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 "gc/shared/gcLocker.inline.hpp"
  34 #include "gc/shared/workgroup.hpp"
  35 #include "interpreter/interpreter.hpp"
  36 #include "interpreter/linkResolver.hpp"
  37 #include "interpreter/oopMapCache.hpp"
  38 #include "jvmtifiles/jvmtiEnv.hpp"
  39 #include "memory/metaspaceShared.hpp"
  40 #include "memory/oopFactory.hpp"
  41 #include "memory/universe.inline.hpp"
  42 #include "oops/instanceKlass.hpp"
  43 #include "oops/objArrayOop.hpp"
  44 #include "oops/oop.inline.hpp"
  45 #include "oops/symbol.hpp"
  46 #include "oops/verifyOopClosure.hpp"
  47 #include "prims/jvm_misc.hpp"
  48 #include "prims/jvmtiExport.hpp"
  49 #include "prims/jvmtiThreadState.hpp"
  50 #include "prims/privilegedStack.hpp"
  51 #include "runtime/arguments.hpp"
  52 #include "runtime/atomic.inline.hpp"
  53 #include "runtime/biasedLocking.hpp"
  54 #include "runtime/deoptimization.hpp"
  55 #include "runtime/fprofiler.hpp"
  56 #include "runtime/frame.inline.hpp"
  57 #include "runtime/globals.hpp"
  58 #include "runtime/init.hpp"
  59 #include "runtime/interfaceSupport.hpp"
  60 #include "runtime/java.hpp"
  61 #include "runtime/javaCalls.hpp"
  62 #include "runtime/jniPeriodicChecker.hpp"
  63 #include "runtime/memprofiler.hpp"
  64 #include "runtime/mutexLocker.hpp"
  65 #include "runtime/objectMonitor.hpp"
  66 #include "runtime/orderAccess.inline.hpp"
  67 #include "runtime/osThread.hpp"
  68 #include "runtime/safepoint.hpp"
  69 #include "runtime/sharedRuntime.hpp"
  70 #include "runtime/statSampler.hpp"
  71 #include "runtime/stubRoutines.hpp"
  72 #include "runtime/sweeper.hpp"
  73 #include "runtime/task.hpp"
  74 #include "runtime/thread.inline.hpp"
  75 #include "runtime/threadCritical.hpp"
  76 #include "runtime/threadLocalStorage.hpp"
  77 #include "runtime/vframe.hpp"
  78 #include "runtime/vframeArray.hpp"
  79 #include "runtime/vframe_hp.hpp"
  80 #include "runtime/vmThread.hpp"
  81 #include "runtime/vm_operations.hpp"
  82 #include "runtime/vm_version.hpp"
  83 #include "services/attachListener.hpp"
  84 #include "services/management.hpp"
  85 #include "services/memTracker.hpp"
  86 #include "services/threadService.hpp"
  87 #include "trace/traceMacros.hpp"
  88 #include "trace/tracing.hpp"
  89 #include "utilities/defaultStream.hpp"
  90 #include "utilities/dtrace.hpp"
  91 #include "utilities/events.hpp"
  92 #include "utilities/macros.hpp"
  93 #include "utilities/preserveException.hpp"
  94 #if INCLUDE_ALL_GCS
  95 #include "gc/cms/concurrentMarkSweepThread.hpp"
  96 #include "gc/g1/concurrentMarkThread.inline.hpp"
  97 #include "gc/parallel/pcTasks.hpp"
  98 #endif // INCLUDE_ALL_GCS
  99 #ifdef COMPILER1
 100 #include "c1/c1_Compiler.hpp"
 101 #endif
 102 #ifdef COMPILER2
 103 #include "opto/c2compiler.hpp"
 104 #include "opto/idealGraphPrinter.hpp"
 105 #endif
 106 #if INCLUDE_RTM_OPT
 107 #include "runtime/rtmLocking.hpp"
 108 #endif
 109 
 110 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
 111 
 112 #ifdef DTRACE_ENABLED
 113 
 114 // Only bother with this argument setup if dtrace is available
 115 
 116   #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
 117   #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
 118 
 119   #define DTRACE_THREAD_PROBE(probe, javathread)                           \
 120     {                                                                      \
 121       ResourceMark rm(this);                                               \
 122       int len = 0;                                                         \
 123       const char* name = (javathread)->get_thread_name();                  \
 124       len = strlen(name);                                                  \
 125       HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */               \
 126         (char *) name, len,                                                \
 127         java_lang_Thread::thread_id((javathread)->threadObj()),            \
 128         (uintptr_t) (javathread)->osthread()->thread_id(),                 \
 129         java_lang_Thread::is_daemon((javathread)->threadObj()));           \
 130     }
 131 
 132 #else //  ndef DTRACE_ENABLED
 133 
 134   #define DTRACE_THREAD_PROBE(probe, javathread)
 135 
 136 #endif // ndef DTRACE_ENABLED
 137 
 138 
 139 // Class hierarchy
 140 // - Thread
 141 //   - VMThread
 142 //   - WatcherThread
 143 //   - ConcurrentMarkSweepThread
 144 //   - JavaThread
 145 //     - CompilerThread
 146 
 147 // ======= Thread ========
 148 // Support for forcing alignment of thread objects for biased locking
 149 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
 150   if (UseBiasedLocking) {
 151     const int alignment = markOopDesc::biased_lock_alignment;
 152     size_t aligned_size = size + (alignment - sizeof(intptr_t));
 153     void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
 154                                           : AllocateHeap(aligned_size, flags, CURRENT_PC,
 155                                                          AllocFailStrategy::RETURN_NULL);
 156     void* aligned_addr     = (void*) align_size_up((intptr_t) real_malloc_addr, alignment);
 157     assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
 158            ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
 159            "JavaThread alignment code overflowed allocated storage");
 160     if (TraceBiasedLocking) {
 161       if (aligned_addr != real_malloc_addr) {
 162         tty->print_cr("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
 163                       real_malloc_addr, aligned_addr);
 164       }
 165     }
 166     ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
 167     return aligned_addr;
 168   } else {
 169     return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
 170                        : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
 171   }
 172 }
 173 
 174 void Thread::operator delete(void* p) {
 175   if (UseBiasedLocking) {
 176     void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;
 177     FreeHeap(real_malloc_addr);
 178   } else {
 179     FreeHeap(p);
 180   }
 181 }
 182 
 183 
 184 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
 185 // JavaThread
 186 
 187 
 188 Thread::Thread() {
 189   // stack and get_thread
 190   set_stack_base(NULL);
 191   set_stack_size(0);
 192   set_self_raw_id(0);
 193   set_lgrp_id(-1);
 194   DEBUG_ONLY(clear_suspendible_thread();)
 195 
 196   // allocated data structures
 197   set_osthread(NULL);
 198   set_resource_area(new (mtThread)ResourceArea());
 199   DEBUG_ONLY(_current_resource_mark = NULL;)
 200   set_handle_area(new (mtThread) HandleArea(NULL));
 201   set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
 202   set_active_handles(NULL);
 203   set_free_handle_block(NULL);
 204   set_last_handle_mark(NULL);
 205 
 206   // This initial value ==> never claimed.
 207   _oops_do_parity = 0;
 208 
 209   // the handle mark links itself to last_handle_mark
 210   new HandleMark(this);
 211 
 212   // plain initialization
 213   debug_only(_owned_locks = NULL;)
 214   debug_only(_allow_allocation_count = 0;)
 215   NOT_PRODUCT(_allow_safepoint_count = 0;)
 216   NOT_PRODUCT(_skip_gcalot = false;)
 217   _jvmti_env_iteration_count = 0;
 218   set_allocated_bytes(0);
 219   _vm_operation_started_count = 0;
 220   _vm_operation_completed_count = 0;
 221   _current_pending_monitor = NULL;
 222   _current_pending_monitor_is_from_java = true;
 223   _current_waiting_monitor = NULL;
 224   _num_nested_signal = 0;
 225   omFreeList = NULL;
 226   omFreeCount = 0;
 227   omFreeProvision = 32;
 228   omInUseList = NULL;
 229   omInUseCount = 0;
 230 
 231 #ifdef ASSERT
 232   _visited_for_critical_count = false;
 233 #endif
 234 
 235   _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
 236                          Monitor::_safepoint_check_sometimes);
 237   _suspend_flags = 0;
 238 
 239   // thread-specific hashCode stream generator state - Marsaglia shift-xor form
 240   _hashStateX = os::random();
 241   _hashStateY = 842502087;
 242   _hashStateZ = 0x8767;    // (int)(3579807591LL & 0xffff) ;
 243   _hashStateW = 273326509;
 244 
 245   _OnTrap   = 0;
 246   _schedctl = NULL;
 247   _Stalled  = 0;
 248   _TypeTag  = 0x2BAD;
 249 
 250   // Many of the following fields are effectively final - immutable
 251   // Note that nascent threads can't use the Native Monitor-Mutex
 252   // construct until the _MutexEvent is initialized ...
 253   // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
 254   // we might instead use a stack of ParkEvents that we could provision on-demand.
 255   // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
 256   // and ::Release()
 257   _ParkEvent   = ParkEvent::Allocate(this);
 258   _SleepEvent  = ParkEvent::Allocate(this);
 259   _MutexEvent  = ParkEvent::Allocate(this);
 260   _MuxEvent    = ParkEvent::Allocate(this);
 261 
 262 #ifdef CHECK_UNHANDLED_OOPS
 263   if (CheckUnhandledOops) {
 264     _unhandled_oops = new UnhandledOops(this);
 265   }
 266 #endif // CHECK_UNHANDLED_OOPS
 267 #ifdef ASSERT
 268   if (UseBiasedLocking) {
 269     assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
 270     assert(this == _real_malloc_address ||
 271            this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment),
 272            "bug in forced alignment of thread objects");
 273   }
 274 #endif // ASSERT
 275 }
 276 
 277 // Non-inlined version to be used where thread.inline.hpp shouldn't be included.
 278 Thread* Thread::current_noinline() {
 279   return Thread::current();
 280 }
 281 
 282 void Thread::initialize_thread_local_storage() {
 283   // Note: Make sure this method only calls
 284   // non-blocking operations. Otherwise, it might not work
 285   // with the thread-startup/safepoint interaction.
 286 
 287   // During Java thread startup, safepoint code should allow this
 288   // method to complete because it may need to allocate memory to
 289   // store information for the new thread.
 290 
 291   // initialize structure dependent on thread local storage
 292   ThreadLocalStorage::set_thread(this);
 293 }
 294 
 295 void Thread::record_stack_base_and_size() {
 296   set_stack_base(os::current_stack_base());
 297   set_stack_size(os::current_stack_size());
 298   if (is_Java_thread()) {
 299     ((JavaThread*) this)->set_stack_overflow_limit();
 300   }
 301   // CR 7190089: on Solaris, primordial thread's stack is adjusted
 302   // in initialize_thread(). Without the adjustment, stack size is
 303   // incorrect if stack is set to unlimited (ulimit -s unlimited).
 304   // So far, only Solaris has real implementation of initialize_thread().
 305   //
 306   // set up any platform-specific state.
 307   os::initialize_thread(this);
 308 
 309 #if INCLUDE_NMT
 310   // record thread's native stack, stack grows downward
 311   address stack_low_addr = stack_base() - stack_size();
 312   MemTracker::record_thread_stack(stack_low_addr, stack_size());
 313 #endif // INCLUDE_NMT
 314 }
 315 
 316 
 317 Thread::~Thread() {
 318   // Reclaim the objectmonitors from the omFreeList of the moribund thread.
 319   ObjectSynchronizer::omFlush(this);
 320 
 321   EVENT_THREAD_DESTRUCT(this);
 322 
 323   // stack_base can be NULL if the thread is never started or exited before
 324   // record_stack_base_and_size called. Although, we would like to ensure
 325   // that all started threads do call record_stack_base_and_size(), there is
 326   // not proper way to enforce that.
 327 #if INCLUDE_NMT
 328   if (_stack_base != NULL) {
 329     address low_stack_addr = stack_base() - stack_size();
 330     MemTracker::release_thread_stack(low_stack_addr, stack_size());
 331 #ifdef ASSERT
 332     set_stack_base(NULL);
 333 #endif
 334   }
 335 #endif // INCLUDE_NMT
 336 
 337   // deallocate data structures
 338   delete resource_area();
 339   // since the handle marks are using the handle area, we have to deallocated the root
 340   // handle mark before deallocating the thread's handle area,
 341   assert(last_handle_mark() != NULL, "check we have an element");
 342   delete last_handle_mark();
 343   assert(last_handle_mark() == NULL, "check we have reached the end");
 344 
 345   // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
 346   // We NULL out the fields for good hygiene.
 347   ParkEvent::Release(_ParkEvent); _ParkEvent   = NULL;
 348   ParkEvent::Release(_SleepEvent); _SleepEvent  = NULL;
 349   ParkEvent::Release(_MutexEvent); _MutexEvent  = NULL;
 350   ParkEvent::Release(_MuxEvent); _MuxEvent    = NULL;
 351 
 352   delete handle_area();
 353   delete metadata_handles();
 354 
 355   // osthread() can be NULL, if creation of thread failed.
 356   if (osthread() != NULL) os::free_thread(osthread());
 357 
 358   delete _SR_lock;
 359 
 360   // clear thread local storage if the Thread is deleting itself
 361   if (this == Thread::current()) {
 362     ThreadLocalStorage::set_thread(NULL);
 363   } else {
 364     // In the case where we're not the current thread, invalidate all the
 365     // caches in case some code tries to get the current thread or the
 366     // thread that was destroyed, and gets stale information.
 367     ThreadLocalStorage::invalidate_all();
 368   }
 369   CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
 370 }
 371 
 372 // NOTE: dummy function for assertion purpose.
 373 void Thread::run() {
 374   ShouldNotReachHere();
 375 }
 376 
 377 #ifdef ASSERT
 378 // Private method to check for dangling thread pointer
 379 void check_for_dangling_thread_pointer(Thread *thread) {
 380   assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
 381          "possibility of dangling Thread pointer");
 382 }
 383 #endif
 384 
 385 ThreadPriority Thread::get_priority(const Thread* const thread) {
 386   ThreadPriority priority;
 387   // Can return an error!
 388   (void)os::get_priority(thread, priority);
 389   assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
 390   return priority;
 391 }
 392 
 393 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
 394   debug_only(check_for_dangling_thread_pointer(thread);)
 395   // Can return an error!
 396   (void)os::set_priority(thread, priority);
 397 }
 398 
 399 
 400 void Thread::start(Thread* thread) {
 401   // Start is different from resume in that its safety is guaranteed by context or
 402   // being called from a Java method synchronized on the Thread object.
 403   if (!DisableStartThread) {
 404     if (thread->is_Java_thread()) {
 405       // Initialize the thread state to RUNNABLE before starting this thread.
 406       // Can not set it after the thread started because we do not know the
 407       // exact thread state at that time. It could be in MONITOR_WAIT or
 408       // in SLEEPING or some other state.
 409       java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
 410                                           java_lang_Thread::RUNNABLE);
 411     }
 412     os::start_thread(thread);
 413   }
 414 }
 415 
 416 // Enqueue a VM_Operation to do the job for us - sometime later
 417 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
 418   VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
 419   VMThread::execute(vm_stop);
 420 }
 421 
 422 
 423 // Check if an external suspend request has completed (or has been
 424 // cancelled). Returns true if the thread is externally suspended and
 425 // false otherwise.
 426 //
 427 // The bits parameter returns information about the code path through
 428 // the routine. Useful for debugging:
 429 //
 430 // set in is_ext_suspend_completed():
 431 // 0x00000001 - routine was entered
 432 // 0x00000010 - routine return false at end
 433 // 0x00000100 - thread exited (return false)
 434 // 0x00000200 - suspend request cancelled (return false)
 435 // 0x00000400 - thread suspended (return true)
 436 // 0x00001000 - thread is in a suspend equivalent state (return true)
 437 // 0x00002000 - thread is native and walkable (return true)
 438 // 0x00004000 - thread is native_trans and walkable (needed retry)
 439 //
 440 // set in wait_for_ext_suspend_completion():
 441 // 0x00010000 - routine was entered
 442 // 0x00020000 - suspend request cancelled before loop (return false)
 443 // 0x00040000 - thread suspended before loop (return true)
 444 // 0x00080000 - suspend request cancelled in loop (return false)
 445 // 0x00100000 - thread suspended in loop (return true)
 446 // 0x00200000 - suspend not completed during retry loop (return false)
 447 
 448 // Helper class for tracing suspend wait debug bits.
 449 //
 450 // 0x00000100 indicates that the target thread exited before it could
 451 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
 452 // 0x00080000 each indicate a cancelled suspend request so they don't
 453 // count as wait failures either.
 454 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
 455 
 456 class TraceSuspendDebugBits : public StackObj {
 457  private:
 458   JavaThread * jt;
 459   bool         is_wait;
 460   bool         called_by_wait;  // meaningful when !is_wait
 461   uint32_t *   bits;
 462 
 463  public:
 464   TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
 465                         uint32_t *_bits) {
 466     jt             = _jt;
 467     is_wait        = _is_wait;
 468     called_by_wait = _called_by_wait;
 469     bits           = _bits;
 470   }
 471 
 472   ~TraceSuspendDebugBits() {
 473     if (!is_wait) {
 474 #if 1
 475       // By default, don't trace bits for is_ext_suspend_completed() calls.
 476       // That trace is very chatty.
 477       return;
 478 #else
 479       if (!called_by_wait) {
 480         // If tracing for is_ext_suspend_completed() is enabled, then only
 481         // trace calls to it from wait_for_ext_suspend_completion()
 482         return;
 483       }
 484 #endif
 485     }
 486 
 487     if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
 488       if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
 489         MutexLocker ml(Threads_lock);  // needed for get_thread_name()
 490         ResourceMark rm;
 491 
 492         tty->print_cr(
 493                       "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
 494                       jt->get_thread_name(), *bits);
 495 
 496         guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
 497       }
 498     }
 499   }
 500 };
 501 #undef DEBUG_FALSE_BITS
 502 
 503 
 504 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
 505                                           uint32_t *bits) {
 506   TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
 507 
 508   bool did_trans_retry = false;  // only do thread_in_native_trans retry once
 509   bool do_trans_retry;           // flag to force the retry
 510 
 511   *bits |= 0x00000001;
 512 
 513   do {
 514     do_trans_retry = false;
 515 
 516     if (is_exiting()) {
 517       // Thread is in the process of exiting. This is always checked
 518       // first to reduce the risk of dereferencing a freed JavaThread.
 519       *bits |= 0x00000100;
 520       return false;
 521     }
 522 
 523     if (!is_external_suspend()) {
 524       // Suspend request is cancelled. This is always checked before
 525       // is_ext_suspended() to reduce the risk of a rogue resume
 526       // confusing the thread that made the suspend request.
 527       *bits |= 0x00000200;
 528       return false;
 529     }
 530 
 531     if (is_ext_suspended()) {
 532       // thread is suspended
 533       *bits |= 0x00000400;
 534       return true;
 535     }
 536 
 537     // Now that we no longer do hard suspends of threads running
 538     // native code, the target thread can be changing thread state
 539     // while we are in this routine:
 540     //
 541     //   _thread_in_native -> _thread_in_native_trans -> _thread_blocked
 542     //
 543     // We save a copy of the thread state as observed at this moment
 544     // and make our decision about suspend completeness based on the
 545     // copy. This closes the race where the thread state is seen as
 546     // _thread_in_native_trans in the if-thread_blocked check, but is
 547     // seen as _thread_blocked in if-thread_in_native_trans check.
 548     JavaThreadState save_state = thread_state();
 549 
 550     if (save_state == _thread_blocked && is_suspend_equivalent()) {
 551       // If the thread's state is _thread_blocked and this blocking
 552       // condition is known to be equivalent to a suspend, then we can
 553       // consider the thread to be externally suspended. This means that
 554       // the code that sets _thread_blocked has been modified to do
 555       // self-suspension if the blocking condition releases. We also
 556       // used to check for CONDVAR_WAIT here, but that is now covered by
 557       // the _thread_blocked with self-suspension check.
 558       //
 559       // Return true since we wouldn't be here unless there was still an
 560       // external suspend request.
 561       *bits |= 0x00001000;
 562       return true;
 563     } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
 564       // Threads running native code will self-suspend on native==>VM/Java
 565       // transitions. If its stack is walkable (should always be the case
 566       // unless this function is called before the actual java_suspend()
 567       // call), then the wait is done.
 568       *bits |= 0x00002000;
 569       return true;
 570     } else if (!called_by_wait && !did_trans_retry &&
 571                save_state == _thread_in_native_trans &&
 572                frame_anchor()->walkable()) {
 573       // The thread is transitioning from thread_in_native to another
 574       // thread state. check_safepoint_and_suspend_for_native_trans()
 575       // will force the thread to self-suspend. If it hasn't gotten
 576       // there yet we may have caught the thread in-between the native
 577       // code check above and the self-suspend. Lucky us. If we were
 578       // called by wait_for_ext_suspend_completion(), then it
 579       // will be doing the retries so we don't have to.
 580       //
 581       // Since we use the saved thread state in the if-statement above,
 582       // there is a chance that the thread has already transitioned to
 583       // _thread_blocked by the time we get here. In that case, we will
 584       // make a single unnecessary pass through the logic below. This
 585       // doesn't hurt anything since we still do the trans retry.
 586 
 587       *bits |= 0x00004000;
 588 
 589       // Once the thread leaves thread_in_native_trans for another
 590       // thread state, we break out of this retry loop. We shouldn't
 591       // need this flag to prevent us from getting back here, but
 592       // sometimes paranoia is good.
 593       did_trans_retry = true;
 594 
 595       // We wait for the thread to transition to a more usable state.
 596       for (int i = 1; i <= SuspendRetryCount; i++) {
 597         // We used to do an "os::yield_all(i)" call here with the intention
 598         // that yielding would increase on each retry. However, the parameter
 599         // is ignored on Linux which means the yield didn't scale up. Waiting
 600         // on the SR_lock below provides a much more predictable scale up for
 601         // the delay. It also provides a simple/direct point to check for any
 602         // safepoint requests from the VMThread
 603 
 604         // temporarily drops SR_lock while doing wait with safepoint check
 605         // (if we're a JavaThread - the WatcherThread can also call this)
 606         // and increase delay with each retry
 607         SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 608 
 609         // check the actual thread state instead of what we saved above
 610         if (thread_state() != _thread_in_native_trans) {
 611           // the thread has transitioned to another thread state so
 612           // try all the checks (except this one) one more time.
 613           do_trans_retry = true;
 614           break;
 615         }
 616       } // end retry loop
 617 
 618 
 619     }
 620   } while (do_trans_retry);
 621 
 622   *bits |= 0x00000010;
 623   return false;
 624 }
 625 
 626 // Wait for an external suspend request to complete (or be cancelled).
 627 // Returns true if the thread is externally suspended and false otherwise.
 628 //
 629 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
 630                                                  uint32_t *bits) {
 631   TraceSuspendDebugBits tsdb(this, true /* is_wait */,
 632                              false /* !called_by_wait */, bits);
 633 
 634   // local flag copies to minimize SR_lock hold time
 635   bool is_suspended;
 636   bool pending;
 637   uint32_t reset_bits;
 638 
 639   // set a marker so is_ext_suspend_completed() knows we are the caller
 640   *bits |= 0x00010000;
 641 
 642   // We use reset_bits to reinitialize the bits value at the top of
 643   // each retry loop. This allows the caller to make use of any
 644   // unused bits for their own marking purposes.
 645   reset_bits = *bits;
 646 
 647   {
 648     MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
 649     is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 650                                             delay, bits);
 651     pending = is_external_suspend();
 652   }
 653   // must release SR_lock to allow suspension to complete
 654 
 655   if (!pending) {
 656     // A cancelled suspend request is the only false return from
 657     // is_ext_suspend_completed() that keeps us from entering the
 658     // retry loop.
 659     *bits |= 0x00020000;
 660     return false;
 661   }
 662 
 663   if (is_suspended) {
 664     *bits |= 0x00040000;
 665     return true;
 666   }
 667 
 668   for (int i = 1; i <= retries; i++) {
 669     *bits = reset_bits;  // reinit to only track last retry
 670 
 671     // We used to do an "os::yield_all(i)" call here with the intention
 672     // that yielding would increase on each retry. However, the parameter
 673     // is ignored on Linux which means the yield didn't scale up. Waiting
 674     // on the SR_lock below provides a much more predictable scale up for
 675     // the delay. It also provides a simple/direct point to check for any
 676     // safepoint requests from the VMThread
 677 
 678     {
 679       MutexLocker ml(SR_lock());
 680       // wait with safepoint check (if we're a JavaThread - the WatcherThread
 681       // can also call this)  and increase delay with each retry
 682       SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 683 
 684       is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 685                                               delay, bits);
 686 
 687       // It is possible for the external suspend request to be cancelled
 688       // (by a resume) before the actual suspend operation is completed.
 689       // Refresh our local copy to see if we still need to wait.
 690       pending = is_external_suspend();
 691     }
 692 
 693     if (!pending) {
 694       // A cancelled suspend request is the only false return from
 695       // is_ext_suspend_completed() that keeps us from staying in the
 696       // retry loop.
 697       *bits |= 0x00080000;
 698       return false;
 699     }
 700 
 701     if (is_suspended) {
 702       *bits |= 0x00100000;
 703       return true;
 704     }
 705   } // end retry loop
 706 
 707   // thread did not suspend after all our retries
 708   *bits |= 0x00200000;
 709   return false;
 710 }
 711 
 712 #ifndef PRODUCT
 713 void JavaThread::record_jump(address target, address instr, const char* file,
 714                              int line) {
 715 
 716   // This should not need to be atomic as the only way for simultaneous
 717   // updates is via interrupts. Even then this should be rare or non-existent
 718   // and we don't care that much anyway.
 719 
 720   int index = _jmp_ring_index;
 721   _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
 722   _jmp_ring[index]._target = (intptr_t) target;
 723   _jmp_ring[index]._instruction = (intptr_t) instr;
 724   _jmp_ring[index]._file = file;
 725   _jmp_ring[index]._line = line;
 726 }
 727 #endif // PRODUCT
 728 
 729 // Called by flat profiler
 730 // Callers have already called wait_for_ext_suspend_completion
 731 // The assertion for that is currently too complex to put here:
 732 bool JavaThread::profile_last_Java_frame(frame* _fr) {
 733   bool gotframe = false;
 734   // self suspension saves needed state.
 735   if (has_last_Java_frame() && _anchor.walkable()) {
 736     *_fr = pd_last_frame();
 737     gotframe = true;
 738   }
 739   return gotframe;
 740 }
 741 
 742 void Thread::interrupt(Thread* thread) {
 743   debug_only(check_for_dangling_thread_pointer(thread);)
 744   os::interrupt(thread);
 745 }
 746 
 747 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
 748   debug_only(check_for_dangling_thread_pointer(thread);)
 749   // Note:  If clear_interrupted==false, this simply fetches and
 750   // returns the value of the field osthread()->interrupted().
 751   return os::is_interrupted(thread, clear_interrupted);
 752 }
 753 
 754 
 755 // GC Support
 756 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
 757   jint thread_parity = _oops_do_parity;
 758   if (thread_parity != strong_roots_parity) {
 759     jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
 760     if (res == thread_parity) {
 761       return true;
 762     } else {
 763       guarantee(res == strong_roots_parity, "Or else what?");
 764       return false;
 765     }
 766   }
 767   return false;
 768 }
 769 
 770 void Thread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
 771   active_handles()->oops_do(f);
 772   // Do oop for ThreadShadow
 773   f->do_oop((oop*)&_pending_exception);
 774   handle_area()->oops_do(f);
 775 }
 776 
 777 void Thread::nmethods_do(CodeBlobClosure* cf) {
 778   // no nmethods in a generic thread...
 779 }
 780 
 781 void Thread::metadata_handles_do(void f(Metadata*)) {
 782   // Only walk the Handles in Thread.
 783   if (metadata_handles() != NULL) {
 784     for (int i = 0; i< metadata_handles()->length(); i++) {
 785       f(metadata_handles()->at(i));
 786     }
 787   }
 788 }
 789 
 790 void Thread::print_on(outputStream* st) const {
 791   // get_priority assumes osthread initialized
 792   if (osthread() != NULL) {
 793     int os_prio;
 794     if (os::get_native_priority(this, &os_prio) == OS_OK) {
 795       st->print("os_prio=%d ", os_prio);
 796     }
 797     st->print("tid=" INTPTR_FORMAT " ", this);
 798     ext().print_on(st);
 799     osthread()->print_on(st);
 800   }
 801   debug_only(if (WizardMode) print_owned_locks_on(st);)
 802 }
 803 
 804 // Thread::print_on_error() is called by fatal error handler. Don't use
 805 // any lock or allocate memory.
 806 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
 807   if (is_VM_thread())                 st->print("VMThread");
 808   else if (is_Compiler_thread())      st->print("CompilerThread");
 809   else if (is_Java_thread())          st->print("JavaThread");
 810   else if (is_GC_task_thread())       st->print("GCTaskThread");
 811   else if (is_Watcher_thread())       st->print("WatcherThread");
 812   else if (is_ConcurrentGC_thread())  st->print("ConcurrentGCThread");
 813   else                                st->print("Thread");
 814 
 815   st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
 816             _stack_base - _stack_size, _stack_base);
 817 
 818   if (osthread()) {
 819     st->print(" [id=%d]", osthread()->thread_id());
 820   }
 821 }
 822 
 823 #ifdef ASSERT
 824 void Thread::print_owned_locks_on(outputStream* st) const {
 825   Monitor *cur = _owned_locks;
 826   if (cur == NULL) {
 827     st->print(" (no locks) ");
 828   } else {
 829     st->print_cr(" Locks owned:");
 830     while (cur) {
 831       cur->print_on(st);
 832       cur = cur->next();
 833     }
 834   }
 835 }
 836 
 837 static int ref_use_count  = 0;
 838 
 839 bool Thread::owns_locks_but_compiled_lock() const {
 840   for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 841     if (cur != Compile_lock) return true;
 842   }
 843   return false;
 844 }
 845 
 846 
 847 #endif
 848 
 849 #ifndef PRODUCT
 850 
 851 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
 852 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
 853 // no threads which allow_vm_block's are held
 854 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
 855   // Check if current thread is allowed to block at a safepoint
 856   if (!(_allow_safepoint_count == 0)) {
 857     fatal("Possible safepoint reached by thread that does not allow it");
 858   }
 859   if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
 860     fatal("LEAF method calling lock?");
 861   }
 862 
 863 #ifdef ASSERT
 864   if (potential_vm_operation && is_Java_thread()
 865       && !Universe::is_bootstrapping()) {
 866     // Make sure we do not hold any locks that the VM thread also uses.
 867     // This could potentially lead to deadlocks
 868     for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 869       // Threads_lock is special, since the safepoint synchronization will not start before this is
 870       // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
 871       // since it is used to transfer control between JavaThreads and the VMThread
 872       // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
 873       if ((cur->allow_vm_block() &&
 874            cur != Threads_lock &&
 875            cur != Compile_lock &&               // Temporary: should not be necessary when we get separate compilation
 876            cur != VMOperationRequest_lock &&
 877            cur != VMOperationQueue_lock) ||
 878            cur->rank() == Mutex::special) {
 879         fatal(err_msg("Thread holding lock at safepoint that vm can block on: %s", cur->name()));
 880       }
 881     }
 882   }
 883 
 884   if (GCALotAtAllSafepoints) {
 885     // We could enter a safepoint here and thus have a gc
 886     InterfaceSupport::check_gc_alot();
 887   }
 888 #endif
 889 }
 890 #endif
 891 
 892 bool Thread::is_in_stack(address adr) const {
 893   assert(Thread::current() == this, "is_in_stack can only be called from current thread");
 894   address end = os::current_stack_pointer();
 895   // Allow non Java threads to call this without stack_base
 896   if (_stack_base == NULL) return true;
 897   if (stack_base() >= adr && adr >= end) return true;
 898 
 899   return false;
 900 }
 901 
 902 
 903 bool Thread::is_in_usable_stack(address adr) const {
 904   size_t stack_guard_size = os::uses_stack_guard_pages() ? (StackYellowPages + StackRedPages) * os::vm_page_size() : 0;
 905   size_t usable_stack_size = _stack_size - stack_guard_size;
 906 
 907   return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
 908 }
 909 
 910 
 911 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
 912 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
 913 // used for compilation in the future. If that change is made, the need for these methods
 914 // should be revisited, and they should be removed if possible.
 915 
 916 bool Thread::is_lock_owned(address adr) const {
 917   return on_local_stack(adr);
 918 }
 919 
 920 bool Thread::set_as_starting_thread() {
 921   // NOTE: this must be called inside the main thread.
 922   return os::create_main_thread((JavaThread*)this);
 923 }
 924 
 925 static void initialize_class(Symbol* class_name, TRAPS) {
 926   Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
 927   InstanceKlass::cast(klass)->initialize(CHECK);
 928 }
 929 
 930 
 931 // Creates the initial ThreadGroup
 932 static Handle create_initial_thread_group(TRAPS) {
 933   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
 934   instanceKlassHandle klass (THREAD, k);
 935 
 936   Handle system_instance = klass->allocate_instance_handle(CHECK_NH);
 937   {
 938     JavaValue result(T_VOID);
 939     JavaCalls::call_special(&result,
 940                             system_instance,
 941                             klass,
 942                             vmSymbols::object_initializer_name(),
 943                             vmSymbols::void_method_signature(),
 944                             CHECK_NH);
 945   }
 946   Universe::set_system_thread_group(system_instance());
 947 
 948   Handle main_instance = klass->allocate_instance_handle(CHECK_NH);
 949   {
 950     JavaValue result(T_VOID);
 951     Handle string = java_lang_String::create_from_str("main", CHECK_NH);
 952     JavaCalls::call_special(&result,
 953                             main_instance,
 954                             klass,
 955                             vmSymbols::object_initializer_name(),
 956                             vmSymbols::threadgroup_string_void_signature(),
 957                             system_instance,
 958                             string,
 959                             CHECK_NH);
 960   }
 961   return main_instance;
 962 }
 963 
 964 // Creates the initial Thread
 965 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
 966                                  TRAPS) {
 967   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
 968   instanceKlassHandle klass (THREAD, k);
 969   instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);
 970 
 971   java_lang_Thread::set_thread(thread_oop(), thread);
 972   java_lang_Thread::set_priority(thread_oop(), NormPriority);
 973   thread->set_threadObj(thread_oop());
 974 
 975   Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
 976 
 977   JavaValue result(T_VOID);
 978   JavaCalls::call_special(&result, thread_oop,
 979                           klass,
 980                           vmSymbols::object_initializer_name(),
 981                           vmSymbols::threadgroup_string_void_signature(),
 982                           thread_group,
 983                           string,
 984                           CHECK_NULL);
 985   return thread_oop();
 986 }
 987 
 988 static void call_initializeSystemClass(TRAPS) {
 989   Klass* k =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
 990   instanceKlassHandle klass (THREAD, k);
 991 
 992   JavaValue result(T_VOID);
 993   JavaCalls::call_static(&result, klass, vmSymbols::initializeSystemClass_name(),
 994                          vmSymbols::void_method_signature(), CHECK);
 995 }
 996 
 997 char java_runtime_name[128] = "";
 998 char java_runtime_version[128] = "";
 999 
1000 // extract the JRE name from sun.misc.Version.java_runtime_name
1001 static const char* get_java_runtime_name(TRAPS) {
1002   Klass* k = SystemDictionary::find(vmSymbols::sun_misc_Version(),
1003                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1004   fieldDescriptor fd;
1005   bool found = k != NULL &&
1006                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1007                                                         vmSymbols::string_signature(), &fd);
1008   if (found) {
1009     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1010     if (name_oop == NULL) {
1011       return NULL;
1012     }
1013     const char* name = java_lang_String::as_utf8_string(name_oop,
1014                                                         java_runtime_name,
1015                                                         sizeof(java_runtime_name));
1016     return name;
1017   } else {
1018     return NULL;
1019   }
1020 }
1021 
1022 // extract the JRE version from sun.misc.Version.java_runtime_version
1023 static const char* get_java_runtime_version(TRAPS) {
1024   Klass* k = SystemDictionary::find(vmSymbols::sun_misc_Version(),
1025                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1026   fieldDescriptor fd;
1027   bool found = k != NULL &&
1028                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1029                                                         vmSymbols::string_signature(), &fd);
1030   if (found) {
1031     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1032     if (name_oop == NULL) {
1033       return NULL;
1034     }
1035     const char* name = java_lang_String::as_utf8_string(name_oop,
1036                                                         java_runtime_version,
1037                                                         sizeof(java_runtime_version));
1038     return name;
1039   } else {
1040     return NULL;
1041   }
1042 }
1043 
1044 // General purpose hook into Java code, run once when the VM is initialized.
1045 // The Java library method itself may be changed independently from the VM.
1046 static void call_postVMInitHook(TRAPS) {
1047   Klass* k = SystemDictionary::resolve_or_null(vmSymbols::sun_misc_PostVMInitHook(), THREAD);
1048   instanceKlassHandle klass (THREAD, k);
1049   if (klass.not_null()) {
1050     JavaValue result(T_VOID);
1051     JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1052                            vmSymbols::void_method_signature(),
1053                            CHECK);
1054   }
1055 }
1056 
1057 static void reset_vm_info_property(TRAPS) {
1058   // the vm info string
1059   ResourceMark rm(THREAD);
1060   const char *vm_info = VM_Version::vm_info_string();
1061 
1062   // java.lang.System class
1063   Klass* k =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1064   instanceKlassHandle klass (THREAD, k);
1065 
1066   // setProperty arguments
1067   Handle key_str    = java_lang_String::create_from_str("java.vm.info", CHECK);
1068   Handle value_str  = java_lang_String::create_from_str(vm_info, CHECK);
1069 
1070   // return value
1071   JavaValue r(T_OBJECT);
1072 
1073   // public static String setProperty(String key, String value);
1074   JavaCalls::call_static(&r,
1075                          klass,
1076                          vmSymbols::setProperty_name(),
1077                          vmSymbols::string_string_string_signature(),
1078                          key_str,
1079                          value_str,
1080                          CHECK);
1081 }
1082 
1083 
1084 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1085                                     bool daemon, TRAPS) {
1086   assert(thread_group.not_null(), "thread group should be specified");
1087   assert(threadObj() == NULL, "should only create Java thread object once");
1088 
1089   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1090   instanceKlassHandle klass (THREAD, k);
1091   instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
1092 
1093   java_lang_Thread::set_thread(thread_oop(), this);
1094   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1095   set_threadObj(thread_oop());
1096 
1097   JavaValue result(T_VOID);
1098   if (thread_name != NULL) {
1099     Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1100     // Thread gets assigned specified name and null target
1101     JavaCalls::call_special(&result,
1102                             thread_oop,
1103                             klass,
1104                             vmSymbols::object_initializer_name(),
1105                             vmSymbols::threadgroup_string_void_signature(),
1106                             thread_group, // Argument 1
1107                             name,         // Argument 2
1108                             THREAD);
1109   } else {
1110     // Thread gets assigned name "Thread-nnn" and null target
1111     // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1112     JavaCalls::call_special(&result,
1113                             thread_oop,
1114                             klass,
1115                             vmSymbols::object_initializer_name(),
1116                             vmSymbols::threadgroup_runnable_void_signature(),
1117                             thread_group, // Argument 1
1118                             Handle(),     // Argument 2
1119                             THREAD);
1120   }
1121 
1122 
1123   if (daemon) {
1124     java_lang_Thread::set_daemon(thread_oop());
1125   }
1126 
1127   if (HAS_PENDING_EXCEPTION) {
1128     return;
1129   }
1130 
1131   KlassHandle group(THREAD, SystemDictionary::ThreadGroup_klass());
1132   Handle threadObj(THREAD, this->threadObj());
1133 
1134   JavaCalls::call_special(&result,
1135                           thread_group,
1136                           group,
1137                           vmSymbols::add_method_name(),
1138                           vmSymbols::thread_void_signature(),
1139                           threadObj,          // Arg 1
1140                           THREAD);
1141 }
1142 
1143 // NamedThread --  non-JavaThread subclasses with multiple
1144 // uniquely named instances should derive from this.
1145 NamedThread::NamedThread() : Thread() {
1146   _name = NULL;
1147   _processed_thread = NULL;
1148 }
1149 
1150 NamedThread::~NamedThread() {
1151   if (_name != NULL) {
1152     FREE_C_HEAP_ARRAY(char, _name);
1153     _name = NULL;
1154   }
1155 }
1156 
1157 void NamedThread::set_name(const char* format, ...) {
1158   guarantee(_name == NULL, "Only get to set name once.");
1159   _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1160   guarantee(_name != NULL, "alloc failure");
1161   va_list ap;
1162   va_start(ap, format);
1163   jio_vsnprintf(_name, max_name_len, format, ap);
1164   va_end(ap);
1165 }
1166 
1167 void NamedThread::initialize_named_thread() {
1168   set_native_thread_name(name());
1169 }
1170 
1171 void NamedThread::print_on(outputStream* st) const {
1172   st->print("\"%s\" ", name());
1173   Thread::print_on(st);
1174   st->cr();
1175 }
1176 
1177 
1178 // ======= WatcherThread ========
1179 
1180 // The watcher thread exists to simulate timer interrupts.  It should
1181 // be replaced by an abstraction over whatever native support for
1182 // timer interrupts exists on the platform.
1183 
1184 WatcherThread* WatcherThread::_watcher_thread   = NULL;
1185 bool WatcherThread::_startable = false;
1186 volatile bool  WatcherThread::_should_terminate = false;
1187 
1188 WatcherThread::WatcherThread() : Thread(), _crash_protection(NULL) {
1189   assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1190   if (os::create_thread(this, os::watcher_thread)) {
1191     _watcher_thread = this;
1192 
1193     // Set the watcher thread to the highest OS priority which should not be
1194     // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1195     // is created. The only normal thread using this priority is the reference
1196     // handler thread, which runs for very short intervals only.
1197     // If the VMThread's priority is not lower than the WatcherThread profiling
1198     // will be inaccurate.
1199     os::set_priority(this, MaxPriority);
1200     if (!DisableStartThread) {
1201       os::start_thread(this);
1202     }
1203   }
1204 }
1205 
1206 int WatcherThread::sleep() const {
1207   // The WatcherThread does not participate in the safepoint protocol
1208   // for the PeriodicTask_lock because it is not a JavaThread.
1209   MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1210 
1211   if (_should_terminate) {
1212     // check for termination before we do any housekeeping or wait
1213     return 0;  // we did not sleep.
1214   }
1215 
1216   // remaining will be zero if there are no tasks,
1217   // causing the WatcherThread to sleep until a task is
1218   // enrolled
1219   int remaining = PeriodicTask::time_to_wait();
1220   int time_slept = 0;
1221 
1222   // we expect this to timeout - we only ever get unparked when
1223   // we should terminate or when a new task has been enrolled
1224   OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1225 
1226   jlong time_before_loop = os::javaTimeNanos();
1227 
1228   while (true) {
1229     bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1230                                             remaining);
1231     jlong now = os::javaTimeNanos();
1232 
1233     if (remaining == 0) {
1234       // if we didn't have any tasks we could have waited for a long time
1235       // consider the time_slept zero and reset time_before_loop
1236       time_slept = 0;
1237       time_before_loop = now;
1238     } else {
1239       // need to recalculate since we might have new tasks in _tasks
1240       time_slept = (int) ((now - time_before_loop) / 1000000);
1241     }
1242 
1243     // Change to task list or spurious wakeup of some kind
1244     if (timedout || _should_terminate) {
1245       break;
1246     }
1247 
1248     remaining = PeriodicTask::time_to_wait();
1249     if (remaining == 0) {
1250       // Last task was just disenrolled so loop around and wait until
1251       // another task gets enrolled
1252       continue;
1253     }
1254 
1255     remaining -= time_slept;
1256     if (remaining <= 0) {
1257       break;
1258     }
1259   }
1260 
1261   return time_slept;
1262 }
1263 
1264 void WatcherThread::run() {
1265   assert(this == watcher_thread(), "just checking");
1266 
1267   this->record_stack_base_and_size();
1268   this->initialize_thread_local_storage();
1269   this->set_native_thread_name(this->name());
1270   this->set_active_handles(JNIHandleBlock::allocate_block());
1271   while (true) {
1272     assert(watcher_thread() == Thread::current(), "thread consistency check");
1273     assert(watcher_thread() == this, "thread consistency check");
1274 
1275     // Calculate how long it'll be until the next PeriodicTask work
1276     // should be done, and sleep that amount of time.
1277     int time_waited = sleep();
1278 
1279     if (is_error_reported()) {
1280       // A fatal error has happened, the error handler(VMError::report_and_die)
1281       // should abort JVM after creating an error log file. However in some
1282       // rare cases, the error handler itself might deadlock. Here we try to
1283       // kill JVM if the fatal error handler fails to abort in 2 minutes.
1284       //
1285       // This code is in WatcherThread because WatcherThread wakes up
1286       // periodically so the fatal error handler doesn't need to do anything;
1287       // also because the WatcherThread is less likely to crash than other
1288       // threads.
1289 
1290       for (;;) {
1291         if (!ShowMessageBoxOnError
1292             && (OnError == NULL || OnError[0] == '\0')
1293             && Arguments::abort_hook() == NULL) {
1294           os::sleep(this, 2 * 60 * 1000, false);
1295           fdStream err(defaultStream::output_fd());
1296           err.print_raw_cr("# [ timer expired, abort... ]");
1297           // skip atexit/vm_exit/vm_abort hooks
1298           os::die();
1299         }
1300 
1301         // Wake up 5 seconds later, the fatal handler may reset OnError or
1302         // ShowMessageBoxOnError when it is ready to abort.
1303         os::sleep(this, 5 * 1000, false);
1304       }
1305     }
1306 
1307     if (_should_terminate) {
1308       // check for termination before posting the next tick
1309       break;
1310     }
1311 
1312     PeriodicTask::real_time_tick(time_waited);
1313   }
1314 
1315   // Signal that it is terminated
1316   {
1317     MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1318     _watcher_thread = NULL;
1319     Terminator_lock->notify();
1320   }
1321 
1322   // Thread destructor usually does this..
1323   ThreadLocalStorage::set_thread(NULL);
1324 }
1325 
1326 void WatcherThread::start() {
1327   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1328 
1329   if (watcher_thread() == NULL && _startable) {
1330     _should_terminate = false;
1331     // Create the single instance of WatcherThread
1332     new WatcherThread();
1333   }
1334 }
1335 
1336 void WatcherThread::make_startable() {
1337   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1338   _startable = true;
1339 }
1340 
1341 void WatcherThread::stop() {
1342   {
1343     // Follow normal safepoint aware lock enter protocol since the
1344     // WatcherThread is stopped by another JavaThread.
1345     MutexLocker ml(PeriodicTask_lock);
1346     _should_terminate = true;
1347 
1348     WatcherThread* watcher = watcher_thread();
1349     if (watcher != NULL) {
1350       // unpark the WatcherThread so it can see that it should terminate
1351       watcher->unpark();
1352     }
1353   }
1354 
1355   MutexLocker mu(Terminator_lock);
1356 
1357   while (watcher_thread() != NULL) {
1358     // This wait should make safepoint checks, wait without a timeout,
1359     // and wait as a suspend-equivalent condition.
1360     //
1361     // Note: If the FlatProfiler is running, then this thread is waiting
1362     // for the WatcherThread to terminate and the WatcherThread, via the
1363     // FlatProfiler task, is waiting for the external suspend request on
1364     // this thread to complete. wait_for_ext_suspend_completion() will
1365     // eventually timeout, but that takes time. Making this wait a
1366     // suspend-equivalent condition solves that timeout problem.
1367     //
1368     Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1369                           Mutex::_as_suspend_equivalent_flag);
1370   }
1371 }
1372 
1373 void WatcherThread::unpark() {
1374   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1375   PeriodicTask_lock->notify();
1376 }
1377 
1378 void WatcherThread::print_on(outputStream* st) const {
1379   st->print("\"%s\" ", name());
1380   Thread::print_on(st);
1381   st->cr();
1382 }
1383 
1384 // ======= JavaThread ========
1385 
1386 // A JavaThread is a normal Java thread
1387 
1388 void JavaThread::initialize() {
1389   // Initialize fields
1390 
1391   // Set the claimed par_id to UINT_MAX (ie not claiming any par_ids)
1392   set_claimed_par_id(UINT_MAX);
1393 
1394   set_saved_exception_pc(NULL);
1395   set_threadObj(NULL);
1396   _anchor.clear();
1397   set_entry_point(NULL);
1398   set_jni_functions(jni_functions());
1399   set_callee_target(NULL);
1400   set_vm_result(NULL);
1401   set_vm_result_2(NULL);
1402   set_vframe_array_head(NULL);
1403   set_vframe_array_last(NULL);
1404   set_deferred_locals(NULL);
1405   set_deopt_mark(NULL);
1406   set_deopt_nmethod(NULL);
1407   clear_must_deopt_id();
1408   set_monitor_chunks(NULL);
1409   set_next(NULL);
1410   set_thread_state(_thread_new);
1411   _terminated = _not_terminated;
1412   _privileged_stack_top = NULL;
1413   _array_for_gc = NULL;
1414   _suspend_equivalent = false;
1415   _in_deopt_handler = 0;
1416   _doing_unsafe_access = false;
1417   _stack_guard_state = stack_guard_unused;
1418   (void)const_cast<oop&>(_exception_oop = oop(NULL));
1419   _exception_pc  = 0;
1420   _exception_handler_pc = 0;
1421   _is_method_handle_return = 0;
1422   _jvmti_thread_state= NULL;
1423   _should_post_on_exceptions_flag = JNI_FALSE;
1424   _jvmti_get_loaded_classes_closure = NULL;
1425   _interp_only_mode    = 0;
1426   _special_runtime_exit_condition = _no_async_condition;
1427   _pending_async_exception = NULL;
1428   _thread_stat = NULL;
1429   _thread_stat = new ThreadStatistics();
1430   _blocked_on_compilation = false;
1431   _jni_active_critical = 0;
1432   _pending_jni_exception_check_fn = NULL;
1433   _do_not_unlock_if_synchronized = false;
1434   _cached_monitor_info = NULL;
1435   _parker = Parker::Allocate(this);
1436 
1437 #ifndef PRODUCT
1438   _jmp_ring_index = 0;
1439   for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1440     record_jump(NULL, NULL, NULL, 0);
1441   }
1442 #endif // PRODUCT
1443 
1444   set_thread_profiler(NULL);
1445   if (FlatProfiler::is_active()) {
1446     // This is where we would decide to either give each thread it's own profiler
1447     // or use one global one from FlatProfiler,
1448     // or up to some count of the number of profiled threads, etc.
1449     ThreadProfiler* pp = new ThreadProfiler();
1450     pp->engage();
1451     set_thread_profiler(pp);
1452   }
1453 
1454   // Setup safepoint state info for this thread
1455   ThreadSafepointState::create(this);
1456 
1457   debug_only(_java_call_counter = 0);
1458 
1459   // JVMTI PopFrame support
1460   _popframe_condition = popframe_inactive;
1461   _popframe_preserved_args = NULL;
1462   _popframe_preserved_args_size = 0;
1463   _frames_to_pop_failed_realloc = 0;
1464 
1465   pd_initialize();
1466 }
1467 
1468 #if INCLUDE_ALL_GCS
1469 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1470 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1471 #endif // INCLUDE_ALL_GCS
1472 
1473 JavaThread::JavaThread(bool is_attaching_via_jni) :
1474                        Thread()
1475 #if INCLUDE_ALL_GCS
1476                        , _satb_mark_queue(&_satb_mark_queue_set),
1477                        _dirty_card_queue(&_dirty_card_queue_set)
1478 #endif // INCLUDE_ALL_GCS
1479 {
1480   initialize();
1481   if (is_attaching_via_jni) {
1482     _jni_attach_state = _attaching_via_jni;
1483   } else {
1484     _jni_attach_state = _not_attaching_via_jni;
1485   }
1486   assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1487 }
1488 
1489 bool JavaThread::reguard_stack(address cur_sp) {
1490   if (_stack_guard_state != stack_guard_yellow_disabled) {
1491     return true; // Stack already guarded or guard pages not needed.
1492   }
1493 
1494   if (register_stack_overflow()) {
1495     // For those architectures which have separate register and
1496     // memory stacks, we must check the register stack to see if
1497     // it has overflowed.
1498     return false;
1499   }
1500 
1501   // Java code never executes within the yellow zone: the latter is only
1502   // there to provoke an exception during stack banging.  If java code
1503   // is executing there, either StackShadowPages should be larger, or
1504   // some exception code in c1, c2 or the interpreter isn't unwinding
1505   // when it should.
1506   guarantee(cur_sp > stack_yellow_zone_base(), "not enough space to reguard - increase StackShadowPages");
1507 
1508   enable_stack_yellow_zone();
1509   return true;
1510 }
1511 
1512 bool JavaThread::reguard_stack(void) {
1513   return reguard_stack(os::current_stack_pointer());
1514 }
1515 
1516 
1517 void JavaThread::block_if_vm_exited() {
1518   if (_terminated == _vm_exited) {
1519     // _vm_exited is set at safepoint, and Threads_lock is never released
1520     // we will block here forever
1521     Threads_lock->lock_without_safepoint_check();
1522     ShouldNotReachHere();
1523   }
1524 }
1525 
1526 
1527 // Remove this ifdef when C1 is ported to the compiler interface.
1528 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1529 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1530 
1531 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1532                        Thread()
1533 #if INCLUDE_ALL_GCS
1534                        , _satb_mark_queue(&_satb_mark_queue_set),
1535                        _dirty_card_queue(&_dirty_card_queue_set)
1536 #endif // INCLUDE_ALL_GCS
1537 {
1538   initialize();
1539   _jni_attach_state = _not_attaching_via_jni;
1540   set_entry_point(entry_point);
1541   // Create the native thread itself.
1542   // %note runtime_23
1543   os::ThreadType thr_type = os::java_thread;
1544   thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1545                                                      os::java_thread;
1546   os::create_thread(this, thr_type, stack_sz);
1547   // The _osthread may be NULL here because we ran out of memory (too many threads active).
1548   // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1549   // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1550   // the exception consists of creating the exception object & initializing it, initialization
1551   // will leave the VM via a JavaCall and then all locks must be unlocked).
1552   //
1553   // The thread is still suspended when we reach here. Thread must be explicit started
1554   // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1555   // by calling Threads:add. The reason why this is not done here, is because the thread
1556   // object must be fully initialized (take a look at JVM_Start)
1557 }
1558 
1559 JavaThread::~JavaThread() {
1560 
1561   // JSR166 -- return the parker to the free list
1562   Parker::Release(_parker);
1563   _parker = NULL;
1564 
1565   // Free any remaining  previous UnrollBlock
1566   vframeArray* old_array = vframe_array_last();
1567 
1568   if (old_array != NULL) {
1569     Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1570     old_array->set_unroll_block(NULL);
1571     delete old_info;
1572     delete old_array;
1573   }
1574 
1575   GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1576   if (deferred != NULL) {
1577     // This can only happen if thread is destroyed before deoptimization occurs.
1578     assert(deferred->length() != 0, "empty array!");
1579     do {
1580       jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1581       deferred->remove_at(0);
1582       // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1583       delete dlv;
1584     } while (deferred->length() != 0);
1585     delete deferred;
1586   }
1587 
1588   // All Java related clean up happens in exit
1589   ThreadSafepointState::destroy(this);
1590   if (_thread_profiler != NULL) delete _thread_profiler;
1591   if (_thread_stat != NULL) delete _thread_stat;
1592 }
1593 
1594 
1595 // The first routine called by a new Java thread
1596 void JavaThread::run() {
1597   // initialize thread-local alloc buffer related fields
1598   this->initialize_tlab();
1599 
1600   // used to test validity of stack trace backs
1601   this->record_base_of_stack_pointer();
1602 
1603   // Record real stack base and size.
1604   this->record_stack_base_and_size();
1605 
1606   // Initialize thread local storage; set before calling MutexLocker
1607   this->initialize_thread_local_storage();
1608 
1609   this->create_stack_guard_pages();
1610 
1611   this->cache_global_variables();
1612 
1613   // Thread is now sufficient initialized to be handled by the safepoint code as being
1614   // in the VM. Change thread state from _thread_new to _thread_in_vm
1615   ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1616 
1617   assert(JavaThread::current() == this, "sanity check");
1618   assert(!Thread::current()->owns_locks(), "sanity check");
1619 
1620   DTRACE_THREAD_PROBE(start, this);
1621 
1622   // This operation might block. We call that after all safepoint checks for a new thread has
1623   // been completed.
1624   this->set_active_handles(JNIHandleBlock::allocate_block());
1625 
1626   if (JvmtiExport::should_post_thread_life()) {
1627     JvmtiExport::post_thread_start(this);
1628   }
1629 
1630   EventThreadStart event;
1631   if (event.should_commit()) {
1632     event.set_javalangthread(java_lang_Thread::thread_id(this->threadObj()));
1633     event.commit();
1634   }
1635 
1636   // We call another function to do the rest so we are sure that the stack addresses used
1637   // from there will be lower than the stack base just computed
1638   thread_main_inner();
1639 
1640   // Note, thread is no longer valid at this point!
1641 }
1642 
1643 
1644 void JavaThread::thread_main_inner() {
1645   assert(JavaThread::current() == this, "sanity check");
1646   assert(this->threadObj() != NULL, "just checking");
1647 
1648   // Execute thread entry point unless this thread has a pending exception
1649   // or has been stopped before starting.
1650   // Note: Due to JVM_StopThread we can have pending exceptions already!
1651   if (!this->has_pending_exception() &&
1652       !java_lang_Thread::is_stillborn(this->threadObj())) {
1653     {
1654       ResourceMark rm(this);
1655       this->set_native_thread_name(this->get_thread_name());
1656     }
1657     HandleMark hm(this);
1658     this->entry_point()(this, this);
1659   }
1660 
1661   DTRACE_THREAD_PROBE(stop, this);
1662 
1663   this->exit(false);
1664   delete this;
1665 }
1666 
1667 
1668 static void ensure_join(JavaThread* thread) {
1669   // We do not need to grap the Threads_lock, since we are operating on ourself.
1670   Handle threadObj(thread, thread->threadObj());
1671   assert(threadObj.not_null(), "java thread object must exist");
1672   ObjectLocker lock(threadObj, thread);
1673   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1674   thread->clear_pending_exception();
1675   // Thread is exiting. So set thread_status field in  java.lang.Thread class to TERMINATED.
1676   java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1677   // Clear the native thread instance - this makes isAlive return false and allows the join()
1678   // to complete once we've done the notify_all below
1679   java_lang_Thread::set_thread(threadObj(), NULL);
1680   lock.notify_all(thread);
1681   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1682   thread->clear_pending_exception();
1683 }
1684 
1685 
1686 // For any new cleanup additions, please check to see if they need to be applied to
1687 // cleanup_failed_attach_current_thread as well.
1688 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1689   assert(this == JavaThread::current(), "thread consistency check");
1690 
1691   HandleMark hm(this);
1692   Handle uncaught_exception(this, this->pending_exception());
1693   this->clear_pending_exception();
1694   Handle threadObj(this, this->threadObj());
1695   assert(threadObj.not_null(), "Java thread object should be created");
1696 
1697   if (get_thread_profiler() != NULL) {
1698     get_thread_profiler()->disengage();
1699     ResourceMark rm;
1700     get_thread_profiler()->print(get_thread_name());
1701   }
1702 
1703 
1704   // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1705   {
1706     EXCEPTION_MARK;
1707 
1708     CLEAR_PENDING_EXCEPTION;
1709   }
1710   if (!destroy_vm) {
1711     if (uncaught_exception.not_null()) {
1712       EXCEPTION_MARK;
1713       // Call method Thread.dispatchUncaughtException().
1714       KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1715       JavaValue result(T_VOID);
1716       JavaCalls::call_virtual(&result,
1717                               threadObj, thread_klass,
1718                               vmSymbols::dispatchUncaughtException_name(),
1719                               vmSymbols::throwable_void_signature(),
1720                               uncaught_exception,
1721                               THREAD);
1722       if (HAS_PENDING_EXCEPTION) {
1723         ResourceMark rm(this);
1724         jio_fprintf(defaultStream::error_stream(),
1725                     "\nException: %s thrown from the UncaughtExceptionHandler"
1726                     " in thread \"%s\"\n",
1727                     pending_exception()->klass()->external_name(),
1728                     get_thread_name());
1729         CLEAR_PENDING_EXCEPTION;
1730       }
1731     }
1732 
1733     // Called before the java thread exit since we want to read info
1734     // from java_lang_Thread object
1735     EventThreadEnd event;
1736     if (event.should_commit()) {
1737       event.set_javalangthread(java_lang_Thread::thread_id(this->threadObj()));
1738       event.commit();
1739     }
1740 
1741     // Call after last event on thread
1742     EVENT_THREAD_EXIT(this);
1743 
1744     // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1745     // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1746     // is deprecated anyhow.
1747     if (!is_Compiler_thread()) {
1748       int count = 3;
1749       while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1750         EXCEPTION_MARK;
1751         JavaValue result(T_VOID);
1752         KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1753         JavaCalls::call_virtual(&result,
1754                                 threadObj, thread_klass,
1755                                 vmSymbols::exit_method_name(),
1756                                 vmSymbols::void_method_signature(),
1757                                 THREAD);
1758         CLEAR_PENDING_EXCEPTION;
1759       }
1760     }
1761     // notify JVMTI
1762     if (JvmtiExport::should_post_thread_life()) {
1763       JvmtiExport::post_thread_end(this);
1764     }
1765 
1766     // We have notified the agents that we are exiting, before we go on,
1767     // we must check for a pending external suspend request and honor it
1768     // in order to not surprise the thread that made the suspend request.
1769     while (true) {
1770       {
1771         MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1772         if (!is_external_suspend()) {
1773           set_terminated(_thread_exiting);
1774           ThreadService::current_thread_exiting(this);
1775           break;
1776         }
1777         // Implied else:
1778         // Things get a little tricky here. We have a pending external
1779         // suspend request, but we are holding the SR_lock so we
1780         // can't just self-suspend. So we temporarily drop the lock
1781         // and then self-suspend.
1782       }
1783 
1784       ThreadBlockInVM tbivm(this);
1785       java_suspend_self();
1786 
1787       // We're done with this suspend request, but we have to loop around
1788       // and check again. Eventually we will get SR_lock without a pending
1789       // external suspend request and will be able to mark ourselves as
1790       // exiting.
1791     }
1792     // no more external suspends are allowed at this point
1793   } else {
1794     // before_exit() has already posted JVMTI THREAD_END events
1795   }
1796 
1797   // Notify waiters on thread object. This has to be done after exit() is called
1798   // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1799   // group should have the destroyed bit set before waiters are notified).
1800   ensure_join(this);
1801   assert(!this->has_pending_exception(), "ensure_join should have cleared");
1802 
1803   // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1804   // held by this thread must be released.  A detach operation must only
1805   // get here if there are no Java frames on the stack.  Therefore, any
1806   // owned monitors at this point MUST be JNI-acquired monitors which are
1807   // pre-inflated and in the monitor cache.
1808   //
1809   // ensure_join() ignores IllegalThreadStateExceptions, and so does this.
1810   if (exit_type == jni_detach && JNIDetachReleasesMonitors) {
1811     assert(!this->has_last_Java_frame(), "detaching with Java frames?");
1812     ObjectSynchronizer::release_monitors_owned_by_thread(this);
1813     assert(!this->has_pending_exception(), "release_monitors should have cleared");
1814   }
1815 
1816   // These things needs to be done while we are still a Java Thread. Make sure that thread
1817   // is in a consistent state, in case GC happens
1818   assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1819 
1820   if (active_handles() != NULL) {
1821     JNIHandleBlock* block = active_handles();
1822     set_active_handles(NULL);
1823     JNIHandleBlock::release_block(block);
1824   }
1825 
1826   if (free_handle_block() != NULL) {
1827     JNIHandleBlock* block = free_handle_block();
1828     set_free_handle_block(NULL);
1829     JNIHandleBlock::release_block(block);
1830   }
1831 
1832   // These have to be removed while this is still a valid thread.
1833   remove_stack_guard_pages();
1834 
1835   if (UseTLAB) {
1836     tlab().make_parsable(true);  // retire TLAB
1837   }
1838 
1839   if (JvmtiEnv::environments_might_exist()) {
1840     JvmtiExport::cleanup_thread(this);
1841   }
1842 
1843   // We must flush any deferred card marks before removing a thread from
1844   // the list of active threads.
1845   Universe::heap()->flush_deferred_store_barrier(this);
1846   assert(deferred_card_mark().is_empty(), "Should have been flushed");
1847 
1848 #if INCLUDE_ALL_GCS
1849   // We must flush the G1-related buffers before removing a thread
1850   // from the list of active threads. We must do this after any deferred
1851   // card marks have been flushed (above) so that any entries that are
1852   // added to the thread's dirty card queue as a result are not lost.
1853   if (UseG1GC) {
1854     flush_barrier_queues();
1855   }
1856 #endif // INCLUDE_ALL_GCS
1857 
1858   // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1859   Threads::remove(this);
1860 }
1861 
1862 #if INCLUDE_ALL_GCS
1863 // Flush G1-related queues.
1864 void JavaThread::flush_barrier_queues() {
1865   satb_mark_queue().flush();
1866   dirty_card_queue().flush();
1867 }
1868 
1869 void JavaThread::initialize_queues() {
1870   assert(!SafepointSynchronize::is_at_safepoint(),
1871          "we should not be at a safepoint");
1872 
1873   ObjPtrQueue& satb_queue = satb_mark_queue();
1874   SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1875   // The SATB queue should have been constructed with its active
1876   // field set to false.
1877   assert(!satb_queue.is_active(), "SATB queue should not be active");
1878   assert(satb_queue.is_empty(), "SATB queue should be empty");
1879   // If we are creating the thread during a marking cycle, we should
1880   // set the active field of the SATB queue to true.
1881   if (satb_queue_set.is_active()) {
1882     satb_queue.set_active(true);
1883   }
1884 
1885   DirtyCardQueue& dirty_queue = dirty_card_queue();
1886   // The dirty card queue should have been constructed with its
1887   // active field set to true.
1888   assert(dirty_queue.is_active(), "dirty card queue should be active");
1889 }
1890 #endif // INCLUDE_ALL_GCS
1891 
1892 void JavaThread::cleanup_failed_attach_current_thread() {
1893   if (get_thread_profiler() != NULL) {
1894     get_thread_profiler()->disengage();
1895     ResourceMark rm;
1896     get_thread_profiler()->print(get_thread_name());
1897   }
1898 
1899   if (active_handles() != NULL) {
1900     JNIHandleBlock* block = active_handles();
1901     set_active_handles(NULL);
1902     JNIHandleBlock::release_block(block);
1903   }
1904 
1905   if (free_handle_block() != NULL) {
1906     JNIHandleBlock* block = free_handle_block();
1907     set_free_handle_block(NULL);
1908     JNIHandleBlock::release_block(block);
1909   }
1910 
1911   // These have to be removed while this is still a valid thread.
1912   remove_stack_guard_pages();
1913 
1914   if (UseTLAB) {
1915     tlab().make_parsable(true);  // retire TLAB, if any
1916   }
1917 
1918 #if INCLUDE_ALL_GCS
1919   if (UseG1GC) {
1920     flush_barrier_queues();
1921   }
1922 #endif // INCLUDE_ALL_GCS
1923 
1924   Threads::remove(this);
1925   delete this;
1926 }
1927 
1928 
1929 
1930 
1931 JavaThread* JavaThread::active() {
1932   Thread* thread = ThreadLocalStorage::thread();
1933   assert(thread != NULL, "just checking");
1934   if (thread->is_Java_thread()) {
1935     return (JavaThread*) thread;
1936   } else {
1937     assert(thread->is_VM_thread(), "this must be a vm thread");
1938     VM_Operation* op = ((VMThread*) thread)->vm_operation();
1939     JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
1940     assert(ret->is_Java_thread(), "must be a Java thread");
1941     return ret;
1942   }
1943 }
1944 
1945 bool JavaThread::is_lock_owned(address adr) const {
1946   if (Thread::is_lock_owned(adr)) return true;
1947 
1948   for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
1949     if (chunk->contains(adr)) return true;
1950   }
1951 
1952   return false;
1953 }
1954 
1955 
1956 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
1957   chunk->set_next(monitor_chunks());
1958   set_monitor_chunks(chunk);
1959 }
1960 
1961 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
1962   guarantee(monitor_chunks() != NULL, "must be non empty");
1963   if (monitor_chunks() == chunk) {
1964     set_monitor_chunks(chunk->next());
1965   } else {
1966     MonitorChunk* prev = monitor_chunks();
1967     while (prev->next() != chunk) prev = prev->next();
1968     prev->set_next(chunk->next());
1969   }
1970 }
1971 
1972 // JVM support.
1973 
1974 // Note: this function shouldn't block if it's called in
1975 // _thread_in_native_trans state (such as from
1976 // check_special_condition_for_native_trans()).
1977 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
1978 
1979   if (has_last_Java_frame() && has_async_condition()) {
1980     // If we are at a polling page safepoint (not a poll return)
1981     // then we must defer async exception because live registers
1982     // will be clobbered by the exception path. Poll return is
1983     // ok because the call we a returning from already collides
1984     // with exception handling registers and so there is no issue.
1985     // (The exception handling path kills call result registers but
1986     //  this is ok since the exception kills the result anyway).
1987 
1988     if (is_at_poll_safepoint()) {
1989       // if the code we are returning to has deoptimized we must defer
1990       // the exception otherwise live registers get clobbered on the
1991       // exception path before deoptimization is able to retrieve them.
1992       //
1993       RegisterMap map(this, false);
1994       frame caller_fr = last_frame().sender(&map);
1995       assert(caller_fr.is_compiled_frame(), "what?");
1996       if (caller_fr.is_deoptimized_frame()) {
1997         if (TraceExceptions) {
1998           ResourceMark rm;
1999           tty->print_cr("deferred async exception at compiled safepoint");
2000         }
2001         return;
2002       }
2003     }
2004   }
2005 
2006   JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2007   if (condition == _no_async_condition) {
2008     // Conditions have changed since has_special_runtime_exit_condition()
2009     // was called:
2010     // - if we were here only because of an external suspend request,
2011     //   then that was taken care of above (or cancelled) so we are done
2012     // - if we were here because of another async request, then it has
2013     //   been cleared between the has_special_runtime_exit_condition()
2014     //   and now so again we are done
2015     return;
2016   }
2017 
2018   // Check for pending async. exception
2019   if (_pending_async_exception != NULL) {
2020     // Only overwrite an already pending exception, if it is not a threadDeath.
2021     if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2022 
2023       // We cannot call Exceptions::_throw(...) here because we cannot block
2024       set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2025 
2026       if (TraceExceptions) {
2027         ResourceMark rm;
2028         tty->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", this);
2029         if (has_last_Java_frame()) {
2030           frame f = last_frame();
2031           tty->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", f.pc(), f.sp());
2032         }
2033         tty->print_cr(" of type: %s", InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2034       }
2035       _pending_async_exception = NULL;
2036       clear_has_async_exception();
2037     }
2038   }
2039 
2040   if (check_unsafe_error &&
2041       condition == _async_unsafe_access_error && !has_pending_exception()) {
2042     condition = _no_async_condition;  // done
2043     switch (thread_state()) {
2044     case _thread_in_vm: {
2045       JavaThread* THREAD = this;
2046       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2047     }
2048     case _thread_in_native: {
2049       ThreadInVMfromNative tiv(this);
2050       JavaThread* THREAD = this;
2051       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2052     }
2053     case _thread_in_Java: {
2054       ThreadInVMfromJava tiv(this);
2055       JavaThread* THREAD = this;
2056       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2057     }
2058     default:
2059       ShouldNotReachHere();
2060     }
2061   }
2062 
2063   assert(condition == _no_async_condition || has_pending_exception() ||
2064          (!check_unsafe_error && condition == _async_unsafe_access_error),
2065          "must have handled the async condition, if no exception");
2066 }
2067 
2068 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2069   //
2070   // Check for pending external suspend. Internal suspend requests do
2071   // not use handle_special_runtime_exit_condition().
2072   // If JNIEnv proxies are allowed, don't self-suspend if the target
2073   // thread is not the current thread. In older versions of jdbx, jdbx
2074   // threads could call into the VM with another thread's JNIEnv so we
2075   // can be here operating on behalf of a suspended thread (4432884).
2076   bool do_self_suspend = is_external_suspend_with_lock();
2077   if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2078     //
2079     // Because thread is external suspended the safepoint code will count
2080     // thread as at a safepoint. This can be odd because we can be here
2081     // as _thread_in_Java which would normally transition to _thread_blocked
2082     // at a safepoint. We would like to mark the thread as _thread_blocked
2083     // before calling java_suspend_self like all other callers of it but
2084     // we must then observe proper safepoint protocol. (We can't leave
2085     // _thread_blocked with a safepoint in progress). However we can be
2086     // here as _thread_in_native_trans so we can't use a normal transition
2087     // constructor/destructor pair because they assert on that type of
2088     // transition. We could do something like:
2089     //
2090     // JavaThreadState state = thread_state();
2091     // set_thread_state(_thread_in_vm);
2092     // {
2093     //   ThreadBlockInVM tbivm(this);
2094     //   java_suspend_self()
2095     // }
2096     // set_thread_state(_thread_in_vm_trans);
2097     // if (safepoint) block;
2098     // set_thread_state(state);
2099     //
2100     // but that is pretty messy. Instead we just go with the way the
2101     // code has worked before and note that this is the only path to
2102     // java_suspend_self that doesn't put the thread in _thread_blocked
2103     // mode.
2104 
2105     frame_anchor()->make_walkable(this);
2106     java_suspend_self();
2107 
2108     // We might be here for reasons in addition to the self-suspend request
2109     // so check for other async requests.
2110   }
2111 
2112   if (check_asyncs) {
2113     check_and_handle_async_exceptions();
2114   }
2115 }
2116 
2117 void JavaThread::send_thread_stop(oop java_throwable)  {
2118   assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2119   assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2120   assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2121 
2122   // Do not throw asynchronous exceptions against the compiler thread
2123   // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2124   if (is_Compiler_thread()) return;
2125 
2126   {
2127     // Actually throw the Throwable against the target Thread - however
2128     // only if there is no thread death exception installed already.
2129     if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2130       // If the topmost frame is a runtime stub, then we are calling into
2131       // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2132       // must deoptimize the caller before continuing, as the compiled  exception handler table
2133       // may not be valid
2134       if (has_last_Java_frame()) {
2135         frame f = last_frame();
2136         if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2137           // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2138           RegisterMap reg_map(this, UseBiasedLocking);
2139           frame compiled_frame = f.sender(&reg_map);
2140           if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2141             Deoptimization::deoptimize(this, compiled_frame, &reg_map);
2142           }
2143         }
2144       }
2145 
2146       // Set async. pending exception in thread.
2147       set_pending_async_exception(java_throwable);
2148 
2149       if (TraceExceptions) {
2150         ResourceMark rm;
2151         tty->print_cr("Pending Async. exception installed of type: %s", InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2152       }
2153       // for AbortVMOnException flag
2154       NOT_PRODUCT(Exceptions::debug_check_abort(InstanceKlass::cast(_pending_async_exception->klass())->external_name()));
2155     }
2156   }
2157 
2158 
2159   // Interrupt thread so it will wake up from a potential wait()
2160   Thread::interrupt(this);
2161 }
2162 
2163 // External suspension mechanism.
2164 //
2165 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2166 // to any VM_locks and it is at a transition
2167 // Self-suspension will happen on the transition out of the vm.
2168 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2169 //
2170 // Guarantees on return:
2171 //   + Target thread will not execute any new bytecode (that's why we need to
2172 //     force a safepoint)
2173 //   + Target thread will not enter any new monitors
2174 //
2175 void JavaThread::java_suspend() {
2176   { MutexLocker mu(Threads_lock);
2177     if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2178       return;
2179     }
2180   }
2181 
2182   { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2183     if (!is_external_suspend()) {
2184       // a racing resume has cancelled us; bail out now
2185       return;
2186     }
2187 
2188     // suspend is done
2189     uint32_t debug_bits = 0;
2190     // Warning: is_ext_suspend_completed() may temporarily drop the
2191     // SR_lock to allow the thread to reach a stable thread state if
2192     // it is currently in a transient thread state.
2193     if (is_ext_suspend_completed(false /* !called_by_wait */,
2194                                  SuspendRetryDelay, &debug_bits)) {
2195       return;
2196     }
2197   }
2198 
2199   VM_ForceSafepoint vm_suspend;
2200   VMThread::execute(&vm_suspend);
2201 }
2202 
2203 // Part II of external suspension.
2204 // A JavaThread self suspends when it detects a pending external suspend
2205 // request. This is usually on transitions. It is also done in places
2206 // where continuing to the next transition would surprise the caller,
2207 // e.g., monitor entry.
2208 //
2209 // Returns the number of times that the thread self-suspended.
2210 //
2211 // Note: DO NOT call java_suspend_self() when you just want to block current
2212 //       thread. java_suspend_self() is the second stage of cooperative
2213 //       suspension for external suspend requests and should only be used
2214 //       to complete an external suspend request.
2215 //
2216 int JavaThread::java_suspend_self() {
2217   int ret = 0;
2218 
2219   // we are in the process of exiting so don't suspend
2220   if (is_exiting()) {
2221     clear_external_suspend();
2222     return ret;
2223   }
2224 
2225   assert(_anchor.walkable() ||
2226          (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2227          "must have walkable stack");
2228 
2229   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2230 
2231   assert(!this->is_ext_suspended(),
2232          "a thread trying to self-suspend should not already be suspended");
2233 
2234   if (this->is_suspend_equivalent()) {
2235     // If we are self-suspending as a result of the lifting of a
2236     // suspend equivalent condition, then the suspend_equivalent
2237     // flag is not cleared until we set the ext_suspended flag so
2238     // that wait_for_ext_suspend_completion() returns consistent
2239     // results.
2240     this->clear_suspend_equivalent();
2241   }
2242 
2243   // A racing resume may have cancelled us before we grabbed SR_lock
2244   // above. Or another external suspend request could be waiting for us
2245   // by the time we return from SR_lock()->wait(). The thread
2246   // that requested the suspension may already be trying to walk our
2247   // stack and if we return now, we can change the stack out from under
2248   // it. This would be a "bad thing (TM)" and cause the stack walker
2249   // to crash. We stay self-suspended until there are no more pending
2250   // external suspend requests.
2251   while (is_external_suspend()) {
2252     ret++;
2253     this->set_ext_suspended();
2254 
2255     // _ext_suspended flag is cleared by java_resume()
2256     while (is_ext_suspended()) {
2257       this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2258     }
2259   }
2260 
2261   return ret;
2262 }
2263 
2264 #ifdef ASSERT
2265 // verify the JavaThread has not yet been published in the Threads::list, and
2266 // hence doesn't need protection from concurrent access at this stage
2267 void JavaThread::verify_not_published() {
2268   if (!Threads_lock->owned_by_self()) {
2269     MutexLockerEx ml(Threads_lock,  Mutex::_no_safepoint_check_flag);
2270     assert(!Threads::includes(this),
2271            "java thread shouldn't have been published yet!");
2272   } else {
2273     assert(!Threads::includes(this),
2274            "java thread shouldn't have been published yet!");
2275   }
2276 }
2277 #endif
2278 
2279 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2280 // progress or when _suspend_flags is non-zero.
2281 // Current thread needs to self-suspend if there is a suspend request and/or
2282 // block if a safepoint is in progress.
2283 // Async exception ISN'T checked.
2284 // Note only the ThreadInVMfromNative transition can call this function
2285 // directly and when thread state is _thread_in_native_trans
2286 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2287   assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2288 
2289   JavaThread *curJT = JavaThread::current();
2290   bool do_self_suspend = thread->is_external_suspend();
2291 
2292   assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2293 
2294   // If JNIEnv proxies are allowed, don't self-suspend if the target
2295   // thread is not the current thread. In older versions of jdbx, jdbx
2296   // threads could call into the VM with another thread's JNIEnv so we
2297   // can be here operating on behalf of a suspended thread (4432884).
2298   if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2299     JavaThreadState state = thread->thread_state();
2300 
2301     // We mark this thread_blocked state as a suspend-equivalent so
2302     // that a caller to is_ext_suspend_completed() won't be confused.
2303     // The suspend-equivalent state is cleared by java_suspend_self().
2304     thread->set_suspend_equivalent();
2305 
2306     // If the safepoint code sees the _thread_in_native_trans state, it will
2307     // wait until the thread changes to other thread state. There is no
2308     // guarantee on how soon we can obtain the SR_lock and complete the
2309     // self-suspend request. It would be a bad idea to let safepoint wait for
2310     // too long. Temporarily change the state to _thread_blocked to
2311     // let the VM thread know that this thread is ready for GC. The problem
2312     // of changing thread state is that safepoint could happen just after
2313     // java_suspend_self() returns after being resumed, and VM thread will
2314     // see the _thread_blocked state. We must check for safepoint
2315     // after restoring the state and make sure we won't leave while a safepoint
2316     // is in progress.
2317     thread->set_thread_state(_thread_blocked);
2318     thread->java_suspend_self();
2319     thread->set_thread_state(state);
2320     // Make sure new state is seen by VM thread
2321     if (os::is_MP()) {
2322       if (UseMembar) {
2323         // Force a fence between the write above and read below
2324         OrderAccess::fence();
2325       } else {
2326         // Must use this rather than serialization page in particular on Windows
2327         InterfaceSupport::serialize_memory(thread);
2328       }
2329     }
2330   }
2331 
2332   if (SafepointSynchronize::do_call_back()) {
2333     // If we are safepointing, then block the caller which may not be
2334     // the same as the target thread (see above).
2335     SafepointSynchronize::block(curJT);
2336   }
2337 
2338   if (thread->is_deopt_suspend()) {
2339     thread->clear_deopt_suspend();
2340     RegisterMap map(thread, false);
2341     frame f = thread->last_frame();
2342     while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2343       f = f.sender(&map);
2344     }
2345     if (f.id() == thread->must_deopt_id()) {
2346       thread->clear_must_deopt_id();
2347       f.deoptimize(thread);
2348     } else {
2349       fatal("missed deoptimization!");
2350     }
2351   }
2352 }
2353 
2354 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2355 // progress or when _suspend_flags is non-zero.
2356 // Current thread needs to self-suspend if there is a suspend request and/or
2357 // block if a safepoint is in progress.
2358 // Also check for pending async exception (not including unsafe access error).
2359 // Note only the native==>VM/Java barriers can call this function and when
2360 // thread state is _thread_in_native_trans.
2361 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2362   check_safepoint_and_suspend_for_native_trans(thread);
2363 
2364   if (thread->has_async_exception()) {
2365     // We are in _thread_in_native_trans state, don't handle unsafe
2366     // access error since that may block.
2367     thread->check_and_handle_async_exceptions(false);
2368   }
2369 }
2370 
2371 // This is a variant of the normal
2372 // check_special_condition_for_native_trans with slightly different
2373 // semantics for use by critical native wrappers.  It does all the
2374 // normal checks but also performs the transition back into
2375 // thread_in_Java state.  This is required so that critical natives
2376 // can potentially block and perform a GC if they are the last thread
2377 // exiting the GC_locker.
2378 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2379   check_special_condition_for_native_trans(thread);
2380 
2381   // Finish the transition
2382   thread->set_thread_state(_thread_in_Java);
2383 
2384   if (thread->do_critical_native_unlock()) {
2385     ThreadInVMfromJavaNoAsyncException tiv(thread);
2386     GC_locker::unlock_critical(thread);
2387     thread->clear_critical_native_unlock();
2388   }
2389 }
2390 
2391 // We need to guarantee the Threads_lock here, since resumes are not
2392 // allowed during safepoint synchronization
2393 // Can only resume from an external suspension
2394 void JavaThread::java_resume() {
2395   assert_locked_or_safepoint(Threads_lock);
2396 
2397   // Sanity check: thread is gone, has started exiting or the thread
2398   // was not externally suspended.
2399   if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2400     return;
2401   }
2402 
2403   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2404 
2405   clear_external_suspend();
2406 
2407   if (is_ext_suspended()) {
2408     clear_ext_suspended();
2409     SR_lock()->notify_all();
2410   }
2411 }
2412 
2413 void JavaThread::create_stack_guard_pages() {
2414   if (! os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) return;
2415   address low_addr = stack_base() - stack_size();
2416   size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
2417 
2418   int allocate = os::allocate_stack_guard_pages();
2419   // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2420 
2421   if (allocate && !os::create_stack_guard_pages((char *) low_addr, len)) {
2422     warning("Attempt to allocate stack guard pages failed.");
2423     return;
2424   }
2425 
2426   if (os::guard_memory((char *) low_addr, len)) {
2427     _stack_guard_state = stack_guard_enabled;
2428   } else {
2429     warning("Attempt to protect stack guard pages failed.");
2430     if (os::uncommit_memory((char *) low_addr, len)) {
2431       warning("Attempt to deallocate stack guard pages failed.");
2432     }
2433   }
2434 }
2435 
2436 void JavaThread::remove_stack_guard_pages() {
2437   assert(Thread::current() == this, "from different thread");
2438   if (_stack_guard_state == stack_guard_unused) return;
2439   address low_addr = stack_base() - stack_size();
2440   size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
2441 
2442   if (os::allocate_stack_guard_pages()) {
2443     if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2444       _stack_guard_state = stack_guard_unused;
2445     } else {
2446       warning("Attempt to deallocate stack guard pages failed.");
2447     }
2448   } else {
2449     if (_stack_guard_state == stack_guard_unused) return;
2450     if (os::unguard_memory((char *) low_addr, len)) {
2451       _stack_guard_state = stack_guard_unused;
2452     } else {
2453       warning("Attempt to unprotect stack guard pages failed.");
2454     }
2455   }
2456 }
2457 
2458 void JavaThread::enable_stack_yellow_zone() {
2459   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2460   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2461 
2462   // The base notation is from the stacks point of view, growing downward.
2463   // We need to adjust it to work correctly with guard_memory()
2464   address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2465 
2466   guarantee(base < stack_base(), "Error calculating stack yellow zone");
2467   guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2468 
2469   if (os::guard_memory((char *) base, stack_yellow_zone_size())) {
2470     _stack_guard_state = stack_guard_enabled;
2471   } else {
2472     warning("Attempt to guard stack yellow zone failed.");
2473   }
2474   enable_register_stack_guard();
2475 }
2476 
2477 void JavaThread::disable_stack_yellow_zone() {
2478   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2479   assert(_stack_guard_state != stack_guard_yellow_disabled, "already disabled");
2480 
2481   // Simply return if called for a thread that does not use guard pages.
2482   if (_stack_guard_state == stack_guard_unused) return;
2483 
2484   // The base notation is from the stacks point of view, growing downward.
2485   // We need to adjust it to work correctly with guard_memory()
2486   address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2487 
2488   if (os::unguard_memory((char *)base, stack_yellow_zone_size())) {
2489     _stack_guard_state = stack_guard_yellow_disabled;
2490   } else {
2491     warning("Attempt to unguard stack yellow zone failed.");
2492   }
2493   disable_register_stack_guard();
2494 }
2495 
2496 void JavaThread::enable_stack_red_zone() {
2497   // The base notation is from the stacks point of view, growing downward.
2498   // We need to adjust it to work correctly with guard_memory()
2499   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2500   address base = stack_red_zone_base() - stack_red_zone_size();
2501 
2502   guarantee(base < stack_base(), "Error calculating stack red zone");
2503   guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2504 
2505   if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2506     warning("Attempt to guard stack red zone failed.");
2507   }
2508 }
2509 
2510 void JavaThread::disable_stack_red_zone() {
2511   // The base notation is from the stacks point of view, growing downward.
2512   // We need to adjust it to work correctly with guard_memory()
2513   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2514   address base = stack_red_zone_base() - stack_red_zone_size();
2515   if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2516     warning("Attempt to unguard stack red zone failed.");
2517   }
2518 }
2519 
2520 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2521   // ignore is there is no stack
2522   if (!has_last_Java_frame()) return;
2523   // traverse the stack frames. Starts from top frame.
2524   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2525     frame* fr = fst.current();
2526     f(fr, fst.register_map());
2527   }
2528 }
2529 
2530 
2531 #ifndef PRODUCT
2532 // Deoptimization
2533 // Function for testing deoptimization
2534 void JavaThread::deoptimize() {
2535   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2536   StackFrameStream fst(this, UseBiasedLocking);
2537   bool deopt = false;           // Dump stack only if a deopt actually happens.
2538   bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2539   // Iterate over all frames in the thread and deoptimize
2540   for (; !fst.is_done(); fst.next()) {
2541     if (fst.current()->can_be_deoptimized()) {
2542 
2543       if (only_at) {
2544         // Deoptimize only at particular bcis.  DeoptimizeOnlyAt
2545         // consists of comma or carriage return separated numbers so
2546         // search for the current bci in that string.
2547         address pc = fst.current()->pc();
2548         nmethod* nm =  (nmethod*) fst.current()->cb();
2549         ScopeDesc* sd = nm->scope_desc_at(pc);
2550         char buffer[8];
2551         jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2552         size_t len = strlen(buffer);
2553         const char * found = strstr(DeoptimizeOnlyAt, buffer);
2554         while (found != NULL) {
2555           if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2556               (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2557             // Check that the bci found is bracketed by terminators.
2558             break;
2559           }
2560           found = strstr(found + 1, buffer);
2561         }
2562         if (!found) {
2563           continue;
2564         }
2565       }
2566 
2567       if (DebugDeoptimization && !deopt) {
2568         deopt = true; // One-time only print before deopt
2569         tty->print_cr("[BEFORE Deoptimization]");
2570         trace_frames();
2571         trace_stack();
2572       }
2573       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2574     }
2575   }
2576 
2577   if (DebugDeoptimization && deopt) {
2578     tty->print_cr("[AFTER Deoptimization]");
2579     trace_frames();
2580   }
2581 }
2582 
2583 
2584 // Make zombies
2585 void JavaThread::make_zombies() {
2586   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2587     if (fst.current()->can_be_deoptimized()) {
2588       // it is a Java nmethod
2589       nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2590       nm->make_not_entrant();
2591     }
2592   }
2593 }
2594 #endif // PRODUCT
2595 
2596 
2597 void JavaThread::deoptimized_wrt_marked_nmethods() {
2598   if (!has_last_Java_frame()) return;
2599   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2600   StackFrameStream fst(this, UseBiasedLocking);
2601   for (; !fst.is_done(); fst.next()) {
2602     if (fst.current()->should_be_deoptimized()) {
2603       if (LogCompilation && xtty != NULL) {
2604         nmethod* nm = fst.current()->cb()->as_nmethod_or_null();
2605         xtty->elem("deoptimized thread='" UINTX_FORMAT "' compile_id='%d'",
2606                    this->name(), nm != NULL ? nm->compile_id() : -1);
2607       }
2608 
2609       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2610     }
2611   }
2612 }
2613 
2614 
2615 // If the caller is a NamedThread, then remember, in the current scope,
2616 // the given JavaThread in its _processed_thread field.
2617 class RememberProcessedThread: public StackObj {
2618   NamedThread* _cur_thr;
2619  public:
2620   RememberProcessedThread(JavaThread* jthr) {
2621     Thread* thread = Thread::current();
2622     if (thread->is_Named_thread()) {
2623       _cur_thr = (NamedThread *)thread;
2624       _cur_thr->set_processed_thread(jthr);
2625     } else {
2626       _cur_thr = NULL;
2627     }
2628   }
2629 
2630   ~RememberProcessedThread() {
2631     if (_cur_thr) {
2632       _cur_thr->set_processed_thread(NULL);
2633     }
2634   }
2635 };
2636 
2637 void JavaThread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
2638   // Verify that the deferred card marks have been flushed.
2639   assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2640 
2641   // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2642   // since there may be more than one thread using each ThreadProfiler.
2643 
2644   // Traverse the GCHandles
2645   Thread::oops_do(f, cld_f, cf);
2646 
2647   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2648          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2649 
2650   if (has_last_Java_frame()) {
2651     // Record JavaThread to GC thread
2652     RememberProcessedThread rpt(this);
2653 
2654     // Traverse the privileged stack
2655     if (_privileged_stack_top != NULL) {
2656       _privileged_stack_top->oops_do(f);
2657     }
2658 
2659     // traverse the registered growable array
2660     if (_array_for_gc != NULL) {
2661       for (int index = 0; index < _array_for_gc->length(); index++) {
2662         f->do_oop(_array_for_gc->adr_at(index));
2663       }
2664     }
2665 
2666     // Traverse the monitor chunks
2667     for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2668       chunk->oops_do(f);
2669     }
2670 
2671     // Traverse the execution stack
2672     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2673       fst.current()->oops_do(f, cld_f, cf, fst.register_map());
2674     }
2675   }
2676 
2677   // callee_target is never live across a gc point so NULL it here should
2678   // it still contain a methdOop.
2679 
2680   set_callee_target(NULL);
2681 
2682   assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2683   // If we have deferred set_locals there might be oops waiting to be
2684   // written
2685   GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2686   if (list != NULL) {
2687     for (int i = 0; i < list->length(); i++) {
2688       list->at(i)->oops_do(f);
2689     }
2690   }
2691 
2692   // Traverse instance variables at the end since the GC may be moving things
2693   // around using this function
2694   f->do_oop((oop*) &_threadObj);
2695   f->do_oop((oop*) &_vm_result);
2696   f->do_oop((oop*) &_exception_oop);
2697   f->do_oop((oop*) &_pending_async_exception);
2698 
2699   if (jvmti_thread_state() != NULL) {
2700     jvmti_thread_state()->oops_do(f);
2701   }
2702 }
2703 
2704 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2705   Thread::nmethods_do(cf);  // (super method is a no-op)
2706 
2707   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2708          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2709 
2710   if (has_last_Java_frame()) {
2711     // Traverse the execution stack
2712     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2713       fst.current()->nmethods_do(cf);
2714     }
2715   }
2716 }
2717 
2718 void JavaThread::metadata_do(void f(Metadata*)) {
2719   if (has_last_Java_frame()) {
2720     // Traverse the execution stack to call f() on the methods in the stack
2721     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2722       fst.current()->metadata_do(f);
2723     }
2724   } else if (is_Compiler_thread()) {
2725     // need to walk ciMetadata in current compile tasks to keep alive.
2726     CompilerThread* ct = (CompilerThread*)this;
2727     if (ct->env() != NULL) {
2728       ct->env()->metadata_do(f);
2729     }
2730   }
2731 }
2732 
2733 // Printing
2734 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2735   switch (_thread_state) {
2736   case _thread_uninitialized:     return "_thread_uninitialized";
2737   case _thread_new:               return "_thread_new";
2738   case _thread_new_trans:         return "_thread_new_trans";
2739   case _thread_in_native:         return "_thread_in_native";
2740   case _thread_in_native_trans:   return "_thread_in_native_trans";
2741   case _thread_in_vm:             return "_thread_in_vm";
2742   case _thread_in_vm_trans:       return "_thread_in_vm_trans";
2743   case _thread_in_Java:           return "_thread_in_Java";
2744   case _thread_in_Java_trans:     return "_thread_in_Java_trans";
2745   case _thread_blocked:           return "_thread_blocked";
2746   case _thread_blocked_trans:     return "_thread_blocked_trans";
2747   default:                        return "unknown thread state";
2748   }
2749 }
2750 
2751 #ifndef PRODUCT
2752 void JavaThread::print_thread_state_on(outputStream *st) const {
2753   st->print_cr("   JavaThread state: %s", _get_thread_state_name(_thread_state));
2754 };
2755 void JavaThread::print_thread_state() const {
2756   print_thread_state_on(tty);
2757 }
2758 #endif // PRODUCT
2759 
2760 // Called by Threads::print() for VM_PrintThreads operation
2761 void JavaThread::print_on(outputStream *st) const {
2762   st->print("\"%s\" ", get_thread_name());
2763   oop thread_oop = threadObj();
2764   if (thread_oop != NULL) {
2765     st->print("#" INT64_FORMAT " ", java_lang_Thread::thread_id(thread_oop));
2766     if (java_lang_Thread::is_daemon(thread_oop))  st->print("daemon ");
2767     st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2768   }
2769   Thread::print_on(st);
2770   // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2771   st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2772   if (thread_oop != NULL) {
2773     st->print_cr("   java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2774   }
2775 #ifndef PRODUCT
2776   print_thread_state_on(st);
2777   _safepoint_state->print_on(st);
2778 #endif // PRODUCT
2779 }
2780 
2781 // Called by fatal error handler. The difference between this and
2782 // JavaThread::print() is that we can't grab lock or allocate memory.
2783 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2784   st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2785   oop thread_obj = threadObj();
2786   if (thread_obj != NULL) {
2787     if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2788   }
2789   st->print(" [");
2790   st->print("%s", _get_thread_state_name(_thread_state));
2791   if (osthread()) {
2792     st->print(", id=%d", osthread()->thread_id());
2793   }
2794   st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2795             _stack_base - _stack_size, _stack_base);
2796   st->print("]");
2797   return;
2798 }
2799 
2800 // Verification
2801 
2802 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2803 
2804 void JavaThread::verify() {
2805   // Verify oops in the thread.
2806   oops_do(&VerifyOopClosure::verify_oop, NULL, NULL);
2807 
2808   // Verify the stack frames.
2809   frames_do(frame_verify);
2810 }
2811 
2812 // CR 6300358 (sub-CR 2137150)
2813 // Most callers of this method assume that it can't return NULL but a
2814 // thread may not have a name whilst it is in the process of attaching to
2815 // the VM - see CR 6412693, and there are places where a JavaThread can be
2816 // seen prior to having it's threadObj set (eg JNI attaching threads and
2817 // if vm exit occurs during initialization). These cases can all be accounted
2818 // for such that this method never returns NULL.
2819 const char* JavaThread::get_thread_name() const {
2820 #ifdef ASSERT
2821   // early safepoints can hit while current thread does not yet have TLS
2822   if (!SafepointSynchronize::is_at_safepoint()) {
2823     Thread *cur = Thread::current();
2824     if (!(cur->is_Java_thread() && cur == this)) {
2825       // Current JavaThreads are allowed to get their own name without
2826       // the Threads_lock.
2827       assert_locked_or_safepoint(Threads_lock);
2828     }
2829   }
2830 #endif // ASSERT
2831   return get_thread_name_string();
2832 }
2833 
2834 // Returns a non-NULL representation of this thread's name, or a suitable
2835 // descriptive string if there is no set name
2836 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
2837   const char* name_str;
2838   oop thread_obj = threadObj();
2839   if (thread_obj != NULL) {
2840     oop name = java_lang_Thread::name(thread_obj);
2841     if (name != NULL) {
2842       if (buf == NULL) {
2843         name_str = java_lang_String::as_utf8_string(name);
2844       } else {
2845         name_str = java_lang_String::as_utf8_string(name, buf, buflen);
2846       }
2847     } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
2848       name_str = "<no-name - thread is attaching>";
2849     } else {
2850       name_str = Thread::name();
2851     }
2852   } else {
2853     name_str = Thread::name();
2854   }
2855   assert(name_str != NULL, "unexpected NULL thread name");
2856   return name_str;
2857 }
2858 
2859 
2860 const char* JavaThread::get_threadgroup_name() const {
2861   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2862   oop thread_obj = threadObj();
2863   if (thread_obj != NULL) {
2864     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2865     if (thread_group != NULL) {
2866       typeArrayOop name = java_lang_ThreadGroup::name(thread_group);
2867       // ThreadGroup.name can be null
2868       if (name != NULL) {
2869         const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2870         return str;
2871       }
2872     }
2873   }
2874   return NULL;
2875 }
2876 
2877 const char* JavaThread::get_parent_name() const {
2878   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2879   oop thread_obj = threadObj();
2880   if (thread_obj != NULL) {
2881     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2882     if (thread_group != NULL) {
2883       oop parent = java_lang_ThreadGroup::parent(thread_group);
2884       if (parent != NULL) {
2885         typeArrayOop name = java_lang_ThreadGroup::name(parent);
2886         // ThreadGroup.name can be null
2887         if (name != NULL) {
2888           const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2889           return str;
2890         }
2891       }
2892     }
2893   }
2894   return NULL;
2895 }
2896 
2897 ThreadPriority JavaThread::java_priority() const {
2898   oop thr_oop = threadObj();
2899   if (thr_oop == NULL) return NormPriority; // Bootstrapping
2900   ThreadPriority priority = java_lang_Thread::priority(thr_oop);
2901   assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
2902   return priority;
2903 }
2904 
2905 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
2906 
2907   assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
2908   // Link Java Thread object <-> C++ Thread
2909 
2910   // Get the C++ thread object (an oop) from the JNI handle (a jthread)
2911   // and put it into a new Handle.  The Handle "thread_oop" can then
2912   // be used to pass the C++ thread object to other methods.
2913 
2914   // Set the Java level thread object (jthread) field of the
2915   // new thread (a JavaThread *) to C++ thread object using the
2916   // "thread_oop" handle.
2917 
2918   // Set the thread field (a JavaThread *) of the
2919   // oop representing the java_lang_Thread to the new thread (a JavaThread *).
2920 
2921   Handle thread_oop(Thread::current(),
2922                     JNIHandles::resolve_non_null(jni_thread));
2923   assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
2924          "must be initialized");
2925   set_threadObj(thread_oop());
2926   java_lang_Thread::set_thread(thread_oop(), this);
2927 
2928   if (prio == NoPriority) {
2929     prio = java_lang_Thread::priority(thread_oop());
2930     assert(prio != NoPriority, "A valid priority should be present");
2931   }
2932 
2933   // Push the Java priority down to the native thread; needs Threads_lock
2934   Thread::set_priority(this, prio);
2935 
2936   prepare_ext();
2937 
2938   // Add the new thread to the Threads list and set it in motion.
2939   // We must have threads lock in order to call Threads::add.
2940   // It is crucial that we do not block before the thread is
2941   // added to the Threads list for if a GC happens, then the java_thread oop
2942   // will not be visited by GC.
2943   Threads::add(this);
2944 }
2945 
2946 oop JavaThread::current_park_blocker() {
2947   // Support for JSR-166 locks
2948   oop thread_oop = threadObj();
2949   if (thread_oop != NULL &&
2950       JDK_Version::current().supports_thread_park_blocker()) {
2951     return java_lang_Thread::park_blocker(thread_oop);
2952   }
2953   return NULL;
2954 }
2955 
2956 
2957 void JavaThread::print_stack_on(outputStream* st) {
2958   if (!has_last_Java_frame()) return;
2959   ResourceMark rm;
2960   HandleMark   hm;
2961 
2962   RegisterMap reg_map(this);
2963   vframe* start_vf = last_java_vframe(&reg_map);
2964   int count = 0;
2965   for (vframe* f = start_vf; f; f = f->sender()) {
2966     if (f->is_java_frame()) {
2967       javaVFrame* jvf = javaVFrame::cast(f);
2968       java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
2969 
2970       // Print out lock information
2971       if (JavaMonitorsInStackTrace) {
2972         jvf->print_lock_info_on(st, count);
2973       }
2974     } else {
2975       // Ignore non-Java frames
2976     }
2977 
2978     // Bail-out case for too deep stacks
2979     count++;
2980     if (MaxJavaStackTraceDepth == count) return;
2981   }
2982 }
2983 
2984 
2985 // JVMTI PopFrame support
2986 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
2987   assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
2988   if (in_bytes(size_in_bytes) != 0) {
2989     _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
2990     _popframe_preserved_args_size = in_bytes(size_in_bytes);
2991     Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
2992   }
2993 }
2994 
2995 void* JavaThread::popframe_preserved_args() {
2996   return _popframe_preserved_args;
2997 }
2998 
2999 ByteSize JavaThread::popframe_preserved_args_size() {
3000   return in_ByteSize(_popframe_preserved_args_size);
3001 }
3002 
3003 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3004   int sz = in_bytes(popframe_preserved_args_size());
3005   assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3006   return in_WordSize(sz / wordSize);
3007 }
3008 
3009 void JavaThread::popframe_free_preserved_args() {
3010   assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3011   FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3012   _popframe_preserved_args = NULL;
3013   _popframe_preserved_args_size = 0;
3014 }
3015 
3016 #ifndef PRODUCT
3017 
3018 void JavaThread::trace_frames() {
3019   tty->print_cr("[Describe stack]");
3020   int frame_no = 1;
3021   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3022     tty->print("  %d. ", frame_no++);
3023     fst.current()->print_value_on(tty, this);
3024     tty->cr();
3025   }
3026 }
3027 
3028 class PrintAndVerifyOopClosure: public OopClosure {
3029  protected:
3030   template <class T> inline void do_oop_work(T* p) {
3031     oop obj = oopDesc::load_decode_heap_oop(p);
3032     if (obj == NULL) return;
3033     tty->print(INTPTR_FORMAT ": ", p);
3034     if (obj->is_oop_or_null()) {
3035       if (obj->is_objArray()) {
3036         tty->print_cr("valid objArray: " INTPTR_FORMAT, (oopDesc*) obj);
3037       } else {
3038         obj->print();
3039       }
3040     } else {
3041       tty->print_cr("invalid oop: " INTPTR_FORMAT, (oopDesc*) obj);
3042     }
3043     tty->cr();
3044   }
3045  public:
3046   virtual void do_oop(oop* p) { do_oop_work(p); }
3047   virtual void do_oop(narrowOop* p)  { do_oop_work(p); }
3048 };
3049 
3050 
3051 static void oops_print(frame* f, const RegisterMap *map) {
3052   PrintAndVerifyOopClosure print;
3053   f->print_value();
3054   f->oops_do(&print, NULL, NULL, (RegisterMap*)map);
3055 }
3056 
3057 // Print our all the locations that contain oops and whether they are
3058 // valid or not.  This useful when trying to find the oldest frame
3059 // where an oop has gone bad since the frame walk is from youngest to
3060 // oldest.
3061 void JavaThread::trace_oops() {
3062   tty->print_cr("[Trace oops]");
3063   frames_do(oops_print);
3064 }
3065 
3066 
3067 #ifdef ASSERT
3068 // Print or validate the layout of stack frames
3069 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3070   ResourceMark rm;
3071   PRESERVE_EXCEPTION_MARK;
3072   FrameValues values;
3073   int frame_no = 0;
3074   for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3075     fst.current()->describe(values, ++frame_no);
3076     if (depth == frame_no) break;
3077   }
3078   if (validate_only) {
3079     values.validate();
3080   } else {
3081     tty->print_cr("[Describe stack layout]");
3082     values.print(this);
3083   }
3084 }
3085 #endif
3086 
3087 void JavaThread::trace_stack_from(vframe* start_vf) {
3088   ResourceMark rm;
3089   int vframe_no = 1;
3090   for (vframe* f = start_vf; f; f = f->sender()) {
3091     if (f->is_java_frame()) {
3092       javaVFrame::cast(f)->print_activation(vframe_no++);
3093     } else {
3094       f->print();
3095     }
3096     if (vframe_no > StackPrintLimit) {
3097       tty->print_cr("...<more frames>...");
3098       return;
3099     }
3100   }
3101 }
3102 
3103 
3104 void JavaThread::trace_stack() {
3105   if (!has_last_Java_frame()) return;
3106   ResourceMark rm;
3107   HandleMark   hm;
3108   RegisterMap reg_map(this);
3109   trace_stack_from(last_java_vframe(&reg_map));
3110 }
3111 
3112 
3113 #endif // PRODUCT
3114 
3115 
3116 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3117   assert(reg_map != NULL, "a map must be given");
3118   frame f = last_frame();
3119   for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3120     if (vf->is_java_frame()) return javaVFrame::cast(vf);
3121   }
3122   return NULL;
3123 }
3124 
3125 
3126 Klass* JavaThread::security_get_caller_class(int depth) {
3127   vframeStream vfst(this);
3128   vfst.security_get_caller_frame(depth);
3129   if (!vfst.at_end()) {
3130     return vfst.method()->method_holder();
3131   }
3132   return NULL;
3133 }
3134 
3135 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3136   assert(thread->is_Compiler_thread(), "must be compiler thread");
3137   CompileBroker::compiler_thread_loop();
3138 }
3139 
3140 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3141   NMethodSweeper::sweeper_loop();
3142 }
3143 
3144 // Create a CompilerThread
3145 CompilerThread::CompilerThread(CompileQueue* queue,
3146                                CompilerCounters* counters)
3147                                : JavaThread(&compiler_thread_entry) {
3148   _env   = NULL;
3149   _log   = NULL;
3150   _task  = NULL;
3151   _queue = queue;
3152   _counters = counters;
3153   _buffer_blob = NULL;
3154   _compiler = NULL;
3155 
3156 #ifndef PRODUCT
3157   _ideal_graph_printer = NULL;
3158 #endif
3159 }
3160 
3161 // Create sweeper thread
3162 CodeCacheSweeperThread::CodeCacheSweeperThread()
3163 : JavaThread(&sweeper_thread_entry) {
3164   _scanned_nmethod = NULL;
3165 }
3166 void CodeCacheSweeperThread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
3167   JavaThread::oops_do(f, cld_f, cf);
3168   if (_scanned_nmethod != NULL && cf != NULL) {
3169     // Safepoints can occur when the sweeper is scanning an nmethod so
3170     // process it here to make sure it isn't unloaded in the middle of
3171     // a scan.
3172     cf->do_code_blob(_scanned_nmethod);
3173   }
3174 }
3175 
3176 
3177 // ======= Threads ========
3178 
3179 // The Threads class links together all active threads, and provides
3180 // operations over all threads.  It is protected by its own Mutex
3181 // lock, which is also used in other contexts to protect thread
3182 // operations from having the thread being operated on from exiting
3183 // and going away unexpectedly (e.g., safepoint synchronization)
3184 
3185 JavaThread* Threads::_thread_list = NULL;
3186 int         Threads::_number_of_threads = 0;
3187 int         Threads::_number_of_non_daemon_threads = 0;
3188 int         Threads::_return_code = 0;
3189 int         Threads::_thread_claim_parity = 0;
3190 size_t      JavaThread::_stack_size_at_create = 0;
3191 #ifdef ASSERT
3192 bool        Threads::_vm_complete = false;
3193 #endif
3194 
3195 // All JavaThreads
3196 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
3197 
3198 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3199 void Threads::threads_do(ThreadClosure* tc) {
3200   assert_locked_or_safepoint(Threads_lock);
3201   // ALL_JAVA_THREADS iterates through all JavaThreads
3202   ALL_JAVA_THREADS(p) {
3203     tc->do_thread(p);
3204   }
3205   // Someday we could have a table or list of all non-JavaThreads.
3206   // For now, just manually iterate through them.
3207   tc->do_thread(VMThread::vm_thread());
3208   Universe::heap()->gc_threads_do(tc);
3209   WatcherThread *wt = WatcherThread::watcher_thread();
3210   // Strictly speaking, the following NULL check isn't sufficient to make sure
3211   // the data for WatcherThread is still valid upon being examined. However,
3212   // considering that WatchThread terminates when the VM is on the way to
3213   // exit at safepoint, the chance of the above is extremely small. The right
3214   // way to prevent termination of WatcherThread would be to acquire
3215   // Terminator_lock, but we can't do that without violating the lock rank
3216   // checking in some cases.
3217   if (wt != NULL) {
3218     tc->do_thread(wt);
3219   }
3220 
3221   // If CompilerThreads ever become non-JavaThreads, add them here
3222 }
3223 
3224 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3225   TraceTime timer("Initialize java.lang classes", TraceStartupTime);
3226 
3227   if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3228     create_vm_init_libraries();
3229   }
3230 
3231   initialize_class(vmSymbols::java_lang_String(), CHECK);
3232 
3233   // Initialize java_lang.System (needed before creating the thread)
3234   initialize_class(vmSymbols::java_lang_System(), CHECK);
3235   // The VM creates & returns objects of this class. Make sure it's initialized.
3236   initialize_class(vmSymbols::java_lang_Class(), CHECK);
3237   initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3238   Handle thread_group = create_initial_thread_group(CHECK);
3239   Universe::set_main_thread_group(thread_group());
3240   initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3241   oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3242   main_thread->set_threadObj(thread_object);
3243   // Set thread status to running since main thread has
3244   // been started and running.
3245   java_lang_Thread::set_thread_status(thread_object,
3246                                       java_lang_Thread::RUNNABLE);
3247 
3248   // The VM preresolves methods to these classes. Make sure that they get initialized
3249   initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3250   initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3251   call_initializeSystemClass(CHECK);
3252 
3253   // get the Java runtime name after java.lang.System is initialized
3254   JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3255   JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3256 
3257   // an instance of OutOfMemory exception has been allocated earlier
3258   initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3259   initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3260   initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3261   initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3262   initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3263   initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3264   initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3265   initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3266 }
3267 
3268 void Threads::initialize_jsr292_core_classes(TRAPS) {
3269   initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3270   initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3271   initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3272 }
3273 
3274 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3275   extern void JDK_Version_init();
3276 
3277   // Check version
3278   if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3279 
3280   // Initialize the output stream module
3281   ostream_init();
3282 
3283   // Process java launcher properties.
3284   Arguments::process_sun_java_launcher_properties(args);
3285 
3286   // Initialize the os module before using TLS
3287   os::init();
3288 
3289   // Initialize system properties.
3290   Arguments::init_system_properties();
3291 
3292   // So that JDK version can be used as a discriminator when parsing arguments
3293   JDK_Version_init();
3294 
3295   // Update/Initialize System properties after JDK version number is known
3296   Arguments::init_version_specific_system_properties();
3297 
3298   // Parse arguments
3299   jint parse_result = Arguments::parse(args);
3300   if (parse_result != JNI_OK) return parse_result;
3301 
3302   os::init_before_ergo();
3303 
3304   jint ergo_result = Arguments::apply_ergo();
3305   if (ergo_result != JNI_OK) return ergo_result;
3306 
3307   // Final check of all arguments after ergonomics which may change values.
3308   if (!CommandLineFlags::check_all_ranges_and_constraints()) {
3309     return JNI_EINVAL;
3310   }
3311 
3312   if (PauseAtStartup) {
3313     os::pause();
3314   }
3315 
3316   HOTSPOT_VM_INIT_BEGIN();
3317 
3318   // Record VM creation timing statistics
3319   TraceVmCreationTime create_vm_timer;
3320   create_vm_timer.start();
3321 
3322   // Timing (must come after argument parsing)
3323   TraceTime timer("Create VM", TraceStartupTime);
3324 
3325   // Initialize the os module after parsing the args
3326   jint os_init_2_result = os::init_2();
3327   if (os_init_2_result != JNI_OK) return os_init_2_result;
3328 
3329   jint adjust_after_os_result = Arguments::adjust_after_os();
3330   if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3331 
3332   // initialize TLS
3333   ThreadLocalStorage::init();
3334 
3335   // Initialize output stream logging
3336   ostream_init_log();
3337 
3338   // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3339   // Must be before create_vm_init_agents()
3340   if (Arguments::init_libraries_at_startup()) {
3341     convert_vm_init_libraries_to_agents();
3342   }
3343 
3344   // Launch -agentlib/-agentpath and converted -Xrun agents
3345   if (Arguments::init_agents_at_startup()) {
3346     create_vm_init_agents();
3347   }
3348 
3349   // Initialize Threads state
3350   _thread_list = NULL;
3351   _number_of_threads = 0;
3352   _number_of_non_daemon_threads = 0;
3353 
3354   // Initialize global data structures and create system classes in heap
3355   vm_init_globals();
3356 
3357   // Attach the main thread to this os thread
3358   JavaThread* main_thread = new JavaThread();
3359   main_thread->set_thread_state(_thread_in_vm);
3360   // must do this before set_active_handles and initialize_thread_local_storage
3361   // Note: on solaris initialize_thread_local_storage() will (indirectly)
3362   // change the stack size recorded here to one based on the java thread
3363   // stacksize. This adjusted size is what is used to figure the placement
3364   // of the guard pages.
3365   main_thread->record_stack_base_and_size();
3366   main_thread->initialize_thread_local_storage();
3367 
3368   main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3369 
3370   if (!main_thread->set_as_starting_thread()) {
3371     vm_shutdown_during_initialization(
3372                                       "Failed necessary internal allocation. Out of swap space");
3373     delete main_thread;
3374     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3375     return JNI_ENOMEM;
3376   }
3377 
3378   // Enable guard page *after* os::create_main_thread(), otherwise it would
3379   // crash Linux VM, see notes in os_linux.cpp.
3380   main_thread->create_stack_guard_pages();
3381 
3382   // Initialize Java-Level synchronization subsystem
3383   ObjectMonitor::Initialize();
3384 
3385   // Initialize global modules
3386   jint status = init_globals();
3387   if (status != JNI_OK) {
3388     delete main_thread;
3389     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3390     return status;
3391   }
3392 
3393   // Should be done after the heap is fully created
3394   main_thread->cache_global_variables();
3395 
3396   HandleMark hm;
3397 
3398   { MutexLocker mu(Threads_lock);
3399     Threads::add(main_thread);
3400   }
3401 
3402   // Any JVMTI raw monitors entered in onload will transition into
3403   // real raw monitor. VM is setup enough here for raw monitor enter.
3404   JvmtiExport::transition_pending_onload_raw_monitors();
3405 
3406   // Create the VMThread
3407   { TraceTime timer("Start VMThread", TraceStartupTime);
3408     VMThread::create();
3409     Thread* vmthread = VMThread::vm_thread();
3410 
3411     if (!os::create_thread(vmthread, os::vm_thread)) {
3412       vm_exit_during_initialization("Cannot create VM thread. "
3413                                     "Out of system resources.");
3414     }
3415 
3416     // Wait for the VM thread to become ready, and VMThread::run to initialize
3417     // Monitors can have spurious returns, must always check another state flag
3418     {
3419       MutexLocker ml(Notify_lock);
3420       os::start_thread(vmthread);
3421       while (vmthread->active_handles() == NULL) {
3422         Notify_lock->wait();
3423       }
3424     }
3425   }
3426 
3427   assert(Universe::is_fully_initialized(), "not initialized");
3428   if (VerifyDuringStartup) {
3429     // Make sure we're starting with a clean slate.
3430     VM_Verify verify_op;
3431     VMThread::execute(&verify_op);
3432   }
3433 
3434   Thread* THREAD = Thread::current();
3435 
3436   // At this point, the Universe is initialized, but we have not executed
3437   // any byte code.  Now is a good time (the only time) to dump out the
3438   // internal state of the JVM for sharing.
3439   if (DumpSharedSpaces) {
3440     MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3441     ShouldNotReachHere();
3442   }
3443 
3444   // Always call even when there are not JVMTI environments yet, since environments
3445   // may be attached late and JVMTI must track phases of VM execution
3446   JvmtiExport::enter_start_phase();
3447 
3448   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3449   JvmtiExport::post_vm_start();
3450 
3451   initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3452 
3453   // We need this for ClassDataSharing - the initial vm.info property is set
3454   // with the default value of CDS "sharing" which may be reset through
3455   // command line options.
3456   reset_vm_info_property(CHECK_JNI_ERR);
3457 
3458   quicken_jni_functions();
3459 
3460   // Must be run after init_ft which initializes ft_enabled
3461   if (TRACE_INITIALIZE() != JNI_OK) {
3462     vm_exit_during_initialization("Failed to initialize tracing backend");
3463   }
3464 
3465   // Set flag that basic initialization has completed. Used by exceptions and various
3466   // debug stuff, that does not work until all basic classes have been initialized.
3467   set_init_completed();
3468 
3469   Metaspace::post_initialize();
3470 
3471   HOTSPOT_VM_INIT_END();
3472 
3473   // record VM initialization completion time
3474 #if INCLUDE_MANAGEMENT
3475   Management::record_vm_init_completed();
3476 #endif // INCLUDE_MANAGEMENT
3477 
3478   // Compute system loader. Note that this has to occur after set_init_completed, since
3479   // valid exceptions may be thrown in the process.
3480   // Note that we do not use CHECK_0 here since we are inside an EXCEPTION_MARK and
3481   // set_init_completed has just been called, causing exceptions not to be shortcut
3482   // anymore. We call vm_exit_during_initialization directly instead.
3483   SystemDictionary::compute_java_system_loader(CHECK_JNI_ERR);
3484 
3485 #if INCLUDE_ALL_GCS
3486   // Support for ConcurrentMarkSweep. This should be cleaned up
3487   // and better encapsulated. The ugly nested if test would go away
3488   // once things are properly refactored. XXX YSR
3489   if (UseConcMarkSweepGC || UseG1GC) {
3490     if (UseConcMarkSweepGC) {
3491       ConcurrentMarkSweepThread::makeSurrogateLockerThread(CHECK_JNI_ERR);
3492     } else {
3493       ConcurrentMarkThread::makeSurrogateLockerThread(CHECK_JNI_ERR);
3494     }
3495   }
3496 #endif // INCLUDE_ALL_GCS
3497 
3498   // Always call even when there are not JVMTI environments yet, since environments
3499   // may be attached late and JVMTI must track phases of VM execution
3500   JvmtiExport::enter_live_phase();
3501 
3502   // Signal Dispatcher needs to be started before VMInit event is posted
3503   os::signal_init();
3504 
3505   // Start Attach Listener if +StartAttachListener or it can't be started lazily
3506   if (!DisableAttachMechanism) {
3507     AttachListener::vm_start();
3508     if (StartAttachListener || AttachListener::init_at_startup()) {
3509       AttachListener::init();
3510     }
3511   }
3512 
3513   // Launch -Xrun agents
3514   // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3515   // back-end can launch with -Xdebug -Xrunjdwp.
3516   if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3517     create_vm_init_libraries();
3518   }
3519 
3520   // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3521   JvmtiExport::post_vm_initialized();
3522 
3523   if (TRACE_START() != JNI_OK) {
3524     vm_exit_during_initialization("Failed to start tracing backend.");
3525   }
3526 
3527   if (CleanChunkPoolAsync) {
3528     Chunk::start_chunk_pool_cleaner_task();
3529   }
3530 
3531   // initialize compiler(s)
3532 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK)
3533   CompileBroker::compilation_init();
3534 #endif
3535 
3536   // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3537   // It is done after compilers are initialized, because otherwise compilations of
3538   // signature polymorphic MH intrinsics can be missed
3539   // (see SystemDictionary::find_method_handle_intrinsic).
3540   initialize_jsr292_core_classes(CHECK_JNI_ERR);
3541 
3542 #if INCLUDE_MANAGEMENT
3543   Management::initialize(THREAD);
3544 
3545   if (HAS_PENDING_EXCEPTION) {
3546     // management agent fails to start possibly due to
3547     // configuration problem and is responsible for printing
3548     // stack trace if appropriate. Simply exit VM.
3549     vm_exit(1);
3550   }
3551 #endif // INCLUDE_MANAGEMENT
3552 
3553   if (Arguments::has_profile())       FlatProfiler::engage(main_thread, true);
3554   if (MemProfiling)                   MemProfiler::engage();
3555   StatSampler::engage();
3556   if (CheckJNICalls)                  JniPeriodicChecker::engage();
3557 
3558   BiasedLocking::init();
3559 
3560 #if INCLUDE_RTM_OPT
3561   RTMLockingCounters::init();
3562 #endif
3563 
3564   if (JDK_Version::current().post_vm_init_hook_enabled()) {
3565     call_postVMInitHook(THREAD);
3566     // The Java side of PostVMInitHook.run must deal with all
3567     // exceptions and provide means of diagnosis.
3568     if (HAS_PENDING_EXCEPTION) {
3569       CLEAR_PENDING_EXCEPTION;
3570     }
3571   }
3572 
3573   {
3574     MutexLocker ml(PeriodicTask_lock);
3575     // Make sure the WatcherThread can be started by WatcherThread::start()
3576     // or by dynamic enrollment.
3577     WatcherThread::make_startable();
3578     // Start up the WatcherThread if there are any periodic tasks
3579     // NOTE:  All PeriodicTasks should be registered by now. If they
3580     //   aren't, late joiners might appear to start slowly (we might
3581     //   take a while to process their first tick).
3582     if (PeriodicTask::num_tasks() > 0) {
3583       WatcherThread::start();
3584     }
3585   }
3586 
3587   create_vm_timer.end();
3588 #ifdef ASSERT
3589   _vm_complete = true;
3590 #endif
3591   return JNI_OK;
3592 }
3593 
3594 // type for the Agent_OnLoad and JVM_OnLoad entry points
3595 extern "C" {
3596   typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3597 }
3598 // Find a command line agent library and return its entry point for
3599 //         -agentlib:  -agentpath:   -Xrun
3600 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3601 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3602                                     const char *on_load_symbols[],
3603                                     size_t num_symbol_entries) {
3604   OnLoadEntry_t on_load_entry = NULL;
3605   void *library = NULL;
3606 
3607   if (!agent->valid()) {
3608     char buffer[JVM_MAXPATHLEN];
3609     char ebuf[1024] = "";
3610     const char *name = agent->name();
3611     const char *msg = "Could not find agent library ";
3612 
3613     // First check to see if agent is statically linked into executable
3614     if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3615       library = agent->os_lib();
3616     } else if (agent->is_absolute_path()) {
3617       library = os::dll_load(name, ebuf, sizeof ebuf);
3618       if (library == NULL) {
3619         const char *sub_msg = " in absolute path, with error: ";
3620         size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3621         char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3622         jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3623         // If we can't find the agent, exit.
3624         vm_exit_during_initialization(buf, NULL);
3625         FREE_C_HEAP_ARRAY(char, buf);
3626       }
3627     } else {
3628       // Try to load the agent from the standard dll directory
3629       if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(),
3630                              name)) {
3631         library = os::dll_load(buffer, ebuf, sizeof ebuf);
3632       }
3633       if (library == NULL) { // Try the local directory
3634         char ns[1] = {0};
3635         if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) {
3636           library = os::dll_load(buffer, ebuf, sizeof ebuf);
3637         }
3638         if (library == NULL) {
3639           const char *sub_msg = " on the library path, with error: ";
3640           size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3641           char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3642           jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3643           // If we can't find the agent, exit.
3644           vm_exit_during_initialization(buf, NULL);
3645           FREE_C_HEAP_ARRAY(char, buf);
3646         }
3647       }
3648     }
3649     agent->set_os_lib(library);
3650     agent->set_valid();
3651   }
3652 
3653   // Find the OnLoad function.
3654   on_load_entry =
3655     CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
3656                                                           false,
3657                                                           on_load_symbols,
3658                                                           num_symbol_entries));
3659   return on_load_entry;
3660 }
3661 
3662 // Find the JVM_OnLoad entry point
3663 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3664   const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3665   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3666 }
3667 
3668 // Find the Agent_OnLoad entry point
3669 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3670   const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3671   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3672 }
3673 
3674 // For backwards compatibility with -Xrun
3675 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3676 // treated like -agentpath:
3677 // Must be called before agent libraries are created
3678 void Threads::convert_vm_init_libraries_to_agents() {
3679   AgentLibrary* agent;
3680   AgentLibrary* next;
3681 
3682   for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3683     next = agent->next();  // cache the next agent now as this agent may get moved off this list
3684     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3685 
3686     // If there is an JVM_OnLoad function it will get called later,
3687     // otherwise see if there is an Agent_OnLoad
3688     if (on_load_entry == NULL) {
3689       on_load_entry = lookup_agent_on_load(agent);
3690       if (on_load_entry != NULL) {
3691         // switch it to the agent list -- so that Agent_OnLoad will be called,
3692         // JVM_OnLoad won't be attempted and Agent_OnUnload will
3693         Arguments::convert_library_to_agent(agent);
3694       } else {
3695         vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3696       }
3697     }
3698   }
3699 }
3700 
3701 // Create agents for -agentlib:  -agentpath:  and converted -Xrun
3702 // Invokes Agent_OnLoad
3703 // Called very early -- before JavaThreads exist
3704 void Threads::create_vm_init_agents() {
3705   extern struct JavaVM_ main_vm;
3706   AgentLibrary* agent;
3707 
3708   JvmtiExport::enter_onload_phase();
3709 
3710   for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3711     OnLoadEntry_t  on_load_entry = lookup_agent_on_load(agent);
3712 
3713     if (on_load_entry != NULL) {
3714       // Invoke the Agent_OnLoad function
3715       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3716       if (err != JNI_OK) {
3717         vm_exit_during_initialization("agent library failed to init", agent->name());
3718       }
3719     } else {
3720       vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
3721     }
3722   }
3723   JvmtiExport::enter_primordial_phase();
3724 }
3725 
3726 extern "C" {
3727   typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
3728 }
3729 
3730 void Threads::shutdown_vm_agents() {
3731   // Send any Agent_OnUnload notifications
3732   const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
3733   size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
3734   extern struct JavaVM_ main_vm;
3735   for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3736 
3737     // Find the Agent_OnUnload function.
3738     Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
3739                                                    os::find_agent_function(agent,
3740                                                    false,
3741                                                    on_unload_symbols,
3742                                                    num_symbol_entries));
3743 
3744     // Invoke the Agent_OnUnload function
3745     if (unload_entry != NULL) {
3746       JavaThread* thread = JavaThread::current();
3747       ThreadToNativeFromVM ttn(thread);
3748       HandleMark hm(thread);
3749       (*unload_entry)(&main_vm);
3750     }
3751   }
3752 }
3753 
3754 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
3755 // Invokes JVM_OnLoad
3756 void Threads::create_vm_init_libraries() {
3757   extern struct JavaVM_ main_vm;
3758   AgentLibrary* agent;
3759 
3760   for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
3761     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3762 
3763     if (on_load_entry != NULL) {
3764       // Invoke the JVM_OnLoad function
3765       JavaThread* thread = JavaThread::current();
3766       ThreadToNativeFromVM ttn(thread);
3767       HandleMark hm(thread);
3768       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3769       if (err != JNI_OK) {
3770         vm_exit_during_initialization("-Xrun library failed to init", agent->name());
3771       }
3772     } else {
3773       vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
3774     }
3775   }
3776 }
3777 
3778 JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) {
3779   assert(Threads_lock->owned_by_self(), "Must hold Threads_lock");
3780 
3781   JavaThread* java_thread = NULL;
3782   // Sequential search for now.  Need to do better optimization later.
3783   for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) {
3784     oop tobj = thread->threadObj();
3785     if (!thread->is_exiting() &&
3786         tobj != NULL &&
3787         java_tid == java_lang_Thread::thread_id(tobj)) {
3788       java_thread = thread;
3789       break;
3790     }
3791   }
3792   return java_thread;
3793 }
3794 
3795 
3796 // Last thread running calls java.lang.Shutdown.shutdown()
3797 void JavaThread::invoke_shutdown_hooks() {
3798   HandleMark hm(this);
3799 
3800   // We could get here with a pending exception, if so clear it now.
3801   if (this->has_pending_exception()) {
3802     this->clear_pending_exception();
3803   }
3804 
3805   EXCEPTION_MARK;
3806   Klass* k =
3807     SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
3808                                       THREAD);
3809   if (k != NULL) {
3810     // SystemDictionary::resolve_or_null will return null if there was
3811     // an exception.  If we cannot load the Shutdown class, just don't
3812     // call Shutdown.shutdown() at all.  This will mean the shutdown hooks
3813     // and finalizers (if runFinalizersOnExit is set) won't be run.
3814     // Note that if a shutdown hook was registered or runFinalizersOnExit
3815     // was called, the Shutdown class would have already been loaded
3816     // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
3817     instanceKlassHandle shutdown_klass (THREAD, k);
3818     JavaValue result(T_VOID);
3819     JavaCalls::call_static(&result,
3820                            shutdown_klass,
3821                            vmSymbols::shutdown_method_name(),
3822                            vmSymbols::void_method_signature(),
3823                            THREAD);
3824   }
3825   CLEAR_PENDING_EXCEPTION;
3826 }
3827 
3828 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
3829 // the program falls off the end of main(). Another VM exit path is through
3830 // vm_exit() when the program calls System.exit() to return a value or when
3831 // there is a serious error in VM. The two shutdown paths are not exactly
3832 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
3833 // and VM_Exit op at VM level.
3834 //
3835 // Shutdown sequence:
3836 //   + Shutdown native memory tracking if it is on
3837 //   + Wait until we are the last non-daemon thread to execute
3838 //     <-- every thing is still working at this moment -->
3839 //   + Call java.lang.Shutdown.shutdown(), which will invoke Java level
3840 //        shutdown hooks, run finalizers if finalization-on-exit
3841 //   + Call before_exit(), prepare for VM exit
3842 //      > run VM level shutdown hooks (they are registered through JVM_OnExit(),
3843 //        currently the only user of this mechanism is File.deleteOnExit())
3844 //      > stop flat profiler, StatSampler, watcher thread, CMS threads,
3845 //        post thread end and vm death events to JVMTI,
3846 //        stop signal thread
3847 //   + Call JavaThread::exit(), it will:
3848 //      > release JNI handle blocks, remove stack guard pages
3849 //      > remove this thread from Threads list
3850 //     <-- no more Java code from this thread after this point -->
3851 //   + Stop VM thread, it will bring the remaining VM to a safepoint and stop
3852 //     the compiler threads at safepoint
3853 //     <-- do not use anything that could get blocked by Safepoint -->
3854 //   + Disable tracing at JNI/JVM barriers
3855 //   + Set _vm_exited flag for threads that are still running native code
3856 //   + Delete this thread
3857 //   + Call exit_globals()
3858 //      > deletes tty
3859 //      > deletes PerfMemory resources
3860 //   + Return to caller
3861 
3862 bool Threads::destroy_vm() {
3863   JavaThread* thread = JavaThread::current();
3864 
3865 #ifdef ASSERT
3866   _vm_complete = false;
3867 #endif
3868   // Wait until we are the last non-daemon thread to execute
3869   { MutexLocker nu(Threads_lock);
3870     while (Threads::number_of_non_daemon_threads() > 1)
3871       // This wait should make safepoint checks, wait without a timeout,
3872       // and wait as a suspend-equivalent condition.
3873       //
3874       // Note: If the FlatProfiler is running and this thread is waiting
3875       // for another non-daemon thread to finish, then the FlatProfiler
3876       // is waiting for the external suspend request on this thread to
3877       // complete. wait_for_ext_suspend_completion() will eventually
3878       // timeout, but that takes time. Making this wait a suspend-
3879       // equivalent condition solves that timeout problem.
3880       //
3881       Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
3882                          Mutex::_as_suspend_equivalent_flag);
3883   }
3884 
3885   // Hang forever on exit if we are reporting an error.
3886   if (ShowMessageBoxOnError && is_error_reported()) {
3887     os::infinite_sleep();
3888   }
3889   os::wait_for_keypress_at_exit();
3890 
3891   // run Java level shutdown hooks
3892   thread->invoke_shutdown_hooks();
3893 
3894   before_exit(thread);
3895 
3896   thread->exit(true);
3897 
3898   // Stop VM thread.
3899   {
3900     // 4945125 The vm thread comes to a safepoint during exit.
3901     // GC vm_operations can get caught at the safepoint, and the
3902     // heap is unparseable if they are caught. Grab the Heap_lock
3903     // to prevent this. The GC vm_operations will not be able to
3904     // queue until after the vm thread is dead. After this point,
3905     // we'll never emerge out of the safepoint before the VM exits.
3906 
3907     MutexLocker ml(Heap_lock);
3908 
3909     VMThread::wait_for_vm_thread_exit();
3910     assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
3911     VMThread::destroy();
3912   }
3913 
3914   // clean up ideal graph printers
3915 #if defined(COMPILER2) && !defined(PRODUCT)
3916   IdealGraphPrinter::clean_up();
3917 #endif
3918 
3919   // Now, all Java threads are gone except daemon threads. Daemon threads
3920   // running Java code or in VM are stopped by the Safepoint. However,
3921   // daemon threads executing native code are still running.  But they
3922   // will be stopped at native=>Java/VM barriers. Note that we can't
3923   // simply kill or suspend them, as it is inherently deadlock-prone.
3924 
3925 #ifndef PRODUCT
3926   // disable function tracing at JNI/JVM barriers
3927   TraceJNICalls = false;
3928   TraceJVMCalls = false;
3929   TraceRuntimeCalls = false;
3930 #endif
3931 
3932   VM_Exit::set_vm_exited();
3933 
3934   notify_vm_shutdown();
3935 
3936   delete thread;
3937 
3938   // exit_globals() will delete tty
3939   exit_globals();
3940 
3941   return true;
3942 }
3943 
3944 
3945 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
3946   if (version == JNI_VERSION_1_1) return JNI_TRUE;
3947   return is_supported_jni_version(version);
3948 }
3949 
3950 
3951 jboolean Threads::is_supported_jni_version(jint version) {
3952   if (version == JNI_VERSION_1_2) return JNI_TRUE;
3953   if (version == JNI_VERSION_1_4) return JNI_TRUE;
3954   if (version == JNI_VERSION_1_6) return JNI_TRUE;
3955   if (version == JNI_VERSION_1_8) return JNI_TRUE;
3956   return JNI_FALSE;
3957 }
3958 
3959 
3960 void Threads::add(JavaThread* p, bool force_daemon) {
3961   // The threads lock must be owned at this point
3962   assert_locked_or_safepoint(Threads_lock);
3963 
3964   // See the comment for this method in thread.hpp for its purpose and
3965   // why it is called here.
3966   p->initialize_queues();
3967   p->set_next(_thread_list);
3968   _thread_list = p;
3969   _number_of_threads++;
3970   oop threadObj = p->threadObj();
3971   bool daemon = true;
3972   // Bootstrapping problem: threadObj can be null for initial
3973   // JavaThread (or for threads attached via JNI)
3974   if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
3975     _number_of_non_daemon_threads++;
3976     daemon = false;
3977   }
3978 
3979   ThreadService::add_thread(p, daemon);
3980 
3981   // Possible GC point.
3982   Events::log(p, "Thread added: " INTPTR_FORMAT, p);
3983 }
3984 
3985 void Threads::remove(JavaThread* p) {
3986   // Extra scope needed for Thread_lock, so we can check
3987   // that we do not remove thread without safepoint code notice
3988   { MutexLocker ml(Threads_lock);
3989 
3990     assert(includes(p), "p must be present");
3991 
3992     JavaThread* current = _thread_list;
3993     JavaThread* prev    = NULL;
3994 
3995     while (current != p) {
3996       prev    = current;
3997       current = current->next();
3998     }
3999 
4000     if (prev) {
4001       prev->set_next(current->next());
4002     } else {
4003       _thread_list = p->next();
4004     }
4005     _number_of_threads--;
4006     oop threadObj = p->threadObj();
4007     bool daemon = true;
4008     if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4009       _number_of_non_daemon_threads--;
4010       daemon = false;
4011 
4012       // Only one thread left, do a notify on the Threads_lock so a thread waiting
4013       // on destroy_vm will wake up.
4014       if (number_of_non_daemon_threads() == 1) {
4015         Threads_lock->notify_all();
4016       }
4017     }
4018     ThreadService::remove_thread(p, daemon);
4019 
4020     // Make sure that safepoint code disregard this thread. This is needed since
4021     // the thread might mess around with locks after this point. This can cause it
4022     // to do callbacks into the safepoint code. However, the safepoint code is not aware
4023     // of this thread since it is removed from the queue.
4024     p->set_terminated_value();
4025   } // unlock Threads_lock
4026 
4027   // Since Events::log uses a lock, we grab it outside the Threads_lock
4028   Events::log(p, "Thread exited: " INTPTR_FORMAT, p);
4029 }
4030 
4031 // Threads_lock must be held when this is called (or must be called during a safepoint)
4032 bool Threads::includes(JavaThread* p) {
4033   assert(Threads_lock->is_locked(), "sanity check");
4034   ALL_JAVA_THREADS(q) {
4035     if (q == p) {
4036       return true;
4037     }
4038   }
4039   return false;
4040 }
4041 
4042 // Operations on the Threads list for GC.  These are not explicitly locked,
4043 // but the garbage collector must provide a safe context for them to run.
4044 // In particular, these things should never be called when the Threads_lock
4045 // is held by some other thread. (Note: the Safepoint abstraction also
4046 // uses the Threads_lock to guarantee this property. It also makes sure that
4047 // all threads gets blocked when exiting or starting).
4048 
4049 void Threads::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
4050   ALL_JAVA_THREADS(p) {
4051     p->oops_do(f, cld_f, cf);
4052   }
4053   VMThread::vm_thread()->oops_do(f, cld_f, cf);
4054 }
4055 
4056 void Threads::change_thread_claim_parity() {
4057   // Set the new claim parity.
4058   assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4059          "Not in range.");
4060   _thread_claim_parity++;
4061   if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4062   assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4063          "Not in range.");
4064 }
4065 
4066 #ifdef ASSERT
4067 void Threads::assert_all_threads_claimed() {
4068   ALL_JAVA_THREADS(p) {
4069     const int thread_parity = p->oops_do_parity();
4070     assert((thread_parity == _thread_claim_parity),
4071         err_msg("Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity));
4072   }
4073 }
4074 #endif // ASSERT
4075 
4076 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
4077   int cp = Threads::thread_claim_parity();
4078   ALL_JAVA_THREADS(p) {
4079     if (p->claim_oops_do(is_par, cp)) {
4080       p->oops_do(f, cld_f, cf);
4081     }
4082   }
4083   VMThread* vmt = VMThread::vm_thread();
4084   if (vmt->claim_oops_do(is_par, cp)) {
4085     vmt->oops_do(f, cld_f, cf);
4086   }
4087 }
4088 
4089 #if INCLUDE_ALL_GCS
4090 // Used by ParallelScavenge
4091 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4092   ALL_JAVA_THREADS(p) {
4093     q->enqueue(new ThreadRootsTask(p));
4094   }
4095   q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4096 }
4097 
4098 // Used by Parallel Old
4099 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4100   ALL_JAVA_THREADS(p) {
4101     q->enqueue(new ThreadRootsMarkingTask(p));
4102   }
4103   q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4104 }
4105 #endif // INCLUDE_ALL_GCS
4106 
4107 void Threads::nmethods_do(CodeBlobClosure* cf) {
4108   ALL_JAVA_THREADS(p) {
4109     p->nmethods_do(cf);
4110   }
4111   VMThread::vm_thread()->nmethods_do(cf);
4112 }
4113 
4114 void Threads::metadata_do(void f(Metadata*)) {
4115   ALL_JAVA_THREADS(p) {
4116     p->metadata_do(f);
4117   }
4118 }
4119 
4120 class ThreadHandlesClosure : public ThreadClosure {
4121   void (*_f)(Metadata*);
4122  public:
4123   ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4124   virtual void do_thread(Thread* thread) {
4125     thread->metadata_handles_do(_f);
4126   }
4127 };
4128 
4129 void Threads::metadata_handles_do(void f(Metadata*)) {
4130   // Only walk the Handles in Thread.
4131   ThreadHandlesClosure handles_closure(f);
4132   threads_do(&handles_closure);
4133 }
4134 
4135 void Threads::deoptimized_wrt_marked_nmethods() {
4136   ALL_JAVA_THREADS(p) {
4137     p->deoptimized_wrt_marked_nmethods();
4138   }
4139 }
4140 
4141 
4142 // Get count Java threads that are waiting to enter the specified monitor.
4143 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
4144                                                          address monitor,
4145                                                          bool doLock) {
4146   assert(doLock || SafepointSynchronize::is_at_safepoint(),
4147          "must grab Threads_lock or be at safepoint");
4148   GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4149 
4150   int i = 0;
4151   {
4152     MutexLockerEx ml(doLock ? Threads_lock : NULL);
4153     ALL_JAVA_THREADS(p) {
4154       if (p->is_Compiler_thread()) continue;
4155 
4156       address pending = (address)p->current_pending_monitor();
4157       if (pending == monitor) {             // found a match
4158         if (i < count) result->append(p);   // save the first count matches
4159         i++;
4160       }
4161     }
4162   }
4163   return result;
4164 }
4165 
4166 
4167 JavaThread *Threads::owning_thread_from_monitor_owner(address owner,
4168                                                       bool doLock) {
4169   assert(doLock ||
4170          Threads_lock->owned_by_self() ||
4171          SafepointSynchronize::is_at_safepoint(),
4172          "must grab Threads_lock or be at safepoint");
4173 
4174   // NULL owner means not locked so we can skip the search
4175   if (owner == NULL) return NULL;
4176 
4177   {
4178     MutexLockerEx ml(doLock ? Threads_lock : NULL);
4179     ALL_JAVA_THREADS(p) {
4180       // first, see if owner is the address of a Java thread
4181       if (owner == (address)p) return p;
4182     }
4183   }
4184   // Cannot assert on lack of success here since this function may be
4185   // used by code that is trying to report useful problem information
4186   // like deadlock detection.
4187   if (UseHeavyMonitors) return NULL;
4188 
4189   // If we didn't find a matching Java thread and we didn't force use of
4190   // heavyweight monitors, then the owner is the stack address of the
4191   // Lock Word in the owning Java thread's stack.
4192   //
4193   JavaThread* the_owner = NULL;
4194   {
4195     MutexLockerEx ml(doLock ? Threads_lock : NULL);
4196     ALL_JAVA_THREADS(q) {
4197       if (q->is_lock_owned(owner)) {
4198         the_owner = q;
4199         break;
4200       }
4201     }
4202   }
4203   // cannot assert on lack of success here; see above comment
4204   return the_owner;
4205 }
4206 
4207 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4208 void Threads::print_on(outputStream* st, bool print_stacks,
4209                        bool internal_format, bool print_concurrent_locks) {
4210   char buf[32];
4211   st->print_cr("%s", os::local_time_string(buf, sizeof(buf)));
4212 
4213   st->print_cr("Full thread dump %s (%s %s):",
4214                Abstract_VM_Version::vm_name(),
4215                Abstract_VM_Version::vm_release(),
4216                Abstract_VM_Version::vm_info_string());
4217   st->cr();
4218 
4219 #if INCLUDE_SERVICES
4220   // Dump concurrent locks
4221   ConcurrentLocksDump concurrent_locks;
4222   if (print_concurrent_locks) {
4223     concurrent_locks.dump_at_safepoint();
4224   }
4225 #endif // INCLUDE_SERVICES
4226 
4227   ALL_JAVA_THREADS(p) {
4228     ResourceMark rm;
4229     p->print_on(st);
4230     if (print_stacks) {
4231       if (internal_format) {
4232         p->trace_stack();
4233       } else {
4234         p->print_stack_on(st);
4235       }
4236     }
4237     st->cr();
4238 #if INCLUDE_SERVICES
4239     if (print_concurrent_locks) {
4240       concurrent_locks.print_locks_on(p, st);
4241     }
4242 #endif // INCLUDE_SERVICES
4243   }
4244 
4245   VMThread::vm_thread()->print_on(st);
4246   st->cr();
4247   Universe::heap()->print_gc_threads_on(st);
4248   WatcherThread* wt = WatcherThread::watcher_thread();
4249   if (wt != NULL) {
4250     wt->print_on(st);
4251     st->cr();
4252   }
4253   CompileBroker::print_compiler_threads_on(st);
4254   st->flush();
4255 }
4256 
4257 // Threads::print_on_error() is called by fatal error handler. It's possible
4258 // that VM is not at safepoint and/or current thread is inside signal handler.
4259 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4260 // memory (even in resource area), it might deadlock the error handler.
4261 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4262                              int buflen) {
4263   bool found_current = false;
4264   st->print_cr("Java Threads: ( => current thread )");
4265   ALL_JAVA_THREADS(thread) {
4266     bool is_current = (current == thread);
4267     found_current = found_current || is_current;
4268 
4269     st->print("%s", is_current ? "=>" : "  ");
4270 
4271     st->print(PTR_FORMAT, thread);
4272     st->print(" ");
4273     thread->print_on_error(st, buf, buflen);
4274     st->cr();
4275   }
4276   st->cr();
4277 
4278   st->print_cr("Other Threads:");
4279   if (VMThread::vm_thread()) {
4280     bool is_current = (current == VMThread::vm_thread());
4281     found_current = found_current || is_current;
4282     st->print("%s", current == VMThread::vm_thread() ? "=>" : "  ");
4283 
4284     st->print(PTR_FORMAT, VMThread::vm_thread());
4285     st->print(" ");
4286     VMThread::vm_thread()->print_on_error(st, buf, buflen);
4287     st->cr();
4288   }
4289   WatcherThread* wt = WatcherThread::watcher_thread();
4290   if (wt != NULL) {
4291     bool is_current = (current == wt);
4292     found_current = found_current || is_current;
4293     st->print("%s", is_current ? "=>" : "  ");
4294 
4295     st->print(PTR_FORMAT, wt);
4296     st->print(" ");
4297     wt->print_on_error(st, buf, buflen);
4298     st->cr();
4299   }
4300   if (!found_current) {
4301     st->cr();
4302     st->print("=>" PTR_FORMAT " (exited) ", current);
4303     current->print_on_error(st, buf, buflen);
4304     st->cr();
4305   }
4306 }
4307 
4308 // Internal SpinLock and Mutex
4309 // Based on ParkEvent
4310 
4311 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4312 //
4313 // We employ SpinLocks _only for low-contention, fixed-length
4314 // short-duration critical sections where we're concerned
4315 // about native mutex_t or HotSpot Mutex:: latency.
4316 // The mux construct provides a spin-then-block mutual exclusion
4317 // mechanism.
4318 //
4319 // Testing has shown that contention on the ListLock guarding gFreeList
4320 // is common.  If we implement ListLock as a simple SpinLock it's common
4321 // for the JVM to devolve to yielding with little progress.  This is true
4322 // despite the fact that the critical sections protected by ListLock are
4323 // extremely short.
4324 //
4325 // TODO-FIXME: ListLock should be of type SpinLock.
4326 // We should make this a 1st-class type, integrated into the lock
4327 // hierarchy as leaf-locks.  Critically, the SpinLock structure
4328 // should have sufficient padding to avoid false-sharing and excessive
4329 // cache-coherency traffic.
4330 
4331 
4332 typedef volatile int SpinLockT;
4333 
4334 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4335   if (Atomic::cmpxchg (1, adr, 0) == 0) {
4336     return;   // normal fast-path return
4337   }
4338 
4339   // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4340   TEVENT(SpinAcquire - ctx);
4341   int ctr = 0;
4342   int Yields = 0;
4343   for (;;) {
4344     while (*adr != 0) {
4345       ++ctr;
4346       if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4347         if (Yields > 5) {
4348           os::naked_short_sleep(1);
4349         } else {
4350           os::naked_yield();
4351           ++Yields;
4352         }
4353       } else {
4354         SpinPause();
4355       }
4356     }
4357     if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4358   }
4359 }
4360 
4361 void Thread::SpinRelease(volatile int * adr) {
4362   assert(*adr != 0, "invariant");
4363   OrderAccess::fence();      // guarantee at least release consistency.
4364   // Roach-motel semantics.
4365   // It's safe if subsequent LDs and STs float "up" into the critical section,
4366   // but prior LDs and STs within the critical section can't be allowed
4367   // to reorder or float past the ST that releases the lock.
4368   // Loads and stores in the critical section - which appear in program
4369   // order before the store that releases the lock - must also appear
4370   // before the store that releases the lock in memory visibility order.
4371   // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4372   // the ST of 0 into the lock-word which releases the lock, so fence
4373   // more than covers this on all platforms.
4374   *adr = 0;
4375 }
4376 
4377 // muxAcquire and muxRelease:
4378 //
4379 // *  muxAcquire and muxRelease support a single-word lock-word construct.
4380 //    The LSB of the word is set IFF the lock is held.
4381 //    The remainder of the word points to the head of a singly-linked list
4382 //    of threads blocked on the lock.
4383 //
4384 // *  The current implementation of muxAcquire-muxRelease uses its own
4385 //    dedicated Thread._MuxEvent instance.  If we're interested in
4386 //    minimizing the peak number of extant ParkEvent instances then
4387 //    we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4388 //    as certain invariants were satisfied.  Specifically, care would need
4389 //    to be taken with regards to consuming unpark() "permits".
4390 //    A safe rule of thumb is that a thread would never call muxAcquire()
4391 //    if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4392 //    park().  Otherwise the _ParkEvent park() operation in muxAcquire() could
4393 //    consume an unpark() permit intended for monitorenter, for instance.
4394 //    One way around this would be to widen the restricted-range semaphore
4395 //    implemented in park().  Another alternative would be to provide
4396 //    multiple instances of the PlatformEvent() for each thread.  One
4397 //    instance would be dedicated to muxAcquire-muxRelease, for instance.
4398 //
4399 // *  Usage:
4400 //    -- Only as leaf locks
4401 //    -- for short-term locking only as muxAcquire does not perform
4402 //       thread state transitions.
4403 //
4404 // Alternatives:
4405 // *  We could implement muxAcquire and muxRelease with MCS or CLH locks
4406 //    but with parking or spin-then-park instead of pure spinning.
4407 // *  Use Taura-Oyama-Yonenzawa locks.
4408 // *  It's possible to construct a 1-0 lock if we encode the lockword as
4409 //    (List,LockByte).  Acquire will CAS the full lockword while Release
4410 //    will STB 0 into the LockByte.  The 1-0 scheme admits stranding, so
4411 //    acquiring threads use timers (ParkTimed) to detect and recover from
4412 //    the stranding window.  Thread/Node structures must be aligned on 256-byte
4413 //    boundaries by using placement-new.
4414 // *  Augment MCS with advisory back-link fields maintained with CAS().
4415 //    Pictorially:  LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4416 //    The validity of the backlinks must be ratified before we trust the value.
4417 //    If the backlinks are invalid the exiting thread must back-track through the
4418 //    the forward links, which are always trustworthy.
4419 // *  Add a successor indication.  The LockWord is currently encoded as
4420 //    (List, LOCKBIT:1).  We could also add a SUCCBIT or an explicit _succ variable
4421 //    to provide the usual futile-wakeup optimization.
4422 //    See RTStt for details.
4423 // *  Consider schedctl.sc_nopreempt to cover the critical section.
4424 //
4425 
4426 
4427 typedef volatile intptr_t MutexT;      // Mux Lock-word
4428 enum MuxBits { LOCKBIT = 1 };
4429 
4430 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4431   intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4432   if (w == 0) return;
4433   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4434     return;
4435   }
4436 
4437   TEVENT(muxAcquire - Contention);
4438   ParkEvent * const Self = Thread::current()->_MuxEvent;
4439   assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4440   for (;;) {
4441     int its = (os::is_MP() ? 100 : 0) + 1;
4442 
4443     // Optional spin phase: spin-then-park strategy
4444     while (--its >= 0) {
4445       w = *Lock;
4446       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4447         return;
4448       }
4449     }
4450 
4451     Self->reset();
4452     Self->OnList = intptr_t(Lock);
4453     // The following fence() isn't _strictly necessary as the subsequent
4454     // CAS() both serializes execution and ratifies the fetched *Lock value.
4455     OrderAccess::fence();
4456     for (;;) {
4457       w = *Lock;
4458       if ((w & LOCKBIT) == 0) {
4459         if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4460           Self->OnList = 0;   // hygiene - allows stronger asserts
4461           return;
4462         }
4463         continue;      // Interference -- *Lock changed -- Just retry
4464       }
4465       assert(w & LOCKBIT, "invariant");
4466       Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4467       if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4468     }
4469 
4470     while (Self->OnList != 0) {
4471       Self->park();
4472     }
4473   }
4474 }
4475 
4476 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4477   intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4478   if (w == 0) return;
4479   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4480     return;
4481   }
4482 
4483   TEVENT(muxAcquire - Contention);
4484   ParkEvent * ReleaseAfter = NULL;
4485   if (ev == NULL) {
4486     ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4487   }
4488   assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4489   for (;;) {
4490     guarantee(ev->OnList == 0, "invariant");
4491     int its = (os::is_MP() ? 100 : 0) + 1;
4492 
4493     // Optional spin phase: spin-then-park strategy
4494     while (--its >= 0) {
4495       w = *Lock;
4496       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4497         if (ReleaseAfter != NULL) {
4498           ParkEvent::Release(ReleaseAfter);
4499         }
4500         return;
4501       }
4502     }
4503 
4504     ev->reset();
4505     ev->OnList = intptr_t(Lock);
4506     // The following fence() isn't _strictly necessary as the subsequent
4507     // CAS() both serializes execution and ratifies the fetched *Lock value.
4508     OrderAccess::fence();
4509     for (;;) {
4510       w = *Lock;
4511       if ((w & LOCKBIT) == 0) {
4512         if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4513           ev->OnList = 0;
4514           // We call ::Release while holding the outer lock, thus
4515           // artificially lengthening the critical section.
4516           // Consider deferring the ::Release() until the subsequent unlock(),
4517           // after we've dropped the outer lock.
4518           if (ReleaseAfter != NULL) {
4519             ParkEvent::Release(ReleaseAfter);
4520           }
4521           return;
4522         }
4523         continue;      // Interference -- *Lock changed -- Just retry
4524       }
4525       assert(w & LOCKBIT, "invariant");
4526       ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4527       if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4528     }
4529 
4530     while (ev->OnList != 0) {
4531       ev->park();
4532     }
4533   }
4534 }
4535 
4536 // Release() must extract a successor from the list and then wake that thread.
4537 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4538 // similar to that used by ParkEvent::Allocate() and ::Release().  DMR-based
4539 // Release() would :
4540 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4541 // (B) Extract a successor from the private list "in-hand"
4542 // (C) attempt to CAS() the residual back into *Lock over null.
4543 //     If there were any newly arrived threads and the CAS() would fail.
4544 //     In that case Release() would detach the RATs, re-merge the list in-hand
4545 //     with the RATs and repeat as needed.  Alternately, Release() might
4546 //     detach and extract a successor, but then pass the residual list to the wakee.
4547 //     The wakee would be responsible for reattaching and remerging before it
4548 //     competed for the lock.
4549 //
4550 // Both "pop" and DMR are immune from ABA corruption -- there can be
4551 // multiple concurrent pushers, but only one popper or detacher.
4552 // This implementation pops from the head of the list.  This is unfair,
4553 // but tends to provide excellent throughput as hot threads remain hot.
4554 // (We wake recently run threads first).
4555 //
4556 // All paths through muxRelease() will execute a CAS.
4557 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4558 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4559 // executed within the critical section are complete and globally visible before the
4560 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4561 void Thread::muxRelease(volatile intptr_t * Lock)  {
4562   for (;;) {
4563     const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT);
4564     assert(w & LOCKBIT, "invariant");
4565     if (w == LOCKBIT) return;
4566     ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4567     assert(List != NULL, "invariant");
4568     assert(List->OnList == intptr_t(Lock), "invariant");
4569     ParkEvent * const nxt = List->ListNext;
4570     guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4571 
4572     // The following CAS() releases the lock and pops the head element.
4573     // The CAS() also ratifies the previously fetched lock-word value.
4574     if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4575       continue;
4576     }
4577     List->OnList = 0;
4578     OrderAccess::fence();
4579     List->unpark();
4580     return;
4581   }
4582 }
4583 
4584 
4585 void Threads::verify() {
4586   ALL_JAVA_THREADS(p) {
4587     p->verify();
4588   }
4589   VMThread* thread = VMThread::vm_thread();
4590   if (thread != NULL) thread->verify();
4591 }
--- EOF ---