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/barrierSet.hpp"
  37 #include "gc/shared/gcId.hpp"
  38 #include "gc/shared/gcLocker.inline.hpp"
  39 #include "gc/shared/workgroup.hpp"
  40 #include "interpreter/interpreter.hpp"
  41 #include "interpreter/linkResolver.hpp"
  42 #include "interpreter/oopMapCache.hpp"
  43 #include "jvmtifiles/jvmtiEnv.hpp"
  44 #include "logging/log.hpp"
  45 #include "logging/logConfiguration.hpp"
  46 #include "logging/logStream.hpp"
  47 #include "memory/allocation.inline.hpp"
  48 #include "memory/metaspaceShared.hpp"
  49 #include "memory/oopFactory.hpp"
  50 #include "memory/resourceArea.hpp"
  51 #include "memory/universe.hpp"
  52 #include "oops/access.inline.hpp"
  53 #include "oops/instanceKlass.hpp"
  54 #include "oops/objArrayOop.hpp"
  55 #include "oops/oop.inline.hpp"
  56 #include "oops/symbol.hpp"
  57 #include "oops/typeArrayOop.inline.hpp"
  58 #include "oops/verifyOopClosure.hpp"
  59 #include "prims/jvm_misc.hpp"
  60 #include "prims/jvmtiExport.hpp"
  61 #include "prims/jvmtiThreadState.hpp"
  62 #include "prims/privilegedStack.hpp"
  63 #include "runtime/arguments.hpp"
  64 #include "runtime/atomic.hpp"
  65 #include "runtime/biasedLocking.hpp"
  66 #include "runtime/commandLineFlagConstraintList.hpp"
  67 #include "runtime/commandLineFlagWriteableList.hpp"
  68 #include "runtime/commandLineFlagRangeList.hpp"
  69 #include "runtime/deoptimization.hpp"
  70 #include "runtime/frame.inline.hpp"
  71 #include "runtime/globals.hpp"
  72 #include "runtime/handshake.hpp"
  73 #include "runtime/init.hpp"
  74 #include "runtime/interfaceSupport.inline.hpp"
  75 #include "runtime/java.hpp"
  76 #include "runtime/javaCalls.hpp"
  77 #include "runtime/jniHandles.inline.hpp"
  78 #include "runtime/jniPeriodicChecker.hpp"
  79 #include "runtime/memprofiler.hpp"
  80 #include "runtime/mutexLocker.hpp"
  81 #include "runtime/objectMonitor.hpp"
  82 #include "runtime/orderAccess.inline.hpp"
  83 #include "runtime/osThread.hpp"
  84 #include "runtime/prefetch.inline.hpp"
  85 #include "runtime/safepoint.hpp"
  86 #include "runtime/safepointMechanism.inline.hpp"
  87 #include "runtime/sharedRuntime.hpp"
  88 #include "runtime/statSampler.hpp"
  89 #include "runtime/stubRoutines.hpp"
  90 #include "runtime/sweeper.hpp"
  91 #include "runtime/task.hpp"
  92 #include "runtime/thread.inline.hpp"
  93 #include "runtime/threadCritical.hpp"
  94 #include "runtime/threadSMR.inline.hpp"
  95 #include "runtime/timer.hpp"
  96 #include "runtime/timerTrace.hpp"
  97 #include "runtime/vframe.inline.hpp"
  98 #include "runtime/vframeArray.hpp"
  99 #include "runtime/vframe_hp.hpp"
 100 #include "runtime/vmThread.hpp"
 101 #include "runtime/vm_operations.hpp"
 102 #include "runtime/vm_version.hpp"
 103 #include "services/attachListener.hpp"
 104 #include "services/management.hpp"
 105 #include "services/memTracker.hpp"
 106 #include "services/threadService.hpp"
 107 #include "trace/traceMacros.hpp"
 108 #include "trace/tracing.hpp"
 109 #include "trace/tracingExport.hpp"
 110 #include "utilities/align.hpp"
 111 #include "utilities/copy.hpp"
 112 #include "utilities/defaultStream.hpp"
 113 #include "utilities/dtrace.hpp"
 114 #include "utilities/events.hpp"
 115 #include "utilities/macros.hpp"
 116 #include "utilities/preserveException.hpp"
 117 #include "utilities/vmError.hpp"
 118 #if INCLUDE_ALL_GCS
 119 #include "gc/cms/concurrentMarkSweepThread.hpp"
 120 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
 121 #include "gc/parallel/pcTasks.hpp"
 122 #endif // INCLUDE_ALL_GCS
 123 #if INCLUDE_JVMCI
 124 #include "jvmci/jvmciCompiler.hpp"
 125 #include "jvmci/jvmciRuntime.hpp"
 126 #include "logging/logHandle.hpp"
 127 #endif
 128 #ifdef COMPILER1
 129 #include "c1/c1_Compiler.hpp"
 130 #endif
 131 #ifdef COMPILER2
 132 #include "opto/c2compiler.hpp"
 133 #include "opto/idealGraphPrinter.hpp"
 134 #endif
 135 #if INCLUDE_RTM_OPT
 136 #include "runtime/rtmLocking.hpp"
 137 #endif
 138 
 139 // Initialization after module runtime initialization
 140 void universe_post_module_init();  // must happen after call_initPhase2
 141 
 142 #ifdef DTRACE_ENABLED
 143 
 144 // Only bother with this argument setup if dtrace is available
 145 
 146   #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
 147   #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
 148 
 149   #define DTRACE_THREAD_PROBE(probe, javathread)                           \
 150     {                                                                      \
 151       ResourceMark rm(this);                                               \
 152       int len = 0;                                                         \
 153       const char* name = (javathread)->get_thread_name();                  \
 154       len = strlen(name);                                                  \
 155       HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */               \
 156         (char *) name, len,                                                \
 157         java_lang_Thread::thread_id((javathread)->threadObj()),            \
 158         (uintptr_t) (javathread)->osthread()->thread_id(),                 \
 159         java_lang_Thread::is_daemon((javathread)->threadObj()));           \
 160     }
 161 
 162 #else //  ndef DTRACE_ENABLED
 163 
 164   #define DTRACE_THREAD_PROBE(probe, javathread)
 165 
 166 #endif // ndef DTRACE_ENABLED
 167 
 168 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 169 // Current thread is maintained as a thread-local variable
 170 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
 171 #endif
 172 // Class hierarchy
 173 // - Thread
 174 //   - VMThread
 175 //   - WatcherThread
 176 //   - ConcurrentMarkSweepThread
 177 //   - JavaThread
 178 //     - CompilerThread
 179 
 180 // ======= Thread ========
 181 // Support for forcing alignment of thread objects for biased locking
 182 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
 183   if (UseBiasedLocking) {
 184     const int alignment = markOopDesc::biased_lock_alignment;
 185     size_t aligned_size = size + (alignment - sizeof(intptr_t));
 186     void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
 187                                           : AllocateHeap(aligned_size, flags, CURRENT_PC,
 188                                                          AllocFailStrategy::RETURN_NULL);
 189     void* aligned_addr     = align_up(real_malloc_addr, alignment);
 190     assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
 191            ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
 192            "JavaThread alignment code overflowed allocated storage");
 193     if (aligned_addr != real_malloc_addr) {
 194       log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
 195                               p2i(real_malloc_addr),
 196                               p2i(aligned_addr));
 197     }
 198     ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
 199     return aligned_addr;
 200   } else {
 201     return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
 202                        : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
 203   }
 204 }
 205 
 206 void Thread::operator delete(void* p) {
 207   if (UseBiasedLocking) {
 208     FreeHeap(((Thread*) p)->_real_malloc_address);
 209   } else {
 210     FreeHeap(p);
 211   }
 212 }
 213 
 214 void JavaThread::smr_delete() {
 215   if (_on_thread_list) {
 216     ThreadsSMRSupport::smr_delete(this);
 217   } else {
 218     delete this;
 219   }
 220 }
 221 
 222 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
 223 // JavaThread
 224 
 225 
 226 Thread::Thread() {
 227   // stack and get_thread
 228   set_stack_base(NULL);
 229   set_stack_size(0);
 230   set_self_raw_id(0);
 231   set_lgrp_id(-1);
 232   DEBUG_ONLY(clear_suspendible_thread();)
 233 
 234   // allocated data structures
 235   set_osthread(NULL);
 236   set_resource_area(new (mtThread)ResourceArea());
 237   DEBUG_ONLY(_current_resource_mark = NULL;)
 238   set_handle_area(new (mtThread) HandleArea(NULL));
 239   set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
 240   set_active_handles(NULL);
 241   set_free_handle_block(NULL);
 242   set_last_handle_mark(NULL);
 243 
 244   _statistic_info.setStartTime(os::javaTimeMillis());
 245   _statistic_info.setDefineClassCount(0);
 246 
 247   // This initial value ==> never claimed.
 248   _oops_do_parity = 0;
 249   _threads_hazard_ptr = NULL;
 250   _nested_threads_hazard_ptr = NULL;
 251   _nested_threads_hazard_ptr_cnt = 0;
 252   _rcu_counter = 0;
 253 
 254   // the handle mark links itself to last_handle_mark
 255   new HandleMark(this);
 256 
 257   // plain initialization
 258   debug_only(_owned_locks = NULL;)
 259   debug_only(_allow_allocation_count = 0;)
 260   NOT_PRODUCT(_allow_safepoint_count = 0;)
 261   NOT_PRODUCT(_skip_gcalot = false;)
 262   _jvmti_env_iteration_count = 0;
 263   set_allocated_bytes(0);
 264   _vm_operation_started_count = 0;
 265   _vm_operation_completed_count = 0;
 266   _current_pending_monitor = NULL;
 267   _current_pending_monitor_is_from_java = true;
 268   _current_waiting_monitor = NULL;
 269   _num_nested_signal = 0;
 270   omFreeList = NULL;
 271   omFreeCount = 0;
 272   omFreeProvision = 32;
 273   omInUseList = NULL;
 274   omInUseCount = 0;
 275 
 276 #ifdef ASSERT
 277   _visited_for_critical_count = false;
 278 #endif
 279 
 280   _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
 281                          Monitor::_safepoint_check_sometimes);
 282   _suspend_flags = 0;
 283 
 284   // thread-specific hashCode stream generator state - Marsaglia shift-xor form
 285   _hashStateX = os::random();
 286   _hashStateY = 842502087;
 287   _hashStateZ = 0x8767;    // (int)(3579807591LL & 0xffff) ;
 288   _hashStateW = 273326509;
 289 
 290   _OnTrap   = 0;
 291   _schedctl = NULL;
 292   _Stalled  = 0;
 293   _TypeTag  = 0x2BAD;
 294 
 295   // Many of the following fields are effectively final - immutable
 296   // Note that nascent threads can't use the Native Monitor-Mutex
 297   // construct until the _MutexEvent is initialized ...
 298   // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
 299   // we might instead use a stack of ParkEvents that we could provision on-demand.
 300   // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
 301   // and ::Release()
 302   _ParkEvent   = ParkEvent::Allocate(this);
 303   _SleepEvent  = ParkEvent::Allocate(this);
 304   _MutexEvent  = ParkEvent::Allocate(this);
 305   _MuxEvent    = ParkEvent::Allocate(this);
 306 
 307 #ifdef CHECK_UNHANDLED_OOPS
 308   if (CheckUnhandledOops) {
 309     _unhandled_oops = new UnhandledOops(this);
 310   }
 311 #endif // CHECK_UNHANDLED_OOPS
 312 #ifdef ASSERT
 313   if (UseBiasedLocking) {
 314     assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
 315     assert(this == _real_malloc_address ||
 316            this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment),
 317            "bug in forced alignment of thread objects");
 318   }
 319 #endif // ASSERT
 320 
 321   // Notify the barrier set that a thread is being created. Note that the
 322   // main thread is created before a barrier set is available. The call to
 323   // BarrierSet::on_thread_create() for the main thread is therefore deferred
 324   // until it calls BarrierSet::set_barrier_set().
 325   BarrierSet* const barrier_set = BarrierSet::barrier_set();
 326   if (barrier_set != NULL) {
 327     barrier_set->on_thread_create(this);
 328   }
 329 }
 330 
 331 void Thread::initialize_thread_current() {
 332 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 333   assert(_thr_current == NULL, "Thread::current already initialized");
 334   _thr_current = this;
 335 #endif
 336   assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
 337   ThreadLocalStorage::set_thread(this);
 338   assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
 339 }
 340 
 341 void Thread::clear_thread_current() {
 342   assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
 343 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 344   _thr_current = NULL;
 345 #endif
 346   ThreadLocalStorage::set_thread(NULL);
 347 }
 348 
 349 void Thread::record_stack_base_and_size() {
 350   set_stack_base(os::current_stack_base());
 351   set_stack_size(os::current_stack_size());
 352   // CR 7190089: on Solaris, primordial thread's stack is adjusted
 353   // in initialize_thread(). Without the adjustment, stack size is
 354   // incorrect if stack is set to unlimited (ulimit -s unlimited).
 355   // So far, only Solaris has real implementation of initialize_thread().
 356   //
 357   // set up any platform-specific state.
 358   os::initialize_thread(this);
 359 
 360   // Set stack limits after thread is initialized.
 361   if (is_Java_thread()) {
 362     ((JavaThread*) this)->set_stack_overflow_limit();
 363     ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
 364   }
 365 #if INCLUDE_NMT
 366   // record thread's native stack, stack grows downward
 367   MemTracker::record_thread_stack(stack_end(), stack_size());
 368 #endif // INCLUDE_NMT
 369   log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
 370     PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
 371     os::current_thread_id(), p2i(stack_base() - stack_size()),
 372     p2i(stack_base()), stack_size()/1024);
 373 }
 374 
 375 
 376 Thread::~Thread() {
 377   EVENT_THREAD_DESTRUCT(this);
 378 
 379   // Notify the barrier set that a thread is being destroyed. Note that a barrier
 380   // set might not be available if we encountered errors during bootstrapping.
 381   BarrierSet* const barrier_set = BarrierSet::barrier_set();
 382   if (barrier_set != NULL) {
 383     barrier_set->on_thread_destroy(this);
 384   }
 385 
 386   // stack_base can be NULL if the thread is never started or exited before
 387   // record_stack_base_and_size called. Although, we would like to ensure
 388   // that all started threads do call record_stack_base_and_size(), there is
 389   // not proper way to enforce that.
 390 #if INCLUDE_NMT
 391   if (_stack_base != NULL) {
 392     MemTracker::release_thread_stack(stack_end(), stack_size());
 393 #ifdef ASSERT
 394     set_stack_base(NULL);
 395 #endif
 396   }
 397 #endif // INCLUDE_NMT
 398 
 399   // deallocate data structures
 400   delete resource_area();
 401   // since the handle marks are using the handle area, we have to deallocated the root
 402   // handle mark before deallocating the thread's handle area,
 403   assert(last_handle_mark() != NULL, "check we have an element");
 404   delete last_handle_mark();
 405   assert(last_handle_mark() == NULL, "check we have reached the end");
 406 
 407   // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
 408   // We NULL out the fields for good hygiene.
 409   ParkEvent::Release(_ParkEvent); _ParkEvent   = NULL;
 410   ParkEvent::Release(_SleepEvent); _SleepEvent  = NULL;
 411   ParkEvent::Release(_MutexEvent); _MutexEvent  = NULL;
 412   ParkEvent::Release(_MuxEvent); _MuxEvent    = NULL;
 413 
 414   delete handle_area();
 415   delete metadata_handles();
 416 
 417   // SR_handler uses this as a termination indicator -
 418   // needs to happen before os::free_thread()
 419   delete _SR_lock;
 420   _SR_lock = NULL;
 421 
 422   // osthread() can be NULL, if creation of thread failed.
 423   if (osthread() != NULL) os::free_thread(osthread());
 424 
 425   // clear Thread::current if thread is deleting itself.
 426   // Needed to ensure JNI correctly detects non-attached threads.
 427   if (this == Thread::current()) {
 428     clear_thread_current();
 429   }
 430 
 431   CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
 432 }
 433 
 434 // NOTE: dummy function for assertion purpose.
 435 void Thread::run() {
 436   ShouldNotReachHere();
 437 }
 438 
 439 #ifdef ASSERT
 440 // A JavaThread is considered "dangling" if it is not the current
 441 // thread, has been added the Threads list, the system is not at a
 442 // safepoint and the Thread is not "protected".
 443 //
 444 void Thread::check_for_dangling_thread_pointer(Thread *thread) {
 445   assert(!thread->is_Java_thread() || Thread::current() == thread ||
 446          !((JavaThread *) thread)->on_thread_list() ||
 447          SafepointSynchronize::is_at_safepoint() ||
 448          ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread),
 449          "possibility of dangling Thread pointer");
 450 }
 451 #endif
 452 
 453 ThreadPriority Thread::get_priority(const Thread* const thread) {
 454   ThreadPriority priority;
 455   // Can return an error!
 456   (void)os::get_priority(thread, priority);
 457   assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
 458   return priority;
 459 }
 460 
 461 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
 462   debug_only(check_for_dangling_thread_pointer(thread);)
 463   // Can return an error!
 464   (void)os::set_priority(thread, priority);
 465 }
 466 
 467 
 468 void Thread::start(Thread* thread) {
 469   // Start is different from resume in that its safety is guaranteed by context or
 470   // being called from a Java method synchronized on the Thread object.
 471   if (!DisableStartThread) {
 472     if (thread->is_Java_thread()) {
 473       // Initialize the thread state to RUNNABLE before starting this thread.
 474       // Can not set it after the thread started because we do not know the
 475       // exact thread state at that time. It could be in MONITOR_WAIT or
 476       // in SLEEPING or some other state.
 477       java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
 478                                           java_lang_Thread::RUNNABLE);
 479     }
 480     os::start_thread(thread);
 481   }
 482 }
 483 
 484 // Enqueue a VM_Operation to do the job for us - sometime later
 485 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
 486   VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
 487   VMThread::execute(vm_stop);
 488 }
 489 
 490 
 491 // Check if an external suspend request has completed (or has been
 492 // cancelled). Returns true if the thread is externally suspended and
 493 // false otherwise.
 494 //
 495 // The bits parameter returns information about the code path through
 496 // the routine. Useful for debugging:
 497 //
 498 // set in is_ext_suspend_completed():
 499 // 0x00000001 - routine was entered
 500 // 0x00000010 - routine return false at end
 501 // 0x00000100 - thread exited (return false)
 502 // 0x00000200 - suspend request cancelled (return false)
 503 // 0x00000400 - thread suspended (return true)
 504 // 0x00001000 - thread is in a suspend equivalent state (return true)
 505 // 0x00002000 - thread is native and walkable (return true)
 506 // 0x00004000 - thread is native_trans and walkable (needed retry)
 507 //
 508 // set in wait_for_ext_suspend_completion():
 509 // 0x00010000 - routine was entered
 510 // 0x00020000 - suspend request cancelled before loop (return false)
 511 // 0x00040000 - thread suspended before loop (return true)
 512 // 0x00080000 - suspend request cancelled in loop (return false)
 513 // 0x00100000 - thread suspended in loop (return true)
 514 // 0x00200000 - suspend not completed during retry loop (return false)
 515 
 516 // Helper class for tracing suspend wait debug bits.
 517 //
 518 // 0x00000100 indicates that the target thread exited before it could
 519 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
 520 // 0x00080000 each indicate a cancelled suspend request so they don't
 521 // count as wait failures either.
 522 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
 523 
 524 class TraceSuspendDebugBits : public StackObj {
 525  private:
 526   JavaThread * jt;
 527   bool         is_wait;
 528   bool         called_by_wait;  // meaningful when !is_wait
 529   uint32_t *   bits;
 530 
 531  public:
 532   TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
 533                         uint32_t *_bits) {
 534     jt             = _jt;
 535     is_wait        = _is_wait;
 536     called_by_wait = _called_by_wait;
 537     bits           = _bits;
 538   }
 539 
 540   ~TraceSuspendDebugBits() {
 541     if (!is_wait) {
 542 #if 1
 543       // By default, don't trace bits for is_ext_suspend_completed() calls.
 544       // That trace is very chatty.
 545       return;
 546 #else
 547       if (!called_by_wait) {
 548         // If tracing for is_ext_suspend_completed() is enabled, then only
 549         // trace calls to it from wait_for_ext_suspend_completion()
 550         return;
 551       }
 552 #endif
 553     }
 554 
 555     if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
 556       if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
 557         MutexLocker ml(Threads_lock);  // needed for get_thread_name()
 558         ResourceMark rm;
 559 
 560         tty->print_cr(
 561                       "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
 562                       jt->get_thread_name(), *bits);
 563 
 564         guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
 565       }
 566     }
 567   }
 568 };
 569 #undef DEBUG_FALSE_BITS
 570 
 571 
 572 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
 573                                           uint32_t *bits) {
 574   TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
 575 
 576   bool did_trans_retry = false;  // only do thread_in_native_trans retry once
 577   bool do_trans_retry;           // flag to force the retry
 578 
 579   *bits |= 0x00000001;
 580 
 581   do {
 582     do_trans_retry = false;
 583 
 584     if (is_exiting()) {
 585       // Thread is in the process of exiting. This is always checked
 586       // first to reduce the risk of dereferencing a freed JavaThread.
 587       *bits |= 0x00000100;
 588       return false;
 589     }
 590 
 591     if (!is_external_suspend()) {
 592       // Suspend request is cancelled. This is always checked before
 593       // is_ext_suspended() to reduce the risk of a rogue resume
 594       // confusing the thread that made the suspend request.
 595       *bits |= 0x00000200;
 596       return false;
 597     }
 598 
 599     if (is_ext_suspended()) {
 600       // thread is suspended
 601       *bits |= 0x00000400;
 602       return true;
 603     }
 604 
 605     // Now that we no longer do hard suspends of threads running
 606     // native code, the target thread can be changing thread state
 607     // while we are in this routine:
 608     //
 609     //   _thread_in_native -> _thread_in_native_trans -> _thread_blocked
 610     //
 611     // We save a copy of the thread state as observed at this moment
 612     // and make our decision about suspend completeness based on the
 613     // copy. This closes the race where the thread state is seen as
 614     // _thread_in_native_trans in the if-thread_blocked check, but is
 615     // seen as _thread_blocked in if-thread_in_native_trans check.
 616     JavaThreadState save_state = thread_state();
 617 
 618     if (save_state == _thread_blocked && is_suspend_equivalent()) {
 619       // If the thread's state is _thread_blocked and this blocking
 620       // condition is known to be equivalent to a suspend, then we can
 621       // consider the thread to be externally suspended. This means that
 622       // the code that sets _thread_blocked has been modified to do
 623       // self-suspension if the blocking condition releases. We also
 624       // used to check for CONDVAR_WAIT here, but that is now covered by
 625       // the _thread_blocked with self-suspension check.
 626       //
 627       // Return true since we wouldn't be here unless there was still an
 628       // external suspend request.
 629       *bits |= 0x00001000;
 630       return true;
 631     } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
 632       // Threads running native code will self-suspend on native==>VM/Java
 633       // transitions. If its stack is walkable (should always be the case
 634       // unless this function is called before the actual java_suspend()
 635       // call), then the wait is done.
 636       *bits |= 0x00002000;
 637       return true;
 638     } else if (!called_by_wait && !did_trans_retry &&
 639                save_state == _thread_in_native_trans &&
 640                frame_anchor()->walkable()) {
 641       // The thread is transitioning from thread_in_native to another
 642       // thread state. check_safepoint_and_suspend_for_native_trans()
 643       // will force the thread to self-suspend. If it hasn't gotten
 644       // there yet we may have caught the thread in-between the native
 645       // code check above and the self-suspend. Lucky us. If we were
 646       // called by wait_for_ext_suspend_completion(), then it
 647       // will be doing the retries so we don't have to.
 648       //
 649       // Since we use the saved thread state in the if-statement above,
 650       // there is a chance that the thread has already transitioned to
 651       // _thread_blocked by the time we get here. In that case, we will
 652       // make a single unnecessary pass through the logic below. This
 653       // doesn't hurt anything since we still do the trans retry.
 654 
 655       *bits |= 0x00004000;
 656 
 657       // Once the thread leaves thread_in_native_trans for another
 658       // thread state, we break out of this retry loop. We shouldn't
 659       // need this flag to prevent us from getting back here, but
 660       // sometimes paranoia is good.
 661       did_trans_retry = true;
 662 
 663       // We wait for the thread to transition to a more usable state.
 664       for (int i = 1; i <= SuspendRetryCount; i++) {
 665         // We used to do an "os::yield_all(i)" call here with the intention
 666         // that yielding would increase on each retry. However, the parameter
 667         // is ignored on Linux which means the yield didn't scale up. Waiting
 668         // on the SR_lock below provides a much more predictable scale up for
 669         // the delay. It also provides a simple/direct point to check for any
 670         // safepoint requests from the VMThread
 671 
 672         // temporarily drops SR_lock while doing wait with safepoint check
 673         // (if we're a JavaThread - the WatcherThread can also call this)
 674         // and increase delay with each retry
 675         SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 676 
 677         // check the actual thread state instead of what we saved above
 678         if (thread_state() != _thread_in_native_trans) {
 679           // the thread has transitioned to another thread state so
 680           // try all the checks (except this one) one more time.
 681           do_trans_retry = true;
 682           break;
 683         }
 684       } // end retry loop
 685 
 686 
 687     }
 688   } while (do_trans_retry);
 689 
 690   *bits |= 0x00000010;
 691   return false;
 692 }
 693 
 694 // Wait for an external suspend request to complete (or be cancelled).
 695 // Returns true if the thread is externally suspended and false otherwise.
 696 //
 697 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
 698                                                  uint32_t *bits) {
 699   TraceSuspendDebugBits tsdb(this, true /* is_wait */,
 700                              false /* !called_by_wait */, bits);
 701 
 702   // local flag copies to minimize SR_lock hold time
 703   bool is_suspended;
 704   bool pending;
 705   uint32_t reset_bits;
 706 
 707   // set a marker so is_ext_suspend_completed() knows we are the caller
 708   *bits |= 0x00010000;
 709 
 710   // We use reset_bits to reinitialize the bits value at the top of
 711   // each retry loop. This allows the caller to make use of any
 712   // unused bits for their own marking purposes.
 713   reset_bits = *bits;
 714 
 715   {
 716     MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
 717     is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 718                                             delay, bits);
 719     pending = is_external_suspend();
 720   }
 721   // must release SR_lock to allow suspension to complete
 722 
 723   if (!pending) {
 724     // A cancelled suspend request is the only false return from
 725     // is_ext_suspend_completed() that keeps us from entering the
 726     // retry loop.
 727     *bits |= 0x00020000;
 728     return false;
 729   }
 730 
 731   if (is_suspended) {
 732     *bits |= 0x00040000;
 733     return true;
 734   }
 735 
 736   for (int i = 1; i <= retries; i++) {
 737     *bits = reset_bits;  // reinit to only track last retry
 738 
 739     // We used to do an "os::yield_all(i)" call here with the intention
 740     // that yielding would increase on each retry. However, the parameter
 741     // is ignored on Linux which means the yield didn't scale up. Waiting
 742     // on the SR_lock below provides a much more predictable scale up for
 743     // the delay. It also provides a simple/direct point to check for any
 744     // safepoint requests from the VMThread
 745 
 746     {
 747       MutexLocker ml(SR_lock());
 748       // wait with safepoint check (if we're a JavaThread - the WatcherThread
 749       // can also call this)  and increase delay with each retry
 750       SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 751 
 752       is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 753                                               delay, bits);
 754 
 755       // It is possible for the external suspend request to be cancelled
 756       // (by a resume) before the actual suspend operation is completed.
 757       // Refresh our local copy to see if we still need to wait.
 758       pending = is_external_suspend();
 759     }
 760 
 761     if (!pending) {
 762       // A cancelled suspend request is the only false return from
 763       // is_ext_suspend_completed() that keeps us from staying in the
 764       // retry loop.
 765       *bits |= 0x00080000;
 766       return false;
 767     }
 768 
 769     if (is_suspended) {
 770       *bits |= 0x00100000;
 771       return true;
 772     }
 773   } // end retry loop
 774 
 775   // thread did not suspend after all our retries
 776   *bits |= 0x00200000;
 777   return false;
 778 }
 779 
 780 // Called from API entry points which perform stack walking. If the
 781 // associated JavaThread is the current thread, then wait_for_suspend
 782 // is not used. Otherwise, it determines if we should wait for the
 783 // "other" thread to complete external suspension. (NOTE: in future
 784 // releases the suspension mechanism should be reimplemented so this
 785 // is not necessary.)
 786 //
 787 bool
 788 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) {
 789   if (this != JavaThread::current()) {
 790     // "other" threads require special handling.
 791     if (wait_for_suspend) {
 792       // We are allowed to wait for the external suspend to complete
 793       // so give the other thread a chance to get suspended.
 794       if (!wait_for_ext_suspend_completion(SuspendRetryCount,
 795                                            SuspendRetryDelay, bits)) {
 796         // Didn't make it so let the caller know.
 797         return false;
 798       }
 799     }
 800     // We aren't allowed to wait for the external suspend to complete
 801     // so if the other thread isn't externally suspended we need to
 802     // let the caller know.
 803     else if (!is_ext_suspend_completed_with_lock(bits)) {
 804       return false;
 805     }
 806   }
 807 
 808   return true;
 809 }
 810 
 811 #ifndef PRODUCT
 812 void JavaThread::record_jump(address target, address instr, const char* file,
 813                              int line) {
 814 
 815   // This should not need to be atomic as the only way for simultaneous
 816   // updates is via interrupts. Even then this should be rare or non-existent
 817   // and we don't care that much anyway.
 818 
 819   int index = _jmp_ring_index;
 820   _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
 821   _jmp_ring[index]._target = (intptr_t) target;
 822   _jmp_ring[index]._instruction = (intptr_t) instr;
 823   _jmp_ring[index]._file = file;
 824   _jmp_ring[index]._line = line;
 825 }
 826 #endif // PRODUCT
 827 
 828 void Thread::interrupt(Thread* thread) {
 829   debug_only(check_for_dangling_thread_pointer(thread);)
 830   os::interrupt(thread);
 831 }
 832 
 833 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
 834   debug_only(check_for_dangling_thread_pointer(thread);)
 835   // Note:  If clear_interrupted==false, this simply fetches and
 836   // returns the value of the field osthread()->interrupted().
 837   return os::is_interrupted(thread, clear_interrupted);
 838 }
 839 
 840 
 841 // GC Support
 842 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
 843   int thread_parity = _oops_do_parity;
 844   if (thread_parity != strong_roots_parity) {
 845     jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
 846     if (res == thread_parity) {
 847       return true;
 848     } else {
 849       guarantee(res == strong_roots_parity, "Or else what?");
 850       return false;
 851     }
 852   }
 853   return false;
 854 }
 855 
 856 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
 857   active_handles()->oops_do(f);
 858   // Do oop for ThreadShadow
 859   f->do_oop((oop*)&_pending_exception);
 860   handle_area()->oops_do(f);
 861 
 862   if (MonitorInUseLists) {
 863     // When using thread local monitor lists, we scan them here,
 864     // and the remaining global monitors in ObjectSynchronizer::oops_do().
 865     ObjectSynchronizer::thread_local_used_oops_do(this, f);
 866   }
 867 }
 868 
 869 void Thread::metadata_handles_do(void f(Metadata*)) {
 870   // Only walk the Handles in Thread.
 871   if (metadata_handles() != NULL) {
 872     for (int i = 0; i< metadata_handles()->length(); i++) {
 873       f(metadata_handles()->at(i));
 874     }
 875   }
 876 }
 877 
 878 void Thread::print_on(outputStream* st) const {
 879   // get_priority assumes osthread initialized
 880   if (osthread() != NULL) {
 881     int os_prio;
 882     if (os::get_native_priority(this, &os_prio) == OS_OK) {
 883       st->print("os_prio=%d ", os_prio);
 884     }
 885 
 886     if (os::is_thread_cpu_time_supported()) {
 887       st->print("cpu=%.2fms ",
 888                 os::thread_cpu_time(const_cast<Thread*>(this), true) / 1000000.0
 889         );
 890       st->print("elapsed=%.2fs ",
 891                 _statistic_info.getElepsedTime() / 1000.0);
 892     }
 893 
 894     if (is_Java_thread()) {
 895       jlong allocated_bytes = const_cast<Thread*>(this)->cooked_allocated_bytes();
 896       st->print("allocated=" JLONG_FORMAT "B ", allocated_bytes);
 897       st->print("defined_classes=" INT64_FORMAT " ", _statistic_info.getDefineClassCount());
 898     }
 899 
 900     st->print("tid=" INTPTR_FORMAT " ", p2i(this));
 901     osthread()->print_on(st);
 902   }
 903   if (_threads_hazard_ptr != NULL) {
 904     st->print("_threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr));
 905   }
 906   if (_nested_threads_hazard_ptr != NULL) {
 907     print_nested_threads_hazard_ptrs_on(st);
 908   }
 909   st->print(" ");
 910   debug_only(if (WizardMode) print_owned_locks_on(st);)
 911 }
 912 
 913 void Thread::print_nested_threads_hazard_ptrs_on(outputStream* st) const {
 914   assert(_nested_threads_hazard_ptr != NULL, "must be set to print");
 915 
 916   if (EnableThreadSMRStatistics) {
 917     st->print(", _nested_threads_hazard_ptr_cnt=%u", _nested_threads_hazard_ptr_cnt);
 918   }
 919   st->print(", _nested_threads_hazard_ptrs=");
 920   for (NestedThreadsList* node = _nested_threads_hazard_ptr; node != NULL;
 921        node = node->next()) {
 922     if (node != _nested_threads_hazard_ptr) {
 923       // First node does not need a comma-space separator.
 924       st->print(", ");
 925     }
 926     st->print(INTPTR_FORMAT, p2i(node->t_list()));
 927   }
 928 }
 929 
 930 // Thread::print_on_error() is called by fatal error handler. Don't use
 931 // any lock or allocate memory.
 932 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
 933   assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
 934 
 935   if (is_VM_thread())                 { st->print("VMThread"); }
 936   else if (is_GC_task_thread())       { st->print("GCTaskThread"); }
 937   else if (is_Watcher_thread())       { st->print("WatcherThread"); }
 938   else if (is_ConcurrentGC_thread())  { st->print("ConcurrentGCThread"); }
 939   else                                { st->print("Thread"); }
 940 
 941   if (is_Named_thread()) {
 942     st->print(" \"%s\"", name());
 943   }
 944 
 945   st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
 946             p2i(stack_end()), p2i(stack_base()));
 947 
 948   if (osthread()) {
 949     st->print(" [id=%d]", osthread()->thread_id());
 950   }
 951 
 952   if (_threads_hazard_ptr != NULL) {
 953     st->print(" _threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr));
 954   }
 955   if (_nested_threads_hazard_ptr != NULL) {
 956     print_nested_threads_hazard_ptrs_on(st);
 957   }
 958 }
 959 
 960 void Thread::print_value_on(outputStream* st) const {
 961   if (is_Named_thread()) {
 962     st->print(" \"%s\" ", name());
 963   }
 964   st->print(INTPTR_FORMAT, p2i(this));   // print address
 965 }
 966 
 967 #ifdef ASSERT
 968 void Thread::print_owned_locks_on(outputStream* st) const {
 969   Monitor *cur = _owned_locks;
 970   if (cur == NULL) {
 971     st->print(" (no locks) ");
 972   } else {
 973     st->print_cr(" Locks owned:");
 974     while (cur) {
 975       cur->print_on(st);
 976       cur = cur->next();
 977     }
 978   }
 979 }
 980 
 981 static int ref_use_count  = 0;
 982 
 983 bool Thread::owns_locks_but_compiled_lock() const {
 984   for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 985     if (cur != Compile_lock) return true;
 986   }
 987   return false;
 988 }
 989 
 990 
 991 #endif
 992 
 993 #ifndef PRODUCT
 994 
 995 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially
 996 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that
 997 // no threads which allow_vm_block's are held
 998 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
 999   // Check if current thread is allowed to block at a safepoint
1000   if (!(_allow_safepoint_count == 0)) {
1001     fatal("Possible safepoint reached by thread that does not allow it");
1002   }
1003   if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
1004     fatal("LEAF method calling lock?");
1005   }
1006 
1007 #ifdef ASSERT
1008   if (potential_vm_operation && is_Java_thread()
1009       && !Universe::is_bootstrapping()) {
1010     // Make sure we do not hold any locks that the VM thread also uses.
1011     // This could potentially lead to deadlocks
1012     for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
1013       // Threads_lock is special, since the safepoint synchronization will not start before this is
1014       // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
1015       // since it is used to transfer control between JavaThreads and the VMThread
1016       // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
1017       if ((cur->allow_vm_block() &&
1018            cur != Threads_lock &&
1019            cur != Compile_lock &&               // Temporary: should not be necessary when we get separate compilation
1020            cur != VMOperationRequest_lock &&
1021            cur != VMOperationQueue_lock) ||
1022            cur->rank() == Mutex::special) {
1023         fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
1024       }
1025     }
1026   }
1027 
1028   if (GCALotAtAllSafepoints) {
1029     // We could enter a safepoint here and thus have a gc
1030     InterfaceSupport::check_gc_alot();
1031   }
1032 #endif
1033 }
1034 #endif
1035 
1036 bool Thread::is_in_stack(address adr) const {
1037   assert(Thread::current() == this, "is_in_stack can only be called from current thread");
1038   address end = os::current_stack_pointer();
1039   // Allow non Java threads to call this without stack_base
1040   if (_stack_base == NULL) return true;
1041   if (stack_base() >= adr && adr >= end) return true;
1042 
1043   return false;
1044 }
1045 
1046 bool Thread::is_in_usable_stack(address adr) const {
1047   size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
1048   size_t usable_stack_size = _stack_size - stack_guard_size;
1049 
1050   return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
1051 }
1052 
1053 
1054 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
1055 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
1056 // used for compilation in the future. If that change is made, the need for these methods
1057 // should be revisited, and they should be removed if possible.
1058 
1059 bool Thread::is_lock_owned(address adr) const {
1060   return on_local_stack(adr);
1061 }
1062 
1063 bool Thread::set_as_starting_thread() {
1064   // NOTE: this must be called inside the main thread.
1065   return os::create_main_thread((JavaThread*)this);
1066 }
1067 
1068 static void initialize_class(Symbol* class_name, TRAPS) {
1069   Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
1070   InstanceKlass::cast(klass)->initialize(CHECK);
1071 }
1072 
1073 
1074 // Creates the initial ThreadGroup
1075 static Handle create_initial_thread_group(TRAPS) {
1076   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
1077   InstanceKlass* ik = InstanceKlass::cast(k);
1078 
1079   Handle system_instance = ik->allocate_instance_handle(CHECK_NH);
1080   {
1081     JavaValue result(T_VOID);
1082     JavaCalls::call_special(&result,
1083                             system_instance,
1084                             ik,
1085                             vmSymbols::object_initializer_name(),
1086                             vmSymbols::void_method_signature(),
1087                             CHECK_NH);
1088   }
1089   Universe::set_system_thread_group(system_instance());
1090 
1091   Handle main_instance = ik->allocate_instance_handle(CHECK_NH);
1092   {
1093     JavaValue result(T_VOID);
1094     Handle string = java_lang_String::create_from_str("main", CHECK_NH);
1095     JavaCalls::call_special(&result,
1096                             main_instance,
1097                             ik,
1098                             vmSymbols::object_initializer_name(),
1099                             vmSymbols::threadgroup_string_void_signature(),
1100                             system_instance,
1101                             string,
1102                             CHECK_NH);
1103   }
1104   return main_instance;
1105 }
1106 
1107 // Creates the initial Thread
1108 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
1109                                  TRAPS) {
1110   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
1111   InstanceKlass* ik = InstanceKlass::cast(k);
1112   instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
1113 
1114   java_lang_Thread::set_thread(thread_oop(), thread);
1115   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1116   thread->set_threadObj(thread_oop());
1117 
1118   Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1119 
1120   JavaValue result(T_VOID);
1121   JavaCalls::call_special(&result, thread_oop,
1122                           ik,
1123                           vmSymbols::object_initializer_name(),
1124                           vmSymbols::threadgroup_string_void_signature(),
1125                           thread_group,
1126                           string,
1127                           CHECK_NULL);
1128   return thread_oop();
1129 }
1130 
1131 char java_runtime_name[128] = "";
1132 char java_runtime_version[128] = "";
1133 
1134 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1135 static const char* get_java_runtime_name(TRAPS) {
1136   Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1137                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1138   fieldDescriptor fd;
1139   bool found = k != NULL &&
1140                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1141                                                         vmSymbols::string_signature(), &fd);
1142   if (found) {
1143     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1144     if (name_oop == NULL) {
1145       return NULL;
1146     }
1147     const char* name = java_lang_String::as_utf8_string(name_oop,
1148                                                         java_runtime_name,
1149                                                         sizeof(java_runtime_name));
1150     return name;
1151   } else {
1152     return NULL;
1153   }
1154 }
1155 
1156 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1157 static const char* get_java_runtime_version(TRAPS) {
1158   Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1159                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1160   fieldDescriptor fd;
1161   bool found = k != NULL &&
1162                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1163                                                         vmSymbols::string_signature(), &fd);
1164   if (found) {
1165     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1166     if (name_oop == NULL) {
1167       return NULL;
1168     }
1169     const char* name = java_lang_String::as_utf8_string(name_oop,
1170                                                         java_runtime_version,
1171                                                         sizeof(java_runtime_version));
1172     return name;
1173   } else {
1174     return NULL;
1175   }
1176 }
1177 
1178 // General purpose hook into Java code, run once when the VM is initialized.
1179 // The Java library method itself may be changed independently from the VM.
1180 static void call_postVMInitHook(TRAPS) {
1181   Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1182   if (klass != NULL) {
1183     JavaValue result(T_VOID);
1184     JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1185                            vmSymbols::void_method_signature(),
1186                            CHECK);
1187   }
1188 }
1189 
1190 static void reset_vm_info_property(TRAPS) {
1191   // the vm info string
1192   ResourceMark rm(THREAD);
1193   const char *vm_info = VM_Version::vm_info_string();
1194 
1195   // java.lang.System class
1196   Klass* klass =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1197 
1198   // setProperty arguments
1199   Handle key_str    = java_lang_String::create_from_str("java.vm.info", CHECK);
1200   Handle value_str  = java_lang_String::create_from_str(vm_info, CHECK);
1201 
1202   // return value
1203   JavaValue r(T_OBJECT);
1204 
1205   // public static String setProperty(String key, String value);
1206   JavaCalls::call_static(&r,
1207                          klass,
1208                          vmSymbols::setProperty_name(),
1209                          vmSymbols::string_string_string_signature(),
1210                          key_str,
1211                          value_str,
1212                          CHECK);
1213 }
1214 
1215 
1216 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1217                                     bool daemon, TRAPS) {
1218   assert(thread_group.not_null(), "thread group should be specified");
1219   assert(threadObj() == NULL, "should only create Java thread object once");
1220 
1221   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1222   InstanceKlass* ik = InstanceKlass::cast(k);
1223   instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1224 
1225   java_lang_Thread::set_thread(thread_oop(), this);
1226   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1227   set_threadObj(thread_oop());
1228 
1229   JavaValue result(T_VOID);
1230   if (thread_name != NULL) {
1231     Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1232     // Thread gets assigned specified name and null target
1233     JavaCalls::call_special(&result,
1234                             thread_oop,
1235                             ik,
1236                             vmSymbols::object_initializer_name(),
1237                             vmSymbols::threadgroup_string_void_signature(),
1238                             thread_group, // Argument 1
1239                             name,         // Argument 2
1240                             THREAD);
1241   } else {
1242     // Thread gets assigned name "Thread-nnn" and null target
1243     // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1244     JavaCalls::call_special(&result,
1245                             thread_oop,
1246                             ik,
1247                             vmSymbols::object_initializer_name(),
1248                             vmSymbols::threadgroup_runnable_void_signature(),
1249                             thread_group, // Argument 1
1250                             Handle(),     // Argument 2
1251                             THREAD);
1252   }
1253 
1254 
1255   if (daemon) {
1256     java_lang_Thread::set_daemon(thread_oop());
1257   }
1258 
1259   if (HAS_PENDING_EXCEPTION) {
1260     return;
1261   }
1262 
1263   Klass* group =  SystemDictionary::ThreadGroup_klass();
1264   Handle threadObj(THREAD, this->threadObj());
1265 
1266   JavaCalls::call_special(&result,
1267                           thread_group,
1268                           group,
1269                           vmSymbols::add_method_name(),
1270                           vmSymbols::thread_void_signature(),
1271                           threadObj,          // Arg 1
1272                           THREAD);
1273 }
1274 
1275 // NamedThread --  non-JavaThread subclasses with multiple
1276 // uniquely named instances should derive from this.
1277 NamedThread::NamedThread() : Thread() {
1278   _name = NULL;
1279   _processed_thread = NULL;
1280   _gc_id = GCId::undefined();
1281 }
1282 
1283 NamedThread::~NamedThread() {
1284   if (_name != NULL) {
1285     FREE_C_HEAP_ARRAY(char, _name);
1286     _name = NULL;
1287   }
1288 }
1289 
1290 void NamedThread::set_name(const char* format, ...) {
1291   guarantee(_name == NULL, "Only get to set name once.");
1292   _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1293   guarantee(_name != NULL, "alloc failure");
1294   va_list ap;
1295   va_start(ap, format);
1296   jio_vsnprintf(_name, max_name_len, format, ap);
1297   va_end(ap);
1298 }
1299 
1300 void NamedThread::initialize_named_thread() {
1301   set_native_thread_name(name());
1302 }
1303 
1304 void NamedThread::print_on(outputStream* st) const {
1305   st->print("\"%s\" ", name());
1306   Thread::print_on(st);
1307   st->cr();
1308 }
1309 
1310 
1311 // ======= WatcherThread ========
1312 
1313 // The watcher thread exists to simulate timer interrupts.  It should
1314 // be replaced by an abstraction over whatever native support for
1315 // timer interrupts exists on the platform.
1316 
1317 WatcherThread* WatcherThread::_watcher_thread   = NULL;
1318 bool WatcherThread::_startable = false;
1319 volatile bool  WatcherThread::_should_terminate = false;
1320 
1321 WatcherThread::WatcherThread() : Thread() {
1322   assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1323   if (os::create_thread(this, os::watcher_thread)) {
1324     _watcher_thread = this;
1325 
1326     // Set the watcher thread to the highest OS priority which should not be
1327     // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1328     // is created. The only normal thread using this priority is the reference
1329     // handler thread, which runs for very short intervals only.
1330     // If the VMThread's priority is not lower than the WatcherThread profiling
1331     // will be inaccurate.
1332     os::set_priority(this, MaxPriority);
1333     if (!DisableStartThread) {
1334       os::start_thread(this);
1335     }
1336   }
1337 }
1338 
1339 int WatcherThread::sleep() const {
1340   // The WatcherThread does not participate in the safepoint protocol
1341   // for the PeriodicTask_lock because it is not a JavaThread.
1342   MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1343 
1344   if (_should_terminate) {
1345     // check for termination before we do any housekeeping or wait
1346     return 0;  // we did not sleep.
1347   }
1348 
1349   // remaining will be zero if there are no tasks,
1350   // causing the WatcherThread to sleep until a task is
1351   // enrolled
1352   int remaining = PeriodicTask::time_to_wait();
1353   int time_slept = 0;
1354 
1355   // we expect this to timeout - we only ever get unparked when
1356   // we should terminate or when a new task has been enrolled
1357   OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1358 
1359   jlong time_before_loop = os::javaTimeNanos();
1360 
1361   while (true) {
1362     bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1363                                             remaining);
1364     jlong now = os::javaTimeNanos();
1365 
1366     if (remaining == 0) {
1367       // if we didn't have any tasks we could have waited for a long time
1368       // consider the time_slept zero and reset time_before_loop
1369       time_slept = 0;
1370       time_before_loop = now;
1371     } else {
1372       // need to recalculate since we might have new tasks in _tasks
1373       time_slept = (int) ((now - time_before_loop) / 1000000);
1374     }
1375 
1376     // Change to task list or spurious wakeup of some kind
1377     if (timedout || _should_terminate) {
1378       break;
1379     }
1380 
1381     remaining = PeriodicTask::time_to_wait();
1382     if (remaining == 0) {
1383       // Last task was just disenrolled so loop around and wait until
1384       // another task gets enrolled
1385       continue;
1386     }
1387 
1388     remaining -= time_slept;
1389     if (remaining <= 0) {
1390       break;
1391     }
1392   }
1393 
1394   return time_slept;
1395 }
1396 
1397 void WatcherThread::run() {
1398   assert(this == watcher_thread(), "just checking");
1399 
1400   this->record_stack_base_and_size();
1401   this->set_native_thread_name(this->name());
1402   this->set_active_handles(JNIHandleBlock::allocate_block());
1403   while (true) {
1404     assert(watcher_thread() == Thread::current(), "thread consistency check");
1405     assert(watcher_thread() == this, "thread consistency check");
1406 
1407     // Calculate how long it'll be until the next PeriodicTask work
1408     // should be done, and sleep that amount of time.
1409     int time_waited = sleep();
1410 
1411     if (VMError::is_error_reported()) {
1412       // A fatal error has happened, the error handler(VMError::report_and_die)
1413       // should abort JVM after creating an error log file. However in some
1414       // rare cases, the error handler itself might deadlock. Here periodically
1415       // check for error reporting timeouts, and if it happens, just proceed to
1416       // abort the VM.
1417 
1418       // This code is in WatcherThread because WatcherThread wakes up
1419       // periodically so the fatal error handler doesn't need to do anything;
1420       // also because the WatcherThread is less likely to crash than other
1421       // threads.
1422 
1423       for (;;) {
1424         // Note: we use naked sleep in this loop because we want to avoid using
1425         // any kind of VM infrastructure which may be broken at this point.
1426         if (VMError::check_timeout()) {
1427           // We hit error reporting timeout. Error reporting was interrupted and
1428           // will be wrapping things up now (closing files etc). Give it some more
1429           // time, then quit the VM.
1430           os::naked_short_sleep(200);
1431           // Print a message to stderr.
1432           fdStream err(defaultStream::output_fd());
1433           err.print_raw_cr("# [ timer expired, abort... ]");
1434           // skip atexit/vm_exit/vm_abort hooks
1435           os::die();
1436         }
1437 
1438         // Wait a second, then recheck for timeout.
1439         os::naked_short_sleep(999);
1440       }
1441     }
1442 
1443     if (_should_terminate) {
1444       // check for termination before posting the next tick
1445       break;
1446     }
1447 
1448     PeriodicTask::real_time_tick(time_waited);
1449   }
1450 
1451   // Signal that it is terminated
1452   {
1453     MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1454     _watcher_thread = NULL;
1455     Terminator_lock->notify();
1456   }
1457 }
1458 
1459 void WatcherThread::start() {
1460   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1461 
1462   if (watcher_thread() == NULL && _startable) {
1463     _should_terminate = false;
1464     // Create the single instance of WatcherThread
1465     new WatcherThread();
1466   }
1467 }
1468 
1469 void WatcherThread::make_startable() {
1470   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1471   _startable = true;
1472 }
1473 
1474 void WatcherThread::stop() {
1475   {
1476     // Follow normal safepoint aware lock enter protocol since the
1477     // WatcherThread is stopped by another JavaThread.
1478     MutexLocker ml(PeriodicTask_lock);
1479     _should_terminate = true;
1480 
1481     WatcherThread* watcher = watcher_thread();
1482     if (watcher != NULL) {
1483       // unpark the WatcherThread so it can see that it should terminate
1484       watcher->unpark();
1485     }
1486   }
1487 
1488   MutexLocker mu(Terminator_lock);
1489 
1490   while (watcher_thread() != NULL) {
1491     // This wait should make safepoint checks, wait without a timeout,
1492     // and wait as a suspend-equivalent condition.
1493     Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1494                           Mutex::_as_suspend_equivalent_flag);
1495   }
1496 }
1497 
1498 void WatcherThread::unpark() {
1499   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1500   PeriodicTask_lock->notify();
1501 }
1502 
1503 void WatcherThread::print_on(outputStream* st) const {
1504   st->print("\"%s\" ", name());
1505   Thread::print_on(st);
1506   st->cr();
1507 }
1508 
1509 // ======= JavaThread ========
1510 
1511 #if INCLUDE_JVMCI
1512 
1513 jlong* JavaThread::_jvmci_old_thread_counters;
1514 
1515 bool jvmci_counters_include(JavaThread* thread) {
1516   oop threadObj = thread->threadObj();
1517   return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1518 }
1519 
1520 void JavaThread::collect_counters(typeArrayOop array) {
1521   if (JVMCICounterSize > 0) {
1522     MutexLocker tl(Threads_lock);
1523     JavaThreadIteratorWithHandle jtiwh;
1524     for (int i = 0; i < array->length(); i++) {
1525       array->long_at_put(i, _jvmci_old_thread_counters[i]);
1526     }
1527     for (; JavaThread *tp = jtiwh.next(); ) {
1528       if (jvmci_counters_include(tp)) {
1529         for (int i = 0; i < array->length(); i++) {
1530           array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1531         }
1532       }
1533     }
1534   }
1535 }
1536 
1537 #endif // INCLUDE_JVMCI
1538 
1539 // A JavaThread is a normal Java thread
1540 
1541 void JavaThread::initialize() {
1542   // Initialize fields
1543 
1544   set_saved_exception_pc(NULL);
1545   set_threadObj(NULL);
1546   _anchor.clear();
1547   set_entry_point(NULL);
1548   set_jni_functions(jni_functions());
1549   set_callee_target(NULL);
1550   set_vm_result(NULL);
1551   set_vm_result_2(NULL);
1552   set_vframe_array_head(NULL);
1553   set_vframe_array_last(NULL);
1554   set_deferred_locals(NULL);
1555   set_deopt_mark(NULL);
1556   set_deopt_compiled_method(NULL);
1557   clear_must_deopt_id();
1558   set_monitor_chunks(NULL);
1559   set_next(NULL);
1560   _on_thread_list = false;
1561   set_thread_state(_thread_new);
1562   _terminated = _not_terminated;
1563   _privileged_stack_top = NULL;
1564   _array_for_gc = NULL;
1565   _suspend_equivalent = false;
1566   _in_deopt_handler = 0;
1567   _doing_unsafe_access = false;
1568   _stack_guard_state = stack_guard_unused;
1569 #if INCLUDE_JVMCI
1570   _pending_monitorenter = false;
1571   _pending_deoptimization = -1;
1572   _pending_failed_speculation = NULL;
1573   _pending_transfer_to_interpreter = false;
1574   _adjusting_comp_level = false;
1575   _jvmci._alternate_call_target = NULL;
1576   assert(_jvmci._implicit_exception_pc == NULL, "must be");
1577   if (JVMCICounterSize > 0) {
1578     _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1579     memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1580   } else {
1581     _jvmci_counters = NULL;
1582   }
1583 #endif // INCLUDE_JVMCI
1584   _reserved_stack_activation = NULL;  // stack base not known yet
1585   (void)const_cast<oop&>(_exception_oop = oop(NULL));
1586   _exception_pc  = 0;
1587   _exception_handler_pc = 0;
1588   _is_method_handle_return = 0;
1589   _jvmti_thread_state= NULL;
1590   _should_post_on_exceptions_flag = JNI_FALSE;
1591   _jvmti_get_loaded_classes_closure = NULL;
1592   _interp_only_mode    = 0;
1593   _special_runtime_exit_condition = _no_async_condition;
1594   _pending_async_exception = NULL;
1595   _thread_stat = NULL;
1596   _thread_stat = new ThreadStatistics();
1597   _blocked_on_compilation = false;
1598   _jni_active_critical = 0;
1599   _pending_jni_exception_check_fn = NULL;
1600   _do_not_unlock_if_synchronized = false;
1601   _cached_monitor_info = NULL;
1602   _parker = Parker::Allocate(this);
1603 
1604 #ifndef PRODUCT
1605   _jmp_ring_index = 0;
1606   for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1607     record_jump(NULL, NULL, NULL, 0);
1608   }
1609 #endif // PRODUCT
1610 
1611   // Setup safepoint state info for this thread
1612   ThreadSafepointState::create(this);
1613 
1614   debug_only(_java_call_counter = 0);
1615 
1616   // JVMTI PopFrame support
1617   _popframe_condition = popframe_inactive;
1618   _popframe_preserved_args = NULL;
1619   _popframe_preserved_args_size = 0;
1620   _frames_to_pop_failed_realloc = 0;
1621 
1622   if (SafepointMechanism::uses_thread_local_poll()) {
1623     SafepointMechanism::initialize_header(this);
1624   }
1625 
1626   pd_initialize();
1627 }
1628 
1629 JavaThread::JavaThread(bool is_attaching_via_jni) :
1630                        Thread() {
1631   initialize();
1632   if (is_attaching_via_jni) {
1633     _jni_attach_state = _attaching_via_jni;
1634   } else {
1635     _jni_attach_state = _not_attaching_via_jni;
1636   }
1637   assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1638 }
1639 
1640 bool JavaThread::reguard_stack(address cur_sp) {
1641   if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1642       && _stack_guard_state != stack_guard_reserved_disabled) {
1643     return true; // Stack already guarded or guard pages not needed.
1644   }
1645 
1646   if (register_stack_overflow()) {
1647     // For those architectures which have separate register and
1648     // memory stacks, we must check the register stack to see if
1649     // it has overflowed.
1650     return false;
1651   }
1652 
1653   // Java code never executes within the yellow zone: the latter is only
1654   // there to provoke an exception during stack banging.  If java code
1655   // is executing there, either StackShadowPages should be larger, or
1656   // some exception code in c1, c2 or the interpreter isn't unwinding
1657   // when it should.
1658   guarantee(cur_sp > stack_reserved_zone_base(),
1659             "not enough space to reguard - increase StackShadowPages");
1660   if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1661     enable_stack_yellow_reserved_zone();
1662     if (reserved_stack_activation() != stack_base()) {
1663       set_reserved_stack_activation(stack_base());
1664     }
1665   } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1666     set_reserved_stack_activation(stack_base());
1667     enable_stack_reserved_zone();
1668   }
1669   return true;
1670 }
1671 
1672 bool JavaThread::reguard_stack(void) {
1673   return reguard_stack(os::current_stack_pointer());
1674 }
1675 
1676 
1677 void JavaThread::block_if_vm_exited() {
1678   if (_terminated == _vm_exited) {
1679     // _vm_exited is set at safepoint, and Threads_lock is never released
1680     // we will block here forever
1681     Threads_lock->lock_without_safepoint_check();
1682     ShouldNotReachHere();
1683   }
1684 }
1685 
1686 
1687 // Remove this ifdef when C1 is ported to the compiler interface.
1688 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1689 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1690 
1691 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1692                        Thread() {
1693   initialize();
1694   _jni_attach_state = _not_attaching_via_jni;
1695   set_entry_point(entry_point);
1696   // Create the native thread itself.
1697   // %note runtime_23
1698   os::ThreadType thr_type = os::java_thread;
1699   thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1700                                                      os::java_thread;
1701   os::create_thread(this, thr_type, stack_sz);
1702   // The _osthread may be NULL here because we ran out of memory (too many threads active).
1703   // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1704   // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1705   // the exception consists of creating the exception object & initializing it, initialization
1706   // will leave the VM via a JavaCall and then all locks must be unlocked).
1707   //
1708   // The thread is still suspended when we reach here. Thread must be explicit started
1709   // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1710   // by calling Threads:add. The reason why this is not done here, is because the thread
1711   // object must be fully initialized (take a look at JVM_Start)
1712 }
1713 
1714 JavaThread::~JavaThread() {
1715 
1716   // JSR166 -- return the parker to the free list
1717   Parker::Release(_parker);
1718   _parker = NULL;
1719 
1720   // Free any remaining  previous UnrollBlock
1721   vframeArray* old_array = vframe_array_last();
1722 
1723   if (old_array != NULL) {
1724     Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1725     old_array->set_unroll_block(NULL);
1726     delete old_info;
1727     delete old_array;
1728   }
1729 
1730   GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1731   if (deferred != NULL) {
1732     // This can only happen if thread is destroyed before deoptimization occurs.
1733     assert(deferred->length() != 0, "empty array!");
1734     do {
1735       jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1736       deferred->remove_at(0);
1737       // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1738       delete dlv;
1739     } while (deferred->length() != 0);
1740     delete deferred;
1741   }
1742 
1743   // All Java related clean up happens in exit
1744   ThreadSafepointState::destroy(this);
1745   if (_thread_stat != NULL) delete _thread_stat;
1746 
1747 #if INCLUDE_JVMCI
1748   if (JVMCICounterSize > 0) {
1749     if (jvmci_counters_include(this)) {
1750       for (int i = 0; i < JVMCICounterSize; i++) {
1751         _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1752       }
1753     }
1754     FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1755   }
1756 #endif // INCLUDE_JVMCI
1757 }
1758 
1759 
1760 // The first routine called by a new Java thread
1761 void JavaThread::run() {
1762   // initialize thread-local alloc buffer related fields
1763   this->initialize_tlab();
1764 
1765   // used to test validity of stack trace backs
1766   this->record_base_of_stack_pointer();
1767 
1768   // Record real stack base and size.
1769   this->record_stack_base_and_size();
1770 
1771   this->create_stack_guard_pages();
1772 
1773   this->cache_global_variables();
1774 
1775   // Thread is now sufficient initialized to be handled by the safepoint code as being
1776   // in the VM. Change thread state from _thread_new to _thread_in_vm
1777   ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1778 
1779   assert(JavaThread::current() == this, "sanity check");
1780   assert(!Thread::current()->owns_locks(), "sanity check");
1781 
1782   DTRACE_THREAD_PROBE(start, this);
1783 
1784   // This operation might block. We call that after all safepoint checks for a new thread has
1785   // been completed.
1786   this->set_active_handles(JNIHandleBlock::allocate_block());
1787 
1788   if (JvmtiExport::should_post_thread_life()) {
1789     JvmtiExport::post_thread_start(this);
1790   }
1791 
1792   EventThreadStart event;
1793   if (event.should_commit()) {
1794     event.set_thread(THREAD_TRACE_ID(this));
1795     event.commit();
1796   }
1797 
1798   // We call another function to do the rest so we are sure that the stack addresses used
1799   // from there will be lower than the stack base just computed
1800   thread_main_inner();
1801 
1802   // Note, thread is no longer valid at this point!
1803 }
1804 
1805 
1806 void JavaThread::thread_main_inner() {
1807   assert(JavaThread::current() == this, "sanity check");
1808   assert(this->threadObj() != NULL, "just checking");
1809 
1810   // Execute thread entry point unless this thread has a pending exception
1811   // or has been stopped before starting.
1812   // Note: Due to JVM_StopThread we can have pending exceptions already!
1813   if (!this->has_pending_exception() &&
1814       !java_lang_Thread::is_stillborn(this->threadObj())) {
1815     {
1816       ResourceMark rm(this);
1817       this->set_native_thread_name(this->get_thread_name());
1818     }
1819     HandleMark hm(this);
1820     this->entry_point()(this, this);
1821   }
1822 
1823   DTRACE_THREAD_PROBE(stop, this);
1824 
1825   this->exit(false);
1826   this->smr_delete();
1827 }
1828 
1829 
1830 static void ensure_join(JavaThread* thread) {
1831   // We do not need to grab the Threads_lock, since we are operating on ourself.
1832   Handle threadObj(thread, thread->threadObj());
1833   assert(threadObj.not_null(), "java thread object must exist");
1834   ObjectLocker lock(threadObj, thread);
1835   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1836   thread->clear_pending_exception();
1837   // Thread is exiting. So set thread_status field in  java.lang.Thread class to TERMINATED.
1838   java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1839   // Clear the native thread instance - this makes isAlive return false and allows the join()
1840   // to complete once we've done the notify_all below
1841   java_lang_Thread::set_thread(threadObj(), NULL);
1842   lock.notify_all(thread);
1843   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1844   thread->clear_pending_exception();
1845 }
1846 
1847 
1848 // For any new cleanup additions, please check to see if they need to be applied to
1849 // cleanup_failed_attach_current_thread as well.
1850 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1851   assert(this == JavaThread::current(), "thread consistency check");
1852 
1853   elapsedTimer _timer_exit_phase1;
1854   elapsedTimer _timer_exit_phase2;
1855   elapsedTimer _timer_exit_phase3;
1856   elapsedTimer _timer_exit_phase4;
1857 
1858   if (log_is_enabled(Debug, os, thread, timer)) {
1859     _timer_exit_phase1.start();
1860   }
1861 
1862   HandleMark hm(this);
1863   Handle uncaught_exception(this, this->pending_exception());
1864   this->clear_pending_exception();
1865   Handle threadObj(this, this->threadObj());
1866   assert(threadObj.not_null(), "Java thread object should be created");
1867 
1868   // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1869   {
1870     EXCEPTION_MARK;
1871 
1872     CLEAR_PENDING_EXCEPTION;
1873   }
1874   if (!destroy_vm) {
1875     if (uncaught_exception.not_null()) {
1876       EXCEPTION_MARK;
1877       // Call method Thread.dispatchUncaughtException().
1878       Klass* thread_klass = SystemDictionary::Thread_klass();
1879       JavaValue result(T_VOID);
1880       JavaCalls::call_virtual(&result,
1881                               threadObj, thread_klass,
1882                               vmSymbols::dispatchUncaughtException_name(),
1883                               vmSymbols::throwable_void_signature(),
1884                               uncaught_exception,
1885                               THREAD);
1886       if (HAS_PENDING_EXCEPTION) {
1887         ResourceMark rm(this);
1888         jio_fprintf(defaultStream::error_stream(),
1889                     "\nException: %s thrown from the UncaughtExceptionHandler"
1890                     " in thread \"%s\"\n",
1891                     pending_exception()->klass()->external_name(),
1892                     get_thread_name());
1893         CLEAR_PENDING_EXCEPTION;
1894       }
1895     }
1896 
1897     // Called before the java thread exit since we want to read info
1898     // from java_lang_Thread object
1899     EventThreadEnd event;
1900     if (event.should_commit()) {
1901       event.set_thread(THREAD_TRACE_ID(this));
1902       event.commit();
1903     }
1904 
1905     // Call after last event on thread
1906     EVENT_THREAD_EXIT(this);
1907 
1908     // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1909     // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1910     // is deprecated anyhow.
1911     if (!is_Compiler_thread()) {
1912       int count = 3;
1913       while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1914         EXCEPTION_MARK;
1915         JavaValue result(T_VOID);
1916         Klass* thread_klass = SystemDictionary::Thread_klass();
1917         JavaCalls::call_virtual(&result,
1918                                 threadObj, thread_klass,
1919                                 vmSymbols::exit_method_name(),
1920                                 vmSymbols::void_method_signature(),
1921                                 THREAD);
1922         CLEAR_PENDING_EXCEPTION;
1923       }
1924     }
1925     // notify JVMTI
1926     if (JvmtiExport::should_post_thread_life()) {
1927       JvmtiExport::post_thread_end(this);
1928     }
1929 
1930     // We have notified the agents that we are exiting, before we go on,
1931     // we must check for a pending external suspend request and honor it
1932     // in order to not surprise the thread that made the suspend request.
1933     while (true) {
1934       {
1935         MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1936         if (!is_external_suspend()) {
1937           set_terminated(_thread_exiting);
1938           ThreadService::current_thread_exiting(this);
1939           break;
1940         }
1941         // Implied else:
1942         // Things get a little tricky here. We have a pending external
1943         // suspend request, but we are holding the SR_lock so we
1944         // can't just self-suspend. So we temporarily drop the lock
1945         // and then self-suspend.
1946       }
1947 
1948       ThreadBlockInVM tbivm(this);
1949       java_suspend_self();
1950 
1951       // We're done with this suspend request, but we have to loop around
1952       // and check again. Eventually we will get SR_lock without a pending
1953       // external suspend request and will be able to mark ourselves as
1954       // exiting.
1955     }
1956     // no more external suspends are allowed at this point
1957   } else {
1958     // before_exit() has already posted JVMTI THREAD_END events
1959   }
1960 
1961   if (log_is_enabled(Debug, os, thread, timer)) {
1962     _timer_exit_phase1.stop();
1963     _timer_exit_phase2.start();
1964   }
1965   // Notify waiters on thread object. This has to be done after exit() is called
1966   // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1967   // group should have the destroyed bit set before waiters are notified).
1968   ensure_join(this);
1969   assert(!this->has_pending_exception(), "ensure_join should have cleared");
1970 
1971   if (log_is_enabled(Debug, os, thread, timer)) {
1972     _timer_exit_phase2.stop();
1973     _timer_exit_phase3.start();
1974   }
1975   // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1976   // held by this thread must be released. The spec does not distinguish
1977   // between JNI-acquired and regular Java monitors. We can only see
1978   // regular Java monitors here if monitor enter-exit matching is broken.
1979   //
1980   // Optionally release any monitors for regular JavaThread exits. This
1981   // is provided as a work around for any bugs in monitor enter-exit
1982   // matching. This can be expensive so it is not enabled by default.
1983   //
1984   // ensure_join() ignores IllegalThreadStateExceptions, and so does
1985   // ObjectSynchronizer::release_monitors_owned_by_thread().
1986   if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) {
1987     // Sanity check even though JNI DetachCurrentThread() would have
1988     // returned JNI_ERR if there was a Java frame. JavaThread exit
1989     // should be done executing Java code by the time we get here.
1990     assert(!this->has_last_Java_frame(),
1991            "should not have a Java frame when detaching or exiting");
1992     ObjectSynchronizer::release_monitors_owned_by_thread(this);
1993     assert(!this->has_pending_exception(), "release_monitors should have cleared");
1994   }
1995 
1996   // These things needs to be done while we are still a Java Thread. Make sure that thread
1997   // is in a consistent state, in case GC happens
1998   assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1999 
2000   if (active_handles() != NULL) {
2001     JNIHandleBlock* block = active_handles();
2002     set_active_handles(NULL);
2003     JNIHandleBlock::release_block(block);
2004   }
2005 
2006   if (free_handle_block() != NULL) {
2007     JNIHandleBlock* block = free_handle_block();
2008     set_free_handle_block(NULL);
2009     JNIHandleBlock::release_block(block);
2010   }
2011 
2012   // These have to be removed while this is still a valid thread.
2013   remove_stack_guard_pages();
2014 
2015   if (UseTLAB) {
2016     tlab().make_parsable(true);  // retire TLAB
2017   }
2018 
2019   if (JvmtiEnv::environments_might_exist()) {
2020     JvmtiExport::cleanup_thread(this);
2021   }
2022 
2023   // We must flush any deferred card marks and other various GC barrier
2024   // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer)
2025   // before removing a thread from the list of active threads.
2026   BarrierSet::barrier_set()->on_thread_detach(this);
2027 
2028   log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
2029     exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
2030     os::current_thread_id());
2031 
2032   if (log_is_enabled(Debug, os, thread, timer)) {
2033     _timer_exit_phase3.stop();
2034     _timer_exit_phase4.start();
2035   }
2036   // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
2037   Threads::remove(this);
2038 
2039   if (log_is_enabled(Debug, os, thread, timer)) {
2040     _timer_exit_phase4.stop();
2041     ResourceMark rm(this);
2042     log_debug(os, thread, timer)("name='%s'"
2043                                  ", exit-phase1=" JLONG_FORMAT
2044                                  ", exit-phase2=" JLONG_FORMAT
2045                                  ", exit-phase3=" JLONG_FORMAT
2046                                  ", exit-phase4=" JLONG_FORMAT,
2047                                  get_thread_name(),
2048                                  _timer_exit_phase1.milliseconds(),
2049                                  _timer_exit_phase2.milliseconds(),
2050                                  _timer_exit_phase3.milliseconds(),
2051                                  _timer_exit_phase4.milliseconds());
2052   }
2053 }
2054 
2055 void JavaThread::cleanup_failed_attach_current_thread() {
2056   if (active_handles() != NULL) {
2057     JNIHandleBlock* block = active_handles();
2058     set_active_handles(NULL);
2059     JNIHandleBlock::release_block(block);
2060   }
2061 
2062   if (free_handle_block() != NULL) {
2063     JNIHandleBlock* block = free_handle_block();
2064     set_free_handle_block(NULL);
2065     JNIHandleBlock::release_block(block);
2066   }
2067 
2068   // These have to be removed while this is still a valid thread.
2069   remove_stack_guard_pages();
2070 
2071   if (UseTLAB) {
2072     tlab().make_parsable(true);  // retire TLAB, if any
2073   }
2074 
2075   BarrierSet::barrier_set()->on_thread_detach(this);
2076 
2077   Threads::remove(this);
2078   this->smr_delete();
2079 }
2080 
2081 JavaThread* JavaThread::active() {
2082   Thread* thread = Thread::current();
2083   if (thread->is_Java_thread()) {
2084     return (JavaThread*) thread;
2085   } else {
2086     assert(thread->is_VM_thread(), "this must be a vm thread");
2087     VM_Operation* op = ((VMThread*) thread)->vm_operation();
2088     JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2089     assert(ret->is_Java_thread(), "must be a Java thread");
2090     return ret;
2091   }
2092 }
2093 
2094 bool JavaThread::is_lock_owned(address adr) const {
2095   if (Thread::is_lock_owned(adr)) return true;
2096 
2097   for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2098     if (chunk->contains(adr)) return true;
2099   }
2100 
2101   return false;
2102 }
2103 
2104 
2105 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2106   chunk->set_next(monitor_chunks());
2107   set_monitor_chunks(chunk);
2108 }
2109 
2110 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2111   guarantee(monitor_chunks() != NULL, "must be non empty");
2112   if (monitor_chunks() == chunk) {
2113     set_monitor_chunks(chunk->next());
2114   } else {
2115     MonitorChunk* prev = monitor_chunks();
2116     while (prev->next() != chunk) prev = prev->next();
2117     prev->set_next(chunk->next());
2118   }
2119 }
2120 
2121 // JVM support.
2122 
2123 // Note: this function shouldn't block if it's called in
2124 // _thread_in_native_trans state (such as from
2125 // check_special_condition_for_native_trans()).
2126 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2127 
2128   if (has_last_Java_frame() && has_async_condition()) {
2129     // If we are at a polling page safepoint (not a poll return)
2130     // then we must defer async exception because live registers
2131     // will be clobbered by the exception path. Poll return is
2132     // ok because the call we a returning from already collides
2133     // with exception handling registers and so there is no issue.
2134     // (The exception handling path kills call result registers but
2135     //  this is ok since the exception kills the result anyway).
2136 
2137     if (is_at_poll_safepoint()) {
2138       // if the code we are returning to has deoptimized we must defer
2139       // the exception otherwise live registers get clobbered on the
2140       // exception path before deoptimization is able to retrieve them.
2141       //
2142       RegisterMap map(this, false);
2143       frame caller_fr = last_frame().sender(&map);
2144       assert(caller_fr.is_compiled_frame(), "what?");
2145       if (caller_fr.is_deoptimized_frame()) {
2146         log_info(exceptions)("deferred async exception at compiled safepoint");
2147         return;
2148       }
2149     }
2150   }
2151 
2152   JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2153   if (condition == _no_async_condition) {
2154     // Conditions have changed since has_special_runtime_exit_condition()
2155     // was called:
2156     // - if we were here only because of an external suspend request,
2157     //   then that was taken care of above (or cancelled) so we are done
2158     // - if we were here because of another async request, then it has
2159     //   been cleared between the has_special_runtime_exit_condition()
2160     //   and now so again we are done
2161     return;
2162   }
2163 
2164   // Check for pending async. exception
2165   if (_pending_async_exception != NULL) {
2166     // Only overwrite an already pending exception, if it is not a threadDeath.
2167     if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2168 
2169       // We cannot call Exceptions::_throw(...) here because we cannot block
2170       set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2171 
2172       LogTarget(Info, exceptions) lt;
2173       if (lt.is_enabled()) {
2174         ResourceMark rm;
2175         LogStream ls(lt);
2176         ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2177           if (has_last_Java_frame()) {
2178             frame f = last_frame();
2179            ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2180           }
2181         ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2182       }
2183       _pending_async_exception = NULL;
2184       clear_has_async_exception();
2185     }
2186   }
2187 
2188   if (check_unsafe_error &&
2189       condition == _async_unsafe_access_error && !has_pending_exception()) {
2190     condition = _no_async_condition;  // done
2191     switch (thread_state()) {
2192     case _thread_in_vm: {
2193       JavaThread* THREAD = this;
2194       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2195     }
2196     case _thread_in_native: {
2197       ThreadInVMfromNative tiv(this);
2198       JavaThread* THREAD = this;
2199       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2200     }
2201     case _thread_in_Java: {
2202       ThreadInVMfromJava tiv(this);
2203       JavaThread* THREAD = this;
2204       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2205     }
2206     default:
2207       ShouldNotReachHere();
2208     }
2209   }
2210 
2211   assert(condition == _no_async_condition || has_pending_exception() ||
2212          (!check_unsafe_error && condition == _async_unsafe_access_error),
2213          "must have handled the async condition, if no exception");
2214 }
2215 
2216 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2217   //
2218   // Check for pending external suspend. Internal suspend requests do
2219   // not use handle_special_runtime_exit_condition().
2220   // If JNIEnv proxies are allowed, don't self-suspend if the target
2221   // thread is not the current thread. In older versions of jdbx, jdbx
2222   // threads could call into the VM with another thread's JNIEnv so we
2223   // can be here operating on behalf of a suspended thread (4432884).
2224   bool do_self_suspend = is_external_suspend_with_lock();
2225   if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2226     //
2227     // Because thread is external suspended the safepoint code will count
2228     // thread as at a safepoint. This can be odd because we can be here
2229     // as _thread_in_Java which would normally transition to _thread_blocked
2230     // at a safepoint. We would like to mark the thread as _thread_blocked
2231     // before calling java_suspend_self like all other callers of it but
2232     // we must then observe proper safepoint protocol. (We can't leave
2233     // _thread_blocked with a safepoint in progress). However we can be
2234     // here as _thread_in_native_trans so we can't use a normal transition
2235     // constructor/destructor pair because they assert on that type of
2236     // transition. We could do something like:
2237     //
2238     // JavaThreadState state = thread_state();
2239     // set_thread_state(_thread_in_vm);
2240     // {
2241     //   ThreadBlockInVM tbivm(this);
2242     //   java_suspend_self()
2243     // }
2244     // set_thread_state(_thread_in_vm_trans);
2245     // if (safepoint) block;
2246     // set_thread_state(state);
2247     //
2248     // but that is pretty messy. Instead we just go with the way the
2249     // code has worked before and note that this is the only path to
2250     // java_suspend_self that doesn't put the thread in _thread_blocked
2251     // mode.
2252 
2253     frame_anchor()->make_walkable(this);
2254     java_suspend_self();
2255 
2256     // We might be here for reasons in addition to the self-suspend request
2257     // so check for other async requests.
2258   }
2259 
2260   if (check_asyncs) {
2261     check_and_handle_async_exceptions();
2262   }
2263 #if INCLUDE_TRACE
2264   if (is_trace_suspend()) {
2265     TRACE_SUSPEND_THREAD(this);
2266   }
2267 #endif
2268 }
2269 
2270 void JavaThread::send_thread_stop(oop java_throwable)  {
2271   assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2272   assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2273   assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2274 
2275   // Do not throw asynchronous exceptions against the compiler thread
2276   // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2277   if (!can_call_java()) return;
2278 
2279   {
2280     // Actually throw the Throwable against the target Thread - however
2281     // only if there is no thread death exception installed already.
2282     if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2283       // If the topmost frame is a runtime stub, then we are calling into
2284       // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2285       // must deoptimize the caller before continuing, as the compiled  exception handler table
2286       // may not be valid
2287       if (has_last_Java_frame()) {
2288         frame f = last_frame();
2289         if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2290           // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2291           RegisterMap reg_map(this, UseBiasedLocking);
2292           frame compiled_frame = f.sender(&reg_map);
2293           if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2294             Deoptimization::deoptimize(this, compiled_frame, &reg_map);
2295           }
2296         }
2297       }
2298 
2299       // Set async. pending exception in thread.
2300       set_pending_async_exception(java_throwable);
2301 
2302       if (log_is_enabled(Info, exceptions)) {
2303          ResourceMark rm;
2304         log_info(exceptions)("Pending Async. exception installed of type: %s",
2305                              InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2306       }
2307       // for AbortVMOnException flag
2308       Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2309     }
2310   }
2311 
2312 
2313   // Interrupt thread so it will wake up from a potential wait()
2314   Thread::interrupt(this);
2315 }
2316 
2317 // External suspension mechanism.
2318 //
2319 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2320 // to any VM_locks and it is at a transition
2321 // Self-suspension will happen on the transition out of the vm.
2322 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2323 //
2324 // Guarantees on return:
2325 //   + Target thread will not execute any new bytecode (that's why we need to
2326 //     force a safepoint)
2327 //   + Target thread will not enter any new monitors
2328 //
2329 void JavaThread::java_suspend() {
2330   ThreadsListHandle tlh;
2331   if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) {
2332     return;
2333   }
2334 
2335   { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2336     if (!is_external_suspend()) {
2337       // a racing resume has cancelled us; bail out now
2338       return;
2339     }
2340 
2341     // suspend is done
2342     uint32_t debug_bits = 0;
2343     // Warning: is_ext_suspend_completed() may temporarily drop the
2344     // SR_lock to allow the thread to reach a stable thread state if
2345     // it is currently in a transient thread state.
2346     if (is_ext_suspend_completed(false /* !called_by_wait */,
2347                                  SuspendRetryDelay, &debug_bits)) {
2348       return;
2349     }
2350   }
2351 
2352   VM_ThreadSuspend vm_suspend;
2353   VMThread::execute(&vm_suspend);
2354 }
2355 
2356 // Part II of external suspension.
2357 // A JavaThread self suspends when it detects a pending external suspend
2358 // request. This is usually on transitions. It is also done in places
2359 // where continuing to the next transition would surprise the caller,
2360 // e.g., monitor entry.
2361 //
2362 // Returns the number of times that the thread self-suspended.
2363 //
2364 // Note: DO NOT call java_suspend_self() when you just want to block current
2365 //       thread. java_suspend_self() is the second stage of cooperative
2366 //       suspension for external suspend requests and should only be used
2367 //       to complete an external suspend request.
2368 //
2369 int JavaThread::java_suspend_self() {
2370   int ret = 0;
2371 
2372   // we are in the process of exiting so don't suspend
2373   if (is_exiting()) {
2374     clear_external_suspend();
2375     return ret;
2376   }
2377 
2378   assert(_anchor.walkable() ||
2379          (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2380          "must have walkable stack");
2381 
2382   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2383 
2384   assert(!this->is_ext_suspended(),
2385          "a thread trying to self-suspend should not already be suspended");
2386 
2387   if (this->is_suspend_equivalent()) {
2388     // If we are self-suspending as a result of the lifting of a
2389     // suspend equivalent condition, then the suspend_equivalent
2390     // flag is not cleared until we set the ext_suspended flag so
2391     // that wait_for_ext_suspend_completion() returns consistent
2392     // results.
2393     this->clear_suspend_equivalent();
2394   }
2395 
2396   // A racing resume may have cancelled us before we grabbed SR_lock
2397   // above. Or another external suspend request could be waiting for us
2398   // by the time we return from SR_lock()->wait(). The thread
2399   // that requested the suspension may already be trying to walk our
2400   // stack and if we return now, we can change the stack out from under
2401   // it. This would be a "bad thing (TM)" and cause the stack walker
2402   // to crash. We stay self-suspended until there are no more pending
2403   // external suspend requests.
2404   while (is_external_suspend()) {
2405     ret++;
2406     this->set_ext_suspended();
2407 
2408     // _ext_suspended flag is cleared by java_resume()
2409     while (is_ext_suspended()) {
2410       this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2411     }
2412   }
2413 
2414   return ret;
2415 }
2416 
2417 #ifdef ASSERT
2418 // Verify the JavaThread has not yet been published in the Threads::list, and
2419 // hence doesn't need protection from concurrent access at this stage.
2420 void JavaThread::verify_not_published() {
2421   // Cannot create a ThreadsListHandle here and check !tlh.includes(this)
2422   // since an unpublished JavaThread doesn't participate in the
2423   // Thread-SMR protocol for keeping a ThreadsList alive.
2424   assert(!on_thread_list(), "JavaThread shouldn't have been published yet!");
2425 }
2426 #endif
2427 
2428 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2429 // progress or when _suspend_flags is non-zero.
2430 // Current thread needs to self-suspend if there is a suspend request and/or
2431 // block if a safepoint is in progress.
2432 // Async exception ISN'T checked.
2433 // Note only the ThreadInVMfromNative transition can call this function
2434 // directly and when thread state is _thread_in_native_trans
2435 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2436   assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2437 
2438   JavaThread *curJT = JavaThread::current();
2439   bool do_self_suspend = thread->is_external_suspend();
2440 
2441   assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2442 
2443   // If JNIEnv proxies are allowed, don't self-suspend if the target
2444   // thread is not the current thread. In older versions of jdbx, jdbx
2445   // threads could call into the VM with another thread's JNIEnv so we
2446   // can be here operating on behalf of a suspended thread (4432884).
2447   if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2448     JavaThreadState state = thread->thread_state();
2449 
2450     // We mark this thread_blocked state as a suspend-equivalent so
2451     // that a caller to is_ext_suspend_completed() won't be confused.
2452     // The suspend-equivalent state is cleared by java_suspend_self().
2453     thread->set_suspend_equivalent();
2454 
2455     // If the safepoint code sees the _thread_in_native_trans state, it will
2456     // wait until the thread changes to other thread state. There is no
2457     // guarantee on how soon we can obtain the SR_lock and complete the
2458     // self-suspend request. It would be a bad idea to let safepoint wait for
2459     // too long. Temporarily change the state to _thread_blocked to
2460     // let the VM thread know that this thread is ready for GC. The problem
2461     // of changing thread state is that safepoint could happen just after
2462     // java_suspend_self() returns after being resumed, and VM thread will
2463     // see the _thread_blocked state. We must check for safepoint
2464     // after restoring the state and make sure we won't leave while a safepoint
2465     // is in progress.
2466     thread->set_thread_state(_thread_blocked);
2467     thread->java_suspend_self();
2468     thread->set_thread_state(state);
2469 
2470     InterfaceSupport::serialize_thread_state_with_handler(thread);
2471   }
2472 
2473   SafepointMechanism::block_if_requested(curJT);
2474 
2475   if (thread->is_deopt_suspend()) {
2476     thread->clear_deopt_suspend();
2477     RegisterMap map(thread, false);
2478     frame f = thread->last_frame();
2479     while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2480       f = f.sender(&map);
2481     }
2482     if (f.id() == thread->must_deopt_id()) {
2483       thread->clear_must_deopt_id();
2484       f.deoptimize(thread);
2485     } else {
2486       fatal("missed deoptimization!");
2487     }
2488   }
2489 #if INCLUDE_TRACE
2490   if (thread->is_trace_suspend()) {
2491     TRACE_SUSPEND_THREAD(thread);
2492   }
2493 #endif
2494 }
2495 
2496 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2497 // progress or when _suspend_flags is non-zero.
2498 // Current thread needs to self-suspend if there is a suspend request and/or
2499 // block if a safepoint is in progress.
2500 // Also check for pending async exception (not including unsafe access error).
2501 // Note only the native==>VM/Java barriers can call this function and when
2502 // thread state is _thread_in_native_trans.
2503 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2504   check_safepoint_and_suspend_for_native_trans(thread);
2505 
2506   if (thread->has_async_exception()) {
2507     // We are in _thread_in_native_trans state, don't handle unsafe
2508     // access error since that may block.
2509     thread->check_and_handle_async_exceptions(false);
2510   }
2511 }
2512 
2513 // This is a variant of the normal
2514 // check_special_condition_for_native_trans with slightly different
2515 // semantics for use by critical native wrappers.  It does all the
2516 // normal checks but also performs the transition back into
2517 // thread_in_Java state.  This is required so that critical natives
2518 // can potentially block and perform a GC if they are the last thread
2519 // exiting the GCLocker.
2520 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2521   check_special_condition_for_native_trans(thread);
2522 
2523   // Finish the transition
2524   thread->set_thread_state(_thread_in_Java);
2525 
2526   if (thread->do_critical_native_unlock()) {
2527     ThreadInVMfromJavaNoAsyncException tiv(thread);
2528     GCLocker::unlock_critical(thread);
2529     thread->clear_critical_native_unlock();
2530   }
2531 }
2532 
2533 // We need to guarantee the Threads_lock here, since resumes are not
2534 // allowed during safepoint synchronization
2535 // Can only resume from an external suspension
2536 void JavaThread::java_resume() {
2537   assert_locked_or_safepoint(Threads_lock);
2538 
2539   // Sanity check: thread is gone, has started exiting or the thread
2540   // was not externally suspended.
2541   ThreadsListHandle tlh;
2542   if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) {
2543     return;
2544   }
2545 
2546   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2547 
2548   clear_external_suspend();
2549 
2550   if (is_ext_suspended()) {
2551     clear_ext_suspended();
2552     SR_lock()->notify_all();
2553   }
2554 }
2555 
2556 size_t JavaThread::_stack_red_zone_size = 0;
2557 size_t JavaThread::_stack_yellow_zone_size = 0;
2558 size_t JavaThread::_stack_reserved_zone_size = 0;
2559 size_t JavaThread::_stack_shadow_zone_size = 0;
2560 
2561 void JavaThread::create_stack_guard_pages() {
2562   if (!os::uses_stack_guard_pages() ||
2563       _stack_guard_state != stack_guard_unused ||
2564       (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) {
2565       log_info(os, thread)("Stack guard page creation for thread "
2566                            UINTX_FORMAT " disabled", os::current_thread_id());
2567     return;
2568   }
2569   address low_addr = stack_end();
2570   size_t len = stack_guard_zone_size();
2571 
2572   assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2573   assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2574 
2575   int must_commit = os::must_commit_stack_guard_pages();
2576   // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2577 
2578   if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2579     log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2580     return;
2581   }
2582 
2583   if (os::guard_memory((char *) low_addr, len)) {
2584     _stack_guard_state = stack_guard_enabled;
2585   } else {
2586     log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2587       PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2588     if (os::uncommit_memory((char *) low_addr, len)) {
2589       log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2590     }
2591     return;
2592   }
2593 
2594   log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2595     PTR_FORMAT "-" PTR_FORMAT ".",
2596     os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2597 }
2598 
2599 void JavaThread::remove_stack_guard_pages() {
2600   assert(Thread::current() == this, "from different thread");
2601   if (_stack_guard_state == stack_guard_unused) return;
2602   address low_addr = stack_end();
2603   size_t len = stack_guard_zone_size();
2604 
2605   if (os::must_commit_stack_guard_pages()) {
2606     if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2607       _stack_guard_state = stack_guard_unused;
2608     } else {
2609       log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2610         PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2611       return;
2612     }
2613   } else {
2614     if (_stack_guard_state == stack_guard_unused) return;
2615     if (os::unguard_memory((char *) low_addr, len)) {
2616       _stack_guard_state = stack_guard_unused;
2617     } else {
2618       log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2619         PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2620       return;
2621     }
2622   }
2623 
2624   log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2625     PTR_FORMAT "-" PTR_FORMAT ".",
2626     os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2627 }
2628 
2629 void JavaThread::enable_stack_reserved_zone() {
2630   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2631   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2632 
2633   // The base notation is from the stack's point of view, growing downward.
2634   // We need to adjust it to work correctly with guard_memory()
2635   address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2636 
2637   guarantee(base < stack_base(),"Error calculating stack reserved zone");
2638   guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2639 
2640   if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2641     _stack_guard_state = stack_guard_enabled;
2642   } else {
2643     warning("Attempt to guard stack reserved zone failed.");
2644   }
2645   enable_register_stack_guard();
2646 }
2647 
2648 void JavaThread::disable_stack_reserved_zone() {
2649   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2650   assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2651 
2652   // Simply return if called for a thread that does not use guard pages.
2653   if (_stack_guard_state == stack_guard_unused) return;
2654 
2655   // The base notation is from the stack's point of view, growing downward.
2656   // We need to adjust it to work correctly with guard_memory()
2657   address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2658 
2659   if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2660     _stack_guard_state = stack_guard_reserved_disabled;
2661   } else {
2662     warning("Attempt to unguard stack reserved zone failed.");
2663   }
2664   disable_register_stack_guard();
2665 }
2666 
2667 void JavaThread::enable_stack_yellow_reserved_zone() {
2668   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2669   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2670 
2671   // The base notation is from the stacks point of view, growing downward.
2672   // We need to adjust it to work correctly with guard_memory()
2673   address base = stack_red_zone_base();
2674 
2675   guarantee(base < stack_base(), "Error calculating stack yellow zone");
2676   guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2677 
2678   if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2679     _stack_guard_state = stack_guard_enabled;
2680   } else {
2681     warning("Attempt to guard stack yellow zone failed.");
2682   }
2683   enable_register_stack_guard();
2684 }
2685 
2686 void JavaThread::disable_stack_yellow_reserved_zone() {
2687   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2688   assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2689 
2690   // Simply return if called for a thread that does not use guard pages.
2691   if (_stack_guard_state == stack_guard_unused) return;
2692 
2693   // The base notation is from the stacks point of view, growing downward.
2694   // We need to adjust it to work correctly with guard_memory()
2695   address base = stack_red_zone_base();
2696 
2697   if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2698     _stack_guard_state = stack_guard_yellow_reserved_disabled;
2699   } else {
2700     warning("Attempt to unguard stack yellow zone failed.");
2701   }
2702   disable_register_stack_guard();
2703 }
2704 
2705 void JavaThread::enable_stack_red_zone() {
2706   // The base notation is from the stacks point of view, growing downward.
2707   // We need to adjust it to work correctly with guard_memory()
2708   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2709   address base = stack_red_zone_base() - stack_red_zone_size();
2710 
2711   guarantee(base < stack_base(), "Error calculating stack red zone");
2712   guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2713 
2714   if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2715     warning("Attempt to guard stack red zone failed.");
2716   }
2717 }
2718 
2719 void JavaThread::disable_stack_red_zone() {
2720   // The base notation is from the stacks point of view, growing downward.
2721   // We need to adjust it to work correctly with guard_memory()
2722   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2723   address base = stack_red_zone_base() - stack_red_zone_size();
2724   if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2725     warning("Attempt to unguard stack red zone failed.");
2726   }
2727 }
2728 
2729 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2730   // ignore is there is no stack
2731   if (!has_last_Java_frame()) return;
2732   // traverse the stack frames. Starts from top frame.
2733   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2734     frame* fr = fst.current();
2735     f(fr, fst.register_map());
2736   }
2737 }
2738 
2739 
2740 #ifndef PRODUCT
2741 // Deoptimization
2742 // Function for testing deoptimization
2743 void JavaThread::deoptimize() {
2744   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2745   StackFrameStream fst(this, UseBiasedLocking);
2746   bool deopt = false;           // Dump stack only if a deopt actually happens.
2747   bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2748   // Iterate over all frames in the thread and deoptimize
2749   for (; !fst.is_done(); fst.next()) {
2750     if (fst.current()->can_be_deoptimized()) {
2751 
2752       if (only_at) {
2753         // Deoptimize only at particular bcis.  DeoptimizeOnlyAt
2754         // consists of comma or carriage return separated numbers so
2755         // search for the current bci in that string.
2756         address pc = fst.current()->pc();
2757         nmethod* nm =  (nmethod*) fst.current()->cb();
2758         ScopeDesc* sd = nm->scope_desc_at(pc);
2759         char buffer[8];
2760         jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2761         size_t len = strlen(buffer);
2762         const char * found = strstr(DeoptimizeOnlyAt, buffer);
2763         while (found != NULL) {
2764           if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2765               (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2766             // Check that the bci found is bracketed by terminators.
2767             break;
2768           }
2769           found = strstr(found + 1, buffer);
2770         }
2771         if (!found) {
2772           continue;
2773         }
2774       }
2775 
2776       if (DebugDeoptimization && !deopt) {
2777         deopt = true; // One-time only print before deopt
2778         tty->print_cr("[BEFORE Deoptimization]");
2779         trace_frames();
2780         trace_stack();
2781       }
2782       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2783     }
2784   }
2785 
2786   if (DebugDeoptimization && deopt) {
2787     tty->print_cr("[AFTER Deoptimization]");
2788     trace_frames();
2789   }
2790 }
2791 
2792 
2793 // Make zombies
2794 void JavaThread::make_zombies() {
2795   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2796     if (fst.current()->can_be_deoptimized()) {
2797       // it is a Java nmethod
2798       nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2799       nm->make_not_entrant();
2800     }
2801   }
2802 }
2803 #endif // PRODUCT
2804 
2805 
2806 void JavaThread::deoptimized_wrt_marked_nmethods() {
2807   if (!has_last_Java_frame()) return;
2808   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2809   StackFrameStream fst(this, UseBiasedLocking);
2810   for (; !fst.is_done(); fst.next()) {
2811     if (fst.current()->should_be_deoptimized()) {
2812       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2813     }
2814   }
2815 }
2816 
2817 
2818 // If the caller is a NamedThread, then remember, in the current scope,
2819 // the given JavaThread in its _processed_thread field.
2820 class RememberProcessedThread: public StackObj {
2821   NamedThread* _cur_thr;
2822  public:
2823   RememberProcessedThread(JavaThread* jthr) {
2824     Thread* thread = Thread::current();
2825     if (thread->is_Named_thread()) {
2826       _cur_thr = (NamedThread *)thread;
2827       _cur_thr->set_processed_thread(jthr);
2828     } else {
2829       _cur_thr = NULL;
2830     }
2831   }
2832 
2833   ~RememberProcessedThread() {
2834     if (_cur_thr) {
2835       _cur_thr->set_processed_thread(NULL);
2836     }
2837   }
2838 };
2839 
2840 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2841   // Verify that the deferred card marks have been flushed.
2842   assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2843 
2844   // Traverse the GCHandles
2845   Thread::oops_do(f, cf);
2846 
2847   JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);)
2848 
2849   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2850          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2851 
2852   if (has_last_Java_frame()) {
2853     // Record JavaThread to GC thread
2854     RememberProcessedThread rpt(this);
2855 
2856     // Traverse the privileged stack
2857     if (_privileged_stack_top != NULL) {
2858       _privileged_stack_top->oops_do(f);
2859     }
2860 
2861     // traverse the registered growable array
2862     if (_array_for_gc != NULL) {
2863       for (int index = 0; index < _array_for_gc->length(); index++) {
2864         f->do_oop(_array_for_gc->adr_at(index));
2865       }
2866     }
2867 
2868     // Traverse the monitor chunks
2869     for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2870       chunk->oops_do(f);
2871     }
2872 
2873     // Traverse the execution stack
2874     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2875       fst.current()->oops_do(f, cf, fst.register_map());
2876     }
2877   }
2878 
2879   // callee_target is never live across a gc point so NULL it here should
2880   // it still contain a methdOop.
2881 
2882   set_callee_target(NULL);
2883 
2884   assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2885   // If we have deferred set_locals there might be oops waiting to be
2886   // written
2887   GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2888   if (list != NULL) {
2889     for (int i = 0; i < list->length(); i++) {
2890       list->at(i)->oops_do(f);
2891     }
2892   }
2893 
2894   // Traverse instance variables at the end since the GC may be moving things
2895   // around using this function
2896   f->do_oop((oop*) &_threadObj);
2897   f->do_oop((oop*) &_vm_result);
2898   f->do_oop((oop*) &_exception_oop);
2899   f->do_oop((oop*) &_pending_async_exception);
2900 
2901   if (jvmti_thread_state() != NULL) {
2902     jvmti_thread_state()->oops_do(f);
2903   }
2904 }
2905 
2906 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2907   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2908          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2909 
2910   if (has_last_Java_frame()) {
2911     // Traverse the execution stack
2912     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2913       fst.current()->nmethods_do(cf);
2914     }
2915   }
2916 }
2917 
2918 void JavaThread::metadata_do(void f(Metadata*)) {
2919   if (has_last_Java_frame()) {
2920     // Traverse the execution stack to call f() on the methods in the stack
2921     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2922       fst.current()->metadata_do(f);
2923     }
2924   } else if (is_Compiler_thread()) {
2925     // need to walk ciMetadata in current compile tasks to keep alive.
2926     CompilerThread* ct = (CompilerThread*)this;
2927     if (ct->env() != NULL) {
2928       ct->env()->metadata_do(f);
2929     }
2930     CompileTask* task = ct->task();
2931     if (task != NULL) {
2932       task->metadata_do(f);
2933     }
2934   }
2935 }
2936 
2937 // Printing
2938 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2939   switch (_thread_state) {
2940   case _thread_uninitialized:     return "_thread_uninitialized";
2941   case _thread_new:               return "_thread_new";
2942   case _thread_new_trans:         return "_thread_new_trans";
2943   case _thread_in_native:         return "_thread_in_native";
2944   case _thread_in_native_trans:   return "_thread_in_native_trans";
2945   case _thread_in_vm:             return "_thread_in_vm";
2946   case _thread_in_vm_trans:       return "_thread_in_vm_trans";
2947   case _thread_in_Java:           return "_thread_in_Java";
2948   case _thread_in_Java_trans:     return "_thread_in_Java_trans";
2949   case _thread_blocked:           return "_thread_blocked";
2950   case _thread_blocked_trans:     return "_thread_blocked_trans";
2951   default:                        return "unknown thread state";
2952   }
2953 }
2954 
2955 #ifndef PRODUCT
2956 void JavaThread::print_thread_state_on(outputStream *st) const {
2957   st->print_cr("   JavaThread state: %s", _get_thread_state_name(_thread_state));
2958 };
2959 void JavaThread::print_thread_state() const {
2960   print_thread_state_on(tty);
2961 }
2962 #endif // PRODUCT
2963 
2964 // Called by Threads::print() for VM_PrintThreads operation
2965 void JavaThread::print_on(outputStream *st) const {
2966   st->print_raw("\"");
2967   st->print_raw(get_thread_name());
2968   st->print_raw("\" ");
2969   oop thread_oop = threadObj();
2970   if (thread_oop != NULL) {
2971     st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
2972     if (java_lang_Thread::is_daemon(thread_oop))  st->print("daemon ");
2973     st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2974   }
2975   Thread::print_on(st);
2976   // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2977   st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2978   if (thread_oop != NULL) {
2979     st->print_cr("   java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2980   }
2981 #ifndef PRODUCT
2982   print_thread_state_on(st);
2983   _safepoint_state->print_on(st);
2984 #endif // PRODUCT
2985   if (is_Compiler_thread()) {
2986     CompileTask *task = ((CompilerThread*)this)->task();
2987     if (task != NULL) {
2988       st->print("   Compiling: ");
2989       task->print(st, NULL, true, false);
2990     } else {
2991       st->print("   No compile task");
2992     }
2993     st->cr();
2994   }
2995 }
2996 
2997 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2998   st->print("%s", get_thread_name_string(buf, buflen));
2999 }
3000 
3001 // Called by fatal error handler. The difference between this and
3002 // JavaThread::print() is that we can't grab lock or allocate memory.
3003 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
3004   st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
3005   oop thread_obj = threadObj();
3006   if (thread_obj != NULL) {
3007     if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
3008   }
3009   st->print(" [");
3010   st->print("%s", _get_thread_state_name(_thread_state));
3011   if (osthread()) {
3012     st->print(", id=%d", osthread()->thread_id());
3013   }
3014   st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
3015             p2i(stack_end()), p2i(stack_base()));
3016   st->print("]");
3017 
3018   if (_threads_hazard_ptr != NULL) {
3019     st->print(" _threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr));
3020   }
3021   if (_nested_threads_hazard_ptr != NULL) {
3022     print_nested_threads_hazard_ptrs_on(st);
3023   }
3024   return;
3025 }
3026 
3027 // Verification
3028 
3029 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
3030 
3031 void JavaThread::verify() {
3032   // Verify oops in the thread.
3033   oops_do(&VerifyOopClosure::verify_oop, NULL);
3034 
3035   // Verify the stack frames.
3036   frames_do(frame_verify);
3037 }
3038 
3039 // CR 6300358 (sub-CR 2137150)
3040 // Most callers of this method assume that it can't return NULL but a
3041 // thread may not have a name whilst it is in the process of attaching to
3042 // the VM - see CR 6412693, and there are places where a JavaThread can be
3043 // seen prior to having it's threadObj set (eg JNI attaching threads and
3044 // if vm exit occurs during initialization). These cases can all be accounted
3045 // for such that this method never returns NULL.
3046 const char* JavaThread::get_thread_name() const {
3047 #ifdef ASSERT
3048   // early safepoints can hit while current thread does not yet have TLS
3049   if (!SafepointSynchronize::is_at_safepoint()) {
3050     Thread *cur = Thread::current();
3051     if (!(cur->is_Java_thread() && cur == this)) {
3052       // Current JavaThreads are allowed to get their own name without
3053       // the Threads_lock.
3054       assert_locked_or_safepoint(Threads_lock);
3055     }
3056   }
3057 #endif // ASSERT
3058   return get_thread_name_string();
3059 }
3060 
3061 // Returns a non-NULL representation of this thread's name, or a suitable
3062 // descriptive string if there is no set name
3063 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3064   const char* name_str;
3065   oop thread_obj = threadObj();
3066   if (thread_obj != NULL) {
3067     oop name = java_lang_Thread::name(thread_obj);
3068     if (name != NULL) {
3069       if (buf == NULL) {
3070         name_str = java_lang_String::as_utf8_string(name);
3071       } else {
3072         name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3073       }
3074     } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3075       name_str = "<no-name - thread is attaching>";
3076     } else {
3077       name_str = Thread::name();
3078     }
3079   } else {
3080     name_str = Thread::name();
3081   }
3082   assert(name_str != NULL, "unexpected NULL thread name");
3083   return name_str;
3084 }
3085 
3086 
3087 const char* JavaThread::get_threadgroup_name() const {
3088   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3089   oop thread_obj = threadObj();
3090   if (thread_obj != NULL) {
3091     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3092     if (thread_group != NULL) {
3093       // ThreadGroup.name can be null
3094       return java_lang_ThreadGroup::name(thread_group);
3095     }
3096   }
3097   return NULL;
3098 }
3099 
3100 const char* JavaThread::get_parent_name() const {
3101   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3102   oop thread_obj = threadObj();
3103   if (thread_obj != NULL) {
3104     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3105     if (thread_group != NULL) {
3106       oop parent = java_lang_ThreadGroup::parent(thread_group);
3107       if (parent != NULL) {
3108         // ThreadGroup.name can be null
3109         return java_lang_ThreadGroup::name(parent);
3110       }
3111     }
3112   }
3113   return NULL;
3114 }
3115 
3116 ThreadPriority JavaThread::java_priority() const {
3117   oop thr_oop = threadObj();
3118   if (thr_oop == NULL) return NormPriority; // Bootstrapping
3119   ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3120   assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3121   return priority;
3122 }
3123 
3124 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3125 
3126   assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3127   // Link Java Thread object <-> C++ Thread
3128 
3129   // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3130   // and put it into a new Handle.  The Handle "thread_oop" can then
3131   // be used to pass the C++ thread object to other methods.
3132 
3133   // Set the Java level thread object (jthread) field of the
3134   // new thread (a JavaThread *) to C++ thread object using the
3135   // "thread_oop" handle.
3136 
3137   // Set the thread field (a JavaThread *) of the
3138   // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3139 
3140   Handle thread_oop(Thread::current(),
3141                     JNIHandles::resolve_non_null(jni_thread));
3142   assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3143          "must be initialized");
3144   set_threadObj(thread_oop());
3145   java_lang_Thread::set_thread(thread_oop(), this);
3146 
3147   if (prio == NoPriority) {
3148     prio = java_lang_Thread::priority(thread_oop());
3149     assert(prio != NoPriority, "A valid priority should be present");
3150   }
3151 
3152   // Push the Java priority down to the native thread; needs Threads_lock
3153   Thread::set_priority(this, prio);
3154 
3155   // Add the new thread to the Threads list and set it in motion.
3156   // We must have threads lock in order to call Threads::add.
3157   // It is crucial that we do not block before the thread is
3158   // added to the Threads list for if a GC happens, then the java_thread oop
3159   // will not be visited by GC.
3160   Threads::add(this);
3161 }
3162 
3163 oop JavaThread::current_park_blocker() {
3164   // Support for JSR-166 locks
3165   oop thread_oop = threadObj();
3166   if (thread_oop != NULL &&
3167       JDK_Version::current().supports_thread_park_blocker()) {
3168     return java_lang_Thread::park_blocker(thread_oop);
3169   }
3170   return NULL;
3171 }
3172 
3173 
3174 void JavaThread::print_stack_on(outputStream* st) {
3175   if (!has_last_Java_frame()) return;
3176   ResourceMark rm;
3177   HandleMark   hm;
3178 
3179   RegisterMap reg_map(this);
3180   vframe* start_vf = last_java_vframe(&reg_map);
3181   int count = 0;
3182   for (vframe* f = start_vf; f != NULL; f = f->sender()) {
3183     if (f->is_java_frame()) {
3184       javaVFrame* jvf = javaVFrame::cast(f);
3185       java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3186 
3187       // Print out lock information
3188       if (JavaMonitorsInStackTrace) {
3189         jvf->print_lock_info_on(st, count);
3190       }
3191     } else {
3192       // Ignore non-Java frames
3193     }
3194 
3195     // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
3196     count++;
3197     if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
3198   }
3199 }
3200 
3201 
3202 // JVMTI PopFrame support
3203 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3204   assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3205   if (in_bytes(size_in_bytes) != 0) {
3206     _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3207     _popframe_preserved_args_size = in_bytes(size_in_bytes);
3208     Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3209   }
3210 }
3211 
3212 void* JavaThread::popframe_preserved_args() {
3213   return _popframe_preserved_args;
3214 }
3215 
3216 ByteSize JavaThread::popframe_preserved_args_size() {
3217   return in_ByteSize(_popframe_preserved_args_size);
3218 }
3219 
3220 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3221   int sz = in_bytes(popframe_preserved_args_size());
3222   assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3223   return in_WordSize(sz / wordSize);
3224 }
3225 
3226 void JavaThread::popframe_free_preserved_args() {
3227   assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3228   FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3229   _popframe_preserved_args = NULL;
3230   _popframe_preserved_args_size = 0;
3231 }
3232 
3233 #ifndef PRODUCT
3234 
3235 void JavaThread::trace_frames() {
3236   tty->print_cr("[Describe stack]");
3237   int frame_no = 1;
3238   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3239     tty->print("  %d. ", frame_no++);
3240     fst.current()->print_value_on(tty, this);
3241     tty->cr();
3242   }
3243 }
3244 
3245 class PrintAndVerifyOopClosure: public OopClosure {
3246  protected:
3247   template <class T> inline void do_oop_work(T* p) {
3248     oop obj = RawAccess<>::oop_load(p);
3249     if (obj == NULL) return;
3250     tty->print(INTPTR_FORMAT ": ", p2i(p));
3251     if (oopDesc::is_oop_or_null(obj)) {
3252       if (obj->is_objArray()) {
3253         tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3254       } else {
3255         obj->print();
3256       }
3257     } else {
3258       tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3259     }
3260     tty->cr();
3261   }
3262  public:
3263   virtual void do_oop(oop* p) { do_oop_work(p); }
3264   virtual void do_oop(narrowOop* p)  { do_oop_work(p); }
3265 };
3266 
3267 
3268 static void oops_print(frame* f, const RegisterMap *map) {
3269   PrintAndVerifyOopClosure print;
3270   f->print_value();
3271   f->oops_do(&print, NULL, (RegisterMap*)map);
3272 }
3273 
3274 // Print our all the locations that contain oops and whether they are
3275 // valid or not.  This useful when trying to find the oldest frame
3276 // where an oop has gone bad since the frame walk is from youngest to
3277 // oldest.
3278 void JavaThread::trace_oops() {
3279   tty->print_cr("[Trace oops]");
3280   frames_do(oops_print);
3281 }
3282 
3283 
3284 #ifdef ASSERT
3285 // Print or validate the layout of stack frames
3286 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3287   ResourceMark rm;
3288   PRESERVE_EXCEPTION_MARK;
3289   FrameValues values;
3290   int frame_no = 0;
3291   for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3292     fst.current()->describe(values, ++frame_no);
3293     if (depth == frame_no) break;
3294   }
3295   if (validate_only) {
3296     values.validate();
3297   } else {
3298     tty->print_cr("[Describe stack layout]");
3299     values.print(this);
3300   }
3301 }
3302 #endif
3303 
3304 void JavaThread::trace_stack_from(vframe* start_vf) {
3305   ResourceMark rm;
3306   int vframe_no = 1;
3307   for (vframe* f = start_vf; f; f = f->sender()) {
3308     if (f->is_java_frame()) {
3309       javaVFrame::cast(f)->print_activation(vframe_no++);
3310     } else {
3311       f->print();
3312     }
3313     if (vframe_no > StackPrintLimit) {
3314       tty->print_cr("...<more frames>...");
3315       return;
3316     }
3317   }
3318 }
3319 
3320 
3321 void JavaThread::trace_stack() {
3322   if (!has_last_Java_frame()) return;
3323   ResourceMark rm;
3324   HandleMark   hm;
3325   RegisterMap reg_map(this);
3326   trace_stack_from(last_java_vframe(&reg_map));
3327 }
3328 
3329 
3330 #endif // PRODUCT
3331 
3332 
3333 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3334   assert(reg_map != NULL, "a map must be given");
3335   frame f = last_frame();
3336   for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3337     if (vf->is_java_frame()) return javaVFrame::cast(vf);
3338   }
3339   return NULL;
3340 }
3341 
3342 
3343 Klass* JavaThread::security_get_caller_class(int depth) {
3344   vframeStream vfst(this);
3345   vfst.security_get_caller_frame(depth);
3346   if (!vfst.at_end()) {
3347     return vfst.method()->method_holder();
3348   }
3349   return NULL;
3350 }
3351 
3352 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3353   assert(thread->is_Compiler_thread(), "must be compiler thread");
3354   CompileBroker::compiler_thread_loop();
3355 }
3356 
3357 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3358   NMethodSweeper::sweeper_loop();
3359 }
3360 
3361 // Create a CompilerThread
3362 CompilerThread::CompilerThread(CompileQueue* queue,
3363                                CompilerCounters* counters)
3364                                : JavaThread(&compiler_thread_entry) {
3365   _env   = NULL;
3366   _log   = NULL;
3367   _task  = NULL;
3368   _queue = queue;
3369   _counters = counters;
3370   _buffer_blob = NULL;
3371   _compiler = NULL;
3372 
3373   // Compiler uses resource area for compilation, let's bias it to mtCompiler
3374   resource_area()->bias_to(mtCompiler);
3375 
3376 #ifndef PRODUCT
3377   _ideal_graph_printer = NULL;
3378 #endif
3379 }
3380 
3381 bool CompilerThread::can_call_java() const {
3382   return _compiler != NULL && _compiler->is_jvmci();
3383 }
3384 
3385 // Create sweeper thread
3386 CodeCacheSweeperThread::CodeCacheSweeperThread()
3387 : JavaThread(&sweeper_thread_entry) {
3388   _scanned_compiled_method = NULL;
3389 }
3390 
3391 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3392   JavaThread::oops_do(f, cf);
3393   if (_scanned_compiled_method != NULL && cf != NULL) {
3394     // Safepoints can occur when the sweeper is scanning an nmethod so
3395     // process it here to make sure it isn't unloaded in the middle of
3396     // a scan.
3397     cf->do_code_blob(_scanned_compiled_method);
3398   }
3399 }
3400 
3401 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3402   JavaThread::nmethods_do(cf);
3403   if (_scanned_compiled_method != NULL && cf != NULL) {
3404     // Safepoints can occur when the sweeper is scanning an nmethod so
3405     // process it here to make sure it isn't unloaded in the middle of
3406     // a scan.
3407     cf->do_code_blob(_scanned_compiled_method);
3408   }
3409 }
3410 
3411 
3412 // ======= Threads ========
3413 
3414 // The Threads class links together all active threads, and provides
3415 // operations over all threads. It is protected by the Threads_lock,
3416 // which is also used in other global contexts like safepointing.
3417 // ThreadsListHandles are used to safely perform operations on one
3418 // or more threads without the risk of the thread exiting during the
3419 // operation.
3420 //
3421 // Note: The Threads_lock is currently more widely used than we
3422 // would like. We are actively migrating Threads_lock uses to other
3423 // mechanisms in order to reduce Threads_lock contention.
3424 
3425 JavaThread* Threads::_thread_list = NULL;
3426 int         Threads::_number_of_threads = 0;
3427 int         Threads::_number_of_non_daemon_threads = 0;
3428 int         Threads::_return_code = 0;
3429 int         Threads::_thread_claim_parity = 0;
3430 size_t      JavaThread::_stack_size_at_create = 0;
3431 
3432 #ifdef ASSERT
3433 bool        Threads::_vm_complete = false;
3434 #endif
3435 
3436 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
3437   Prefetch::read((void*)addr, prefetch_interval);
3438   return *addr;
3439 }
3440 
3441 // Possibly the ugliest for loop the world has seen. C++ does not allow
3442 // multiple types in the declaration section of the for loop. In this case
3443 // we are only dealing with pointers and hence can cast them. It looks ugly
3444 // but macros are ugly and therefore it's fine to make things absurdly ugly.
3445 #define DO_JAVA_THREADS(LIST, X)                                                                                          \
3446     for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes,                           \
3447              *MACRO_list = (JavaThread*)(LIST),                                                                           \
3448              **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(),  \
3449              **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(),                                     \
3450              *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval);                 \
3451          MACRO_current_p != MACRO_end;                                                                                    \
3452          MACRO_current_p++,                                                                                               \
3453              X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval))
3454 
3455 // All JavaThreads
3456 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X)
3457 
3458 // All non-JavaThreads (i.e., every non-JavaThread in the system).
3459 void Threads::non_java_threads_do(ThreadClosure* tc) {
3460   // Someday we could have a table or list of all non-JavaThreads.
3461   // For now, just manually iterate through them.
3462   tc->do_thread(VMThread::vm_thread());
3463   if (Universe::heap() != NULL) {
3464     Universe::heap()->gc_threads_do(tc);
3465   }
3466   WatcherThread *wt = WatcherThread::watcher_thread();
3467   // Strictly speaking, the following NULL check isn't sufficient to make sure
3468   // the data for WatcherThread is still valid upon being examined. However,
3469   // considering that WatchThread terminates when the VM is on the way to
3470   // exit at safepoint, the chance of the above is extremely small. The right
3471   // way to prevent termination of WatcherThread would be to acquire
3472   // Terminator_lock, but we can't do that without violating the lock rank
3473   // checking in some cases.
3474   if (wt != NULL) {
3475     tc->do_thread(wt);
3476   }
3477 
3478 #if INCLUDE_TRACE
3479   Thread* sampler_thread = TracingExport::sampler_thread_acquire();
3480   if (sampler_thread != NULL) {
3481     tc->do_thread(sampler_thread);
3482   }
3483 #endif
3484 
3485   // If CompilerThreads ever become non-JavaThreads, add them here
3486 }
3487 
3488 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system).
3489 void Threads::threads_do(ThreadClosure* tc) {
3490   assert_locked_or_safepoint(Threads_lock);
3491   // ALL_JAVA_THREADS iterates through all JavaThreads.
3492   ALL_JAVA_THREADS(p) {
3493     tc->do_thread(p);
3494   }
3495   non_java_threads_do(tc);
3496 }
3497 
3498 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
3499   int cp = Threads::thread_claim_parity();
3500   ALL_JAVA_THREADS(p) {
3501     if (p->claim_oops_do(is_par, cp)) {
3502       tc->do_thread(p);
3503     }
3504   }
3505   VMThread* vmt = VMThread::vm_thread();
3506   if (vmt->claim_oops_do(is_par, cp)) {
3507     tc->do_thread(vmt);
3508   }
3509 }
3510 
3511 // The system initialization in the library has three phases.
3512 //
3513 // Phase 1: java.lang.System class initialization
3514 //     java.lang.System is a primordial class loaded and initialized
3515 //     by the VM early during startup.  java.lang.System.<clinit>
3516 //     only does registerNatives and keeps the rest of the class
3517 //     initialization work later until thread initialization completes.
3518 //
3519 //     System.initPhase1 initializes the system properties, the static
3520 //     fields in, out, and err. Set up java signal handlers, OS-specific
3521 //     system settings, and thread group of the main thread.
3522 static void call_initPhase1(TRAPS) {
3523   Klass* klass =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3524   JavaValue result(T_VOID);
3525   JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3526                                          vmSymbols::void_method_signature(), CHECK);
3527 }
3528 
3529 // Phase 2. Module system initialization
3530 //     This will initialize the module system.  Only java.base classes
3531 //     can be loaded until phase 2 completes.
3532 //
3533 //     Call System.initPhase2 after the compiler initialization and jsr292
3534 //     classes get initialized because module initialization runs a lot of java
3535 //     code, that for performance reasons, should be compiled.  Also, this will
3536 //     enable the startup code to use lambda and other language features in this
3537 //     phase and onward.
3538 //
3539 //     After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3540 static void call_initPhase2(TRAPS) {
3541   TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3542 
3543   Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3544 
3545   JavaValue result(T_INT);
3546   JavaCallArguments args;
3547   args.push_int(DisplayVMOutputToStderr);
3548   args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3549   JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3550                                          vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3551   if (result.get_jint() != JNI_OK) {
3552     vm_exit_during_initialization(); // no message or exception
3553   }
3554 
3555   universe_post_module_init();
3556 }
3557 
3558 // Phase 3. final setup - set security manager, system class loader and TCCL
3559 //
3560 //     This will instantiate and set the security manager, set the system class
3561 //     loader as well as the thread context class loader.  The security manager
3562 //     and system class loader may be a custom class loaded from -Xbootclasspath/a,
3563 //     other modules or the application's classpath.
3564 static void call_initPhase3(TRAPS) {
3565   Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3566   JavaValue result(T_VOID);
3567   JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3568                                          vmSymbols::void_method_signature(), CHECK);
3569 }
3570 
3571 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3572   TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3573 
3574   if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3575     create_vm_init_libraries();
3576   }
3577 
3578   initialize_class(vmSymbols::java_lang_String(), CHECK);
3579 
3580   // Inject CompactStrings value after the static initializers for String ran.
3581   java_lang_String::set_compact_strings(CompactStrings);
3582 
3583   // Initialize java_lang.System (needed before creating the thread)
3584   initialize_class(vmSymbols::java_lang_System(), CHECK);
3585   // The VM creates & returns objects of this class. Make sure it's initialized.
3586   initialize_class(vmSymbols::java_lang_Class(), CHECK);
3587   initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3588   Handle thread_group = create_initial_thread_group(CHECK);
3589   Universe::set_main_thread_group(thread_group());
3590   initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3591   oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3592   main_thread->set_threadObj(thread_object);
3593   // Set thread status to running since main thread has
3594   // been started and running.
3595   java_lang_Thread::set_thread_status(thread_object,
3596                                       java_lang_Thread::RUNNABLE);
3597 
3598   // The VM creates objects of this class.
3599   initialize_class(vmSymbols::java_lang_Module(), CHECK);
3600 
3601   // The VM preresolves methods to these classes. Make sure that they get initialized
3602   initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3603   initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3604 
3605   // Phase 1 of the system initialization in the library, java.lang.System class initialization
3606   call_initPhase1(CHECK);
3607 
3608   // get the Java runtime name after java.lang.System is initialized
3609   JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3610   JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3611 
3612   // an instance of OutOfMemory exception has been allocated earlier
3613   initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3614   initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3615   initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3616   initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3617   initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3618   initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3619   initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3620   initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3621 }
3622 
3623 void Threads::initialize_jsr292_core_classes(TRAPS) {
3624   TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3625 
3626   initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3627   initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3628   initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3629   initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3630 }
3631 
3632 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3633   extern void JDK_Version_init();
3634 
3635   // Preinitialize version info.
3636   VM_Version::early_initialize();
3637 
3638   // Check version
3639   if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3640 
3641   // Initialize library-based TLS
3642   ThreadLocalStorage::init();
3643 
3644   // Initialize the output stream module
3645   ostream_init();
3646 
3647   // Process java launcher properties.
3648   Arguments::process_sun_java_launcher_properties(args);
3649 
3650   // Initialize the os module
3651   os::init();
3652 
3653   // Record VM creation timing statistics
3654   TraceVmCreationTime create_vm_timer;
3655   create_vm_timer.start();
3656 
3657   // Initialize system properties.
3658   Arguments::init_system_properties();
3659 
3660   // So that JDK version can be used as a discriminator when parsing arguments
3661   JDK_Version_init();
3662 
3663   // Update/Initialize System properties after JDK version number is known
3664   Arguments::init_version_specific_system_properties();
3665 
3666   // Make sure to initialize log configuration *before* parsing arguments
3667   LogConfiguration::initialize(create_vm_timer.begin_time());
3668 
3669   // Parse arguments
3670   // Note: this internally calls os::init_container_support()
3671   jint parse_result = Arguments::parse(args);
3672   if (parse_result != JNI_OK) return parse_result;
3673 
3674   os::init_before_ergo();
3675 
3676   jint ergo_result = Arguments::apply_ergo();
3677   if (ergo_result != JNI_OK) return ergo_result;
3678 
3679   // Final check of all ranges after ergonomics which may change values.
3680   if (!CommandLineFlagRangeList::check_ranges()) {
3681     return JNI_EINVAL;
3682   }
3683 
3684   // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3685   bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo);
3686   if (!constraint_result) {
3687     return JNI_EINVAL;
3688   }
3689 
3690   CommandLineFlagWriteableList::mark_startup();
3691 
3692   if (PauseAtStartup) {
3693     os::pause();
3694   }
3695 
3696   HOTSPOT_VM_INIT_BEGIN();
3697 
3698   // Timing (must come after argument parsing)
3699   TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3700 
3701 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT
3702   // Initialize assert poison page mechanism.
3703   if (ShowRegistersOnAssert) {
3704     initialize_assert_poison();
3705   }
3706 #endif // CAN_SHOW_REGISTERS_ON_ASSERT
3707 
3708   // Initialize the os module after parsing the args
3709   jint os_init_2_result = os::init_2();
3710   if (os_init_2_result != JNI_OK) return os_init_2_result;
3711 
3712   SafepointMechanism::initialize();
3713 
3714   jint adjust_after_os_result = Arguments::adjust_after_os();
3715   if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3716 
3717   // Initialize output stream logging
3718   ostream_init_log();
3719 
3720   // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3721   // Must be before create_vm_init_agents()
3722   if (Arguments::init_libraries_at_startup()) {
3723     convert_vm_init_libraries_to_agents();
3724   }
3725 
3726   // Launch -agentlib/-agentpath and converted -Xrun agents
3727   if (Arguments::init_agents_at_startup()) {
3728     create_vm_init_agents();
3729   }
3730 
3731   // Initialize Threads state
3732   _thread_list = NULL;
3733   _number_of_threads = 0;
3734   _number_of_non_daemon_threads = 0;
3735 
3736   // Initialize global data structures and create system classes in heap
3737   vm_init_globals();
3738 
3739 #if INCLUDE_JVMCI
3740   if (JVMCICounterSize > 0) {
3741     JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3742     memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3743   } else {
3744     JavaThread::_jvmci_old_thread_counters = NULL;
3745   }
3746 #endif // INCLUDE_JVMCI
3747 
3748   // Attach the main thread to this os thread
3749   JavaThread* main_thread = new JavaThread();
3750   main_thread->set_thread_state(_thread_in_vm);
3751   main_thread->initialize_thread_current();
3752   // must do this before set_active_handles
3753   main_thread->record_stack_base_and_size();
3754   main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3755 
3756   if (!main_thread->set_as_starting_thread()) {
3757     vm_shutdown_during_initialization(
3758                                       "Failed necessary internal allocation. Out of swap space");
3759     main_thread->smr_delete();
3760     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3761     return JNI_ENOMEM;
3762   }
3763 
3764   // Enable guard page *after* os::create_main_thread(), otherwise it would
3765   // crash Linux VM, see notes in os_linux.cpp.
3766   main_thread->create_stack_guard_pages();
3767 
3768   // Initialize Java-Level synchronization subsystem
3769   ObjectMonitor::Initialize();
3770 
3771   // Initialize global modules
3772   jint status = init_globals();
3773   if (status != JNI_OK) {
3774     main_thread->smr_delete();
3775     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3776     return status;
3777   }
3778 
3779   if (TRACE_INITIALIZE() != JNI_OK) {
3780     vm_exit_during_initialization("Failed to initialize tracing backend");
3781   }
3782 
3783   // Should be done after the heap is fully created
3784   main_thread->cache_global_variables();
3785 
3786   HandleMark hm;
3787 
3788   { MutexLocker mu(Threads_lock);
3789     Threads::add(main_thread);
3790   }
3791 
3792   // Any JVMTI raw monitors entered in onload will transition into
3793   // real raw monitor. VM is setup enough here for raw monitor enter.
3794   JvmtiExport::transition_pending_onload_raw_monitors();
3795 
3796   // Create the VMThread
3797   { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3798 
3799   VMThread::create();
3800     Thread* vmthread = VMThread::vm_thread();
3801 
3802     if (!os::create_thread(vmthread, os::vm_thread)) {
3803       vm_exit_during_initialization("Cannot create VM thread. "
3804                                     "Out of system resources.");
3805     }
3806 
3807     // Wait for the VM thread to become ready, and VMThread::run to initialize
3808     // Monitors can have spurious returns, must always check another state flag
3809     {
3810       MutexLocker ml(Notify_lock);
3811       os::start_thread(vmthread);
3812       while (vmthread->active_handles() == NULL) {
3813         Notify_lock->wait();
3814       }
3815     }
3816   }
3817 
3818   assert(Universe::is_fully_initialized(), "not initialized");
3819   if (VerifyDuringStartup) {
3820     // Make sure we're starting with a clean slate.
3821     VM_Verify verify_op;
3822     VMThread::execute(&verify_op);
3823   }
3824 
3825   Thread* THREAD = Thread::current();
3826 
3827   // Always call even when there are not JVMTI environments yet, since environments
3828   // may be attached late and JVMTI must track phases of VM execution
3829   JvmtiExport::enter_early_start_phase();
3830 
3831   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3832   JvmtiExport::post_early_vm_start();
3833 
3834   initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3835 
3836   // We need this for ClassDataSharing - the initial vm.info property is set
3837   // with the default value of CDS "sharing" which may be reset through
3838   // command line options.
3839   reset_vm_info_property(CHECK_JNI_ERR);
3840 
3841   quicken_jni_functions();
3842 
3843   // No more stub generation allowed after that point.
3844   StubCodeDesc::freeze();
3845 
3846   // Set flag that basic initialization has completed. Used by exceptions and various
3847   // debug stuff, that does not work until all basic classes have been initialized.
3848   set_init_completed();
3849 
3850   LogConfiguration::post_initialize();
3851   Metaspace::post_initialize();
3852 
3853   HOTSPOT_VM_INIT_END();
3854 
3855   // record VM initialization completion time
3856 #if INCLUDE_MANAGEMENT
3857   Management::record_vm_init_completed();
3858 #endif // INCLUDE_MANAGEMENT
3859 
3860   // Signal Dispatcher needs to be started before VMInit event is posted
3861   os::signal_init(CHECK_JNI_ERR);
3862 
3863   // Start Attach Listener if +StartAttachListener or it can't be started lazily
3864   if (!DisableAttachMechanism) {
3865     AttachListener::vm_start();
3866     if (StartAttachListener || AttachListener::init_at_startup()) {
3867       AttachListener::init();
3868     }
3869   }
3870 
3871   // Launch -Xrun agents
3872   // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3873   // back-end can launch with -Xdebug -Xrunjdwp.
3874   if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3875     create_vm_init_libraries();
3876   }
3877 
3878   if (CleanChunkPoolAsync) {
3879     Chunk::start_chunk_pool_cleaner_task();
3880   }
3881 
3882   // initialize compiler(s)
3883 #if defined(COMPILER1) || COMPILER2_OR_JVMCI
3884 #if INCLUDE_JVMCI
3885   bool force_JVMCI_intialization = false;
3886   if (EnableJVMCI) {
3887     // Initialize JVMCI eagerly when it is explicitly requested.
3888     // Or when JVMCIPrintProperties is enabled.
3889     // The JVMCI Java initialization code will read this flag and
3890     // do the printing if it's set.
3891     force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties;
3892 
3893     if (!force_JVMCI_intialization) {
3894       // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3895       // compilations via JVMCI will not actually block until JVMCI is initialized.
3896       force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3897     }
3898   }
3899 #endif
3900   CompileBroker::compilation_init_phase1(CHECK_JNI_ERR);
3901   // Postpone completion of compiler initialization to after JVMCI
3902   // is initialized to avoid timeouts of blocking compilations.
3903   if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) {
3904     CompileBroker::compilation_init_phase2();
3905   }
3906 #endif
3907 
3908   // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3909   // It is done after compilers are initialized, because otherwise compilations of
3910   // signature polymorphic MH intrinsics can be missed
3911   // (see SystemDictionary::find_method_handle_intrinsic).
3912   initialize_jsr292_core_classes(CHECK_JNI_ERR);
3913 
3914   // This will initialize the module system.  Only java.base classes can be
3915   // loaded until phase 2 completes
3916   call_initPhase2(CHECK_JNI_ERR);
3917 
3918   // Always call even when there are not JVMTI environments yet, since environments
3919   // may be attached late and JVMTI must track phases of VM execution
3920   JvmtiExport::enter_start_phase();
3921 
3922   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3923   JvmtiExport::post_vm_start();
3924 
3925   // Final system initialization including security manager and system class loader
3926   call_initPhase3(CHECK_JNI_ERR);
3927 
3928   // cache the system and platform class loaders
3929   SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
3930 
3931 #if INCLUDE_CDS
3932   if (DumpSharedSpaces) {
3933     // capture the module path info from the ModuleEntryTable
3934     ClassLoader::initialize_module_path(THREAD);
3935   }
3936 #endif
3937 
3938 #if INCLUDE_JVMCI
3939   if (force_JVMCI_intialization) {
3940     JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
3941     CompileBroker::compilation_init_phase2();
3942   }
3943 #endif
3944 
3945   // Always call even when there are not JVMTI environments yet, since environments
3946   // may be attached late and JVMTI must track phases of VM execution
3947   JvmtiExport::enter_live_phase();
3948 
3949   // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3950   JvmtiExport::post_vm_initialized();
3951 
3952   if (TRACE_START() != JNI_OK) {
3953     vm_exit_during_initialization("Failed to start tracing backend.");
3954   }
3955 
3956 #if INCLUDE_MANAGEMENT
3957   Management::initialize(THREAD);
3958 
3959   if (HAS_PENDING_EXCEPTION) {
3960     // management agent fails to start possibly due to
3961     // configuration problem and is responsible for printing
3962     // stack trace if appropriate. Simply exit VM.
3963     vm_exit(1);
3964   }
3965 #endif // INCLUDE_MANAGEMENT
3966 
3967   if (MemProfiling)                   MemProfiler::engage();
3968   StatSampler::engage();
3969   if (CheckJNICalls)                  JniPeriodicChecker::engage();
3970 
3971   BiasedLocking::init();
3972 
3973 #if INCLUDE_RTM_OPT
3974   RTMLockingCounters::init();
3975 #endif
3976 
3977   if (JDK_Version::current().post_vm_init_hook_enabled()) {
3978     call_postVMInitHook(THREAD);
3979     // The Java side of PostVMInitHook.run must deal with all
3980     // exceptions and provide means of diagnosis.
3981     if (HAS_PENDING_EXCEPTION) {
3982       CLEAR_PENDING_EXCEPTION;
3983     }
3984   }
3985 
3986   {
3987     MutexLocker ml(PeriodicTask_lock);
3988     // Make sure the WatcherThread can be started by WatcherThread::start()
3989     // or by dynamic enrollment.
3990     WatcherThread::make_startable();
3991     // Start up the WatcherThread if there are any periodic tasks
3992     // NOTE:  All PeriodicTasks should be registered by now. If they
3993     //   aren't, late joiners might appear to start slowly (we might
3994     //   take a while to process their first tick).
3995     if (PeriodicTask::num_tasks() > 0) {
3996       WatcherThread::start();
3997     }
3998   }
3999 
4000   create_vm_timer.end();
4001 #ifdef ASSERT
4002   _vm_complete = true;
4003 #endif
4004 
4005   if (DumpSharedSpaces) {
4006     MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
4007     ShouldNotReachHere();
4008   }
4009 
4010   return JNI_OK;
4011 }
4012 
4013 // type for the Agent_OnLoad and JVM_OnLoad entry points
4014 extern "C" {
4015   typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
4016 }
4017 // Find a command line agent library and return its entry point for
4018 //         -agentlib:  -agentpath:   -Xrun
4019 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
4020 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
4021                                     const char *on_load_symbols[],
4022                                     size_t num_symbol_entries) {
4023   OnLoadEntry_t on_load_entry = NULL;
4024   void *library = NULL;
4025 
4026   if (!agent->valid()) {
4027     char buffer[JVM_MAXPATHLEN];
4028     char ebuf[1024] = "";
4029     const char *name = agent->name();
4030     const char *msg = "Could not find agent library ";
4031 
4032     // First check to see if agent is statically linked into executable
4033     if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
4034       library = agent->os_lib();
4035     } else if (agent->is_absolute_path()) {
4036       library = os::dll_load(name, ebuf, sizeof ebuf);
4037       if (library == NULL) {
4038         const char *sub_msg = " in absolute path, with error: ";
4039         size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
4040         char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4041         jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4042         // If we can't find the agent, exit.
4043         vm_exit_during_initialization(buf, NULL);
4044         FREE_C_HEAP_ARRAY(char, buf);
4045       }
4046     } else {
4047       // Try to load the agent from the standard dll directory
4048       if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
4049                              name)) {
4050         library = os::dll_load(buffer, ebuf, sizeof ebuf);
4051       }
4052       if (library == NULL) { // Try the library path directory.
4053         if (os::dll_build_name(buffer, sizeof(buffer), name)) {
4054           library = os::dll_load(buffer, ebuf, sizeof ebuf);
4055         }
4056         if (library == NULL) {
4057           const char *sub_msg = " on the library path, with error: ";
4058           const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image.";
4059 
4060           size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) +
4061                        strlen(ebuf) + strlen(sub_msg2) + 1;
4062           char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4063           if (!agent->is_instrument_lib()) {
4064             jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4065           } else {
4066             jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2);
4067           }
4068           // If we can't find the agent, exit.
4069           vm_exit_during_initialization(buf, NULL);
4070           FREE_C_HEAP_ARRAY(char, buf);
4071         }
4072       }
4073     }
4074     agent->set_os_lib(library);
4075     agent->set_valid();
4076   }
4077 
4078   // Find the OnLoad function.
4079   on_load_entry =
4080     CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
4081                                                           false,
4082                                                           on_load_symbols,
4083                                                           num_symbol_entries));
4084   return on_load_entry;
4085 }
4086 
4087 // Find the JVM_OnLoad entry point
4088 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
4089   const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
4090   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4091 }
4092 
4093 // Find the Agent_OnLoad entry point
4094 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
4095   const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
4096   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4097 }
4098 
4099 // For backwards compatibility with -Xrun
4100 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
4101 // treated like -agentpath:
4102 // Must be called before agent libraries are created
4103 void Threads::convert_vm_init_libraries_to_agents() {
4104   AgentLibrary* agent;
4105   AgentLibrary* next;
4106 
4107   for (agent = Arguments::libraries(); agent != NULL; agent = next) {
4108     next = agent->next();  // cache the next agent now as this agent may get moved off this list
4109     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4110 
4111     // If there is an JVM_OnLoad function it will get called later,
4112     // otherwise see if there is an Agent_OnLoad
4113     if (on_load_entry == NULL) {
4114       on_load_entry = lookup_agent_on_load(agent);
4115       if (on_load_entry != NULL) {
4116         // switch it to the agent list -- so that Agent_OnLoad will be called,
4117         // JVM_OnLoad won't be attempted and Agent_OnUnload will
4118         Arguments::convert_library_to_agent(agent);
4119       } else {
4120         vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
4121       }
4122     }
4123   }
4124 }
4125 
4126 // Create agents for -agentlib:  -agentpath:  and converted -Xrun
4127 // Invokes Agent_OnLoad
4128 // Called very early -- before JavaThreads exist
4129 void Threads::create_vm_init_agents() {
4130   extern struct JavaVM_ main_vm;
4131   AgentLibrary* agent;
4132 
4133   JvmtiExport::enter_onload_phase();
4134 
4135   for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4136     OnLoadEntry_t  on_load_entry = lookup_agent_on_load(agent);
4137 
4138     if (on_load_entry != NULL) {
4139       // Invoke the Agent_OnLoad function
4140       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4141       if (err != JNI_OK) {
4142         vm_exit_during_initialization("agent library failed to init", agent->name());
4143       }
4144     } else {
4145       vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4146     }
4147   }
4148   JvmtiExport::enter_primordial_phase();
4149 }
4150 
4151 extern "C" {
4152   typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4153 }
4154 
4155 void Threads::shutdown_vm_agents() {
4156   // Send any Agent_OnUnload notifications
4157   const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4158   size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4159   extern struct JavaVM_ main_vm;
4160   for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4161 
4162     // Find the Agent_OnUnload function.
4163     Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4164                                                    os::find_agent_function(agent,
4165                                                    false,
4166                                                    on_unload_symbols,
4167                                                    num_symbol_entries));
4168 
4169     // Invoke the Agent_OnUnload function
4170     if (unload_entry != NULL) {
4171       JavaThread* thread = JavaThread::current();
4172       ThreadToNativeFromVM ttn(thread);
4173       HandleMark hm(thread);
4174       (*unload_entry)(&main_vm);
4175     }
4176   }
4177 }
4178 
4179 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4180 // Invokes JVM_OnLoad
4181 void Threads::create_vm_init_libraries() {
4182   extern struct JavaVM_ main_vm;
4183   AgentLibrary* agent;
4184 
4185   for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4186     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4187 
4188     if (on_load_entry != NULL) {
4189       // Invoke the JVM_OnLoad function
4190       JavaThread* thread = JavaThread::current();
4191       ThreadToNativeFromVM ttn(thread);
4192       HandleMark hm(thread);
4193       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4194       if (err != JNI_OK) {
4195         vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4196       }
4197     } else {
4198       vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4199     }
4200   }
4201 }
4202 
4203 
4204 // Last thread running calls java.lang.Shutdown.shutdown()
4205 void JavaThread::invoke_shutdown_hooks() {
4206   HandleMark hm(this);
4207 
4208   // We could get here with a pending exception, if so clear it now.
4209   if (this->has_pending_exception()) {
4210     this->clear_pending_exception();
4211   }
4212 
4213   EXCEPTION_MARK;
4214   Klass* shutdown_klass =
4215     SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4216                                       THREAD);
4217   if (shutdown_klass != NULL) {
4218     // SystemDictionary::resolve_or_null will return null if there was
4219     // an exception.  If we cannot load the Shutdown class, just don't
4220     // call Shutdown.shutdown() at all.  This will mean the shutdown hooks
4221     // won't be run.  Note that if a shutdown hook was registered,
4222     // the Shutdown class would have already been loaded
4223     // (Runtime.addShutdownHook will load it).
4224     JavaValue result(T_VOID);
4225     JavaCalls::call_static(&result,
4226                            shutdown_klass,
4227                            vmSymbols::shutdown_method_name(),
4228                            vmSymbols::void_method_signature(),
4229                            THREAD);
4230   }
4231   CLEAR_PENDING_EXCEPTION;
4232 }
4233 
4234 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4235 // the program falls off the end of main(). Another VM exit path is through
4236 // vm_exit() when the program calls System.exit() to return a value or when
4237 // there is a serious error in VM. The two shutdown paths are not exactly
4238 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4239 // and VM_Exit op at VM level.
4240 //
4241 // Shutdown sequence:
4242 //   + Shutdown native memory tracking if it is on
4243 //   + Wait until we are the last non-daemon thread to execute
4244 //     <-- every thing is still working at this moment -->
4245 //   + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4246 //        shutdown hooks
4247 //   + Call before_exit(), prepare for VM exit
4248 //      > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4249 //        currently the only user of this mechanism is File.deleteOnExit())
4250 //      > stop StatSampler, watcher thread, CMS threads,
4251 //        post thread end and vm death events to JVMTI,
4252 //        stop signal thread
4253 //   + Call JavaThread::exit(), it will:
4254 //      > release JNI handle blocks, remove stack guard pages
4255 //      > remove this thread from Threads list
4256 //     <-- no more Java code from this thread after this point -->
4257 //   + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4258 //     the compiler threads at safepoint
4259 //     <-- do not use anything that could get blocked by Safepoint -->
4260 //   + Disable tracing at JNI/JVM barriers
4261 //   + Set _vm_exited flag for threads that are still running native code
4262 //   + Delete this thread
4263 //   + Call exit_globals()
4264 //      > deletes tty
4265 //      > deletes PerfMemory resources
4266 //   + Return to caller
4267 
4268 bool Threads::destroy_vm() {
4269   JavaThread* thread = JavaThread::current();
4270 
4271 #ifdef ASSERT
4272   _vm_complete = false;
4273 #endif
4274   // Wait until we are the last non-daemon thread to execute
4275   { MutexLocker nu(Threads_lock);
4276     while (Threads::number_of_non_daemon_threads() > 1)
4277       // This wait should make safepoint checks, wait without a timeout,
4278       // and wait as a suspend-equivalent condition.
4279       Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4280                          Mutex::_as_suspend_equivalent_flag);
4281   }
4282 
4283   EventShutdown e;
4284   if (e.should_commit()) {
4285     e.set_reason("No remaining non-daemon Java threads");
4286     e.commit();
4287   }
4288 
4289   // Hang forever on exit if we are reporting an error.
4290   if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4291     os::infinite_sleep();
4292   }
4293   os::wait_for_keypress_at_exit();
4294 
4295   // run Java level shutdown hooks
4296   thread->invoke_shutdown_hooks();
4297 
4298   before_exit(thread);
4299 
4300   thread->exit(true);
4301 
4302   // Stop VM thread.
4303   {
4304     // 4945125 The vm thread comes to a safepoint during exit.
4305     // GC vm_operations can get caught at the safepoint, and the
4306     // heap is unparseable if they are caught. Grab the Heap_lock
4307     // to prevent this. The GC vm_operations will not be able to
4308     // queue until after the vm thread is dead. After this point,
4309     // we'll never emerge out of the safepoint before the VM exits.
4310 
4311     MutexLocker ml(Heap_lock);
4312 
4313     VMThread::wait_for_vm_thread_exit();
4314     assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4315     VMThread::destroy();
4316   }
4317 
4318   // Now, all Java threads are gone except daemon threads. Daemon threads
4319   // running Java code or in VM are stopped by the Safepoint. However,
4320   // daemon threads executing native code are still running.  But they
4321   // will be stopped at native=>Java/VM barriers. Note that we can't
4322   // simply kill or suspend them, as it is inherently deadlock-prone.
4323 
4324   VM_Exit::set_vm_exited();
4325 
4326   // Clean up ideal graph printers after the VMThread has started
4327   // the final safepoint which will block all the Compiler threads.
4328   // Note that this Thread has already logically exited so the
4329   // clean_up() function's use of a JavaThreadIteratorWithHandle
4330   // would be a problem except set_vm_exited() has remembered the
4331   // shutdown thread which is granted a policy exception.
4332 #if defined(COMPILER2) && !defined(PRODUCT)
4333   IdealGraphPrinter::clean_up();
4334 #endif
4335 
4336   notify_vm_shutdown();
4337 
4338   // We are after VM_Exit::set_vm_exited() so we can't call
4339   // thread->smr_delete() or we will block on the Threads_lock.
4340   // Deleting the shutdown thread here is safe because another
4341   // JavaThread cannot have an active ThreadsListHandle for
4342   // this JavaThread.
4343   delete thread;
4344 
4345 #if INCLUDE_JVMCI
4346   if (JVMCICounterSize > 0) {
4347     FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4348   }
4349 #endif
4350 
4351   // exit_globals() will delete tty
4352   exit_globals();
4353 
4354   LogConfiguration::finalize();
4355 
4356   return true;
4357 }
4358 
4359 
4360 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4361   if (version == JNI_VERSION_1_1) return JNI_TRUE;
4362   return is_supported_jni_version(version);
4363 }
4364 
4365 
4366 jboolean Threads::is_supported_jni_version(jint version) {
4367   if (version == JNI_VERSION_1_2) return JNI_TRUE;
4368   if (version == JNI_VERSION_1_4) return JNI_TRUE;
4369   if (version == JNI_VERSION_1_6) return JNI_TRUE;
4370   if (version == JNI_VERSION_1_8) return JNI_TRUE;
4371   if (version == JNI_VERSION_9) return JNI_TRUE;
4372   if (version == JNI_VERSION_10) return JNI_TRUE;
4373   return JNI_FALSE;
4374 }
4375 
4376 
4377 void Threads::add(JavaThread* p, bool force_daemon) {
4378   // The threads lock must be owned at this point
4379   assert_locked_or_safepoint(Threads_lock);
4380 
4381   BarrierSet::barrier_set()->on_thread_attach(p);
4382 
4383   p->set_next(_thread_list);
4384   _thread_list = p;
4385 
4386   // Once a JavaThread is added to the Threads list, smr_delete() has
4387   // to be used to delete it. Otherwise we can just delete it directly.
4388   p->set_on_thread_list();
4389 
4390   _number_of_threads++;
4391   oop threadObj = p->threadObj();
4392   bool daemon = true;
4393   // Bootstrapping problem: threadObj can be null for initial
4394   // JavaThread (or for threads attached via JNI)
4395   if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4396     _number_of_non_daemon_threads++;
4397     daemon = false;
4398   }
4399 
4400   ThreadService::add_thread(p, daemon);
4401 
4402   // Maintain fast thread list
4403   ThreadsSMRSupport::add_thread(p);
4404 
4405   // Possible GC point.
4406   Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4407 }
4408 
4409 void Threads::remove(JavaThread* p) {
4410 
4411   // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread.
4412   ObjectSynchronizer::omFlush(p);
4413 
4414   // Extra scope needed for Thread_lock, so we can check
4415   // that we do not remove thread without safepoint code notice
4416   { MutexLocker ml(Threads_lock);
4417 
4418     assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present");
4419 
4420     // Maintain fast thread list
4421     ThreadsSMRSupport::remove_thread(p);
4422 
4423     JavaThread* current = _thread_list;
4424     JavaThread* prev    = NULL;
4425 
4426     while (current != p) {
4427       prev    = current;
4428       current = current->next();
4429     }
4430 
4431     if (prev) {
4432       prev->set_next(current->next());
4433     } else {
4434       _thread_list = p->next();
4435     }
4436 
4437     _number_of_threads--;
4438     oop threadObj = p->threadObj();
4439     bool daemon = true;
4440     if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4441       _number_of_non_daemon_threads--;
4442       daemon = false;
4443 
4444       // Only one thread left, do a notify on the Threads_lock so a thread waiting
4445       // on destroy_vm will wake up.
4446       if (number_of_non_daemon_threads() == 1) {
4447         Threads_lock->notify_all();
4448       }
4449     }
4450     ThreadService::remove_thread(p, daemon);
4451 
4452     // Make sure that safepoint code disregard this thread. This is needed since
4453     // the thread might mess around with locks after this point. This can cause it
4454     // to do callbacks into the safepoint code. However, the safepoint code is not aware
4455     // of this thread since it is removed from the queue.
4456     p->set_terminated_value();
4457   } // unlock Threads_lock
4458 
4459   // Since Events::log uses a lock, we grab it outside the Threads_lock
4460   Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4461 }
4462 
4463 // Operations on the Threads list for GC.  These are not explicitly locked,
4464 // but the garbage collector must provide a safe context for them to run.
4465 // In particular, these things should never be called when the Threads_lock
4466 // is held by some other thread. (Note: the Safepoint abstraction also
4467 // uses the Threads_lock to guarantee this property. It also makes sure that
4468 // all threads gets blocked when exiting or starting).
4469 
4470 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4471   ALL_JAVA_THREADS(p) {
4472     p->oops_do(f, cf);
4473   }
4474   VMThread::vm_thread()->oops_do(f, cf);
4475 }
4476 
4477 void Threads::change_thread_claim_parity() {
4478   // Set the new claim parity.
4479   assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4480          "Not in range.");
4481   _thread_claim_parity++;
4482   if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4483   assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4484          "Not in range.");
4485 }
4486 
4487 #ifdef ASSERT
4488 void Threads::assert_all_threads_claimed() {
4489   ALL_JAVA_THREADS(p) {
4490     const int thread_parity = p->oops_do_parity();
4491     assert((thread_parity == _thread_claim_parity),
4492            "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4493   }
4494   VMThread* vmt = VMThread::vm_thread();
4495   const int thread_parity = vmt->oops_do_parity();
4496   assert((thread_parity == _thread_claim_parity),
4497          "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity);
4498 }
4499 #endif // ASSERT
4500 
4501 class ParallelOopsDoThreadClosure : public ThreadClosure {
4502 private:
4503   OopClosure* _f;
4504   CodeBlobClosure* _cf;
4505 public:
4506   ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {}
4507   void do_thread(Thread* t) {
4508     t->oops_do(_f, _cf);
4509   }
4510 };
4511 
4512 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4513   ParallelOopsDoThreadClosure tc(f, cf);
4514   possibly_parallel_threads_do(is_par, &tc);
4515 }
4516 
4517 #if INCLUDE_ALL_GCS
4518 // Used by ParallelScavenge
4519 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4520   ALL_JAVA_THREADS(p) {
4521     q->enqueue(new ThreadRootsTask(p));
4522   }
4523   q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4524 }
4525 
4526 // Used by Parallel Old
4527 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4528   ALL_JAVA_THREADS(p) {
4529     q->enqueue(new ThreadRootsMarkingTask(p));
4530   }
4531   q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4532 }
4533 #endif // INCLUDE_ALL_GCS
4534 
4535 void Threads::nmethods_do(CodeBlobClosure* cf) {
4536   ALL_JAVA_THREADS(p) {
4537     // This is used by the code cache sweeper to mark nmethods that are active
4538     // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4539     // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4540     if(!p->is_Code_cache_sweeper_thread()) {
4541       p->nmethods_do(cf);
4542     }
4543   }
4544 }
4545 
4546 void Threads::metadata_do(void f(Metadata*)) {
4547   ALL_JAVA_THREADS(p) {
4548     p->metadata_do(f);
4549   }
4550 }
4551 
4552 class ThreadHandlesClosure : public ThreadClosure {
4553   void (*_f)(Metadata*);
4554  public:
4555   ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4556   virtual void do_thread(Thread* thread) {
4557     thread->metadata_handles_do(_f);
4558   }
4559 };
4560 
4561 void Threads::metadata_handles_do(void f(Metadata*)) {
4562   // Only walk the Handles in Thread.
4563   ThreadHandlesClosure handles_closure(f);
4564   threads_do(&handles_closure);
4565 }
4566 
4567 void Threads::deoptimized_wrt_marked_nmethods() {
4568   ALL_JAVA_THREADS(p) {
4569     p->deoptimized_wrt_marked_nmethods();
4570   }
4571 }
4572 
4573 
4574 // Get count Java threads that are waiting to enter the specified monitor.
4575 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
4576                                                          int count,
4577                                                          address monitor) {
4578   GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4579 
4580   int i = 0;
4581   DO_JAVA_THREADS(t_list, p) {
4582     if (!p->can_call_java()) continue;
4583 
4584     address pending = (address)p->current_pending_monitor();
4585     if (pending == monitor) {             // found a match
4586       if (i < count) result->append(p);   // save the first count matches
4587       i++;
4588     }
4589   }
4590 
4591   return result;
4592 }
4593 
4594 
4595 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
4596                                                       address owner) {
4597   // NULL owner means not locked so we can skip the search
4598   if (owner == NULL) return NULL;
4599 
4600   DO_JAVA_THREADS(t_list, p) {
4601     // first, see if owner is the address of a Java thread
4602     if (owner == (address)p) return p;
4603   }
4604 
4605   // Cannot assert on lack of success here since this function may be
4606   // used by code that is trying to report useful problem information
4607   // like deadlock detection.
4608   if (UseHeavyMonitors) return NULL;
4609 
4610   // If we didn't find a matching Java thread and we didn't force use of
4611   // heavyweight monitors, then the owner is the stack address of the
4612   // Lock Word in the owning Java thread's stack.
4613   //
4614   JavaThread* the_owner = NULL;
4615   DO_JAVA_THREADS(t_list, q) {
4616     if (q->is_lock_owned(owner)) {
4617       the_owner = q;
4618       break;
4619     }
4620   }
4621 
4622   // cannot assert on lack of success here; see above comment
4623   return the_owner;
4624 }
4625 
4626 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4627 void Threads::print_on(outputStream* st, bool print_stacks,
4628                        bool internal_format, bool print_concurrent_locks) {
4629   char buf[32];
4630   st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4631 
4632   st->print_cr("Full thread dump %s (%s %s):",
4633                Abstract_VM_Version::vm_name(),
4634                Abstract_VM_Version::vm_release(),
4635                Abstract_VM_Version::vm_info_string());
4636   st->cr();
4637 
4638 #if INCLUDE_SERVICES
4639   // Dump concurrent locks
4640   ConcurrentLocksDump concurrent_locks;
4641   if (print_concurrent_locks) {
4642     concurrent_locks.dump_at_safepoint();
4643   }
4644 #endif // INCLUDE_SERVICES
4645 
4646   ThreadsSMRSupport::print_info_on(st);
4647   st->cr();
4648 
4649   ALL_JAVA_THREADS(p) {
4650     ResourceMark rm;
4651     p->print_on(st);
4652     if (print_stacks) {
4653       if (internal_format) {
4654         p->trace_stack();
4655       } else {
4656         p->print_stack_on(st);
4657       }
4658     }
4659     st->cr();
4660 #if INCLUDE_SERVICES
4661     if (print_concurrent_locks) {
4662       concurrent_locks.print_locks_on(p, st);
4663     }
4664 #endif // INCLUDE_SERVICES
4665   }
4666 
4667   VMThread::vm_thread()->print_on(st);
4668   st->cr();
4669   Universe::heap()->print_gc_threads_on(st);
4670   WatcherThread* wt = WatcherThread::watcher_thread();
4671   if (wt != NULL) {
4672     wt->print_on(st);
4673     st->cr();
4674   }
4675 
4676   st->flush();
4677 }
4678 
4679 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4680                              int buflen, bool* found_current) {
4681   if (this_thread != NULL) {
4682     bool is_current = (current == this_thread);
4683     *found_current = *found_current || is_current;
4684     st->print("%s", is_current ? "=>" : "  ");
4685 
4686     st->print(PTR_FORMAT, p2i(this_thread));
4687     st->print(" ");
4688     this_thread->print_on_error(st, buf, buflen);
4689     st->cr();
4690   }
4691 }
4692 
4693 class PrintOnErrorClosure : public ThreadClosure {
4694   outputStream* _st;
4695   Thread* _current;
4696   char* _buf;
4697   int _buflen;
4698   bool* _found_current;
4699  public:
4700   PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4701                       int buflen, bool* found_current) :
4702    _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4703 
4704   virtual void do_thread(Thread* thread) {
4705     Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4706   }
4707 };
4708 
4709 // Threads::print_on_error() is called by fatal error handler. It's possible
4710 // that VM is not at safepoint and/or current thread is inside signal handler.
4711 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4712 // memory (even in resource area), it might deadlock the error handler.
4713 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4714                              int buflen) {
4715   ThreadsSMRSupport::print_info_on(st);
4716   st->cr();
4717 
4718   bool found_current = false;
4719   st->print_cr("Java Threads: ( => current thread )");
4720   ALL_JAVA_THREADS(thread) {
4721     print_on_error(thread, st, current, buf, buflen, &found_current);
4722   }
4723   st->cr();
4724 
4725   st->print_cr("Other Threads:");
4726   print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4727   print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4728 
4729   PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4730   Universe::heap()->gc_threads_do(&print_closure);
4731 
4732   if (!found_current) {
4733     st->cr();
4734     st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4735     current->print_on_error(st, buf, buflen);
4736     st->cr();
4737   }
4738   st->cr();
4739 
4740   st->print_cr("Threads with active compile tasks:");
4741   print_threads_compiling(st, buf, buflen);
4742 }
4743 
4744 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4745   ALL_JAVA_THREADS(thread) {
4746     if (thread->is_Compiler_thread()) {
4747       CompilerThread* ct = (CompilerThread*) thread;
4748 
4749       // Keep task in local variable for NULL check.
4750       // ct->_task might be set to NULL by concurring compiler thread
4751       // because it completed the compilation. The task is never freed,
4752       // though, just returned to a free list.
4753       CompileTask* task = ct->task();
4754       if (task != NULL) {
4755         thread->print_name_on_error(st, buf, buflen);
4756         task->print(st, NULL, true, true);
4757       }
4758     }
4759   }
4760 }
4761 
4762 
4763 // Internal SpinLock and Mutex
4764 // Based on ParkEvent
4765 
4766 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4767 //
4768 // We employ SpinLocks _only for low-contention, fixed-length
4769 // short-duration critical sections where we're concerned
4770 // about native mutex_t or HotSpot Mutex:: latency.
4771 // The mux construct provides a spin-then-block mutual exclusion
4772 // mechanism.
4773 //
4774 // Testing has shown that contention on the ListLock guarding gFreeList
4775 // is common.  If we implement ListLock as a simple SpinLock it's common
4776 // for the JVM to devolve to yielding with little progress.  This is true
4777 // despite the fact that the critical sections protected by ListLock are
4778 // extremely short.
4779 //
4780 // TODO-FIXME: ListLock should be of type SpinLock.
4781 // We should make this a 1st-class type, integrated into the lock
4782 // hierarchy as leaf-locks.  Critically, the SpinLock structure
4783 // should have sufficient padding to avoid false-sharing and excessive
4784 // cache-coherency traffic.
4785 
4786 
4787 typedef volatile int SpinLockT;
4788 
4789 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4790   if (Atomic::cmpxchg (1, adr, 0) == 0) {
4791     return;   // normal fast-path return
4792   }
4793 
4794   // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4795   TEVENT(SpinAcquire - ctx);
4796   int ctr = 0;
4797   int Yields = 0;
4798   for (;;) {
4799     while (*adr != 0) {
4800       ++ctr;
4801       if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4802         if (Yields > 5) {
4803           os::naked_short_sleep(1);
4804         } else {
4805           os::naked_yield();
4806           ++Yields;
4807         }
4808       } else {
4809         SpinPause();
4810       }
4811     }
4812     if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4813   }
4814 }
4815 
4816 void Thread::SpinRelease(volatile int * adr) {
4817   assert(*adr != 0, "invariant");
4818   OrderAccess::fence();      // guarantee at least release consistency.
4819   // Roach-motel semantics.
4820   // It's safe if subsequent LDs and STs float "up" into the critical section,
4821   // but prior LDs and STs within the critical section can't be allowed
4822   // to reorder or float past the ST that releases the lock.
4823   // Loads and stores in the critical section - which appear in program
4824   // order before the store that releases the lock - must also appear
4825   // before the store that releases the lock in memory visibility order.
4826   // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4827   // the ST of 0 into the lock-word which releases the lock, so fence
4828   // more than covers this on all platforms.
4829   *adr = 0;
4830 }
4831 
4832 // muxAcquire and muxRelease:
4833 //
4834 // *  muxAcquire and muxRelease support a single-word lock-word construct.
4835 //    The LSB of the word is set IFF the lock is held.
4836 //    The remainder of the word points to the head of a singly-linked list
4837 //    of threads blocked on the lock.
4838 //
4839 // *  The current implementation of muxAcquire-muxRelease uses its own
4840 //    dedicated Thread._MuxEvent instance.  If we're interested in
4841 //    minimizing the peak number of extant ParkEvent instances then
4842 //    we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4843 //    as certain invariants were satisfied.  Specifically, care would need
4844 //    to be taken with regards to consuming unpark() "permits".
4845 //    A safe rule of thumb is that a thread would never call muxAcquire()
4846 //    if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4847 //    park().  Otherwise the _ParkEvent park() operation in muxAcquire() could
4848 //    consume an unpark() permit intended for monitorenter, for instance.
4849 //    One way around this would be to widen the restricted-range semaphore
4850 //    implemented in park().  Another alternative would be to provide
4851 //    multiple instances of the PlatformEvent() for each thread.  One
4852 //    instance would be dedicated to muxAcquire-muxRelease, for instance.
4853 //
4854 // *  Usage:
4855 //    -- Only as leaf locks
4856 //    -- for short-term locking only as muxAcquire does not perform
4857 //       thread state transitions.
4858 //
4859 // Alternatives:
4860 // *  We could implement muxAcquire and muxRelease with MCS or CLH locks
4861 //    but with parking or spin-then-park instead of pure spinning.
4862 // *  Use Taura-Oyama-Yonenzawa locks.
4863 // *  It's possible to construct a 1-0 lock if we encode the lockword as
4864 //    (List,LockByte).  Acquire will CAS the full lockword while Release
4865 //    will STB 0 into the LockByte.  The 1-0 scheme admits stranding, so
4866 //    acquiring threads use timers (ParkTimed) to detect and recover from
4867 //    the stranding window.  Thread/Node structures must be aligned on 256-byte
4868 //    boundaries by using placement-new.
4869 // *  Augment MCS with advisory back-link fields maintained with CAS().
4870 //    Pictorially:  LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4871 //    The validity of the backlinks must be ratified before we trust the value.
4872 //    If the backlinks are invalid the exiting thread must back-track through the
4873 //    the forward links, which are always trustworthy.
4874 // *  Add a successor indication.  The LockWord is currently encoded as
4875 //    (List, LOCKBIT:1).  We could also add a SUCCBIT or an explicit _succ variable
4876 //    to provide the usual futile-wakeup optimization.
4877 //    See RTStt for details.
4878 // *  Consider schedctl.sc_nopreempt to cover the critical section.
4879 //
4880 
4881 
4882 const intptr_t LOCKBIT = 1;
4883 
4884 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4885   intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4886   if (w == 0) return;
4887   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4888     return;
4889   }
4890 
4891   TEVENT(muxAcquire - Contention);
4892   ParkEvent * const Self = Thread::current()->_MuxEvent;
4893   assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4894   for (;;) {
4895     int its = (os::is_MP() ? 100 : 0) + 1;
4896 
4897     // Optional spin phase: spin-then-park strategy
4898     while (--its >= 0) {
4899       w = *Lock;
4900       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4901         return;
4902       }
4903     }
4904 
4905     Self->reset();
4906     Self->OnList = intptr_t(Lock);
4907     // The following fence() isn't _strictly necessary as the subsequent
4908     // CAS() both serializes execution and ratifies the fetched *Lock value.
4909     OrderAccess::fence();
4910     for (;;) {
4911       w = *Lock;
4912       if ((w & LOCKBIT) == 0) {
4913         if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4914           Self->OnList = 0;   // hygiene - allows stronger asserts
4915           return;
4916         }
4917         continue;      // Interference -- *Lock changed -- Just retry
4918       }
4919       assert(w & LOCKBIT, "invariant");
4920       Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4921       if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4922     }
4923 
4924     while (Self->OnList != 0) {
4925       Self->park();
4926     }
4927   }
4928 }
4929 
4930 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4931   intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4932   if (w == 0) return;
4933   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4934     return;
4935   }
4936 
4937   TEVENT(muxAcquire - Contention);
4938   ParkEvent * ReleaseAfter = NULL;
4939   if (ev == NULL) {
4940     ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4941   }
4942   assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4943   for (;;) {
4944     guarantee(ev->OnList == 0, "invariant");
4945     int its = (os::is_MP() ? 100 : 0) + 1;
4946 
4947     // Optional spin phase: spin-then-park strategy
4948     while (--its >= 0) {
4949       w = *Lock;
4950       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4951         if (ReleaseAfter != NULL) {
4952           ParkEvent::Release(ReleaseAfter);
4953         }
4954         return;
4955       }
4956     }
4957 
4958     ev->reset();
4959     ev->OnList = intptr_t(Lock);
4960     // The following fence() isn't _strictly necessary as the subsequent
4961     // CAS() both serializes execution and ratifies the fetched *Lock value.
4962     OrderAccess::fence();
4963     for (;;) {
4964       w = *Lock;
4965       if ((w & LOCKBIT) == 0) {
4966         if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4967           ev->OnList = 0;
4968           // We call ::Release while holding the outer lock, thus
4969           // artificially lengthening the critical section.
4970           // Consider deferring the ::Release() until the subsequent unlock(),
4971           // after we've dropped the outer lock.
4972           if (ReleaseAfter != NULL) {
4973             ParkEvent::Release(ReleaseAfter);
4974           }
4975           return;
4976         }
4977         continue;      // Interference -- *Lock changed -- Just retry
4978       }
4979       assert(w & LOCKBIT, "invariant");
4980       ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4981       if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4982     }
4983 
4984     while (ev->OnList != 0) {
4985       ev->park();
4986     }
4987   }
4988 }
4989 
4990 // Release() must extract a successor from the list and then wake that thread.
4991 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4992 // similar to that used by ParkEvent::Allocate() and ::Release().  DMR-based
4993 // Release() would :
4994 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4995 // (B) Extract a successor from the private list "in-hand"
4996 // (C) attempt to CAS() the residual back into *Lock over null.
4997 //     If there were any newly arrived threads and the CAS() would fail.
4998 //     In that case Release() would detach the RATs, re-merge the list in-hand
4999 //     with the RATs and repeat as needed.  Alternately, Release() might
5000 //     detach and extract a successor, but then pass the residual list to the wakee.
5001 //     The wakee would be responsible for reattaching and remerging before it
5002 //     competed for the lock.
5003 //
5004 // Both "pop" and DMR are immune from ABA corruption -- there can be
5005 // multiple concurrent pushers, but only one popper or detacher.
5006 // This implementation pops from the head of the list.  This is unfair,
5007 // but tends to provide excellent throughput as hot threads remain hot.
5008 // (We wake recently run threads first).
5009 //
5010 // All paths through muxRelease() will execute a CAS.
5011 // Release consistency -- We depend on the CAS in muxRelease() to provide full
5012 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
5013 // executed within the critical section are complete and globally visible before the
5014 // store (CAS) to the lock-word that releases the lock becomes globally visible.
5015 void Thread::muxRelease(volatile intptr_t * Lock)  {
5016   for (;;) {
5017     const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT);
5018     assert(w & LOCKBIT, "invariant");
5019     if (w == LOCKBIT) return;
5020     ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
5021     assert(List != NULL, "invariant");
5022     assert(List->OnList == intptr_t(Lock), "invariant");
5023     ParkEvent * const nxt = List->ListNext;
5024     guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
5025 
5026     // The following CAS() releases the lock and pops the head element.
5027     // The CAS() also ratifies the previously fetched lock-word value.
5028     if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) {
5029       continue;
5030     }
5031     List->OnList = 0;
5032     OrderAccess::fence();
5033     List->unpark();
5034     return;
5035   }
5036 }
5037 
5038 
5039 void Threads::verify() {
5040   ALL_JAVA_THREADS(p) {
5041     p->verify();
5042   }
5043   VMThread* thread = VMThread::vm_thread();
5044   if (thread != NULL) thread->verify();
5045 }