1 /*
   2  * Copyright (c) 1997, 2011, 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/scopeDesc.hpp"
  31 #include "compiler/compileBroker.hpp"
  32 #include "interpreter/interpreter.hpp"
  33 #include "interpreter/linkResolver.hpp"
  34 #include "interpreter/oopMapCache.hpp"
  35 #include "jvmtifiles/jvmtiEnv.hpp"
  36 #include "memory/oopFactory.hpp"
  37 #include "memory/universe.inline.hpp"
  38 #include "oops/instanceKlass.hpp"
  39 #include "oops/objArrayOop.hpp"
  40 #include "oops/oop.inline.hpp"
  41 #include "oops/symbol.hpp"
  42 #include "prims/jvm_misc.hpp"
  43 #include "prims/jvmtiExport.hpp"
  44 #include "prims/jvmtiThreadState.hpp"
  45 #include "prims/privilegedStack.hpp"
  46 #include "runtime/aprofiler.hpp"
  47 #include "runtime/arguments.hpp"
  48 #include "runtime/biasedLocking.hpp"
  49 #include "runtime/deoptimization.hpp"
  50 #include "runtime/fprofiler.hpp"
  51 #include "runtime/frame.inline.hpp"
  52 #include "runtime/init.hpp"
  53 #include "runtime/interfaceSupport.hpp"
  54 #include "runtime/java.hpp"
  55 #include "runtime/javaCalls.hpp"
  56 #include "runtime/jniPeriodicChecker.hpp"
  57 #include "runtime/memprofiler.hpp"
  58 #include "runtime/mutexLocker.hpp"
  59 #include "runtime/objectMonitor.hpp"
  60 #include "runtime/osThread.hpp"
  61 #include "runtime/safepoint.hpp"
  62 #include "runtime/sharedRuntime.hpp"
  63 #include "runtime/statSampler.hpp"
  64 #include "runtime/stubRoutines.hpp"
  65 #include "runtime/task.hpp"
  66 #include "runtime/threadCritical.hpp"
  67 #include "runtime/threadLocalStorage.hpp"
  68 #include "runtime/vframe.hpp"
  69 #include "runtime/vframeArray.hpp"
  70 #include "runtime/vframe_hp.hpp"
  71 #include "runtime/vmThread.hpp"
  72 #include "runtime/vm_operations.hpp"
  73 #include "services/attachListener.hpp"
  74 #include "services/management.hpp"
  75 #include "services/threadService.hpp"
  76 #include "utilities/defaultStream.hpp"
  77 #include "utilities/dtrace.hpp"
  78 #include "utilities/events.hpp"
  79 #include "utilities/preserveException.hpp"
  80 #ifdef TARGET_OS_FAMILY_linux
  81 # include "os_linux.inline.hpp"
  82 # include "thread_linux.inline.hpp"
  83 #endif
  84 #ifdef TARGET_OS_FAMILY_solaris
  85 # include "os_solaris.inline.hpp"
  86 # include "thread_solaris.inline.hpp"
  87 #endif
  88 #ifdef TARGET_OS_FAMILY_windows
  89 # include "os_windows.inline.hpp"
  90 # include "thread_windows.inline.hpp"
  91 #endif
  92 #ifdef TARGET_OS_FAMILY_bsd
  93 # include "os_bsd.inline.hpp"
  94 # include "thread_bsd.inline.hpp"
  95 #endif
  96 #ifndef SERIALGC
  97 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp"
  98 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
  99 #include "gc_implementation/parallelScavenge/pcTasks.hpp"
 100 #endif
 101 #ifdef COMPILER1
 102 #include "c1/c1_Compiler.hpp"
 103 #endif
 104 #ifdef COMPILER2
 105 #include "opto/c2compiler.hpp"
 106 #include "opto/idealGraphPrinter.hpp"
 107 #endif
 108 
 109 #ifdef DTRACE_ENABLED
 110 
 111 // Only bother with this argument setup if dtrace is available
 112 
 113 HS_DTRACE_PROBE_DECL(hotspot, vm__init__begin);
 114 HS_DTRACE_PROBE_DECL(hotspot, vm__init__end);
 115 HS_DTRACE_PROBE_DECL5(hotspot, thread__start, char*, intptr_t,
 116   intptr_t, intptr_t, bool);
 117 HS_DTRACE_PROBE_DECL5(hotspot, thread__stop, char*, intptr_t,
 118   intptr_t, intptr_t, bool);
 119 
 120 #define DTRACE_THREAD_PROBE(probe, javathread)                             \
 121   {                                                                        \
 122     ResourceMark rm(this);                                                 \
 123     int len = 0;                                                           \
 124     const char* name = (javathread)->get_thread_name();                    \
 125     len = strlen(name);                                                    \
 126     HS_DTRACE_PROBE5(hotspot, thread__##probe,                             \
 127       name, len,                                                           \
 128       java_lang_Thread::thread_id((javathread)->threadObj()),              \
 129       (javathread)->osthread()->thread_id(),                               \
 130       java_lang_Thread::is_daemon((javathread)->threadObj()));             \
 131   }
 132 
 133 #else //  ndef DTRACE_ENABLED
 134 
 135 #define DTRACE_THREAD_PROBE(probe, javathread)
 136 
 137 #endif // ndef DTRACE_ENABLED
 138 
 139 // Class hierarchy
 140 // - Thread
 141 //   - VMThread
 142 //   - WatcherThread
 143 //   - ConcurrentMarkSweepThread
 144 //   - JavaThread
 145 //     - CompilerThread
 146 
 147 // ======= Thread ========
 148 
 149 // Support for forcing alignment of thread objects for biased locking
 150 void* Thread::operator new(size_t size) {
 151   if (UseBiasedLocking) {
 152     const int alignment = markOopDesc::biased_lock_alignment;
 153     size_t aligned_size = size + (alignment - sizeof(intptr_t));
 154     void* real_malloc_addr = CHeapObj::operator new(aligned_size);
 155     void* aligned_addr     = (void*) align_size_up((intptr_t) real_malloc_addr, alignment);
 156     assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
 157            ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
 158            "JavaThread alignment code overflowed allocated storage");
 159     if (TraceBiasedLocking) {
 160       if (aligned_addr != real_malloc_addr)
 161         tty->print_cr("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
 162                       real_malloc_addr, aligned_addr);
 163     }
 164     ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
 165     return aligned_addr;
 166   } else {
 167     return CHeapObj::operator new(size);
 168   }
 169 }
 170 
 171 void Thread::operator delete(void* p) {
 172   if (UseBiasedLocking) {
 173     void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;
 174     CHeapObj::operator delete(real_malloc_addr);
 175   } else {
 176     CHeapObj::operator delete(p);
 177   }
 178 }
 179 
 180 
 181 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
 182 // JavaThread
 183 
 184 
 185 Thread::Thread() {
 186   // stack and get_thread
 187   set_stack_base(NULL);
 188   set_stack_size(0);
 189   set_self_raw_id(0);
 190   set_lgrp_id(-1);
 191 
 192   // allocated data structures
 193   set_osthread(NULL);
 194   set_resource_area(new ResourceArea());
 195   set_handle_area(new HandleArea(NULL));
 196   set_active_handles(NULL);
 197   set_free_handle_block(NULL);
 198   set_last_handle_mark(NULL);
 199 
 200   // This initial value ==> never claimed.
 201   _oops_do_parity = 0;
 202 
 203   // the handle mark links itself to last_handle_mark
 204   new HandleMark(this);
 205 
 206   // plain initialization
 207   debug_only(_owned_locks = NULL;)
 208   debug_only(_allow_allocation_count = 0;)
 209   NOT_PRODUCT(_allow_safepoint_count = 0;)
 210   NOT_PRODUCT(_skip_gcalot = false;)
 211   CHECK_UNHANDLED_OOPS_ONLY(_gc_locked_out_count = 0;)
 212   _jvmti_env_iteration_count = 0;
 213   set_allocated_bytes(0);
 214   _vm_operation_started_count = 0;
 215   _vm_operation_completed_count = 0;
 216   _current_pending_monitor = NULL;
 217   _current_pending_monitor_is_from_java = true;
 218   _current_waiting_monitor = NULL;
 219   _num_nested_signal = 0;
 220   omFreeList = NULL ;
 221   omFreeCount = 0 ;
 222   omFreeProvision = 32 ;
 223   omInUseList = NULL ;
 224   omInUseCount = 0 ;
 225 
 226   _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true);
 227   _suspend_flags = 0;
 228 
 229   // thread-specific hashCode stream generator state - Marsaglia shift-xor form
 230   _hashStateX = os::random() ;
 231   _hashStateY = 842502087 ;
 232   _hashStateZ = 0x8767 ;    // (int)(3579807591LL & 0xffff) ;
 233   _hashStateW = 273326509 ;
 234 
 235   _OnTrap   = 0 ;
 236   _schedctl = NULL ;
 237   _Stalled  = 0 ;
 238   _TypeTag  = 0x2BAD ;
 239 
 240   // Many of the following fields are effectively final - immutable
 241   // Note that nascent threads can't use the Native Monitor-Mutex
 242   // construct until the _MutexEvent is initialized ...
 243   // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
 244   // we might instead use a stack of ParkEvents that we could provision on-demand.
 245   // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
 246   // and ::Release()
 247   _ParkEvent   = ParkEvent::Allocate (this) ;
 248   _SleepEvent  = ParkEvent::Allocate (this) ;
 249   _MutexEvent  = ParkEvent::Allocate (this) ;
 250   _MuxEvent    = ParkEvent::Allocate (this) ;
 251 
 252 #ifdef CHECK_UNHANDLED_OOPS
 253   if (CheckUnhandledOops) {
 254     _unhandled_oops = new UnhandledOops(this);
 255   }
 256 #endif // CHECK_UNHANDLED_OOPS
 257 #ifdef ASSERT
 258   if (UseBiasedLocking) {
 259     assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
 260     assert(this == _real_malloc_address ||
 261            this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment),
 262            "bug in forced alignment of thread objects");
 263   }
 264 #endif /* ASSERT */
 265 }
 266 
 267 void Thread::initialize_thread_local_storage() {
 268   // Note: Make sure this method only calls
 269   // non-blocking operations. Otherwise, it might not work
 270   // with the thread-startup/safepoint interaction.
 271 
 272   // During Java thread startup, safepoint code should allow this
 273   // method to complete because it may need to allocate memory to
 274   // store information for the new thread.
 275 
 276   // initialize structure dependent on thread local storage
 277   ThreadLocalStorage::set_thread(this);
 278 
 279   // set up any platform-specific state.
 280   os::initialize_thread();
 281 
 282 }
 283 
 284 void Thread::record_stack_base_and_size() {
 285   set_stack_base(os::current_stack_base());
 286   set_stack_size(os::current_stack_size());
 287 }
 288 
 289 
 290 Thread::~Thread() {
 291   // Reclaim the objectmonitors from the omFreeList of the moribund thread.
 292   ObjectSynchronizer::omFlush (this) ;
 293 
 294   // deallocate data structures
 295   delete resource_area();
 296   // since the handle marks are using the handle area, we have to deallocated the root
 297   // handle mark before deallocating the thread's handle area,
 298   assert(last_handle_mark() != NULL, "check we have an element");
 299   delete last_handle_mark();
 300   assert(last_handle_mark() == NULL, "check we have reached the end");
 301 
 302   // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
 303   // We NULL out the fields for good hygiene.
 304   ParkEvent::Release (_ParkEvent)   ; _ParkEvent   = NULL ;
 305   ParkEvent::Release (_SleepEvent)  ; _SleepEvent  = NULL ;
 306   ParkEvent::Release (_MutexEvent)  ; _MutexEvent  = NULL ;
 307   ParkEvent::Release (_MuxEvent)    ; _MuxEvent    = NULL ;
 308 
 309   delete handle_area();
 310 
 311   // osthread() can be NULL, if creation of thread failed.
 312   if (osthread() != NULL) os::free_thread(osthread());
 313 
 314   delete _SR_lock;
 315 
 316   // clear thread local storage if the Thread is deleting itself
 317   if (this == Thread::current()) {
 318     ThreadLocalStorage::set_thread(NULL);
 319   } else {
 320     // In the case where we're not the current thread, invalidate all the
 321     // caches in case some code tries to get the current thread or the
 322     // thread that was destroyed, and gets stale information.
 323     ThreadLocalStorage::invalidate_all();
 324   }
 325   CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
 326 }
 327 
 328 // NOTE: dummy function for assertion purpose.
 329 void Thread::run() {
 330   ShouldNotReachHere();
 331 }
 332 
 333 #ifdef ASSERT
 334 // Private method to check for dangling thread pointer
 335 void check_for_dangling_thread_pointer(Thread *thread) {
 336  assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
 337          "possibility of dangling Thread pointer");
 338 }
 339 #endif
 340 
 341 
 342 #ifndef PRODUCT
 343 // Tracing method for basic thread operations
 344 void Thread::trace(const char* msg, const Thread* const thread) {
 345   if (!TraceThreadEvents) return;
 346   ResourceMark rm;
 347   ThreadCritical tc;
 348   const char *name = "non-Java thread";
 349   int prio = -1;
 350   if (thread->is_Java_thread()
 351       && !thread->is_Compiler_thread()) {
 352     // The Threads_lock must be held to get information about
 353     // this thread but may not be in some situations when
 354     // tracing  thread events.
 355     bool release_Threads_lock = false;
 356     if (!Threads_lock->owned_by_self()) {
 357       Threads_lock->lock();
 358       release_Threads_lock = true;
 359     }
 360     JavaThread* jt = (JavaThread *)thread;
 361     name = (char *)jt->get_thread_name();
 362     oop thread_oop = jt->threadObj();
 363     if (thread_oop != NULL) {
 364       prio = java_lang_Thread::priority(thread_oop);
 365     }
 366     if (release_Threads_lock) {
 367       Threads_lock->unlock();
 368     }
 369   }
 370   tty->print_cr("Thread::%s " INTPTR_FORMAT " [%lx] %s (prio: %d)", msg, thread, thread->osthread()->thread_id(), name, prio);
 371 }
 372 #endif
 373 
 374 
 375 ThreadPriority Thread::get_priority(const Thread* const thread) {
 376   trace("get priority", thread);
 377   ThreadPriority priority;
 378   // Can return an error!
 379   (void)os::get_priority(thread, priority);
 380   assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
 381   return priority;
 382 }
 383 
 384 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
 385   trace("set priority", thread);
 386   debug_only(check_for_dangling_thread_pointer(thread);)
 387   // Can return an error!
 388   (void)os::set_priority(thread, priority);
 389 }
 390 
 391 
 392 void Thread::start(Thread* thread) {
 393   trace("start", thread);
 394   // Start is different from resume in that its safety is guaranteed by context or
 395   // being called from a Java method synchronized on the Thread object.
 396   if (!DisableStartThread) {
 397     if (thread->is_Java_thread()) {
 398       // Initialize the thread state to RUNNABLE before starting this thread.
 399       // Can not set it after the thread started because we do not know the
 400       // exact thread state at that time. It could be in MONITOR_WAIT or
 401       // in SLEEPING or some other state.
 402       java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
 403                                           java_lang_Thread::RUNNABLE);
 404     }
 405     os::start_thread(thread);
 406   }
 407 }
 408 
 409 // Enqueue a VM_Operation to do the job for us - sometime later
 410 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
 411   VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
 412   VMThread::execute(vm_stop);
 413 }
 414 
 415 
 416 //
 417 // Check if an external suspend request has completed (or has been
 418 // cancelled). Returns true if the thread is externally suspended and
 419 // false otherwise.
 420 //
 421 // The bits parameter returns information about the code path through
 422 // the routine. Useful for debugging:
 423 //
 424 // set in is_ext_suspend_completed():
 425 // 0x00000001 - routine was entered
 426 // 0x00000010 - routine return false at end
 427 // 0x00000100 - thread exited (return false)
 428 // 0x00000200 - suspend request cancelled (return false)
 429 // 0x00000400 - thread suspended (return true)
 430 // 0x00001000 - thread is in a suspend equivalent state (return true)
 431 // 0x00002000 - thread is native and walkable (return true)
 432 // 0x00004000 - thread is native_trans and walkable (needed retry)
 433 //
 434 // set in wait_for_ext_suspend_completion():
 435 // 0x00010000 - routine was entered
 436 // 0x00020000 - suspend request cancelled before loop (return false)
 437 // 0x00040000 - thread suspended before loop (return true)
 438 // 0x00080000 - suspend request cancelled in loop (return false)
 439 // 0x00100000 - thread suspended in loop (return true)
 440 // 0x00200000 - suspend not completed during retry loop (return false)
 441 //
 442 
 443 // Helper class for tracing suspend wait debug bits.
 444 //
 445 // 0x00000100 indicates that the target thread exited before it could
 446 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
 447 // 0x00080000 each indicate a cancelled suspend request so they don't
 448 // count as wait failures either.
 449 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
 450 
 451 class TraceSuspendDebugBits : public StackObj {
 452  private:
 453   JavaThread * jt;
 454   bool         is_wait;
 455   bool         called_by_wait;  // meaningful when !is_wait
 456   uint32_t *   bits;
 457 
 458  public:
 459   TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
 460                         uint32_t *_bits) {
 461     jt             = _jt;
 462     is_wait        = _is_wait;
 463     called_by_wait = _called_by_wait;
 464     bits           = _bits;
 465   }
 466 
 467   ~TraceSuspendDebugBits() {
 468     if (!is_wait) {
 469 #if 1
 470       // By default, don't trace bits for is_ext_suspend_completed() calls.
 471       // That trace is very chatty.
 472       return;
 473 #else
 474       if (!called_by_wait) {
 475         // If tracing for is_ext_suspend_completed() is enabled, then only
 476         // trace calls to it from wait_for_ext_suspend_completion()
 477         return;
 478       }
 479 #endif
 480     }
 481 
 482     if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
 483       if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
 484         MutexLocker ml(Threads_lock);  // needed for get_thread_name()
 485         ResourceMark rm;
 486 
 487         tty->print_cr(
 488             "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
 489             jt->get_thread_name(), *bits);
 490 
 491         guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
 492       }
 493     }
 494   }
 495 };
 496 #undef DEBUG_FALSE_BITS
 497 
 498 
 499 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, uint32_t *bits) {
 500   TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
 501 
 502   bool did_trans_retry = false;  // only do thread_in_native_trans retry once
 503   bool do_trans_retry;           // flag to force the retry
 504 
 505   *bits |= 0x00000001;
 506 
 507   do {
 508     do_trans_retry = false;
 509 
 510     if (is_exiting()) {
 511       // Thread is in the process of exiting. This is always checked
 512       // first to reduce the risk of dereferencing a freed JavaThread.
 513       *bits |= 0x00000100;
 514       return false;
 515     }
 516 
 517     if (!is_external_suspend()) {
 518       // Suspend request is cancelled. This is always checked before
 519       // is_ext_suspended() to reduce the risk of a rogue resume
 520       // confusing the thread that made the suspend request.
 521       *bits |= 0x00000200;
 522       return false;
 523     }
 524 
 525     if (is_ext_suspended()) {
 526       // thread is suspended
 527       *bits |= 0x00000400;
 528       return true;
 529     }
 530 
 531     // Now that we no longer do hard suspends of threads running
 532     // native code, the target thread can be changing thread state
 533     // while we are in this routine:
 534     //
 535     //   _thread_in_native -> _thread_in_native_trans -> _thread_blocked
 536     //
 537     // We save a copy of the thread state as observed at this moment
 538     // and make our decision about suspend completeness based on the
 539     // copy. This closes the race where the thread state is seen as
 540     // _thread_in_native_trans in the if-thread_blocked check, but is
 541     // seen as _thread_blocked in if-thread_in_native_trans check.
 542     JavaThreadState save_state = thread_state();
 543 
 544     if (save_state == _thread_blocked && is_suspend_equivalent()) {
 545       // If the thread's state is _thread_blocked and this blocking
 546       // condition is known to be equivalent to a suspend, then we can
 547       // consider the thread to be externally suspended. This means that
 548       // the code that sets _thread_blocked has been modified to do
 549       // self-suspension if the blocking condition releases. We also
 550       // used to check for CONDVAR_WAIT here, but that is now covered by
 551       // the _thread_blocked with self-suspension check.
 552       //
 553       // Return true since we wouldn't be here unless there was still an
 554       // external suspend request.
 555       *bits |= 0x00001000;
 556       return true;
 557     } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
 558       // Threads running native code will self-suspend on native==>VM/Java
 559       // transitions. If its stack is walkable (should always be the case
 560       // unless this function is called before the actual java_suspend()
 561       // call), then the wait is done.
 562       *bits |= 0x00002000;
 563       return true;
 564     } else if (!called_by_wait && !did_trans_retry &&
 565                save_state == _thread_in_native_trans &&
 566                frame_anchor()->walkable()) {
 567       // The thread is transitioning from thread_in_native to another
 568       // thread state. check_safepoint_and_suspend_for_native_trans()
 569       // will force the thread to self-suspend. If it hasn't gotten
 570       // there yet we may have caught the thread in-between the native
 571       // code check above and the self-suspend. Lucky us. If we were
 572       // called by wait_for_ext_suspend_completion(), then it
 573       // will be doing the retries so we don't have to.
 574       //
 575       // Since we use the saved thread state in the if-statement above,
 576       // there is a chance that the thread has already transitioned to
 577       // _thread_blocked by the time we get here. In that case, we will
 578       // make a single unnecessary pass through the logic below. This
 579       // doesn't hurt anything since we still do the trans retry.
 580 
 581       *bits |= 0x00004000;
 582 
 583       // Once the thread leaves thread_in_native_trans for another
 584       // thread state, we break out of this retry loop. We shouldn't
 585       // need this flag to prevent us from getting back here, but
 586       // sometimes paranoia is good.
 587       did_trans_retry = true;
 588 
 589       // We wait for the thread to transition to a more usable state.
 590       for (int i = 1; i <= SuspendRetryCount; i++) {
 591         // We used to do an "os::yield_all(i)" call here with the intention
 592         // that yielding would increase on each retry. However, the parameter
 593         // is ignored on Linux which means the yield didn't scale up. Waiting
 594         // on the SR_lock below provides a much more predictable scale up for
 595         // the delay. It also provides a simple/direct point to check for any
 596         // safepoint requests from the VMThread
 597 
 598         // temporarily drops SR_lock while doing wait with safepoint check
 599         // (if we're a JavaThread - the WatcherThread can also call this)
 600         // and increase delay with each retry
 601         SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 602 
 603         // check the actual thread state instead of what we saved above
 604         if (thread_state() != _thread_in_native_trans) {
 605           // the thread has transitioned to another thread state so
 606           // try all the checks (except this one) one more time.
 607           do_trans_retry = true;
 608           break;
 609         }
 610       } // end retry loop
 611 
 612 
 613     }
 614   } while (do_trans_retry);
 615 
 616   *bits |= 0x00000010;
 617   return false;
 618 }
 619 
 620 //
 621 // Wait for an external suspend request to complete (or be cancelled).
 622 // Returns true if the thread is externally suspended and false otherwise.
 623 //
 624 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
 625        uint32_t *bits) {
 626   TraceSuspendDebugBits tsdb(this, true /* is_wait */,
 627                              false /* !called_by_wait */, bits);
 628 
 629   // local flag copies to minimize SR_lock hold time
 630   bool is_suspended;
 631   bool pending;
 632   uint32_t reset_bits;
 633 
 634   // set a marker so is_ext_suspend_completed() knows we are the caller
 635   *bits |= 0x00010000;
 636 
 637   // We use reset_bits to reinitialize the bits value at the top of
 638   // each retry loop. This allows the caller to make use of any
 639   // unused bits for their own marking purposes.
 640   reset_bits = *bits;
 641 
 642   {
 643     MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
 644     is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 645                                             delay, bits);
 646     pending = is_external_suspend();
 647   }
 648   // must release SR_lock to allow suspension to complete
 649 
 650   if (!pending) {
 651     // A cancelled suspend request is the only false return from
 652     // is_ext_suspend_completed() that keeps us from entering the
 653     // retry loop.
 654     *bits |= 0x00020000;
 655     return false;
 656   }
 657 
 658   if (is_suspended) {
 659     *bits |= 0x00040000;
 660     return true;
 661   }
 662 
 663   for (int i = 1; i <= retries; i++) {
 664     *bits = reset_bits;  // reinit to only track last retry
 665 
 666     // We used to do an "os::yield_all(i)" call here with the intention
 667     // that yielding would increase on each retry. However, the parameter
 668     // is ignored on Linux which means the yield didn't scale up. Waiting
 669     // on the SR_lock below provides a much more predictable scale up for
 670     // the delay. It also provides a simple/direct point to check for any
 671     // safepoint requests from the VMThread
 672 
 673     {
 674       MutexLocker ml(SR_lock());
 675       // wait with safepoint check (if we're a JavaThread - the WatcherThread
 676       // can also call this)  and increase delay with each retry
 677       SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 678 
 679       is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 680                                               delay, bits);
 681 
 682       // It is possible for the external suspend request to be cancelled
 683       // (by a resume) before the actual suspend operation is completed.
 684       // Refresh our local copy to see if we still need to wait.
 685       pending = is_external_suspend();
 686     }
 687 
 688     if (!pending) {
 689       // A cancelled suspend request is the only false return from
 690       // is_ext_suspend_completed() that keeps us from staying in the
 691       // retry loop.
 692       *bits |= 0x00080000;
 693       return false;
 694     }
 695 
 696     if (is_suspended) {
 697       *bits |= 0x00100000;
 698       return true;
 699     }
 700   } // end retry loop
 701 
 702   // thread did not suspend after all our retries
 703   *bits |= 0x00200000;
 704   return false;
 705 }
 706 
 707 #ifndef PRODUCT
 708 void JavaThread::record_jump(address target, address instr, const char* file, int line) {
 709 
 710   // This should not need to be atomic as the only way for simultaneous
 711   // updates is via interrupts. Even then this should be rare or non-existant
 712   // and we don't care that much anyway.
 713 
 714   int index = _jmp_ring_index;
 715   _jmp_ring_index = (index + 1 ) & (jump_ring_buffer_size - 1);
 716   _jmp_ring[index]._target = (intptr_t) target;
 717   _jmp_ring[index]._instruction = (intptr_t) instr;
 718   _jmp_ring[index]._file = file;
 719   _jmp_ring[index]._line = line;
 720 }
 721 #endif /* PRODUCT */
 722 
 723 // Called by flat profiler
 724 // Callers have already called wait_for_ext_suspend_completion
 725 // The assertion for that is currently too complex to put here:
 726 bool JavaThread::profile_last_Java_frame(frame* _fr) {
 727   bool gotframe = false;
 728   // self suspension saves needed state.
 729   if (has_last_Java_frame() && _anchor.walkable()) {
 730      *_fr = pd_last_frame();
 731      gotframe = true;
 732   }
 733   return gotframe;
 734 }
 735 
 736 void Thread::interrupt(Thread* thread) {
 737   trace("interrupt", thread);
 738   debug_only(check_for_dangling_thread_pointer(thread);)
 739   os::interrupt(thread);
 740 }
 741 
 742 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
 743   trace("is_interrupted", thread);
 744   debug_only(check_for_dangling_thread_pointer(thread);)
 745   // Note:  If clear_interrupted==false, this simply fetches and
 746   // returns the value of the field osthread()->interrupted().
 747   return os::is_interrupted(thread, clear_interrupted);
 748 }
 749 
 750 
 751 // GC Support
 752 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
 753   jint thread_parity = _oops_do_parity;
 754   if (thread_parity != strong_roots_parity) {
 755     jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
 756     if (res == thread_parity) {
 757       return true;
 758     } else {
 759       guarantee(res == strong_roots_parity, "Or else what?");
 760       assert(SharedHeap::heap()->n_par_threads() > 0,
 761              "Should only fail when parallel.");
 762       return false;
 763     }
 764   }
 765   assert(SharedHeap::heap()->n_par_threads() > 0,
 766          "Should only fail when parallel.");
 767   return false;
 768 }
 769 
 770 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
 771   active_handles()->oops_do(f);
 772   // Do oop for ThreadShadow
 773   f->do_oop((oop*)&_pending_exception);
 774   handle_area()->oops_do(f);
 775 }
 776 
 777 void Thread::nmethods_do(CodeBlobClosure* cf) {
 778   // no nmethods in a generic thread...
 779 }
 780 
 781 void Thread::print_on(outputStream* st) const {
 782   // get_priority assumes osthread initialized
 783   if (osthread() != NULL) {
 784     st->print("prio=%d tid=" INTPTR_FORMAT " ", get_priority(this), this);
 785     osthread()->print_on(st);
 786   }
 787   debug_only(if (WizardMode) print_owned_locks_on(st);)
 788 }
 789 
 790 // Thread::print_on_error() is called by fatal error handler. Don't use
 791 // any lock or allocate memory.
 792 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
 793   if      (is_VM_thread())                  st->print("VMThread");
 794   else if (is_Compiler_thread())            st->print("CompilerThread");
 795   else if (is_Java_thread())                st->print("JavaThread");
 796   else if (is_GC_task_thread())             st->print("GCTaskThread");
 797   else if (is_Watcher_thread())             st->print("WatcherThread");
 798   else if (is_ConcurrentGC_thread())        st->print("ConcurrentGCThread");
 799   else st->print("Thread");
 800 
 801   st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
 802             _stack_base - _stack_size, _stack_base);
 803 
 804   if (osthread()) {
 805     st->print(" [id=%d]", osthread()->thread_id());
 806   }
 807 }
 808 
 809 #ifdef ASSERT
 810 void Thread::print_owned_locks_on(outputStream* st) const {
 811   Monitor *cur = _owned_locks;
 812   if (cur == NULL) {
 813     st->print(" (no locks) ");
 814   } else {
 815     st->print_cr(" Locks owned:");
 816     while(cur) {
 817       cur->print_on(st);
 818       cur = cur->next();
 819     }
 820   }
 821 }
 822 
 823 static int ref_use_count  = 0;
 824 
 825 bool Thread::owns_locks_but_compiled_lock() const {
 826   for(Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 827     if (cur != Compile_lock) return true;
 828   }
 829   return false;
 830 }
 831 
 832 
 833 #endif
 834 
 835 #ifndef PRODUCT
 836 
 837 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
 838 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
 839 // no threads which allow_vm_block's are held
 840 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
 841     // Check if current thread is allowed to block at a safepoint
 842     if (!(_allow_safepoint_count == 0))
 843       fatal("Possible safepoint reached by thread that does not allow it");
 844     if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
 845       fatal("LEAF method calling lock?");
 846     }
 847 
 848 #ifdef ASSERT
 849     if (potential_vm_operation && is_Java_thread()
 850         && !Universe::is_bootstrapping()) {
 851       // Make sure we do not hold any locks that the VM thread also uses.
 852       // This could potentially lead to deadlocks
 853       for(Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 854         // Threads_lock is special, since the safepoint synchronization will not start before this is
 855         // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
 856         // since it is used to transfer control between JavaThreads and the VMThread
 857         // Do not *exclude* any locks unless you are absolutly sure it is correct. Ask someone else first!
 858         if ( (cur->allow_vm_block() &&
 859               cur != Threads_lock &&
 860               cur != Compile_lock &&               // Temporary: should not be necessary when we get spearate compilation
 861               cur != VMOperationRequest_lock &&
 862               cur != VMOperationQueue_lock) ||
 863               cur->rank() == Mutex::special) {
 864           warning("Thread holding lock at safepoint that vm can block on: %s", cur->name());
 865         }
 866       }
 867     }
 868 
 869     if (GCALotAtAllSafepoints) {
 870       // We could enter a safepoint here and thus have a gc
 871       InterfaceSupport::check_gc_alot();
 872     }
 873 #endif
 874 }
 875 #endif
 876 
 877 bool Thread::is_in_stack(address adr) const {
 878   assert(Thread::current() == this, "is_in_stack can only be called from current thread");
 879   address end = os::current_stack_pointer();
 880   if (stack_base() >= adr && adr >= end) return true;
 881 
 882   return false;
 883 }
 884 
 885 
 886 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
 887 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
 888 // used for compilation in the future. If that change is made, the need for these methods
 889 // should be revisited, and they should be removed if possible.
 890 
 891 bool Thread::is_lock_owned(address adr) const {
 892   return on_local_stack(adr);
 893 }
 894 
 895 bool Thread::set_as_starting_thread() {
 896  // NOTE: this must be called inside the main thread.
 897   return os::create_main_thread((JavaThread*)this);
 898 }
 899 
 900 static void initialize_class(Symbol* class_name, TRAPS) {
 901   klassOop klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
 902   instanceKlass::cast(klass)->initialize(CHECK);
 903 }
 904 
 905 
 906 // Creates the initial ThreadGroup
 907 static Handle create_initial_thread_group(TRAPS) {
 908   klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
 909   instanceKlassHandle klass (THREAD, k);
 910 
 911   Handle system_instance = klass->allocate_instance_handle(CHECK_NH);
 912   {
 913     JavaValue result(T_VOID);
 914     JavaCalls::call_special(&result,
 915                             system_instance,
 916                             klass,
 917                             vmSymbols::object_initializer_name(),
 918                             vmSymbols::void_method_signature(),
 919                             CHECK_NH);
 920   }
 921   Universe::set_system_thread_group(system_instance());
 922 
 923   Handle main_instance = klass->allocate_instance_handle(CHECK_NH);
 924   {
 925     JavaValue result(T_VOID);
 926     Handle string = java_lang_String::create_from_str("main", CHECK_NH);
 927     JavaCalls::call_special(&result,
 928                             main_instance,
 929                             klass,
 930                             vmSymbols::object_initializer_name(),
 931                             vmSymbols::threadgroup_string_void_signature(),
 932                             system_instance,
 933                             string,
 934                             CHECK_NH);
 935   }
 936   return main_instance;
 937 }
 938 
 939 // Creates the initial Thread
 940 static oop create_initial_thread(Handle thread_group, JavaThread* thread, TRAPS) {
 941   klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
 942   instanceKlassHandle klass (THREAD, k);
 943   instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);
 944 
 945   java_lang_Thread::set_thread(thread_oop(), thread);
 946   java_lang_Thread::set_priority(thread_oop(), NormPriority);
 947   thread->set_threadObj(thread_oop());
 948 
 949   Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
 950 
 951   JavaValue result(T_VOID);
 952   JavaCalls::call_special(&result, thread_oop,
 953                                    klass,
 954                                    vmSymbols::object_initializer_name(),
 955                                    vmSymbols::threadgroup_string_void_signature(),
 956                                    thread_group,
 957                                    string,
 958                                    CHECK_NULL);
 959   return thread_oop();
 960 }
 961 
 962 static void call_initializeSystemClass(TRAPS) {
 963   klassOop k =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
 964   instanceKlassHandle klass (THREAD, k);
 965 
 966   JavaValue result(T_VOID);
 967   JavaCalls::call_static(&result, klass, vmSymbols::initializeSystemClass_name(),
 968                                          vmSymbols::void_method_signature(), CHECK);
 969 }
 970 
 971 // General purpose hook into Java code, run once when the VM is initialized.
 972 // The Java library method itself may be changed independently from the VM.
 973 static void call_postVMInitHook(TRAPS) {
 974   klassOop k = SystemDictionary::PostVMInitHook_klass();
 975   instanceKlassHandle klass (THREAD, k);
 976   if (klass.not_null()) {
 977     JavaValue result(T_VOID);
 978     JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
 979                                            vmSymbols::void_method_signature(),
 980                                            CHECK);
 981   }
 982 }
 983 
 984 static void reset_vm_info_property(TRAPS) {
 985   // the vm info string
 986   ResourceMark rm(THREAD);
 987   const char *vm_info = VM_Version::vm_info_string();
 988 
 989   // java.lang.System class
 990   klassOop k =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
 991   instanceKlassHandle klass (THREAD, k);
 992 
 993   // setProperty arguments
 994   Handle key_str    = java_lang_String::create_from_str("java.vm.info", CHECK);
 995   Handle value_str  = java_lang_String::create_from_str(vm_info, CHECK);
 996 
 997   // return value
 998   JavaValue r(T_OBJECT);
 999 
1000   // public static String setProperty(String key, String value);
1001   JavaCalls::call_static(&r,
1002                          klass,
1003                          vmSymbols::setProperty_name(),
1004                          vmSymbols::string_string_string_signature(),
1005                          key_str,
1006                          value_str,
1007                          CHECK);
1008 }
1009 
1010 
1011 void JavaThread::allocate_threadObj(Handle thread_group, char* thread_name, bool daemon, TRAPS) {
1012   assert(thread_group.not_null(), "thread group should be specified");
1013   assert(threadObj() == NULL, "should only create Java thread object once");
1014 
1015   klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1016   instanceKlassHandle klass (THREAD, k);
1017   instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
1018 
1019   java_lang_Thread::set_thread(thread_oop(), this);
1020   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1021   set_threadObj(thread_oop());
1022 
1023   JavaValue result(T_VOID);
1024   if (thread_name != NULL) {
1025     Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1026     // Thread gets assigned specified name and null target
1027     JavaCalls::call_special(&result,
1028                             thread_oop,
1029                             klass,
1030                             vmSymbols::object_initializer_name(),
1031                             vmSymbols::threadgroup_string_void_signature(),
1032                             thread_group, // Argument 1
1033                             name,         // Argument 2
1034                             THREAD);
1035   } else {
1036     // Thread gets assigned name "Thread-nnn" and null target
1037     // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1038     JavaCalls::call_special(&result,
1039                             thread_oop,
1040                             klass,
1041                             vmSymbols::object_initializer_name(),
1042                             vmSymbols::threadgroup_runnable_void_signature(),
1043                             thread_group, // Argument 1
1044                             Handle(),     // Argument 2
1045                             THREAD);
1046   }
1047 
1048 
1049   if (daemon) {
1050       java_lang_Thread::set_daemon(thread_oop());
1051   }
1052 
1053   if (HAS_PENDING_EXCEPTION) {
1054     return;
1055   }
1056 
1057   KlassHandle group(this, SystemDictionary::ThreadGroup_klass());
1058   Handle threadObj(this, this->threadObj());
1059 
1060   JavaCalls::call_special(&result,
1061                          thread_group,
1062                          group,
1063                          vmSymbols::add_method_name(),
1064                          vmSymbols::thread_void_signature(),
1065                          threadObj,          // Arg 1
1066                          THREAD);
1067 
1068 
1069 }
1070 
1071 // NamedThread --  non-JavaThread subclasses with multiple
1072 // uniquely named instances should derive from this.
1073 NamedThread::NamedThread() : Thread() {
1074   _name = NULL;
1075   _processed_thread = NULL;
1076 }
1077 
1078 NamedThread::~NamedThread() {
1079   if (_name != NULL) {
1080     FREE_C_HEAP_ARRAY(char, _name);
1081     _name = NULL;
1082   }
1083 }
1084 
1085 void NamedThread::set_name(const char* format, ...) {
1086   guarantee(_name == NULL, "Only get to set name once.");
1087   _name = NEW_C_HEAP_ARRAY(char, max_name_len);
1088   guarantee(_name != NULL, "alloc failure");
1089   va_list ap;
1090   va_start(ap, format);
1091   jio_vsnprintf(_name, max_name_len, format, ap);
1092   va_end(ap);
1093 }
1094 
1095 // ======= WatcherThread ========
1096 
1097 // The watcher thread exists to simulate timer interrupts.  It should
1098 // be replaced by an abstraction over whatever native support for
1099 // timer interrupts exists on the platform.
1100 
1101 WatcherThread* WatcherThread::_watcher_thread   = NULL;
1102 volatile bool  WatcherThread::_should_terminate = false;
1103 
1104 WatcherThread::WatcherThread() : Thread() {
1105   assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1106   if (os::create_thread(this, os::watcher_thread)) {
1107     _watcher_thread = this;
1108 
1109     // Set the watcher thread to the highest OS priority which should not be
1110     // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1111     // is created. The only normal thread using this priority is the reference
1112     // handler thread, which runs for very short intervals only.
1113     // If the VMThread's priority is not lower than the WatcherThread profiling
1114     // will be inaccurate.
1115     os::set_priority(this, MaxPriority);
1116     if (!DisableStartThread) {
1117       os::start_thread(this);
1118     }
1119   }
1120 }
1121 
1122 void WatcherThread::run() {
1123   assert(this == watcher_thread(), "just checking");
1124 
1125   this->record_stack_base_and_size();
1126   this->initialize_thread_local_storage();
1127   this->set_active_handles(JNIHandleBlock::allocate_block());
1128   while(!_should_terminate) {
1129     assert(watcher_thread() == Thread::current(),  "thread consistency check");
1130     assert(watcher_thread() == this,  "thread consistency check");
1131 
1132     // Calculate how long it'll be until the next PeriodicTask work
1133     // should be done, and sleep that amount of time.
1134     size_t time_to_wait = PeriodicTask::time_to_wait();
1135 
1136     // we expect this to timeout - we only ever get unparked when
1137     // we should terminate
1138     {
1139       OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1140 
1141       jlong prev_time = os::javaTimeNanos();
1142       for (;;) {
1143         int res= _SleepEvent->park(time_to_wait);
1144         if (res == OS_TIMEOUT || _should_terminate)
1145           break;
1146         // spurious wakeup of some kind
1147         jlong now = os::javaTimeNanos();
1148         time_to_wait -= (now - prev_time) / 1000000;
1149         if (time_to_wait <= 0)
1150           break;
1151         prev_time = now;
1152       }
1153     }
1154 
1155     if (is_error_reported()) {
1156       // A fatal error has happened, the error handler(VMError::report_and_die)
1157       // should abort JVM after creating an error log file. However in some
1158       // rare cases, the error handler itself might deadlock. Here we try to
1159       // kill JVM if the fatal error handler fails to abort in 2 minutes.
1160       //
1161       // This code is in WatcherThread because WatcherThread wakes up
1162       // periodically so the fatal error handler doesn't need to do anything;
1163       // also because the WatcherThread is less likely to crash than other
1164       // threads.
1165 
1166       for (;;) {
1167         if (!ShowMessageBoxOnError
1168          && (OnError == NULL || OnError[0] == '\0')
1169          && Arguments::abort_hook() == NULL) {
1170              os::sleep(this, 2 * 60 * 1000, false);
1171              fdStream err(defaultStream::output_fd());
1172              err.print_raw_cr("# [ timer expired, abort... ]");
1173              // skip atexit/vm_exit/vm_abort hooks
1174              os::die();
1175         }
1176 
1177         // Wake up 5 seconds later, the fatal handler may reset OnError or
1178         // ShowMessageBoxOnError when it is ready to abort.
1179         os::sleep(this, 5 * 1000, false);
1180       }
1181     }
1182 
1183     PeriodicTask::real_time_tick(time_to_wait);
1184 
1185     // If we have no more tasks left due to dynamic disenrollment,
1186     // shut down the thread since we don't currently support dynamic enrollment
1187     if (PeriodicTask::num_tasks() == 0) {
1188       _should_terminate = true;
1189     }
1190   }
1191 
1192   // Signal that it is terminated
1193   {
1194     MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1195     _watcher_thread = NULL;
1196     Terminator_lock->notify();
1197   }
1198 
1199   // Thread destructor usually does this..
1200   ThreadLocalStorage::set_thread(NULL);
1201 }
1202 
1203 void WatcherThread::start() {
1204   if (watcher_thread() == NULL) {
1205     _should_terminate = false;
1206     // Create the single instance of WatcherThread
1207     new WatcherThread();
1208   }
1209 }
1210 
1211 void WatcherThread::stop() {
1212   // it is ok to take late safepoints here, if needed
1213   MutexLocker mu(Terminator_lock);
1214   _should_terminate = true;
1215   OrderAccess::fence();  // ensure WatcherThread sees update in main loop
1216 
1217   Thread* watcher = watcher_thread();
1218   if (watcher != NULL)
1219     watcher->_SleepEvent->unpark();
1220 
1221   while(watcher_thread() != NULL) {
1222     // This wait should make safepoint checks, wait without a timeout,
1223     // and wait as a suspend-equivalent condition.
1224     //
1225     // Note: If the FlatProfiler is running, then this thread is waiting
1226     // for the WatcherThread to terminate and the WatcherThread, via the
1227     // FlatProfiler task, is waiting for the external suspend request on
1228     // this thread to complete. wait_for_ext_suspend_completion() will
1229     // eventually timeout, but that takes time. Making this wait a
1230     // suspend-equivalent condition solves that timeout problem.
1231     //
1232     Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1233                           Mutex::_as_suspend_equivalent_flag);
1234   }
1235 }
1236 
1237 void WatcherThread::print_on(outputStream* st) const {
1238   st->print("\"%s\" ", name());
1239   Thread::print_on(st);
1240   st->cr();
1241 }
1242 
1243 // ======= JavaThread ========
1244 
1245 // A JavaThread is a normal Java thread
1246 
1247 void JavaThread::initialize() {
1248   // Initialize fields
1249 
1250   // Set the claimed par_id to -1 (ie not claiming any par_ids)
1251   set_claimed_par_id(-1);
1252 
1253   set_saved_exception_pc(NULL);
1254   set_threadObj(NULL);
1255   _anchor.clear();
1256   set_entry_point(NULL);
1257   set_jni_functions(jni_functions());
1258   set_callee_target(NULL);
1259   set_vm_result(NULL);
1260   set_vm_result_2(NULL);
1261   set_vframe_array_head(NULL);
1262   set_vframe_array_last(NULL);
1263   set_deferred_locals(NULL);
1264   set_deopt_mark(NULL);
1265   set_deopt_nmethod(NULL);
1266   clear_must_deopt_id();
1267   set_monitor_chunks(NULL);
1268   set_next(NULL);
1269   set_thread_state(_thread_new);
1270   _terminated = _not_terminated;
1271   _privileged_stack_top = NULL;
1272   _array_for_gc = NULL;
1273   _suspend_equivalent = false;
1274   _in_deopt_handler = 0;
1275   _doing_unsafe_access = false;
1276   _stack_guard_state = stack_guard_unused;
1277   _exception_oop = NULL;
1278   _exception_pc  = 0;
1279   _exception_handler_pc = 0;
1280   _is_method_handle_return = 0;
1281   _jvmti_thread_state= NULL;
1282   _should_post_on_exceptions_flag = JNI_FALSE;
1283   _jvmti_get_loaded_classes_closure = NULL;
1284   _interp_only_mode    = 0;
1285   _special_runtime_exit_condition = _no_async_condition;
1286   _pending_async_exception = NULL;
1287   _is_compiling = false;
1288   _thread_stat = NULL;
1289   _thread_stat = new ThreadStatistics();
1290   _blocked_on_compilation = false;
1291   _jni_active_critical = 0;
1292   _do_not_unlock_if_synchronized = false;
1293   _cached_monitor_info = NULL;
1294   _parker = Parker::Allocate(this) ;
1295 
1296 #ifndef PRODUCT
1297   _jmp_ring_index = 0;
1298   for (int ji = 0 ; ji < jump_ring_buffer_size ; ji++ ) {
1299     record_jump(NULL, NULL, NULL, 0);
1300   }
1301 #endif /* PRODUCT */
1302 
1303   set_thread_profiler(NULL);
1304   if (FlatProfiler::is_active()) {
1305     // This is where we would decide to either give each thread it's own profiler
1306     // or use one global one from FlatProfiler,
1307     // or up to some count of the number of profiled threads, etc.
1308     ThreadProfiler* pp = new ThreadProfiler();
1309     pp->engage();
1310     set_thread_profiler(pp);
1311   }
1312 
1313   // Setup safepoint state info for this thread
1314   ThreadSafepointState::create(this);
1315 
1316   debug_only(_java_call_counter = 0);
1317 
1318   // JVMTI PopFrame support
1319   _popframe_condition = popframe_inactive;
1320   _popframe_preserved_args = NULL;
1321   _popframe_preserved_args_size = 0;
1322 
1323   pd_initialize();
1324 }
1325 
1326 #ifndef SERIALGC
1327 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1328 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1329 #endif // !SERIALGC
1330 
1331 JavaThread::JavaThread(bool is_attaching) :
1332   Thread()
1333 #ifndef SERIALGC
1334   , _satb_mark_queue(&_satb_mark_queue_set),
1335   _dirty_card_queue(&_dirty_card_queue_set)
1336 #endif // !SERIALGC
1337 {
1338   initialize();
1339   _is_attaching = is_attaching;
1340   assert(_deferred_card_mark.is_empty(), "Default MemRegion ctor");
1341 }
1342 
1343 bool JavaThread::reguard_stack(address cur_sp) {
1344   if (_stack_guard_state != stack_guard_yellow_disabled) {
1345     return true; // Stack already guarded or guard pages not needed.
1346   }
1347 
1348   if (register_stack_overflow()) {
1349     // For those architectures which have separate register and
1350     // memory stacks, we must check the register stack to see if
1351     // it has overflowed.
1352     return false;
1353   }
1354 
1355   // Java code never executes within the yellow zone: the latter is only
1356   // there to provoke an exception during stack banging.  If java code
1357   // is executing there, either StackShadowPages should be larger, or
1358   // some exception code in c1, c2 or the interpreter isn't unwinding
1359   // when it should.
1360   guarantee(cur_sp > stack_yellow_zone_base(), "not enough space to reguard - increase StackShadowPages");
1361 
1362   enable_stack_yellow_zone();
1363   return true;
1364 }
1365 
1366 bool JavaThread::reguard_stack(void) {
1367   return reguard_stack(os::current_stack_pointer());
1368 }
1369 
1370 
1371 void JavaThread::block_if_vm_exited() {
1372   if (_terminated == _vm_exited) {
1373     // _vm_exited is set at safepoint, and Threads_lock is never released
1374     // we will block here forever
1375     Threads_lock->lock_without_safepoint_check();
1376     ShouldNotReachHere();
1377   }
1378 }
1379 
1380 
1381 // Remove this ifdef when C1 is ported to the compiler interface.
1382 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1383 
1384 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1385   Thread()
1386 #ifndef SERIALGC
1387   , _satb_mark_queue(&_satb_mark_queue_set),
1388   _dirty_card_queue(&_dirty_card_queue_set)
1389 #endif // !SERIALGC
1390 {
1391   if (TraceThreadEvents) {
1392     tty->print_cr("creating thread %p", this);
1393   }
1394   initialize();
1395   _is_attaching = false;
1396   set_entry_point(entry_point);
1397   // Create the native thread itself.
1398   // %note runtime_23
1399   os::ThreadType thr_type = os::java_thread;
1400   thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1401                                                      os::java_thread;
1402   os::create_thread(this, thr_type, stack_sz);
1403 
1404   // The _osthread may be NULL here because we ran out of memory (too many threads active).
1405   // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1406   // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1407   // the exception consists of creating the exception object & initializing it, initialization
1408   // will leave the VM via a JavaCall and then all locks must be unlocked).
1409   //
1410   // The thread is still suspended when we reach here. Thread must be explicit started
1411   // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1412   // by calling Threads:add. The reason why this is not done here, is because the thread
1413   // object must be fully initialized (take a look at JVM_Start)
1414 }
1415 
1416 JavaThread::~JavaThread() {
1417   if (TraceThreadEvents) {
1418       tty->print_cr("terminate thread %p", this);
1419   }
1420 
1421   // JSR166 -- return the parker to the free list
1422   Parker::Release(_parker);
1423   _parker = NULL ;
1424 
1425   // Free any remaining  previous UnrollBlock
1426   vframeArray* old_array = vframe_array_last();
1427 
1428   if (old_array != NULL) {
1429     Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1430     old_array->set_unroll_block(NULL);
1431     delete old_info;
1432     delete old_array;
1433   }
1434 
1435   GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1436   if (deferred != NULL) {
1437     // This can only happen if thread is destroyed before deoptimization occurs.
1438     assert(deferred->length() != 0, "empty array!");
1439     do {
1440       jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1441       deferred->remove_at(0);
1442       // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1443       delete dlv;
1444     } while (deferred->length() != 0);
1445     delete deferred;
1446   }
1447 
1448   // All Java related clean up happens in exit
1449   ThreadSafepointState::destroy(this);
1450   if (_thread_profiler != NULL) delete _thread_profiler;
1451   if (_thread_stat != NULL) delete _thread_stat;
1452 }
1453 
1454 
1455 // The first routine called by a new Java thread
1456 void JavaThread::run() {
1457   // initialize thread-local alloc buffer related fields
1458   this->initialize_tlab();
1459 
1460   // used to test validitity of stack trace backs
1461   this->record_base_of_stack_pointer();
1462 
1463   // Record real stack base and size.
1464   this->record_stack_base_and_size();
1465 
1466   // Initialize thread local storage; set before calling MutexLocker
1467   this->initialize_thread_local_storage();
1468 
1469   this->create_stack_guard_pages();
1470 
1471   this->cache_global_variables();
1472 
1473   // Thread is now sufficient initialized to be handled by the safepoint code as being
1474   // in the VM. Change thread state from _thread_new to _thread_in_vm
1475   ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1476 
1477   assert(JavaThread::current() == this, "sanity check");
1478   assert(!Thread::current()->owns_locks(), "sanity check");
1479 
1480   DTRACE_THREAD_PROBE(start, this);
1481 
1482   // This operation might block. We call that after all safepoint checks for a new thread has
1483   // been completed.
1484   this->set_active_handles(JNIHandleBlock::allocate_block());
1485 
1486   if (JvmtiExport::should_post_thread_life()) {
1487     JvmtiExport::post_thread_start(this);
1488   }
1489 
1490   // We call another function to do the rest so we are sure that the stack addresses used
1491   // from there will be lower than the stack base just computed
1492   thread_main_inner();
1493 
1494   // Note, thread is no longer valid at this point!
1495 }
1496 
1497 
1498 void JavaThread::thread_main_inner() {
1499   assert(JavaThread::current() == this, "sanity check");
1500   assert(this->threadObj() != NULL, "just checking");
1501 
1502   // Execute thread entry point unless this thread has a pending exception
1503   // or has been stopped before starting.
1504   // Note: Due to JVM_StopThread we can have pending exceptions already!
1505   if (!this->has_pending_exception() &&
1506       !java_lang_Thread::is_stillborn(this->threadObj())) {
1507     HandleMark hm(this);
1508     this->entry_point()(this, this);
1509   }
1510 
1511   DTRACE_THREAD_PROBE(stop, this);
1512 
1513   this->exit(false);
1514   delete this;
1515 }
1516 
1517 
1518 static void ensure_join(JavaThread* thread) {
1519   // We do not need to grap the Threads_lock, since we are operating on ourself.
1520   Handle threadObj(thread, thread->threadObj());
1521   assert(threadObj.not_null(), "java thread object must exist");
1522   ObjectLocker lock(threadObj, thread);
1523   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1524   thread->clear_pending_exception();
1525   // Thread is exiting. So set thread_status field in  java.lang.Thread class to TERMINATED.
1526   java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1527   // Clear the native thread instance - this makes isAlive return false and allows the join()
1528   // to complete once we've done the notify_all below
1529   java_lang_Thread::set_thread(threadObj(), NULL);
1530   lock.notify_all(thread);
1531   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1532   thread->clear_pending_exception();
1533 }
1534 
1535 
1536 // For any new cleanup additions, please check to see if they need to be applied to
1537 // cleanup_failed_attach_current_thread as well.
1538 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1539   assert(this == JavaThread::current(),  "thread consistency check");
1540   if (!InitializeJavaLangSystem) return;
1541 
1542   HandleMark hm(this);
1543   Handle uncaught_exception(this, this->pending_exception());
1544   this->clear_pending_exception();
1545   Handle threadObj(this, this->threadObj());
1546   assert(threadObj.not_null(), "Java thread object should be created");
1547 
1548   if (get_thread_profiler() != NULL) {
1549     get_thread_profiler()->disengage();
1550     ResourceMark rm;
1551     get_thread_profiler()->print(get_thread_name());
1552   }
1553 
1554 
1555   // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1556   {
1557     EXCEPTION_MARK;
1558 
1559     CLEAR_PENDING_EXCEPTION;
1560   }
1561   // FIXIT: The is_null check is only so it works better on JDK1.2 VM's. This
1562   // has to be fixed by a runtime query method
1563   if (!destroy_vm || JDK_Version::is_jdk12x_version()) {
1564     // JSR-166: change call from from ThreadGroup.uncaughtException to
1565     // java.lang.Thread.dispatchUncaughtException
1566     if (uncaught_exception.not_null()) {
1567       Handle group(this, java_lang_Thread::threadGroup(threadObj()));
1568       Events::log("uncaught exception INTPTR_FORMAT " " INTPTR_FORMAT " " INTPTR_FORMAT",
1569         (address)uncaught_exception(), (address)threadObj(), (address)group());
1570       {
1571         EXCEPTION_MARK;
1572         // Check if the method Thread.dispatchUncaughtException() exists. If so
1573         // call it.  Otherwise we have an older library without the JSR-166 changes,
1574         // so call ThreadGroup.uncaughtException()
1575         KlassHandle recvrKlass(THREAD, threadObj->klass());
1576         CallInfo callinfo;
1577         KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1578         LinkResolver::resolve_virtual_call(callinfo, threadObj, recvrKlass, thread_klass,
1579                                            vmSymbols::dispatchUncaughtException_name(),
1580                                            vmSymbols::throwable_void_signature(),
1581                                            KlassHandle(), false, false, THREAD);
1582         CLEAR_PENDING_EXCEPTION;
1583         methodHandle method = callinfo.selected_method();
1584         if (method.not_null()) {
1585           JavaValue result(T_VOID);
1586           JavaCalls::call_virtual(&result,
1587                                   threadObj, thread_klass,
1588                                   vmSymbols::dispatchUncaughtException_name(),
1589                                   vmSymbols::throwable_void_signature(),
1590                                   uncaught_exception,
1591                                   THREAD);
1592         } else {
1593           KlassHandle thread_group(THREAD, SystemDictionary::ThreadGroup_klass());
1594           JavaValue result(T_VOID);
1595           JavaCalls::call_virtual(&result,
1596                                   group, thread_group,
1597                                   vmSymbols::uncaughtException_name(),
1598                                   vmSymbols::thread_throwable_void_signature(),
1599                                   threadObj,           // Arg 1
1600                                   uncaught_exception,  // Arg 2
1601                                   THREAD);
1602         }
1603         if (HAS_PENDING_EXCEPTION) {
1604           ResourceMark rm(this);
1605           jio_fprintf(defaultStream::error_stream(),
1606                 "\nException: %s thrown from the UncaughtExceptionHandler"
1607                 " in thread \"%s\"\n",
1608                 Klass::cast(pending_exception()->klass())->external_name(),
1609                 get_thread_name());
1610           CLEAR_PENDING_EXCEPTION;
1611         }
1612       }
1613     }
1614 
1615     // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1616     // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1617     // is deprecated anyhow.
1618     { int count = 3;
1619       while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1620         EXCEPTION_MARK;
1621         JavaValue result(T_VOID);
1622         KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1623         JavaCalls::call_virtual(&result,
1624                               threadObj, thread_klass,
1625                               vmSymbols::exit_method_name(),
1626                               vmSymbols::void_method_signature(),
1627                               THREAD);
1628         CLEAR_PENDING_EXCEPTION;
1629       }
1630     }
1631 
1632     // notify JVMTI
1633     if (JvmtiExport::should_post_thread_life()) {
1634       JvmtiExport::post_thread_end(this);
1635     }
1636 
1637     // We have notified the agents that we are exiting, before we go on,
1638     // we must check for a pending external suspend request and honor it
1639     // in order to not surprise the thread that made the suspend request.
1640     while (true) {
1641       {
1642         MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1643         if (!is_external_suspend()) {
1644           set_terminated(_thread_exiting);
1645           ThreadService::current_thread_exiting(this);
1646           break;
1647         }
1648         // Implied else:
1649         // Things get a little tricky here. We have a pending external
1650         // suspend request, but we are holding the SR_lock so we
1651         // can't just self-suspend. So we temporarily drop the lock
1652         // and then self-suspend.
1653       }
1654 
1655       ThreadBlockInVM tbivm(this);
1656       java_suspend_self();
1657 
1658       // We're done with this suspend request, but we have to loop around
1659       // and check again. Eventually we will get SR_lock without a pending
1660       // external suspend request and will be able to mark ourselves as
1661       // exiting.
1662     }
1663     // no more external suspends are allowed at this point
1664   } else {
1665     // before_exit() has already posted JVMTI THREAD_END events
1666   }
1667 
1668   // Notify waiters on thread object. This has to be done after exit() is called
1669   // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1670   // group should have the destroyed bit set before waiters are notified).
1671   ensure_join(this);
1672   assert(!this->has_pending_exception(), "ensure_join should have cleared");
1673 
1674   // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1675   // held by this thread must be released.  A detach operation must only
1676   // get here if there are no Java frames on the stack.  Therefore, any
1677   // owned monitors at this point MUST be JNI-acquired monitors which are
1678   // pre-inflated and in the monitor cache.
1679   //
1680   // ensure_join() ignores IllegalThreadStateExceptions, and so does this.
1681   if (exit_type == jni_detach && JNIDetachReleasesMonitors) {
1682     assert(!this->has_last_Java_frame(), "detaching with Java frames?");
1683     ObjectSynchronizer::release_monitors_owned_by_thread(this);
1684     assert(!this->has_pending_exception(), "release_monitors should have cleared");
1685   }
1686 
1687   // These things needs to be done while we are still a Java Thread. Make sure that thread
1688   // is in a consistent state, in case GC happens
1689   assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1690 
1691   if (active_handles() != NULL) {
1692     JNIHandleBlock* block = active_handles();
1693     set_active_handles(NULL);
1694     JNIHandleBlock::release_block(block);
1695   }
1696 
1697   if (free_handle_block() != NULL) {
1698     JNIHandleBlock* block = free_handle_block();
1699     set_free_handle_block(NULL);
1700     JNIHandleBlock::release_block(block);
1701   }
1702 
1703   // These have to be removed while this is still a valid thread.
1704   remove_stack_guard_pages();
1705 
1706   if (UseTLAB) {
1707     tlab().make_parsable(true);  // retire TLAB
1708   }
1709 
1710   if (JvmtiEnv::environments_might_exist()) {
1711     JvmtiExport::cleanup_thread(this);
1712   }
1713 
1714 #ifndef SERIALGC
1715   // We must flush G1-related buffers before removing a thread from
1716   // the list of active threads.
1717   if (UseG1GC) {
1718     flush_barrier_queues();
1719   }
1720 #endif
1721 
1722   // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1723   Threads::remove(this);
1724 }
1725 
1726 #ifndef SERIALGC
1727 // Flush G1-related queues.
1728 void JavaThread::flush_barrier_queues() {
1729   satb_mark_queue().flush();
1730   dirty_card_queue().flush();
1731 }
1732 
1733 void JavaThread::initialize_queues() {
1734   assert(!SafepointSynchronize::is_at_safepoint(),
1735          "we should not be at a safepoint");
1736 
1737   ObjPtrQueue& satb_queue = satb_mark_queue();
1738   SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1739   // The SATB queue should have been constructed with its active
1740   // field set to false.
1741   assert(!satb_queue.is_active(), "SATB queue should not be active");
1742   assert(satb_queue.is_empty(), "SATB queue should be empty");
1743   // If we are creating the thread during a marking cycle, we should
1744   // set the active field of the SATB queue to true.
1745   if (satb_queue_set.is_active()) {
1746     satb_queue.set_active(true);
1747   }
1748 
1749   DirtyCardQueue& dirty_queue = dirty_card_queue();
1750   // The dirty card queue should have been constructed with its
1751   // active field set to true.
1752   assert(dirty_queue.is_active(), "dirty card queue should be active");
1753 }
1754 #endif // !SERIALGC
1755 
1756 void JavaThread::cleanup_failed_attach_current_thread() {
1757   if (get_thread_profiler() != NULL) {
1758     get_thread_profiler()->disengage();
1759     ResourceMark rm;
1760     get_thread_profiler()->print(get_thread_name());
1761   }
1762 
1763   if (active_handles() != NULL) {
1764     JNIHandleBlock* block = active_handles();
1765     set_active_handles(NULL);
1766     JNIHandleBlock::release_block(block);
1767   }
1768 
1769   if (free_handle_block() != NULL) {
1770     JNIHandleBlock* block = free_handle_block();
1771     set_free_handle_block(NULL);
1772     JNIHandleBlock::release_block(block);
1773   }
1774 
1775   // These have to be removed while this is still a valid thread.
1776   remove_stack_guard_pages();
1777 
1778   if (UseTLAB) {
1779     tlab().make_parsable(true);  // retire TLAB, if any
1780   }
1781 
1782 #ifndef SERIALGC
1783   if (UseG1GC) {
1784     flush_barrier_queues();
1785   }
1786 #endif
1787 
1788   Threads::remove(this);
1789   delete this;
1790 }
1791 
1792 
1793 
1794 
1795 JavaThread* JavaThread::active() {
1796   Thread* thread = ThreadLocalStorage::thread();
1797   assert(thread != NULL, "just checking");
1798   if (thread->is_Java_thread()) {
1799     return (JavaThread*) thread;
1800   } else {
1801     assert(thread->is_VM_thread(), "this must be a vm thread");
1802     VM_Operation* op = ((VMThread*) thread)->vm_operation();
1803     JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
1804     assert(ret->is_Java_thread(), "must be a Java thread");
1805     return ret;
1806   }
1807 }
1808 
1809 bool JavaThread::is_lock_owned(address adr) const {
1810   if (Thread::is_lock_owned(adr)) return true;
1811 
1812   for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
1813     if (chunk->contains(adr)) return true;
1814   }
1815 
1816   return false;
1817 }
1818 
1819 
1820 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
1821   chunk->set_next(monitor_chunks());
1822   set_monitor_chunks(chunk);
1823 }
1824 
1825 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
1826   guarantee(monitor_chunks() != NULL, "must be non empty");
1827   if (monitor_chunks() == chunk) {
1828     set_monitor_chunks(chunk->next());
1829   } else {
1830     MonitorChunk* prev = monitor_chunks();
1831     while (prev->next() != chunk) prev = prev->next();
1832     prev->set_next(chunk->next());
1833   }
1834 }
1835 
1836 // JVM support.
1837 
1838 // Note: this function shouldn't block if it's called in
1839 // _thread_in_native_trans state (such as from
1840 // check_special_condition_for_native_trans()).
1841 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
1842 
1843   if (has_last_Java_frame() && has_async_condition()) {
1844     // If we are at a polling page safepoint (not a poll return)
1845     // then we must defer async exception because live registers
1846     // will be clobbered by the exception path. Poll return is
1847     // ok because the call we a returning from already collides
1848     // with exception handling registers and so there is no issue.
1849     // (The exception handling path kills call result registers but
1850     //  this is ok since the exception kills the result anyway).
1851 
1852     if (is_at_poll_safepoint()) {
1853       // if the code we are returning to has deoptimized we must defer
1854       // the exception otherwise live registers get clobbered on the
1855       // exception path before deoptimization is able to retrieve them.
1856       //
1857       RegisterMap map(this, false);
1858       frame caller_fr = last_frame().sender(&map);
1859       assert(caller_fr.is_compiled_frame(), "what?");
1860       if (caller_fr.is_deoptimized_frame()) {
1861         if (TraceExceptions) {
1862           ResourceMark rm;
1863           tty->print_cr("deferred async exception at compiled safepoint");
1864         }
1865         return;
1866       }
1867     }
1868   }
1869 
1870   JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
1871   if (condition == _no_async_condition) {
1872     // Conditions have changed since has_special_runtime_exit_condition()
1873     // was called:
1874     // - if we were here only because of an external suspend request,
1875     //   then that was taken care of above (or cancelled) so we are done
1876     // - if we were here because of another async request, then it has
1877     //   been cleared between the has_special_runtime_exit_condition()
1878     //   and now so again we are done
1879     return;
1880   }
1881 
1882   // Check for pending async. exception
1883   if (_pending_async_exception != NULL) {
1884     // Only overwrite an already pending exception, if it is not a threadDeath.
1885     if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
1886 
1887       // We cannot call Exceptions::_throw(...) here because we cannot block
1888       set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
1889 
1890       if (TraceExceptions) {
1891         ResourceMark rm;
1892         tty->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", this);
1893         if (has_last_Java_frame() ) {
1894           frame f = last_frame();
1895           tty->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", f.pc(), f.sp());
1896         }
1897         tty->print_cr(" of type: %s", instanceKlass::cast(_pending_async_exception->klass())->external_name());
1898       }
1899       _pending_async_exception = NULL;
1900       clear_has_async_exception();
1901     }
1902   }
1903 
1904   if (check_unsafe_error &&
1905       condition == _async_unsafe_access_error && !has_pending_exception()) {
1906     condition = _no_async_condition;  // done
1907     switch (thread_state()) {
1908     case _thread_in_vm:
1909       {
1910         JavaThread* THREAD = this;
1911         THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
1912       }
1913     case _thread_in_native:
1914       {
1915         ThreadInVMfromNative tiv(this);
1916         JavaThread* THREAD = this;
1917         THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
1918       }
1919     case _thread_in_Java:
1920       {
1921         ThreadInVMfromJava tiv(this);
1922         JavaThread* THREAD = this;
1923         THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
1924       }
1925     default:
1926       ShouldNotReachHere();
1927     }
1928   }
1929 
1930   assert(condition == _no_async_condition || has_pending_exception() ||
1931          (!check_unsafe_error && condition == _async_unsafe_access_error),
1932          "must have handled the async condition, if no exception");
1933 }
1934 
1935 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
1936   //
1937   // Check for pending external suspend. Internal suspend requests do
1938   // not use handle_special_runtime_exit_condition().
1939   // If JNIEnv proxies are allowed, don't self-suspend if the target
1940   // thread is not the current thread. In older versions of jdbx, jdbx
1941   // threads could call into the VM with another thread's JNIEnv so we
1942   // can be here operating on behalf of a suspended thread (4432884).
1943   bool do_self_suspend = is_external_suspend_with_lock();
1944   if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
1945     //
1946     // Because thread is external suspended the safepoint code will count
1947     // thread as at a safepoint. This can be odd because we can be here
1948     // as _thread_in_Java which would normally transition to _thread_blocked
1949     // at a safepoint. We would like to mark the thread as _thread_blocked
1950     // before calling java_suspend_self like all other callers of it but
1951     // we must then observe proper safepoint protocol. (We can't leave
1952     // _thread_blocked with a safepoint in progress). However we can be
1953     // here as _thread_in_native_trans so we can't use a normal transition
1954     // constructor/destructor pair because they assert on that type of
1955     // transition. We could do something like:
1956     //
1957     // JavaThreadState state = thread_state();
1958     // set_thread_state(_thread_in_vm);
1959     // {
1960     //   ThreadBlockInVM tbivm(this);
1961     //   java_suspend_self()
1962     // }
1963     // set_thread_state(_thread_in_vm_trans);
1964     // if (safepoint) block;
1965     // set_thread_state(state);
1966     //
1967     // but that is pretty messy. Instead we just go with the way the
1968     // code has worked before and note that this is the only path to
1969     // java_suspend_self that doesn't put the thread in _thread_blocked
1970     // mode.
1971 
1972     frame_anchor()->make_walkable(this);
1973     java_suspend_self();
1974 
1975     // We might be here for reasons in addition to the self-suspend request
1976     // so check for other async requests.
1977   }
1978 
1979   if (check_asyncs) {
1980     check_and_handle_async_exceptions();
1981   }
1982 }
1983 
1984 void JavaThread::send_thread_stop(oop java_throwable)  {
1985   assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
1986   assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
1987   assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
1988 
1989   // Do not throw asynchronous exceptions against the compiler thread
1990   // (the compiler thread should not be a Java thread -- fix in 1.4.2)
1991   if (is_Compiler_thread()) return;
1992 
1993   {
1994     // Actually throw the Throwable against the target Thread - however
1995     // only if there is no thread death exception installed already.
1996     if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
1997       // If the topmost frame is a runtime stub, then we are calling into
1998       // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
1999       // must deoptimize the caller before continuing, as the compiled  exception handler table
2000       // may not be valid
2001       if (has_last_Java_frame()) {
2002         frame f = last_frame();
2003         if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2004           // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2005           RegisterMap reg_map(this, UseBiasedLocking);
2006           frame compiled_frame = f.sender(&reg_map);
2007           if (compiled_frame.can_be_deoptimized()) {
2008             Deoptimization::deoptimize(this, compiled_frame, &reg_map);
2009           }
2010         }
2011       }
2012 
2013       // Set async. pending exception in thread.
2014       set_pending_async_exception(java_throwable);
2015 
2016       if (TraceExceptions) {
2017        ResourceMark rm;
2018        tty->print_cr("Pending Async. exception installed of type: %s", instanceKlass::cast(_pending_async_exception->klass())->external_name());
2019       }
2020       // for AbortVMOnException flag
2021       NOT_PRODUCT(Exceptions::debug_check_abort(instanceKlass::cast(_pending_async_exception->klass())->external_name()));
2022     }
2023   }
2024 
2025 
2026   // Interrupt thread so it will wake up from a potential wait()
2027   Thread::interrupt(this);
2028 }
2029 
2030 // External suspension mechanism.
2031 //
2032 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2033 // to any VM_locks and it is at a transition
2034 // Self-suspension will happen on the transition out of the vm.
2035 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2036 //
2037 // Guarantees on return:
2038 //   + Target thread will not execute any new bytecode (that's why we need to
2039 //     force a safepoint)
2040 //   + Target thread will not enter any new monitors
2041 //
2042 void JavaThread::java_suspend() {
2043   { MutexLocker mu(Threads_lock);
2044     if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2045        return;
2046     }
2047   }
2048 
2049   { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2050     if (!is_external_suspend()) {
2051       // a racing resume has cancelled us; bail out now
2052       return;
2053     }
2054 
2055     // suspend is done
2056     uint32_t debug_bits = 0;
2057     // Warning: is_ext_suspend_completed() may temporarily drop the
2058     // SR_lock to allow the thread to reach a stable thread state if
2059     // it is currently in a transient thread state.
2060     if (is_ext_suspend_completed(false /* !called_by_wait */,
2061                                  SuspendRetryDelay, &debug_bits) ) {
2062       return;
2063     }
2064   }
2065 
2066   VM_ForceSafepoint vm_suspend;
2067   VMThread::execute(&vm_suspend);
2068 }
2069 
2070 // Part II of external suspension.
2071 // A JavaThread self suspends when it detects a pending external suspend
2072 // request. This is usually on transitions. It is also done in places
2073 // where continuing to the next transition would surprise the caller,
2074 // e.g., monitor entry.
2075 //
2076 // Returns the number of times that the thread self-suspended.
2077 //
2078 // Note: DO NOT call java_suspend_self() when you just want to block current
2079 //       thread. java_suspend_self() is the second stage of cooperative
2080 //       suspension for external suspend requests and should only be used
2081 //       to complete an external suspend request.
2082 //
2083 int JavaThread::java_suspend_self() {
2084   int ret = 0;
2085 
2086   // we are in the process of exiting so don't suspend
2087   if (is_exiting()) {
2088      clear_external_suspend();
2089      return ret;
2090   }
2091 
2092   assert(_anchor.walkable() ||
2093     (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2094     "must have walkable stack");
2095 
2096   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2097 
2098   assert(!this->is_ext_suspended(),
2099     "a thread trying to self-suspend should not already be suspended");
2100 
2101   if (this->is_suspend_equivalent()) {
2102     // If we are self-suspending as a result of the lifting of a
2103     // suspend equivalent condition, then the suspend_equivalent
2104     // flag is not cleared until we set the ext_suspended flag so
2105     // that wait_for_ext_suspend_completion() returns consistent
2106     // results.
2107     this->clear_suspend_equivalent();
2108   }
2109 
2110   // A racing resume may have cancelled us before we grabbed SR_lock
2111   // above. Or another external suspend request could be waiting for us
2112   // by the time we return from SR_lock()->wait(). The thread
2113   // that requested the suspension may already be trying to walk our
2114   // stack and if we return now, we can change the stack out from under
2115   // it. This would be a "bad thing (TM)" and cause the stack walker
2116   // to crash. We stay self-suspended until there are no more pending
2117   // external suspend requests.
2118   while (is_external_suspend()) {
2119     ret++;
2120     this->set_ext_suspended();
2121 
2122     // _ext_suspended flag is cleared by java_resume()
2123     while (is_ext_suspended()) {
2124       this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2125     }
2126   }
2127 
2128   return ret;
2129 }
2130 
2131 #ifdef ASSERT
2132 // verify the JavaThread has not yet been published in the Threads::list, and
2133 // hence doesn't need protection from concurrent access at this stage
2134 void JavaThread::verify_not_published() {
2135   if (!Threads_lock->owned_by_self()) {
2136    MutexLockerEx ml(Threads_lock,  Mutex::_no_safepoint_check_flag);
2137    assert( !Threads::includes(this),
2138            "java thread shouldn't have been published yet!");
2139   }
2140   else {
2141    assert( !Threads::includes(this),
2142            "java thread shouldn't have been published yet!");
2143   }
2144 }
2145 #endif
2146 
2147 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2148 // progress or when _suspend_flags is non-zero.
2149 // Current thread needs to self-suspend if there is a suspend request and/or
2150 // block if a safepoint is in progress.
2151 // Async exception ISN'T checked.
2152 // Note only the ThreadInVMfromNative transition can call this function
2153 // directly and when thread state is _thread_in_native_trans
2154 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2155   assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2156 
2157   JavaThread *curJT = JavaThread::current();
2158   bool do_self_suspend = thread->is_external_suspend();
2159 
2160   assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2161 
2162   // If JNIEnv proxies are allowed, don't self-suspend if the target
2163   // thread is not the current thread. In older versions of jdbx, jdbx
2164   // threads could call into the VM with another thread's JNIEnv so we
2165   // can be here operating on behalf of a suspended thread (4432884).
2166   if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2167     JavaThreadState state = thread->thread_state();
2168 
2169     // We mark this thread_blocked state as a suspend-equivalent so
2170     // that a caller to is_ext_suspend_completed() won't be confused.
2171     // The suspend-equivalent state is cleared by java_suspend_self().
2172     thread->set_suspend_equivalent();
2173 
2174     // If the safepoint code sees the _thread_in_native_trans state, it will
2175     // wait until the thread changes to other thread state. There is no
2176     // guarantee on how soon we can obtain the SR_lock and complete the
2177     // self-suspend request. It would be a bad idea to let safepoint wait for
2178     // too long. Temporarily change the state to _thread_blocked to
2179     // let the VM thread know that this thread is ready for GC. The problem
2180     // of changing thread state is that safepoint could happen just after
2181     // java_suspend_self() returns after being resumed, and VM thread will
2182     // see the _thread_blocked state. We must check for safepoint
2183     // after restoring the state and make sure we won't leave while a safepoint
2184     // is in progress.
2185     thread->set_thread_state(_thread_blocked);
2186     thread->java_suspend_self();
2187     thread->set_thread_state(state);
2188     // Make sure new state is seen by VM thread
2189     if (os::is_MP()) {
2190       if (UseMembar) {
2191         // Force a fence between the write above and read below
2192         OrderAccess::fence();
2193       } else {
2194         // Must use this rather than serialization page in particular on Windows
2195         InterfaceSupport::serialize_memory(thread);
2196       }
2197     }
2198   }
2199 
2200   if (SafepointSynchronize::do_call_back()) {
2201     // If we are safepointing, then block the caller which may not be
2202     // the same as the target thread (see above).
2203     SafepointSynchronize::block(curJT);
2204   }
2205 
2206   if (thread->is_deopt_suspend()) {
2207     thread->clear_deopt_suspend();
2208     RegisterMap map(thread, false);
2209     frame f = thread->last_frame();
2210     while ( f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2211       f = f.sender(&map);
2212     }
2213     if (f.id() == thread->must_deopt_id()) {
2214       thread->clear_must_deopt_id();
2215       f.deoptimize(thread);
2216     } else {
2217       fatal("missed deoptimization!");
2218     }
2219   }
2220 }
2221 
2222 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2223 // progress or when _suspend_flags is non-zero.
2224 // Current thread needs to self-suspend if there is a suspend request and/or
2225 // block if a safepoint is in progress.
2226 // Also check for pending async exception (not including unsafe access error).
2227 // Note only the native==>VM/Java barriers can call this function and when
2228 // thread state is _thread_in_native_trans.
2229 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2230   check_safepoint_and_suspend_for_native_trans(thread);
2231 
2232   if (thread->has_async_exception()) {
2233     // We are in _thread_in_native_trans state, don't handle unsafe
2234     // access error since that may block.
2235     thread->check_and_handle_async_exceptions(false);
2236   }
2237 }
2238 
2239 // We need to guarantee the Threads_lock here, since resumes are not
2240 // allowed during safepoint synchronization
2241 // Can only resume from an external suspension
2242 void JavaThread::java_resume() {
2243   assert_locked_or_safepoint(Threads_lock);
2244 
2245   // Sanity check: thread is gone, has started exiting or the thread
2246   // was not externally suspended.
2247   if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2248     return;
2249   }
2250 
2251   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2252 
2253   clear_external_suspend();
2254 
2255   if (is_ext_suspended()) {
2256     clear_ext_suspended();
2257     SR_lock()->notify_all();
2258   }
2259 }
2260 
2261 void JavaThread::create_stack_guard_pages() {
2262   if (! os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) return;
2263   address low_addr = stack_base() - stack_size();
2264   size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
2265 
2266   int allocate = os::allocate_stack_guard_pages();
2267   // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2268 
2269   if (allocate && !os::create_stack_guard_pages((char *) low_addr, len)) {
2270     warning("Attempt to allocate stack guard pages failed.");
2271     return;
2272   }
2273 
2274   if (os::guard_memory((char *) low_addr, len)) {
2275     _stack_guard_state = stack_guard_enabled;
2276   } else {
2277     warning("Attempt to protect stack guard pages failed.");
2278     if (os::uncommit_memory((char *) low_addr, len)) {
2279       warning("Attempt to deallocate stack guard pages failed.");
2280     }
2281   }
2282 }
2283 
2284 void JavaThread::remove_stack_guard_pages() {
2285   if (_stack_guard_state == stack_guard_unused) return;
2286   address low_addr = stack_base() - stack_size();
2287   size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
2288 
2289   if (os::allocate_stack_guard_pages()) {
2290     if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2291       _stack_guard_state = stack_guard_unused;
2292     } else {
2293       warning("Attempt to deallocate stack guard pages failed.");
2294     }
2295   } else {
2296     if (_stack_guard_state == stack_guard_unused) return;
2297     if (os::unguard_memory((char *) low_addr, len)) {
2298       _stack_guard_state = stack_guard_unused;
2299     } else {
2300         warning("Attempt to unprotect stack guard pages failed.");
2301     }
2302   }
2303 }
2304 
2305 void JavaThread::enable_stack_yellow_zone() {
2306   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2307   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2308 
2309   // The base notation is from the stacks point of view, growing downward.
2310   // We need to adjust it to work correctly with guard_memory()
2311   address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2312 
2313   guarantee(base < stack_base(),"Error calculating stack yellow zone");
2314   guarantee(base < os::current_stack_pointer(),"Error calculating stack yellow zone");
2315 
2316   if (os::guard_memory((char *) base, stack_yellow_zone_size())) {
2317     _stack_guard_state = stack_guard_enabled;
2318   } else {
2319     warning("Attempt to guard stack yellow zone failed.");
2320   }
2321   enable_register_stack_guard();
2322 }
2323 
2324 void JavaThread::disable_stack_yellow_zone() {
2325   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2326   assert(_stack_guard_state != stack_guard_yellow_disabled, "already disabled");
2327 
2328   // Simply return if called for a thread that does not use guard pages.
2329   if (_stack_guard_state == stack_guard_unused) return;
2330 
2331   // The base notation is from the stacks point of view, growing downward.
2332   // We need to adjust it to work correctly with guard_memory()
2333   address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2334 
2335   if (os::unguard_memory((char *)base, stack_yellow_zone_size())) {
2336     _stack_guard_state = stack_guard_yellow_disabled;
2337   } else {
2338     warning("Attempt to unguard stack yellow zone failed.");
2339   }
2340   disable_register_stack_guard();
2341 }
2342 
2343 void JavaThread::enable_stack_red_zone() {
2344   // The base notation is from the stacks point of view, growing downward.
2345   // We need to adjust it to work correctly with guard_memory()
2346   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2347   address base = stack_red_zone_base() - stack_red_zone_size();
2348 
2349   guarantee(base < stack_base(),"Error calculating stack red zone");
2350   guarantee(base < os::current_stack_pointer(),"Error calculating stack red zone");
2351 
2352   if(!os::guard_memory((char *) base, stack_red_zone_size())) {
2353     warning("Attempt to guard stack red zone failed.");
2354   }
2355 }
2356 
2357 void JavaThread::disable_stack_red_zone() {
2358   // The base notation is from the stacks point of view, growing downward.
2359   // We need to adjust it to work correctly with guard_memory()
2360   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2361   address base = stack_red_zone_base() - stack_red_zone_size();
2362   if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2363     warning("Attempt to unguard stack red zone failed.");
2364   }
2365 }
2366 
2367 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2368   // ignore is there is no stack
2369   if (!has_last_Java_frame()) return;
2370   // traverse the stack frames. Starts from top frame.
2371   for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2372     frame* fr = fst.current();
2373     f(fr, fst.register_map());
2374   }
2375 }
2376 
2377 
2378 #ifndef PRODUCT
2379 // Deoptimization
2380 // Function for testing deoptimization
2381 void JavaThread::deoptimize() {
2382   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2383   StackFrameStream fst(this, UseBiasedLocking);
2384   bool deopt = false;           // Dump stack only if a deopt actually happens.
2385   bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2386   // Iterate over all frames in the thread and deoptimize
2387   for(; !fst.is_done(); fst.next()) {
2388     if(fst.current()->can_be_deoptimized()) {
2389 
2390       if (only_at) {
2391         // Deoptimize only at particular bcis.  DeoptimizeOnlyAt
2392         // consists of comma or carriage return separated numbers so
2393         // search for the current bci in that string.
2394         address pc = fst.current()->pc();
2395         nmethod* nm =  (nmethod*) fst.current()->cb();
2396         ScopeDesc* sd = nm->scope_desc_at( pc);
2397         char buffer[8];
2398         jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2399         size_t len = strlen(buffer);
2400         const char * found = strstr(DeoptimizeOnlyAt, buffer);
2401         while (found != NULL) {
2402           if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2403               (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2404             // Check that the bci found is bracketed by terminators.
2405             break;
2406           }
2407           found = strstr(found + 1, buffer);
2408         }
2409         if (!found) {
2410           continue;
2411         }
2412       }
2413 
2414       if (DebugDeoptimization && !deopt) {
2415         deopt = true; // One-time only print before deopt
2416         tty->print_cr("[BEFORE Deoptimization]");
2417         trace_frames();
2418         trace_stack();
2419       }
2420       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2421     }
2422   }
2423 
2424   if (DebugDeoptimization && deopt) {
2425     tty->print_cr("[AFTER Deoptimization]");
2426     trace_frames();
2427   }
2428 }
2429 
2430 
2431 // Make zombies
2432 void JavaThread::make_zombies() {
2433   for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2434     if (fst.current()->can_be_deoptimized()) {
2435       // it is a Java nmethod
2436       nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2437       nm->make_not_entrant();
2438     }
2439   }
2440 }
2441 #endif // PRODUCT
2442 
2443 
2444 void JavaThread::deoptimized_wrt_marked_nmethods() {
2445   if (!has_last_Java_frame()) return;
2446   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2447   StackFrameStream fst(this, UseBiasedLocking);
2448   for(; !fst.is_done(); fst.next()) {
2449     if (fst.current()->should_be_deoptimized()) {
2450       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2451     }
2452   }
2453 }
2454 
2455 
2456 // GC support
2457 static void frame_gc_epilogue(frame* f, const RegisterMap* map) { f->gc_epilogue(); }
2458 
2459 void JavaThread::gc_epilogue() {
2460   frames_do(frame_gc_epilogue);
2461 }
2462 
2463 
2464 static void frame_gc_prologue(frame* f, const RegisterMap* map) { f->gc_prologue(); }
2465 
2466 void JavaThread::gc_prologue() {
2467   frames_do(frame_gc_prologue);
2468 }
2469 
2470 // If the caller is a NamedThread, then remember, in the current scope,
2471 // the given JavaThread in its _processed_thread field.
2472 class RememberProcessedThread: public StackObj {
2473   NamedThread* _cur_thr;
2474 public:
2475   RememberProcessedThread(JavaThread* jthr) {
2476     Thread* thread = Thread::current();
2477     if (thread->is_Named_thread()) {
2478       _cur_thr = (NamedThread *)thread;
2479       _cur_thr->set_processed_thread(jthr);
2480     } else {
2481       _cur_thr = NULL;
2482     }
2483   }
2484 
2485   ~RememberProcessedThread() {
2486     if (_cur_thr) {
2487       _cur_thr->set_processed_thread(NULL);
2488     }
2489   }
2490 };
2491 
2492 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2493   // Verify that the deferred card marks have been flushed.
2494   assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2495 
2496   // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2497   // since there may be more than one thread using each ThreadProfiler.
2498 
2499   // Traverse the GCHandles
2500   Thread::oops_do(f, cf);
2501 
2502   assert( (!has_last_Java_frame() && java_call_counter() == 0) ||
2503           (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2504 
2505   if (has_last_Java_frame()) {
2506     // Record JavaThread to GC thread
2507     RememberProcessedThread rpt(this);
2508 
2509     // Traverse the privileged stack
2510     if (_privileged_stack_top != NULL) {
2511       _privileged_stack_top->oops_do(f);
2512     }
2513 
2514     // traverse the registered growable array
2515     if (_array_for_gc != NULL) {
2516       for (int index = 0; index < _array_for_gc->length(); index++) {
2517         f->do_oop(_array_for_gc->adr_at(index));
2518       }
2519     }
2520 
2521     // Traverse the monitor chunks
2522     for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2523       chunk->oops_do(f);
2524     }
2525 
2526     // Traverse the execution stack
2527     for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2528       fst.current()->oops_do(f, cf, fst.register_map());
2529     }
2530   }
2531 
2532   // callee_target is never live across a gc point so NULL it here should
2533   // it still contain a methdOop.
2534 
2535   set_callee_target(NULL);
2536 
2537   assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2538   // If we have deferred set_locals there might be oops waiting to be
2539   // written
2540   GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2541   if (list != NULL) {
2542     for (int i = 0; i < list->length(); i++) {
2543       list->at(i)->oops_do(f);
2544     }
2545   }
2546 
2547   // Traverse instance variables at the end since the GC may be moving things
2548   // around using this function
2549   f->do_oop((oop*) &_threadObj);
2550   f->do_oop((oop*) &_vm_result);
2551   f->do_oop((oop*) &_vm_result_2);
2552   f->do_oop((oop*) &_exception_oop);
2553   f->do_oop((oop*) &_pending_async_exception);
2554 
2555   if (jvmti_thread_state() != NULL) {
2556     jvmti_thread_state()->oops_do(f);
2557   }
2558 }
2559 
2560 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2561   Thread::nmethods_do(cf);  // (super method is a no-op)
2562 
2563   assert( (!has_last_Java_frame() && java_call_counter() == 0) ||
2564           (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2565 
2566   if (has_last_Java_frame()) {
2567     // Traverse the execution stack
2568     for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2569       fst.current()->nmethods_do(cf);
2570     }
2571   }
2572 }
2573 
2574 // Printing
2575 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2576   switch (_thread_state) {
2577   case _thread_uninitialized:     return "_thread_uninitialized";
2578   case _thread_new:               return "_thread_new";
2579   case _thread_new_trans:         return "_thread_new_trans";
2580   case _thread_in_native:         return "_thread_in_native";
2581   case _thread_in_native_trans:   return "_thread_in_native_trans";
2582   case _thread_in_vm:             return "_thread_in_vm";
2583   case _thread_in_vm_trans:       return "_thread_in_vm_trans";
2584   case _thread_in_Java:           return "_thread_in_Java";
2585   case _thread_in_Java_trans:     return "_thread_in_Java_trans";
2586   case _thread_blocked:           return "_thread_blocked";
2587   case _thread_blocked_trans:     return "_thread_blocked_trans";
2588   default:                        return "unknown thread state";
2589   }
2590 }
2591 
2592 #ifndef PRODUCT
2593 void JavaThread::print_thread_state_on(outputStream *st) const {
2594   st->print_cr("   JavaThread state: %s", _get_thread_state_name(_thread_state));
2595 };
2596 void JavaThread::print_thread_state() const {
2597   print_thread_state_on(tty);
2598 };
2599 #endif // PRODUCT
2600 
2601 // Called by Threads::print() for VM_PrintThreads operation
2602 void JavaThread::print_on(outputStream *st) const {
2603   st->print("\"%s\" ", get_thread_name());
2604   oop thread_oop = threadObj();
2605   if (thread_oop != NULL && java_lang_Thread::is_daemon(thread_oop))  st->print("daemon ");
2606   Thread::print_on(st);
2607   // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2608   st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2609   if (thread_oop != NULL && JDK_Version::is_gte_jdk15x_version()) {
2610     st->print_cr("   java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2611   }
2612 #ifndef PRODUCT
2613   print_thread_state_on(st);
2614   _safepoint_state->print_on(st);
2615 #endif // PRODUCT
2616 }
2617 
2618 // Called by fatal error handler. The difference between this and
2619 // JavaThread::print() is that we can't grab lock or allocate memory.
2620 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2621   st->print("JavaThread \"%s\"",  get_thread_name_string(buf, buflen));
2622   oop thread_obj = threadObj();
2623   if (thread_obj != NULL) {
2624      if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2625   }
2626   st->print(" [");
2627   st->print("%s", _get_thread_state_name(_thread_state));
2628   if (osthread()) {
2629     st->print(", id=%d", osthread()->thread_id());
2630   }
2631   st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2632             _stack_base - _stack_size, _stack_base);
2633   st->print("]");
2634   return;
2635 }
2636 
2637 // Verification
2638 
2639 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2640 
2641 void JavaThread::verify() {
2642   // Verify oops in the thread.
2643   oops_do(&VerifyOopClosure::verify_oop, NULL);
2644 
2645   // Verify the stack frames.
2646   frames_do(frame_verify);
2647 }
2648 
2649 // CR 6300358 (sub-CR 2137150)
2650 // Most callers of this method assume that it can't return NULL but a
2651 // thread may not have a name whilst it is in the process of attaching to
2652 // the VM - see CR 6412693, and there are places where a JavaThread can be
2653 // seen prior to having it's threadObj set (eg JNI attaching threads and
2654 // if vm exit occurs during initialization). These cases can all be accounted
2655 // for such that this method never returns NULL.
2656 const char* JavaThread::get_thread_name() const {
2657 #ifdef ASSERT
2658   // early safepoints can hit while current thread does not yet have TLS
2659   if (!SafepointSynchronize::is_at_safepoint()) {
2660     Thread *cur = Thread::current();
2661     if (!(cur->is_Java_thread() && cur == this)) {
2662       // Current JavaThreads are allowed to get their own name without
2663       // the Threads_lock.
2664       assert_locked_or_safepoint(Threads_lock);
2665     }
2666   }
2667 #endif // ASSERT
2668     return get_thread_name_string();
2669 }
2670 
2671 // Returns a non-NULL representation of this thread's name, or a suitable
2672 // descriptive string if there is no set name
2673 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
2674   const char* name_str;
2675   oop thread_obj = threadObj();
2676   if (thread_obj != NULL) {
2677     typeArrayOop name = java_lang_Thread::name(thread_obj);
2678     if (name != NULL) {
2679       if (buf == NULL) {
2680         name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2681       }
2682       else {
2683         name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length(), buf, buflen);
2684       }
2685     }
2686     else if (is_attaching()) { // workaround for 6412693 - see 6404306
2687       name_str = "<no-name - thread is attaching>";
2688     }
2689     else {
2690       name_str = Thread::name();
2691     }
2692   }
2693   else {
2694     name_str = Thread::name();
2695   }
2696   assert(name_str != NULL, "unexpected NULL thread name");
2697   return name_str;
2698 }
2699 
2700 
2701 const char* JavaThread::get_threadgroup_name() const {
2702   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2703   oop thread_obj = threadObj();
2704   if (thread_obj != NULL) {
2705     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2706     if (thread_group != NULL) {
2707       typeArrayOop name = java_lang_ThreadGroup::name(thread_group);
2708       // ThreadGroup.name can be null
2709       if (name != NULL) {
2710         const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2711         return str;
2712       }
2713     }
2714   }
2715   return NULL;
2716 }
2717 
2718 const char* JavaThread::get_parent_name() const {
2719   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2720   oop thread_obj = threadObj();
2721   if (thread_obj != NULL) {
2722     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2723     if (thread_group != NULL) {
2724       oop parent = java_lang_ThreadGroup::parent(thread_group);
2725       if (parent != NULL) {
2726         typeArrayOop name = java_lang_ThreadGroup::name(parent);
2727         // ThreadGroup.name can be null
2728         if (name != NULL) {
2729           const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2730           return str;
2731         }
2732       }
2733     }
2734   }
2735   return NULL;
2736 }
2737 
2738 ThreadPriority JavaThread::java_priority() const {
2739   oop thr_oop = threadObj();
2740   if (thr_oop == NULL) return NormPriority; // Bootstrapping
2741   ThreadPriority priority = java_lang_Thread::priority(thr_oop);
2742   assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
2743   return priority;
2744 }
2745 
2746 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
2747 
2748   assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
2749   // Link Java Thread object <-> C++ Thread
2750 
2751   // Get the C++ thread object (an oop) from the JNI handle (a jthread)
2752   // and put it into a new Handle.  The Handle "thread_oop" can then
2753   // be used to pass the C++ thread object to other methods.
2754 
2755   // Set the Java level thread object (jthread) field of the
2756   // new thread (a JavaThread *) to C++ thread object using the
2757   // "thread_oop" handle.
2758 
2759   // Set the thread field (a JavaThread *) of the
2760   // oop representing the java_lang_Thread to the new thread (a JavaThread *).
2761 
2762   Handle thread_oop(Thread::current(),
2763                     JNIHandles::resolve_non_null(jni_thread));
2764   assert(instanceKlass::cast(thread_oop->klass())->is_linked(),
2765     "must be initialized");
2766   set_threadObj(thread_oop());
2767   java_lang_Thread::set_thread(thread_oop(), this);
2768 
2769   if (prio == NoPriority) {
2770     prio = java_lang_Thread::priority(thread_oop());
2771     assert(prio != NoPriority, "A valid priority should be present");
2772   }
2773 
2774   // Push the Java priority down to the native thread; needs Threads_lock
2775   Thread::set_priority(this, prio);
2776 
2777   // Add the new thread to the Threads list and set it in motion.
2778   // We must have threads lock in order to call Threads::add.
2779   // It is crucial that we do not block before the thread is
2780   // added to the Threads list for if a GC happens, then the java_thread oop
2781   // will not be visited by GC.
2782   Threads::add(this);
2783 }
2784 
2785 oop JavaThread::current_park_blocker() {
2786   // Support for JSR-166 locks
2787   oop thread_oop = threadObj();
2788   if (thread_oop != NULL &&
2789       JDK_Version::current().supports_thread_park_blocker()) {
2790     return java_lang_Thread::park_blocker(thread_oop);
2791   }
2792   return NULL;
2793 }
2794 
2795 
2796 void JavaThread::print_stack_on(outputStream* st) {
2797   if (!has_last_Java_frame()) return;
2798   ResourceMark rm;
2799   HandleMark   hm;
2800 
2801   RegisterMap reg_map(this);
2802   vframe* start_vf = last_java_vframe(&reg_map);
2803   int count = 0;
2804   for (vframe* f = start_vf; f; f = f->sender() ) {
2805     if (f->is_java_frame()) {
2806       javaVFrame* jvf = javaVFrame::cast(f);
2807       java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
2808 
2809       // Print out lock information
2810       if (JavaMonitorsInStackTrace) {
2811         jvf->print_lock_info_on(st, count);
2812       }
2813     } else {
2814       // Ignore non-Java frames
2815     }
2816 
2817     // Bail-out case for too deep stacks
2818     count++;
2819     if (MaxJavaStackTraceDepth == count) return;
2820   }
2821 }
2822 
2823 
2824 // JVMTI PopFrame support
2825 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
2826   assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
2827   if (in_bytes(size_in_bytes) != 0) {
2828     _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes));
2829     _popframe_preserved_args_size = in_bytes(size_in_bytes);
2830     Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
2831   }
2832 }
2833 
2834 void* JavaThread::popframe_preserved_args() {
2835   return _popframe_preserved_args;
2836 }
2837 
2838 ByteSize JavaThread::popframe_preserved_args_size() {
2839   return in_ByteSize(_popframe_preserved_args_size);
2840 }
2841 
2842 WordSize JavaThread::popframe_preserved_args_size_in_words() {
2843   int sz = in_bytes(popframe_preserved_args_size());
2844   assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
2845   return in_WordSize(sz / wordSize);
2846 }
2847 
2848 void JavaThread::popframe_free_preserved_args() {
2849   assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
2850   FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
2851   _popframe_preserved_args = NULL;
2852   _popframe_preserved_args_size = 0;
2853 }
2854 
2855 #ifndef PRODUCT
2856 
2857 void JavaThread::trace_frames() {
2858   tty->print_cr("[Describe stack]");
2859   int frame_no = 1;
2860   for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2861     tty->print("  %d. ", frame_no++);
2862     fst.current()->print_value_on(tty,this);
2863     tty->cr();
2864   }
2865 }
2866 
2867 class PrintAndVerifyOopClosure: public OopClosure {
2868  protected:
2869   template <class T> inline void do_oop_work(T* p) {
2870     oop obj = oopDesc::load_decode_heap_oop(p);
2871     if (obj == NULL) return;
2872     tty->print(INTPTR_FORMAT ": ", p);
2873     if (obj->is_oop_or_null()) {
2874       if (obj->is_objArray()) {
2875         tty->print_cr("valid objArray: " INTPTR_FORMAT, (oopDesc*) obj);
2876       } else {
2877         obj->print();
2878       }
2879     } else {
2880       tty->print_cr("invalid oop: " INTPTR_FORMAT, (oopDesc*) obj);
2881     }
2882     tty->cr();
2883   }
2884  public:
2885   virtual void do_oop(oop* p) { do_oop_work(p); }
2886   virtual void do_oop(narrowOop* p)  { do_oop_work(p); }
2887 };
2888 
2889 
2890 static void oops_print(frame* f, const RegisterMap *map) {
2891   PrintAndVerifyOopClosure print;
2892   f->print_value();
2893   f->oops_do(&print, NULL, (RegisterMap*)map);
2894 }
2895 
2896 // Print our all the locations that contain oops and whether they are
2897 // valid or not.  This useful when trying to find the oldest frame
2898 // where an oop has gone bad since the frame walk is from youngest to
2899 // oldest.
2900 void JavaThread::trace_oops() {
2901   tty->print_cr("[Trace oops]");
2902   frames_do(oops_print);
2903 }
2904 
2905 
2906 #ifdef ASSERT
2907 // Print or validate the layout of stack frames
2908 void JavaThread::print_frame_layout(int depth, bool validate_only) {
2909   ResourceMark rm;
2910   PRESERVE_EXCEPTION_MARK;
2911   FrameValues values;
2912   int frame_no = 0;
2913   for(StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
2914     fst.current()->describe(values, ++frame_no);
2915     if (depth == frame_no) break;
2916   }
2917   if (validate_only) {
2918     values.validate();
2919   } else {
2920     tty->print_cr("[Describe stack layout]");
2921     values.print();
2922   }
2923 }
2924 #endif
2925 
2926 void JavaThread::trace_stack_from(vframe* start_vf) {
2927   ResourceMark rm;
2928   int vframe_no = 1;
2929   for (vframe* f = start_vf; f; f = f->sender() ) {
2930     if (f->is_java_frame()) {
2931       javaVFrame::cast(f)->print_activation(vframe_no++);
2932     } else {
2933       f->print();
2934     }
2935     if (vframe_no > StackPrintLimit) {
2936       tty->print_cr("...<more frames>...");
2937       return;
2938     }
2939   }
2940 }
2941 
2942 
2943 void JavaThread::trace_stack() {
2944   if (!has_last_Java_frame()) return;
2945   ResourceMark rm;
2946   HandleMark   hm;
2947   RegisterMap reg_map(this);
2948   trace_stack_from(last_java_vframe(&reg_map));
2949 }
2950 
2951 
2952 #endif // PRODUCT
2953 
2954 
2955 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
2956   assert(reg_map != NULL, "a map must be given");
2957   frame f = last_frame();
2958   for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender() ) {
2959     if (vf->is_java_frame()) return javaVFrame::cast(vf);
2960   }
2961   return NULL;
2962 }
2963 
2964 
2965 klassOop JavaThread::security_get_caller_class(int depth) {
2966   vframeStream vfst(this);
2967   vfst.security_get_caller_frame(depth);
2968   if (!vfst.at_end()) {
2969     return vfst.method()->method_holder();
2970   }
2971   return NULL;
2972 }
2973 
2974 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
2975   assert(thread->is_Compiler_thread(), "must be compiler thread");
2976   CompileBroker::compiler_thread_loop();
2977 }
2978 
2979 // Create a CompilerThread
2980 CompilerThread::CompilerThread(CompileQueue* queue, CompilerCounters* counters)
2981 : JavaThread(&compiler_thread_entry) {
2982   _env   = NULL;
2983   _log   = NULL;
2984   _task  = NULL;
2985   _queue = queue;
2986   _counters = counters;
2987   _buffer_blob = NULL;
2988   _scanned_nmethod = NULL;
2989 
2990 #ifndef PRODUCT
2991   _ideal_graph_printer = NULL;
2992 #endif
2993 }
2994 
2995 void CompilerThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2996   JavaThread::oops_do(f, cf);
2997   if (_scanned_nmethod != NULL && cf != NULL) {
2998     // Safepoints can occur when the sweeper is scanning an nmethod so
2999     // process it here to make sure it isn't unloaded in the middle of
3000     // a scan.
3001     cf->do_code_blob(_scanned_nmethod);
3002   }
3003 }
3004 
3005 // ======= Threads ========
3006 
3007 // The Threads class links together all active threads, and provides
3008 // operations over all threads.  It is protected by its own Mutex
3009 // lock, which is also used in other contexts to protect thread
3010 // operations from having the thread being operated on from exiting
3011 // and going away unexpectedly (e.g., safepoint synchronization)
3012 
3013 JavaThread* Threads::_thread_list = NULL;
3014 int         Threads::_number_of_threads = 0;
3015 int         Threads::_number_of_non_daemon_threads = 0;
3016 int         Threads::_return_code = 0;
3017 size_t      JavaThread::_stack_size_at_create = 0;
3018 
3019 // All JavaThreads
3020 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
3021 
3022 void os_stream();
3023 
3024 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3025 void Threads::threads_do(ThreadClosure* tc) {
3026   assert_locked_or_safepoint(Threads_lock);
3027   // ALL_JAVA_THREADS iterates through all JavaThreads
3028   ALL_JAVA_THREADS(p) {
3029     tc->do_thread(p);
3030   }
3031   // Someday we could have a table or list of all non-JavaThreads.
3032   // For now, just manually iterate through them.
3033   tc->do_thread(VMThread::vm_thread());
3034   Universe::heap()->gc_threads_do(tc);
3035   WatcherThread *wt = WatcherThread::watcher_thread();
3036   // Strictly speaking, the following NULL check isn't sufficient to make sure
3037   // the data for WatcherThread is still valid upon being examined. However,
3038   // considering that WatchThread terminates when the VM is on the way to
3039   // exit at safepoint, the chance of the above is extremely small. The right
3040   // way to prevent termination of WatcherThread would be to acquire
3041   // Terminator_lock, but we can't do that without violating the lock rank
3042   // checking in some cases.
3043   if (wt != NULL)
3044     tc->do_thread(wt);
3045 
3046   // If CompilerThreads ever become non-JavaThreads, add them here
3047 }
3048 
3049 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3050 
3051   extern void JDK_Version_init();
3052 
3053   // Check version
3054   if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3055 
3056   // Initialize the output stream module
3057   ostream_init();
3058 
3059   // Process java launcher properties.
3060   Arguments::process_sun_java_launcher_properties(args);
3061 
3062   // Initialize the os module before using TLS
3063   os::init();
3064 
3065   // Initialize system properties.
3066   Arguments::init_system_properties();
3067 
3068   // So that JDK version can be used as a discrimintor when parsing arguments
3069   JDK_Version_init();
3070 
3071   // Update/Initialize System properties after JDK version number is known
3072   Arguments::init_version_specific_system_properties();
3073 
3074   // Parse arguments
3075   jint parse_result = Arguments::parse(args);
3076   if (parse_result != JNI_OK) return parse_result;
3077 
3078   if (PauseAtStartup) {
3079     os::pause();
3080   }
3081 
3082   HS_DTRACE_PROBE(hotspot, vm__init__begin);
3083 
3084   // Record VM creation timing statistics
3085   TraceVmCreationTime create_vm_timer;
3086   create_vm_timer.start();
3087 
3088   // Timing (must come after argument parsing)
3089   TraceTime timer("Create VM", TraceStartupTime);
3090 
3091   // Initialize the os module after parsing the args
3092   jint os_init_2_result = os::init_2();
3093   if (os_init_2_result != JNI_OK) return os_init_2_result;
3094 
3095   // Initialize output stream logging
3096   ostream_init_log();
3097 
3098   // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3099   // Must be before create_vm_init_agents()
3100   if (Arguments::init_libraries_at_startup()) {
3101     convert_vm_init_libraries_to_agents();
3102   }
3103 
3104   // Launch -agentlib/-agentpath and converted -Xrun agents
3105   if (Arguments::init_agents_at_startup()) {
3106     create_vm_init_agents();
3107   }
3108 
3109   // Initialize Threads state
3110   _thread_list = NULL;
3111   _number_of_threads = 0;
3112   _number_of_non_daemon_threads = 0;
3113 
3114   // Initialize TLS
3115   ThreadLocalStorage::init();
3116 
3117   // Initialize global data structures and create system classes in heap
3118   vm_init_globals();
3119 
3120   // Attach the main thread to this os thread
3121   JavaThread* main_thread = new JavaThread();
3122   main_thread->set_thread_state(_thread_in_vm);
3123   // must do this before set_active_handles and initialize_thread_local_storage
3124   // Note: on solaris initialize_thread_local_storage() will (indirectly)
3125   // change the stack size recorded here to one based on the java thread
3126   // stacksize. This adjusted size is what is used to figure the placement
3127   // of the guard pages.
3128   main_thread->record_stack_base_and_size();
3129   main_thread->initialize_thread_local_storage();
3130 
3131   main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3132 
3133   if (!main_thread->set_as_starting_thread()) {
3134     vm_shutdown_during_initialization(
3135       "Failed necessary internal allocation. Out of swap space");
3136     delete main_thread;
3137     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3138     return JNI_ENOMEM;
3139   }
3140 
3141   // Enable guard page *after* os::create_main_thread(), otherwise it would
3142   // crash Linux VM, see notes in os_linux.cpp.
3143   main_thread->create_stack_guard_pages();
3144 
3145   // Initialize Java-Level synchronization subsystem
3146   ObjectMonitor::Initialize() ;
3147 
3148   // Initialize global modules
3149   jint status = init_globals();
3150   if (status != JNI_OK) {
3151     delete main_thread;
3152     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3153     return status;
3154   }
3155 
3156   // Should be done after the heap is fully created
3157   main_thread->cache_global_variables();
3158 
3159   HandleMark hm;
3160 
3161   { MutexLocker mu(Threads_lock);
3162     Threads::add(main_thread);
3163   }
3164 
3165   // Any JVMTI raw monitors entered in onload will transition into
3166   // real raw monitor. VM is setup enough here for raw monitor enter.
3167   JvmtiExport::transition_pending_onload_raw_monitors();
3168 
3169   if (VerifyBeforeGC &&
3170       Universe::heap()->total_collections() >= VerifyGCStartAt) {
3171     Universe::heap()->prepare_for_verify();
3172     Universe::verify();   // make sure we're starting with a clean slate
3173   }
3174 
3175   // Create the VMThread
3176   { TraceTime timer("Start VMThread", TraceStartupTime);
3177     VMThread::create();
3178     Thread* vmthread = VMThread::vm_thread();
3179 
3180     if (!os::create_thread(vmthread, os::vm_thread))
3181       vm_exit_during_initialization("Cannot create VM thread. Out of system resources.");
3182 
3183     // Wait for the VM thread to become ready, and VMThread::run to initialize
3184     // Monitors can have spurious returns, must always check another state flag
3185     {
3186       MutexLocker ml(Notify_lock);
3187       os::start_thread(vmthread);
3188       while (vmthread->active_handles() == NULL) {
3189         Notify_lock->wait();
3190       }
3191     }
3192   }
3193 
3194   assert (Universe::is_fully_initialized(), "not initialized");
3195   EXCEPTION_MARK;
3196 
3197   // At this point, the Universe is initialized, but we have not executed
3198   // any byte code.  Now is a good time (the only time) to dump out the
3199   // internal state of the JVM for sharing.
3200 
3201   if (DumpSharedSpaces) {
3202     Universe::heap()->preload_and_dump(CHECK_0);
3203     ShouldNotReachHere();
3204   }
3205 
3206   // Always call even when there are not JVMTI environments yet, since environments
3207   // may be attached late and JVMTI must track phases of VM execution
3208   JvmtiExport::enter_start_phase();
3209 
3210   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3211   JvmtiExport::post_vm_start();
3212 
3213   {
3214     TraceTime timer("Initialize java.lang classes", TraceStartupTime);
3215 
3216     if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3217       create_vm_init_libraries();
3218     }
3219 
3220     if (InitializeJavaLangString) {
3221       initialize_class(vmSymbols::java_lang_String(), CHECK_0);
3222     } else {
3223       warning("java.lang.String not initialized");
3224     }
3225 
3226     if (AggressiveOpts) {
3227       {
3228         // Forcibly initialize java/util/HashMap and mutate the private
3229         // static final "frontCacheEnabled" field before we start creating instances
3230 #ifdef ASSERT
3231         klassOop tmp_k = SystemDictionary::find(vmSymbols::java_util_HashMap(), Handle(), Handle(), CHECK_0);
3232         assert(tmp_k == NULL, "java/util/HashMap should not be loaded yet");
3233 #endif
3234         klassOop k_o = SystemDictionary::resolve_or_null(vmSymbols::java_util_HashMap(), Handle(), Handle(), CHECK_0);
3235         KlassHandle k = KlassHandle(THREAD, k_o);
3236         guarantee(k.not_null(), "Must find java/util/HashMap");
3237         instanceKlassHandle ik = instanceKlassHandle(THREAD, k());
3238         ik->initialize(CHECK_0);
3239         fieldDescriptor fd;
3240         // Possible we might not find this field; if so, don't break
3241         if (ik->find_local_field(vmSymbols::frontCacheEnabled_name(), vmSymbols::bool_signature(), &fd)) {
3242           k()->java_mirror()->bool_field_put(fd.offset(), true);
3243         }
3244       }
3245 
3246       if (UseStringCache) {
3247         // Forcibly initialize java/lang/StringValue and mutate the private
3248         // static final "stringCacheEnabled" field before we start creating instances
3249         klassOop k_o = SystemDictionary::resolve_or_null(vmSymbols::java_lang_StringValue(), Handle(), Handle(), CHECK_0);
3250         // Possible that StringValue isn't present: if so, silently don't break
3251         if (k_o != NULL) {
3252           KlassHandle k = KlassHandle(THREAD, k_o);
3253           instanceKlassHandle ik = instanceKlassHandle(THREAD, k());
3254           ik->initialize(CHECK_0);
3255           fieldDescriptor fd;
3256           // Possible we might not find this field: if so, silently don't break
3257           if (ik->find_local_field(vmSymbols::stringCacheEnabled_name(), vmSymbols::bool_signature(), &fd)) {
3258             k()->java_mirror()->bool_field_put(fd.offset(), true);
3259           }
3260         }
3261       }
3262     }
3263 
3264     // Initialize java_lang.System (needed before creating the thread)
3265     if (InitializeJavaLangSystem) {
3266       initialize_class(vmSymbols::java_lang_System(), CHECK_0);
3267       initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK_0);
3268       Handle thread_group = create_initial_thread_group(CHECK_0);
3269       Universe::set_main_thread_group(thread_group());
3270       initialize_class(vmSymbols::java_lang_Thread(), CHECK_0);
3271       oop thread_object = create_initial_thread(thread_group, main_thread, CHECK_0);
3272       main_thread->set_threadObj(thread_object);
3273       // Set thread status to running since main thread has
3274       // been started and running.
3275       java_lang_Thread::set_thread_status(thread_object,
3276                                           java_lang_Thread::RUNNABLE);
3277 
3278       // The VM preresolve methods to these classes. Make sure that get initialized
3279       initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK_0);
3280       initialize_class(vmSymbols::java_lang_ref_Finalizer(),  CHECK_0);
3281       // The VM creates & returns objects of this class. Make sure it's initialized.
3282       initialize_class(vmSymbols::java_lang_Class(), CHECK_0);
3283       call_initializeSystemClass(CHECK_0);
3284     } else {
3285       warning("java.lang.System not initialized");
3286     }
3287 
3288     // an instance of OutOfMemory exception has been allocated earlier
3289     if (InitializeJavaLangExceptionsErrors) {
3290       initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK_0);
3291       initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK_0);
3292       initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK_0);
3293       initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK_0);
3294       initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK_0);
3295       initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK_0);
3296       initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK_0);
3297     } else {
3298       warning("java.lang.OutOfMemoryError has not been initialized");
3299       warning("java.lang.NullPointerException has not been initialized");
3300       warning("java.lang.ClassCastException has not been initialized");
3301       warning("java.lang.ArrayStoreException has not been initialized");
3302       warning("java.lang.ArithmeticException has not been initialized");
3303       warning("java.lang.StackOverflowError has not been initialized");
3304     }
3305   }
3306 
3307   // See        : bugid 4211085.
3308   // Background : the static initializer of java.lang.Compiler tries to read
3309   //              property"java.compiler" and read & write property "java.vm.info".
3310   //              When a security manager is installed through the command line
3311   //              option "-Djava.security.manager", the above properties are not
3312   //              readable and the static initializer for java.lang.Compiler fails
3313   //              resulting in a NoClassDefFoundError.  This can happen in any
3314   //              user code which calls methods in java.lang.Compiler.
3315   // Hack :       the hack is to pre-load and initialize this class, so that only
3316   //              system domains are on the stack when the properties are read.
3317   //              Currently even the AWT code has calls to methods in java.lang.Compiler.
3318   //              On the classic VM, java.lang.Compiler is loaded very early to load the JIT.
3319   // Future Fix : the best fix is to grant everyone permissions to read "java.compiler" and
3320   //              read and write"java.vm.info" in the default policy file. See bugid 4211383
3321   //              Once that is done, we should remove this hack.
3322   initialize_class(vmSymbols::java_lang_Compiler(), CHECK_0);
3323 
3324   // More hackery - the static initializer of java.lang.Compiler adds the string "nojit" to
3325   // the java.vm.info property if no jit gets loaded through java.lang.Compiler (the hotspot
3326   // compiler does not get loaded through java.lang.Compiler).  "java -version" with the
3327   // hotspot vm says "nojit" all the time which is confusing.  So, we reset it here.
3328   // This should also be taken out as soon as 4211383 gets fixed.
3329   reset_vm_info_property(CHECK_0);
3330 
3331   quicken_jni_functions();
3332 
3333   // Set flag that basic initialization has completed. Used by exceptions and various
3334   // debug stuff, that does not work until all basic classes have been initialized.
3335   set_init_completed();
3336 
3337   HS_DTRACE_PROBE(hotspot, vm__init__end);
3338 
3339   // record VM initialization completion time
3340   Management::record_vm_init_completed();
3341 
3342   // Compute system loader. Note that this has to occur after set_init_completed, since
3343   // valid exceptions may be thrown in the process.
3344   // Note that we do not use CHECK_0 here since we are inside an EXCEPTION_MARK and
3345   // set_init_completed has just been called, causing exceptions not to be shortcut
3346   // anymore. We call vm_exit_during_initialization directly instead.
3347   SystemDictionary::compute_java_system_loader(THREAD);
3348   if (HAS_PENDING_EXCEPTION) {
3349     vm_exit_during_initialization(Handle(THREAD, PENDING_EXCEPTION));
3350   }
3351 
3352 #ifndef SERIALGC
3353   // Support for ConcurrentMarkSweep. This should be cleaned up
3354   // and better encapsulated. The ugly nested if test would go away
3355   // once things are properly refactored. XXX YSR
3356   if (UseConcMarkSweepGC || UseG1GC) {
3357     if (UseConcMarkSweepGC) {
3358       ConcurrentMarkSweepThread::makeSurrogateLockerThread(THREAD);
3359     } else {
3360       ConcurrentMarkThread::makeSurrogateLockerThread(THREAD);
3361     }
3362     if (HAS_PENDING_EXCEPTION) {
3363       vm_exit_during_initialization(Handle(THREAD, PENDING_EXCEPTION));
3364     }
3365   }
3366 #endif // SERIALGC
3367 
3368   // Always call even when there are not JVMTI environments yet, since environments
3369   // may be attached late and JVMTI must track phases of VM execution
3370   JvmtiExport::enter_live_phase();
3371 
3372   // Signal Dispatcher needs to be started before VMInit event is posted
3373   os::signal_init();
3374 
3375   // Start Attach Listener if +StartAttachListener or it can't be started lazily
3376   if (!DisableAttachMechanism) {
3377     if (StartAttachListener || AttachListener::init_at_startup()) {
3378       AttachListener::init();
3379     }
3380   }
3381 
3382   // Launch -Xrun agents
3383   // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3384   // back-end can launch with -Xdebug -Xrunjdwp.
3385   if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3386     create_vm_init_libraries();
3387   }
3388 
3389   // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3390   JvmtiExport::post_vm_initialized();
3391 
3392   if (CleanChunkPoolAsync) {
3393     Chunk::start_chunk_pool_cleaner_task();
3394   }
3395 
3396   // initialize compiler(s)
3397   CompileBroker::compilation_init();
3398 
3399   Management::initialize(THREAD);
3400   if (HAS_PENDING_EXCEPTION) {
3401     // management agent fails to start possibly due to
3402     // configuration problem and is responsible for printing
3403     // stack trace if appropriate. Simply exit VM.
3404     vm_exit(1);
3405   }
3406 
3407   if (Arguments::has_profile())       FlatProfiler::engage(main_thread, true);
3408   if (Arguments::has_alloc_profile()) AllocationProfiler::engage();
3409   if (MemProfiling)                   MemProfiler::engage();
3410   StatSampler::engage();
3411   if (CheckJNICalls)                  JniPeriodicChecker::engage();
3412 
3413   BiasedLocking::init();
3414 
3415   if (JDK_Version::current().post_vm_init_hook_enabled()) {
3416     call_postVMInitHook(THREAD);
3417     // The Java side of PostVMInitHook.run must deal with all
3418     // exceptions and provide means of diagnosis.
3419     if (HAS_PENDING_EXCEPTION) {
3420       CLEAR_PENDING_EXCEPTION;
3421     }
3422   }
3423 
3424   // Start up the WatcherThread if there are any periodic tasks
3425   // NOTE:  All PeriodicTasks should be registered by now. If they
3426   //   aren't, late joiners might appear to start slowly (we might
3427   //   take a while to process their first tick).
3428   if (PeriodicTask::num_tasks() > 0) {
3429     WatcherThread::start();
3430   }
3431 
3432   // Give os specific code one last chance to start
3433   os::init_3();
3434 
3435   create_vm_timer.end();
3436   return JNI_OK;
3437 }
3438 
3439 // type for the Agent_OnLoad and JVM_OnLoad entry points
3440 extern "C" {
3441   typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3442 }
3443 // Find a command line agent library and return its entry point for
3444 //         -agentlib:  -agentpath:   -Xrun
3445 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3446 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, const char *on_load_symbols[], size_t num_symbol_entries) {
3447   OnLoadEntry_t on_load_entry = NULL;
3448   void *library = agent->os_lib();  // check if we have looked it up before
3449 
3450   if (library == NULL) {
3451     char buffer[JVM_MAXPATHLEN];
3452     char ebuf[1024];
3453     const char *name = agent->name();
3454     const char *msg = "Could not find agent library ";
3455 
3456     if (agent->is_absolute_path()) {
3457       library = os::dll_load(name, ebuf, sizeof ebuf);
3458       if (library == NULL) {
3459         const char *sub_msg = " in absolute path, with error: ";
3460         size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3461         char *buf = NEW_C_HEAP_ARRAY(char, len);
3462         jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3463         // If we can't find the agent, exit.
3464         vm_exit_during_initialization(buf, NULL);
3465         FREE_C_HEAP_ARRAY(char, buf);
3466       }
3467     } else {
3468       // Try to load the agent from the standard dll directory
3469       os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(), name);
3470       library = os::dll_load(buffer, ebuf, sizeof ebuf);
3471 #ifdef KERNEL
3472       // Download instrument dll
3473       if (library == NULL && strcmp(name, "instrument") == 0) {
3474         char *props = Arguments::get_kernel_properties();
3475         char *home  = Arguments::get_java_home();
3476         const char *fmt   = "%s/bin/java %s -Dkernel.background.download=false"
3477                       " sun.jkernel.DownloadManager -download client_jvm";
3478         size_t length = strlen(props) + strlen(home) + strlen(fmt) + 1;
3479         char *cmd = NEW_C_HEAP_ARRAY(char, length);
3480         jio_snprintf(cmd, length, fmt, home, props);
3481         int status = os::fork_and_exec(cmd);
3482         FreeHeap(props);
3483         if (status == -1) {
3484           warning(cmd);
3485           vm_exit_during_initialization("fork_and_exec failed: %s",
3486                                          strerror(errno));
3487         }
3488         FREE_C_HEAP_ARRAY(char, cmd);
3489         // when this comes back the instrument.dll should be where it belongs.
3490         library = os::dll_load(buffer, ebuf, sizeof ebuf);
3491       }
3492 #endif // KERNEL
3493       if (library == NULL) { // Try the local directory
3494         char ns[1] = {0};
3495         os::dll_build_name(buffer, sizeof(buffer), ns, name);
3496         library = os::dll_load(buffer, ebuf, sizeof ebuf);
3497         if (library == NULL) {
3498           const char *sub_msg = " on the library path, with error: ";
3499           size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3500           char *buf = NEW_C_HEAP_ARRAY(char, len);
3501           jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3502           // If we can't find the agent, exit.
3503           vm_exit_during_initialization(buf, NULL);
3504           FREE_C_HEAP_ARRAY(char, buf);
3505         }
3506       }
3507     }
3508     agent->set_os_lib(library);
3509   }
3510 
3511   // Find the OnLoad function.
3512   for (size_t symbol_index = 0; symbol_index < num_symbol_entries; symbol_index++) {
3513     on_load_entry = CAST_TO_FN_PTR(OnLoadEntry_t, os::dll_lookup(library, on_load_symbols[symbol_index]));
3514     if (on_load_entry != NULL) break;
3515   }
3516   return on_load_entry;
3517 }
3518 
3519 // Find the JVM_OnLoad entry point
3520 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3521   const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3522   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3523 }
3524 
3525 // Find the Agent_OnLoad entry point
3526 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3527   const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3528   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3529 }
3530 
3531 // For backwards compatibility with -Xrun
3532 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3533 // treated like -agentpath:
3534 // Must be called before agent libraries are created
3535 void Threads::convert_vm_init_libraries_to_agents() {
3536   AgentLibrary* agent;
3537   AgentLibrary* next;
3538 
3539   for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3540     next = agent->next();  // cache the next agent now as this agent may get moved off this list
3541     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3542 
3543     // If there is an JVM_OnLoad function it will get called later,
3544     // otherwise see if there is an Agent_OnLoad
3545     if (on_load_entry == NULL) {
3546       on_load_entry = lookup_agent_on_load(agent);
3547       if (on_load_entry != NULL) {
3548         // switch it to the agent list -- so that Agent_OnLoad will be called,
3549         // JVM_OnLoad won't be attempted and Agent_OnUnload will
3550         Arguments::convert_library_to_agent(agent);
3551       } else {
3552         vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3553       }
3554     }
3555   }
3556 }
3557 
3558 // Create agents for -agentlib:  -agentpath:  and converted -Xrun
3559 // Invokes Agent_OnLoad
3560 // Called very early -- before JavaThreads exist
3561 void Threads::create_vm_init_agents() {
3562   extern struct JavaVM_ main_vm;
3563   AgentLibrary* agent;
3564 
3565   JvmtiExport::enter_onload_phase();
3566   for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3567     OnLoadEntry_t  on_load_entry = lookup_agent_on_load(agent);
3568 
3569     if (on_load_entry != NULL) {
3570       // Invoke the Agent_OnLoad function
3571       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3572       if (err != JNI_OK) {
3573         vm_exit_during_initialization("agent library failed to init", agent->name());
3574       }
3575     } else {
3576       vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
3577     }
3578   }
3579   JvmtiExport::enter_primordial_phase();
3580 }
3581 
3582 extern "C" {
3583   typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
3584 }
3585 
3586 void Threads::shutdown_vm_agents() {
3587   // Send any Agent_OnUnload notifications
3588   const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
3589   extern struct JavaVM_ main_vm;
3590   for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3591 
3592     // Find the Agent_OnUnload function.
3593     for (uint symbol_index = 0; symbol_index < ARRAY_SIZE(on_unload_symbols); symbol_index++) {
3594       Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
3595                os::dll_lookup(agent->os_lib(), on_unload_symbols[symbol_index]));
3596 
3597       // Invoke the Agent_OnUnload function
3598       if (unload_entry != NULL) {
3599         JavaThread* thread = JavaThread::current();
3600         ThreadToNativeFromVM ttn(thread);
3601         HandleMark hm(thread);
3602         (*unload_entry)(&main_vm);
3603         break;
3604       }
3605     }
3606   }
3607 }
3608 
3609 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
3610 // Invokes JVM_OnLoad
3611 void Threads::create_vm_init_libraries() {
3612   extern struct JavaVM_ main_vm;
3613   AgentLibrary* agent;
3614 
3615   for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
3616     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3617 
3618     if (on_load_entry != NULL) {
3619       // Invoke the JVM_OnLoad function
3620       JavaThread* thread = JavaThread::current();
3621       ThreadToNativeFromVM ttn(thread);
3622       HandleMark hm(thread);
3623       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3624       if (err != JNI_OK) {
3625         vm_exit_during_initialization("-Xrun library failed to init", agent->name());
3626       }
3627     } else {
3628       vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
3629     }
3630   }
3631 }
3632 
3633 // Last thread running calls java.lang.Shutdown.shutdown()
3634 void JavaThread::invoke_shutdown_hooks() {
3635   HandleMark hm(this);
3636 
3637   // We could get here with a pending exception, if so clear it now.
3638   if (this->has_pending_exception()) {
3639     this->clear_pending_exception();
3640   }
3641 
3642   EXCEPTION_MARK;
3643   klassOop k =
3644     SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
3645                                       THREAD);
3646   if (k != NULL) {
3647     // SystemDictionary::resolve_or_null will return null if there was
3648     // an exception.  If we cannot load the Shutdown class, just don't
3649     // call Shutdown.shutdown() at all.  This will mean the shutdown hooks
3650     // and finalizers (if runFinalizersOnExit is set) won't be run.
3651     // Note that if a shutdown hook was registered or runFinalizersOnExit
3652     // was called, the Shutdown class would have already been loaded
3653     // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
3654     instanceKlassHandle shutdown_klass (THREAD, k);
3655     JavaValue result(T_VOID);
3656     JavaCalls::call_static(&result,
3657                            shutdown_klass,
3658                            vmSymbols::shutdown_method_name(),
3659                            vmSymbols::void_method_signature(),
3660                            THREAD);
3661   }
3662   CLEAR_PENDING_EXCEPTION;
3663 }
3664 
3665 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
3666 // the program falls off the end of main(). Another VM exit path is through
3667 // vm_exit() when the program calls System.exit() to return a value or when
3668 // there is a serious error in VM. The two shutdown paths are not exactly
3669 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
3670 // and VM_Exit op at VM level.
3671 //
3672 // Shutdown sequence:
3673 //   + Wait until we are the last non-daemon thread to execute
3674 //     <-- every thing is still working at this moment -->
3675 //   + Call java.lang.Shutdown.shutdown(), which will invoke Java level
3676 //        shutdown hooks, run finalizers if finalization-on-exit
3677 //   + Call before_exit(), prepare for VM exit
3678 //      > run VM level shutdown hooks (they are registered through JVM_OnExit(),
3679 //        currently the only user of this mechanism is File.deleteOnExit())
3680 //      > stop flat profiler, StatSampler, watcher thread, CMS threads,
3681 //        post thread end and vm death events to JVMTI,
3682 //        stop signal thread
3683 //   + Call JavaThread::exit(), it will:
3684 //      > release JNI handle blocks, remove stack guard pages
3685 //      > remove this thread from Threads list
3686 //     <-- no more Java code from this thread after this point -->
3687 //   + Stop VM thread, it will bring the remaining VM to a safepoint and stop
3688 //     the compiler threads at safepoint
3689 //     <-- do not use anything that could get blocked by Safepoint -->
3690 //   + Disable tracing at JNI/JVM barriers
3691 //   + Set _vm_exited flag for threads that are still running native code
3692 //   + Delete this thread
3693 //   + Call exit_globals()
3694 //      > deletes tty
3695 //      > deletes PerfMemory resources
3696 //   + Return to caller
3697 
3698 bool Threads::destroy_vm() {
3699   JavaThread* thread = JavaThread::current();
3700 
3701   // Wait until we are the last non-daemon thread to execute
3702   { MutexLocker nu(Threads_lock);
3703     while (Threads::number_of_non_daemon_threads() > 1 )
3704       // This wait should make safepoint checks, wait without a timeout,
3705       // and wait as a suspend-equivalent condition.
3706       //
3707       // Note: If the FlatProfiler is running and this thread is waiting
3708       // for another non-daemon thread to finish, then the FlatProfiler
3709       // is waiting for the external suspend request on this thread to
3710       // complete. wait_for_ext_suspend_completion() will eventually
3711       // timeout, but that takes time. Making this wait a suspend-
3712       // equivalent condition solves that timeout problem.
3713       //
3714       Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
3715                          Mutex::_as_suspend_equivalent_flag);
3716   }
3717 
3718   // Hang forever on exit if we are reporting an error.
3719   if (ShowMessageBoxOnError && is_error_reported()) {
3720     os::infinite_sleep();
3721   }
3722   os::wait_for_keypress_at_exit();
3723 
3724   if (JDK_Version::is_jdk12x_version()) {
3725     // We are the last thread running, so check if finalizers should be run.
3726     // For 1.3 or later this is done in thread->invoke_shutdown_hooks()
3727     HandleMark rm(thread);
3728     Universe::run_finalizers_on_exit();
3729   } else {
3730     // run Java level shutdown hooks
3731     thread->invoke_shutdown_hooks();
3732   }
3733 
3734   before_exit(thread);
3735 
3736   thread->exit(true);
3737 
3738   // Stop VM thread.
3739   {
3740     // 4945125 The vm thread comes to a safepoint during exit.
3741     // GC vm_operations can get caught at the safepoint, and the
3742     // heap is unparseable if they are caught. Grab the Heap_lock
3743     // to prevent this. The GC vm_operations will not be able to
3744     // queue until after the vm thread is dead.
3745     // After this point, we'll never emerge out of the safepoint before
3746     // the VM exits, so concurrent GC threads do not need to be explicitly
3747     // stopped; they remain inactive until the process exits.
3748     // Note: some concurrent G1 threads may be running during a safepoint,
3749     // but these will not be accessing the heap, just some G1-specific side
3750     // data structures that are not accessed by any other threads but them
3751     // after this point in a terminal safepoint.
3752 
3753     MutexLocker ml(Heap_lock);
3754 
3755     VMThread::wait_for_vm_thread_exit();
3756     assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
3757     VMThread::destroy();
3758   }
3759 
3760   // clean up ideal graph printers
3761 #if defined(COMPILER2) && !defined(PRODUCT)
3762   IdealGraphPrinter::clean_up();
3763 #endif
3764 
3765   // Now, all Java threads are gone except daemon threads. Daemon threads
3766   // running Java code or in VM are stopped by the Safepoint. However,
3767   // daemon threads executing native code are still running.  But they
3768   // will be stopped at native=>Java/VM barriers. Note that we can't
3769   // simply kill or suspend them, as it is inherently deadlock-prone.
3770 
3771 #ifndef PRODUCT
3772   // disable function tracing at JNI/JVM barriers
3773   TraceJNICalls = false;
3774   TraceJVMCalls = false;
3775   TraceRuntimeCalls = false;
3776 #endif
3777 
3778   VM_Exit::set_vm_exited();
3779 
3780   notify_vm_shutdown();
3781 
3782   delete thread;
3783 
3784   // exit_globals() will delete tty
3785   exit_globals();
3786 
3787   return true;
3788 }
3789 
3790 
3791 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
3792   if (version == JNI_VERSION_1_1) return JNI_TRUE;
3793   return is_supported_jni_version(version);
3794 }
3795 
3796 
3797 jboolean Threads::is_supported_jni_version(jint version) {
3798   if (version == JNI_VERSION_1_2) return JNI_TRUE;
3799   if (version == JNI_VERSION_1_4) return JNI_TRUE;
3800   if (version == JNI_VERSION_1_6) return JNI_TRUE;
3801   return JNI_FALSE;
3802 }
3803 
3804 
3805 void Threads::add(JavaThread* p, bool force_daemon) {
3806   // The threads lock must be owned at this point
3807   assert_locked_or_safepoint(Threads_lock);
3808 
3809   // See the comment for this method in thread.hpp for its purpose and
3810   // why it is called here.
3811   p->initialize_queues();
3812   p->set_next(_thread_list);
3813   _thread_list = p;
3814   _number_of_threads++;
3815   oop threadObj = p->threadObj();
3816   bool daemon = true;
3817   // Bootstrapping problem: threadObj can be null for initial
3818   // JavaThread (or for threads attached via JNI)
3819   if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
3820     _number_of_non_daemon_threads++;
3821     daemon = false;
3822   }
3823 
3824   ThreadService::add_thread(p, daemon);
3825 
3826   // Possible GC point.
3827   Events::log("Thread added: " INTPTR_FORMAT, p);
3828 }
3829 
3830 void Threads::remove(JavaThread* p) {
3831   // Extra scope needed for Thread_lock, so we can check
3832   // that we do not remove thread without safepoint code notice
3833   { MutexLocker ml(Threads_lock);
3834 
3835     assert(includes(p), "p must be present");
3836 
3837     JavaThread* current = _thread_list;
3838     JavaThread* prev    = NULL;
3839 
3840     while (current != p) {
3841       prev    = current;
3842       current = current->next();
3843     }
3844 
3845     if (prev) {
3846       prev->set_next(current->next());
3847     } else {
3848       _thread_list = p->next();
3849     }
3850     _number_of_threads--;
3851     oop threadObj = p->threadObj();
3852     bool daemon = true;
3853     if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
3854       _number_of_non_daemon_threads--;
3855       daemon = false;
3856 
3857       // Only one thread left, do a notify on the Threads_lock so a thread waiting
3858       // on destroy_vm will wake up.
3859       if (number_of_non_daemon_threads() == 1)
3860         Threads_lock->notify_all();
3861     }
3862     ThreadService::remove_thread(p, daemon);
3863 
3864     // Make sure that safepoint code disregard this thread. This is needed since
3865     // the thread might mess around with locks after this point. This can cause it
3866     // to do callbacks into the safepoint code. However, the safepoint code is not aware
3867     // of this thread since it is removed from the queue.
3868     p->set_terminated_value();
3869   } // unlock Threads_lock
3870 
3871   // Since Events::log uses a lock, we grab it outside the Threads_lock
3872   Events::log("Thread exited: " INTPTR_FORMAT, p);
3873 }
3874 
3875 // Threads_lock must be held when this is called (or must be called during a safepoint)
3876 bool Threads::includes(JavaThread* p) {
3877   assert(Threads_lock->is_locked(), "sanity check");
3878   ALL_JAVA_THREADS(q) {
3879     if (q == p ) {
3880       return true;
3881     }
3882   }
3883   return false;
3884 }
3885 
3886 // Operations on the Threads list for GC.  These are not explicitly locked,
3887 // but the garbage collector must provide a safe context for them to run.
3888 // In particular, these things should never be called when the Threads_lock
3889 // is held by some other thread. (Note: the Safepoint abstraction also
3890 // uses the Threads_lock to gurantee this property. It also makes sure that
3891 // all threads gets blocked when exiting or starting).
3892 
3893 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3894   ALL_JAVA_THREADS(p) {
3895     p->oops_do(f, cf);
3896   }
3897   VMThread::vm_thread()->oops_do(f, cf);
3898 }
3899 
3900 void Threads::possibly_parallel_oops_do(OopClosure* f, CodeBlobClosure* cf) {
3901   // Introduce a mechanism allowing parallel threads to claim threads as
3902   // root groups.  Overhead should be small enough to use all the time,
3903   // even in sequential code.
3904   SharedHeap* sh = SharedHeap::heap();
3905   bool is_par = (sh->n_par_threads() > 0);
3906   int cp = SharedHeap::heap()->strong_roots_parity();
3907   ALL_JAVA_THREADS(p) {
3908     if (p->claim_oops_do(is_par, cp)) {
3909       p->oops_do(f, cf);
3910     }
3911   }
3912   VMThread* vmt = VMThread::vm_thread();
3913   if (vmt->claim_oops_do(is_par, cp)) {
3914     vmt->oops_do(f, cf);
3915   }
3916 }
3917 
3918 #ifndef SERIALGC
3919 // Used by ParallelScavenge
3920 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
3921   ALL_JAVA_THREADS(p) {
3922     q->enqueue(new ThreadRootsTask(p));
3923   }
3924   q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
3925 }
3926 
3927 // Used by Parallel Old
3928 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
3929   ALL_JAVA_THREADS(p) {
3930     q->enqueue(new ThreadRootsMarkingTask(p));
3931   }
3932   q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
3933 }
3934 #endif // SERIALGC
3935 
3936 void Threads::nmethods_do(CodeBlobClosure* cf) {
3937   ALL_JAVA_THREADS(p) {
3938     p->nmethods_do(cf);
3939   }
3940   VMThread::vm_thread()->nmethods_do(cf);
3941 }
3942 
3943 void Threads::gc_epilogue() {
3944   ALL_JAVA_THREADS(p) {
3945     p->gc_epilogue();
3946   }
3947 }
3948 
3949 void Threads::gc_prologue() {
3950   ALL_JAVA_THREADS(p) {
3951     p->gc_prologue();
3952   }
3953 }
3954 
3955 void Threads::deoptimized_wrt_marked_nmethods() {
3956   ALL_JAVA_THREADS(p) {
3957     p->deoptimized_wrt_marked_nmethods();
3958   }
3959 }
3960 
3961 
3962 // Get count Java threads that are waiting to enter the specified monitor.
3963 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
3964   address monitor, bool doLock) {
3965   assert(doLock || SafepointSynchronize::is_at_safepoint(),
3966     "must grab Threads_lock or be at safepoint");
3967   GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
3968 
3969   int i = 0;
3970   {
3971     MutexLockerEx ml(doLock ? Threads_lock : NULL);
3972     ALL_JAVA_THREADS(p) {
3973       if (p->is_Compiler_thread()) continue;
3974 
3975       address pending = (address)p->current_pending_monitor();
3976       if (pending == monitor) {             // found a match
3977         if (i < count) result->append(p);   // save the first count matches
3978         i++;
3979       }
3980     }
3981   }
3982   return result;
3983 }
3984 
3985 
3986 JavaThread *Threads::owning_thread_from_monitor_owner(address owner, bool doLock) {
3987   assert(doLock ||
3988          Threads_lock->owned_by_self() ||
3989          SafepointSynchronize::is_at_safepoint(),
3990          "must grab Threads_lock or be at safepoint");
3991 
3992   // NULL owner means not locked so we can skip the search
3993   if (owner == NULL) return NULL;
3994 
3995   {
3996     MutexLockerEx ml(doLock ? Threads_lock : NULL);
3997     ALL_JAVA_THREADS(p) {
3998       // first, see if owner is the address of a Java thread
3999       if (owner == (address)p) return p;
4000     }
4001   }
4002   assert(UseHeavyMonitors == false, "Did not find owning Java thread with UseHeavyMonitors enabled");
4003   if (UseHeavyMonitors) return NULL;
4004 
4005   //
4006   // If we didn't find a matching Java thread and we didn't force use of
4007   // heavyweight monitors, then the owner is the stack address of the
4008   // Lock Word in the owning Java thread's stack.
4009   //
4010   JavaThread* the_owner = NULL;
4011   {
4012     MutexLockerEx ml(doLock ? Threads_lock : NULL);
4013     ALL_JAVA_THREADS(q) {
4014       if (q->is_lock_owned(owner)) {
4015         the_owner = q;
4016         break;
4017       }
4018     }
4019   }
4020   assert(the_owner != NULL, "Did not find owning Java thread for lock word address");
4021   return the_owner;
4022 }
4023 
4024 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4025 void Threads::print_on(outputStream* st, bool print_stacks, bool internal_format, bool print_concurrent_locks) {
4026   char buf[32];
4027   st->print_cr(os::local_time_string(buf, sizeof(buf)));
4028 
4029   st->print_cr("Full thread dump %s (%s %s):",
4030                 Abstract_VM_Version::vm_name(),
4031                 Abstract_VM_Version::vm_release(),
4032                 Abstract_VM_Version::vm_info_string()
4033                );
4034   st->cr();
4035 
4036 #ifndef SERIALGC
4037   // Dump concurrent locks
4038   ConcurrentLocksDump concurrent_locks;
4039   if (print_concurrent_locks) {
4040     concurrent_locks.dump_at_safepoint();
4041   }
4042 #endif // SERIALGC
4043 
4044   ALL_JAVA_THREADS(p) {
4045     ResourceMark rm;
4046     p->print_on(st);
4047     if (print_stacks) {
4048       if (internal_format) {
4049         p->trace_stack();
4050       } else {
4051         p->print_stack_on(st);
4052       }
4053     }
4054     st->cr();
4055 #ifndef SERIALGC
4056     if (print_concurrent_locks) {
4057       concurrent_locks.print_locks_on(p, st);
4058     }
4059 #endif // SERIALGC
4060   }
4061 
4062   VMThread::vm_thread()->print_on(st);
4063   st->cr();
4064   Universe::heap()->print_gc_threads_on(st);
4065   WatcherThread* wt = WatcherThread::watcher_thread();
4066   if (wt != NULL) wt->print_on(st);
4067   st->cr();
4068   CompileBroker::print_compiler_threads_on(st);
4069   st->flush();
4070 }
4071 
4072 // Threads::print_on_error() is called by fatal error handler. It's possible
4073 // that VM is not at safepoint and/or current thread is inside signal handler.
4074 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4075 // memory (even in resource area), it might deadlock the error handler.
4076 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, int buflen) {
4077   bool found_current = false;
4078   st->print_cr("Java Threads: ( => current thread )");
4079   ALL_JAVA_THREADS(thread) {
4080     bool is_current = (current == thread);
4081     found_current = found_current || is_current;
4082 
4083     st->print("%s", is_current ? "=>" : "  ");
4084 
4085     st->print(PTR_FORMAT, thread);
4086     st->print(" ");
4087     thread->print_on_error(st, buf, buflen);
4088     st->cr();
4089   }
4090   st->cr();
4091 
4092   st->print_cr("Other Threads:");
4093   if (VMThread::vm_thread()) {
4094     bool is_current = (current == VMThread::vm_thread());
4095     found_current = found_current || is_current;
4096     st->print("%s", current == VMThread::vm_thread() ? "=>" : "  ");
4097 
4098     st->print(PTR_FORMAT, VMThread::vm_thread());
4099     st->print(" ");
4100     VMThread::vm_thread()->print_on_error(st, buf, buflen);
4101     st->cr();
4102   }
4103   WatcherThread* wt = WatcherThread::watcher_thread();
4104   if (wt != NULL) {
4105     bool is_current = (current == wt);
4106     found_current = found_current || is_current;
4107     st->print("%s", is_current ? "=>" : "  ");
4108 
4109     st->print(PTR_FORMAT, wt);
4110     st->print(" ");
4111     wt->print_on_error(st, buf, buflen);
4112     st->cr();
4113   }
4114   if (!found_current) {
4115     st->cr();
4116     st->print("=>" PTR_FORMAT " (exited) ", current);
4117     current->print_on_error(st, buf, buflen);
4118     st->cr();
4119   }
4120 }
4121 
4122 // Internal SpinLock and Mutex
4123 // Based on ParkEvent
4124 
4125 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4126 //
4127 // We employ SpinLocks _only for low-contention, fixed-length
4128 // short-duration critical sections where we're concerned
4129 // about native mutex_t or HotSpot Mutex:: latency.
4130 // The mux construct provides a spin-then-block mutual exclusion
4131 // mechanism.
4132 //
4133 // Testing has shown that contention on the ListLock guarding gFreeList
4134 // is common.  If we implement ListLock as a simple SpinLock it's common
4135 // for the JVM to devolve to yielding with little progress.  This is true
4136 // despite the fact that the critical sections protected by ListLock are
4137 // extremely short.
4138 //
4139 // TODO-FIXME: ListLock should be of type SpinLock.
4140 // We should make this a 1st-class type, integrated into the lock
4141 // hierarchy as leaf-locks.  Critically, the SpinLock structure
4142 // should have sufficient padding to avoid false-sharing and excessive
4143 // cache-coherency traffic.
4144 
4145 
4146 typedef volatile int SpinLockT ;
4147 
4148 void Thread::SpinAcquire (volatile int * adr, const char * LockName) {
4149   if (Atomic::cmpxchg (1, adr, 0) == 0) {
4150      return ;   // normal fast-path return
4151   }
4152 
4153   // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4154   TEVENT (SpinAcquire - ctx) ;
4155   int ctr = 0 ;
4156   int Yields = 0 ;
4157   for (;;) {
4158      while (*adr != 0) {
4159         ++ctr ;
4160         if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4161            if (Yields > 5) {
4162              // Consider using a simple NakedSleep() instead.
4163              // Then SpinAcquire could be called by non-JVM threads
4164              Thread::current()->_ParkEvent->park(1) ;
4165            } else {
4166              os::NakedYield() ;
4167              ++Yields ;
4168            }
4169         } else {
4170            SpinPause() ;
4171         }
4172      }
4173      if (Atomic::cmpxchg (1, adr, 0) == 0) return ;
4174   }
4175 }
4176 
4177 void Thread::SpinRelease (volatile int * adr) {
4178   assert (*adr != 0, "invariant") ;
4179   OrderAccess::fence() ;      // guarantee at least release consistency.
4180   // Roach-motel semantics.
4181   // It's safe if subsequent LDs and STs float "up" into the critical section,
4182   // but prior LDs and STs within the critical section can't be allowed
4183   // to reorder or float past the ST that releases the lock.
4184   *adr = 0 ;
4185 }
4186 
4187 // muxAcquire and muxRelease:
4188 //
4189 // *  muxAcquire and muxRelease support a single-word lock-word construct.
4190 //    The LSB of the word is set IFF the lock is held.
4191 //    The remainder of the word points to the head of a singly-linked list
4192 //    of threads blocked on the lock.
4193 //
4194 // *  The current implementation of muxAcquire-muxRelease uses its own
4195 //    dedicated Thread._MuxEvent instance.  If we're interested in
4196 //    minimizing the peak number of extant ParkEvent instances then
4197 //    we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4198 //    as certain invariants were satisfied.  Specifically, care would need
4199 //    to be taken with regards to consuming unpark() "permits".
4200 //    A safe rule of thumb is that a thread would never call muxAcquire()
4201 //    if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4202 //    park().  Otherwise the _ParkEvent park() operation in muxAcquire() could
4203 //    consume an unpark() permit intended for monitorenter, for instance.
4204 //    One way around this would be to widen the restricted-range semaphore
4205 //    implemented in park().  Another alternative would be to provide
4206 //    multiple instances of the PlatformEvent() for each thread.  One
4207 //    instance would be dedicated to muxAcquire-muxRelease, for instance.
4208 //
4209 // *  Usage:
4210 //    -- Only as leaf locks
4211 //    -- for short-term locking only as muxAcquire does not perform
4212 //       thread state transitions.
4213 //
4214 // Alternatives:
4215 // *  We could implement muxAcquire and muxRelease with MCS or CLH locks
4216 //    but with parking or spin-then-park instead of pure spinning.
4217 // *  Use Taura-Oyama-Yonenzawa locks.
4218 // *  It's possible to construct a 1-0 lock if we encode the lockword as
4219 //    (List,LockByte).  Acquire will CAS the full lockword while Release
4220 //    will STB 0 into the LockByte.  The 1-0 scheme admits stranding, so
4221 //    acquiring threads use timers (ParkTimed) to detect and recover from
4222 //    the stranding window.  Thread/Node structures must be aligned on 256-byte
4223 //    boundaries by using placement-new.
4224 // *  Augment MCS with advisory back-link fields maintained with CAS().
4225 //    Pictorially:  LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4226 //    The validity of the backlinks must be ratified before we trust the value.
4227 //    If the backlinks are invalid the exiting thread must back-track through the
4228 //    the forward links, which are always trustworthy.
4229 // *  Add a successor indication.  The LockWord is currently encoded as
4230 //    (List, LOCKBIT:1).  We could also add a SUCCBIT or an explicit _succ variable
4231 //    to provide the usual futile-wakeup optimization.
4232 //    See RTStt for details.
4233 // *  Consider schedctl.sc_nopreempt to cover the critical section.
4234 //
4235 
4236 
4237 typedef volatile intptr_t MutexT ;      // Mux Lock-word
4238 enum MuxBits { LOCKBIT = 1 } ;
4239 
4240 void Thread::muxAcquire (volatile intptr_t * Lock, const char * LockName) {
4241   intptr_t w = Atomic::cmpxchg_ptr (LOCKBIT, Lock, 0) ;
4242   if (w == 0) return ;
4243   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4244      return ;
4245   }
4246 
4247   TEVENT (muxAcquire - Contention) ;
4248   ParkEvent * const Self = Thread::current()->_MuxEvent ;
4249   assert ((intptr_t(Self) & LOCKBIT) == 0, "invariant") ;
4250   for (;;) {
4251      int its = (os::is_MP() ? 100 : 0) + 1 ;
4252 
4253      // Optional spin phase: spin-then-park strategy
4254      while (--its >= 0) {
4255        w = *Lock ;
4256        if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4257           return ;
4258        }
4259      }
4260 
4261      Self->reset() ;
4262      Self->OnList = intptr_t(Lock) ;
4263      // The following fence() isn't _strictly necessary as the subsequent
4264      // CAS() both serializes execution and ratifies the fetched *Lock value.
4265      OrderAccess::fence();
4266      for (;;) {
4267         w = *Lock ;
4268         if ((w & LOCKBIT) == 0) {
4269             if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4270                 Self->OnList = 0 ;   // hygiene - allows stronger asserts
4271                 return ;
4272             }
4273             continue ;      // Interference -- *Lock changed -- Just retry
4274         }
4275         assert (w & LOCKBIT, "invariant") ;
4276         Self->ListNext = (ParkEvent *) (w & ~LOCKBIT );
4277         if (Atomic::cmpxchg_ptr (intptr_t(Self)|LOCKBIT, Lock, w) == w) break ;
4278      }
4279 
4280      while (Self->OnList != 0) {
4281         Self->park() ;
4282      }
4283   }
4284 }
4285 
4286 void Thread::muxAcquireW (volatile intptr_t * Lock, ParkEvent * ev) {
4287   intptr_t w = Atomic::cmpxchg_ptr (LOCKBIT, Lock, 0) ;
4288   if (w == 0) return ;
4289   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4290     return ;
4291   }
4292 
4293   TEVENT (muxAcquire - Contention) ;
4294   ParkEvent * ReleaseAfter = NULL ;
4295   if (ev == NULL) {
4296     ev = ReleaseAfter = ParkEvent::Allocate (NULL) ;
4297   }
4298   assert ((intptr_t(ev) & LOCKBIT) == 0, "invariant") ;
4299   for (;;) {
4300     guarantee (ev->OnList == 0, "invariant") ;
4301     int its = (os::is_MP() ? 100 : 0) + 1 ;
4302 
4303     // Optional spin phase: spin-then-park strategy
4304     while (--its >= 0) {
4305       w = *Lock ;
4306       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4307         if (ReleaseAfter != NULL) {
4308           ParkEvent::Release (ReleaseAfter) ;
4309         }
4310         return ;
4311       }
4312     }
4313 
4314     ev->reset() ;
4315     ev->OnList = intptr_t(Lock) ;
4316     // The following fence() isn't _strictly necessary as the subsequent
4317     // CAS() both serializes execution and ratifies the fetched *Lock value.
4318     OrderAccess::fence();
4319     for (;;) {
4320       w = *Lock ;
4321       if ((w & LOCKBIT) == 0) {
4322         if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4323           ev->OnList = 0 ;
4324           // We call ::Release while holding the outer lock, thus
4325           // artificially lengthening the critical section.
4326           // Consider deferring the ::Release() until the subsequent unlock(),
4327           // after we've dropped the outer lock.
4328           if (ReleaseAfter != NULL) {
4329             ParkEvent::Release (ReleaseAfter) ;
4330           }
4331           return ;
4332         }
4333         continue ;      // Interference -- *Lock changed -- Just retry
4334       }
4335       assert (w & LOCKBIT, "invariant") ;
4336       ev->ListNext = (ParkEvent *) (w & ~LOCKBIT );
4337       if (Atomic::cmpxchg_ptr (intptr_t(ev)|LOCKBIT, Lock, w) == w) break ;
4338     }
4339 
4340     while (ev->OnList != 0) {
4341       ev->park() ;
4342     }
4343   }
4344 }
4345 
4346 // Release() must extract a successor from the list and then wake that thread.
4347 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4348 // similar to that used by ParkEvent::Allocate() and ::Release().  DMR-based
4349 // Release() would :
4350 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4351 // (B) Extract a successor from the private list "in-hand"
4352 // (C) attempt to CAS() the residual back into *Lock over null.
4353 //     If there were any newly arrived threads and the CAS() would fail.
4354 //     In that case Release() would detach the RATs, re-merge the list in-hand
4355 //     with the RATs and repeat as needed.  Alternately, Release() might
4356 //     detach and extract a successor, but then pass the residual list to the wakee.
4357 //     The wakee would be responsible for reattaching and remerging before it
4358 //     competed for the lock.
4359 //
4360 // Both "pop" and DMR are immune from ABA corruption -- there can be
4361 // multiple concurrent pushers, but only one popper or detacher.
4362 // This implementation pops from the head of the list.  This is unfair,
4363 // but tends to provide excellent throughput as hot threads remain hot.
4364 // (We wake recently run threads first).
4365 
4366 void Thread::muxRelease (volatile intptr_t * Lock)  {
4367   for (;;) {
4368     const intptr_t w = Atomic::cmpxchg_ptr (0, Lock, LOCKBIT) ;
4369     assert (w & LOCKBIT, "invariant") ;
4370     if (w == LOCKBIT) return ;
4371     ParkEvent * List = (ParkEvent *) (w & ~LOCKBIT) ;
4372     assert (List != NULL, "invariant") ;
4373     assert (List->OnList == intptr_t(Lock), "invariant") ;
4374     ParkEvent * nxt = List->ListNext ;
4375 
4376     // The following CAS() releases the lock and pops the head element.
4377     if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4378       continue ;
4379     }
4380     List->OnList = 0 ;
4381     OrderAccess::fence() ;
4382     List->unpark () ;
4383     return ;
4384   }
4385 }
4386 
4387 
4388 void Threads::verify() {
4389   ALL_JAVA_THREADS(p) {
4390     p->verify();
4391   }
4392   VMThread* thread = VMThread::vm_thread();
4393   if (thread != NULL) thread->verify();
4394 }