize(thread);
2455     } else {
2456       fatal("missed deoptimization!");
2457     }
2458   }
2459 #if INCLUDE_TRACE
2460   if (thread->is_trace_suspend()) {
2461     TRACE_SUSPEND_THREAD(thread);
2462   }
2463 #endif
2464 }
2465 
2466 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2467 // progress or when _suspend_flags is non-zero.
2468 // Current thread needs to self-suspend if there is a suspend request and/or
2469 // block if a safepoint is in progress.
2470 // Also check for pending async exception (not including unsafe access error).
2471 // Note only the native==>VM/Java barriers can call this function and when
2472 // thread state is _thread_in_native_trans.
2473 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2474   check_safepoint_and_suspend_for_native_trans(thread);
2475 
2476   if (thread->has_async_exception()) {
2477     // We are in _thread_in_native_trans state, don't handle unsafe
2478     // access error since that may block.
2479     thread->check_and_handle_async_exceptions(false);
2480   }
2481 }
2482 
2483 // This is a variant of the normal
2484 // check_special_condition_for_native_trans with slightly different
2485 // semantics for use by critical native wrappers.  It does all the
2486 // normal checks but also performs the transition back into
2487 // thread_in_Java state.  This is required so that critical natives
2488 // can potentially block and perform a GC if they are the last thread
2489 // exiting the GCLocker.
2490 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2491   check_special_condition_for_native_trans(thread);
2492 
2493   // Finish the transition
2494   thread->set_thread_state(_thread_in_Java);
2495 
2496   if (thread->do_critical_native_unlock()) {
2497     ThreadInVMfromJavaNoAsyncException tiv(thread);
2498     GCLocker::unlock_critical(thread);
2499     thread->clear_critical_native_unlock();
2500   }
2501 }
2502 
2503 // We need to guarantee the Threads_lock here, since resumes are not
2504 // allowed during safepoint synchronization
2505 // Can only resume from an external suspension
2506 void JavaThread::java_resume() {
2507   assert_locked_or_safepoint(Threads_lock);
2508 
2509   // Sanity check: thread is gone, has started exiting or the thread
2510   // was not externally suspended.
2511   ThreadsListHandle tlh;
2512   if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) {
2513     return;
2514   }
2515 
2516   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2517 
2518   clear_external_suspend();
2519 
2520   if (is_ext_suspended()) {
2521     clear_ext_suspended();
2522     SR_lock()->notify_all();
2523   }
2524 }
2525 
2526 size_t JavaThread::_stack_red_zone_size = 0;
2527 size_t JavaThread::_stack_yellow_zone_size = 0;
2528 size_t JavaThread::_stack_reserved_zone_size = 0;
2529 size_t JavaThread::_stack_shadow_zone_size = 0;
2530 
2531 void JavaThread::create_stack_guard_pages() {
2532   if (!os::uses_stack_guard_pages() ||
2533       _stack_guard_state != stack_guard_unused ||
2534       (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) {
2535       log_info(os, thread)("Stack guard page creation for thread "
2536                            UINTX_FORMAT " disabled", os::current_thread_id());
2537     return;
2538   }
2539   address low_addr = stack_end();
2540   size_t len = stack_guard_zone_size();
2541 
2542   assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2543   assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2544 
2545   int must_commit = os::must_commit_stack_guard_pages();
2546   // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2547 
2548   if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2549     log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2550     return;
2551   }
2552 
2553   if (os::guard_memory((char *) low_addr, len)) {
2554     _stack_guard_state = stack_guard_enabled;
2555   } else {
2556     log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2557       PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2558     if (os::uncommit_memory((char *) low_addr, len)) {
2559       log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2560     }
2561     return;
2562   }
2563 
2564   log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2565     PTR_FORMAT "-" PTR_FORMAT ".",
2566     os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2567 }
2568 
2569 void JavaThread::remove_stack_guard_pages() {
2570   assert(Thread::current() == this, "from different thread");
2571   if (_stack_guard_state == stack_guard_unused) return;
2572   address low_addr = stack_end();
2573   size_t len = stack_guard_zone_size();
2574 
2575   if (os::must_commit_stack_guard_pages()) {
2576     if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2577       _stack_guard_state = stack_guard_unused;
2578     } else {
2579       log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2580         PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2581       return;
2582     }
2583   } else {
2584     if (_stack_guard_state == stack_guard_unused) return;
2585     if (os::unguard_memory((char *) low_addr, len)) {
2586       _stack_guard_state = stack_guard_unused;
2587     } else {
2588       log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2589         PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2590       return;
2591     }
2592   }
2593 
2594   log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2595     PTR_FORMAT "-" PTR_FORMAT ".",
2596     os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2597 }
2598 
2599 void JavaThread::enable_stack_reserved_zone() {
2600   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2601   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2602 
2603   // The base notation is from the stack's point of view, growing downward.
2604   // We need to adjust it to work correctly with guard_memory()
2605   address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2606 
2607   guarantee(base < stack_base(),"Error calculating stack reserved zone");
2608   guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2609 
2610   if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2611     _stack_guard_state = stack_guard_enabled;
2612   } else {
2613     warning("Attempt to guard stack reserved zone failed.");
2614   }
2615   enable_register_stack_guard();
2616 }
2617 
2618 void JavaThread::disable_stack_reserved_zone() {
2619   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2620   assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2621 
2622   // Simply return if called for a thread that does not use guard pages.
2623   if (_stack_guard_state == stack_guard_unused) return;
2624 
2625   // The base notation is from the stack's point of view, growing downward.
2626   // We need to adjust it to work correctly with guard_memory()
2627   address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2628 
2629   if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2630     _stack_guard_state = stack_guard_reserved_disabled;
2631   } else {
2632     warning("Attempt to unguard stack reserved zone failed.");
2633   }
2634   disable_register_stack_guard();
2635 }
2636 
2637 void JavaThread::enable_stack_yellow_reserved_zone() {
2638   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2639   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2640 
2641   // The base notation is from the stacks point of view, growing downward.
2642   // We need to adjust it to work correctly with guard_memory()
2643   address base = stack_red_zone_base();
2644 
2645   guarantee(base < stack_base(), "Error calculating stack yellow zone");
2646   guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2647 
2648   if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2649     _stack_guard_state = stack_guard_enabled;
2650   } else {
2651     warning("Attempt to guard stack yellow zone failed.");
2652   }
2653   enable_register_stack_guard();
2654 }
2655 
2656 void JavaThread::disable_stack_yellow_reserved_zone() {
2657   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2658   assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2659 
2660   // Simply return if called for a thread that does not use guard pages.
2661   if (_stack_guard_state == stack_guard_unused) return;
2662 
2663   // The base notation is from the stacks point of view, growing downward.
2664   // We need to adjust it to work correctly with guard_memory()
2665   address base = stack_red_zone_base();
2666 
2667   if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2668     _stack_guard_state = stack_guard_yellow_reserved_disabled;
2669   } else {
2670     warning("Attempt to unguard stack yellow zone failed.");
2671   }
2672   disable_register_stack_guard();
2673 }
2674 
2675 void JavaThread::enable_stack_red_zone() {
2676   // The base notation is from the stacks point of view, growing downward.
2677   // We need to adjust it to work correctly with guard_memory()
2678   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2679   address base = stack_red_zone_base() - stack_red_zone_size();
2680 
2681   guarantee(base < stack_base(), "Error calculating stack red zone");
2682   guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2683 
2684   if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2685     warning("Attempt to guard stack red zone failed.");
2686   }
2687 }
2688 
2689 void JavaThread::disable_stack_red_zone() {
2690   // The base notation is from the stacks point of view, growing downward.
2691   // We need to adjust it to work correctly with guard_memory()
2692   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2693   address base = stack_red_zone_base() - stack_red_zone_size();
2694   if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2695     warning("Attempt to unguard stack red zone failed.");
2696   }
2697 }
2698 
2699 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2700   // ignore is there is no stack
2701   if (!has_last_Java_frame()) return;
2702   // traverse the stack frames. Starts from top frame.
2703   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2704     frame* fr = fst.current();
2705     f(fr, fst.register_map());
2706   }
2707 }
2708 
2709 
2710 #ifndef PRODUCT
2711 // Deoptimization
2712 // Function for testing deoptimization
2713 void JavaThread::deoptimize() {
2714   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2715   StackFrameStream fst(this, UseBiasedLocking);
2716   bool deopt = false;           // Dump stack only if a deopt actually happens.
2717   bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2718   // Iterate over all frames in the thread and deoptimize
2719   for (; !fst.is_done(); fst.next()) {
2720     if (fst.current()->can_be_deoptimized()) {
2721 
2722       if (only_at) {
2723         // Deoptimize only at particular bcis.  DeoptimizeOnlyAt
2724         // consists of comma or carriage return separated numbers so
2725         // search for the current bci in that string.
2726         address pc = fst.current()->pc();
2727         nmethod* nm =  (nmethod*) fst.current()->cb();
2728         ScopeDesc* sd = nm->scope_desc_at(pc);
2729         char buffer[8];
2730         jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2731         size_t len = strlen(buffer);
2732         const char * found = strstr(DeoptimizeOnlyAt, buffer);
2733         while (found != NULL) {
2734           if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2735               (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2736             // Check that the bci found is bracketed by terminators.
2737             break;
2738           }
2739           found = strstr(found + 1, buffer);
2740         }
2741         if (!found) {
2742           continue;
2743         }
2744       }
2745 
2746       if (DebugDeoptimization && !deopt) {
2747         deopt = true; // One-time only print before deopt
2748         tty->print_cr("[BEFORE Deoptimization]");
2749         trace_frames();
2750         trace_stack();
2751       }
2752       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2753     }
2754   }
2755 
2756   if (DebugDeoptimization && deopt) {
2757     tty->print_cr("[AFTER Deoptimization]");
2758     trace_frames();
2759   }
2760 }
2761 
2762 
2763 // Make zombies
2764 void JavaThread::make_zombies() {
2765   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2766     if (fst.current()->can_be_deoptimized()) {
2767       // it is a Java nmethod
2768       nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2769       nm->make_not_entrant();
2770     }
2771   }
2772 }
2773 #endif // PRODUCT
2774 
2775 
2776 void JavaThread::deoptimized_wrt_marked_nmethods() {
2777   if (!has_last_Java_frame()) return;
2778   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2779   StackFrameStream fst(this, UseBiasedLocking);
2780   for (; !fst.is_done(); fst.next()) {
2781     if (fst.current()->should_be_deoptimized()) {
2782       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2783     }
2784   }
2785 }
2786 
2787 
2788 // If the caller is a NamedThread, then remember, in the current scope,
2789 // the given JavaThread in its _processed_thread field.
2790 class RememberProcessedThread: public StackObj {
2791   NamedThread* _cur_thr;
2792  public:
2793   RememberProcessedThread(JavaThread* jthr) {
2794     Thread* thread = Thread::current();
2795     if (thread->is_Named_thread()) {
2796       _cur_thr = (NamedThread *)thread;
2797       _cur_thr->set_processed_thread(jthr);
2798     } else {
2799       _cur_thr = NULL;
2800     }
2801   }
2802 
2803   ~RememberProcessedThread() {
2804     if (_cur_thr) {
2805       _cur_thr->set_processed_thread(NULL);
2806     }
2807   }
2808 };
2809 
2810 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2811   // Verify that the deferred card marks have been flushed.
2812   assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2813 
2814   // Traverse the GCHandles
2815   Thread::oops_do(f, cf);
2816 
2817   JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);)
2818 
2819   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2820          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2821 
2822   if (has_last_Java_frame()) {
2823     // Record JavaThread to GC thread
2824     RememberProcessedThread rpt(this);
2825 
2826     // Traverse the privileged stack
2827     if (_privileged_stack_top != NULL) {
2828       _privileged_stack_top->oops_do(f);
2829     }
2830 
2831     // traverse the registered growable array
2832     if (_array_for_gc != NULL) {
2833       for (int index = 0; index < _array_for_gc->length(); index++) {
2834         f->do_oop(_array_for_gc->adr_at(index));
2835       }
2836     }
2837 
2838     // Traverse the monitor chunks
2839     for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2840       chunk->oops_do(f);
2841     }
2842 
2843     // Traverse the execution stack
2844     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2845       fst.current()->oops_do(f, cf, fst.register_map());
2846     }
2847   }
2848 
2849   // callee_target is never live across a gc point so NULL it here should
2850   // it still contain a methdOop.
2851 
2852   set_callee_target(NULL);
2853 
2854   assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2855   // If we have deferred set_locals there might be oops waiting to be
2856   // written
2857   GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2858   if (list != NULL) {
2859     for (int i = 0; i < list->length(); i++) {
2860       list->at(i)->oops_do(f);
2861     }
2862   }
2863 
2864   // Traverse instance variables at the end since the GC may be moving things
2865   // around using this function
2866   f->do_oop((oop*) &_threadObj);
2867   f->do_oop((oop*) &_vm_result);
2868   f->do_oop((oop*) &_exception_oop);
2869   f->do_oop((oop*) &_pending_async_exception);
2870 
2871   if (jvmti_thread_state() != NULL) {
2872     jvmti_thread_state()->oops_do(f);
2873   }
2874 }
2875 
2876 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2877   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2878          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2879 
2880   if (has_last_Java_frame()) {
2881     // Traverse the execution stack
2882     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2883       fst.current()->nmethods_do(cf);
2884     }
2885   }
2886 }
2887 
2888 void JavaThread::metadata_do(void f(Metadata*)) {
2889   if (has_last_Java_frame()) {
2890     // Traverse the execution stack to call f() on the methods in the stack
2891     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2892       fst.current()->metadata_do(f);
2893     }
2894   } else if (is_Compiler_thread()) {
2895     // need to walk ciMetadata in current compile tasks to keep alive.
2896     CompilerThread* ct = (CompilerThread*)this;
2897     if (ct->env() != NULL) {
2898       ct->env()->metadata_do(f);
2899     }
2900     CompileTask* task = ct->task();
2901     if (task != NULL) {
2902       task->metadata_do(f);
2903     }
2904   }
2905 }
2906 
2907 // Printing
2908 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2909   switch (_thread_state) {
2910   case _thread_uninitialized:     return "_thread_uninitialized";
2911   case _thread_new:               return "_thread_new";
2912   case _thread_new_trans:         return "_thread_new_trans";
2913   case _thread_in_native:         return "_thread_in_native";
2914   case _thread_in_native_trans:   return "_thread_in_native_trans";
2915   case _thread_in_vm:             return "_thread_in_vm";
2916   case _thread_in_vm_trans:       return "_thread_in_vm_trans";
2917   case _thread_in_Java:           return "_thread_in_Java";
2918   case _thread_in_Java_trans:     return "_thread_in_Java_trans";
2919   case _thread_blocked:           return "_thread_blocked";
2920   case _thread_blocked_trans:     return "_thread_blocked_trans";
2921   default:                        return "unknown thread state";
2922   }
2923 }
2924 
2925 #ifndef PRODUCT
2926 void JavaThread::print_thread_state_on(outputStream *st) const {
2927   st->print_cr("   JavaThread state: %s", _get_thread_state_name(_thread_state));
2928 };
2929 void JavaThread::print_thread_state() const {
2930   print_thread_state_on(tty);
2931 }
2932 #endif // PRODUCT
2933 
2934 // Called by Threads::print() for VM_PrintThreads operation
2935 void JavaThread::print_on(outputStream *st) const {
2936   st->print_raw("\"");
2937   st->print_raw(get_thread_name());
2938   st->print_raw("\" ");
2939   oop thread_oop = threadObj();
2940   if (thread_oop != NULL) {
2941     st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
2942     if (java_lang_Thread::is_daemon(thread_oop))  st->print("daemon ");
2943     st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2944   }
2945   Thread::print_on(st);
2946   // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2947   st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2948   if (thread_oop != NULL) {
2949     st->print_cr("   java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2950   }
2951 #ifndef PRODUCT
2952   print_thread_state_on(st);
2953   _safepoint_state->print_on(st);
2954 #endif // PRODUCT
2955   if (is_Compiler_thread()) {
2956     CompileTask *task = ((CompilerThread*)this)->task();
2957     if (task != NULL) {
2958       st->print("   Compiling: ");
2959       task->print(st, NULL, true, false);
2960     } else {
2961       st->print("   No compile task");
2962     }
2963     st->cr();
2964   }
2965 }
2966 
2967 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2968   st->print("%s", get_thread_name_string(buf, buflen));
2969 }
2970 
2971 // Called by fatal error handler. The difference between this and
2972 // JavaThread::print() is that we can't grab lock or allocate memory.
2973 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2974   st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2975   oop thread_obj = threadObj();
2976   if (thread_obj != NULL) {
2977     if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2978   }
2979   st->print(" [");
2980   st->print("%s", _get_thread_state_name(_thread_state));
2981   if (osthread()) {
2982     st->print(", id=%d", osthread()->thread_id());
2983   }
2984   st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2985             p2i(stack_end()), p2i(stack_base()));
2986   st->print("]");
2987 
2988   if (_threads_hazard_ptr != NULL) {
2989     st->print(" _threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr));
2990   }
2991   if (_nested_threads_hazard_ptr != NULL) {
2992     print_nested_threads_hazard_ptrs_on(st);
2993   }
2994   return;
2995 }
2996 
2997 // Verification
2998 
2999 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
3000 
3001 void JavaThread::verify() {
3002   // Verify oops in the thread.
3003   oops_do(&VerifyOopClosure::verify_oop, NULL);
3004 
3005   // Verify the stack frames.
3006   frames_do(frame_verify);
3007 }
3008 
3009 // CR 6300358 (sub-CR 2137150)
3010 // Most callers of this method assume that it can't return NULL but a
3011 // thread may not have a name whilst it is in the process of attaching to
3012 // the VM - see CR 6412693, and there are places where a JavaThread can be
3013 // seen prior to having it's threadObj set (eg JNI attaching threads and
3014 // if vm exit occurs during initialization). These cases can all be accounted
3015 // for such that this method never returns NULL.
3016 const char* JavaThread::get_thread_name() const {
3017 #ifdef ASSERT
3018   // early safepoints can hit while current thread does not yet have TLS
3019   if (!SafepointSynchronize::is_at_safepoint()) {
3020     Thread *cur = Thread::current();
3021     if (!(cur->is_Java_thread() && cur == this)) {
3022       // Current JavaThreads are allowed to get their own name without
3023       // the Threads_lock.
3024       assert_locked_or_safepoint(Threads_lock);
3025     }
3026   }
3027 #endif // ASSERT
3028   return get_thread_name_string();
3029 }
3030 
3031 // Returns a non-NULL representation of this thread's name, or a suitable
3032 // descriptive string if there is no set name
3033 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3034   const char* name_str;
3035   oop thread_obj = threadObj();
3036   if (thread_obj != NULL) {
3037     oop name = java_lang_Thread::name(thread_obj);
3038     if (name != NULL) {
3039       if (buf == NULL) {
3040         name_str = java_lang_String::as_utf8_string(name);
3041       } else {
3042         name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3043       }
3044     } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3045       name_str = "<no-name - thread is attaching>";
3046     } else {
3047       name_str = Thread::name();
3048     }
3049   } else {
3050     name_str = Thread::name();
3051   }
3052   assert(name_str != NULL, "unexpected NULL thread name");
3053   return name_str;
3054 }
3055 
3056 
3057 const char* JavaThread::get_threadgroup_name() const {
3058   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3059   oop thread_obj = threadObj();
3060   if (thread_obj != NULL) {
3061     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3062     if (thread_group != NULL) {
3063       // ThreadGroup.name can be null
3064       return java_lang_ThreadGroup::name(thread_group);
3065     }
3066   }
3067   return NULL;
3068 }
3069 
3070 const char* JavaThread::get_parent_name() const {
3071   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3072   oop thread_obj = threadObj();
3073   if (thread_obj != NULL) {
3074     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3075     if (thread_group != NULL) {
3076       oop parent = java_lang_ThreadGroup::parent(thread_group);
3077       if (parent != NULL) {
3078         // ThreadGroup.name can be null
3079         return java_lang_ThreadGroup::name(parent);
3080       }
3081     }
3082   }
3083   return NULL;
3084 }
3085 
3086 ThreadPriority JavaThread::java_priority() const {
3087   oop thr_oop = threadObj();
3088   if (thr_oop == NULL) return NormPriority; // Bootstrapping
3089   ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3090   assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3091   return priority;
3092 }
3093 
3094 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3095 
3096   assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3097   // Link Java Thread object <-> C++ Thread
3098 
3099   // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3100   // and put it into a new Handle.  The Handle "thread_oop" can then
3101   // be used to pass the C++ thread object to other methods.
3102 
3103   // Set the Java level thread object (jthread) field of the
3104   // new thread (a JavaThread *) to C++ thread object using the
3105   // "thread_oop" handle.
3106 
3107   // Set the thread field (a JavaThread *) of the
3108   // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3109 
3110   Handle thread_oop(Thread::current(),
3111                     JNIHandles::resolve_non_null(jni_thread));
3112   assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3113          "must be initialized");
3114   set_threadObj(thread_oop());
3115   java_lang_Thread::set_thread(thread_oop(), this);
3116 
3117   if (prio == NoPriority) {
3118     prio = java_lang_Thread::priority(thread_oop());
3119     assert(prio != NoPriority, "A valid priority should be present");
3120   }
3121 
3122   // Push the Java priority down to the native thread; needs Threads_lock
3123   Thread::set_priority(this, prio);
3124 
3125   prepare_ext();
3126 
3127   // Add the new thread to the Threads list and set it in motion.
3128   // We must have threads lock in order to call Threads::add.
3129   // It is crucial that we do not block before the thread is
3130   // added to the Threads list for if a GC happens, then the java_thread oop
3131   // will not be visited by GC.
3132   Threads::add(this);
3133 }
3134 
3135 oop JavaThread::current_park_blocker() {
3136   // Support for JSR-166 locks
3137   oop thread_oop = threadObj();
3138   if (thread_oop != NULL &&
3139       JDK_Version::current().supports_thread_park_blocker()) {
3140     return java_lang_Thread::park_blocker(thread_oop);
3141   }
3142   return NULL;
3143 }
3144 
3145 
3146 void JavaThread::print_stack_on(outputStream* st) {
3147   if (!has_last_Java_frame()) return;
3148   ResourceMark rm;
3149   HandleMark   hm;
3150 
3151   RegisterMap reg_map(this);
3152   vframe* start_vf = last_java_vframe(&reg_map);
3153   int count = 0;
3154   for (vframe* f = start_vf; f != NULL; f = f->sender()) {
3155     if (f->is_java_frame()) {
3156       javaVFrame* jvf = javaVFrame::cast(f);
3157       java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3158 
3159       // Print out lock information
3160       if (JavaMonitorsInStackTrace) {
3161         jvf->print_lock_info_on(st, count);
3162       }
3163     } else {
3164       // Ignore non-Java frames
3165     }
3166 
3167     // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
3168     count++;
3169     if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
3170   }
3171 }
3172 
3173 
3174 // JVMTI PopFrame support
3175 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3176   assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3177   if (in_bytes(size_in_bytes) != 0) {
3178     _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3179     _popframe_preserved_args_size = in_bytes(size_in_bytes);
3180     Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3181   }
3182 }
3183 
3184 void* JavaThread::popframe_preserved_args() {
3185   return _popframe_preserved_args;
3186 }
3187 
3188 ByteSize JavaThread::popframe_preserved_args_size() {
3189   return in_ByteSize(_popframe_preserved_args_size);
3190 }
3191 
3192 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3193   int sz = in_bytes(popframe_preserved_args_size());
3194   assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3195   return in_WordSize(sz / wordSize);
3196 }
3197 
3198 void JavaThread::popframe_free_preserved_args() {
3199   assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3200   FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3201   _popframe_preserved_args = NULL;
3202   _popframe_preserved_args_size = 0;
3203 }
3204 
3205 #ifndef PRODUCT
3206 
3207 void JavaThread::trace_frames() {
3208   tty->print_cr("[Describe stack]");
3209   int frame_no = 1;
3210   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3211     tty->print("  %d. ", frame_no++);
3212     fst.current()->print_value_on(tty, this);
3213     tty->cr();
3214   }
3215 }
3216 
3217 class PrintAndVerifyOopClosure: public OopClosure {
3218  protected:
3219   template <class T> inline void do_oop_work(T* p) {
3220     oop obj = oopDesc::load_decode_heap_oop(p);
3221     if (obj == NULL) return;
3222     tty->print(INTPTR_FORMAT ": ", p2i(p));
3223     if (oopDesc::is_oop_or_null(obj)) {
3224       if (obj->is_objArray()) {
3225         tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3226       } else {
3227         obj->print();
3228       }
3229     } else {
3230       tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3231     }
3232     tty->cr();
3233   }
3234  public:
3235   virtual void do_oop(oop* p) { do_oop_work(p); }
3236   virtual void do_oop(narrowOop* p)  { do_oop_work(p); }
3237 };
3238 
3239 
3240 static void oops_print(frame* f, const RegisterMap *map) {
3241   PrintAndVerifyOopClosure print;
3242   f->print_value();
3243   f->oops_do(&print, NULL, (RegisterMap*)map);
3244 }
3245 
3246 // Print our all the locations that contain oops and whether they are
3247 // valid or not.  This useful when trying to find the oldest frame
3248 // where an oop has gone bad since the frame walk is from youngest to
3249 // oldest.
3250 void JavaThread::trace_oops() {
3251   tty->print_cr("[Trace oops]");
3252   frames_do(oops_print);
3253 }
3254 
3255 
3256 #ifdef ASSERT
3257 // Print or validate the layout of stack frames
3258 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3259   ResourceMark rm;
3260   PRESERVE_EXCEPTION_MARK;
3261   FrameValues values;
3262   int frame_no = 0;
3263   for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3264     fst.current()->describe(values, ++frame_no);
3265     if (depth == frame_no) break;
3266   }
3267   if (validate_only) {
3268     values.validate();
3269   } else {
3270     tty->print_cr("[Describe stack layout]");
3271     values.print(this);
3272   }
3273 }
3274 #endif
3275 
3276 void JavaThread::trace_stack_from(vframe* start_vf) {
3277   ResourceMark rm;
3278   int vframe_no = 1;
3279   for (vframe* f = start_vf; f; f = f->sender()) {
3280     if (f->is_java_frame()) {
3281       javaVFrame::cast(f)->print_activation(vframe_no++);
3282     } else {
3283       f->print();
3284     }
3285     if (vframe_no > StackPrintLimit) {
3286       tty->print_cr("...<more frames>...");
3287       return;
3288     }
3289   }
3290 }
3291 
3292 
3293 void JavaThread::trace_stack() {
3294   if (!has_last_Java_frame()) return;
3295   ResourceMark rm;
3296   HandleMark   hm;
3297   RegisterMap reg_map(this);
3298   trace_stack_from(last_java_vframe(&reg_map));
3299 }
3300 
3301 
3302 #endif // PRODUCT
3303 
3304 
3305 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3306   assert(reg_map != NULL, "a map must be given");
3307   frame f = last_frame();
3308   for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3309     if (vf->is_java_frame()) return javaVFrame::cast(vf);
3310   }
3311   return NULL;
3312 }
3313 
3314 
3315 Klass* JavaThread::security_get_caller_class(int depth) {
3316   vframeStream vfst(this);
3317   vfst.security_get_caller_frame(depth);
3318   if (!vfst.at_end()) {
3319     return vfst.method()->method_holder();
3320   }
3321   return NULL;
3322 }
3323 
3324 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3325   assert(thread->is_Compiler_thread(), "must be compiler thread");
3326   CompileBroker::compiler_thread_loop();
3327 }
3328 
3329 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3330   NMethodSweeper::sweeper_loop();
3331 }
3332 
3333 // Create a CompilerThread
3334 CompilerThread::CompilerThread(CompileQueue* queue,
3335                                CompilerCounters* counters)
3336                                : JavaThread(&compiler_thread_entry) {
3337   _env   = NULL;
3338   _log   = NULL;
3339   _task  = NULL;
3340   _queue = queue;
3341   _counters = counters;
3342   _buffer_blob = NULL;
3343   _compiler = NULL;
3344 
3345   // Compiler uses resource area for compilation, let's bias it to mtCompiler
3346   resource_area()->bias_to(mtCompiler);
3347 
3348 #ifndef PRODUCT
3349   _ideal_graph_printer = NULL;
3350 #endif
3351 }
3352 
3353 bool CompilerThread::can_call_java() const {
3354   return _compiler != NULL && _compiler->is_jvmci();
3355 }
3356 
3357 // Create sweeper thread
3358 CodeCacheSweeperThread::CodeCacheSweeperThread()
3359 : JavaThread(&sweeper_thread_entry) {
3360   _scanned_compiled_method = NULL;
3361 }
3362 
3363 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3364   JavaThread::oops_do(f, cf);
3365   if (_scanned_compiled_method != NULL && cf != NULL) {
3366     // Safepoints can occur when the sweeper is scanning an nmethod so
3367     // process it here to make sure it isn't unloaded in the middle of
3368     // a scan.
3369     cf->do_code_blob(_scanned_compiled_method);
3370   }
3371 }
3372 
3373 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3374   JavaThread::nmethods_do(cf);
3375   if (_scanned_compiled_method != NULL && cf != NULL) {
3376     // Safepoints can occur when the sweeper is scanning an nmethod so
3377     // process it here to make sure it isn't unloaded in the middle of
3378     // a scan.
3379     cf->do_code_blob(_scanned_compiled_method);
3380   }
3381 }
3382 
3383 
3384 // ======= Threads ========
3385 
3386 // The Threads class links together all active threads, and provides
3387 // operations over all threads. It is protected by the Threads_lock,
3388 // which is also used in other global contexts like safepointing.
3389 // ThreadsListHandles are used to safely perform operations on one
3390 // or more threads without the risk of the thread exiting during the
3391 // operation.
3392 //
3393 // Note: The Threads_lock is currently more widely used than we
3394 // would like. We are actively migrating Threads_lock uses to other
3395 // mechanisms in order to reduce Threads_lock contention.
3396 
3397 JavaThread* Threads::_thread_list = NULL;
3398 int         Threads::_number_of_threads = 0;
3399 int         Threads::_number_of_non_daemon_threads = 0;
3400 int         Threads::_return_code = 0;
3401 int         Threads::_thread_claim_parity = 0;
3402 size_t      JavaThread::_stack_size_at_create = 0;
3403 
3404 #ifdef ASSERT
3405 bool        Threads::_vm_complete = false;
3406 #endif
3407 
3408 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
3409   Prefetch::read((void*)addr, prefetch_interval);
3410   return *addr;
3411 }
3412 
3413 // Possibly the ugliest for loop the world has seen. C++ does not allow
3414 // multiple types in the declaration section of the for loop. In this case
3415 // we are only dealing with pointers and hence can cast them. It looks ugly
3416 // but macros are ugly and therefore it's fine to make things absurdly ugly.
3417 #define DO_JAVA_THREADS(LIST, X)                                                                                          \
3418     for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes,                           \
3419              *MACRO_list = (JavaThread*)(LIST),                                                                           \
3420              **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(),  \
3421              **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(),                                     \
3422              *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval);                 \
3423          MACRO_current_p != MACRO_end;                                                                                    \
3424          MACRO_current_p++,                                                                                               \
3425              X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval))
3426 
3427 // All JavaThreads
3428 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X)
3429 
3430 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3431 void Threads::threads_do(ThreadClosure* tc) {
3432   assert_locked_or_safepoint(Threads_lock);
3433   // ALL_JAVA_THREADS iterates through all JavaThreads
3434   ALL_JAVA_THREADS(p) {
3435     tc->do_thread(p);
3436   }
3437   // Someday we could have a table or list of all non-JavaThreads.
3438   // For now, just manually iterate through them.
3439   tc->do_thread(VMThread::vm_thread());
3440   Universe::heap()->gc_threads_do(tc);
3441   WatcherThread *wt = WatcherThread::watcher_thread();
3442   // Strictly speaking, the following NULL check isn't sufficient to make sure
3443   // the data for WatcherThread is still valid upon being examined. However,
3444   // considering that WatchThread terminates when the VM is on the way to
3445   // exit at safepoint, the chance of the above is extremely small. The right
3446   // way to prevent termination of WatcherThread would be to acquire
3447   // Terminator_lock, but we can't do that without violating the lock rank
3448   // checking in some cases.
3449   if (wt != NULL) {
3450     tc->do_thread(wt);
3451   }
3452 
3453   // If CompilerThreads ever become non-JavaThreads, add them here
3454 }
3455 
3456 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
3457   int cp = Threads::thread_claim_parity();
3458   ALL_JAVA_THREADS(p) {
3459     if (p->claim_oops_do(is_par, cp)) {
3460       tc->do_thread(p);
3461     }
3462   }
3463   VMThread* vmt = VMThread::vm_thread();
3464   if (vmt->claim_oops_do(is_par, cp)) {
3465     tc->do_thread(vmt);
3466   }
3467 }
3468 
3469 // The system initialization in the library has three phases.
3470 //
3471 // Phase 1: java.lang.System class initialization
3472 //     java.lang.System is a primordial class loaded and initialized
3473 //     by the VM early during startup.  java.lang.System.<clinit>
3474 //     only does registerNatives and keeps the rest of the class
3475 //     initialization work later until thread initialization completes.
3476 //
3477 //     System.initPhase1 initializes the system properties, the static
3478 //     fields in, out, and err. Set up java signal handlers, OS-specific
3479 //     system settings, and thread group of the main thread.
3480 static void call_initPhase1(TRAPS) {
3481   Klass* klass =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3482   JavaValue result(T_VOID);
3483   JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3484                                          vmSymbols::void_method_signature(), CHECK);
3485 }
3486 
3487 // Phase 2. Module system initialization
3488 //     This will initialize the module system.  Only java.base classes
3489 //     can be loaded until phase 2 completes.
3490 //
3491 //     Call System.initPhase2 after the compiler initialization and jsr292
3492 //     classes get initialized because module initialization runs a lot of java
3493 //     code, that for performance reasons, should be compiled.  Also, this will
3494 //     enable the startup code to use lambda and other language features in this
3495 //     phase and onward.
3496 //
3497 //     After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3498 static void call_initPhase2(TRAPS) {
3499   TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3500 
3501   Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3502 
3503   JavaValue result(T_INT);
3504   JavaCallArguments args;
3505   args.push_int(DisplayVMOutputToStderr);
3506   args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3507   JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3508                                          vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3509   if (result.get_jint() != JNI_OK) {
3510     vm_exit_during_initialization(); // no message or exception
3511   }
3512 
3513   universe_post_module_init();
3514 }
3515 
3516 // Phase 3. final setup - set security manager, system class loader and TCCL
3517 //
3518 //     This will instantiate and set the security manager, set the system class
3519 //     loader as well as the thread context class loader.  The security manager
3520 //     and system class loader may be a custom class loaded from -Xbootclasspath/a,
3521 //     other modules or the application's classpath.
3522 static void call_initPhase3(TRAPS) {
3523   Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3524   JavaValue result(T_VOID);
3525   JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3526                                          vmSymbols::void_method_signature(), CHECK);
3527 }
3528 
3529 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3530   TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3531 
3532   if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3533     create_vm_init_libraries();
3534   }
3535 
3536   initialize_class(vmSymbols::java_lang_String(), CHECK);
3537 
3538   // Inject CompactStrings value after the static initializers for String ran.
3539   java_lang_String::set_compact_strings(CompactStrings);
3540 
3541   // Initialize java_lang.System (needed before creating the thread)
3542   initialize_class(vmSymbols::java_lang_System(), CHECK);
3543   // The VM creates & returns objects of this class. Make sure it's initialized.
3544   initialize_class(vmSymbols::java_lang_Class(), CHECK);
3545   initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3546   Handle thread_group = create_initial_thread_group(CHECK);
3547   Universe::set_main_thread_group(thread_group());
3548   initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3549   oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3550   main_thread->set_threadObj(thread_object);
3551   // Set thread status to running since main thread has
3552   // been started and running.
3553   java_lang_Thread::set_thread_status(thread_object,
3554                                       java_lang_Thread::RUNNABLE);
3555 
3556   // The VM creates objects of this class.
3557   initialize_class(vmSymbols::java_lang_Module(), CHECK);
3558 
3559   // The VM preresolves methods to these classes. Make sure that they get initialized
3560   initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3561   initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3562 
3563   // Phase 1 of the system initialization in the library, java.lang.System class initialization
3564   call_initPhase1(CHECK);
3565 
3566   // get the Java runtime name after java.lang.System is initialized
3567   JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3568   JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3569 
3570   // an instance of OutOfMemory exception has been allocated earlier
3571   initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3572   initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3573   initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3574   initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3575   initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3576   initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3577   initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3578   initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3579 }
3580 
3581 void Threads::initialize_jsr292_core_classes(TRAPS) {
3582   TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3583 
3584   initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3585   initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3586   initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3587   initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3588 }
3589 
3590 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3591   extern void JDK_Version_init();
3592 
3593   // Preinitialize version info.
3594   VM_Version::early_initialize();
3595 
3596   // Check version
3597   if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3598 
3599   // Initialize library-based TLS
3600   ThreadLocalStorage::init();
3601 
3602   // Initialize the output stream module
3603   ostream_init();
3604 
3605   // Process java launcher properties.
3606   Arguments::process_sun_java_launcher_properties(args);
3607 
3608   // Initialize the os module
3609   os::init();
3610 
3611   // Record VM creation timing statistics
3612   TraceVmCreationTime create_vm_timer;
3613   create_vm_timer.start();
3614 
3615   // Initialize system properties.
3616   Arguments::init_system_properties();
3617 
3618   // So that JDK version can be used as a discriminator when parsing arguments
3619   JDK_Version_init();
3620 
3621   // Update/Initialize System properties after JDK version number is known
3622   Arguments::init_version_specific_system_properties();
3623 
3624   // Make sure to initialize log configuration *before* parsing arguments
3625   LogConfiguration::initialize(create_vm_timer.begin_time());
3626 
3627   // Parse arguments
3628   // Note: this internally calls os::init_container_support()
3629   jint parse_result = Arguments::parse(args);
3630   if (parse_result != JNI_OK) return parse_result;
3631 
3632   os::init_before_ergo();
3633 
3634   jint ergo_result = Arguments::apply_ergo();
3635   if (ergo_result != JNI_OK) return ergo_result;
3636 
3637   // Final check of all ranges after ergonomics which may change values.
3638   if (!CommandLineFlagRangeList::check_ranges()) {
3639     return JNI_EINVAL;
3640   }
3641 
3642   // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3643   bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo);
3644   if (!constraint_result) {
3645     return JNI_EINVAL;
3646   }
3647 
3648   CommandLineFlagWriteableList::mark_startup();
3649 
3650   if (PauseAtStartup) {
3651     os::pause();
3652   }
3653 
3654   HOTSPOT_VM_INIT_BEGIN();
3655 
3656   // Timing (must come after argument parsing)
3657   TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3658 
3659   // Initialize the os module after parsing the args
3660   jint os_init_2_result = os::init_2();
3661   if (os_init_2_result != JNI_OK) return os_init_2_result;
3662 
3663   SafepointMechanism::initialize();
3664 
3665   jint adjust_after_os_result = Arguments::adjust_after_os();
3666   if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3667 
3668   // Initialize output stream logging
3669   ostream_init_log();
3670 
3671   // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3672   // Must be before create_vm_init_agents()
3673   if (Arguments::init_libraries_at_startup()) {
3674     convert_vm_init_libraries_to_agents();
3675   }
3676 
3677   // Launch -agentlib/-agentpath and converted -Xrun agents
3678   if (Arguments::init_agents_at_startup()) {
3679     create_vm_init_agents();
3680   }
3681 
3682   // Initialize Threads state
3683   _thread_list = NULL;
3684   _number_of_threads = 0;
3685   _number_of_non_daemon_threads = 0;
3686 
3687   // Initialize global data structures and create system classes in heap
3688   vm_init_globals();
3689 
3690 #if INCLUDE_JVMCI
3691   if (JVMCICounterSize > 0) {
3692     JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3693     memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3694   } else {
3695     JavaThread::_jvmci_old_thread_counters = NULL;
3696   }
3697 #endif // INCLUDE_JVMCI
3698 
3699   // Attach the main thread to this os thread
3700   JavaThread* main_thread = new JavaThread();
3701   main_thread->set_thread_state(_thread_in_vm);
3702   main_thread->initialize_thread_current();
3703   // must do this before set_active_handles
3704   main_thread->record_stack_base_and_size();
3705   main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3706 
3707   if (!main_thread->set_as_starting_thread()) {
3708     vm_shutdown_during_initialization(
3709                                       "Failed necessary internal allocation. Out of swap space");
3710     main_thread->smr_delete();
3711     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3712     return JNI_ENOMEM;
3713   }
3714 
3715   // Enable guard page *after* os::create_main_thread(), otherwise it would
3716   // crash Linux VM, see notes in os_linux.cpp.
3717   main_thread->create_stack_guard_pages();
3718 
3719   // Initialize Java-Level synchronization subsystem
3720   ObjectMonitor::Initialize();
3721 
3722   // Initialize global modules
3723   jint status = init_globals();
3724   if (status != JNI_OK) {
3725     main_thread->smr_delete();
3726     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3727     return status;
3728   }
3729 
3730   if (TRACE_INITIALIZE() != JNI_OK) {
3731     vm_exit_during_initialization("Failed to initialize tracing backend");
3732   }
3733 
3734   // Should be done after the heap is fully created
3735   main_thread->cache_global_variables();
3736 
3737   HandleMark hm;
3738 
3739   { MutexLocker mu(Threads_lock);
3740     Threads::add(main_thread);
3741   }
3742 
3743   // Any JVMTI raw monitors entered in onload will transition into
3744   // real raw monitor. VM is setup enough here for raw monitor enter.
3745   JvmtiExport::transition_pending_onload_raw_monitors();
3746 
3747   // Create the VMThread
3748   { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3749 
3750   VMThread::create();
3751     Thread* vmthread = VMThread::vm_thread();
3752 
3753     if (!os::create_thread(vmthread, os::vm_thread)) {
3754       vm_exit_during_initialization("Cannot create VM thread. "
3755                                     "Out of system resources.");
3756     }
3757 
3758     // Wait for the VM thread to become ready, and VMThread::run to initialize
3759     // Monitors can have spurious returns, must always check another state flag
3760     {
3761       MutexLocker ml(Notify_lock);
3762       os::start_thread(vmthread);
3763       while (vmthread->active_handles() == NULL) {
3764         Notify_lock->wait();
3765       }
3766     }
3767   }
3768 
3769   assert(Universe::is_fully_initialized(), "not initialized");
3770   if (VerifyDuringStartup) {
3771     // Make sure we're starting with a clean slate.
3772     VM_Verify verify_op;
3773     VMThread::execute(&verify_op);
3774   }
3775 
3776   Thread* THREAD = Thread::current();
3777 
3778   // Always call even when there are not JVMTI environments yet, since environments
3779   // may be attached late and JVMTI must track phases of VM execution
3780   JvmtiExport::enter_early_start_phase();
3781 
3782   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3783   JvmtiExport::post_early_vm_start();
3784 
3785   initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3786 
3787   // We need this for ClassDataSharing - the initial vm.info property is set
3788   // with the default value of CDS "sharing" which may be reset through
3789   // command line options.
3790   reset_vm_info_property(CHECK_JNI_ERR);
3791 
3792   quicken_jni_functions();
3793 
3794   // No more stub generation allowed after that point.
3795   StubCodeDesc::freeze();
3796 
3797   // Set flag that basic initialization has completed. Used by exceptions and various
3798   // debug stuff, that does not work until all basic classes have been initialized.
3799   set_init_completed();
3800 
3801   LogConfiguration::post_initialize();
3802   Metaspace::post_initialize();
3803 
3804   HOTSPOT_VM_INIT_END();
3805 
3806   // record VM initialization completion time
3807 #if INCLUDE_MANAGEMENT
3808   Management::record_vm_init_completed();
3809 #endif // INCLUDE_MANAGEMENT
3810 
3811   // Signal Dispatcher needs to be started before VMInit event is posted
3812   os::signal_init(CHECK_JNI_ERR);
3813 
3814   // Start Attach Listener if +StartAttachListener or it can't be started lazily
3815   if (!DisableAttachMechanism) {
3816     AttachListener::vm_start();
3817     if (StartAttachListener || AttachListener::init_at_startup()) {
3818       AttachListener::init();
3819     }
3820   }
3821 
3822   // Launch -Xrun agents
3823   // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3824   // back-end can launch with -Xdebug -Xrunjdwp.
3825   if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3826     create_vm_init_libraries();
3827   }
3828 
3829   if (CleanChunkPoolAsync) {
3830     Chunk::start_chunk_pool_cleaner_task();
3831   }
3832 
3833   // initialize compiler(s)
3834 #if defined(COMPILER1) || COMPILER2_OR_JVMCI
3835   CompileBroker::compilation_init(CHECK_JNI_ERR);
3836 #endif
3837 
3838   // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3839   // It is done after compilers are initialized, because otherwise compilations of
3840   // signature polymorphic MH intrinsics can be missed
3841   // (see SystemDictionary::find_method_handle_intrinsic).
3842   initialize_jsr292_core_classes(CHECK_JNI_ERR);
3843 
3844   // This will initialize the module system.  Only java.base classes can be
3845   // loaded until phase 2 completes
3846   call_initPhase2(CHECK_JNI_ERR);
3847 
3848   // Always call even when there are not JVMTI environments yet, since environments
3849   // may be attached late and JVMTI must track phases of VM execution
3850   JvmtiExport::enter_start_phase();
3851 
3852   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3853   JvmtiExport::post_vm_start();
3854 
3855   // Final system initialization including security manager and system class loader
3856   call_initPhase3(CHECK_JNI_ERR);
3857 
3858   // cache the system and platform class loaders
3859   SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
3860 
3861 #if INCLUDE_JVMCI
3862   if (EnableJVMCI) {
3863     // Initialize JVMCI eagerly if JVMCIPrintProperties is enabled.
3864     // The JVMCI Java initialization code will read this flag and
3865     // do the printing if it's set.
3866     bool init = JVMCIPrintProperties;
3867 
3868     if (!init) {
3869       // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3870       // compilations via JVMCI will not actually block until JVMCI is initialized.
3871       init = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3872     }
3873 
3874     if (init) {
3875       JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
3876     }
3877   }
3878 #endif
3879 
3880   // Always call even when there are not JVMTI environments yet, since environments
3881   // may be attached late and JVMTI must track phases of VM execution
3882   JvmtiExport::enter_live_phase();
3883 
3884   // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3885   JvmtiExport::post_vm_initialized();
3886 
3887   if (TRACE_START() != JNI_OK) {
3888     vm_exit_during_initialization("Failed to start tracing backend.");
3889   }
3890 
3891 #if INCLUDE_MANAGEMENT
3892   Management::initialize(THREAD);
3893 
3894   if (HAS_PENDING_EXCEPTION) {
3895     // management agent fails to start possibly due to
3896     // configuration problem and is responsible for printing
3897     // stack trace if appropriate. Simply exit VM.
3898     vm_exit(1);
3899   }
3900 #endif // INCLUDE_MANAGEMENT
3901 
3902   if (MemProfiling)                   MemProfiler::engage();
3903   StatSampler::engage();
3904   if (CheckJNICalls)                  JniPeriodicChecker::engage();
3905 
3906   BiasedLocking::init();
3907 
3908 #if INCLUDE_RTM_OPT
3909   RTMLockingCounters::init();
3910 #endif
3911 
3912   if (JDK_Version::current().post_vm_init_hook_enabled()) {
3913     call_postVMInitHook(THREAD);
3914     // The Java side of PostVMInitHook.run must deal with all
3915     // exceptions and provide means of diagnosis.
3916     if (HAS_PENDING_EXCEPTION) {
3917       CLEAR_PENDING_EXCEPTION;
3918     }
3919   }
3920 
3921   {
3922     MutexLocker ml(PeriodicTask_lock);
3923     // Make sure the WatcherThread can be started by WatcherThread::start()
3924     // or by dynamic enrollment.
3925     WatcherThread::make_startable();
3926     // Start up the WatcherThread if there are any periodic tasks
3927     // NOTE:  All PeriodicTasks should be registered by now. If they
3928     //   aren't, late joiners might appear to start slowly (we might
3929     //   take a while to process their first tick).
3930     if (PeriodicTask::num_tasks() > 0) {
3931       WatcherThread::start();
3932     }
3933   }
3934 
3935   create_vm_timer.end();
3936 #ifdef ASSERT
3937   _vm_complete = true;
3938 #endif
3939 
3940   if (DumpSharedSpaces) {
3941     MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3942     ShouldNotReachHere();
3943   }
3944 
3945   return JNI_OK;
3946 }
3947 
3948 // type for the Agent_OnLoad and JVM_OnLoad entry points
3949 extern "C" {
3950   typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3951 }
3952 // Find a command line agent library and return its entry point for
3953 //         -agentlib:  -agentpath:   -Xrun
3954 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3955 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3956                                     const char *on_load_symbols[],
3957                                     size_t num_symbol_entries) {
3958   OnLoadEntry_t on_load_entry = NULL;
3959   void *library = NULL;
3960 
3961   if (!agent->valid()) {
3962     char buffer[JVM_MAXPATHLEN];
3963     char ebuf[1024] = "";
3964     const char *name = agent->name();
3965     const char *msg = "Could not find agent library ";
3966 
3967     // First check to see if agent is statically linked into executable
3968     if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3969       library = agent->os_lib();
3970     } else if (agent->is_absolute_path()) {
3971       library = os::dll_load(name, ebuf, sizeof ebuf);
3972       if (library == NULL) {
3973         const char *sub_msg = " in absolute path, with error: ";
3974         size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3975         char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3976         jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3977         // If we can't find the agent, exit.
3978         vm_exit_during_initialization(buf, NULL);
3979         FREE_C_HEAP_ARRAY(char, buf);
3980       }
3981     } else {
3982       // Try to load the agent from the standard dll directory
3983       if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
3984                              name)) {
3985         library = os::dll_load(buffer, ebuf, sizeof ebuf);
3986       }
3987       if (library == NULL) { // Try the library path directory.
3988         if (os::dll_build_name(buffer, sizeof(buffer), name)) {
3989           library = os::dll_load(buffer, ebuf, sizeof ebuf);
3990         }
3991         if (library == NULL) {
3992           const char *sub_msg = " on the library path, with error: ";
3993           const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image.";
3994 
3995           size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) +
3996                        strlen(ebuf) + strlen(sub_msg2) + 1;
3997           char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3998           if (!agent->is_instrument_lib()) {
3999             jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4000           } else {
4001             jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2);
4002           }
4003           // If we can't find the agent, exit.
4004           vm_exit_during_initialization(buf, NULL);
4005           FREE_C_HEAP_ARRAY(char, buf);
4006         }
4007       }
4008     }
4009     agent->set_os_lib(library);
4010     agent->set_valid();
4011   }
4012 
4013   // Find the OnLoad function.
4014   on_load_entry =
4015     CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
4016                                                           false,
4017                                                           on_load_symbols,
4018                                                           num_symbol_entries));
4019   return on_load_entry;
4020 }
4021 
4022 // Find the JVM_OnLoad entry point
4023 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
4024   const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
4025   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4026 }
4027 
4028 // Find the Agent_OnLoad entry point
4029 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
4030   const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
4031   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4032 }
4033 
4034 // For backwards compatibility with -Xrun
4035 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
4036 // treated like -agentpath:
4037 // Must be called before agent libraries are created
4038 void Threads::convert_vm_init_libraries_to_agents() {
4039   AgentLibrary* agent;
4040   AgentLibrary* next;
4041 
4042   for (agent = Arguments::libraries(); agent != NULL; agent = next) {
4043     next = agent->next();  // cache the next agent now as this agent may get moved off this list
4044     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4045 
4046     // If there is an JVM_OnLoad function it will get called later,
4047     // otherwise see if there is an Agent_OnLoad
4048     if (on_load_entry == NULL) {
4049       on_load_entry = lookup_agent_on_load(agent);
4050       if (on_load_entry != NULL) {
4051         // switch it to the agent list -- so that Agent_OnLoad will be called,
4052         // JVM_OnLoad won't be attempted and Agent_OnUnload will
4053         Arguments::convert_library_to_agent(agent);
4054       } else {
4055         vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
4056       }
4057     }
4058   }
4059 }
4060 
4061 // Create agents for -agentlib:  -agentpath:  and converted -Xrun
4062 // Invokes Agent_OnLoad
4063 // Called very early -- before JavaThreads exist
4064 void Threads::create_vm_init_agents() {
4065   extern struct JavaVM_ main_vm;
4066   AgentLibrary* agent;
4067 
4068   JvmtiExport::enter_onload_phase();
4069 
4070   for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4071     OnLoadEntry_t  on_load_entry = lookup_agent_on_load(agent);
4072 
4073     if (on_load_entry != NULL) {
4074       // Invoke the Agent_OnLoad function
4075       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4076       if (err != JNI_OK) {
4077         vm_exit_during_initialization("agent library failed to init", agent->name());
4078       }
4079     } else {
4080       vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4081     }
4082   }
4083   JvmtiExport::enter_primordial_phase();
4084 }
4085 
4086 extern "C" {
4087   typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4088 }
4089 
4090 void Threads::shutdown_vm_agents() {
4091   // Send any Agent_OnUnload notifications
4092   const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4093   size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4094   extern struct JavaVM_ main_vm;
4095   for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4096 
4097     // Find the Agent_OnUnload function.
4098     Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4099                                                    os::find_agent_function(agent,
4100                                                    false,
4101                                                    on_unload_symbols,
4102                                                    num_symbol_entries));
4103 
4104     // Invoke the Agent_OnUnload function
4105     if (unload_entry != NULL) {
4106       JavaThread* thread = JavaThread::current();
4107       ThreadToNativeFromVM ttn(thread);
4108       HandleMark hm(thread);
4109       (*unload_entry)(&main_vm);
4110     }
4111   }
4112 }
4113 
4114 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4115 // Invokes JVM_OnLoad
4116 void Threads::create_vm_init_libraries() {
4117   extern struct JavaVM_ main_vm;
4118   AgentLibrary* agent;
4119 
4120   for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4121     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4122 
4123     if (on_load_entry != NULL) {
4124       // Invoke the JVM_OnLoad function
4125       JavaThread* thread = JavaThread::current();
4126       ThreadToNativeFromVM ttn(thread);
4127       HandleMark hm(thread);
4128       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4129       if (err != JNI_OK) {
4130         vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4131       }
4132     } else {
4133       vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4134     }
4135   }
4136 }
4137 
4138 
4139 // Last thread running calls java.lang.Shutdown.shutdown()
4140 void JavaThread::invoke_shutdown_hooks() {
4141   HandleMark hm(this);
4142 
4143   // We could get here with a pending exception, if so clear it now.
4144   if (this->has_pending_exception()) {
4145     this->clear_pending_exception();
4146   }
4147 
4148   EXCEPTION_MARK;
4149   Klass* shutdown_klass =
4150     SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4151                                       THREAD);
4152   if (shutdown_klass != NULL) {
4153     // SystemDictionary::resolve_or_null will return null if there was
4154     // an exception.  If we cannot load the Shutdown class, just don't
4155     // call Shutdown.shutdown() at all.  This will mean the shutdown hooks
4156     // and finalizers (if runFinalizersOnExit is set) won't be run.
4157     // Note that if a shutdown hook was registered or runFinalizersOnExit
4158     // was called, the Shutdown class would have already been loaded
4159     // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
4160     JavaValue result(T_VOID);
4161     JavaCalls::call_static(&result,
4162                            shutdown_klass,
4163                            vmSymbols::shutdown_method_name(),
4164                            vmSymbols::void_method_signature(),
4165                            THREAD);
4166   }
4167   CLEAR_PENDING_EXCEPTION;
4168 }
4169 
4170 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4171 // the program falls off the end of main(). Another VM exit path is through
4172 // vm_exit() when the program calls System.exit() to return a value or when
4173 // there is a serious error in VM. The two shutdown paths are not exactly
4174 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4175 // and VM_Exit op at VM level.
4176 //
4177 // Shutdown sequence:
4178 //   + Shutdown native memory tracking if it is on
4179 //   + Wait until we are the last non-daemon thread to execute
4180 //     <-- every thing is still working at this moment -->
4181 //   + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4182 //        shutdown hooks, run finalizers if finalization-on-exit
4183 //   + Call before_exit(), prepare for VM exit
4184 //      > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4185 //        currently the only user of this mechanism is File.deleteOnExit())
4186 //      > stop StatSampler, watcher thread, CMS threads,
4187 //        post thread end and vm death events to JVMTI,
4188 //        stop signal thread
4189 //   + Call JavaThread::exit(), it will:
4190 //      > release JNI handle blocks, remove stack guard pages
4191 //      > remove this thread from Threads list
4192 //     <-- no more Java code from this thread after this point -->
4193 //   + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4194 //     the compiler threads at safepoint
4195 //     <-- do not use anything that could get blocked by Safepoint -->
4196 //   + Disable tracing at JNI/JVM barriers
4197 //   + Set _vm_exited flag for threads that are still running native code
4198 //   + Delete this thread
4199 //   + Call exit_globals()
4200 //      > deletes tty
4201 //      > deletes PerfMemory resources
4202 //   + Return to caller
4203 
4204 bool Threads::destroy_vm() {
4205   JavaThread* thread = JavaThread::current();
4206 
4207 #ifdef ASSERT
4208   _vm_complete = false;
4209 #endif
4210   // Wait until we are the last non-daemon thread to execute
4211   { MutexLocker nu(Threads_lock);
4212     while (Threads::number_of_non_daemon_threads() > 1)
4213       // This wait should make safepoint checks, wait without a timeout,
4214       // and wait as a suspend-equivalent condition.
4215       Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4216                          Mutex::_as_suspend_equivalent_flag);
4217   }
4218 
4219   EventShutdown e;
4220   if (e.should_commit()) {
4221     e.set_reason("No remaining non-daemon Java threads");
4222     e.commit();
4223   }
4224 
4225   // Hang forever on exit if we are reporting an error.
4226   if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4227     os::infinite_sleep();
4228   }
4229   os::wait_for_keypress_at_exit();
4230 
4231   // run Java level shutdown hooks
4232   thread->invoke_shutdown_hooks();
4233 
4234   before_exit(thread);
4235 
4236   thread->exit(true);
4237 
4238   // Stop VM thread.
4239   {
4240     // 4945125 The vm thread comes to a safepoint during exit.
4241     // GC vm_operations can get caught at the safepoint, and the
4242     // heap is unparseable if they are caught. Grab the Heap_lock
4243     // to prevent this. The GC vm_operations will not be able to
4244     // queue until after the vm thread is dead. After this point,
4245     // we'll never emerge out of the safepoint before the VM exits.
4246 
4247     MutexLocker ml(Heap_lock);
4248 
4249     VMThread::wait_for_vm_thread_exit();
4250     assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4251     VMThread::destroy();
4252   }
4253 
4254   // clean up ideal graph printers
4255 #if defined(COMPILER2) && !defined(PRODUCT)
4256   IdealGraphPrinter::clean_up();
4257 #endif
4258 
4259   // Now, all Java threads are gone except daemon threads. Daemon threads
4260   // running Java code or in VM are stopped by the Safepoint. However,
4261   // daemon threads executing native code are still running.  But they
4262   // will be stopped at native=>Java/VM barriers. Note that we can't
4263   // simply kill or suspend them, as it is inherently deadlock-prone.
4264 
4265   VM_Exit::set_vm_exited();
4266 
4267   notify_vm_shutdown();
4268 
4269   // We are after VM_Exit::set_vm_exited() so we can't call
4270   // thread->smr_delete() or we will block on the Threads_lock.
4271   // Deleting the shutdown thread here is safe because another
4272   // JavaThread cannot have an active ThreadsListHandle for
4273   // this JavaThread.
4274   delete thread;
4275 
4276 #if INCLUDE_JVMCI
4277   if (JVMCICounterSize > 0) {
4278     FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4279   }
4280 #endif
4281 
4282   // exit_globals() will delete tty
4283   exit_globals();
4284 
4285   LogConfiguration::finalize();
4286 
4287   return true;
4288 }
4289 
4290 
4291 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4292   if (version == JNI_VERSION_1_1) return JNI_TRUE;
4293   return is_supported_jni_version(version);
4294 }
4295 
4296 
4297 jboolean Threads::is_supported_jni_version(jint version) {
4298   if (version == JNI_VERSION_1_2) return JNI_TRUE;
4299   if (version == JNI_VERSION_1_4) return JNI_TRUE;
4300   if (version == JNI_VERSION_1_6) return JNI_TRUE;
4301   if (version == JNI_VERSION_1_8) return JNI_TRUE;
4302   if (version == JNI_VERSION_9) return JNI_TRUE;
4303   if (version == JNI_VERSION_10) return JNI_TRUE;
4304   return JNI_FALSE;
4305 }
4306 
4307 
4308 void Threads::add(JavaThread* p, bool force_daemon) {
4309   // The threads lock must be owned at this point
4310   assert_locked_or_safepoint(Threads_lock);
4311 
4312   BarrierSet::barrier_set()->on_thread_attach(p);
4313 
4314   p->set_next(_thread_list);
4315   _thread_list = p;
4316 
4317   // Once a JavaThread is added to the Threads list, smr_delete() has
4318   // to be used to delete it. Otherwise we can just delete it directly.
4319   p->set_on_thread_list();
4320 
4321   _number_of_threads++;
4322   oop threadObj = p->threadObj();
4323   bool daemon = true;
4324   // Bootstrapping problem: threadObj can be null for initial
4325   // JavaThread (or for threads attached via JNI)
4326   if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4327     _number_of_non_daemon_threads++;
4328     daemon = false;
4329   }
4330 
4331   ThreadService::add_thread(p, daemon);
4332 
4333   // Maintain fast thread list
4334   ThreadsSMRSupport::add_thread(p);
4335 
4336   // Possible GC point.
4337   Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4338 }
4339 
4340 void Threads::remove(JavaThread* p) {
4341 
4342   // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread.
4343   ObjectSynchronizer::omFlush(p);
4344 
4345   // Extra scope needed for Thread_lock, so we can check
4346   // that we do not remove thread without safepoint code notice
4347   { MutexLocker ml(Threads_lock);
4348 
4349     assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present");
4350 
4351     // Maintain fast thread list
4352     ThreadsSMRSupport::remove_thread(p);
4353 
4354     JavaThread* current = _thread_list;
4355     JavaThread* prev    = NULL;
4356 
4357     while (current != p) {
4358       prev    = current;
4359       current = current->next();
4360     }
4361 
4362     if (prev) {
4363       prev->set_next(current->next());
4364     } else {
4365       _thread_list = p->next();
4366     }
4367 
4368     _number_of_threads--;
4369     oop threadObj = p->threadObj();
4370     bool daemon = true;
4371     if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4372       _number_of_non_daemon_threads--;
4373       daemon = false;
4374 
4375       // Only one thread left, do a notify on the Threads_lock so a thread waiting
4376       // on destroy_vm will wake up.
4377       if (number_of_non_daemon_threads() == 1) {
4378         Threads_lock->notify_all();
4379       }
4380     }
4381     ThreadService::remove_thread(p, daemon);
4382 
4383     // Make sure that safepoint code disregard this thread. This is needed since
4384     // the thread might mess around with locks after this point. This can cause it
4385     // to do callbacks into the safepoint code. However, the safepoint code is not aware
4386     // of this thread since it is removed from the queue.
4387     p->set_terminated_value();
4388   } // unlock Threads_lock
4389 
4390   // Since Events::log uses a lock, we grab it outside the Threads_lock
4391   Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4392 }
4393 
4394 // Operations on the Threads list for GC.  These are not explicitly locked,
4395 // but the garbage collector must provide a safe context for them to run.
4396 // In particular, these things should never be called when the Threads_lock
4397 // is held by some other thread. (Note: the Safepoint abstraction also
4398 // uses the Threads_lock to guarantee this property. It also makes sure that
4399 // all threads gets blocked when exiting or starting).
4400 
4401 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4402   ALL_JAVA_THREADS(p) {
4403     p->oops_do(f, cf);
4404   }
4405   VMThread::vm_thread()->oops_do(f, cf);
4406 }
4407 
4408 void Threads::change_thread_claim_parity() {
4409   // Set the new claim parity.
4410   assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4411          "Not in range.");
4412   _thread_claim_parity++;
4413   if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4414   assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4415          "Not in range.");
4416 }
4417 
4418 #ifdef ASSERT
4419 void Threads::assert_all_threads_claimed() {
4420   ALL_JAVA_THREADS(p) {
4421     const int thread_parity = p->oops_do_parity();
4422     assert((thread_parity == _thread_claim_parity),
4423            "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4424   }
4425   VMThread* vmt = VMThread::vm_thread();
4426   const int thread_parity = vmt->oops_do_parity();
4427   assert((thread_parity == _thread_claim_parity),
4428          "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity);
4429 }
4430 #endif // ASSERT
4431 
4432 class ParallelOopsDoThreadClosure : public ThreadClosure {
4433 private:
4434   OopClosure* _f;
4435   CodeBlobClosure* _cf;
4436 public:
4437   ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {}
4438   void do_thread(Thread* t) {
4439     t->oops_do(_f, _cf);
4440   }
4441 };
4442 
4443 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4444   ParallelOopsDoThreadClosure tc(f, cf);
4445   possibly_parallel_threads_do(is_par, &tc);
4446 }
4447 
4448 #if INCLUDE_ALL_GCS
4449 // Used by ParallelScavenge
4450 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4451   ALL_JAVA_THREADS(p) {
4452     q->enqueue(new ThreadRootsTask(p));
4453   }
4454   q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4455 }
4456 
4457 // Used by Parallel Old
4458 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4459   ALL_JAVA_THREADS(p) {
4460     q->enqueue(new ThreadRootsMarkingTask(p));
4461   }
4462   q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4463 }
4464 #endif // INCLUDE_ALL_GCS
4465 
4466 void Threads::nmethods_do(CodeBlobClosure* cf) {
4467   ALL_JAVA_THREADS(p) {
4468     // This is used by the code cache sweeper to mark nmethods that are active
4469     // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4470     // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4471     if(!p->is_Code_cache_sweeper_thread()) {
4472       p->nmethods_do(cf);
4473     }
4474   }
4475 }
4476 
4477 void Threads::metadata_do(void f(Metadata*)) {
4478   ALL_JAVA_THREADS(p) {
4479     p->metadata_do(f);
4480   }
4481 }
4482 
4483 class ThreadHandlesClosure : public ThreadClosure {
4484   void (*_f)(Metadata*);
4485  public:
4486   ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4487   virtual void do_thread(Thread* thread) {
4488     thread->metadata_handles_do(_f);
4489   }
4490 };
4491 
4492 void Threads::metadata_handles_do(void f(Metadata*)) {
4493   // Only walk the Handles in Thread.
4494   ThreadHandlesClosure handles_closure(f);
4495   threads_do(&handles_closure);
4496 }
4497 
4498 void Threads::deoptimized_wrt_marked_nmethods() {
4499   ALL_JAVA_THREADS(p) {
4500     p->deoptimized_wrt_marked_nmethods();
4501   }
4502 }
4503 
4504 
4505 // Get count Java threads that are waiting to enter the specified monitor.
4506 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
4507                                                          int count,
4508                                                          address monitor) {
4509   GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4510 
4511   int i = 0;
4512   DO_JAVA_THREADS(t_list, p) {
4513     if (!p->can_call_java()) continue;
4514 
4515     address pending = (address)p->current_pending_monitor();
4516     if (pending == monitor) {             // found a match
4517       if (i < count) result->append(p);   // save the first count matches
4518       i++;
4519     }
4520   }
4521 
4522   return result;
4523 }
4524 
4525 
4526 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
4527                                                       address owner) {
4528   // NULL owner means not locked so we can skip the search
4529   if (owner == NULL) return NULL;
4530 
4531   DO_JAVA_THREADS(t_list, p) {
4532     // first, see if owner is the address of a Java thread
4533     if (owner == (address)p) return p;
4534   }
4535 
4536   // Cannot assert on lack of success here since this function may be
4537   // used by code that is trying to report useful problem information
4538   // like deadlock detection.
4539   if (UseHeavyMonitors) return NULL;
4540 
4541   // If we didn't find a matching Java thread and we didn't force use of
4542   // heavyweight monitors, then the owner is the stack address of the
4543   // Lock Word in the owning Java thread's stack.
4544   //
4545   JavaThread* the_owner = NULL;
4546   DO_JAVA_THREADS(t_list, q) {
4547     if (q->is_lock_owned(owner)) {
4548       the_owner = q;
4549       break;
4550     }
4551   }
4552 
4553   // cannot assert on lack of success here; see above comment
4554   return the_owner;
4555 }
4556 
4557 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4558 void Threads::print_on(outputStream* st, bool print_stacks,
4559                        bool internal_format, bool print_concurrent_locks) {
4560   char buf[32];
4561   st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4562 
4563   st->print_cr("Full thread dump %s (%s %s):",
4564                Abstract_VM_Version::vm_name(),
4565                Abstract_VM_Version::vm_release(),
4566                Abstract_VM_Version::vm_info_string());
4567   st->cr();
4568 
4569 #if INCLUDE_SERVICES
4570   // Dump concurrent locks
4571   ConcurrentLocksDump concurrent_locks;
4572   if (print_concurrent_locks) {
4573     concurrent_locks.dump_at_safepoint();
4574   }
4575 #endif // INCLUDE_SERVICES
4576 
4577   ThreadsSMRSupport::print_info_on(st);
4578   st->cr();
4579 
4580   ALL_JAVA_THREADS(p) {
4581     ResourceMark rm;
4582     p->print_on(st);
4583     if (print_stacks) {
4584       if (internal_format) {
4585         p->trace_stack();
4586       } else {
4587         p->print_stack_on(st);
4588       }
4589     }
4590     st->cr();
4591 #if INCLUDE_SERVICES
4592     if (print_concurrent_locks) {
4593       concurrent_locks.print_locks_on(p, st);
4594     }
4595 #endif // INCLUDE_SERVICES
4596   }
4597 
4598   VMThread::vm_thread()->print_on(st);
4599   st->cr();
4600   Universe::heap()->print_gc_threads_on(st);
4601   WatcherThread* wt = WatcherThread::watcher_thread();
4602   if (wt != NULL) {
4603     wt->print_on(st);
4604     st->cr();
4605   }
4606 
4607   st->flush();
4608 }
4609 
4610 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4611                              int buflen, bool* found_current) {
4612   if (this_thread != NULL) {
4613     bool is_current = (current == this_thread);
4614     *found_current = *found_current || is_current;
4615     st->print("%s", is_current ? "=>" : "  ");
4616 
4617     st->print(PTR_FORMAT, p2i(this_thread));
4618     st->print(" ");
4619     this_thread->print_on_error(st, buf, buflen);
4620     st->cr();
4621   }
4622 }
4623 
4624 class PrintOnErrorClosure : public ThreadClosure {
4625   outputStream* _st;
4626   Thread* _current;
4627   char* _buf;
4628   int _buflen;
4629   bool* _found_current;
4630  public:
4631   PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4632                       int buflen, bool* found_current) :
4633    _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4634 
4635   virtual void do_thread(Thread* thread) {
4636     Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4637   }
4638 };
4639 
4640 // Threads::print_on_error() is called by fatal error handler. It's possible
4641 // that VM is not at safepoint and/or current thread is inside signal handler.
4642 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4643 // memory (even in resource area), it might deadlock the error handler.
4644 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4645                              int buflen) {
4646   ThreadsSMRSupport::print_info_on(st);
4647   st->cr();
4648 
4649   bool found_current = false;
4650   st->print_cr("Java Threads: ( => current thread )");
4651   ALL_JAVA_THREADS(thread) {
4652     print_on_error(thread, st, current, buf, buflen, &found_current);
4653   }
4654   st->cr();
4655 
4656   st->print_cr("Other Threads:");
4657   print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4658   print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4659 
4660   PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4661   Universe::heap()->gc_threads_do(&print_closure);
4662 
4663   if (!found_current) {
4664     st->cr();
4665     st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4666     current->print_on_error(st, buf, buflen);
4667     st->cr();
4668   }
4669   st->cr();
4670 
4671   st->print_cr("Threads with active compile tasks:");
4672   print_threads_compiling(st, buf, buflen);
4673 }
4674 
4675 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4676   ALL_JAVA_THREADS(thread) {
4677     if (thread->is_Compiler_thread()) {
4678       CompilerThread* ct = (CompilerThread*) thread;
4679 
4680       // Keep task in local variable for NULL check.
4681       // ct->_task might be set to NULL by concurring compiler thread
4682       // because it completed the compilation. The task is never freed,
4683       // though, just returned to a free list.
4684       CompileTask* task = ct->task();
4685       if (task != NULL) {
4686         thread->print_name_on_error(st, buf, buflen);
4687         task->print(st, NULL, true, true);
4688       }
4689     }
4690   }
4691 }
4692 
4693 
4694 // Internal SpinLock and Mutex
4695 // Based on ParkEvent
4696 
4697 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4698 //
4699 // We employ SpinLocks _only for low-contention, fixed-length
4700 // short-duration critical sections where we're concerned
4701 // about native mutex_t or HotSpot Mutex:: latency.
4702 // The mux construct provides a spin-then-block mutual exclusion
4703 // mechanism.
4704 //
4705 // Testing has shown that contention on the ListLock guarding gFreeList
4706 // is common.  If we implement ListLock as a simple SpinLock it's common
4707 // for the JVM to devolve to yielding with little progress.  This is true
4708 // despite the fact that the critical sections protected by ListLock are
4709 // extremely short.
4710 //
4711 // TODO-FIXME: ListLock should be of type SpinLock.
4712 // We should make this a 1st-class type, integrated into the lock
4713 // hierarchy as leaf-locks.  Critically, the SpinLock structure
4714 // should have sufficient padding to avoid false-sharing and excessive
4715 // cache-coherency traffic.
4716 
4717 
4718 typedef volatile int SpinLockT;
4719 
4720 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4721   if (Atomic::cmpxchg (1, adr, 0) == 0) {
4722     return;   // normal fast-path return
4723   }
4724 
4725   // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4726   TEVENT(SpinAcquire - ctx);
4727   int ctr = 0;
4728   int Yields = 0;
4729   for (;;) {
4730     while (*adr != 0) {
4731       ++ctr;
4732       if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4733         if (Yields > 5) {
4734           os::naked_short_sleep(1);
4735         } else {
4736           os::naked_yield();
4737           ++Yields;
4738         }
4739       } else {
4740         SpinPause();
4741       }
4742     }
4743     if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4744   }
4745 }
4746 
4747 void Thread::SpinRelease(volatile int * adr) {
4748   assert(*adr != 0, "invariant");
4749   OrderAccess::fence();      // guarantee at least release consistency.
4750   // Roach-motel semantics.
4751   // It's safe if subsequent LDs and STs float "up" into the critical section,
4752   // but prior LDs and STs within the critical section can't be allowed
4753   // to reorder or float past the ST that releases the lock.
4754   // Loads and stores in the critical section - which appear in program
4755   // order before the store that releases the lock - must also appear
4756   // before the store that releases the lock in memory visibility order.
4757   // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4758   // the ST of 0 into the lock-word which releases the lock, so fence
4759   // more than covers this on all platforms.
4760   *adr = 0;
4761 }
4762 
4763 // muxAcquire and muxRelease:
4764 //
4765 // *  muxAcquire and muxRelease support a single-word lock-word construct.
4766 //    The LSB of the word is set IFF the lock is held.
4767 //    The remainder of the word points to the head of a singly-linked list
4768 //    of threads blocked on the lock.
4769 //
4770 // *  The current implementation of muxAcquire-muxRelease uses its own
4771 //    dedicated Thread._MuxEvent instance.  If we're interested in
4772 //    minimizing the peak number of extant ParkEvent instances then
4773 //    we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4774 //    as certain invariants were satisfied.  Specifically, care would need
4775 //    to be taken with regards to consuming unpark() "permits".
4776 //    A safe rule of thumb is that a thread would never call muxAcquire()
4777 //    if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4778 //    park().  Otherwise the _ParkEvent park() operation in muxAcquire() could
4779 //    consume an unpark() permit intended for monitorenter, for instance.
4780 //    One way around this would be to widen the restricted-range semaphore
4781 //    implemented in park().  Another alternative would be to provide
4782 //    multiple instances of the PlatformEvent() for each thread.  One
4783 //    instance would be dedicated to muxAcquire-muxRelease, for instance.
4784 //
4785 // *  Usage:
4786 //    -- Only as leaf locks
4787 //    -- for short-term locking only as muxAcquire does not perform
4788 //       thread state transitions.
4789 //
4790 // Alternatives:
4791 // *  We could implement muxAcquire and muxRelease with MCS or CLH locks
4792 //    but with parking or spin-then-park instead of pure spinning.
4793 // *  Use Taura-Oyama-Yonenzawa locks.
4794 // *  It's possible to construct a 1-0 lock if we encode the lockword as
4795 //    (List,LockByte).  Acquire will CAS the full lockword while Release
4796 //    will STB 0 into the LockByte.  The 1-0 scheme admits stranding, so
4797 //    acquiring threads use timers (ParkTimed) to detect and recover from
4798 //    the stranding window.  Thread/Node structures must be aligned on 256-byte
4799 //    boundaries by using placement-new.
4800 // *  Augment MCS with advisory back-link fields maintained with CAS().
4801 //    Pictorially:  LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4802 //    The validity of the backlinks must be ratified before we trust the value.
4803 //    If the backlinks are invalid the exiting thread must back-track through the
4804 //    the forward links, which are always trustworthy.
4805 // *  Add a successor indication.  The LockWord is currently encoded as
4806 //    (List, LOCKBIT:1).  We could also add a SUCCBIT or an explicit _succ variable
4807 //    to provide the usual futile-wakeup optimization.
4808 //    See RTStt for details.
4809 // *  Consider schedctl.sc_nopreempt to cover the critical section.
4810 //
4811 
4812 
4813 const intptr_t LOCKBIT = 1;
4814 
4815 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4816   intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4817   if (w == 0) return;
4818   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4819     return;
4820   }
4821 
4822   TEVENT(muxAcquire - Contention);
4823   ParkEvent * const Self = Thread::current()->_MuxEvent;
4824   assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4825   for (;;) {
4826     int its = (os::is_MP() ? 100 : 0) + 1;
4827 
4828     // Optional spin phase: spin-then-park strategy
4829     while (--its >= 0) {
4830       w = *Lock;
4831       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4832         return;
4833       }
4834     }
4835 
4836     Self->reset();
4837     Self->OnList = intptr_t(Lock);
4838     // The following fence() isn't _strictly necessary as the subsequent
4839     // CAS() both serializes execution and ratifies the fetched *Lock value.
4840     OrderAccess::fence();
4841     for (;;) {
4842       w = *Lock;
4843       if ((w & LOCKBIT) == 0) {
4844         if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4845           Self->OnList = 0;   // hygiene - allows stronger asserts
4846           return;
4847         }
4848         continue;      // Interference -- *Lock changed -- Just retry
4849       }
4850       assert(w & LOCKBIT, "invariant");
4851       Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4852       if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4853     }
4854 
4855     while (Self->OnList != 0) {
4856       Self->park();
4857     }
4858   }
4859 }
4860 
4861 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4862   intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4863   if (w == 0) return;
4864   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4865     return;
4866   }
4867 
4868   TEVENT(muxAcquire - Contention);
4869   ParkEvent * ReleaseAfter = NULL;
4870   if (ev == NULL) {
4871     ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4872   }
4873   assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4874   for (;;) {
4875     guarantee(ev->OnList == 0, "invariant");
4876     int its = (os::is_MP() ? 100 : 0) + 1;
4877 
4878     // Optional spin phase: spin-then-park strategy
4879     while (--its >= 0) {
4880       w = *Lock;
4881       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4882         if (ReleaseAfter != NULL) {
4883           ParkEvent::Release(ReleaseAfter);
4884         }
4885         return;
4886       }
4887     }
4888 
4889     ev->reset();
4890     ev->OnList = intptr_t(Lock);
4891     // The following fence() isn't _strictly necessary as the subsequent
4892     // CAS() both serializes execution and ratifies the fetched *Lock value.
4893     OrderAccess::fence();
4894     for (;;) {
4895       w = *Lock;
4896       if ((w & LOCKBIT) == 0) {
4897         if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4898           ev->OnList = 0;
4899           // We call ::Release while holding the outer lock, thus
4900           // artificially lengthening the critical section.
4901           // Consider deferring the ::Release() until the subsequent unlock(),
4902           // after we've dropped the outer lock.
4903           if (ReleaseAfter != NULL) {
4904             ParkEvent::Release(ReleaseAfter);
4905           }
4906           return;
4907         }
4908         continue;      // Interference -- *Lock changed -- Just retry
4909       }
4910       assert(w & LOCKBIT, "invariant");
4911       ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4912       if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4913     }
4914 
4915     while (ev->OnList != 0) {
4916       ev->park();
4917     }
4918   }
4919 }
4920 
4921 // Release() must extract a successor from the list and then wake that thread.
4922 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4923 // similar to that used by ParkEvent::Allocate() and ::Release().  DMR-based
4924 // Release() would :
4925 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4926 // (B) Extract a successor from the private list "in-hand"
4927 // (C) attempt to CAS() the residual back into *Lock over null.
4928 //     If there were any newly arrived threads and the CAS() would fail.
4929 //     In that case Release() would detach the RATs, re-merge the list in-hand
4930 //     with the RATs and repeat as needed.  Alternately, Release() might
4931 //     detach and extract a successor, but then pass the residual list to the wakee.
4932 //     The wakee would be responsible for reattaching and remerging before it
4933 //     competed for the lock.
4934 //
4935 // Both "pop" and DMR are immune from ABA corruption -- there can be
4936 // multiple concurrent pushers, but only one popper or detacher.
4937 // This implementation pops from the head of the list.  This is unfair,
4938 // but tends to provide excellent throughput as hot threads remain hot.
4939 // (We wake recently run threads first).
4940 //
4941 // All paths through muxRelease() will execute a CAS.
4942 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4943 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4944 // executed within the critical section are complete and globally visible before the
4945 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4946 void Thread::muxRelease(volatile intptr_t * Lock)  {
4947   for (;;) {
4948     const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT);
4949     assert(w & LOCKBIT, "invariant");
4950     if (w == LOCKBIT) return;
4951     ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4952     assert(List != NULL, "invariant");
4953     assert(List->OnList == intptr_t(Lock), "invariant");
4954     ParkEvent * const nxt = List->ListNext;
4955     guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4956 
4957     // The following CAS() releases the lock and pops the head element.
4958     // The CAS() also ratifies the previously fetched lock-word value.
4959     if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) {
4960       continue;
4961     }
4962     List->OnList = 0;
4963     OrderAccess::fence();
4964     List->unpark();
4965     return;
4966   }
4967 }
4968 
4969 
4970 void Threads::verify() {
4971   ALL_JAVA_THREADS(p) {
4972     p->verify();
4973   }
4974   VMThread* thread = VMThread::vm_thread();
4975   if (thread != NULL) thread->verify();
4976 }