1 /*
   2  * Copyright (c) 1997, 2014, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "classfile/classLoader.hpp"
  27 #include "classfile/javaClasses.hpp"
  28 #include "classfile/systemDictionary.hpp"
  29 #include "classfile/vmSymbols.hpp"
  30 #include "code/codeCache.hpp"
  31 #include "code/scopeDesc.hpp"
  32 #include "compiler/compileBroker.hpp"
  33 #include "interpreter/interpreter.hpp"
  34 #include "interpreter/linkResolver.hpp"
  35 #include "interpreter/oopMapCache.hpp"
  36 #include "jvmtifiles/jvmtiEnv.hpp"
  37 #include "memory/gcLocker.inline.hpp"
  38 #include "memory/metaspaceShared.hpp"
  39 #include "memory/oopFactory.hpp"
  40 #include "memory/universe.inline.hpp"
  41 #include "oops/instanceKlass.hpp"
  42 #include "oops/objArrayOop.hpp"
  43 #include "oops/oop.inline.hpp"
  44 #include "oops/symbol.hpp"
  45 #include "prims/jvm_misc.hpp"
  46 #include "prims/jvmtiExport.hpp"
  47 #include "prims/jvmtiThreadState.hpp"
  48 #include "prims/privilegedStack.hpp"
  49 #include "runtime/arguments.hpp"
  50 #include "runtime/atomic.inline.hpp"
  51 #include "runtime/biasedLocking.hpp"
  52 #include "runtime/deoptimization.hpp"
  53 #include "runtime/fprofiler.hpp"
  54 #include "runtime/frame.inline.hpp"
  55 #include "runtime/init.hpp"
  56 #include "runtime/interfaceSupport.hpp"
  57 #include "runtime/java.hpp"
  58 #include "runtime/javaCalls.hpp"
  59 #include "runtime/jniPeriodicChecker.hpp"
  60 #include "runtime/memprofiler.hpp"
  61 #include "runtime/mutexLocker.hpp"
  62 #include "runtime/objectMonitor.hpp"
  63 #include "runtime/orderAccess.inline.hpp"
  64 #include "runtime/osThread.hpp"
  65 #include "runtime/safepoint.hpp"
  66 #include "runtime/sharedRuntime.hpp"
  67 #include "runtime/statSampler.hpp"
  68 #include "runtime/stubRoutines.hpp"
  69 #include "runtime/sweeper.hpp"
  70 #include "runtime/task.hpp"
  71 #include "runtime/thread.inline.hpp"
  72 #include "runtime/threadCritical.hpp"
  73 #include "runtime/threadLocalStorage.hpp"
  74 #include "runtime/vframe.hpp"
  75 #include "runtime/vframeArray.hpp"
  76 #include "runtime/vframe_hp.hpp"
  77 #include "runtime/vmThread.hpp"
  78 #include "runtime/vm_operations.hpp"
  79 #include "runtime/vm_version.hpp"
  80 #include "services/attachListener.hpp"
  81 #include "services/management.hpp"
  82 #include "services/memTracker.hpp"
  83 #include "services/threadService.hpp"
  84 #include "trace/tracing.hpp"
  85 #include "trace/traceMacros.hpp"
  86 #include "utilities/defaultStream.hpp"
  87 #include "utilities/dtrace.hpp"
  88 #include "utilities/events.hpp"
  89 #include "utilities/preserveException.hpp"
  90 #include "utilities/macros.hpp"
  91 #if INCLUDE_ALL_GCS
  92 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp"
  93 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
  94 #include "gc_implementation/parallelScavenge/pcTasks.hpp"
  95 #endif // INCLUDE_ALL_GCS
  96 #ifdef COMPILER1
  97 #include "c1/c1_Compiler.hpp"
  98 #endif
  99 #ifdef COMPILER2
 100 #include "opto/c2compiler.hpp"
 101 #include "opto/idealGraphPrinter.hpp"
 102 #endif
 103 #if INCLUDE_RTM_OPT
 104 #include "runtime/rtmLocking.hpp"
 105 #endif
 106 
 107 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
 108 
 109 #ifdef DTRACE_ENABLED
 110 
 111 // Only bother with this argument setup if dtrace is available
 112 
 113   #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
 114   #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
 115 
 116   #define DTRACE_THREAD_PROBE(probe, javathread)                           \
 117     {                                                                      \
 118       ResourceMark rm(this);                                               \
 119       int len = 0;                                                         \
 120       const char* name = (javathread)->get_thread_name();                  \
 121       len = strlen(name);                                                  \
 122       HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */               \
 123         (char *) name, len,                                                \
 124         java_lang_Thread::thread_id((javathread)->threadObj()),            \
 125         (uintptr_t) (javathread)->osthread()->thread_id(),                 \
 126         java_lang_Thread::is_daemon((javathread)->threadObj()));           \
 127     }
 128 
 129 #else //  ndef DTRACE_ENABLED
 130 
 131   #define DTRACE_THREAD_PROBE(probe, javathread)
 132 
 133 #endif // ndef DTRACE_ENABLED
 134 
 135 
 136 // Class hierarchy
 137 // - Thread
 138 //   - VMThread
 139 //   - WatcherThread
 140 //   - ConcurrentMarkSweepThread
 141 //   - JavaThread
 142 //     - CompilerThread
 143 
 144 // ======= Thread ========
 145 // Support for forcing alignment of thread objects for biased locking
 146 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
 147   if (UseBiasedLocking) {
 148     const int alignment = markOopDesc::biased_lock_alignment;
 149     size_t aligned_size = size + (alignment - sizeof(intptr_t));
 150     void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
 151                                           : AllocateHeap(aligned_size, flags, CURRENT_PC,
 152                                                          AllocFailStrategy::RETURN_NULL);
 153     void* aligned_addr     = (void*) align_size_up((intptr_t) real_malloc_addr, alignment);
 154     assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
 155            ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
 156            "JavaThread alignment code overflowed allocated storage");
 157     if (TraceBiasedLocking) {
 158       if (aligned_addr != real_malloc_addr) {
 159         tty->print_cr("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
 160                       real_malloc_addr, aligned_addr);
 161       }
 162     }
 163     ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
 164     return aligned_addr;
 165   } else {
 166     return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
 167                        : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
 168   }
 169 }
 170 
 171 void Thread::operator delete(void* p) {
 172   if (UseBiasedLocking) {
 173     void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;
 174     FreeHeap(real_malloc_addr);
 175   } else {
 176     FreeHeap(p);
 177   }
 178 }
 179 
 180 
 181 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
 182 // JavaThread
 183 
 184 
 185 Thread::Thread() {
 186   // stack and get_thread
 187   set_stack_base(NULL);
 188   set_stack_size(0);
 189   set_self_raw_id(0);
 190   set_lgrp_id(-1);
 191 
 192   // allocated data structures
 193   set_osthread(NULL);
 194   set_resource_area(new (mtThread)ResourceArea());
 195   DEBUG_ONLY(_current_resource_mark = NULL;)
 196   set_handle_area(new (mtThread) HandleArea(NULL));
 197   set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
 198   set_active_handles(NULL);
 199   set_free_handle_block(NULL);
 200   set_last_handle_mark(NULL);
 201 
 202   // This initial value ==> never claimed.
 203   _oops_do_parity = 0;
 204 
 205   _metadata_on_stack_buffer = NULL;
 206 
 207   // the handle mark links itself to last_handle_mark
 208   new HandleMark(this);
 209 
 210   // plain initialization
 211   debug_only(_owned_locks = NULL;)
 212   debug_only(_allow_allocation_count = 0;)
 213   NOT_PRODUCT(_allow_safepoint_count = 0;)
 214   NOT_PRODUCT(_skip_gcalot = false;)
 215   _jvmti_env_iteration_count = 0;
 216   set_allocated_bytes(0);
 217   _vm_operation_started_count = 0;
 218   _vm_operation_completed_count = 0;
 219   _current_pending_monitor = NULL;
 220   _current_pending_monitor_is_from_java = true;
 221   _current_waiting_monitor = NULL;
 222   _num_nested_signal = 0;
 223   omFreeList = NULL;
 224   omFreeCount = 0;
 225   omFreeProvision = 32;
 226   omInUseList = NULL;
 227   omInUseCount = 0;
 228 
 229 #ifdef ASSERT
 230   _visited_for_critical_count = false;
 231 #endif
 232 
 233   _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
 234                          Monitor::_safepoint_check_sometimes);
 235   _suspend_flags = 0;
 236 
 237   // thread-specific hashCode stream generator state - Marsaglia shift-xor form
 238   _hashStateX = os::random();
 239   _hashStateY = 842502087;
 240   _hashStateZ = 0x8767;    // (int)(3579807591LL & 0xffff) ;
 241   _hashStateW = 273326509;
 242 
 243   _OnTrap   = 0;
 244   _schedctl = NULL;
 245   _Stalled  = 0;
 246   _TypeTag  = 0x2BAD;
 247 
 248   // Many of the following fields are effectively final - immutable
 249   // Note that nascent threads can't use the Native Monitor-Mutex
 250   // construct until the _MutexEvent is initialized ...
 251   // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
 252   // we might instead use a stack of ParkEvents that we could provision on-demand.
 253   // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
 254   // and ::Release()
 255   _ParkEvent   = ParkEvent::Allocate(this);
 256   _SleepEvent  = ParkEvent::Allocate(this);
 257   _MutexEvent  = ParkEvent::Allocate(this);
 258   _MuxEvent    = ParkEvent::Allocate(this);
 259 
 260 #ifdef CHECK_UNHANDLED_OOPS
 261   if (CheckUnhandledOops) {
 262     _unhandled_oops = new UnhandledOops(this);
 263   }
 264 #endif // CHECK_UNHANDLED_OOPS
 265 #ifdef ASSERT
 266   if (UseBiasedLocking) {
 267     assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
 268     assert(this == _real_malloc_address ||
 269            this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment),
 270            "bug in forced alignment of thread objects");
 271   }
 272 #endif // ASSERT
 273 }
 274 
 275 void Thread::initialize_thread_local_storage() {
 276   // Note: Make sure this method only calls
 277   // non-blocking operations. Otherwise, it might not work
 278   // with the thread-startup/safepoint interaction.
 279 
 280   // During Java thread startup, safepoint code should allow this
 281   // method to complete because it may need to allocate memory to
 282   // store information for the new thread.
 283 
 284   // initialize structure dependent on thread local storage
 285   ThreadLocalStorage::set_thread(this);
 286 }
 287 
 288 void Thread::record_stack_base_and_size() {
 289   set_stack_base(os::current_stack_base());
 290   set_stack_size(os::current_stack_size());
 291   if (is_Java_thread()) {
 292     ((JavaThread*) this)->set_stack_overflow_limit();
 293   }
 294   // CR 7190089: on Solaris, primordial thread's stack is adjusted
 295   // in initialize_thread(). Without the adjustment, stack size is
 296   // incorrect if stack is set to unlimited (ulimit -s unlimited).
 297   // So far, only Solaris has real implementation of initialize_thread().
 298   //
 299   // set up any platform-specific state.
 300   os::initialize_thread(this);
 301 
 302 #if INCLUDE_NMT
 303   // record thread's native stack, stack grows downward
 304   address stack_low_addr = stack_base() - stack_size();
 305   MemTracker::record_thread_stack(stack_low_addr, stack_size());
 306 #endif // INCLUDE_NMT
 307 }
 308 
 309 
 310 Thread::~Thread() {
 311   // Reclaim the objectmonitors from the omFreeList of the moribund thread.
 312   ObjectSynchronizer::omFlush(this);
 313 
 314   EVENT_THREAD_DESTRUCT(this);
 315 
 316   // stack_base can be NULL if the thread is never started or exited before
 317   // record_stack_base_and_size called. Although, we would like to ensure
 318   // that all started threads do call record_stack_base_and_size(), there is
 319   // not proper way to enforce that.
 320 #if INCLUDE_NMT
 321   if (_stack_base != NULL) {
 322     address low_stack_addr = stack_base() - stack_size();
 323     MemTracker::release_thread_stack(low_stack_addr, stack_size());
 324 #ifdef ASSERT
 325     set_stack_base(NULL);
 326 #endif
 327   }
 328 #endif // INCLUDE_NMT
 329 
 330   // deallocate data structures
 331   delete resource_area();
 332   // since the handle marks are using the handle area, we have to deallocated the root
 333   // handle mark before deallocating the thread's handle area,
 334   assert(last_handle_mark() != NULL, "check we have an element");
 335   delete last_handle_mark();
 336   assert(last_handle_mark() == NULL, "check we have reached the end");
 337 
 338   // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
 339   // We NULL out the fields for good hygiene.
 340   ParkEvent::Release(_ParkEvent); _ParkEvent   = NULL;
 341   ParkEvent::Release(_SleepEvent); _SleepEvent  = NULL;
 342   ParkEvent::Release(_MutexEvent); _MutexEvent  = NULL;
 343   ParkEvent::Release(_MuxEvent); _MuxEvent    = NULL;
 344 
 345   delete handle_area();
 346   delete metadata_handles();
 347 
 348   // osthread() can be NULL, if creation of thread failed.
 349   if (osthread() != NULL) os::free_thread(osthread());
 350 
 351   delete _SR_lock;
 352 
 353   // clear thread local storage if the Thread is deleting itself
 354   if (this == Thread::current()) {
 355     ThreadLocalStorage::set_thread(NULL);
 356   } else {
 357     // In the case where we're not the current thread, invalidate all the
 358     // caches in case some code tries to get the current thread or the
 359     // thread that was destroyed, and gets stale information.
 360     ThreadLocalStorage::invalidate_all();
 361   }
 362   CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
 363 }
 364 
 365 // NOTE: dummy function for assertion purpose.
 366 void Thread::run() {
 367   ShouldNotReachHere();
 368 }
 369 
 370 #ifdef ASSERT
 371 // Private method to check for dangling thread pointer
 372 void check_for_dangling_thread_pointer(Thread *thread) {
 373   assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
 374          "possibility of dangling Thread pointer");
 375 }
 376 #endif
 377 
 378 ThreadPriority Thread::get_priority(const Thread* const thread) {
 379   ThreadPriority priority;
 380   // Can return an error!
 381   (void)os::get_priority(thread, priority);
 382   assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
 383   return priority;
 384 }
 385 
 386 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
 387   debug_only(check_for_dangling_thread_pointer(thread);)
 388   // Can return an error!
 389   (void)os::set_priority(thread, priority);
 390 }
 391 
 392 
 393 void Thread::start(Thread* thread) {
 394   // Start is different from resume in that its safety is guaranteed by context or
 395   // being called from a Java method synchronized on the Thread object.
 396   if (!DisableStartThread) {
 397     if (thread->is_Java_thread()) {
 398       // Initialize the thread state to RUNNABLE before starting this thread.
 399       // Can not set it after the thread started because we do not know the
 400       // exact thread state at that time. It could be in MONITOR_WAIT or
 401       // in SLEEPING or some other state.
 402       java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
 403                                           java_lang_Thread::RUNNABLE);
 404     }
 405     os::start_thread(thread);
 406   }
 407 }
 408 
 409 // Enqueue a VM_Operation to do the job for us - sometime later
 410 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
 411   VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
 412   VMThread::execute(vm_stop);
 413 }
 414 
 415 
 416 // Check if an external suspend request has completed (or has been
 417 // cancelled). Returns true if the thread is externally suspended and
 418 // false otherwise.
 419 //
 420 // The bits parameter returns information about the code path through
 421 // the routine. Useful for debugging:
 422 //
 423 // set in is_ext_suspend_completed():
 424 // 0x00000001 - routine was entered
 425 // 0x00000010 - routine return false at end
 426 // 0x00000100 - thread exited (return false)
 427 // 0x00000200 - suspend request cancelled (return false)
 428 // 0x00000400 - thread suspended (return true)
 429 // 0x00001000 - thread is in a suspend equivalent state (return true)
 430 // 0x00002000 - thread is native and walkable (return true)
 431 // 0x00004000 - thread is native_trans and walkable (needed retry)
 432 //
 433 // set in wait_for_ext_suspend_completion():
 434 // 0x00010000 - routine was entered
 435 // 0x00020000 - suspend request cancelled before loop (return false)
 436 // 0x00040000 - thread suspended before loop (return true)
 437 // 0x00080000 - suspend request cancelled in loop (return false)
 438 // 0x00100000 - thread suspended in loop (return true)
 439 // 0x00200000 - suspend not completed during retry loop (return false)
 440 
 441 // Helper class for tracing suspend wait debug bits.
 442 //
 443 // 0x00000100 indicates that the target thread exited before it could
 444 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
 445 // 0x00080000 each indicate a cancelled suspend request so they don't
 446 // count as wait failures either.
 447 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
 448 
 449 class TraceSuspendDebugBits : public StackObj {
 450  private:
 451   JavaThread * jt;
 452   bool         is_wait;
 453   bool         called_by_wait;  // meaningful when !is_wait
 454   uint32_t *   bits;
 455 
 456  public:
 457   TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
 458                         uint32_t *_bits) {
 459     jt             = _jt;
 460     is_wait        = _is_wait;
 461     called_by_wait = _called_by_wait;
 462     bits           = _bits;
 463   }
 464 
 465   ~TraceSuspendDebugBits() {
 466     if (!is_wait) {
 467 #if 1
 468       // By default, don't trace bits for is_ext_suspend_completed() calls.
 469       // That trace is very chatty.
 470       return;
 471 #else
 472       if (!called_by_wait) {
 473         // If tracing for is_ext_suspend_completed() is enabled, then only
 474         // trace calls to it from wait_for_ext_suspend_completion()
 475         return;
 476       }
 477 #endif
 478     }
 479 
 480     if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
 481       if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
 482         MutexLocker ml(Threads_lock);  // needed for get_thread_name()
 483         ResourceMark rm;
 484 
 485         tty->print_cr(
 486                       "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
 487                       jt->get_thread_name(), *bits);
 488 
 489         guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
 490       }
 491     }
 492   }
 493 };
 494 #undef DEBUG_FALSE_BITS
 495 
 496 
 497 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
 498                                           uint32_t *bits) {
 499   TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
 500 
 501   bool did_trans_retry = false;  // only do thread_in_native_trans retry once
 502   bool do_trans_retry;           // flag to force the retry
 503 
 504   *bits |= 0x00000001;
 505 
 506   do {
 507     do_trans_retry = false;
 508 
 509     if (is_exiting()) {
 510       // Thread is in the process of exiting. This is always checked
 511       // first to reduce the risk of dereferencing a freed JavaThread.
 512       *bits |= 0x00000100;
 513       return false;
 514     }
 515 
 516     if (!is_external_suspend()) {
 517       // Suspend request is cancelled. This is always checked before
 518       // is_ext_suspended() to reduce the risk of a rogue resume
 519       // confusing the thread that made the suspend request.
 520       *bits |= 0x00000200;
 521       return false;
 522     }
 523 
 524     if (is_ext_suspended()) {
 525       // thread is suspended
 526       *bits |= 0x00000400;
 527       return true;
 528     }
 529 
 530     // Now that we no longer do hard suspends of threads running
 531     // native code, the target thread can be changing thread state
 532     // while we are in this routine:
 533     //
 534     //   _thread_in_native -> _thread_in_native_trans -> _thread_blocked
 535     //
 536     // We save a copy of the thread state as observed at this moment
 537     // and make our decision about suspend completeness based on the
 538     // copy. This closes the race where the thread state is seen as
 539     // _thread_in_native_trans in the if-thread_blocked check, but is
 540     // seen as _thread_blocked in if-thread_in_native_trans check.
 541     JavaThreadState save_state = thread_state();
 542 
 543     if (save_state == _thread_blocked && is_suspend_equivalent()) {
 544       // If the thread's state is _thread_blocked and this blocking
 545       // condition is known to be equivalent to a suspend, then we can
 546       // consider the thread to be externally suspended. This means that
 547       // the code that sets _thread_blocked has been modified to do
 548       // self-suspension if the blocking condition releases. We also
 549       // used to check for CONDVAR_WAIT here, but that is now covered by
 550       // the _thread_blocked with self-suspension check.
 551       //
 552       // Return true since we wouldn't be here unless there was still an
 553       // external suspend request.
 554       *bits |= 0x00001000;
 555       return true;
 556     } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
 557       // Threads running native code will self-suspend on native==>VM/Java
 558       // transitions. If its stack is walkable (should always be the case
 559       // unless this function is called before the actual java_suspend()
 560       // call), then the wait is done.
 561       *bits |= 0x00002000;
 562       return true;
 563     } else if (!called_by_wait && !did_trans_retry &&
 564                save_state == _thread_in_native_trans &&
 565                frame_anchor()->walkable()) {
 566       // The thread is transitioning from thread_in_native to another
 567       // thread state. check_safepoint_and_suspend_for_native_trans()
 568       // will force the thread to self-suspend. If it hasn't gotten
 569       // there yet we may have caught the thread in-between the native
 570       // code check above and the self-suspend. Lucky us. If we were
 571       // called by wait_for_ext_suspend_completion(), then it
 572       // will be doing the retries so we don't have to.
 573       //
 574       // Since we use the saved thread state in the if-statement above,
 575       // there is a chance that the thread has already transitioned to
 576       // _thread_blocked by the time we get here. In that case, we will
 577       // make a single unnecessary pass through the logic below. This
 578       // doesn't hurt anything since we still do the trans retry.
 579 
 580       *bits |= 0x00004000;
 581 
 582       // Once the thread leaves thread_in_native_trans for another
 583       // thread state, we break out of this retry loop. We shouldn't
 584       // need this flag to prevent us from getting back here, but
 585       // sometimes paranoia is good.
 586       did_trans_retry = true;
 587 
 588       // We wait for the thread to transition to a more usable state.
 589       for (int i = 1; i <= SuspendRetryCount; i++) {
 590         // We used to do an "os::yield_all(i)" call here with the intention
 591         // that yielding would increase on each retry. However, the parameter
 592         // is ignored on Linux which means the yield didn't scale up. Waiting
 593         // on the SR_lock below provides a much more predictable scale up for
 594         // the delay. It also provides a simple/direct point to check for any
 595         // safepoint requests from the VMThread
 596 
 597         // temporarily drops SR_lock while doing wait with safepoint check
 598         // (if we're a JavaThread - the WatcherThread can also call this)
 599         // and increase delay with each retry
 600         SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 601 
 602         // check the actual thread state instead of what we saved above
 603         if (thread_state() != _thread_in_native_trans) {
 604           // the thread has transitioned to another thread state so
 605           // try all the checks (except this one) one more time.
 606           do_trans_retry = true;
 607           break;
 608         }
 609       } // end retry loop
 610 
 611 
 612     }
 613   } while (do_trans_retry);
 614 
 615   *bits |= 0x00000010;
 616   return false;
 617 }
 618 
 619 // Wait for an external suspend request to complete (or be cancelled).
 620 // Returns true if the thread is externally suspended and false otherwise.
 621 //
 622 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
 623                                                  uint32_t *bits) {
 624   TraceSuspendDebugBits tsdb(this, true /* is_wait */,
 625                              false /* !called_by_wait */, bits);
 626 
 627   // local flag copies to minimize SR_lock hold time
 628   bool is_suspended;
 629   bool pending;
 630   uint32_t reset_bits;
 631 
 632   // set a marker so is_ext_suspend_completed() knows we are the caller
 633   *bits |= 0x00010000;
 634 
 635   // We use reset_bits to reinitialize the bits value at the top of
 636   // each retry loop. This allows the caller to make use of any
 637   // unused bits for their own marking purposes.
 638   reset_bits = *bits;
 639 
 640   {
 641     MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
 642     is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 643                                             delay, bits);
 644     pending = is_external_suspend();
 645   }
 646   // must release SR_lock to allow suspension to complete
 647 
 648   if (!pending) {
 649     // A cancelled suspend request is the only false return from
 650     // is_ext_suspend_completed() that keeps us from entering the
 651     // retry loop.
 652     *bits |= 0x00020000;
 653     return false;
 654   }
 655 
 656   if (is_suspended) {
 657     *bits |= 0x00040000;
 658     return true;
 659   }
 660 
 661   for (int i = 1; i <= retries; i++) {
 662     *bits = reset_bits;  // reinit to only track last retry
 663 
 664     // We used to do an "os::yield_all(i)" call here with the intention
 665     // that yielding would increase on each retry. However, the parameter
 666     // is ignored on Linux which means the yield didn't scale up. Waiting
 667     // on the SR_lock below provides a much more predictable scale up for
 668     // the delay. It also provides a simple/direct point to check for any
 669     // safepoint requests from the VMThread
 670 
 671     {
 672       MutexLocker ml(SR_lock());
 673       // wait with safepoint check (if we're a JavaThread - the WatcherThread
 674       // can also call this)  and increase delay with each retry
 675       SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 676 
 677       is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 678                                               delay, bits);
 679 
 680       // It is possible for the external suspend request to be cancelled
 681       // (by a resume) before the actual suspend operation is completed.
 682       // Refresh our local copy to see if we still need to wait.
 683       pending = is_external_suspend();
 684     }
 685 
 686     if (!pending) {
 687       // A cancelled suspend request is the only false return from
 688       // is_ext_suspend_completed() that keeps us from staying in the
 689       // retry loop.
 690       *bits |= 0x00080000;
 691       return false;
 692     }
 693 
 694     if (is_suspended) {
 695       *bits |= 0x00100000;
 696       return true;
 697     }
 698   } // end retry loop
 699 
 700   // thread did not suspend after all our retries
 701   *bits |= 0x00200000;
 702   return false;
 703 }
 704 
 705 #ifndef PRODUCT
 706 void JavaThread::record_jump(address target, address instr, const char* file,
 707                              int line) {
 708 
 709   // This should not need to be atomic as the only way for simultaneous
 710   // updates is via interrupts. Even then this should be rare or non-existent
 711   // and we don't care that much anyway.
 712 
 713   int index = _jmp_ring_index;
 714   _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
 715   _jmp_ring[index]._target = (intptr_t) target;
 716   _jmp_ring[index]._instruction = (intptr_t) instr;
 717   _jmp_ring[index]._file = file;
 718   _jmp_ring[index]._line = line;
 719 }
 720 #endif // PRODUCT
 721 
 722 // Called by flat profiler
 723 // Callers have already called wait_for_ext_suspend_completion
 724 // The assertion for that is currently too complex to put here:
 725 bool JavaThread::profile_last_Java_frame(frame* _fr) {
 726   bool gotframe = false;
 727   // self suspension saves needed state.
 728   if (has_last_Java_frame() && _anchor.walkable()) {
 729     *_fr = pd_last_frame();
 730     gotframe = true;
 731   }
 732   return gotframe;
 733 }
 734 
 735 void Thread::interrupt(Thread* thread) {
 736   debug_only(check_for_dangling_thread_pointer(thread);)
 737   os::interrupt(thread);
 738 }
 739 
 740 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
 741   debug_only(check_for_dangling_thread_pointer(thread);)
 742   // Note:  If clear_interrupted==false, this simply fetches and
 743   // returns the value of the field osthread()->interrupted().
 744   return os::is_interrupted(thread, clear_interrupted);
 745 }
 746 
 747 
 748 // GC Support
 749 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
 750   jint thread_parity = _oops_do_parity;
 751   if (thread_parity != strong_roots_parity) {
 752     jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
 753     if (res == thread_parity) {
 754       return true;
 755     } else {
 756       guarantee(res == strong_roots_parity, "Or else what?");
 757       assert(SharedHeap::heap()->workers()->active_workers() > 0,
 758              "Should only fail when parallel.");
 759       return false;
 760     }
 761   }
 762   assert(SharedHeap::heap()->workers()->active_workers() > 0,
 763          "Should only fail when parallel.");
 764   return false;
 765 }
 766 
 767 void Thread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
 768   active_handles()->oops_do(f);
 769   // Do oop for ThreadShadow
 770   f->do_oop((oop*)&_pending_exception);
 771   handle_area()->oops_do(f);
 772 }
 773 
 774 void Thread::nmethods_do(CodeBlobClosure* cf) {
 775   // no nmethods in a generic thread...
 776 }
 777 
 778 void Thread::metadata_do(void f(Metadata*)) {
 779   if (metadata_handles() != NULL) {
 780     for (int i = 0; i< metadata_handles()->length(); i++) {
 781       f(metadata_handles()->at(i));
 782     }
 783   }
 784 }
 785 
 786 void Thread::print_on(outputStream* st) const {
 787   // get_priority assumes osthread initialized
 788   if (osthread() != NULL) {
 789     int os_prio;
 790     if (os::get_native_priority(this, &os_prio) == OS_OK) {
 791       st->print("os_prio=%d ", os_prio);
 792     }
 793     st->print("tid=" INTPTR_FORMAT " ", this);
 794     ext().print_on(st);
 795     osthread()->print_on(st);
 796   }
 797   debug_only(if (WizardMode) print_owned_locks_on(st);)
 798 }
 799 
 800 // Thread::print_on_error() is called by fatal error handler. Don't use
 801 // any lock or allocate memory.
 802 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
 803   if (is_VM_thread())                 st->print("VMThread");
 804   else if (is_Compiler_thread())      st->print("CompilerThread");
 805   else if (is_Java_thread())          st->print("JavaThread");
 806   else if (is_GC_task_thread())       st->print("GCTaskThread");
 807   else if (is_Watcher_thread())       st->print("WatcherThread");
 808   else if (is_ConcurrentGC_thread())  st->print("ConcurrentGCThread");
 809   else                                st->print("Thread");
 810 
 811   st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
 812             _stack_base - _stack_size, _stack_base);
 813 
 814   if (osthread()) {
 815     st->print(" [id=%d]", osthread()->thread_id());
 816   }
 817 }
 818 
 819 #ifdef ASSERT
 820 void Thread::print_owned_locks_on(outputStream* st) const {
 821   Monitor *cur = _owned_locks;
 822   if (cur == NULL) {
 823     st->print(" (no locks) ");
 824   } else {
 825     st->print_cr(" Locks owned:");
 826     while (cur) {
 827       cur->print_on(st);
 828       cur = cur->next();
 829     }
 830   }
 831 }
 832 
 833 static int ref_use_count  = 0;
 834 
 835 bool Thread::owns_locks_but_compiled_lock() const {
 836   for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 837     if (cur != Compile_lock) return true;
 838   }
 839   return false;
 840 }
 841 
 842 
 843 #endif
 844 
 845 #ifndef PRODUCT
 846 
 847 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
 848 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
 849 // no threads which allow_vm_block's are held
 850 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
 851   // Check if current thread is allowed to block at a safepoint
 852   if (!(_allow_safepoint_count == 0)) {
 853     fatal("Possible safepoint reached by thread that does not allow it");
 854   }
 855   if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
 856     fatal("LEAF method calling lock?");
 857   }
 858 
 859 #ifdef ASSERT
 860   if (potential_vm_operation && is_Java_thread()
 861       && !Universe::is_bootstrapping()) {
 862     // Make sure we do not hold any locks that the VM thread also uses.
 863     // This could potentially lead to deadlocks
 864     for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 865       // Threads_lock is special, since the safepoint synchronization will not start before this is
 866       // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
 867       // since it is used to transfer control between JavaThreads and the VMThread
 868       // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
 869       if ((cur->allow_vm_block() &&
 870            cur != Threads_lock &&
 871            cur != Compile_lock &&               // Temporary: should not be necessary when we get separate compilation
 872            cur != VMOperationRequest_lock &&
 873            cur != VMOperationQueue_lock) ||
 874            cur->rank() == Mutex::special) {
 875         fatal(err_msg("Thread holding lock at safepoint that vm can block on: %s", cur->name()));
 876       }
 877     }
 878   }
 879 
 880   if (GCALotAtAllSafepoints) {
 881     // We could enter a safepoint here and thus have a gc
 882     InterfaceSupport::check_gc_alot();
 883   }
 884 #endif
 885 }
 886 #endif
 887 
 888 bool Thread::is_in_stack(address adr) const {
 889   assert(Thread::current() == this, "is_in_stack can only be called from current thread");
 890   address end = os::current_stack_pointer();
 891   // Allow non Java threads to call this without stack_base
 892   if (_stack_base == NULL) return true;
 893   if (stack_base() >= adr && adr >= end) return true;
 894 
 895   return false;
 896 }
 897 
 898 
 899 bool Thread::is_in_usable_stack(address adr) const {
 900   size_t stack_guard_size = os::uses_stack_guard_pages() ? (StackYellowPages + StackRedPages) * os::vm_page_size() : 0;
 901   size_t usable_stack_size = _stack_size - stack_guard_size;
 902 
 903   return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
 904 }
 905 
 906 
 907 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
 908 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
 909 // used for compilation in the future. If that change is made, the need for these methods
 910 // should be revisited, and they should be removed if possible.
 911 
 912 bool Thread::is_lock_owned(address adr) const {
 913   return on_local_stack(adr);
 914 }
 915 
 916 bool Thread::set_as_starting_thread() {
 917   // NOTE: this must be called inside the main thread.
 918   return os::create_main_thread((JavaThread*)this);
 919 }
 920 
 921 static void initialize_class(Symbol* class_name, TRAPS) {
 922   Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
 923   InstanceKlass::cast(klass)->initialize(CHECK);
 924 }
 925 
 926 
 927 // Creates the initial ThreadGroup
 928 static Handle create_initial_thread_group(TRAPS) {
 929   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
 930   instanceKlassHandle klass (THREAD, k);
 931 
 932   Handle system_instance = klass->allocate_instance_handle(CHECK_NH);
 933   {
 934     JavaValue result(T_VOID);
 935     JavaCalls::call_special(&result,
 936                             system_instance,
 937                             klass,
 938                             vmSymbols::object_initializer_name(),
 939                             vmSymbols::void_method_signature(),
 940                             CHECK_NH);
 941   }
 942   Universe::set_system_thread_group(system_instance());
 943 
 944   Handle main_instance = klass->allocate_instance_handle(CHECK_NH);
 945   {
 946     JavaValue result(T_VOID);
 947     Handle string = java_lang_String::create_from_str("main", CHECK_NH);
 948     JavaCalls::call_special(&result,
 949                             main_instance,
 950                             klass,
 951                             vmSymbols::object_initializer_name(),
 952                             vmSymbols::threadgroup_string_void_signature(),
 953                             system_instance,
 954                             string,
 955                             CHECK_NH);
 956   }
 957   return main_instance;
 958 }
 959 
 960 // Creates the initial Thread
 961 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
 962                                  TRAPS) {
 963   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
 964   instanceKlassHandle klass (THREAD, k);
 965   instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);
 966 
 967   java_lang_Thread::set_thread(thread_oop(), thread);
 968   java_lang_Thread::set_priority(thread_oop(), NormPriority);
 969   thread->set_threadObj(thread_oop());
 970 
 971   Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
 972 
 973   JavaValue result(T_VOID);
 974   JavaCalls::call_special(&result, thread_oop,
 975                           klass,
 976                           vmSymbols::object_initializer_name(),
 977                           vmSymbols::threadgroup_string_void_signature(),
 978                           thread_group,
 979                           string,
 980                           CHECK_NULL);
 981   return thread_oop();
 982 }
 983 
 984 static void call_initializeSystemClass(TRAPS) {
 985   Klass* k =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
 986   instanceKlassHandle klass (THREAD, k);
 987 
 988   JavaValue result(T_VOID);
 989   JavaCalls::call_static(&result, klass, vmSymbols::initializeSystemClass_name(),
 990                          vmSymbols::void_method_signature(), CHECK);
 991 }
 992 
 993 char java_runtime_name[128] = "";
 994 char java_runtime_version[128] = "";
 995 
 996 // extract the JRE name from sun.misc.Version.java_runtime_name
 997 static const char* get_java_runtime_name(TRAPS) {
 998   Klass* k = SystemDictionary::find(vmSymbols::sun_misc_Version(),
 999                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1000   fieldDescriptor fd;
1001   bool found = k != NULL &&
1002                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1003                                                         vmSymbols::string_signature(), &fd);
1004   if (found) {
1005     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1006     if (name_oop == NULL) {
1007       return NULL;
1008     }
1009     const char* name = java_lang_String::as_utf8_string(name_oop,
1010                                                         java_runtime_name,
1011                                                         sizeof(java_runtime_name));
1012     return name;
1013   } else {
1014     return NULL;
1015   }
1016 }
1017 
1018 // extract the JRE version from sun.misc.Version.java_runtime_version
1019 static const char* get_java_runtime_version(TRAPS) {
1020   Klass* k = SystemDictionary::find(vmSymbols::sun_misc_Version(),
1021                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1022   fieldDescriptor fd;
1023   bool found = k != NULL &&
1024                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1025                                                         vmSymbols::string_signature(), &fd);
1026   if (found) {
1027     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1028     if (name_oop == NULL) {
1029       return NULL;
1030     }
1031     const char* name = java_lang_String::as_utf8_string(name_oop,
1032                                                         java_runtime_version,
1033                                                         sizeof(java_runtime_version));
1034     return name;
1035   } else {
1036     return NULL;
1037   }
1038 }
1039 
1040 // General purpose hook into Java code, run once when the VM is initialized.
1041 // The Java library method itself may be changed independently from the VM.
1042 static void call_postVMInitHook(TRAPS) {
1043   Klass* k = SystemDictionary::resolve_or_null(vmSymbols::sun_misc_PostVMInitHook(), THREAD);
1044   instanceKlassHandle klass (THREAD, k);
1045   if (klass.not_null()) {
1046     JavaValue result(T_VOID);
1047     JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1048                            vmSymbols::void_method_signature(),
1049                            CHECK);
1050   }
1051 }
1052 
1053 static void reset_vm_info_property(TRAPS) {
1054   // the vm info string
1055   ResourceMark rm(THREAD);
1056   const char *vm_info = VM_Version::vm_info_string();
1057 
1058   // java.lang.System class
1059   Klass* k =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1060   instanceKlassHandle klass (THREAD, k);
1061 
1062   // setProperty arguments
1063   Handle key_str    = java_lang_String::create_from_str("java.vm.info", CHECK);
1064   Handle value_str  = java_lang_String::create_from_str(vm_info, CHECK);
1065 
1066   // return value
1067   JavaValue r(T_OBJECT);
1068 
1069   // public static String setProperty(String key, String value);
1070   JavaCalls::call_static(&r,
1071                          klass,
1072                          vmSymbols::setProperty_name(),
1073                          vmSymbols::string_string_string_signature(),
1074                          key_str,
1075                          value_str,
1076                          CHECK);
1077 }
1078 
1079 
1080 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1081                                     bool daemon, TRAPS) {
1082   assert(thread_group.not_null(), "thread group should be specified");
1083   assert(threadObj() == NULL, "should only create Java thread object once");
1084 
1085   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1086   instanceKlassHandle klass (THREAD, k);
1087   instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
1088 
1089   java_lang_Thread::set_thread(thread_oop(), this);
1090   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1091   set_threadObj(thread_oop());
1092 
1093   JavaValue result(T_VOID);
1094   if (thread_name != NULL) {
1095     Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1096     // Thread gets assigned specified name and null target
1097     JavaCalls::call_special(&result,
1098                             thread_oop,
1099                             klass,
1100                             vmSymbols::object_initializer_name(),
1101                             vmSymbols::threadgroup_string_void_signature(),
1102                             thread_group, // Argument 1
1103                             name,         // Argument 2
1104                             THREAD);
1105   } else {
1106     // Thread gets assigned name "Thread-nnn" and null target
1107     // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1108     JavaCalls::call_special(&result,
1109                             thread_oop,
1110                             klass,
1111                             vmSymbols::object_initializer_name(),
1112                             vmSymbols::threadgroup_runnable_void_signature(),
1113                             thread_group, // Argument 1
1114                             Handle(),     // Argument 2
1115                             THREAD);
1116   }
1117 
1118 
1119   if (daemon) {
1120     java_lang_Thread::set_daemon(thread_oop());
1121   }
1122 
1123   if (HAS_PENDING_EXCEPTION) {
1124     return;
1125   }
1126 
1127   KlassHandle group(THREAD, SystemDictionary::ThreadGroup_klass());
1128   Handle threadObj(THREAD, this->threadObj());
1129 
1130   JavaCalls::call_special(&result,
1131                           thread_group,
1132                           group,
1133                           vmSymbols::add_method_name(),
1134                           vmSymbols::thread_void_signature(),
1135                           threadObj,          // Arg 1
1136                           THREAD);
1137 }
1138 
1139 // NamedThread --  non-JavaThread subclasses with multiple
1140 // uniquely named instances should derive from this.
1141 NamedThread::NamedThread() : Thread() {
1142   _name = NULL;
1143   _processed_thread = NULL;
1144 }
1145 
1146 NamedThread::~NamedThread() {
1147   if (_name != NULL) {
1148     FREE_C_HEAP_ARRAY(char, _name);
1149     _name = NULL;
1150   }
1151 }
1152 
1153 void NamedThread::set_name(const char* format, ...) {
1154   guarantee(_name == NULL, "Only get to set name once.");
1155   _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1156   guarantee(_name != NULL, "alloc failure");
1157   va_list ap;
1158   va_start(ap, format);
1159   jio_vsnprintf(_name, max_name_len, format, ap);
1160   va_end(ap);
1161 }
1162 
1163 void NamedThread::print_on(outputStream* st) const {
1164   st->print("\"%s\" ", name());
1165   Thread::print_on(st);
1166   st->cr();
1167 }
1168 
1169 
1170 // ======= WatcherThread ========
1171 
1172 // The watcher thread exists to simulate timer interrupts.  It should
1173 // be replaced by an abstraction over whatever native support for
1174 // timer interrupts exists on the platform.
1175 
1176 WatcherThread* WatcherThread::_watcher_thread   = NULL;
1177 bool WatcherThread::_startable = false;
1178 volatile bool  WatcherThread::_should_terminate = false;
1179 
1180 WatcherThread::WatcherThread() : Thread(), _crash_protection(NULL) {
1181   assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1182   if (os::create_thread(this, os::watcher_thread)) {
1183     _watcher_thread = this;
1184 
1185     // Set the watcher thread to the highest OS priority which should not be
1186     // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1187     // is created. The only normal thread using this priority is the reference
1188     // handler thread, which runs for very short intervals only.
1189     // If the VMThread's priority is not lower than the WatcherThread profiling
1190     // will be inaccurate.
1191     os::set_priority(this, MaxPriority);
1192     if (!DisableStartThread) {
1193       os::start_thread(this);
1194     }
1195   }
1196 }
1197 
1198 int WatcherThread::sleep() const {


1199   MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1200 





1201   // remaining will be zero if there are no tasks,
1202   // causing the WatcherThread to sleep until a task is
1203   // enrolled
1204   int remaining = PeriodicTask::time_to_wait();
1205   int time_slept = 0;
1206 
1207   // we expect this to timeout - we only ever get unparked when
1208   // we should terminate or when a new task has been enrolled
1209   OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1210 
1211   jlong time_before_loop = os::javaTimeNanos();
1212 
1213   for (;;) {
1214     bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag, remaining);

1215     jlong now = os::javaTimeNanos();
1216 
1217     if (remaining == 0) {
1218       // if we didn't have any tasks we could have waited for a long time
1219       // consider the time_slept zero and reset time_before_loop
1220       time_slept = 0;
1221       time_before_loop = now;
1222     } else {
1223       // need to recalculate since we might have new tasks in _tasks
1224       time_slept = (int) ((now - time_before_loop) / 1000000);
1225     }
1226 
1227     // Change to task list or spurious wakeup of some kind
1228     if (timedout || _should_terminate) {
1229       break;
1230     }
1231 
1232     remaining = PeriodicTask::time_to_wait();
1233     if (remaining == 0) {
1234       // Last task was just disenrolled so loop around and wait until
1235       // another task gets enrolled
1236       continue;
1237     }
1238 
1239     remaining -= time_slept;
1240     if (remaining <= 0) {
1241       break;
1242     }
1243   }
1244 
1245   return time_slept;
1246 }
1247 
1248 void WatcherThread::run() {
1249   assert(this == watcher_thread(), "just checking");
1250 
1251   this->record_stack_base_and_size();
1252   this->initialize_thread_local_storage();
1253   this->set_native_thread_name(this->name());
1254   this->set_active_handles(JNIHandleBlock::allocate_block());
1255   while (!_should_terminate) {
1256     assert(watcher_thread() == Thread::current(), "thread consistency check");
1257     assert(watcher_thread() == this, "thread consistency check");
1258 
1259     // Calculate how long it'll be until the next PeriodicTask work
1260     // should be done, and sleep that amount of time.
1261     int time_waited = sleep();
1262 
1263     if (is_error_reported()) {
1264       // A fatal error has happened, the error handler(VMError::report_and_die)
1265       // should abort JVM after creating an error log file. However in some
1266       // rare cases, the error handler itself might deadlock. Here we try to
1267       // kill JVM if the fatal error handler fails to abort in 2 minutes.
1268       //
1269       // This code is in WatcherThread because WatcherThread wakes up
1270       // periodically so the fatal error handler doesn't need to do anything;
1271       // also because the WatcherThread is less likely to crash than other
1272       // threads.
1273 
1274       for (;;) {
1275         if (!ShowMessageBoxOnError
1276             && (OnError == NULL || OnError[0] == '\0')
1277             && Arguments::abort_hook() == NULL) {
1278           os::sleep(this, 2 * 60 * 1000, false);
1279           fdStream err(defaultStream::output_fd());
1280           err.print_raw_cr("# [ timer expired, abort... ]");
1281           // skip atexit/vm_exit/vm_abort hooks
1282           os::die();
1283         }
1284 
1285         // Wake up 5 seconds later, the fatal handler may reset OnError or
1286         // ShowMessageBoxOnError when it is ready to abort.
1287         os::sleep(this, 5 * 1000, false);
1288       }
1289     }
1290 





1291     PeriodicTask::real_time_tick(time_waited);
1292   }
1293 
1294   // Signal that it is terminated
1295   {
1296     MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1297     _watcher_thread = NULL;
1298     Terminator_lock->notify();
1299   }
1300 
1301   // Thread destructor usually does this..
1302   ThreadLocalStorage::set_thread(NULL);
1303 }
1304 
1305 void WatcherThread::start() {
1306   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1307 
1308   if (watcher_thread() == NULL && _startable) {
1309     _should_terminate = false;
1310     // Create the single instance of WatcherThread
1311     new WatcherThread();
1312   }
1313 }
1314 
1315 void WatcherThread::make_startable() {
1316   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1317   _startable = true;
1318 }
1319 
1320 void WatcherThread::stop() {
1321   // Get the PeriodicTask_lock if we can. If we cannot, then the
1322   // WatcherThread is using it and we don't want to block on that lock
1323   // here because that might cause a safepoint deadlock depending on
1324   // what the current WatcherThread tasks are doing.
1325   bool have_lock = PeriodicTask_lock->try_lock();
1326 
1327   _should_terminate = true;
1328   OrderAccess::fence();  // ensure WatcherThread sees update in main loop
1329 
1330   if (have_lock) {
1331     WatcherThread* watcher = watcher_thread();
1332     if (watcher != NULL) {
1333       // If we managed to get the lock, then we should unpark the
1334       // WatcherThread so that it can see we want it to stop.
1335       watcher->unpark();
1336     }
1337 
1338     PeriodicTask_lock->unlock();
1339   }
1340 
1341   // it is ok to take late safepoints here, if needed
1342   MutexLocker mu(Terminator_lock);
1343 
1344   while (watcher_thread() != NULL) {
1345     // This wait should make safepoint checks, wait without a timeout,
1346     // and wait as a suspend-equivalent condition.
1347     //
1348     // Note: If the FlatProfiler is running, then this thread is waiting
1349     // for the WatcherThread to terminate and the WatcherThread, via the
1350     // FlatProfiler task, is waiting for the external suspend request on
1351     // this thread to complete. wait_for_ext_suspend_completion() will
1352     // eventually timeout, but that takes time. Making this wait a
1353     // suspend-equivalent condition solves that timeout problem.
1354     //
1355     Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1356                           Mutex::_as_suspend_equivalent_flag);
1357   }
1358 }
1359 
1360 void WatcherThread::unpark() {
1361   MutexLockerEx ml(PeriodicTask_lock->owned_by_self()
1362                    ? NULL
1363                    : PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1364   PeriodicTask_lock->notify();
1365 }
1366 
1367 void WatcherThread::print_on(outputStream* st) const {
1368   st->print("\"%s\" ", name());
1369   Thread::print_on(st);
1370   st->cr();
1371 }
1372 
1373 // ======= JavaThread ========
1374 
1375 // A JavaThread is a normal Java thread
1376 
1377 void JavaThread::initialize() {
1378   // Initialize fields
1379 
1380   // Set the claimed par_id to UINT_MAX (ie not claiming any par_ids)
1381   set_claimed_par_id(UINT_MAX);
1382 
1383   set_saved_exception_pc(NULL);
1384   set_threadObj(NULL);
1385   _anchor.clear();
1386   set_entry_point(NULL);
1387   set_jni_functions(jni_functions());
1388   set_callee_target(NULL);
1389   set_vm_result(NULL);
1390   set_vm_result_2(NULL);
1391   set_vframe_array_head(NULL);
1392   set_vframe_array_last(NULL);
1393   set_deferred_locals(NULL);
1394   set_deopt_mark(NULL);
1395   set_deopt_nmethod(NULL);
1396   clear_must_deopt_id();
1397   set_monitor_chunks(NULL);
1398   set_next(NULL);
1399   set_thread_state(_thread_new);
1400   _terminated = _not_terminated;
1401   _privileged_stack_top = NULL;
1402   _array_for_gc = NULL;
1403   _suspend_equivalent = false;
1404   _in_deopt_handler = 0;
1405   _doing_unsafe_access = false;
1406   _stack_guard_state = stack_guard_unused;
1407   (void)const_cast<oop&>(_exception_oop = oop(NULL));
1408   _exception_pc  = 0;
1409   _exception_handler_pc = 0;
1410   _is_method_handle_return = 0;
1411   _jvmti_thread_state= NULL;
1412   _should_post_on_exceptions_flag = JNI_FALSE;
1413   _jvmti_get_loaded_classes_closure = NULL;
1414   _interp_only_mode    = 0;
1415   _special_runtime_exit_condition = _no_async_condition;
1416   _pending_async_exception = NULL;
1417   _thread_stat = NULL;
1418   _thread_stat = new ThreadStatistics();
1419   _blocked_on_compilation = false;
1420   _jni_active_critical = 0;
1421   _pending_jni_exception_check_fn = NULL;
1422   _do_not_unlock_if_synchronized = false;
1423   _cached_monitor_info = NULL;
1424   _parker = Parker::Allocate(this);
1425 
1426 #ifndef PRODUCT
1427   _jmp_ring_index = 0;
1428   for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1429     record_jump(NULL, NULL, NULL, 0);
1430   }
1431 #endif // PRODUCT
1432 
1433   set_thread_profiler(NULL);
1434   if (FlatProfiler::is_active()) {
1435     // This is where we would decide to either give each thread it's own profiler
1436     // or use one global one from FlatProfiler,
1437     // or up to some count of the number of profiled threads, etc.
1438     ThreadProfiler* pp = new ThreadProfiler();
1439     pp->engage();
1440     set_thread_profiler(pp);
1441   }
1442 
1443   // Setup safepoint state info for this thread
1444   ThreadSafepointState::create(this);
1445 
1446   debug_only(_java_call_counter = 0);
1447 
1448   // JVMTI PopFrame support
1449   _popframe_condition = popframe_inactive;
1450   _popframe_preserved_args = NULL;
1451   _popframe_preserved_args_size = 0;
1452   _frames_to_pop_failed_realloc = 0;
1453 
1454   pd_initialize();
1455 }
1456 
1457 #if INCLUDE_ALL_GCS
1458 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1459 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1460 #endif // INCLUDE_ALL_GCS
1461 
1462 JavaThread::JavaThread(bool is_attaching_via_jni) :
1463                        Thread()
1464 #if INCLUDE_ALL_GCS
1465                        , _satb_mark_queue(&_satb_mark_queue_set),
1466                        _dirty_card_queue(&_dirty_card_queue_set)
1467 #endif // INCLUDE_ALL_GCS
1468 {
1469   initialize();
1470   if (is_attaching_via_jni) {
1471     _jni_attach_state = _attaching_via_jni;
1472   } else {
1473     _jni_attach_state = _not_attaching_via_jni;
1474   }
1475   assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1476 }
1477 
1478 bool JavaThread::reguard_stack(address cur_sp) {
1479   if (_stack_guard_state != stack_guard_yellow_disabled) {
1480     return true; // Stack already guarded or guard pages not needed.
1481   }
1482 
1483   if (register_stack_overflow()) {
1484     // For those architectures which have separate register and
1485     // memory stacks, we must check the register stack to see if
1486     // it has overflowed.
1487     return false;
1488   }
1489 
1490   // Java code never executes within the yellow zone: the latter is only
1491   // there to provoke an exception during stack banging.  If java code
1492   // is executing there, either StackShadowPages should be larger, or
1493   // some exception code in c1, c2 or the interpreter isn't unwinding
1494   // when it should.
1495   guarantee(cur_sp > stack_yellow_zone_base(), "not enough space to reguard - increase StackShadowPages");
1496 
1497   enable_stack_yellow_zone();
1498   return true;
1499 }
1500 
1501 bool JavaThread::reguard_stack(void) {
1502   return reguard_stack(os::current_stack_pointer());
1503 }
1504 
1505 
1506 void JavaThread::block_if_vm_exited() {
1507   if (_terminated == _vm_exited) {
1508     // _vm_exited is set at safepoint, and Threads_lock is never released
1509     // we will block here forever
1510     Threads_lock->lock_without_safepoint_check();
1511     ShouldNotReachHere();
1512   }
1513 }
1514 
1515 
1516 // Remove this ifdef when C1 is ported to the compiler interface.
1517 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1518 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1519 
1520 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1521                        Thread()
1522 #if INCLUDE_ALL_GCS
1523                        , _satb_mark_queue(&_satb_mark_queue_set),
1524                        _dirty_card_queue(&_dirty_card_queue_set)
1525 #endif // INCLUDE_ALL_GCS
1526 {
1527   initialize();
1528   _jni_attach_state = _not_attaching_via_jni;
1529   set_entry_point(entry_point);
1530   // Create the native thread itself.
1531   // %note runtime_23
1532   os::ThreadType thr_type = os::java_thread;
1533   thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1534                                                      os::java_thread;
1535   os::create_thread(this, thr_type, stack_sz);
1536   // The _osthread may be NULL here because we ran out of memory (too many threads active).
1537   // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1538   // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1539   // the exception consists of creating the exception object & initializing it, initialization
1540   // will leave the VM via a JavaCall and then all locks must be unlocked).
1541   //
1542   // The thread is still suspended when we reach here. Thread must be explicit started
1543   // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1544   // by calling Threads:add. The reason why this is not done here, is because the thread
1545   // object must be fully initialized (take a look at JVM_Start)
1546 }
1547 
1548 JavaThread::~JavaThread() {
1549 
1550   // JSR166 -- return the parker to the free list
1551   Parker::Release(_parker);
1552   _parker = NULL;
1553 
1554   // Free any remaining  previous UnrollBlock
1555   vframeArray* old_array = vframe_array_last();
1556 
1557   if (old_array != NULL) {
1558     Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1559     old_array->set_unroll_block(NULL);
1560     delete old_info;
1561     delete old_array;
1562   }
1563 
1564   GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1565   if (deferred != NULL) {
1566     // This can only happen if thread is destroyed before deoptimization occurs.
1567     assert(deferred->length() != 0, "empty array!");
1568     do {
1569       jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1570       deferred->remove_at(0);
1571       // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1572       delete dlv;
1573     } while (deferred->length() != 0);
1574     delete deferred;
1575   }
1576 
1577   // All Java related clean up happens in exit
1578   ThreadSafepointState::destroy(this);
1579   if (_thread_profiler != NULL) delete _thread_profiler;
1580   if (_thread_stat != NULL) delete _thread_stat;
1581 }
1582 
1583 
1584 // The first routine called by a new Java thread
1585 void JavaThread::run() {
1586   // initialize thread-local alloc buffer related fields
1587   this->initialize_tlab();
1588 
1589   // used to test validity of stack trace backs
1590   this->record_base_of_stack_pointer();
1591 
1592   // Record real stack base and size.
1593   this->record_stack_base_and_size();
1594 
1595   // Initialize thread local storage; set before calling MutexLocker
1596   this->initialize_thread_local_storage();
1597 
1598   this->create_stack_guard_pages();
1599 
1600   this->cache_global_variables();
1601 
1602   // Thread is now sufficient initialized to be handled by the safepoint code as being
1603   // in the VM. Change thread state from _thread_new to _thread_in_vm
1604   ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1605 
1606   assert(JavaThread::current() == this, "sanity check");
1607   assert(!Thread::current()->owns_locks(), "sanity check");
1608 
1609   DTRACE_THREAD_PROBE(start, this);
1610 
1611   // This operation might block. We call that after all safepoint checks for a new thread has
1612   // been completed.
1613   this->set_active_handles(JNIHandleBlock::allocate_block());
1614 
1615   if (JvmtiExport::should_post_thread_life()) {
1616     JvmtiExport::post_thread_start(this);
1617   }
1618 
1619   EventThreadStart event;
1620   if (event.should_commit()) {
1621     event.set_javalangthread(java_lang_Thread::thread_id(this->threadObj()));
1622     event.commit();
1623   }
1624 
1625   // We call another function to do the rest so we are sure that the stack addresses used
1626   // from there will be lower than the stack base just computed
1627   thread_main_inner();
1628 
1629   // Note, thread is no longer valid at this point!
1630 }
1631 
1632 
1633 void JavaThread::thread_main_inner() {
1634   assert(JavaThread::current() == this, "sanity check");
1635   assert(this->threadObj() != NULL, "just checking");
1636 
1637   // Execute thread entry point unless this thread has a pending exception
1638   // or has been stopped before starting.
1639   // Note: Due to JVM_StopThread we can have pending exceptions already!
1640   if (!this->has_pending_exception() &&
1641       !java_lang_Thread::is_stillborn(this->threadObj())) {
1642     {
1643       ResourceMark rm(this);
1644       this->set_native_thread_name(this->get_thread_name());
1645     }
1646     HandleMark hm(this);
1647     this->entry_point()(this, this);
1648   }
1649 
1650   DTRACE_THREAD_PROBE(stop, this);
1651 
1652   this->exit(false);
1653   delete this;
1654 }
1655 
1656 
1657 static void ensure_join(JavaThread* thread) {
1658   // We do not need to grap the Threads_lock, since we are operating on ourself.
1659   Handle threadObj(thread, thread->threadObj());
1660   assert(threadObj.not_null(), "java thread object must exist");
1661   ObjectLocker lock(threadObj, thread);
1662   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1663   thread->clear_pending_exception();
1664   // Thread is exiting. So set thread_status field in  java.lang.Thread class to TERMINATED.
1665   java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1666   // Clear the native thread instance - this makes isAlive return false and allows the join()
1667   // to complete once we've done the notify_all below
1668   java_lang_Thread::set_thread(threadObj(), NULL);
1669   lock.notify_all(thread);
1670   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1671   thread->clear_pending_exception();
1672 }
1673 
1674 
1675 // For any new cleanup additions, please check to see if they need to be applied to
1676 // cleanup_failed_attach_current_thread as well.
1677 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1678   assert(this == JavaThread::current(), "thread consistency check");
1679 
1680   HandleMark hm(this);
1681   Handle uncaught_exception(this, this->pending_exception());
1682   this->clear_pending_exception();
1683   Handle threadObj(this, this->threadObj());
1684   assert(threadObj.not_null(), "Java thread object should be created");
1685 
1686   if (get_thread_profiler() != NULL) {
1687     get_thread_profiler()->disengage();
1688     ResourceMark rm;
1689     get_thread_profiler()->print(get_thread_name());
1690   }
1691 
1692 
1693   // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1694   {
1695     EXCEPTION_MARK;
1696 
1697     CLEAR_PENDING_EXCEPTION;
1698   }
1699   if (!destroy_vm) {
1700     if (uncaught_exception.not_null()) {
1701       EXCEPTION_MARK;
1702       // Call method Thread.dispatchUncaughtException().
1703       KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1704       JavaValue result(T_VOID);
1705       JavaCalls::call_virtual(&result,
1706                               threadObj, thread_klass,
1707                               vmSymbols::dispatchUncaughtException_name(),
1708                               vmSymbols::throwable_void_signature(),
1709                               uncaught_exception,
1710                               THREAD);
1711       if (HAS_PENDING_EXCEPTION) {
1712         ResourceMark rm(this);
1713         jio_fprintf(defaultStream::error_stream(),
1714                     "\nException: %s thrown from the UncaughtExceptionHandler"
1715                     " in thread \"%s\"\n",
1716                     pending_exception()->klass()->external_name(),
1717                     get_thread_name());
1718         CLEAR_PENDING_EXCEPTION;
1719       }
1720     }
1721 
1722     // Called before the java thread exit since we want to read info
1723     // from java_lang_Thread object
1724     EventThreadEnd event;
1725     if (event.should_commit()) {
1726       event.set_javalangthread(java_lang_Thread::thread_id(this->threadObj()));
1727       event.commit();
1728     }
1729 
1730     // Call after last event on thread
1731     EVENT_THREAD_EXIT(this);
1732 
1733     // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1734     // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1735     // is deprecated anyhow.
1736     if (!is_Compiler_thread()) {
1737       int count = 3;
1738       while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1739         EXCEPTION_MARK;
1740         JavaValue result(T_VOID);
1741         KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1742         JavaCalls::call_virtual(&result,
1743                                 threadObj, thread_klass,
1744                                 vmSymbols::exit_method_name(),
1745                                 vmSymbols::void_method_signature(),
1746                                 THREAD);
1747         CLEAR_PENDING_EXCEPTION;
1748       }
1749     }
1750     // notify JVMTI
1751     if (JvmtiExport::should_post_thread_life()) {
1752       JvmtiExport::post_thread_end(this);
1753     }
1754 
1755     // We have notified the agents that we are exiting, before we go on,
1756     // we must check for a pending external suspend request and honor it
1757     // in order to not surprise the thread that made the suspend request.
1758     while (true) {
1759       {
1760         MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1761         if (!is_external_suspend()) {
1762           set_terminated(_thread_exiting);
1763           ThreadService::current_thread_exiting(this);
1764           break;
1765         }
1766         // Implied else:
1767         // Things get a little tricky here. We have a pending external
1768         // suspend request, but we are holding the SR_lock so we
1769         // can't just self-suspend. So we temporarily drop the lock
1770         // and then self-suspend.
1771       }
1772 
1773       ThreadBlockInVM tbivm(this);
1774       java_suspend_self();
1775 
1776       // We're done with this suspend request, but we have to loop around
1777       // and check again. Eventually we will get SR_lock without a pending
1778       // external suspend request and will be able to mark ourselves as
1779       // exiting.
1780     }
1781     // no more external suspends are allowed at this point
1782   } else {
1783     // before_exit() has already posted JVMTI THREAD_END events
1784   }
1785 
1786   // Notify waiters on thread object. This has to be done after exit() is called
1787   // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1788   // group should have the destroyed bit set before waiters are notified).
1789   ensure_join(this);
1790   assert(!this->has_pending_exception(), "ensure_join should have cleared");
1791 
1792   // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1793   // held by this thread must be released.  A detach operation must only
1794   // get here if there are no Java frames on the stack.  Therefore, any
1795   // owned monitors at this point MUST be JNI-acquired monitors which are
1796   // pre-inflated and in the monitor cache.
1797   //
1798   // ensure_join() ignores IllegalThreadStateExceptions, and so does this.
1799   if (exit_type == jni_detach && JNIDetachReleasesMonitors) {
1800     assert(!this->has_last_Java_frame(), "detaching with Java frames?");
1801     ObjectSynchronizer::release_monitors_owned_by_thread(this);
1802     assert(!this->has_pending_exception(), "release_monitors should have cleared");
1803   }
1804 
1805   // These things needs to be done while we are still a Java Thread. Make sure that thread
1806   // is in a consistent state, in case GC happens
1807   assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1808 
1809   if (active_handles() != NULL) {
1810     JNIHandleBlock* block = active_handles();
1811     set_active_handles(NULL);
1812     JNIHandleBlock::release_block(block);
1813   }
1814 
1815   if (free_handle_block() != NULL) {
1816     JNIHandleBlock* block = free_handle_block();
1817     set_free_handle_block(NULL);
1818     JNIHandleBlock::release_block(block);
1819   }
1820 
1821   // These have to be removed while this is still a valid thread.
1822   remove_stack_guard_pages();
1823 
1824   if (UseTLAB) {
1825     tlab().make_parsable(true);  // retire TLAB
1826   }
1827 
1828   if (JvmtiEnv::environments_might_exist()) {
1829     JvmtiExport::cleanup_thread(this);
1830   }
1831 
1832   // We must flush any deferred card marks before removing a thread from
1833   // the list of active threads.
1834   Universe::heap()->flush_deferred_store_barrier(this);
1835   assert(deferred_card_mark().is_empty(), "Should have been flushed");
1836 
1837 #if INCLUDE_ALL_GCS
1838   // We must flush the G1-related buffers before removing a thread
1839   // from the list of active threads. We must do this after any deferred
1840   // card marks have been flushed (above) so that any entries that are
1841   // added to the thread's dirty card queue as a result are not lost.
1842   if (UseG1GC) {
1843     flush_barrier_queues();
1844   }
1845 #endif // INCLUDE_ALL_GCS
1846 
1847   // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1848   Threads::remove(this);
1849 }
1850 
1851 #if INCLUDE_ALL_GCS
1852 // Flush G1-related queues.
1853 void JavaThread::flush_barrier_queues() {
1854   satb_mark_queue().flush();
1855   dirty_card_queue().flush();
1856 }
1857 
1858 void JavaThread::initialize_queues() {
1859   assert(!SafepointSynchronize::is_at_safepoint(),
1860          "we should not be at a safepoint");
1861 
1862   ObjPtrQueue& satb_queue = satb_mark_queue();
1863   SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1864   // The SATB queue should have been constructed with its active
1865   // field set to false.
1866   assert(!satb_queue.is_active(), "SATB queue should not be active");
1867   assert(satb_queue.is_empty(), "SATB queue should be empty");
1868   // If we are creating the thread during a marking cycle, we should
1869   // set the active field of the SATB queue to true.
1870   if (satb_queue_set.is_active()) {
1871     satb_queue.set_active(true);
1872   }
1873 
1874   DirtyCardQueue& dirty_queue = dirty_card_queue();
1875   // The dirty card queue should have been constructed with its
1876   // active field set to true.
1877   assert(dirty_queue.is_active(), "dirty card queue should be active");
1878 }
1879 #endif // INCLUDE_ALL_GCS
1880 
1881 void JavaThread::cleanup_failed_attach_current_thread() {
1882   if (get_thread_profiler() != NULL) {
1883     get_thread_profiler()->disengage();
1884     ResourceMark rm;
1885     get_thread_profiler()->print(get_thread_name());
1886   }
1887 
1888   if (active_handles() != NULL) {
1889     JNIHandleBlock* block = active_handles();
1890     set_active_handles(NULL);
1891     JNIHandleBlock::release_block(block);
1892   }
1893 
1894   if (free_handle_block() != NULL) {
1895     JNIHandleBlock* block = free_handle_block();
1896     set_free_handle_block(NULL);
1897     JNIHandleBlock::release_block(block);
1898   }
1899 
1900   // These have to be removed while this is still a valid thread.
1901   remove_stack_guard_pages();
1902 
1903   if (UseTLAB) {
1904     tlab().make_parsable(true);  // retire TLAB, if any
1905   }
1906 
1907 #if INCLUDE_ALL_GCS
1908   if (UseG1GC) {
1909     flush_barrier_queues();
1910   }
1911 #endif // INCLUDE_ALL_GCS
1912 
1913   Threads::remove(this);
1914   delete this;
1915 }
1916 
1917 
1918 
1919 
1920 JavaThread* JavaThread::active() {
1921   Thread* thread = ThreadLocalStorage::thread();
1922   assert(thread != NULL, "just checking");
1923   if (thread->is_Java_thread()) {
1924     return (JavaThread*) thread;
1925   } else {
1926     assert(thread->is_VM_thread(), "this must be a vm thread");
1927     VM_Operation* op = ((VMThread*) thread)->vm_operation();
1928     JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
1929     assert(ret->is_Java_thread(), "must be a Java thread");
1930     return ret;
1931   }
1932 }
1933 
1934 bool JavaThread::is_lock_owned(address adr) const {
1935   if (Thread::is_lock_owned(adr)) return true;
1936 
1937   for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
1938     if (chunk->contains(adr)) return true;
1939   }
1940 
1941   return false;
1942 }
1943 
1944 
1945 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
1946   chunk->set_next(monitor_chunks());
1947   set_monitor_chunks(chunk);
1948 }
1949 
1950 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
1951   guarantee(monitor_chunks() != NULL, "must be non empty");
1952   if (monitor_chunks() == chunk) {
1953     set_monitor_chunks(chunk->next());
1954   } else {
1955     MonitorChunk* prev = monitor_chunks();
1956     while (prev->next() != chunk) prev = prev->next();
1957     prev->set_next(chunk->next());
1958   }
1959 }
1960 
1961 // JVM support.
1962 
1963 // Note: this function shouldn't block if it's called in
1964 // _thread_in_native_trans state (such as from
1965 // check_special_condition_for_native_trans()).
1966 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
1967 
1968   if (has_last_Java_frame() && has_async_condition()) {
1969     // If we are at a polling page safepoint (not a poll return)
1970     // then we must defer async exception because live registers
1971     // will be clobbered by the exception path. Poll return is
1972     // ok because the call we a returning from already collides
1973     // with exception handling registers and so there is no issue.
1974     // (The exception handling path kills call result registers but
1975     //  this is ok since the exception kills the result anyway).
1976 
1977     if (is_at_poll_safepoint()) {
1978       // if the code we are returning to has deoptimized we must defer
1979       // the exception otherwise live registers get clobbered on the
1980       // exception path before deoptimization is able to retrieve them.
1981       //
1982       RegisterMap map(this, false);
1983       frame caller_fr = last_frame().sender(&map);
1984       assert(caller_fr.is_compiled_frame(), "what?");
1985       if (caller_fr.is_deoptimized_frame()) {
1986         if (TraceExceptions) {
1987           ResourceMark rm;
1988           tty->print_cr("deferred async exception at compiled safepoint");
1989         }
1990         return;
1991       }
1992     }
1993   }
1994 
1995   JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
1996   if (condition == _no_async_condition) {
1997     // Conditions have changed since has_special_runtime_exit_condition()
1998     // was called:
1999     // - if we were here only because of an external suspend request,
2000     //   then that was taken care of above (or cancelled) so we are done
2001     // - if we were here because of another async request, then it has
2002     //   been cleared between the has_special_runtime_exit_condition()
2003     //   and now so again we are done
2004     return;
2005   }
2006 
2007   // Check for pending async. exception
2008   if (_pending_async_exception != NULL) {
2009     // Only overwrite an already pending exception, if it is not a threadDeath.
2010     if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2011 
2012       // We cannot call Exceptions::_throw(...) here because we cannot block
2013       set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2014 
2015       if (TraceExceptions) {
2016         ResourceMark rm;
2017         tty->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", this);
2018         if (has_last_Java_frame()) {
2019           frame f = last_frame();
2020           tty->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", f.pc(), f.sp());
2021         }
2022         tty->print_cr(" of type: %s", InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2023       }
2024       _pending_async_exception = NULL;
2025       clear_has_async_exception();
2026     }
2027   }
2028 
2029   if (check_unsafe_error &&
2030       condition == _async_unsafe_access_error && !has_pending_exception()) {
2031     condition = _no_async_condition;  // done
2032     switch (thread_state()) {
2033     case _thread_in_vm: {
2034       JavaThread* THREAD = this;
2035       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2036     }
2037     case _thread_in_native: {
2038       ThreadInVMfromNative tiv(this);
2039       JavaThread* THREAD = this;
2040       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2041     }
2042     case _thread_in_Java: {
2043       ThreadInVMfromJava tiv(this);
2044       JavaThread* THREAD = this;
2045       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2046     }
2047     default:
2048       ShouldNotReachHere();
2049     }
2050   }
2051 
2052   assert(condition == _no_async_condition || has_pending_exception() ||
2053          (!check_unsafe_error && condition == _async_unsafe_access_error),
2054          "must have handled the async condition, if no exception");
2055 }
2056 
2057 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2058   //
2059   // Check for pending external suspend. Internal suspend requests do
2060   // not use handle_special_runtime_exit_condition().
2061   // If JNIEnv proxies are allowed, don't self-suspend if the target
2062   // thread is not the current thread. In older versions of jdbx, jdbx
2063   // threads could call into the VM with another thread's JNIEnv so we
2064   // can be here operating on behalf of a suspended thread (4432884).
2065   bool do_self_suspend = is_external_suspend_with_lock();
2066   if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2067     //
2068     // Because thread is external suspended the safepoint code will count
2069     // thread as at a safepoint. This can be odd because we can be here
2070     // as _thread_in_Java which would normally transition to _thread_blocked
2071     // at a safepoint. We would like to mark the thread as _thread_blocked
2072     // before calling java_suspend_self like all other callers of it but
2073     // we must then observe proper safepoint protocol. (We can't leave
2074     // _thread_blocked with a safepoint in progress). However we can be
2075     // here as _thread_in_native_trans so we can't use a normal transition
2076     // constructor/destructor pair because they assert on that type of
2077     // transition. We could do something like:
2078     //
2079     // JavaThreadState state = thread_state();
2080     // set_thread_state(_thread_in_vm);
2081     // {
2082     //   ThreadBlockInVM tbivm(this);
2083     //   java_suspend_self()
2084     // }
2085     // set_thread_state(_thread_in_vm_trans);
2086     // if (safepoint) block;
2087     // set_thread_state(state);
2088     //
2089     // but that is pretty messy. Instead we just go with the way the
2090     // code has worked before and note that this is the only path to
2091     // java_suspend_self that doesn't put the thread in _thread_blocked
2092     // mode.
2093 
2094     frame_anchor()->make_walkable(this);
2095     java_suspend_self();
2096 
2097     // We might be here for reasons in addition to the self-suspend request
2098     // so check for other async requests.
2099   }
2100 
2101   if (check_asyncs) {
2102     check_and_handle_async_exceptions();
2103   }
2104 }
2105 
2106 void JavaThread::send_thread_stop(oop java_throwable)  {
2107   assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2108   assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2109   assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2110 
2111   // Do not throw asynchronous exceptions against the compiler thread
2112   // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2113   if (is_Compiler_thread()) return;
2114 
2115   {
2116     // Actually throw the Throwable against the target Thread - however
2117     // only if there is no thread death exception installed already.
2118     if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2119       // If the topmost frame is a runtime stub, then we are calling into
2120       // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2121       // must deoptimize the caller before continuing, as the compiled  exception handler table
2122       // may not be valid
2123       if (has_last_Java_frame()) {
2124         frame f = last_frame();
2125         if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2126           // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2127           RegisterMap reg_map(this, UseBiasedLocking);
2128           frame compiled_frame = f.sender(&reg_map);
2129           if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2130             Deoptimization::deoptimize(this, compiled_frame, &reg_map);
2131           }
2132         }
2133       }
2134 
2135       // Set async. pending exception in thread.
2136       set_pending_async_exception(java_throwable);
2137 
2138       if (TraceExceptions) {
2139         ResourceMark rm;
2140         tty->print_cr("Pending Async. exception installed of type: %s", InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2141       }
2142       // for AbortVMOnException flag
2143       NOT_PRODUCT(Exceptions::debug_check_abort(InstanceKlass::cast(_pending_async_exception->klass())->external_name()));
2144     }
2145   }
2146 
2147 
2148   // Interrupt thread so it will wake up from a potential wait()
2149   Thread::interrupt(this);
2150 }
2151 
2152 // External suspension mechanism.
2153 //
2154 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2155 // to any VM_locks and it is at a transition
2156 // Self-suspension will happen on the transition out of the vm.
2157 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2158 //
2159 // Guarantees on return:
2160 //   + Target thread will not execute any new bytecode (that's why we need to
2161 //     force a safepoint)
2162 //   + Target thread will not enter any new monitors
2163 //
2164 void JavaThread::java_suspend() {
2165   { MutexLocker mu(Threads_lock);
2166     if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2167       return;
2168     }
2169   }
2170 
2171   { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2172     if (!is_external_suspend()) {
2173       // a racing resume has cancelled us; bail out now
2174       return;
2175     }
2176 
2177     // suspend is done
2178     uint32_t debug_bits = 0;
2179     // Warning: is_ext_suspend_completed() may temporarily drop the
2180     // SR_lock to allow the thread to reach a stable thread state if
2181     // it is currently in a transient thread state.
2182     if (is_ext_suspend_completed(false /* !called_by_wait */,
2183                                  SuspendRetryDelay, &debug_bits)) {
2184       return;
2185     }
2186   }
2187 
2188   VM_ForceSafepoint vm_suspend;
2189   VMThread::execute(&vm_suspend);
2190 }
2191 
2192 // Part II of external suspension.
2193 // A JavaThread self suspends when it detects a pending external suspend
2194 // request. This is usually on transitions. It is also done in places
2195 // where continuing to the next transition would surprise the caller,
2196 // e.g., monitor entry.
2197 //
2198 // Returns the number of times that the thread self-suspended.
2199 //
2200 // Note: DO NOT call java_suspend_self() when you just want to block current
2201 //       thread. java_suspend_self() is the second stage of cooperative
2202 //       suspension for external suspend requests and should only be used
2203 //       to complete an external suspend request.
2204 //
2205 int JavaThread::java_suspend_self() {
2206   int ret = 0;
2207 
2208   // we are in the process of exiting so don't suspend
2209   if (is_exiting()) {
2210     clear_external_suspend();
2211     return ret;
2212   }
2213 
2214   assert(_anchor.walkable() ||
2215          (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2216          "must have walkable stack");
2217 
2218   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2219 
2220   assert(!this->is_ext_suspended(),
2221          "a thread trying to self-suspend should not already be suspended");
2222 
2223   if (this->is_suspend_equivalent()) {
2224     // If we are self-suspending as a result of the lifting of a
2225     // suspend equivalent condition, then the suspend_equivalent
2226     // flag is not cleared until we set the ext_suspended flag so
2227     // that wait_for_ext_suspend_completion() returns consistent
2228     // results.
2229     this->clear_suspend_equivalent();
2230   }
2231 
2232   // A racing resume may have cancelled us before we grabbed SR_lock
2233   // above. Or another external suspend request could be waiting for us
2234   // by the time we return from SR_lock()->wait(). The thread
2235   // that requested the suspension may already be trying to walk our
2236   // stack and if we return now, we can change the stack out from under
2237   // it. This would be a "bad thing (TM)" and cause the stack walker
2238   // to crash. We stay self-suspended until there are no more pending
2239   // external suspend requests.
2240   while (is_external_suspend()) {
2241     ret++;
2242     this->set_ext_suspended();
2243 
2244     // _ext_suspended flag is cleared by java_resume()
2245     while (is_ext_suspended()) {
2246       this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2247     }
2248   }
2249 
2250   return ret;
2251 }
2252 
2253 #ifdef ASSERT
2254 // verify the JavaThread has not yet been published in the Threads::list, and
2255 // hence doesn't need protection from concurrent access at this stage
2256 void JavaThread::verify_not_published() {
2257   if (!Threads_lock->owned_by_self()) {
2258     MutexLockerEx ml(Threads_lock,  Mutex::_no_safepoint_check_flag);
2259     assert(!Threads::includes(this),
2260            "java thread shouldn't have been published yet!");
2261   } else {
2262     assert(!Threads::includes(this),
2263            "java thread shouldn't have been published yet!");
2264   }
2265 }
2266 #endif
2267 
2268 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2269 // progress or when _suspend_flags is non-zero.
2270 // Current thread needs to self-suspend if there is a suspend request and/or
2271 // block if a safepoint is in progress.
2272 // Async exception ISN'T checked.
2273 // Note only the ThreadInVMfromNative transition can call this function
2274 // directly and when thread state is _thread_in_native_trans
2275 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2276   assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2277 
2278   JavaThread *curJT = JavaThread::current();
2279   bool do_self_suspend = thread->is_external_suspend();
2280 
2281   assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2282 
2283   // If JNIEnv proxies are allowed, don't self-suspend if the target
2284   // thread is not the current thread. In older versions of jdbx, jdbx
2285   // threads could call into the VM with another thread's JNIEnv so we
2286   // can be here operating on behalf of a suspended thread (4432884).
2287   if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2288     JavaThreadState state = thread->thread_state();
2289 
2290     // We mark this thread_blocked state as a suspend-equivalent so
2291     // that a caller to is_ext_suspend_completed() won't be confused.
2292     // The suspend-equivalent state is cleared by java_suspend_self().
2293     thread->set_suspend_equivalent();
2294 
2295     // If the safepoint code sees the _thread_in_native_trans state, it will
2296     // wait until the thread changes to other thread state. There is no
2297     // guarantee on how soon we can obtain the SR_lock and complete the
2298     // self-suspend request. It would be a bad idea to let safepoint wait for
2299     // too long. Temporarily change the state to _thread_blocked to
2300     // let the VM thread know that this thread is ready for GC. The problem
2301     // of changing thread state is that safepoint could happen just after
2302     // java_suspend_self() returns after being resumed, and VM thread will
2303     // see the _thread_blocked state. We must check for safepoint
2304     // after restoring the state and make sure we won't leave while a safepoint
2305     // is in progress.
2306     thread->set_thread_state(_thread_blocked);
2307     thread->java_suspend_self();
2308     thread->set_thread_state(state);
2309     // Make sure new state is seen by VM thread
2310     if (os::is_MP()) {
2311       if (UseMembar) {
2312         // Force a fence between the write above and read below
2313         OrderAccess::fence();
2314       } else {
2315         // Must use this rather than serialization page in particular on Windows
2316         InterfaceSupport::serialize_memory(thread);
2317       }
2318     }
2319   }
2320 
2321   if (SafepointSynchronize::do_call_back()) {
2322     // If we are safepointing, then block the caller which may not be
2323     // the same as the target thread (see above).
2324     SafepointSynchronize::block(curJT);
2325   }
2326 
2327   if (thread->is_deopt_suspend()) {
2328     thread->clear_deopt_suspend();
2329     RegisterMap map(thread, false);
2330     frame f = thread->last_frame();
2331     while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2332       f = f.sender(&map);
2333     }
2334     if (f.id() == thread->must_deopt_id()) {
2335       thread->clear_must_deopt_id();
2336       f.deoptimize(thread);
2337     } else {
2338       fatal("missed deoptimization!");
2339     }
2340   }
2341 }
2342 
2343 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2344 // progress or when _suspend_flags is non-zero.
2345 // Current thread needs to self-suspend if there is a suspend request and/or
2346 // block if a safepoint is in progress.
2347 // Also check for pending async exception (not including unsafe access error).
2348 // Note only the native==>VM/Java barriers can call this function and when
2349 // thread state is _thread_in_native_trans.
2350 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2351   check_safepoint_and_suspend_for_native_trans(thread);
2352 
2353   if (thread->has_async_exception()) {
2354     // We are in _thread_in_native_trans state, don't handle unsafe
2355     // access error since that may block.
2356     thread->check_and_handle_async_exceptions(false);
2357   }
2358 }
2359 
2360 // This is a variant of the normal
2361 // check_special_condition_for_native_trans with slightly different
2362 // semantics for use by critical native wrappers.  It does all the
2363 // normal checks but also performs the transition back into
2364 // thread_in_Java state.  This is required so that critical natives
2365 // can potentially block and perform a GC if they are the last thread
2366 // exiting the GC_locker.
2367 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2368   check_special_condition_for_native_trans(thread);
2369 
2370   // Finish the transition
2371   thread->set_thread_state(_thread_in_Java);
2372 
2373   if (thread->do_critical_native_unlock()) {
2374     ThreadInVMfromJavaNoAsyncException tiv(thread);
2375     GC_locker::unlock_critical(thread);
2376     thread->clear_critical_native_unlock();
2377   }
2378 }
2379 
2380 // We need to guarantee the Threads_lock here, since resumes are not
2381 // allowed during safepoint synchronization
2382 // Can only resume from an external suspension
2383 void JavaThread::java_resume() {
2384   assert_locked_or_safepoint(Threads_lock);
2385 
2386   // Sanity check: thread is gone, has started exiting or the thread
2387   // was not externally suspended.
2388   if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2389     return;
2390   }
2391 
2392   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2393 
2394   clear_external_suspend();
2395 
2396   if (is_ext_suspended()) {
2397     clear_ext_suspended();
2398     SR_lock()->notify_all();
2399   }
2400 }
2401 
2402 void JavaThread::create_stack_guard_pages() {
2403   if (! os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) return;
2404   address low_addr = stack_base() - stack_size();
2405   size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
2406 
2407   int allocate = os::allocate_stack_guard_pages();
2408   // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2409 
2410   if (allocate && !os::create_stack_guard_pages((char *) low_addr, len)) {
2411     warning("Attempt to allocate stack guard pages failed.");
2412     return;
2413   }
2414 
2415   if (os::guard_memory((char *) low_addr, len)) {
2416     _stack_guard_state = stack_guard_enabled;
2417   } else {
2418     warning("Attempt to protect stack guard pages failed.");
2419     if (os::uncommit_memory((char *) low_addr, len)) {
2420       warning("Attempt to deallocate stack guard pages failed.");
2421     }
2422   }
2423 }
2424 
2425 void JavaThread::remove_stack_guard_pages() {
2426   assert(Thread::current() == this, "from different thread");
2427   if (_stack_guard_state == stack_guard_unused) return;
2428   address low_addr = stack_base() - stack_size();
2429   size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
2430 
2431   if (os::allocate_stack_guard_pages()) {
2432     if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2433       _stack_guard_state = stack_guard_unused;
2434     } else {
2435       warning("Attempt to deallocate stack guard pages failed.");
2436     }
2437   } else {
2438     if (_stack_guard_state == stack_guard_unused) return;
2439     if (os::unguard_memory((char *) low_addr, len)) {
2440       _stack_guard_state = stack_guard_unused;
2441     } else {
2442       warning("Attempt to unprotect stack guard pages failed.");
2443     }
2444   }
2445 }
2446 
2447 void JavaThread::enable_stack_yellow_zone() {
2448   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2449   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2450 
2451   // The base notation is from the stacks point of view, growing downward.
2452   // We need to adjust it to work correctly with guard_memory()
2453   address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2454 
2455   guarantee(base < stack_base(), "Error calculating stack yellow zone");
2456   guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2457 
2458   if (os::guard_memory((char *) base, stack_yellow_zone_size())) {
2459     _stack_guard_state = stack_guard_enabled;
2460   } else {
2461     warning("Attempt to guard stack yellow zone failed.");
2462   }
2463   enable_register_stack_guard();
2464 }
2465 
2466 void JavaThread::disable_stack_yellow_zone() {
2467   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2468   assert(_stack_guard_state != stack_guard_yellow_disabled, "already disabled");
2469 
2470   // Simply return if called for a thread that does not use guard pages.
2471   if (_stack_guard_state == stack_guard_unused) return;
2472 
2473   // The base notation is from the stacks point of view, growing downward.
2474   // We need to adjust it to work correctly with guard_memory()
2475   address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2476 
2477   if (os::unguard_memory((char *)base, stack_yellow_zone_size())) {
2478     _stack_guard_state = stack_guard_yellow_disabled;
2479   } else {
2480     warning("Attempt to unguard stack yellow zone failed.");
2481   }
2482   disable_register_stack_guard();
2483 }
2484 
2485 void JavaThread::enable_stack_red_zone() {
2486   // The base notation is from the stacks point of view, growing downward.
2487   // We need to adjust it to work correctly with guard_memory()
2488   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2489   address base = stack_red_zone_base() - stack_red_zone_size();
2490 
2491   guarantee(base < stack_base(), "Error calculating stack red zone");
2492   guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2493 
2494   if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2495     warning("Attempt to guard stack red zone failed.");
2496   }
2497 }
2498 
2499 void JavaThread::disable_stack_red_zone() {
2500   // The base notation is from the stacks point of view, growing downward.
2501   // We need to adjust it to work correctly with guard_memory()
2502   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2503   address base = stack_red_zone_base() - stack_red_zone_size();
2504   if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2505     warning("Attempt to unguard stack red zone failed.");
2506   }
2507 }
2508 
2509 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2510   // ignore is there is no stack
2511   if (!has_last_Java_frame()) return;
2512   // traverse the stack frames. Starts from top frame.
2513   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2514     frame* fr = fst.current();
2515     f(fr, fst.register_map());
2516   }
2517 }
2518 
2519 
2520 #ifndef PRODUCT
2521 // Deoptimization
2522 // Function for testing deoptimization
2523 void JavaThread::deoptimize() {
2524   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2525   StackFrameStream fst(this, UseBiasedLocking);
2526   bool deopt = false;           // Dump stack only if a deopt actually happens.
2527   bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2528   // Iterate over all frames in the thread and deoptimize
2529   for (; !fst.is_done(); fst.next()) {
2530     if (fst.current()->can_be_deoptimized()) {
2531 
2532       if (only_at) {
2533         // Deoptimize only at particular bcis.  DeoptimizeOnlyAt
2534         // consists of comma or carriage return separated numbers so
2535         // search for the current bci in that string.
2536         address pc = fst.current()->pc();
2537         nmethod* nm =  (nmethod*) fst.current()->cb();
2538         ScopeDesc* sd = nm->scope_desc_at(pc);
2539         char buffer[8];
2540         jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2541         size_t len = strlen(buffer);
2542         const char * found = strstr(DeoptimizeOnlyAt, buffer);
2543         while (found != NULL) {
2544           if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2545               (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2546             // Check that the bci found is bracketed by terminators.
2547             break;
2548           }
2549           found = strstr(found + 1, buffer);
2550         }
2551         if (!found) {
2552           continue;
2553         }
2554       }
2555 
2556       if (DebugDeoptimization && !deopt) {
2557         deopt = true; // One-time only print before deopt
2558         tty->print_cr("[BEFORE Deoptimization]");
2559         trace_frames();
2560         trace_stack();
2561       }
2562       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2563     }
2564   }
2565 
2566   if (DebugDeoptimization && deopt) {
2567     tty->print_cr("[AFTER Deoptimization]");
2568     trace_frames();
2569   }
2570 }
2571 
2572 
2573 // Make zombies
2574 void JavaThread::make_zombies() {
2575   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2576     if (fst.current()->can_be_deoptimized()) {
2577       // it is a Java nmethod
2578       nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2579       nm->make_not_entrant();
2580     }
2581   }
2582 }
2583 #endif // PRODUCT
2584 
2585 
2586 void JavaThread::deoptimized_wrt_marked_nmethods() {
2587   if (!has_last_Java_frame()) return;
2588   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2589   StackFrameStream fst(this, UseBiasedLocking);
2590   for (; !fst.is_done(); fst.next()) {
2591     if (fst.current()->should_be_deoptimized()) {
2592       if (LogCompilation && xtty != NULL) {
2593         nmethod* nm = fst.current()->cb()->as_nmethod_or_null();
2594         xtty->elem("deoptimized thread='" UINTX_FORMAT "' compile_id='%d'",
2595                    this->name(), nm != NULL ? nm->compile_id() : -1);
2596       }
2597 
2598       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2599     }
2600   }
2601 }
2602 
2603 
2604 // If the caller is a NamedThread, then remember, in the current scope,
2605 // the given JavaThread in its _processed_thread field.
2606 class RememberProcessedThread: public StackObj {
2607   NamedThread* _cur_thr;
2608  public:
2609   RememberProcessedThread(JavaThread* jthr) {
2610     Thread* thread = Thread::current();
2611     if (thread->is_Named_thread()) {
2612       _cur_thr = (NamedThread *)thread;
2613       _cur_thr->set_processed_thread(jthr);
2614     } else {
2615       _cur_thr = NULL;
2616     }
2617   }
2618 
2619   ~RememberProcessedThread() {
2620     if (_cur_thr) {
2621       _cur_thr->set_processed_thread(NULL);
2622     }
2623   }
2624 };
2625 
2626 void JavaThread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
2627   // Verify that the deferred card marks have been flushed.
2628   assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2629 
2630   // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2631   // since there may be more than one thread using each ThreadProfiler.
2632 
2633   // Traverse the GCHandles
2634   Thread::oops_do(f, cld_f, cf);
2635 
2636   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2637          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2638 
2639   if (has_last_Java_frame()) {
2640     // Record JavaThread to GC thread
2641     RememberProcessedThread rpt(this);
2642 
2643     // Traverse the privileged stack
2644     if (_privileged_stack_top != NULL) {
2645       _privileged_stack_top->oops_do(f);
2646     }
2647 
2648     // traverse the registered growable array
2649     if (_array_for_gc != NULL) {
2650       for (int index = 0; index < _array_for_gc->length(); index++) {
2651         f->do_oop(_array_for_gc->adr_at(index));
2652       }
2653     }
2654 
2655     // Traverse the monitor chunks
2656     for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2657       chunk->oops_do(f);
2658     }
2659 
2660     // Traverse the execution stack
2661     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2662       fst.current()->oops_do(f, cld_f, cf, fst.register_map());
2663     }
2664   }
2665 
2666   // callee_target is never live across a gc point so NULL it here should
2667   // it still contain a methdOop.
2668 
2669   set_callee_target(NULL);
2670 
2671   assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2672   // If we have deferred set_locals there might be oops waiting to be
2673   // written
2674   GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2675   if (list != NULL) {
2676     for (int i = 0; i < list->length(); i++) {
2677       list->at(i)->oops_do(f);
2678     }
2679   }
2680 
2681   // Traverse instance variables at the end since the GC may be moving things
2682   // around using this function
2683   f->do_oop((oop*) &_threadObj);
2684   f->do_oop((oop*) &_vm_result);
2685   f->do_oop((oop*) &_exception_oop);
2686   f->do_oop((oop*) &_pending_async_exception);
2687 
2688   if (jvmti_thread_state() != NULL) {
2689     jvmti_thread_state()->oops_do(f);
2690   }
2691 }
2692 
2693 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2694   Thread::nmethods_do(cf);  // (super method is a no-op)
2695 
2696   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2697          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2698 
2699   if (has_last_Java_frame()) {
2700     // Traverse the execution stack
2701     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2702       fst.current()->nmethods_do(cf);
2703     }
2704   }
2705 }
2706 
2707 void JavaThread::metadata_do(void f(Metadata*)) {
2708   Thread::metadata_do(f);
2709   if (has_last_Java_frame()) {
2710     // Traverse the execution stack to call f() on the methods in the stack
2711     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2712       fst.current()->metadata_do(f);
2713     }
2714   } else if (is_Compiler_thread()) {
2715     // need to walk ciMetadata in current compile tasks to keep alive.
2716     CompilerThread* ct = (CompilerThread*)this;
2717     if (ct->env() != NULL) {
2718       ct->env()->metadata_do(f);
2719     }
2720   }
2721 }
2722 
2723 // Printing
2724 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2725   switch (_thread_state) {
2726   case _thread_uninitialized:     return "_thread_uninitialized";
2727   case _thread_new:               return "_thread_new";
2728   case _thread_new_trans:         return "_thread_new_trans";
2729   case _thread_in_native:         return "_thread_in_native";
2730   case _thread_in_native_trans:   return "_thread_in_native_trans";
2731   case _thread_in_vm:             return "_thread_in_vm";
2732   case _thread_in_vm_trans:       return "_thread_in_vm_trans";
2733   case _thread_in_Java:           return "_thread_in_Java";
2734   case _thread_in_Java_trans:     return "_thread_in_Java_trans";
2735   case _thread_blocked:           return "_thread_blocked";
2736   case _thread_blocked_trans:     return "_thread_blocked_trans";
2737   default:                        return "unknown thread state";
2738   }
2739 }
2740 
2741 #ifndef PRODUCT
2742 void JavaThread::print_thread_state_on(outputStream *st) const {
2743   st->print_cr("   JavaThread state: %s", _get_thread_state_name(_thread_state));
2744 };
2745 void JavaThread::print_thread_state() const {
2746   print_thread_state_on(tty);
2747 }
2748 #endif // PRODUCT
2749 
2750 // Called by Threads::print() for VM_PrintThreads operation
2751 void JavaThread::print_on(outputStream *st) const {
2752   st->print("\"%s\" ", get_thread_name());
2753   oop thread_oop = threadObj();
2754   if (thread_oop != NULL) {
2755     st->print("#" INT64_FORMAT " ", java_lang_Thread::thread_id(thread_oop));
2756     if (java_lang_Thread::is_daemon(thread_oop))  st->print("daemon ");
2757     st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2758   }
2759   Thread::print_on(st);
2760   // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2761   st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2762   if (thread_oop != NULL) {
2763     st->print_cr("   java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2764   }
2765 #ifndef PRODUCT
2766   print_thread_state_on(st);
2767   _safepoint_state->print_on(st);
2768 #endif // PRODUCT
2769 }
2770 
2771 // Called by fatal error handler. The difference between this and
2772 // JavaThread::print() is that we can't grab lock or allocate memory.
2773 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2774   st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2775   oop thread_obj = threadObj();
2776   if (thread_obj != NULL) {
2777     if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2778   }
2779   st->print(" [");
2780   st->print("%s", _get_thread_state_name(_thread_state));
2781   if (osthread()) {
2782     st->print(", id=%d", osthread()->thread_id());
2783   }
2784   st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2785             _stack_base - _stack_size, _stack_base);
2786   st->print("]");
2787   return;
2788 }
2789 
2790 // Verification
2791 
2792 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2793 
2794 void JavaThread::verify() {
2795   // Verify oops in the thread.
2796   oops_do(&VerifyOopClosure::verify_oop, NULL, NULL);
2797 
2798   // Verify the stack frames.
2799   frames_do(frame_verify);
2800 }
2801 
2802 // CR 6300358 (sub-CR 2137150)
2803 // Most callers of this method assume that it can't return NULL but a
2804 // thread may not have a name whilst it is in the process of attaching to
2805 // the VM - see CR 6412693, and there are places where a JavaThread can be
2806 // seen prior to having it's threadObj set (eg JNI attaching threads and
2807 // if vm exit occurs during initialization). These cases can all be accounted
2808 // for such that this method never returns NULL.
2809 const char* JavaThread::get_thread_name() const {
2810 #ifdef ASSERT
2811   // early safepoints can hit while current thread does not yet have TLS
2812   if (!SafepointSynchronize::is_at_safepoint()) {
2813     Thread *cur = Thread::current();
2814     if (!(cur->is_Java_thread() && cur == this)) {
2815       // Current JavaThreads are allowed to get their own name without
2816       // the Threads_lock.
2817       assert_locked_or_safepoint(Threads_lock);
2818     }
2819   }
2820 #endif // ASSERT
2821   return get_thread_name_string();
2822 }
2823 
2824 // Returns a non-NULL representation of this thread's name, or a suitable
2825 // descriptive string if there is no set name
2826 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
2827   const char* name_str;
2828   oop thread_obj = threadObj();
2829   if (thread_obj != NULL) {
2830     oop name = java_lang_Thread::name(thread_obj);
2831     if (name != NULL) {
2832       if (buf == NULL) {
2833         name_str = java_lang_String::as_utf8_string(name);
2834       } else {
2835         name_str = java_lang_String::as_utf8_string(name, buf, buflen);
2836       }
2837     } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
2838       name_str = "<no-name - thread is attaching>";
2839     } else {
2840       name_str = Thread::name();
2841     }
2842   } else {
2843     name_str = Thread::name();
2844   }
2845   assert(name_str != NULL, "unexpected NULL thread name");
2846   return name_str;
2847 }
2848 
2849 
2850 const char* JavaThread::get_threadgroup_name() const {
2851   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2852   oop thread_obj = threadObj();
2853   if (thread_obj != NULL) {
2854     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2855     if (thread_group != NULL) {
2856       typeArrayOop name = java_lang_ThreadGroup::name(thread_group);
2857       // ThreadGroup.name can be null
2858       if (name != NULL) {
2859         const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2860         return str;
2861       }
2862     }
2863   }
2864   return NULL;
2865 }
2866 
2867 const char* JavaThread::get_parent_name() const {
2868   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2869   oop thread_obj = threadObj();
2870   if (thread_obj != NULL) {
2871     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2872     if (thread_group != NULL) {
2873       oop parent = java_lang_ThreadGroup::parent(thread_group);
2874       if (parent != NULL) {
2875         typeArrayOop name = java_lang_ThreadGroup::name(parent);
2876         // ThreadGroup.name can be null
2877         if (name != NULL) {
2878           const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2879           return str;
2880         }
2881       }
2882     }
2883   }
2884   return NULL;
2885 }
2886 
2887 ThreadPriority JavaThread::java_priority() const {
2888   oop thr_oop = threadObj();
2889   if (thr_oop == NULL) return NormPriority; // Bootstrapping
2890   ThreadPriority priority = java_lang_Thread::priority(thr_oop);
2891   assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
2892   return priority;
2893 }
2894 
2895 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
2896 
2897   assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
2898   // Link Java Thread object <-> C++ Thread
2899 
2900   // Get the C++ thread object (an oop) from the JNI handle (a jthread)
2901   // and put it into a new Handle.  The Handle "thread_oop" can then
2902   // be used to pass the C++ thread object to other methods.
2903 
2904   // Set the Java level thread object (jthread) field of the
2905   // new thread (a JavaThread *) to C++ thread object using the
2906   // "thread_oop" handle.
2907 
2908   // Set the thread field (a JavaThread *) of the
2909   // oop representing the java_lang_Thread to the new thread (a JavaThread *).
2910 
2911   Handle thread_oop(Thread::current(),
2912                     JNIHandles::resolve_non_null(jni_thread));
2913   assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
2914          "must be initialized");
2915   set_threadObj(thread_oop());
2916   java_lang_Thread::set_thread(thread_oop(), this);
2917 
2918   if (prio == NoPriority) {
2919     prio = java_lang_Thread::priority(thread_oop());
2920     assert(prio != NoPriority, "A valid priority should be present");
2921   }
2922 
2923   // Push the Java priority down to the native thread; needs Threads_lock
2924   Thread::set_priority(this, prio);
2925 
2926   prepare_ext();
2927 
2928   // Add the new thread to the Threads list and set it in motion.
2929   // We must have threads lock in order to call Threads::add.
2930   // It is crucial that we do not block before the thread is
2931   // added to the Threads list for if a GC happens, then the java_thread oop
2932   // will not be visited by GC.
2933   Threads::add(this);
2934 }
2935 
2936 oop JavaThread::current_park_blocker() {
2937   // Support for JSR-166 locks
2938   oop thread_oop = threadObj();
2939   if (thread_oop != NULL &&
2940       JDK_Version::current().supports_thread_park_blocker()) {
2941     return java_lang_Thread::park_blocker(thread_oop);
2942   }
2943   return NULL;
2944 }
2945 
2946 
2947 void JavaThread::print_stack_on(outputStream* st) {
2948   if (!has_last_Java_frame()) return;
2949   ResourceMark rm;
2950   HandleMark   hm;
2951 
2952   RegisterMap reg_map(this);
2953   vframe* start_vf = last_java_vframe(&reg_map);
2954   int count = 0;
2955   for (vframe* f = start_vf; f; f = f->sender()) {
2956     if (f->is_java_frame()) {
2957       javaVFrame* jvf = javaVFrame::cast(f);
2958       java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
2959 
2960       // Print out lock information
2961       if (JavaMonitorsInStackTrace) {
2962         jvf->print_lock_info_on(st, count);
2963       }
2964     } else {
2965       // Ignore non-Java frames
2966     }
2967 
2968     // Bail-out case for too deep stacks
2969     count++;
2970     if (MaxJavaStackTraceDepth == count) return;
2971   }
2972 }
2973 
2974 
2975 // JVMTI PopFrame support
2976 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
2977   assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
2978   if (in_bytes(size_in_bytes) != 0) {
2979     _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
2980     _popframe_preserved_args_size = in_bytes(size_in_bytes);
2981     Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
2982   }
2983 }
2984 
2985 void* JavaThread::popframe_preserved_args() {
2986   return _popframe_preserved_args;
2987 }
2988 
2989 ByteSize JavaThread::popframe_preserved_args_size() {
2990   return in_ByteSize(_popframe_preserved_args_size);
2991 }
2992 
2993 WordSize JavaThread::popframe_preserved_args_size_in_words() {
2994   int sz = in_bytes(popframe_preserved_args_size());
2995   assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
2996   return in_WordSize(sz / wordSize);
2997 }
2998 
2999 void JavaThread::popframe_free_preserved_args() {
3000   assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3001   FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3002   _popframe_preserved_args = NULL;
3003   _popframe_preserved_args_size = 0;
3004 }
3005 
3006 #ifndef PRODUCT
3007 
3008 void JavaThread::trace_frames() {
3009   tty->print_cr("[Describe stack]");
3010   int frame_no = 1;
3011   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3012     tty->print("  %d. ", frame_no++);
3013     fst.current()->print_value_on(tty, this);
3014     tty->cr();
3015   }
3016 }
3017 
3018 class PrintAndVerifyOopClosure: public OopClosure {
3019  protected:
3020   template <class T> inline void do_oop_work(T* p) {
3021     oop obj = oopDesc::load_decode_heap_oop(p);
3022     if (obj == NULL) return;
3023     tty->print(INTPTR_FORMAT ": ", p);
3024     if (obj->is_oop_or_null()) {
3025       if (obj->is_objArray()) {
3026         tty->print_cr("valid objArray: " INTPTR_FORMAT, (oopDesc*) obj);
3027       } else {
3028         obj->print();
3029       }
3030     } else {
3031       tty->print_cr("invalid oop: " INTPTR_FORMAT, (oopDesc*) obj);
3032     }
3033     tty->cr();
3034   }
3035  public:
3036   virtual void do_oop(oop* p) { do_oop_work(p); }
3037   virtual void do_oop(narrowOop* p)  { do_oop_work(p); }
3038 };
3039 
3040 
3041 static void oops_print(frame* f, const RegisterMap *map) {
3042   PrintAndVerifyOopClosure print;
3043   f->print_value();
3044   f->oops_do(&print, NULL, NULL, (RegisterMap*)map);
3045 }
3046 
3047 // Print our all the locations that contain oops and whether they are
3048 // valid or not.  This useful when trying to find the oldest frame
3049 // where an oop has gone bad since the frame walk is from youngest to
3050 // oldest.
3051 void JavaThread::trace_oops() {
3052   tty->print_cr("[Trace oops]");
3053   frames_do(oops_print);
3054 }
3055 
3056 
3057 #ifdef ASSERT
3058 // Print or validate the layout of stack frames
3059 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3060   ResourceMark rm;
3061   PRESERVE_EXCEPTION_MARK;
3062   FrameValues values;
3063   int frame_no = 0;
3064   for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3065     fst.current()->describe(values, ++frame_no);
3066     if (depth == frame_no) break;
3067   }
3068   if (validate_only) {
3069     values.validate();
3070   } else {
3071     tty->print_cr("[Describe stack layout]");
3072     values.print(this);
3073   }
3074 }
3075 #endif
3076 
3077 void JavaThread::trace_stack_from(vframe* start_vf) {
3078   ResourceMark rm;
3079   int vframe_no = 1;
3080   for (vframe* f = start_vf; f; f = f->sender()) {
3081     if (f->is_java_frame()) {
3082       javaVFrame::cast(f)->print_activation(vframe_no++);
3083     } else {
3084       f->print();
3085     }
3086     if (vframe_no > StackPrintLimit) {
3087       tty->print_cr("...<more frames>...");
3088       return;
3089     }
3090   }
3091 }
3092 
3093 
3094 void JavaThread::trace_stack() {
3095   if (!has_last_Java_frame()) return;
3096   ResourceMark rm;
3097   HandleMark   hm;
3098   RegisterMap reg_map(this);
3099   trace_stack_from(last_java_vframe(&reg_map));
3100 }
3101 
3102 
3103 #endif // PRODUCT
3104 
3105 
3106 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3107   assert(reg_map != NULL, "a map must be given");
3108   frame f = last_frame();
3109   for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3110     if (vf->is_java_frame()) return javaVFrame::cast(vf);
3111   }
3112   return NULL;
3113 }
3114 
3115 
3116 Klass* JavaThread::security_get_caller_class(int depth) {
3117   vframeStream vfst(this);
3118   vfst.security_get_caller_frame(depth);
3119   if (!vfst.at_end()) {
3120     return vfst.method()->method_holder();
3121   }
3122   return NULL;
3123 }
3124 
3125 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3126   assert(thread->is_Compiler_thread(), "must be compiler thread");
3127   CompileBroker::compiler_thread_loop();
3128 }
3129 
3130 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3131   NMethodSweeper::sweeper_loop();
3132 }
3133 
3134 // Create a CompilerThread
3135 CompilerThread::CompilerThread(CompileQueue* queue,
3136                                CompilerCounters* counters)
3137                                : JavaThread(&compiler_thread_entry) {
3138   _env   = NULL;
3139   _log   = NULL;
3140   _task  = NULL;
3141   _queue = queue;
3142   _counters = counters;
3143   _buffer_blob = NULL;
3144   _compiler = NULL;
3145 
3146 #ifndef PRODUCT
3147   _ideal_graph_printer = NULL;
3148 #endif
3149 }
3150 
3151 // Create sweeper thread
3152 CodeCacheSweeperThread::CodeCacheSweeperThread()
3153 : JavaThread(&sweeper_thread_entry) {
3154   _scanned_nmethod = NULL;
3155 }
3156 void CodeCacheSweeperThread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
3157   JavaThread::oops_do(f, cld_f, cf);
3158   if (_scanned_nmethod != NULL && cf != NULL) {
3159     // Safepoints can occur when the sweeper is scanning an nmethod so
3160     // process it here to make sure it isn't unloaded in the middle of
3161     // a scan.
3162     cf->do_code_blob(_scanned_nmethod);
3163   }
3164 }
3165 
3166 
3167 // ======= Threads ========
3168 
3169 // The Threads class links together all active threads, and provides
3170 // operations over all threads.  It is protected by its own Mutex
3171 // lock, which is also used in other contexts to protect thread
3172 // operations from having the thread being operated on from exiting
3173 // and going away unexpectedly (e.g., safepoint synchronization)
3174 
3175 JavaThread* Threads::_thread_list = NULL;
3176 int         Threads::_number_of_threads = 0;
3177 int         Threads::_number_of_non_daemon_threads = 0;
3178 int         Threads::_return_code = 0;
3179 size_t      JavaThread::_stack_size_at_create = 0;
3180 #ifdef ASSERT
3181 bool        Threads::_vm_complete = false;
3182 #endif
3183 
3184 // All JavaThreads
3185 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
3186 
3187 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3188 void Threads::threads_do(ThreadClosure* tc) {
3189   assert_locked_or_safepoint(Threads_lock);
3190   // ALL_JAVA_THREADS iterates through all JavaThreads
3191   ALL_JAVA_THREADS(p) {
3192     tc->do_thread(p);
3193   }
3194   // Someday we could have a table or list of all non-JavaThreads.
3195   // For now, just manually iterate through them.
3196   tc->do_thread(VMThread::vm_thread());
3197   Universe::heap()->gc_threads_do(tc);
3198   WatcherThread *wt = WatcherThread::watcher_thread();
3199   // Strictly speaking, the following NULL check isn't sufficient to make sure
3200   // the data for WatcherThread is still valid upon being examined. However,
3201   // considering that WatchThread terminates when the VM is on the way to
3202   // exit at safepoint, the chance of the above is extremely small. The right
3203   // way to prevent termination of WatcherThread would be to acquire
3204   // Terminator_lock, but we can't do that without violating the lock rank
3205   // checking in some cases.
3206   if (wt != NULL) {
3207     tc->do_thread(wt);
3208   }
3209 
3210   // If CompilerThreads ever become non-JavaThreads, add them here
3211 }
3212 
3213 
3214 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3215   TraceTime timer("Initialize java.lang classes", TraceStartupTime);
3216 
3217   if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3218     create_vm_init_libraries();
3219   }
3220 
3221   initialize_class(vmSymbols::java_lang_String(), CHECK);
3222 
3223   // Initialize java_lang.System (needed before creating the thread)
3224   initialize_class(vmSymbols::java_lang_System(), CHECK);
3225   initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3226   Handle thread_group = create_initial_thread_group(CHECK);
3227   Universe::set_main_thread_group(thread_group());
3228   initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3229   oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3230   main_thread->set_threadObj(thread_object);
3231   // Set thread status to running since main thread has
3232   // been started and running.
3233   java_lang_Thread::set_thread_status(thread_object,
3234                                       java_lang_Thread::RUNNABLE);
3235 
3236   // The VM creates & returns objects of this class. Make sure it's initialized.
3237   initialize_class(vmSymbols::java_lang_Class(), CHECK);
3238 
3239   // The VM preresolves methods to these classes. Make sure that they get initialized
3240   initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3241   initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3242   call_initializeSystemClass(CHECK);
3243 
3244   // get the Java runtime name after java.lang.System is initialized
3245   JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3246   JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3247 
3248   // an instance of OutOfMemory exception has been allocated earlier
3249   initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3250   initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3251   initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3252   initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3253   initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3254   initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3255   initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3256   initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3257 }
3258 
3259 void Threads::initialize_jsr292_core_classes(TRAPS) {
3260   initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3261   initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3262   initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3263 }
3264 
3265 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3266   extern void JDK_Version_init();
3267 
3268   // Check version
3269   if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3270 
3271   // Initialize the output stream module
3272   ostream_init();
3273 
3274   // Process java launcher properties.
3275   Arguments::process_sun_java_launcher_properties(args);
3276 
3277   // Initialize the os module before using TLS
3278   os::init();
3279 
3280   // Initialize system properties.
3281   Arguments::init_system_properties();
3282 
3283   // So that JDK version can be used as a discriminator when parsing arguments
3284   JDK_Version_init();
3285 
3286   // Update/Initialize System properties after JDK version number is known
3287   Arguments::init_version_specific_system_properties();
3288 
3289   // Parse arguments
3290   jint parse_result = Arguments::parse(args);
3291   if (parse_result != JNI_OK) return parse_result;
3292 
3293   os::init_before_ergo();
3294 
3295   jint ergo_result = Arguments::apply_ergo();
3296   if (ergo_result != JNI_OK) return ergo_result;
3297 
3298   if (PauseAtStartup) {
3299     os::pause();
3300   }
3301 
3302   HOTSPOT_VM_INIT_BEGIN();
3303 
3304   // Record VM creation timing statistics
3305   TraceVmCreationTime create_vm_timer;
3306   create_vm_timer.start();
3307 
3308   // Timing (must come after argument parsing)
3309   TraceTime timer("Create VM", TraceStartupTime);
3310 
3311   // Initialize the os module after parsing the args
3312   jint os_init_2_result = os::init_2();
3313   if (os_init_2_result != JNI_OK) return os_init_2_result;
3314 
3315   jint adjust_after_os_result = Arguments::adjust_after_os();
3316   if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3317 
3318   // initialize TLS
3319   ThreadLocalStorage::init();
3320 
3321   // Initialize output stream logging
3322   ostream_init_log();
3323 
3324   // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3325   // Must be before create_vm_init_agents()
3326   if (Arguments::init_libraries_at_startup()) {
3327     convert_vm_init_libraries_to_agents();
3328   }
3329 
3330   // Launch -agentlib/-agentpath and converted -Xrun agents
3331   if (Arguments::init_agents_at_startup()) {
3332     create_vm_init_agents();
3333   }
3334 
3335   // Initialize Threads state
3336   _thread_list = NULL;
3337   _number_of_threads = 0;
3338   _number_of_non_daemon_threads = 0;
3339 
3340   // Initialize global data structures and create system classes in heap
3341   vm_init_globals();
3342 
3343   // Attach the main thread to this os thread
3344   JavaThread* main_thread = new JavaThread();
3345   main_thread->set_thread_state(_thread_in_vm);
3346   // must do this before set_active_handles and initialize_thread_local_storage
3347   // Note: on solaris initialize_thread_local_storage() will (indirectly)
3348   // change the stack size recorded here to one based on the java thread
3349   // stacksize. This adjusted size is what is used to figure the placement
3350   // of the guard pages.
3351   main_thread->record_stack_base_and_size();
3352   main_thread->initialize_thread_local_storage();
3353 
3354   main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3355 
3356   if (!main_thread->set_as_starting_thread()) {
3357     vm_shutdown_during_initialization(
3358                                       "Failed necessary internal allocation. Out of swap space");
3359     delete main_thread;
3360     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3361     return JNI_ENOMEM;
3362   }
3363 
3364   // Enable guard page *after* os::create_main_thread(), otherwise it would
3365   // crash Linux VM, see notes in os_linux.cpp.
3366   main_thread->create_stack_guard_pages();
3367 
3368   // Initialize Java-Level synchronization subsystem
3369   ObjectMonitor::Initialize();
3370 
3371   // Initialize global modules
3372   jint status = init_globals();
3373   if (status != JNI_OK) {
3374     delete main_thread;
3375     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3376     return status;
3377   }
3378 
3379   // Should be done after the heap is fully created
3380   main_thread->cache_global_variables();
3381 
3382   HandleMark hm;
3383 
3384   { MutexLocker mu(Threads_lock);
3385     Threads::add(main_thread);
3386   }
3387 
3388   // Any JVMTI raw monitors entered in onload will transition into
3389   // real raw monitor. VM is setup enough here for raw monitor enter.
3390   JvmtiExport::transition_pending_onload_raw_monitors();
3391 
3392   // Create the VMThread
3393   { TraceTime timer("Start VMThread", TraceStartupTime);
3394     VMThread::create();
3395     Thread* vmthread = VMThread::vm_thread();
3396 
3397     if (!os::create_thread(vmthread, os::vm_thread)) {
3398       vm_exit_during_initialization("Cannot create VM thread. "
3399                                     "Out of system resources.");
3400     }
3401 
3402     // Wait for the VM thread to become ready, and VMThread::run to initialize
3403     // Monitors can have spurious returns, must always check another state flag
3404     {
3405       MutexLocker ml(Notify_lock);
3406       os::start_thread(vmthread);
3407       while (vmthread->active_handles() == NULL) {
3408         Notify_lock->wait();
3409       }
3410     }
3411   }
3412 
3413   assert(Universe::is_fully_initialized(), "not initialized");
3414   if (VerifyDuringStartup) {
3415     // Make sure we're starting with a clean slate.
3416     VM_Verify verify_op;
3417     VMThread::execute(&verify_op);
3418   }
3419 
3420   Thread* THREAD = Thread::current();
3421 
3422   // At this point, the Universe is initialized, but we have not executed
3423   // any byte code.  Now is a good time (the only time) to dump out the
3424   // internal state of the JVM for sharing.
3425   if (DumpSharedSpaces) {
3426     MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3427     ShouldNotReachHere();
3428   }
3429 
3430   // Always call even when there are not JVMTI environments yet, since environments
3431   // may be attached late and JVMTI must track phases of VM execution
3432   JvmtiExport::enter_start_phase();
3433 
3434   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3435   JvmtiExport::post_vm_start();
3436 
3437   initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3438 
3439   // We need this for ClassDataSharing - the initial vm.info property is set
3440   // with the default value of CDS "sharing" which may be reset through
3441   // command line options.
3442   reset_vm_info_property(CHECK_JNI_ERR);
3443 
3444   quicken_jni_functions();
3445 
3446   // Must be run after init_ft which initializes ft_enabled
3447   if (TRACE_INITIALIZE() != JNI_OK) {
3448     vm_exit_during_initialization("Failed to initialize tracing backend");
3449   }
3450 
3451   // Set flag that basic initialization has completed. Used by exceptions and various
3452   // debug stuff, that does not work until all basic classes have been initialized.
3453   set_init_completed();
3454 
3455   Metaspace::post_initialize();
3456 
3457   HOTSPOT_VM_INIT_END();
3458 
3459   // record VM initialization completion time
3460 #if INCLUDE_MANAGEMENT
3461   Management::record_vm_init_completed();
3462 #endif // INCLUDE_MANAGEMENT
3463 
3464   // Compute system loader. Note that this has to occur after set_init_completed, since
3465   // valid exceptions may be thrown in the process.
3466   // Note that we do not use CHECK_0 here since we are inside an EXCEPTION_MARK and
3467   // set_init_completed has just been called, causing exceptions not to be shortcut
3468   // anymore. We call vm_exit_during_initialization directly instead.
3469   SystemDictionary::compute_java_system_loader(CHECK_JNI_ERR);
3470 
3471 #if INCLUDE_ALL_GCS
3472   // Support for ConcurrentMarkSweep. This should be cleaned up
3473   // and better encapsulated. The ugly nested if test would go away
3474   // once things are properly refactored. XXX YSR
3475   if (UseConcMarkSweepGC || UseG1GC) {
3476     if (UseConcMarkSweepGC) {
3477       ConcurrentMarkSweepThread::makeSurrogateLockerThread(CHECK_JNI_ERR);
3478     } else {
3479       ConcurrentMarkThread::makeSurrogateLockerThread(CHECK_JNI_ERR);
3480     }
3481   }
3482 #endif // INCLUDE_ALL_GCS
3483 
3484   // Always call even when there are not JVMTI environments yet, since environments
3485   // may be attached late and JVMTI must track phases of VM execution
3486   JvmtiExport::enter_live_phase();
3487 
3488   // Signal Dispatcher needs to be started before VMInit event is posted
3489   os::signal_init();
3490 
3491   // Start Attach Listener if +StartAttachListener or it can't be started lazily
3492   if (!DisableAttachMechanism) {
3493     AttachListener::vm_start();
3494     if (StartAttachListener || AttachListener::init_at_startup()) {
3495       AttachListener::init();
3496     }
3497   }
3498 
3499   // Launch -Xrun agents
3500   // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3501   // back-end can launch with -Xdebug -Xrunjdwp.
3502   if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3503     create_vm_init_libraries();
3504   }
3505 
3506   // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3507   JvmtiExport::post_vm_initialized();
3508 
3509   if (TRACE_START() != JNI_OK) {
3510     vm_exit_during_initialization("Failed to start tracing backend.");
3511   }
3512 
3513   if (CleanChunkPoolAsync) {
3514     Chunk::start_chunk_pool_cleaner_task();
3515   }
3516 
3517   // initialize compiler(s)
3518 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK)
3519   CompileBroker::compilation_init();
3520 #endif
3521 
3522   // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3523   // It is done after compilers are initialized, because otherwise compilations of
3524   // signature polymorphic MH intrinsics can be missed
3525   // (see SystemDictionary::find_method_handle_intrinsic).
3526   initialize_jsr292_core_classes(CHECK_JNI_ERR);
3527 
3528 #if INCLUDE_MANAGEMENT
3529   Management::initialize(THREAD);
3530 
3531   if (HAS_PENDING_EXCEPTION) {
3532     // management agent fails to start possibly due to
3533     // configuration problem and is responsible for printing
3534     // stack trace if appropriate. Simply exit VM.
3535     vm_exit(1);
3536   }
3537 #endif // INCLUDE_MANAGEMENT
3538 
3539   if (Arguments::has_profile())       FlatProfiler::engage(main_thread, true);
3540   if (MemProfiling)                   MemProfiler::engage();
3541   StatSampler::engage();
3542   if (CheckJNICalls)                  JniPeriodicChecker::engage();
3543 
3544   BiasedLocking::init();
3545 
3546 #if INCLUDE_RTM_OPT
3547   RTMLockingCounters::init();
3548 #endif
3549 
3550   if (JDK_Version::current().post_vm_init_hook_enabled()) {
3551     call_postVMInitHook(THREAD);
3552     // The Java side of PostVMInitHook.run must deal with all
3553     // exceptions and provide means of diagnosis.
3554     if (HAS_PENDING_EXCEPTION) {
3555       CLEAR_PENDING_EXCEPTION;
3556     }
3557   }
3558 
3559   {
3560     MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
3561     // Make sure the watcher thread can be started by WatcherThread::start()
3562     // or by dynamic enrollment.
3563     WatcherThread::make_startable();
3564     // Start up the WatcherThread if there are any periodic tasks
3565     // NOTE:  All PeriodicTasks should be registered by now. If they
3566     //   aren't, late joiners might appear to start slowly (we might
3567     //   take a while to process their first tick).
3568     if (PeriodicTask::num_tasks() > 0) {
3569       WatcherThread::start();
3570     }
3571   }
3572 
3573   create_vm_timer.end();
3574 #ifdef ASSERT
3575   _vm_complete = true;
3576 #endif
3577   return JNI_OK;
3578 }
3579 
3580 // type for the Agent_OnLoad and JVM_OnLoad entry points
3581 extern "C" {
3582   typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3583 }
3584 // Find a command line agent library and return its entry point for
3585 //         -agentlib:  -agentpath:   -Xrun
3586 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3587 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3588                                     const char *on_load_symbols[],
3589                                     size_t num_symbol_entries) {
3590   OnLoadEntry_t on_load_entry = NULL;
3591   void *library = NULL;
3592 
3593   if (!agent->valid()) {
3594     char buffer[JVM_MAXPATHLEN];
3595     char ebuf[1024] = "";
3596     const char *name = agent->name();
3597     const char *msg = "Could not find agent library ";
3598 
3599     // First check to see if agent is statically linked into executable
3600     if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3601       library = agent->os_lib();
3602     } else if (agent->is_absolute_path()) {
3603       library = os::dll_load(name, ebuf, sizeof ebuf);
3604       if (library == NULL) {
3605         const char *sub_msg = " in absolute path, with error: ";
3606         size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3607         char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3608         jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3609         // If we can't find the agent, exit.
3610         vm_exit_during_initialization(buf, NULL);
3611         FREE_C_HEAP_ARRAY(char, buf);
3612       }
3613     } else {
3614       // Try to load the agent from the standard dll directory
3615       if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(),
3616                              name)) {
3617         library = os::dll_load(buffer, ebuf, sizeof ebuf);
3618       }
3619       if (library == NULL) { // Try the local directory
3620         char ns[1] = {0};
3621         if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) {
3622           library = os::dll_load(buffer, ebuf, sizeof ebuf);
3623         }
3624         if (library == NULL) {
3625           const char *sub_msg = " on the library path, with error: ";
3626           size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3627           char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3628           jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3629           // If we can't find the agent, exit.
3630           vm_exit_during_initialization(buf, NULL);
3631           FREE_C_HEAP_ARRAY(char, buf);
3632         }
3633       }
3634     }
3635     agent->set_os_lib(library);
3636     agent->set_valid();
3637   }
3638 
3639   // Find the OnLoad function.
3640   on_load_entry =
3641     CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
3642                                                           false,
3643                                                           on_load_symbols,
3644                                                           num_symbol_entries));
3645   return on_load_entry;
3646 }
3647 
3648 // Find the JVM_OnLoad entry point
3649 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3650   const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3651   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3652 }
3653 
3654 // Find the Agent_OnLoad entry point
3655 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3656   const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3657   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3658 }
3659 
3660 // For backwards compatibility with -Xrun
3661 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3662 // treated like -agentpath:
3663 // Must be called before agent libraries are created
3664 void Threads::convert_vm_init_libraries_to_agents() {
3665   AgentLibrary* agent;
3666   AgentLibrary* next;
3667 
3668   for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3669     next = agent->next();  // cache the next agent now as this agent may get moved off this list
3670     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3671 
3672     // If there is an JVM_OnLoad function it will get called later,
3673     // otherwise see if there is an Agent_OnLoad
3674     if (on_load_entry == NULL) {
3675       on_load_entry = lookup_agent_on_load(agent);
3676       if (on_load_entry != NULL) {
3677         // switch it to the agent list -- so that Agent_OnLoad will be called,
3678         // JVM_OnLoad won't be attempted and Agent_OnUnload will
3679         Arguments::convert_library_to_agent(agent);
3680       } else {
3681         vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3682       }
3683     }
3684   }
3685 }
3686 
3687 // Create agents for -agentlib:  -agentpath:  and converted -Xrun
3688 // Invokes Agent_OnLoad
3689 // Called very early -- before JavaThreads exist
3690 void Threads::create_vm_init_agents() {
3691   extern struct JavaVM_ main_vm;
3692   AgentLibrary* agent;
3693 
3694   JvmtiExport::enter_onload_phase();
3695 
3696   for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3697     OnLoadEntry_t  on_load_entry = lookup_agent_on_load(agent);
3698 
3699     if (on_load_entry != NULL) {
3700       // Invoke the Agent_OnLoad function
3701       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3702       if (err != JNI_OK) {
3703         vm_exit_during_initialization("agent library failed to init", agent->name());
3704       }
3705     } else {
3706       vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
3707     }
3708   }
3709   JvmtiExport::enter_primordial_phase();
3710 }
3711 
3712 extern "C" {
3713   typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
3714 }
3715 
3716 void Threads::shutdown_vm_agents() {
3717   // Send any Agent_OnUnload notifications
3718   const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
3719   size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
3720   extern struct JavaVM_ main_vm;
3721   for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3722 
3723     // Find the Agent_OnUnload function.
3724     Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
3725                                                    os::find_agent_function(agent,
3726                                                    false,
3727                                                    on_unload_symbols,
3728                                                    num_symbol_entries));
3729 
3730     // Invoke the Agent_OnUnload function
3731     if (unload_entry != NULL) {
3732       JavaThread* thread = JavaThread::current();
3733       ThreadToNativeFromVM ttn(thread);
3734       HandleMark hm(thread);
3735       (*unload_entry)(&main_vm);
3736     }
3737   }
3738 }
3739 
3740 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
3741 // Invokes JVM_OnLoad
3742 void Threads::create_vm_init_libraries() {
3743   extern struct JavaVM_ main_vm;
3744   AgentLibrary* agent;
3745 
3746   for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
3747     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3748 
3749     if (on_load_entry != NULL) {
3750       // Invoke the JVM_OnLoad function
3751       JavaThread* thread = JavaThread::current();
3752       ThreadToNativeFromVM ttn(thread);
3753       HandleMark hm(thread);
3754       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3755       if (err != JNI_OK) {
3756         vm_exit_during_initialization("-Xrun library failed to init", agent->name());
3757       }
3758     } else {
3759       vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
3760     }
3761   }
3762 }
3763 
3764 JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) {
3765   assert(Threads_lock->owned_by_self(), "Must hold Threads_lock");
3766 
3767   JavaThread* java_thread = NULL;
3768   // Sequential search for now.  Need to do better optimization later.
3769   for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) {
3770     oop tobj = thread->threadObj();
3771     if (!thread->is_exiting() &&
3772         tobj != NULL &&
3773         java_tid == java_lang_Thread::thread_id(tobj)) {
3774       java_thread = thread;
3775       break;
3776     }
3777   }
3778   return java_thread;
3779 }
3780 
3781 
3782 // Last thread running calls java.lang.Shutdown.shutdown()
3783 void JavaThread::invoke_shutdown_hooks() {
3784   HandleMark hm(this);
3785 
3786   // We could get here with a pending exception, if so clear it now.
3787   if (this->has_pending_exception()) {
3788     this->clear_pending_exception();
3789   }
3790 
3791   EXCEPTION_MARK;
3792   Klass* k =
3793     SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
3794                                       THREAD);
3795   if (k != NULL) {
3796     // SystemDictionary::resolve_or_null will return null if there was
3797     // an exception.  If we cannot load the Shutdown class, just don't
3798     // call Shutdown.shutdown() at all.  This will mean the shutdown hooks
3799     // and finalizers (if runFinalizersOnExit is set) won't be run.
3800     // Note that if a shutdown hook was registered or runFinalizersOnExit
3801     // was called, the Shutdown class would have already been loaded
3802     // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
3803     instanceKlassHandle shutdown_klass (THREAD, k);
3804     JavaValue result(T_VOID);
3805     JavaCalls::call_static(&result,
3806                            shutdown_klass,
3807                            vmSymbols::shutdown_method_name(),
3808                            vmSymbols::void_method_signature(),
3809                            THREAD);
3810   }
3811   CLEAR_PENDING_EXCEPTION;
3812 }
3813 
3814 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
3815 // the program falls off the end of main(). Another VM exit path is through
3816 // vm_exit() when the program calls System.exit() to return a value or when
3817 // there is a serious error in VM. The two shutdown paths are not exactly
3818 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
3819 // and VM_Exit op at VM level.
3820 //
3821 // Shutdown sequence:
3822 //   + Shutdown native memory tracking if it is on
3823 //   + Wait until we are the last non-daemon thread to execute
3824 //     <-- every thing is still working at this moment -->
3825 //   + Call java.lang.Shutdown.shutdown(), which will invoke Java level
3826 //        shutdown hooks, run finalizers if finalization-on-exit
3827 //   + Call before_exit(), prepare for VM exit
3828 //      > run VM level shutdown hooks (they are registered through JVM_OnExit(),
3829 //        currently the only user of this mechanism is File.deleteOnExit())
3830 //      > stop flat profiler, StatSampler, watcher thread, CMS threads,
3831 //        post thread end and vm death events to JVMTI,
3832 //        stop signal thread
3833 //   + Call JavaThread::exit(), it will:
3834 //      > release JNI handle blocks, remove stack guard pages
3835 //      > remove this thread from Threads list
3836 //     <-- no more Java code from this thread after this point -->
3837 //   + Stop VM thread, it will bring the remaining VM to a safepoint and stop
3838 //     the compiler threads at safepoint
3839 //     <-- do not use anything that could get blocked by Safepoint -->
3840 //   + Disable tracing at JNI/JVM barriers
3841 //   + Set _vm_exited flag for threads that are still running native code
3842 //   + Delete this thread
3843 //   + Call exit_globals()
3844 //      > deletes tty
3845 //      > deletes PerfMemory resources
3846 //   + Return to caller
3847 
3848 bool Threads::destroy_vm() {
3849   JavaThread* thread = JavaThread::current();
3850 
3851 #ifdef ASSERT
3852   _vm_complete = false;
3853 #endif
3854   // Wait until we are the last non-daemon thread to execute
3855   { MutexLocker nu(Threads_lock);
3856     while (Threads::number_of_non_daemon_threads() > 1)
3857       // This wait should make safepoint checks, wait without a timeout,
3858       // and wait as a suspend-equivalent condition.
3859       //
3860       // Note: If the FlatProfiler is running and this thread is waiting
3861       // for another non-daemon thread to finish, then the FlatProfiler
3862       // is waiting for the external suspend request on this thread to
3863       // complete. wait_for_ext_suspend_completion() will eventually
3864       // timeout, but that takes time. Making this wait a suspend-
3865       // equivalent condition solves that timeout problem.
3866       //
3867       Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
3868                          Mutex::_as_suspend_equivalent_flag);
3869   }
3870 
3871   // Hang forever on exit if we are reporting an error.
3872   if (ShowMessageBoxOnError && is_error_reported()) {
3873     os::infinite_sleep();
3874   }
3875   os::wait_for_keypress_at_exit();
3876 
3877   // run Java level shutdown hooks
3878   thread->invoke_shutdown_hooks();
3879 
3880   before_exit(thread);
3881 
3882   thread->exit(true);
3883 
3884   // Stop VM thread.
3885   {
3886     // 4945125 The vm thread comes to a safepoint during exit.
3887     // GC vm_operations can get caught at the safepoint, and the
3888     // heap is unparseable if they are caught. Grab the Heap_lock
3889     // to prevent this. The GC vm_operations will not be able to
3890     // queue until after the vm thread is dead. After this point,
3891     // we'll never emerge out of the safepoint before the VM exits.
3892 
3893     MutexLocker ml(Heap_lock);
3894 
3895     VMThread::wait_for_vm_thread_exit();
3896     assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
3897     VMThread::destroy();
3898   }
3899 
3900   // clean up ideal graph printers
3901 #if defined(COMPILER2) && !defined(PRODUCT)
3902   IdealGraphPrinter::clean_up();
3903 #endif
3904 
3905   // Now, all Java threads are gone except daemon threads. Daemon threads
3906   // running Java code or in VM are stopped by the Safepoint. However,
3907   // daemon threads executing native code are still running.  But they
3908   // will be stopped at native=>Java/VM barriers. Note that we can't
3909   // simply kill or suspend them, as it is inherently deadlock-prone.
3910 
3911 #ifndef PRODUCT
3912   // disable function tracing at JNI/JVM barriers
3913   TraceJNICalls = false;
3914   TraceJVMCalls = false;
3915   TraceRuntimeCalls = false;
3916 #endif
3917 
3918   VM_Exit::set_vm_exited();
3919 
3920   notify_vm_shutdown();
3921 
3922   delete thread;
3923 
3924   // exit_globals() will delete tty
3925   exit_globals();
3926 
3927   return true;
3928 }
3929 
3930 
3931 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
3932   if (version == JNI_VERSION_1_1) return JNI_TRUE;
3933   return is_supported_jni_version(version);
3934 }
3935 
3936 
3937 jboolean Threads::is_supported_jni_version(jint version) {
3938   if (version == JNI_VERSION_1_2) return JNI_TRUE;
3939   if (version == JNI_VERSION_1_4) return JNI_TRUE;
3940   if (version == JNI_VERSION_1_6) return JNI_TRUE;
3941   if (version == JNI_VERSION_1_8) return JNI_TRUE;
3942   return JNI_FALSE;
3943 }
3944 
3945 
3946 void Threads::add(JavaThread* p, bool force_daemon) {
3947   // The threads lock must be owned at this point
3948   assert_locked_or_safepoint(Threads_lock);
3949 
3950   // See the comment for this method in thread.hpp for its purpose and
3951   // why it is called here.
3952   p->initialize_queues();
3953   p->set_next(_thread_list);
3954   _thread_list = p;
3955   _number_of_threads++;
3956   oop threadObj = p->threadObj();
3957   bool daemon = true;
3958   // Bootstrapping problem: threadObj can be null for initial
3959   // JavaThread (or for threads attached via JNI)
3960   if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
3961     _number_of_non_daemon_threads++;
3962     daemon = false;
3963   }
3964 
3965   ThreadService::add_thread(p, daemon);
3966 
3967   // Possible GC point.
3968   Events::log(p, "Thread added: " INTPTR_FORMAT, p);
3969 }
3970 
3971 void Threads::remove(JavaThread* p) {
3972   // Extra scope needed for Thread_lock, so we can check
3973   // that we do not remove thread without safepoint code notice
3974   { MutexLocker ml(Threads_lock);
3975 
3976     assert(includes(p), "p must be present");
3977 
3978     JavaThread* current = _thread_list;
3979     JavaThread* prev    = NULL;
3980 
3981     while (current != p) {
3982       prev    = current;
3983       current = current->next();
3984     }
3985 
3986     if (prev) {
3987       prev->set_next(current->next());
3988     } else {
3989       _thread_list = p->next();
3990     }
3991     _number_of_threads--;
3992     oop threadObj = p->threadObj();
3993     bool daemon = true;
3994     if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
3995       _number_of_non_daemon_threads--;
3996       daemon = false;
3997 
3998       // Only one thread left, do a notify on the Threads_lock so a thread waiting
3999       // on destroy_vm will wake up.
4000       if (number_of_non_daemon_threads() == 1) {
4001         Threads_lock->notify_all();
4002       }
4003     }
4004     ThreadService::remove_thread(p, daemon);
4005 
4006     // Make sure that safepoint code disregard this thread. This is needed since
4007     // the thread might mess around with locks after this point. This can cause it
4008     // to do callbacks into the safepoint code. However, the safepoint code is not aware
4009     // of this thread since it is removed from the queue.
4010     p->set_terminated_value();
4011   } // unlock Threads_lock
4012 
4013   // Since Events::log uses a lock, we grab it outside the Threads_lock
4014   Events::log(p, "Thread exited: " INTPTR_FORMAT, p);
4015 }
4016 
4017 // Threads_lock must be held when this is called (or must be called during a safepoint)
4018 bool Threads::includes(JavaThread* p) {
4019   assert(Threads_lock->is_locked(), "sanity check");
4020   ALL_JAVA_THREADS(q) {
4021     if (q == p) {
4022       return true;
4023     }
4024   }
4025   return false;
4026 }
4027 
4028 // Operations on the Threads list for GC.  These are not explicitly locked,
4029 // but the garbage collector must provide a safe context for them to run.
4030 // In particular, these things should never be called when the Threads_lock
4031 // is held by some other thread. (Note: the Safepoint abstraction also
4032 // uses the Threads_lock to guarantee this property. It also makes sure that
4033 // all threads gets blocked when exiting or starting).
4034 
4035 void Threads::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
4036   ALL_JAVA_THREADS(p) {
4037     p->oops_do(f, cld_f, cf);
4038   }
4039   VMThread::vm_thread()->oops_do(f, cld_f, cf);
4040 }
4041 
4042 void Threads::possibly_parallel_oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
4043   // Introduce a mechanism allowing parallel threads to claim threads as
4044   // root groups.  Overhead should be small enough to use all the time,
4045   // even in sequential code.
4046   SharedHeap* sh = SharedHeap::heap();
4047   // Cannot yet substitute active_workers for n_par_threads
4048   // because of G1CollectedHeap::verify() use of
4049   // SharedHeap::process_roots().  n_par_threads == 0 will
4050   // turn off parallelism in process_roots while active_workers
4051   // is being used for parallelism elsewhere.
4052   bool is_par = sh->n_par_threads() > 0;
4053   assert(!is_par ||
4054          (SharedHeap::heap()->n_par_threads() ==
4055          SharedHeap::heap()->workers()->active_workers()), "Mismatch");
4056   int cp = SharedHeap::heap()->strong_roots_parity();
4057   ALL_JAVA_THREADS(p) {
4058     if (p->claim_oops_do(is_par, cp)) {
4059       p->oops_do(f, cld_f, cf);
4060     }
4061   }
4062   VMThread* vmt = VMThread::vm_thread();
4063   if (vmt->claim_oops_do(is_par, cp)) {
4064     vmt->oops_do(f, cld_f, cf);
4065   }
4066 }
4067 
4068 #if INCLUDE_ALL_GCS
4069 // Used by ParallelScavenge
4070 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4071   ALL_JAVA_THREADS(p) {
4072     q->enqueue(new ThreadRootsTask(p));
4073   }
4074   q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4075 }
4076 
4077 // Used by Parallel Old
4078 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4079   ALL_JAVA_THREADS(p) {
4080     q->enqueue(new ThreadRootsMarkingTask(p));
4081   }
4082   q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4083 }
4084 #endif // INCLUDE_ALL_GCS
4085 
4086 void Threads::nmethods_do(CodeBlobClosure* cf) {
4087   ALL_JAVA_THREADS(p) {
4088     p->nmethods_do(cf);
4089   }
4090   VMThread::vm_thread()->nmethods_do(cf);
4091 }
4092 
4093 void Threads::metadata_do(void f(Metadata*)) {
4094   ALL_JAVA_THREADS(p) {
4095     p->metadata_do(f);
4096   }
4097 }
4098 
4099 void Threads::deoptimized_wrt_marked_nmethods() {
4100   ALL_JAVA_THREADS(p) {
4101     p->deoptimized_wrt_marked_nmethods();
4102   }
4103 }
4104 
4105 
4106 // Get count Java threads that are waiting to enter the specified monitor.
4107 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
4108                                                          address monitor,
4109                                                          bool doLock) {
4110   assert(doLock || SafepointSynchronize::is_at_safepoint(),
4111          "must grab Threads_lock or be at safepoint");
4112   GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4113 
4114   int i = 0;
4115   {
4116     MutexLockerEx ml(doLock ? Threads_lock : NULL);
4117     ALL_JAVA_THREADS(p) {
4118       if (p->is_Compiler_thread()) continue;
4119 
4120       address pending = (address)p->current_pending_monitor();
4121       if (pending == monitor) {             // found a match
4122         if (i < count) result->append(p);   // save the first count matches
4123         i++;
4124       }
4125     }
4126   }
4127   return result;
4128 }
4129 
4130 
4131 JavaThread *Threads::owning_thread_from_monitor_owner(address owner,
4132                                                       bool doLock) {
4133   assert(doLock ||
4134          Threads_lock->owned_by_self() ||
4135          SafepointSynchronize::is_at_safepoint(),
4136          "must grab Threads_lock or be at safepoint");
4137 
4138   // NULL owner means not locked so we can skip the search
4139   if (owner == NULL) return NULL;
4140 
4141   {
4142     MutexLockerEx ml(doLock ? Threads_lock : NULL);
4143     ALL_JAVA_THREADS(p) {
4144       // first, see if owner is the address of a Java thread
4145       if (owner == (address)p) return p;
4146     }
4147   }
4148   // Cannot assert on lack of success here since this function may be
4149   // used by code that is trying to report useful problem information
4150   // like deadlock detection.
4151   if (UseHeavyMonitors) return NULL;
4152 
4153   // If we didn't find a matching Java thread and we didn't force use of
4154   // heavyweight monitors, then the owner is the stack address of the
4155   // Lock Word in the owning Java thread's stack.
4156   //
4157   JavaThread* the_owner = NULL;
4158   {
4159     MutexLockerEx ml(doLock ? Threads_lock : NULL);
4160     ALL_JAVA_THREADS(q) {
4161       if (q->is_lock_owned(owner)) {
4162         the_owner = q;
4163         break;
4164       }
4165     }
4166   }
4167   // cannot assert on lack of success here; see above comment
4168   return the_owner;
4169 }
4170 
4171 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4172 void Threads::print_on(outputStream* st, bool print_stacks,
4173                        bool internal_format, bool print_concurrent_locks) {
4174   char buf[32];
4175   st->print_cr("%s", os::local_time_string(buf, sizeof(buf)));
4176 
4177   st->print_cr("Full thread dump %s (%s %s):",
4178                Abstract_VM_Version::vm_name(),
4179                Abstract_VM_Version::vm_release(),
4180                Abstract_VM_Version::vm_info_string());
4181   st->cr();
4182 
4183 #if INCLUDE_ALL_GCS
4184   // Dump concurrent locks
4185   ConcurrentLocksDump concurrent_locks;
4186   if (print_concurrent_locks) {
4187     concurrent_locks.dump_at_safepoint();
4188   }
4189 #endif // INCLUDE_ALL_GCS
4190 
4191   ALL_JAVA_THREADS(p) {
4192     ResourceMark rm;
4193     p->print_on(st);
4194     if (print_stacks) {
4195       if (internal_format) {
4196         p->trace_stack();
4197       } else {
4198         p->print_stack_on(st);
4199       }
4200     }
4201     st->cr();
4202 #if INCLUDE_ALL_GCS
4203     if (print_concurrent_locks) {
4204       concurrent_locks.print_locks_on(p, st);
4205     }
4206 #endif // INCLUDE_ALL_GCS
4207   }
4208 
4209   VMThread::vm_thread()->print_on(st);
4210   st->cr();
4211   Universe::heap()->print_gc_threads_on(st);
4212   WatcherThread* wt = WatcherThread::watcher_thread();
4213   if (wt != NULL) {
4214     wt->print_on(st);
4215     st->cr();
4216   }
4217   CompileBroker::print_compiler_threads_on(st);
4218   st->flush();
4219 }
4220 
4221 // Threads::print_on_error() is called by fatal error handler. It's possible
4222 // that VM is not at safepoint and/or current thread is inside signal handler.
4223 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4224 // memory (even in resource area), it might deadlock the error handler.
4225 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4226                              int buflen) {
4227   bool found_current = false;
4228   st->print_cr("Java Threads: ( => current thread )");
4229   ALL_JAVA_THREADS(thread) {
4230     bool is_current = (current == thread);
4231     found_current = found_current || is_current;
4232 
4233     st->print("%s", is_current ? "=>" : "  ");
4234 
4235     st->print(PTR_FORMAT, thread);
4236     st->print(" ");
4237     thread->print_on_error(st, buf, buflen);
4238     st->cr();
4239   }
4240   st->cr();
4241 
4242   st->print_cr("Other Threads:");
4243   if (VMThread::vm_thread()) {
4244     bool is_current = (current == VMThread::vm_thread());
4245     found_current = found_current || is_current;
4246     st->print("%s", current == VMThread::vm_thread() ? "=>" : "  ");
4247 
4248     st->print(PTR_FORMAT, VMThread::vm_thread());
4249     st->print(" ");
4250     VMThread::vm_thread()->print_on_error(st, buf, buflen);
4251     st->cr();
4252   }
4253   WatcherThread* wt = WatcherThread::watcher_thread();
4254   if (wt != NULL) {
4255     bool is_current = (current == wt);
4256     found_current = found_current || is_current;
4257     st->print("%s", is_current ? "=>" : "  ");
4258 
4259     st->print(PTR_FORMAT, wt);
4260     st->print(" ");
4261     wt->print_on_error(st, buf, buflen);
4262     st->cr();
4263   }
4264   if (!found_current) {
4265     st->cr();
4266     st->print("=>" PTR_FORMAT " (exited) ", current);
4267     current->print_on_error(st, buf, buflen);
4268     st->cr();
4269   }
4270 }
4271 
4272 // Internal SpinLock and Mutex
4273 // Based on ParkEvent
4274 
4275 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4276 //
4277 // We employ SpinLocks _only for low-contention, fixed-length
4278 // short-duration critical sections where we're concerned
4279 // about native mutex_t or HotSpot Mutex:: latency.
4280 // The mux construct provides a spin-then-block mutual exclusion
4281 // mechanism.
4282 //
4283 // Testing has shown that contention on the ListLock guarding gFreeList
4284 // is common.  If we implement ListLock as a simple SpinLock it's common
4285 // for the JVM to devolve to yielding with little progress.  This is true
4286 // despite the fact that the critical sections protected by ListLock are
4287 // extremely short.
4288 //
4289 // TODO-FIXME: ListLock should be of type SpinLock.
4290 // We should make this a 1st-class type, integrated into the lock
4291 // hierarchy as leaf-locks.  Critically, the SpinLock structure
4292 // should have sufficient padding to avoid false-sharing and excessive
4293 // cache-coherency traffic.
4294 
4295 
4296 typedef volatile int SpinLockT;
4297 
4298 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4299   if (Atomic::cmpxchg (1, adr, 0) == 0) {
4300     return;   // normal fast-path return
4301   }
4302 
4303   // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4304   TEVENT(SpinAcquire - ctx);
4305   int ctr = 0;
4306   int Yields = 0;
4307   for (;;) {
4308     while (*adr != 0) {
4309       ++ctr;
4310       if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4311         if (Yields > 5) {
4312           os::naked_short_sleep(1);
4313         } else {
4314           os::naked_yield();
4315           ++Yields;
4316         }
4317       } else {
4318         SpinPause();
4319       }
4320     }
4321     if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4322   }
4323 }
4324 
4325 void Thread::SpinRelease(volatile int * adr) {
4326   assert(*adr != 0, "invariant");
4327   OrderAccess::fence();      // guarantee at least release consistency.
4328   // Roach-motel semantics.
4329   // It's safe if subsequent LDs and STs float "up" into the critical section,
4330   // but prior LDs and STs within the critical section can't be allowed
4331   // to reorder or float past the ST that releases the lock.
4332   // Loads and stores in the critical section - which appear in program
4333   // order before the store that releases the lock - must also appear
4334   // before the store that releases the lock in memory visibility order.
4335   // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4336   // the ST of 0 into the lock-word which releases the lock, so fence
4337   // more than covers this on all platforms.
4338   *adr = 0;
4339 }
4340 
4341 // muxAcquire and muxRelease:
4342 //
4343 // *  muxAcquire and muxRelease support a single-word lock-word construct.
4344 //    The LSB of the word is set IFF the lock is held.
4345 //    The remainder of the word points to the head of a singly-linked list
4346 //    of threads blocked on the lock.
4347 //
4348 // *  The current implementation of muxAcquire-muxRelease uses its own
4349 //    dedicated Thread._MuxEvent instance.  If we're interested in
4350 //    minimizing the peak number of extant ParkEvent instances then
4351 //    we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4352 //    as certain invariants were satisfied.  Specifically, care would need
4353 //    to be taken with regards to consuming unpark() "permits".
4354 //    A safe rule of thumb is that a thread would never call muxAcquire()
4355 //    if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4356 //    park().  Otherwise the _ParkEvent park() operation in muxAcquire() could
4357 //    consume an unpark() permit intended for monitorenter, for instance.
4358 //    One way around this would be to widen the restricted-range semaphore
4359 //    implemented in park().  Another alternative would be to provide
4360 //    multiple instances of the PlatformEvent() for each thread.  One
4361 //    instance would be dedicated to muxAcquire-muxRelease, for instance.
4362 //
4363 // *  Usage:
4364 //    -- Only as leaf locks
4365 //    -- for short-term locking only as muxAcquire does not perform
4366 //       thread state transitions.
4367 //
4368 // Alternatives:
4369 // *  We could implement muxAcquire and muxRelease with MCS or CLH locks
4370 //    but with parking or spin-then-park instead of pure spinning.
4371 // *  Use Taura-Oyama-Yonenzawa locks.
4372 // *  It's possible to construct a 1-0 lock if we encode the lockword as
4373 //    (List,LockByte).  Acquire will CAS the full lockword while Release
4374 //    will STB 0 into the LockByte.  The 1-0 scheme admits stranding, so
4375 //    acquiring threads use timers (ParkTimed) to detect and recover from
4376 //    the stranding window.  Thread/Node structures must be aligned on 256-byte
4377 //    boundaries by using placement-new.
4378 // *  Augment MCS with advisory back-link fields maintained with CAS().
4379 //    Pictorially:  LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4380 //    The validity of the backlinks must be ratified before we trust the value.
4381 //    If the backlinks are invalid the exiting thread must back-track through the
4382 //    the forward links, which are always trustworthy.
4383 // *  Add a successor indication.  The LockWord is currently encoded as
4384 //    (List, LOCKBIT:1).  We could also add a SUCCBIT or an explicit _succ variable
4385 //    to provide the usual futile-wakeup optimization.
4386 //    See RTStt for details.
4387 // *  Consider schedctl.sc_nopreempt to cover the critical section.
4388 //
4389 
4390 
4391 typedef volatile intptr_t MutexT;      // Mux Lock-word
4392 enum MuxBits { LOCKBIT = 1 };
4393 
4394 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4395   intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4396   if (w == 0) return;
4397   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4398     return;
4399   }
4400 
4401   TEVENT(muxAcquire - Contention);
4402   ParkEvent * const Self = Thread::current()->_MuxEvent;
4403   assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4404   for (;;) {
4405     int its = (os::is_MP() ? 100 : 0) + 1;
4406 
4407     // Optional spin phase: spin-then-park strategy
4408     while (--its >= 0) {
4409       w = *Lock;
4410       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4411         return;
4412       }
4413     }
4414 
4415     Self->reset();
4416     Self->OnList = intptr_t(Lock);
4417     // The following fence() isn't _strictly necessary as the subsequent
4418     // CAS() both serializes execution and ratifies the fetched *Lock value.
4419     OrderAccess::fence();
4420     for (;;) {
4421       w = *Lock;
4422       if ((w & LOCKBIT) == 0) {
4423         if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4424           Self->OnList = 0;   // hygiene - allows stronger asserts
4425           return;
4426         }
4427         continue;      // Interference -- *Lock changed -- Just retry
4428       }
4429       assert(w & LOCKBIT, "invariant");
4430       Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4431       if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4432     }
4433 
4434     while (Self->OnList != 0) {
4435       Self->park();
4436     }
4437   }
4438 }
4439 
4440 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4441   intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4442   if (w == 0) return;
4443   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4444     return;
4445   }
4446 
4447   TEVENT(muxAcquire - Contention);
4448   ParkEvent * ReleaseAfter = NULL;
4449   if (ev == NULL) {
4450     ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4451   }
4452   assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4453   for (;;) {
4454     guarantee(ev->OnList == 0, "invariant");
4455     int its = (os::is_MP() ? 100 : 0) + 1;
4456 
4457     // Optional spin phase: spin-then-park strategy
4458     while (--its >= 0) {
4459       w = *Lock;
4460       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4461         if (ReleaseAfter != NULL) {
4462           ParkEvent::Release(ReleaseAfter);
4463         }
4464         return;
4465       }
4466     }
4467 
4468     ev->reset();
4469     ev->OnList = intptr_t(Lock);
4470     // The following fence() isn't _strictly necessary as the subsequent
4471     // CAS() both serializes execution and ratifies the fetched *Lock value.
4472     OrderAccess::fence();
4473     for (;;) {
4474       w = *Lock;
4475       if ((w & LOCKBIT) == 0) {
4476         if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4477           ev->OnList = 0;
4478           // We call ::Release while holding the outer lock, thus
4479           // artificially lengthening the critical section.
4480           // Consider deferring the ::Release() until the subsequent unlock(),
4481           // after we've dropped the outer lock.
4482           if (ReleaseAfter != NULL) {
4483             ParkEvent::Release(ReleaseAfter);
4484           }
4485           return;
4486         }
4487         continue;      // Interference -- *Lock changed -- Just retry
4488       }
4489       assert(w & LOCKBIT, "invariant");
4490       ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4491       if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4492     }
4493 
4494     while (ev->OnList != 0) {
4495       ev->park();
4496     }
4497   }
4498 }
4499 
4500 // Release() must extract a successor from the list and then wake that thread.
4501 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4502 // similar to that used by ParkEvent::Allocate() and ::Release().  DMR-based
4503 // Release() would :
4504 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4505 // (B) Extract a successor from the private list "in-hand"
4506 // (C) attempt to CAS() the residual back into *Lock over null.
4507 //     If there were any newly arrived threads and the CAS() would fail.
4508 //     In that case Release() would detach the RATs, re-merge the list in-hand
4509 //     with the RATs and repeat as needed.  Alternately, Release() might
4510 //     detach and extract a successor, but then pass the residual list to the wakee.
4511 //     The wakee would be responsible for reattaching and remerging before it
4512 //     competed for the lock.
4513 //
4514 // Both "pop" and DMR are immune from ABA corruption -- there can be
4515 // multiple concurrent pushers, but only one popper or detacher.
4516 // This implementation pops from the head of the list.  This is unfair,
4517 // but tends to provide excellent throughput as hot threads remain hot.
4518 // (We wake recently run threads first).
4519 //
4520 // All paths through muxRelease() will execute a CAS.
4521 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4522 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4523 // executed within the critical section are complete and globally visible before the
4524 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4525 void Thread::muxRelease(volatile intptr_t * Lock)  {
4526   for (;;) {
4527     const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT);
4528     assert(w & LOCKBIT, "invariant");
4529     if (w == LOCKBIT) return;
4530     ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4531     assert(List != NULL, "invariant");
4532     assert(List->OnList == intptr_t(Lock), "invariant");
4533     ParkEvent * const nxt = List->ListNext;
4534     guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4535 
4536     // The following CAS() releases the lock and pops the head element.
4537     // The CAS() also ratifies the previously fetched lock-word value.
4538     if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4539       continue;
4540     }
4541     List->OnList = 0;
4542     OrderAccess::fence();
4543     List->unpark();
4544     return;
4545   }
4546 }
4547 
4548 
4549 void Threads::verify() {
4550   ALL_JAVA_THREADS(p) {
4551     p->verify();
4552   }
4553   VMThread* thread = VMThread::vm_thread();
4554   if (thread != NULL) thread->verify();
4555 }
--- EOF ---