1 /*
   2  * Copyright (c) 1997, 2014, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "classfile/classLoader.hpp"
  27 #include "classfile/javaClasses.hpp"
  28 #include "classfile/systemDictionary.hpp"
  29 #include "classfile/vmSymbols.hpp"
  30 #include "code/codeCache.hpp"
  31 #include "code/scopeDesc.hpp"
  32 #include "compiler/compileBroker.hpp"
  33 #include "interpreter/interpreter.hpp"
  34 #include "interpreter/linkResolver.hpp"
  35 #include "interpreter/oopMapCache.hpp"
  36 #include "jvmtifiles/jvmtiEnv.hpp"
  37 #include "memory/gcLocker.inline.hpp"
  38 #include "memory/metaspaceShared.hpp"
  39 #include "memory/oopFactory.hpp"
  40 #include "memory/universe.inline.hpp"
  41 #include "oops/instanceKlass.hpp"
  42 #include "oops/objArrayOop.hpp"
  43 #include "oops/oop.inline.hpp"
  44 #include "oops/symbol.hpp"
  45 #include "prims/jvm_misc.hpp"
  46 #include "prims/jvmtiExport.hpp"
  47 #include "prims/jvmtiThreadState.hpp"
  48 #include "prims/privilegedStack.hpp"
  49 #include "runtime/arguments.hpp"
  50 #include "runtime/atomic.inline.hpp"
  51 #include "runtime/biasedLocking.hpp"
  52 #include "runtime/deoptimization.hpp"
  53 #include "runtime/fprofiler.hpp"
  54 #include "runtime/frame.inline.hpp"
  55 #include "runtime/init.hpp"
  56 #include "runtime/interfaceSupport.hpp"
  57 #include "runtime/java.hpp"
  58 #include "runtime/javaCalls.hpp"
  59 #include "runtime/jniPeriodicChecker.hpp"
  60 #include "runtime/memprofiler.hpp"
  61 #include "runtime/mutexLocker.hpp"
  62 #include "runtime/objectMonitor.hpp"
  63 #include "runtime/orderAccess.inline.hpp"
  64 #include "runtime/osThread.hpp"
  65 #include "runtime/safepoint.hpp"
  66 #include "runtime/sharedRuntime.hpp"
  67 #include "runtime/statSampler.hpp"
  68 #include "runtime/stubRoutines.hpp"
  69 #include "runtime/task.hpp"
  70 #include "runtime/thread.inline.hpp"
  71 #include "runtime/threadCritical.hpp"
  72 #include "runtime/threadLocalStorage.hpp"
  73 #include "runtime/vframe.hpp"
  74 #include "runtime/vframeArray.hpp"
  75 #include "runtime/vframe_hp.hpp"
  76 #include "runtime/vmThread.hpp"
  77 #include "runtime/vm_operations.hpp"
  78 #include "runtime/vm_version.hpp"
  79 #include "services/attachListener.hpp"
  80 #include "services/management.hpp"
  81 #include "services/memTracker.hpp"
  82 #include "services/threadService.hpp"
  83 #include "trace/tracing.hpp"
  84 #include "trace/traceMacros.hpp"
  85 #include "utilities/defaultStream.hpp"
  86 #include "utilities/dtrace.hpp"
  87 #include "utilities/events.hpp"
  88 #include "utilities/preserveException.hpp"
  89 #include "utilities/macros.hpp"
  90 #if INCLUDE_ALL_GCS
  91 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp"
  92 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
  93 #include "gc_implementation/parallelScavenge/pcTasks.hpp"
  94 #endif // INCLUDE_ALL_GCS
  95 #ifdef COMPILER1
  96 #include "c1/c1_Compiler.hpp"
  97 #endif
  98 #ifdef COMPILER2
  99 #include "opto/c2compiler.hpp"
 100 #include "opto/idealGraphPrinter.hpp"
 101 #endif
 102 #if INCLUDE_RTM_OPT
 103 #include "runtime/rtmLocking.hpp"
 104 #endif
 105 
 106 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
 107 
 108 #ifdef DTRACE_ENABLED
 109 
 110 // Only bother with this argument setup if dtrace is available
 111 
 112   #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
 113   #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
 114 
 115   #define DTRACE_THREAD_PROBE(probe, javathread)                           \
 116     {                                                                      \
 117       ResourceMark rm(this);                                               \
 118       int len = 0;                                                         \
 119       const char* name = (javathread)->get_thread_name();                  \
 120       len = strlen(name);                                                  \
 121       HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */               \
 122         (char *) name, len,                                                \
 123         java_lang_Thread::thread_id((javathread)->threadObj()),            \
 124         (uintptr_t) (javathread)->osthread()->thread_id(),                 \
 125         java_lang_Thread::is_daemon((javathread)->threadObj()));           \
 126     }
 127 
 128 #else //  ndef DTRACE_ENABLED
 129 
 130   #define DTRACE_THREAD_PROBE(probe, javathread)
 131 
 132 #endif // ndef DTRACE_ENABLED
 133 
 134 
 135 // Class hierarchy
 136 // - Thread
 137 //   - VMThread
 138 //   - WatcherThread
 139 //   - ConcurrentMarkSweepThread
 140 //   - JavaThread
 141 //     - CompilerThread
 142 
 143 // ======= Thread ========
 144 // Support for forcing alignment of thread objects for biased locking
 145 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
 146   if (UseBiasedLocking) {
 147     const int alignment = markOopDesc::biased_lock_alignment;
 148     size_t aligned_size = size + (alignment - sizeof(intptr_t));
 149     void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
 150                                           : AllocateHeap(aligned_size, flags, CURRENT_PC,
 151                                                          AllocFailStrategy::RETURN_NULL);
 152     void* aligned_addr     = (void*) align_size_up((intptr_t) real_malloc_addr, alignment);
 153     assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
 154            ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
 155            "JavaThread alignment code overflowed allocated storage");
 156     if (TraceBiasedLocking) {
 157       if (aligned_addr != real_malloc_addr) {
 158         tty->print_cr("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
 159                       real_malloc_addr, aligned_addr);
 160       }
 161     }
 162     ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
 163     return aligned_addr;
 164   } else {
 165     return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
 166                        : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
 167   }
 168 }
 169 
 170 void Thread::operator delete(void* p) {
 171   if (UseBiasedLocking) {
 172     void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;
 173     FreeHeap(real_malloc_addr, mtThread);
 174   } else {
 175     FreeHeap(p, mtThread);
 176   }
 177 }
 178 
 179 
 180 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
 181 // JavaThread
 182 
 183 
 184 Thread::Thread() {
 185   // stack and get_thread
 186   set_stack_base(NULL);
 187   set_stack_size(0);
 188   set_self_raw_id(0);
 189   set_lgrp_id(-1);
 190 
 191   // allocated data structures
 192   set_osthread(NULL);
 193   set_resource_area(new (mtThread)ResourceArea());
 194   DEBUG_ONLY(_current_resource_mark = NULL;)
 195   set_handle_area(new (mtThread) HandleArea(NULL));
 196   set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
 197   set_active_handles(NULL);
 198   set_free_handle_block(NULL);
 199   set_last_handle_mark(NULL);
 200 
 201   // This initial value ==> never claimed.
 202   _oops_do_parity = 0;
 203 
 204   _metadata_on_stack_buffer = NULL;
 205 
 206   // the handle mark links itself to last_handle_mark
 207   new HandleMark(this);
 208 
 209   // plain initialization
 210   debug_only(_owned_locks = NULL;)
 211   debug_only(_allow_allocation_count = 0;)
 212   NOT_PRODUCT(_allow_safepoint_count = 0;)
 213   NOT_PRODUCT(_skip_gcalot = false;)
 214   _jvmti_env_iteration_count = 0;
 215   set_allocated_bytes(0);
 216   _vm_operation_started_count = 0;
 217   _vm_operation_completed_count = 0;
 218   _current_pending_monitor = NULL;
 219   _current_pending_monitor_is_from_java = true;
 220   _current_waiting_monitor = NULL;
 221   _num_nested_signal = 0;
 222   omFreeList = NULL;
 223   omFreeCount = 0;
 224   omFreeProvision = 32;
 225   omInUseList = NULL;
 226   omInUseCount = 0;
 227 
 228 #ifdef ASSERT
 229   _visited_for_critical_count = false;
 230 #endif
 231 
 232   _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true);
 233   _suspend_flags = 0;
 234 
 235   // thread-specific hashCode stream generator state - Marsaglia shift-xor form
 236   _hashStateX = os::random();
 237   _hashStateY = 842502087;
 238   _hashStateZ = 0x8767;    // (int)(3579807591LL & 0xffff) ;
 239   _hashStateW = 273326509;
 240 
 241   _OnTrap   = 0;
 242   _schedctl = NULL;
 243   _Stalled  = 0;
 244   _TypeTag  = 0x2BAD;
 245 
 246   // Many of the following fields are effectively final - immutable
 247   // Note that nascent threads can't use the Native Monitor-Mutex
 248   // construct until the _MutexEvent is initialized ...
 249   // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
 250   // we might instead use a stack of ParkEvents that we could provision on-demand.
 251   // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
 252   // and ::Release()
 253   _ParkEvent   = ParkEvent::Allocate(this);
 254   _SleepEvent  = ParkEvent::Allocate(this);
 255   _MutexEvent  = ParkEvent::Allocate(this);
 256   _MuxEvent    = ParkEvent::Allocate(this);
 257 
 258 #ifdef CHECK_UNHANDLED_OOPS
 259   if (CheckUnhandledOops) {
 260     _unhandled_oops = new UnhandledOops(this);
 261   }
 262 #endif // CHECK_UNHANDLED_OOPS
 263 #ifdef ASSERT
 264   if (UseBiasedLocking) {
 265     assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
 266     assert(this == _real_malloc_address ||
 267            this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment),
 268            "bug in forced alignment of thread objects");
 269   }
 270 #endif // ASSERT
 271 }
 272 
 273 void Thread::initialize_thread_local_storage() {
 274   // Note: Make sure this method only calls
 275   // non-blocking operations. Otherwise, it might not work
 276   // with the thread-startup/safepoint interaction.
 277 
 278   // During Java thread startup, safepoint code should allow this
 279   // method to complete because it may need to allocate memory to
 280   // store information for the new thread.
 281 
 282   // initialize structure dependent on thread local storage
 283   ThreadLocalStorage::set_thread(this);
 284 }
 285 
 286 void Thread::record_stack_base_and_size() {
 287   set_stack_base(os::current_stack_base());
 288   set_stack_size(os::current_stack_size());
 289   if (is_Java_thread()) {
 290     ((JavaThread*) this)->set_stack_overflow_limit();
 291   }
 292   // CR 7190089: on Solaris, primordial thread's stack is adjusted
 293   // in initialize_thread(). Without the adjustment, stack size is
 294   // incorrect if stack is set to unlimited (ulimit -s unlimited).
 295   // So far, only Solaris has real implementation of initialize_thread().
 296   //
 297   // set up any platform-specific state.
 298   os::initialize_thread(this);
 299 
 300 #if INCLUDE_NMT
 301   // record thread's native stack, stack grows downward
 302   address stack_low_addr = stack_base() - stack_size();
 303   MemTracker::record_thread_stack(stack_low_addr, stack_size());
 304 #endif // INCLUDE_NMT
 305 }
 306 
 307 
 308 Thread::~Thread() {
 309   // Reclaim the objectmonitors from the omFreeList of the moribund thread.
 310   ObjectSynchronizer::omFlush(this);
 311 
 312   EVENT_THREAD_DESTRUCT(this);
 313 
 314   // stack_base can be NULL if the thread is never started or exited before
 315   // record_stack_base_and_size called. Although, we would like to ensure
 316   // that all started threads do call record_stack_base_and_size(), there is
 317   // not proper way to enforce that.
 318 #if INCLUDE_NMT
 319   if (_stack_base != NULL) {
 320     address low_stack_addr = stack_base() - stack_size();
 321     MemTracker::release_thread_stack(low_stack_addr, stack_size());
 322 #ifdef ASSERT
 323     set_stack_base(NULL);
 324 #endif
 325   }
 326 #endif // INCLUDE_NMT
 327 
 328   // deallocate data structures
 329   delete resource_area();
 330   // since the handle marks are using the handle area, we have to deallocated the root
 331   // handle mark before deallocating the thread's handle area,
 332   assert(last_handle_mark() != NULL, "check we have an element");
 333   delete last_handle_mark();
 334   assert(last_handle_mark() == NULL, "check we have reached the end");
 335 
 336   // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
 337   // We NULL out the fields for good hygiene.
 338   ParkEvent::Release(_ParkEvent); _ParkEvent   = NULL;
 339   ParkEvent::Release(_SleepEvent); _SleepEvent  = NULL;
 340   ParkEvent::Release(_MutexEvent); _MutexEvent  = NULL;
 341   ParkEvent::Release(_MuxEvent); _MuxEvent    = NULL;
 342 
 343   delete handle_area();
 344   delete metadata_handles();
 345 
 346   // osthread() can be NULL, if creation of thread failed.
 347   if (osthread() != NULL) os::free_thread(osthread());
 348 
 349   delete _SR_lock;
 350 
 351   // clear thread local storage if the Thread is deleting itself
 352   if (this == Thread::current()) {
 353     ThreadLocalStorage::set_thread(NULL);
 354   } else {
 355     // In the case where we're not the current thread, invalidate all the
 356     // caches in case some code tries to get the current thread or the
 357     // thread that was destroyed, and gets stale information.
 358     ThreadLocalStorage::invalidate_all();
 359   }
 360   CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
 361 }
 362 
 363 // NOTE: dummy function for assertion purpose.
 364 void Thread::run() {
 365   ShouldNotReachHere();
 366 }
 367 
 368 #ifdef ASSERT
 369 // Private method to check for dangling thread pointer
 370 void check_for_dangling_thread_pointer(Thread *thread) {
 371   assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
 372          "possibility of dangling Thread pointer");
 373 }
 374 #endif
 375 
 376 
 377 #ifndef PRODUCT
 378 // Tracing method for basic thread operations
 379 void Thread::trace(const char* msg, const Thread* const thread) {
 380   if (!TraceThreadEvents) return;
 381   ResourceMark rm;
 382   ThreadCritical tc;
 383   const char *name = "non-Java thread";
 384   int prio = -1;
 385   if (thread->is_Java_thread()
 386       && !thread->is_Compiler_thread()) {
 387     // The Threads_lock must be held to get information about
 388     // this thread but may not be in some situations when
 389     // tracing  thread events.
 390     bool release_Threads_lock = false;
 391     if (!Threads_lock->owned_by_self()) {
 392       Threads_lock->lock();
 393       release_Threads_lock = true;
 394     }
 395     JavaThread* jt = (JavaThread *)thread;
 396     name = (char *)jt->get_thread_name();
 397     oop thread_oop = jt->threadObj();
 398     if (thread_oop != NULL) {
 399       prio = java_lang_Thread::priority(thread_oop);
 400     }
 401     if (release_Threads_lock) {
 402       Threads_lock->unlock();
 403     }
 404   }
 405   tty->print_cr("Thread::%s " INTPTR_FORMAT " [%lx] %s (prio: %d)", msg, thread, thread->osthread()->thread_id(), name, prio);
 406 }
 407 #endif
 408 
 409 
 410 ThreadPriority Thread::get_priority(const Thread* const thread) {
 411   trace("get priority", thread);
 412   ThreadPriority priority;
 413   // Can return an error!
 414   (void)os::get_priority(thread, priority);
 415   assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
 416   return priority;
 417 }
 418 
 419 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
 420   trace("set priority", thread);
 421   debug_only(check_for_dangling_thread_pointer(thread);)
 422   // Can return an error!
 423   (void)os::set_priority(thread, priority);
 424 }
 425 
 426 
 427 void Thread::start(Thread* thread) {
 428   trace("start", thread);
 429   // Start is different from resume in that its safety is guaranteed by context or
 430   // being called from a Java method synchronized on the Thread object.
 431   if (!DisableStartThread) {
 432     if (thread->is_Java_thread()) {
 433       // Initialize the thread state to RUNNABLE before starting this thread.
 434       // Can not set it after the thread started because we do not know the
 435       // exact thread state at that time. It could be in MONITOR_WAIT or
 436       // in SLEEPING or some other state.
 437       java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
 438                                           java_lang_Thread::RUNNABLE);
 439     }
 440     os::start_thread(thread);
 441   }
 442 }
 443 
 444 // Enqueue a VM_Operation to do the job for us - sometime later
 445 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
 446   VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
 447   VMThread::execute(vm_stop);
 448 }
 449 
 450 
 451 // Check if an external suspend request has completed (or has been
 452 // cancelled). Returns true if the thread is externally suspended and
 453 // false otherwise.
 454 //
 455 // The bits parameter returns information about the code path through
 456 // the routine. Useful for debugging:
 457 //
 458 // set in is_ext_suspend_completed():
 459 // 0x00000001 - routine was entered
 460 // 0x00000010 - routine return false at end
 461 // 0x00000100 - thread exited (return false)
 462 // 0x00000200 - suspend request cancelled (return false)
 463 // 0x00000400 - thread suspended (return true)
 464 // 0x00001000 - thread is in a suspend equivalent state (return true)
 465 // 0x00002000 - thread is native and walkable (return true)
 466 // 0x00004000 - thread is native_trans and walkable (needed retry)
 467 //
 468 // set in wait_for_ext_suspend_completion():
 469 // 0x00010000 - routine was entered
 470 // 0x00020000 - suspend request cancelled before loop (return false)
 471 // 0x00040000 - thread suspended before loop (return true)
 472 // 0x00080000 - suspend request cancelled in loop (return false)
 473 // 0x00100000 - thread suspended in loop (return true)
 474 // 0x00200000 - suspend not completed during retry loop (return false)
 475 
 476 // Helper class for tracing suspend wait debug bits.
 477 //
 478 // 0x00000100 indicates that the target thread exited before it could
 479 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
 480 // 0x00080000 each indicate a cancelled suspend request so they don't
 481 // count as wait failures either.
 482 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
 483 
 484 class TraceSuspendDebugBits : public StackObj {
 485  private:
 486   JavaThread * jt;
 487   bool         is_wait;
 488   bool         called_by_wait;  // meaningful when !is_wait
 489   uint32_t *   bits;
 490 
 491  public:
 492   TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
 493                         uint32_t *_bits) {
 494     jt             = _jt;
 495     is_wait        = _is_wait;
 496     called_by_wait = _called_by_wait;
 497     bits           = _bits;
 498   }
 499 
 500   ~TraceSuspendDebugBits() {
 501     if (!is_wait) {
 502 #if 1
 503       // By default, don't trace bits for is_ext_suspend_completed() calls.
 504       // That trace is very chatty.
 505       return;
 506 #else
 507       if (!called_by_wait) {
 508         // If tracing for is_ext_suspend_completed() is enabled, then only
 509         // trace calls to it from wait_for_ext_suspend_completion()
 510         return;
 511       }
 512 #endif
 513     }
 514 
 515     if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
 516       if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
 517         MutexLocker ml(Threads_lock);  // needed for get_thread_name()
 518         ResourceMark rm;
 519 
 520         tty->print_cr(
 521                       "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
 522                       jt->get_thread_name(), *bits);
 523 
 524         guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
 525       }
 526     }
 527   }
 528 };
 529 #undef DEBUG_FALSE_BITS
 530 
 531 
 532 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
 533                                           uint32_t *bits) {
 534   TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
 535 
 536   bool did_trans_retry = false;  // only do thread_in_native_trans retry once
 537   bool do_trans_retry;           // flag to force the retry
 538 
 539   *bits |= 0x00000001;
 540 
 541   do {
 542     do_trans_retry = false;
 543 
 544     if (is_exiting()) {
 545       // Thread is in the process of exiting. This is always checked
 546       // first to reduce the risk of dereferencing a freed JavaThread.
 547       *bits |= 0x00000100;
 548       return false;
 549     }
 550 
 551     if (!is_external_suspend()) {
 552       // Suspend request is cancelled. This is always checked before
 553       // is_ext_suspended() to reduce the risk of a rogue resume
 554       // confusing the thread that made the suspend request.
 555       *bits |= 0x00000200;
 556       return false;
 557     }
 558 
 559     if (is_ext_suspended()) {
 560       // thread is suspended
 561       *bits |= 0x00000400;
 562       return true;
 563     }
 564 
 565     // Now that we no longer do hard suspends of threads running
 566     // native code, the target thread can be changing thread state
 567     // while we are in this routine:
 568     //
 569     //   _thread_in_native -> _thread_in_native_trans -> _thread_blocked
 570     //
 571     // We save a copy of the thread state as observed at this moment
 572     // and make our decision about suspend completeness based on the
 573     // copy. This closes the race where the thread state is seen as
 574     // _thread_in_native_trans in the if-thread_blocked check, but is
 575     // seen as _thread_blocked in if-thread_in_native_trans check.
 576     JavaThreadState save_state = thread_state();
 577 
 578     if (save_state == _thread_blocked && is_suspend_equivalent()) {
 579       // If the thread's state is _thread_blocked and this blocking
 580       // condition is known to be equivalent to a suspend, then we can
 581       // consider the thread to be externally suspended. This means that
 582       // the code that sets _thread_blocked has been modified to do
 583       // self-suspension if the blocking condition releases. We also
 584       // used to check for CONDVAR_WAIT here, but that is now covered by
 585       // the _thread_blocked with self-suspension check.
 586       //
 587       // Return true since we wouldn't be here unless there was still an
 588       // external suspend request.
 589       *bits |= 0x00001000;
 590       return true;
 591     } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
 592       // Threads running native code will self-suspend on native==>VM/Java
 593       // transitions. If its stack is walkable (should always be the case
 594       // unless this function is called before the actual java_suspend()
 595       // call), then the wait is done.
 596       *bits |= 0x00002000;
 597       return true;
 598     } else if (!called_by_wait && !did_trans_retry &&
 599                save_state == _thread_in_native_trans &&
 600                frame_anchor()->walkable()) {
 601       // The thread is transitioning from thread_in_native to another
 602       // thread state. check_safepoint_and_suspend_for_native_trans()
 603       // will force the thread to self-suspend. If it hasn't gotten
 604       // there yet we may have caught the thread in-between the native
 605       // code check above and the self-suspend. Lucky us. If we were
 606       // called by wait_for_ext_suspend_completion(), then it
 607       // will be doing the retries so we don't have to.
 608       //
 609       // Since we use the saved thread state in the if-statement above,
 610       // there is a chance that the thread has already transitioned to
 611       // _thread_blocked by the time we get here. In that case, we will
 612       // make a single unnecessary pass through the logic below. This
 613       // doesn't hurt anything since we still do the trans retry.
 614 
 615       *bits |= 0x00004000;
 616 
 617       // Once the thread leaves thread_in_native_trans for another
 618       // thread state, we break out of this retry loop. We shouldn't
 619       // need this flag to prevent us from getting back here, but
 620       // sometimes paranoia is good.
 621       did_trans_retry = true;
 622 
 623       // We wait for the thread to transition to a more usable state.
 624       for (int i = 1; i <= SuspendRetryCount; i++) {
 625         // We used to do an "os::yield_all(i)" call here with the intention
 626         // that yielding would increase on each retry. However, the parameter
 627         // is ignored on Linux which means the yield didn't scale up. Waiting
 628         // on the SR_lock below provides a much more predictable scale up for
 629         // the delay. It also provides a simple/direct point to check for any
 630         // safepoint requests from the VMThread
 631 
 632         // temporarily drops SR_lock while doing wait with safepoint check
 633         // (if we're a JavaThread - the WatcherThread can also call this)
 634         // and increase delay with each retry
 635         SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 636 
 637         // check the actual thread state instead of what we saved above
 638         if (thread_state() != _thread_in_native_trans) {
 639           // the thread has transitioned to another thread state so
 640           // try all the checks (except this one) one more time.
 641           do_trans_retry = true;
 642           break;
 643         }
 644       } // end retry loop
 645 
 646 
 647     }
 648   } while (do_trans_retry);
 649 
 650   *bits |= 0x00000010;
 651   return false;
 652 }
 653 
 654 // Wait for an external suspend request to complete (or be cancelled).
 655 // Returns true if the thread is externally suspended and false otherwise.
 656 //
 657 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
 658                                                  uint32_t *bits) {
 659   TraceSuspendDebugBits tsdb(this, true /* is_wait */,
 660                              false /* !called_by_wait */, bits);
 661 
 662   // local flag copies to minimize SR_lock hold time
 663   bool is_suspended;
 664   bool pending;
 665   uint32_t reset_bits;
 666 
 667   // set a marker so is_ext_suspend_completed() knows we are the caller
 668   *bits |= 0x00010000;
 669 
 670   // We use reset_bits to reinitialize the bits value at the top of
 671   // each retry loop. This allows the caller to make use of any
 672   // unused bits for their own marking purposes.
 673   reset_bits = *bits;
 674 
 675   {
 676     MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
 677     is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 678                                             delay, bits);
 679     pending = is_external_suspend();
 680   }
 681   // must release SR_lock to allow suspension to complete
 682 
 683   if (!pending) {
 684     // A cancelled suspend request is the only false return from
 685     // is_ext_suspend_completed() that keeps us from entering the
 686     // retry loop.
 687     *bits |= 0x00020000;
 688     return false;
 689   }
 690 
 691   if (is_suspended) {
 692     *bits |= 0x00040000;
 693     return true;
 694   }
 695 
 696   for (int i = 1; i <= retries; i++) {
 697     *bits = reset_bits;  // reinit to only track last retry
 698 
 699     // We used to do an "os::yield_all(i)" call here with the intention
 700     // that yielding would increase on each retry. However, the parameter
 701     // is ignored on Linux which means the yield didn't scale up. Waiting
 702     // on the SR_lock below provides a much more predictable scale up for
 703     // the delay. It also provides a simple/direct point to check for any
 704     // safepoint requests from the VMThread
 705 
 706     {
 707       MutexLocker ml(SR_lock());
 708       // wait with safepoint check (if we're a JavaThread - the WatcherThread
 709       // can also call this)  and increase delay with each retry
 710       SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 711 
 712       is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 713                                               delay, bits);
 714 
 715       // It is possible for the external suspend request to be cancelled
 716       // (by a resume) before the actual suspend operation is completed.
 717       // Refresh our local copy to see if we still need to wait.
 718       pending = is_external_suspend();
 719     }
 720 
 721     if (!pending) {
 722       // A cancelled suspend request is the only false return from
 723       // is_ext_suspend_completed() that keeps us from staying in the
 724       // retry loop.
 725       *bits |= 0x00080000;
 726       return false;
 727     }
 728 
 729     if (is_suspended) {
 730       *bits |= 0x00100000;
 731       return true;
 732     }
 733   } // end retry loop
 734 
 735   // thread did not suspend after all our retries
 736   *bits |= 0x00200000;
 737   return false;
 738 }
 739 
 740 #ifndef PRODUCT
 741 void JavaThread::record_jump(address target, address instr, const char* file,
 742                              int line) {
 743 
 744   // This should not need to be atomic as the only way for simultaneous
 745   // updates is via interrupts. Even then this should be rare or non-existent
 746   // and we don't care that much anyway.
 747 
 748   int index = _jmp_ring_index;
 749   _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
 750   _jmp_ring[index]._target = (intptr_t) target;
 751   _jmp_ring[index]._instruction = (intptr_t) instr;
 752   _jmp_ring[index]._file = file;
 753   _jmp_ring[index]._line = line;
 754 }
 755 #endif // PRODUCT
 756 
 757 // Called by flat profiler
 758 // Callers have already called wait_for_ext_suspend_completion
 759 // The assertion for that is currently too complex to put here:
 760 bool JavaThread::profile_last_Java_frame(frame* _fr) {
 761   bool gotframe = false;
 762   // self suspension saves needed state.
 763   if (has_last_Java_frame() && _anchor.walkable()) {
 764     *_fr = pd_last_frame();
 765     gotframe = true;
 766   }
 767   return gotframe;
 768 }
 769 
 770 void Thread::interrupt(Thread* thread) {
 771   trace("interrupt", thread);
 772   debug_only(check_for_dangling_thread_pointer(thread);)
 773   os::interrupt(thread);
 774 }
 775 
 776 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
 777   trace("is_interrupted", thread);
 778   debug_only(check_for_dangling_thread_pointer(thread);)
 779   // Note:  If clear_interrupted==false, this simply fetches and
 780   // returns the value of the field osthread()->interrupted().
 781   return os::is_interrupted(thread, clear_interrupted);
 782 }
 783 
 784 
 785 // GC Support
 786 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
 787   jint thread_parity = _oops_do_parity;
 788   if (thread_parity != strong_roots_parity) {
 789     jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
 790     if (res == thread_parity) {
 791       return true;
 792     } else {
 793       guarantee(res == strong_roots_parity, "Or else what?");
 794       assert(SharedHeap::heap()->workers()->active_workers() > 0,
 795              "Should only fail when parallel.");
 796       return false;
 797     }
 798   }
 799   assert(SharedHeap::heap()->workers()->active_workers() > 0,
 800          "Should only fail when parallel.");
 801   return false;
 802 }
 803 
 804 void Thread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
 805   active_handles()->oops_do(f);
 806   // Do oop for ThreadShadow
 807   f->do_oop((oop*)&_pending_exception);
 808   handle_area()->oops_do(f);
 809 }
 810 
 811 void Thread::nmethods_do(CodeBlobClosure* cf) {
 812   // no nmethods in a generic thread...
 813 }
 814 
 815 void Thread::metadata_do(void f(Metadata*)) {
 816   if (metadata_handles() != NULL) {
 817     for (int i = 0; i< metadata_handles()->length(); i++) {
 818       f(metadata_handles()->at(i));
 819     }
 820   }
 821 }
 822 
 823 void Thread::print_on(outputStream* st) const {
 824   // get_priority assumes osthread initialized
 825   if (osthread() != NULL) {
 826     int os_prio;
 827     if (os::get_native_priority(this, &os_prio) == OS_OK) {
 828       st->print("os_prio=%d ", os_prio);
 829     }
 830     st->print("tid=" INTPTR_FORMAT " ", this);
 831     ext().print_on(st);
 832     osthread()->print_on(st);
 833   }
 834   debug_only(if (WizardMode) print_owned_locks_on(st);)
 835 }
 836 
 837 // Thread::print_on_error() is called by fatal error handler. Don't use
 838 // any lock or allocate memory.
 839 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
 840   if (is_VM_thread())                 st->print("VMThread");
 841   else if (is_Compiler_thread())      st->print("CompilerThread");
 842   else if (is_Java_thread())          st->print("JavaThread");
 843   else if (is_GC_task_thread())       st->print("GCTaskThread");
 844   else if (is_Watcher_thread())       st->print("WatcherThread");
 845   else if (is_ConcurrentGC_thread())  st->print("ConcurrentGCThread");
 846   else                                st->print("Thread");
 847 
 848   st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
 849             _stack_base - _stack_size, _stack_base);
 850 
 851   if (osthread()) {
 852     st->print(" [id=%d]", osthread()->thread_id());
 853   }
 854 }
 855 
 856 #ifdef ASSERT
 857 void Thread::print_owned_locks_on(outputStream* st) const {
 858   Monitor *cur = _owned_locks;
 859   if (cur == NULL) {
 860     st->print(" (no locks) ");
 861   } else {
 862     st->print_cr(" Locks owned:");
 863     while (cur) {
 864       cur->print_on(st);
 865       cur = cur->next();
 866     }
 867   }
 868 }
 869 
 870 static int ref_use_count  = 0;
 871 
 872 bool Thread::owns_locks_but_compiled_lock() const {
 873   for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 874     if (cur != Compile_lock) return true;
 875   }
 876   return false;
 877 }
 878 
 879 
 880 #endif
 881 
 882 #ifndef PRODUCT
 883 
 884 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
 885 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
 886 // no threads which allow_vm_block's are held
 887 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
 888   // Check if current thread is allowed to block at a safepoint
 889   if (!(_allow_safepoint_count == 0)) {
 890     fatal("Possible safepoint reached by thread that does not allow it");
 891   }
 892   if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
 893     fatal("LEAF method calling lock?");
 894   }
 895 
 896 #ifdef ASSERT
 897   if (potential_vm_operation && is_Java_thread()
 898       && !Universe::is_bootstrapping()) {
 899     // Make sure we do not hold any locks that the VM thread also uses.
 900     // This could potentially lead to deadlocks
 901     for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 902       // Threads_lock is special, since the safepoint synchronization will not start before this is
 903       // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
 904       // since it is used to transfer control between JavaThreads and the VMThread
 905       // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
 906       if ((cur->allow_vm_block() &&
 907            cur != Threads_lock &&
 908            cur != Compile_lock &&               // Temporary: should not be necessary when we get separate compilation
 909            cur != VMOperationRequest_lock &&
 910            cur != VMOperationQueue_lock) ||
 911            cur->rank() == Mutex::special) {
 912         fatal(err_msg("Thread holding lock at safepoint that vm can block on: %s", cur->name()));
 913       }
 914     }
 915   }
 916 
 917   if (GCALotAtAllSafepoints) {
 918     // We could enter a safepoint here and thus have a gc
 919     InterfaceSupport::check_gc_alot();
 920   }
 921 #endif
 922 }
 923 #endif
 924 
 925 bool Thread::is_in_stack(address adr) const {
 926   assert(Thread::current() == this, "is_in_stack can only be called from current thread");
 927   address end = os::current_stack_pointer();
 928   // Allow non Java threads to call this without stack_base
 929   if (_stack_base == NULL) return true;
 930   if (stack_base() >= adr && adr >= end) return true;
 931 
 932   return false;
 933 }
 934 
 935 
 936 bool Thread::is_in_usable_stack(address adr) const {
 937   size_t stack_guard_size = os::uses_stack_guard_pages() ? (StackYellowPages + StackRedPages) * os::vm_page_size() : 0;
 938   size_t usable_stack_size = _stack_size - stack_guard_size;
 939 
 940   return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
 941 }
 942 
 943 
 944 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
 945 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
 946 // used for compilation in the future. If that change is made, the need for these methods
 947 // should be revisited, and they should be removed if possible.
 948 
 949 bool Thread::is_lock_owned(address adr) const {
 950   return on_local_stack(adr);
 951 }
 952 
 953 bool Thread::set_as_starting_thread() {
 954   // NOTE: this must be called inside the main thread.
 955   return os::create_main_thread((JavaThread*)this);
 956 }
 957 
 958 static void initialize_class(Symbol* class_name, TRAPS) {
 959   Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
 960   InstanceKlass::cast(klass)->initialize(CHECK);
 961 }
 962 
 963 
 964 // Creates the initial ThreadGroup
 965 static Handle create_initial_thread_group(TRAPS) {
 966   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
 967   instanceKlassHandle klass (THREAD, k);
 968 
 969   Handle system_instance = klass->allocate_instance_handle(CHECK_NH);
 970   {
 971     JavaValue result(T_VOID);
 972     JavaCalls::call_special(&result,
 973                             system_instance,
 974                             klass,
 975                             vmSymbols::object_initializer_name(),
 976                             vmSymbols::void_method_signature(),
 977                             CHECK_NH);
 978   }
 979   Universe::set_system_thread_group(system_instance());
 980 
 981   Handle main_instance = klass->allocate_instance_handle(CHECK_NH);
 982   {
 983     JavaValue result(T_VOID);
 984     Handle string = java_lang_String::create_from_str("main", CHECK_NH);
 985     JavaCalls::call_special(&result,
 986                             main_instance,
 987                             klass,
 988                             vmSymbols::object_initializer_name(),
 989                             vmSymbols::threadgroup_string_void_signature(),
 990                             system_instance,
 991                             string,
 992                             CHECK_NH);
 993   }
 994   return main_instance;
 995 }
 996 
 997 // Creates the initial Thread
 998 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
 999                                  TRAPS) {
1000   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
1001   instanceKlassHandle klass (THREAD, k);
1002   instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);
1003 
1004   java_lang_Thread::set_thread(thread_oop(), thread);
1005   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1006   thread->set_threadObj(thread_oop());
1007 
1008   Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1009 
1010   JavaValue result(T_VOID);
1011   JavaCalls::call_special(&result, thread_oop,
1012                           klass,
1013                           vmSymbols::object_initializer_name(),
1014                           vmSymbols::threadgroup_string_void_signature(),
1015                           thread_group,
1016                           string,
1017                           CHECK_NULL);
1018   return thread_oop();
1019 }
1020 
1021 static void call_initializeSystemClass(TRAPS) {
1022   Klass* k =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1023   instanceKlassHandle klass (THREAD, k);
1024 
1025   JavaValue result(T_VOID);
1026   JavaCalls::call_static(&result, klass, vmSymbols::initializeSystemClass_name(),
1027                          vmSymbols::void_method_signature(), CHECK);
1028 }
1029 
1030 char java_runtime_name[128] = "";
1031 char java_runtime_version[128] = "";
1032 
1033 // extract the JRE name from sun.misc.Version.java_runtime_name
1034 static const char* get_java_runtime_name(TRAPS) {
1035   Klass* k = SystemDictionary::find(vmSymbols::sun_misc_Version(),
1036                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1037   fieldDescriptor fd;
1038   bool found = k != NULL &&
1039                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1040                                                         vmSymbols::string_signature(), &fd);
1041   if (found) {
1042     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1043     if (name_oop == NULL) {
1044       return NULL;
1045     }
1046     const char* name = java_lang_String::as_utf8_string(name_oop,
1047                                                         java_runtime_name,
1048                                                         sizeof(java_runtime_name));
1049     return name;
1050   } else {
1051     return NULL;
1052   }
1053 }
1054 
1055 // extract the JRE version from sun.misc.Version.java_runtime_version
1056 static const char* get_java_runtime_version(TRAPS) {
1057   Klass* k = SystemDictionary::find(vmSymbols::sun_misc_Version(),
1058                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1059   fieldDescriptor fd;
1060   bool found = k != NULL &&
1061                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1062                                                         vmSymbols::string_signature(), &fd);
1063   if (found) {
1064     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1065     if (name_oop == NULL) {
1066       return NULL;
1067     }
1068     const char* name = java_lang_String::as_utf8_string(name_oop,
1069                                                         java_runtime_version,
1070                                                         sizeof(java_runtime_version));
1071     return name;
1072   } else {
1073     return NULL;
1074   }
1075 }
1076 
1077 // General purpose hook into Java code, run once when the VM is initialized.
1078 // The Java library method itself may be changed independently from the VM.
1079 static void call_postVMInitHook(TRAPS) {
1080   Klass* k = SystemDictionary::resolve_or_null(vmSymbols::sun_misc_PostVMInitHook(), THREAD);
1081   instanceKlassHandle klass (THREAD, k);
1082   if (klass.not_null()) {
1083     JavaValue result(T_VOID);
1084     JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1085                            vmSymbols::void_method_signature(),
1086                            CHECK);
1087   }
1088 }
1089 
1090 static void reset_vm_info_property(TRAPS) {
1091   // the vm info string
1092   ResourceMark rm(THREAD);
1093   const char *vm_info = VM_Version::vm_info_string();
1094 
1095   // java.lang.System class
1096   Klass* k =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1097   instanceKlassHandle klass (THREAD, k);
1098 
1099   // setProperty arguments
1100   Handle key_str    = java_lang_String::create_from_str("java.vm.info", CHECK);
1101   Handle value_str  = java_lang_String::create_from_str(vm_info, CHECK);
1102 
1103   // return value
1104   JavaValue r(T_OBJECT);
1105 
1106   // public static String setProperty(String key, String value);
1107   JavaCalls::call_static(&r,
1108                          klass,
1109                          vmSymbols::setProperty_name(),
1110                          vmSymbols::string_string_string_signature(),
1111                          key_str,
1112                          value_str,
1113                          CHECK);
1114 }
1115 
1116 
1117 void JavaThread::allocate_threadObj(Handle thread_group, char* thread_name,
1118                                     bool daemon, TRAPS) {
1119   assert(thread_group.not_null(), "thread group should be specified");
1120   assert(threadObj() == NULL, "should only create Java thread object once");
1121 
1122   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1123   instanceKlassHandle klass (THREAD, k);
1124   instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
1125 
1126   java_lang_Thread::set_thread(thread_oop(), this);
1127   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1128   set_threadObj(thread_oop());
1129 
1130   JavaValue result(T_VOID);
1131   if (thread_name != NULL) {
1132     Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1133     // Thread gets assigned specified name and null target
1134     JavaCalls::call_special(&result,
1135                             thread_oop,
1136                             klass,
1137                             vmSymbols::object_initializer_name(),
1138                             vmSymbols::threadgroup_string_void_signature(),
1139                             thread_group, // Argument 1
1140                             name,         // Argument 2
1141                             THREAD);
1142   } else {
1143     // Thread gets assigned name "Thread-nnn" and null target
1144     // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1145     JavaCalls::call_special(&result,
1146                             thread_oop,
1147                             klass,
1148                             vmSymbols::object_initializer_name(),
1149                             vmSymbols::threadgroup_runnable_void_signature(),
1150                             thread_group, // Argument 1
1151                             Handle(),     // Argument 2
1152                             THREAD);
1153   }
1154 
1155 
1156   if (daemon) {
1157     java_lang_Thread::set_daemon(thread_oop());
1158   }
1159 
1160   if (HAS_PENDING_EXCEPTION) {
1161     return;
1162   }
1163 
1164   KlassHandle group(this, SystemDictionary::ThreadGroup_klass());
1165   Handle threadObj(this, this->threadObj());
1166 
1167   JavaCalls::call_special(&result,
1168                           thread_group,
1169                           group,
1170                           vmSymbols::add_method_name(),
1171                           vmSymbols::thread_void_signature(),
1172                           threadObj,          // Arg 1
1173                           THREAD);
1174 
1175 
1176 }
1177 
1178 // NamedThread --  non-JavaThread subclasses with multiple
1179 // uniquely named instances should derive from this.
1180 NamedThread::NamedThread() : Thread() {
1181   _name = NULL;
1182   _processed_thread = NULL;
1183 }
1184 
1185 NamedThread::~NamedThread() {
1186   if (_name != NULL) {
1187     FREE_C_HEAP_ARRAY(char, _name, mtThread);
1188     _name = NULL;
1189   }
1190 }
1191 
1192 void NamedThread::set_name(const char* format, ...) {
1193   guarantee(_name == NULL, "Only get to set name once.");
1194   _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1195   guarantee(_name != NULL, "alloc failure");
1196   va_list ap;
1197   va_start(ap, format);
1198   jio_vsnprintf(_name, max_name_len, format, ap);
1199   va_end(ap);
1200 }
1201 
1202 void NamedThread::print_on(outputStream* st) const {
1203   st->print("\"%s\" ", name());
1204   Thread::print_on(st);
1205   st->cr();
1206 }
1207 
1208 
1209 // ======= WatcherThread ========
1210 
1211 // The watcher thread exists to simulate timer interrupts.  It should
1212 // be replaced by an abstraction over whatever native support for
1213 // timer interrupts exists on the platform.
1214 
1215 WatcherThread* WatcherThread::_watcher_thread   = NULL;
1216 bool WatcherThread::_startable = false;
1217 volatile bool  WatcherThread::_should_terminate = false;
1218 
1219 WatcherThread::WatcherThread() : Thread(), _crash_protection(NULL) {
1220   assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1221   if (os::create_thread(this, os::watcher_thread)) {
1222     _watcher_thread = this;
1223 
1224     // Set the watcher thread to the highest OS priority which should not be
1225     // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1226     // is created. The only normal thread using this priority is the reference
1227     // handler thread, which runs for very short intervals only.
1228     // If the VMThread's priority is not lower than the WatcherThread profiling
1229     // will be inaccurate.
1230     os::set_priority(this, MaxPriority);
1231     if (!DisableStartThread) {
1232       os::start_thread(this);
1233     }
1234   }
1235 }
1236 
1237 int WatcherThread::sleep() const {
1238   MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1239 
1240   // remaining will be zero if there are no tasks,
1241   // causing the WatcherThread to sleep until a task is
1242   // enrolled
1243   int remaining = PeriodicTask::time_to_wait();
1244   int time_slept = 0;
1245 
1246   // we expect this to timeout - we only ever get unparked when
1247   // we should terminate or when a new task has been enrolled
1248   OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1249 
1250   jlong time_before_loop = os::javaTimeNanos();
1251 
1252   for (;;) {
1253     bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag, remaining);
1254     jlong now = os::javaTimeNanos();
1255 
1256     if (remaining == 0) {
1257       // if we didn't have any tasks we could have waited for a long time
1258       // consider the time_slept zero and reset time_before_loop
1259       time_slept = 0;
1260       time_before_loop = now;
1261     } else {
1262       // need to recalculate since we might have new tasks in _tasks
1263       time_slept = (int) ((now - time_before_loop) / 1000000);
1264     }
1265 
1266     // Change to task list or spurious wakeup of some kind
1267     if (timedout || _should_terminate) {
1268       break;
1269     }
1270 
1271     remaining = PeriodicTask::time_to_wait();
1272     if (remaining == 0) {
1273       // Last task was just disenrolled so loop around and wait until
1274       // another task gets enrolled
1275       continue;
1276     }
1277 
1278     remaining -= time_slept;
1279     if (remaining <= 0) {
1280       break;
1281     }
1282   }
1283 
1284   return time_slept;
1285 }
1286 
1287 void WatcherThread::run() {
1288   assert(this == watcher_thread(), "just checking");
1289 
1290   this->record_stack_base_and_size();
1291   this->initialize_thread_local_storage();
1292   this->set_native_thread_name(this->name());
1293   this->set_active_handles(JNIHandleBlock::allocate_block());
1294   while (!_should_terminate) {
1295     assert(watcher_thread() == Thread::current(), "thread consistency check");
1296     assert(watcher_thread() == this, "thread consistency check");
1297 
1298     // Calculate how long it'll be until the next PeriodicTask work
1299     // should be done, and sleep that amount of time.
1300     int time_waited = sleep();
1301 
1302     if (is_error_reported()) {
1303       // A fatal error has happened, the error handler(VMError::report_and_die)
1304       // should abort JVM after creating an error log file. However in some
1305       // rare cases, the error handler itself might deadlock. Here we try to
1306       // kill JVM if the fatal error handler fails to abort in 2 minutes.
1307       //
1308       // This code is in WatcherThread because WatcherThread wakes up
1309       // periodically so the fatal error handler doesn't need to do anything;
1310       // also because the WatcherThread is less likely to crash than other
1311       // threads.
1312 
1313       for (;;) {
1314         if (!ShowMessageBoxOnError
1315             && (OnError == NULL || OnError[0] == '\0')
1316             && Arguments::abort_hook() == NULL) {
1317           os::sleep(this, 2 * 60 * 1000, false);
1318           fdStream err(defaultStream::output_fd());
1319           err.print_raw_cr("# [ timer expired, abort... ]");
1320           // skip atexit/vm_exit/vm_abort hooks
1321           os::die();
1322         }
1323 
1324         // Wake up 5 seconds later, the fatal handler may reset OnError or
1325         // ShowMessageBoxOnError when it is ready to abort.
1326         os::sleep(this, 5 * 1000, false);
1327       }
1328     }
1329 
1330     PeriodicTask::real_time_tick(time_waited);
1331   }
1332 
1333   // Signal that it is terminated
1334   {
1335     MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1336     _watcher_thread = NULL;
1337     Terminator_lock->notify();
1338   }
1339 
1340   // Thread destructor usually does this..
1341   ThreadLocalStorage::set_thread(NULL);
1342 }
1343 
1344 void WatcherThread::start() {
1345   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1346 
1347   if (watcher_thread() == NULL && _startable) {
1348     _should_terminate = false;
1349     // Create the single instance of WatcherThread
1350     new WatcherThread();
1351   }
1352 }
1353 
1354 void WatcherThread::make_startable() {
1355   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1356   _startable = true;
1357 }
1358 
1359 void WatcherThread::stop() {
1360   // Get the PeriodicTask_lock if we can. If we cannot, then the
1361   // WatcherThread is using it and we don't want to block on that lock
1362   // here because that might cause a safepoint deadlock depending on
1363   // what the current WatcherThread tasks are doing.
1364   bool have_lock = PeriodicTask_lock->try_lock();
1365 
1366   _should_terminate = true;
1367   OrderAccess::fence();  // ensure WatcherThread sees update in main loop
1368 
1369   if (have_lock) {
1370     WatcherThread* watcher = watcher_thread();
1371     if (watcher != NULL) {
1372       // If we managed to get the lock, then we should unpark the
1373       // WatcherThread so that it can see we want it to stop.
1374       watcher->unpark();
1375     }
1376 
1377     PeriodicTask_lock->unlock();
1378   }
1379 
1380   // it is ok to take late safepoints here, if needed
1381   MutexLocker mu(Terminator_lock);
1382 
1383   while (watcher_thread() != NULL) {
1384     // This wait should make safepoint checks, wait without a timeout,
1385     // and wait as a suspend-equivalent condition.
1386     //
1387     // Note: If the FlatProfiler is running, then this thread is waiting
1388     // for the WatcherThread to terminate and the WatcherThread, via the
1389     // FlatProfiler task, is waiting for the external suspend request on
1390     // this thread to complete. wait_for_ext_suspend_completion() will
1391     // eventually timeout, but that takes time. Making this wait a
1392     // suspend-equivalent condition solves that timeout problem.
1393     //
1394     Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1395                           Mutex::_as_suspend_equivalent_flag);
1396   }
1397 }
1398 
1399 void WatcherThread::unpark() {
1400   MutexLockerEx ml(PeriodicTask_lock->owned_by_self()
1401                    ? NULL
1402                    : PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1403   PeriodicTask_lock->notify();
1404 }
1405 
1406 void WatcherThread::print_on(outputStream* st) const {
1407   st->print("\"%s\" ", name());
1408   Thread::print_on(st);
1409   st->cr();
1410 }
1411 
1412 // ======= JavaThread ========
1413 
1414 // A JavaThread is a normal Java thread
1415 
1416 void JavaThread::initialize() {
1417   // Initialize fields
1418 
1419   // Set the claimed par_id to UINT_MAX (ie not claiming any par_ids)
1420   set_claimed_par_id(UINT_MAX);
1421 
1422   set_saved_exception_pc(NULL);
1423   set_threadObj(NULL);
1424   _anchor.clear();
1425   set_entry_point(NULL);
1426   set_jni_functions(jni_functions());
1427   set_callee_target(NULL);
1428   set_vm_result(NULL);
1429   set_vm_result_2(NULL);
1430   set_vframe_array_head(NULL);
1431   set_vframe_array_last(NULL);
1432   set_deferred_locals(NULL);
1433   set_deopt_mark(NULL);
1434   set_deopt_nmethod(NULL);
1435   clear_must_deopt_id();
1436   set_monitor_chunks(NULL);
1437   set_next(NULL);
1438   set_thread_state(_thread_new);
1439   _terminated = _not_terminated;
1440   _privileged_stack_top = NULL;
1441   _array_for_gc = NULL;
1442   _suspend_equivalent = false;
1443   _in_deopt_handler = 0;
1444   _doing_unsafe_access = false;
1445   _stack_guard_state = stack_guard_unused;
1446   (void)const_cast<oop&>(_exception_oop = oop(NULL));
1447   _exception_pc  = 0;
1448   _exception_handler_pc = 0;
1449   _is_method_handle_return = 0;
1450   _jvmti_thread_state= NULL;
1451   _should_post_on_exceptions_flag = JNI_FALSE;
1452   _jvmti_get_loaded_classes_closure = NULL;
1453   _interp_only_mode    = 0;
1454   _special_runtime_exit_condition = _no_async_condition;
1455   _pending_async_exception = NULL;
1456   _thread_stat = NULL;
1457   _thread_stat = new ThreadStatistics();
1458   _blocked_on_compilation = false;
1459   _jni_active_critical = 0;
1460   _pending_jni_exception_check_fn = NULL;
1461   _do_not_unlock_if_synchronized = false;
1462   _cached_monitor_info = NULL;
1463   _parker = Parker::Allocate(this);
1464 
1465 #ifndef PRODUCT
1466   _jmp_ring_index = 0;
1467   for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1468     record_jump(NULL, NULL, NULL, 0);
1469   }
1470 #endif // PRODUCT
1471 
1472   set_thread_profiler(NULL);
1473   if (FlatProfiler::is_active()) {
1474     // This is where we would decide to either give each thread it's own profiler
1475     // or use one global one from FlatProfiler,
1476     // or up to some count of the number of profiled threads, etc.
1477     ThreadProfiler* pp = new ThreadProfiler();
1478     pp->engage();
1479     set_thread_profiler(pp);
1480   }
1481 
1482   // Setup safepoint state info for this thread
1483   ThreadSafepointState::create(this);
1484 
1485   debug_only(_java_call_counter = 0);
1486 
1487   // JVMTI PopFrame support
1488   _popframe_condition = popframe_inactive;
1489   _popframe_preserved_args = NULL;
1490   _popframe_preserved_args_size = 0;
1491 
1492   pd_initialize();
1493 }
1494 
1495 #if INCLUDE_ALL_GCS
1496 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1497 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1498 #endif // INCLUDE_ALL_GCS
1499 
1500 JavaThread::JavaThread(bool is_attaching_via_jni) :
1501                        Thread()
1502 #if INCLUDE_ALL_GCS
1503                        , _satb_mark_queue(&_satb_mark_queue_set),
1504                        _dirty_card_queue(&_dirty_card_queue_set)
1505 #endif // INCLUDE_ALL_GCS
1506 {
1507   initialize();
1508   if (is_attaching_via_jni) {
1509     _jni_attach_state = _attaching_via_jni;
1510   } else {
1511     _jni_attach_state = _not_attaching_via_jni;
1512   }
1513   assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1514 }
1515 
1516 bool JavaThread::reguard_stack(address cur_sp) {
1517   if (_stack_guard_state != stack_guard_yellow_disabled) {
1518     return true; // Stack already guarded or guard pages not needed.
1519   }
1520 
1521   if (register_stack_overflow()) {
1522     // For those architectures which have separate register and
1523     // memory stacks, we must check the register stack to see if
1524     // it has overflowed.
1525     return false;
1526   }
1527 
1528   // Java code never executes within the yellow zone: the latter is only
1529   // there to provoke an exception during stack banging.  If java code
1530   // is executing there, either StackShadowPages should be larger, or
1531   // some exception code in c1, c2 or the interpreter isn't unwinding
1532   // when it should.
1533   guarantee(cur_sp > stack_yellow_zone_base(), "not enough space to reguard - increase StackShadowPages");
1534 
1535   enable_stack_yellow_zone();
1536   return true;
1537 }
1538 
1539 bool JavaThread::reguard_stack(void) {
1540   return reguard_stack(os::current_stack_pointer());
1541 }
1542 
1543 
1544 void JavaThread::block_if_vm_exited() {
1545   if (_terminated == _vm_exited) {
1546     // _vm_exited is set at safepoint, and Threads_lock is never released
1547     // we will block here forever
1548     Threads_lock->lock_without_safepoint_check();
1549     ShouldNotReachHere();
1550   }
1551 }
1552 
1553 
1554 // Remove this ifdef when C1 is ported to the compiler interface.
1555 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1556 
1557 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1558                        Thread()
1559 #if INCLUDE_ALL_GCS
1560                        , _satb_mark_queue(&_satb_mark_queue_set),
1561                        _dirty_card_queue(&_dirty_card_queue_set)
1562 #endif // INCLUDE_ALL_GCS
1563 {
1564   if (TraceThreadEvents) {
1565     tty->print_cr("creating thread %p", this);
1566   }
1567   initialize();
1568   _jni_attach_state = _not_attaching_via_jni;
1569   set_entry_point(entry_point);
1570   // Create the native thread itself.
1571   // %note runtime_23
1572   os::ThreadType thr_type = os::java_thread;
1573   thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1574                                                      os::java_thread;
1575   os::create_thread(this, thr_type, stack_sz);
1576   // The _osthread may be NULL here because we ran out of memory (too many threads active).
1577   // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1578   // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1579   // the exception consists of creating the exception object & initializing it, initialization
1580   // will leave the VM via a JavaCall and then all locks must be unlocked).
1581   //
1582   // The thread is still suspended when we reach here. Thread must be explicit started
1583   // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1584   // by calling Threads:add. The reason why this is not done here, is because the thread
1585   // object must be fully initialized (take a look at JVM_Start)
1586 }
1587 
1588 JavaThread::~JavaThread() {
1589   if (TraceThreadEvents) {
1590     tty->print_cr("terminate thread %p", this);
1591   }
1592 
1593   // JSR166 -- return the parker to the free list
1594   Parker::Release(_parker);
1595   _parker = NULL;
1596 
1597   // Free any remaining  previous UnrollBlock
1598   vframeArray* old_array = vframe_array_last();
1599 
1600   if (old_array != NULL) {
1601     Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1602     old_array->set_unroll_block(NULL);
1603     delete old_info;
1604     delete old_array;
1605   }
1606 
1607   GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1608   if (deferred != NULL) {
1609     // This can only happen if thread is destroyed before deoptimization occurs.
1610     assert(deferred->length() != 0, "empty array!");
1611     do {
1612       jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1613       deferred->remove_at(0);
1614       // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1615       delete dlv;
1616     } while (deferred->length() != 0);
1617     delete deferred;
1618   }
1619 
1620   // All Java related clean up happens in exit
1621   ThreadSafepointState::destroy(this);
1622   if (_thread_profiler != NULL) delete _thread_profiler;
1623   if (_thread_stat != NULL) delete _thread_stat;
1624 }
1625 
1626 
1627 // The first routine called by a new Java thread
1628 void JavaThread::run() {
1629   // initialize thread-local alloc buffer related fields
1630   this->initialize_tlab();
1631 
1632   // used to test validity of stack trace backs
1633   this->record_base_of_stack_pointer();
1634 
1635   // Record real stack base and size.
1636   this->record_stack_base_and_size();
1637 
1638   // Initialize thread local storage; set before calling MutexLocker
1639   this->initialize_thread_local_storage();
1640 
1641   this->create_stack_guard_pages();
1642 
1643   this->cache_global_variables();
1644 
1645   // Thread is now sufficient initialized to be handled by the safepoint code as being
1646   // in the VM. Change thread state from _thread_new to _thread_in_vm
1647   ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1648 
1649   assert(JavaThread::current() == this, "sanity check");
1650   assert(!Thread::current()->owns_locks(), "sanity check");
1651 
1652   DTRACE_THREAD_PROBE(start, this);
1653 
1654   // This operation might block. We call that after all safepoint checks for a new thread has
1655   // been completed.
1656   this->set_active_handles(JNIHandleBlock::allocate_block());
1657 
1658   if (JvmtiExport::should_post_thread_life()) {
1659     JvmtiExport::post_thread_start(this);
1660   }
1661 
1662   EventThreadStart event;
1663   if (event.should_commit()) {
1664     event.set_javalangthread(java_lang_Thread::thread_id(this->threadObj()));
1665     event.commit();
1666   }
1667 
1668   // We call another function to do the rest so we are sure that the stack addresses used
1669   // from there will be lower than the stack base just computed
1670   thread_main_inner();
1671 
1672   // Note, thread is no longer valid at this point!
1673 }
1674 
1675 
1676 void JavaThread::thread_main_inner() {
1677   assert(JavaThread::current() == this, "sanity check");
1678   assert(this->threadObj() != NULL, "just checking");
1679 
1680   // Execute thread entry point unless this thread has a pending exception
1681   // or has been stopped before starting.
1682   // Note: Due to JVM_StopThread we can have pending exceptions already!
1683   if (!this->has_pending_exception() &&
1684       !java_lang_Thread::is_stillborn(this->threadObj())) {
1685     {
1686       ResourceMark rm(this);
1687       this->set_native_thread_name(this->get_thread_name());
1688     }
1689     HandleMark hm(this);
1690     this->entry_point()(this, this);
1691   }
1692 
1693   DTRACE_THREAD_PROBE(stop, this);
1694 
1695   this->exit(false);
1696   delete this;
1697 }
1698 
1699 
1700 static void ensure_join(JavaThread* thread) {
1701   // We do not need to grap the Threads_lock, since we are operating on ourself.
1702   Handle threadObj(thread, thread->threadObj());
1703   assert(threadObj.not_null(), "java thread object must exist");
1704   ObjectLocker lock(threadObj, thread);
1705   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1706   thread->clear_pending_exception();
1707   // Thread is exiting. So set thread_status field in  java.lang.Thread class to TERMINATED.
1708   java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1709   // Clear the native thread instance - this makes isAlive return false and allows the join()
1710   // to complete once we've done the notify_all below
1711   java_lang_Thread::set_thread(threadObj(), NULL);
1712   lock.notify_all(thread);
1713   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1714   thread->clear_pending_exception();
1715 }
1716 
1717 
1718 // For any new cleanup additions, please check to see if they need to be applied to
1719 // cleanup_failed_attach_current_thread as well.
1720 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1721   assert(this == JavaThread::current(), "thread consistency check");
1722 
1723   HandleMark hm(this);
1724   Handle uncaught_exception(this, this->pending_exception());
1725   this->clear_pending_exception();
1726   Handle threadObj(this, this->threadObj());
1727   assert(threadObj.not_null(), "Java thread object should be created");
1728 
1729   if (get_thread_profiler() != NULL) {
1730     get_thread_profiler()->disengage();
1731     ResourceMark rm;
1732     get_thread_profiler()->print(get_thread_name());
1733   }
1734 
1735 
1736   // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1737   {
1738     EXCEPTION_MARK;
1739 
1740     CLEAR_PENDING_EXCEPTION;
1741   }
1742   if (!destroy_vm) {
1743     if (uncaught_exception.not_null()) {
1744       EXCEPTION_MARK;
1745       // Call method Thread.dispatchUncaughtException().
1746       KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1747       JavaValue result(T_VOID);
1748       JavaCalls::call_virtual(&result,
1749                               threadObj, thread_klass,
1750                               vmSymbols::dispatchUncaughtException_name(),
1751                               vmSymbols::throwable_void_signature(),
1752                               uncaught_exception,
1753                               THREAD);
1754       if (HAS_PENDING_EXCEPTION) {
1755         ResourceMark rm(this);
1756         jio_fprintf(defaultStream::error_stream(),
1757                     "\nException: %s thrown from the UncaughtExceptionHandler"
1758                     " in thread \"%s\"\n",
1759                     pending_exception()->klass()->external_name(),
1760                     get_thread_name());
1761         CLEAR_PENDING_EXCEPTION;
1762       }
1763     }
1764 
1765     // Called before the java thread exit since we want to read info
1766     // from java_lang_Thread object
1767     EventThreadEnd event;
1768     if (event.should_commit()) {
1769       event.set_javalangthread(java_lang_Thread::thread_id(this->threadObj()));
1770       event.commit();
1771     }
1772 
1773     // Call after last event on thread
1774     EVENT_THREAD_EXIT(this);
1775 
1776     // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1777     // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1778     // is deprecated anyhow.
1779     if (!is_Compiler_thread()) {
1780       int count = 3;
1781       while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1782         EXCEPTION_MARK;
1783         JavaValue result(T_VOID);
1784         KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1785         JavaCalls::call_virtual(&result,
1786                                 threadObj, thread_klass,
1787                                 vmSymbols::exit_method_name(),
1788                                 vmSymbols::void_method_signature(),
1789                                 THREAD);
1790         CLEAR_PENDING_EXCEPTION;
1791       }
1792     }
1793     // notify JVMTI
1794     if (JvmtiExport::should_post_thread_life()) {
1795       JvmtiExport::post_thread_end(this);
1796     }
1797 
1798     // We have notified the agents that we are exiting, before we go on,
1799     // we must check for a pending external suspend request and honor it
1800     // in order to not surprise the thread that made the suspend request.
1801     while (true) {
1802       {
1803         MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1804         if (!is_external_suspend()) {
1805           set_terminated(_thread_exiting);
1806           ThreadService::current_thread_exiting(this);
1807           break;
1808         }
1809         // Implied else:
1810         // Things get a little tricky here. We have a pending external
1811         // suspend request, but we are holding the SR_lock so we
1812         // can't just self-suspend. So we temporarily drop the lock
1813         // and then self-suspend.
1814       }
1815 
1816       ThreadBlockInVM tbivm(this);
1817       java_suspend_self();
1818 
1819       // We're done with this suspend request, but we have to loop around
1820       // and check again. Eventually we will get SR_lock without a pending
1821       // external suspend request and will be able to mark ourselves as
1822       // exiting.
1823     }
1824     // no more external suspends are allowed at this point
1825   } else {
1826     // before_exit() has already posted JVMTI THREAD_END events
1827   }
1828 
1829   // Notify waiters on thread object. This has to be done after exit() is called
1830   // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1831   // group should have the destroyed bit set before waiters are notified).
1832   ensure_join(this);
1833   assert(!this->has_pending_exception(), "ensure_join should have cleared");
1834 
1835   // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1836   // held by this thread must be released.  A detach operation must only
1837   // get here if there are no Java frames on the stack.  Therefore, any
1838   // owned monitors at this point MUST be JNI-acquired monitors which are
1839   // pre-inflated and in the monitor cache.
1840   //
1841   // ensure_join() ignores IllegalThreadStateExceptions, and so does this.
1842   if (exit_type == jni_detach && JNIDetachReleasesMonitors) {
1843     assert(!this->has_last_Java_frame(), "detaching with Java frames?");
1844     ObjectSynchronizer::release_monitors_owned_by_thread(this);
1845     assert(!this->has_pending_exception(), "release_monitors should have cleared");
1846   }
1847 
1848   // These things needs to be done while we are still a Java Thread. Make sure that thread
1849   // is in a consistent state, in case GC happens
1850   assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1851 
1852   if (active_handles() != NULL) {
1853     JNIHandleBlock* block = active_handles();
1854     set_active_handles(NULL);
1855     JNIHandleBlock::release_block(block);
1856   }
1857 
1858   if (free_handle_block() != NULL) {
1859     JNIHandleBlock* block = free_handle_block();
1860     set_free_handle_block(NULL);
1861     JNIHandleBlock::release_block(block);
1862   }
1863 
1864   // These have to be removed while this is still a valid thread.
1865   remove_stack_guard_pages();
1866 
1867   if (UseTLAB) {
1868     tlab().make_parsable(true);  // retire TLAB
1869   }
1870 
1871   if (JvmtiEnv::environments_might_exist()) {
1872     JvmtiExport::cleanup_thread(this);
1873   }
1874 
1875   // We must flush any deferred card marks before removing a thread from
1876   // the list of active threads.
1877   Universe::heap()->flush_deferred_store_barrier(this);
1878   assert(deferred_card_mark().is_empty(), "Should have been flushed");
1879 
1880 #if INCLUDE_ALL_GCS
1881   // We must flush the G1-related buffers before removing a thread
1882   // from the list of active threads. We must do this after any deferred
1883   // card marks have been flushed (above) so that any entries that are
1884   // added to the thread's dirty card queue as a result are not lost.
1885   if (UseG1GC) {
1886     flush_barrier_queues();
1887   }
1888 #endif // INCLUDE_ALL_GCS
1889 
1890   // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1891   Threads::remove(this);
1892 }
1893 
1894 #if INCLUDE_ALL_GCS
1895 // Flush G1-related queues.
1896 void JavaThread::flush_barrier_queues() {
1897   satb_mark_queue().flush();
1898   dirty_card_queue().flush();
1899 }
1900 
1901 void JavaThread::initialize_queues() {
1902   assert(!SafepointSynchronize::is_at_safepoint(),
1903          "we should not be at a safepoint");
1904 
1905   ObjPtrQueue& satb_queue = satb_mark_queue();
1906   SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1907   // The SATB queue should have been constructed with its active
1908   // field set to false.
1909   assert(!satb_queue.is_active(), "SATB queue should not be active");
1910   assert(satb_queue.is_empty(), "SATB queue should be empty");
1911   // If we are creating the thread during a marking cycle, we should
1912   // set the active field of the SATB queue to true.
1913   if (satb_queue_set.is_active()) {
1914     satb_queue.set_active(true);
1915   }
1916 
1917   DirtyCardQueue& dirty_queue = dirty_card_queue();
1918   // The dirty card queue should have been constructed with its
1919   // active field set to true.
1920   assert(dirty_queue.is_active(), "dirty card queue should be active");
1921 }
1922 #endif // INCLUDE_ALL_GCS
1923 
1924 void JavaThread::cleanup_failed_attach_current_thread() {
1925   if (get_thread_profiler() != NULL) {
1926     get_thread_profiler()->disengage();
1927     ResourceMark rm;
1928     get_thread_profiler()->print(get_thread_name());
1929   }
1930 
1931   if (active_handles() != NULL) {
1932     JNIHandleBlock* block = active_handles();
1933     set_active_handles(NULL);
1934     JNIHandleBlock::release_block(block);
1935   }
1936 
1937   if (free_handle_block() != NULL) {
1938     JNIHandleBlock* block = free_handle_block();
1939     set_free_handle_block(NULL);
1940     JNIHandleBlock::release_block(block);
1941   }
1942 
1943   // These have to be removed while this is still a valid thread.
1944   remove_stack_guard_pages();
1945 
1946   if (UseTLAB) {
1947     tlab().make_parsable(true);  // retire TLAB, if any
1948   }
1949 
1950 #if INCLUDE_ALL_GCS
1951   if (UseG1GC) {
1952     flush_barrier_queues();
1953   }
1954 #endif // INCLUDE_ALL_GCS
1955 
1956   Threads::remove(this);
1957   delete this;
1958 }
1959 
1960 
1961 
1962 
1963 JavaThread* JavaThread::active() {
1964   Thread* thread = ThreadLocalStorage::thread();
1965   assert(thread != NULL, "just checking");
1966   if (thread->is_Java_thread()) {
1967     return (JavaThread*) thread;
1968   } else {
1969     assert(thread->is_VM_thread(), "this must be a vm thread");
1970     VM_Operation* op = ((VMThread*) thread)->vm_operation();
1971     JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
1972     assert(ret->is_Java_thread(), "must be a Java thread");
1973     return ret;
1974   }
1975 }
1976 
1977 bool JavaThread::is_lock_owned(address adr) const {
1978   if (Thread::is_lock_owned(adr)) return true;
1979 
1980   for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
1981     if (chunk->contains(adr)) return true;
1982   }
1983 
1984   return false;
1985 }
1986 
1987 
1988 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
1989   chunk->set_next(monitor_chunks());
1990   set_monitor_chunks(chunk);
1991 }
1992 
1993 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
1994   guarantee(monitor_chunks() != NULL, "must be non empty");
1995   if (monitor_chunks() == chunk) {
1996     set_monitor_chunks(chunk->next());
1997   } else {
1998     MonitorChunk* prev = monitor_chunks();
1999     while (prev->next() != chunk) prev = prev->next();
2000     prev->set_next(chunk->next());
2001   }
2002 }
2003 
2004 // JVM support.
2005 
2006 // Note: this function shouldn't block if it's called in
2007 // _thread_in_native_trans state (such as from
2008 // check_special_condition_for_native_trans()).
2009 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2010 
2011   if (has_last_Java_frame() && has_async_condition()) {
2012     // If we are at a polling page safepoint (not a poll return)
2013     // then we must defer async exception because live registers
2014     // will be clobbered by the exception path. Poll return is
2015     // ok because the call we a returning from already collides
2016     // with exception handling registers and so there is no issue.
2017     // (The exception handling path kills call result registers but
2018     //  this is ok since the exception kills the result anyway).
2019 
2020     if (is_at_poll_safepoint()) {
2021       // if the code we are returning to has deoptimized we must defer
2022       // the exception otherwise live registers get clobbered on the
2023       // exception path before deoptimization is able to retrieve them.
2024       //
2025       RegisterMap map(this, false);
2026       frame caller_fr = last_frame().sender(&map);
2027       assert(caller_fr.is_compiled_frame(), "what?");
2028       if (caller_fr.is_deoptimized_frame()) {
2029         if (TraceExceptions) {
2030           ResourceMark rm;
2031           tty->print_cr("deferred async exception at compiled safepoint");
2032         }
2033         return;
2034       }
2035     }
2036   }
2037 
2038   JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2039   if (condition == _no_async_condition) {
2040     // Conditions have changed since has_special_runtime_exit_condition()
2041     // was called:
2042     // - if we were here only because of an external suspend request,
2043     //   then that was taken care of above (or cancelled) so we are done
2044     // - if we were here because of another async request, then it has
2045     //   been cleared between the has_special_runtime_exit_condition()
2046     //   and now so again we are done
2047     return;
2048   }
2049 
2050   // Check for pending async. exception
2051   if (_pending_async_exception != NULL) {
2052     // Only overwrite an already pending exception, if it is not a threadDeath.
2053     if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2054 
2055       // We cannot call Exceptions::_throw(...) here because we cannot block
2056       set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2057 
2058       if (TraceExceptions) {
2059         ResourceMark rm;
2060         tty->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", this);
2061         if (has_last_Java_frame()) {
2062           frame f = last_frame();
2063           tty->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", f.pc(), f.sp());
2064         }
2065         tty->print_cr(" of type: %s", InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2066       }
2067       _pending_async_exception = NULL;
2068       clear_has_async_exception();
2069     }
2070   }
2071 
2072   if (check_unsafe_error &&
2073       condition == _async_unsafe_access_error && !has_pending_exception()) {
2074     condition = _no_async_condition;  // done
2075     switch (thread_state()) {
2076     case _thread_in_vm: {
2077       JavaThread* THREAD = this;
2078       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2079     }
2080     case _thread_in_native: {
2081       ThreadInVMfromNative tiv(this);
2082       JavaThread* THREAD = this;
2083       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2084     }
2085     case _thread_in_Java: {
2086       ThreadInVMfromJava tiv(this);
2087       JavaThread* THREAD = this;
2088       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2089     }
2090     default:
2091       ShouldNotReachHere();
2092     }
2093   }
2094 
2095   assert(condition == _no_async_condition || has_pending_exception() ||
2096          (!check_unsafe_error && condition == _async_unsafe_access_error),
2097          "must have handled the async condition, if no exception");
2098 }
2099 
2100 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2101   //
2102   // Check for pending external suspend. Internal suspend requests do
2103   // not use handle_special_runtime_exit_condition().
2104   // If JNIEnv proxies are allowed, don't self-suspend if the target
2105   // thread is not the current thread. In older versions of jdbx, jdbx
2106   // threads could call into the VM with another thread's JNIEnv so we
2107   // can be here operating on behalf of a suspended thread (4432884).
2108   bool do_self_suspend = is_external_suspend_with_lock();
2109   if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2110     //
2111     // Because thread is external suspended the safepoint code will count
2112     // thread as at a safepoint. This can be odd because we can be here
2113     // as _thread_in_Java which would normally transition to _thread_blocked
2114     // at a safepoint. We would like to mark the thread as _thread_blocked
2115     // before calling java_suspend_self like all other callers of it but
2116     // we must then observe proper safepoint protocol. (We can't leave
2117     // _thread_blocked with a safepoint in progress). However we can be
2118     // here as _thread_in_native_trans so we can't use a normal transition
2119     // constructor/destructor pair because they assert on that type of
2120     // transition. We could do something like:
2121     //
2122     // JavaThreadState state = thread_state();
2123     // set_thread_state(_thread_in_vm);
2124     // {
2125     //   ThreadBlockInVM tbivm(this);
2126     //   java_suspend_self()
2127     // }
2128     // set_thread_state(_thread_in_vm_trans);
2129     // if (safepoint) block;
2130     // set_thread_state(state);
2131     //
2132     // but that is pretty messy. Instead we just go with the way the
2133     // code has worked before and note that this is the only path to
2134     // java_suspend_self that doesn't put the thread in _thread_blocked
2135     // mode.
2136 
2137     frame_anchor()->make_walkable(this);
2138     java_suspend_self();
2139 
2140     // We might be here for reasons in addition to the self-suspend request
2141     // so check for other async requests.
2142   }
2143 
2144   if (check_asyncs) {
2145     check_and_handle_async_exceptions();
2146   }
2147 }
2148 
2149 void JavaThread::send_thread_stop(oop java_throwable)  {
2150   assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2151   assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2152   assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2153 
2154   // Do not throw asynchronous exceptions against the compiler thread
2155   // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2156   if (is_Compiler_thread()) return;
2157 
2158   {
2159     // Actually throw the Throwable against the target Thread - however
2160     // only if there is no thread death exception installed already.
2161     if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2162       // If the topmost frame is a runtime stub, then we are calling into
2163       // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2164       // must deoptimize the caller before continuing, as the compiled  exception handler table
2165       // may not be valid
2166       if (has_last_Java_frame()) {
2167         frame f = last_frame();
2168         if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2169           // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2170           RegisterMap reg_map(this, UseBiasedLocking);
2171           frame compiled_frame = f.sender(&reg_map);
2172           if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2173             Deoptimization::deoptimize(this, compiled_frame, &reg_map);
2174           }
2175         }
2176       }
2177 
2178       // Set async. pending exception in thread.
2179       set_pending_async_exception(java_throwable);
2180 
2181       if (TraceExceptions) {
2182         ResourceMark rm;
2183         tty->print_cr("Pending Async. exception installed of type: %s", InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2184       }
2185       // for AbortVMOnException flag
2186       NOT_PRODUCT(Exceptions::debug_check_abort(InstanceKlass::cast(_pending_async_exception->klass())->external_name()));
2187     }
2188   }
2189 
2190 
2191   // Interrupt thread so it will wake up from a potential wait()
2192   Thread::interrupt(this);
2193 }
2194 
2195 // External suspension mechanism.
2196 //
2197 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2198 // to any VM_locks and it is at a transition
2199 // Self-suspension will happen on the transition out of the vm.
2200 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2201 //
2202 // Guarantees on return:
2203 //   + Target thread will not execute any new bytecode (that's why we need to
2204 //     force a safepoint)
2205 //   + Target thread will not enter any new monitors
2206 //
2207 void JavaThread::java_suspend() {
2208   { MutexLocker mu(Threads_lock);
2209     if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2210       return;
2211     }
2212   }
2213 
2214   { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2215     if (!is_external_suspend()) {
2216       // a racing resume has cancelled us; bail out now
2217       return;
2218     }
2219 
2220     // suspend is done
2221     uint32_t debug_bits = 0;
2222     // Warning: is_ext_suspend_completed() may temporarily drop the
2223     // SR_lock to allow the thread to reach a stable thread state if
2224     // it is currently in a transient thread state.
2225     if (is_ext_suspend_completed(false /* !called_by_wait */,
2226                                  SuspendRetryDelay, &debug_bits)) {
2227       return;
2228     }
2229   }
2230 
2231   VM_ForceSafepoint vm_suspend;
2232   VMThread::execute(&vm_suspend);
2233 }
2234 
2235 // Part II of external suspension.
2236 // A JavaThread self suspends when it detects a pending external suspend
2237 // request. This is usually on transitions. It is also done in places
2238 // where continuing to the next transition would surprise the caller,
2239 // e.g., monitor entry.
2240 //
2241 // Returns the number of times that the thread self-suspended.
2242 //
2243 // Note: DO NOT call java_suspend_self() when you just want to block current
2244 //       thread. java_suspend_self() is the second stage of cooperative
2245 //       suspension for external suspend requests and should only be used
2246 //       to complete an external suspend request.
2247 //
2248 int JavaThread::java_suspend_self() {
2249   int ret = 0;
2250 
2251   // we are in the process of exiting so don't suspend
2252   if (is_exiting()) {
2253     clear_external_suspend();
2254     return ret;
2255   }
2256 
2257   assert(_anchor.walkable() ||
2258          (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2259          "must have walkable stack");
2260 
2261   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2262 
2263   assert(!this->is_ext_suspended(),
2264          "a thread trying to self-suspend should not already be suspended");
2265 
2266   if (this->is_suspend_equivalent()) {
2267     // If we are self-suspending as a result of the lifting of a
2268     // suspend equivalent condition, then the suspend_equivalent
2269     // flag is not cleared until we set the ext_suspended flag so
2270     // that wait_for_ext_suspend_completion() returns consistent
2271     // results.
2272     this->clear_suspend_equivalent();
2273   }
2274 
2275   // A racing resume may have cancelled us before we grabbed SR_lock
2276   // above. Or another external suspend request could be waiting for us
2277   // by the time we return from SR_lock()->wait(). The thread
2278   // that requested the suspension may already be trying to walk our
2279   // stack and if we return now, we can change the stack out from under
2280   // it. This would be a "bad thing (TM)" and cause the stack walker
2281   // to crash. We stay self-suspended until there are no more pending
2282   // external suspend requests.
2283   while (is_external_suspend()) {
2284     ret++;
2285     this->set_ext_suspended();
2286 
2287     // _ext_suspended flag is cleared by java_resume()
2288     while (is_ext_suspended()) {
2289       this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2290     }
2291   }
2292 
2293   return ret;
2294 }
2295 
2296 #ifdef ASSERT
2297 // verify the JavaThread has not yet been published in the Threads::list, and
2298 // hence doesn't need protection from concurrent access at this stage
2299 void JavaThread::verify_not_published() {
2300   if (!Threads_lock->owned_by_self()) {
2301     MutexLockerEx ml(Threads_lock,  Mutex::_no_safepoint_check_flag);
2302     assert(!Threads::includes(this),
2303            "java thread shouldn't have been published yet!");
2304   } else {
2305     assert(!Threads::includes(this),
2306            "java thread shouldn't have been published yet!");
2307   }
2308 }
2309 #endif
2310 
2311 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2312 // progress or when _suspend_flags is non-zero.
2313 // Current thread needs to self-suspend if there is a suspend request and/or
2314 // block if a safepoint is in progress.
2315 // Async exception ISN'T checked.
2316 // Note only the ThreadInVMfromNative transition can call this function
2317 // directly and when thread state is _thread_in_native_trans
2318 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2319   assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2320 
2321   JavaThread *curJT = JavaThread::current();
2322   bool do_self_suspend = thread->is_external_suspend();
2323 
2324   assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2325 
2326   // If JNIEnv proxies are allowed, don't self-suspend if the target
2327   // thread is not the current thread. In older versions of jdbx, jdbx
2328   // threads could call into the VM with another thread's JNIEnv so we
2329   // can be here operating on behalf of a suspended thread (4432884).
2330   if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2331     JavaThreadState state = thread->thread_state();
2332 
2333     // We mark this thread_blocked state as a suspend-equivalent so
2334     // that a caller to is_ext_suspend_completed() won't be confused.
2335     // The suspend-equivalent state is cleared by java_suspend_self().
2336     thread->set_suspend_equivalent();
2337 
2338     // If the safepoint code sees the _thread_in_native_trans state, it will
2339     // wait until the thread changes to other thread state. There is no
2340     // guarantee on how soon we can obtain the SR_lock and complete the
2341     // self-suspend request. It would be a bad idea to let safepoint wait for
2342     // too long. Temporarily change the state to _thread_blocked to
2343     // let the VM thread know that this thread is ready for GC. The problem
2344     // of changing thread state is that safepoint could happen just after
2345     // java_suspend_self() returns after being resumed, and VM thread will
2346     // see the _thread_blocked state. We must check for safepoint
2347     // after restoring the state and make sure we won't leave while a safepoint
2348     // is in progress.
2349     thread->set_thread_state(_thread_blocked);
2350     thread->java_suspend_self();
2351     thread->set_thread_state(state);
2352     // Make sure new state is seen by VM thread
2353     if (os::is_MP()) {
2354       if (UseMembar) {
2355         // Force a fence between the write above and read below
2356         OrderAccess::fence();
2357       } else {
2358         // Must use this rather than serialization page in particular on Windows
2359         InterfaceSupport::serialize_memory(thread);
2360       }
2361     }
2362   }
2363 
2364   if (SafepointSynchronize::do_call_back()) {
2365     // If we are safepointing, then block the caller which may not be
2366     // the same as the target thread (see above).
2367     SafepointSynchronize::block(curJT);
2368   }
2369 
2370   if (thread->is_deopt_suspend()) {
2371     thread->clear_deopt_suspend();
2372     RegisterMap map(thread, false);
2373     frame f = thread->last_frame();
2374     while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2375       f = f.sender(&map);
2376     }
2377     if (f.id() == thread->must_deopt_id()) {
2378       thread->clear_must_deopt_id();
2379       f.deoptimize(thread);
2380     } else {
2381       fatal("missed deoptimization!");
2382     }
2383   }
2384 }
2385 
2386 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2387 // progress or when _suspend_flags is non-zero.
2388 // Current thread needs to self-suspend if there is a suspend request and/or
2389 // block if a safepoint is in progress.
2390 // Also check for pending async exception (not including unsafe access error).
2391 // Note only the native==>VM/Java barriers can call this function and when
2392 // thread state is _thread_in_native_trans.
2393 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2394   check_safepoint_and_suspend_for_native_trans(thread);
2395 
2396   if (thread->has_async_exception()) {
2397     // We are in _thread_in_native_trans state, don't handle unsafe
2398     // access error since that may block.
2399     thread->check_and_handle_async_exceptions(false);
2400   }
2401 }
2402 
2403 // This is a variant of the normal
2404 // check_special_condition_for_native_trans with slightly different
2405 // semantics for use by critical native wrappers.  It does all the
2406 // normal checks but also performs the transition back into
2407 // thread_in_Java state.  This is required so that critical natives
2408 // can potentially block and perform a GC if they are the last thread
2409 // exiting the GC_locker.
2410 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2411   check_special_condition_for_native_trans(thread);
2412 
2413   // Finish the transition
2414   thread->set_thread_state(_thread_in_Java);
2415 
2416   if (thread->do_critical_native_unlock()) {
2417     ThreadInVMfromJavaNoAsyncException tiv(thread);
2418     GC_locker::unlock_critical(thread);
2419     thread->clear_critical_native_unlock();
2420   }
2421 }
2422 
2423 // We need to guarantee the Threads_lock here, since resumes are not
2424 // allowed during safepoint synchronization
2425 // Can only resume from an external suspension
2426 void JavaThread::java_resume() {
2427   assert_locked_or_safepoint(Threads_lock);
2428 
2429   // Sanity check: thread is gone, has started exiting or the thread
2430   // was not externally suspended.
2431   if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2432     return;
2433   }
2434 
2435   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2436 
2437   clear_external_suspend();
2438 
2439   if (is_ext_suspended()) {
2440     clear_ext_suspended();
2441     SR_lock()->notify_all();
2442   }
2443 }
2444 
2445 void JavaThread::create_stack_guard_pages() {
2446   if (! os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) return;
2447   address low_addr = stack_base() - stack_size();
2448   size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
2449 
2450   int allocate = os::allocate_stack_guard_pages();
2451   // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2452 
2453   if (allocate && !os::create_stack_guard_pages((char *) low_addr, len)) {
2454     warning("Attempt to allocate stack guard pages failed.");
2455     return;
2456   }
2457 
2458   if (os::guard_memory((char *) low_addr, len)) {
2459     _stack_guard_state = stack_guard_enabled;
2460   } else {
2461     warning("Attempt to protect stack guard pages failed.");
2462     if (os::uncommit_memory((char *) low_addr, len)) {
2463       warning("Attempt to deallocate stack guard pages failed.");
2464     }
2465   }
2466 }
2467 
2468 void JavaThread::remove_stack_guard_pages() {
2469   assert(Thread::current() == this, "from different thread");
2470   if (_stack_guard_state == stack_guard_unused) return;
2471   address low_addr = stack_base() - stack_size();
2472   size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
2473 
2474   if (os::allocate_stack_guard_pages()) {
2475     if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2476       _stack_guard_state = stack_guard_unused;
2477     } else {
2478       warning("Attempt to deallocate stack guard pages failed.");
2479     }
2480   } else {
2481     if (_stack_guard_state == stack_guard_unused) return;
2482     if (os::unguard_memory((char *) low_addr, len)) {
2483       _stack_guard_state = stack_guard_unused;
2484     } else {
2485       warning("Attempt to unprotect stack guard pages failed.");
2486     }
2487   }
2488 }
2489 
2490 void JavaThread::enable_stack_yellow_zone() {
2491   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2492   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2493 
2494   // The base notation is from the stacks point of view, growing downward.
2495   // We need to adjust it to work correctly with guard_memory()
2496   address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2497 
2498   guarantee(base < stack_base(), "Error calculating stack yellow zone");
2499   guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2500 
2501   if (os::guard_memory((char *) base, stack_yellow_zone_size())) {
2502     _stack_guard_state = stack_guard_enabled;
2503   } else {
2504     warning("Attempt to guard stack yellow zone failed.");
2505   }
2506   enable_register_stack_guard();
2507 }
2508 
2509 void JavaThread::disable_stack_yellow_zone() {
2510   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2511   assert(_stack_guard_state != stack_guard_yellow_disabled, "already disabled");
2512 
2513   // Simply return if called for a thread that does not use guard pages.
2514   if (_stack_guard_state == stack_guard_unused) return;
2515 
2516   // The base notation is from the stacks point of view, growing downward.
2517   // We need to adjust it to work correctly with guard_memory()
2518   address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2519 
2520   if (os::unguard_memory((char *)base, stack_yellow_zone_size())) {
2521     _stack_guard_state = stack_guard_yellow_disabled;
2522   } else {
2523     warning("Attempt to unguard stack yellow zone failed.");
2524   }
2525   disable_register_stack_guard();
2526 }
2527 
2528 void JavaThread::enable_stack_red_zone() {
2529   // The base notation is from the stacks point of view, growing downward.
2530   // We need to adjust it to work correctly with guard_memory()
2531   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2532   address base = stack_red_zone_base() - stack_red_zone_size();
2533 
2534   guarantee(base < stack_base(), "Error calculating stack red zone");
2535   guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2536 
2537   if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2538     warning("Attempt to guard stack red zone failed.");
2539   }
2540 }
2541 
2542 void JavaThread::disable_stack_red_zone() {
2543   // The base notation is from the stacks point of view, growing downward.
2544   // We need to adjust it to work correctly with guard_memory()
2545   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2546   address base = stack_red_zone_base() - stack_red_zone_size();
2547   if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2548     warning("Attempt to unguard stack red zone failed.");
2549   }
2550 }
2551 
2552 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2553   // ignore is there is no stack
2554   if (!has_last_Java_frame()) return;
2555   // traverse the stack frames. Starts from top frame.
2556   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2557     frame* fr = fst.current();
2558     f(fr, fst.register_map());
2559   }
2560 }
2561 
2562 
2563 #ifndef PRODUCT
2564 // Deoptimization
2565 // Function for testing deoptimization
2566 void JavaThread::deoptimize() {
2567   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2568   StackFrameStream fst(this, UseBiasedLocking);
2569   bool deopt = false;           // Dump stack only if a deopt actually happens.
2570   bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2571   // Iterate over all frames in the thread and deoptimize
2572   for (; !fst.is_done(); fst.next()) {
2573     if (fst.current()->can_be_deoptimized()) {
2574 
2575       if (only_at) {
2576         // Deoptimize only at particular bcis.  DeoptimizeOnlyAt
2577         // consists of comma or carriage return separated numbers so
2578         // search for the current bci in that string.
2579         address pc = fst.current()->pc();
2580         nmethod* nm =  (nmethod*) fst.current()->cb();
2581         ScopeDesc* sd = nm->scope_desc_at(pc);
2582         char buffer[8];
2583         jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2584         size_t len = strlen(buffer);
2585         const char * found = strstr(DeoptimizeOnlyAt, buffer);
2586         while (found != NULL) {
2587           if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2588               (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2589             // Check that the bci found is bracketed by terminators.
2590             break;
2591           }
2592           found = strstr(found + 1, buffer);
2593         }
2594         if (!found) {
2595           continue;
2596         }
2597       }
2598 
2599       if (DebugDeoptimization && !deopt) {
2600         deopt = true; // One-time only print before deopt
2601         tty->print_cr("[BEFORE Deoptimization]");
2602         trace_frames();
2603         trace_stack();
2604       }
2605       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2606     }
2607   }
2608 
2609   if (DebugDeoptimization && deopt) {
2610     tty->print_cr("[AFTER Deoptimization]");
2611     trace_frames();
2612   }
2613 }
2614 
2615 
2616 // Make zombies
2617 void JavaThread::make_zombies() {
2618   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2619     if (fst.current()->can_be_deoptimized()) {
2620       // it is a Java nmethod
2621       nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2622       nm->make_not_entrant();
2623     }
2624   }
2625 }
2626 #endif // PRODUCT
2627 
2628 
2629 void JavaThread::deoptimized_wrt_marked_nmethods() {
2630   if (!has_last_Java_frame()) return;
2631   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2632   StackFrameStream fst(this, UseBiasedLocking);
2633   for (; !fst.is_done(); fst.next()) {
2634     if (fst.current()->should_be_deoptimized()) {
2635       if (LogCompilation && xtty != NULL) {
2636         nmethod* nm = fst.current()->cb()->as_nmethod_or_null();
2637         xtty->elem("deoptimized thread='" UINTX_FORMAT "' compile_id='%d'",
2638                    this->name(), nm != NULL ? nm->compile_id() : -1);
2639       }
2640 
2641       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2642     }
2643   }
2644 }
2645 
2646 
2647 // If the caller is a NamedThread, then remember, in the current scope,
2648 // the given JavaThread in its _processed_thread field.
2649 class RememberProcessedThread: public StackObj {
2650   NamedThread* _cur_thr;
2651  public:
2652   RememberProcessedThread(JavaThread* jthr) {
2653     Thread* thread = Thread::current();
2654     if (thread->is_Named_thread()) {
2655       _cur_thr = (NamedThread *)thread;
2656       _cur_thr->set_processed_thread(jthr);
2657     } else {
2658       _cur_thr = NULL;
2659     }
2660   }
2661 
2662   ~RememberProcessedThread() {
2663     if (_cur_thr) {
2664       _cur_thr->set_processed_thread(NULL);
2665     }
2666   }
2667 };
2668 
2669 void JavaThread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
2670   // Verify that the deferred card marks have been flushed.
2671   assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2672 
2673   // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2674   // since there may be more than one thread using each ThreadProfiler.
2675 
2676   // Traverse the GCHandles
2677   Thread::oops_do(f, cld_f, cf);
2678 
2679   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2680          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2681 
2682   if (has_last_Java_frame()) {
2683     // Record JavaThread to GC thread
2684     RememberProcessedThread rpt(this);
2685 
2686     // Traverse the privileged stack
2687     if (_privileged_stack_top != NULL) {
2688       _privileged_stack_top->oops_do(f);
2689     }
2690 
2691     // traverse the registered growable array
2692     if (_array_for_gc != NULL) {
2693       for (int index = 0; index < _array_for_gc->length(); index++) {
2694         f->do_oop(_array_for_gc->adr_at(index));
2695       }
2696     }
2697 
2698     // Traverse the monitor chunks
2699     for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2700       chunk->oops_do(f);
2701     }
2702 
2703     // Traverse the execution stack
2704     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2705       fst.current()->oops_do(f, cld_f, cf, fst.register_map());
2706     }
2707   }
2708 
2709   // callee_target is never live across a gc point so NULL it here should
2710   // it still contain a methdOop.
2711 
2712   set_callee_target(NULL);
2713 
2714   assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2715   // If we have deferred set_locals there might be oops waiting to be
2716   // written
2717   GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2718   if (list != NULL) {
2719     for (int i = 0; i < list->length(); i++) {
2720       list->at(i)->oops_do(f);
2721     }
2722   }
2723 
2724   // Traverse instance variables at the end since the GC may be moving things
2725   // around using this function
2726   f->do_oop((oop*) &_threadObj);
2727   f->do_oop((oop*) &_vm_result);
2728   f->do_oop((oop*) &_exception_oop);
2729   f->do_oop((oop*) &_pending_async_exception);
2730 
2731   if (jvmti_thread_state() != NULL) {
2732     jvmti_thread_state()->oops_do(f);
2733   }
2734 }
2735 
2736 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2737   Thread::nmethods_do(cf);  // (super method is a no-op)
2738 
2739   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2740          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2741 
2742   if (has_last_Java_frame()) {
2743     // Traverse the execution stack
2744     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2745       fst.current()->nmethods_do(cf);
2746     }
2747   }
2748 }
2749 
2750 void JavaThread::metadata_do(void f(Metadata*)) {
2751   Thread::metadata_do(f);
2752   if (has_last_Java_frame()) {
2753     // Traverse the execution stack to call f() on the methods in the stack
2754     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2755       fst.current()->metadata_do(f);
2756     }
2757   } else if (is_Compiler_thread()) {
2758     // need to walk ciMetadata in current compile tasks to keep alive.
2759     CompilerThread* ct = (CompilerThread*)this;
2760     if (ct->env() != NULL) {
2761       ct->env()->metadata_do(f);
2762     }
2763   }
2764 }
2765 
2766 // Printing
2767 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2768   switch (_thread_state) {
2769   case _thread_uninitialized:     return "_thread_uninitialized";
2770   case _thread_new:               return "_thread_new";
2771   case _thread_new_trans:         return "_thread_new_trans";
2772   case _thread_in_native:         return "_thread_in_native";
2773   case _thread_in_native_trans:   return "_thread_in_native_trans";
2774   case _thread_in_vm:             return "_thread_in_vm";
2775   case _thread_in_vm_trans:       return "_thread_in_vm_trans";
2776   case _thread_in_Java:           return "_thread_in_Java";
2777   case _thread_in_Java_trans:     return "_thread_in_Java_trans";
2778   case _thread_blocked:           return "_thread_blocked";
2779   case _thread_blocked_trans:     return "_thread_blocked_trans";
2780   default:                        return "unknown thread state";
2781   }
2782 }
2783 
2784 #ifndef PRODUCT
2785 void JavaThread::print_thread_state_on(outputStream *st) const {
2786   st->print_cr("   JavaThread state: %s", _get_thread_state_name(_thread_state));
2787 };
2788 void JavaThread::print_thread_state() const {
2789   print_thread_state_on(tty);
2790 }
2791 #endif // PRODUCT
2792 
2793 // Called by Threads::print() for VM_PrintThreads operation
2794 void JavaThread::print_on(outputStream *st) const {
2795   st->print("\"%s\" ", get_thread_name());
2796   oop thread_oop = threadObj();
2797   if (thread_oop != NULL) {
2798     st->print("#" INT64_FORMAT " ", java_lang_Thread::thread_id(thread_oop));
2799     if (java_lang_Thread::is_daemon(thread_oop))  st->print("daemon ");
2800     st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2801   }
2802   Thread::print_on(st);
2803   // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2804   st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2805   if (thread_oop != NULL) {
2806     st->print_cr("   java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2807   }
2808 #ifndef PRODUCT
2809   print_thread_state_on(st);
2810   _safepoint_state->print_on(st);
2811 #endif // PRODUCT
2812 }
2813 
2814 // Called by fatal error handler. The difference between this and
2815 // JavaThread::print() is that we can't grab lock or allocate memory.
2816 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2817   st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2818   oop thread_obj = threadObj();
2819   if (thread_obj != NULL) {
2820     if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2821   }
2822   st->print(" [");
2823   st->print("%s", _get_thread_state_name(_thread_state));
2824   if (osthread()) {
2825     st->print(", id=%d", osthread()->thread_id());
2826   }
2827   st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2828             _stack_base - _stack_size, _stack_base);
2829   st->print("]");
2830   return;
2831 }
2832 
2833 // Verification
2834 
2835 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2836 
2837 void JavaThread::verify() {
2838   // Verify oops in the thread.
2839   oops_do(&VerifyOopClosure::verify_oop, NULL, NULL);
2840 
2841   // Verify the stack frames.
2842   frames_do(frame_verify);
2843 }
2844 
2845 // CR 6300358 (sub-CR 2137150)
2846 // Most callers of this method assume that it can't return NULL but a
2847 // thread may not have a name whilst it is in the process of attaching to
2848 // the VM - see CR 6412693, and there are places where a JavaThread can be
2849 // seen prior to having it's threadObj set (eg JNI attaching threads and
2850 // if vm exit occurs during initialization). These cases can all be accounted
2851 // for such that this method never returns NULL.
2852 const char* JavaThread::get_thread_name() const {
2853 #ifdef ASSERT
2854   // early safepoints can hit while current thread does not yet have TLS
2855   if (!SafepointSynchronize::is_at_safepoint()) {
2856     Thread *cur = Thread::current();
2857     if (!(cur->is_Java_thread() && cur == this)) {
2858       // Current JavaThreads are allowed to get their own name without
2859       // the Threads_lock.
2860       assert_locked_or_safepoint(Threads_lock);
2861     }
2862   }
2863 #endif // ASSERT
2864   return get_thread_name_string();
2865 }
2866 
2867 // Returns a non-NULL representation of this thread's name, or a suitable
2868 // descriptive string if there is no set name
2869 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
2870   const char* name_str;
2871   oop thread_obj = threadObj();
2872   if (thread_obj != NULL) {
2873     oop name = java_lang_Thread::name(thread_obj);
2874     if (name != NULL) {
2875       if (buf == NULL) {
2876         name_str = java_lang_String::as_utf8_string(name);

2877       } else {
2878         name_str = java_lang_String::as_utf8_string(name, buf, buflen);

2879       }
2880     } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
2881       name_str = "<no-name - thread is attaching>";
2882     } else {
2883       name_str = Thread::name();
2884     }
2885   } else {
2886     name_str = Thread::name();
2887   }
2888   assert(name_str != NULL, "unexpected NULL thread name");
2889   return name_str;
2890 }
2891 
2892 
2893 const char* JavaThread::get_threadgroup_name() const {
2894   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2895   oop thread_obj = threadObj();
2896   if (thread_obj != NULL) {
2897     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2898     if (thread_group != NULL) {
2899       typeArrayOop name = java_lang_ThreadGroup::name(thread_group);
2900       // ThreadGroup.name can be null
2901       if (name != NULL) {
2902         const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2903         return str;
2904       }
2905     }
2906   }
2907   return NULL;
2908 }
2909 
2910 const char* JavaThread::get_parent_name() const {
2911   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2912   oop thread_obj = threadObj();
2913   if (thread_obj != NULL) {
2914     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2915     if (thread_group != NULL) {
2916       oop parent = java_lang_ThreadGroup::parent(thread_group);
2917       if (parent != NULL) {
2918         typeArrayOop name = java_lang_ThreadGroup::name(parent);
2919         // ThreadGroup.name can be null
2920         if (name != NULL) {
2921           const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2922           return str;
2923         }
2924       }
2925     }
2926   }
2927   return NULL;
2928 }
2929 
2930 ThreadPriority JavaThread::java_priority() const {
2931   oop thr_oop = threadObj();
2932   if (thr_oop == NULL) return NormPriority; // Bootstrapping
2933   ThreadPriority priority = java_lang_Thread::priority(thr_oop);
2934   assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
2935   return priority;
2936 }
2937 
2938 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
2939 
2940   assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
2941   // Link Java Thread object <-> C++ Thread
2942 
2943   // Get the C++ thread object (an oop) from the JNI handle (a jthread)
2944   // and put it into a new Handle.  The Handle "thread_oop" can then
2945   // be used to pass the C++ thread object to other methods.
2946 
2947   // Set the Java level thread object (jthread) field of the
2948   // new thread (a JavaThread *) to C++ thread object using the
2949   // "thread_oop" handle.
2950 
2951   // Set the thread field (a JavaThread *) of the
2952   // oop representing the java_lang_Thread to the new thread (a JavaThread *).
2953 
2954   Handle thread_oop(Thread::current(),
2955                     JNIHandles::resolve_non_null(jni_thread));
2956   assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
2957          "must be initialized");
2958   set_threadObj(thread_oop());
2959   java_lang_Thread::set_thread(thread_oop(), this);
2960 
2961   if (prio == NoPriority) {
2962     prio = java_lang_Thread::priority(thread_oop());
2963     assert(prio != NoPriority, "A valid priority should be present");
2964   }
2965 
2966   // Push the Java priority down to the native thread; needs Threads_lock
2967   Thread::set_priority(this, prio);
2968 
2969   prepare_ext();
2970 
2971   // Add the new thread to the Threads list and set it in motion.
2972   // We must have threads lock in order to call Threads::add.
2973   // It is crucial that we do not block before the thread is
2974   // added to the Threads list for if a GC happens, then the java_thread oop
2975   // will not be visited by GC.
2976   Threads::add(this);
2977 }
2978 
2979 oop JavaThread::current_park_blocker() {
2980   // Support for JSR-166 locks
2981   oop thread_oop = threadObj();
2982   if (thread_oop != NULL &&
2983       JDK_Version::current().supports_thread_park_blocker()) {
2984     return java_lang_Thread::park_blocker(thread_oop);
2985   }
2986   return NULL;
2987 }
2988 
2989 
2990 void JavaThread::print_stack_on(outputStream* st) {
2991   if (!has_last_Java_frame()) return;
2992   ResourceMark rm;
2993   HandleMark   hm;
2994 
2995   RegisterMap reg_map(this);
2996   vframe* start_vf = last_java_vframe(&reg_map);
2997   int count = 0;
2998   for (vframe* f = start_vf; f; f = f->sender()) {
2999     if (f->is_java_frame()) {
3000       javaVFrame* jvf = javaVFrame::cast(f);
3001       java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3002 
3003       // Print out lock information
3004       if (JavaMonitorsInStackTrace) {
3005         jvf->print_lock_info_on(st, count);
3006       }
3007     } else {
3008       // Ignore non-Java frames
3009     }
3010 
3011     // Bail-out case for too deep stacks
3012     count++;
3013     if (MaxJavaStackTraceDepth == count) return;
3014   }
3015 }
3016 
3017 
3018 // JVMTI PopFrame support
3019 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3020   assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3021   if (in_bytes(size_in_bytes) != 0) {
3022     _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3023     _popframe_preserved_args_size = in_bytes(size_in_bytes);
3024     Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3025   }
3026 }
3027 
3028 void* JavaThread::popframe_preserved_args() {
3029   return _popframe_preserved_args;
3030 }
3031 
3032 ByteSize JavaThread::popframe_preserved_args_size() {
3033   return in_ByteSize(_popframe_preserved_args_size);
3034 }
3035 
3036 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3037   int sz = in_bytes(popframe_preserved_args_size());
3038   assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3039   return in_WordSize(sz / wordSize);
3040 }
3041 
3042 void JavaThread::popframe_free_preserved_args() {
3043   assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3044   FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args, mtThread);
3045   _popframe_preserved_args = NULL;
3046   _popframe_preserved_args_size = 0;
3047 }
3048 
3049 #ifndef PRODUCT
3050 
3051 void JavaThread::trace_frames() {
3052   tty->print_cr("[Describe stack]");
3053   int frame_no = 1;
3054   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3055     tty->print("  %d. ", frame_no++);
3056     fst.current()->print_value_on(tty, this);
3057     tty->cr();
3058   }
3059 }
3060 
3061 class PrintAndVerifyOopClosure: public OopClosure {
3062  protected:
3063   template <class T> inline void do_oop_work(T* p) {
3064     oop obj = oopDesc::load_decode_heap_oop(p);
3065     if (obj == NULL) return;
3066     tty->print(INTPTR_FORMAT ": ", p);
3067     if (obj->is_oop_or_null()) {
3068       if (obj->is_objArray()) {
3069         tty->print_cr("valid objArray: " INTPTR_FORMAT, (oopDesc*) obj);
3070       } else {
3071         obj->print();
3072       }
3073     } else {
3074       tty->print_cr("invalid oop: " INTPTR_FORMAT, (oopDesc*) obj);
3075     }
3076     tty->cr();
3077   }
3078  public:
3079   virtual void do_oop(oop* p) { do_oop_work(p); }
3080   virtual void do_oop(narrowOop* p)  { do_oop_work(p); }
3081 };
3082 
3083 
3084 static void oops_print(frame* f, const RegisterMap *map) {
3085   PrintAndVerifyOopClosure print;
3086   f->print_value();
3087   f->oops_do(&print, NULL, NULL, (RegisterMap*)map);
3088 }
3089 
3090 // Print our all the locations that contain oops and whether they are
3091 // valid or not.  This useful when trying to find the oldest frame
3092 // where an oop has gone bad since the frame walk is from youngest to
3093 // oldest.
3094 void JavaThread::trace_oops() {
3095   tty->print_cr("[Trace oops]");
3096   frames_do(oops_print);
3097 }
3098 
3099 
3100 #ifdef ASSERT
3101 // Print or validate the layout of stack frames
3102 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3103   ResourceMark rm;
3104   PRESERVE_EXCEPTION_MARK;
3105   FrameValues values;
3106   int frame_no = 0;
3107   for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3108     fst.current()->describe(values, ++frame_no);
3109     if (depth == frame_no) break;
3110   }
3111   if (validate_only) {
3112     values.validate();
3113   } else {
3114     tty->print_cr("[Describe stack layout]");
3115     values.print(this);
3116   }
3117 }
3118 #endif
3119 
3120 void JavaThread::trace_stack_from(vframe* start_vf) {
3121   ResourceMark rm;
3122   int vframe_no = 1;
3123   for (vframe* f = start_vf; f; f = f->sender()) {
3124     if (f->is_java_frame()) {
3125       javaVFrame::cast(f)->print_activation(vframe_no++);
3126     } else {
3127       f->print();
3128     }
3129     if (vframe_no > StackPrintLimit) {
3130       tty->print_cr("...<more frames>...");
3131       return;
3132     }
3133   }
3134 }
3135 
3136 
3137 void JavaThread::trace_stack() {
3138   if (!has_last_Java_frame()) return;
3139   ResourceMark rm;
3140   HandleMark   hm;
3141   RegisterMap reg_map(this);
3142   trace_stack_from(last_java_vframe(&reg_map));
3143 }
3144 
3145 
3146 #endif // PRODUCT
3147 
3148 
3149 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3150   assert(reg_map != NULL, "a map must be given");
3151   frame f = last_frame();
3152   for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3153     if (vf->is_java_frame()) return javaVFrame::cast(vf);
3154   }
3155   return NULL;
3156 }
3157 
3158 
3159 Klass* JavaThread::security_get_caller_class(int depth) {
3160   vframeStream vfst(this);
3161   vfst.security_get_caller_frame(depth);
3162   if (!vfst.at_end()) {
3163     return vfst.method()->method_holder();
3164   }
3165   return NULL;
3166 }
3167 
3168 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3169   assert(thread->is_Compiler_thread(), "must be compiler thread");
3170   CompileBroker::compiler_thread_loop();
3171 }
3172 
3173 // Create a CompilerThread
3174 CompilerThread::CompilerThread(CompileQueue* queue,
3175                                CompilerCounters* counters)
3176                                : JavaThread(&compiler_thread_entry) {
3177   _env   = NULL;
3178   _log   = NULL;
3179   _task  = NULL;
3180   _queue = queue;
3181   _counters = counters;
3182   _buffer_blob = NULL;
3183   _scanned_nmethod = NULL;
3184   _compiler = NULL;
3185 
3186 #ifndef PRODUCT
3187   _ideal_graph_printer = NULL;
3188 #endif
3189 }
3190 
3191 void CompilerThread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
3192   JavaThread::oops_do(f, cld_f, cf);
3193   if (_scanned_nmethod != NULL && cf != NULL) {
3194     // Safepoints can occur when the sweeper is scanning an nmethod so
3195     // process it here to make sure it isn't unloaded in the middle of
3196     // a scan.
3197     cf->do_code_blob(_scanned_nmethod);
3198   }
3199 }
3200 
3201 
3202 // ======= Threads ========
3203 
3204 // The Threads class links together all active threads, and provides
3205 // operations over all threads.  It is protected by its own Mutex
3206 // lock, which is also used in other contexts to protect thread
3207 // operations from having the thread being operated on from exiting
3208 // and going away unexpectedly (e.g., safepoint synchronization)
3209 
3210 JavaThread* Threads::_thread_list = NULL;
3211 int         Threads::_number_of_threads = 0;
3212 int         Threads::_number_of_non_daemon_threads = 0;
3213 int         Threads::_return_code = 0;
3214 size_t      JavaThread::_stack_size_at_create = 0;
3215 #ifdef ASSERT
3216 bool        Threads::_vm_complete = false;
3217 #endif
3218 
3219 // All JavaThreads
3220 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
3221 
3222 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3223 void Threads::threads_do(ThreadClosure* tc) {
3224   assert_locked_or_safepoint(Threads_lock);
3225   // ALL_JAVA_THREADS iterates through all JavaThreads
3226   ALL_JAVA_THREADS(p) {
3227     tc->do_thread(p);
3228   }
3229   // Someday we could have a table or list of all non-JavaThreads.
3230   // For now, just manually iterate through them.
3231   tc->do_thread(VMThread::vm_thread());
3232   Universe::heap()->gc_threads_do(tc);
3233   WatcherThread *wt = WatcherThread::watcher_thread();
3234   // Strictly speaking, the following NULL check isn't sufficient to make sure
3235   // the data for WatcherThread is still valid upon being examined. However,
3236   // considering that WatchThread terminates when the VM is on the way to
3237   // exit at safepoint, the chance of the above is extremely small. The right
3238   // way to prevent termination of WatcherThread would be to acquire
3239   // Terminator_lock, but we can't do that without violating the lock rank
3240   // checking in some cases.
3241   if (wt != NULL) {
3242     tc->do_thread(wt);
3243   }
3244 
3245   // If CompilerThreads ever become non-JavaThreads, add them here
3246 }
3247 
3248 
3249 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3250   TraceTime timer("Initialize java.lang classes", TraceStartupTime);
3251 
3252   if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3253     create_vm_init_libraries();
3254   }
3255 
3256   initialize_class(vmSymbols::java_lang_String(), CHECK);
3257 
3258   // Initialize java_lang.System (needed before creating the thread)
3259   initialize_class(vmSymbols::java_lang_System(), CHECK);
3260   initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3261   Handle thread_group = create_initial_thread_group(CHECK);
3262   Universe::set_main_thread_group(thread_group());
3263   initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3264   oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3265   main_thread->set_threadObj(thread_object);
3266   // Set thread status to running since main thread has
3267   // been started and running.
3268   java_lang_Thread::set_thread_status(thread_object,
3269                                       java_lang_Thread::RUNNABLE);
3270 
3271   // The VM creates & returns objects of this class. Make sure it's initialized.
3272   initialize_class(vmSymbols::java_lang_Class(), CHECK);
3273 
3274   // The VM preresolves methods to these classes. Make sure that they get initialized
3275   initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3276   initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3277   call_initializeSystemClass(CHECK);
3278 
3279   // get the Java runtime name after java.lang.System is initialized
3280   JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3281   JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3282 
3283   // an instance of OutOfMemory exception has been allocated earlier
3284   initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3285   initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3286   initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3287   initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3288   initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3289   initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3290   initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3291   initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3292 }
3293 
3294 void Threads::initialize_jsr292_core_classes(TRAPS) {
3295   initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3296   initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3297   initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3298 }
3299 
3300 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3301   extern void JDK_Version_init();
3302 
3303   // Check version
3304   if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3305 
3306   // Initialize the output stream module
3307   ostream_init();
3308 
3309   // Process java launcher properties.
3310   Arguments::process_sun_java_launcher_properties(args);
3311 
3312   // Initialize the os module before using TLS
3313   os::init();
3314 
3315   // Initialize system properties.
3316   Arguments::init_system_properties();
3317 
3318   // So that JDK version can be used as a discriminator when parsing arguments
3319   JDK_Version_init();
3320 
3321   // Update/Initialize System properties after JDK version number is known
3322   Arguments::init_version_specific_system_properties();
3323 
3324   // Parse arguments
3325   jint parse_result = Arguments::parse(args);
3326   if (parse_result != JNI_OK) return parse_result;
3327 
3328   os::init_before_ergo();
3329 
3330   jint ergo_result = Arguments::apply_ergo();
3331   if (ergo_result != JNI_OK) return ergo_result;
3332 
3333   if (PauseAtStartup) {
3334     os::pause();
3335   }
3336 
3337   HOTSPOT_VM_INIT_BEGIN();
3338 
3339   // Record VM creation timing statistics
3340   TraceVmCreationTime create_vm_timer;
3341   create_vm_timer.start();
3342 
3343   // Timing (must come after argument parsing)
3344   TraceTime timer("Create VM", TraceStartupTime);
3345 
3346   // Initialize the os module after parsing the args
3347   jint os_init_2_result = os::init_2();
3348   if (os_init_2_result != JNI_OK) return os_init_2_result;
3349 
3350   jint adjust_after_os_result = Arguments::adjust_after_os();
3351   if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3352 
3353   // initialize TLS
3354   ThreadLocalStorage::init();
3355 
3356   // Initialize output stream logging
3357   ostream_init_log();
3358 
3359   // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3360   // Must be before create_vm_init_agents()
3361   if (Arguments::init_libraries_at_startup()) {
3362     convert_vm_init_libraries_to_agents();
3363   }
3364 
3365   // Launch -agentlib/-agentpath and converted -Xrun agents
3366   if (Arguments::init_agents_at_startup()) {
3367     create_vm_init_agents();
3368   }
3369 
3370   // Initialize Threads state
3371   _thread_list = NULL;
3372   _number_of_threads = 0;
3373   _number_of_non_daemon_threads = 0;
3374 
3375   // Initialize global data structures and create system classes in heap
3376   vm_init_globals();
3377 
3378   // Attach the main thread to this os thread
3379   JavaThread* main_thread = new JavaThread();
3380   main_thread->set_thread_state(_thread_in_vm);
3381   // must do this before set_active_handles and initialize_thread_local_storage
3382   // Note: on solaris initialize_thread_local_storage() will (indirectly)
3383   // change the stack size recorded here to one based on the java thread
3384   // stacksize. This adjusted size is what is used to figure the placement
3385   // of the guard pages.
3386   main_thread->record_stack_base_and_size();
3387   main_thread->initialize_thread_local_storage();
3388 
3389   main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3390 
3391   if (!main_thread->set_as_starting_thread()) {
3392     vm_shutdown_during_initialization(
3393                                       "Failed necessary internal allocation. Out of swap space");
3394     delete main_thread;
3395     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3396     return JNI_ENOMEM;
3397   }
3398 
3399   // Enable guard page *after* os::create_main_thread(), otherwise it would
3400   // crash Linux VM, see notes in os_linux.cpp.
3401   main_thread->create_stack_guard_pages();
3402 
3403   // Initialize Java-Level synchronization subsystem
3404   ObjectMonitor::Initialize();
3405 
3406   // Initialize global modules
3407   jint status = init_globals();
3408   if (status != JNI_OK) {
3409     delete main_thread;
3410     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3411     return status;
3412   }
3413 
3414   // Should be done after the heap is fully created
3415   main_thread->cache_global_variables();
3416 
3417   HandleMark hm;
3418 
3419   { MutexLocker mu(Threads_lock);
3420     Threads::add(main_thread);
3421   }
3422 
3423   // Any JVMTI raw monitors entered in onload will transition into
3424   // real raw monitor. VM is setup enough here for raw monitor enter.
3425   JvmtiExport::transition_pending_onload_raw_monitors();
3426 
3427   // Create the VMThread
3428   { TraceTime timer("Start VMThread", TraceStartupTime);
3429     VMThread::create();
3430     Thread* vmthread = VMThread::vm_thread();
3431 
3432     if (!os::create_thread(vmthread, os::vm_thread)) {
3433       vm_exit_during_initialization("Cannot create VM thread. "
3434                                     "Out of system resources.");
3435     }
3436 
3437     // Wait for the VM thread to become ready, and VMThread::run to initialize
3438     // Monitors can have spurious returns, must always check another state flag
3439     {
3440       MutexLocker ml(Notify_lock);
3441       os::start_thread(vmthread);
3442       while (vmthread->active_handles() == NULL) {
3443         Notify_lock->wait();
3444       }
3445     }
3446   }
3447 
3448   assert(Universe::is_fully_initialized(), "not initialized");
3449   if (VerifyDuringStartup) {
3450     // Make sure we're starting with a clean slate.
3451     VM_Verify verify_op;
3452     VMThread::execute(&verify_op);
3453   }
3454 
3455   Thread* THREAD = Thread::current();
3456 
3457   // At this point, the Universe is initialized, but we have not executed
3458   // any byte code.  Now is a good time (the only time) to dump out the
3459   // internal state of the JVM for sharing.
3460   if (DumpSharedSpaces) {
3461     MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3462     ShouldNotReachHere();
3463   }
3464 
3465   // Always call even when there are not JVMTI environments yet, since environments
3466   // may be attached late and JVMTI must track phases of VM execution
3467   JvmtiExport::enter_start_phase();
3468 
3469   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3470   JvmtiExport::post_vm_start();
3471 
3472   initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3473 
3474   // We need this for ClassDataSharing - the initial vm.info property is set
3475   // with the default value of CDS "sharing" which may be reset through
3476   // command line options.
3477   reset_vm_info_property(CHECK_JNI_ERR);
3478 
3479   quicken_jni_functions();
3480 
3481   // Must be run after init_ft which initializes ft_enabled
3482   if (TRACE_INITIALIZE() != JNI_OK) {
3483     vm_exit_during_initialization("Failed to initialize tracing backend");
3484   }
3485 
3486   // Set flag that basic initialization has completed. Used by exceptions and various
3487   // debug stuff, that does not work until all basic classes have been initialized.
3488   set_init_completed();
3489 
3490   Metaspace::post_initialize();
3491 
3492   HOTSPOT_VM_INIT_END();
3493 
3494   // record VM initialization completion time
3495 #if INCLUDE_MANAGEMENT
3496   Management::record_vm_init_completed();
3497 #endif // INCLUDE_MANAGEMENT
3498 
3499   // Compute system loader. Note that this has to occur after set_init_completed, since
3500   // valid exceptions may be thrown in the process.
3501   // Note that we do not use CHECK_0 here since we are inside an EXCEPTION_MARK and
3502   // set_init_completed has just been called, causing exceptions not to be shortcut
3503   // anymore. We call vm_exit_during_initialization directly instead.
3504   SystemDictionary::compute_java_system_loader(CHECK_JNI_ERR);
3505 
3506 #if INCLUDE_ALL_GCS
3507   // Support for ConcurrentMarkSweep. This should be cleaned up
3508   // and better encapsulated. The ugly nested if test would go away
3509   // once things are properly refactored. XXX YSR
3510   if (UseConcMarkSweepGC || UseG1GC) {
3511     if (UseConcMarkSweepGC) {
3512       ConcurrentMarkSweepThread::makeSurrogateLockerThread(CHECK_JNI_ERR);
3513     } else {
3514       ConcurrentMarkThread::makeSurrogateLockerThread(CHECK_JNI_ERR);
3515     }
3516   }
3517 #endif // INCLUDE_ALL_GCS
3518 
3519   // Always call even when there are not JVMTI environments yet, since environments
3520   // may be attached late and JVMTI must track phases of VM execution
3521   JvmtiExport::enter_live_phase();
3522 
3523   // Signal Dispatcher needs to be started before VMInit event is posted
3524   os::signal_init();
3525 
3526   // Start Attach Listener if +StartAttachListener or it can't be started lazily
3527   if (!DisableAttachMechanism) {
3528     AttachListener::vm_start();
3529     if (StartAttachListener || AttachListener::init_at_startup()) {
3530       AttachListener::init();
3531     }
3532   }
3533 
3534   // Launch -Xrun agents
3535   // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3536   // back-end can launch with -Xdebug -Xrunjdwp.
3537   if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3538     create_vm_init_libraries();
3539   }
3540 
3541   // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3542   JvmtiExport::post_vm_initialized();
3543 
3544   if (TRACE_START() != JNI_OK) {
3545     vm_exit_during_initialization("Failed to start tracing backend.");
3546   }
3547 
3548   if (CleanChunkPoolAsync) {
3549     Chunk::start_chunk_pool_cleaner_task();
3550   }
3551 
3552   // initialize compiler(s)
3553 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK)
3554   CompileBroker::compilation_init();
3555 #endif
3556 
3557   // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3558   // It is done after compilers are initialized, because otherwise compilations of
3559   // signature polymorphic MH intrinsics can be missed
3560   // (see SystemDictionary::find_method_handle_intrinsic).
3561   initialize_jsr292_core_classes(CHECK_JNI_ERR);
3562 
3563 #if INCLUDE_MANAGEMENT
3564   Management::initialize(THREAD);
3565 
3566   if (HAS_PENDING_EXCEPTION) {
3567     // management agent fails to start possibly due to
3568     // configuration problem and is responsible for printing
3569     // stack trace if appropriate. Simply exit VM.
3570     vm_exit(1);
3571   }
3572 #endif // INCLUDE_MANAGEMENT
3573 
3574   if (Arguments::has_profile())       FlatProfiler::engage(main_thread, true);
3575   if (MemProfiling)                   MemProfiler::engage();
3576   StatSampler::engage();
3577   if (CheckJNICalls)                  JniPeriodicChecker::engage();
3578 
3579   BiasedLocking::init();
3580 
3581 #if INCLUDE_RTM_OPT
3582   RTMLockingCounters::init();
3583 #endif
3584 
3585   if (JDK_Version::current().post_vm_init_hook_enabled()) {
3586     call_postVMInitHook(THREAD);
3587     // The Java side of PostVMInitHook.run must deal with all
3588     // exceptions and provide means of diagnosis.
3589     if (HAS_PENDING_EXCEPTION) {
3590       CLEAR_PENDING_EXCEPTION;
3591     }
3592   }
3593 
3594   {
3595     MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
3596     // Make sure the watcher thread can be started by WatcherThread::start()
3597     // or by dynamic enrollment.
3598     WatcherThread::make_startable();
3599     // Start up the WatcherThread if there are any periodic tasks
3600     // NOTE:  All PeriodicTasks should be registered by now. If they
3601     //   aren't, late joiners might appear to start slowly (we might
3602     //   take a while to process their first tick).
3603     if (PeriodicTask::num_tasks() > 0) {
3604       WatcherThread::start();
3605     }
3606   }
3607 
3608   // Give os specific code one last chance to start
3609   os::init_3();
3610 
3611   create_vm_timer.end();
3612 #ifdef ASSERT
3613   _vm_complete = true;
3614 #endif
3615   return JNI_OK;
3616 }
3617 
3618 // type for the Agent_OnLoad and JVM_OnLoad entry points
3619 extern "C" {
3620   typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3621 }
3622 // Find a command line agent library and return its entry point for
3623 //         -agentlib:  -agentpath:   -Xrun
3624 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3625 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3626                                     const char *on_load_symbols[],
3627                                     size_t num_symbol_entries) {
3628   OnLoadEntry_t on_load_entry = NULL;
3629   void *library = NULL;
3630 
3631   if (!agent->valid()) {
3632     char buffer[JVM_MAXPATHLEN];
3633     char ebuf[1024];
3634     const char *name = agent->name();
3635     const char *msg = "Could not find agent library ";
3636 
3637     // First check to see if agent is statically linked into executable
3638     if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3639       library = agent->os_lib();
3640     } else if (agent->is_absolute_path()) {
3641       library = os::dll_load(name, ebuf, sizeof ebuf);
3642       if (library == NULL) {
3643         const char *sub_msg = " in absolute path, with error: ";
3644         size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3645         char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3646         jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3647         // If we can't find the agent, exit.
3648         vm_exit_during_initialization(buf, NULL);
3649         FREE_C_HEAP_ARRAY(char, buf, mtThread);
3650       }
3651     } else {
3652       // Try to load the agent from the standard dll directory
3653       if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(),
3654                              name)) {
3655         library = os::dll_load(buffer, ebuf, sizeof ebuf);
3656       }
3657       if (library == NULL) { // Try the local directory
3658         char ns[1] = {0};
3659         if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) {
3660           library = os::dll_load(buffer, ebuf, sizeof ebuf);
3661         }
3662         if (library == NULL) {
3663           const char *sub_msg = " on the library path, with error: ";
3664           size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3665           char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3666           jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3667           // If we can't find the agent, exit.
3668           vm_exit_during_initialization(buf, NULL);
3669           FREE_C_HEAP_ARRAY(char, buf, mtThread);
3670         }
3671       }
3672     }
3673     agent->set_os_lib(library);
3674     agent->set_valid();
3675   }
3676 
3677   // Find the OnLoad function.
3678   on_load_entry =
3679     CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
3680                                                           false,
3681                                                           on_load_symbols,
3682                                                           num_symbol_entries));
3683   return on_load_entry;
3684 }
3685 
3686 // Find the JVM_OnLoad entry point
3687 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3688   const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3689   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3690 }
3691 
3692 // Find the Agent_OnLoad entry point
3693 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3694   const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3695   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3696 }
3697 
3698 // For backwards compatibility with -Xrun
3699 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3700 // treated like -agentpath:
3701 // Must be called before agent libraries are created
3702 void Threads::convert_vm_init_libraries_to_agents() {
3703   AgentLibrary* agent;
3704   AgentLibrary* next;
3705 
3706   for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3707     next = agent->next();  // cache the next agent now as this agent may get moved off this list
3708     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3709 
3710     // If there is an JVM_OnLoad function it will get called later,
3711     // otherwise see if there is an Agent_OnLoad
3712     if (on_load_entry == NULL) {
3713       on_load_entry = lookup_agent_on_load(agent);
3714       if (on_load_entry != NULL) {
3715         // switch it to the agent list -- so that Agent_OnLoad will be called,
3716         // JVM_OnLoad won't be attempted and Agent_OnUnload will
3717         Arguments::convert_library_to_agent(agent);
3718       } else {
3719         vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3720       }
3721     }
3722   }
3723 }
3724 
3725 // Create agents for -agentlib:  -agentpath:  and converted -Xrun
3726 // Invokes Agent_OnLoad
3727 // Called very early -- before JavaThreads exist
3728 void Threads::create_vm_init_agents() {
3729   extern struct JavaVM_ main_vm;
3730   AgentLibrary* agent;
3731 
3732   JvmtiExport::enter_onload_phase();
3733 
3734   for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3735     OnLoadEntry_t  on_load_entry = lookup_agent_on_load(agent);
3736 
3737     if (on_load_entry != NULL) {
3738       // Invoke the Agent_OnLoad function
3739       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3740       if (err != JNI_OK) {
3741         vm_exit_during_initialization("agent library failed to init", agent->name());
3742       }
3743     } else {
3744       vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
3745     }
3746   }
3747   JvmtiExport::enter_primordial_phase();
3748 }
3749 
3750 extern "C" {
3751   typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
3752 }
3753 
3754 void Threads::shutdown_vm_agents() {
3755   // Send any Agent_OnUnload notifications
3756   const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
3757   size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
3758   extern struct JavaVM_ main_vm;
3759   for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3760 
3761     // Find the Agent_OnUnload function.
3762     Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
3763                                                    os::find_agent_function(agent,
3764                                                    false,
3765                                                    on_unload_symbols,
3766                                                    num_symbol_entries));
3767 
3768     // Invoke the Agent_OnUnload function
3769     if (unload_entry != NULL) {
3770       JavaThread* thread = JavaThread::current();
3771       ThreadToNativeFromVM ttn(thread);
3772       HandleMark hm(thread);
3773       (*unload_entry)(&main_vm);
3774     }
3775   }
3776 }
3777 
3778 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
3779 // Invokes JVM_OnLoad
3780 void Threads::create_vm_init_libraries() {
3781   extern struct JavaVM_ main_vm;
3782   AgentLibrary* agent;
3783 
3784   for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
3785     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3786 
3787     if (on_load_entry != NULL) {
3788       // Invoke the JVM_OnLoad function
3789       JavaThread* thread = JavaThread::current();
3790       ThreadToNativeFromVM ttn(thread);
3791       HandleMark hm(thread);
3792       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3793       if (err != JNI_OK) {
3794         vm_exit_during_initialization("-Xrun library failed to init", agent->name());
3795       }
3796     } else {
3797       vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
3798     }
3799   }
3800 }
3801 
3802 JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) {
3803   assert(Threads_lock->owned_by_self(), "Must hold Threads_lock");
3804 
3805   JavaThread* java_thread = NULL;
3806   // Sequential search for now.  Need to do better optimization later.
3807   for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) {
3808     oop tobj = thread->threadObj();
3809     if (!thread->is_exiting() &&
3810         tobj != NULL &&
3811         java_tid == java_lang_Thread::thread_id(tobj)) {
3812       java_thread = thread;
3813       break;
3814     }
3815   }
3816   return java_thread;
3817 }
3818 
3819 
3820 // Last thread running calls java.lang.Shutdown.shutdown()
3821 void JavaThread::invoke_shutdown_hooks() {
3822   HandleMark hm(this);
3823 
3824   // We could get here with a pending exception, if so clear it now.
3825   if (this->has_pending_exception()) {
3826     this->clear_pending_exception();
3827   }
3828 
3829   EXCEPTION_MARK;
3830   Klass* k =
3831     SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
3832                                       THREAD);
3833   if (k != NULL) {
3834     // SystemDictionary::resolve_or_null will return null if there was
3835     // an exception.  If we cannot load the Shutdown class, just don't
3836     // call Shutdown.shutdown() at all.  This will mean the shutdown hooks
3837     // and finalizers (if runFinalizersOnExit is set) won't be run.
3838     // Note that if a shutdown hook was registered or runFinalizersOnExit
3839     // was called, the Shutdown class would have already been loaded
3840     // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
3841     instanceKlassHandle shutdown_klass (THREAD, k);
3842     JavaValue result(T_VOID);
3843     JavaCalls::call_static(&result,
3844                            shutdown_klass,
3845                            vmSymbols::shutdown_method_name(),
3846                            vmSymbols::void_method_signature(),
3847                            THREAD);
3848   }
3849   CLEAR_PENDING_EXCEPTION;
3850 }
3851 
3852 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
3853 // the program falls off the end of main(). Another VM exit path is through
3854 // vm_exit() when the program calls System.exit() to return a value or when
3855 // there is a serious error in VM. The two shutdown paths are not exactly
3856 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
3857 // and VM_Exit op at VM level.
3858 //
3859 // Shutdown sequence:
3860 //   + Shutdown native memory tracking if it is on
3861 //   + Wait until we are the last non-daemon thread to execute
3862 //     <-- every thing is still working at this moment -->
3863 //   + Call java.lang.Shutdown.shutdown(), which will invoke Java level
3864 //        shutdown hooks, run finalizers if finalization-on-exit
3865 //   + Call before_exit(), prepare for VM exit
3866 //      > run VM level shutdown hooks (they are registered through JVM_OnExit(),
3867 //        currently the only user of this mechanism is File.deleteOnExit())
3868 //      > stop flat profiler, StatSampler, watcher thread, CMS threads,
3869 //        post thread end and vm death events to JVMTI,
3870 //        stop signal thread
3871 //   + Call JavaThread::exit(), it will:
3872 //      > release JNI handle blocks, remove stack guard pages
3873 //      > remove this thread from Threads list
3874 //     <-- no more Java code from this thread after this point -->
3875 //   + Stop VM thread, it will bring the remaining VM to a safepoint and stop
3876 //     the compiler threads at safepoint
3877 //     <-- do not use anything that could get blocked by Safepoint -->
3878 //   + Disable tracing at JNI/JVM barriers
3879 //   + Set _vm_exited flag for threads that are still running native code
3880 //   + Delete this thread
3881 //   + Call exit_globals()
3882 //      > deletes tty
3883 //      > deletes PerfMemory resources
3884 //   + Return to caller
3885 
3886 bool Threads::destroy_vm() {
3887   JavaThread* thread = JavaThread::current();
3888 
3889 #ifdef ASSERT
3890   _vm_complete = false;
3891 #endif
3892   // Wait until we are the last non-daemon thread to execute
3893   { MutexLocker nu(Threads_lock);
3894     while (Threads::number_of_non_daemon_threads() > 1)
3895       // This wait should make safepoint checks, wait without a timeout,
3896       // and wait as a suspend-equivalent condition.
3897       //
3898       // Note: If the FlatProfiler is running and this thread is waiting
3899       // for another non-daemon thread to finish, then the FlatProfiler
3900       // is waiting for the external suspend request on this thread to
3901       // complete. wait_for_ext_suspend_completion() will eventually
3902       // timeout, but that takes time. Making this wait a suspend-
3903       // equivalent condition solves that timeout problem.
3904       //
3905       Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
3906                          Mutex::_as_suspend_equivalent_flag);
3907   }
3908 
3909   // Hang forever on exit if we are reporting an error.
3910   if (ShowMessageBoxOnError && is_error_reported()) {
3911     os::infinite_sleep();
3912   }
3913   os::wait_for_keypress_at_exit();
3914 
3915   // run Java level shutdown hooks
3916   thread->invoke_shutdown_hooks();
3917 
3918   before_exit(thread);
3919 
3920   thread->exit(true);
3921 
3922   // Stop VM thread.
3923   {
3924     // 4945125 The vm thread comes to a safepoint during exit.
3925     // GC vm_operations can get caught at the safepoint, and the
3926     // heap is unparseable if they are caught. Grab the Heap_lock
3927     // to prevent this. The GC vm_operations will not be able to
3928     // queue until after the vm thread is dead. After this point,
3929     // we'll never emerge out of the safepoint before the VM exits.
3930 
3931     MutexLocker ml(Heap_lock);
3932 
3933     VMThread::wait_for_vm_thread_exit();
3934     assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
3935     VMThread::destroy();
3936   }
3937 
3938   // clean up ideal graph printers
3939 #if defined(COMPILER2) && !defined(PRODUCT)
3940   IdealGraphPrinter::clean_up();
3941 #endif
3942 
3943   // Now, all Java threads are gone except daemon threads. Daemon threads
3944   // running Java code or in VM are stopped by the Safepoint. However,
3945   // daemon threads executing native code are still running.  But they
3946   // will be stopped at native=>Java/VM barriers. Note that we can't
3947   // simply kill or suspend them, as it is inherently deadlock-prone.
3948 
3949 #ifndef PRODUCT
3950   // disable function tracing at JNI/JVM barriers
3951   TraceJNICalls = false;
3952   TraceJVMCalls = false;
3953   TraceRuntimeCalls = false;
3954 #endif
3955 
3956   VM_Exit::set_vm_exited();
3957 
3958   notify_vm_shutdown();
3959 
3960   delete thread;
3961 
3962   // exit_globals() will delete tty
3963   exit_globals();
3964 
3965   return true;
3966 }
3967 
3968 
3969 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
3970   if (version == JNI_VERSION_1_1) return JNI_TRUE;
3971   return is_supported_jni_version(version);
3972 }
3973 
3974 
3975 jboolean Threads::is_supported_jni_version(jint version) {
3976   if (version == JNI_VERSION_1_2) return JNI_TRUE;
3977   if (version == JNI_VERSION_1_4) return JNI_TRUE;
3978   if (version == JNI_VERSION_1_6) return JNI_TRUE;
3979   if (version == JNI_VERSION_1_8) return JNI_TRUE;
3980   return JNI_FALSE;
3981 }
3982 
3983 
3984 void Threads::add(JavaThread* p, bool force_daemon) {
3985   // The threads lock must be owned at this point
3986   assert_locked_or_safepoint(Threads_lock);
3987 
3988   // See the comment for this method in thread.hpp for its purpose and
3989   // why it is called here.
3990   p->initialize_queues();
3991   p->set_next(_thread_list);
3992   _thread_list = p;
3993   _number_of_threads++;
3994   oop threadObj = p->threadObj();
3995   bool daemon = true;
3996   // Bootstrapping problem: threadObj can be null for initial
3997   // JavaThread (or for threads attached via JNI)
3998   if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
3999     _number_of_non_daemon_threads++;
4000     daemon = false;
4001   }
4002 
4003   ThreadService::add_thread(p, daemon);
4004 
4005   // Possible GC point.
4006   Events::log(p, "Thread added: " INTPTR_FORMAT, p);
4007 }
4008 
4009 void Threads::remove(JavaThread* p) {
4010   // Extra scope needed for Thread_lock, so we can check
4011   // that we do not remove thread without safepoint code notice
4012   { MutexLocker ml(Threads_lock);
4013 
4014     assert(includes(p), "p must be present");
4015 
4016     JavaThread* current = _thread_list;
4017     JavaThread* prev    = NULL;
4018 
4019     while (current != p) {
4020       prev    = current;
4021       current = current->next();
4022     }
4023 
4024     if (prev) {
4025       prev->set_next(current->next());
4026     } else {
4027       _thread_list = p->next();
4028     }
4029     _number_of_threads--;
4030     oop threadObj = p->threadObj();
4031     bool daemon = true;
4032     if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4033       _number_of_non_daemon_threads--;
4034       daemon = false;
4035 
4036       // Only one thread left, do a notify on the Threads_lock so a thread waiting
4037       // on destroy_vm will wake up.
4038       if (number_of_non_daemon_threads() == 1) {
4039         Threads_lock->notify_all();
4040       }
4041     }
4042     ThreadService::remove_thread(p, daemon);
4043 
4044     // Make sure that safepoint code disregard this thread. This is needed since
4045     // the thread might mess around with locks after this point. This can cause it
4046     // to do callbacks into the safepoint code. However, the safepoint code is not aware
4047     // of this thread since it is removed from the queue.
4048     p->set_terminated_value();
4049   } // unlock Threads_lock
4050 
4051   // Since Events::log uses a lock, we grab it outside the Threads_lock
4052   Events::log(p, "Thread exited: " INTPTR_FORMAT, p);
4053 }
4054 
4055 // Threads_lock must be held when this is called (or must be called during a safepoint)
4056 bool Threads::includes(JavaThread* p) {
4057   assert(Threads_lock->is_locked(), "sanity check");
4058   ALL_JAVA_THREADS(q) {
4059     if (q == p) {
4060       return true;
4061     }
4062   }
4063   return false;
4064 }
4065 
4066 // Operations on the Threads list for GC.  These are not explicitly locked,
4067 // but the garbage collector must provide a safe context for them to run.
4068 // In particular, these things should never be called when the Threads_lock
4069 // is held by some other thread. (Note: the Safepoint abstraction also
4070 // uses the Threads_lock to guarantee this property. It also makes sure that
4071 // all threads gets blocked when exiting or starting).
4072 
4073 void Threads::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
4074   ALL_JAVA_THREADS(p) {
4075     p->oops_do(f, cld_f, cf);
4076   }
4077   VMThread::vm_thread()->oops_do(f, cld_f, cf);
4078 }
4079 
4080 void Threads::possibly_parallel_oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
4081   // Introduce a mechanism allowing parallel threads to claim threads as
4082   // root groups.  Overhead should be small enough to use all the time,
4083   // even in sequential code.
4084   SharedHeap* sh = SharedHeap::heap();
4085   // Cannot yet substitute active_workers for n_par_threads
4086   // because of G1CollectedHeap::verify() use of
4087   // SharedHeap::process_roots().  n_par_threads == 0 will
4088   // turn off parallelism in process_roots while active_workers
4089   // is being used for parallelism elsewhere.
4090   bool is_par = sh->n_par_threads() > 0;
4091   assert(!is_par ||
4092          (SharedHeap::heap()->n_par_threads() ==
4093          SharedHeap::heap()->workers()->active_workers()), "Mismatch");
4094   int cp = SharedHeap::heap()->strong_roots_parity();
4095   ALL_JAVA_THREADS(p) {
4096     if (p->claim_oops_do(is_par, cp)) {
4097       p->oops_do(f, cld_f, cf);
4098     }
4099   }
4100   VMThread* vmt = VMThread::vm_thread();
4101   if (vmt->claim_oops_do(is_par, cp)) {
4102     vmt->oops_do(f, cld_f, cf);
4103   }
4104 }
4105 
4106 #if INCLUDE_ALL_GCS
4107 // Used by ParallelScavenge
4108 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4109   ALL_JAVA_THREADS(p) {
4110     q->enqueue(new ThreadRootsTask(p));
4111   }
4112   q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4113 }
4114 
4115 // Used by Parallel Old
4116 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4117   ALL_JAVA_THREADS(p) {
4118     q->enqueue(new ThreadRootsMarkingTask(p));
4119   }
4120   q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4121 }
4122 #endif // INCLUDE_ALL_GCS
4123 
4124 void Threads::nmethods_do(CodeBlobClosure* cf) {
4125   ALL_JAVA_THREADS(p) {
4126     p->nmethods_do(cf);
4127   }
4128   VMThread::vm_thread()->nmethods_do(cf);
4129 }
4130 
4131 void Threads::metadata_do(void f(Metadata*)) {
4132   ALL_JAVA_THREADS(p) {
4133     p->metadata_do(f);
4134   }
4135 }
4136 
4137 void Threads::deoptimized_wrt_marked_nmethods() {
4138   ALL_JAVA_THREADS(p) {
4139     p->deoptimized_wrt_marked_nmethods();
4140   }
4141 }
4142 
4143 
4144 // Get count Java threads that are waiting to enter the specified monitor.
4145 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
4146                                                          address monitor,
4147                                                          bool doLock) {
4148   assert(doLock || SafepointSynchronize::is_at_safepoint(),
4149          "must grab Threads_lock or be at safepoint");
4150   GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4151 
4152   int i = 0;
4153   {
4154     MutexLockerEx ml(doLock ? Threads_lock : NULL);
4155     ALL_JAVA_THREADS(p) {
4156       if (p->is_Compiler_thread()) continue;
4157 
4158       address pending = (address)p->current_pending_monitor();
4159       if (pending == monitor) {             // found a match
4160         if (i < count) result->append(p);   // save the first count matches
4161         i++;
4162       }
4163     }
4164   }
4165   return result;
4166 }
4167 
4168 
4169 JavaThread *Threads::owning_thread_from_monitor_owner(address owner,
4170                                                       bool doLock) {
4171   assert(doLock ||
4172          Threads_lock->owned_by_self() ||
4173          SafepointSynchronize::is_at_safepoint(),
4174          "must grab Threads_lock or be at safepoint");
4175 
4176   // NULL owner means not locked so we can skip the search
4177   if (owner == NULL) return NULL;
4178 
4179   {
4180     MutexLockerEx ml(doLock ? Threads_lock : NULL);
4181     ALL_JAVA_THREADS(p) {
4182       // first, see if owner is the address of a Java thread
4183       if (owner == (address)p) return p;
4184     }
4185   }
4186   // Cannot assert on lack of success here since this function may be
4187   // used by code that is trying to report useful problem information
4188   // like deadlock detection.
4189   if (UseHeavyMonitors) return NULL;
4190 
4191   // If we didn't find a matching Java thread and we didn't force use of
4192   // heavyweight monitors, then the owner is the stack address of the
4193   // Lock Word in the owning Java thread's stack.
4194   //
4195   JavaThread* the_owner = NULL;
4196   {
4197     MutexLockerEx ml(doLock ? Threads_lock : NULL);
4198     ALL_JAVA_THREADS(q) {
4199       if (q->is_lock_owned(owner)) {
4200         the_owner = q;
4201         break;
4202       }
4203     }
4204   }
4205   // cannot assert on lack of success here; see above comment
4206   return the_owner;
4207 }
4208 
4209 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4210 void Threads::print_on(outputStream* st, bool print_stacks,
4211                        bool internal_format, bool print_concurrent_locks) {
4212   char buf[32];
4213   st->print_cr("%s", os::local_time_string(buf, sizeof(buf)));
4214 
4215   st->print_cr("Full thread dump %s (%s %s):",
4216                Abstract_VM_Version::vm_name(),
4217                Abstract_VM_Version::vm_release(),
4218                Abstract_VM_Version::vm_info_string());
4219   st->cr();
4220 
4221 #if INCLUDE_ALL_GCS
4222   // Dump concurrent locks
4223   ConcurrentLocksDump concurrent_locks;
4224   if (print_concurrent_locks) {
4225     concurrent_locks.dump_at_safepoint();
4226   }
4227 #endif // INCLUDE_ALL_GCS
4228 
4229   ALL_JAVA_THREADS(p) {
4230     ResourceMark rm;
4231     p->print_on(st);
4232     if (print_stacks) {
4233       if (internal_format) {
4234         p->trace_stack();
4235       } else {
4236         p->print_stack_on(st);
4237       }
4238     }
4239     st->cr();
4240 #if INCLUDE_ALL_GCS
4241     if (print_concurrent_locks) {
4242       concurrent_locks.print_locks_on(p, st);
4243     }
4244 #endif // INCLUDE_ALL_GCS
4245   }
4246 
4247   VMThread::vm_thread()->print_on(st);
4248   st->cr();
4249   Universe::heap()->print_gc_threads_on(st);
4250   WatcherThread* wt = WatcherThread::watcher_thread();
4251   if (wt != NULL) {
4252     wt->print_on(st);
4253     st->cr();
4254   }
4255   CompileBroker::print_compiler_threads_on(st);
4256   st->flush();
4257 }
4258 
4259 // Threads::print_on_error() is called by fatal error handler. It's possible
4260 // that VM is not at safepoint and/or current thread is inside signal handler.
4261 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4262 // memory (even in resource area), it might deadlock the error handler.
4263 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4264                              int buflen) {
4265   bool found_current = false;
4266   st->print_cr("Java Threads: ( => current thread )");
4267   ALL_JAVA_THREADS(thread) {
4268     bool is_current = (current == thread);
4269     found_current = found_current || is_current;
4270 
4271     st->print("%s", is_current ? "=>" : "  ");
4272 
4273     st->print(PTR_FORMAT, thread);
4274     st->print(" ");
4275     thread->print_on_error(st, buf, buflen);
4276     st->cr();
4277   }
4278   st->cr();
4279 
4280   st->print_cr("Other Threads:");
4281   if (VMThread::vm_thread()) {
4282     bool is_current = (current == VMThread::vm_thread());
4283     found_current = found_current || is_current;
4284     st->print("%s", current == VMThread::vm_thread() ? "=>" : "  ");
4285 
4286     st->print(PTR_FORMAT, VMThread::vm_thread());
4287     st->print(" ");
4288     VMThread::vm_thread()->print_on_error(st, buf, buflen);
4289     st->cr();
4290   }
4291   WatcherThread* wt = WatcherThread::watcher_thread();
4292   if (wt != NULL) {
4293     bool is_current = (current == wt);
4294     found_current = found_current || is_current;
4295     st->print("%s", is_current ? "=>" : "  ");
4296 
4297     st->print(PTR_FORMAT, wt);
4298     st->print(" ");
4299     wt->print_on_error(st, buf, buflen);
4300     st->cr();
4301   }
4302   if (!found_current) {
4303     st->cr();
4304     st->print("=>" PTR_FORMAT " (exited) ", current);
4305     current->print_on_error(st, buf, buflen);
4306     st->cr();
4307   }
4308 }
4309 
4310 // Internal SpinLock and Mutex
4311 // Based on ParkEvent
4312 
4313 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4314 //
4315 // We employ SpinLocks _only for low-contention, fixed-length
4316 // short-duration critical sections where we're concerned
4317 // about native mutex_t or HotSpot Mutex:: latency.
4318 // The mux construct provides a spin-then-block mutual exclusion
4319 // mechanism.
4320 //
4321 // Testing has shown that contention on the ListLock guarding gFreeList
4322 // is common.  If we implement ListLock as a simple SpinLock it's common
4323 // for the JVM to devolve to yielding with little progress.  This is true
4324 // despite the fact that the critical sections protected by ListLock are
4325 // extremely short.
4326 //
4327 // TODO-FIXME: ListLock should be of type SpinLock.
4328 // We should make this a 1st-class type, integrated into the lock
4329 // hierarchy as leaf-locks.  Critically, the SpinLock structure
4330 // should have sufficient padding to avoid false-sharing and excessive
4331 // cache-coherency traffic.
4332 
4333 
4334 typedef volatile int SpinLockT;
4335 
4336 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4337   if (Atomic::cmpxchg (1, adr, 0) == 0) {
4338     return;   // normal fast-path return
4339   }
4340 
4341   // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4342   TEVENT(SpinAcquire - ctx);
4343   int ctr = 0;
4344   int Yields = 0;
4345   for (;;) {
4346     while (*adr != 0) {
4347       ++ctr;
4348       if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4349         if (Yields > 5) {
4350           os::naked_short_sleep(1);
4351         } else {
4352           os::naked_yield();
4353           ++Yields;
4354         }
4355       } else {
4356         SpinPause();
4357       }
4358     }
4359     if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4360   }
4361 }
4362 
4363 void Thread::SpinRelease(volatile int * adr) {
4364   assert(*adr != 0, "invariant");
4365   OrderAccess::fence();      // guarantee at least release consistency.
4366   // Roach-motel semantics.
4367   // It's safe if subsequent LDs and STs float "up" into the critical section,
4368   // but prior LDs and STs within the critical section can't be allowed
4369   // to reorder or float past the ST that releases the lock.
4370   // Loads and stores in the critical section - which appear in program
4371   // order before the store that releases the lock - must also appear
4372   // before the store that releases the lock in memory visibility order.
4373   // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4374   // the ST of 0 into the lock-word which releases the lock, so fence
4375   // more than covers this on all platforms.
4376   *adr = 0;
4377 }
4378 
4379 // muxAcquire and muxRelease:
4380 //
4381 // *  muxAcquire and muxRelease support a single-word lock-word construct.
4382 //    The LSB of the word is set IFF the lock is held.
4383 //    The remainder of the word points to the head of a singly-linked list
4384 //    of threads blocked on the lock.
4385 //
4386 // *  The current implementation of muxAcquire-muxRelease uses its own
4387 //    dedicated Thread._MuxEvent instance.  If we're interested in
4388 //    minimizing the peak number of extant ParkEvent instances then
4389 //    we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4390 //    as certain invariants were satisfied.  Specifically, care would need
4391 //    to be taken with regards to consuming unpark() "permits".
4392 //    A safe rule of thumb is that a thread would never call muxAcquire()
4393 //    if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4394 //    park().  Otherwise the _ParkEvent park() operation in muxAcquire() could
4395 //    consume an unpark() permit intended for monitorenter, for instance.
4396 //    One way around this would be to widen the restricted-range semaphore
4397 //    implemented in park().  Another alternative would be to provide
4398 //    multiple instances of the PlatformEvent() for each thread.  One
4399 //    instance would be dedicated to muxAcquire-muxRelease, for instance.
4400 //
4401 // *  Usage:
4402 //    -- Only as leaf locks
4403 //    -- for short-term locking only as muxAcquire does not perform
4404 //       thread state transitions.
4405 //
4406 // Alternatives:
4407 // *  We could implement muxAcquire and muxRelease with MCS or CLH locks
4408 //    but with parking or spin-then-park instead of pure spinning.
4409 // *  Use Taura-Oyama-Yonenzawa locks.
4410 // *  It's possible to construct a 1-0 lock if we encode the lockword as
4411 //    (List,LockByte).  Acquire will CAS the full lockword while Release
4412 //    will STB 0 into the LockByte.  The 1-0 scheme admits stranding, so
4413 //    acquiring threads use timers (ParkTimed) to detect and recover from
4414 //    the stranding window.  Thread/Node structures must be aligned on 256-byte
4415 //    boundaries by using placement-new.
4416 // *  Augment MCS with advisory back-link fields maintained with CAS().
4417 //    Pictorially:  LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4418 //    The validity of the backlinks must be ratified before we trust the value.
4419 //    If the backlinks are invalid the exiting thread must back-track through the
4420 //    the forward links, which are always trustworthy.
4421 // *  Add a successor indication.  The LockWord is currently encoded as
4422 //    (List, LOCKBIT:1).  We could also add a SUCCBIT or an explicit _succ variable
4423 //    to provide the usual futile-wakeup optimization.
4424 //    See RTStt for details.
4425 // *  Consider schedctl.sc_nopreempt to cover the critical section.
4426 //
4427 
4428 
4429 typedef volatile intptr_t MutexT;      // Mux Lock-word
4430 enum MuxBits { LOCKBIT = 1 };
4431 
4432 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4433   intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4434   if (w == 0) return;
4435   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4436     return;
4437   }
4438 
4439   TEVENT(muxAcquire - Contention);
4440   ParkEvent * const Self = Thread::current()->_MuxEvent;
4441   assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4442   for (;;) {
4443     int its = (os::is_MP() ? 100 : 0) + 1;
4444 
4445     // Optional spin phase: spin-then-park strategy
4446     while (--its >= 0) {
4447       w = *Lock;
4448       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4449         return;
4450       }
4451     }
4452 
4453     Self->reset();
4454     Self->OnList = intptr_t(Lock);
4455     // The following fence() isn't _strictly necessary as the subsequent
4456     // CAS() both serializes execution and ratifies the fetched *Lock value.
4457     OrderAccess::fence();
4458     for (;;) {
4459       w = *Lock;
4460       if ((w & LOCKBIT) == 0) {
4461         if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4462           Self->OnList = 0;   // hygiene - allows stronger asserts
4463           return;
4464         }
4465         continue;      // Interference -- *Lock changed -- Just retry
4466       }
4467       assert(w & LOCKBIT, "invariant");
4468       Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4469       if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4470     }
4471 
4472     while (Self->OnList != 0) {
4473       Self->park();
4474     }
4475   }
4476 }
4477 
4478 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4479   intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4480   if (w == 0) return;
4481   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4482     return;
4483   }
4484 
4485   TEVENT(muxAcquire - Contention);
4486   ParkEvent * ReleaseAfter = NULL;
4487   if (ev == NULL) {
4488     ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4489   }
4490   assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4491   for (;;) {
4492     guarantee(ev->OnList == 0, "invariant");
4493     int its = (os::is_MP() ? 100 : 0) + 1;
4494 
4495     // Optional spin phase: spin-then-park strategy
4496     while (--its >= 0) {
4497       w = *Lock;
4498       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4499         if (ReleaseAfter != NULL) {
4500           ParkEvent::Release(ReleaseAfter);
4501         }
4502         return;
4503       }
4504     }
4505 
4506     ev->reset();
4507     ev->OnList = intptr_t(Lock);
4508     // The following fence() isn't _strictly necessary as the subsequent
4509     // CAS() both serializes execution and ratifies the fetched *Lock value.
4510     OrderAccess::fence();
4511     for (;;) {
4512       w = *Lock;
4513       if ((w & LOCKBIT) == 0) {
4514         if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4515           ev->OnList = 0;
4516           // We call ::Release while holding the outer lock, thus
4517           // artificially lengthening the critical section.
4518           // Consider deferring the ::Release() until the subsequent unlock(),
4519           // after we've dropped the outer lock.
4520           if (ReleaseAfter != NULL) {
4521             ParkEvent::Release(ReleaseAfter);
4522           }
4523           return;
4524         }
4525         continue;      // Interference -- *Lock changed -- Just retry
4526       }
4527       assert(w & LOCKBIT, "invariant");
4528       ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4529       if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4530     }
4531 
4532     while (ev->OnList != 0) {
4533       ev->park();
4534     }
4535   }
4536 }
4537 
4538 // Release() must extract a successor from the list and then wake that thread.
4539 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4540 // similar to that used by ParkEvent::Allocate() and ::Release().  DMR-based
4541 // Release() would :
4542 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4543 // (B) Extract a successor from the private list "in-hand"
4544 // (C) attempt to CAS() the residual back into *Lock over null.
4545 //     If there were any newly arrived threads and the CAS() would fail.
4546 //     In that case Release() would detach the RATs, re-merge the list in-hand
4547 //     with the RATs and repeat as needed.  Alternately, Release() might
4548 //     detach and extract a successor, but then pass the residual list to the wakee.
4549 //     The wakee would be responsible for reattaching and remerging before it
4550 //     competed for the lock.
4551 //
4552 // Both "pop" and DMR are immune from ABA corruption -- there can be
4553 // multiple concurrent pushers, but only one popper or detacher.
4554 // This implementation pops from the head of the list.  This is unfair,
4555 // but tends to provide excellent throughput as hot threads remain hot.
4556 // (We wake recently run threads first).
4557 //
4558 // All paths through muxRelease() will execute a CAS.
4559 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4560 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4561 // executed within the critical section are complete and globally visible before the
4562 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4563 void Thread::muxRelease(volatile intptr_t * Lock)  {
4564   for (;;) {
4565     const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT);
4566     assert(w & LOCKBIT, "invariant");
4567     if (w == LOCKBIT) return;
4568     ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4569     assert(List != NULL, "invariant");
4570     assert(List->OnList == intptr_t(Lock), "invariant");
4571     ParkEvent * const nxt = List->ListNext;
4572     guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4573 
4574     // The following CAS() releases the lock and pops the head element.
4575     // The CAS() also ratifies the previously fetched lock-word value.
4576     if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4577       continue;
4578     }
4579     List->OnList = 0;
4580     OrderAccess::fence();
4581     List->unpark();
4582     return;
4583   }
4584 }
4585 
4586 
4587 void Threads::verify() {
4588   ALL_JAVA_THREADS(p) {
4589     p->verify();
4590   }
4591   VMThread* thread = VMThread::vm_thread();
4592   if (thread != NULL) thread->verify();
4593 }
--- EOF ---