1 /*
   2  * Copyright (c) 1997, 2015, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "classfile/classLoader.hpp"
  27 #include "classfile/javaClasses.hpp"
  28 #include "classfile/systemDictionary.hpp"
  29 #include "classfile/vmSymbols.hpp"
  30 #include "code/codeCache.hpp"
  31 #include "code/scopeDesc.hpp"
  32 #include "compiler/compileBroker.hpp"
  33 #include "gc/shared/gcLocker.inline.hpp"
  34 #include "gc/shared/workgroup.hpp"
  35 #include "interpreter/interpreter.hpp"
  36 #include "interpreter/linkResolver.hpp"
  37 #include "interpreter/oopMapCache.hpp"
  38 #include "jvmtifiles/jvmtiEnv.hpp"
  39 #include "memory/metaspaceShared.hpp"
  40 #include "memory/oopFactory.hpp"
  41 #include "memory/universe.inline.hpp"
  42 #include "oops/instanceKlass.hpp"
  43 #include "oops/objArrayOop.hpp"
  44 #include "oops/oop.inline.hpp"
  45 #include "oops/symbol.hpp"
  46 #include "oops/verifyOopClosure.hpp"
  47 #include "prims/jvm_misc.hpp"
  48 #include "prims/jvmtiExport.hpp"
  49 #include "prims/jvmtiThreadState.hpp"
  50 #include "prims/privilegedStack.hpp"
  51 #include "runtime/arguments.hpp"
  52 #include "runtime/atomic.inline.hpp"
  53 #include "runtime/biasedLocking.hpp"
  54 #include "runtime/deoptimization.hpp"
  55 #include "runtime/fprofiler.hpp"
  56 #include "runtime/frame.inline.hpp"

  57 #include "runtime/init.hpp"
  58 #include "runtime/interfaceSupport.hpp"
  59 #include "runtime/java.hpp"
  60 #include "runtime/javaCalls.hpp"
  61 #include "runtime/jniPeriodicChecker.hpp"
  62 #include "runtime/memprofiler.hpp"
  63 #include "runtime/mutexLocker.hpp"
  64 #include "runtime/objectMonitor.hpp"
  65 #include "runtime/orderAccess.inline.hpp"
  66 #include "runtime/osThread.hpp"
  67 #include "runtime/safepoint.hpp"
  68 #include "runtime/sharedRuntime.hpp"
  69 #include "runtime/statSampler.hpp"
  70 #include "runtime/stubRoutines.hpp"
  71 #include "runtime/sweeper.hpp"
  72 #include "runtime/task.hpp"
  73 #include "runtime/thread.inline.hpp"
  74 #include "runtime/threadCritical.hpp"
  75 #include "runtime/threadLocalStorage.hpp"
  76 #include "runtime/vframe.hpp"
  77 #include "runtime/vframeArray.hpp"
  78 #include "runtime/vframe_hp.hpp"
  79 #include "runtime/vmThread.hpp"
  80 #include "runtime/vm_operations.hpp"
  81 #include "runtime/vm_version.hpp"
  82 #include "services/attachListener.hpp"
  83 #include "services/management.hpp"
  84 #include "services/memTracker.hpp"
  85 #include "services/threadService.hpp"
  86 #include "trace/traceMacros.hpp"
  87 #include "trace/tracing.hpp"
  88 #include "utilities/defaultStream.hpp"
  89 #include "utilities/dtrace.hpp"
  90 #include "utilities/events.hpp"
  91 #include "utilities/macros.hpp"
  92 #include "utilities/preserveException.hpp"
  93 #if INCLUDE_ALL_GCS
  94 #include "gc/cms/concurrentMarkSweepThread.hpp"
  95 #include "gc/g1/concurrentMarkThread.inline.hpp"
  96 #include "gc/parallel/pcTasks.hpp"
  97 #endif // INCLUDE_ALL_GCS
  98 #ifdef COMPILER1
  99 #include "c1/c1_Compiler.hpp"
 100 #endif
 101 #ifdef COMPILER2
 102 #include "opto/c2compiler.hpp"
 103 #include "opto/idealGraphPrinter.hpp"
 104 #endif
 105 #if INCLUDE_RTM_OPT
 106 #include "runtime/rtmLocking.hpp"
 107 #endif
 108 
 109 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
 110 
 111 #ifdef DTRACE_ENABLED
 112 
 113 // Only bother with this argument setup if dtrace is available
 114 
 115   #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
 116   #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
 117 
 118   #define DTRACE_THREAD_PROBE(probe, javathread)                           \
 119     {                                                                      \
 120       ResourceMark rm(this);                                               \
 121       int len = 0;                                                         \
 122       const char* name = (javathread)->get_thread_name();                  \
 123       len = strlen(name);                                                  \
 124       HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */               \
 125         (char *) name, len,                                                \
 126         java_lang_Thread::thread_id((javathread)->threadObj()),            \
 127         (uintptr_t) (javathread)->osthread()->thread_id(),                 \
 128         java_lang_Thread::is_daemon((javathread)->threadObj()));           \
 129     }
 130 
 131 #else //  ndef DTRACE_ENABLED
 132 
 133   #define DTRACE_THREAD_PROBE(probe, javathread)
 134 
 135 #endif // ndef DTRACE_ENABLED
 136 
 137 
 138 // Class hierarchy
 139 // - Thread
 140 //   - VMThread
 141 //   - WatcherThread
 142 //   - ConcurrentMarkSweepThread
 143 //   - JavaThread
 144 //     - CompilerThread
 145 
 146 // ======= Thread ========
 147 // Support for forcing alignment of thread objects for biased locking
 148 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
 149   if (UseBiasedLocking) {
 150     const int alignment = markOopDesc::biased_lock_alignment;
 151     size_t aligned_size = size + (alignment - sizeof(intptr_t));
 152     void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
 153                                           : AllocateHeap(aligned_size, flags, CURRENT_PC,
 154                                                          AllocFailStrategy::RETURN_NULL);
 155     void* aligned_addr     = (void*) align_size_up((intptr_t) real_malloc_addr, alignment);
 156     assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
 157            ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
 158            "JavaThread alignment code overflowed allocated storage");
 159     if (TraceBiasedLocking) {
 160       if (aligned_addr != real_malloc_addr) {
 161         tty->print_cr("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
 162                       real_malloc_addr, aligned_addr);
 163       }
 164     }
 165     ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
 166     return aligned_addr;
 167   } else {
 168     return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
 169                        : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
 170   }
 171 }
 172 
 173 void Thread::operator delete(void* p) {
 174   if (UseBiasedLocking) {
 175     void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;
 176     FreeHeap(real_malloc_addr);
 177   } else {
 178     FreeHeap(p);
 179   }
 180 }
 181 
 182 
 183 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
 184 // JavaThread
 185 
 186 
 187 Thread::Thread() {
 188   // stack and get_thread
 189   set_stack_base(NULL);
 190   set_stack_size(0);
 191   set_self_raw_id(0);
 192   set_lgrp_id(-1);
 193   DEBUG_ONLY(clear_suspendible_thread();)
 194 
 195   // allocated data structures
 196   set_osthread(NULL);
 197   set_resource_area(new (mtThread)ResourceArea());
 198   DEBUG_ONLY(_current_resource_mark = NULL;)
 199   set_handle_area(new (mtThread) HandleArea(NULL));
 200   set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
 201   set_active_handles(NULL);
 202   set_free_handle_block(NULL);
 203   set_last_handle_mark(NULL);
 204 
 205   // This initial value ==> never claimed.
 206   _oops_do_parity = 0;
 207 
 208   // the handle mark links itself to last_handle_mark
 209   new HandleMark(this);
 210 
 211   // plain initialization
 212   debug_only(_owned_locks = NULL;)
 213   debug_only(_allow_allocation_count = 0;)
 214   NOT_PRODUCT(_allow_safepoint_count = 0;)
 215   NOT_PRODUCT(_skip_gcalot = false;)
 216   _jvmti_env_iteration_count = 0;
 217   set_allocated_bytes(0);
 218   _vm_operation_started_count = 0;
 219   _vm_operation_completed_count = 0;
 220   _current_pending_monitor = NULL;
 221   _current_pending_monitor_is_from_java = true;
 222   _current_waiting_monitor = NULL;
 223   _num_nested_signal = 0;
 224   omFreeList = NULL;
 225   omFreeCount = 0;
 226   omFreeProvision = 32;
 227   omInUseList = NULL;
 228   omInUseCount = 0;
 229 
 230 #ifdef ASSERT
 231   _visited_for_critical_count = false;
 232 #endif
 233 
 234   _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
 235                          Monitor::_safepoint_check_sometimes);
 236   _suspend_flags = 0;
 237 
 238   // thread-specific hashCode stream generator state - Marsaglia shift-xor form
 239   _hashStateX = os::random();
 240   _hashStateY = 842502087;
 241   _hashStateZ = 0x8767;    // (int)(3579807591LL & 0xffff) ;
 242   _hashStateW = 273326509;
 243 
 244   _OnTrap   = 0;
 245   _schedctl = NULL;
 246   _Stalled  = 0;
 247   _TypeTag  = 0x2BAD;
 248 
 249   // Many of the following fields are effectively final - immutable
 250   // Note that nascent threads can't use the Native Monitor-Mutex
 251   // construct until the _MutexEvent is initialized ...
 252   // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
 253   // we might instead use a stack of ParkEvents that we could provision on-demand.
 254   // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
 255   // and ::Release()
 256   _ParkEvent   = ParkEvent::Allocate(this);
 257   _SleepEvent  = ParkEvent::Allocate(this);
 258   _MutexEvent  = ParkEvent::Allocate(this);
 259   _MuxEvent    = ParkEvent::Allocate(this);
 260 
 261 #ifdef CHECK_UNHANDLED_OOPS
 262   if (CheckUnhandledOops) {
 263     _unhandled_oops = new UnhandledOops(this);
 264   }
 265 #endif // CHECK_UNHANDLED_OOPS
 266 #ifdef ASSERT
 267   if (UseBiasedLocking) {
 268     assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
 269     assert(this == _real_malloc_address ||
 270            this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment),
 271            "bug in forced alignment of thread objects");
 272   }
 273 #endif // ASSERT
 274 }
 275 
 276 // Non-inlined version to be used where thread.inline.hpp shouldn't be included.
 277 Thread* Thread::current_noinline() {
 278   return Thread::current();
 279 }
 280 
 281 void Thread::initialize_thread_local_storage() {
 282   // Note: Make sure this method only calls
 283   // non-blocking operations. Otherwise, it might not work
 284   // with the thread-startup/safepoint interaction.
 285 
 286   // During Java thread startup, safepoint code should allow this
 287   // method to complete because it may need to allocate memory to
 288   // store information for the new thread.
 289 
 290   // initialize structure dependent on thread local storage
 291   ThreadLocalStorage::set_thread(this);
 292 }
 293 
 294 void Thread::record_stack_base_and_size() {
 295   set_stack_base(os::current_stack_base());
 296   set_stack_size(os::current_stack_size());
 297   if (is_Java_thread()) {
 298     ((JavaThread*) this)->set_stack_overflow_limit();
 299   }
 300   // CR 7190089: on Solaris, primordial thread's stack is adjusted
 301   // in initialize_thread(). Without the adjustment, stack size is
 302   // incorrect if stack is set to unlimited (ulimit -s unlimited).
 303   // So far, only Solaris has real implementation of initialize_thread().
 304   //
 305   // set up any platform-specific state.
 306   os::initialize_thread(this);
 307 
 308 #if INCLUDE_NMT
 309   // record thread's native stack, stack grows downward
 310   address stack_low_addr = stack_base() - stack_size();
 311   MemTracker::record_thread_stack(stack_low_addr, stack_size());
 312 #endif // INCLUDE_NMT
 313 }
 314 
 315 
 316 Thread::~Thread() {
 317   // Reclaim the objectmonitors from the omFreeList of the moribund thread.
 318   ObjectSynchronizer::omFlush(this);
 319 
 320   EVENT_THREAD_DESTRUCT(this);
 321 
 322   // stack_base can be NULL if the thread is never started or exited before
 323   // record_stack_base_and_size called. Although, we would like to ensure
 324   // that all started threads do call record_stack_base_and_size(), there is
 325   // not proper way to enforce that.
 326 #if INCLUDE_NMT
 327   if (_stack_base != NULL) {
 328     address low_stack_addr = stack_base() - stack_size();
 329     MemTracker::release_thread_stack(low_stack_addr, stack_size());
 330 #ifdef ASSERT
 331     set_stack_base(NULL);
 332 #endif
 333   }
 334 #endif // INCLUDE_NMT
 335 
 336   // deallocate data structures
 337   delete resource_area();
 338   // since the handle marks are using the handle area, we have to deallocated the root
 339   // handle mark before deallocating the thread's handle area,
 340   assert(last_handle_mark() != NULL, "check we have an element");
 341   delete last_handle_mark();
 342   assert(last_handle_mark() == NULL, "check we have reached the end");
 343 
 344   // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
 345   // We NULL out the fields for good hygiene.
 346   ParkEvent::Release(_ParkEvent); _ParkEvent   = NULL;
 347   ParkEvent::Release(_SleepEvent); _SleepEvent  = NULL;
 348   ParkEvent::Release(_MutexEvent); _MutexEvent  = NULL;
 349   ParkEvent::Release(_MuxEvent); _MuxEvent    = NULL;
 350 
 351   delete handle_area();
 352   delete metadata_handles();
 353 
 354   // osthread() can be NULL, if creation of thread failed.
 355   if (osthread() != NULL) os::free_thread(osthread());
 356 
 357   delete _SR_lock;
 358 
 359   // clear thread local storage if the Thread is deleting itself
 360   if (this == Thread::current()) {
 361     ThreadLocalStorage::set_thread(NULL);
 362   } else {
 363     // In the case where we're not the current thread, invalidate all the
 364     // caches in case some code tries to get the current thread or the
 365     // thread that was destroyed, and gets stale information.
 366     ThreadLocalStorage::invalidate_all();
 367   }
 368   CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
 369 }
 370 
 371 // NOTE: dummy function for assertion purpose.
 372 void Thread::run() {
 373   ShouldNotReachHere();
 374 }
 375 
 376 #ifdef ASSERT
 377 // Private method to check for dangling thread pointer
 378 void check_for_dangling_thread_pointer(Thread *thread) {
 379   assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
 380          "possibility of dangling Thread pointer");
 381 }
 382 #endif
 383 
 384 ThreadPriority Thread::get_priority(const Thread* const thread) {
 385   ThreadPriority priority;
 386   // Can return an error!
 387   (void)os::get_priority(thread, priority);
 388   assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
 389   return priority;
 390 }
 391 
 392 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
 393   debug_only(check_for_dangling_thread_pointer(thread);)
 394   // Can return an error!
 395   (void)os::set_priority(thread, priority);
 396 }
 397 
 398 
 399 void Thread::start(Thread* thread) {
 400   // Start is different from resume in that its safety is guaranteed by context or
 401   // being called from a Java method synchronized on the Thread object.
 402   if (!DisableStartThread) {
 403     if (thread->is_Java_thread()) {
 404       // Initialize the thread state to RUNNABLE before starting this thread.
 405       // Can not set it after the thread started because we do not know the
 406       // exact thread state at that time. It could be in MONITOR_WAIT or
 407       // in SLEEPING or some other state.
 408       java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
 409                                           java_lang_Thread::RUNNABLE);
 410     }
 411     os::start_thread(thread);
 412   }
 413 }
 414 
 415 // Enqueue a VM_Operation to do the job for us - sometime later
 416 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
 417   VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
 418   VMThread::execute(vm_stop);
 419 }
 420 
 421 
 422 // Check if an external suspend request has completed (or has been
 423 // cancelled). Returns true if the thread is externally suspended and
 424 // false otherwise.
 425 //
 426 // The bits parameter returns information about the code path through
 427 // the routine. Useful for debugging:
 428 //
 429 // set in is_ext_suspend_completed():
 430 // 0x00000001 - routine was entered
 431 // 0x00000010 - routine return false at end
 432 // 0x00000100 - thread exited (return false)
 433 // 0x00000200 - suspend request cancelled (return false)
 434 // 0x00000400 - thread suspended (return true)
 435 // 0x00001000 - thread is in a suspend equivalent state (return true)
 436 // 0x00002000 - thread is native and walkable (return true)
 437 // 0x00004000 - thread is native_trans and walkable (needed retry)
 438 //
 439 // set in wait_for_ext_suspend_completion():
 440 // 0x00010000 - routine was entered
 441 // 0x00020000 - suspend request cancelled before loop (return false)
 442 // 0x00040000 - thread suspended before loop (return true)
 443 // 0x00080000 - suspend request cancelled in loop (return false)
 444 // 0x00100000 - thread suspended in loop (return true)
 445 // 0x00200000 - suspend not completed during retry loop (return false)
 446 
 447 // Helper class for tracing suspend wait debug bits.
 448 //
 449 // 0x00000100 indicates that the target thread exited before it could
 450 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
 451 // 0x00080000 each indicate a cancelled suspend request so they don't
 452 // count as wait failures either.
 453 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
 454 
 455 class TraceSuspendDebugBits : public StackObj {
 456  private:
 457   JavaThread * jt;
 458   bool         is_wait;
 459   bool         called_by_wait;  // meaningful when !is_wait
 460   uint32_t *   bits;
 461 
 462  public:
 463   TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
 464                         uint32_t *_bits) {
 465     jt             = _jt;
 466     is_wait        = _is_wait;
 467     called_by_wait = _called_by_wait;
 468     bits           = _bits;
 469   }
 470 
 471   ~TraceSuspendDebugBits() {
 472     if (!is_wait) {
 473 #if 1
 474       // By default, don't trace bits for is_ext_suspend_completed() calls.
 475       // That trace is very chatty.
 476       return;
 477 #else
 478       if (!called_by_wait) {
 479         // If tracing for is_ext_suspend_completed() is enabled, then only
 480         // trace calls to it from wait_for_ext_suspend_completion()
 481         return;
 482       }
 483 #endif
 484     }
 485 
 486     if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
 487       if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
 488         MutexLocker ml(Threads_lock);  // needed for get_thread_name()
 489         ResourceMark rm;
 490 
 491         tty->print_cr(
 492                       "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
 493                       jt->get_thread_name(), *bits);
 494 
 495         guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
 496       }
 497     }
 498   }
 499 };
 500 #undef DEBUG_FALSE_BITS
 501 
 502 
 503 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
 504                                           uint32_t *bits) {
 505   TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
 506 
 507   bool did_trans_retry = false;  // only do thread_in_native_trans retry once
 508   bool do_trans_retry;           // flag to force the retry
 509 
 510   *bits |= 0x00000001;
 511 
 512   do {
 513     do_trans_retry = false;
 514 
 515     if (is_exiting()) {
 516       // Thread is in the process of exiting. This is always checked
 517       // first to reduce the risk of dereferencing a freed JavaThread.
 518       *bits |= 0x00000100;
 519       return false;
 520     }
 521 
 522     if (!is_external_suspend()) {
 523       // Suspend request is cancelled. This is always checked before
 524       // is_ext_suspended() to reduce the risk of a rogue resume
 525       // confusing the thread that made the suspend request.
 526       *bits |= 0x00000200;
 527       return false;
 528     }
 529 
 530     if (is_ext_suspended()) {
 531       // thread is suspended
 532       *bits |= 0x00000400;
 533       return true;
 534     }
 535 
 536     // Now that we no longer do hard suspends of threads running
 537     // native code, the target thread can be changing thread state
 538     // while we are in this routine:
 539     //
 540     //   _thread_in_native -> _thread_in_native_trans -> _thread_blocked
 541     //
 542     // We save a copy of the thread state as observed at this moment
 543     // and make our decision about suspend completeness based on the
 544     // copy. This closes the race where the thread state is seen as
 545     // _thread_in_native_trans in the if-thread_blocked check, but is
 546     // seen as _thread_blocked in if-thread_in_native_trans check.
 547     JavaThreadState save_state = thread_state();
 548 
 549     if (save_state == _thread_blocked && is_suspend_equivalent()) {
 550       // If the thread's state is _thread_blocked and this blocking
 551       // condition is known to be equivalent to a suspend, then we can
 552       // consider the thread to be externally suspended. This means that
 553       // the code that sets _thread_blocked has been modified to do
 554       // self-suspension if the blocking condition releases. We also
 555       // used to check for CONDVAR_WAIT here, but that is now covered by
 556       // the _thread_blocked with self-suspension check.
 557       //
 558       // Return true since we wouldn't be here unless there was still an
 559       // external suspend request.
 560       *bits |= 0x00001000;
 561       return true;
 562     } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
 563       // Threads running native code will self-suspend on native==>VM/Java
 564       // transitions. If its stack is walkable (should always be the case
 565       // unless this function is called before the actual java_suspend()
 566       // call), then the wait is done.
 567       *bits |= 0x00002000;
 568       return true;
 569     } else if (!called_by_wait && !did_trans_retry &&
 570                save_state == _thread_in_native_trans &&
 571                frame_anchor()->walkable()) {
 572       // The thread is transitioning from thread_in_native to another
 573       // thread state. check_safepoint_and_suspend_for_native_trans()
 574       // will force the thread to self-suspend. If it hasn't gotten
 575       // there yet we may have caught the thread in-between the native
 576       // code check above and the self-suspend. Lucky us. If we were
 577       // called by wait_for_ext_suspend_completion(), then it
 578       // will be doing the retries so we don't have to.
 579       //
 580       // Since we use the saved thread state in the if-statement above,
 581       // there is a chance that the thread has already transitioned to
 582       // _thread_blocked by the time we get here. In that case, we will
 583       // make a single unnecessary pass through the logic below. This
 584       // doesn't hurt anything since we still do the trans retry.
 585 
 586       *bits |= 0x00004000;
 587 
 588       // Once the thread leaves thread_in_native_trans for another
 589       // thread state, we break out of this retry loop. We shouldn't
 590       // need this flag to prevent us from getting back here, but
 591       // sometimes paranoia is good.
 592       did_trans_retry = true;
 593 
 594       // We wait for the thread to transition to a more usable state.
 595       for (int i = 1; i <= SuspendRetryCount; i++) {
 596         // We used to do an "os::yield_all(i)" call here with the intention
 597         // that yielding would increase on each retry. However, the parameter
 598         // is ignored on Linux which means the yield didn't scale up. Waiting
 599         // on the SR_lock below provides a much more predictable scale up for
 600         // the delay. It also provides a simple/direct point to check for any
 601         // safepoint requests from the VMThread
 602 
 603         // temporarily drops SR_lock while doing wait with safepoint check
 604         // (if we're a JavaThread - the WatcherThread can also call this)
 605         // and increase delay with each retry
 606         SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 607 
 608         // check the actual thread state instead of what we saved above
 609         if (thread_state() != _thread_in_native_trans) {
 610           // the thread has transitioned to another thread state so
 611           // try all the checks (except this one) one more time.
 612           do_trans_retry = true;
 613           break;
 614         }
 615       } // end retry loop
 616 
 617 
 618     }
 619   } while (do_trans_retry);
 620 
 621   *bits |= 0x00000010;
 622   return false;
 623 }
 624 
 625 // Wait for an external suspend request to complete (or be cancelled).
 626 // Returns true if the thread is externally suspended and false otherwise.
 627 //
 628 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
 629                                                  uint32_t *bits) {
 630   TraceSuspendDebugBits tsdb(this, true /* is_wait */,
 631                              false /* !called_by_wait */, bits);
 632 
 633   // local flag copies to minimize SR_lock hold time
 634   bool is_suspended;
 635   bool pending;
 636   uint32_t reset_bits;
 637 
 638   // set a marker so is_ext_suspend_completed() knows we are the caller
 639   *bits |= 0x00010000;
 640 
 641   // We use reset_bits to reinitialize the bits value at the top of
 642   // each retry loop. This allows the caller to make use of any
 643   // unused bits for their own marking purposes.
 644   reset_bits = *bits;
 645 
 646   {
 647     MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
 648     is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 649                                             delay, bits);
 650     pending = is_external_suspend();
 651   }
 652   // must release SR_lock to allow suspension to complete
 653 
 654   if (!pending) {
 655     // A cancelled suspend request is the only false return from
 656     // is_ext_suspend_completed() that keeps us from entering the
 657     // retry loop.
 658     *bits |= 0x00020000;
 659     return false;
 660   }
 661 
 662   if (is_suspended) {
 663     *bits |= 0x00040000;
 664     return true;
 665   }
 666 
 667   for (int i = 1; i <= retries; i++) {
 668     *bits = reset_bits;  // reinit to only track last retry
 669 
 670     // We used to do an "os::yield_all(i)" call here with the intention
 671     // that yielding would increase on each retry. However, the parameter
 672     // is ignored on Linux which means the yield didn't scale up. Waiting
 673     // on the SR_lock below provides a much more predictable scale up for
 674     // the delay. It also provides a simple/direct point to check for any
 675     // safepoint requests from the VMThread
 676 
 677     {
 678       MutexLocker ml(SR_lock());
 679       // wait with safepoint check (if we're a JavaThread - the WatcherThread
 680       // can also call this)  and increase delay with each retry
 681       SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 682 
 683       is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 684                                               delay, bits);
 685 
 686       // It is possible for the external suspend request to be cancelled
 687       // (by a resume) before the actual suspend operation is completed.
 688       // Refresh our local copy to see if we still need to wait.
 689       pending = is_external_suspend();
 690     }
 691 
 692     if (!pending) {
 693       // A cancelled suspend request is the only false return from
 694       // is_ext_suspend_completed() that keeps us from staying in the
 695       // retry loop.
 696       *bits |= 0x00080000;
 697       return false;
 698     }
 699 
 700     if (is_suspended) {
 701       *bits |= 0x00100000;
 702       return true;
 703     }
 704   } // end retry loop
 705 
 706   // thread did not suspend after all our retries
 707   *bits |= 0x00200000;
 708   return false;
 709 }
 710 
 711 #ifndef PRODUCT
 712 void JavaThread::record_jump(address target, address instr, const char* file,
 713                              int line) {
 714 
 715   // This should not need to be atomic as the only way for simultaneous
 716   // updates is via interrupts. Even then this should be rare or non-existent
 717   // and we don't care that much anyway.
 718 
 719   int index = _jmp_ring_index;
 720   _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
 721   _jmp_ring[index]._target = (intptr_t) target;
 722   _jmp_ring[index]._instruction = (intptr_t) instr;
 723   _jmp_ring[index]._file = file;
 724   _jmp_ring[index]._line = line;
 725 }
 726 #endif // PRODUCT
 727 
 728 // Called by flat profiler
 729 // Callers have already called wait_for_ext_suspend_completion
 730 // The assertion for that is currently too complex to put here:
 731 bool JavaThread::profile_last_Java_frame(frame* _fr) {
 732   bool gotframe = false;
 733   // self suspension saves needed state.
 734   if (has_last_Java_frame() && _anchor.walkable()) {
 735     *_fr = pd_last_frame();
 736     gotframe = true;
 737   }
 738   return gotframe;
 739 }
 740 
 741 void Thread::interrupt(Thread* thread) {
 742   debug_only(check_for_dangling_thread_pointer(thread);)
 743   os::interrupt(thread);
 744 }
 745 
 746 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
 747   debug_only(check_for_dangling_thread_pointer(thread);)
 748   // Note:  If clear_interrupted==false, this simply fetches and
 749   // returns the value of the field osthread()->interrupted().
 750   return os::is_interrupted(thread, clear_interrupted);
 751 }
 752 
 753 
 754 // GC Support
 755 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
 756   jint thread_parity = _oops_do_parity;
 757   if (thread_parity != strong_roots_parity) {
 758     jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
 759     if (res == thread_parity) {
 760       return true;
 761     } else {
 762       guarantee(res == strong_roots_parity, "Or else what?");
 763       return false;
 764     }
 765   }
 766   return false;
 767 }
 768 
 769 void Thread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
 770   active_handles()->oops_do(f);
 771   // Do oop for ThreadShadow
 772   f->do_oop((oop*)&_pending_exception);
 773   handle_area()->oops_do(f);
 774 }
 775 
 776 void Thread::nmethods_do(CodeBlobClosure* cf) {
 777   // no nmethods in a generic thread...
 778 }
 779 
 780 void Thread::metadata_handles_do(void f(Metadata*)) {
 781   // Only walk the Handles in Thread.
 782   if (metadata_handles() != NULL) {
 783     for (int i = 0; i< metadata_handles()->length(); i++) {
 784       f(metadata_handles()->at(i));
 785     }
 786   }
 787 }
 788 
 789 void Thread::print_on(outputStream* st) const {
 790   // get_priority assumes osthread initialized
 791   if (osthread() != NULL) {
 792     int os_prio;
 793     if (os::get_native_priority(this, &os_prio) == OS_OK) {
 794       st->print("os_prio=%d ", os_prio);
 795     }
 796     st->print("tid=" INTPTR_FORMAT " ", this);
 797     ext().print_on(st);
 798     osthread()->print_on(st);
 799   }
 800   debug_only(if (WizardMode) print_owned_locks_on(st);)
 801 }
 802 
 803 // Thread::print_on_error() is called by fatal error handler. Don't use
 804 // any lock or allocate memory.
 805 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
 806   if (is_VM_thread())                 st->print("VMThread");
 807   else if (is_Compiler_thread())      st->print("CompilerThread");
 808   else if (is_Java_thread())          st->print("JavaThread");
 809   else if (is_GC_task_thread())       st->print("GCTaskThread");
 810   else if (is_Watcher_thread())       st->print("WatcherThread");
 811   else if (is_ConcurrentGC_thread())  st->print("ConcurrentGCThread");
 812   else                                st->print("Thread");
 813 
 814   st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
 815             _stack_base - _stack_size, _stack_base);
 816 
 817   if (osthread()) {
 818     st->print(" [id=%d]", osthread()->thread_id());
 819   }
 820 }
 821 
 822 #ifdef ASSERT
 823 void Thread::print_owned_locks_on(outputStream* st) const {
 824   Monitor *cur = _owned_locks;
 825   if (cur == NULL) {
 826     st->print(" (no locks) ");
 827   } else {
 828     st->print_cr(" Locks owned:");
 829     while (cur) {
 830       cur->print_on(st);
 831       cur = cur->next();
 832     }
 833   }
 834 }
 835 
 836 static int ref_use_count  = 0;
 837 
 838 bool Thread::owns_locks_but_compiled_lock() const {
 839   for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 840     if (cur != Compile_lock) return true;
 841   }
 842   return false;
 843 }
 844 
 845 
 846 #endif
 847 
 848 #ifndef PRODUCT
 849 
 850 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
 851 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
 852 // no threads which allow_vm_block's are held
 853 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
 854   // Check if current thread is allowed to block at a safepoint
 855   if (!(_allow_safepoint_count == 0)) {
 856     fatal("Possible safepoint reached by thread that does not allow it");
 857   }
 858   if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
 859     fatal("LEAF method calling lock?");
 860   }
 861 
 862 #ifdef ASSERT
 863   if (potential_vm_operation && is_Java_thread()
 864       && !Universe::is_bootstrapping()) {
 865     // Make sure we do not hold any locks that the VM thread also uses.
 866     // This could potentially lead to deadlocks
 867     for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 868       // Threads_lock is special, since the safepoint synchronization will not start before this is
 869       // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
 870       // since it is used to transfer control between JavaThreads and the VMThread
 871       // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
 872       if ((cur->allow_vm_block() &&
 873            cur != Threads_lock &&
 874            cur != Compile_lock &&               // Temporary: should not be necessary when we get separate compilation
 875            cur != VMOperationRequest_lock &&
 876            cur != VMOperationQueue_lock) ||
 877            cur->rank() == Mutex::special) {
 878         fatal(err_msg("Thread holding lock at safepoint that vm can block on: %s", cur->name()));
 879       }
 880     }
 881   }
 882 
 883   if (GCALotAtAllSafepoints) {
 884     // We could enter a safepoint here and thus have a gc
 885     InterfaceSupport::check_gc_alot();
 886   }
 887 #endif
 888 }
 889 #endif
 890 
 891 bool Thread::is_in_stack(address adr) const {
 892   assert(Thread::current() == this, "is_in_stack can only be called from current thread");
 893   address end = os::current_stack_pointer();
 894   // Allow non Java threads to call this without stack_base
 895   if (_stack_base == NULL) return true;
 896   if (stack_base() >= adr && adr >= end) return true;
 897 
 898   return false;
 899 }
 900 
 901 
 902 bool Thread::is_in_usable_stack(address adr) const {
 903   size_t stack_guard_size = os::uses_stack_guard_pages() ? (StackYellowPages + StackRedPages) * os::vm_page_size() : 0;
 904   size_t usable_stack_size = _stack_size - stack_guard_size;
 905 
 906   return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
 907 }
 908 
 909 
 910 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
 911 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
 912 // used for compilation in the future. If that change is made, the need for these methods
 913 // should be revisited, and they should be removed if possible.
 914 
 915 bool Thread::is_lock_owned(address adr) const {
 916   return on_local_stack(adr);
 917 }
 918 
 919 bool Thread::set_as_starting_thread() {
 920   // NOTE: this must be called inside the main thread.
 921   return os::create_main_thread((JavaThread*)this);
 922 }
 923 
 924 static void initialize_class(Symbol* class_name, TRAPS) {
 925   Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
 926   InstanceKlass::cast(klass)->initialize(CHECK);
 927 }
 928 
 929 
 930 // Creates the initial ThreadGroup
 931 static Handle create_initial_thread_group(TRAPS) {
 932   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
 933   instanceKlassHandle klass (THREAD, k);
 934 
 935   Handle system_instance = klass->allocate_instance_handle(CHECK_NH);
 936   {
 937     JavaValue result(T_VOID);
 938     JavaCalls::call_special(&result,
 939                             system_instance,
 940                             klass,
 941                             vmSymbols::object_initializer_name(),
 942                             vmSymbols::void_method_signature(),
 943                             CHECK_NH);
 944   }
 945   Universe::set_system_thread_group(system_instance());
 946 
 947   Handle main_instance = klass->allocate_instance_handle(CHECK_NH);
 948   {
 949     JavaValue result(T_VOID);
 950     Handle string = java_lang_String::create_from_str("main", CHECK_NH);
 951     JavaCalls::call_special(&result,
 952                             main_instance,
 953                             klass,
 954                             vmSymbols::object_initializer_name(),
 955                             vmSymbols::threadgroup_string_void_signature(),
 956                             system_instance,
 957                             string,
 958                             CHECK_NH);
 959   }
 960   return main_instance;
 961 }
 962 
 963 // Creates the initial Thread
 964 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
 965                                  TRAPS) {
 966   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
 967   instanceKlassHandle klass (THREAD, k);
 968   instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);
 969 
 970   java_lang_Thread::set_thread(thread_oop(), thread);
 971   java_lang_Thread::set_priority(thread_oop(), NormPriority);
 972   thread->set_threadObj(thread_oop());
 973 
 974   Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
 975 
 976   JavaValue result(T_VOID);
 977   JavaCalls::call_special(&result, thread_oop,
 978                           klass,
 979                           vmSymbols::object_initializer_name(),
 980                           vmSymbols::threadgroup_string_void_signature(),
 981                           thread_group,
 982                           string,
 983                           CHECK_NULL);
 984   return thread_oop();
 985 }
 986 
 987 static void call_initializeSystemClass(TRAPS) {
 988   Klass* k =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
 989   instanceKlassHandle klass (THREAD, k);
 990 
 991   JavaValue result(T_VOID);
 992   JavaCalls::call_static(&result, klass, vmSymbols::initializeSystemClass_name(),
 993                          vmSymbols::void_method_signature(), CHECK);
 994 }
 995 
 996 char java_runtime_name[128] = "";
 997 char java_runtime_version[128] = "";
 998 
 999 // extract the JRE name from sun.misc.Version.java_runtime_name
1000 static const char* get_java_runtime_name(TRAPS) {
1001   Klass* k = SystemDictionary::find(vmSymbols::sun_misc_Version(),
1002                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1003   fieldDescriptor fd;
1004   bool found = k != NULL &&
1005                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1006                                                         vmSymbols::string_signature(), &fd);
1007   if (found) {
1008     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1009     if (name_oop == NULL) {
1010       return NULL;
1011     }
1012     const char* name = java_lang_String::as_utf8_string(name_oop,
1013                                                         java_runtime_name,
1014                                                         sizeof(java_runtime_name));
1015     return name;
1016   } else {
1017     return NULL;
1018   }
1019 }
1020 
1021 // extract the JRE version from sun.misc.Version.java_runtime_version
1022 static const char* get_java_runtime_version(TRAPS) {
1023   Klass* k = SystemDictionary::find(vmSymbols::sun_misc_Version(),
1024                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1025   fieldDescriptor fd;
1026   bool found = k != NULL &&
1027                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1028                                                         vmSymbols::string_signature(), &fd);
1029   if (found) {
1030     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1031     if (name_oop == NULL) {
1032       return NULL;
1033     }
1034     const char* name = java_lang_String::as_utf8_string(name_oop,
1035                                                         java_runtime_version,
1036                                                         sizeof(java_runtime_version));
1037     return name;
1038   } else {
1039     return NULL;
1040   }
1041 }
1042 
1043 // General purpose hook into Java code, run once when the VM is initialized.
1044 // The Java library method itself may be changed independently from the VM.
1045 static void call_postVMInitHook(TRAPS) {
1046   Klass* k = SystemDictionary::resolve_or_null(vmSymbols::sun_misc_PostVMInitHook(), THREAD);
1047   instanceKlassHandle klass (THREAD, k);
1048   if (klass.not_null()) {
1049     JavaValue result(T_VOID);
1050     JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1051                            vmSymbols::void_method_signature(),
1052                            CHECK);
1053   }
1054 }
1055 
1056 static void reset_vm_info_property(TRAPS) {
1057   // the vm info string
1058   ResourceMark rm(THREAD);
1059   const char *vm_info = VM_Version::vm_info_string();
1060 
1061   // java.lang.System class
1062   Klass* k =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1063   instanceKlassHandle klass (THREAD, k);
1064 
1065   // setProperty arguments
1066   Handle key_str    = java_lang_String::create_from_str("java.vm.info", CHECK);
1067   Handle value_str  = java_lang_String::create_from_str(vm_info, CHECK);
1068 
1069   // return value
1070   JavaValue r(T_OBJECT);
1071 
1072   // public static String setProperty(String key, String value);
1073   JavaCalls::call_static(&r,
1074                          klass,
1075                          vmSymbols::setProperty_name(),
1076                          vmSymbols::string_string_string_signature(),
1077                          key_str,
1078                          value_str,
1079                          CHECK);
1080 }
1081 
1082 
1083 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1084                                     bool daemon, TRAPS) {
1085   assert(thread_group.not_null(), "thread group should be specified");
1086   assert(threadObj() == NULL, "should only create Java thread object once");
1087 
1088   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1089   instanceKlassHandle klass (THREAD, k);
1090   instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
1091 
1092   java_lang_Thread::set_thread(thread_oop(), this);
1093   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1094   set_threadObj(thread_oop());
1095 
1096   JavaValue result(T_VOID);
1097   if (thread_name != NULL) {
1098     Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1099     // Thread gets assigned specified name and null target
1100     JavaCalls::call_special(&result,
1101                             thread_oop,
1102                             klass,
1103                             vmSymbols::object_initializer_name(),
1104                             vmSymbols::threadgroup_string_void_signature(),
1105                             thread_group, // Argument 1
1106                             name,         // Argument 2
1107                             THREAD);
1108   } else {
1109     // Thread gets assigned name "Thread-nnn" and null target
1110     // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1111     JavaCalls::call_special(&result,
1112                             thread_oop,
1113                             klass,
1114                             vmSymbols::object_initializer_name(),
1115                             vmSymbols::threadgroup_runnable_void_signature(),
1116                             thread_group, // Argument 1
1117                             Handle(),     // Argument 2
1118                             THREAD);
1119   }
1120 
1121 
1122   if (daemon) {
1123     java_lang_Thread::set_daemon(thread_oop());
1124   }
1125 
1126   if (HAS_PENDING_EXCEPTION) {
1127     return;
1128   }
1129 
1130   KlassHandle group(THREAD, SystemDictionary::ThreadGroup_klass());
1131   Handle threadObj(THREAD, this->threadObj());
1132 
1133   JavaCalls::call_special(&result,
1134                           thread_group,
1135                           group,
1136                           vmSymbols::add_method_name(),
1137                           vmSymbols::thread_void_signature(),
1138                           threadObj,          // Arg 1
1139                           THREAD);
1140 }
1141 
1142 // NamedThread --  non-JavaThread subclasses with multiple
1143 // uniquely named instances should derive from this.
1144 NamedThread::NamedThread() : Thread() {
1145   _name = NULL;
1146   _processed_thread = NULL;
1147 }
1148 
1149 NamedThread::~NamedThread() {
1150   if (_name != NULL) {
1151     FREE_C_HEAP_ARRAY(char, _name);
1152     _name = NULL;
1153   }
1154 }
1155 
1156 void NamedThread::set_name(const char* format, ...) {
1157   guarantee(_name == NULL, "Only get to set name once.");
1158   _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1159   guarantee(_name != NULL, "alloc failure");
1160   va_list ap;
1161   va_start(ap, format);
1162   jio_vsnprintf(_name, max_name_len, format, ap);
1163   va_end(ap);
1164 }
1165 
1166 void NamedThread::initialize_named_thread() {
1167   set_native_thread_name(name());
1168 }
1169 
1170 void NamedThread::print_on(outputStream* st) const {
1171   st->print("\"%s\" ", name());
1172   Thread::print_on(st);
1173   st->cr();
1174 }
1175 
1176 
1177 // ======= WatcherThread ========
1178 
1179 // The watcher thread exists to simulate timer interrupts.  It should
1180 // be replaced by an abstraction over whatever native support for
1181 // timer interrupts exists on the platform.
1182 
1183 WatcherThread* WatcherThread::_watcher_thread   = NULL;
1184 bool WatcherThread::_startable = false;
1185 volatile bool  WatcherThread::_should_terminate = false;
1186 
1187 WatcherThread::WatcherThread() : Thread(), _crash_protection(NULL) {
1188   assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1189   if (os::create_thread(this, os::watcher_thread)) {
1190     _watcher_thread = this;
1191 
1192     // Set the watcher thread to the highest OS priority which should not be
1193     // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1194     // is created. The only normal thread using this priority is the reference
1195     // handler thread, which runs for very short intervals only.
1196     // If the VMThread's priority is not lower than the WatcherThread profiling
1197     // will be inaccurate.
1198     os::set_priority(this, MaxPriority);
1199     if (!DisableStartThread) {
1200       os::start_thread(this);
1201     }
1202   }
1203 }
1204 
1205 int WatcherThread::sleep() const {
1206   // The WatcherThread does not participate in the safepoint protocol
1207   // for the PeriodicTask_lock because it is not a JavaThread.
1208   MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1209 
1210   if (_should_terminate) {
1211     // check for termination before we do any housekeeping or wait
1212     return 0;  // we did not sleep.
1213   }
1214 
1215   // remaining will be zero if there are no tasks,
1216   // causing the WatcherThread to sleep until a task is
1217   // enrolled
1218   int remaining = PeriodicTask::time_to_wait();
1219   int time_slept = 0;
1220 
1221   // we expect this to timeout - we only ever get unparked when
1222   // we should terminate or when a new task has been enrolled
1223   OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1224 
1225   jlong time_before_loop = os::javaTimeNanos();
1226 
1227   while (true) {
1228     bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1229                                             remaining);
1230     jlong now = os::javaTimeNanos();
1231 
1232     if (remaining == 0) {
1233       // if we didn't have any tasks we could have waited for a long time
1234       // consider the time_slept zero and reset time_before_loop
1235       time_slept = 0;
1236       time_before_loop = now;
1237     } else {
1238       // need to recalculate since we might have new tasks in _tasks
1239       time_slept = (int) ((now - time_before_loop) / 1000000);
1240     }
1241 
1242     // Change to task list or spurious wakeup of some kind
1243     if (timedout || _should_terminate) {
1244       break;
1245     }
1246 
1247     remaining = PeriodicTask::time_to_wait();
1248     if (remaining == 0) {
1249       // Last task was just disenrolled so loop around and wait until
1250       // another task gets enrolled
1251       continue;
1252     }
1253 
1254     remaining -= time_slept;
1255     if (remaining <= 0) {
1256       break;
1257     }
1258   }
1259 
1260   return time_slept;
1261 }
1262 
1263 void WatcherThread::run() {
1264   assert(this == watcher_thread(), "just checking");
1265 
1266   this->record_stack_base_and_size();
1267   this->initialize_thread_local_storage();
1268   this->set_native_thread_name(this->name());
1269   this->set_active_handles(JNIHandleBlock::allocate_block());
1270   while (true) {
1271     assert(watcher_thread() == Thread::current(), "thread consistency check");
1272     assert(watcher_thread() == this, "thread consistency check");
1273 
1274     // Calculate how long it'll be until the next PeriodicTask work
1275     // should be done, and sleep that amount of time.
1276     int time_waited = sleep();
1277 
1278     if (is_error_reported()) {
1279       // A fatal error has happened, the error handler(VMError::report_and_die)
1280       // should abort JVM after creating an error log file. However in some
1281       // rare cases, the error handler itself might deadlock. Here we try to
1282       // kill JVM if the fatal error handler fails to abort in 2 minutes.
1283       //
1284       // This code is in WatcherThread because WatcherThread wakes up
1285       // periodically so the fatal error handler doesn't need to do anything;
1286       // also because the WatcherThread is less likely to crash than other
1287       // threads.
1288 
1289       for (;;) {
1290         if (!ShowMessageBoxOnError
1291             && (OnError == NULL || OnError[0] == '\0')
1292             && Arguments::abort_hook() == NULL) {
1293           os::sleep(this, 2 * 60 * 1000, false);
1294           fdStream err(defaultStream::output_fd());
1295           err.print_raw_cr("# [ timer expired, abort... ]");
1296           // skip atexit/vm_exit/vm_abort hooks
1297           os::die();
1298         }
1299 
1300         // Wake up 5 seconds later, the fatal handler may reset OnError or
1301         // ShowMessageBoxOnError when it is ready to abort.
1302         os::sleep(this, 5 * 1000, false);
1303       }
1304     }
1305 
1306     if (_should_terminate) {
1307       // check for termination before posting the next tick
1308       break;
1309     }
1310 
1311     PeriodicTask::real_time_tick(time_waited);
1312   }
1313 
1314   // Signal that it is terminated
1315   {
1316     MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1317     _watcher_thread = NULL;
1318     Terminator_lock->notify();
1319   }
1320 
1321   // Thread destructor usually does this..
1322   ThreadLocalStorage::set_thread(NULL);
1323 }
1324 
1325 void WatcherThread::start() {
1326   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1327 
1328   if (watcher_thread() == NULL && _startable) {
1329     _should_terminate = false;
1330     // Create the single instance of WatcherThread
1331     new WatcherThread();
1332   }
1333 }
1334 
1335 void WatcherThread::make_startable() {
1336   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1337   _startable = true;
1338 }
1339 
1340 void WatcherThread::stop() {
1341   {
1342     // Follow normal safepoint aware lock enter protocol since the
1343     // WatcherThread is stopped by another JavaThread.
1344     MutexLocker ml(PeriodicTask_lock);
1345     _should_terminate = true;
1346 
1347     WatcherThread* watcher = watcher_thread();
1348     if (watcher != NULL) {
1349       // unpark the WatcherThread so it can see that it should terminate
1350       watcher->unpark();
1351     }
1352   }
1353 
1354   MutexLocker mu(Terminator_lock);
1355 
1356   while (watcher_thread() != NULL) {
1357     // This wait should make safepoint checks, wait without a timeout,
1358     // and wait as a suspend-equivalent condition.
1359     //
1360     // Note: If the FlatProfiler is running, then this thread is waiting
1361     // for the WatcherThread to terminate and the WatcherThread, via the
1362     // FlatProfiler task, is waiting for the external suspend request on
1363     // this thread to complete. wait_for_ext_suspend_completion() will
1364     // eventually timeout, but that takes time. Making this wait a
1365     // suspend-equivalent condition solves that timeout problem.
1366     //
1367     Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1368                           Mutex::_as_suspend_equivalent_flag);
1369   }
1370 }
1371 
1372 void WatcherThread::unpark() {
1373   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1374   PeriodicTask_lock->notify();
1375 }
1376 
1377 void WatcherThread::print_on(outputStream* st) const {
1378   st->print("\"%s\" ", name());
1379   Thread::print_on(st);
1380   st->cr();
1381 }
1382 
1383 // ======= JavaThread ========
1384 
1385 // A JavaThread is a normal Java thread
1386 
1387 void JavaThread::initialize() {
1388   // Initialize fields
1389 
1390   // Set the claimed par_id to UINT_MAX (ie not claiming any par_ids)
1391   set_claimed_par_id(UINT_MAX);
1392 
1393   set_saved_exception_pc(NULL);
1394   set_threadObj(NULL);
1395   _anchor.clear();
1396   set_entry_point(NULL);
1397   set_jni_functions(jni_functions());
1398   set_callee_target(NULL);
1399   set_vm_result(NULL);
1400   set_vm_result_2(NULL);
1401   set_vframe_array_head(NULL);
1402   set_vframe_array_last(NULL);
1403   set_deferred_locals(NULL);
1404   set_deopt_mark(NULL);
1405   set_deopt_nmethod(NULL);
1406   clear_must_deopt_id();
1407   set_monitor_chunks(NULL);
1408   set_next(NULL);
1409   set_thread_state(_thread_new);
1410   _terminated = _not_terminated;
1411   _privileged_stack_top = NULL;
1412   _array_for_gc = NULL;
1413   _suspend_equivalent = false;
1414   _in_deopt_handler = 0;
1415   _doing_unsafe_access = false;
1416   _stack_guard_state = stack_guard_unused;
1417   (void)const_cast<oop&>(_exception_oop = oop(NULL));
1418   _exception_pc  = 0;
1419   _exception_handler_pc = 0;
1420   _is_method_handle_return = 0;
1421   _jvmti_thread_state= NULL;
1422   _should_post_on_exceptions_flag = JNI_FALSE;
1423   _jvmti_get_loaded_classes_closure = NULL;
1424   _interp_only_mode    = 0;
1425   _special_runtime_exit_condition = _no_async_condition;
1426   _pending_async_exception = NULL;
1427   _thread_stat = NULL;
1428   _thread_stat = new ThreadStatistics();
1429   _blocked_on_compilation = false;
1430   _jni_active_critical = 0;
1431   _pending_jni_exception_check_fn = NULL;
1432   _do_not_unlock_if_synchronized = false;
1433   _cached_monitor_info = NULL;
1434   _parker = Parker::Allocate(this);
1435 
1436 #ifndef PRODUCT
1437   _jmp_ring_index = 0;
1438   for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1439     record_jump(NULL, NULL, NULL, 0);
1440   }
1441 #endif // PRODUCT
1442 
1443   set_thread_profiler(NULL);
1444   if (FlatProfiler::is_active()) {
1445     // This is where we would decide to either give each thread it's own profiler
1446     // or use one global one from FlatProfiler,
1447     // or up to some count of the number of profiled threads, etc.
1448     ThreadProfiler* pp = new ThreadProfiler();
1449     pp->engage();
1450     set_thread_profiler(pp);
1451   }
1452 
1453   // Setup safepoint state info for this thread
1454   ThreadSafepointState::create(this);
1455 
1456   debug_only(_java_call_counter = 0);
1457 
1458   // JVMTI PopFrame support
1459   _popframe_condition = popframe_inactive;
1460   _popframe_preserved_args = NULL;
1461   _popframe_preserved_args_size = 0;
1462   _frames_to_pop_failed_realloc = 0;
1463 
1464   pd_initialize();
1465 }
1466 
1467 #if INCLUDE_ALL_GCS
1468 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1469 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1470 #endif // INCLUDE_ALL_GCS
1471 
1472 JavaThread::JavaThread(bool is_attaching_via_jni) :
1473                        Thread()
1474 #if INCLUDE_ALL_GCS
1475                        , _satb_mark_queue(&_satb_mark_queue_set),
1476                        _dirty_card_queue(&_dirty_card_queue_set)
1477 #endif // INCLUDE_ALL_GCS
1478 {
1479   initialize();
1480   if (is_attaching_via_jni) {
1481     _jni_attach_state = _attaching_via_jni;
1482   } else {
1483     _jni_attach_state = _not_attaching_via_jni;
1484   }
1485   assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1486 }
1487 
1488 bool JavaThread::reguard_stack(address cur_sp) {
1489   if (_stack_guard_state != stack_guard_yellow_disabled) {
1490     return true; // Stack already guarded or guard pages not needed.
1491   }
1492 
1493   if (register_stack_overflow()) {
1494     // For those architectures which have separate register and
1495     // memory stacks, we must check the register stack to see if
1496     // it has overflowed.
1497     return false;
1498   }
1499 
1500   // Java code never executes within the yellow zone: the latter is only
1501   // there to provoke an exception during stack banging.  If java code
1502   // is executing there, either StackShadowPages should be larger, or
1503   // some exception code in c1, c2 or the interpreter isn't unwinding
1504   // when it should.
1505   guarantee(cur_sp > stack_yellow_zone_base(), "not enough space to reguard - increase StackShadowPages");
1506 
1507   enable_stack_yellow_zone();
1508   return true;
1509 }
1510 
1511 bool JavaThread::reguard_stack(void) {
1512   return reguard_stack(os::current_stack_pointer());
1513 }
1514 
1515 
1516 void JavaThread::block_if_vm_exited() {
1517   if (_terminated == _vm_exited) {
1518     // _vm_exited is set at safepoint, and Threads_lock is never released
1519     // we will block here forever
1520     Threads_lock->lock_without_safepoint_check();
1521     ShouldNotReachHere();
1522   }
1523 }
1524 
1525 
1526 // Remove this ifdef when C1 is ported to the compiler interface.
1527 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1528 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1529 
1530 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1531                        Thread()
1532 #if INCLUDE_ALL_GCS
1533                        , _satb_mark_queue(&_satb_mark_queue_set),
1534                        _dirty_card_queue(&_dirty_card_queue_set)
1535 #endif // INCLUDE_ALL_GCS
1536 {
1537   initialize();
1538   _jni_attach_state = _not_attaching_via_jni;
1539   set_entry_point(entry_point);
1540   // Create the native thread itself.
1541   // %note runtime_23
1542   os::ThreadType thr_type = os::java_thread;
1543   thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1544                                                      os::java_thread;
1545   os::create_thread(this, thr_type, stack_sz);
1546   // The _osthread may be NULL here because we ran out of memory (too many threads active).
1547   // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1548   // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1549   // the exception consists of creating the exception object & initializing it, initialization
1550   // will leave the VM via a JavaCall and then all locks must be unlocked).
1551   //
1552   // The thread is still suspended when we reach here. Thread must be explicit started
1553   // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1554   // by calling Threads:add. The reason why this is not done here, is because the thread
1555   // object must be fully initialized (take a look at JVM_Start)
1556 }
1557 
1558 JavaThread::~JavaThread() {
1559 
1560   // JSR166 -- return the parker to the free list
1561   Parker::Release(_parker);
1562   _parker = NULL;
1563 
1564   // Free any remaining  previous UnrollBlock
1565   vframeArray* old_array = vframe_array_last();
1566 
1567   if (old_array != NULL) {
1568     Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1569     old_array->set_unroll_block(NULL);
1570     delete old_info;
1571     delete old_array;
1572   }
1573 
1574   GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1575   if (deferred != NULL) {
1576     // This can only happen if thread is destroyed before deoptimization occurs.
1577     assert(deferred->length() != 0, "empty array!");
1578     do {
1579       jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1580       deferred->remove_at(0);
1581       // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1582       delete dlv;
1583     } while (deferred->length() != 0);
1584     delete deferred;
1585   }
1586 
1587   // All Java related clean up happens in exit
1588   ThreadSafepointState::destroy(this);
1589   if (_thread_profiler != NULL) delete _thread_profiler;
1590   if (_thread_stat != NULL) delete _thread_stat;
1591 }
1592 
1593 
1594 // The first routine called by a new Java thread
1595 void JavaThread::run() {
1596   // initialize thread-local alloc buffer related fields
1597   this->initialize_tlab();
1598 
1599   // used to test validity of stack trace backs
1600   this->record_base_of_stack_pointer();
1601 
1602   // Record real stack base and size.
1603   this->record_stack_base_and_size();
1604 
1605   // Initialize thread local storage; set before calling MutexLocker
1606   this->initialize_thread_local_storage();
1607 
1608   this->create_stack_guard_pages();
1609 
1610   this->cache_global_variables();
1611 
1612   // Thread is now sufficient initialized to be handled by the safepoint code as being
1613   // in the VM. Change thread state from _thread_new to _thread_in_vm
1614   ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1615 
1616   assert(JavaThread::current() == this, "sanity check");
1617   assert(!Thread::current()->owns_locks(), "sanity check");
1618 
1619   DTRACE_THREAD_PROBE(start, this);
1620 
1621   // This operation might block. We call that after all safepoint checks for a new thread has
1622   // been completed.
1623   this->set_active_handles(JNIHandleBlock::allocate_block());
1624 
1625   if (JvmtiExport::should_post_thread_life()) {
1626     JvmtiExport::post_thread_start(this);
1627   }
1628 
1629   EventThreadStart event;
1630   if (event.should_commit()) {
1631     event.set_javalangthread(java_lang_Thread::thread_id(this->threadObj()));
1632     event.commit();
1633   }
1634 
1635   // We call another function to do the rest so we are sure that the stack addresses used
1636   // from there will be lower than the stack base just computed
1637   thread_main_inner();
1638 
1639   // Note, thread is no longer valid at this point!
1640 }
1641 
1642 
1643 void JavaThread::thread_main_inner() {
1644   assert(JavaThread::current() == this, "sanity check");
1645   assert(this->threadObj() != NULL, "just checking");
1646 
1647   // Execute thread entry point unless this thread has a pending exception
1648   // or has been stopped before starting.
1649   // Note: Due to JVM_StopThread we can have pending exceptions already!
1650   if (!this->has_pending_exception() &&
1651       !java_lang_Thread::is_stillborn(this->threadObj())) {
1652     {
1653       ResourceMark rm(this);
1654       this->set_native_thread_name(this->get_thread_name());
1655     }
1656     HandleMark hm(this);
1657     this->entry_point()(this, this);
1658   }
1659 
1660   DTRACE_THREAD_PROBE(stop, this);
1661 
1662   this->exit(false);
1663   delete this;
1664 }
1665 
1666 
1667 static void ensure_join(JavaThread* thread) {
1668   // We do not need to grap the Threads_lock, since we are operating on ourself.
1669   Handle threadObj(thread, thread->threadObj());
1670   assert(threadObj.not_null(), "java thread object must exist");
1671   ObjectLocker lock(threadObj, thread);
1672   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1673   thread->clear_pending_exception();
1674   // Thread is exiting. So set thread_status field in  java.lang.Thread class to TERMINATED.
1675   java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1676   // Clear the native thread instance - this makes isAlive return false and allows the join()
1677   // to complete once we've done the notify_all below
1678   java_lang_Thread::set_thread(threadObj(), NULL);
1679   lock.notify_all(thread);
1680   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1681   thread->clear_pending_exception();
1682 }
1683 
1684 
1685 // For any new cleanup additions, please check to see if they need to be applied to
1686 // cleanup_failed_attach_current_thread as well.
1687 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1688   assert(this == JavaThread::current(), "thread consistency check");
1689 
1690   HandleMark hm(this);
1691   Handle uncaught_exception(this, this->pending_exception());
1692   this->clear_pending_exception();
1693   Handle threadObj(this, this->threadObj());
1694   assert(threadObj.not_null(), "Java thread object should be created");
1695 
1696   if (get_thread_profiler() != NULL) {
1697     get_thread_profiler()->disengage();
1698     ResourceMark rm;
1699     get_thread_profiler()->print(get_thread_name());
1700   }
1701 
1702 
1703   // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1704   {
1705     EXCEPTION_MARK;
1706 
1707     CLEAR_PENDING_EXCEPTION;
1708   }
1709   if (!destroy_vm) {
1710     if (uncaught_exception.not_null()) {
1711       EXCEPTION_MARK;
1712       // Call method Thread.dispatchUncaughtException().
1713       KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1714       JavaValue result(T_VOID);
1715       JavaCalls::call_virtual(&result,
1716                               threadObj, thread_klass,
1717                               vmSymbols::dispatchUncaughtException_name(),
1718                               vmSymbols::throwable_void_signature(),
1719                               uncaught_exception,
1720                               THREAD);
1721       if (HAS_PENDING_EXCEPTION) {
1722         ResourceMark rm(this);
1723         jio_fprintf(defaultStream::error_stream(),
1724                     "\nException: %s thrown from the UncaughtExceptionHandler"
1725                     " in thread \"%s\"\n",
1726                     pending_exception()->klass()->external_name(),
1727                     get_thread_name());
1728         CLEAR_PENDING_EXCEPTION;
1729       }
1730     }
1731 
1732     // Called before the java thread exit since we want to read info
1733     // from java_lang_Thread object
1734     EventThreadEnd event;
1735     if (event.should_commit()) {
1736       event.set_javalangthread(java_lang_Thread::thread_id(this->threadObj()));
1737       event.commit();
1738     }
1739 
1740     // Call after last event on thread
1741     EVENT_THREAD_EXIT(this);
1742 
1743     // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1744     // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1745     // is deprecated anyhow.
1746     if (!is_Compiler_thread()) {
1747       int count = 3;
1748       while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1749         EXCEPTION_MARK;
1750         JavaValue result(T_VOID);
1751         KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1752         JavaCalls::call_virtual(&result,
1753                                 threadObj, thread_klass,
1754                                 vmSymbols::exit_method_name(),
1755                                 vmSymbols::void_method_signature(),
1756                                 THREAD);
1757         CLEAR_PENDING_EXCEPTION;
1758       }
1759     }
1760     // notify JVMTI
1761     if (JvmtiExport::should_post_thread_life()) {
1762       JvmtiExport::post_thread_end(this);
1763     }
1764 
1765     // We have notified the agents that we are exiting, before we go on,
1766     // we must check for a pending external suspend request and honor it
1767     // in order to not surprise the thread that made the suspend request.
1768     while (true) {
1769       {
1770         MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1771         if (!is_external_suspend()) {
1772           set_terminated(_thread_exiting);
1773           ThreadService::current_thread_exiting(this);
1774           break;
1775         }
1776         // Implied else:
1777         // Things get a little tricky here. We have a pending external
1778         // suspend request, but we are holding the SR_lock so we
1779         // can't just self-suspend. So we temporarily drop the lock
1780         // and then self-suspend.
1781       }
1782 
1783       ThreadBlockInVM tbivm(this);
1784       java_suspend_self();
1785 
1786       // We're done with this suspend request, but we have to loop around
1787       // and check again. Eventually we will get SR_lock without a pending
1788       // external suspend request and will be able to mark ourselves as
1789       // exiting.
1790     }
1791     // no more external suspends are allowed at this point
1792   } else {
1793     // before_exit() has already posted JVMTI THREAD_END events
1794   }
1795 
1796   // Notify waiters on thread object. This has to be done after exit() is called
1797   // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1798   // group should have the destroyed bit set before waiters are notified).
1799   ensure_join(this);
1800   assert(!this->has_pending_exception(), "ensure_join should have cleared");
1801 
1802   // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1803   // held by this thread must be released.  A detach operation must only
1804   // get here if there are no Java frames on the stack.  Therefore, any
1805   // owned monitors at this point MUST be JNI-acquired monitors which are
1806   // pre-inflated and in the monitor cache.
1807   //
1808   // ensure_join() ignores IllegalThreadStateExceptions, and so does this.
1809   if (exit_type == jni_detach && JNIDetachReleasesMonitors) {
1810     assert(!this->has_last_Java_frame(), "detaching with Java frames?");
1811     ObjectSynchronizer::release_monitors_owned_by_thread(this);
1812     assert(!this->has_pending_exception(), "release_monitors should have cleared");
1813   }
1814 
1815   // These things needs to be done while we are still a Java Thread. Make sure that thread
1816   // is in a consistent state, in case GC happens
1817   assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1818 
1819   if (active_handles() != NULL) {
1820     JNIHandleBlock* block = active_handles();
1821     set_active_handles(NULL);
1822     JNIHandleBlock::release_block(block);
1823   }
1824 
1825   if (free_handle_block() != NULL) {
1826     JNIHandleBlock* block = free_handle_block();
1827     set_free_handle_block(NULL);
1828     JNIHandleBlock::release_block(block);
1829   }
1830 
1831   // These have to be removed while this is still a valid thread.
1832   remove_stack_guard_pages();
1833 
1834   if (UseTLAB) {
1835     tlab().make_parsable(true);  // retire TLAB
1836   }
1837 
1838   if (JvmtiEnv::environments_might_exist()) {
1839     JvmtiExport::cleanup_thread(this);
1840   }
1841 
1842   // We must flush any deferred card marks before removing a thread from
1843   // the list of active threads.
1844   Universe::heap()->flush_deferred_store_barrier(this);
1845   assert(deferred_card_mark().is_empty(), "Should have been flushed");
1846 
1847 #if INCLUDE_ALL_GCS
1848   // We must flush the G1-related buffers before removing a thread
1849   // from the list of active threads. We must do this after any deferred
1850   // card marks have been flushed (above) so that any entries that are
1851   // added to the thread's dirty card queue as a result are not lost.
1852   if (UseG1GC) {
1853     flush_barrier_queues();
1854   }
1855 #endif // INCLUDE_ALL_GCS
1856 
1857   // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1858   Threads::remove(this);
1859 }
1860 
1861 #if INCLUDE_ALL_GCS
1862 // Flush G1-related queues.
1863 void JavaThread::flush_barrier_queues() {
1864   satb_mark_queue().flush();
1865   dirty_card_queue().flush();
1866 }
1867 
1868 void JavaThread::initialize_queues() {
1869   assert(!SafepointSynchronize::is_at_safepoint(),
1870          "we should not be at a safepoint");
1871 
1872   ObjPtrQueue& satb_queue = satb_mark_queue();
1873   SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1874   // The SATB queue should have been constructed with its active
1875   // field set to false.
1876   assert(!satb_queue.is_active(), "SATB queue should not be active");
1877   assert(satb_queue.is_empty(), "SATB queue should be empty");
1878   // If we are creating the thread during a marking cycle, we should
1879   // set the active field of the SATB queue to true.
1880   if (satb_queue_set.is_active()) {
1881     satb_queue.set_active(true);
1882   }
1883 
1884   DirtyCardQueue& dirty_queue = dirty_card_queue();
1885   // The dirty card queue should have been constructed with its
1886   // active field set to true.
1887   assert(dirty_queue.is_active(), "dirty card queue should be active");
1888 }
1889 #endif // INCLUDE_ALL_GCS
1890 
1891 void JavaThread::cleanup_failed_attach_current_thread() {
1892   if (get_thread_profiler() != NULL) {
1893     get_thread_profiler()->disengage();
1894     ResourceMark rm;
1895     get_thread_profiler()->print(get_thread_name());
1896   }
1897 
1898   if (active_handles() != NULL) {
1899     JNIHandleBlock* block = active_handles();
1900     set_active_handles(NULL);
1901     JNIHandleBlock::release_block(block);
1902   }
1903 
1904   if (free_handle_block() != NULL) {
1905     JNIHandleBlock* block = free_handle_block();
1906     set_free_handle_block(NULL);
1907     JNIHandleBlock::release_block(block);
1908   }
1909 
1910   // These have to be removed while this is still a valid thread.
1911   remove_stack_guard_pages();
1912 
1913   if (UseTLAB) {
1914     tlab().make_parsable(true);  // retire TLAB, if any
1915   }
1916 
1917 #if INCLUDE_ALL_GCS
1918   if (UseG1GC) {
1919     flush_barrier_queues();
1920   }
1921 #endif // INCLUDE_ALL_GCS
1922 
1923   Threads::remove(this);
1924   delete this;
1925 }
1926 
1927 
1928 
1929 
1930 JavaThread* JavaThread::active() {
1931   Thread* thread = ThreadLocalStorage::thread();
1932   assert(thread != NULL, "just checking");
1933   if (thread->is_Java_thread()) {
1934     return (JavaThread*) thread;
1935   } else {
1936     assert(thread->is_VM_thread(), "this must be a vm thread");
1937     VM_Operation* op = ((VMThread*) thread)->vm_operation();
1938     JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
1939     assert(ret->is_Java_thread(), "must be a Java thread");
1940     return ret;
1941   }
1942 }
1943 
1944 bool JavaThread::is_lock_owned(address adr) const {
1945   if (Thread::is_lock_owned(adr)) return true;
1946 
1947   for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
1948     if (chunk->contains(adr)) return true;
1949   }
1950 
1951   return false;
1952 }
1953 
1954 
1955 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
1956   chunk->set_next(monitor_chunks());
1957   set_monitor_chunks(chunk);
1958 }
1959 
1960 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
1961   guarantee(monitor_chunks() != NULL, "must be non empty");
1962   if (monitor_chunks() == chunk) {
1963     set_monitor_chunks(chunk->next());
1964   } else {
1965     MonitorChunk* prev = monitor_chunks();
1966     while (prev->next() != chunk) prev = prev->next();
1967     prev->set_next(chunk->next());
1968   }
1969 }
1970 
1971 // JVM support.
1972 
1973 // Note: this function shouldn't block if it's called in
1974 // _thread_in_native_trans state (such as from
1975 // check_special_condition_for_native_trans()).
1976 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
1977 
1978   if (has_last_Java_frame() && has_async_condition()) {
1979     // If we are at a polling page safepoint (not a poll return)
1980     // then we must defer async exception because live registers
1981     // will be clobbered by the exception path. Poll return is
1982     // ok because the call we a returning from already collides
1983     // with exception handling registers and so there is no issue.
1984     // (The exception handling path kills call result registers but
1985     //  this is ok since the exception kills the result anyway).
1986 
1987     if (is_at_poll_safepoint()) {
1988       // if the code we are returning to has deoptimized we must defer
1989       // the exception otherwise live registers get clobbered on the
1990       // exception path before deoptimization is able to retrieve them.
1991       //
1992       RegisterMap map(this, false);
1993       frame caller_fr = last_frame().sender(&map);
1994       assert(caller_fr.is_compiled_frame(), "what?");
1995       if (caller_fr.is_deoptimized_frame()) {
1996         if (TraceExceptions) {
1997           ResourceMark rm;
1998           tty->print_cr("deferred async exception at compiled safepoint");
1999         }
2000         return;
2001       }
2002     }
2003   }
2004 
2005   JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2006   if (condition == _no_async_condition) {
2007     // Conditions have changed since has_special_runtime_exit_condition()
2008     // was called:
2009     // - if we were here only because of an external suspend request,
2010     //   then that was taken care of above (or cancelled) so we are done
2011     // - if we were here because of another async request, then it has
2012     //   been cleared between the has_special_runtime_exit_condition()
2013     //   and now so again we are done
2014     return;
2015   }
2016 
2017   // Check for pending async. exception
2018   if (_pending_async_exception != NULL) {
2019     // Only overwrite an already pending exception, if it is not a threadDeath.
2020     if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2021 
2022       // We cannot call Exceptions::_throw(...) here because we cannot block
2023       set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2024 
2025       if (TraceExceptions) {
2026         ResourceMark rm;
2027         tty->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", this);
2028         if (has_last_Java_frame()) {
2029           frame f = last_frame();
2030           tty->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", f.pc(), f.sp());
2031         }
2032         tty->print_cr(" of type: %s", InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2033       }
2034       _pending_async_exception = NULL;
2035       clear_has_async_exception();
2036     }
2037   }
2038 
2039   if (check_unsafe_error &&
2040       condition == _async_unsafe_access_error && !has_pending_exception()) {
2041     condition = _no_async_condition;  // done
2042     switch (thread_state()) {
2043     case _thread_in_vm: {
2044       JavaThread* THREAD = this;
2045       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2046     }
2047     case _thread_in_native: {
2048       ThreadInVMfromNative tiv(this);
2049       JavaThread* THREAD = this;
2050       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2051     }
2052     case _thread_in_Java: {
2053       ThreadInVMfromJava tiv(this);
2054       JavaThread* THREAD = this;
2055       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2056     }
2057     default:
2058       ShouldNotReachHere();
2059     }
2060   }
2061 
2062   assert(condition == _no_async_condition || has_pending_exception() ||
2063          (!check_unsafe_error && condition == _async_unsafe_access_error),
2064          "must have handled the async condition, if no exception");
2065 }
2066 
2067 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2068   //
2069   // Check for pending external suspend. Internal suspend requests do
2070   // not use handle_special_runtime_exit_condition().
2071   // If JNIEnv proxies are allowed, don't self-suspend if the target
2072   // thread is not the current thread. In older versions of jdbx, jdbx
2073   // threads could call into the VM with another thread's JNIEnv so we
2074   // can be here operating on behalf of a suspended thread (4432884).
2075   bool do_self_suspend = is_external_suspend_with_lock();
2076   if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2077     //
2078     // Because thread is external suspended the safepoint code will count
2079     // thread as at a safepoint. This can be odd because we can be here
2080     // as _thread_in_Java which would normally transition to _thread_blocked
2081     // at a safepoint. We would like to mark the thread as _thread_blocked
2082     // before calling java_suspend_self like all other callers of it but
2083     // we must then observe proper safepoint protocol. (We can't leave
2084     // _thread_blocked with a safepoint in progress). However we can be
2085     // here as _thread_in_native_trans so we can't use a normal transition
2086     // constructor/destructor pair because they assert on that type of
2087     // transition. We could do something like:
2088     //
2089     // JavaThreadState state = thread_state();
2090     // set_thread_state(_thread_in_vm);
2091     // {
2092     //   ThreadBlockInVM tbivm(this);
2093     //   java_suspend_self()
2094     // }
2095     // set_thread_state(_thread_in_vm_trans);
2096     // if (safepoint) block;
2097     // set_thread_state(state);
2098     //
2099     // but that is pretty messy. Instead we just go with the way the
2100     // code has worked before and note that this is the only path to
2101     // java_suspend_self that doesn't put the thread in _thread_blocked
2102     // mode.
2103 
2104     frame_anchor()->make_walkable(this);
2105     java_suspend_self();
2106 
2107     // We might be here for reasons in addition to the self-suspend request
2108     // so check for other async requests.
2109   }
2110 
2111   if (check_asyncs) {
2112     check_and_handle_async_exceptions();
2113   }
2114 }
2115 
2116 void JavaThread::send_thread_stop(oop java_throwable)  {
2117   assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2118   assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2119   assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2120 
2121   // Do not throw asynchronous exceptions against the compiler thread
2122   // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2123   if (is_Compiler_thread()) return;
2124 
2125   {
2126     // Actually throw the Throwable against the target Thread - however
2127     // only if there is no thread death exception installed already.
2128     if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2129       // If the topmost frame is a runtime stub, then we are calling into
2130       // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2131       // must deoptimize the caller before continuing, as the compiled  exception handler table
2132       // may not be valid
2133       if (has_last_Java_frame()) {
2134         frame f = last_frame();
2135         if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2136           // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2137           RegisterMap reg_map(this, UseBiasedLocking);
2138           frame compiled_frame = f.sender(&reg_map);
2139           if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2140             Deoptimization::deoptimize(this, compiled_frame, &reg_map);
2141           }
2142         }
2143       }
2144 
2145       // Set async. pending exception in thread.
2146       set_pending_async_exception(java_throwable);
2147 
2148       if (TraceExceptions) {
2149         ResourceMark rm;
2150         tty->print_cr("Pending Async. exception installed of type: %s", InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2151       }
2152       // for AbortVMOnException flag
2153       NOT_PRODUCT(Exceptions::debug_check_abort(InstanceKlass::cast(_pending_async_exception->klass())->external_name()));
2154     }
2155   }
2156 
2157 
2158   // Interrupt thread so it will wake up from a potential wait()
2159   Thread::interrupt(this);
2160 }
2161 
2162 // External suspension mechanism.
2163 //
2164 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2165 // to any VM_locks and it is at a transition
2166 // Self-suspension will happen on the transition out of the vm.
2167 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2168 //
2169 // Guarantees on return:
2170 //   + Target thread will not execute any new bytecode (that's why we need to
2171 //     force a safepoint)
2172 //   + Target thread will not enter any new monitors
2173 //
2174 void JavaThread::java_suspend() {
2175   { MutexLocker mu(Threads_lock);
2176     if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2177       return;
2178     }
2179   }
2180 
2181   { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2182     if (!is_external_suspend()) {
2183       // a racing resume has cancelled us; bail out now
2184       return;
2185     }
2186 
2187     // suspend is done
2188     uint32_t debug_bits = 0;
2189     // Warning: is_ext_suspend_completed() may temporarily drop the
2190     // SR_lock to allow the thread to reach a stable thread state if
2191     // it is currently in a transient thread state.
2192     if (is_ext_suspend_completed(false /* !called_by_wait */,
2193                                  SuspendRetryDelay, &debug_bits)) {
2194       return;
2195     }
2196   }
2197 
2198   VM_ForceSafepoint vm_suspend;
2199   VMThread::execute(&vm_suspend);
2200 }
2201 
2202 // Part II of external suspension.
2203 // A JavaThread self suspends when it detects a pending external suspend
2204 // request. This is usually on transitions. It is also done in places
2205 // where continuing to the next transition would surprise the caller,
2206 // e.g., monitor entry.
2207 //
2208 // Returns the number of times that the thread self-suspended.
2209 //
2210 // Note: DO NOT call java_suspend_self() when you just want to block current
2211 //       thread. java_suspend_self() is the second stage of cooperative
2212 //       suspension for external suspend requests and should only be used
2213 //       to complete an external suspend request.
2214 //
2215 int JavaThread::java_suspend_self() {
2216   int ret = 0;
2217 
2218   // we are in the process of exiting so don't suspend
2219   if (is_exiting()) {
2220     clear_external_suspend();
2221     return ret;
2222   }
2223 
2224   assert(_anchor.walkable() ||
2225          (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2226          "must have walkable stack");
2227 
2228   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2229 
2230   assert(!this->is_ext_suspended(),
2231          "a thread trying to self-suspend should not already be suspended");
2232 
2233   if (this->is_suspend_equivalent()) {
2234     // If we are self-suspending as a result of the lifting of a
2235     // suspend equivalent condition, then the suspend_equivalent
2236     // flag is not cleared until we set the ext_suspended flag so
2237     // that wait_for_ext_suspend_completion() returns consistent
2238     // results.
2239     this->clear_suspend_equivalent();
2240   }
2241 
2242   // A racing resume may have cancelled us before we grabbed SR_lock
2243   // above. Or another external suspend request could be waiting for us
2244   // by the time we return from SR_lock()->wait(). The thread
2245   // that requested the suspension may already be trying to walk our
2246   // stack and if we return now, we can change the stack out from under
2247   // it. This would be a "bad thing (TM)" and cause the stack walker
2248   // to crash. We stay self-suspended until there are no more pending
2249   // external suspend requests.
2250   while (is_external_suspend()) {
2251     ret++;
2252     this->set_ext_suspended();
2253 
2254     // _ext_suspended flag is cleared by java_resume()
2255     while (is_ext_suspended()) {
2256       this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2257     }
2258   }
2259 
2260   return ret;
2261 }
2262 
2263 #ifdef ASSERT
2264 // verify the JavaThread has not yet been published in the Threads::list, and
2265 // hence doesn't need protection from concurrent access at this stage
2266 void JavaThread::verify_not_published() {
2267   if (!Threads_lock->owned_by_self()) {
2268     MutexLockerEx ml(Threads_lock,  Mutex::_no_safepoint_check_flag);
2269     assert(!Threads::includes(this),
2270            "java thread shouldn't have been published yet!");
2271   } else {
2272     assert(!Threads::includes(this),
2273            "java thread shouldn't have been published yet!");
2274   }
2275 }
2276 #endif
2277 
2278 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2279 // progress or when _suspend_flags is non-zero.
2280 // Current thread needs to self-suspend if there is a suspend request and/or
2281 // block if a safepoint is in progress.
2282 // Async exception ISN'T checked.
2283 // Note only the ThreadInVMfromNative transition can call this function
2284 // directly and when thread state is _thread_in_native_trans
2285 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2286   assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2287 
2288   JavaThread *curJT = JavaThread::current();
2289   bool do_self_suspend = thread->is_external_suspend();
2290 
2291   assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2292 
2293   // If JNIEnv proxies are allowed, don't self-suspend if the target
2294   // thread is not the current thread. In older versions of jdbx, jdbx
2295   // threads could call into the VM with another thread's JNIEnv so we
2296   // can be here operating on behalf of a suspended thread (4432884).
2297   if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2298     JavaThreadState state = thread->thread_state();
2299 
2300     // We mark this thread_blocked state as a suspend-equivalent so
2301     // that a caller to is_ext_suspend_completed() won't be confused.
2302     // The suspend-equivalent state is cleared by java_suspend_self().
2303     thread->set_suspend_equivalent();
2304 
2305     // If the safepoint code sees the _thread_in_native_trans state, it will
2306     // wait until the thread changes to other thread state. There is no
2307     // guarantee on how soon we can obtain the SR_lock and complete the
2308     // self-suspend request. It would be a bad idea to let safepoint wait for
2309     // too long. Temporarily change the state to _thread_blocked to
2310     // let the VM thread know that this thread is ready for GC. The problem
2311     // of changing thread state is that safepoint could happen just after
2312     // java_suspend_self() returns after being resumed, and VM thread will
2313     // see the _thread_blocked state. We must check for safepoint
2314     // after restoring the state and make sure we won't leave while a safepoint
2315     // is in progress.
2316     thread->set_thread_state(_thread_blocked);
2317     thread->java_suspend_self();
2318     thread->set_thread_state(state);
2319     // Make sure new state is seen by VM thread
2320     if (os::is_MP()) {
2321       if (UseMembar) {
2322         // Force a fence between the write above and read below
2323         OrderAccess::fence();
2324       } else {
2325         // Must use this rather than serialization page in particular on Windows
2326         InterfaceSupport::serialize_memory(thread);
2327       }
2328     }
2329   }
2330 
2331   if (SafepointSynchronize::do_call_back()) {
2332     // If we are safepointing, then block the caller which may not be
2333     // the same as the target thread (see above).
2334     SafepointSynchronize::block(curJT);
2335   }
2336 
2337   if (thread->is_deopt_suspend()) {
2338     thread->clear_deopt_suspend();
2339     RegisterMap map(thread, false);
2340     frame f = thread->last_frame();
2341     while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2342       f = f.sender(&map);
2343     }
2344     if (f.id() == thread->must_deopt_id()) {
2345       thread->clear_must_deopt_id();
2346       f.deoptimize(thread);
2347     } else {
2348       fatal("missed deoptimization!");
2349     }
2350   }
2351 }
2352 
2353 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2354 // progress or when _suspend_flags is non-zero.
2355 // Current thread needs to self-suspend if there is a suspend request and/or
2356 // block if a safepoint is in progress.
2357 // Also check for pending async exception (not including unsafe access error).
2358 // Note only the native==>VM/Java barriers can call this function and when
2359 // thread state is _thread_in_native_trans.
2360 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2361   check_safepoint_and_suspend_for_native_trans(thread);
2362 
2363   if (thread->has_async_exception()) {
2364     // We are in _thread_in_native_trans state, don't handle unsafe
2365     // access error since that may block.
2366     thread->check_and_handle_async_exceptions(false);
2367   }
2368 }
2369 
2370 // This is a variant of the normal
2371 // check_special_condition_for_native_trans with slightly different
2372 // semantics for use by critical native wrappers.  It does all the
2373 // normal checks but also performs the transition back into
2374 // thread_in_Java state.  This is required so that critical natives
2375 // can potentially block and perform a GC if they are the last thread
2376 // exiting the GC_locker.
2377 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2378   check_special_condition_for_native_trans(thread);
2379 
2380   // Finish the transition
2381   thread->set_thread_state(_thread_in_Java);
2382 
2383   if (thread->do_critical_native_unlock()) {
2384     ThreadInVMfromJavaNoAsyncException tiv(thread);
2385     GC_locker::unlock_critical(thread);
2386     thread->clear_critical_native_unlock();
2387   }
2388 }
2389 
2390 // We need to guarantee the Threads_lock here, since resumes are not
2391 // allowed during safepoint synchronization
2392 // Can only resume from an external suspension
2393 void JavaThread::java_resume() {
2394   assert_locked_or_safepoint(Threads_lock);
2395 
2396   // Sanity check: thread is gone, has started exiting or the thread
2397   // was not externally suspended.
2398   if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2399     return;
2400   }
2401 
2402   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2403 
2404   clear_external_suspend();
2405 
2406   if (is_ext_suspended()) {
2407     clear_ext_suspended();
2408     SR_lock()->notify_all();
2409   }
2410 }
2411 
2412 void JavaThread::create_stack_guard_pages() {
2413   if (! os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) return;
2414   address low_addr = stack_base() - stack_size();
2415   size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
2416 
2417   int allocate = os::allocate_stack_guard_pages();
2418   // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2419 
2420   if (allocate && !os::create_stack_guard_pages((char *) low_addr, len)) {
2421     warning("Attempt to allocate stack guard pages failed.");
2422     return;
2423   }
2424 
2425   if (os::guard_memory((char *) low_addr, len)) {
2426     _stack_guard_state = stack_guard_enabled;
2427   } else {
2428     warning("Attempt to protect stack guard pages failed.");
2429     if (os::uncommit_memory((char *) low_addr, len)) {
2430       warning("Attempt to deallocate stack guard pages failed.");
2431     }
2432   }
2433 }
2434 
2435 void JavaThread::remove_stack_guard_pages() {
2436   assert(Thread::current() == this, "from different thread");
2437   if (_stack_guard_state == stack_guard_unused) return;
2438   address low_addr = stack_base() - stack_size();
2439   size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
2440 
2441   if (os::allocate_stack_guard_pages()) {
2442     if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2443       _stack_guard_state = stack_guard_unused;
2444     } else {
2445       warning("Attempt to deallocate stack guard pages failed.");
2446     }
2447   } else {
2448     if (_stack_guard_state == stack_guard_unused) return;
2449     if (os::unguard_memory((char *) low_addr, len)) {
2450       _stack_guard_state = stack_guard_unused;
2451     } else {
2452       warning("Attempt to unprotect stack guard pages failed.");
2453     }
2454   }
2455 }
2456 
2457 void JavaThread::enable_stack_yellow_zone() {
2458   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2459   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2460 
2461   // The base notation is from the stacks point of view, growing downward.
2462   // We need to adjust it to work correctly with guard_memory()
2463   address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2464 
2465   guarantee(base < stack_base(), "Error calculating stack yellow zone");
2466   guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2467 
2468   if (os::guard_memory((char *) base, stack_yellow_zone_size())) {
2469     _stack_guard_state = stack_guard_enabled;
2470   } else {
2471     warning("Attempt to guard stack yellow zone failed.");
2472   }
2473   enable_register_stack_guard();
2474 }
2475 
2476 void JavaThread::disable_stack_yellow_zone() {
2477   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2478   assert(_stack_guard_state != stack_guard_yellow_disabled, "already disabled");
2479 
2480   // Simply return if called for a thread that does not use guard pages.
2481   if (_stack_guard_state == stack_guard_unused) return;
2482 
2483   // The base notation is from the stacks point of view, growing downward.
2484   // We need to adjust it to work correctly with guard_memory()
2485   address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2486 
2487   if (os::unguard_memory((char *)base, stack_yellow_zone_size())) {
2488     _stack_guard_state = stack_guard_yellow_disabled;
2489   } else {
2490     warning("Attempt to unguard stack yellow zone failed.");
2491   }
2492   disable_register_stack_guard();
2493 }
2494 
2495 void JavaThread::enable_stack_red_zone() {
2496   // The base notation is from the stacks point of view, growing downward.
2497   // We need to adjust it to work correctly with guard_memory()
2498   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2499   address base = stack_red_zone_base() - stack_red_zone_size();
2500 
2501   guarantee(base < stack_base(), "Error calculating stack red zone");
2502   guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2503 
2504   if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2505     warning("Attempt to guard stack red zone failed.");
2506   }
2507 }
2508 
2509 void JavaThread::disable_stack_red_zone() {
2510   // The base notation is from the stacks point of view, growing downward.
2511   // We need to adjust it to work correctly with guard_memory()
2512   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2513   address base = stack_red_zone_base() - stack_red_zone_size();
2514   if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2515     warning("Attempt to unguard stack red zone failed.");
2516   }
2517 }
2518 
2519 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2520   // ignore is there is no stack
2521   if (!has_last_Java_frame()) return;
2522   // traverse the stack frames. Starts from top frame.
2523   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2524     frame* fr = fst.current();
2525     f(fr, fst.register_map());
2526   }
2527 }
2528 
2529 
2530 #ifndef PRODUCT
2531 // Deoptimization
2532 // Function for testing deoptimization
2533 void JavaThread::deoptimize() {
2534   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2535   StackFrameStream fst(this, UseBiasedLocking);
2536   bool deopt = false;           // Dump stack only if a deopt actually happens.
2537   bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2538   // Iterate over all frames in the thread and deoptimize
2539   for (; !fst.is_done(); fst.next()) {
2540     if (fst.current()->can_be_deoptimized()) {
2541 
2542       if (only_at) {
2543         // Deoptimize only at particular bcis.  DeoptimizeOnlyAt
2544         // consists of comma or carriage return separated numbers so
2545         // search for the current bci in that string.
2546         address pc = fst.current()->pc();
2547         nmethod* nm =  (nmethod*) fst.current()->cb();
2548         ScopeDesc* sd = nm->scope_desc_at(pc);
2549         char buffer[8];
2550         jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2551         size_t len = strlen(buffer);
2552         const char * found = strstr(DeoptimizeOnlyAt, buffer);
2553         while (found != NULL) {
2554           if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2555               (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2556             // Check that the bci found is bracketed by terminators.
2557             break;
2558           }
2559           found = strstr(found + 1, buffer);
2560         }
2561         if (!found) {
2562           continue;
2563         }
2564       }
2565 
2566       if (DebugDeoptimization && !deopt) {
2567         deopt = true; // One-time only print before deopt
2568         tty->print_cr("[BEFORE Deoptimization]");
2569         trace_frames();
2570         trace_stack();
2571       }
2572       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2573     }
2574   }
2575 
2576   if (DebugDeoptimization && deopt) {
2577     tty->print_cr("[AFTER Deoptimization]");
2578     trace_frames();
2579   }
2580 }
2581 
2582 
2583 // Make zombies
2584 void JavaThread::make_zombies() {
2585   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2586     if (fst.current()->can_be_deoptimized()) {
2587       // it is a Java nmethod
2588       nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2589       nm->make_not_entrant();
2590     }
2591   }
2592 }
2593 #endif // PRODUCT
2594 
2595 
2596 void JavaThread::deoptimized_wrt_marked_nmethods() {
2597   if (!has_last_Java_frame()) return;
2598   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2599   StackFrameStream fst(this, UseBiasedLocking);
2600   for (; !fst.is_done(); fst.next()) {
2601     if (fst.current()->should_be_deoptimized()) {
2602       if (LogCompilation && xtty != NULL) {
2603         nmethod* nm = fst.current()->cb()->as_nmethod_or_null();
2604         xtty->elem("deoptimized thread='" UINTX_FORMAT "' compile_id='%d'",
2605                    this->name(), nm != NULL ? nm->compile_id() : -1);
2606       }
2607 
2608       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2609     }
2610   }
2611 }
2612 
2613 
2614 // If the caller is a NamedThread, then remember, in the current scope,
2615 // the given JavaThread in its _processed_thread field.
2616 class RememberProcessedThread: public StackObj {
2617   NamedThread* _cur_thr;
2618  public:
2619   RememberProcessedThread(JavaThread* jthr) {
2620     Thread* thread = Thread::current();
2621     if (thread->is_Named_thread()) {
2622       _cur_thr = (NamedThread *)thread;
2623       _cur_thr->set_processed_thread(jthr);
2624     } else {
2625       _cur_thr = NULL;
2626     }
2627   }
2628 
2629   ~RememberProcessedThread() {
2630     if (_cur_thr) {
2631       _cur_thr->set_processed_thread(NULL);
2632     }
2633   }
2634 };
2635 
2636 void JavaThread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
2637   // Verify that the deferred card marks have been flushed.
2638   assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2639 
2640   // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2641   // since there may be more than one thread using each ThreadProfiler.
2642 
2643   // Traverse the GCHandles
2644   Thread::oops_do(f, cld_f, cf);
2645 
2646   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2647          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2648 
2649   if (has_last_Java_frame()) {
2650     // Record JavaThread to GC thread
2651     RememberProcessedThread rpt(this);
2652 
2653     // Traverse the privileged stack
2654     if (_privileged_stack_top != NULL) {
2655       _privileged_stack_top->oops_do(f);
2656     }
2657 
2658     // traverse the registered growable array
2659     if (_array_for_gc != NULL) {
2660       for (int index = 0; index < _array_for_gc->length(); index++) {
2661         f->do_oop(_array_for_gc->adr_at(index));
2662       }
2663     }
2664 
2665     // Traverse the monitor chunks
2666     for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2667       chunk->oops_do(f);
2668     }
2669 
2670     // Traverse the execution stack
2671     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2672       fst.current()->oops_do(f, cld_f, cf, fst.register_map());
2673     }
2674   }
2675 
2676   // callee_target is never live across a gc point so NULL it here should
2677   // it still contain a methdOop.
2678 
2679   set_callee_target(NULL);
2680 
2681   assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2682   // If we have deferred set_locals there might be oops waiting to be
2683   // written
2684   GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2685   if (list != NULL) {
2686     for (int i = 0; i < list->length(); i++) {
2687       list->at(i)->oops_do(f);
2688     }
2689   }
2690 
2691   // Traverse instance variables at the end since the GC may be moving things
2692   // around using this function
2693   f->do_oop((oop*) &_threadObj);
2694   f->do_oop((oop*) &_vm_result);
2695   f->do_oop((oop*) &_exception_oop);
2696   f->do_oop((oop*) &_pending_async_exception);
2697 
2698   if (jvmti_thread_state() != NULL) {
2699     jvmti_thread_state()->oops_do(f);
2700   }
2701 }
2702 
2703 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2704   Thread::nmethods_do(cf);  // (super method is a no-op)
2705 
2706   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2707          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2708 
2709   if (has_last_Java_frame()) {
2710     // Traverse the execution stack
2711     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2712       fst.current()->nmethods_do(cf);
2713     }
2714   }
2715 }
2716 
2717 void JavaThread::metadata_do(void f(Metadata*)) {
2718   if (has_last_Java_frame()) {
2719     // Traverse the execution stack to call f() on the methods in the stack
2720     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2721       fst.current()->metadata_do(f);
2722     }
2723   } else if (is_Compiler_thread()) {
2724     // need to walk ciMetadata in current compile tasks to keep alive.
2725     CompilerThread* ct = (CompilerThread*)this;
2726     if (ct->env() != NULL) {
2727       ct->env()->metadata_do(f);
2728     }
2729   }
2730 }
2731 
2732 // Printing
2733 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2734   switch (_thread_state) {
2735   case _thread_uninitialized:     return "_thread_uninitialized";
2736   case _thread_new:               return "_thread_new";
2737   case _thread_new_trans:         return "_thread_new_trans";
2738   case _thread_in_native:         return "_thread_in_native";
2739   case _thread_in_native_trans:   return "_thread_in_native_trans";
2740   case _thread_in_vm:             return "_thread_in_vm";
2741   case _thread_in_vm_trans:       return "_thread_in_vm_trans";
2742   case _thread_in_Java:           return "_thread_in_Java";
2743   case _thread_in_Java_trans:     return "_thread_in_Java_trans";
2744   case _thread_blocked:           return "_thread_blocked";
2745   case _thread_blocked_trans:     return "_thread_blocked_trans";
2746   default:                        return "unknown thread state";
2747   }
2748 }
2749 
2750 #ifndef PRODUCT
2751 void JavaThread::print_thread_state_on(outputStream *st) const {
2752   st->print_cr("   JavaThread state: %s", _get_thread_state_name(_thread_state));
2753 };
2754 void JavaThread::print_thread_state() const {
2755   print_thread_state_on(tty);
2756 }
2757 #endif // PRODUCT
2758 
2759 // Called by Threads::print() for VM_PrintThreads operation
2760 void JavaThread::print_on(outputStream *st) const {
2761   st->print("\"%s\" ", get_thread_name());
2762   oop thread_oop = threadObj();
2763   if (thread_oop != NULL) {
2764     st->print("#" INT64_FORMAT " ", java_lang_Thread::thread_id(thread_oop));
2765     if (java_lang_Thread::is_daemon(thread_oop))  st->print("daemon ");
2766     st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2767   }
2768   Thread::print_on(st);
2769   // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2770   st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2771   if (thread_oop != NULL) {
2772     st->print_cr("   java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2773   }
2774 #ifndef PRODUCT
2775   print_thread_state_on(st);
2776   _safepoint_state->print_on(st);
2777 #endif // PRODUCT
2778 }
2779 
2780 // Called by fatal error handler. The difference between this and
2781 // JavaThread::print() is that we can't grab lock or allocate memory.
2782 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2783   st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2784   oop thread_obj = threadObj();
2785   if (thread_obj != NULL) {
2786     if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2787   }
2788   st->print(" [");
2789   st->print("%s", _get_thread_state_name(_thread_state));
2790   if (osthread()) {
2791     st->print(", id=%d", osthread()->thread_id());
2792   }
2793   st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2794             _stack_base - _stack_size, _stack_base);
2795   st->print("]");
2796   return;
2797 }
2798 
2799 // Verification
2800 
2801 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2802 
2803 void JavaThread::verify() {
2804   // Verify oops in the thread.
2805   oops_do(&VerifyOopClosure::verify_oop, NULL, NULL);
2806 
2807   // Verify the stack frames.
2808   frames_do(frame_verify);
2809 }
2810 
2811 // CR 6300358 (sub-CR 2137150)
2812 // Most callers of this method assume that it can't return NULL but a
2813 // thread may not have a name whilst it is in the process of attaching to
2814 // the VM - see CR 6412693, and there are places where a JavaThread can be
2815 // seen prior to having it's threadObj set (eg JNI attaching threads and
2816 // if vm exit occurs during initialization). These cases can all be accounted
2817 // for such that this method never returns NULL.
2818 const char* JavaThread::get_thread_name() const {
2819 #ifdef ASSERT
2820   // early safepoints can hit while current thread does not yet have TLS
2821   if (!SafepointSynchronize::is_at_safepoint()) {
2822     Thread *cur = Thread::current();
2823     if (!(cur->is_Java_thread() && cur == this)) {
2824       // Current JavaThreads are allowed to get their own name without
2825       // the Threads_lock.
2826       assert_locked_or_safepoint(Threads_lock);
2827     }
2828   }
2829 #endif // ASSERT
2830   return get_thread_name_string();
2831 }
2832 
2833 // Returns a non-NULL representation of this thread's name, or a suitable
2834 // descriptive string if there is no set name
2835 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
2836   const char* name_str;
2837   oop thread_obj = threadObj();
2838   if (thread_obj != NULL) {
2839     oop name = java_lang_Thread::name(thread_obj);
2840     if (name != NULL) {
2841       if (buf == NULL) {
2842         name_str = java_lang_String::as_utf8_string(name);
2843       } else {
2844         name_str = java_lang_String::as_utf8_string(name, buf, buflen);
2845       }
2846     } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
2847       name_str = "<no-name - thread is attaching>";
2848     } else {
2849       name_str = Thread::name();
2850     }
2851   } else {
2852     name_str = Thread::name();
2853   }
2854   assert(name_str != NULL, "unexpected NULL thread name");
2855   return name_str;
2856 }
2857 
2858 
2859 const char* JavaThread::get_threadgroup_name() const {
2860   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2861   oop thread_obj = threadObj();
2862   if (thread_obj != NULL) {
2863     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2864     if (thread_group != NULL) {
2865       typeArrayOop name = java_lang_ThreadGroup::name(thread_group);
2866       // ThreadGroup.name can be null
2867       if (name != NULL) {
2868         const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2869         return str;
2870       }
2871     }
2872   }
2873   return NULL;
2874 }
2875 
2876 const char* JavaThread::get_parent_name() const {
2877   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2878   oop thread_obj = threadObj();
2879   if (thread_obj != NULL) {
2880     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2881     if (thread_group != NULL) {
2882       oop parent = java_lang_ThreadGroup::parent(thread_group);
2883       if (parent != NULL) {
2884         typeArrayOop name = java_lang_ThreadGroup::name(parent);
2885         // ThreadGroup.name can be null
2886         if (name != NULL) {
2887           const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2888           return str;
2889         }
2890       }
2891     }
2892   }
2893   return NULL;
2894 }
2895 
2896 ThreadPriority JavaThread::java_priority() const {
2897   oop thr_oop = threadObj();
2898   if (thr_oop == NULL) return NormPriority; // Bootstrapping
2899   ThreadPriority priority = java_lang_Thread::priority(thr_oop);
2900   assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
2901   return priority;
2902 }
2903 
2904 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
2905 
2906   assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
2907   // Link Java Thread object <-> C++ Thread
2908 
2909   // Get the C++ thread object (an oop) from the JNI handle (a jthread)
2910   // and put it into a new Handle.  The Handle "thread_oop" can then
2911   // be used to pass the C++ thread object to other methods.
2912 
2913   // Set the Java level thread object (jthread) field of the
2914   // new thread (a JavaThread *) to C++ thread object using the
2915   // "thread_oop" handle.
2916 
2917   // Set the thread field (a JavaThread *) of the
2918   // oop representing the java_lang_Thread to the new thread (a JavaThread *).
2919 
2920   Handle thread_oop(Thread::current(),
2921                     JNIHandles::resolve_non_null(jni_thread));
2922   assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
2923          "must be initialized");
2924   set_threadObj(thread_oop());
2925   java_lang_Thread::set_thread(thread_oop(), this);
2926 
2927   if (prio == NoPriority) {
2928     prio = java_lang_Thread::priority(thread_oop());
2929     assert(prio != NoPriority, "A valid priority should be present");
2930   }
2931 
2932   // Push the Java priority down to the native thread; needs Threads_lock
2933   Thread::set_priority(this, prio);
2934 
2935   prepare_ext();
2936 
2937   // Add the new thread to the Threads list and set it in motion.
2938   // We must have threads lock in order to call Threads::add.
2939   // It is crucial that we do not block before the thread is
2940   // added to the Threads list for if a GC happens, then the java_thread oop
2941   // will not be visited by GC.
2942   Threads::add(this);
2943 }
2944 
2945 oop JavaThread::current_park_blocker() {
2946   // Support for JSR-166 locks
2947   oop thread_oop = threadObj();
2948   if (thread_oop != NULL &&
2949       JDK_Version::current().supports_thread_park_blocker()) {
2950     return java_lang_Thread::park_blocker(thread_oop);
2951   }
2952   return NULL;
2953 }
2954 
2955 
2956 void JavaThread::print_stack_on(outputStream* st) {
2957   if (!has_last_Java_frame()) return;
2958   ResourceMark rm;
2959   HandleMark   hm;
2960 
2961   RegisterMap reg_map(this);
2962   vframe* start_vf = last_java_vframe(&reg_map);
2963   int count = 0;
2964   for (vframe* f = start_vf; f; f = f->sender()) {
2965     if (f->is_java_frame()) {
2966       javaVFrame* jvf = javaVFrame::cast(f);
2967       java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
2968 
2969       // Print out lock information
2970       if (JavaMonitorsInStackTrace) {
2971         jvf->print_lock_info_on(st, count);
2972       }
2973     } else {
2974       // Ignore non-Java frames
2975     }
2976 
2977     // Bail-out case for too deep stacks
2978     count++;
2979     if (MaxJavaStackTraceDepth == count) return;
2980   }
2981 }
2982 
2983 
2984 // JVMTI PopFrame support
2985 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
2986   assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
2987   if (in_bytes(size_in_bytes) != 0) {
2988     _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
2989     _popframe_preserved_args_size = in_bytes(size_in_bytes);
2990     Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
2991   }
2992 }
2993 
2994 void* JavaThread::popframe_preserved_args() {
2995   return _popframe_preserved_args;
2996 }
2997 
2998 ByteSize JavaThread::popframe_preserved_args_size() {
2999   return in_ByteSize(_popframe_preserved_args_size);
3000 }
3001 
3002 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3003   int sz = in_bytes(popframe_preserved_args_size());
3004   assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3005   return in_WordSize(sz / wordSize);
3006 }
3007 
3008 void JavaThread::popframe_free_preserved_args() {
3009   assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3010   FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3011   _popframe_preserved_args = NULL;
3012   _popframe_preserved_args_size = 0;
3013 }
3014 
3015 #ifndef PRODUCT
3016 
3017 void JavaThread::trace_frames() {
3018   tty->print_cr("[Describe stack]");
3019   int frame_no = 1;
3020   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3021     tty->print("  %d. ", frame_no++);
3022     fst.current()->print_value_on(tty, this);
3023     tty->cr();
3024   }
3025 }
3026 
3027 class PrintAndVerifyOopClosure: public OopClosure {
3028  protected:
3029   template <class T> inline void do_oop_work(T* p) {
3030     oop obj = oopDesc::load_decode_heap_oop(p);
3031     if (obj == NULL) return;
3032     tty->print(INTPTR_FORMAT ": ", p);
3033     if (obj->is_oop_or_null()) {
3034       if (obj->is_objArray()) {
3035         tty->print_cr("valid objArray: " INTPTR_FORMAT, (oopDesc*) obj);
3036       } else {
3037         obj->print();
3038       }
3039     } else {
3040       tty->print_cr("invalid oop: " INTPTR_FORMAT, (oopDesc*) obj);
3041     }
3042     tty->cr();
3043   }
3044  public:
3045   virtual void do_oop(oop* p) { do_oop_work(p); }
3046   virtual void do_oop(narrowOop* p)  { do_oop_work(p); }
3047 };
3048 
3049 
3050 static void oops_print(frame* f, const RegisterMap *map) {
3051   PrintAndVerifyOopClosure print;
3052   f->print_value();
3053   f->oops_do(&print, NULL, NULL, (RegisterMap*)map);
3054 }
3055 
3056 // Print our all the locations that contain oops and whether they are
3057 // valid or not.  This useful when trying to find the oldest frame
3058 // where an oop has gone bad since the frame walk is from youngest to
3059 // oldest.
3060 void JavaThread::trace_oops() {
3061   tty->print_cr("[Trace oops]");
3062   frames_do(oops_print);
3063 }
3064 
3065 
3066 #ifdef ASSERT
3067 // Print or validate the layout of stack frames
3068 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3069   ResourceMark rm;
3070   PRESERVE_EXCEPTION_MARK;
3071   FrameValues values;
3072   int frame_no = 0;
3073   for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3074     fst.current()->describe(values, ++frame_no);
3075     if (depth == frame_no) break;
3076   }
3077   if (validate_only) {
3078     values.validate();
3079   } else {
3080     tty->print_cr("[Describe stack layout]");
3081     values.print(this);
3082   }
3083 }
3084 #endif
3085 
3086 void JavaThread::trace_stack_from(vframe* start_vf) {
3087   ResourceMark rm;
3088   int vframe_no = 1;
3089   for (vframe* f = start_vf; f; f = f->sender()) {
3090     if (f->is_java_frame()) {
3091       javaVFrame::cast(f)->print_activation(vframe_no++);
3092     } else {
3093       f->print();
3094     }
3095     if (vframe_no > StackPrintLimit) {
3096       tty->print_cr("...<more frames>...");
3097       return;
3098     }
3099   }
3100 }
3101 
3102 
3103 void JavaThread::trace_stack() {
3104   if (!has_last_Java_frame()) return;
3105   ResourceMark rm;
3106   HandleMark   hm;
3107   RegisterMap reg_map(this);
3108   trace_stack_from(last_java_vframe(&reg_map));
3109 }
3110 
3111 
3112 #endif // PRODUCT
3113 
3114 
3115 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3116   assert(reg_map != NULL, "a map must be given");
3117   frame f = last_frame();
3118   for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3119     if (vf->is_java_frame()) return javaVFrame::cast(vf);
3120   }
3121   return NULL;
3122 }
3123 
3124 
3125 Klass* JavaThread::security_get_caller_class(int depth) {
3126   vframeStream vfst(this);
3127   vfst.security_get_caller_frame(depth);
3128   if (!vfst.at_end()) {
3129     return vfst.method()->method_holder();
3130   }
3131   return NULL;
3132 }
3133 
3134 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3135   assert(thread->is_Compiler_thread(), "must be compiler thread");
3136   CompileBroker::compiler_thread_loop();
3137 }
3138 
3139 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3140   NMethodSweeper::sweeper_loop();
3141 }
3142 
3143 // Create a CompilerThread
3144 CompilerThread::CompilerThread(CompileQueue* queue,
3145                                CompilerCounters* counters)
3146                                : JavaThread(&compiler_thread_entry) {
3147   _env   = NULL;
3148   _log   = NULL;
3149   _task  = NULL;
3150   _queue = queue;
3151   _counters = counters;
3152   _buffer_blob = NULL;
3153   _compiler = NULL;
3154 
3155 #ifndef PRODUCT
3156   _ideal_graph_printer = NULL;
3157 #endif
3158 }
3159 
3160 // Create sweeper thread
3161 CodeCacheSweeperThread::CodeCacheSweeperThread()
3162 : JavaThread(&sweeper_thread_entry) {
3163   _scanned_nmethod = NULL;
3164 }
3165 void CodeCacheSweeperThread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
3166   JavaThread::oops_do(f, cld_f, cf);
3167   if (_scanned_nmethod != NULL && cf != NULL) {
3168     // Safepoints can occur when the sweeper is scanning an nmethod so
3169     // process it here to make sure it isn't unloaded in the middle of
3170     // a scan.
3171     cf->do_code_blob(_scanned_nmethod);
3172   }
3173 }
3174 
3175 
3176 // ======= Threads ========
3177 
3178 // The Threads class links together all active threads, and provides
3179 // operations over all threads.  It is protected by its own Mutex
3180 // lock, which is also used in other contexts to protect thread
3181 // operations from having the thread being operated on from exiting
3182 // and going away unexpectedly (e.g., safepoint synchronization)
3183 
3184 JavaThread* Threads::_thread_list = NULL;
3185 int         Threads::_number_of_threads = 0;
3186 int         Threads::_number_of_non_daemon_threads = 0;
3187 int         Threads::_return_code = 0;
3188 int         Threads::_thread_claim_parity = 0;
3189 size_t      JavaThread::_stack_size_at_create = 0;
3190 #ifdef ASSERT
3191 bool        Threads::_vm_complete = false;
3192 #endif
3193 
3194 // All JavaThreads
3195 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
3196 
3197 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3198 void Threads::threads_do(ThreadClosure* tc) {
3199   assert_locked_or_safepoint(Threads_lock);
3200   // ALL_JAVA_THREADS iterates through all JavaThreads
3201   ALL_JAVA_THREADS(p) {
3202     tc->do_thread(p);
3203   }
3204   // Someday we could have a table or list of all non-JavaThreads.
3205   // For now, just manually iterate through them.
3206   tc->do_thread(VMThread::vm_thread());
3207   Universe::heap()->gc_threads_do(tc);
3208   WatcherThread *wt = WatcherThread::watcher_thread();
3209   // Strictly speaking, the following NULL check isn't sufficient to make sure
3210   // the data for WatcherThread is still valid upon being examined. However,
3211   // considering that WatchThread terminates when the VM is on the way to
3212   // exit at safepoint, the chance of the above is extremely small. The right
3213   // way to prevent termination of WatcherThread would be to acquire
3214   // Terminator_lock, but we can't do that without violating the lock rank
3215   // checking in some cases.
3216   if (wt != NULL) {
3217     tc->do_thread(wt);
3218   }
3219 
3220   // If CompilerThreads ever become non-JavaThreads, add them here
3221 }
3222 
3223 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3224   TraceTime timer("Initialize java.lang classes", TraceStartupTime);
3225 
3226   if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3227     create_vm_init_libraries();
3228   }
3229 
3230   initialize_class(vmSymbols::java_lang_String(), CHECK);
3231 
3232   // Initialize java_lang.System (needed before creating the thread)
3233   initialize_class(vmSymbols::java_lang_System(), CHECK);
3234   // The VM creates & returns objects of this class. Make sure it's initialized.
3235   initialize_class(vmSymbols::java_lang_Class(), CHECK);
3236   initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3237   Handle thread_group = create_initial_thread_group(CHECK);
3238   Universe::set_main_thread_group(thread_group());
3239   initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3240   oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3241   main_thread->set_threadObj(thread_object);
3242   // Set thread status to running since main thread has
3243   // been started and running.
3244   java_lang_Thread::set_thread_status(thread_object,
3245                                       java_lang_Thread::RUNNABLE);
3246 
3247   // The VM preresolves methods to these classes. Make sure that they get initialized
3248   initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3249   initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3250   call_initializeSystemClass(CHECK);
3251 
3252   // get the Java runtime name after java.lang.System is initialized
3253   JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3254   JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3255 
3256   // an instance of OutOfMemory exception has been allocated earlier
3257   initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3258   initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3259   initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3260   initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3261   initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3262   initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3263   initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3264   initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3265 }
3266 
3267 void Threads::initialize_jsr292_core_classes(TRAPS) {
3268   initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3269   initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3270   initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3271 }
3272 
3273 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3274   extern void JDK_Version_init();
3275 
3276   // Check version
3277   if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3278 
3279   // Initialize the output stream module
3280   ostream_init();
3281 
3282   // Process java launcher properties.
3283   Arguments::process_sun_java_launcher_properties(args);
3284 
3285   // Initialize the os module before using TLS
3286   os::init();
3287 
3288   // Initialize system properties.
3289   Arguments::init_system_properties();
3290 
3291   // So that JDK version can be used as a discriminator when parsing arguments
3292   JDK_Version_init();
3293 
3294   // Update/Initialize System properties after JDK version number is known
3295   Arguments::init_version_specific_system_properties();
3296 
3297   // Parse arguments
3298   jint parse_result = Arguments::parse(args);
3299   if (parse_result != JNI_OK) return parse_result;
3300 
3301   os::init_before_ergo();
3302 
3303   jint ergo_result = Arguments::apply_ergo();
3304   if (ergo_result != JNI_OK) return ergo_result;
3305 





3306   if (PauseAtStartup) {
3307     os::pause();
3308   }
3309 
3310   HOTSPOT_VM_INIT_BEGIN();
3311 
3312   // Record VM creation timing statistics
3313   TraceVmCreationTime create_vm_timer;
3314   create_vm_timer.start();
3315 
3316   // Timing (must come after argument parsing)
3317   TraceTime timer("Create VM", TraceStartupTime);
3318 
3319   // Initialize the os module after parsing the args
3320   jint os_init_2_result = os::init_2();
3321   if (os_init_2_result != JNI_OK) return os_init_2_result;
3322 
3323   jint adjust_after_os_result = Arguments::adjust_after_os();
3324   if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3325 
3326   // initialize TLS
3327   ThreadLocalStorage::init();
3328 
3329   // Initialize output stream logging
3330   ostream_init_log();
3331 
3332   // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3333   // Must be before create_vm_init_agents()
3334   if (Arguments::init_libraries_at_startup()) {
3335     convert_vm_init_libraries_to_agents();
3336   }
3337 
3338   // Launch -agentlib/-agentpath and converted -Xrun agents
3339   if (Arguments::init_agents_at_startup()) {
3340     create_vm_init_agents();
3341   }
3342 
3343   // Initialize Threads state
3344   _thread_list = NULL;
3345   _number_of_threads = 0;
3346   _number_of_non_daemon_threads = 0;
3347 
3348   // Initialize global data structures and create system classes in heap
3349   vm_init_globals();
3350 
3351   // Attach the main thread to this os thread
3352   JavaThread* main_thread = new JavaThread();
3353   main_thread->set_thread_state(_thread_in_vm);
3354   // must do this before set_active_handles and initialize_thread_local_storage
3355   // Note: on solaris initialize_thread_local_storage() will (indirectly)
3356   // change the stack size recorded here to one based on the java thread
3357   // stacksize. This adjusted size is what is used to figure the placement
3358   // of the guard pages.
3359   main_thread->record_stack_base_and_size();
3360   main_thread->initialize_thread_local_storage();
3361 
3362   main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3363 
3364   if (!main_thread->set_as_starting_thread()) {
3365     vm_shutdown_during_initialization(
3366                                       "Failed necessary internal allocation. Out of swap space");
3367     delete main_thread;
3368     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3369     return JNI_ENOMEM;
3370   }
3371 
3372   // Enable guard page *after* os::create_main_thread(), otherwise it would
3373   // crash Linux VM, see notes in os_linux.cpp.
3374   main_thread->create_stack_guard_pages();
3375 
3376   // Initialize Java-Level synchronization subsystem
3377   ObjectMonitor::Initialize();
3378 
3379   // Initialize global modules
3380   jint status = init_globals();
3381   if (status != JNI_OK) {
3382     delete main_thread;
3383     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3384     return status;
3385   }
3386 
3387   // Should be done after the heap is fully created
3388   main_thread->cache_global_variables();
3389 
3390   HandleMark hm;
3391 
3392   { MutexLocker mu(Threads_lock);
3393     Threads::add(main_thread);
3394   }
3395 
3396   // Any JVMTI raw monitors entered in onload will transition into
3397   // real raw monitor. VM is setup enough here for raw monitor enter.
3398   JvmtiExport::transition_pending_onload_raw_monitors();
3399 
3400   // Create the VMThread
3401   { TraceTime timer("Start VMThread", TraceStartupTime);
3402     VMThread::create();
3403     Thread* vmthread = VMThread::vm_thread();
3404 
3405     if (!os::create_thread(vmthread, os::vm_thread)) {
3406       vm_exit_during_initialization("Cannot create VM thread. "
3407                                     "Out of system resources.");
3408     }
3409 
3410     // Wait for the VM thread to become ready, and VMThread::run to initialize
3411     // Monitors can have spurious returns, must always check another state flag
3412     {
3413       MutexLocker ml(Notify_lock);
3414       os::start_thread(vmthread);
3415       while (vmthread->active_handles() == NULL) {
3416         Notify_lock->wait();
3417       }
3418     }
3419   }
3420 
3421   assert(Universe::is_fully_initialized(), "not initialized");
3422   if (VerifyDuringStartup) {
3423     // Make sure we're starting with a clean slate.
3424     VM_Verify verify_op;
3425     VMThread::execute(&verify_op);
3426   }
3427 
3428   Thread* THREAD = Thread::current();
3429 
3430   // At this point, the Universe is initialized, but we have not executed
3431   // any byte code.  Now is a good time (the only time) to dump out the
3432   // internal state of the JVM for sharing.
3433   if (DumpSharedSpaces) {
3434     MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3435     ShouldNotReachHere();
3436   }
3437 
3438   // Always call even when there are not JVMTI environments yet, since environments
3439   // may be attached late and JVMTI must track phases of VM execution
3440   JvmtiExport::enter_start_phase();
3441 
3442   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3443   JvmtiExport::post_vm_start();
3444 
3445   initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3446 
3447   // We need this for ClassDataSharing - the initial vm.info property is set
3448   // with the default value of CDS "sharing" which may be reset through
3449   // command line options.
3450   reset_vm_info_property(CHECK_JNI_ERR);
3451 
3452   quicken_jni_functions();
3453 
3454   // Must be run after init_ft which initializes ft_enabled
3455   if (TRACE_INITIALIZE() != JNI_OK) {
3456     vm_exit_during_initialization("Failed to initialize tracing backend");
3457   }
3458 
3459   // Set flag that basic initialization has completed. Used by exceptions and various
3460   // debug stuff, that does not work until all basic classes have been initialized.
3461   set_init_completed();
3462 
3463   Metaspace::post_initialize();
3464 
3465   HOTSPOT_VM_INIT_END();
3466 
3467   // record VM initialization completion time
3468 #if INCLUDE_MANAGEMENT
3469   Management::record_vm_init_completed();
3470 #endif // INCLUDE_MANAGEMENT
3471 
3472   // Compute system loader. Note that this has to occur after set_init_completed, since
3473   // valid exceptions may be thrown in the process.
3474   // Note that we do not use CHECK_0 here since we are inside an EXCEPTION_MARK and
3475   // set_init_completed has just been called, causing exceptions not to be shortcut
3476   // anymore. We call vm_exit_during_initialization directly instead.
3477   SystemDictionary::compute_java_system_loader(CHECK_JNI_ERR);
3478 
3479 #if INCLUDE_ALL_GCS
3480   // Support for ConcurrentMarkSweep. This should be cleaned up
3481   // and better encapsulated. The ugly nested if test would go away
3482   // once things are properly refactored. XXX YSR
3483   if (UseConcMarkSweepGC || UseG1GC) {
3484     if (UseConcMarkSweepGC) {
3485       ConcurrentMarkSweepThread::makeSurrogateLockerThread(CHECK_JNI_ERR);
3486     } else {
3487       ConcurrentMarkThread::makeSurrogateLockerThread(CHECK_JNI_ERR);
3488     }
3489   }
3490 #endif // INCLUDE_ALL_GCS
3491 
3492   // Always call even when there are not JVMTI environments yet, since environments
3493   // may be attached late and JVMTI must track phases of VM execution
3494   JvmtiExport::enter_live_phase();
3495 
3496   // Signal Dispatcher needs to be started before VMInit event is posted
3497   os::signal_init();
3498 
3499   // Start Attach Listener if +StartAttachListener or it can't be started lazily
3500   if (!DisableAttachMechanism) {
3501     AttachListener::vm_start();
3502     if (StartAttachListener || AttachListener::init_at_startup()) {
3503       AttachListener::init();
3504     }
3505   }
3506 
3507   // Launch -Xrun agents
3508   // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3509   // back-end can launch with -Xdebug -Xrunjdwp.
3510   if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3511     create_vm_init_libraries();
3512   }
3513 
3514   // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3515   JvmtiExport::post_vm_initialized();
3516 
3517   if (TRACE_START() != JNI_OK) {
3518     vm_exit_during_initialization("Failed to start tracing backend.");
3519   }
3520 
3521   if (CleanChunkPoolAsync) {
3522     Chunk::start_chunk_pool_cleaner_task();
3523   }
3524 
3525   // initialize compiler(s)
3526 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK)
3527   CompileBroker::compilation_init();
3528 #endif
3529 
3530   // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3531   // It is done after compilers are initialized, because otherwise compilations of
3532   // signature polymorphic MH intrinsics can be missed
3533   // (see SystemDictionary::find_method_handle_intrinsic).
3534   initialize_jsr292_core_classes(CHECK_JNI_ERR);
3535 
3536 #if INCLUDE_MANAGEMENT
3537   Management::initialize(THREAD);
3538 
3539   if (HAS_PENDING_EXCEPTION) {
3540     // management agent fails to start possibly due to
3541     // configuration problem and is responsible for printing
3542     // stack trace if appropriate. Simply exit VM.
3543     vm_exit(1);
3544   }
3545 #endif // INCLUDE_MANAGEMENT
3546 
3547   if (Arguments::has_profile())       FlatProfiler::engage(main_thread, true);
3548   if (MemProfiling)                   MemProfiler::engage();
3549   StatSampler::engage();
3550   if (CheckJNICalls)                  JniPeriodicChecker::engage();
3551 
3552   BiasedLocking::init();
3553 
3554 #if INCLUDE_RTM_OPT
3555   RTMLockingCounters::init();
3556 #endif
3557 
3558   if (JDK_Version::current().post_vm_init_hook_enabled()) {
3559     call_postVMInitHook(THREAD);
3560     // The Java side of PostVMInitHook.run must deal with all
3561     // exceptions and provide means of diagnosis.
3562     if (HAS_PENDING_EXCEPTION) {
3563       CLEAR_PENDING_EXCEPTION;
3564     }
3565   }
3566 
3567   {
3568     MutexLocker ml(PeriodicTask_lock);
3569     // Make sure the WatcherThread can be started by WatcherThread::start()
3570     // or by dynamic enrollment.
3571     WatcherThread::make_startable();
3572     // Start up the WatcherThread if there are any periodic tasks
3573     // NOTE:  All PeriodicTasks should be registered by now. If they
3574     //   aren't, late joiners might appear to start slowly (we might
3575     //   take a while to process their first tick).
3576     if (PeriodicTask::num_tasks() > 0) {
3577       WatcherThread::start();
3578     }
3579   }
3580 
3581   create_vm_timer.end();
3582 #ifdef ASSERT
3583   _vm_complete = true;
3584 #endif
3585   return JNI_OK;
3586 }
3587 
3588 // type for the Agent_OnLoad and JVM_OnLoad entry points
3589 extern "C" {
3590   typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3591 }
3592 // Find a command line agent library and return its entry point for
3593 //         -agentlib:  -agentpath:   -Xrun
3594 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3595 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3596                                     const char *on_load_symbols[],
3597                                     size_t num_symbol_entries) {
3598   OnLoadEntry_t on_load_entry = NULL;
3599   void *library = NULL;
3600 
3601   if (!agent->valid()) {
3602     char buffer[JVM_MAXPATHLEN];
3603     char ebuf[1024] = "";
3604     const char *name = agent->name();
3605     const char *msg = "Could not find agent library ";
3606 
3607     // First check to see if agent is statically linked into executable
3608     if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3609       library = agent->os_lib();
3610     } else if (agent->is_absolute_path()) {
3611       library = os::dll_load(name, ebuf, sizeof ebuf);
3612       if (library == NULL) {
3613         const char *sub_msg = " in absolute path, with error: ";
3614         size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3615         char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3616         jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3617         // If we can't find the agent, exit.
3618         vm_exit_during_initialization(buf, NULL);
3619         FREE_C_HEAP_ARRAY(char, buf);
3620       }
3621     } else {
3622       // Try to load the agent from the standard dll directory
3623       if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(),
3624                              name)) {
3625         library = os::dll_load(buffer, ebuf, sizeof ebuf);
3626       }
3627       if (library == NULL) { // Try the local directory
3628         char ns[1] = {0};
3629         if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) {
3630           library = os::dll_load(buffer, ebuf, sizeof ebuf);
3631         }
3632         if (library == NULL) {
3633           const char *sub_msg = " on the library path, with error: ";
3634           size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3635           char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3636           jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3637           // If we can't find the agent, exit.
3638           vm_exit_during_initialization(buf, NULL);
3639           FREE_C_HEAP_ARRAY(char, buf);
3640         }
3641       }
3642     }
3643     agent->set_os_lib(library);
3644     agent->set_valid();
3645   }
3646 
3647   // Find the OnLoad function.
3648   on_load_entry =
3649     CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
3650                                                           false,
3651                                                           on_load_symbols,
3652                                                           num_symbol_entries));
3653   return on_load_entry;
3654 }
3655 
3656 // Find the JVM_OnLoad entry point
3657 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3658   const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3659   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3660 }
3661 
3662 // Find the Agent_OnLoad entry point
3663 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3664   const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3665   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3666 }
3667 
3668 // For backwards compatibility with -Xrun
3669 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3670 // treated like -agentpath:
3671 // Must be called before agent libraries are created
3672 void Threads::convert_vm_init_libraries_to_agents() {
3673   AgentLibrary* agent;
3674   AgentLibrary* next;
3675 
3676   for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3677     next = agent->next();  // cache the next agent now as this agent may get moved off this list
3678     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3679 
3680     // If there is an JVM_OnLoad function it will get called later,
3681     // otherwise see if there is an Agent_OnLoad
3682     if (on_load_entry == NULL) {
3683       on_load_entry = lookup_agent_on_load(agent);
3684       if (on_load_entry != NULL) {
3685         // switch it to the agent list -- so that Agent_OnLoad will be called,
3686         // JVM_OnLoad won't be attempted and Agent_OnUnload will
3687         Arguments::convert_library_to_agent(agent);
3688       } else {
3689         vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3690       }
3691     }
3692   }
3693 }
3694 
3695 // Create agents for -agentlib:  -agentpath:  and converted -Xrun
3696 // Invokes Agent_OnLoad
3697 // Called very early -- before JavaThreads exist
3698 void Threads::create_vm_init_agents() {
3699   extern struct JavaVM_ main_vm;
3700   AgentLibrary* agent;
3701 
3702   JvmtiExport::enter_onload_phase();
3703 
3704   for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3705     OnLoadEntry_t  on_load_entry = lookup_agent_on_load(agent);
3706 
3707     if (on_load_entry != NULL) {
3708       // Invoke the Agent_OnLoad function
3709       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3710       if (err != JNI_OK) {
3711         vm_exit_during_initialization("agent library failed to init", agent->name());
3712       }
3713     } else {
3714       vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
3715     }
3716   }
3717   JvmtiExport::enter_primordial_phase();
3718 }
3719 
3720 extern "C" {
3721   typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
3722 }
3723 
3724 void Threads::shutdown_vm_agents() {
3725   // Send any Agent_OnUnload notifications
3726   const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
3727   size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
3728   extern struct JavaVM_ main_vm;
3729   for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3730 
3731     // Find the Agent_OnUnload function.
3732     Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
3733                                                    os::find_agent_function(agent,
3734                                                    false,
3735                                                    on_unload_symbols,
3736                                                    num_symbol_entries));
3737 
3738     // Invoke the Agent_OnUnload function
3739     if (unload_entry != NULL) {
3740       JavaThread* thread = JavaThread::current();
3741       ThreadToNativeFromVM ttn(thread);
3742       HandleMark hm(thread);
3743       (*unload_entry)(&main_vm);
3744     }
3745   }
3746 }
3747 
3748 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
3749 // Invokes JVM_OnLoad
3750 void Threads::create_vm_init_libraries() {
3751   extern struct JavaVM_ main_vm;
3752   AgentLibrary* agent;
3753 
3754   for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
3755     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3756 
3757     if (on_load_entry != NULL) {
3758       // Invoke the JVM_OnLoad function
3759       JavaThread* thread = JavaThread::current();
3760       ThreadToNativeFromVM ttn(thread);
3761       HandleMark hm(thread);
3762       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3763       if (err != JNI_OK) {
3764         vm_exit_during_initialization("-Xrun library failed to init", agent->name());
3765       }
3766     } else {
3767       vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
3768     }
3769   }
3770 }
3771 
3772 JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) {
3773   assert(Threads_lock->owned_by_self(), "Must hold Threads_lock");
3774 
3775   JavaThread* java_thread = NULL;
3776   // Sequential search for now.  Need to do better optimization later.
3777   for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) {
3778     oop tobj = thread->threadObj();
3779     if (!thread->is_exiting() &&
3780         tobj != NULL &&
3781         java_tid == java_lang_Thread::thread_id(tobj)) {
3782       java_thread = thread;
3783       break;
3784     }
3785   }
3786   return java_thread;
3787 }
3788 
3789 
3790 // Last thread running calls java.lang.Shutdown.shutdown()
3791 void JavaThread::invoke_shutdown_hooks() {
3792   HandleMark hm(this);
3793 
3794   // We could get here with a pending exception, if so clear it now.
3795   if (this->has_pending_exception()) {
3796     this->clear_pending_exception();
3797   }
3798 
3799   EXCEPTION_MARK;
3800   Klass* k =
3801     SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
3802                                       THREAD);
3803   if (k != NULL) {
3804     // SystemDictionary::resolve_or_null will return null if there was
3805     // an exception.  If we cannot load the Shutdown class, just don't
3806     // call Shutdown.shutdown() at all.  This will mean the shutdown hooks
3807     // and finalizers (if runFinalizersOnExit is set) won't be run.
3808     // Note that if a shutdown hook was registered or runFinalizersOnExit
3809     // was called, the Shutdown class would have already been loaded
3810     // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
3811     instanceKlassHandle shutdown_klass (THREAD, k);
3812     JavaValue result(T_VOID);
3813     JavaCalls::call_static(&result,
3814                            shutdown_klass,
3815                            vmSymbols::shutdown_method_name(),
3816                            vmSymbols::void_method_signature(),
3817                            THREAD);
3818   }
3819   CLEAR_PENDING_EXCEPTION;
3820 }
3821 
3822 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
3823 // the program falls off the end of main(). Another VM exit path is through
3824 // vm_exit() when the program calls System.exit() to return a value or when
3825 // there is a serious error in VM. The two shutdown paths are not exactly
3826 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
3827 // and VM_Exit op at VM level.
3828 //
3829 // Shutdown sequence:
3830 //   + Shutdown native memory tracking if it is on
3831 //   + Wait until we are the last non-daemon thread to execute
3832 //     <-- every thing is still working at this moment -->
3833 //   + Call java.lang.Shutdown.shutdown(), which will invoke Java level
3834 //        shutdown hooks, run finalizers if finalization-on-exit
3835 //   + Call before_exit(), prepare for VM exit
3836 //      > run VM level shutdown hooks (they are registered through JVM_OnExit(),
3837 //        currently the only user of this mechanism is File.deleteOnExit())
3838 //      > stop flat profiler, StatSampler, watcher thread, CMS threads,
3839 //        post thread end and vm death events to JVMTI,
3840 //        stop signal thread
3841 //   + Call JavaThread::exit(), it will:
3842 //      > release JNI handle blocks, remove stack guard pages
3843 //      > remove this thread from Threads list
3844 //     <-- no more Java code from this thread after this point -->
3845 //   + Stop VM thread, it will bring the remaining VM to a safepoint and stop
3846 //     the compiler threads at safepoint
3847 //     <-- do not use anything that could get blocked by Safepoint -->
3848 //   + Disable tracing at JNI/JVM barriers
3849 //   + Set _vm_exited flag for threads that are still running native code
3850 //   + Delete this thread
3851 //   + Call exit_globals()
3852 //      > deletes tty
3853 //      > deletes PerfMemory resources
3854 //   + Return to caller
3855 
3856 bool Threads::destroy_vm() {
3857   JavaThread* thread = JavaThread::current();
3858 
3859 #ifdef ASSERT
3860   _vm_complete = false;
3861 #endif
3862   // Wait until we are the last non-daemon thread to execute
3863   { MutexLocker nu(Threads_lock);
3864     while (Threads::number_of_non_daemon_threads() > 1)
3865       // This wait should make safepoint checks, wait without a timeout,
3866       // and wait as a suspend-equivalent condition.
3867       //
3868       // Note: If the FlatProfiler is running and this thread is waiting
3869       // for another non-daemon thread to finish, then the FlatProfiler
3870       // is waiting for the external suspend request on this thread to
3871       // complete. wait_for_ext_suspend_completion() will eventually
3872       // timeout, but that takes time. Making this wait a suspend-
3873       // equivalent condition solves that timeout problem.
3874       //
3875       Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
3876                          Mutex::_as_suspend_equivalent_flag);
3877   }
3878 
3879   // Hang forever on exit if we are reporting an error.
3880   if (ShowMessageBoxOnError && is_error_reported()) {
3881     os::infinite_sleep();
3882   }
3883   os::wait_for_keypress_at_exit();
3884 
3885   // run Java level shutdown hooks
3886   thread->invoke_shutdown_hooks();
3887 
3888   before_exit(thread);
3889 
3890   thread->exit(true);
3891 
3892   // Stop VM thread.
3893   {
3894     // 4945125 The vm thread comes to a safepoint during exit.
3895     // GC vm_operations can get caught at the safepoint, and the
3896     // heap is unparseable if they are caught. Grab the Heap_lock
3897     // to prevent this. The GC vm_operations will not be able to
3898     // queue until after the vm thread is dead. After this point,
3899     // we'll never emerge out of the safepoint before the VM exits.
3900 
3901     MutexLocker ml(Heap_lock);
3902 
3903     VMThread::wait_for_vm_thread_exit();
3904     assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
3905     VMThread::destroy();
3906   }
3907 
3908   // clean up ideal graph printers
3909 #if defined(COMPILER2) && !defined(PRODUCT)
3910   IdealGraphPrinter::clean_up();
3911 #endif
3912 
3913   // Now, all Java threads are gone except daemon threads. Daemon threads
3914   // running Java code or in VM are stopped by the Safepoint. However,
3915   // daemon threads executing native code are still running.  But they
3916   // will be stopped at native=>Java/VM barriers. Note that we can't
3917   // simply kill or suspend them, as it is inherently deadlock-prone.
3918 
3919 #ifndef PRODUCT
3920   // disable function tracing at JNI/JVM barriers
3921   TraceJNICalls = false;
3922   TraceJVMCalls = false;
3923   TraceRuntimeCalls = false;
3924 #endif
3925 
3926   VM_Exit::set_vm_exited();
3927 
3928   notify_vm_shutdown();
3929 
3930   delete thread;
3931 
3932   // exit_globals() will delete tty
3933   exit_globals();
3934 
3935   return true;
3936 }
3937 
3938 
3939 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
3940   if (version == JNI_VERSION_1_1) return JNI_TRUE;
3941   return is_supported_jni_version(version);
3942 }
3943 
3944 
3945 jboolean Threads::is_supported_jni_version(jint version) {
3946   if (version == JNI_VERSION_1_2) return JNI_TRUE;
3947   if (version == JNI_VERSION_1_4) return JNI_TRUE;
3948   if (version == JNI_VERSION_1_6) return JNI_TRUE;
3949   if (version == JNI_VERSION_1_8) return JNI_TRUE;
3950   return JNI_FALSE;
3951 }
3952 
3953 
3954 void Threads::add(JavaThread* p, bool force_daemon) {
3955   // The threads lock must be owned at this point
3956   assert_locked_or_safepoint(Threads_lock);
3957 
3958   // See the comment for this method in thread.hpp for its purpose and
3959   // why it is called here.
3960   p->initialize_queues();
3961   p->set_next(_thread_list);
3962   _thread_list = p;
3963   _number_of_threads++;
3964   oop threadObj = p->threadObj();
3965   bool daemon = true;
3966   // Bootstrapping problem: threadObj can be null for initial
3967   // JavaThread (or for threads attached via JNI)
3968   if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
3969     _number_of_non_daemon_threads++;
3970     daemon = false;
3971   }
3972 
3973   ThreadService::add_thread(p, daemon);
3974 
3975   // Possible GC point.
3976   Events::log(p, "Thread added: " INTPTR_FORMAT, p);
3977 }
3978 
3979 void Threads::remove(JavaThread* p) {
3980   // Extra scope needed for Thread_lock, so we can check
3981   // that we do not remove thread without safepoint code notice
3982   { MutexLocker ml(Threads_lock);
3983 
3984     assert(includes(p), "p must be present");
3985 
3986     JavaThread* current = _thread_list;
3987     JavaThread* prev    = NULL;
3988 
3989     while (current != p) {
3990       prev    = current;
3991       current = current->next();
3992     }
3993 
3994     if (prev) {
3995       prev->set_next(current->next());
3996     } else {
3997       _thread_list = p->next();
3998     }
3999     _number_of_threads--;
4000     oop threadObj = p->threadObj();
4001     bool daemon = true;
4002     if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4003       _number_of_non_daemon_threads--;
4004       daemon = false;
4005 
4006       // Only one thread left, do a notify on the Threads_lock so a thread waiting
4007       // on destroy_vm will wake up.
4008       if (number_of_non_daemon_threads() == 1) {
4009         Threads_lock->notify_all();
4010       }
4011     }
4012     ThreadService::remove_thread(p, daemon);
4013 
4014     // Make sure that safepoint code disregard this thread. This is needed since
4015     // the thread might mess around with locks after this point. This can cause it
4016     // to do callbacks into the safepoint code. However, the safepoint code is not aware
4017     // of this thread since it is removed from the queue.
4018     p->set_terminated_value();
4019   } // unlock Threads_lock
4020 
4021   // Since Events::log uses a lock, we grab it outside the Threads_lock
4022   Events::log(p, "Thread exited: " INTPTR_FORMAT, p);
4023 }
4024 
4025 // Threads_lock must be held when this is called (or must be called during a safepoint)
4026 bool Threads::includes(JavaThread* p) {
4027   assert(Threads_lock->is_locked(), "sanity check");
4028   ALL_JAVA_THREADS(q) {
4029     if (q == p) {
4030       return true;
4031     }
4032   }
4033   return false;
4034 }
4035 
4036 // Operations on the Threads list for GC.  These are not explicitly locked,
4037 // but the garbage collector must provide a safe context for them to run.
4038 // In particular, these things should never be called when the Threads_lock
4039 // is held by some other thread. (Note: the Safepoint abstraction also
4040 // uses the Threads_lock to guarantee this property. It also makes sure that
4041 // all threads gets blocked when exiting or starting).
4042 
4043 void Threads::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
4044   ALL_JAVA_THREADS(p) {
4045     p->oops_do(f, cld_f, cf);
4046   }
4047   VMThread::vm_thread()->oops_do(f, cld_f, cf);
4048 }
4049 
4050 void Threads::change_thread_claim_parity() {
4051   // Set the new claim parity.
4052   assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4053          "Not in range.");
4054   _thread_claim_parity++;
4055   if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4056   assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4057          "Not in range.");
4058 }
4059 
4060 #ifdef ASSERT
4061 void Threads::assert_all_threads_claimed() {
4062   ALL_JAVA_THREADS(p) {
4063     const int thread_parity = p->oops_do_parity();
4064     assert((thread_parity == _thread_claim_parity),
4065         err_msg("Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity));
4066   }
4067 }
4068 #endif // ASSERT
4069 
4070 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
4071   int cp = Threads::thread_claim_parity();
4072   ALL_JAVA_THREADS(p) {
4073     if (p->claim_oops_do(is_par, cp)) {
4074       p->oops_do(f, cld_f, cf);
4075     }
4076   }
4077   VMThread* vmt = VMThread::vm_thread();
4078   if (vmt->claim_oops_do(is_par, cp)) {
4079     vmt->oops_do(f, cld_f, cf);
4080   }
4081 }
4082 
4083 #if INCLUDE_ALL_GCS
4084 // Used by ParallelScavenge
4085 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4086   ALL_JAVA_THREADS(p) {
4087     q->enqueue(new ThreadRootsTask(p));
4088   }
4089   q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4090 }
4091 
4092 // Used by Parallel Old
4093 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4094   ALL_JAVA_THREADS(p) {
4095     q->enqueue(new ThreadRootsMarkingTask(p));
4096   }
4097   q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4098 }
4099 #endif // INCLUDE_ALL_GCS
4100 
4101 void Threads::nmethods_do(CodeBlobClosure* cf) {
4102   ALL_JAVA_THREADS(p) {
4103     p->nmethods_do(cf);
4104   }
4105   VMThread::vm_thread()->nmethods_do(cf);
4106 }
4107 
4108 void Threads::metadata_do(void f(Metadata*)) {
4109   ALL_JAVA_THREADS(p) {
4110     p->metadata_do(f);
4111   }
4112 }
4113 
4114 class ThreadHandlesClosure : public ThreadClosure {
4115   void (*_f)(Metadata*);
4116  public:
4117   ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4118   virtual void do_thread(Thread* thread) {
4119     thread->metadata_handles_do(_f);
4120   }
4121 };
4122 
4123 void Threads::metadata_handles_do(void f(Metadata*)) {
4124   // Only walk the Handles in Thread.
4125   ThreadHandlesClosure handles_closure(f);
4126   threads_do(&handles_closure);
4127 }
4128 
4129 void Threads::deoptimized_wrt_marked_nmethods() {
4130   ALL_JAVA_THREADS(p) {
4131     p->deoptimized_wrt_marked_nmethods();
4132   }
4133 }
4134 
4135 
4136 // Get count Java threads that are waiting to enter the specified monitor.
4137 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
4138                                                          address monitor,
4139                                                          bool doLock) {
4140   assert(doLock || SafepointSynchronize::is_at_safepoint(),
4141          "must grab Threads_lock or be at safepoint");
4142   GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4143 
4144   int i = 0;
4145   {
4146     MutexLockerEx ml(doLock ? Threads_lock : NULL);
4147     ALL_JAVA_THREADS(p) {
4148       if (p->is_Compiler_thread()) continue;
4149 
4150       address pending = (address)p->current_pending_monitor();
4151       if (pending == monitor) {             // found a match
4152         if (i < count) result->append(p);   // save the first count matches
4153         i++;
4154       }
4155     }
4156   }
4157   return result;
4158 }
4159 
4160 
4161 JavaThread *Threads::owning_thread_from_monitor_owner(address owner,
4162                                                       bool doLock) {
4163   assert(doLock ||
4164          Threads_lock->owned_by_self() ||
4165          SafepointSynchronize::is_at_safepoint(),
4166          "must grab Threads_lock or be at safepoint");
4167 
4168   // NULL owner means not locked so we can skip the search
4169   if (owner == NULL) return NULL;
4170 
4171   {
4172     MutexLockerEx ml(doLock ? Threads_lock : NULL);
4173     ALL_JAVA_THREADS(p) {
4174       // first, see if owner is the address of a Java thread
4175       if (owner == (address)p) return p;
4176     }
4177   }
4178   // Cannot assert on lack of success here since this function may be
4179   // used by code that is trying to report useful problem information
4180   // like deadlock detection.
4181   if (UseHeavyMonitors) return NULL;
4182 
4183   // If we didn't find a matching Java thread and we didn't force use of
4184   // heavyweight monitors, then the owner is the stack address of the
4185   // Lock Word in the owning Java thread's stack.
4186   //
4187   JavaThread* the_owner = NULL;
4188   {
4189     MutexLockerEx ml(doLock ? Threads_lock : NULL);
4190     ALL_JAVA_THREADS(q) {
4191       if (q->is_lock_owned(owner)) {
4192         the_owner = q;
4193         break;
4194       }
4195     }
4196   }
4197   // cannot assert on lack of success here; see above comment
4198   return the_owner;
4199 }
4200 
4201 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4202 void Threads::print_on(outputStream* st, bool print_stacks,
4203                        bool internal_format, bool print_concurrent_locks) {
4204   char buf[32];
4205   st->print_cr("%s", os::local_time_string(buf, sizeof(buf)));
4206 
4207   st->print_cr("Full thread dump %s (%s %s):",
4208                Abstract_VM_Version::vm_name(),
4209                Abstract_VM_Version::vm_release(),
4210                Abstract_VM_Version::vm_info_string());
4211   st->cr();
4212 
4213 #if INCLUDE_SERVICES
4214   // Dump concurrent locks
4215   ConcurrentLocksDump concurrent_locks;
4216   if (print_concurrent_locks) {
4217     concurrent_locks.dump_at_safepoint();
4218   }
4219 #endif // INCLUDE_SERVICES
4220 
4221   ALL_JAVA_THREADS(p) {
4222     ResourceMark rm;
4223     p->print_on(st);
4224     if (print_stacks) {
4225       if (internal_format) {
4226         p->trace_stack();
4227       } else {
4228         p->print_stack_on(st);
4229       }
4230     }
4231     st->cr();
4232 #if INCLUDE_SERVICES
4233     if (print_concurrent_locks) {
4234       concurrent_locks.print_locks_on(p, st);
4235     }
4236 #endif // INCLUDE_SERVICES
4237   }
4238 
4239   VMThread::vm_thread()->print_on(st);
4240   st->cr();
4241   Universe::heap()->print_gc_threads_on(st);
4242   WatcherThread* wt = WatcherThread::watcher_thread();
4243   if (wt != NULL) {
4244     wt->print_on(st);
4245     st->cr();
4246   }
4247   CompileBroker::print_compiler_threads_on(st);
4248   st->flush();
4249 }
4250 
4251 // Threads::print_on_error() is called by fatal error handler. It's possible
4252 // that VM is not at safepoint and/or current thread is inside signal handler.
4253 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4254 // memory (even in resource area), it might deadlock the error handler.
4255 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4256                              int buflen) {
4257   bool found_current = false;
4258   st->print_cr("Java Threads: ( => current thread )");
4259   ALL_JAVA_THREADS(thread) {
4260     bool is_current = (current == thread);
4261     found_current = found_current || is_current;
4262 
4263     st->print("%s", is_current ? "=>" : "  ");
4264 
4265     st->print(PTR_FORMAT, thread);
4266     st->print(" ");
4267     thread->print_on_error(st, buf, buflen);
4268     st->cr();
4269   }
4270   st->cr();
4271 
4272   st->print_cr("Other Threads:");
4273   if (VMThread::vm_thread()) {
4274     bool is_current = (current == VMThread::vm_thread());
4275     found_current = found_current || is_current;
4276     st->print("%s", current == VMThread::vm_thread() ? "=>" : "  ");
4277 
4278     st->print(PTR_FORMAT, VMThread::vm_thread());
4279     st->print(" ");
4280     VMThread::vm_thread()->print_on_error(st, buf, buflen);
4281     st->cr();
4282   }
4283   WatcherThread* wt = WatcherThread::watcher_thread();
4284   if (wt != NULL) {
4285     bool is_current = (current == wt);
4286     found_current = found_current || is_current;
4287     st->print("%s", is_current ? "=>" : "  ");
4288 
4289     st->print(PTR_FORMAT, wt);
4290     st->print(" ");
4291     wt->print_on_error(st, buf, buflen);
4292     st->cr();
4293   }
4294   if (!found_current) {
4295     st->cr();
4296     st->print("=>" PTR_FORMAT " (exited) ", current);
4297     current->print_on_error(st, buf, buflen);
4298     st->cr();
4299   }
4300 }
4301 
4302 // Internal SpinLock and Mutex
4303 // Based on ParkEvent
4304 
4305 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4306 //
4307 // We employ SpinLocks _only for low-contention, fixed-length
4308 // short-duration critical sections where we're concerned
4309 // about native mutex_t or HotSpot Mutex:: latency.
4310 // The mux construct provides a spin-then-block mutual exclusion
4311 // mechanism.
4312 //
4313 // Testing has shown that contention on the ListLock guarding gFreeList
4314 // is common.  If we implement ListLock as a simple SpinLock it's common
4315 // for the JVM to devolve to yielding with little progress.  This is true
4316 // despite the fact that the critical sections protected by ListLock are
4317 // extremely short.
4318 //
4319 // TODO-FIXME: ListLock should be of type SpinLock.
4320 // We should make this a 1st-class type, integrated into the lock
4321 // hierarchy as leaf-locks.  Critically, the SpinLock structure
4322 // should have sufficient padding to avoid false-sharing and excessive
4323 // cache-coherency traffic.
4324 
4325 
4326 typedef volatile int SpinLockT;
4327 
4328 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4329   if (Atomic::cmpxchg (1, adr, 0) == 0) {
4330     return;   // normal fast-path return
4331   }
4332 
4333   // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4334   TEVENT(SpinAcquire - ctx);
4335   int ctr = 0;
4336   int Yields = 0;
4337   for (;;) {
4338     while (*adr != 0) {
4339       ++ctr;
4340       if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4341         if (Yields > 5) {
4342           os::naked_short_sleep(1);
4343         } else {
4344           os::naked_yield();
4345           ++Yields;
4346         }
4347       } else {
4348         SpinPause();
4349       }
4350     }
4351     if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4352   }
4353 }
4354 
4355 void Thread::SpinRelease(volatile int * adr) {
4356   assert(*adr != 0, "invariant");
4357   OrderAccess::fence();      // guarantee at least release consistency.
4358   // Roach-motel semantics.
4359   // It's safe if subsequent LDs and STs float "up" into the critical section,
4360   // but prior LDs and STs within the critical section can't be allowed
4361   // to reorder or float past the ST that releases the lock.
4362   // Loads and stores in the critical section - which appear in program
4363   // order before the store that releases the lock - must also appear
4364   // before the store that releases the lock in memory visibility order.
4365   // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4366   // the ST of 0 into the lock-word which releases the lock, so fence
4367   // more than covers this on all platforms.
4368   *adr = 0;
4369 }
4370 
4371 // muxAcquire and muxRelease:
4372 //
4373 // *  muxAcquire and muxRelease support a single-word lock-word construct.
4374 //    The LSB of the word is set IFF the lock is held.
4375 //    The remainder of the word points to the head of a singly-linked list
4376 //    of threads blocked on the lock.
4377 //
4378 // *  The current implementation of muxAcquire-muxRelease uses its own
4379 //    dedicated Thread._MuxEvent instance.  If we're interested in
4380 //    minimizing the peak number of extant ParkEvent instances then
4381 //    we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4382 //    as certain invariants were satisfied.  Specifically, care would need
4383 //    to be taken with regards to consuming unpark() "permits".
4384 //    A safe rule of thumb is that a thread would never call muxAcquire()
4385 //    if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4386 //    park().  Otherwise the _ParkEvent park() operation in muxAcquire() could
4387 //    consume an unpark() permit intended for monitorenter, for instance.
4388 //    One way around this would be to widen the restricted-range semaphore
4389 //    implemented in park().  Another alternative would be to provide
4390 //    multiple instances of the PlatformEvent() for each thread.  One
4391 //    instance would be dedicated to muxAcquire-muxRelease, for instance.
4392 //
4393 // *  Usage:
4394 //    -- Only as leaf locks
4395 //    -- for short-term locking only as muxAcquire does not perform
4396 //       thread state transitions.
4397 //
4398 // Alternatives:
4399 // *  We could implement muxAcquire and muxRelease with MCS or CLH locks
4400 //    but with parking or spin-then-park instead of pure spinning.
4401 // *  Use Taura-Oyama-Yonenzawa locks.
4402 // *  It's possible to construct a 1-0 lock if we encode the lockword as
4403 //    (List,LockByte).  Acquire will CAS the full lockword while Release
4404 //    will STB 0 into the LockByte.  The 1-0 scheme admits stranding, so
4405 //    acquiring threads use timers (ParkTimed) to detect and recover from
4406 //    the stranding window.  Thread/Node structures must be aligned on 256-byte
4407 //    boundaries by using placement-new.
4408 // *  Augment MCS with advisory back-link fields maintained with CAS().
4409 //    Pictorially:  LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4410 //    The validity of the backlinks must be ratified before we trust the value.
4411 //    If the backlinks are invalid the exiting thread must back-track through the
4412 //    the forward links, which are always trustworthy.
4413 // *  Add a successor indication.  The LockWord is currently encoded as
4414 //    (List, LOCKBIT:1).  We could also add a SUCCBIT or an explicit _succ variable
4415 //    to provide the usual futile-wakeup optimization.
4416 //    See RTStt for details.
4417 // *  Consider schedctl.sc_nopreempt to cover the critical section.
4418 //
4419 
4420 
4421 typedef volatile intptr_t MutexT;      // Mux Lock-word
4422 enum MuxBits { LOCKBIT = 1 };
4423 
4424 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4425   intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4426   if (w == 0) return;
4427   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4428     return;
4429   }
4430 
4431   TEVENT(muxAcquire - Contention);
4432   ParkEvent * const Self = Thread::current()->_MuxEvent;
4433   assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4434   for (;;) {
4435     int its = (os::is_MP() ? 100 : 0) + 1;
4436 
4437     // Optional spin phase: spin-then-park strategy
4438     while (--its >= 0) {
4439       w = *Lock;
4440       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4441         return;
4442       }
4443     }
4444 
4445     Self->reset();
4446     Self->OnList = intptr_t(Lock);
4447     // The following fence() isn't _strictly necessary as the subsequent
4448     // CAS() both serializes execution and ratifies the fetched *Lock value.
4449     OrderAccess::fence();
4450     for (;;) {
4451       w = *Lock;
4452       if ((w & LOCKBIT) == 0) {
4453         if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4454           Self->OnList = 0;   // hygiene - allows stronger asserts
4455           return;
4456         }
4457         continue;      // Interference -- *Lock changed -- Just retry
4458       }
4459       assert(w & LOCKBIT, "invariant");
4460       Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4461       if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4462     }
4463 
4464     while (Self->OnList != 0) {
4465       Self->park();
4466     }
4467   }
4468 }
4469 
4470 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4471   intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4472   if (w == 0) return;
4473   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4474     return;
4475   }
4476 
4477   TEVENT(muxAcquire - Contention);
4478   ParkEvent * ReleaseAfter = NULL;
4479   if (ev == NULL) {
4480     ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4481   }
4482   assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4483   for (;;) {
4484     guarantee(ev->OnList == 0, "invariant");
4485     int its = (os::is_MP() ? 100 : 0) + 1;
4486 
4487     // Optional spin phase: spin-then-park strategy
4488     while (--its >= 0) {
4489       w = *Lock;
4490       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4491         if (ReleaseAfter != NULL) {
4492           ParkEvent::Release(ReleaseAfter);
4493         }
4494         return;
4495       }
4496     }
4497 
4498     ev->reset();
4499     ev->OnList = intptr_t(Lock);
4500     // The following fence() isn't _strictly necessary as the subsequent
4501     // CAS() both serializes execution and ratifies the fetched *Lock value.
4502     OrderAccess::fence();
4503     for (;;) {
4504       w = *Lock;
4505       if ((w & LOCKBIT) == 0) {
4506         if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4507           ev->OnList = 0;
4508           // We call ::Release while holding the outer lock, thus
4509           // artificially lengthening the critical section.
4510           // Consider deferring the ::Release() until the subsequent unlock(),
4511           // after we've dropped the outer lock.
4512           if (ReleaseAfter != NULL) {
4513             ParkEvent::Release(ReleaseAfter);
4514           }
4515           return;
4516         }
4517         continue;      // Interference -- *Lock changed -- Just retry
4518       }
4519       assert(w & LOCKBIT, "invariant");
4520       ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4521       if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4522     }
4523 
4524     while (ev->OnList != 0) {
4525       ev->park();
4526     }
4527   }
4528 }
4529 
4530 // Release() must extract a successor from the list and then wake that thread.
4531 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4532 // similar to that used by ParkEvent::Allocate() and ::Release().  DMR-based
4533 // Release() would :
4534 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4535 // (B) Extract a successor from the private list "in-hand"
4536 // (C) attempt to CAS() the residual back into *Lock over null.
4537 //     If there were any newly arrived threads and the CAS() would fail.
4538 //     In that case Release() would detach the RATs, re-merge the list in-hand
4539 //     with the RATs and repeat as needed.  Alternately, Release() might
4540 //     detach and extract a successor, but then pass the residual list to the wakee.
4541 //     The wakee would be responsible for reattaching and remerging before it
4542 //     competed for the lock.
4543 //
4544 // Both "pop" and DMR are immune from ABA corruption -- there can be
4545 // multiple concurrent pushers, but only one popper or detacher.
4546 // This implementation pops from the head of the list.  This is unfair,
4547 // but tends to provide excellent throughput as hot threads remain hot.
4548 // (We wake recently run threads first).
4549 //
4550 // All paths through muxRelease() will execute a CAS.
4551 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4552 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4553 // executed within the critical section are complete and globally visible before the
4554 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4555 void Thread::muxRelease(volatile intptr_t * Lock)  {
4556   for (;;) {
4557     const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT);
4558     assert(w & LOCKBIT, "invariant");
4559     if (w == LOCKBIT) return;
4560     ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4561     assert(List != NULL, "invariant");
4562     assert(List->OnList == intptr_t(Lock), "invariant");
4563     ParkEvent * const nxt = List->ListNext;
4564     guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4565 
4566     // The following CAS() releases the lock and pops the head element.
4567     // The CAS() also ratifies the previously fetched lock-word value.
4568     if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4569       continue;
4570     }
4571     List->OnList = 0;
4572     OrderAccess::fence();
4573     List->unpark();
4574     return;
4575   }
4576 }
4577 
4578 
4579 void Threads::verify() {
4580   ALL_JAVA_THREADS(p) {
4581     p->verify();
4582   }
4583   VMThread* thread = VMThread::vm_thread();
4584   if (thread != NULL) thread->verify();
4585 }
--- EOF ---