1 /*
   2  * Copyright (c) 1997, 2018, 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 "jvm.h"
  27 #include "classfile/classLoader.hpp"
  28 #include "classfile/javaClasses.hpp"
  29 #include "classfile/moduleEntry.hpp"
  30 #include "classfile/systemDictionary.hpp"
  31 #include "classfile/vmSymbols.hpp"
  32 #include "code/codeCache.hpp"
  33 #include "code/scopeDesc.hpp"
  34 #include "compiler/compileBroker.hpp"
  35 #include "compiler/compileTask.hpp"
  36 #include "gc/shared/gcId.hpp"
  37 #include "gc/shared/gcLocker.inline.hpp"
  38 #include "gc/shared/workgroup.hpp"
  39 #include "interpreter/interpreter.hpp"
  40 #include "interpreter/linkResolver.hpp"
  41 #include "interpreter/oopMapCache.hpp"
  42 #include "jvmtifiles/jvmtiEnv.hpp"
  43 #include "logging/log.hpp"
  44 #include "logging/logConfiguration.hpp"
  45 #include "logging/logStream.hpp"
  46 #include "memory/allocation.inline.hpp"
  47 #include "memory/metaspaceShared.hpp"
  48 #include "memory/oopFactory.hpp"
  49 #include "memory/resourceArea.hpp"
  50 #include "memory/universe.hpp"
  51 #include "oops/access.inline.hpp"
  52 #include "oops/instanceKlass.hpp"
  53 #include "oops/objArrayOop.hpp"
  54 #include "oops/oop.inline.hpp"
  55 #include "oops/symbol.hpp"
  56 #include "oops/typeArrayOop.inline.hpp"
  57 #include "oops/verifyOopClosure.hpp"
  58 #include "prims/jvm_misc.hpp"
  59 #include "prims/jvmtiExport.hpp"
  60 #include "prims/jvmtiThreadState.hpp"
  61 #include "prims/privilegedStack.hpp"
  62 #include "runtime/arguments.hpp"
  63 #include "runtime/atomic.hpp"
  64 #include "runtime/biasedLocking.hpp"
  65 #include "runtime/commandLineFlagConstraintList.hpp"
  66 #include "runtime/commandLineFlagWriteableList.hpp"
  67 #include "runtime/commandLineFlagRangeList.hpp"
  68 #include "runtime/deoptimization.hpp"
  69 #include "runtime/frame.inline.hpp"
  70 #include "runtime/globals.hpp"
  71 #include "runtime/handshake.hpp"
  72 #include "runtime/init.hpp"
  73 #include "runtime/interfaceSupport.inline.hpp"
  74 #include "runtime/java.hpp"
  75 #include "runtime/javaCalls.hpp"
  76 #include "runtime/jniHandles.inline.hpp"
  77 #include "runtime/jniPeriodicChecker.hpp"
  78 #include "runtime/memprofiler.hpp"
  79 #include "runtime/mutexLocker.hpp"
  80 #include "runtime/objectMonitor.hpp"
  81 #include "runtime/orderAccess.inline.hpp"
  82 #include "runtime/osThread.hpp"
  83 #include "runtime/prefetch.inline.hpp"
  84 #include "runtime/safepoint.hpp"
  85 #include "runtime/safepointMechanism.inline.hpp"
  86 #include "runtime/sharedRuntime.hpp"
  87 #include "runtime/statSampler.hpp"
  88 #include "runtime/stubRoutines.hpp"
  89 #include "runtime/sweeper.hpp"
  90 #include "runtime/task.hpp"
  91 #include "runtime/thread.inline.hpp"
  92 #include "runtime/threadCritical.hpp"
  93 #include "runtime/threadSMR.inline.hpp"
  94 #include "runtime/timer.hpp"
  95 #include "runtime/timerTrace.hpp"
  96 #include "runtime/vframe.inline.hpp"
  97 #include "runtime/vframeArray.hpp"
  98 #include "runtime/vframe_hp.hpp"
  99 #include "runtime/vmThread.hpp"
 100 #include "runtime/vm_operations.hpp"
 101 #include "runtime/vm_version.hpp"
 102 #include "services/attachListener.hpp"
 103 #include "services/management.hpp"
 104 #include "services/memTracker.hpp"
 105 #include "services/threadService.hpp"
 106 #include "trace/traceMacros.hpp"
 107 #include "trace/tracing.hpp"
 108 #include "trace/tracingExport.hpp"
 109 #include "utilities/align.hpp"
 110 #include "utilities/copy.hpp"
 111 #include "utilities/defaultStream.hpp"
 112 #include "utilities/dtrace.hpp"
 113 #include "utilities/events.hpp"
 114 #include "utilities/macros.hpp"
 115 #include "utilities/preserveException.hpp"
 116 #include "utilities/vmError.hpp"
 117 #if INCLUDE_ALL_GCS
 118 #include "gc/cms/concurrentMarkSweepThread.hpp"
 119 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
 120 #include "gc/parallel/pcTasks.hpp"
 121 #endif // INCLUDE_ALL_GCS
 122 #if INCLUDE_JVMCI
 123 #include "jvmci/jvmciCompiler.hpp"
 124 #include "jvmci/jvmciRuntime.hpp"
 125 #include "logging/logHandle.hpp"
 126 #endif
 127 #ifdef COMPILER1
 128 #include "c1/c1_Compiler.hpp"
 129 #endif
 130 #ifdef COMPILER2
 131 #include "opto/c2compiler.hpp"
 132 #include "opto/idealGraphPrinter.hpp"
 133 #endif
 134 #if INCLUDE_RTM_OPT
 135 #include "runtime/rtmLocking.hpp"
 136 #endif
 137 
 138 // Initialization after module runtime initialization
 139 void universe_post_module_init();  // must happen after call_initPhase2
 140 
 141 #ifdef DTRACE_ENABLED
 142 
 143 // Only bother with this argument setup if dtrace is available
 144 
 145   #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
 146   #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
 147 
 148   #define DTRACE_THREAD_PROBE(probe, javathread)                           \
 149     {                                                                      \
 150       ResourceMark rm(this);                                               \
 151       int len = 0;                                                         \
 152       const char* name = (javathread)->get_thread_name();                  \
 153       len = strlen(name);                                                  \
 154       HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */               \
 155         (char *) name, len,                                                \
 156         java_lang_Thread::thread_id((javathread)->threadObj()),            \
 157         (uintptr_t) (javathread)->osthread()->thread_id(),                 \
 158         java_lang_Thread::is_daemon((javathread)->threadObj()));           \
 159     }
 160 
 161 #else //  ndef DTRACE_ENABLED
 162 
 163   #define DTRACE_THREAD_PROBE(probe, javathread)
 164 
 165 #endif // ndef DTRACE_ENABLED
 166 
 167 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 168 // Current thread is maintained as a thread-local variable
 169 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
 170 #endif
 171 // Class hierarchy
 172 // - Thread
 173 //   - VMThread
 174 //   - WatcherThread
 175 //   - ConcurrentMarkSweepThread
 176 //   - JavaThread
 177 //     - CompilerThread
 178 
 179 // ======= Thread ========
 180 // Support for forcing alignment of thread objects for biased locking
 181 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
 182   if (UseBiasedLocking) {
 183     const int alignment = markOopDesc::biased_lock_alignment;
 184     size_t aligned_size = size + (alignment - sizeof(intptr_t));
 185     void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
 186                                           : AllocateHeap(aligned_size, flags, CURRENT_PC,
 187                                                          AllocFailStrategy::RETURN_NULL);
 188     void* aligned_addr     = align_up(real_malloc_addr, alignment);
 189     assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
 190            ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
 191            "JavaThread alignment code overflowed allocated storage");
 192     if (aligned_addr != real_malloc_addr) {
 193       log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
 194                               p2i(real_malloc_addr),
 195                               p2i(aligned_addr));
 196     }
 197     ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
 198     return aligned_addr;
 199   } else {
 200     return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
 201                        : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
 202   }
 203 }
 204 
 205 void Thread::operator delete(void* p) {
 206   if (UseBiasedLocking) {
 207     FreeHeap(((Thread*) p)->_real_malloc_address);
 208   } else {
 209     FreeHeap(p);
 210   }
 211 }
 212 
 213 void JavaThread::smr_delete() {
 214   if (_on_thread_list) {
 215     ThreadsSMRSupport::smr_delete(this);
 216   } else {
 217     delete this;
 218   }
 219 }
 220 
 221 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
 222 // JavaThread
 223 
 224 
 225 Thread::Thread() {
 226   // stack and get_thread
 227   set_stack_base(NULL);
 228   set_stack_size(0);
 229   set_self_raw_id(0);
 230   set_lgrp_id(-1);
 231   DEBUG_ONLY(clear_suspendible_thread();)
 232 
 233   // allocated data structures
 234   set_osthread(NULL);
 235   set_resource_area(new (mtThread)ResourceArea());
 236   DEBUG_ONLY(_current_resource_mark = NULL;)
 237   set_handle_area(new (mtThread) HandleArea(NULL));
 238   set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
 239   set_active_handles(NULL);
 240   set_free_handle_block(NULL);
 241   set_last_handle_mark(NULL);
 242 
 243   // This initial value ==> never claimed.
 244   _oops_do_parity = 0;
 245   _threads_hazard_ptr = NULL;
 246   _nested_threads_hazard_ptr = NULL;
 247   _nested_threads_hazard_ptr_cnt = 0;
 248 
 249   // the handle mark links itself to last_handle_mark
 250   new HandleMark(this);
 251 
 252   // plain initialization
 253   debug_only(_owned_locks = NULL;)
 254   debug_only(_allow_allocation_count = 0;)
 255   NOT_PRODUCT(_allow_safepoint_count = 0;)
 256   NOT_PRODUCT(_skip_gcalot = false;)
 257   _jvmti_env_iteration_count = 0;
 258   set_allocated_bytes(0);
 259   _vm_operation_started_count = 0;
 260   _vm_operation_completed_count = 0;
 261   _current_pending_monitor = NULL;
 262   _current_pending_monitor_is_from_java = true;
 263   _current_waiting_monitor = NULL;
 264   _num_nested_signal = 0;
 265   omFreeList = NULL;
 266   omFreeCount = 0;
 267   omFreeProvision = 32;
 268   omInUseList = NULL;
 269   omInUseCount = 0;
 270 
 271 #ifdef ASSERT
 272   _visited_for_critical_count = false;
 273 #endif
 274 
 275   _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
 276                          Monitor::_safepoint_check_sometimes);
 277   _suspend_flags = 0;
 278 
 279   // thread-specific hashCode stream generator state - Marsaglia shift-xor form
 280   _hashStateX = os::random();
 281   _hashStateY = 842502087;
 282   _hashStateZ = 0x8767;    // (int)(3579807591LL & 0xffff) ;
 283   _hashStateW = 273326509;
 284 
 285   _OnTrap   = 0;
 286   _schedctl = NULL;
 287   _Stalled  = 0;
 288   _TypeTag  = 0x2BAD;
 289 
 290   // Many of the following fields are effectively final - immutable
 291   // Note that nascent threads can't use the Native Monitor-Mutex
 292   // construct until the _MutexEvent is initialized ...
 293   // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
 294   // we might instead use a stack of ParkEvents that we could provision on-demand.
 295   // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
 296   // and ::Release()
 297   _ParkEvent   = ParkEvent::Allocate(this);
 298   _SleepEvent  = ParkEvent::Allocate(this);
 299   _MutexEvent  = ParkEvent::Allocate(this);
 300   _MuxEvent    = ParkEvent::Allocate(this);
 301 
 302 #ifdef CHECK_UNHANDLED_OOPS
 303   if (CheckUnhandledOops) {
 304     _unhandled_oops = new UnhandledOops(this);
 305   }
 306 #endif // CHECK_UNHANDLED_OOPS
 307 #ifdef ASSERT
 308   if (UseBiasedLocking) {
 309     assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
 310     assert(this == _real_malloc_address ||
 311            this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment),
 312            "bug in forced alignment of thread objects");
 313   }
 314 #endif // ASSERT
 315 }
 316 
 317 void Thread::initialize_thread_current() {
 318 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 319   assert(_thr_current == NULL, "Thread::current already initialized");
 320   _thr_current = this;
 321 #endif
 322   assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
 323   ThreadLocalStorage::set_thread(this);
 324   assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
 325 }
 326 
 327 void Thread::clear_thread_current() {
 328   assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
 329 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 330   _thr_current = NULL;
 331 #endif
 332   ThreadLocalStorage::set_thread(NULL);
 333 }
 334 
 335 void Thread::record_stack_base_and_size() {
 336   set_stack_base(os::current_stack_base());
 337   set_stack_size(os::current_stack_size());
 338   // CR 7190089: on Solaris, primordial thread's stack is adjusted
 339   // in initialize_thread(). Without the adjustment, stack size is
 340   // incorrect if stack is set to unlimited (ulimit -s unlimited).
 341   // So far, only Solaris has real implementation of initialize_thread().
 342   //
 343   // set up any platform-specific state.
 344   os::initialize_thread(this);
 345 
 346   // Set stack limits after thread is initialized.
 347   if (is_Java_thread()) {
 348     ((JavaThread*) this)->set_stack_overflow_limit();
 349     ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
 350   }
 351 #if INCLUDE_NMT
 352   // record thread's native stack, stack grows downward
 353   MemTracker::record_thread_stack(stack_end(), stack_size());
 354 #endif // INCLUDE_NMT
 355   log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
 356     PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
 357     os::current_thread_id(), p2i(stack_base() - stack_size()),
 358     p2i(stack_base()), stack_size()/1024);
 359 }
 360 
 361 
 362 Thread::~Thread() {
 363   EVENT_THREAD_DESTRUCT(this);
 364 
 365   // stack_base can be NULL if the thread is never started or exited before
 366   // record_stack_base_and_size called. Although, we would like to ensure
 367   // that all started threads do call record_stack_base_and_size(), there is
 368   // not proper way to enforce that.
 369 #if INCLUDE_NMT
 370   if (_stack_base != NULL) {
 371     MemTracker::release_thread_stack(stack_end(), stack_size());
 372 #ifdef ASSERT
 373     set_stack_base(NULL);
 374 #endif
 375   }
 376 #endif // INCLUDE_NMT
 377 
 378   // deallocate data structures
 379   delete resource_area();
 380   // since the handle marks are using the handle area, we have to deallocated the root
 381   // handle mark before deallocating the thread's handle area,
 382   assert(last_handle_mark() != NULL, "check we have an element");
 383   delete last_handle_mark();
 384   assert(last_handle_mark() == NULL, "check we have reached the end");
 385 
 386   // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
 387   // We NULL out the fields for good hygiene.
 388   ParkEvent::Release(_ParkEvent); _ParkEvent   = NULL;
 389   ParkEvent::Release(_SleepEvent); _SleepEvent  = NULL;
 390   ParkEvent::Release(_MutexEvent); _MutexEvent  = NULL;
 391   ParkEvent::Release(_MuxEvent); _MuxEvent    = NULL;
 392 
 393   delete handle_area();
 394   delete metadata_handles();
 395 
 396   // SR_handler uses this as a termination indicator -
 397   // needs to happen before os::free_thread()
 398   delete _SR_lock;
 399   _SR_lock = NULL;
 400 
 401   // osthread() can be NULL, if creation of thread failed.
 402   if (osthread() != NULL) os::free_thread(osthread());
 403 
 404   // clear Thread::current if thread is deleting itself.
 405   // Needed to ensure JNI correctly detects non-attached threads.
 406   if (this == Thread::current()) {
 407     clear_thread_current();
 408   }
 409 
 410   CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
 411 }
 412 
 413 // NOTE: dummy function for assertion purpose.
 414 void Thread::run() {
 415   ShouldNotReachHere();
 416 }
 417 
 418 #ifdef ASSERT
 419 // A JavaThread is considered "dangling" if it is not the current
 420 // thread, has been added the Threads list, the system is not at a
 421 // safepoint and the Thread is not "protected".
 422 //
 423 void Thread::check_for_dangling_thread_pointer(Thread *thread) {
 424   assert(!thread->is_Java_thread() || Thread::current() == thread ||
 425          !((JavaThread *) thread)->on_thread_list() ||
 426          SafepointSynchronize::is_at_safepoint() ||
 427          ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread),
 428          "possibility of dangling Thread pointer");
 429 }
 430 #endif
 431 
 432 ThreadPriority Thread::get_priority(const Thread* const thread) {
 433   ThreadPriority priority;
 434   // Can return an error!
 435   (void)os::get_priority(thread, priority);
 436   assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
 437   return priority;
 438 }
 439 
 440 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
 441   debug_only(check_for_dangling_thread_pointer(thread);)
 442   // Can return an error!
 443   (void)os::set_priority(thread, priority);
 444 }
 445 
 446 
 447 void Thread::start(Thread* thread) {
 448   // Start is different from resume in that its safety is guaranteed by context or
 449   // being called from a Java method synchronized on the Thread object.
 450   if (!DisableStartThread) {
 451     if (thread->is_Java_thread()) {
 452       // Initialize the thread state to RUNNABLE before starting this thread.
 453       // Can not set it after the thread started because we do not know the
 454       // exact thread state at that time. It could be in MONITOR_WAIT or
 455       // in SLEEPING or some other state.
 456       java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
 457                                           java_lang_Thread::RUNNABLE);
 458     }
 459     os::start_thread(thread);
 460   }
 461 }
 462 
 463 // Enqueue a VM_Operation to do the job for us - sometime later
 464 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
 465   VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
 466   VMThread::execute(vm_stop);
 467 }
 468 
 469 
 470 // Check if an external suspend request has completed (or has been
 471 // cancelled). Returns true if the thread is externally suspended and
 472 // false otherwise.
 473 //
 474 // The bits parameter returns information about the code path through
 475 // the routine. Useful for debugging:
 476 //
 477 // set in is_ext_suspend_completed():
 478 // 0x00000001 - routine was entered
 479 // 0x00000010 - routine return false at end
 480 // 0x00000100 - thread exited (return false)
 481 // 0x00000200 - suspend request cancelled (return false)
 482 // 0x00000400 - thread suspended (return true)
 483 // 0x00001000 - thread is in a suspend equivalent state (return true)
 484 // 0x00002000 - thread is native and walkable (return true)
 485 // 0x00004000 - thread is native_trans and walkable (needed retry)
 486 //
 487 // set in wait_for_ext_suspend_completion():
 488 // 0x00010000 - routine was entered
 489 // 0x00020000 - suspend request cancelled before loop (return false)
 490 // 0x00040000 - thread suspended before loop (return true)
 491 // 0x00080000 - suspend request cancelled in loop (return false)
 492 // 0x00100000 - thread suspended in loop (return true)
 493 // 0x00200000 - suspend not completed during retry loop (return false)
 494 
 495 // Helper class for tracing suspend wait debug bits.
 496 //
 497 // 0x00000100 indicates that the target thread exited before it could
 498 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
 499 // 0x00080000 each indicate a cancelled suspend request so they don't
 500 // count as wait failures either.
 501 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
 502 
 503 class TraceSuspendDebugBits : public StackObj {
 504  private:
 505   JavaThread * jt;
 506   bool         is_wait;
 507   bool         called_by_wait;  // meaningful when !is_wait
 508   uint32_t *   bits;
 509 
 510  public:
 511   TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
 512                         uint32_t *_bits) {
 513     jt             = _jt;
 514     is_wait        = _is_wait;
 515     called_by_wait = _called_by_wait;
 516     bits           = _bits;
 517   }
 518 
 519   ~TraceSuspendDebugBits() {
 520     if (!is_wait) {
 521 #if 1
 522       // By default, don't trace bits for is_ext_suspend_completed() calls.
 523       // That trace is very chatty.
 524       return;
 525 #else
 526       if (!called_by_wait) {
 527         // If tracing for is_ext_suspend_completed() is enabled, then only
 528         // trace calls to it from wait_for_ext_suspend_completion()
 529         return;
 530       }
 531 #endif
 532     }
 533 
 534     if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
 535       if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
 536         MutexLocker ml(Threads_lock);  // needed for get_thread_name()
 537         ResourceMark rm;
 538 
 539         tty->print_cr(
 540                       "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
 541                       jt->get_thread_name(), *bits);
 542 
 543         guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
 544       }
 545     }
 546   }
 547 };
 548 #undef DEBUG_FALSE_BITS
 549 
 550 
 551 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
 552                                           uint32_t *bits) {
 553   TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
 554 
 555   bool did_trans_retry = false;  // only do thread_in_native_trans retry once
 556   bool do_trans_retry;           // flag to force the retry
 557 
 558   *bits |= 0x00000001;
 559 
 560   do {
 561     do_trans_retry = false;
 562 
 563     if (is_exiting()) {
 564       // Thread is in the process of exiting. This is always checked
 565       // first to reduce the risk of dereferencing a freed JavaThread.
 566       *bits |= 0x00000100;
 567       return false;
 568     }
 569 
 570     if (!is_external_suspend()) {
 571       // Suspend request is cancelled. This is always checked before
 572       // is_ext_suspended() to reduce the risk of a rogue resume
 573       // confusing the thread that made the suspend request.
 574       *bits |= 0x00000200;
 575       return false;
 576     }
 577 
 578     if (is_ext_suspended()) {
 579       // thread is suspended
 580       *bits |= 0x00000400;
 581       return true;
 582     }
 583 
 584     // Now that we no longer do hard suspends of threads running
 585     // native code, the target thread can be changing thread state
 586     // while we are in this routine:
 587     //
 588     //   _thread_in_native -> _thread_in_native_trans -> _thread_blocked
 589     //
 590     // We save a copy of the thread state as observed at this moment
 591     // and make our decision about suspend completeness based on the
 592     // copy. This closes the race where the thread state is seen as
 593     // _thread_in_native_trans in the if-thread_blocked check, but is
 594     // seen as _thread_blocked in if-thread_in_native_trans check.
 595     JavaThreadState save_state = thread_state();
 596 
 597     if (save_state == _thread_blocked && is_suspend_equivalent()) {
 598       // If the thread's state is _thread_blocked and this blocking
 599       // condition is known to be equivalent to a suspend, then we can
 600       // consider the thread to be externally suspended. This means that
 601       // the code that sets _thread_blocked has been modified to do
 602       // self-suspension if the blocking condition releases. We also
 603       // used to check for CONDVAR_WAIT here, but that is now covered by
 604       // the _thread_blocked with self-suspension check.
 605       //
 606       // Return true since we wouldn't be here unless there was still an
 607       // external suspend request.
 608       *bits |= 0x00001000;
 609       return true;
 610     } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
 611       // Threads running native code will self-suspend on native==>VM/Java
 612       // transitions. If its stack is walkable (should always be the case
 613       // unless this function is called before the actual java_suspend()
 614       // call), then the wait is done.
 615       *bits |= 0x00002000;
 616       return true;
 617     } else if (!called_by_wait && !did_trans_retry &&
 618                save_state == _thread_in_native_trans &&
 619                frame_anchor()->walkable()) {
 620       // The thread is transitioning from thread_in_native to another
 621       // thread state. check_safepoint_and_suspend_for_native_trans()
 622       // will force the thread to self-suspend. If it hasn't gotten
 623       // there yet we may have caught the thread in-between the native
 624       // code check above and the self-suspend. Lucky us. If we were
 625       // called by wait_for_ext_suspend_completion(), then it
 626       // will be doing the retries so we don't have to.
 627       //
 628       // Since we use the saved thread state in the if-statement above,
 629       // there is a chance that the thread has already transitioned to
 630       // _thread_blocked by the time we get here. In that case, we will
 631       // make a single unnecessary pass through the logic below. This
 632       // doesn't hurt anything since we still do the trans retry.
 633 
 634       *bits |= 0x00004000;
 635 
 636       // Once the thread leaves thread_in_native_trans for another
 637       // thread state, we break out of this retry loop. We shouldn't
 638       // need this flag to prevent us from getting back here, but
 639       // sometimes paranoia is good.
 640       did_trans_retry = true;
 641 
 642       // We wait for the thread to transition to a more usable state.
 643       for (int i = 1; i <= SuspendRetryCount; i++) {
 644         // We used to do an "os::yield_all(i)" call here with the intention
 645         // that yielding would increase on each retry. However, the parameter
 646         // is ignored on Linux which means the yield didn't scale up. Waiting
 647         // on the SR_lock below provides a much more predictable scale up for
 648         // the delay. It also provides a simple/direct point to check for any
 649         // safepoint requests from the VMThread
 650 
 651         // temporarily drops SR_lock while doing wait with safepoint check
 652         // (if we're a JavaThread - the WatcherThread can also call this)
 653         // and increase delay with each retry
 654         SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 655 
 656         // check the actual thread state instead of what we saved above
 657         if (thread_state() != _thread_in_native_trans) {
 658           // the thread has transitioned to another thread state so
 659           // try all the checks (except this one) one more time.
 660           do_trans_retry = true;
 661           break;
 662         }
 663       } // end retry loop
 664 
 665 
 666     }
 667   } while (do_trans_retry);
 668 
 669   *bits |= 0x00000010;
 670   return false;
 671 }
 672 
 673 // Wait for an external suspend request to complete (or be cancelled).
 674 // Returns true if the thread is externally suspended and false otherwise.
 675 //
 676 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
 677                                                  uint32_t *bits) {
 678   TraceSuspendDebugBits tsdb(this, true /* is_wait */,
 679                              false /* !called_by_wait */, bits);
 680 
 681   // local flag copies to minimize SR_lock hold time
 682   bool is_suspended;
 683   bool pending;
 684   uint32_t reset_bits;
 685 
 686   // set a marker so is_ext_suspend_completed() knows we are the caller
 687   *bits |= 0x00010000;
 688 
 689   // We use reset_bits to reinitialize the bits value at the top of
 690   // each retry loop. This allows the caller to make use of any
 691   // unused bits for their own marking purposes.
 692   reset_bits = *bits;
 693 
 694   {
 695     MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
 696     is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 697                                             delay, bits);
 698     pending = is_external_suspend();
 699   }
 700   // must release SR_lock to allow suspension to complete
 701 
 702   if (!pending) {
 703     // A cancelled suspend request is the only false return from
 704     // is_ext_suspend_completed() that keeps us from entering the
 705     // retry loop.
 706     *bits |= 0x00020000;
 707     return false;
 708   }
 709 
 710   if (is_suspended) {
 711     *bits |= 0x00040000;
 712     return true;
 713   }
 714 
 715   for (int i = 1; i <= retries; i++) {
 716     *bits = reset_bits;  // reinit to only track last retry
 717 
 718     // We used to do an "os::yield_all(i)" call here with the intention
 719     // that yielding would increase on each retry. However, the parameter
 720     // is ignored on Linux which means the yield didn't scale up. Waiting
 721     // on the SR_lock below provides a much more predictable scale up for
 722     // the delay. It also provides a simple/direct point to check for any
 723     // safepoint requests from the VMThread
 724 
 725     {
 726       MutexLocker ml(SR_lock());
 727       // wait with safepoint check (if we're a JavaThread - the WatcherThread
 728       // can also call this)  and increase delay with each retry
 729       SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 730 
 731       is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 732                                               delay, bits);
 733 
 734       // It is possible for the external suspend request to be cancelled
 735       // (by a resume) before the actual suspend operation is completed.
 736       // Refresh our local copy to see if we still need to wait.
 737       pending = is_external_suspend();
 738     }
 739 
 740     if (!pending) {
 741       // A cancelled suspend request is the only false return from
 742       // is_ext_suspend_completed() that keeps us from staying in the
 743       // retry loop.
 744       *bits |= 0x00080000;
 745       return false;
 746     }
 747 
 748     if (is_suspended) {
 749       *bits |= 0x00100000;
 750       return true;
 751     }
 752   } // end retry loop
 753 
 754   // thread did not suspend after all our retries
 755   *bits |= 0x00200000;
 756   return false;
 757 }
 758 
 759 // Called from API entry points which perform stack walking. If the
 760 // associated JavaThread is the current thread, then wait_for_suspend
 761 // is not used. Otherwise, it determines if we should wait for the
 762 // "other" thread to complete external suspension. (NOTE: in future
 763 // releases the suspension mechanism should be reimplemented so this
 764 // is not necessary.)
 765 //
 766 bool
 767 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) {
 768   if (this != JavaThread::current()) {
 769     // "other" threads require special handling.
 770     if (wait_for_suspend) {
 771       // We are allowed to wait for the external suspend to complete
 772       // so give the other thread a chance to get suspended.
 773       if (!wait_for_ext_suspend_completion(SuspendRetryCount,
 774                                            SuspendRetryDelay, bits)) {
 775         // Didn't make it so let the caller know.
 776         return false;
 777       }
 778     }
 779     // We aren't allowed to wait for the external suspend to complete
 780     // so if the other thread isn't externally suspended we need to
 781     // let the caller know.
 782     else if (!is_ext_suspend_completed_with_lock(bits)) {
 783       return false;
 784     }
 785   }
 786 
 787   return true;
 788 }
 789 
 790 #ifndef PRODUCT
 791 void JavaThread::record_jump(address target, address instr, const char* file,
 792                              int line) {
 793 
 794   // This should not need to be atomic as the only way for simultaneous
 795   // updates is via interrupts. Even then this should be rare or non-existent
 796   // and we don't care that much anyway.
 797 
 798   int index = _jmp_ring_index;
 799   _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
 800   _jmp_ring[index]._target = (intptr_t) target;
 801   _jmp_ring[index]._instruction = (intptr_t) instr;
 802   _jmp_ring[index]._file = file;
 803   _jmp_ring[index]._line = line;
 804 }
 805 #endif // PRODUCT
 806 
 807 void Thread::interrupt(Thread* thread) {
 808   debug_only(check_for_dangling_thread_pointer(thread);)
 809   os::interrupt(thread);
 810 }
 811 
 812 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
 813   debug_only(check_for_dangling_thread_pointer(thread);)
 814   // Note:  If clear_interrupted==false, this simply fetches and
 815   // returns the value of the field osthread()->interrupted().
 816   return os::is_interrupted(thread, clear_interrupted);
 817 }
 818 
 819 
 820 // GC Support
 821 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
 822   int thread_parity = _oops_do_parity;
 823   if (thread_parity != strong_roots_parity) {
 824     jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
 825     if (res == thread_parity) {
 826       return true;
 827     } else {
 828       guarantee(res == strong_roots_parity, "Or else what?");
 829       return false;
 830     }
 831   }
 832   return false;
 833 }
 834 
 835 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
 836   active_handles()->oops_do(f);
 837   // Do oop for ThreadShadow
 838   f->do_oop((oop*)&_pending_exception);
 839   handle_area()->oops_do(f);
 840 
 841   if (MonitorInUseLists) {
 842     // When using thread local monitor lists, we scan them here,
 843     // and the remaining global monitors in ObjectSynchronizer::oops_do().
 844     ObjectSynchronizer::thread_local_used_oops_do(this, f);
 845   }
 846 }
 847 
 848 void Thread::metadata_handles_do(void f(Metadata*)) {
 849   // Only walk the Handles in Thread.
 850   if (metadata_handles() != NULL) {
 851     for (int i = 0; i< metadata_handles()->length(); i++) {
 852       f(metadata_handles()->at(i));
 853     }
 854   }
 855 }
 856 
 857 void Thread::print_on(outputStream* st) const {
 858   // get_priority assumes osthread initialized
 859   if (osthread() != NULL) {
 860     int os_prio;
 861     if (os::get_native_priority(this, &os_prio) == OS_OK) {
 862       st->print("os_prio=%d ", os_prio);
 863     }
 864     st->print("tid=" INTPTR_FORMAT " ", p2i(this));
 865     osthread()->print_on(st);
 866   }
 867   if (_threads_hazard_ptr != NULL) {
 868     st->print("_threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr));
 869   }
 870   if (_nested_threads_hazard_ptr != NULL) {
 871     print_nested_threads_hazard_ptrs_on(st);
 872   }
 873   st->print(" ");
 874   debug_only(if (WizardMode) print_owned_locks_on(st);)
 875 }
 876 
 877 void Thread::print_nested_threads_hazard_ptrs_on(outputStream* st) const {
 878   assert(_nested_threads_hazard_ptr != NULL, "must be set to print");
 879 
 880   if (EnableThreadSMRStatistics) {
 881     st->print(", _nested_threads_hazard_ptr_cnt=%u", _nested_threads_hazard_ptr_cnt);
 882   }
 883   st->print(", _nested_threads_hazard_ptrs=");
 884   for (NestedThreadsList* node = _nested_threads_hazard_ptr; node != NULL;
 885        node = node->next()) {
 886     if (node != _nested_threads_hazard_ptr) {
 887       // First node does not need a comma-space separator.
 888       st->print(", ");
 889     }
 890     st->print(INTPTR_FORMAT, p2i(node->t_list()));
 891   }
 892 }
 893 
 894 // Thread::print_on_error() is called by fatal error handler. Don't use
 895 // any lock or allocate memory.
 896 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
 897   assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
 898 
 899   if (is_VM_thread())                 { st->print("VMThread"); }
 900   else if (is_GC_task_thread())       { st->print("GCTaskThread"); }
 901   else if (is_Watcher_thread())       { st->print("WatcherThread"); }
 902   else if (is_ConcurrentGC_thread())  { st->print("ConcurrentGCThread"); }
 903   else                                { st->print("Thread"); }
 904 
 905   if (is_Named_thread()) {
 906     st->print(" \"%s\"", name());
 907   }
 908 
 909   st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
 910             p2i(stack_end()), p2i(stack_base()));
 911 
 912   if (osthread()) {
 913     st->print(" [id=%d]", osthread()->thread_id());
 914   }
 915 
 916   if (_threads_hazard_ptr != NULL) {
 917     st->print(" _threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr));
 918   }
 919   if (_nested_threads_hazard_ptr != NULL) {
 920     print_nested_threads_hazard_ptrs_on(st);
 921   }
 922 }
 923 
 924 void Thread::print_value_on(outputStream* st) const {
 925   if (is_Named_thread()) {
 926     st->print(" \"%s\" ", name());
 927   }
 928   st->print(INTPTR_FORMAT, p2i(this));   // print address
 929 }
 930 
 931 #ifdef ASSERT
 932 void Thread::print_owned_locks_on(outputStream* st) const {
 933   Monitor *cur = _owned_locks;
 934   if (cur == NULL) {
 935     st->print(" (no locks) ");
 936   } else {
 937     st->print_cr(" Locks owned:");
 938     while (cur) {
 939       cur->print_on(st);
 940       cur = cur->next();
 941     }
 942   }
 943 }
 944 
 945 static int ref_use_count  = 0;
 946 
 947 bool Thread::owns_locks_but_compiled_lock() const {
 948   for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 949     if (cur != Compile_lock) return true;
 950   }
 951   return false;
 952 }
 953 
 954 
 955 #endif
 956 
 957 #ifndef PRODUCT
 958 
 959 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially
 960 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that
 961 // no threads which allow_vm_block's are held
 962 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
 963   // Check if current thread is allowed to block at a safepoint
 964   if (!(_allow_safepoint_count == 0)) {
 965     fatal("Possible safepoint reached by thread that does not allow it");
 966   }
 967   if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
 968     fatal("LEAF method calling lock?");
 969   }
 970 
 971 #ifdef ASSERT
 972   if (potential_vm_operation && is_Java_thread()
 973       && !Universe::is_bootstrapping()) {
 974     // Make sure we do not hold any locks that the VM thread also uses.
 975     // This could potentially lead to deadlocks
 976     for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 977       // Threads_lock is special, since the safepoint synchronization will not start before this is
 978       // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
 979       // since it is used to transfer control between JavaThreads and the VMThread
 980       // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
 981       if ((cur->allow_vm_block() &&
 982            cur != Threads_lock &&
 983            cur != Compile_lock &&               // Temporary: should not be necessary when we get separate compilation
 984            cur != VMOperationRequest_lock &&
 985            cur != VMOperationQueue_lock) ||
 986            cur->rank() == Mutex::special) {
 987         fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
 988       }
 989     }
 990   }
 991 
 992   if (GCALotAtAllSafepoints) {
 993     // We could enter a safepoint here and thus have a gc
 994     InterfaceSupport::check_gc_alot();
 995   }
 996 #endif
 997 }
 998 #endif
 999 
1000 bool Thread::is_in_stack(address adr) const {
1001   assert(Thread::current() == this, "is_in_stack can only be called from current thread");
1002   address end = os::current_stack_pointer();
1003   // Allow non Java threads to call this without stack_base
1004   if (_stack_base == NULL) return true;
1005   if (stack_base() >= adr && adr >= end) return true;
1006 
1007   return false;
1008 }
1009 
1010 bool Thread::is_in_usable_stack(address adr) const {
1011   size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
1012   size_t usable_stack_size = _stack_size - stack_guard_size;
1013 
1014   return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
1015 }
1016 
1017 
1018 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
1019 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
1020 // used for compilation in the future. If that change is made, the need for these methods
1021 // should be revisited, and they should be removed if possible.
1022 
1023 bool Thread::is_lock_owned(address adr) const {
1024   return on_local_stack(adr);
1025 }
1026 
1027 bool Thread::set_as_starting_thread() {
1028   // NOTE: this must be called inside the main thread.
1029   return os::create_main_thread((JavaThread*)this);
1030 }
1031 
1032 static void initialize_class(Symbol* class_name, TRAPS) {
1033   Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
1034   InstanceKlass::cast(klass)->initialize(CHECK);
1035 }
1036 
1037 
1038 // Creates the initial ThreadGroup
1039 static Handle create_initial_thread_group(TRAPS) {
1040   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
1041   InstanceKlass* ik = InstanceKlass::cast(k);
1042 
1043   Handle system_instance = ik->allocate_instance_handle(CHECK_NH);
1044   {
1045     JavaValue result(T_VOID);
1046     JavaCalls::call_special(&result,
1047                             system_instance,
1048                             ik,
1049                             vmSymbols::object_initializer_name(),
1050                             vmSymbols::void_method_signature(),
1051                             CHECK_NH);
1052   }
1053   Universe::set_system_thread_group(system_instance());
1054 
1055   Handle main_instance = ik->allocate_instance_handle(CHECK_NH);
1056   {
1057     JavaValue result(T_VOID);
1058     Handle string = java_lang_String::create_from_str("main", CHECK_NH);
1059     JavaCalls::call_special(&result,
1060                             main_instance,
1061                             ik,
1062                             vmSymbols::object_initializer_name(),
1063                             vmSymbols::threadgroup_string_void_signature(),
1064                             system_instance,
1065                             string,
1066                             CHECK_NH);
1067   }
1068   return main_instance;
1069 }
1070 
1071 // Creates the initial Thread
1072 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
1073                                  TRAPS) {
1074   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
1075   InstanceKlass* ik = InstanceKlass::cast(k);
1076   instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
1077 
1078   java_lang_Thread::set_thread(thread_oop(), thread);
1079   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1080   thread->set_threadObj(thread_oop());
1081 
1082   Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1083 
1084   JavaValue result(T_VOID);
1085   JavaCalls::call_special(&result, thread_oop,
1086                           ik,
1087                           vmSymbols::object_initializer_name(),
1088                           vmSymbols::threadgroup_string_void_signature(),
1089                           thread_group,
1090                           string,
1091                           CHECK_NULL);
1092   return thread_oop();
1093 }
1094 
1095 char java_runtime_name[128] = "";
1096 char java_runtime_version[128] = "";
1097 
1098 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1099 static const char* get_java_runtime_name(TRAPS) {
1100   Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1101                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1102   fieldDescriptor fd;
1103   bool found = k != NULL &&
1104                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1105                                                         vmSymbols::string_signature(), &fd);
1106   if (found) {
1107     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1108     if (name_oop == NULL) {
1109       return NULL;
1110     }
1111     const char* name = java_lang_String::as_utf8_string(name_oop,
1112                                                         java_runtime_name,
1113                                                         sizeof(java_runtime_name));
1114     return name;
1115   } else {
1116     return NULL;
1117   }
1118 }
1119 
1120 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1121 static const char* get_java_runtime_version(TRAPS) {
1122   Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1123                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1124   fieldDescriptor fd;
1125   bool found = k != NULL &&
1126                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1127                                                         vmSymbols::string_signature(), &fd);
1128   if (found) {
1129     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1130     if (name_oop == NULL) {
1131       return NULL;
1132     }
1133     const char* name = java_lang_String::as_utf8_string(name_oop,
1134                                                         java_runtime_version,
1135                                                         sizeof(java_runtime_version));
1136     return name;
1137   } else {
1138     return NULL;
1139   }
1140 }
1141 
1142 // General purpose hook into Java code, run once when the VM is initialized.
1143 // The Java library method itself may be changed independently from the VM.
1144 static void call_postVMInitHook(TRAPS) {
1145   Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1146   if (klass != NULL) {
1147     JavaValue result(T_VOID);
1148     JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1149                            vmSymbols::void_method_signature(),
1150                            CHECK);
1151   }
1152 }
1153 
1154 static void reset_vm_info_property(TRAPS) {
1155   // the vm info string
1156   ResourceMark rm(THREAD);
1157   const char *vm_info = VM_Version::vm_info_string();
1158 
1159   // java.lang.System class
1160   Klass* klass =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1161 
1162   // setProperty arguments
1163   Handle key_str    = java_lang_String::create_from_str("java.vm.info", CHECK);
1164   Handle value_str  = java_lang_String::create_from_str(vm_info, CHECK);
1165 
1166   // return value
1167   JavaValue r(T_OBJECT);
1168 
1169   // public static String setProperty(String key, String value);
1170   JavaCalls::call_static(&r,
1171                          klass,
1172                          vmSymbols::setProperty_name(),
1173                          vmSymbols::string_string_string_signature(),
1174                          key_str,
1175                          value_str,
1176                          CHECK);
1177 }
1178 
1179 
1180 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1181                                     bool daemon, TRAPS) {
1182   assert(thread_group.not_null(), "thread group should be specified");
1183   assert(threadObj() == NULL, "should only create Java thread object once");
1184 
1185   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1186   InstanceKlass* ik = InstanceKlass::cast(k);
1187   instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1188 
1189   java_lang_Thread::set_thread(thread_oop(), this);
1190   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1191   set_threadObj(thread_oop());
1192 
1193   JavaValue result(T_VOID);
1194   if (thread_name != NULL) {
1195     Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1196     // Thread gets assigned specified name and null target
1197     JavaCalls::call_special(&result,
1198                             thread_oop,
1199                             ik,
1200                             vmSymbols::object_initializer_name(),
1201                             vmSymbols::threadgroup_string_void_signature(),
1202                             thread_group, // Argument 1
1203                             name,         // Argument 2
1204                             THREAD);
1205   } else {
1206     // Thread gets assigned name "Thread-nnn" and null target
1207     // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1208     JavaCalls::call_special(&result,
1209                             thread_oop,
1210                             ik,
1211                             vmSymbols::object_initializer_name(),
1212                             vmSymbols::threadgroup_runnable_void_signature(),
1213                             thread_group, // Argument 1
1214                             Handle(),     // Argument 2
1215                             THREAD);
1216   }
1217 
1218 
1219   if (daemon) {
1220     java_lang_Thread::set_daemon(thread_oop());
1221   }
1222 
1223   if (HAS_PENDING_EXCEPTION) {
1224     return;
1225   }
1226 
1227   Klass* group =  SystemDictionary::ThreadGroup_klass();
1228   Handle threadObj(THREAD, this->threadObj());
1229 
1230   JavaCalls::call_special(&result,
1231                           thread_group,
1232                           group,
1233                           vmSymbols::add_method_name(),
1234                           vmSymbols::thread_void_signature(),
1235                           threadObj,          // Arg 1
1236                           THREAD);
1237 }
1238 
1239 // NamedThread --  non-JavaThread subclasses with multiple
1240 // uniquely named instances should derive from this.
1241 NamedThread::NamedThread() : Thread() {
1242   _name = NULL;
1243   _processed_thread = NULL;
1244   _gc_id = GCId::undefined();
1245 }
1246 
1247 NamedThread::~NamedThread() {
1248   if (_name != NULL) {
1249     FREE_C_HEAP_ARRAY(char, _name);
1250     _name = NULL;
1251   }
1252 }
1253 
1254 void NamedThread::set_name(const char* format, ...) {
1255   guarantee(_name == NULL, "Only get to set name once.");
1256   _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1257   guarantee(_name != NULL, "alloc failure");
1258   va_list ap;
1259   va_start(ap, format);
1260   jio_vsnprintf(_name, max_name_len, format, ap);
1261   va_end(ap);
1262 }
1263 
1264 void NamedThread::initialize_named_thread() {
1265   set_native_thread_name(name());
1266 }
1267 
1268 void NamedThread::print_on(outputStream* st) const {
1269   st->print("\"%s\" ", name());
1270   Thread::print_on(st);
1271   st->cr();
1272 }
1273 
1274 
1275 // ======= WatcherThread ========
1276 
1277 // The watcher thread exists to simulate timer interrupts.  It should
1278 // be replaced by an abstraction over whatever native support for
1279 // timer interrupts exists on the platform.
1280 
1281 WatcherThread* WatcherThread::_watcher_thread   = NULL;
1282 bool WatcherThread::_startable = false;
1283 volatile bool  WatcherThread::_should_terminate = false;
1284 
1285 WatcherThread::WatcherThread() : Thread() {
1286   assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1287   if (os::create_thread(this, os::watcher_thread)) {
1288     _watcher_thread = this;
1289 
1290     // Set the watcher thread to the highest OS priority which should not be
1291     // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1292     // is created. The only normal thread using this priority is the reference
1293     // handler thread, which runs for very short intervals only.
1294     // If the VMThread's priority is not lower than the WatcherThread profiling
1295     // will be inaccurate.
1296     os::set_priority(this, MaxPriority);
1297     if (!DisableStartThread) {
1298       os::start_thread(this);
1299     }
1300   }
1301 }
1302 
1303 int WatcherThread::sleep() const {
1304   // The WatcherThread does not participate in the safepoint protocol
1305   // for the PeriodicTask_lock because it is not a JavaThread.
1306   MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1307 
1308   if (_should_terminate) {
1309     // check for termination before we do any housekeeping or wait
1310     return 0;  // we did not sleep.
1311   }
1312 
1313   // remaining will be zero if there are no tasks,
1314   // causing the WatcherThread to sleep until a task is
1315   // enrolled
1316   int remaining = PeriodicTask::time_to_wait();
1317   int time_slept = 0;
1318 
1319   // we expect this to timeout - we only ever get unparked when
1320   // we should terminate or when a new task has been enrolled
1321   OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1322 
1323   jlong time_before_loop = os::javaTimeNanos();
1324 
1325   while (true) {
1326     bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1327                                             remaining);
1328     jlong now = os::javaTimeNanos();
1329 
1330     if (remaining == 0) {
1331       // if we didn't have any tasks we could have waited for a long time
1332       // consider the time_slept zero and reset time_before_loop
1333       time_slept = 0;
1334       time_before_loop = now;
1335     } else {
1336       // need to recalculate since we might have new tasks in _tasks
1337       time_slept = (int) ((now - time_before_loop) / 1000000);
1338     }
1339 
1340     // Change to task list or spurious wakeup of some kind
1341     if (timedout || _should_terminate) {
1342       break;
1343     }
1344 
1345     remaining = PeriodicTask::time_to_wait();
1346     if (remaining == 0) {
1347       // Last task was just disenrolled so loop around and wait until
1348       // another task gets enrolled
1349       continue;
1350     }
1351 
1352     remaining -= time_slept;
1353     if (remaining <= 0) {
1354       break;
1355     }
1356   }
1357 
1358   return time_slept;
1359 }
1360 
1361 void WatcherThread::run() {
1362   assert(this == watcher_thread(), "just checking");
1363 
1364   this->record_stack_base_and_size();
1365   this->set_native_thread_name(this->name());
1366   this->set_active_handles(JNIHandleBlock::allocate_block());
1367   while (true) {
1368     assert(watcher_thread() == Thread::current(), "thread consistency check");
1369     assert(watcher_thread() == this, "thread consistency check");
1370 
1371     // Calculate how long it'll be until the next PeriodicTask work
1372     // should be done, and sleep that amount of time.
1373     int time_waited = sleep();
1374 
1375     if (VMError::is_error_reported()) {
1376       // A fatal error has happened, the error handler(VMError::report_and_die)
1377       // should abort JVM after creating an error log file. However in some
1378       // rare cases, the error handler itself might deadlock. Here periodically
1379       // check for error reporting timeouts, and if it happens, just proceed to
1380       // abort the VM.
1381 
1382       // This code is in WatcherThread because WatcherThread wakes up
1383       // periodically so the fatal error handler doesn't need to do anything;
1384       // also because the WatcherThread is less likely to crash than other
1385       // threads.
1386 
1387       for (;;) {
1388         // Note: we use naked sleep in this loop because we want to avoid using
1389         // any kind of VM infrastructure which may be broken at this point.
1390         if (VMError::check_timeout()) {
1391           // We hit error reporting timeout. Error reporting was interrupted and
1392           // will be wrapping things up now (closing files etc). Give it some more
1393           // time, then quit the VM.
1394           os::naked_short_sleep(200);
1395           // Print a message to stderr.
1396           fdStream err(defaultStream::output_fd());
1397           err.print_raw_cr("# [ timer expired, abort... ]");
1398           // skip atexit/vm_exit/vm_abort hooks
1399           os::die();
1400         }
1401 
1402         // Wait a second, then recheck for timeout.
1403         os::naked_short_sleep(999);
1404       }
1405     }
1406 
1407     if (_should_terminate) {
1408       // check for termination before posting the next tick
1409       break;
1410     }
1411 
1412     PeriodicTask::real_time_tick(time_waited);
1413   }
1414 
1415   // Signal that it is terminated
1416   {
1417     MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1418     _watcher_thread = NULL;
1419     Terminator_lock->notify();
1420   }
1421 }
1422 
1423 void WatcherThread::start() {
1424   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1425 
1426   if (watcher_thread() == NULL && _startable) {
1427     _should_terminate = false;
1428     // Create the single instance of WatcherThread
1429     new WatcherThread();
1430   }
1431 }
1432 
1433 void WatcherThread::make_startable() {
1434   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1435   _startable = true;
1436 }
1437 
1438 void WatcherThread::stop() {
1439   {
1440     // Follow normal safepoint aware lock enter protocol since the
1441     // WatcherThread is stopped by another JavaThread.
1442     MutexLocker ml(PeriodicTask_lock);
1443     _should_terminate = true;
1444 
1445     WatcherThread* watcher = watcher_thread();
1446     if (watcher != NULL) {
1447       // unpark the WatcherThread so it can see that it should terminate
1448       watcher->unpark();
1449     }
1450   }
1451 
1452   MutexLocker mu(Terminator_lock);
1453 
1454   while (watcher_thread() != NULL) {
1455     // This wait should make safepoint checks, wait without a timeout,
1456     // and wait as a suspend-equivalent condition.
1457     Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1458                           Mutex::_as_suspend_equivalent_flag);
1459   }
1460 }
1461 
1462 void WatcherThread::unpark() {
1463   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1464   PeriodicTask_lock->notify();
1465 }
1466 
1467 void WatcherThread::print_on(outputStream* st) const {
1468   st->print("\"%s\" ", name());
1469   Thread::print_on(st);
1470   st->cr();
1471 }
1472 
1473 // ======= JavaThread ========
1474 
1475 #if INCLUDE_JVMCI
1476 
1477 jlong* JavaThread::_jvmci_old_thread_counters;
1478 
1479 bool jvmci_counters_include(JavaThread* thread) {
1480   oop threadObj = thread->threadObj();
1481   return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1482 }
1483 
1484 void JavaThread::collect_counters(typeArrayOop array) {
1485   if (JVMCICounterSize > 0) {
1486     MutexLocker tl(Threads_lock);
1487     JavaThreadIteratorWithHandle jtiwh;
1488     for (int i = 0; i < array->length(); i++) {
1489       array->long_at_put(i, _jvmci_old_thread_counters[i]);
1490     }
1491     for (; JavaThread *tp = jtiwh.next(); ) {
1492       if (jvmci_counters_include(tp)) {
1493         for (int i = 0; i < array->length(); i++) {
1494           array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1495         }
1496       }
1497     }
1498   }
1499 }
1500 
1501 #endif // INCLUDE_JVMCI
1502 
1503 // A JavaThread is a normal Java thread
1504 
1505 void JavaThread::initialize() {
1506   // Initialize fields
1507 
1508   set_saved_exception_pc(NULL);
1509   set_threadObj(NULL);
1510   _anchor.clear();
1511   set_entry_point(NULL);
1512   set_jni_functions(jni_functions());
1513   set_callee_target(NULL);
1514   set_vm_result(NULL);
1515   set_vm_result_2(NULL);
1516   set_vframe_array_head(NULL);
1517   set_vframe_array_last(NULL);
1518   set_deferred_locals(NULL);
1519   set_deopt_mark(NULL);
1520   set_deopt_compiled_method(NULL);
1521   clear_must_deopt_id();
1522   set_monitor_chunks(NULL);
1523   set_next(NULL);
1524   _on_thread_list = false;
1525   set_thread_state(_thread_new);
1526   _terminated = _not_terminated;
1527   _privileged_stack_top = NULL;
1528   _array_for_gc = NULL;
1529   _suspend_equivalent = false;
1530   _in_deopt_handler = 0;
1531   _doing_unsafe_access = false;
1532   _stack_guard_state = stack_guard_unused;
1533 #if INCLUDE_JVMCI
1534   _pending_monitorenter = false;
1535   _pending_deoptimization = -1;
1536   _pending_failed_speculation = NULL;
1537   _pending_transfer_to_interpreter = false;
1538   _adjusting_comp_level = false;
1539   _jvmci._alternate_call_target = NULL;
1540   assert(_jvmci._implicit_exception_pc == NULL, "must be");
1541   if (JVMCICounterSize > 0) {
1542     _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1543     memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1544   } else {
1545     _jvmci_counters = NULL;
1546   }
1547 #endif // INCLUDE_JVMCI
1548   _reserved_stack_activation = NULL;  // stack base not known yet
1549   (void)const_cast<oop&>(_exception_oop = oop(NULL));
1550   _exception_pc  = 0;
1551   _exception_handler_pc = 0;
1552   _is_method_handle_return = 0;
1553   _jvmti_thread_state= NULL;
1554   _should_post_on_exceptions_flag = JNI_FALSE;
1555   _jvmti_get_loaded_classes_closure = NULL;
1556   _interp_only_mode    = 0;
1557   _special_runtime_exit_condition = _no_async_condition;
1558   _pending_async_exception = NULL;
1559   _thread_stat = NULL;
1560   _thread_stat = new ThreadStatistics();
1561   _blocked_on_compilation = false;
1562   _jni_active_critical = 0;
1563   _pending_jni_exception_check_fn = NULL;
1564   _do_not_unlock_if_synchronized = false;
1565   _cached_monitor_info = NULL;
1566   _parker = Parker::Allocate(this);
1567 
1568 #ifndef PRODUCT
1569   _jmp_ring_index = 0;
1570   for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1571     record_jump(NULL, NULL, NULL, 0);
1572   }
1573 #endif // PRODUCT
1574 
1575   // Setup safepoint state info for this thread
1576   ThreadSafepointState::create(this);
1577 
1578   debug_only(_java_call_counter = 0);
1579 
1580   // JVMTI PopFrame support
1581   _popframe_condition = popframe_inactive;
1582   _popframe_preserved_args = NULL;
1583   _popframe_preserved_args_size = 0;
1584   _frames_to_pop_failed_realloc = 0;
1585 
1586   if (SafepointMechanism::uses_thread_local_poll()) {
1587     SafepointMechanism::initialize_header(this);
1588   }
1589 
1590   pd_initialize();
1591 }
1592 
1593 #if INCLUDE_ALL_GCS
1594 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1595 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1596 #endif // INCLUDE_ALL_GCS
1597 
1598 JavaThread::JavaThread(bool is_attaching_via_jni) :
1599                        Thread()
1600 #if INCLUDE_ALL_GCS
1601                        , _satb_mark_queue(&_satb_mark_queue_set),
1602                        _dirty_card_queue(&_dirty_card_queue_set)
1603 #endif // INCLUDE_ALL_GCS
1604 {
1605   initialize();
1606   if (is_attaching_via_jni) {
1607     _jni_attach_state = _attaching_via_jni;
1608   } else {
1609     _jni_attach_state = _not_attaching_via_jni;
1610   }
1611   assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1612 }
1613 
1614 bool JavaThread::reguard_stack(address cur_sp) {
1615   if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1616       && _stack_guard_state != stack_guard_reserved_disabled) {
1617     return true; // Stack already guarded or guard pages not needed.
1618   }
1619 
1620   if (register_stack_overflow()) {
1621     // For those architectures which have separate register and
1622     // memory stacks, we must check the register stack to see if
1623     // it has overflowed.
1624     return false;
1625   }
1626 
1627   // Java code never executes within the yellow zone: the latter is only
1628   // there to provoke an exception during stack banging.  If java code
1629   // is executing there, either StackShadowPages should be larger, or
1630   // some exception code in c1, c2 or the interpreter isn't unwinding
1631   // when it should.
1632   guarantee(cur_sp > stack_reserved_zone_base(),
1633             "not enough space to reguard - increase StackShadowPages");
1634   if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1635     enable_stack_yellow_reserved_zone();
1636     if (reserved_stack_activation() != stack_base()) {
1637       set_reserved_stack_activation(stack_base());
1638     }
1639   } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1640     set_reserved_stack_activation(stack_base());
1641     enable_stack_reserved_zone();
1642   }
1643   return true;
1644 }
1645 
1646 bool JavaThread::reguard_stack(void) {
1647   return reguard_stack(os::current_stack_pointer());
1648 }
1649 
1650 
1651 void JavaThread::block_if_vm_exited() {
1652   if (_terminated == _vm_exited) {
1653     // _vm_exited is set at safepoint, and Threads_lock is never released
1654     // we will block here forever
1655     Threads_lock->lock_without_safepoint_check();
1656     ShouldNotReachHere();
1657   }
1658 }
1659 
1660 
1661 // Remove this ifdef when C1 is ported to the compiler interface.
1662 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1663 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1664 
1665 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1666                        Thread()
1667 #if INCLUDE_ALL_GCS
1668                        , _satb_mark_queue(&_satb_mark_queue_set),
1669                        _dirty_card_queue(&_dirty_card_queue_set)
1670 #endif // INCLUDE_ALL_GCS
1671 {
1672   initialize();
1673   _jni_attach_state = _not_attaching_via_jni;
1674   set_entry_point(entry_point);
1675   // Create the native thread itself.
1676   // %note runtime_23
1677   os::ThreadType thr_type = os::java_thread;
1678   thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1679                                                      os::java_thread;
1680   os::create_thread(this, thr_type, stack_sz);
1681   // The _osthread may be NULL here because we ran out of memory (too many threads active).
1682   // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1683   // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1684   // the exception consists of creating the exception object & initializing it, initialization
1685   // will leave the VM via a JavaCall and then all locks must be unlocked).
1686   //
1687   // The thread is still suspended when we reach here. Thread must be explicit started
1688   // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1689   // by calling Threads:add. The reason why this is not done here, is because the thread
1690   // object must be fully initialized (take a look at JVM_Start)
1691 }
1692 
1693 JavaThread::~JavaThread() {
1694 
1695   // JSR166 -- return the parker to the free list
1696   Parker::Release(_parker);
1697   _parker = NULL;
1698 
1699   // Free any remaining  previous UnrollBlock
1700   vframeArray* old_array = vframe_array_last();
1701 
1702   if (old_array != NULL) {
1703     Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1704     old_array->set_unroll_block(NULL);
1705     delete old_info;
1706     delete old_array;
1707   }
1708 
1709   GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1710   if (deferred != NULL) {
1711     // This can only happen if thread is destroyed before deoptimization occurs.
1712     assert(deferred->length() != 0, "empty array!");
1713     do {
1714       jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1715       deferred->remove_at(0);
1716       // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1717       delete dlv;
1718     } while (deferred->length() != 0);
1719     delete deferred;
1720   }
1721 
1722   // All Java related clean up happens in exit
1723   ThreadSafepointState::destroy(this);
1724   if (_thread_stat != NULL) delete _thread_stat;
1725 
1726 #if INCLUDE_JVMCI
1727   if (JVMCICounterSize > 0) {
1728     if (jvmci_counters_include(this)) {
1729       for (int i = 0; i < JVMCICounterSize; i++) {
1730         _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1731       }
1732     }
1733     FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1734   }
1735 #endif // INCLUDE_JVMCI
1736 }
1737 
1738 
1739 // The first routine called by a new Java thread
1740 void JavaThread::run() {
1741   // initialize thread-local alloc buffer related fields
1742   this->initialize_tlab();
1743 
1744   // used to test validity of stack trace backs
1745   this->record_base_of_stack_pointer();
1746 
1747   // Record real stack base and size.
1748   this->record_stack_base_and_size();
1749 
1750   this->create_stack_guard_pages();
1751 
1752   this->cache_global_variables();
1753 
1754   // Thread is now sufficient initialized to be handled by the safepoint code as being
1755   // in the VM. Change thread state from _thread_new to _thread_in_vm
1756   ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1757 
1758   assert(JavaThread::current() == this, "sanity check");
1759   assert(!Thread::current()->owns_locks(), "sanity check");
1760 
1761   DTRACE_THREAD_PROBE(start, this);
1762 
1763   // This operation might block. We call that after all safepoint checks for a new thread has
1764   // been completed.
1765   this->set_active_handles(JNIHandleBlock::allocate_block());
1766 
1767   if (JvmtiExport::should_post_thread_life()) {
1768     JvmtiExport::post_thread_start(this);
1769   }
1770 
1771   EventThreadStart event;
1772   if (event.should_commit()) {
1773     event.set_thread(THREAD_TRACE_ID(this));
1774     event.commit();
1775   }
1776 
1777   // We call another function to do the rest so we are sure that the stack addresses used
1778   // from there will be lower than the stack base just computed
1779   thread_main_inner();
1780 
1781   // Note, thread is no longer valid at this point!
1782 }
1783 
1784 
1785 void JavaThread::thread_main_inner() {
1786   assert(JavaThread::current() == this, "sanity check");
1787   assert(this->threadObj() != NULL, "just checking");
1788 
1789   // Execute thread entry point unless this thread has a pending exception
1790   // or has been stopped before starting.
1791   // Note: Due to JVM_StopThread we can have pending exceptions already!
1792   if (!this->has_pending_exception() &&
1793       !java_lang_Thread::is_stillborn(this->threadObj())) {
1794     {
1795       ResourceMark rm(this);
1796       this->set_native_thread_name(this->get_thread_name());
1797     }
1798     HandleMark hm(this);
1799     this->entry_point()(this, this);
1800   }
1801 
1802   DTRACE_THREAD_PROBE(stop, this);
1803 
1804   this->exit(false);
1805   this->smr_delete();
1806 }
1807 
1808 
1809 static void ensure_join(JavaThread* thread) {
1810   // We do not need to grab the Threads_lock, since we are operating on ourself.
1811   Handle threadObj(thread, thread->threadObj());
1812   assert(threadObj.not_null(), "java thread object must exist");
1813   ObjectLocker lock(threadObj, thread);
1814   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1815   thread->clear_pending_exception();
1816   // Thread is exiting. So set thread_status field in  java.lang.Thread class to TERMINATED.
1817   java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1818   // Clear the native thread instance - this makes isAlive return false and allows the join()
1819   // to complete once we've done the notify_all below
1820   java_lang_Thread::set_thread(threadObj(), NULL);
1821   lock.notify_all(thread);
1822   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1823   thread->clear_pending_exception();
1824 }
1825 
1826 
1827 // For any new cleanup additions, please check to see if they need to be applied to
1828 // cleanup_failed_attach_current_thread as well.
1829 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1830   assert(this == JavaThread::current(), "thread consistency check");
1831 
1832   elapsedTimer _timer_exit_phase1;
1833   elapsedTimer _timer_exit_phase2;
1834   elapsedTimer _timer_exit_phase3;
1835   elapsedTimer _timer_exit_phase4;
1836 
1837   if (log_is_enabled(Debug, os, thread, timer)) {
1838     _timer_exit_phase1.start();
1839   }
1840 
1841   HandleMark hm(this);
1842   Handle uncaught_exception(this, this->pending_exception());
1843   this->clear_pending_exception();
1844   Handle threadObj(this, this->threadObj());
1845   assert(threadObj.not_null(), "Java thread object should be created");
1846 
1847   // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1848   {
1849     EXCEPTION_MARK;
1850 
1851     CLEAR_PENDING_EXCEPTION;
1852   }
1853   if (!destroy_vm) {
1854     if (uncaught_exception.not_null()) {
1855       EXCEPTION_MARK;
1856       // Call method Thread.dispatchUncaughtException().
1857       Klass* thread_klass = SystemDictionary::Thread_klass();
1858       JavaValue result(T_VOID);
1859       JavaCalls::call_virtual(&result,
1860                               threadObj, thread_klass,
1861                               vmSymbols::dispatchUncaughtException_name(),
1862                               vmSymbols::throwable_void_signature(),
1863                               uncaught_exception,
1864                               THREAD);
1865       if (HAS_PENDING_EXCEPTION) {
1866         ResourceMark rm(this);
1867         jio_fprintf(defaultStream::error_stream(),
1868                     "\nException: %s thrown from the UncaughtExceptionHandler"
1869                     " in thread \"%s\"\n",
1870                     pending_exception()->klass()->external_name(),
1871                     get_thread_name());
1872         CLEAR_PENDING_EXCEPTION;
1873       }
1874     }
1875 
1876     // Called before the java thread exit since we want to read info
1877     // from java_lang_Thread object
1878     EventThreadEnd event;
1879     if (event.should_commit()) {
1880       event.set_thread(THREAD_TRACE_ID(this));
1881       event.commit();
1882     }
1883 
1884     // Call after last event on thread
1885     EVENT_THREAD_EXIT(this);
1886 
1887     // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1888     // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1889     // is deprecated anyhow.
1890     if (!is_Compiler_thread()) {
1891       int count = 3;
1892       while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1893         EXCEPTION_MARK;
1894         JavaValue result(T_VOID);
1895         Klass* thread_klass = SystemDictionary::Thread_klass();
1896         JavaCalls::call_virtual(&result,
1897                                 threadObj, thread_klass,
1898                                 vmSymbols::exit_method_name(),
1899                                 vmSymbols::void_method_signature(),
1900                                 THREAD);
1901         CLEAR_PENDING_EXCEPTION;
1902       }
1903     }
1904     // notify JVMTI
1905     if (JvmtiExport::should_post_thread_life()) {
1906       JvmtiExport::post_thread_end(this);
1907     }
1908 
1909     // We have notified the agents that we are exiting, before we go on,
1910     // we must check for a pending external suspend request and honor it
1911     // in order to not surprise the thread that made the suspend request.
1912     while (true) {
1913       {
1914         MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1915         if (!is_external_suspend()) {
1916           set_terminated(_thread_exiting);
1917           ThreadService::current_thread_exiting(this);
1918           break;
1919         }
1920         // Implied else:
1921         // Things get a little tricky here. We have a pending external
1922         // suspend request, but we are holding the SR_lock so we
1923         // can't just self-suspend. So we temporarily drop the lock
1924         // and then self-suspend.
1925       }
1926 
1927       ThreadBlockInVM tbivm(this);
1928       java_suspend_self();
1929 
1930       // We're done with this suspend request, but we have to loop around
1931       // and check again. Eventually we will get SR_lock without a pending
1932       // external suspend request and will be able to mark ourselves as
1933       // exiting.
1934     }
1935     // no more external suspends are allowed at this point
1936   } else {
1937     // before_exit() has already posted JVMTI THREAD_END events
1938   }
1939 
1940   if (log_is_enabled(Debug, os, thread, timer)) {
1941     _timer_exit_phase1.stop();
1942     _timer_exit_phase2.start();
1943   }
1944   // Notify waiters on thread object. This has to be done after exit() is called
1945   // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1946   // group should have the destroyed bit set before waiters are notified).
1947   ensure_join(this);
1948   assert(!this->has_pending_exception(), "ensure_join should have cleared");
1949 
1950   if (log_is_enabled(Debug, os, thread, timer)) {
1951     _timer_exit_phase2.stop();
1952     _timer_exit_phase3.start();
1953   }
1954   // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1955   // held by this thread must be released. The spec does not distinguish
1956   // between JNI-acquired and regular Java monitors. We can only see
1957   // regular Java monitors here if monitor enter-exit matching is broken.
1958   //
1959   // Optionally release any monitors for regular JavaThread exits. This
1960   // is provided as a work around for any bugs in monitor enter-exit
1961   // matching. This can be expensive so it is not enabled by default.
1962   //
1963   // ensure_join() ignores IllegalThreadStateExceptions, and so does
1964   // ObjectSynchronizer::release_monitors_owned_by_thread().
1965   if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) {
1966     // Sanity check even though JNI DetachCurrentThread() would have
1967     // returned JNI_ERR if there was a Java frame. JavaThread exit
1968     // should be done executing Java code by the time we get here.
1969     assert(!this->has_last_Java_frame(),
1970            "should not have a Java frame when detaching or exiting");
1971     ObjectSynchronizer::release_monitors_owned_by_thread(this);
1972     assert(!this->has_pending_exception(), "release_monitors should have cleared");
1973   }
1974 
1975   // These things needs to be done while we are still a Java Thread. Make sure that thread
1976   // is in a consistent state, in case GC happens
1977   assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1978 
1979   if (active_handles() != NULL) {
1980     JNIHandleBlock* block = active_handles();
1981     set_active_handles(NULL);
1982     JNIHandleBlock::release_block(block);
1983   }
1984 
1985   if (free_handle_block() != NULL) {
1986     JNIHandleBlock* block = free_handle_block();
1987     set_free_handle_block(NULL);
1988     JNIHandleBlock::release_block(block);
1989   }
1990 
1991   // These have to be removed while this is still a valid thread.
1992   remove_stack_guard_pages();
1993 
1994   if (UseTLAB) {
1995     tlab().make_parsable(true);  // retire TLAB
1996   }
1997 
1998   if (JvmtiEnv::environments_might_exist()) {
1999     JvmtiExport::cleanup_thread(this);
2000   }
2001 
2002   // We must flush any deferred card marks and other various GC barrier
2003   // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer)
2004   // before removing a thread from the list of active threads.
2005   BarrierSet::barrier_set()->on_thread_detach(this);
2006 
2007   log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
2008     exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
2009     os::current_thread_id());
2010 
2011   if (log_is_enabled(Debug, os, thread, timer)) {
2012     _timer_exit_phase3.stop();
2013     _timer_exit_phase4.start();
2014   }
2015   // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
2016   Threads::remove(this);
2017 
2018   if (log_is_enabled(Debug, os, thread, timer)) {
2019     _timer_exit_phase4.stop();
2020     ResourceMark rm(this);
2021     log_debug(os, thread, timer)("name='%s'"
2022                                  ", exit-phase1=" JLONG_FORMAT
2023                                  ", exit-phase2=" JLONG_FORMAT
2024                                  ", exit-phase3=" JLONG_FORMAT
2025                                  ", exit-phase4=" JLONG_FORMAT,
2026                                  get_thread_name(),
2027                                  _timer_exit_phase1.milliseconds(),
2028                                  _timer_exit_phase2.milliseconds(),
2029                                  _timer_exit_phase3.milliseconds(),
2030                                  _timer_exit_phase4.milliseconds());
2031   }
2032 }
2033 
2034 void JavaThread::cleanup_failed_attach_current_thread() {
2035   if (active_handles() != NULL) {
2036     JNIHandleBlock* block = active_handles();
2037     set_active_handles(NULL);
2038     JNIHandleBlock::release_block(block);
2039   }
2040 
2041   if (free_handle_block() != NULL) {
2042     JNIHandleBlock* block = free_handle_block();
2043     set_free_handle_block(NULL);
2044     JNIHandleBlock::release_block(block);
2045   }
2046 
2047   // These have to be removed while this is still a valid thread.
2048   remove_stack_guard_pages();
2049 
2050   if (UseTLAB) {
2051     tlab().make_parsable(true);  // retire TLAB, if any
2052   }
2053 
2054   BarrierSet::barrier_set()->on_thread_detach(this);
2055 
2056   Threads::remove(this);
2057   this->smr_delete();
2058 }
2059 
2060 JavaThread* JavaThread::active() {
2061   Thread* thread = Thread::current();
2062   if (thread->is_Java_thread()) {
2063     return (JavaThread*) thread;
2064   } else {
2065     assert(thread->is_VM_thread(), "this must be a vm thread");
2066     VM_Operation* op = ((VMThread*) thread)->vm_operation();
2067     JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2068     assert(ret->is_Java_thread(), "must be a Java thread");
2069     return ret;
2070   }
2071 }
2072 
2073 bool JavaThread::is_lock_owned(address adr) const {
2074   if (Thread::is_lock_owned(adr)) return true;
2075 
2076   for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2077     if (chunk->contains(adr)) return true;
2078   }
2079 
2080   return false;
2081 }
2082 
2083 
2084 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2085   chunk->set_next(monitor_chunks());
2086   set_monitor_chunks(chunk);
2087 }
2088 
2089 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2090   guarantee(monitor_chunks() != NULL, "must be non empty");
2091   if (monitor_chunks() == chunk) {
2092     set_monitor_chunks(chunk->next());
2093   } else {
2094     MonitorChunk* prev = monitor_chunks();
2095     while (prev->next() != chunk) prev = prev->next();
2096     prev->set_next(chunk->next());
2097   }
2098 }
2099 
2100 // JVM support.
2101 
2102 // Note: this function shouldn't block if it's called in
2103 // _thread_in_native_trans state (such as from
2104 // check_special_condition_for_native_trans()).
2105 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2106 
2107   if (has_last_Java_frame() && has_async_condition()) {
2108     // If we are at a polling page safepoint (not a poll return)
2109     // then we must defer async exception because live registers
2110     // will be clobbered by the exception path. Poll return is
2111     // ok because the call we a returning from already collides
2112     // with exception handling registers and so there is no issue.
2113     // (The exception handling path kills call result registers but
2114     //  this is ok since the exception kills the result anyway).
2115 
2116     if (is_at_poll_safepoint()) {
2117       // if the code we are returning to has deoptimized we must defer
2118       // the exception otherwise live registers get clobbered on the
2119       // exception path before deoptimization is able to retrieve them.
2120       //
2121       RegisterMap map(this, false);
2122       frame caller_fr = last_frame().sender(&map);
2123       assert(caller_fr.is_compiled_frame(), "what?");
2124       if (caller_fr.is_deoptimized_frame()) {
2125         log_info(exceptions)("deferred async exception at compiled safepoint");
2126         return;
2127       }
2128     }
2129   }
2130 
2131   JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2132   if (condition == _no_async_condition) {
2133     // Conditions have changed since has_special_runtime_exit_condition()
2134     // was called:
2135     // - if we were here only because of an external suspend request,
2136     //   then that was taken care of above (or cancelled) so we are done
2137     // - if we were here because of another async request, then it has
2138     //   been cleared between the has_special_runtime_exit_condition()
2139     //   and now so again we are done
2140     return;
2141   }
2142 
2143   // Check for pending async. exception
2144   if (_pending_async_exception != NULL) {
2145     // Only overwrite an already pending exception, if it is not a threadDeath.
2146     if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2147 
2148       // We cannot call Exceptions::_throw(...) here because we cannot block
2149       set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2150 
2151       LogTarget(Info, exceptions) lt;
2152       if (lt.is_enabled()) {
2153         ResourceMark rm;
2154         LogStream ls(lt);
2155         ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2156           if (has_last_Java_frame()) {
2157             frame f = last_frame();
2158            ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2159           }
2160         ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2161       }
2162       _pending_async_exception = NULL;
2163       clear_has_async_exception();
2164     }
2165   }
2166 
2167   if (check_unsafe_error &&
2168       condition == _async_unsafe_access_error && !has_pending_exception()) {
2169     condition = _no_async_condition;  // done
2170     switch (thread_state()) {
2171     case _thread_in_vm: {
2172       JavaThread* THREAD = this;
2173       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2174     }
2175     case _thread_in_native: {
2176       ThreadInVMfromNative tiv(this);
2177       JavaThread* THREAD = this;
2178       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2179     }
2180     case _thread_in_Java: {
2181       ThreadInVMfromJava tiv(this);
2182       JavaThread* THREAD = this;
2183       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2184     }
2185     default:
2186       ShouldNotReachHere();
2187     }
2188   }
2189 
2190   assert(condition == _no_async_condition || has_pending_exception() ||
2191          (!check_unsafe_error && condition == _async_unsafe_access_error),
2192          "must have handled the async condition, if no exception");
2193 }
2194 
2195 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2196   //
2197   // Check for pending external suspend. Internal suspend requests do
2198   // not use handle_special_runtime_exit_condition().
2199   // If JNIEnv proxies are allowed, don't self-suspend if the target
2200   // thread is not the current thread. In older versions of jdbx, jdbx
2201   // threads could call into the VM with another thread's JNIEnv so we
2202   // can be here operating on behalf of a suspended thread (4432884).
2203   bool do_self_suspend = is_external_suspend_with_lock();
2204   if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2205     //
2206     // Because thread is external suspended the safepoint code will count
2207     // thread as at a safepoint. This can be odd because we can be here
2208     // as _thread_in_Java which would normally transition to _thread_blocked
2209     // at a safepoint. We would like to mark the thread as _thread_blocked
2210     // before calling java_suspend_self like all other callers of it but
2211     // we must then observe proper safepoint protocol. (We can't leave
2212     // _thread_blocked with a safepoint in progress). However we can be
2213     // here as _thread_in_native_trans so we can't use a normal transition
2214     // constructor/destructor pair because they assert on that type of
2215     // transition. We could do something like:
2216     //
2217     // JavaThreadState state = thread_state();
2218     // set_thread_state(_thread_in_vm);
2219     // {
2220     //   ThreadBlockInVM tbivm(this);
2221     //   java_suspend_self()
2222     // }
2223     // set_thread_state(_thread_in_vm_trans);
2224     // if (safepoint) block;
2225     // set_thread_state(state);
2226     //
2227     // but that is pretty messy. Instead we just go with the way the
2228     // code has worked before and note that this is the only path to
2229     // java_suspend_self that doesn't put the thread in _thread_blocked
2230     // mode.
2231 
2232     frame_anchor()->make_walkable(this);
2233     java_suspend_self();
2234 
2235     // We might be here for reasons in addition to the self-suspend request
2236     // so check for other async requests.
2237   }
2238 
2239   if (check_asyncs) {
2240     check_and_handle_async_exceptions();
2241   }
2242 #if INCLUDE_TRACE
2243   if (is_trace_suspend()) {
2244     TRACE_SUSPEND_THREAD(this);
2245   }
2246 #endif
2247 }
2248 
2249 void JavaThread::send_thread_stop(oop java_throwable)  {
2250   assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2251   assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2252   assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2253 
2254   // Do not throw asynchronous exceptions against the compiler thread
2255   // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2256   if (!can_call_java()) return;
2257 
2258   {
2259     // Actually throw the Throwable against the target Thread - however
2260     // only if there is no thread death exception installed already.
2261     if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2262       // If the topmost frame is a runtime stub, then we are calling into
2263       // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2264       // must deoptimize the caller before continuing, as the compiled  exception handler table
2265       // may not be valid
2266       if (has_last_Java_frame()) {
2267         frame f = last_frame();
2268         if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2269           // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2270           RegisterMap reg_map(this, UseBiasedLocking);
2271           frame compiled_frame = f.sender(&reg_map);
2272           if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2273             Deoptimization::deoptimize(this, compiled_frame, &reg_map);
2274           }
2275         }
2276       }
2277 
2278       // Set async. pending exception in thread.
2279       set_pending_async_exception(java_throwable);
2280 
2281       if (log_is_enabled(Info, exceptions)) {
2282          ResourceMark rm;
2283         log_info(exceptions)("Pending Async. exception installed of type: %s",
2284                              InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2285       }
2286       // for AbortVMOnException flag
2287       Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2288     }
2289   }
2290 
2291 
2292   // Interrupt thread so it will wake up from a potential wait()
2293   Thread::interrupt(this);
2294 }
2295 
2296 // External suspension mechanism.
2297 //
2298 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2299 // to any VM_locks and it is at a transition
2300 // Self-suspension will happen on the transition out of the vm.
2301 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2302 //
2303 // Guarantees on return:
2304 //   + Target thread will not execute any new bytecode (that's why we need to
2305 //     force a safepoint)
2306 //   + Target thread will not enter any new monitors
2307 //
2308 void JavaThread::java_suspend() {
2309   ThreadsListHandle tlh;
2310   if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) {
2311     return;
2312   }
2313 
2314   { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2315     if (!is_external_suspend()) {
2316       // a racing resume has cancelled us; bail out now
2317       return;
2318     }
2319 
2320     // suspend is done
2321     uint32_t debug_bits = 0;
2322     // Warning: is_ext_suspend_completed() may temporarily drop the
2323     // SR_lock to allow the thread to reach a stable thread state if
2324     // it is currently in a transient thread state.
2325     if (is_ext_suspend_completed(false /* !called_by_wait */,
2326                                  SuspendRetryDelay, &debug_bits)) {
2327       return;
2328     }
2329   }
2330 
2331   VM_ThreadSuspend vm_suspend;
2332   VMThread::execute(&vm_suspend);
2333 }
2334 
2335 // Part II of external suspension.
2336 // A JavaThread self suspends when it detects a pending external suspend
2337 // request. This is usually on transitions. It is also done in places
2338 // where continuing to the next transition would surprise the caller,
2339 // e.g., monitor entry.
2340 //
2341 // Returns the number of times that the thread self-suspended.
2342 //
2343 // Note: DO NOT call java_suspend_self() when you just want to block current
2344 //       thread. java_suspend_self() is the second stage of cooperative
2345 //       suspension for external suspend requests and should only be used
2346 //       to complete an external suspend request.
2347 //
2348 int JavaThread::java_suspend_self() {
2349   int ret = 0;
2350 
2351   // we are in the process of exiting so don't suspend
2352   if (is_exiting()) {
2353     clear_external_suspend();
2354     return ret;
2355   }
2356 
2357   assert(_anchor.walkable() ||
2358          (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2359          "must have walkable stack");
2360 
2361   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2362 
2363   assert(!this->is_ext_suspended(),
2364          "a thread trying to self-suspend should not already be suspended");
2365 
2366   if (this->is_suspend_equivalent()) {
2367     // If we are self-suspending as a result of the lifting of a
2368     // suspend equivalent condition, then the suspend_equivalent
2369     // flag is not cleared until we set the ext_suspended flag so
2370     // that wait_for_ext_suspend_completion() returns consistent
2371     // results.
2372     this->clear_suspend_equivalent();
2373   }
2374 
2375   // A racing resume may have cancelled us before we grabbed SR_lock
2376   // above. Or another external suspend request could be waiting for us
2377   // by the time we return from SR_lock()->wait(). The thread
2378   // that requested the suspension may already be trying to walk our
2379   // stack and if we return now, we can change the stack out from under
2380   // it. This would be a "bad thing (TM)" and cause the stack walker
2381   // to crash. We stay self-suspended until there are no more pending
2382   // external suspend requests.
2383   while (is_external_suspend()) {
2384     ret++;
2385     this->set_ext_suspended();
2386 
2387     // _ext_suspended flag is cleared by java_resume()
2388     while (is_ext_suspended()) {
2389       this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2390     }
2391   }
2392 
2393   return ret;
2394 }
2395 
2396 #ifdef ASSERT
2397 // Verify the JavaThread has not yet been published in the Threads::list, and
2398 // hence doesn't need protection from concurrent access at this stage.
2399 void JavaThread::verify_not_published() {
2400   // Cannot create a ThreadsListHandle here and check !tlh.includes(this)
2401   // since an unpublished JavaThread doesn't participate in the
2402   // Thread-SMR protocol for keeping a ThreadsList alive.
2403   assert(!on_thread_list(), "JavaThread shouldn't have been published yet!");
2404 }
2405 #endif
2406 
2407 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2408 // progress or when _suspend_flags is non-zero.
2409 // Current thread needs to self-suspend if there is a suspend request and/or
2410 // block if a safepoint is in progress.
2411 // Async exception ISN'T checked.
2412 // Note only the ThreadInVMfromNative transition can call this function
2413 // directly and when thread state is _thread_in_native_trans
2414 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2415   assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2416 
2417   JavaThread *curJT = JavaThread::current();
2418   bool do_self_suspend = thread->is_external_suspend();
2419 
2420   assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2421 
2422   // If JNIEnv proxies are allowed, don't self-suspend if the target
2423   // thread is not the current thread. In older versions of jdbx, jdbx
2424   // threads could call into the VM with another thread's JNIEnv so we
2425   // can be here operating on behalf of a suspended thread (4432884).
2426   if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2427     JavaThreadState state = thread->thread_state();
2428 
2429     // We mark this thread_blocked state as a suspend-equivalent so
2430     // that a caller to is_ext_suspend_completed() won't be confused.
2431     // The suspend-equivalent state is cleared by java_suspend_self().
2432     thread->set_suspend_equivalent();
2433 
2434     // If the safepoint code sees the _thread_in_native_trans state, it will
2435     // wait until the thread changes to other thread state. There is no
2436     // guarantee on how soon we can obtain the SR_lock and complete the
2437     // self-suspend request. It would be a bad idea to let safepoint wait for
2438     // too long. Temporarily change the state to _thread_blocked to
2439     // let the VM thread know that this thread is ready for GC. The problem
2440     // of changing thread state is that safepoint could happen just after
2441     // java_suspend_self() returns after being resumed, and VM thread will
2442     // see the _thread_blocked state. We must check for safepoint
2443     // after restoring the state and make sure we won't leave while a safepoint
2444     // is in progress.
2445     thread->set_thread_state(_thread_blocked);
2446     thread->java_suspend_self();
2447     thread->set_thread_state(state);
2448 
2449     InterfaceSupport::serialize_thread_state_with_handler(thread);
2450   }
2451 
2452   SafepointMechanism::block_if_requested(curJT);
2453 
2454   if (thread->is_deopt_suspend()) {
2455     thread->clear_deopt_suspend();
2456     RegisterMap map(thread, false);
2457     frame f = thread->last_frame();
2458     while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2459       f = f.sender(&map);
2460     }
2461     if (f.id() == thread->must_deopt_id()) {
2462       thread->clear_must_deopt_id();
2463       f.deoptimize(thread);
2464     } else {
2465       fatal("missed deoptimization!");
2466     }
2467   }
2468 #if INCLUDE_TRACE
2469   if (thread->is_trace_suspend()) {
2470     TRACE_SUSPEND_THREAD(thread);
2471   }
2472 #endif
2473 }
2474 
2475 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2476 // progress or when _suspend_flags is non-zero.
2477 // Current thread needs to self-suspend if there is a suspend request and/or
2478 // block if a safepoint is in progress.
2479 // Also check for pending async exception (not including unsafe access error).
2480 // Note only the native==>VM/Java barriers can call this function and when
2481 // thread state is _thread_in_native_trans.
2482 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2483   check_safepoint_and_suspend_for_native_trans(thread);
2484 
2485   if (thread->has_async_exception()) {
2486     // We are in _thread_in_native_trans state, don't handle unsafe
2487     // access error since that may block.
2488     thread->check_and_handle_async_exceptions(false);
2489   }
2490 }
2491 
2492 // This is a variant of the normal
2493 // check_special_condition_for_native_trans with slightly different
2494 // semantics for use by critical native wrappers.  It does all the
2495 // normal checks but also performs the transition back into
2496 // thread_in_Java state.  This is required so that critical natives
2497 // can potentially block and perform a GC if they are the last thread
2498 // exiting the GCLocker.
2499 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2500   check_special_condition_for_native_trans(thread);
2501 
2502   // Finish the transition
2503   thread->set_thread_state(_thread_in_Java);
2504 
2505   if (thread->do_critical_native_unlock()) {
2506     ThreadInVMfromJavaNoAsyncException tiv(thread);
2507     GCLocker::unlock_critical(thread);
2508     thread->clear_critical_native_unlock();
2509   }
2510 }
2511 
2512 // We need to guarantee the Threads_lock here, since resumes are not
2513 // allowed during safepoint synchronization
2514 // Can only resume from an external suspension
2515 void JavaThread::java_resume() {
2516   assert_locked_or_safepoint(Threads_lock);
2517 
2518   // Sanity check: thread is gone, has started exiting or the thread
2519   // was not externally suspended.
2520   ThreadsListHandle tlh;
2521   if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) {
2522     return;
2523   }
2524 
2525   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2526 
2527   clear_external_suspend();
2528 
2529   if (is_ext_suspended()) {
2530     clear_ext_suspended();
2531     SR_lock()->notify_all();
2532   }
2533 }
2534 
2535 size_t JavaThread::_stack_red_zone_size = 0;
2536 size_t JavaThread::_stack_yellow_zone_size = 0;
2537 size_t JavaThread::_stack_reserved_zone_size = 0;
2538 size_t JavaThread::_stack_shadow_zone_size = 0;
2539 
2540 void JavaThread::create_stack_guard_pages() {
2541   if (!os::uses_stack_guard_pages() ||
2542       _stack_guard_state != stack_guard_unused ||
2543       (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) {
2544       log_info(os, thread)("Stack guard page creation for thread "
2545                            UINTX_FORMAT " disabled", os::current_thread_id());
2546     return;
2547   }
2548   address low_addr = stack_end();
2549   size_t len = stack_guard_zone_size();
2550 
2551   assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2552   assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2553 
2554   int must_commit = os::must_commit_stack_guard_pages();
2555   // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2556 
2557   if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2558     log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2559     return;
2560   }
2561 
2562   if (os::guard_memory((char *) low_addr, len)) {
2563     _stack_guard_state = stack_guard_enabled;
2564   } else {
2565     log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2566       PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2567     if (os::uncommit_memory((char *) low_addr, len)) {
2568       log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2569     }
2570     return;
2571   }
2572 
2573   log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2574     PTR_FORMAT "-" PTR_FORMAT ".",
2575     os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2576 }
2577 
2578 void JavaThread::remove_stack_guard_pages() {
2579   assert(Thread::current() == this, "from different thread");
2580   if (_stack_guard_state == stack_guard_unused) return;
2581   address low_addr = stack_end();
2582   size_t len = stack_guard_zone_size();
2583 
2584   if (os::must_commit_stack_guard_pages()) {
2585     if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2586       _stack_guard_state = stack_guard_unused;
2587     } else {
2588       log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2589         PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2590       return;
2591     }
2592   } else {
2593     if (_stack_guard_state == stack_guard_unused) return;
2594     if (os::unguard_memory((char *) low_addr, len)) {
2595       _stack_guard_state = stack_guard_unused;
2596     } else {
2597       log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2598         PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2599       return;
2600     }
2601   }
2602 
2603   log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2604     PTR_FORMAT "-" PTR_FORMAT ".",
2605     os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2606 }
2607 
2608 void JavaThread::enable_stack_reserved_zone() {
2609   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2610   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2611 
2612   // The base notation is from the stack's point of view, growing downward.
2613   // We need to adjust it to work correctly with guard_memory()
2614   address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2615 
2616   guarantee(base < stack_base(),"Error calculating stack reserved zone");
2617   guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2618 
2619   if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2620     _stack_guard_state = stack_guard_enabled;
2621   } else {
2622     warning("Attempt to guard stack reserved zone failed.");
2623   }
2624   enable_register_stack_guard();
2625 }
2626 
2627 void JavaThread::disable_stack_reserved_zone() {
2628   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2629   assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2630 
2631   // Simply return if called for a thread that does not use guard pages.
2632   if (_stack_guard_state == stack_guard_unused) return;
2633 
2634   // The base notation is from the stack's point of view, growing downward.
2635   // We need to adjust it to work correctly with guard_memory()
2636   address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2637 
2638   if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2639     _stack_guard_state = stack_guard_reserved_disabled;
2640   } else {
2641     warning("Attempt to unguard stack reserved zone failed.");
2642   }
2643   disable_register_stack_guard();
2644 }
2645 
2646 void JavaThread::enable_stack_yellow_reserved_zone() {
2647   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2648   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2649 
2650   // The base notation is from the stacks point of view, growing downward.
2651   // We need to adjust it to work correctly with guard_memory()
2652   address base = stack_red_zone_base();
2653 
2654   guarantee(base < stack_base(), "Error calculating stack yellow zone");
2655   guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2656 
2657   if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2658     _stack_guard_state = stack_guard_enabled;
2659   } else {
2660     warning("Attempt to guard stack yellow zone failed.");
2661   }
2662   enable_register_stack_guard();
2663 }
2664 
2665 void JavaThread::disable_stack_yellow_reserved_zone() {
2666   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2667   assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2668 
2669   // Simply return if called for a thread that does not use guard pages.
2670   if (_stack_guard_state == stack_guard_unused) return;
2671 
2672   // The base notation is from the stacks point of view, growing downward.
2673   // We need to adjust it to work correctly with guard_memory()
2674   address base = stack_red_zone_base();
2675 
2676   if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2677     _stack_guard_state = stack_guard_yellow_reserved_disabled;
2678   } else {
2679     warning("Attempt to unguard stack yellow zone failed.");
2680   }
2681   disable_register_stack_guard();
2682 }
2683 
2684 void JavaThread::enable_stack_red_zone() {
2685   // The base notation is from the stacks point of view, growing downward.
2686   // We need to adjust it to work correctly with guard_memory()
2687   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2688   address base = stack_red_zone_base() - stack_red_zone_size();
2689 
2690   guarantee(base < stack_base(), "Error calculating stack red zone");
2691   guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2692 
2693   if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2694     warning("Attempt to guard stack red zone failed.");
2695   }
2696 }
2697 
2698 void JavaThread::disable_stack_red_zone() {
2699   // The base notation is from the stacks point of view, growing downward.
2700   // We need to adjust it to work correctly with guard_memory()
2701   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2702   address base = stack_red_zone_base() - stack_red_zone_size();
2703   if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2704     warning("Attempt to unguard stack red zone failed.");
2705   }
2706 }
2707 
2708 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2709   // ignore is there is no stack
2710   if (!has_last_Java_frame()) return;
2711   // traverse the stack frames. Starts from top frame.
2712   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2713     frame* fr = fst.current();
2714     f(fr, fst.register_map());
2715   }
2716 }
2717 
2718 
2719 #ifndef PRODUCT
2720 // Deoptimization
2721 // Function for testing deoptimization
2722 void JavaThread::deoptimize() {
2723   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2724   StackFrameStream fst(this, UseBiasedLocking);
2725   bool deopt = false;           // Dump stack only if a deopt actually happens.
2726   bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2727   // Iterate over all frames in the thread and deoptimize
2728   for (; !fst.is_done(); fst.next()) {
2729     if (fst.current()->can_be_deoptimized()) {
2730 
2731       if (only_at) {
2732         // Deoptimize only at particular bcis.  DeoptimizeOnlyAt
2733         // consists of comma or carriage return separated numbers so
2734         // search for the current bci in that string.
2735         address pc = fst.current()->pc();
2736         nmethod* nm =  (nmethod*) fst.current()->cb();
2737         ScopeDesc* sd = nm->scope_desc_at(pc);
2738         char buffer[8];
2739         jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2740         size_t len = strlen(buffer);
2741         const char * found = strstr(DeoptimizeOnlyAt, buffer);
2742         while (found != NULL) {
2743           if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2744               (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2745             // Check that the bci found is bracketed by terminators.
2746             break;
2747           }
2748           found = strstr(found + 1, buffer);
2749         }
2750         if (!found) {
2751           continue;
2752         }
2753       }
2754 
2755       if (DebugDeoptimization && !deopt) {
2756         deopt = true; // One-time only print before deopt
2757         tty->print_cr("[BEFORE Deoptimization]");
2758         trace_frames();
2759         trace_stack();
2760       }
2761       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2762     }
2763   }
2764 
2765   if (DebugDeoptimization && deopt) {
2766     tty->print_cr("[AFTER Deoptimization]");
2767     trace_frames();
2768   }
2769 }
2770 
2771 
2772 // Make zombies
2773 void JavaThread::make_zombies() {
2774   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2775     if (fst.current()->can_be_deoptimized()) {
2776       // it is a Java nmethod
2777       nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2778       nm->make_not_entrant();
2779     }
2780   }
2781 }
2782 #endif // PRODUCT
2783 
2784 
2785 void JavaThread::deoptimized_wrt_marked_nmethods() {
2786   if (!has_last_Java_frame()) return;
2787   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2788   StackFrameStream fst(this, UseBiasedLocking);
2789   for (; !fst.is_done(); fst.next()) {
2790     if (fst.current()->should_be_deoptimized()) {
2791       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2792     }
2793   }
2794 }
2795 
2796 
2797 // If the caller is a NamedThread, then remember, in the current scope,
2798 // the given JavaThread in its _processed_thread field.
2799 class RememberProcessedThread: public StackObj {
2800   NamedThread* _cur_thr;
2801  public:
2802   RememberProcessedThread(JavaThread* jthr) {
2803     Thread* thread = Thread::current();
2804     if (thread->is_Named_thread()) {
2805       _cur_thr = (NamedThread *)thread;
2806       _cur_thr->set_processed_thread(jthr);
2807     } else {
2808       _cur_thr = NULL;
2809     }
2810   }
2811 
2812   ~RememberProcessedThread() {
2813     if (_cur_thr) {
2814       _cur_thr->set_processed_thread(NULL);
2815     }
2816   }
2817 };
2818 
2819 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2820   // Verify that the deferred card marks have been flushed.
2821   assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2822 
2823   // Traverse the GCHandles
2824   Thread::oops_do(f, cf);
2825 
2826   JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);)
2827 
2828   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2829          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2830 
2831   if (has_last_Java_frame()) {
2832     // Record JavaThread to GC thread
2833     RememberProcessedThread rpt(this);
2834 
2835     // Traverse the privileged stack
2836     if (_privileged_stack_top != NULL) {
2837       _privileged_stack_top->oops_do(f);
2838     }
2839 
2840     // traverse the registered growable array
2841     if (_array_for_gc != NULL) {
2842       for (int index = 0; index < _array_for_gc->length(); index++) {
2843         f->do_oop(_array_for_gc->adr_at(index));
2844       }
2845     }
2846 
2847     // Traverse the monitor chunks
2848     for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2849       chunk->oops_do(f);
2850     }
2851 
2852     // Traverse the execution stack
2853     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2854       fst.current()->oops_do(f, cf, fst.register_map());
2855     }
2856   }
2857 
2858   // callee_target is never live across a gc point so NULL it here should
2859   // it still contain a methdOop.
2860 
2861   set_callee_target(NULL);
2862 
2863   assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2864   // If we have deferred set_locals there might be oops waiting to be
2865   // written
2866   GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2867   if (list != NULL) {
2868     for (int i = 0; i < list->length(); i++) {
2869       list->at(i)->oops_do(f);
2870     }
2871   }
2872 
2873   // Traverse instance variables at the end since the GC may be moving things
2874   // around using this function
2875   f->do_oop((oop*) &_threadObj);
2876   f->do_oop((oop*) &_vm_result);
2877   f->do_oop((oop*) &_exception_oop);
2878   f->do_oop((oop*) &_pending_async_exception);
2879 
2880   if (jvmti_thread_state() != NULL) {
2881     jvmti_thread_state()->oops_do(f);
2882   }
2883 }
2884 
2885 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2886   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2887          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2888 
2889   if (has_last_Java_frame()) {
2890     // Traverse the execution stack
2891     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2892       fst.current()->nmethods_do(cf);
2893     }
2894   }
2895 }
2896 
2897 void JavaThread::metadata_do(void f(Metadata*)) {
2898   if (has_last_Java_frame()) {
2899     // Traverse the execution stack to call f() on the methods in the stack
2900     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2901       fst.current()->metadata_do(f);
2902     }
2903   } else if (is_Compiler_thread()) {
2904     // need to walk ciMetadata in current compile tasks to keep alive.
2905     CompilerThread* ct = (CompilerThread*)this;
2906     if (ct->env() != NULL) {
2907       ct->env()->metadata_do(f);
2908     }
2909     CompileTask* task = ct->task();
2910     if (task != NULL) {
2911       task->metadata_do(f);
2912     }
2913   }
2914 }
2915 
2916 // Printing
2917 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2918   switch (_thread_state) {
2919   case _thread_uninitialized:     return "_thread_uninitialized";
2920   case _thread_new:               return "_thread_new";
2921   case _thread_new_trans:         return "_thread_new_trans";
2922   case _thread_in_native:         return "_thread_in_native";
2923   case _thread_in_native_trans:   return "_thread_in_native_trans";
2924   case _thread_in_vm:             return "_thread_in_vm";
2925   case _thread_in_vm_trans:       return "_thread_in_vm_trans";
2926   case _thread_in_Java:           return "_thread_in_Java";
2927   case _thread_in_Java_trans:     return "_thread_in_Java_trans";
2928   case _thread_blocked:           return "_thread_blocked";
2929   case _thread_blocked_trans:     return "_thread_blocked_trans";
2930   default:                        return "unknown thread state";
2931   }
2932 }
2933 
2934 #ifndef PRODUCT
2935 void JavaThread::print_thread_state_on(outputStream *st) const {
2936   st->print_cr("   JavaThread state: %s", _get_thread_state_name(_thread_state));
2937 };
2938 void JavaThread::print_thread_state() const {
2939   print_thread_state_on(tty);
2940 }
2941 #endif // PRODUCT
2942 
2943 // Called by Threads::print() for VM_PrintThreads operation
2944 void JavaThread::print_on(outputStream *st) const {
2945   st->print_raw("\"");
2946   st->print_raw(get_thread_name());
2947   st->print_raw("\" ");
2948   oop thread_oop = threadObj();
2949   if (thread_oop != NULL) {
2950     st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
2951     if (java_lang_Thread::is_daemon(thread_oop))  st->print("daemon ");
2952     st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2953   }
2954   Thread::print_on(st);
2955   // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2956   st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2957   if (thread_oop != NULL) {
2958     st->print_cr("   java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2959   }
2960 #ifndef PRODUCT
2961   print_thread_state_on(st);
2962   _safepoint_state->print_on(st);
2963 #endif // PRODUCT
2964   if (is_Compiler_thread()) {
2965     CompileTask *task = ((CompilerThread*)this)->task();
2966     if (task != NULL) {
2967       st->print("   Compiling: ");
2968       task->print(st, NULL, true, false);
2969     } else {
2970       st->print("   No compile task");
2971     }
2972     st->cr();
2973   }
2974 }
2975 
2976 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2977   st->print("%s", get_thread_name_string(buf, buflen));
2978 }
2979 
2980 // Called by fatal error handler. The difference between this and
2981 // JavaThread::print() is that we can't grab lock or allocate memory.
2982 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2983   st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2984   oop thread_obj = threadObj();
2985   if (thread_obj != NULL) {
2986     if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2987   }
2988   st->print(" [");
2989   st->print("%s", _get_thread_state_name(_thread_state));
2990   if (osthread()) {
2991     st->print(", id=%d", osthread()->thread_id());
2992   }
2993   st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2994             p2i(stack_end()), p2i(stack_base()));
2995   st->print("]");
2996 
2997   if (_threads_hazard_ptr != NULL) {
2998     st->print(" _threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr));
2999   }
3000   if (_nested_threads_hazard_ptr != NULL) {
3001     print_nested_threads_hazard_ptrs_on(st);
3002   }
3003   return;
3004 }
3005 
3006 // Verification
3007 
3008 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
3009 
3010 void JavaThread::verify() {
3011   // Verify oops in the thread.
3012   oops_do(&VerifyOopClosure::verify_oop, NULL);
3013 
3014   // Verify the stack frames.
3015   frames_do(frame_verify);
3016 }
3017 
3018 // CR 6300358 (sub-CR 2137150)
3019 // Most callers of this method assume that it can't return NULL but a
3020 // thread may not have a name whilst it is in the process of attaching to
3021 // the VM - see CR 6412693, and there are places where a JavaThread can be
3022 // seen prior to having it's threadObj set (eg JNI attaching threads and
3023 // if vm exit occurs during initialization). These cases can all be accounted
3024 // for such that this method never returns NULL.
3025 const char* JavaThread::get_thread_name() const {
3026 #ifdef ASSERT
3027   // early safepoints can hit while current thread does not yet have TLS
3028   if (!SafepointSynchronize::is_at_safepoint()) {
3029     Thread *cur = Thread::current();
3030     if (!(cur->is_Java_thread() && cur == this)) {
3031       // Current JavaThreads are allowed to get their own name without
3032       // the Threads_lock.
3033       assert_locked_or_safepoint(Threads_lock);
3034     }
3035   }
3036 #endif // ASSERT
3037   return get_thread_name_string();
3038 }
3039 
3040 // Returns a non-NULL representation of this thread's name, or a suitable
3041 // descriptive string if there is no set name
3042 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3043   const char* name_str;
3044   oop thread_obj = threadObj();
3045   if (thread_obj != NULL) {
3046     oop name = java_lang_Thread::name(thread_obj);
3047     if (name != NULL) {
3048       if (buf == NULL) {
3049         name_str = java_lang_String::as_utf8_string(name);
3050       } else {
3051         name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3052       }
3053     } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3054       name_str = "<no-name - thread is attaching>";
3055     } else {
3056       name_str = Thread::name();
3057     }
3058   } else {
3059     name_str = Thread::name();
3060   }
3061   assert(name_str != NULL, "unexpected NULL thread name");
3062   return name_str;
3063 }
3064 
3065 
3066 const char* JavaThread::get_threadgroup_name() const {
3067   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3068   oop thread_obj = threadObj();
3069   if (thread_obj != NULL) {
3070     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3071     if (thread_group != NULL) {
3072       // ThreadGroup.name can be null
3073       return java_lang_ThreadGroup::name(thread_group);
3074     }
3075   }
3076   return NULL;
3077 }
3078 
3079 const char* JavaThread::get_parent_name() const {
3080   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3081   oop thread_obj = threadObj();
3082   if (thread_obj != NULL) {
3083     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3084     if (thread_group != NULL) {
3085       oop parent = java_lang_ThreadGroup::parent(thread_group);
3086       if (parent != NULL) {
3087         // ThreadGroup.name can be null
3088         return java_lang_ThreadGroup::name(parent);
3089       }
3090     }
3091   }
3092   return NULL;
3093 }
3094 
3095 ThreadPriority JavaThread::java_priority() const {
3096   oop thr_oop = threadObj();
3097   if (thr_oop == NULL) return NormPriority; // Bootstrapping
3098   ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3099   assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3100   return priority;
3101 }
3102 
3103 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3104 
3105   assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3106   // Link Java Thread object <-> C++ Thread
3107 
3108   // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3109   // and put it into a new Handle.  The Handle "thread_oop" can then
3110   // be used to pass the C++ thread object to other methods.
3111 
3112   // Set the Java level thread object (jthread) field of the
3113   // new thread (a JavaThread *) to C++ thread object using the
3114   // "thread_oop" handle.
3115 
3116   // Set the thread field (a JavaThread *) of the
3117   // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3118 
3119   Handle thread_oop(Thread::current(),
3120                     JNIHandles::resolve_non_null(jni_thread));
3121   assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3122          "must be initialized");
3123   set_threadObj(thread_oop());
3124   java_lang_Thread::set_thread(thread_oop(), this);
3125 
3126   if (prio == NoPriority) {
3127     prio = java_lang_Thread::priority(thread_oop());
3128     assert(prio != NoPriority, "A valid priority should be present");
3129   }
3130 
3131   // Push the Java priority down to the native thread; needs Threads_lock
3132   Thread::set_priority(this, prio);
3133 
3134   // Add the new thread to the Threads list and set it in motion.
3135   // We must have threads lock in order to call Threads::add.
3136   // It is crucial that we do not block before the thread is
3137   // added to the Threads list for if a GC happens, then the java_thread oop
3138   // will not be visited by GC.
3139   Threads::add(this);
3140 }
3141 
3142 oop JavaThread::current_park_blocker() {
3143   // Support for JSR-166 locks
3144   oop thread_oop = threadObj();
3145   if (thread_oop != NULL &&
3146       JDK_Version::current().supports_thread_park_blocker()) {
3147     return java_lang_Thread::park_blocker(thread_oop);
3148   }
3149   return NULL;
3150 }
3151 
3152 
3153 void JavaThread::print_stack_on(outputStream* st) {
3154   if (!has_last_Java_frame()) return;
3155   ResourceMark rm;
3156   HandleMark   hm;
3157 
3158   RegisterMap reg_map(this);
3159   vframe* start_vf = last_java_vframe(&reg_map);
3160   int count = 0;
3161   for (vframe* f = start_vf; f != NULL; f = f->sender()) {
3162     if (f->is_java_frame()) {
3163       javaVFrame* jvf = javaVFrame::cast(f);
3164       java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3165 
3166       // Print out lock information
3167       if (JavaMonitorsInStackTrace) {
3168         jvf->print_lock_info_on(st, count);
3169       }
3170     } else {
3171       // Ignore non-Java frames
3172     }
3173 
3174     // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
3175     count++;
3176     if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
3177   }
3178 }
3179 
3180 
3181 // JVMTI PopFrame support
3182 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3183   assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3184   if (in_bytes(size_in_bytes) != 0) {
3185     _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3186     _popframe_preserved_args_size = in_bytes(size_in_bytes);
3187     Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3188   }
3189 }
3190 
3191 void* JavaThread::popframe_preserved_args() {
3192   return _popframe_preserved_args;
3193 }
3194 
3195 ByteSize JavaThread::popframe_preserved_args_size() {
3196   return in_ByteSize(_popframe_preserved_args_size);
3197 }
3198 
3199 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3200   int sz = in_bytes(popframe_preserved_args_size());
3201   assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3202   return in_WordSize(sz / wordSize);
3203 }
3204 
3205 void JavaThread::popframe_free_preserved_args() {
3206   assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3207   FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3208   _popframe_preserved_args = NULL;
3209   _popframe_preserved_args_size = 0;
3210 }
3211 
3212 #ifndef PRODUCT
3213 
3214 void JavaThread::trace_frames() {
3215   tty->print_cr("[Describe stack]");
3216   int frame_no = 1;
3217   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3218     tty->print("  %d. ", frame_no++);
3219     fst.current()->print_value_on(tty, this);
3220     tty->cr();
3221   }
3222 }
3223 
3224 class PrintAndVerifyOopClosure: public OopClosure {
3225  protected:
3226   template <class T> inline void do_oop_work(T* p) {
3227     oop obj = RawAccess<>::oop_load(p);
3228     if (obj == NULL) return;
3229     tty->print(INTPTR_FORMAT ": ", p2i(p));
3230     if (oopDesc::is_oop_or_null(obj)) {
3231       if (obj->is_objArray()) {
3232         tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3233       } else {
3234         obj->print();
3235       }
3236     } else {
3237       tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3238     }
3239     tty->cr();
3240   }
3241  public:
3242   virtual void do_oop(oop* p) { do_oop_work(p); }
3243   virtual void do_oop(narrowOop* p)  { do_oop_work(p); }
3244 };
3245 
3246 
3247 static void oops_print(frame* f, const RegisterMap *map) {
3248   PrintAndVerifyOopClosure print;
3249   f->print_value();
3250   f->oops_do(&print, NULL, (RegisterMap*)map);
3251 }
3252 
3253 // Print our all the locations that contain oops and whether they are
3254 // valid or not.  This useful when trying to find the oldest frame
3255 // where an oop has gone bad since the frame walk is from youngest to
3256 // oldest.
3257 void JavaThread::trace_oops() {
3258   tty->print_cr("[Trace oops]");
3259   frames_do(oops_print);
3260 }
3261 
3262 
3263 #ifdef ASSERT
3264 // Print or validate the layout of stack frames
3265 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3266   ResourceMark rm;
3267   PRESERVE_EXCEPTION_MARK;
3268   FrameValues values;
3269   int frame_no = 0;
3270   for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3271     fst.current()->describe(values, ++frame_no);
3272     if (depth == frame_no) break;
3273   }
3274   if (validate_only) {
3275     values.validate();
3276   } else {
3277     tty->print_cr("[Describe stack layout]");
3278     values.print(this);
3279   }
3280 }
3281 #endif
3282 
3283 void JavaThread::trace_stack_from(vframe* start_vf) {
3284   ResourceMark rm;
3285   int vframe_no = 1;
3286   for (vframe* f = start_vf; f; f = f->sender()) {
3287     if (f->is_java_frame()) {
3288       javaVFrame::cast(f)->print_activation(vframe_no++);
3289     } else {
3290       f->print();
3291     }
3292     if (vframe_no > StackPrintLimit) {
3293       tty->print_cr("...<more frames>...");
3294       return;
3295     }
3296   }
3297 }
3298 
3299 
3300 void JavaThread::trace_stack() {
3301   if (!has_last_Java_frame()) return;
3302   ResourceMark rm;
3303   HandleMark   hm;
3304   RegisterMap reg_map(this);
3305   trace_stack_from(last_java_vframe(&reg_map));
3306 }
3307 
3308 
3309 #endif // PRODUCT
3310 
3311 
3312 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3313   assert(reg_map != NULL, "a map must be given");
3314   frame f = last_frame();
3315   for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3316     if (vf->is_java_frame()) return javaVFrame::cast(vf);
3317   }
3318   return NULL;
3319 }
3320 
3321 
3322 Klass* JavaThread::security_get_caller_class(int depth) {
3323   vframeStream vfst(this);
3324   vfst.security_get_caller_frame(depth);
3325   if (!vfst.at_end()) {
3326     return vfst.method()->method_holder();
3327   }
3328   return NULL;
3329 }
3330 
3331 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3332   assert(thread->is_Compiler_thread(), "must be compiler thread");
3333   CompileBroker::compiler_thread_loop();
3334 }
3335 
3336 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3337   NMethodSweeper::sweeper_loop();
3338 }
3339 
3340 // Create a CompilerThread
3341 CompilerThread::CompilerThread(CompileQueue* queue,
3342                                CompilerCounters* counters)
3343                                : JavaThread(&compiler_thread_entry) {
3344   _env   = NULL;
3345   _log   = NULL;
3346   _task  = NULL;
3347   _queue = queue;
3348   _counters = counters;
3349   _buffer_blob = NULL;
3350   _compiler = NULL;
3351 
3352   // Compiler uses resource area for compilation, let's bias it to mtCompiler
3353   resource_area()->bias_to(mtCompiler);
3354 
3355 #ifndef PRODUCT
3356   _ideal_graph_printer = NULL;
3357 #endif
3358 }
3359 
3360 bool CompilerThread::can_call_java() const {
3361   return _compiler != NULL && _compiler->is_jvmci();
3362 }
3363 
3364 // Create sweeper thread
3365 CodeCacheSweeperThread::CodeCacheSweeperThread()
3366 : JavaThread(&sweeper_thread_entry) {
3367   _scanned_compiled_method = NULL;
3368 }
3369 
3370 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3371   JavaThread::oops_do(f, cf);
3372   if (_scanned_compiled_method != NULL && cf != NULL) {
3373     // Safepoints can occur when the sweeper is scanning an nmethod so
3374     // process it here to make sure it isn't unloaded in the middle of
3375     // a scan.
3376     cf->do_code_blob(_scanned_compiled_method);
3377   }
3378 }
3379 
3380 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3381   JavaThread::nmethods_do(cf);
3382   if (_scanned_compiled_method != NULL && cf != NULL) {
3383     // Safepoints can occur when the sweeper is scanning an nmethod so
3384     // process it here to make sure it isn't unloaded in the middle of
3385     // a scan.
3386     cf->do_code_blob(_scanned_compiled_method);
3387   }
3388 }
3389 
3390 
3391 // ======= Threads ========
3392 
3393 // The Threads class links together all active threads, and provides
3394 // operations over all threads. It is protected by the Threads_lock,
3395 // which is also used in other global contexts like safepointing.
3396 // ThreadsListHandles are used to safely perform operations on one
3397 // or more threads without the risk of the thread exiting during the
3398 // operation.
3399 //
3400 // Note: The Threads_lock is currently more widely used than we
3401 // would like. We are actively migrating Threads_lock uses to other
3402 // mechanisms in order to reduce Threads_lock contention.
3403 
3404 JavaThread* Threads::_thread_list = NULL;
3405 int         Threads::_number_of_threads = 0;
3406 int         Threads::_number_of_non_daemon_threads = 0;
3407 int         Threads::_return_code = 0;
3408 int         Threads::_thread_claim_parity = 0;
3409 size_t      JavaThread::_stack_size_at_create = 0;
3410 
3411 #ifdef ASSERT
3412 bool        Threads::_vm_complete = false;
3413 #endif
3414 
3415 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
3416   Prefetch::read((void*)addr, prefetch_interval);
3417   return *addr;
3418 }
3419 
3420 // Possibly the ugliest for loop the world has seen. C++ does not allow
3421 // multiple types in the declaration section of the for loop. In this case
3422 // we are only dealing with pointers and hence can cast them. It looks ugly
3423 // but macros are ugly and therefore it's fine to make things absurdly ugly.
3424 #define DO_JAVA_THREADS(LIST, X)                                                                                          \
3425     for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes,                           \
3426              *MACRO_list = (JavaThread*)(LIST),                                                                           \
3427              **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(),  \
3428              **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(),                                     \
3429              *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval);                 \
3430          MACRO_current_p != MACRO_end;                                                                                    \
3431          MACRO_current_p++,                                                                                               \
3432              X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval))
3433 
3434 // All JavaThreads
3435 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X)
3436 
3437 // All non-JavaThreads (i.e., every non-JavaThread in the system).
3438 void Threads::non_java_threads_do(ThreadClosure* tc) {
3439   // Someday we could have a table or list of all non-JavaThreads.
3440   // For now, just manually iterate through them.
3441   tc->do_thread(VMThread::vm_thread());
3442   if (Universe::heap() != NULL) {
3443     Universe::heap()->gc_threads_do(tc);
3444   }
3445   WatcherThread *wt = WatcherThread::watcher_thread();
3446   // Strictly speaking, the following NULL check isn't sufficient to make sure
3447   // the data for WatcherThread is still valid upon being examined. However,
3448   // considering that WatchThread terminates when the VM is on the way to
3449   // exit at safepoint, the chance of the above is extremely small. The right
3450   // way to prevent termination of WatcherThread would be to acquire
3451   // Terminator_lock, but we can't do that without violating the lock rank
3452   // checking in some cases.
3453   if (wt != NULL) {
3454     tc->do_thread(wt);
3455   }
3456 
3457 #if INCLUDE_TRACE
3458   Thread* sampler_thread = TracingExport::sampler_thread_acquire();
3459   if (sampler_thread != NULL) {
3460     tc->do_thread(sampler_thread);
3461   }
3462 #endif
3463 
3464   // If CompilerThreads ever become non-JavaThreads, add them here
3465 }
3466 
3467 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system).
3468 void Threads::threads_do(ThreadClosure* tc) {
3469   assert_locked_or_safepoint(Threads_lock);
3470   // ALL_JAVA_THREADS iterates through all JavaThreads.
3471   ALL_JAVA_THREADS(p) {
3472     tc->do_thread(p);
3473   }
3474   non_java_threads_do(tc);
3475 }
3476 
3477 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
3478   int cp = Threads::thread_claim_parity();
3479   ALL_JAVA_THREADS(p) {
3480     if (p->claim_oops_do(is_par, cp)) {
3481       tc->do_thread(p);
3482     }
3483   }
3484   VMThread* vmt = VMThread::vm_thread();
3485   if (vmt->claim_oops_do(is_par, cp)) {
3486     tc->do_thread(vmt);
3487   }
3488 }
3489 
3490 // The system initialization in the library has three phases.
3491 //
3492 // Phase 1: java.lang.System class initialization
3493 //     java.lang.System is a primordial class loaded and initialized
3494 //     by the VM early during startup.  java.lang.System.<clinit>
3495 //     only does registerNatives and keeps the rest of the class
3496 //     initialization work later until thread initialization completes.
3497 //
3498 //     System.initPhase1 initializes the system properties, the static
3499 //     fields in, out, and err. Set up java signal handlers, OS-specific
3500 //     system settings, and thread group of the main thread.
3501 static void call_initPhase1(TRAPS) {
3502   Klass* klass =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3503   JavaValue result(T_VOID);
3504   JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3505                                          vmSymbols::void_method_signature(), CHECK);
3506 }
3507 
3508 // Phase 2. Module system initialization
3509 //     This will initialize the module system.  Only java.base classes
3510 //     can be loaded until phase 2 completes.
3511 //
3512 //     Call System.initPhase2 after the compiler initialization and jsr292
3513 //     classes get initialized because module initialization runs a lot of java
3514 //     code, that for performance reasons, should be compiled.  Also, this will
3515 //     enable the startup code to use lambda and other language features in this
3516 //     phase and onward.
3517 //
3518 //     After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3519 static void call_initPhase2(TRAPS) {
3520   TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3521 
3522   Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3523 
3524   JavaValue result(T_INT);
3525   JavaCallArguments args;
3526   args.push_int(DisplayVMOutputToStderr);
3527   args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3528   JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3529                                          vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3530   if (result.get_jint() != JNI_OK) {
3531     vm_exit_during_initialization(); // no message or exception
3532   }
3533 
3534   universe_post_module_init();
3535 }
3536 
3537 // Phase 3. final setup - set security manager, system class loader and TCCL
3538 //
3539 //     This will instantiate and set the security manager, set the system class
3540 //     loader as well as the thread context class loader.  The security manager
3541 //     and system class loader may be a custom class loaded from -Xbootclasspath/a,
3542 //     other modules or the application's classpath.
3543 static void call_initPhase3(TRAPS) {
3544   Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3545   JavaValue result(T_VOID);
3546   JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3547                                          vmSymbols::void_method_signature(), CHECK);
3548 }
3549 
3550 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3551   TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3552 
3553   if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3554     create_vm_init_libraries();
3555   }
3556 
3557   initialize_class(vmSymbols::java_lang_String(), CHECK);
3558 
3559   // Inject CompactStrings value after the static initializers for String ran.
3560   java_lang_String::set_compact_strings(CompactStrings);
3561 
3562   // Initialize java_lang.System (needed before creating the thread)
3563   initialize_class(vmSymbols::java_lang_System(), CHECK);
3564   // The VM creates & returns objects of this class. Make sure it's initialized.
3565   initialize_class(vmSymbols::java_lang_Class(), CHECK);
3566   initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3567   Handle thread_group = create_initial_thread_group(CHECK);
3568   Universe::set_main_thread_group(thread_group());
3569   initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3570   oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3571   main_thread->set_threadObj(thread_object);
3572   // Set thread status to running since main thread has
3573   // been started and running.
3574   java_lang_Thread::set_thread_status(thread_object,
3575                                       java_lang_Thread::RUNNABLE);
3576 
3577   // The VM creates objects of this class.
3578   initialize_class(vmSymbols::java_lang_Module(), CHECK);
3579 
3580   // The VM preresolves methods to these classes. Make sure that they get initialized
3581   initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3582   initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3583 
3584   // Phase 1 of the system initialization in the library, java.lang.System class initialization
3585   call_initPhase1(CHECK);
3586 
3587   // get the Java runtime name after java.lang.System is initialized
3588   JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3589   JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3590 
3591   // an instance of OutOfMemory exception has been allocated earlier
3592   initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3593   initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3594   initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3595   initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3596   initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3597   initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3598   initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3599   initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3600 }
3601 
3602 void Threads::initialize_jsr292_core_classes(TRAPS) {
3603   TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3604 
3605   initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3606   initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3607   initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3608   initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3609 }
3610 
3611 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3612   extern void JDK_Version_init();
3613 
3614   // Preinitialize version info.
3615   VM_Version::early_initialize();
3616 
3617   // Check version
3618   if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3619 
3620   // Initialize library-based TLS
3621   ThreadLocalStorage::init();
3622 
3623   // Initialize the output stream module
3624   ostream_init();
3625 
3626   // Process java launcher properties.
3627   Arguments::process_sun_java_launcher_properties(args);
3628 
3629   // Initialize the os module
3630   os::init();
3631 
3632   // Record VM creation timing statistics
3633   TraceVmCreationTime create_vm_timer;
3634   create_vm_timer.start();
3635 
3636   // Initialize system properties.
3637   Arguments::init_system_properties();
3638 
3639   // So that JDK version can be used as a discriminator when parsing arguments
3640   JDK_Version_init();
3641 
3642   // Update/Initialize System properties after JDK version number is known
3643   Arguments::init_version_specific_system_properties();
3644 
3645   // Make sure to initialize log configuration *before* parsing arguments
3646   LogConfiguration::initialize(create_vm_timer.begin_time());
3647 
3648   // Parse arguments
3649   // Note: this internally calls os::init_container_support()
3650   jint parse_result = Arguments::parse(args);
3651   if (parse_result != JNI_OK) return parse_result;
3652 
3653   os::init_before_ergo();
3654 
3655   jint ergo_result = Arguments::apply_ergo();
3656   if (ergo_result != JNI_OK) return ergo_result;
3657 
3658   // Final check of all ranges after ergonomics which may change values.
3659   if (!CommandLineFlagRangeList::check_ranges()) {
3660     return JNI_EINVAL;
3661   }
3662 
3663   // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3664   bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo);
3665   if (!constraint_result) {
3666     return JNI_EINVAL;
3667   }
3668 
3669   CommandLineFlagWriteableList::mark_startup();
3670 
3671   if (PauseAtStartup) {
3672     os::pause();
3673   }
3674 
3675   HOTSPOT_VM_INIT_BEGIN();
3676 
3677   // Timing (must come after argument parsing)
3678   TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3679 
3680 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT
3681   // Initialize assert poison page mechanism.
3682   if (ShowRegistersOnAssert) {
3683     initialize_assert_poison();
3684   }
3685 #endif // CAN_SHOW_REGISTERS_ON_ASSERT
3686 
3687   // Initialize the os module after parsing the args
3688   jint os_init_2_result = os::init_2();
3689   if (os_init_2_result != JNI_OK) return os_init_2_result;
3690 
3691   SafepointMechanism::initialize();
3692 
3693   jint adjust_after_os_result = Arguments::adjust_after_os();
3694   if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3695 
3696   // Initialize output stream logging
3697   ostream_init_log();
3698 
3699   // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3700   // Must be before create_vm_init_agents()
3701   if (Arguments::init_libraries_at_startup()) {
3702     convert_vm_init_libraries_to_agents();
3703   }
3704 
3705   // Launch -agentlib/-agentpath and converted -Xrun agents
3706   if (Arguments::init_agents_at_startup()) {
3707     create_vm_init_agents();
3708   }
3709 
3710   // Initialize Threads state
3711   _thread_list = NULL;
3712   _number_of_threads = 0;
3713   _number_of_non_daemon_threads = 0;
3714 
3715   // Initialize global data structures and create system classes in heap
3716   vm_init_globals();
3717 
3718 #if INCLUDE_JVMCI
3719   if (JVMCICounterSize > 0) {
3720     JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3721     memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3722   } else {
3723     JavaThread::_jvmci_old_thread_counters = NULL;
3724   }
3725 #endif // INCLUDE_JVMCI
3726 
3727   // Attach the main thread to this os thread
3728   JavaThread* main_thread = new JavaThread();
3729   main_thread->set_thread_state(_thread_in_vm);
3730   main_thread->initialize_thread_current();
3731   // must do this before set_active_handles
3732   main_thread->record_stack_base_and_size();
3733   main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3734 
3735   if (!main_thread->set_as_starting_thread()) {
3736     vm_shutdown_during_initialization(
3737                                       "Failed necessary internal allocation. Out of swap space");
3738     main_thread->smr_delete();
3739     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3740     return JNI_ENOMEM;
3741   }
3742 
3743   // Enable guard page *after* os::create_main_thread(), otherwise it would
3744   // crash Linux VM, see notes in os_linux.cpp.
3745   main_thread->create_stack_guard_pages();
3746 
3747   // Initialize Java-Level synchronization subsystem
3748   ObjectMonitor::Initialize();
3749 
3750   // Initialize global modules
3751   jint status = init_globals();
3752   if (status != JNI_OK) {
3753     main_thread->smr_delete();
3754     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3755     return status;
3756   }
3757 
3758   if (TRACE_INITIALIZE() != JNI_OK) {
3759     vm_exit_during_initialization("Failed to initialize tracing backend");
3760   }
3761 
3762   // Should be done after the heap is fully created
3763   main_thread->cache_global_variables();
3764 
3765   HandleMark hm;
3766 
3767   { MutexLocker mu(Threads_lock);
3768     Threads::add(main_thread);
3769   }
3770 
3771   // Any JVMTI raw monitors entered in onload will transition into
3772   // real raw monitor. VM is setup enough here for raw monitor enter.
3773   JvmtiExport::transition_pending_onload_raw_monitors();
3774 
3775   // Create the VMThread
3776   { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3777 
3778   VMThread::create();
3779     Thread* vmthread = VMThread::vm_thread();
3780 
3781     if (!os::create_thread(vmthread, os::vm_thread)) {
3782       vm_exit_during_initialization("Cannot create VM thread. "
3783                                     "Out of system resources.");
3784     }
3785 
3786     // Wait for the VM thread to become ready, and VMThread::run to initialize
3787     // Monitors can have spurious returns, must always check another state flag
3788     {
3789       MutexLocker ml(Notify_lock);
3790       os::start_thread(vmthread);
3791       while (vmthread->active_handles() == NULL) {
3792         Notify_lock->wait();
3793       }
3794     }
3795   }
3796 
3797   assert(Universe::is_fully_initialized(), "not initialized");
3798   if (VerifyDuringStartup) {
3799     // Make sure we're starting with a clean slate.
3800     VM_Verify verify_op;
3801     VMThread::execute(&verify_op);
3802   }
3803 
3804   Thread* THREAD = Thread::current();
3805 
3806   // Always call even when there are not JVMTI environments yet, since environments
3807   // may be attached late and JVMTI must track phases of VM execution
3808   JvmtiExport::enter_early_start_phase();
3809 
3810   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3811   JvmtiExport::post_early_vm_start();
3812 
3813   initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3814 
3815   // We need this for ClassDataSharing - the initial vm.info property is set
3816   // with the default value of CDS "sharing" which may be reset through
3817   // command line options.
3818   reset_vm_info_property(CHECK_JNI_ERR);
3819 
3820   quicken_jni_functions();
3821 
3822   // No more stub generation allowed after that point.
3823   StubCodeDesc::freeze();
3824 
3825   // Set flag that basic initialization has completed. Used by exceptions and various
3826   // debug stuff, that does not work until all basic classes have been initialized.
3827   set_init_completed();
3828 
3829   LogConfiguration::post_initialize();
3830   Metaspace::post_initialize();
3831 
3832   HOTSPOT_VM_INIT_END();
3833 
3834   // record VM initialization completion time
3835 #if INCLUDE_MANAGEMENT
3836   Management::record_vm_init_completed();
3837 #endif // INCLUDE_MANAGEMENT
3838 
3839   // Signal Dispatcher needs to be started before VMInit event is posted
3840   os::signal_init(CHECK_JNI_ERR);
3841 
3842   // Start Attach Listener if +StartAttachListener or it can't be started lazily
3843   if (!DisableAttachMechanism) {
3844     AttachListener::vm_start();
3845     if (StartAttachListener || AttachListener::init_at_startup()) {
3846       AttachListener::init();
3847     }
3848   }
3849 
3850   // Launch -Xrun agents
3851   // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3852   // back-end can launch with -Xdebug -Xrunjdwp.
3853   if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3854     create_vm_init_libraries();
3855   }
3856 
3857   if (CleanChunkPoolAsync) {
3858     Chunk::start_chunk_pool_cleaner_task();
3859   }
3860 
3861   // initialize compiler(s)
3862 #if defined(COMPILER1) || COMPILER2_OR_JVMCI
3863 #if INCLUDE_JVMCI
3864   bool force_JVMCI_intialization = false;
3865   if (EnableJVMCI) {
3866     // Initialize JVMCI eagerly when it is explicitly requested.
3867     // Or when JVMCIPrintProperties is enabled.
3868     // The JVMCI Java initialization code will read this flag and
3869     // do the printing if it's set.
3870     force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties;
3871 
3872     if (!force_JVMCI_intialization) {
3873       // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3874       // compilations via JVMCI will not actually block until JVMCI is initialized.
3875       force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3876     }
3877   }
3878 #endif
3879   CompileBroker::compilation_init_phase1(CHECK_JNI_ERR);
3880   // Postpone completion of compiler initialization to after JVMCI
3881   // is initialized to avoid timeouts of blocking compilations.
3882   if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) {
3883     CompileBroker::compilation_init_phase2();
3884   }
3885 #endif
3886 
3887   // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3888   // It is done after compilers are initialized, because otherwise compilations of
3889   // signature polymorphic MH intrinsics can be missed
3890   // (see SystemDictionary::find_method_handle_intrinsic).
3891   initialize_jsr292_core_classes(CHECK_JNI_ERR);
3892 
3893   // This will initialize the module system.  Only java.base classes can be
3894   // loaded until phase 2 completes
3895   call_initPhase2(CHECK_JNI_ERR);
3896 
3897   // Always call even when there are not JVMTI environments yet, since environments
3898   // may be attached late and JVMTI must track phases of VM execution
3899   JvmtiExport::enter_start_phase();
3900 
3901   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3902   JvmtiExport::post_vm_start();
3903 
3904   // Final system initialization including security manager and system class loader
3905   call_initPhase3(CHECK_JNI_ERR);
3906 
3907   // cache the system and platform class loaders
3908   SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
3909 
3910 #if INCLUDE_CDS
3911   if (DumpSharedSpaces) {
3912     // capture the module path info from the ModuleEntryTable
3913     ClassLoader::initialize_module_path(THREAD);
3914   }
3915 #endif
3916 
3917 #if INCLUDE_JVMCI
3918   if (force_JVMCI_intialization) {
3919     JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
3920     CompileBroker::compilation_init_phase2();
3921   }
3922 #endif
3923 
3924   // Always call even when there are not JVMTI environments yet, since environments
3925   // may be attached late and JVMTI must track phases of VM execution
3926   JvmtiExport::enter_live_phase();
3927 
3928   // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3929   JvmtiExport::post_vm_initialized();
3930 
3931   if (TRACE_START() != JNI_OK) {
3932     vm_exit_during_initialization("Failed to start tracing backend.");
3933   }
3934 
3935 #if INCLUDE_MANAGEMENT
3936   Management::initialize(THREAD);
3937 
3938   if (HAS_PENDING_EXCEPTION) {
3939     // management agent fails to start possibly due to
3940     // configuration problem and is responsible for printing
3941     // stack trace if appropriate. Simply exit VM.
3942     vm_exit(1);
3943   }
3944 #endif // INCLUDE_MANAGEMENT
3945 
3946   if (MemProfiling)                   MemProfiler::engage();
3947   StatSampler::engage();
3948   if (CheckJNICalls)                  JniPeriodicChecker::engage();
3949 
3950   BiasedLocking::init();
3951 
3952 #if INCLUDE_RTM_OPT
3953   RTMLockingCounters::init();
3954 #endif
3955 
3956   if (JDK_Version::current().post_vm_init_hook_enabled()) {
3957     call_postVMInitHook(THREAD);
3958     // The Java side of PostVMInitHook.run must deal with all
3959     // exceptions and provide means of diagnosis.
3960     if (HAS_PENDING_EXCEPTION) {
3961       CLEAR_PENDING_EXCEPTION;
3962     }
3963   }
3964 
3965   {
3966     MutexLocker ml(PeriodicTask_lock);
3967     // Make sure the WatcherThread can be started by WatcherThread::start()
3968     // or by dynamic enrollment.
3969     WatcherThread::make_startable();
3970     // Start up the WatcherThread if there are any periodic tasks
3971     // NOTE:  All PeriodicTasks should be registered by now. If they
3972     //   aren't, late joiners might appear to start slowly (we might
3973     //   take a while to process their first tick).
3974     if (PeriodicTask::num_tasks() > 0) {
3975       WatcherThread::start();
3976     }
3977   }
3978 
3979   create_vm_timer.end();
3980 #ifdef ASSERT
3981   _vm_complete = true;
3982 #endif
3983 
3984   if (DumpSharedSpaces) {
3985     MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3986     ShouldNotReachHere();
3987   }
3988 
3989   return JNI_OK;
3990 }
3991 
3992 // type for the Agent_OnLoad and JVM_OnLoad entry points
3993 extern "C" {
3994   typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3995 }
3996 // Find a command line agent library and return its entry point for
3997 //         -agentlib:  -agentpath:   -Xrun
3998 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3999 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
4000                                     const char *on_load_symbols[],
4001                                     size_t num_symbol_entries) {
4002   OnLoadEntry_t on_load_entry = NULL;
4003   void *library = NULL;
4004 
4005   if (!agent->valid()) {
4006     char buffer[JVM_MAXPATHLEN];
4007     char ebuf[1024] = "";
4008     const char *name = agent->name();
4009     const char *msg = "Could not find agent library ";
4010 
4011     // First check to see if agent is statically linked into executable
4012     if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
4013       library = agent->os_lib();
4014     } else if (agent->is_absolute_path()) {
4015       library = os::dll_load(name, ebuf, sizeof ebuf);
4016       if (library == NULL) {
4017         const char *sub_msg = " in absolute path, with error: ";
4018         size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
4019         char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4020         jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4021         // If we can't find the agent, exit.
4022         vm_exit_during_initialization(buf, NULL);
4023         FREE_C_HEAP_ARRAY(char, buf);
4024       }
4025     } else {
4026       // Try to load the agent from the standard dll directory
4027       if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
4028                              name)) {
4029         library = os::dll_load(buffer, ebuf, sizeof ebuf);
4030       }
4031       if (library == NULL) { // Try the library path directory.
4032         if (os::dll_build_name(buffer, sizeof(buffer), name)) {
4033           library = os::dll_load(buffer, ebuf, sizeof ebuf);
4034         }
4035         if (library == NULL) {
4036           const char *sub_msg = " on the library path, with error: ";
4037           const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image.";
4038 
4039           size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) +
4040                        strlen(ebuf) + strlen(sub_msg2) + 1;
4041           char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4042           if (!agent->is_instrument_lib()) {
4043             jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4044           } else {
4045             jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2);
4046           }
4047           // If we can't find the agent, exit.
4048           vm_exit_during_initialization(buf, NULL);
4049           FREE_C_HEAP_ARRAY(char, buf);
4050         }
4051       }
4052     }
4053     agent->set_os_lib(library);
4054     agent->set_valid();
4055   }
4056 
4057   // Find the OnLoad function.
4058   on_load_entry =
4059     CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
4060                                                           false,
4061                                                           on_load_symbols,
4062                                                           num_symbol_entries));
4063   return on_load_entry;
4064 }
4065 
4066 // Find the JVM_OnLoad entry point
4067 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
4068   const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
4069   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4070 }
4071 
4072 // Find the Agent_OnLoad entry point
4073 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
4074   const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
4075   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4076 }
4077 
4078 // For backwards compatibility with -Xrun
4079 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
4080 // treated like -agentpath:
4081 // Must be called before agent libraries are created
4082 void Threads::convert_vm_init_libraries_to_agents() {
4083   AgentLibrary* agent;
4084   AgentLibrary* next;
4085 
4086   for (agent = Arguments::libraries(); agent != NULL; agent = next) {
4087     next = agent->next();  // cache the next agent now as this agent may get moved off this list
4088     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4089 
4090     // If there is an JVM_OnLoad function it will get called later,
4091     // otherwise see if there is an Agent_OnLoad
4092     if (on_load_entry == NULL) {
4093       on_load_entry = lookup_agent_on_load(agent);
4094       if (on_load_entry != NULL) {
4095         // switch it to the agent list -- so that Agent_OnLoad will be called,
4096         // JVM_OnLoad won't be attempted and Agent_OnUnload will
4097         Arguments::convert_library_to_agent(agent);
4098       } else {
4099         vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
4100       }
4101     }
4102   }
4103 }
4104 
4105 // Create agents for -agentlib:  -agentpath:  and converted -Xrun
4106 // Invokes Agent_OnLoad
4107 // Called very early -- before JavaThreads exist
4108 void Threads::create_vm_init_agents() {
4109   extern struct JavaVM_ main_vm;
4110   AgentLibrary* agent;
4111 
4112   JvmtiExport::enter_onload_phase();
4113 
4114   for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4115     OnLoadEntry_t  on_load_entry = lookup_agent_on_load(agent);
4116 
4117     if (on_load_entry != NULL) {
4118       // Invoke the Agent_OnLoad function
4119       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4120       if (err != JNI_OK) {
4121         vm_exit_during_initialization("agent library failed to init", agent->name());
4122       }
4123     } else {
4124       vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4125     }
4126   }
4127   JvmtiExport::enter_primordial_phase();
4128 }
4129 
4130 extern "C" {
4131   typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4132 }
4133 
4134 void Threads::shutdown_vm_agents() {
4135   // Send any Agent_OnUnload notifications
4136   const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4137   size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4138   extern struct JavaVM_ main_vm;
4139   for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4140 
4141     // Find the Agent_OnUnload function.
4142     Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4143                                                    os::find_agent_function(agent,
4144                                                    false,
4145                                                    on_unload_symbols,
4146                                                    num_symbol_entries));
4147 
4148     // Invoke the Agent_OnUnload function
4149     if (unload_entry != NULL) {
4150       JavaThread* thread = JavaThread::current();
4151       ThreadToNativeFromVM ttn(thread);
4152       HandleMark hm(thread);
4153       (*unload_entry)(&main_vm);
4154     }
4155   }
4156 }
4157 
4158 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4159 // Invokes JVM_OnLoad
4160 void Threads::create_vm_init_libraries() {
4161   extern struct JavaVM_ main_vm;
4162   AgentLibrary* agent;
4163 
4164   for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4165     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4166 
4167     if (on_load_entry != NULL) {
4168       // Invoke the JVM_OnLoad function
4169       JavaThread* thread = JavaThread::current();
4170       ThreadToNativeFromVM ttn(thread);
4171       HandleMark hm(thread);
4172       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4173       if (err != JNI_OK) {
4174         vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4175       }
4176     } else {
4177       vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4178     }
4179   }
4180 }
4181 
4182 
4183 // Last thread running calls java.lang.Shutdown.shutdown()
4184 void JavaThread::invoke_shutdown_hooks() {
4185   HandleMark hm(this);
4186 
4187   // We could get here with a pending exception, if so clear it now.
4188   if (this->has_pending_exception()) {
4189     this->clear_pending_exception();
4190   }
4191 
4192   EXCEPTION_MARK;
4193   Klass* shutdown_klass =
4194     SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4195                                       THREAD);
4196   if (shutdown_klass != NULL) {
4197     // SystemDictionary::resolve_or_null will return null if there was
4198     // an exception.  If we cannot load the Shutdown class, just don't
4199     // call Shutdown.shutdown() at all.  This will mean the shutdown hooks
4200     // won't be run.  Note that if a shutdown hook was registered,
4201     // the Shutdown class would have already been loaded
4202     // (Runtime.addShutdownHook will load it).
4203     JavaValue result(T_VOID);
4204     JavaCalls::call_static(&result,
4205                            shutdown_klass,
4206                            vmSymbols::shutdown_method_name(),
4207                            vmSymbols::void_method_signature(),
4208                            THREAD);
4209   }
4210   CLEAR_PENDING_EXCEPTION;
4211 }
4212 
4213 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4214 // the program falls off the end of main(). Another VM exit path is through
4215 // vm_exit() when the program calls System.exit() to return a value or when
4216 // there is a serious error in VM. The two shutdown paths are not exactly
4217 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4218 // and VM_Exit op at VM level.
4219 //
4220 // Shutdown sequence:
4221 //   + Shutdown native memory tracking if it is on
4222 //   + Wait until we are the last non-daemon thread to execute
4223 //     <-- every thing is still working at this moment -->
4224 //   + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4225 //        shutdown hooks
4226 //   + Call before_exit(), prepare for VM exit
4227 //      > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4228 //        currently the only user of this mechanism is File.deleteOnExit())
4229 //      > stop StatSampler, watcher thread, CMS threads,
4230 //        post thread end and vm death events to JVMTI,
4231 //        stop signal thread
4232 //   + Call JavaThread::exit(), it will:
4233 //      > release JNI handle blocks, remove stack guard pages
4234 //      > remove this thread from Threads list
4235 //     <-- no more Java code from this thread after this point -->
4236 //   + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4237 //     the compiler threads at safepoint
4238 //     <-- do not use anything that could get blocked by Safepoint -->
4239 //   + Disable tracing at JNI/JVM barriers
4240 //   + Set _vm_exited flag for threads that are still running native code
4241 //   + Delete this thread
4242 //   + Call exit_globals()
4243 //      > deletes tty
4244 //      > deletes PerfMemory resources
4245 //   + Return to caller
4246 
4247 bool Threads::destroy_vm() {
4248   JavaThread* thread = JavaThread::current();
4249 
4250 #ifdef ASSERT
4251   _vm_complete = false;
4252 #endif
4253   // Wait until we are the last non-daemon thread to execute
4254   { MutexLocker nu(Threads_lock);
4255     while (Threads::number_of_non_daemon_threads() > 1)
4256       // This wait should make safepoint checks, wait without a timeout,
4257       // and wait as a suspend-equivalent condition.
4258       Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4259                          Mutex::_as_suspend_equivalent_flag);
4260   }
4261 
4262   EventShutdown e;
4263   if (e.should_commit()) {
4264     e.set_reason("No remaining non-daemon Java threads");
4265     e.commit();
4266   }
4267 
4268   // Hang forever on exit if we are reporting an error.
4269   if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4270     os::infinite_sleep();
4271   }
4272   os::wait_for_keypress_at_exit();
4273 
4274   // run Java level shutdown hooks
4275   thread->invoke_shutdown_hooks();
4276 
4277   before_exit(thread);
4278 
4279   thread->exit(true);
4280 
4281   // Stop VM thread.
4282   {
4283     // 4945125 The vm thread comes to a safepoint during exit.
4284     // GC vm_operations can get caught at the safepoint, and the
4285     // heap is unparseable if they are caught. Grab the Heap_lock
4286     // to prevent this. The GC vm_operations will not be able to
4287     // queue until after the vm thread is dead. After this point,
4288     // we'll never emerge out of the safepoint before the VM exits.
4289 
4290     MutexLocker ml(Heap_lock);
4291 
4292     VMThread::wait_for_vm_thread_exit();
4293     assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4294     VMThread::destroy();
4295   }
4296 
4297   // Now, all Java threads are gone except daemon threads. Daemon threads
4298   // running Java code or in VM are stopped by the Safepoint. However,
4299   // daemon threads executing native code are still running.  But they
4300   // will be stopped at native=>Java/VM barriers. Note that we can't
4301   // simply kill or suspend them, as it is inherently deadlock-prone.
4302 
4303   VM_Exit::set_vm_exited();
4304 
4305   // Clean up ideal graph printers after the VMThread has started
4306   // the final safepoint which will block all the Compiler threads.
4307   // Note that this Thread has already logically exited so the
4308   // clean_up() function's use of a JavaThreadIteratorWithHandle
4309   // would be a problem except set_vm_exited() has remembered the
4310   // shutdown thread which is granted a policy exception.
4311 #if defined(COMPILER2) && !defined(PRODUCT)
4312   IdealGraphPrinter::clean_up();
4313 #endif
4314 
4315   notify_vm_shutdown();
4316 
4317   // We are after VM_Exit::set_vm_exited() so we can't call
4318   // thread->smr_delete() or we will block on the Threads_lock.
4319   // Deleting the shutdown thread here is safe because another
4320   // JavaThread cannot have an active ThreadsListHandle for
4321   // this JavaThread.
4322   delete thread;
4323 
4324 #if INCLUDE_JVMCI
4325   if (JVMCICounterSize > 0) {
4326     FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4327   }
4328 #endif
4329 
4330   // exit_globals() will delete tty
4331   exit_globals();
4332 
4333   LogConfiguration::finalize();
4334 
4335   return true;
4336 }
4337 
4338 
4339 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4340   if (version == JNI_VERSION_1_1) return JNI_TRUE;
4341   return is_supported_jni_version(version);
4342 }
4343 
4344 
4345 jboolean Threads::is_supported_jni_version(jint version) {
4346   if (version == JNI_VERSION_1_2) return JNI_TRUE;
4347   if (version == JNI_VERSION_1_4) return JNI_TRUE;
4348   if (version == JNI_VERSION_1_6) return JNI_TRUE;
4349   if (version == JNI_VERSION_1_8) return JNI_TRUE;
4350   if (version == JNI_VERSION_9) return JNI_TRUE;
4351   if (version == JNI_VERSION_10) return JNI_TRUE;
4352   return JNI_FALSE;
4353 }
4354 
4355 
4356 void Threads::add(JavaThread* p, bool force_daemon) {
4357   // The threads lock must be owned at this point
4358   assert_locked_or_safepoint(Threads_lock);
4359 
4360   BarrierSet::barrier_set()->on_thread_attach(p);
4361 
4362   p->set_next(_thread_list);
4363   _thread_list = p;
4364 
4365   // Once a JavaThread is added to the Threads list, smr_delete() has
4366   // to be used to delete it. Otherwise we can just delete it directly.
4367   p->set_on_thread_list();
4368 
4369   _number_of_threads++;
4370   oop threadObj = p->threadObj();
4371   bool daemon = true;
4372   // Bootstrapping problem: threadObj can be null for initial
4373   // JavaThread (or for threads attached via JNI)
4374   if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4375     _number_of_non_daemon_threads++;
4376     daemon = false;
4377   }
4378 
4379   ThreadService::add_thread(p, daemon);
4380 
4381   // Maintain fast thread list
4382   ThreadsSMRSupport::add_thread(p);
4383 
4384   // Possible GC point.
4385   Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4386 }
4387 
4388 void Threads::remove(JavaThread* p) {
4389 
4390   // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread.
4391   ObjectSynchronizer::omFlush(p);
4392 
4393   // Extra scope needed for Thread_lock, so we can check
4394   // that we do not remove thread without safepoint code notice
4395   { MutexLocker ml(Threads_lock);
4396 
4397     assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present");
4398 
4399     // Maintain fast thread list
4400     ThreadsSMRSupport::remove_thread(p);
4401 
4402     JavaThread* current = _thread_list;
4403     JavaThread* prev    = NULL;
4404 
4405     while (current != p) {
4406       prev    = current;
4407       current = current->next();
4408     }
4409 
4410     if (prev) {
4411       prev->set_next(current->next());
4412     } else {
4413       _thread_list = p->next();
4414     }
4415 
4416     _number_of_threads--;
4417     oop threadObj = p->threadObj();
4418     bool daemon = true;
4419     if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4420       _number_of_non_daemon_threads--;
4421       daemon = false;
4422 
4423       // Only one thread left, do a notify on the Threads_lock so a thread waiting
4424       // on destroy_vm will wake up.
4425       if (number_of_non_daemon_threads() == 1) {
4426         Threads_lock->notify_all();
4427       }
4428     }
4429     ThreadService::remove_thread(p, daemon);
4430 
4431     // Make sure that safepoint code disregard this thread. This is needed since
4432     // the thread might mess around with locks after this point. This can cause it
4433     // to do callbacks into the safepoint code. However, the safepoint code is not aware
4434     // of this thread since it is removed from the queue.
4435     p->set_terminated_value();
4436   } // unlock Threads_lock
4437 
4438   // Since Events::log uses a lock, we grab it outside the Threads_lock
4439   Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4440 }
4441 
4442 // Operations on the Threads list for GC.  These are not explicitly locked,
4443 // but the garbage collector must provide a safe context for them to run.
4444 // In particular, these things should never be called when the Threads_lock
4445 // is held by some other thread. (Note: the Safepoint abstraction also
4446 // uses the Threads_lock to guarantee this property. It also makes sure that
4447 // all threads gets blocked when exiting or starting).
4448 
4449 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4450   ALL_JAVA_THREADS(p) {
4451     p->oops_do(f, cf);
4452   }
4453   VMThread::vm_thread()->oops_do(f, cf);
4454 }
4455 
4456 void Threads::change_thread_claim_parity() {
4457   // Set the new claim parity.
4458   assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4459          "Not in range.");
4460   _thread_claim_parity++;
4461   if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4462   assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4463          "Not in range.");
4464 }
4465 
4466 #ifdef ASSERT
4467 void Threads::assert_all_threads_claimed() {
4468   ALL_JAVA_THREADS(p) {
4469     const int thread_parity = p->oops_do_parity();
4470     assert((thread_parity == _thread_claim_parity),
4471            "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4472   }
4473   VMThread* vmt = VMThread::vm_thread();
4474   const int thread_parity = vmt->oops_do_parity();
4475   assert((thread_parity == _thread_claim_parity),
4476          "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity);
4477 }
4478 #endif // ASSERT
4479 
4480 class ParallelOopsDoThreadClosure : public ThreadClosure {
4481 private:
4482   OopClosure* _f;
4483   CodeBlobClosure* _cf;
4484 public:
4485   ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {}
4486   void do_thread(Thread* t) {
4487     t->oops_do(_f, _cf);
4488   }
4489 };
4490 
4491 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4492   ParallelOopsDoThreadClosure tc(f, cf);
4493   possibly_parallel_threads_do(is_par, &tc);
4494 }
4495 
4496 #if INCLUDE_ALL_GCS
4497 // Used by ParallelScavenge
4498 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4499   ALL_JAVA_THREADS(p) {
4500     q->enqueue(new ThreadRootsTask(p));
4501   }
4502   q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4503 }
4504 
4505 // Used by Parallel Old
4506 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4507   ALL_JAVA_THREADS(p) {
4508     q->enqueue(new ThreadRootsMarkingTask(p));
4509   }
4510   q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4511 }
4512 #endif // INCLUDE_ALL_GCS
4513 
4514 void Threads::nmethods_do(CodeBlobClosure* cf) {
4515   ALL_JAVA_THREADS(p) {
4516     // This is used by the code cache sweeper to mark nmethods that are active
4517     // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4518     // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4519     if(!p->is_Code_cache_sweeper_thread()) {
4520       p->nmethods_do(cf);
4521     }
4522   }
4523 }
4524 
4525 void Threads::metadata_do(void f(Metadata*)) {
4526   ALL_JAVA_THREADS(p) {
4527     p->metadata_do(f);
4528   }
4529 }
4530 
4531 class ThreadHandlesClosure : public ThreadClosure {
4532   void (*_f)(Metadata*);
4533  public:
4534   ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4535   virtual void do_thread(Thread* thread) {
4536     thread->metadata_handles_do(_f);
4537   }
4538 };
4539 
4540 void Threads::metadata_handles_do(void f(Metadata*)) {
4541   // Only walk the Handles in Thread.
4542   ThreadHandlesClosure handles_closure(f);
4543   threads_do(&handles_closure);
4544 }
4545 
4546 void Threads::deoptimized_wrt_marked_nmethods() {
4547   ALL_JAVA_THREADS(p) {
4548     p->deoptimized_wrt_marked_nmethods();
4549   }
4550 }
4551 
4552 
4553 // Get count Java threads that are waiting to enter the specified monitor.
4554 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
4555                                                          int count,
4556                                                          address monitor) {
4557   GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4558 
4559   int i = 0;
4560   DO_JAVA_THREADS(t_list, p) {
4561     if (!p->can_call_java()) continue;
4562 
4563     address pending = (address)p->current_pending_monitor();
4564     if (pending == monitor) {             // found a match
4565       if (i < count) result->append(p);   // save the first count matches
4566       i++;
4567     }
4568   }
4569 
4570   return result;
4571 }
4572 
4573 
4574 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
4575                                                       address owner) {
4576   // NULL owner means not locked so we can skip the search
4577   if (owner == NULL) return NULL;
4578 
4579   DO_JAVA_THREADS(t_list, p) {
4580     // first, see if owner is the address of a Java thread
4581     if (owner == (address)p) return p;
4582   }
4583 
4584   // Cannot assert on lack of success here since this function may be
4585   // used by code that is trying to report useful problem information
4586   // like deadlock detection.
4587   if (UseHeavyMonitors) return NULL;
4588 
4589   // If we didn't find a matching Java thread and we didn't force use of
4590   // heavyweight monitors, then the owner is the stack address of the
4591   // Lock Word in the owning Java thread's stack.
4592   //
4593   JavaThread* the_owner = NULL;
4594   DO_JAVA_THREADS(t_list, q) {
4595     if (q->is_lock_owned(owner)) {
4596       the_owner = q;
4597       break;
4598     }
4599   }
4600 
4601   // cannot assert on lack of success here; see above comment
4602   return the_owner;
4603 }
4604 
4605 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4606 void Threads::print_on(outputStream* st, bool print_stacks,
4607                        bool internal_format, bool print_concurrent_locks) {
4608   char buf[32];
4609   st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4610 
4611   st->print_cr("Full thread dump %s (%s %s):",
4612                Abstract_VM_Version::vm_name(),
4613                Abstract_VM_Version::vm_release(),
4614                Abstract_VM_Version::vm_info_string());
4615   st->cr();
4616 
4617 #if INCLUDE_SERVICES
4618   // Dump concurrent locks
4619   ConcurrentLocksDump concurrent_locks;
4620   if (print_concurrent_locks) {
4621     concurrent_locks.dump_at_safepoint();
4622   }
4623 #endif // INCLUDE_SERVICES
4624 
4625   ThreadsSMRSupport::print_info_on(st);
4626   st->cr();
4627 
4628   ALL_JAVA_THREADS(p) {
4629     ResourceMark rm;
4630     p->print_on(st);
4631     if (print_stacks) {
4632       if (internal_format) {
4633         p->trace_stack();
4634       } else {
4635         p->print_stack_on(st);
4636       }
4637     }
4638     st->cr();
4639 #if INCLUDE_SERVICES
4640     if (print_concurrent_locks) {
4641       concurrent_locks.print_locks_on(p, st);
4642     }
4643 #endif // INCLUDE_SERVICES
4644   }
4645 
4646   VMThread::vm_thread()->print_on(st);
4647   st->cr();
4648   Universe::heap()->print_gc_threads_on(st);
4649   WatcherThread* wt = WatcherThread::watcher_thread();
4650   if (wt != NULL) {
4651     wt->print_on(st);
4652     st->cr();
4653   }
4654 
4655   st->flush();
4656 }
4657 
4658 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4659                              int buflen, bool* found_current) {
4660   if (this_thread != NULL) {
4661     bool is_current = (current == this_thread);
4662     *found_current = *found_current || is_current;
4663     st->print("%s", is_current ? "=>" : "  ");
4664 
4665     st->print(PTR_FORMAT, p2i(this_thread));
4666     st->print(" ");
4667     this_thread->print_on_error(st, buf, buflen);
4668     st->cr();
4669   }
4670 }
4671 
4672 class PrintOnErrorClosure : public ThreadClosure {
4673   outputStream* _st;
4674   Thread* _current;
4675   char* _buf;
4676   int _buflen;
4677   bool* _found_current;
4678  public:
4679   PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4680                       int buflen, bool* found_current) :
4681    _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4682 
4683   virtual void do_thread(Thread* thread) {
4684     Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4685   }
4686 };
4687 
4688 // Threads::print_on_error() is called by fatal error handler. It's possible
4689 // that VM is not at safepoint and/or current thread is inside signal handler.
4690 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4691 // memory (even in resource area), it might deadlock the error handler.
4692 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4693                              int buflen) {
4694   ThreadsSMRSupport::print_info_on(st);
4695   st->cr();
4696 
4697   bool found_current = false;
4698   st->print_cr("Java Threads: ( => current thread )");
4699   ALL_JAVA_THREADS(thread) {
4700     print_on_error(thread, st, current, buf, buflen, &found_current);
4701   }
4702   st->cr();
4703 
4704   st->print_cr("Other Threads:");
4705   print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4706   print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4707 
4708   PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4709   Universe::heap()->gc_threads_do(&print_closure);
4710 
4711   if (!found_current) {
4712     st->cr();
4713     st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4714     current->print_on_error(st, buf, buflen);
4715     st->cr();
4716   }
4717   st->cr();
4718 
4719   st->print_cr("Threads with active compile tasks:");
4720   print_threads_compiling(st, buf, buflen);
4721 }
4722 
4723 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4724   ALL_JAVA_THREADS(thread) {
4725     if (thread->is_Compiler_thread()) {
4726       CompilerThread* ct = (CompilerThread*) thread;
4727 
4728       // Keep task in local variable for NULL check.
4729       // ct->_task might be set to NULL by concurring compiler thread
4730       // because it completed the compilation. The task is never freed,
4731       // though, just returned to a free list.
4732       CompileTask* task = ct->task();
4733       if (task != NULL) {
4734         thread->print_name_on_error(st, buf, buflen);
4735         task->print(st, NULL, true, true);
4736       }
4737     }
4738   }
4739 }
4740 
4741 
4742 // Internal SpinLock and Mutex
4743 // Based on ParkEvent
4744 
4745 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4746 //
4747 // We employ SpinLocks _only for low-contention, fixed-length
4748 // short-duration critical sections where we're concerned
4749 // about native mutex_t or HotSpot Mutex:: latency.
4750 // The mux construct provides a spin-then-block mutual exclusion
4751 // mechanism.
4752 //
4753 // Testing has shown that contention on the ListLock guarding gFreeList
4754 // is common.  If we implement ListLock as a simple SpinLock it's common
4755 // for the JVM to devolve to yielding with little progress.  This is true
4756 // despite the fact that the critical sections protected by ListLock are
4757 // extremely short.
4758 //
4759 // TODO-FIXME: ListLock should be of type SpinLock.
4760 // We should make this a 1st-class type, integrated into the lock
4761 // hierarchy as leaf-locks.  Critically, the SpinLock structure
4762 // should have sufficient padding to avoid false-sharing and excessive
4763 // cache-coherency traffic.
4764 
4765 
4766 typedef volatile int SpinLockT;
4767 
4768 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4769   if (Atomic::cmpxchg (1, adr, 0) == 0) {
4770     return;   // normal fast-path return
4771   }
4772 
4773   // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4774   TEVENT(SpinAcquire - ctx);
4775   int ctr = 0;
4776   int Yields = 0;
4777   for (;;) {
4778     while (*adr != 0) {
4779       ++ctr;
4780       if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4781         if (Yields > 5) {
4782           os::naked_short_sleep(1);
4783         } else {
4784           os::naked_yield();
4785           ++Yields;
4786         }
4787       } else {
4788         SpinPause();
4789       }
4790     }
4791     if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4792   }
4793 }
4794 
4795 void Thread::SpinRelease(volatile int * adr) {
4796   assert(*adr != 0, "invariant");
4797   OrderAccess::fence();      // guarantee at least release consistency.
4798   // Roach-motel semantics.
4799   // It's safe if subsequent LDs and STs float "up" into the critical section,
4800   // but prior LDs and STs within the critical section can't be allowed
4801   // to reorder or float past the ST that releases the lock.
4802   // Loads and stores in the critical section - which appear in program
4803   // order before the store that releases the lock - must also appear
4804   // before the store that releases the lock in memory visibility order.
4805   // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4806   // the ST of 0 into the lock-word which releases the lock, so fence
4807   // more than covers this on all platforms.
4808   *adr = 0;
4809 }
4810 
4811 // muxAcquire and muxRelease:
4812 //
4813 // *  muxAcquire and muxRelease support a single-word lock-word construct.
4814 //    The LSB of the word is set IFF the lock is held.
4815 //    The remainder of the word points to the head of a singly-linked list
4816 //    of threads blocked on the lock.
4817 //
4818 // *  The current implementation of muxAcquire-muxRelease uses its own
4819 //    dedicated Thread._MuxEvent instance.  If we're interested in
4820 //    minimizing the peak number of extant ParkEvent instances then
4821 //    we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4822 //    as certain invariants were satisfied.  Specifically, care would need
4823 //    to be taken with regards to consuming unpark() "permits".
4824 //    A safe rule of thumb is that a thread would never call muxAcquire()
4825 //    if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4826 //    park().  Otherwise the _ParkEvent park() operation in muxAcquire() could
4827 //    consume an unpark() permit intended for monitorenter, for instance.
4828 //    One way around this would be to widen the restricted-range semaphore
4829 //    implemented in park().  Another alternative would be to provide
4830 //    multiple instances of the PlatformEvent() for each thread.  One
4831 //    instance would be dedicated to muxAcquire-muxRelease, for instance.
4832 //
4833 // *  Usage:
4834 //    -- Only as leaf locks
4835 //    -- for short-term locking only as muxAcquire does not perform
4836 //       thread state transitions.
4837 //
4838 // Alternatives:
4839 // *  We could implement muxAcquire and muxRelease with MCS or CLH locks
4840 //    but with parking or spin-then-park instead of pure spinning.
4841 // *  Use Taura-Oyama-Yonenzawa locks.
4842 // *  It's possible to construct a 1-0 lock if we encode the lockword as
4843 //    (List,LockByte).  Acquire will CAS the full lockword while Release
4844 //    will STB 0 into the LockByte.  The 1-0 scheme admits stranding, so
4845 //    acquiring threads use timers (ParkTimed) to detect and recover from
4846 //    the stranding window.  Thread/Node structures must be aligned on 256-byte
4847 //    boundaries by using placement-new.
4848 // *  Augment MCS with advisory back-link fields maintained with CAS().
4849 //    Pictorially:  LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4850 //    The validity of the backlinks must be ratified before we trust the value.
4851 //    If the backlinks are invalid the exiting thread must back-track through the
4852 //    the forward links, which are always trustworthy.
4853 // *  Add a successor indication.  The LockWord is currently encoded as
4854 //    (List, LOCKBIT:1).  We could also add a SUCCBIT or an explicit _succ variable
4855 //    to provide the usual futile-wakeup optimization.
4856 //    See RTStt for details.
4857 // *  Consider schedctl.sc_nopreempt to cover the critical section.
4858 //
4859 
4860 
4861 const intptr_t LOCKBIT = 1;
4862 
4863 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4864   intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4865   if (w == 0) return;
4866   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4867     return;
4868   }
4869 
4870   TEVENT(muxAcquire - Contention);
4871   ParkEvent * const Self = Thread::current()->_MuxEvent;
4872   assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4873   for (;;) {
4874     int its = (os::is_MP() ? 100 : 0) + 1;
4875 
4876     // Optional spin phase: spin-then-park strategy
4877     while (--its >= 0) {
4878       w = *Lock;
4879       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4880         return;
4881       }
4882     }
4883 
4884     Self->reset();
4885     Self->OnList = intptr_t(Lock);
4886     // The following fence() isn't _strictly necessary as the subsequent
4887     // CAS() both serializes execution and ratifies the fetched *Lock value.
4888     OrderAccess::fence();
4889     for (;;) {
4890       w = *Lock;
4891       if ((w & LOCKBIT) == 0) {
4892         if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4893           Self->OnList = 0;   // hygiene - allows stronger asserts
4894           return;
4895         }
4896         continue;      // Interference -- *Lock changed -- Just retry
4897       }
4898       assert(w & LOCKBIT, "invariant");
4899       Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4900       if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4901     }
4902 
4903     while (Self->OnList != 0) {
4904       Self->park();
4905     }
4906   }
4907 }
4908 
4909 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4910   intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4911   if (w == 0) return;
4912   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4913     return;
4914   }
4915 
4916   TEVENT(muxAcquire - Contention);
4917   ParkEvent * ReleaseAfter = NULL;
4918   if (ev == NULL) {
4919     ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4920   }
4921   assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4922   for (;;) {
4923     guarantee(ev->OnList == 0, "invariant");
4924     int its = (os::is_MP() ? 100 : 0) + 1;
4925 
4926     // Optional spin phase: spin-then-park strategy
4927     while (--its >= 0) {
4928       w = *Lock;
4929       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4930         if (ReleaseAfter != NULL) {
4931           ParkEvent::Release(ReleaseAfter);
4932         }
4933         return;
4934       }
4935     }
4936 
4937     ev->reset();
4938     ev->OnList = intptr_t(Lock);
4939     // The following fence() isn't _strictly necessary as the subsequent
4940     // CAS() both serializes execution and ratifies the fetched *Lock value.
4941     OrderAccess::fence();
4942     for (;;) {
4943       w = *Lock;
4944       if ((w & LOCKBIT) == 0) {
4945         if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4946           ev->OnList = 0;
4947           // We call ::Release while holding the outer lock, thus
4948           // artificially lengthening the critical section.
4949           // Consider deferring the ::Release() until the subsequent unlock(),
4950           // after we've dropped the outer lock.
4951           if (ReleaseAfter != NULL) {
4952             ParkEvent::Release(ReleaseAfter);
4953           }
4954           return;
4955         }
4956         continue;      // Interference -- *Lock changed -- Just retry
4957       }
4958       assert(w & LOCKBIT, "invariant");
4959       ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4960       if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4961     }
4962 
4963     while (ev->OnList != 0) {
4964       ev->park();
4965     }
4966   }
4967 }
4968 
4969 // Release() must extract a successor from the list and then wake that thread.
4970 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4971 // similar to that used by ParkEvent::Allocate() and ::Release().  DMR-based
4972 // Release() would :
4973 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4974 // (B) Extract a successor from the private list "in-hand"
4975 // (C) attempt to CAS() the residual back into *Lock over null.
4976 //     If there were any newly arrived threads and the CAS() would fail.
4977 //     In that case Release() would detach the RATs, re-merge the list in-hand
4978 //     with the RATs and repeat as needed.  Alternately, Release() might
4979 //     detach and extract a successor, but then pass the residual list to the wakee.
4980 //     The wakee would be responsible for reattaching and remerging before it
4981 //     competed for the lock.
4982 //
4983 // Both "pop" and DMR are immune from ABA corruption -- there can be
4984 // multiple concurrent pushers, but only one popper or detacher.
4985 // This implementation pops from the head of the list.  This is unfair,
4986 // but tends to provide excellent throughput as hot threads remain hot.
4987 // (We wake recently run threads first).
4988 //
4989 // All paths through muxRelease() will execute a CAS.
4990 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4991 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4992 // executed within the critical section are complete and globally visible before the
4993 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4994 void Thread::muxRelease(volatile intptr_t * Lock)  {
4995   for (;;) {
4996     const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT);
4997     assert(w & LOCKBIT, "invariant");
4998     if (w == LOCKBIT) return;
4999     ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
5000     assert(List != NULL, "invariant");
5001     assert(List->OnList == intptr_t(Lock), "invariant");
5002     ParkEvent * const nxt = List->ListNext;
5003     guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
5004 
5005     // The following CAS() releases the lock and pops the head element.
5006     // The CAS() also ratifies the previously fetched lock-word value.
5007     if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) {
5008       continue;
5009     }
5010     List->OnList = 0;
5011     OrderAccess::fence();
5012     List->unpark();
5013     return;
5014   }
5015 }
5016 
5017 
5018 void Threads::verify() {
5019   ALL_JAVA_THREADS(p) {
5020     p->verify();
5021   }
5022   VMThread* thread = VMThread::vm_thread();
5023   if (thread != NULL) thread->verify();
5024 }