1 /*
   2  * Copyright (c) 1997, 2015, 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 "classfile/classLoader.hpp"
  27 #include "classfile/javaClasses.hpp"
  28 #include "classfile/systemDictionary.hpp"
  29 #include "classfile/vmSymbols.hpp"
  30 #include "code/codeCache.hpp"
  31 #include "code/scopeDesc.hpp"
  32 #include "compiler/compileBroker.hpp"
  33 #include "interpreter/interpreter.hpp"
  34 #include "interpreter/linkResolver.hpp"
  35 #include "interpreter/oopMapCache.hpp"
  36 #include "jvmtifiles/jvmtiEnv.hpp"
  37 #include "memory/gcLocker.inline.hpp"
  38 #include "memory/metaspaceShared.hpp"
  39 #include "memory/oopFactory.hpp"
  40 #include "memory/universe.inline.hpp"
  41 #include "oops/instanceKlass.hpp"
  42 #include "oops/objArrayOop.hpp"
  43 #include "oops/oop.inline.hpp"
  44 #include "oops/symbol.hpp"
  45 #include "oops/verifyOop.hpp"
  46 #include "prims/jvm_misc.hpp"
  47 #include "prims/jvmtiExport.hpp"
  48 #include "prims/jvmtiThreadState.hpp"
  49 #include "prims/privilegedStack.hpp"
  50 #include "runtime/arguments.hpp"
  51 #include "runtime/atomic.inline.hpp"
  52 #include "runtime/biasedLocking.hpp"
  53 #include "runtime/deoptimization.hpp"
  54 #include "runtime/fprofiler.hpp"
  55 #include "runtime/frame.inline.hpp"
  56 #include "runtime/init.hpp"
  57 #include "runtime/interfaceSupport.hpp"
  58 #include "runtime/java.hpp"
  59 #include "runtime/javaCalls.hpp"
  60 #include "runtime/jniPeriodicChecker.hpp"
  61 #include "runtime/memprofiler.hpp"
  62 #include "runtime/mutexLocker.hpp"
  63 #include "runtime/objectMonitor.hpp"
  64 #include "runtime/orderAccess.inline.hpp"
  65 #include "runtime/osThread.hpp"
  66 #include "runtime/safepoint.hpp"
  67 #include "runtime/sharedRuntime.hpp"
  68 #include "runtime/statSampler.hpp"
  69 #include "runtime/stubRoutines.hpp"
  70 #include "runtime/sweeper.hpp"
  71 #include "runtime/task.hpp"
  72 #include "runtime/thread.inline.hpp"
  73 #include "runtime/threadCritical.hpp"
  74 #include "runtime/threadLocalStorage.hpp"
  75 #include "runtime/vframe.hpp"
  76 #include "runtime/vframeArray.hpp"
  77 #include "runtime/vframe_hp.hpp"
  78 #include "runtime/vmThread.hpp"
  79 #include "runtime/vm_operations.hpp"
  80 #include "runtime/vm_version.hpp"
  81 #include "services/attachListener.hpp"
  82 #include "services/management.hpp"
  83 #include "services/memTracker.hpp"
  84 #include "services/threadService.hpp"
  85 #include "trace/tracing.hpp"
  86 #include "trace/traceMacros.hpp"
  87 #include "utilities/defaultStream.hpp"
  88 #include "utilities/dtrace.hpp"
  89 #include "utilities/events.hpp"
  90 #include "utilities/preserveException.hpp"
  91 #include "utilities/macros.hpp"
  92 #if INCLUDE_ALL_GCS
  93 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp"
  94 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
  95 #include "gc_implementation/parallelScavenge/pcTasks.hpp"
  96 #endif // INCLUDE_ALL_GCS
  97 #ifdef COMPILER1
  98 #include "c1/c1_Compiler.hpp"
  99 #endif
 100 #ifdef COMPILER2
 101 #include "opto/c2compiler.hpp"
 102 #include "opto/idealGraphPrinter.hpp"
 103 #endif
 104 #if INCLUDE_RTM_OPT
 105 #include "runtime/rtmLocking.hpp"
 106 #endif
 107 
 108 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
 109 
 110 #ifdef DTRACE_ENABLED
 111 
 112 // Only bother with this argument setup if dtrace is available
 113 
 114   #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
 115   #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
 116 
 117   #define DTRACE_THREAD_PROBE(probe, javathread)                           \
 118     {                                                                      \
 119       ResourceMark rm(this);                                               \
 120       int len = 0;                                                         \
 121       const char* name = (javathread)->get_thread_name();                  \
 122       len = strlen(name);                                                  \
 123       HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */               \
 124         (char *) name, len,                                                \
 125         java_lang_Thread::thread_id((javathread)->threadObj()),            \
 126         (uintptr_t) (javathread)->osthread()->thread_id(),                 \
 127         java_lang_Thread::is_daemon((javathread)->threadObj()));           \
 128     }
 129 
 130 #else //  ndef DTRACE_ENABLED
 131 
 132   #define DTRACE_THREAD_PROBE(probe, javathread)
 133 
 134 #endif // ndef DTRACE_ENABLED
 135 
 136 
 137 // Class hierarchy
 138 // - Thread
 139 //   - VMThread
 140 //   - WatcherThread
 141 //   - ConcurrentMarkSweepThread
 142 //   - JavaThread
 143 //     - CompilerThread
 144 
 145 // ======= Thread ========
 146 // Support for forcing alignment of thread objects for biased locking
 147 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
 148   if (UseBiasedLocking) {
 149     const int alignment = markOopDesc::biased_lock_alignment;
 150     size_t aligned_size = size + (alignment - sizeof(intptr_t));
 151     void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
 152                                           : AllocateHeap(aligned_size, flags, CURRENT_PC,
 153                                                          AllocFailStrategy::RETURN_NULL);
 154     void* aligned_addr     = (void*) align_size_up((intptr_t) real_malloc_addr, alignment);
 155     assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
 156            ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
 157            "JavaThread alignment code overflowed allocated storage");
 158     if (TraceBiasedLocking) {
 159       if (aligned_addr != real_malloc_addr) {
 160         tty->print_cr("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
 161                       real_malloc_addr, aligned_addr);
 162       }
 163     }
 164     ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
 165     return aligned_addr;
 166   } else {
 167     return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
 168                        : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
 169   }
 170 }
 171 
 172 void Thread::operator delete(void* p) {
 173   if (UseBiasedLocking) {
 174     void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;
 175     FreeHeap(real_malloc_addr);
 176   } else {
 177     FreeHeap(p);
 178   }
 179 }
 180 
 181 
 182 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
 183 // JavaThread
 184 
 185 
 186 Thread::Thread() {
 187   // stack and get_thread
 188   set_stack_base(NULL);
 189   set_stack_size(0);
 190   set_self_raw_id(0);
 191   set_lgrp_id(-1);
 192 
 193   // allocated data structures
 194   set_osthread(NULL);
 195   set_resource_area(new (mtThread)ResourceArea());
 196   DEBUG_ONLY(_current_resource_mark = NULL;)
 197   set_handle_area(new (mtThread) HandleArea(NULL));
 198   set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
 199   set_active_handles(NULL);
 200   set_free_handle_block(NULL);
 201   set_last_handle_mark(NULL);
 202 
 203   // This initial value ==> never claimed.
 204   _oops_do_parity = 0;
 205 
 206   _metadata_on_stack_buffer = NULL;
 207 
 208   // the handle mark links itself to last_handle_mark
 209   new HandleMark(this);
 210 
 211   // plain initialization
 212   debug_only(_owned_locks = NULL;)
 213   debug_only(_allow_allocation_count = 0;)
 214   NOT_PRODUCT(_allow_safepoint_count = 0;)
 215   NOT_PRODUCT(_skip_gcalot = false;)
 216   _jvmti_env_iteration_count = 0;
 217   set_allocated_bytes(0);
 218   _vm_operation_started_count = 0;
 219   _vm_operation_completed_count = 0;
 220   _current_pending_monitor = NULL;
 221   _current_pending_monitor_is_from_java = true;
 222   _current_waiting_monitor = NULL;
 223   _num_nested_signal = 0;
 224   omFreeList = NULL;
 225   omFreeCount = 0;
 226   omFreeProvision = 32;
 227   omInUseList = NULL;
 228   omInUseCount = 0;
 229 
 230 #ifdef ASSERT
 231   _visited_for_critical_count = false;
 232 #endif
 233 
 234   _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
 235                          Monitor::_safepoint_check_sometimes);
 236   _suspend_flags = 0;
 237 
 238   // thread-specific hashCode stream generator state - Marsaglia shift-xor form
 239   _hashStateX = os::random();
 240   _hashStateY = 842502087;
 241   _hashStateZ = 0x8767;    // (int)(3579807591LL & 0xffff) ;
 242   _hashStateW = 273326509;
 243 
 244   _OnTrap   = 0;
 245   _schedctl = NULL;
 246   _Stalled  = 0;
 247   _TypeTag  = 0x2BAD;
 248 
 249   // Many of the following fields are effectively final - immutable
 250   // Note that nascent threads can't use the Native Monitor-Mutex
 251   // construct until the _MutexEvent is initialized ...
 252   // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
 253   // we might instead use a stack of ParkEvents that we could provision on-demand.
 254   // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
 255   // and ::Release()
 256   _ParkEvent   = ParkEvent::Allocate(this);
 257   _SleepEvent  = ParkEvent::Allocate(this);
 258   _MutexEvent  = ParkEvent::Allocate(this);
 259   _MuxEvent    = ParkEvent::Allocate(this);
 260 
 261 #ifdef CHECK_UNHANDLED_OOPS
 262   if (CheckUnhandledOops) {
 263     _unhandled_oops = new UnhandledOops(this);
 264   }
 265 #endif // CHECK_UNHANDLED_OOPS
 266 #ifdef ASSERT
 267   if (UseBiasedLocking) {
 268     assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
 269     assert(this == _real_malloc_address ||
 270            this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment),
 271            "bug in forced alignment of thread objects");
 272   }
 273 #endif // ASSERT
 274 }
 275 
 276 void Thread::initialize_thread_local_storage() {
 277   // Note: Make sure this method only calls
 278   // non-blocking operations. Otherwise, it might not work
 279   // with the thread-startup/safepoint interaction.
 280 
 281   // During Java thread startup, safepoint code should allow this
 282   // method to complete because it may need to allocate memory to
 283   // store information for the new thread.
 284 
 285   // initialize structure dependent on thread local storage
 286   ThreadLocalStorage::set_thread(this);
 287 }
 288 
 289 void Thread::record_stack_base_and_size() {
 290   set_stack_base(os::current_stack_base());
 291   set_stack_size(os::current_stack_size());
 292   if (is_Java_thread()) {
 293     ((JavaThread*) this)->set_stack_overflow_limit();
 294   }
 295   // CR 7190089: on Solaris, primordial thread's stack is adjusted
 296   // in initialize_thread(). Without the adjustment, stack size is
 297   // incorrect if stack is set to unlimited (ulimit -s unlimited).
 298   // So far, only Solaris has real implementation of initialize_thread().
 299   //
 300   // set up any platform-specific state.
 301   os::initialize_thread(this);
 302 
 303 #if INCLUDE_NMT
 304   // record thread's native stack, stack grows downward
 305   address stack_low_addr = stack_base() - stack_size();
 306   MemTracker::record_thread_stack(stack_low_addr, stack_size());
 307 #endif // INCLUDE_NMT
 308 }
 309 
 310 
 311 Thread::~Thread() {
 312   // Reclaim the objectmonitors from the omFreeList of the moribund thread.
 313   ObjectSynchronizer::omFlush(this);
 314 
 315   EVENT_THREAD_DESTRUCT(this);
 316 
 317   // stack_base can be NULL if the thread is never started or exited before
 318   // record_stack_base_and_size called. Although, we would like to ensure
 319   // that all started threads do call record_stack_base_and_size(), there is
 320   // not proper way to enforce that.
 321 #if INCLUDE_NMT
 322   if (_stack_base != NULL) {
 323     address low_stack_addr = stack_base() - stack_size();
 324     MemTracker::release_thread_stack(low_stack_addr, stack_size());
 325 #ifdef ASSERT
 326     set_stack_base(NULL);
 327 #endif
 328   }
 329 #endif // INCLUDE_NMT
 330 
 331   // deallocate data structures
 332   delete resource_area();
 333   // since the handle marks are using the handle area, we have to deallocated the root
 334   // handle mark before deallocating the thread's handle area,
 335   assert(last_handle_mark() != NULL, "check we have an element");
 336   delete last_handle_mark();
 337   assert(last_handle_mark() == NULL, "check we have reached the end");
 338 
 339   // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
 340   // We NULL out the fields for good hygiene.
 341   ParkEvent::Release(_ParkEvent); _ParkEvent   = NULL;
 342   ParkEvent::Release(_SleepEvent); _SleepEvent  = NULL;
 343   ParkEvent::Release(_MutexEvent); _MutexEvent  = NULL;
 344   ParkEvent::Release(_MuxEvent); _MuxEvent    = NULL;
 345 
 346   delete handle_area();
 347   delete metadata_handles();
 348 
 349   // osthread() can be NULL, if creation of thread failed.
 350   if (osthread() != NULL) os::free_thread(osthread());
 351 
 352   delete _SR_lock;
 353 
 354   // clear thread local storage if the Thread is deleting itself
 355   if (this == Thread::current()) {
 356     ThreadLocalStorage::set_thread(NULL);
 357   } else {
 358     // In the case where we're not the current thread, invalidate all the
 359     // caches in case some code tries to get the current thread or the
 360     // thread that was destroyed, and gets stale information.
 361     ThreadLocalStorage::invalidate_all();
 362   }
 363   CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
 364 }
 365 
 366 // NOTE: dummy function for assertion purpose.
 367 void Thread::run() {
 368   ShouldNotReachHere();
 369 }
 370 
 371 #ifdef ASSERT
 372 // Private method to check for dangling thread pointer
 373 void check_for_dangling_thread_pointer(Thread *thread) {
 374   assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
 375          "possibility of dangling Thread pointer");
 376 }
 377 #endif
 378 
 379 ThreadPriority Thread::get_priority(const Thread* const thread) {
 380   ThreadPriority priority;
 381   // Can return an error!
 382   (void)os::get_priority(thread, priority);
 383   assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
 384   return priority;
 385 }
 386 
 387 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
 388   debug_only(check_for_dangling_thread_pointer(thread);)
 389   // Can return an error!
 390   (void)os::set_priority(thread, priority);
 391 }
 392 
 393 
 394 void Thread::start(Thread* thread) {
 395   // Start is different from resume in that its safety is guaranteed by context or
 396   // being called from a Java method synchronized on the Thread object.
 397   if (!DisableStartThread) {
 398     if (thread->is_Java_thread()) {
 399       // Initialize the thread state to RUNNABLE before starting this thread.
 400       // Can not set it after the thread started because we do not know the
 401       // exact thread state at that time. It could be in MONITOR_WAIT or
 402       // in SLEEPING or some other state.
 403       java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
 404                                           java_lang_Thread::RUNNABLE);
 405     }
 406     os::start_thread(thread);
 407   }
 408 }
 409 
 410 // Enqueue a VM_Operation to do the job for us - sometime later
 411 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
 412   VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
 413   VMThread::execute(vm_stop);
 414 }
 415 
 416 
 417 // Check if an external suspend request has completed (or has been
 418 // cancelled). Returns true if the thread is externally suspended and
 419 // false otherwise.
 420 //
 421 // The bits parameter returns information about the code path through
 422 // the routine. Useful for debugging:
 423 //
 424 // set in is_ext_suspend_completed():
 425 // 0x00000001 - routine was entered
 426 // 0x00000010 - routine return false at end
 427 // 0x00000100 - thread exited (return false)
 428 // 0x00000200 - suspend request cancelled (return false)
 429 // 0x00000400 - thread suspended (return true)
 430 // 0x00001000 - thread is in a suspend equivalent state (return true)
 431 // 0x00002000 - thread is native and walkable (return true)
 432 // 0x00004000 - thread is native_trans and walkable (needed retry)
 433 //
 434 // set in wait_for_ext_suspend_completion():
 435 // 0x00010000 - routine was entered
 436 // 0x00020000 - suspend request cancelled before loop (return false)
 437 // 0x00040000 - thread suspended before loop (return true)
 438 // 0x00080000 - suspend request cancelled in loop (return false)
 439 // 0x00100000 - thread suspended in loop (return true)
 440 // 0x00200000 - suspend not completed during retry loop (return false)
 441 
 442 // Helper class for tracing suspend wait debug bits.
 443 //
 444 // 0x00000100 indicates that the target thread exited before it could
 445 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
 446 // 0x00080000 each indicate a cancelled suspend request so they don't
 447 // count as wait failures either.
 448 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
 449 
 450 class TraceSuspendDebugBits : public StackObj {
 451  private:
 452   JavaThread * jt;
 453   bool         is_wait;
 454   bool         called_by_wait;  // meaningful when !is_wait
 455   uint32_t *   bits;
 456 
 457  public:
 458   TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
 459                         uint32_t *_bits) {
 460     jt             = _jt;
 461     is_wait        = _is_wait;
 462     called_by_wait = _called_by_wait;
 463     bits           = _bits;
 464   }
 465 
 466   ~TraceSuspendDebugBits() {
 467     if (!is_wait) {
 468 #if 1
 469       // By default, don't trace bits for is_ext_suspend_completed() calls.
 470       // That trace is very chatty.
 471       return;
 472 #else
 473       if (!called_by_wait) {
 474         // If tracing for is_ext_suspend_completed() is enabled, then only
 475         // trace calls to it from wait_for_ext_suspend_completion()
 476         return;
 477       }
 478 #endif
 479     }
 480 
 481     if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
 482       if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
 483         MutexLocker ml(Threads_lock);  // needed for get_thread_name()
 484         ResourceMark rm;
 485 
 486         tty->print_cr(
 487                       "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
 488                       jt->get_thread_name(), *bits);
 489 
 490         guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
 491       }
 492     }
 493   }
 494 };
 495 #undef DEBUG_FALSE_BITS
 496 
 497 
 498 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
 499                                           uint32_t *bits) {
 500   TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
 501 
 502   bool did_trans_retry = false;  // only do thread_in_native_trans retry once
 503   bool do_trans_retry;           // flag to force the retry
 504 
 505   *bits |= 0x00000001;
 506 
 507   do {
 508     do_trans_retry = false;
 509 
 510     if (is_exiting()) {
 511       // Thread is in the process of exiting. This is always checked
 512       // first to reduce the risk of dereferencing a freed JavaThread.
 513       *bits |= 0x00000100;
 514       return false;
 515     }
 516 
 517     if (!is_external_suspend()) {
 518       // Suspend request is cancelled. This is always checked before
 519       // is_ext_suspended() to reduce the risk of a rogue resume
 520       // confusing the thread that made the suspend request.
 521       *bits |= 0x00000200;
 522       return false;
 523     }
 524 
 525     if (is_ext_suspended()) {
 526       // thread is suspended
 527       *bits |= 0x00000400;
 528       return true;
 529     }
 530 
 531     // Now that we no longer do hard suspends of threads running
 532     // native code, the target thread can be changing thread state
 533     // while we are in this routine:
 534     //
 535     //   _thread_in_native -> _thread_in_native_trans -> _thread_blocked
 536     //
 537     // We save a copy of the thread state as observed at this moment
 538     // and make our decision about suspend completeness based on the
 539     // copy. This closes the race where the thread state is seen as
 540     // _thread_in_native_trans in the if-thread_blocked check, but is
 541     // seen as _thread_blocked in if-thread_in_native_trans check.
 542     JavaThreadState save_state = thread_state();
 543 
 544     if (save_state == _thread_blocked && is_suspend_equivalent()) {
 545       // If the thread's state is _thread_blocked and this blocking
 546       // condition is known to be equivalent to a suspend, then we can
 547       // consider the thread to be externally suspended. This means that
 548       // the code that sets _thread_blocked has been modified to do
 549       // self-suspension if the blocking condition releases. We also
 550       // used to check for CONDVAR_WAIT here, but that is now covered by
 551       // the _thread_blocked with self-suspension check.
 552       //
 553       // Return true since we wouldn't be here unless there was still an
 554       // external suspend request.
 555       *bits |= 0x00001000;
 556       return true;
 557     } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
 558       // Threads running native code will self-suspend on native==>VM/Java
 559       // transitions. If its stack is walkable (should always be the case
 560       // unless this function is called before the actual java_suspend()
 561       // call), then the wait is done.
 562       *bits |= 0x00002000;
 563       return true;
 564     } else if (!called_by_wait && !did_trans_retry &&
 565                save_state == _thread_in_native_trans &&
 566                frame_anchor()->walkable()) {
 567       // The thread is transitioning from thread_in_native to another
 568       // thread state. check_safepoint_and_suspend_for_native_trans()
 569       // will force the thread to self-suspend. If it hasn't gotten
 570       // there yet we may have caught the thread in-between the native
 571       // code check above and the self-suspend. Lucky us. If we were
 572       // called by wait_for_ext_suspend_completion(), then it
 573       // will be doing the retries so we don't have to.
 574       //
 575       // Since we use the saved thread state in the if-statement above,
 576       // there is a chance that the thread has already transitioned to
 577       // _thread_blocked by the time we get here. In that case, we will
 578       // make a single unnecessary pass through the logic below. This
 579       // doesn't hurt anything since we still do the trans retry.
 580 
 581       *bits |= 0x00004000;
 582 
 583       // Once the thread leaves thread_in_native_trans for another
 584       // thread state, we break out of this retry loop. We shouldn't
 585       // need this flag to prevent us from getting back here, but
 586       // sometimes paranoia is good.
 587       did_trans_retry = true;
 588 
 589       // We wait for the thread to transition to a more usable state.
 590       for (int i = 1; i <= SuspendRetryCount; i++) {
 591         // We used to do an "os::yield_all(i)" call here with the intention
 592         // that yielding would increase on each retry. However, the parameter
 593         // is ignored on Linux which means the yield didn't scale up. Waiting
 594         // on the SR_lock below provides a much more predictable scale up for
 595         // the delay. It also provides a simple/direct point to check for any
 596         // safepoint requests from the VMThread
 597 
 598         // temporarily drops SR_lock while doing wait with safepoint check
 599         // (if we're a JavaThread - the WatcherThread can also call this)
 600         // and increase delay with each retry
 601         SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 602 
 603         // check the actual thread state instead of what we saved above
 604         if (thread_state() != _thread_in_native_trans) {
 605           // the thread has transitioned to another thread state so
 606           // try all the checks (except this one) one more time.
 607           do_trans_retry = true;
 608           break;
 609         }
 610       } // end retry loop
 611 
 612 
 613     }
 614   } while (do_trans_retry);
 615 
 616   *bits |= 0x00000010;
 617   return false;
 618 }
 619 
 620 // Wait for an external suspend request to complete (or be cancelled).
 621 // Returns true if the thread is externally suspended and false otherwise.
 622 //
 623 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
 624                                                  uint32_t *bits) {
 625   TraceSuspendDebugBits tsdb(this, true /* is_wait */,
 626                              false /* !called_by_wait */, bits);
 627 
 628   // local flag copies to minimize SR_lock hold time
 629   bool is_suspended;
 630   bool pending;
 631   uint32_t reset_bits;
 632 
 633   // set a marker so is_ext_suspend_completed() knows we are the caller
 634   *bits |= 0x00010000;
 635 
 636   // We use reset_bits to reinitialize the bits value at the top of
 637   // each retry loop. This allows the caller to make use of any
 638   // unused bits for their own marking purposes.
 639   reset_bits = *bits;
 640 
 641   {
 642     MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
 643     is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 644                                             delay, bits);
 645     pending = is_external_suspend();
 646   }
 647   // must release SR_lock to allow suspension to complete
 648 
 649   if (!pending) {
 650     // A cancelled suspend request is the only false return from
 651     // is_ext_suspend_completed() that keeps us from entering the
 652     // retry loop.
 653     *bits |= 0x00020000;
 654     return false;
 655   }
 656 
 657   if (is_suspended) {
 658     *bits |= 0x00040000;
 659     return true;
 660   }
 661 
 662   for (int i = 1; i <= retries; i++) {
 663     *bits = reset_bits;  // reinit to only track last retry
 664 
 665     // We used to do an "os::yield_all(i)" call here with the intention
 666     // that yielding would increase on each retry. However, the parameter
 667     // is ignored on Linux which means the yield didn't scale up. Waiting
 668     // on the SR_lock below provides a much more predictable scale up for
 669     // the delay. It also provides a simple/direct point to check for any
 670     // safepoint requests from the VMThread
 671 
 672     {
 673       MutexLocker ml(SR_lock());
 674       // wait with safepoint check (if we're a JavaThread - the WatcherThread
 675       // can also call this)  and increase delay with each retry
 676       SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 677 
 678       is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 679                                               delay, bits);
 680 
 681       // It is possible for the external suspend request to be cancelled
 682       // (by a resume) before the actual suspend operation is completed.
 683       // Refresh our local copy to see if we still need to wait.
 684       pending = is_external_suspend();
 685     }
 686 
 687     if (!pending) {
 688       // A cancelled suspend request is the only false return from
 689       // is_ext_suspend_completed() that keeps us from staying in the
 690       // retry loop.
 691       *bits |= 0x00080000;
 692       return false;
 693     }
 694 
 695     if (is_suspended) {
 696       *bits |= 0x00100000;
 697       return true;
 698     }
 699   } // end retry loop
 700 
 701   // thread did not suspend after all our retries
 702   *bits |= 0x00200000;
 703   return false;
 704 }
 705 
 706 #ifndef PRODUCT
 707 void JavaThread::record_jump(address target, address instr, const char* file,
 708                              int line) {
 709 
 710   // This should not need to be atomic as the only way for simultaneous
 711   // updates is via interrupts. Even then this should be rare or non-existent
 712   // and we don't care that much anyway.
 713 
 714   int index = _jmp_ring_index;
 715   _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
 716   _jmp_ring[index]._target = (intptr_t) target;
 717   _jmp_ring[index]._instruction = (intptr_t) instr;
 718   _jmp_ring[index]._file = file;
 719   _jmp_ring[index]._line = line;
 720 }
 721 #endif // PRODUCT
 722 
 723 // Called by flat profiler
 724 // Callers have already called wait_for_ext_suspend_completion
 725 // The assertion for that is currently too complex to put here:
 726 bool JavaThread::profile_last_Java_frame(frame* _fr) {
 727   bool gotframe = false;
 728   // self suspension saves needed state.
 729   if (has_last_Java_frame() && _anchor.walkable()) {
 730     *_fr = pd_last_frame();
 731     gotframe = true;
 732   }
 733   return gotframe;
 734 }
 735 
 736 void Thread::interrupt(Thread* thread) {
 737   debug_only(check_for_dangling_thread_pointer(thread);)
 738   os::interrupt(thread);
 739 }
 740 
 741 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
 742   debug_only(check_for_dangling_thread_pointer(thread);)
 743   // Note:  If clear_interrupted==false, this simply fetches and
 744   // returns the value of the field osthread()->interrupted().
 745   return os::is_interrupted(thread, clear_interrupted);
 746 }
 747 
 748 
 749 // GC Support
 750 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
 751   jint thread_parity = _oops_do_parity;
 752   if (thread_parity != strong_roots_parity) {
 753     jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
 754     if (res == thread_parity) {
 755       return true;
 756     } else {
 757       guarantee(res == strong_roots_parity, "Or else what?");
 758       assert(SharedHeap::heap()->workers()->active_workers() > 0,
 759              "Should only fail when parallel.");
 760       return false;
 761     }
 762   }
 763   assert(SharedHeap::heap()->workers()->active_workers() > 0,
 764          "Should only fail when parallel.");
 765   return false;
 766 }
 767 
 768 void Thread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
 769   active_handles()->oops_do(f);
 770   // Do oop for ThreadShadow
 771   f->do_oop((oop*)&_pending_exception);
 772   handle_area()->oops_do(f);
 773 }
 774 
 775 void Thread::nmethods_do(CodeBlobClosure* cf) {
 776   // no nmethods in a generic thread...
 777 }
 778 
 779 void Thread::metadata_do(void f(Metadata*)) {
 780   if (metadata_handles() != NULL) {
 781     for (int i = 0; i< metadata_handles()->length(); i++) {
 782       f(metadata_handles()->at(i));
 783     }
 784   }
 785 }
 786 
 787 void Thread::print_on(outputStream* st) const {
 788   // get_priority assumes osthread initialized
 789   if (osthread() != NULL) {
 790     int os_prio;
 791     if (os::get_native_priority(this, &os_prio) == OS_OK) {
 792       st->print("os_prio=%d ", os_prio);
 793     }
 794     st->print("tid=" INTPTR_FORMAT " ", this);
 795     ext().print_on(st);
 796     osthread()->print_on(st);
 797   }
 798   debug_only(if (WizardMode) print_owned_locks_on(st);)
 799 }
 800 
 801 // Thread::print_on_error() is called by fatal error handler. Don't use
 802 // any lock or allocate memory.
 803 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
 804   if (is_VM_thread())                 st->print("VMThread");
 805   else if (is_Compiler_thread())      st->print("CompilerThread");
 806   else if (is_Java_thread())          st->print("JavaThread");
 807   else if (is_GC_task_thread())       st->print("GCTaskThread");
 808   else if (is_Watcher_thread())       st->print("WatcherThread");
 809   else if (is_ConcurrentGC_thread())  st->print("ConcurrentGCThread");
 810   else                                st->print("Thread");
 811 
 812   st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
 813             _stack_base - _stack_size, _stack_base);
 814 
 815   if (osthread()) {
 816     st->print(" [id=%d]", osthread()->thread_id());
 817   }
 818 }
 819 
 820 #ifdef ASSERT
 821 void Thread::print_owned_locks_on(outputStream* st) const {
 822   Monitor *cur = _owned_locks;
 823   if (cur == NULL) {
 824     st->print(" (no locks) ");
 825   } else {
 826     st->print_cr(" Locks owned:");
 827     while (cur) {
 828       cur->print_on(st);
 829       cur = cur->next();
 830     }
 831   }
 832 }
 833 
 834 static int ref_use_count  = 0;
 835 
 836 bool Thread::owns_locks_but_compiled_lock() const {
 837   for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 838     if (cur != Compile_lock) return true;
 839   }
 840   return false;
 841 }
 842 
 843 
 844 #endif
 845 
 846 #ifndef PRODUCT
 847 
 848 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
 849 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
 850 // no threads which allow_vm_block's are held
 851 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
 852   // Check if current thread is allowed to block at a safepoint
 853   if (!(_allow_safepoint_count == 0)) {
 854     fatal("Possible safepoint reached by thread that does not allow it");
 855   }
 856   if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
 857     fatal("LEAF method calling lock?");
 858   }
 859 
 860 #ifdef ASSERT
 861   if (potential_vm_operation && is_Java_thread()
 862       && !Universe::is_bootstrapping()) {
 863     // Make sure we do not hold any locks that the VM thread also uses.
 864     // This could potentially lead to deadlocks
 865     for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 866       // Threads_lock is special, since the safepoint synchronization will not start before this is
 867       // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
 868       // since it is used to transfer control between JavaThreads and the VMThread
 869       // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
 870       if ((cur->allow_vm_block() &&
 871            cur != Threads_lock &&
 872            cur != Compile_lock &&               // Temporary: should not be necessary when we get separate compilation
 873            cur != VMOperationRequest_lock &&
 874            cur != VMOperationQueue_lock) ||
 875            cur->rank() == Mutex::special) {
 876         fatal(err_msg("Thread holding lock at safepoint that vm can block on: %s", cur->name()));
 877       }
 878     }
 879   }
 880 
 881   if (GCALotAtAllSafepoints) {
 882     // We could enter a safepoint here and thus have a gc
 883     InterfaceSupport::check_gc_alot();
 884   }
 885 #endif
 886 }
 887 #endif
 888 
 889 bool Thread::is_in_stack(address adr) const {
 890   assert(Thread::current() == this, "is_in_stack can only be called from current thread");
 891   address end = os::current_stack_pointer();
 892   // Allow non Java threads to call this without stack_base
 893   if (_stack_base == NULL) return true;
 894   if (stack_base() >= adr && adr >= end) return true;
 895 
 896   return false;
 897 }
 898 
 899 
 900 bool Thread::is_in_usable_stack(address adr) const {
 901   size_t stack_guard_size = os::uses_stack_guard_pages() ? (StackYellowPages + StackRedPages) * os::vm_page_size() : 0;
 902   size_t usable_stack_size = _stack_size - stack_guard_size;
 903 
 904   return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
 905 }
 906 
 907 
 908 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
 909 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
 910 // used for compilation in the future. If that change is made, the need for these methods
 911 // should be revisited, and they should be removed if possible.
 912 
 913 bool Thread::is_lock_owned(address adr) const {
 914   return on_local_stack(adr);
 915 }
 916 
 917 bool Thread::set_as_starting_thread() {
 918   // NOTE: this must be called inside the main thread.
 919   return os::create_main_thread((JavaThread*)this);
 920 }
 921 
 922 static void initialize_class(Symbol* class_name, TRAPS) {
 923   Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
 924   InstanceKlass::cast(klass)->initialize(CHECK);
 925 }
 926 
 927 
 928 // Creates the initial ThreadGroup
 929 static Handle create_initial_thread_group(TRAPS) {
 930   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
 931   instanceKlassHandle klass (THREAD, k);
 932 
 933   Handle system_instance = klass->allocate_instance_handle(CHECK_NH);
 934   {
 935     JavaValue result(T_VOID);
 936     JavaCalls::call_special(&result,
 937                             system_instance,
 938                             klass,
 939                             vmSymbols::object_initializer_name(),
 940                             vmSymbols::void_method_signature(),
 941                             CHECK_NH);
 942   }
 943   Universe::set_system_thread_group(system_instance());
 944 
 945   Handle main_instance = klass->allocate_instance_handle(CHECK_NH);
 946   {
 947     JavaValue result(T_VOID);
 948     Handle string = java_lang_String::create_from_str("main", CHECK_NH);
 949     JavaCalls::call_special(&result,
 950                             main_instance,
 951                             klass,
 952                             vmSymbols::object_initializer_name(),
 953                             vmSymbols::threadgroup_string_void_signature(),
 954                             system_instance,
 955                             string,
 956                             CHECK_NH);
 957   }
 958   return main_instance;
 959 }
 960 
 961 // Creates the initial Thread
 962 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
 963                                  TRAPS) {
 964   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
 965   instanceKlassHandle klass (THREAD, k);
 966   instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);
 967 
 968   java_lang_Thread::set_thread(thread_oop(), thread);
 969   java_lang_Thread::set_priority(thread_oop(), NormPriority);
 970   thread->set_threadObj(thread_oop());
 971 
 972   Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
 973 
 974   JavaValue result(T_VOID);
 975   JavaCalls::call_special(&result, thread_oop,
 976                           klass,
 977                           vmSymbols::object_initializer_name(),
 978                           vmSymbols::threadgroup_string_void_signature(),
 979                           thread_group,
 980                           string,
 981                           CHECK_NULL);
 982   return thread_oop();
 983 }
 984 
 985 static void call_initializeSystemClass(TRAPS) {
 986   Klass* k =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
 987   instanceKlassHandle klass (THREAD, k);
 988 
 989   JavaValue result(T_VOID);
 990   JavaCalls::call_static(&result, klass, vmSymbols::initializeSystemClass_name(),
 991                          vmSymbols::void_method_signature(), CHECK);
 992 }
 993 
 994 char java_runtime_name[128] = "";
 995 char java_runtime_version[128] = "";
 996 
 997 // extract the JRE name from sun.misc.Version.java_runtime_name
 998 static const char* get_java_runtime_name(TRAPS) {
 999   Klass* k = SystemDictionary::find(vmSymbols::sun_misc_Version(),
1000                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1001   fieldDescriptor fd;
1002   bool found = k != NULL &&
1003                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1004                                                         vmSymbols::string_signature(), &fd);
1005   if (found) {
1006     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1007     if (name_oop == NULL) {
1008       return NULL;
1009     }
1010     const char* name = java_lang_String::as_utf8_string(name_oop,
1011                                                         java_runtime_name,
1012                                                         sizeof(java_runtime_name));
1013     return name;
1014   } else {
1015     return NULL;
1016   }
1017 }
1018 
1019 // extract the JRE version from sun.misc.Version.java_runtime_version
1020 static const char* get_java_runtime_version(TRAPS) {
1021   Klass* k = SystemDictionary::find(vmSymbols::sun_misc_Version(),
1022                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1023   fieldDescriptor fd;
1024   bool found = k != NULL &&
1025                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1026                                                         vmSymbols::string_signature(), &fd);
1027   if (found) {
1028     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1029     if (name_oop == NULL) {
1030       return NULL;
1031     }
1032     const char* name = java_lang_String::as_utf8_string(name_oop,
1033                                                         java_runtime_version,
1034                                                         sizeof(java_runtime_version));
1035     return name;
1036   } else {
1037     return NULL;
1038   }
1039 }
1040 
1041 // General purpose hook into Java code, run once when the VM is initialized.
1042 // The Java library method itself may be changed independently from the VM.
1043 static void call_postVMInitHook(TRAPS) {
1044   Klass* k = SystemDictionary::resolve_or_null(vmSymbols::sun_misc_PostVMInitHook(), THREAD);
1045   instanceKlassHandle klass (THREAD, k);
1046   if (klass.not_null()) {
1047     JavaValue result(T_VOID);
1048     JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1049                            vmSymbols::void_method_signature(),
1050                            CHECK);
1051   }
1052 }
1053 
1054 static void reset_vm_info_property(TRAPS) {
1055   // the vm info string
1056   ResourceMark rm(THREAD);
1057   const char *vm_info = VM_Version::vm_info_string();
1058 
1059   // java.lang.System class
1060   Klass* k =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1061   instanceKlassHandle klass (THREAD, k);
1062 
1063   // setProperty arguments
1064   Handle key_str    = java_lang_String::create_from_str("java.vm.info", CHECK);
1065   Handle value_str  = java_lang_String::create_from_str(vm_info, CHECK);
1066 
1067   // return value
1068   JavaValue r(T_OBJECT);
1069 
1070   // public static String setProperty(String key, String value);
1071   JavaCalls::call_static(&r,
1072                          klass,
1073                          vmSymbols::setProperty_name(),
1074                          vmSymbols::string_string_string_signature(),
1075                          key_str,
1076                          value_str,
1077                          CHECK);
1078 }
1079 
1080 
1081 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1082                                     bool daemon, TRAPS) {
1083   assert(thread_group.not_null(), "thread group should be specified");
1084   assert(threadObj() == NULL, "should only create Java thread object once");
1085 
1086   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1087   instanceKlassHandle klass (THREAD, k);
1088   instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
1089 
1090   java_lang_Thread::set_thread(thread_oop(), this);
1091   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1092   set_threadObj(thread_oop());
1093 
1094   JavaValue result(T_VOID);
1095   if (thread_name != NULL) {
1096     Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1097     // Thread gets assigned specified name and null target
1098     JavaCalls::call_special(&result,
1099                             thread_oop,
1100                             klass,
1101                             vmSymbols::object_initializer_name(),
1102                             vmSymbols::threadgroup_string_void_signature(),
1103                             thread_group, // Argument 1
1104                             name,         // Argument 2
1105                             THREAD);
1106   } else {
1107     // Thread gets assigned name "Thread-nnn" and null target
1108     // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1109     JavaCalls::call_special(&result,
1110                             thread_oop,
1111                             klass,
1112                             vmSymbols::object_initializer_name(),
1113                             vmSymbols::threadgroup_runnable_void_signature(),
1114                             thread_group, // Argument 1
1115                             Handle(),     // Argument 2
1116                             THREAD);
1117   }
1118 
1119 
1120   if (daemon) {
1121     java_lang_Thread::set_daemon(thread_oop());
1122   }
1123 
1124   if (HAS_PENDING_EXCEPTION) {
1125     return;
1126   }
1127 
1128   KlassHandle group(THREAD, SystemDictionary::ThreadGroup_klass());
1129   Handle threadObj(THREAD, this->threadObj());
1130 
1131   JavaCalls::call_special(&result,
1132                           thread_group,
1133                           group,
1134                           vmSymbols::add_method_name(),
1135                           vmSymbols::thread_void_signature(),
1136                           threadObj,          // Arg 1
1137                           THREAD);
1138 }
1139 
1140 // NamedThread --  non-JavaThread subclasses with multiple
1141 // uniquely named instances should derive from this.
1142 NamedThread::NamedThread() : Thread() {
1143   _name = NULL;
1144   _processed_thread = NULL;
1145 }
1146 
1147 NamedThread::~NamedThread() {
1148   if (_name != NULL) {
1149     FREE_C_HEAP_ARRAY(char, _name);
1150     _name = NULL;
1151   }
1152 }
1153 
1154 void NamedThread::set_name(const char* format, ...) {
1155   guarantee(_name == NULL, "Only get to set name once.");
1156   _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1157   guarantee(_name != NULL, "alloc failure");
1158   va_list ap;
1159   va_start(ap, format);
1160   jio_vsnprintf(_name, max_name_len, format, ap);
1161   va_end(ap);
1162 }
1163 
1164 void NamedThread::print_on(outputStream* st) const {
1165   st->print("\"%s\" ", name());
1166   Thread::print_on(st);
1167   st->cr();
1168 }
1169 
1170 
1171 // ======= WatcherThread ========
1172 
1173 // The watcher thread exists to simulate timer interrupts.  It should
1174 // be replaced by an abstraction over whatever native support for
1175 // timer interrupts exists on the platform.
1176 
1177 WatcherThread* WatcherThread::_watcher_thread   = NULL;
1178 bool WatcherThread::_startable = false;
1179 volatile bool  WatcherThread::_should_terminate = false;
1180 
1181 WatcherThread::WatcherThread() : Thread(), _crash_protection(NULL) {
1182   assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1183   if (os::create_thread(this, os::watcher_thread)) {
1184     _watcher_thread = this;
1185 
1186     // Set the watcher thread to the highest OS priority which should not be
1187     // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1188     // is created. The only normal thread using this priority is the reference
1189     // handler thread, which runs for very short intervals only.
1190     // If the VMThread's priority is not lower than the WatcherThread profiling
1191     // will be inaccurate.
1192     os::set_priority(this, MaxPriority);
1193     if (!DisableStartThread) {
1194       os::start_thread(this);
1195     }
1196   }
1197 }
1198 
1199 int WatcherThread::sleep() const {
1200   MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1201 
1202   // remaining will be zero if there are no tasks,
1203   // causing the WatcherThread to sleep until a task is
1204   // enrolled
1205   int remaining = PeriodicTask::time_to_wait();
1206   int time_slept = 0;
1207 
1208   // we expect this to timeout - we only ever get unparked when
1209   // we should terminate or when a new task has been enrolled
1210   OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1211 
1212   jlong time_before_loop = os::javaTimeNanos();
1213 
1214   for (;;) {
1215     bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag, remaining);
1216     jlong now = os::javaTimeNanos();
1217 
1218     if (remaining == 0) {
1219       // if we didn't have any tasks we could have waited for a long time
1220       // consider the time_slept zero and reset time_before_loop
1221       time_slept = 0;
1222       time_before_loop = now;
1223     } else {
1224       // need to recalculate since we might have new tasks in _tasks
1225       time_slept = (int) ((now - time_before_loop) / 1000000);
1226     }
1227 
1228     // Change to task list or spurious wakeup of some kind
1229     if (timedout || _should_terminate) {
1230       break;
1231     }
1232 
1233     remaining = PeriodicTask::time_to_wait();
1234     if (remaining == 0) {
1235       // Last task was just disenrolled so loop around and wait until
1236       // another task gets enrolled
1237       continue;
1238     }
1239 
1240     remaining -= time_slept;
1241     if (remaining <= 0) {
1242       break;
1243     }
1244   }
1245 
1246   return time_slept;
1247 }
1248 
1249 void WatcherThread::run() {
1250   assert(this == watcher_thread(), "just checking");
1251 
1252   this->record_stack_base_and_size();
1253   this->initialize_thread_local_storage();
1254   this->set_native_thread_name(this->name());
1255   this->set_active_handles(JNIHandleBlock::allocate_block());
1256   while (!_should_terminate) {
1257     assert(watcher_thread() == Thread::current(), "thread consistency check");
1258     assert(watcher_thread() == this, "thread consistency check");
1259 
1260     // Calculate how long it'll be until the next PeriodicTask work
1261     // should be done, and sleep that amount of time.
1262     int time_waited = sleep();
1263 
1264     if (is_error_reported()) {
1265       // A fatal error has happened, the error handler(VMError::report_and_die)
1266       // should abort JVM after creating an error log file. However in some
1267       // rare cases, the error handler itself might deadlock. Here we try to
1268       // kill JVM if the fatal error handler fails to abort in 2 minutes.
1269       //
1270       // This code is in WatcherThread because WatcherThread wakes up
1271       // periodically so the fatal error handler doesn't need to do anything;
1272       // also because the WatcherThread is less likely to crash than other
1273       // threads.
1274 
1275       for (;;) {
1276         if (!ShowMessageBoxOnError
1277             && (OnError == NULL || OnError[0] == '\0')
1278             && Arguments::abort_hook() == NULL) {
1279           os::sleep(this, 2 * 60 * 1000, false);
1280           fdStream err(defaultStream::output_fd());
1281           err.print_raw_cr("# [ timer expired, abort... ]");
1282           // skip atexit/vm_exit/vm_abort hooks
1283           os::die();
1284         }
1285 
1286         // Wake up 5 seconds later, the fatal handler may reset OnError or
1287         // ShowMessageBoxOnError when it is ready to abort.
1288         os::sleep(this, 5 * 1000, false);
1289       }
1290     }
1291 
1292     PeriodicTask::real_time_tick(time_waited);
1293   }
1294 
1295   // Signal that it is terminated
1296   {
1297     MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1298     _watcher_thread = NULL;
1299     Terminator_lock->notify();
1300   }
1301 
1302   // Thread destructor usually does this..
1303   ThreadLocalStorage::set_thread(NULL);
1304 }
1305 
1306 void WatcherThread::start() {
1307   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1308 
1309   if (watcher_thread() == NULL && _startable) {
1310     _should_terminate = false;
1311     // Create the single instance of WatcherThread
1312     new WatcherThread();
1313   }
1314 }
1315 
1316 void WatcherThread::make_startable() {
1317   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1318   _startable = true;
1319 }
1320 
1321 void WatcherThread::stop() {
1322   // Get the PeriodicTask_lock if we can. If we cannot, then the
1323   // WatcherThread is using it and we don't want to block on that lock
1324   // here because that might cause a safepoint deadlock depending on
1325   // what the current WatcherThread tasks are doing.
1326   bool have_lock = PeriodicTask_lock->try_lock();
1327 
1328   _should_terminate = true;
1329   OrderAccess::fence();  // ensure WatcherThread sees update in main loop
1330 
1331   if (have_lock) {
1332     WatcherThread* watcher = watcher_thread();
1333     if (watcher != NULL) {
1334       // If we managed to get the lock, then we should unpark the
1335       // WatcherThread so that it can see we want it to stop.
1336       watcher->unpark();
1337     }
1338 
1339     PeriodicTask_lock->unlock();
1340   }
1341 
1342   // it is ok to take late safepoints here, if needed
1343   MutexLocker mu(Terminator_lock);
1344 
1345   while (watcher_thread() != NULL) {
1346     // This wait should make safepoint checks, wait without a timeout,
1347     // and wait as a suspend-equivalent condition.
1348     //
1349     // Note: If the FlatProfiler is running, then this thread is waiting
1350     // for the WatcherThread to terminate and the WatcherThread, via the
1351     // FlatProfiler task, is waiting for the external suspend request on
1352     // this thread to complete. wait_for_ext_suspend_completion() will
1353     // eventually timeout, but that takes time. Making this wait a
1354     // suspend-equivalent condition solves that timeout problem.
1355     //
1356     Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1357                           Mutex::_as_suspend_equivalent_flag);
1358   }
1359 }
1360 
1361 void WatcherThread::unpark() {
1362   MutexLockerEx ml(PeriodicTask_lock->owned_by_self()
1363                    ? NULL
1364                    : PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1365   PeriodicTask_lock->notify();
1366 }
1367 
1368 void WatcherThread::print_on(outputStream* st) const {
1369   st->print("\"%s\" ", name());
1370   Thread::print_on(st);
1371   st->cr();
1372 }
1373 
1374 // ======= JavaThread ========
1375 
1376 // A JavaThread is a normal Java thread
1377 
1378 void JavaThread::initialize() {
1379   // Initialize fields
1380 
1381   // Set the claimed par_id to UINT_MAX (ie not claiming any par_ids)
1382   set_claimed_par_id(UINT_MAX);
1383 
1384   set_saved_exception_pc(NULL);
1385   set_threadObj(NULL);
1386   _anchor.clear();
1387   set_entry_point(NULL);
1388   set_jni_functions(jni_functions());
1389   set_callee_target(NULL);
1390   set_vm_result(NULL);
1391   set_vm_result_2(NULL);
1392   set_vframe_array_head(NULL);
1393   set_vframe_array_last(NULL);
1394   set_deferred_locals(NULL);
1395   set_deopt_mark(NULL);
1396   set_deopt_nmethod(NULL);
1397   clear_must_deopt_id();
1398   set_monitor_chunks(NULL);
1399   set_next(NULL);
1400   set_thread_state(_thread_new);
1401   _terminated = _not_terminated;
1402   _privileged_stack_top = NULL;
1403   _array_for_gc = NULL;
1404   _suspend_equivalent = false;
1405   _in_deopt_handler = 0;
1406   _doing_unsafe_access = false;
1407   _stack_guard_state = stack_guard_unused;
1408   (void)const_cast<oop&>(_exception_oop = oop(NULL));
1409   _exception_pc  = 0;
1410   _exception_handler_pc = 0;
1411   _is_method_handle_return = 0;
1412   _jvmti_thread_state= NULL;
1413   _should_post_on_exceptions_flag = JNI_FALSE;
1414   _jvmti_get_loaded_classes_closure = NULL;
1415   _interp_only_mode    = 0;
1416   _special_runtime_exit_condition = _no_async_condition;
1417   _pending_async_exception = NULL;
1418   _thread_stat = NULL;
1419   _thread_stat = new ThreadStatistics();
1420   _blocked_on_compilation = false;
1421   _jni_active_critical = 0;
1422   _pending_jni_exception_check_fn = NULL;
1423   _do_not_unlock_if_synchronized = false;
1424   _cached_monitor_info = NULL;
1425   _parker = Parker::Allocate(this);
1426 
1427 #ifndef PRODUCT
1428   _jmp_ring_index = 0;
1429   for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1430     record_jump(NULL, NULL, NULL, 0);
1431   }
1432 #endif // PRODUCT
1433 
1434   set_thread_profiler(NULL);
1435   if (FlatProfiler::is_active()) {
1436     // This is where we would decide to either give each thread it's own profiler
1437     // or use one global one from FlatProfiler,
1438     // or up to some count of the number of profiled threads, etc.
1439     ThreadProfiler* pp = new ThreadProfiler();
1440     pp->engage();
1441     set_thread_profiler(pp);
1442   }
1443 
1444   // Setup safepoint state info for this thread
1445   ThreadSafepointState::create(this);
1446 
1447   debug_only(_java_call_counter = 0);
1448 
1449   // JVMTI PopFrame support
1450   _popframe_condition = popframe_inactive;
1451   _popframe_preserved_args = NULL;
1452   _popframe_preserved_args_size = 0;
1453   _frames_to_pop_failed_realloc = 0;
1454 
1455   pd_initialize();
1456 }
1457 
1458 #if INCLUDE_ALL_GCS
1459 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1460 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1461 #endif // INCLUDE_ALL_GCS
1462 
1463 JavaThread::JavaThread(bool is_attaching_via_jni) :
1464                        Thread()
1465 #if INCLUDE_ALL_GCS
1466                        , _satb_mark_queue(&_satb_mark_queue_set),
1467                        _dirty_card_queue(&_dirty_card_queue_set)
1468 #endif // INCLUDE_ALL_GCS
1469 {
1470   initialize();
1471   if (is_attaching_via_jni) {
1472     _jni_attach_state = _attaching_via_jni;
1473   } else {
1474     _jni_attach_state = _not_attaching_via_jni;
1475   }
1476   assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1477 }
1478 
1479 bool JavaThread::reguard_stack(address cur_sp) {
1480   if (_stack_guard_state != stack_guard_yellow_disabled) {
1481     return true; // Stack already guarded or guard pages not needed.
1482   }
1483 
1484   if (register_stack_overflow()) {
1485     // For those architectures which have separate register and
1486     // memory stacks, we must check the register stack to see if
1487     // it has overflowed.
1488     return false;
1489   }
1490 
1491   // Java code never executes within the yellow zone: the latter is only
1492   // there to provoke an exception during stack banging.  If java code
1493   // is executing there, either StackShadowPages should be larger, or
1494   // some exception code in c1, c2 or the interpreter isn't unwinding
1495   // when it should.
1496   guarantee(cur_sp > stack_yellow_zone_base(), "not enough space to reguard - increase StackShadowPages");
1497 
1498   enable_stack_yellow_zone();
1499   return true;
1500 }
1501 
1502 bool JavaThread::reguard_stack(void) {
1503   return reguard_stack(os::current_stack_pointer());
1504 }
1505 
1506 
1507 void JavaThread::block_if_vm_exited() {
1508   if (_terminated == _vm_exited) {
1509     // _vm_exited is set at safepoint, and Threads_lock is never released
1510     // we will block here forever
1511     Threads_lock->lock_without_safepoint_check();
1512     ShouldNotReachHere();
1513   }
1514 }
1515 
1516 
1517 // Remove this ifdef when C1 is ported to the compiler interface.
1518 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1519 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1520 
1521 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1522                        Thread()
1523 #if INCLUDE_ALL_GCS
1524                        , _satb_mark_queue(&_satb_mark_queue_set),
1525                        _dirty_card_queue(&_dirty_card_queue_set)
1526 #endif // INCLUDE_ALL_GCS
1527 {
1528   initialize();
1529   _jni_attach_state = _not_attaching_via_jni;
1530   set_entry_point(entry_point);
1531   // Create the native thread itself.
1532   // %note runtime_23
1533   os::ThreadType thr_type = os::java_thread;
1534   thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1535                                                      os::java_thread;
1536   os::create_thread(this, thr_type, stack_sz);
1537   // The _osthread may be NULL here because we ran out of memory (too many threads active).
1538   // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1539   // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1540   // the exception consists of creating the exception object & initializing it, initialization
1541   // will leave the VM via a JavaCall and then all locks must be unlocked).
1542   //
1543   // The thread is still suspended when we reach here. Thread must be explicit started
1544   // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1545   // by calling Threads:add. The reason why this is not done here, is because the thread
1546   // object must be fully initialized (take a look at JVM_Start)
1547 }
1548 
1549 JavaThread::~JavaThread() {
1550 
1551   // JSR166 -- return the parker to the free list
1552   Parker::Release(_parker);
1553   _parker = NULL;
1554 
1555   // Free any remaining  previous UnrollBlock
1556   vframeArray* old_array = vframe_array_last();
1557 
1558   if (old_array != NULL) {
1559     Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1560     old_array->set_unroll_block(NULL);
1561     delete old_info;
1562     delete old_array;
1563   }
1564 
1565   GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1566   if (deferred != NULL) {
1567     // This can only happen if thread is destroyed before deoptimization occurs.
1568     assert(deferred->length() != 0, "empty array!");
1569     do {
1570       jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1571       deferred->remove_at(0);
1572       // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1573       delete dlv;
1574     } while (deferred->length() != 0);
1575     delete deferred;
1576   }
1577 
1578   // All Java related clean up happens in exit
1579   ThreadSafepointState::destroy(this);
1580   if (_thread_profiler != NULL) delete _thread_profiler;
1581   if (_thread_stat != NULL) delete _thread_stat;
1582 }
1583 
1584 
1585 // The first routine called by a new Java thread
1586 void JavaThread::run() {
1587   // initialize thread-local alloc buffer related fields
1588   this->initialize_tlab();
1589 
1590   // used to test validity of stack trace backs
1591   this->record_base_of_stack_pointer();
1592 
1593   // Record real stack base and size.
1594   this->record_stack_base_and_size();
1595 
1596   // Initialize thread local storage; set before calling MutexLocker
1597   this->initialize_thread_local_storage();
1598 
1599   this->create_stack_guard_pages();
1600 
1601   this->cache_global_variables();
1602 
1603   // Thread is now sufficient initialized to be handled by the safepoint code as being
1604   // in the VM. Change thread state from _thread_new to _thread_in_vm
1605   ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1606 
1607   assert(JavaThread::current() == this, "sanity check");
1608   assert(!Thread::current()->owns_locks(), "sanity check");
1609 
1610   DTRACE_THREAD_PROBE(start, this);
1611 
1612   // This operation might block. We call that after all safepoint checks for a new thread has
1613   // been completed.
1614   this->set_active_handles(JNIHandleBlock::allocate_block());
1615 
1616   if (JvmtiExport::should_post_thread_life()) {
1617     JvmtiExport::post_thread_start(this);
1618   }
1619 
1620   EventThreadStart event;
1621   if (event.should_commit()) {
1622     event.set_javalangthread(java_lang_Thread::thread_id(this->threadObj()));
1623     event.commit();
1624   }
1625 
1626   // We call another function to do the rest so we are sure that the stack addresses used
1627   // from there will be lower than the stack base just computed
1628   thread_main_inner();
1629 
1630   // Note, thread is no longer valid at this point!
1631 }
1632 
1633 
1634 void JavaThread::thread_main_inner() {
1635   assert(JavaThread::current() == this, "sanity check");
1636   assert(this->threadObj() != NULL, "just checking");
1637 
1638   // Execute thread entry point unless this thread has a pending exception
1639   // or has been stopped before starting.
1640   // Note: Due to JVM_StopThread we can have pending exceptions already!
1641   if (!this->has_pending_exception() &&
1642       !java_lang_Thread::is_stillborn(this->threadObj())) {
1643     {
1644       ResourceMark rm(this);
1645       this->set_native_thread_name(this->get_thread_name());
1646     }
1647     HandleMark hm(this);
1648     this->entry_point()(this, this);
1649   }
1650 
1651   DTRACE_THREAD_PROBE(stop, this);
1652 
1653   this->exit(false);
1654   delete this;
1655 }
1656 
1657 
1658 static void ensure_join(JavaThread* thread) {
1659   // We do not need to grap the Threads_lock, since we are operating on ourself.
1660   Handle threadObj(thread, thread->threadObj());
1661   assert(threadObj.not_null(), "java thread object must exist");
1662   ObjectLocker lock(threadObj, thread);
1663   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1664   thread->clear_pending_exception();
1665   // Thread is exiting. So set thread_status field in  java.lang.Thread class to TERMINATED.
1666   java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1667   // Clear the native thread instance - this makes isAlive return false and allows the join()
1668   // to complete once we've done the notify_all below
1669   java_lang_Thread::set_thread(threadObj(), NULL);
1670   lock.notify_all(thread);
1671   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1672   thread->clear_pending_exception();
1673 }
1674 
1675 
1676 // For any new cleanup additions, please check to see if they need to be applied to
1677 // cleanup_failed_attach_current_thread as well.
1678 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1679   assert(this == JavaThread::current(), "thread consistency check");
1680 
1681   HandleMark hm(this);
1682   Handle uncaught_exception(this, this->pending_exception());
1683   this->clear_pending_exception();
1684   Handle threadObj(this, this->threadObj());
1685   assert(threadObj.not_null(), "Java thread object should be created");
1686 
1687   if (get_thread_profiler() != NULL) {
1688     get_thread_profiler()->disengage();
1689     ResourceMark rm;
1690     get_thread_profiler()->print(get_thread_name());
1691   }
1692 
1693 
1694   // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1695   {
1696     EXCEPTION_MARK;
1697 
1698     CLEAR_PENDING_EXCEPTION;
1699   }
1700   if (!destroy_vm) {
1701     if (uncaught_exception.not_null()) {
1702       EXCEPTION_MARK;
1703       // Call method Thread.dispatchUncaughtException().
1704       KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1705       JavaValue result(T_VOID);
1706       JavaCalls::call_virtual(&result,
1707                               threadObj, thread_klass,
1708                               vmSymbols::dispatchUncaughtException_name(),
1709                               vmSymbols::throwable_void_signature(),
1710                               uncaught_exception,
1711                               THREAD);
1712       if (HAS_PENDING_EXCEPTION) {
1713         ResourceMark rm(this);
1714         jio_fprintf(defaultStream::error_stream(),
1715                     "\nException: %s thrown from the UncaughtExceptionHandler"
1716                     " in thread \"%s\"\n",
1717                     pending_exception()->klass()->external_name(),
1718                     get_thread_name());
1719         CLEAR_PENDING_EXCEPTION;
1720       }
1721     }
1722 
1723     // Called before the java thread exit since we want to read info
1724     // from java_lang_Thread object
1725     EventThreadEnd event;
1726     if (event.should_commit()) {
1727       event.set_javalangthread(java_lang_Thread::thread_id(this->threadObj()));
1728       event.commit();
1729     }
1730 
1731     // Call after last event on thread
1732     EVENT_THREAD_EXIT(this);
1733 
1734     // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1735     // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1736     // is deprecated anyhow.
1737     if (!is_Compiler_thread()) {
1738       int count = 3;
1739       while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1740         EXCEPTION_MARK;
1741         JavaValue result(T_VOID);
1742         KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1743         JavaCalls::call_virtual(&result,
1744                                 threadObj, thread_klass,
1745                                 vmSymbols::exit_method_name(),
1746                                 vmSymbols::void_method_signature(),
1747                                 THREAD);
1748         CLEAR_PENDING_EXCEPTION;
1749       }
1750     }
1751     // notify JVMTI
1752     if (JvmtiExport::should_post_thread_life()) {
1753       JvmtiExport::post_thread_end(this);
1754     }
1755 
1756     // We have notified the agents that we are exiting, before we go on,
1757     // we must check for a pending external suspend request and honor it
1758     // in order to not surprise the thread that made the suspend request.
1759     while (true) {
1760       {
1761         MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1762         if (!is_external_suspend()) {
1763           set_terminated(_thread_exiting);
1764           ThreadService::current_thread_exiting(this);
1765           break;
1766         }
1767         // Implied else:
1768         // Things get a little tricky here. We have a pending external
1769         // suspend request, but we are holding the SR_lock so we
1770         // can't just self-suspend. So we temporarily drop the lock
1771         // and then self-suspend.
1772       }
1773 
1774       ThreadBlockInVM tbivm(this);
1775       java_suspend_self();
1776 
1777       // We're done with this suspend request, but we have to loop around
1778       // and check again. Eventually we will get SR_lock without a pending
1779       // external suspend request and will be able to mark ourselves as
1780       // exiting.
1781     }
1782     // no more external suspends are allowed at this point
1783   } else {
1784     // before_exit() has already posted JVMTI THREAD_END events
1785   }
1786 
1787   // Notify waiters on thread object. This has to be done after exit() is called
1788   // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1789   // group should have the destroyed bit set before waiters are notified).
1790   ensure_join(this);
1791   assert(!this->has_pending_exception(), "ensure_join should have cleared");
1792 
1793   // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1794   // held by this thread must be released.  A detach operation must only
1795   // get here if there are no Java frames on the stack.  Therefore, any
1796   // owned monitors at this point MUST be JNI-acquired monitors which are
1797   // pre-inflated and in the monitor cache.
1798   //
1799   // ensure_join() ignores IllegalThreadStateExceptions, and so does this.
1800   if (exit_type == jni_detach && JNIDetachReleasesMonitors) {
1801     assert(!this->has_last_Java_frame(), "detaching with Java frames?");
1802     ObjectSynchronizer::release_monitors_owned_by_thread(this);
1803     assert(!this->has_pending_exception(), "release_monitors should have cleared");
1804   }
1805 
1806   // These things needs to be done while we are still a Java Thread. Make sure that thread
1807   // is in a consistent state, in case GC happens
1808   assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1809 
1810   if (active_handles() != NULL) {
1811     JNIHandleBlock* block = active_handles();
1812     set_active_handles(NULL);
1813     JNIHandleBlock::release_block(block);
1814   }
1815 
1816   if (free_handle_block() != NULL) {
1817     JNIHandleBlock* block = free_handle_block();
1818     set_free_handle_block(NULL);
1819     JNIHandleBlock::release_block(block);
1820   }
1821 
1822   // These have to be removed while this is still a valid thread.
1823   remove_stack_guard_pages();
1824 
1825   if (UseTLAB) {
1826     tlab().make_parsable(true);  // retire TLAB
1827   }
1828 
1829   if (JvmtiEnv::environments_might_exist()) {
1830     JvmtiExport::cleanup_thread(this);
1831   }
1832 
1833   // We must flush any deferred card marks before removing a thread from
1834   // the list of active threads.
1835   Universe::heap()->flush_deferred_store_barrier(this);
1836   assert(deferred_card_mark().is_empty(), "Should have been flushed");
1837 
1838 #if INCLUDE_ALL_GCS
1839   // We must flush the G1-related buffers before removing a thread
1840   // from the list of active threads. We must do this after any deferred
1841   // card marks have been flushed (above) so that any entries that are
1842   // added to the thread's dirty card queue as a result are not lost.
1843   if (UseG1GC) {
1844     flush_barrier_queues();
1845   }
1846 #endif // INCLUDE_ALL_GCS
1847 
1848   // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1849   Threads::remove(this);
1850 }
1851 
1852 #if INCLUDE_ALL_GCS
1853 // Flush G1-related queues.
1854 void JavaThread::flush_barrier_queues() {
1855   satb_mark_queue().flush();
1856   dirty_card_queue().flush();
1857 }
1858 
1859 void JavaThread::initialize_queues() {
1860   assert(!SafepointSynchronize::is_at_safepoint(),
1861          "we should not be at a safepoint");
1862 
1863   ObjPtrQueue& satb_queue = satb_mark_queue();
1864   SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1865   // The SATB queue should have been constructed with its active
1866   // field set to false.
1867   assert(!satb_queue.is_active(), "SATB queue should not be active");
1868   assert(satb_queue.is_empty(), "SATB queue should be empty");
1869   // If we are creating the thread during a marking cycle, we should
1870   // set the active field of the SATB queue to true.
1871   if (satb_queue_set.is_active()) {
1872     satb_queue.set_active(true);
1873   }
1874 
1875   DirtyCardQueue& dirty_queue = dirty_card_queue();
1876   // The dirty card queue should have been constructed with its
1877   // active field set to true.
1878   assert(dirty_queue.is_active(), "dirty card queue should be active");
1879 }
1880 #endif // INCLUDE_ALL_GCS
1881 
1882 void JavaThread::cleanup_failed_attach_current_thread() {
1883   if (get_thread_profiler() != NULL) {
1884     get_thread_profiler()->disengage();
1885     ResourceMark rm;
1886     get_thread_profiler()->print(get_thread_name());
1887   }
1888 
1889   if (active_handles() != NULL) {
1890     JNIHandleBlock* block = active_handles();
1891     set_active_handles(NULL);
1892     JNIHandleBlock::release_block(block);
1893   }
1894 
1895   if (free_handle_block() != NULL) {
1896     JNIHandleBlock* block = free_handle_block();
1897     set_free_handle_block(NULL);
1898     JNIHandleBlock::release_block(block);
1899   }
1900 
1901   // These have to be removed while this is still a valid thread.
1902   remove_stack_guard_pages();
1903 
1904   if (UseTLAB) {
1905     tlab().make_parsable(true);  // retire TLAB, if any
1906   }
1907 
1908 #if INCLUDE_ALL_GCS
1909   if (UseG1GC) {
1910     flush_barrier_queues();
1911   }
1912 #endif // INCLUDE_ALL_GCS
1913 
1914   Threads::remove(this);
1915   delete this;
1916 }
1917 
1918 
1919 
1920 
1921 JavaThread* JavaThread::active() {
1922   Thread* thread = ThreadLocalStorage::thread();
1923   assert(thread != NULL, "just checking");
1924   if (thread->is_Java_thread()) {
1925     return (JavaThread*) thread;
1926   } else {
1927     assert(thread->is_VM_thread(), "this must be a vm thread");
1928     VM_Operation* op = ((VMThread*) thread)->vm_operation();
1929     JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
1930     assert(ret->is_Java_thread(), "must be a Java thread");
1931     return ret;
1932   }
1933 }
1934 
1935 bool JavaThread::is_lock_owned(address adr) const {
1936   if (Thread::is_lock_owned(adr)) return true;
1937 
1938   for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
1939     if (chunk->contains(adr)) return true;
1940   }
1941 
1942   return false;
1943 }
1944 
1945 
1946 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
1947   chunk->set_next(monitor_chunks());
1948   set_monitor_chunks(chunk);
1949 }
1950 
1951 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
1952   guarantee(monitor_chunks() != NULL, "must be non empty");
1953   if (monitor_chunks() == chunk) {
1954     set_monitor_chunks(chunk->next());
1955   } else {
1956     MonitorChunk* prev = monitor_chunks();
1957     while (prev->next() != chunk) prev = prev->next();
1958     prev->set_next(chunk->next());
1959   }
1960 }
1961 
1962 // JVM support.
1963 
1964 // Note: this function shouldn't block if it's called in
1965 // _thread_in_native_trans state (such as from
1966 // check_special_condition_for_native_trans()).
1967 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
1968 
1969   if (has_last_Java_frame() && has_async_condition()) {
1970     // If we are at a polling page safepoint (not a poll return)
1971     // then we must defer async exception because live registers
1972     // will be clobbered by the exception path. Poll return is
1973     // ok because the call we a returning from already collides
1974     // with exception handling registers and so there is no issue.
1975     // (The exception handling path kills call result registers but
1976     //  this is ok since the exception kills the result anyway).
1977 
1978     if (is_at_poll_safepoint()) {
1979       // if the code we are returning to has deoptimized we must defer
1980       // the exception otherwise live registers get clobbered on the
1981       // exception path before deoptimization is able to retrieve them.
1982       //
1983       RegisterMap map(this, false);
1984       frame caller_fr = last_frame().sender(&map);
1985       assert(caller_fr.is_compiled_frame(), "what?");
1986       if (caller_fr.is_deoptimized_frame()) {
1987         if (TraceExceptions) {
1988           ResourceMark rm;
1989           tty->print_cr("deferred async exception at compiled safepoint");
1990         }
1991         return;
1992       }
1993     }
1994   }
1995 
1996   JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
1997   if (condition == _no_async_condition) {
1998     // Conditions have changed since has_special_runtime_exit_condition()
1999     // was called:
2000     // - if we were here only because of an external suspend request,
2001     //   then that was taken care of above (or cancelled) so we are done
2002     // - if we were here because of another async request, then it has
2003     //   been cleared between the has_special_runtime_exit_condition()
2004     //   and now so again we are done
2005     return;
2006   }
2007 
2008   // Check for pending async. exception
2009   if (_pending_async_exception != NULL) {
2010     // Only overwrite an already pending exception, if it is not a threadDeath.
2011     if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2012 
2013       // We cannot call Exceptions::_throw(...) here because we cannot block
2014       set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2015 
2016       if (TraceExceptions) {
2017         ResourceMark rm;
2018         tty->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", this);
2019         if (has_last_Java_frame()) {
2020           frame f = last_frame();
2021           tty->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", f.pc(), f.sp());
2022         }
2023         tty->print_cr(" of type: %s", InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2024       }
2025       _pending_async_exception = NULL;
2026       clear_has_async_exception();
2027     }
2028   }
2029 
2030   if (check_unsafe_error &&
2031       condition == _async_unsafe_access_error && !has_pending_exception()) {
2032     condition = _no_async_condition;  // done
2033     switch (thread_state()) {
2034     case _thread_in_vm: {
2035       JavaThread* THREAD = this;
2036       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2037     }
2038     case _thread_in_native: {
2039       ThreadInVMfromNative tiv(this);
2040       JavaThread* THREAD = this;
2041       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2042     }
2043     case _thread_in_Java: {
2044       ThreadInVMfromJava tiv(this);
2045       JavaThread* THREAD = this;
2046       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2047     }
2048     default:
2049       ShouldNotReachHere();
2050     }
2051   }
2052 
2053   assert(condition == _no_async_condition || has_pending_exception() ||
2054          (!check_unsafe_error && condition == _async_unsafe_access_error),
2055          "must have handled the async condition, if no exception");
2056 }
2057 
2058 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2059   //
2060   // Check for pending external suspend. Internal suspend requests do
2061   // not use handle_special_runtime_exit_condition().
2062   // If JNIEnv proxies are allowed, don't self-suspend if the target
2063   // thread is not the current thread. In older versions of jdbx, jdbx
2064   // threads could call into the VM with another thread's JNIEnv so we
2065   // can be here operating on behalf of a suspended thread (4432884).
2066   bool do_self_suspend = is_external_suspend_with_lock();
2067   if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2068     //
2069     // Because thread is external suspended the safepoint code will count
2070     // thread as at a safepoint. This can be odd because we can be here
2071     // as _thread_in_Java which would normally transition to _thread_blocked
2072     // at a safepoint. We would like to mark the thread as _thread_blocked
2073     // before calling java_suspend_self like all other callers of it but
2074     // we must then observe proper safepoint protocol. (We can't leave
2075     // _thread_blocked with a safepoint in progress). However we can be
2076     // here as _thread_in_native_trans so we can't use a normal transition
2077     // constructor/destructor pair because they assert on that type of
2078     // transition. We could do something like:
2079     //
2080     // JavaThreadState state = thread_state();
2081     // set_thread_state(_thread_in_vm);
2082     // {
2083     //   ThreadBlockInVM tbivm(this);
2084     //   java_suspend_self()
2085     // }
2086     // set_thread_state(_thread_in_vm_trans);
2087     // if (safepoint) block;
2088     // set_thread_state(state);
2089     //
2090     // but that is pretty messy. Instead we just go with the way the
2091     // code has worked before and note that this is the only path to
2092     // java_suspend_self that doesn't put the thread in _thread_blocked
2093     // mode.
2094 
2095     frame_anchor()->make_walkable(this);
2096     java_suspend_self();
2097 
2098     // We might be here for reasons in addition to the self-suspend request
2099     // so check for other async requests.
2100   }
2101 
2102   if (check_asyncs) {
2103     check_and_handle_async_exceptions();
2104   }
2105 }
2106 
2107 void JavaThread::send_thread_stop(oop java_throwable)  {
2108   assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2109   assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2110   assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2111 
2112   // Do not throw asynchronous exceptions against the compiler thread
2113   // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2114   if (is_Compiler_thread()) return;
2115 
2116   {
2117     // Actually throw the Throwable against the target Thread - however
2118     // only if there is no thread death exception installed already.
2119     if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2120       // If the topmost frame is a runtime stub, then we are calling into
2121       // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2122       // must deoptimize the caller before continuing, as the compiled  exception handler table
2123       // may not be valid
2124       if (has_last_Java_frame()) {
2125         frame f = last_frame();
2126         if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2127           // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2128           RegisterMap reg_map(this, UseBiasedLocking);
2129           frame compiled_frame = f.sender(&reg_map);
2130           if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2131             Deoptimization::deoptimize(this, compiled_frame, &reg_map);
2132           }
2133         }
2134       }
2135 
2136       // Set async. pending exception in thread.
2137       set_pending_async_exception(java_throwable);
2138 
2139       if (TraceExceptions) {
2140         ResourceMark rm;
2141         tty->print_cr("Pending Async. exception installed of type: %s", InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2142       }
2143       // for AbortVMOnException flag
2144       NOT_PRODUCT(Exceptions::debug_check_abort(InstanceKlass::cast(_pending_async_exception->klass())->external_name()));
2145     }
2146   }
2147 
2148 
2149   // Interrupt thread so it will wake up from a potential wait()
2150   Thread::interrupt(this);
2151 }
2152 
2153 // External suspension mechanism.
2154 //
2155 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2156 // to any VM_locks and it is at a transition
2157 // Self-suspension will happen on the transition out of the vm.
2158 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2159 //
2160 // Guarantees on return:
2161 //   + Target thread will not execute any new bytecode (that's why we need to
2162 //     force a safepoint)
2163 //   + Target thread will not enter any new monitors
2164 //
2165 void JavaThread::java_suspend() {
2166   { MutexLocker mu(Threads_lock);
2167     if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2168       return;
2169     }
2170   }
2171 
2172   { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2173     if (!is_external_suspend()) {
2174       // a racing resume has cancelled us; bail out now
2175       return;
2176     }
2177 
2178     // suspend is done
2179     uint32_t debug_bits = 0;
2180     // Warning: is_ext_suspend_completed() may temporarily drop the
2181     // SR_lock to allow the thread to reach a stable thread state if
2182     // it is currently in a transient thread state.
2183     if (is_ext_suspend_completed(false /* !called_by_wait */,
2184                                  SuspendRetryDelay, &debug_bits)) {
2185       return;
2186     }
2187   }
2188 
2189   VM_ForceSafepoint vm_suspend;
2190   VMThread::execute(&vm_suspend);
2191 }
2192 
2193 // Part II of external suspension.
2194 // A JavaThread self suspends when it detects a pending external suspend
2195 // request. This is usually on transitions. It is also done in places
2196 // where continuing to the next transition would surprise the caller,
2197 // e.g., monitor entry.
2198 //
2199 // Returns the number of times that the thread self-suspended.
2200 //
2201 // Note: DO NOT call java_suspend_self() when you just want to block current
2202 //       thread. java_suspend_self() is the second stage of cooperative
2203 //       suspension for external suspend requests and should only be used
2204 //       to complete an external suspend request.
2205 //
2206 int JavaThread::java_suspend_self() {
2207   int ret = 0;
2208 
2209   // we are in the process of exiting so don't suspend
2210   if (is_exiting()) {
2211     clear_external_suspend();
2212     return ret;
2213   }
2214 
2215   assert(_anchor.walkable() ||
2216          (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2217          "must have walkable stack");
2218 
2219   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2220 
2221   assert(!this->is_ext_suspended(),
2222          "a thread trying to self-suspend should not already be suspended");
2223 
2224   if (this->is_suspend_equivalent()) {
2225     // If we are self-suspending as a result of the lifting of a
2226     // suspend equivalent condition, then the suspend_equivalent
2227     // flag is not cleared until we set the ext_suspended flag so
2228     // that wait_for_ext_suspend_completion() returns consistent
2229     // results.
2230     this->clear_suspend_equivalent();
2231   }
2232 
2233   // A racing resume may have cancelled us before we grabbed SR_lock
2234   // above. Or another external suspend request could be waiting for us
2235   // by the time we return from SR_lock()->wait(). The thread
2236   // that requested the suspension may already be trying to walk our
2237   // stack and if we return now, we can change the stack out from under
2238   // it. This would be a "bad thing (TM)" and cause the stack walker
2239   // to crash. We stay self-suspended until there are no more pending
2240   // external suspend requests.
2241   while (is_external_suspend()) {
2242     ret++;
2243     this->set_ext_suspended();
2244 
2245     // _ext_suspended flag is cleared by java_resume()
2246     while (is_ext_suspended()) {
2247       this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2248     }
2249   }
2250 
2251   return ret;
2252 }
2253 
2254 #ifdef ASSERT
2255 // verify the JavaThread has not yet been published in the Threads::list, and
2256 // hence doesn't need protection from concurrent access at this stage
2257 void JavaThread::verify_not_published() {
2258   if (!Threads_lock->owned_by_self()) {
2259     MutexLockerEx ml(Threads_lock,  Mutex::_no_safepoint_check_flag);
2260     assert(!Threads::includes(this),
2261            "java thread shouldn't have been published yet!");
2262   } else {
2263     assert(!Threads::includes(this),
2264            "java thread shouldn't have been published yet!");
2265   }
2266 }
2267 #endif
2268 
2269 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2270 // progress or when _suspend_flags is non-zero.
2271 // Current thread needs to self-suspend if there is a suspend request and/or
2272 // block if a safepoint is in progress.
2273 // Async exception ISN'T checked.
2274 // Note only the ThreadInVMfromNative transition can call this function
2275 // directly and when thread state is _thread_in_native_trans
2276 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2277   assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2278 
2279   JavaThread *curJT = JavaThread::current();
2280   bool do_self_suspend = thread->is_external_suspend();
2281 
2282   assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2283 
2284   // If JNIEnv proxies are allowed, don't self-suspend if the target
2285   // thread is not the current thread. In older versions of jdbx, jdbx
2286   // threads could call into the VM with another thread's JNIEnv so we
2287   // can be here operating on behalf of a suspended thread (4432884).
2288   if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2289     JavaThreadState state = thread->thread_state();
2290 
2291     // We mark this thread_blocked state as a suspend-equivalent so
2292     // that a caller to is_ext_suspend_completed() won't be confused.
2293     // The suspend-equivalent state is cleared by java_suspend_self().
2294     thread->set_suspend_equivalent();
2295 
2296     // If the safepoint code sees the _thread_in_native_trans state, it will
2297     // wait until the thread changes to other thread state. There is no
2298     // guarantee on how soon we can obtain the SR_lock and complete the
2299     // self-suspend request. It would be a bad idea to let safepoint wait for
2300     // too long. Temporarily change the state to _thread_blocked to
2301     // let the VM thread know that this thread is ready for GC. The problem
2302     // of changing thread state is that safepoint could happen just after
2303     // java_suspend_self() returns after being resumed, and VM thread will
2304     // see the _thread_blocked state. We must check for safepoint
2305     // after restoring the state and make sure we won't leave while a safepoint
2306     // is in progress.
2307     thread->set_thread_state(_thread_blocked);
2308     thread->java_suspend_self();
2309     thread->set_thread_state(state);
2310     // Make sure new state is seen by VM thread
2311     if (os::is_MP()) {
2312       if (UseMembar) {
2313         // Force a fence between the write above and read below
2314         OrderAccess::fence();
2315       } else {
2316         // Must use this rather than serialization page in particular on Windows
2317         InterfaceSupport::serialize_memory(thread);
2318       }
2319     }
2320   }
2321 
2322   if (SafepointSynchronize::do_call_back()) {
2323     // If we are safepointing, then block the caller which may not be
2324     // the same as the target thread (see above).
2325     SafepointSynchronize::block(curJT);
2326   }
2327 
2328   if (thread->is_deopt_suspend()) {
2329     thread->clear_deopt_suspend();
2330     RegisterMap map(thread, false);
2331     frame f = thread->last_frame();
2332     while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2333       f = f.sender(&map);
2334     }
2335     if (f.id() == thread->must_deopt_id()) {
2336       thread->clear_must_deopt_id();
2337       f.deoptimize(thread);
2338     } else {
2339       fatal("missed deoptimization!");
2340     }
2341   }
2342 }
2343 
2344 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2345 // progress or when _suspend_flags is non-zero.
2346 // Current thread needs to self-suspend if there is a suspend request and/or
2347 // block if a safepoint is in progress.
2348 // Also check for pending async exception (not including unsafe access error).
2349 // Note only the native==>VM/Java barriers can call this function and when
2350 // thread state is _thread_in_native_trans.
2351 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2352   check_safepoint_and_suspend_for_native_trans(thread);
2353 
2354   if (thread->has_async_exception()) {
2355     // We are in _thread_in_native_trans state, don't handle unsafe
2356     // access error since that may block.
2357     thread->check_and_handle_async_exceptions(false);
2358   }
2359 }
2360 
2361 // This is a variant of the normal
2362 // check_special_condition_for_native_trans with slightly different
2363 // semantics for use by critical native wrappers.  It does all the
2364 // normal checks but also performs the transition back into
2365 // thread_in_Java state.  This is required so that critical natives
2366 // can potentially block and perform a GC if they are the last thread
2367 // exiting the GC_locker.
2368 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2369   check_special_condition_for_native_trans(thread);
2370 
2371   // Finish the transition
2372   thread->set_thread_state(_thread_in_Java);
2373 
2374   if (thread->do_critical_native_unlock()) {
2375     ThreadInVMfromJavaNoAsyncException tiv(thread);
2376     GC_locker::unlock_critical(thread);
2377     thread->clear_critical_native_unlock();
2378   }
2379 }
2380 
2381 // We need to guarantee the Threads_lock here, since resumes are not
2382 // allowed during safepoint synchronization
2383 // Can only resume from an external suspension
2384 void JavaThread::java_resume() {
2385   assert_locked_or_safepoint(Threads_lock);
2386 
2387   // Sanity check: thread is gone, has started exiting or the thread
2388   // was not externally suspended.
2389   if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2390     return;
2391   }
2392 
2393   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2394 
2395   clear_external_suspend();
2396 
2397   if (is_ext_suspended()) {
2398     clear_ext_suspended();
2399     SR_lock()->notify_all();
2400   }
2401 }
2402 
2403 void JavaThread::create_stack_guard_pages() {
2404   if (! os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) return;
2405   address low_addr = stack_base() - stack_size();
2406   size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
2407 
2408   int allocate = os::allocate_stack_guard_pages();
2409   // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2410 
2411   if (allocate && !os::create_stack_guard_pages((char *) low_addr, len)) {
2412     warning("Attempt to allocate stack guard pages failed.");
2413     return;
2414   }
2415 
2416   if (os::guard_memory((char *) low_addr, len)) {
2417     _stack_guard_state = stack_guard_enabled;
2418   } else {
2419     warning("Attempt to protect stack guard pages failed.");
2420     if (os::uncommit_memory((char *) low_addr, len)) {
2421       warning("Attempt to deallocate stack guard pages failed.");
2422     }
2423   }
2424 }
2425 
2426 void JavaThread::remove_stack_guard_pages() {
2427   assert(Thread::current() == this, "from different thread");
2428   if (_stack_guard_state == stack_guard_unused) return;
2429   address low_addr = stack_base() - stack_size();
2430   size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
2431 
2432   if (os::allocate_stack_guard_pages()) {
2433     if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2434       _stack_guard_state = stack_guard_unused;
2435     } else {
2436       warning("Attempt to deallocate stack guard pages failed.");
2437     }
2438   } else {
2439     if (_stack_guard_state == stack_guard_unused) return;
2440     if (os::unguard_memory((char *) low_addr, len)) {
2441       _stack_guard_state = stack_guard_unused;
2442     } else {
2443       warning("Attempt to unprotect stack guard pages failed.");
2444     }
2445   }
2446 }
2447 
2448 void JavaThread::enable_stack_yellow_zone() {
2449   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2450   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2451 
2452   // The base notation is from the stacks point of view, growing downward.
2453   // We need to adjust it to work correctly with guard_memory()
2454   address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2455 
2456   guarantee(base < stack_base(), "Error calculating stack yellow zone");
2457   guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2458 
2459   if (os::guard_memory((char *) base, stack_yellow_zone_size())) {
2460     _stack_guard_state = stack_guard_enabled;
2461   } else {
2462     warning("Attempt to guard stack yellow zone failed.");
2463   }
2464   enable_register_stack_guard();
2465 }
2466 
2467 void JavaThread::disable_stack_yellow_zone() {
2468   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2469   assert(_stack_guard_state != stack_guard_yellow_disabled, "already disabled");
2470 
2471   // Simply return if called for a thread that does not use guard pages.
2472   if (_stack_guard_state == stack_guard_unused) return;
2473 
2474   // The base notation is from the stacks point of view, growing downward.
2475   // We need to adjust it to work correctly with guard_memory()
2476   address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2477 
2478   if (os::unguard_memory((char *)base, stack_yellow_zone_size())) {
2479     _stack_guard_state = stack_guard_yellow_disabled;
2480   } else {
2481     warning("Attempt to unguard stack yellow zone failed.");
2482   }
2483   disable_register_stack_guard();
2484 }
2485 
2486 void JavaThread::enable_stack_red_zone() {
2487   // The base notation is from the stacks point of view, growing downward.
2488   // We need to adjust it to work correctly with guard_memory()
2489   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2490   address base = stack_red_zone_base() - stack_red_zone_size();
2491 
2492   guarantee(base < stack_base(), "Error calculating stack red zone");
2493   guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2494 
2495   if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2496     warning("Attempt to guard stack red zone failed.");
2497   }
2498 }
2499 
2500 void JavaThread::disable_stack_red_zone() {
2501   // The base notation is from the stacks point of view, growing downward.
2502   // We need to adjust it to work correctly with guard_memory()
2503   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2504   address base = stack_red_zone_base() - stack_red_zone_size();
2505   if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2506     warning("Attempt to unguard stack red zone failed.");
2507   }
2508 }
2509 
2510 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2511   // ignore is there is no stack
2512   if (!has_last_Java_frame()) return;
2513   // traverse the stack frames. Starts from top frame.
2514   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2515     frame* fr = fst.current();
2516     f(fr, fst.register_map());
2517   }
2518 }
2519 
2520 
2521 #ifndef PRODUCT
2522 // Deoptimization
2523 // Function for testing deoptimization
2524 void JavaThread::deoptimize() {
2525   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2526   StackFrameStream fst(this, UseBiasedLocking);
2527   bool deopt = false;           // Dump stack only if a deopt actually happens.
2528   bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2529   // Iterate over all frames in the thread and deoptimize
2530   for (; !fst.is_done(); fst.next()) {
2531     if (fst.current()->can_be_deoptimized()) {
2532 
2533       if (only_at) {
2534         // Deoptimize only at particular bcis.  DeoptimizeOnlyAt
2535         // consists of comma or carriage return separated numbers so
2536         // search for the current bci in that string.
2537         address pc = fst.current()->pc();
2538         nmethod* nm =  (nmethod*) fst.current()->cb();
2539         ScopeDesc* sd = nm->scope_desc_at(pc);
2540         char buffer[8];
2541         jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2542         size_t len = strlen(buffer);
2543         const char * found = strstr(DeoptimizeOnlyAt, buffer);
2544         while (found != NULL) {
2545           if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2546               (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2547             // Check that the bci found is bracketed by terminators.
2548             break;
2549           }
2550           found = strstr(found + 1, buffer);
2551         }
2552         if (!found) {
2553           continue;
2554         }
2555       }
2556 
2557       if (DebugDeoptimization && !deopt) {
2558         deopt = true; // One-time only print before deopt
2559         tty->print_cr("[BEFORE Deoptimization]");
2560         trace_frames();
2561         trace_stack();
2562       }
2563       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2564     }
2565   }
2566 
2567   if (DebugDeoptimization && deopt) {
2568     tty->print_cr("[AFTER Deoptimization]");
2569     trace_frames();
2570   }
2571 }
2572 
2573 
2574 // Make zombies
2575 void JavaThread::make_zombies() {
2576   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2577     if (fst.current()->can_be_deoptimized()) {
2578       // it is a Java nmethod
2579       nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2580       nm->make_not_entrant();
2581     }
2582   }
2583 }
2584 #endif // PRODUCT
2585 
2586 
2587 void JavaThread::deoptimized_wrt_marked_nmethods() {
2588   if (!has_last_Java_frame()) return;
2589   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2590   StackFrameStream fst(this, UseBiasedLocking);
2591   for (; !fst.is_done(); fst.next()) {
2592     if (fst.current()->should_be_deoptimized()) {
2593       if (LogCompilation && xtty != NULL) {
2594         nmethod* nm = fst.current()->cb()->as_nmethod_or_null();
2595         xtty->elem("deoptimized thread='" UINTX_FORMAT "' compile_id='%d'",
2596                    this->name(), nm != NULL ? nm->compile_id() : -1);
2597       }
2598 
2599       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2600     }
2601   }
2602 }
2603 
2604 
2605 // If the caller is a NamedThread, then remember, in the current scope,
2606 // the given JavaThread in its _processed_thread field.
2607 class RememberProcessedThread: public StackObj {
2608   NamedThread* _cur_thr;
2609  public:
2610   RememberProcessedThread(JavaThread* jthr) {
2611     Thread* thread = Thread::current();
2612     if (thread->is_Named_thread()) {
2613       _cur_thr = (NamedThread *)thread;
2614       _cur_thr->set_processed_thread(jthr);
2615     } else {
2616       _cur_thr = NULL;
2617     }
2618   }
2619 
2620   ~RememberProcessedThread() {
2621     if (_cur_thr) {
2622       _cur_thr->set_processed_thread(NULL);
2623     }
2624   }
2625 };
2626 
2627 void JavaThread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
2628   // Verify that the deferred card marks have been flushed.
2629   assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2630 
2631   // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2632   // since there may be more than one thread using each ThreadProfiler.
2633 
2634   // Traverse the GCHandles
2635   Thread::oops_do(f, cld_f, cf);
2636 
2637   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2638          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2639 
2640   if (has_last_Java_frame()) {
2641     // Record JavaThread to GC thread
2642     RememberProcessedThread rpt(this);
2643 
2644     // Traverse the privileged stack
2645     if (_privileged_stack_top != NULL) {
2646       _privileged_stack_top->oops_do(f);
2647     }
2648 
2649     // traverse the registered growable array
2650     if (_array_for_gc != NULL) {
2651       for (int index = 0; index < _array_for_gc->length(); index++) {
2652         f->do_oop(_array_for_gc->adr_at(index));
2653       }
2654     }
2655 
2656     // Traverse the monitor chunks
2657     for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2658       chunk->oops_do(f);
2659     }
2660 
2661     // Traverse the execution stack
2662     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2663       fst.current()->oops_do(f, cld_f, cf, fst.register_map());
2664     }
2665   }
2666 
2667   // callee_target is never live across a gc point so NULL it here should
2668   // it still contain a methdOop.
2669 
2670   set_callee_target(NULL);
2671 
2672   assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2673   // If we have deferred set_locals there might be oops waiting to be
2674   // written
2675   GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2676   if (list != NULL) {
2677     for (int i = 0; i < list->length(); i++) {
2678       list->at(i)->oops_do(f);
2679     }
2680   }
2681 
2682   // Traverse instance variables at the end since the GC may be moving things
2683   // around using this function
2684   f->do_oop((oop*) &_threadObj);
2685   f->do_oop((oop*) &_vm_result);
2686   f->do_oop((oop*) &_exception_oop);
2687   f->do_oop((oop*) &_pending_async_exception);
2688 
2689   if (jvmti_thread_state() != NULL) {
2690     jvmti_thread_state()->oops_do(f);
2691   }
2692 }
2693 
2694 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2695   Thread::nmethods_do(cf);  // (super method is a no-op)
2696 
2697   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2698          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2699 
2700   if (has_last_Java_frame()) {
2701     // Traverse the execution stack
2702     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2703       fst.current()->nmethods_do(cf);
2704     }
2705   }
2706 }
2707 
2708 void JavaThread::metadata_do(void f(Metadata*)) {
2709   Thread::metadata_do(f);
2710   if (has_last_Java_frame()) {
2711     // Traverse the execution stack to call f() on the methods in the stack
2712     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2713       fst.current()->metadata_do(f);
2714     }
2715   } else if (is_Compiler_thread()) {
2716     // need to walk ciMetadata in current compile tasks to keep alive.
2717     CompilerThread* ct = (CompilerThread*)this;
2718     if (ct->env() != NULL) {
2719       ct->env()->metadata_do(f);
2720     }
2721   }
2722 }
2723 
2724 // Printing
2725 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2726   switch (_thread_state) {
2727   case _thread_uninitialized:     return "_thread_uninitialized";
2728   case _thread_new:               return "_thread_new";
2729   case _thread_new_trans:         return "_thread_new_trans";
2730   case _thread_in_native:         return "_thread_in_native";
2731   case _thread_in_native_trans:   return "_thread_in_native_trans";
2732   case _thread_in_vm:             return "_thread_in_vm";
2733   case _thread_in_vm_trans:       return "_thread_in_vm_trans";
2734   case _thread_in_Java:           return "_thread_in_Java";
2735   case _thread_in_Java_trans:     return "_thread_in_Java_trans";
2736   case _thread_blocked:           return "_thread_blocked";
2737   case _thread_blocked_trans:     return "_thread_blocked_trans";
2738   default:                        return "unknown thread state";
2739   }
2740 }
2741 
2742 #ifndef PRODUCT
2743 void JavaThread::print_thread_state_on(outputStream *st) const {
2744   st->print_cr("   JavaThread state: %s", _get_thread_state_name(_thread_state));
2745 };
2746 void JavaThread::print_thread_state() const {
2747   print_thread_state_on(tty);
2748 }
2749 #endif // PRODUCT
2750 
2751 // Called by Threads::print() for VM_PrintThreads operation
2752 void JavaThread::print_on(outputStream *st) const {
2753   st->print("\"%s\" ", get_thread_name());
2754   oop thread_oop = threadObj();
2755   if (thread_oop != NULL) {
2756     st->print("#" INT64_FORMAT " ", java_lang_Thread::thread_id(thread_oop));
2757     if (java_lang_Thread::is_daemon(thread_oop))  st->print("daemon ");
2758     st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2759   }
2760   Thread::print_on(st);
2761   // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2762   st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2763   if (thread_oop != NULL) {
2764     st->print_cr("   java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2765   }
2766 #ifndef PRODUCT
2767   print_thread_state_on(st);
2768   _safepoint_state->print_on(st);
2769 #endif // PRODUCT
2770 }
2771 
2772 // Called by fatal error handler. The difference between this and
2773 // JavaThread::print() is that we can't grab lock or allocate memory.
2774 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2775   st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2776   oop thread_obj = threadObj();
2777   if (thread_obj != NULL) {
2778     if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2779   }
2780   st->print(" [");
2781   st->print("%s", _get_thread_state_name(_thread_state));
2782   if (osthread()) {
2783     st->print(", id=%d", osthread()->thread_id());
2784   }
2785   st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2786             _stack_base - _stack_size, _stack_base);
2787   st->print("]");
2788   return;
2789 }
2790 
2791 // Verification
2792 
2793 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2794 
2795 void JavaThread::verify() {
2796   // Verify oops in the thread.
2797   oops_do(&VerifyOopClosure::verify_oop, NULL, NULL);
2798 
2799   // Verify the stack frames.
2800   frames_do(frame_verify);
2801 }
2802 
2803 // CR 6300358 (sub-CR 2137150)
2804 // Most callers of this method assume that it can't return NULL but a
2805 // thread may not have a name whilst it is in the process of attaching to
2806 // the VM - see CR 6412693, and there are places where a JavaThread can be
2807 // seen prior to having it's threadObj set (eg JNI attaching threads and
2808 // if vm exit occurs during initialization). These cases can all be accounted
2809 // for such that this method never returns NULL.
2810 const char* JavaThread::get_thread_name() const {
2811 #ifdef ASSERT
2812   // early safepoints can hit while current thread does not yet have TLS
2813   if (!SafepointSynchronize::is_at_safepoint()) {
2814     Thread *cur = Thread::current();
2815     if (!(cur->is_Java_thread() && cur == this)) {
2816       // Current JavaThreads are allowed to get their own name without
2817       // the Threads_lock.
2818       assert_locked_or_safepoint(Threads_lock);
2819     }
2820   }
2821 #endif // ASSERT
2822   return get_thread_name_string();
2823 }
2824 
2825 // Returns a non-NULL representation of this thread's name, or a suitable
2826 // descriptive string if there is no set name
2827 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
2828   const char* name_str;
2829   oop thread_obj = threadObj();
2830   if (thread_obj != NULL) {
2831     oop name = java_lang_Thread::name(thread_obj);
2832     if (name != NULL) {
2833       if (buf == NULL) {
2834         name_str = java_lang_String::as_utf8_string(name);
2835       } else {
2836         name_str = java_lang_String::as_utf8_string(name, buf, buflen);
2837       }
2838     } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
2839       name_str = "<no-name - thread is attaching>";
2840     } else {
2841       name_str = Thread::name();
2842     }
2843   } else {
2844     name_str = Thread::name();
2845   }
2846   assert(name_str != NULL, "unexpected NULL thread name");
2847   return name_str;
2848 }
2849 
2850 
2851 const char* JavaThread::get_threadgroup_name() const {
2852   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2853   oop thread_obj = threadObj();
2854   if (thread_obj != NULL) {
2855     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2856     if (thread_group != NULL) {
2857       typeArrayOop name = java_lang_ThreadGroup::name(thread_group);
2858       // ThreadGroup.name can be null
2859       if (name != NULL) {
2860         const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2861         return str;
2862       }
2863     }
2864   }
2865   return NULL;
2866 }
2867 
2868 const char* JavaThread::get_parent_name() const {
2869   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2870   oop thread_obj = threadObj();
2871   if (thread_obj != NULL) {
2872     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2873     if (thread_group != NULL) {
2874       oop parent = java_lang_ThreadGroup::parent(thread_group);
2875       if (parent != NULL) {
2876         typeArrayOop name = java_lang_ThreadGroup::name(parent);
2877         // ThreadGroup.name can be null
2878         if (name != NULL) {
2879           const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2880           return str;
2881         }
2882       }
2883     }
2884   }
2885   return NULL;
2886 }
2887 
2888 ThreadPriority JavaThread::java_priority() const {
2889   oop thr_oop = threadObj();
2890   if (thr_oop == NULL) return NormPriority; // Bootstrapping
2891   ThreadPriority priority = java_lang_Thread::priority(thr_oop);
2892   assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
2893   return priority;
2894 }
2895 
2896 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
2897 
2898   assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
2899   // Link Java Thread object <-> C++ Thread
2900 
2901   // Get the C++ thread object (an oop) from the JNI handle (a jthread)
2902   // and put it into a new Handle.  The Handle "thread_oop" can then
2903   // be used to pass the C++ thread object to other methods.
2904 
2905   // Set the Java level thread object (jthread) field of the
2906   // new thread (a JavaThread *) to C++ thread object using the
2907   // "thread_oop" handle.
2908 
2909   // Set the thread field (a JavaThread *) of the
2910   // oop representing the java_lang_Thread to the new thread (a JavaThread *).
2911 
2912   Handle thread_oop(Thread::current(),
2913                     JNIHandles::resolve_non_null(jni_thread));
2914   assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
2915          "must be initialized");
2916   set_threadObj(thread_oop());
2917   java_lang_Thread::set_thread(thread_oop(), this);
2918 
2919   if (prio == NoPriority) {
2920     prio = java_lang_Thread::priority(thread_oop());
2921     assert(prio != NoPriority, "A valid priority should be present");
2922   }
2923 
2924   // Push the Java priority down to the native thread; needs Threads_lock
2925   Thread::set_priority(this, prio);
2926 
2927   prepare_ext();
2928 
2929   // Add the new thread to the Threads list and set it in motion.
2930   // We must have threads lock in order to call Threads::add.
2931   // It is crucial that we do not block before the thread is
2932   // added to the Threads list for if a GC happens, then the java_thread oop
2933   // will not be visited by GC.
2934   Threads::add(this);
2935 }
2936 
2937 oop JavaThread::current_park_blocker() {
2938   // Support for JSR-166 locks
2939   oop thread_oop = threadObj();
2940   if (thread_oop != NULL &&
2941       JDK_Version::current().supports_thread_park_blocker()) {
2942     return java_lang_Thread::park_blocker(thread_oop);
2943   }
2944   return NULL;
2945 }
2946 
2947 
2948 void JavaThread::print_stack_on(outputStream* st) {
2949   if (!has_last_Java_frame()) return;
2950   ResourceMark rm;
2951   HandleMark   hm;
2952 
2953   RegisterMap reg_map(this);
2954   vframe* start_vf = last_java_vframe(&reg_map);
2955   int count = 0;
2956   for (vframe* f = start_vf; f; f = f->sender()) {
2957     if (f->is_java_frame()) {
2958       javaVFrame* jvf = javaVFrame::cast(f);
2959       java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
2960 
2961       // Print out lock information
2962       if (JavaMonitorsInStackTrace) {
2963         jvf->print_lock_info_on(st, count);
2964       }
2965     } else {
2966       // Ignore non-Java frames
2967     }
2968 
2969     // Bail-out case for too deep stacks
2970     count++;
2971     if (MaxJavaStackTraceDepth == count) return;
2972   }
2973 }
2974 
2975 
2976 // JVMTI PopFrame support
2977 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
2978   assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
2979   if (in_bytes(size_in_bytes) != 0) {
2980     _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
2981     _popframe_preserved_args_size = in_bytes(size_in_bytes);
2982     Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
2983   }
2984 }
2985 
2986 void* JavaThread::popframe_preserved_args() {
2987   return _popframe_preserved_args;
2988 }
2989 
2990 ByteSize JavaThread::popframe_preserved_args_size() {
2991   return in_ByteSize(_popframe_preserved_args_size);
2992 }
2993 
2994 WordSize JavaThread::popframe_preserved_args_size_in_words() {
2995   int sz = in_bytes(popframe_preserved_args_size());
2996   assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
2997   return in_WordSize(sz / wordSize);
2998 }
2999 
3000 void JavaThread::popframe_free_preserved_args() {
3001   assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3002   FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3003   _popframe_preserved_args = NULL;
3004   _popframe_preserved_args_size = 0;
3005 }
3006 
3007 #ifndef PRODUCT
3008 
3009 void JavaThread::trace_frames() {
3010   tty->print_cr("[Describe stack]");
3011   int frame_no = 1;
3012   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3013     tty->print("  %d. ", frame_no++);
3014     fst.current()->print_value_on(tty, this);
3015     tty->cr();
3016   }
3017 }
3018 
3019 class PrintAndVerifyOopClosure: public OopClosure {
3020  protected:
3021   template <class T> inline void do_oop_work(T* p) {
3022     oop obj = oopDesc::load_decode_heap_oop(p);
3023     if (obj == NULL) return;
3024     tty->print(INTPTR_FORMAT ": ", p);
3025     if (obj->is_oop_or_null()) {
3026       if (obj->is_objArray()) {
3027         tty->print_cr("valid objArray: " INTPTR_FORMAT, (oopDesc*) obj);
3028       } else {
3029         obj->print();
3030       }
3031     } else {
3032       tty->print_cr("invalid oop: " INTPTR_FORMAT, (oopDesc*) obj);
3033     }
3034     tty->cr();
3035   }
3036  public:
3037   virtual void do_oop(oop* p) { do_oop_work(p); }
3038   virtual void do_oop(narrowOop* p)  { do_oop_work(p); }
3039 };
3040 
3041 
3042 static void oops_print(frame* f, const RegisterMap *map) {
3043   PrintAndVerifyOopClosure print;
3044   f->print_value();
3045   f->oops_do(&print, NULL, NULL, (RegisterMap*)map);
3046 }
3047 
3048 // Print our all the locations that contain oops and whether they are
3049 // valid or not.  This useful when trying to find the oldest frame
3050 // where an oop has gone bad since the frame walk is from youngest to
3051 // oldest.
3052 void JavaThread::trace_oops() {
3053   tty->print_cr("[Trace oops]");
3054   frames_do(oops_print);
3055 }
3056 
3057 
3058 #ifdef ASSERT
3059 // Print or validate the layout of stack frames
3060 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3061   ResourceMark rm;
3062   PRESERVE_EXCEPTION_MARK;
3063   FrameValues values;
3064   int frame_no = 0;
3065   for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3066     fst.current()->describe(values, ++frame_no);
3067     if (depth == frame_no) break;
3068   }
3069   if (validate_only) {
3070     values.validate();
3071   } else {
3072     tty->print_cr("[Describe stack layout]");
3073     values.print(this);
3074   }
3075 }
3076 #endif
3077 
3078 void JavaThread::trace_stack_from(vframe* start_vf) {
3079   ResourceMark rm;
3080   int vframe_no = 1;
3081   for (vframe* f = start_vf; f; f = f->sender()) {
3082     if (f->is_java_frame()) {
3083       javaVFrame::cast(f)->print_activation(vframe_no++);
3084     } else {
3085       f->print();
3086     }
3087     if (vframe_no > StackPrintLimit) {
3088       tty->print_cr("...<more frames>...");
3089       return;
3090     }
3091   }
3092 }
3093 
3094 
3095 void JavaThread::trace_stack() {
3096   if (!has_last_Java_frame()) return;
3097   ResourceMark rm;
3098   HandleMark   hm;
3099   RegisterMap reg_map(this);
3100   trace_stack_from(last_java_vframe(&reg_map));
3101 }
3102 
3103 
3104 #endif // PRODUCT
3105 
3106 
3107 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3108   assert(reg_map != NULL, "a map must be given");
3109   frame f = last_frame();
3110   for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3111     if (vf->is_java_frame()) return javaVFrame::cast(vf);
3112   }
3113   return NULL;
3114 }
3115 
3116 
3117 Klass* JavaThread::security_get_caller_class(int depth) {
3118   vframeStream vfst(this);
3119   vfst.security_get_caller_frame(depth);
3120   if (!vfst.at_end()) {
3121     return vfst.method()->method_holder();
3122   }
3123   return NULL;
3124 }
3125 
3126 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3127   assert(thread->is_Compiler_thread(), "must be compiler thread");
3128   CompileBroker::compiler_thread_loop();
3129 }
3130 
3131 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3132   NMethodSweeper::sweeper_loop();
3133 }
3134 
3135 // Create a CompilerThread
3136 CompilerThread::CompilerThread(CompileQueue* queue,
3137                                CompilerCounters* counters)
3138                                : JavaThread(&compiler_thread_entry) {
3139   _env   = NULL;
3140   _log   = NULL;
3141   _task  = NULL;
3142   _queue = queue;
3143   _counters = counters;
3144   _buffer_blob = NULL;
3145   _compiler = NULL;
3146 
3147 #ifndef PRODUCT
3148   _ideal_graph_printer = NULL;
3149 #endif
3150 }
3151 
3152 // Create sweeper thread
3153 CodeCacheSweeperThread::CodeCacheSweeperThread()
3154 : JavaThread(&sweeper_thread_entry) {
3155   _scanned_nmethod = NULL;
3156 }
3157 void CodeCacheSweeperThread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
3158   JavaThread::oops_do(f, cld_f, cf);
3159   if (_scanned_nmethod != NULL && cf != NULL) {
3160     // Safepoints can occur when the sweeper is scanning an nmethod so
3161     // process it here to make sure it isn't unloaded in the middle of
3162     // a scan.
3163     cf->do_code_blob(_scanned_nmethod);
3164   }
3165 }
3166 
3167 
3168 // ======= Threads ========
3169 
3170 // The Threads class links together all active threads, and provides
3171 // operations over all threads.  It is protected by its own Mutex
3172 // lock, which is also used in other contexts to protect thread
3173 // operations from having the thread being operated on from exiting
3174 // and going away unexpectedly (e.g., safepoint synchronization)
3175 
3176 JavaThread* Threads::_thread_list = NULL;
3177 int         Threads::_number_of_threads = 0;
3178 int         Threads::_number_of_non_daemon_threads = 0;
3179 int         Threads::_return_code = 0;
3180 size_t      JavaThread::_stack_size_at_create = 0;
3181 #ifdef ASSERT
3182 bool        Threads::_vm_complete = false;
3183 #endif
3184 
3185 // All JavaThreads
3186 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
3187 
3188 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3189 void Threads::threads_do(ThreadClosure* tc) {
3190   assert_locked_or_safepoint(Threads_lock);
3191   // ALL_JAVA_THREADS iterates through all JavaThreads
3192   ALL_JAVA_THREADS(p) {
3193     tc->do_thread(p);
3194   }
3195   // Someday we could have a table or list of all non-JavaThreads.
3196   // For now, just manually iterate through them.
3197   tc->do_thread(VMThread::vm_thread());
3198   Universe::heap()->gc_threads_do(tc);
3199   WatcherThread *wt = WatcherThread::watcher_thread();
3200   // Strictly speaking, the following NULL check isn't sufficient to make sure
3201   // the data for WatcherThread is still valid upon being examined. However,
3202   // considering that WatchThread terminates when the VM is on the way to
3203   // exit at safepoint, the chance of the above is extremely small. The right
3204   // way to prevent termination of WatcherThread would be to acquire
3205   // Terminator_lock, but we can't do that without violating the lock rank
3206   // checking in some cases.
3207   if (wt != NULL) {
3208     tc->do_thread(wt);
3209   }
3210 
3211   // If CompilerThreads ever become non-JavaThreads, add them here
3212 }
3213 
3214 
3215 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3216   TraceTime timer("Initialize java.lang classes", TraceStartupTime);
3217 
3218   if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3219     create_vm_init_libraries();
3220   }
3221 
3222   initialize_class(vmSymbols::java_lang_String(), CHECK);
3223 
3224   // Initialize java_lang.System (needed before creating the thread)
3225   initialize_class(vmSymbols::java_lang_System(), CHECK);
3226   initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3227   Handle thread_group = create_initial_thread_group(CHECK);
3228   Universe::set_main_thread_group(thread_group());
3229   initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3230   oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3231   main_thread->set_threadObj(thread_object);
3232   // Set thread status to running since main thread has
3233   // been started and running.
3234   java_lang_Thread::set_thread_status(thread_object,
3235                                       java_lang_Thread::RUNNABLE);
3236 
3237   // The VM creates & returns objects of this class. Make sure it's initialized.
3238   initialize_class(vmSymbols::java_lang_Class(), CHECK);
3239 
3240   // The VM preresolves methods to these classes. Make sure that they get initialized
3241   initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3242   initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3243   call_initializeSystemClass(CHECK);
3244 
3245   // get the Java runtime name after java.lang.System is initialized
3246   JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3247   JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3248 
3249   // an instance of OutOfMemory exception has been allocated earlier
3250   initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3251   initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3252   initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3253   initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3254   initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3255   initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3256   initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3257   initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3258 }
3259 
3260 void Threads::initialize_jsr292_core_classes(TRAPS) {
3261   initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3262   initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3263   initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3264 }
3265 
3266 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3267   extern void JDK_Version_init();
3268 
3269   // Check version
3270   if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3271 
3272   // Initialize the output stream module
3273   ostream_init();
3274 
3275   // Process java launcher properties.
3276   Arguments::process_sun_java_launcher_properties(args);
3277 
3278   // Initialize the os module before using TLS
3279   os::init();
3280 
3281   // Initialize system properties.
3282   Arguments::init_system_properties();
3283 
3284   // So that JDK version can be used as a discriminator when parsing arguments
3285   JDK_Version_init();
3286 
3287   // Update/Initialize System properties after JDK version number is known
3288   Arguments::init_version_specific_system_properties();
3289 
3290   // Parse arguments
3291   jint parse_result = Arguments::parse(args);
3292   if (parse_result != JNI_OK) return parse_result;
3293 
3294   os::init_before_ergo();
3295 
3296   jint ergo_result = Arguments::apply_ergo();
3297   if (ergo_result != JNI_OK) return ergo_result;
3298 
3299   if (PauseAtStartup) {
3300     os::pause();
3301   }
3302 
3303   HOTSPOT_VM_INIT_BEGIN();
3304 
3305   // Record VM creation timing statistics
3306   TraceVmCreationTime create_vm_timer;
3307   create_vm_timer.start();
3308 
3309   // Timing (must come after argument parsing)
3310   TraceTime timer("Create VM", TraceStartupTime);
3311 
3312   // Initialize the os module after parsing the args
3313   jint os_init_2_result = os::init_2();
3314   if (os_init_2_result != JNI_OK) return os_init_2_result;
3315 
3316   jint adjust_after_os_result = Arguments::adjust_after_os();
3317   if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3318 
3319   // initialize TLS
3320   ThreadLocalStorage::init();
3321 
3322   // Initialize output stream logging
3323   ostream_init_log();
3324 
3325   // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3326   // Must be before create_vm_init_agents()
3327   if (Arguments::init_libraries_at_startup()) {
3328     convert_vm_init_libraries_to_agents();
3329   }
3330 
3331   // Launch -agentlib/-agentpath and converted -Xrun agents
3332   if (Arguments::init_agents_at_startup()) {
3333     create_vm_init_agents();
3334   }
3335 
3336   // Initialize Threads state
3337   _thread_list = NULL;
3338   _number_of_threads = 0;
3339   _number_of_non_daemon_threads = 0;
3340 
3341   // Initialize global data structures and create system classes in heap
3342   vm_init_globals();
3343 
3344   // Attach the main thread to this os thread
3345   JavaThread* main_thread = new JavaThread();
3346   main_thread->set_thread_state(_thread_in_vm);
3347   // must do this before set_active_handles and initialize_thread_local_storage
3348   // Note: on solaris initialize_thread_local_storage() will (indirectly)
3349   // change the stack size recorded here to one based on the java thread
3350   // stacksize. This adjusted size is what is used to figure the placement
3351   // of the guard pages.
3352   main_thread->record_stack_base_and_size();
3353   main_thread->initialize_thread_local_storage();
3354 
3355   main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3356 
3357   if (!main_thread->set_as_starting_thread()) {
3358     vm_shutdown_during_initialization(
3359                                       "Failed necessary internal allocation. Out of swap space");
3360     delete main_thread;
3361     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3362     return JNI_ENOMEM;
3363   }
3364 
3365   // Enable guard page *after* os::create_main_thread(), otherwise it would
3366   // crash Linux VM, see notes in os_linux.cpp.
3367   main_thread->create_stack_guard_pages();
3368 
3369   // Initialize Java-Level synchronization subsystem
3370   ObjectMonitor::Initialize();
3371 
3372   // Initialize global modules
3373   jint status = init_globals();
3374   if (status != JNI_OK) {
3375     delete main_thread;
3376     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3377     return status;
3378   }
3379 
3380   // Should be done after the heap is fully created
3381   main_thread->cache_global_variables();
3382 
3383   HandleMark hm;
3384 
3385   { MutexLocker mu(Threads_lock);
3386     Threads::add(main_thread);
3387   }
3388 
3389   // Any JVMTI raw monitors entered in onload will transition into
3390   // real raw monitor. VM is setup enough here for raw monitor enter.
3391   JvmtiExport::transition_pending_onload_raw_monitors();
3392 
3393   // Create the VMThread
3394   { TraceTime timer("Start VMThread", TraceStartupTime);
3395     VMThread::create();
3396     Thread* vmthread = VMThread::vm_thread();
3397 
3398     if (!os::create_thread(vmthread, os::vm_thread)) {
3399       vm_exit_during_initialization("Cannot create VM thread. "
3400                                     "Out of system resources.");
3401     }
3402 
3403     // Wait for the VM thread to become ready, and VMThread::run to initialize
3404     // Monitors can have spurious returns, must always check another state flag
3405     {
3406       MutexLocker ml(Notify_lock);
3407       os::start_thread(vmthread);
3408       while (vmthread->active_handles() == NULL) {
3409         Notify_lock->wait();
3410       }
3411     }
3412   }
3413 
3414   assert(Universe::is_fully_initialized(), "not initialized");
3415   if (VerifyDuringStartup) {
3416     // Make sure we're starting with a clean slate.
3417     VM_Verify verify_op;
3418     VMThread::execute(&verify_op);
3419   }
3420 
3421   Thread* THREAD = Thread::current();
3422 
3423   // At this point, the Universe is initialized, but we have not executed
3424   // any byte code.  Now is a good time (the only time) to dump out the
3425   // internal state of the JVM for sharing.
3426   if (DumpSharedSpaces) {
3427     MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3428     ShouldNotReachHere();
3429   }
3430 
3431   // Always call even when there are not JVMTI environments yet, since environments
3432   // may be attached late and JVMTI must track phases of VM execution
3433   JvmtiExport::enter_start_phase();
3434 
3435   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3436   JvmtiExport::post_vm_start();
3437 
3438   initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3439 
3440   // We need this for ClassDataSharing - the initial vm.info property is set
3441   // with the default value of CDS "sharing" which may be reset through
3442   // command line options.
3443   reset_vm_info_property(CHECK_JNI_ERR);
3444 
3445   quicken_jni_functions();
3446 
3447   // Must be run after init_ft which initializes ft_enabled
3448   if (TRACE_INITIALIZE() != JNI_OK) {
3449     vm_exit_during_initialization("Failed to initialize tracing backend");
3450   }
3451 
3452   // Set flag that basic initialization has completed. Used by exceptions and various
3453   // debug stuff, that does not work until all basic classes have been initialized.
3454   set_init_completed();
3455 
3456   Metaspace::post_initialize();
3457 
3458   HOTSPOT_VM_INIT_END();
3459 
3460   // record VM initialization completion time
3461 #if INCLUDE_MANAGEMENT
3462   Management::record_vm_init_completed();
3463 #endif // INCLUDE_MANAGEMENT
3464 
3465   // Compute system loader. Note that this has to occur after set_init_completed, since
3466   // valid exceptions may be thrown in the process.
3467   // Note that we do not use CHECK_0 here since we are inside an EXCEPTION_MARK and
3468   // set_init_completed has just been called, causing exceptions not to be shortcut
3469   // anymore. We call vm_exit_during_initialization directly instead.
3470   SystemDictionary::compute_java_system_loader(CHECK_JNI_ERR);
3471 
3472 #if INCLUDE_ALL_GCS
3473   // Support for ConcurrentMarkSweep. This should be cleaned up
3474   // and better encapsulated. The ugly nested if test would go away
3475   // once things are properly refactored. XXX YSR
3476   if (UseConcMarkSweepGC || UseG1GC) {
3477     if (UseConcMarkSweepGC) {
3478       ConcurrentMarkSweepThread::makeSurrogateLockerThread(CHECK_JNI_ERR);
3479     } else {
3480       ConcurrentMarkThread::makeSurrogateLockerThread(CHECK_JNI_ERR);
3481     }
3482   }
3483 #endif // INCLUDE_ALL_GCS
3484 
3485   // Always call even when there are not JVMTI environments yet, since environments
3486   // may be attached late and JVMTI must track phases of VM execution
3487   JvmtiExport::enter_live_phase();
3488 
3489   // Signal Dispatcher needs to be started before VMInit event is posted
3490   os::signal_init();
3491 
3492   // Start Attach Listener if +StartAttachListener or it can't be started lazily
3493   if (!DisableAttachMechanism) {
3494     AttachListener::vm_start();
3495     if (StartAttachListener || AttachListener::init_at_startup()) {
3496       AttachListener::init();
3497     }
3498   }
3499 
3500   // Launch -Xrun agents
3501   // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3502   // back-end can launch with -Xdebug -Xrunjdwp.
3503   if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3504     create_vm_init_libraries();
3505   }
3506 
3507   // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3508   JvmtiExport::post_vm_initialized();
3509 
3510   if (TRACE_START() != JNI_OK) {
3511     vm_exit_during_initialization("Failed to start tracing backend.");
3512   }
3513 
3514   if (CleanChunkPoolAsync) {
3515     Chunk::start_chunk_pool_cleaner_task();
3516   }
3517 
3518   // initialize compiler(s)
3519 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK)
3520   CompileBroker::compilation_init();
3521 #endif
3522 
3523   // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3524   // It is done after compilers are initialized, because otherwise compilations of
3525   // signature polymorphic MH intrinsics can be missed
3526   // (see SystemDictionary::find_method_handle_intrinsic).
3527   initialize_jsr292_core_classes(CHECK_JNI_ERR);
3528 
3529 #if INCLUDE_MANAGEMENT
3530   Management::initialize(THREAD);
3531 
3532   if (HAS_PENDING_EXCEPTION) {
3533     // management agent fails to start possibly due to
3534     // configuration problem and is responsible for printing
3535     // stack trace if appropriate. Simply exit VM.
3536     vm_exit(1);
3537   }
3538 #endif // INCLUDE_MANAGEMENT
3539 
3540   if (Arguments::has_profile())       FlatProfiler::engage(main_thread, true);
3541   if (MemProfiling)                   MemProfiler::engage();
3542   StatSampler::engage();
3543   if (CheckJNICalls)                  JniPeriodicChecker::engage();
3544 
3545   BiasedLocking::init();
3546 
3547 #if INCLUDE_RTM_OPT
3548   RTMLockingCounters::init();
3549 #endif
3550 
3551   if (JDK_Version::current().post_vm_init_hook_enabled()) {
3552     call_postVMInitHook(THREAD);
3553     // The Java side of PostVMInitHook.run must deal with all
3554     // exceptions and provide means of diagnosis.
3555     if (HAS_PENDING_EXCEPTION) {
3556       CLEAR_PENDING_EXCEPTION;
3557     }
3558   }
3559 
3560   {
3561     MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
3562     // Make sure the watcher thread can be started by WatcherThread::start()
3563     // or by dynamic enrollment.
3564     WatcherThread::make_startable();
3565     // Start up the WatcherThread if there are any periodic tasks
3566     // NOTE:  All PeriodicTasks should be registered by now. If they
3567     //   aren't, late joiners might appear to start slowly (we might
3568     //   take a while to process their first tick).
3569     if (PeriodicTask::num_tasks() > 0) {
3570       WatcherThread::start();
3571     }
3572   }
3573 
3574   create_vm_timer.end();
3575 #ifdef ASSERT
3576   _vm_complete = true;
3577 #endif
3578   return JNI_OK;
3579 }
3580 
3581 // type for the Agent_OnLoad and JVM_OnLoad entry points
3582 extern "C" {
3583   typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3584 }
3585 // Find a command line agent library and return its entry point for
3586 //         -agentlib:  -agentpath:   -Xrun
3587 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3588 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3589                                     const char *on_load_symbols[],
3590                                     size_t num_symbol_entries) {
3591   OnLoadEntry_t on_load_entry = NULL;
3592   void *library = NULL;
3593 
3594   if (!agent->valid()) {
3595     char buffer[JVM_MAXPATHLEN];
3596     char ebuf[1024] = "";
3597     const char *name = agent->name();
3598     const char *msg = "Could not find agent library ";
3599 
3600     // First check to see if agent is statically linked into executable
3601     if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3602       library = agent->os_lib();
3603     } else if (agent->is_absolute_path()) {
3604       library = os::dll_load(name, ebuf, sizeof ebuf);
3605       if (library == NULL) {
3606         const char *sub_msg = " in absolute path, with error: ";
3607         size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3608         char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3609         jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3610         // If we can't find the agent, exit.
3611         vm_exit_during_initialization(buf, NULL);
3612         FREE_C_HEAP_ARRAY(char, buf);
3613       }
3614     } else {
3615       // Try to load the agent from the standard dll directory
3616       if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(),
3617                              name)) {
3618         library = os::dll_load(buffer, ebuf, sizeof ebuf);
3619       }
3620       if (library == NULL) { // Try the local directory
3621         char ns[1] = {0};
3622         if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) {
3623           library = os::dll_load(buffer, ebuf, sizeof ebuf);
3624         }
3625         if (library == NULL) {
3626           const char *sub_msg = " on the library path, with error: ";
3627           size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3628           char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3629           jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3630           // If we can't find the agent, exit.
3631           vm_exit_during_initialization(buf, NULL);
3632           FREE_C_HEAP_ARRAY(char, buf);
3633         }
3634       }
3635     }
3636     agent->set_os_lib(library);
3637     agent->set_valid();
3638   }
3639 
3640   // Find the OnLoad function.
3641   on_load_entry =
3642     CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
3643                                                           false,
3644                                                           on_load_symbols,
3645                                                           num_symbol_entries));
3646   return on_load_entry;
3647 }
3648 
3649 // Find the JVM_OnLoad entry point
3650 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3651   const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3652   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3653 }
3654 
3655 // Find the Agent_OnLoad entry point
3656 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3657   const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3658   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3659 }
3660 
3661 // For backwards compatibility with -Xrun
3662 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3663 // treated like -agentpath:
3664 // Must be called before agent libraries are created
3665 void Threads::convert_vm_init_libraries_to_agents() {
3666   AgentLibrary* agent;
3667   AgentLibrary* next;
3668 
3669   for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3670     next = agent->next();  // cache the next agent now as this agent may get moved off this list
3671     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3672 
3673     // If there is an JVM_OnLoad function it will get called later,
3674     // otherwise see if there is an Agent_OnLoad
3675     if (on_load_entry == NULL) {
3676       on_load_entry = lookup_agent_on_load(agent);
3677       if (on_load_entry != NULL) {
3678         // switch it to the agent list -- so that Agent_OnLoad will be called,
3679         // JVM_OnLoad won't be attempted and Agent_OnUnload will
3680         Arguments::convert_library_to_agent(agent);
3681       } else {
3682         vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3683       }
3684     }
3685   }
3686 }
3687 
3688 // Create agents for -agentlib:  -agentpath:  and converted -Xrun
3689 // Invokes Agent_OnLoad
3690 // Called very early -- before JavaThreads exist
3691 void Threads::create_vm_init_agents() {
3692   extern struct JavaVM_ main_vm;
3693   AgentLibrary* agent;
3694 
3695   JvmtiExport::enter_onload_phase();
3696 
3697   for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3698     OnLoadEntry_t  on_load_entry = lookup_agent_on_load(agent);
3699 
3700     if (on_load_entry != NULL) {
3701       // Invoke the Agent_OnLoad function
3702       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3703       if (err != JNI_OK) {
3704         vm_exit_during_initialization("agent library failed to init", agent->name());
3705       }
3706     } else {
3707       vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
3708     }
3709   }
3710   JvmtiExport::enter_primordial_phase();
3711 }
3712 
3713 extern "C" {
3714   typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
3715 }
3716 
3717 void Threads::shutdown_vm_agents() {
3718   // Send any Agent_OnUnload notifications
3719   const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
3720   size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
3721   extern struct JavaVM_ main_vm;
3722   for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3723 
3724     // Find the Agent_OnUnload function.
3725     Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
3726                                                    os::find_agent_function(agent,
3727                                                    false,
3728                                                    on_unload_symbols,
3729                                                    num_symbol_entries));
3730 
3731     // Invoke the Agent_OnUnload function
3732     if (unload_entry != NULL) {
3733       JavaThread* thread = JavaThread::current();
3734       ThreadToNativeFromVM ttn(thread);
3735       HandleMark hm(thread);
3736       (*unload_entry)(&main_vm);
3737     }
3738   }
3739 }
3740 
3741 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
3742 // Invokes JVM_OnLoad
3743 void Threads::create_vm_init_libraries() {
3744   extern struct JavaVM_ main_vm;
3745   AgentLibrary* agent;
3746 
3747   for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
3748     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3749 
3750     if (on_load_entry != NULL) {
3751       // Invoke the JVM_OnLoad function
3752       JavaThread* thread = JavaThread::current();
3753       ThreadToNativeFromVM ttn(thread);
3754       HandleMark hm(thread);
3755       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3756       if (err != JNI_OK) {
3757         vm_exit_during_initialization("-Xrun library failed to init", agent->name());
3758       }
3759     } else {
3760       vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
3761     }
3762   }
3763 }
3764 
3765 JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) {
3766   assert(Threads_lock->owned_by_self(), "Must hold Threads_lock");
3767 
3768   JavaThread* java_thread = NULL;
3769   // Sequential search for now.  Need to do better optimization later.
3770   for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) {
3771     oop tobj = thread->threadObj();
3772     if (!thread->is_exiting() &&
3773         tobj != NULL &&
3774         java_tid == java_lang_Thread::thread_id(tobj)) {
3775       java_thread = thread;
3776       break;
3777     }
3778   }
3779   return java_thread;
3780 }
3781 
3782 
3783 // Last thread running calls java.lang.Shutdown.shutdown()
3784 void JavaThread::invoke_shutdown_hooks() {
3785   HandleMark hm(this);
3786 
3787   // We could get here with a pending exception, if so clear it now.
3788   if (this->has_pending_exception()) {
3789     this->clear_pending_exception();
3790   }
3791 
3792   EXCEPTION_MARK;
3793   Klass* k =
3794     SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
3795                                       THREAD);
3796   if (k != NULL) {
3797     // SystemDictionary::resolve_or_null will return null if there was
3798     // an exception.  If we cannot load the Shutdown class, just don't
3799     // call Shutdown.shutdown() at all.  This will mean the shutdown hooks
3800     // and finalizers (if runFinalizersOnExit is set) won't be run.
3801     // Note that if a shutdown hook was registered or runFinalizersOnExit
3802     // was called, the Shutdown class would have already been loaded
3803     // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
3804     instanceKlassHandle shutdown_klass (THREAD, k);
3805     JavaValue result(T_VOID);
3806     JavaCalls::call_static(&result,
3807                            shutdown_klass,
3808                            vmSymbols::shutdown_method_name(),
3809                            vmSymbols::void_method_signature(),
3810                            THREAD);
3811   }
3812   CLEAR_PENDING_EXCEPTION;
3813 }
3814 
3815 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
3816 // the program falls off the end of main(). Another VM exit path is through
3817 // vm_exit() when the program calls System.exit() to return a value or when
3818 // there is a serious error in VM. The two shutdown paths are not exactly
3819 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
3820 // and VM_Exit op at VM level.
3821 //
3822 // Shutdown sequence:
3823 //   + Shutdown native memory tracking if it is on
3824 //   + Wait until we are the last non-daemon thread to execute
3825 //     <-- every thing is still working at this moment -->
3826 //   + Call java.lang.Shutdown.shutdown(), which will invoke Java level
3827 //        shutdown hooks, run finalizers if finalization-on-exit
3828 //   + Call before_exit(), prepare for VM exit
3829 //      > run VM level shutdown hooks (they are registered through JVM_OnExit(),
3830 //        currently the only user of this mechanism is File.deleteOnExit())
3831 //      > stop flat profiler, StatSampler, watcher thread, CMS threads,
3832 //        post thread end and vm death events to JVMTI,
3833 //        stop signal thread
3834 //   + Call JavaThread::exit(), it will:
3835 //      > release JNI handle blocks, remove stack guard pages
3836 //      > remove this thread from Threads list
3837 //     <-- no more Java code from this thread after this point -->
3838 //   + Stop VM thread, it will bring the remaining VM to a safepoint and stop
3839 //     the compiler threads at safepoint
3840 //     <-- do not use anything that could get blocked by Safepoint -->
3841 //   + Disable tracing at JNI/JVM barriers
3842 //   + Set _vm_exited flag for threads that are still running native code
3843 //   + Delete this thread
3844 //   + Call exit_globals()
3845 //      > deletes tty
3846 //      > deletes PerfMemory resources
3847 //   + Return to caller
3848 
3849 bool Threads::destroy_vm() {
3850   JavaThread* thread = JavaThread::current();
3851 
3852 #ifdef ASSERT
3853   _vm_complete = false;
3854 #endif
3855   // Wait until we are the last non-daemon thread to execute
3856   { MutexLocker nu(Threads_lock);
3857     while (Threads::number_of_non_daemon_threads() > 1)
3858       // This wait should make safepoint checks, wait without a timeout,
3859       // and wait as a suspend-equivalent condition.
3860       //
3861       // Note: If the FlatProfiler is running and this thread is waiting
3862       // for another non-daemon thread to finish, then the FlatProfiler
3863       // is waiting for the external suspend request on this thread to
3864       // complete. wait_for_ext_suspend_completion() will eventually
3865       // timeout, but that takes time. Making this wait a suspend-
3866       // equivalent condition solves that timeout problem.
3867       //
3868       Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
3869                          Mutex::_as_suspend_equivalent_flag);
3870   }
3871 
3872   // Hang forever on exit if we are reporting an error.
3873   if (ShowMessageBoxOnError && is_error_reported()) {
3874     os::infinite_sleep();
3875   }
3876   os::wait_for_keypress_at_exit();
3877 
3878   // run Java level shutdown hooks
3879   thread->invoke_shutdown_hooks();
3880 
3881   before_exit(thread);
3882 
3883   thread->exit(true);
3884 
3885   // Stop VM thread.
3886   {
3887     // 4945125 The vm thread comes to a safepoint during exit.
3888     // GC vm_operations can get caught at the safepoint, and the
3889     // heap is unparseable if they are caught. Grab the Heap_lock
3890     // to prevent this. The GC vm_operations will not be able to
3891     // queue until after the vm thread is dead. After this point,
3892     // we'll never emerge out of the safepoint before the VM exits.
3893 
3894     MutexLocker ml(Heap_lock);
3895 
3896     VMThread::wait_for_vm_thread_exit();
3897     assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
3898     VMThread::destroy();
3899   }
3900 
3901   // clean up ideal graph printers
3902 #if defined(COMPILER2) && !defined(PRODUCT)
3903   IdealGraphPrinter::clean_up();
3904 #endif
3905 
3906   // Now, all Java threads are gone except daemon threads. Daemon threads
3907   // running Java code or in VM are stopped by the Safepoint. However,
3908   // daemon threads executing native code are still running.  But they
3909   // will be stopped at native=>Java/VM barriers. Note that we can't
3910   // simply kill or suspend them, as it is inherently deadlock-prone.
3911 
3912 #ifndef PRODUCT
3913   // disable function tracing at JNI/JVM barriers
3914   TraceJNICalls = false;
3915   TraceJVMCalls = false;
3916   TraceRuntimeCalls = false;
3917 #endif
3918 
3919   VM_Exit::set_vm_exited();
3920 
3921   notify_vm_shutdown();
3922 
3923   delete thread;
3924 
3925   // exit_globals() will delete tty
3926   exit_globals();
3927 
3928   return true;
3929 }
3930 
3931 
3932 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
3933   if (version == JNI_VERSION_1_1) return JNI_TRUE;
3934   return is_supported_jni_version(version);
3935 }
3936 
3937 
3938 jboolean Threads::is_supported_jni_version(jint version) {
3939   if (version == JNI_VERSION_1_2) return JNI_TRUE;
3940   if (version == JNI_VERSION_1_4) return JNI_TRUE;
3941   if (version == JNI_VERSION_1_6) return JNI_TRUE;
3942   if (version == JNI_VERSION_1_8) return JNI_TRUE;
3943   return JNI_FALSE;
3944 }
3945 
3946 
3947 void Threads::add(JavaThread* p, bool force_daemon) {
3948   // The threads lock must be owned at this point
3949   assert_locked_or_safepoint(Threads_lock);
3950 
3951   // See the comment for this method in thread.hpp for its purpose and
3952   // why it is called here.
3953   p->initialize_queues();
3954   p->set_next(_thread_list);
3955   _thread_list = p;
3956   _number_of_threads++;
3957   oop threadObj = p->threadObj();
3958   bool daemon = true;
3959   // Bootstrapping problem: threadObj can be null for initial
3960   // JavaThread (or for threads attached via JNI)
3961   if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
3962     _number_of_non_daemon_threads++;
3963     daemon = false;
3964   }
3965 
3966   ThreadService::add_thread(p, daemon);
3967 
3968   // Possible GC point.
3969   Events::log(p, "Thread added: " INTPTR_FORMAT, p);
3970 }
3971 
3972 void Threads::remove(JavaThread* p) {
3973   // Extra scope needed for Thread_lock, so we can check
3974   // that we do not remove thread without safepoint code notice
3975   { MutexLocker ml(Threads_lock);
3976 
3977     assert(includes(p), "p must be present");
3978 
3979     JavaThread* current = _thread_list;
3980     JavaThread* prev    = NULL;
3981 
3982     while (current != p) {
3983       prev    = current;
3984       current = current->next();
3985     }
3986 
3987     if (prev) {
3988       prev->set_next(current->next());
3989     } else {
3990       _thread_list = p->next();
3991     }
3992     _number_of_threads--;
3993     oop threadObj = p->threadObj();
3994     bool daemon = true;
3995     if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
3996       _number_of_non_daemon_threads--;
3997       daemon = false;
3998 
3999       // Only one thread left, do a notify on the Threads_lock so a thread waiting
4000       // on destroy_vm will wake up.
4001       if (number_of_non_daemon_threads() == 1) {
4002         Threads_lock->notify_all();
4003       }
4004     }
4005     ThreadService::remove_thread(p, daemon);
4006 
4007     // Make sure that safepoint code disregard this thread. This is needed since
4008     // the thread might mess around with locks after this point. This can cause it
4009     // to do callbacks into the safepoint code. However, the safepoint code is not aware
4010     // of this thread since it is removed from the queue.
4011     p->set_terminated_value();
4012   } // unlock Threads_lock
4013 
4014   // Since Events::log uses a lock, we grab it outside the Threads_lock
4015   Events::log(p, "Thread exited: " INTPTR_FORMAT, p);
4016 }
4017 
4018 // Threads_lock must be held when this is called (or must be called during a safepoint)
4019 bool Threads::includes(JavaThread* p) {
4020   assert(Threads_lock->is_locked(), "sanity check");
4021   ALL_JAVA_THREADS(q) {
4022     if (q == p) {
4023       return true;
4024     }
4025   }
4026   return false;
4027 }
4028 
4029 // Operations on the Threads list for GC.  These are not explicitly locked,
4030 // but the garbage collector must provide a safe context for them to run.
4031 // In particular, these things should never be called when the Threads_lock
4032 // is held by some other thread. (Note: the Safepoint abstraction also
4033 // uses the Threads_lock to guarantee this property. It also makes sure that
4034 // all threads gets blocked when exiting or starting).
4035 
4036 void Threads::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
4037   ALL_JAVA_THREADS(p) {
4038     p->oops_do(f, cld_f, cf);
4039   }
4040   VMThread::vm_thread()->oops_do(f, cld_f, cf);
4041 }
4042 
4043 void Threads::possibly_parallel_oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
4044   // Introduce a mechanism allowing parallel threads to claim threads as
4045   // root groups.  Overhead should be small enough to use all the time,
4046   // even in sequential code.
4047   SharedHeap* sh = SharedHeap::heap();
4048   // Cannot yet substitute active_workers for n_par_threads
4049   // because of G1CollectedHeap::verify() use of
4050   // SharedHeap::process_roots().  n_par_threads == 0 will
4051   // turn off parallelism in process_roots while active_workers
4052   // is being used for parallelism elsewhere.
4053   bool is_par = sh->n_par_threads() > 0;
4054   assert(!is_par ||
4055          (SharedHeap::heap()->n_par_threads() ==
4056          SharedHeap::heap()->workers()->active_workers()), "Mismatch");
4057   int cp = SharedHeap::heap()->strong_roots_parity();
4058   ALL_JAVA_THREADS(p) {
4059     if (p->claim_oops_do(is_par, cp)) {
4060       p->oops_do(f, cld_f, cf);
4061     }
4062   }
4063   VMThread* vmt = VMThread::vm_thread();
4064   if (vmt->claim_oops_do(is_par, cp)) {
4065     vmt->oops_do(f, cld_f, cf);
4066   }
4067 }
4068 
4069 #if INCLUDE_ALL_GCS
4070 // Used by ParallelScavenge
4071 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4072   ALL_JAVA_THREADS(p) {
4073     q->enqueue(new ThreadRootsTask(p));
4074   }
4075   q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4076 }
4077 
4078 // Used by Parallel Old
4079 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4080   ALL_JAVA_THREADS(p) {
4081     q->enqueue(new ThreadRootsMarkingTask(p));
4082   }
4083   q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4084 }
4085 #endif // INCLUDE_ALL_GCS
4086 
4087 void Threads::nmethods_do(CodeBlobClosure* cf) {
4088   ALL_JAVA_THREADS(p) {
4089     p->nmethods_do(cf);
4090   }
4091   VMThread::vm_thread()->nmethods_do(cf);
4092 }
4093 
4094 void Threads::metadata_do(void f(Metadata*)) {
4095   ALL_JAVA_THREADS(p) {
4096     p->metadata_do(f);
4097   }
4098 }
4099 
4100 void Threads::deoptimized_wrt_marked_nmethods() {
4101   ALL_JAVA_THREADS(p) {
4102     p->deoptimized_wrt_marked_nmethods();
4103   }
4104 }
4105 
4106 
4107 // Get count Java threads that are waiting to enter the specified monitor.
4108 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
4109                                                          address monitor,
4110                                                          bool doLock) {
4111   assert(doLock || SafepointSynchronize::is_at_safepoint(),
4112          "must grab Threads_lock or be at safepoint");
4113   GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4114 
4115   int i = 0;
4116   {
4117     MutexLockerEx ml(doLock ? Threads_lock : NULL);
4118     ALL_JAVA_THREADS(p) {
4119       if (p->is_Compiler_thread()) continue;
4120 
4121       address pending = (address)p->current_pending_monitor();
4122       if (pending == monitor) {             // found a match
4123         if (i < count) result->append(p);   // save the first count matches
4124         i++;
4125       }
4126     }
4127   }
4128   return result;
4129 }
4130 
4131 
4132 JavaThread *Threads::owning_thread_from_monitor_owner(address owner,
4133                                                       bool doLock) {
4134   assert(doLock ||
4135          Threads_lock->owned_by_self() ||
4136          SafepointSynchronize::is_at_safepoint(),
4137          "must grab Threads_lock or be at safepoint");
4138 
4139   // NULL owner means not locked so we can skip the search
4140   if (owner == NULL) return NULL;
4141 
4142   {
4143     MutexLockerEx ml(doLock ? Threads_lock : NULL);
4144     ALL_JAVA_THREADS(p) {
4145       // first, see if owner is the address of a Java thread
4146       if (owner == (address)p) return p;
4147     }
4148   }
4149   // Cannot assert on lack of success here since this function may be
4150   // used by code that is trying to report useful problem information
4151   // like deadlock detection.
4152   if (UseHeavyMonitors) return NULL;
4153 
4154   // If we didn't find a matching Java thread and we didn't force use of
4155   // heavyweight monitors, then the owner is the stack address of the
4156   // Lock Word in the owning Java thread's stack.
4157   //
4158   JavaThread* the_owner = NULL;
4159   {
4160     MutexLockerEx ml(doLock ? Threads_lock : NULL);
4161     ALL_JAVA_THREADS(q) {
4162       if (q->is_lock_owned(owner)) {
4163         the_owner = q;
4164         break;
4165       }
4166     }
4167   }
4168   // cannot assert on lack of success here; see above comment
4169   return the_owner;
4170 }
4171 
4172 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4173 void Threads::print_on(outputStream* st, bool print_stacks,
4174                        bool internal_format, bool print_concurrent_locks) {
4175   char buf[32];
4176   st->print_cr("%s", os::local_time_string(buf, sizeof(buf)));
4177 
4178   st->print_cr("Full thread dump %s (%s %s):",
4179                Abstract_VM_Version::vm_name(),
4180                Abstract_VM_Version::vm_release(),
4181                Abstract_VM_Version::vm_info_string());
4182   st->cr();
4183 
4184 #if INCLUDE_ALL_GCS
4185   // Dump concurrent locks
4186   ConcurrentLocksDump concurrent_locks;
4187   if (print_concurrent_locks) {
4188     concurrent_locks.dump_at_safepoint();
4189   }
4190 #endif // INCLUDE_ALL_GCS
4191 
4192   ALL_JAVA_THREADS(p) {
4193     ResourceMark rm;
4194     p->print_on(st);
4195     if (print_stacks) {
4196       if (internal_format) {
4197         p->trace_stack();
4198       } else {
4199         p->print_stack_on(st);
4200       }
4201     }
4202     st->cr();
4203 #if INCLUDE_ALL_GCS
4204     if (print_concurrent_locks) {
4205       concurrent_locks.print_locks_on(p, st);
4206     }
4207 #endif // INCLUDE_ALL_GCS
4208   }
4209 
4210   VMThread::vm_thread()->print_on(st);
4211   st->cr();
4212   Universe::heap()->print_gc_threads_on(st);
4213   WatcherThread* wt = WatcherThread::watcher_thread();
4214   if (wt != NULL) {
4215     wt->print_on(st);
4216     st->cr();
4217   }
4218   CompileBroker::print_compiler_threads_on(st);
4219   st->flush();
4220 }
4221 
4222 // Threads::print_on_error() is called by fatal error handler. It's possible
4223 // that VM is not at safepoint and/or current thread is inside signal handler.
4224 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4225 // memory (even in resource area), it might deadlock the error handler.
4226 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4227                              int buflen) {
4228   bool found_current = false;
4229   st->print_cr("Java Threads: ( => current thread )");
4230   ALL_JAVA_THREADS(thread) {
4231     bool is_current = (current == thread);
4232     found_current = found_current || is_current;
4233 
4234     st->print("%s", is_current ? "=>" : "  ");
4235 
4236     st->print(PTR_FORMAT, thread);
4237     st->print(" ");
4238     thread->print_on_error(st, buf, buflen);
4239     st->cr();
4240   }
4241   st->cr();
4242 
4243   st->print_cr("Other Threads:");
4244   if (VMThread::vm_thread()) {
4245     bool is_current = (current == VMThread::vm_thread());
4246     found_current = found_current || is_current;
4247     st->print("%s", current == VMThread::vm_thread() ? "=>" : "  ");
4248 
4249     st->print(PTR_FORMAT, VMThread::vm_thread());
4250     st->print(" ");
4251     VMThread::vm_thread()->print_on_error(st, buf, buflen);
4252     st->cr();
4253   }
4254   WatcherThread* wt = WatcherThread::watcher_thread();
4255   if (wt != NULL) {
4256     bool is_current = (current == wt);
4257     found_current = found_current || is_current;
4258     st->print("%s", is_current ? "=>" : "  ");
4259 
4260     st->print(PTR_FORMAT, wt);
4261     st->print(" ");
4262     wt->print_on_error(st, buf, buflen);
4263     st->cr();
4264   }
4265   if (!found_current) {
4266     st->cr();
4267     st->print("=>" PTR_FORMAT " (exited) ", current);
4268     current->print_on_error(st, buf, buflen);
4269     st->cr();
4270   }
4271 }
4272 
4273 // Internal SpinLock and Mutex
4274 // Based on ParkEvent
4275 
4276 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4277 //
4278 // We employ SpinLocks _only for low-contention, fixed-length
4279 // short-duration critical sections where we're concerned
4280 // about native mutex_t or HotSpot Mutex:: latency.
4281 // The mux construct provides a spin-then-block mutual exclusion
4282 // mechanism.
4283 //
4284 // Testing has shown that contention on the ListLock guarding gFreeList
4285 // is common.  If we implement ListLock as a simple SpinLock it's common
4286 // for the JVM to devolve to yielding with little progress.  This is true
4287 // despite the fact that the critical sections protected by ListLock are
4288 // extremely short.
4289 //
4290 // TODO-FIXME: ListLock should be of type SpinLock.
4291 // We should make this a 1st-class type, integrated into the lock
4292 // hierarchy as leaf-locks.  Critically, the SpinLock structure
4293 // should have sufficient padding to avoid false-sharing and excessive
4294 // cache-coherency traffic.
4295 
4296 
4297 typedef volatile int SpinLockT;
4298 
4299 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4300   if (Atomic::cmpxchg (1, adr, 0) == 0) {
4301     return;   // normal fast-path return
4302   }
4303 
4304   // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4305   TEVENT(SpinAcquire - ctx);
4306   int ctr = 0;
4307   int Yields = 0;
4308   for (;;) {
4309     while (*adr != 0) {
4310       ++ctr;
4311       if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4312         if (Yields > 5) {
4313           os::naked_short_sleep(1);
4314         } else {
4315           os::naked_yield();
4316           ++Yields;
4317         }
4318       } else {
4319         SpinPause();
4320       }
4321     }
4322     if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4323   }
4324 }
4325 
4326 void Thread::SpinRelease(volatile int * adr) {
4327   assert(*adr != 0, "invariant");
4328   OrderAccess::fence();      // guarantee at least release consistency.
4329   // Roach-motel semantics.
4330   // It's safe if subsequent LDs and STs float "up" into the critical section,
4331   // but prior LDs and STs within the critical section can't be allowed
4332   // to reorder or float past the ST that releases the lock.
4333   // Loads and stores in the critical section - which appear in program
4334   // order before the store that releases the lock - must also appear
4335   // before the store that releases the lock in memory visibility order.
4336   // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4337   // the ST of 0 into the lock-word which releases the lock, so fence
4338   // more than covers this on all platforms.
4339   *adr = 0;
4340 }
4341 
4342 // muxAcquire and muxRelease:
4343 //
4344 // *  muxAcquire and muxRelease support a single-word lock-word construct.
4345 //    The LSB of the word is set IFF the lock is held.
4346 //    The remainder of the word points to the head of a singly-linked list
4347 //    of threads blocked on the lock.
4348 //
4349 // *  The current implementation of muxAcquire-muxRelease uses its own
4350 //    dedicated Thread._MuxEvent instance.  If we're interested in
4351 //    minimizing the peak number of extant ParkEvent instances then
4352 //    we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4353 //    as certain invariants were satisfied.  Specifically, care would need
4354 //    to be taken with regards to consuming unpark() "permits".
4355 //    A safe rule of thumb is that a thread would never call muxAcquire()
4356 //    if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4357 //    park().  Otherwise the _ParkEvent park() operation in muxAcquire() could
4358 //    consume an unpark() permit intended for monitorenter, for instance.
4359 //    One way around this would be to widen the restricted-range semaphore
4360 //    implemented in park().  Another alternative would be to provide
4361 //    multiple instances of the PlatformEvent() for each thread.  One
4362 //    instance would be dedicated to muxAcquire-muxRelease, for instance.
4363 //
4364 // *  Usage:
4365 //    -- Only as leaf locks
4366 //    -- for short-term locking only as muxAcquire does not perform
4367 //       thread state transitions.
4368 //
4369 // Alternatives:
4370 // *  We could implement muxAcquire and muxRelease with MCS or CLH locks
4371 //    but with parking or spin-then-park instead of pure spinning.
4372 // *  Use Taura-Oyama-Yonenzawa locks.
4373 // *  It's possible to construct a 1-0 lock if we encode the lockword as
4374 //    (List,LockByte).  Acquire will CAS the full lockword while Release
4375 //    will STB 0 into the LockByte.  The 1-0 scheme admits stranding, so
4376 //    acquiring threads use timers (ParkTimed) to detect and recover from
4377 //    the stranding window.  Thread/Node structures must be aligned on 256-byte
4378 //    boundaries by using placement-new.
4379 // *  Augment MCS with advisory back-link fields maintained with CAS().
4380 //    Pictorially:  LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4381 //    The validity of the backlinks must be ratified before we trust the value.
4382 //    If the backlinks are invalid the exiting thread must back-track through the
4383 //    the forward links, which are always trustworthy.
4384 // *  Add a successor indication.  The LockWord is currently encoded as
4385 //    (List, LOCKBIT:1).  We could also add a SUCCBIT or an explicit _succ variable
4386 //    to provide the usual futile-wakeup optimization.
4387 //    See RTStt for details.
4388 // *  Consider schedctl.sc_nopreempt to cover the critical section.
4389 //
4390 
4391 
4392 typedef volatile intptr_t MutexT;      // Mux Lock-word
4393 enum MuxBits { LOCKBIT = 1 };
4394 
4395 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4396   intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4397   if (w == 0) return;
4398   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4399     return;
4400   }
4401 
4402   TEVENT(muxAcquire - Contention);
4403   ParkEvent * const Self = Thread::current()->_MuxEvent;
4404   assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4405   for (;;) {
4406     int its = (os::is_MP() ? 100 : 0) + 1;
4407 
4408     // Optional spin phase: spin-then-park strategy
4409     while (--its >= 0) {
4410       w = *Lock;
4411       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4412         return;
4413       }
4414     }
4415 
4416     Self->reset();
4417     Self->OnList = intptr_t(Lock);
4418     // The following fence() isn't _strictly necessary as the subsequent
4419     // CAS() both serializes execution and ratifies the fetched *Lock value.
4420     OrderAccess::fence();
4421     for (;;) {
4422       w = *Lock;
4423       if ((w & LOCKBIT) == 0) {
4424         if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4425           Self->OnList = 0;   // hygiene - allows stronger asserts
4426           return;
4427         }
4428         continue;      // Interference -- *Lock changed -- Just retry
4429       }
4430       assert(w & LOCKBIT, "invariant");
4431       Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4432       if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4433     }
4434 
4435     while (Self->OnList != 0) {
4436       Self->park();
4437     }
4438   }
4439 }
4440 
4441 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4442   intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4443   if (w == 0) return;
4444   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4445     return;
4446   }
4447 
4448   TEVENT(muxAcquire - Contention);
4449   ParkEvent * ReleaseAfter = NULL;
4450   if (ev == NULL) {
4451     ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4452   }
4453   assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4454   for (;;) {
4455     guarantee(ev->OnList == 0, "invariant");
4456     int its = (os::is_MP() ? 100 : 0) + 1;
4457 
4458     // Optional spin phase: spin-then-park strategy
4459     while (--its >= 0) {
4460       w = *Lock;
4461       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4462         if (ReleaseAfter != NULL) {
4463           ParkEvent::Release(ReleaseAfter);
4464         }
4465         return;
4466       }
4467     }
4468 
4469     ev->reset();
4470     ev->OnList = intptr_t(Lock);
4471     // The following fence() isn't _strictly necessary as the subsequent
4472     // CAS() both serializes execution and ratifies the fetched *Lock value.
4473     OrderAccess::fence();
4474     for (;;) {
4475       w = *Lock;
4476       if ((w & LOCKBIT) == 0) {
4477         if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4478           ev->OnList = 0;
4479           // We call ::Release while holding the outer lock, thus
4480           // artificially lengthening the critical section.
4481           // Consider deferring the ::Release() until the subsequent unlock(),
4482           // after we've dropped the outer lock.
4483           if (ReleaseAfter != NULL) {
4484             ParkEvent::Release(ReleaseAfter);
4485           }
4486           return;
4487         }
4488         continue;      // Interference -- *Lock changed -- Just retry
4489       }
4490       assert(w & LOCKBIT, "invariant");
4491       ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4492       if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4493     }
4494 
4495     while (ev->OnList != 0) {
4496       ev->park();
4497     }
4498   }
4499 }
4500 
4501 // Release() must extract a successor from the list and then wake that thread.
4502 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4503 // similar to that used by ParkEvent::Allocate() and ::Release().  DMR-based
4504 // Release() would :
4505 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4506 // (B) Extract a successor from the private list "in-hand"
4507 // (C) attempt to CAS() the residual back into *Lock over null.
4508 //     If there were any newly arrived threads and the CAS() would fail.
4509 //     In that case Release() would detach the RATs, re-merge the list in-hand
4510 //     with the RATs and repeat as needed.  Alternately, Release() might
4511 //     detach and extract a successor, but then pass the residual list to the wakee.
4512 //     The wakee would be responsible for reattaching and remerging before it
4513 //     competed for the lock.
4514 //
4515 // Both "pop" and DMR are immune from ABA corruption -- there can be
4516 // multiple concurrent pushers, but only one popper or detacher.
4517 // This implementation pops from the head of the list.  This is unfair,
4518 // but tends to provide excellent throughput as hot threads remain hot.
4519 // (We wake recently run threads first).
4520 //
4521 // All paths through muxRelease() will execute a CAS.
4522 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4523 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4524 // executed within the critical section are complete and globally visible before the
4525 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4526 void Thread::muxRelease(volatile intptr_t * Lock)  {
4527   for (;;) {
4528     const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT);
4529     assert(w & LOCKBIT, "invariant");
4530     if (w == LOCKBIT) return;
4531     ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4532     assert(List != NULL, "invariant");
4533     assert(List->OnList == intptr_t(Lock), "invariant");
4534     ParkEvent * const nxt = List->ListNext;
4535     guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4536 
4537     // The following CAS() releases the lock and pops the head element.
4538     // The CAS() also ratifies the previously fetched lock-word value.
4539     if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4540       continue;
4541     }
4542     List->OnList = 0;
4543     OrderAccess::fence();
4544     List->unpark();
4545     return;
4546   }
4547 }
4548 
4549 
4550 void Threads::verify() {
4551   ALL_JAVA_THREADS(p) {
4552     p->verify();
4553   }
4554   VMThread* thread = VMThread::vm_thread();
4555   if (thread != NULL) thread->verify();
4556 }