rev 57156 : imported patch 8234796-v3

   1 /*
   2  * Copyright (c) 1997, 2019, 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 "aot/aotLoader.hpp"
  28 #include "classfile/classLoader.hpp"
  29 #include "classfile/javaClasses.hpp"
  30 #include "classfile/moduleEntry.hpp"
  31 #include "classfile/systemDictionary.hpp"
  32 #include "classfile/vmSymbols.hpp"
  33 #include "code/codeCache.hpp"
  34 #include "code/scopeDesc.hpp"
  35 #include "compiler/compileBroker.hpp"
  36 #include "compiler/compileTask.hpp"
  37 #include "gc/shared/barrierSet.hpp"
  38 #include "gc/shared/gcId.hpp"
  39 #include "gc/shared/gcLocker.inline.hpp"
  40 #include "gc/shared/workgroup.hpp"
  41 #include "interpreter/interpreter.hpp"
  42 #include "interpreter/linkResolver.hpp"
  43 #include "interpreter/oopMapCache.hpp"
  44 #include "jfr/jfrEvents.hpp"
  45 #include "jvmtifiles/jvmtiEnv.hpp"
  46 #include "logging/log.hpp"
  47 #include "logging/logConfiguration.hpp"
  48 #include "logging/logStream.hpp"
  49 #include "memory/allocation.inline.hpp"

  50 #include "memory/metaspaceShared.hpp"
  51 #include "memory/oopFactory.hpp"
  52 #include "memory/resourceArea.hpp"
  53 #include "memory/universe.hpp"
  54 #include "oops/access.inline.hpp"
  55 #include "oops/instanceKlass.hpp"
  56 #include "oops/objArrayOop.hpp"
  57 #include "oops/oop.inline.hpp"
  58 #include "oops/symbol.hpp"
  59 #include "oops/typeArrayOop.inline.hpp"
  60 #include "oops/verifyOopClosure.hpp"
  61 #include "prims/jvm_misc.hpp"
  62 #include "prims/jvmtiExport.hpp"
  63 #include "prims/jvmtiThreadState.hpp"
  64 #include "runtime/arguments.hpp"
  65 #include "runtime/atomic.hpp"
  66 #include "runtime/biasedLocking.hpp"
  67 #include "runtime/fieldDescriptor.inline.hpp"
  68 #include "runtime/flags/jvmFlagConstraintList.hpp"
  69 #include "runtime/flags/jvmFlagRangeList.hpp"
  70 #include "runtime/flags/jvmFlagWriteableList.hpp"
  71 #include "runtime/deoptimization.hpp"
  72 #include "runtime/frame.inline.hpp"
  73 #include "runtime/handles.inline.hpp"
  74 #include "runtime/handshake.hpp"
  75 #include "runtime/init.hpp"
  76 #include "runtime/interfaceSupport.inline.hpp"
  77 #include "runtime/java.hpp"
  78 #include "runtime/javaCalls.hpp"
  79 #include "runtime/jniHandles.inline.hpp"
  80 #include "runtime/jniPeriodicChecker.hpp"
  81 #include "runtime/memprofiler.hpp"
  82 #include "runtime/mutexLocker.hpp"
  83 #include "runtime/objectMonitor.hpp"
  84 #include "runtime/orderAccess.hpp"
  85 #include "runtime/osThread.hpp"
  86 #include "runtime/prefetch.inline.hpp"
  87 #include "runtime/safepoint.hpp"
  88 #include "runtime/safepointMechanism.inline.hpp"
  89 #include "runtime/safepointVerifiers.hpp"
  90 #include "runtime/sharedRuntime.hpp"
  91 #include "runtime/statSampler.hpp"
  92 #include "runtime/stubRoutines.hpp"
  93 #include "runtime/sweeper.hpp"
  94 #include "runtime/task.hpp"
  95 #include "runtime/thread.inline.hpp"
  96 #include "runtime/threadCritical.hpp"
  97 #include "runtime/threadSMR.inline.hpp"
  98 #include "runtime/threadStatisticalInfo.hpp"
  99 #include "runtime/timer.hpp"
 100 #include "runtime/timerTrace.hpp"
 101 #include "runtime/vframe.inline.hpp"
 102 #include "runtime/vframeArray.hpp"
 103 #include "runtime/vframe_hp.hpp"
 104 #include "runtime/vmThread.hpp"
 105 #include "runtime/vmOperations.hpp"
 106 #include "runtime/vm_version.hpp"
 107 #include "services/attachListener.hpp"
 108 #include "services/management.hpp"
 109 #include "services/memTracker.hpp"
 110 #include "services/threadService.hpp"
 111 #include "utilities/align.hpp"
 112 #include "utilities/copy.hpp"
 113 #include "utilities/defaultStream.hpp"
 114 #include "utilities/dtrace.hpp"
 115 #include "utilities/events.hpp"
 116 #include "utilities/macros.hpp"
 117 #include "utilities/preserveException.hpp"
 118 #include "utilities/singleWriterSynchronizer.hpp"
 119 #include "utilities/vmError.hpp"
 120 #if INCLUDE_JVMCI
 121 #include "jvmci/jvmci.hpp"
 122 #include "jvmci/jvmciEnv.hpp"
 123 #endif
 124 #ifdef COMPILER1
 125 #include "c1/c1_Compiler.hpp"
 126 #endif
 127 #ifdef COMPILER2
 128 #include "opto/c2compiler.hpp"
 129 #include "opto/idealGraphPrinter.hpp"
 130 #endif
 131 #if INCLUDE_RTM_OPT
 132 #include "runtime/rtmLocking.hpp"
 133 #endif
 134 #if INCLUDE_JFR
 135 #include "jfr/jfr.hpp"
 136 #endif
 137 
 138 // Initialization after module runtime initialization
 139 void universe_post_module_init();  // must happen after call_initPhase2
 140 
 141 #ifdef DTRACE_ENABLED
 142 
 143 // Only bother with this argument setup if dtrace is available
 144 
 145   #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
 146   #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
 147 
 148   #define DTRACE_THREAD_PROBE(probe, javathread)                           \
 149     {                                                                      \
 150       ResourceMark rm(this);                                               \
 151       int len = 0;                                                         \
 152       const char* name = (javathread)->get_thread_name();                  \
 153       len = strlen(name);                                                  \
 154       HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */               \
 155         (char *) name, len,                                                \
 156         java_lang_Thread::thread_id((javathread)->threadObj()),            \
 157         (uintptr_t) (javathread)->osthread()->thread_id(),                 \
 158         java_lang_Thread::is_daemon((javathread)->threadObj()));           \
 159     }
 160 
 161 #else //  ndef DTRACE_ENABLED
 162 
 163   #define DTRACE_THREAD_PROBE(probe, javathread)
 164 
 165 #endif // ndef DTRACE_ENABLED
 166 
 167 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 168 // Current thread is maintained as a thread-local variable
 169 THREAD_LOCAL Thread* Thread::_thr_current = NULL;
 170 #endif
 171 
 172 // ======= Thread ========
 173 // Support for forcing alignment of thread objects for biased locking
 174 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
 175   if (UseBiasedLocking) {
 176     const size_t alignment = markWord::biased_lock_alignment;
 177     size_t aligned_size = size + (alignment - sizeof(intptr_t));
 178     void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
 179                                           : AllocateHeap(aligned_size, flags, CURRENT_PC,
 180                                                          AllocFailStrategy::RETURN_NULL);
 181     void* aligned_addr     = align_up(real_malloc_addr, alignment);
 182     assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
 183            ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
 184            "JavaThread alignment code overflowed allocated storage");
 185     if (aligned_addr != real_malloc_addr) {
 186       log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
 187                               p2i(real_malloc_addr),
 188                               p2i(aligned_addr));
 189     }
 190     ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
 191     return aligned_addr;
 192   } else {
 193     return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
 194                        : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
 195   }
 196 }
 197 
 198 void Thread::operator delete(void* p) {
 199   if (UseBiasedLocking) {
 200     FreeHeap(((Thread*) p)->_real_malloc_address);
 201   } else {
 202     FreeHeap(p);
 203   }
 204 }
 205 
 206 void JavaThread::smr_delete() {
 207   if (_on_thread_list) {
 208     ThreadsSMRSupport::smr_delete(this);
 209   } else {
 210     delete this;
 211   }
 212 }
 213 
 214 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
 215 // JavaThread
 216 
 217 DEBUG_ONLY(Thread* Thread::_starting_thread = NULL;)
 218 
 219 Thread::Thread() {
 220 
 221   DEBUG_ONLY(_run_state = PRE_CALL_RUN;)
 222 
 223   // stack and get_thread
 224   set_stack_base(NULL);
 225   set_stack_size(0);
 226   set_lgrp_id(-1);
 227   DEBUG_ONLY(clear_suspendible_thread();)
 228 
 229   // allocated data structures
 230   set_osthread(NULL);
 231   set_resource_area(new (mtThread)ResourceArea());
 232   DEBUG_ONLY(_current_resource_mark = NULL;)
 233   set_handle_area(new (mtThread) HandleArea(NULL));
 234   set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
 235   set_active_handles(NULL);
 236   set_free_handle_block(NULL);
 237   set_last_handle_mark(NULL);
 238   DEBUG_ONLY(_missed_ic_stub_refill_verifier = NULL);
 239 
 240   // Initial value of zero ==> never claimed.
 241   _threads_do_token = 0;
 242   _threads_hazard_ptr = NULL;
 243   _threads_list_ptr = NULL;
 244   _nested_threads_hazard_ptr_cnt = 0;
 245   _rcu_counter = 0;
 246 
 247   // the handle mark links itself to last_handle_mark
 248   new HandleMark(this);
 249 
 250   // plain initialization
 251   debug_only(_owned_locks = NULL;)
 252   NOT_PRODUCT(_no_safepoint_count = 0;)
 253   NOT_PRODUCT(_skip_gcalot = false;)
 254   _jvmti_env_iteration_count = 0;
 255   set_allocated_bytes(0);
 256   _vm_operation_started_count = 0;
 257   _vm_operation_completed_count = 0;
 258   _current_pending_monitor = NULL;
 259   _current_pending_monitor_is_from_java = true;
 260   _current_waiting_monitor = NULL;
 261   _current_pending_raw_monitor = NULL;
 262   _num_nested_signal = 0;
 263   om_free_list = NULL;
 264   om_free_count = 0;
 265   om_free_provision = 32;
 266   om_in_use_list = NULL;
 267   om_in_use_count = 0;
 268 
 269 #ifdef ASSERT
 270   _visited_for_critical_count = false;
 271 #endif
 272 
 273   _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
 274                          Monitor::_safepoint_check_sometimes);
 275   _suspend_flags = 0;
 276 
 277   // thread-specific hashCode stream generator state - Marsaglia shift-xor form
 278   _hashStateX = os::random();
 279   _hashStateY = 842502087;
 280   _hashStateZ = 0x8767;    // (int)(3579807591LL & 0xffff) ;
 281   _hashStateW = 273326509;
 282 
 283   _OnTrap   = 0;
 284   _Stalled  = 0;
 285   _TypeTag  = 0x2BAD;
 286 
 287   // Many of the following fields are effectively final - immutable
 288   // Note that nascent threads can't use the Native Monitor-Mutex
 289   // construct until the _MutexEvent is initialized ...
 290   // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
 291   // we might instead use a stack of ParkEvents that we could provision on-demand.
 292   // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
 293   // and ::Release()
 294   _ParkEvent   = ParkEvent::Allocate(this);
 295   _MuxEvent    = ParkEvent::Allocate(this);
 296 
 297 #ifdef CHECK_UNHANDLED_OOPS
 298   if (CheckUnhandledOops) {
 299     _unhandled_oops = new UnhandledOops(this);
 300   }
 301 #endif // CHECK_UNHANDLED_OOPS
 302 #ifdef ASSERT
 303   if (UseBiasedLocking) {
 304     assert(is_aligned(this, markWord::biased_lock_alignment), "forced alignment of thread object failed");
 305     assert(this == _real_malloc_address ||
 306            this == align_up(_real_malloc_address, markWord::biased_lock_alignment),
 307            "bug in forced alignment of thread objects");
 308   }
 309 #endif // ASSERT
 310 
 311   // Notify the barrier set that a thread is being created. The initial
 312   // thread is created before the barrier set is available.  The call to
 313   // BarrierSet::on_thread_create() for this thread is therefore deferred
 314   // to BarrierSet::set_barrier_set().
 315   BarrierSet* const barrier_set = BarrierSet::barrier_set();
 316   if (barrier_set != NULL) {
 317     barrier_set->on_thread_create(this);
 318   } else {
 319     // Only the main thread should be created before the barrier set
 320     // and that happens just before Thread::current is set. No other thread
 321     // can attach as the VM is not created yet, so they can't execute this code.
 322     // If the main thread creates other threads before the barrier set that is an error.
 323     assert(Thread::current_or_null() == NULL, "creating thread before barrier set");
 324   }
 325 }
 326 
 327 void Thread::initialize_thread_current() {
 328 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 329   assert(_thr_current == NULL, "Thread::current already initialized");
 330   _thr_current = this;
 331 #endif
 332   assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
 333   ThreadLocalStorage::set_thread(this);
 334   assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
 335 }
 336 
 337 void Thread::clear_thread_current() {
 338   assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
 339 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 340   _thr_current = NULL;
 341 #endif
 342   ThreadLocalStorage::set_thread(NULL);
 343 }
 344 
 345 void Thread::record_stack_base_and_size() {
 346   // Note: at this point, Thread object is not yet initialized. Do not rely on
 347   // any members being initialized. Do not rely on Thread::current() being set.
 348   // If possible, refrain from doing anything which may crash or assert since
 349   // quite probably those crash dumps will be useless.
 350   set_stack_base(os::current_stack_base());
 351   set_stack_size(os::current_stack_size());
 352 
 353 #ifdef SOLARIS
 354   if (os::is_primordial_thread()) {
 355     os::Solaris::correct_stack_boundaries_for_primordial_thread(this);
 356   }
 357 #endif
 358 
 359   // Set stack limits after thread is initialized.
 360   if (is_Java_thread()) {
 361     ((JavaThread*) this)->set_stack_overflow_limit();
 362     ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
 363   }
 364 }
 365 
 366 #if INCLUDE_NMT
 367 void Thread::register_thread_stack_with_NMT() {
 368   MemTracker::record_thread_stack(stack_end(), stack_size());
 369 }
 370 #endif // INCLUDE_NMT
 371 
 372 void Thread::call_run() {
 373   DEBUG_ONLY(_run_state = CALL_RUN;)
 374 
 375   // At this point, Thread object should be fully initialized and
 376   // Thread::current() should be set.
 377 
 378   assert(Thread::current_or_null() != NULL, "current thread is unset");
 379   assert(Thread::current_or_null() == this, "current thread is wrong");
 380 
 381   // Perform common initialization actions
 382 
 383   register_thread_stack_with_NMT();
 384 
 385   JFR_ONLY(Jfr::on_thread_start(this);)
 386 
 387   log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
 388     PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
 389     os::current_thread_id(), p2i(stack_base() - stack_size()),
 390     p2i(stack_base()), stack_size()/1024);
 391 
 392   // Perform <ChildClass> initialization actions
 393   DEBUG_ONLY(_run_state = PRE_RUN;)
 394   this->pre_run();
 395 
 396   // Invoke <ChildClass>::run()
 397   DEBUG_ONLY(_run_state = RUN;)
 398   this->run();
 399   // Returned from <ChildClass>::run(). Thread finished.
 400 
 401   // Perform common tear-down actions
 402 
 403   assert(Thread::current_or_null() != NULL, "current thread is unset");
 404   assert(Thread::current_or_null() == this, "current thread is wrong");
 405 
 406   // Perform <ChildClass> tear-down actions
 407   DEBUG_ONLY(_run_state = POST_RUN;)
 408   this->post_run();
 409 
 410   // Note: at this point the thread object may already have deleted itself,
 411   // so from here on do not dereference *this*. Not all thread types currently
 412   // delete themselves when they terminate. But no thread should ever be deleted
 413   // asynchronously with respect to its termination - that is what _run_state can
 414   // be used to check.
 415 
 416   assert(Thread::current_or_null() == NULL, "current thread still present");
 417 }
 418 
 419 Thread::~Thread() {
 420 
 421   // Attached threads will remain in PRE_CALL_RUN, as will threads that don't actually
 422   // get started due to errors etc. Any active thread should at least reach post_run
 423   // before it is deleted (usually in post_run()).
 424   assert(_run_state == PRE_CALL_RUN ||
 425          _run_state == POST_RUN, "Active Thread deleted before post_run(): "
 426          "_run_state=%d", (int)_run_state);
 427 
 428   // Notify the barrier set that a thread is being destroyed. Note that a barrier
 429   // set might not be available if we encountered errors during bootstrapping.
 430   BarrierSet* const barrier_set = BarrierSet::barrier_set();
 431   if (barrier_set != NULL) {
 432     barrier_set->on_thread_destroy(this);
 433   }
 434 
 435   // stack_base can be NULL if the thread is never started or exited before
 436   // record_stack_base_and_size called. Although, we would like to ensure
 437   // that all started threads do call record_stack_base_and_size(), there is
 438   // not proper way to enforce that.
 439 #if INCLUDE_NMT
 440   if (_stack_base != NULL) {
 441     MemTracker::release_thread_stack(stack_end(), stack_size());
 442 #ifdef ASSERT
 443     set_stack_base(NULL);
 444 #endif
 445   }
 446 #endif // INCLUDE_NMT
 447 
 448   // deallocate data structures
 449   delete resource_area();
 450   // since the handle marks are using the handle area, we have to deallocated the root
 451   // handle mark before deallocating the thread's handle area,
 452   assert(last_handle_mark() != NULL, "check we have an element");
 453   delete last_handle_mark();
 454   assert(last_handle_mark() == NULL, "check we have reached the end");
 455 
 456   // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
 457   // We NULL out the fields for good hygiene.
 458   ParkEvent::Release(_ParkEvent); _ParkEvent   = NULL;
 459   ParkEvent::Release(_MuxEvent); _MuxEvent    = NULL;
 460 
 461   delete handle_area();
 462   delete metadata_handles();
 463 
 464   // SR_handler uses this as a termination indicator -
 465   // needs to happen before os::free_thread()
 466   delete _SR_lock;
 467   _SR_lock = NULL;
 468 
 469   // osthread() can be NULL, if creation of thread failed.
 470   if (osthread() != NULL) os::free_thread(osthread());
 471 
 472   // Clear Thread::current if thread is deleting itself and it has not
 473   // already been done. This must be done before the memory is deallocated.
 474   // Needed to ensure JNI correctly detects non-attached threads.
 475   if (this == Thread::current_or_null()) {
 476     Thread::clear_thread_current();
 477   }
 478 
 479   CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
 480 }
 481 
 482 #ifdef ASSERT
 483 // A JavaThread is considered "dangling" if it is not the current
 484 // thread, has been added the Threads list, the system is not at a
 485 // safepoint and the Thread is not "protected".
 486 //
 487 void Thread::check_for_dangling_thread_pointer(Thread *thread) {
 488   assert(!thread->is_Java_thread() || Thread::current() == thread ||
 489          !((JavaThread *) thread)->on_thread_list() ||
 490          SafepointSynchronize::is_at_safepoint() ||
 491          ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread),
 492          "possibility of dangling Thread pointer");
 493 }
 494 #endif
 495 
 496 ThreadPriority Thread::get_priority(const Thread* const thread) {
 497   ThreadPriority priority;
 498   // Can return an error!
 499   (void)os::get_priority(thread, priority);
 500   assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
 501   return priority;
 502 }
 503 
 504 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
 505   debug_only(check_for_dangling_thread_pointer(thread);)
 506   // Can return an error!
 507   (void)os::set_priority(thread, priority);
 508 }
 509 
 510 
 511 void Thread::start(Thread* thread) {
 512   // Start is different from resume in that its safety is guaranteed by context or
 513   // being called from a Java method synchronized on the Thread object.
 514   if (!DisableStartThread) {
 515     if (thread->is_Java_thread()) {
 516       // Initialize the thread state to RUNNABLE before starting this thread.
 517       // Can not set it after the thread started because we do not know the
 518       // exact thread state at that time. It could be in MONITOR_WAIT or
 519       // in SLEEPING or some other state.
 520       java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
 521                                           java_lang_Thread::RUNNABLE);
 522     }
 523     os::start_thread(thread);
 524   }
 525 }
 526 
 527 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
 528   VM_ThreadStop vm_stop(java_thread, java_throwable);
 529   VMThread::execute(&vm_stop);
 530 }
 531 
 532 
 533 // Check if an external suspend request has completed (or has been
 534 // cancelled). Returns true if the thread is externally suspended and
 535 // false otherwise.
 536 //
 537 // The bits parameter returns information about the code path through
 538 // the routine. Useful for debugging:
 539 //
 540 // set in is_ext_suspend_completed():
 541 // 0x00000001 - routine was entered
 542 // 0x00000010 - routine return false at end
 543 // 0x00000100 - thread exited (return false)
 544 // 0x00000200 - suspend request cancelled (return false)
 545 // 0x00000400 - thread suspended (return true)
 546 // 0x00001000 - thread is in a suspend equivalent state (return true)
 547 // 0x00002000 - thread is native and walkable (return true)
 548 // 0x00004000 - thread is native_trans and walkable (needed retry)
 549 //
 550 // set in wait_for_ext_suspend_completion():
 551 // 0x00010000 - routine was entered
 552 // 0x00020000 - suspend request cancelled before loop (return false)
 553 // 0x00040000 - thread suspended before loop (return true)
 554 // 0x00080000 - suspend request cancelled in loop (return false)
 555 // 0x00100000 - thread suspended in loop (return true)
 556 // 0x00200000 - suspend not completed during retry loop (return false)
 557 
 558 // Helper class for tracing suspend wait debug bits.
 559 //
 560 // 0x00000100 indicates that the target thread exited before it could
 561 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
 562 // 0x00080000 each indicate a cancelled suspend request so they don't
 563 // count as wait failures either.
 564 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
 565 
 566 class TraceSuspendDebugBits : public StackObj {
 567  private:
 568   JavaThread * jt;
 569   bool         is_wait;
 570   bool         called_by_wait;  // meaningful when !is_wait
 571   uint32_t *   bits;
 572 
 573  public:
 574   TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
 575                         uint32_t *_bits) {
 576     jt             = _jt;
 577     is_wait        = _is_wait;
 578     called_by_wait = _called_by_wait;
 579     bits           = _bits;
 580   }
 581 
 582   ~TraceSuspendDebugBits() {
 583     if (!is_wait) {
 584 #if 1
 585       // By default, don't trace bits for is_ext_suspend_completed() calls.
 586       // That trace is very chatty.
 587       return;
 588 #else
 589       if (!called_by_wait) {
 590         // If tracing for is_ext_suspend_completed() is enabled, then only
 591         // trace calls to it from wait_for_ext_suspend_completion()
 592         return;
 593       }
 594 #endif
 595     }
 596 
 597     if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
 598       if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
 599         MutexLocker ml(Threads_lock);  // needed for get_thread_name()
 600         ResourceMark rm;
 601 
 602         tty->print_cr(
 603                       "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
 604                       jt->get_thread_name(), *bits);
 605 
 606         guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
 607       }
 608     }
 609   }
 610 };
 611 #undef DEBUG_FALSE_BITS
 612 
 613 
 614 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
 615                                           uint32_t *bits) {
 616   TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
 617 
 618   bool did_trans_retry = false;  // only do thread_in_native_trans retry once
 619   bool do_trans_retry;           // flag to force the retry
 620 
 621   *bits |= 0x00000001;
 622 
 623   do {
 624     do_trans_retry = false;
 625 
 626     if (is_exiting()) {
 627       // Thread is in the process of exiting. This is always checked
 628       // first to reduce the risk of dereferencing a freed JavaThread.
 629       *bits |= 0x00000100;
 630       return false;
 631     }
 632 
 633     if (!is_external_suspend()) {
 634       // Suspend request is cancelled. This is always checked before
 635       // is_ext_suspended() to reduce the risk of a rogue resume
 636       // confusing the thread that made the suspend request.
 637       *bits |= 0x00000200;
 638       return false;
 639     }
 640 
 641     if (is_ext_suspended()) {
 642       // thread is suspended
 643       *bits |= 0x00000400;
 644       return true;
 645     }
 646 
 647     // Now that we no longer do hard suspends of threads running
 648     // native code, the target thread can be changing thread state
 649     // while we are in this routine:
 650     //
 651     //   _thread_in_native -> _thread_in_native_trans -> _thread_blocked
 652     //
 653     // We save a copy of the thread state as observed at this moment
 654     // and make our decision about suspend completeness based on the
 655     // copy. This closes the race where the thread state is seen as
 656     // _thread_in_native_trans in the if-thread_blocked check, but is
 657     // seen as _thread_blocked in if-thread_in_native_trans check.
 658     JavaThreadState save_state = thread_state();
 659 
 660     if (save_state == _thread_blocked && is_suspend_equivalent()) {
 661       // If the thread's state is _thread_blocked and this blocking
 662       // condition is known to be equivalent to a suspend, then we can
 663       // consider the thread to be externally suspended. This means that
 664       // the code that sets _thread_blocked has been modified to do
 665       // self-suspension if the blocking condition releases. We also
 666       // used to check for CONDVAR_WAIT here, but that is now covered by
 667       // the _thread_blocked with self-suspension check.
 668       //
 669       // Return true since we wouldn't be here unless there was still an
 670       // external suspend request.
 671       *bits |= 0x00001000;
 672       return true;
 673     } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
 674       // Threads running native code will self-suspend on native==>VM/Java
 675       // transitions. If its stack is walkable (should always be the case
 676       // unless this function is called before the actual java_suspend()
 677       // call), then the wait is done.
 678       *bits |= 0x00002000;
 679       return true;
 680     } else if (!called_by_wait && !did_trans_retry &&
 681                save_state == _thread_in_native_trans &&
 682                frame_anchor()->walkable()) {
 683       // The thread is transitioning from thread_in_native to another
 684       // thread state. check_safepoint_and_suspend_for_native_trans()
 685       // will force the thread to self-suspend. If it hasn't gotten
 686       // there yet we may have caught the thread in-between the native
 687       // code check above and the self-suspend. Lucky us. If we were
 688       // called by wait_for_ext_suspend_completion(), then it
 689       // will be doing the retries so we don't have to.
 690       //
 691       // Since we use the saved thread state in the if-statement above,
 692       // there is a chance that the thread has already transitioned to
 693       // _thread_blocked by the time we get here. In that case, we will
 694       // make a single unnecessary pass through the logic below. This
 695       // doesn't hurt anything since we still do the trans retry.
 696 
 697       *bits |= 0x00004000;
 698 
 699       // Once the thread leaves thread_in_native_trans for another
 700       // thread state, we break out of this retry loop. We shouldn't
 701       // need this flag to prevent us from getting back here, but
 702       // sometimes paranoia is good.
 703       did_trans_retry = true;
 704 
 705       // We wait for the thread to transition to a more usable state.
 706       for (int i = 1; i <= SuspendRetryCount; i++) {
 707         // We used to do an "os::yield_all(i)" call here with the intention
 708         // that yielding would increase on each retry. However, the parameter
 709         // is ignored on Linux which means the yield didn't scale up. Waiting
 710         // on the SR_lock below provides a much more predictable scale up for
 711         // the delay. It also provides a simple/direct point to check for any
 712         // safepoint requests from the VMThread
 713 
 714         // temporarily drops SR_lock while doing wait with safepoint check
 715         // (if we're a JavaThread - the WatcherThread can also call this)
 716         // and increase delay with each retry
 717         if (Thread::current()->is_Java_thread()) {
 718           SR_lock()->wait(i * delay);
 719         } else {
 720           SR_lock()->wait_without_safepoint_check(i * delay);
 721         }
 722 
 723         // check the actual thread state instead of what we saved above
 724         if (thread_state() != _thread_in_native_trans) {
 725           // the thread has transitioned to another thread state so
 726           // try all the checks (except this one) one more time.
 727           do_trans_retry = true;
 728           break;
 729         }
 730       } // end retry loop
 731 
 732 
 733     }
 734   } while (do_trans_retry);
 735 
 736   *bits |= 0x00000010;
 737   return false;
 738 }
 739 
 740 // Wait for an external suspend request to complete (or be cancelled).
 741 // Returns true if the thread is externally suspended and false otherwise.
 742 //
 743 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
 744                                                  uint32_t *bits) {
 745   TraceSuspendDebugBits tsdb(this, true /* is_wait */,
 746                              false /* !called_by_wait */, bits);
 747 
 748   // local flag copies to minimize SR_lock hold time
 749   bool is_suspended;
 750   bool pending;
 751   uint32_t reset_bits;
 752 
 753   // set a marker so is_ext_suspend_completed() knows we are the caller
 754   *bits |= 0x00010000;
 755 
 756   // We use reset_bits to reinitialize the bits value at the top of
 757   // each retry loop. This allows the caller to make use of any
 758   // unused bits for their own marking purposes.
 759   reset_bits = *bits;
 760 
 761   {
 762     MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
 763     is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 764                                             delay, bits);
 765     pending = is_external_suspend();
 766   }
 767   // must release SR_lock to allow suspension to complete
 768 
 769   if (!pending) {
 770     // A cancelled suspend request is the only false return from
 771     // is_ext_suspend_completed() that keeps us from entering the
 772     // retry loop.
 773     *bits |= 0x00020000;
 774     return false;
 775   }
 776 
 777   if (is_suspended) {
 778     *bits |= 0x00040000;
 779     return true;
 780   }
 781 
 782   for (int i = 1; i <= retries; i++) {
 783     *bits = reset_bits;  // reinit to only track last retry
 784 
 785     // We used to do an "os::yield_all(i)" call here with the intention
 786     // that yielding would increase on each retry. However, the parameter
 787     // is ignored on Linux which means the yield didn't scale up. Waiting
 788     // on the SR_lock below provides a much more predictable scale up for
 789     // the delay. It also provides a simple/direct point to check for any
 790     // safepoint requests from the VMThread
 791 
 792     {
 793       Thread* t = Thread::current();
 794       MonitorLocker ml(SR_lock(),
 795                        t->is_Java_thread() ? Mutex::_safepoint_check_flag : Mutex::_no_safepoint_check_flag);
 796       // wait with safepoint check (if we're a JavaThread - the WatcherThread
 797       // can also call this)  and increase delay with each retry
 798       ml.wait(i * delay);
 799 
 800       is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 801                                               delay, bits);
 802 
 803       // It is possible for the external suspend request to be cancelled
 804       // (by a resume) before the actual suspend operation is completed.
 805       // Refresh our local copy to see if we still need to wait.
 806       pending = is_external_suspend();
 807     }
 808 
 809     if (!pending) {
 810       // A cancelled suspend request is the only false return from
 811       // is_ext_suspend_completed() that keeps us from staying in the
 812       // retry loop.
 813       *bits |= 0x00080000;
 814       return false;
 815     }
 816 
 817     if (is_suspended) {
 818       *bits |= 0x00100000;
 819       return true;
 820     }
 821   } // end retry loop
 822 
 823   // thread did not suspend after all our retries
 824   *bits |= 0x00200000;
 825   return false;
 826 }
 827 
 828 // Called from API entry points which perform stack walking. If the
 829 // associated JavaThread is the current thread, then wait_for_suspend
 830 // is not used. Otherwise, it determines if we should wait for the
 831 // "other" thread to complete external suspension. (NOTE: in future
 832 // releases the suspension mechanism should be reimplemented so this
 833 // is not necessary.)
 834 //
 835 bool
 836 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) {
 837   if (this != JavaThread::current()) {
 838     // "other" threads require special handling.
 839     if (wait_for_suspend) {
 840       // We are allowed to wait for the external suspend to complete
 841       // so give the other thread a chance to get suspended.
 842       if (!wait_for_ext_suspend_completion(SuspendRetryCount,
 843                                            SuspendRetryDelay, bits)) {
 844         // Didn't make it so let the caller know.
 845         return false;
 846       }
 847     }
 848     // We aren't allowed to wait for the external suspend to complete
 849     // so if the other thread isn't externally suspended we need to
 850     // let the caller know.
 851     else if (!is_ext_suspend_completed_with_lock(bits)) {
 852       return false;
 853     }
 854   }
 855 
 856   return true;
 857 }
 858 
 859 // GC Support
 860 bool Thread::claim_par_threads_do(uintx claim_token) {
 861   uintx token = _threads_do_token;
 862   if (token != claim_token) {
 863     uintx res = Atomic::cmpxchg(&_threads_do_token, token, claim_token);
 864     if (res == token) {
 865       return true;
 866     }
 867     guarantee(res == claim_token, "invariant");
 868   }
 869   return false;
 870 }
 871 
 872 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
 873   active_handles()->oops_do(f);
 874   // Do oop for ThreadShadow
 875   f->do_oop((oop*)&_pending_exception);
 876   handle_area()->oops_do(f);
 877 
 878   // We scan thread local monitor lists here, and the remaining global
 879   // monitors in ObjectSynchronizer::oops_do().
 880   ObjectSynchronizer::thread_local_used_oops_do(this, f);
 881 }
 882 
 883 void Thread::metadata_handles_do(void f(Metadata*)) {
 884   // Only walk the Handles in Thread.
 885   if (metadata_handles() != NULL) {
 886     for (int i = 0; i< metadata_handles()->length(); i++) {
 887       f(metadata_handles()->at(i));
 888     }
 889   }
 890 }
 891 
 892 void Thread::print_on(outputStream* st, bool print_extended_info) const {
 893   // get_priority assumes osthread initialized
 894   if (osthread() != NULL) {
 895     int os_prio;
 896     if (os::get_native_priority(this, &os_prio) == OS_OK) {
 897       st->print("os_prio=%d ", os_prio);
 898     }
 899 
 900     st->print("cpu=%.2fms ",
 901               os::thread_cpu_time(const_cast<Thread*>(this), true) / 1000000.0
 902               );
 903     st->print("elapsed=%.2fs ",
 904               _statistical_info.getElapsedTime() / 1000.0
 905               );
 906     if (is_Java_thread() && (PrintExtendedThreadInfo || print_extended_info)) {
 907       size_t allocated_bytes = (size_t) const_cast<Thread*>(this)->cooked_allocated_bytes();
 908       st->print("allocated=" SIZE_FORMAT "%s ",
 909                 byte_size_in_proper_unit(allocated_bytes),
 910                 proper_unit_for_byte_size(allocated_bytes)
 911                 );
 912       st->print("defined_classes=" INT64_FORMAT " ", _statistical_info.getDefineClassCount());
 913     }
 914 
 915     st->print("tid=" INTPTR_FORMAT " ", p2i(this));
 916     osthread()->print_on(st);
 917   }
 918   ThreadsSMRSupport::print_info_on(this, st);
 919   st->print(" ");
 920   debug_only(if (WizardMode) print_owned_locks_on(st);)
 921 }
 922 
 923 void Thread::print() const { print_on(tty); }
 924 
 925 // Thread::print_on_error() is called by fatal error handler. Don't use
 926 // any lock or allocate memory.
 927 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
 928   assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
 929 
 930   if (is_VM_thread())                 { st->print("VMThread"); }
 931   else if (is_GC_task_thread())       { st->print("GCTaskThread"); }
 932   else if (is_Watcher_thread())       { st->print("WatcherThread"); }
 933   else if (is_ConcurrentGC_thread())  { st->print("ConcurrentGCThread"); }
 934   else                                { st->print("Thread"); }
 935 
 936   if (is_Named_thread()) {
 937     st->print(" \"%s\"", name());
 938   }
 939 
 940   st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
 941             p2i(stack_end()), p2i(stack_base()));
 942 
 943   if (osthread()) {
 944     st->print(" [id=%d]", osthread()->thread_id());
 945   }
 946 
 947   ThreadsSMRSupport::print_info_on(this, st);
 948 }
 949 
 950 void Thread::print_value_on(outputStream* st) const {
 951   if (is_Named_thread()) {
 952     st->print(" \"%s\" ", name());
 953   }
 954   st->print(INTPTR_FORMAT, p2i(this));   // print address
 955 }
 956 
 957 #ifdef ASSERT
 958 void Thread::print_owned_locks_on(outputStream* st) const {
 959   Mutex* cur = _owned_locks;
 960   if (cur == NULL) {
 961     st->print(" (no locks) ");
 962   } else {
 963     st->print_cr(" Locks owned:");
 964     while (cur) {
 965       cur->print_on(st);
 966       cur = cur->next();
 967     }
 968   }
 969 }
 970 
 971 // Checks safepoint allowed and clears unhandled oops at potential safepoints.
 972 void Thread::check_possible_safepoint() {
 973   if (!is_Java_thread()) return;
 974 
 975   if (_no_safepoint_count > 0) {
 976     print_owned_locks();
 977     fatal("Possible safepoint reached by thread that does not allow it");
 978   }
 979 #ifdef CHECK_UNHANDLED_OOPS
 980   // Clear unhandled oops in JavaThreads so we get a crash right away.
 981   clear_unhandled_oops();
 982 #endif // CHECK_UNHANDLED_OOPS
 983 }
 984 
 985 void Thread::check_for_valid_safepoint_state() {
 986   if (!is_Java_thread()) return;
 987 
 988   // Check NoSafepointVerifier, which is implied by locks taken that can be
 989   // shared with the VM thread.  This makes sure that no locks with allow_vm_block
 990   // are held.
 991   check_possible_safepoint();
 992 
 993   if (((JavaThread*)this)->thread_state() != _thread_in_vm) {
 994     fatal("LEAF method calling lock?");
 995   }
 996 
 997   if (GCALotAtAllSafepoints) {
 998     // We could enter a safepoint here and thus have a gc
 999     InterfaceSupport::check_gc_alot();
1000   }
1001 }
1002 #endif // ASSERT
1003 
1004 bool Thread::is_in_stack(address adr) const {
1005   assert(Thread::current() == this, "is_in_stack can only be called from current thread");
1006   address end = os::current_stack_pointer();
1007   // Allow non Java threads to call this without stack_base
1008   if (_stack_base == NULL) return true;
1009   if (stack_base() > adr && adr >= end) return true;
1010 
1011   return false;
1012 }
1013 
1014 bool Thread::is_in_usable_stack(address adr) const {
1015   size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
1016   size_t usable_stack_size = _stack_size - stack_guard_size;
1017 
1018   return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
1019 }
1020 
1021 
1022 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
1023 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
1024 // used for compilation in the future. If that change is made, the need for these methods
1025 // should be revisited, and they should be removed if possible.
1026 
1027 bool Thread::is_lock_owned(address adr) const {
1028   return on_local_stack(adr);
1029 }
1030 
1031 bool Thread::set_as_starting_thread() {
1032   assert(_starting_thread == NULL, "already initialized: "
1033          "_starting_thread=" INTPTR_FORMAT, p2i(_starting_thread));
1034   // NOTE: this must be called inside the main thread.
1035   DEBUG_ONLY(_starting_thread = this;)
1036   return os::create_main_thread((JavaThread*)this);
1037 }
1038 
1039 static void initialize_class(Symbol* class_name, TRAPS) {
1040   Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
1041   InstanceKlass::cast(klass)->initialize(CHECK);
1042 }
1043 
1044 
1045 // Creates the initial ThreadGroup
1046 static Handle create_initial_thread_group(TRAPS) {
1047   Handle system_instance = JavaCalls::construct_new_instance(
1048                             SystemDictionary::ThreadGroup_klass(),
1049                             vmSymbols::void_method_signature(),
1050                             CHECK_NH);
1051   Universe::set_system_thread_group(system_instance());
1052 
1053   Handle string = java_lang_String::create_from_str("main", CHECK_NH);
1054   Handle main_instance = JavaCalls::construct_new_instance(
1055                             SystemDictionary::ThreadGroup_klass(),
1056                             vmSymbols::threadgroup_string_void_signature(),
1057                             system_instance,
1058                             string,
1059                             CHECK_NH);
1060   return main_instance;
1061 }
1062 
1063 // Creates the initial Thread
1064 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
1065                                  TRAPS) {
1066   InstanceKlass* ik = SystemDictionary::Thread_klass();
1067   assert(ik->is_initialized(), "must be");
1068   instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
1069 
1070   // Cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1071   // constructor calls Thread.current(), which must be set here for the
1072   // initial thread.
1073   java_lang_Thread::set_thread(thread_oop(), thread);
1074   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1075   thread->set_threadObj(thread_oop());
1076 
1077   Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1078 
1079   JavaValue result(T_VOID);
1080   JavaCalls::call_special(&result, thread_oop,
1081                           ik,
1082                           vmSymbols::object_initializer_name(),
1083                           vmSymbols::threadgroup_string_void_signature(),
1084                           thread_group,
1085                           string,
1086                           CHECK_NULL);
1087   return thread_oop();
1088 }
1089 
1090 char java_runtime_name[128] = "";
1091 char java_runtime_version[128] = "";
1092 char java_runtime_vendor_version[128] = "";
1093 char java_runtime_vendor_vm_bug_url[128] = "";
1094 
1095 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1096 static const char* get_java_runtime_name(TRAPS) {
1097   Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1098                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1099   fieldDescriptor fd;
1100   bool found = k != NULL &&
1101                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1102                                                         vmSymbols::string_signature(), &fd);
1103   if (found) {
1104     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1105     if (name_oop == NULL) {
1106       return NULL;
1107     }
1108     const char* name = java_lang_String::as_utf8_string(name_oop,
1109                                                         java_runtime_name,
1110                                                         sizeof(java_runtime_name));
1111     return name;
1112   } else {
1113     return NULL;
1114   }
1115 }
1116 
1117 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1118 static const char* get_java_runtime_version(TRAPS) {
1119   Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1120                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1121   fieldDescriptor fd;
1122   bool found = k != NULL &&
1123                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1124                                                         vmSymbols::string_signature(), &fd);
1125   if (found) {
1126     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1127     if (name_oop == NULL) {
1128       return NULL;
1129     }
1130     const char* name = java_lang_String::as_utf8_string(name_oop,
1131                                                         java_runtime_version,
1132                                                         sizeof(java_runtime_version));
1133     return name;
1134   } else {
1135     return NULL;
1136   }
1137 }
1138 
1139 // extract the JRE vendor version from java.lang.VersionProps.VENDOR_VERSION
1140 static const char* get_java_runtime_vendor_version(TRAPS) {
1141   Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1142                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1143   fieldDescriptor fd;
1144   bool found = k != NULL &&
1145                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_vendor_version_name(),
1146                                                         vmSymbols::string_signature(), &fd);
1147   if (found) {
1148     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1149     if (name_oop == NULL) {
1150       return NULL;
1151     }
1152     const char* name = java_lang_String::as_utf8_string(name_oop,
1153                                                         java_runtime_vendor_version,
1154                                                         sizeof(java_runtime_vendor_version));
1155     return name;
1156   } else {
1157     return NULL;
1158   }
1159 }
1160 
1161 // extract the JRE vendor VM bug URL from java.lang.VersionProps.VENDOR_URL_VM_BUG
1162 static const char* get_java_runtime_vendor_vm_bug_url(TRAPS) {
1163   Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1164                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1165   fieldDescriptor fd;
1166   bool found = k != NULL &&
1167                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_vendor_vm_bug_url_name(),
1168                                                         vmSymbols::string_signature(), &fd);
1169   if (found) {
1170     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1171     if (name_oop == NULL) {
1172       return NULL;
1173     }
1174     const char* name = java_lang_String::as_utf8_string(name_oop,
1175                                                         java_runtime_vendor_vm_bug_url,
1176                                                         sizeof(java_runtime_vendor_vm_bug_url));
1177     return name;
1178   } else {
1179     return NULL;
1180   }
1181 }
1182 
1183 // General purpose hook into Java code, run once when the VM is initialized.
1184 // The Java library method itself may be changed independently from the VM.
1185 static void call_postVMInitHook(TRAPS) {
1186   Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1187   if (klass != NULL) {
1188     JavaValue result(T_VOID);
1189     JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1190                            vmSymbols::void_method_signature(),
1191                            CHECK);
1192   }
1193 }
1194 
1195 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1196                                     bool daemon, TRAPS) {
1197   assert(thread_group.not_null(), "thread group should be specified");
1198   assert(threadObj() == NULL, "should only create Java thread object once");
1199 
1200   InstanceKlass* ik = SystemDictionary::Thread_klass();
1201   assert(ik->is_initialized(), "must be");
1202   instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1203 
1204   // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon.
1205   // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1206   // constructor calls Thread.current(), which must be set here.
1207   java_lang_Thread::set_thread(thread_oop(), this);
1208   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1209   set_threadObj(thread_oop());
1210 
1211   JavaValue result(T_VOID);
1212   if (thread_name != NULL) {
1213     Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1214     // Thread gets assigned specified name and null target
1215     JavaCalls::call_special(&result,
1216                             thread_oop,
1217                             ik,
1218                             vmSymbols::object_initializer_name(),
1219                             vmSymbols::threadgroup_string_void_signature(),
1220                             thread_group,
1221                             name,
1222                             THREAD);
1223   } else {
1224     // Thread gets assigned name "Thread-nnn" and null target
1225     // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1226     JavaCalls::call_special(&result,
1227                             thread_oop,
1228                             ik,
1229                             vmSymbols::object_initializer_name(),
1230                             vmSymbols::threadgroup_runnable_void_signature(),
1231                             thread_group,
1232                             Handle(),
1233                             THREAD);
1234   }
1235 
1236 
1237   if (daemon) {
1238     java_lang_Thread::set_daemon(thread_oop());
1239   }
1240 
1241   if (HAS_PENDING_EXCEPTION) {
1242     return;
1243   }
1244 
1245   Klass* group =  SystemDictionary::ThreadGroup_klass();
1246   Handle threadObj(THREAD, this->threadObj());
1247 
1248   JavaCalls::call_special(&result,
1249                           thread_group,
1250                           group,
1251                           vmSymbols::add_method_name(),
1252                           vmSymbols::thread_void_signature(),
1253                           threadObj,          // Arg 1
1254                           THREAD);
1255 }
1256 
1257 // List of all NonJavaThreads and safe iteration over that list.
1258 
1259 class NonJavaThread::List {
1260 public:
1261   NonJavaThread* volatile _head;
1262   SingleWriterSynchronizer _protect;
1263 
1264   List() : _head(NULL), _protect() {}
1265 };
1266 
1267 NonJavaThread::List NonJavaThread::_the_list;
1268 
1269 NonJavaThread::Iterator::Iterator() :
1270   _protect_enter(_the_list._protect.enter()),
1271   _current(Atomic::load_acquire(&_the_list._head))
1272 {}
1273 
1274 NonJavaThread::Iterator::~Iterator() {
1275   _the_list._protect.exit(_protect_enter);
1276 }
1277 
1278 void NonJavaThread::Iterator::step() {
1279   assert(!end(), "precondition");
1280   _current = Atomic::load_acquire(&_current->_next);
1281 }
1282 
1283 NonJavaThread::NonJavaThread() : Thread(), _next(NULL) {
1284   assert(BarrierSet::barrier_set() != NULL, "NonJavaThread created too soon!");
1285 }
1286 
1287 NonJavaThread::~NonJavaThread() { }
1288 
1289 void NonJavaThread::add_to_the_list() {
1290   MutexLocker ml(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1291   // Initialize BarrierSet-related data before adding to list.
1292   BarrierSet::barrier_set()->on_thread_attach(this);
1293   Atomic::release_store(&_next, _the_list._head);
1294   Atomic::release_store(&_the_list._head, this);
1295 }
1296 
1297 void NonJavaThread::remove_from_the_list() {
1298   {
1299     MutexLocker ml(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1300     // Cleanup BarrierSet-related data before removing from list.
1301     BarrierSet::barrier_set()->on_thread_detach(this);
1302     NonJavaThread* volatile* p = &_the_list._head;
1303     for (NonJavaThread* t = *p; t != NULL; p = &t->_next, t = *p) {
1304       if (t == this) {
1305         *p = _next;
1306         break;
1307       }
1308     }
1309   }
1310   // Wait for any in-progress iterators.  Concurrent synchronize is not
1311   // allowed, so do it while holding a dedicated lock.  Outside and distinct
1312   // from NJTList_lock in case an iteration attempts to lock it.
1313   MutexLocker ml(NonJavaThreadsListSync_lock, Mutex::_no_safepoint_check_flag);
1314   _the_list._protect.synchronize();
1315   _next = NULL;                 // Safe to drop the link now.
1316 }
1317 
1318 void NonJavaThread::pre_run() {
1319   add_to_the_list();
1320 
1321   // This is slightly odd in that NamedThread is a subclass, but
1322   // in fact name() is defined in Thread
1323   assert(this->name() != NULL, "thread name was not set before it was started");
1324   this->set_native_thread_name(this->name());
1325 }
1326 
1327 void NonJavaThread::post_run() {
1328   JFR_ONLY(Jfr::on_thread_exit(this);)
1329   remove_from_the_list();
1330   // Ensure thread-local-storage is cleared before termination.
1331   Thread::clear_thread_current();
1332 }
1333 
1334 // NamedThread --  non-JavaThread subclasses with multiple
1335 // uniquely named instances should derive from this.
1336 NamedThread::NamedThread() :
1337   NonJavaThread(),
1338   _name(NULL),
1339   _processed_thread(NULL),
1340   _gc_id(GCId::undefined())
1341 {}
1342 
1343 NamedThread::~NamedThread() {
1344   FREE_C_HEAP_ARRAY(char, _name);
1345 }
1346 
1347 void NamedThread::set_name(const char* format, ...) {
1348   guarantee(_name == NULL, "Only get to set name once.");
1349   _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1350   va_list ap;
1351   va_start(ap, format);
1352   jio_vsnprintf(_name, max_name_len, format, ap);
1353   va_end(ap);
1354 }
1355 
1356 void NamedThread::print_on(outputStream* st) const {
1357   st->print("\"%s\" ", name());
1358   Thread::print_on(st);
1359   st->cr();
1360 }
1361 
1362 
1363 // ======= WatcherThread ========
1364 
1365 // The watcher thread exists to simulate timer interrupts.  It should
1366 // be replaced by an abstraction over whatever native support for
1367 // timer interrupts exists on the platform.
1368 
1369 WatcherThread* WatcherThread::_watcher_thread   = NULL;
1370 bool WatcherThread::_startable = false;
1371 volatile bool  WatcherThread::_should_terminate = false;
1372 
1373 WatcherThread::WatcherThread() : NonJavaThread() {
1374   assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1375   if (os::create_thread(this, os::watcher_thread)) {
1376     _watcher_thread = this;
1377 
1378     // Set the watcher thread to the highest OS priority which should not be
1379     // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1380     // is created. The only normal thread using this priority is the reference
1381     // handler thread, which runs for very short intervals only.
1382     // If the VMThread's priority is not lower than the WatcherThread profiling
1383     // will be inaccurate.
1384     os::set_priority(this, MaxPriority);
1385     if (!DisableStartThread) {
1386       os::start_thread(this);
1387     }
1388   }
1389 }
1390 
1391 int WatcherThread::sleep() const {
1392   // The WatcherThread does not participate in the safepoint protocol
1393   // for the PeriodicTask_lock because it is not a JavaThread.
1394   MonitorLocker ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1395 
1396   if (_should_terminate) {
1397     // check for termination before we do any housekeeping or wait
1398     return 0;  // we did not sleep.
1399   }
1400 
1401   // remaining will be zero if there are no tasks,
1402   // causing the WatcherThread to sleep until a task is
1403   // enrolled
1404   int remaining = PeriodicTask::time_to_wait();
1405   int time_slept = 0;
1406 
1407   // we expect this to timeout - we only ever get unparked when
1408   // we should terminate or when a new task has been enrolled
1409   OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1410 
1411   jlong time_before_loop = os::javaTimeNanos();
1412 
1413   while (true) {
1414     bool timedout = ml.wait(remaining);
1415     jlong now = os::javaTimeNanos();
1416 
1417     if (remaining == 0) {
1418       // if we didn't have any tasks we could have waited for a long time
1419       // consider the time_slept zero and reset time_before_loop
1420       time_slept = 0;
1421       time_before_loop = now;
1422     } else {
1423       // need to recalculate since we might have new tasks in _tasks
1424       time_slept = (int) ((now - time_before_loop) / 1000000);
1425     }
1426 
1427     // Change to task list or spurious wakeup of some kind
1428     if (timedout || _should_terminate) {
1429       break;
1430     }
1431 
1432     remaining = PeriodicTask::time_to_wait();
1433     if (remaining == 0) {
1434       // Last task was just disenrolled so loop around and wait until
1435       // another task gets enrolled
1436       continue;
1437     }
1438 
1439     remaining -= time_slept;
1440     if (remaining <= 0) {
1441       break;
1442     }
1443   }
1444 
1445   return time_slept;
1446 }
1447 
1448 void WatcherThread::run() {
1449   assert(this == watcher_thread(), "just checking");
1450 
1451   this->set_active_handles(JNIHandleBlock::allocate_block());
1452   while (true) {
1453     assert(watcher_thread() == Thread::current(), "thread consistency check");
1454     assert(watcher_thread() == this, "thread consistency check");
1455 
1456     // Calculate how long it'll be until the next PeriodicTask work
1457     // should be done, and sleep that amount of time.
1458     int time_waited = sleep();
1459 
1460     if (VMError::is_error_reported()) {
1461       // A fatal error has happened, the error handler(VMError::report_and_die)
1462       // should abort JVM after creating an error log file. However in some
1463       // rare cases, the error handler itself might deadlock. Here periodically
1464       // check for error reporting timeouts, and if it happens, just proceed to
1465       // abort the VM.
1466 
1467       // This code is in WatcherThread because WatcherThread wakes up
1468       // periodically so the fatal error handler doesn't need to do anything;
1469       // also because the WatcherThread is less likely to crash than other
1470       // threads.
1471 
1472       for (;;) {
1473         // Note: we use naked sleep in this loop because we want to avoid using
1474         // any kind of VM infrastructure which may be broken at this point.
1475         if (VMError::check_timeout()) {
1476           // We hit error reporting timeout. Error reporting was interrupted and
1477           // will be wrapping things up now (closing files etc). Give it some more
1478           // time, then quit the VM.
1479           os::naked_short_sleep(200);
1480           // Print a message to stderr.
1481           fdStream err(defaultStream::output_fd());
1482           err.print_raw_cr("# [ timer expired, abort... ]");
1483           // skip atexit/vm_exit/vm_abort hooks
1484           os::die();
1485         }
1486 
1487         // Wait a second, then recheck for timeout.
1488         os::naked_short_sleep(999);
1489       }
1490     }
1491 
1492     if (_should_terminate) {
1493       // check for termination before posting the next tick
1494       break;
1495     }
1496 
1497     PeriodicTask::real_time_tick(time_waited);
1498   }
1499 
1500   // Signal that it is terminated
1501   {
1502     MutexLocker mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1503     _watcher_thread = NULL;
1504     Terminator_lock->notify_all();
1505   }
1506 }
1507 
1508 void WatcherThread::start() {
1509   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1510 
1511   if (watcher_thread() == NULL && _startable) {
1512     _should_terminate = false;
1513     // Create the single instance of WatcherThread
1514     new WatcherThread();
1515   }
1516 }
1517 
1518 void WatcherThread::make_startable() {
1519   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1520   _startable = true;
1521 }
1522 
1523 void WatcherThread::stop() {
1524   {
1525     // Follow normal safepoint aware lock enter protocol since the
1526     // WatcherThread is stopped by another JavaThread.
1527     MutexLocker ml(PeriodicTask_lock);
1528     _should_terminate = true;
1529 
1530     WatcherThread* watcher = watcher_thread();
1531     if (watcher != NULL) {
1532       // unpark the WatcherThread so it can see that it should terminate
1533       watcher->unpark();
1534     }
1535   }
1536 
1537   MonitorLocker mu(Terminator_lock);
1538 
1539   while (watcher_thread() != NULL) {
1540     // This wait should make safepoint checks, wait without a timeout,
1541     // and wait as a suspend-equivalent condition.
1542     mu.wait(0, Mutex::_as_suspend_equivalent_flag);
1543   }
1544 }
1545 
1546 void WatcherThread::unpark() {
1547   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1548   PeriodicTask_lock->notify();
1549 }
1550 
1551 void WatcherThread::print_on(outputStream* st) const {
1552   st->print("\"%s\" ", name());
1553   Thread::print_on(st);
1554   st->cr();
1555 }
1556 
1557 // ======= JavaThread ========
1558 
1559 #if INCLUDE_JVMCI
1560 
1561 jlong* JavaThread::_jvmci_old_thread_counters;
1562 
1563 bool jvmci_counters_include(JavaThread* thread) {
1564   return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1565 }
1566 
1567 void JavaThread::collect_counters(jlong* array, int length) {
1568   assert(length == JVMCICounterSize, "wrong value");
1569   for (int i = 0; i < length; i++) {
1570     array[i] = _jvmci_old_thread_counters[i];
1571   }
1572   for (JavaThreadIteratorWithHandle jtiwh; JavaThread *tp = jtiwh.next(); ) {
1573     if (jvmci_counters_include(tp)) {
1574       for (int i = 0; i < length; i++) {
1575         array[i] += tp->_jvmci_counters[i];
1576       }
1577     }
1578   }
1579 }
1580 
1581 // Attempt to enlarge the array for per thread counters.
1582 jlong* resize_counters_array(jlong* old_counters, int current_size, int new_size) {
1583   jlong* new_counters = NEW_C_HEAP_ARRAY(jlong, new_size, mtJVMCI);
1584   if (old_counters == NULL) {
1585     old_counters = new_counters;
1586     memset(old_counters, 0, sizeof(jlong) * new_size);
1587   } else {
1588     for (int i = 0; i < MIN2((int) current_size, new_size); i++) {
1589       new_counters[i] = old_counters[i];
1590     }
1591     if (new_size > current_size) {
1592       memset(new_counters + current_size, 0, sizeof(jlong) * (new_size - current_size));
1593     }
1594     FREE_C_HEAP_ARRAY(jlong, old_counters);
1595   }
1596   return new_counters;
1597 }
1598 
1599 // Attempt to enlarge the array for per thread counters.
1600 void JavaThread::resize_counters(int current_size, int new_size) {
1601   _jvmci_counters = resize_counters_array(_jvmci_counters, current_size, new_size);
1602 }
1603 
1604 class VM_JVMCIResizeCounters : public VM_Operation {
1605  private:
1606   int _new_size;
1607 
1608  public:
1609   VM_JVMCIResizeCounters(int new_size) : _new_size(new_size) { }
1610   VMOp_Type type()                  const        { return VMOp_JVMCIResizeCounters; }
1611   bool allow_nested_vm_operations() const        { return true; }
1612   void doit() {
1613     // Resize the old thread counters array
1614     jlong* new_counters = resize_counters_array(JavaThread::_jvmci_old_thread_counters, JVMCICounterSize, _new_size);
1615     JavaThread::_jvmci_old_thread_counters = new_counters;
1616 
1617     // Now resize each threads array
1618     for (JavaThreadIteratorWithHandle jtiwh; JavaThread *tp = jtiwh.next(); ) {
1619       tp->resize_counters(JVMCICounterSize, _new_size);
1620     }
1621     JVMCICounterSize = _new_size;
1622   }
1623 };
1624 
1625 void JavaThread::resize_all_jvmci_counters(int new_size) {
1626   VM_JVMCIResizeCounters op(new_size);
1627   VMThread::execute(&op);
1628 }
1629 
1630 #endif // INCLUDE_JVMCI
1631 
1632 // A JavaThread is a normal Java thread
1633 
1634 void JavaThread::initialize() {
1635   // Initialize fields
1636 
1637   set_saved_exception_pc(NULL);
1638   set_threadObj(NULL);
1639   _anchor.clear();
1640   set_entry_point(NULL);
1641   set_jni_functions(jni_functions());
1642   set_callee_target(NULL);
1643   set_vm_result(NULL);
1644   set_vm_result_2(NULL);
1645   set_vframe_array_head(NULL);
1646   set_vframe_array_last(NULL);
1647   set_deferred_locals(NULL);
1648   set_deopt_mark(NULL);
1649   set_deopt_compiled_method(NULL);
1650   set_monitor_chunks(NULL);
1651   _on_thread_list = false;
1652   set_thread_state(_thread_new);
1653   _terminated = _not_terminated;
1654   _array_for_gc = NULL;
1655   _suspend_equivalent = false;
1656   _in_deopt_handler = 0;
1657   _doing_unsafe_access = false;
1658   _stack_guard_state = stack_guard_unused;
1659 #if INCLUDE_JVMCI
1660   _pending_monitorenter = false;
1661   _pending_deoptimization = -1;
1662   _pending_failed_speculation = 0;
1663   _pending_transfer_to_interpreter = false;
1664   _in_retryable_allocation = false;
1665   _jvmci._alternate_call_target = NULL;
1666   assert(_jvmci._implicit_exception_pc == NULL, "must be");
1667   _jvmci_counters = NULL;
1668   if (JVMCICounterSize > 0) {
1669     resize_counters(0, (int) JVMCICounterSize);
1670   }
1671 #endif // INCLUDE_JVMCI
1672   _reserved_stack_activation = NULL;  // stack base not known yet
1673   (void)const_cast<oop&>(_exception_oop = oop(NULL));
1674   _exception_pc  = 0;
1675   _exception_handler_pc = 0;
1676   _is_method_handle_return = 0;
1677   _jvmti_thread_state= NULL;
1678   _should_post_on_exceptions_flag = JNI_FALSE;
1679   _interp_only_mode    = 0;
1680   _special_runtime_exit_condition = _no_async_condition;
1681   _pending_async_exception = NULL;
1682   _thread_stat = NULL;
1683   _thread_stat = new ThreadStatistics();
1684   _jni_active_critical = 0;
1685   _pending_jni_exception_check_fn = NULL;
1686   _do_not_unlock_if_synchronized = false;
1687   _cached_monitor_info = NULL;
1688   _parker = Parker::Allocate(this);
1689   _SleepEvent = ParkEvent::Allocate(this);
1690   // Setup safepoint state info for this thread
1691   ThreadSafepointState::create(this);
1692 
1693   debug_only(_java_call_counter = 0);
1694 
1695   // JVMTI PopFrame support
1696   _popframe_condition = popframe_inactive;
1697   _popframe_preserved_args = NULL;
1698   _popframe_preserved_args_size = 0;
1699   _frames_to_pop_failed_realloc = 0;
1700 
1701   if (SafepointMechanism::uses_thread_local_poll()) {
1702     SafepointMechanism::initialize_header(this);
1703   }
1704 
1705   _class_to_be_initialized = NULL;
1706 
1707   pd_initialize();
1708 }
1709 
1710 JavaThread::JavaThread(bool is_attaching_via_jni) :
1711                        Thread() {
1712   initialize();
1713   if (is_attaching_via_jni) {
1714     _jni_attach_state = _attaching_via_jni;
1715   } else {
1716     _jni_attach_state = _not_attaching_via_jni;
1717   }
1718   assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1719 }
1720 
1721 
1722 // interrupt support
1723 
1724 void JavaThread::interrupt() {
1725   debug_only(check_for_dangling_thread_pointer(this);)
1726 
1727   // For Windows _interrupt_event
1728   osthread()->set_interrupted(true);
1729 
1730   // For Thread.sleep
1731   _SleepEvent->unpark();
1732 
1733   // For JSR166 LockSupport.park
1734   parker()->unpark();
1735 
1736   // For ObjectMonitor and JvmtiRawMonitor
1737   _ParkEvent->unpark();
1738 }
1739 
1740 
1741 bool JavaThread::is_interrupted(bool clear_interrupted) {
1742   debug_only(check_for_dangling_thread_pointer(this);)
1743 
1744   if (threadObj() == NULL) {
1745     // If there is no j.l.Thread then it is impossible to have
1746     // been interrupted. We can find NULL during VM initialization
1747     // or when a JNI thread is still in the process of attaching.
1748     // In such cases this must be the current thread.
1749     assert(this == Thread::current(), "invariant");
1750     return false;
1751   }
1752 
1753   bool interrupted = java_lang_Thread::interrupted(threadObj());
1754 
1755   // NOTE that since there is no "lock" around the interrupt and
1756   // is_interrupted operations, there is the possibility that the
1757   // interrupted flag will be "false" but that the
1758   // low-level events will be in the signaled state. This is
1759   // intentional. The effect of this is that Object.wait() and
1760   // LockSupport.park() will appear to have a spurious wakeup, which
1761   // is allowed and not harmful, and the possibility is so rare that
1762   // it is not worth the added complexity to add yet another lock.
1763   // For the sleep event an explicit reset is performed on entry
1764   // to JavaThread::sleep, so there is no early return. It has also been
1765   // recommended not to put the interrupted flag into the "event"
1766   // structure because it hides the issue.
1767   // Also, because there is no lock, we must only clear the interrupt
1768   // state if we are going to report that we were interrupted; otherwise
1769   // an interrupt that happens just after we read the field would be lost.
1770   if (interrupted && clear_interrupted) {
1771     assert(this == Thread::current(), "only the current thread can clear");
1772     java_lang_Thread::set_interrupted(threadObj(), false);
1773     osthread()->set_interrupted(false);
1774   }
1775 
1776   return interrupted;
1777 }
1778 
1779 bool JavaThread::reguard_stack(address cur_sp) {
1780   if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1781       && _stack_guard_state != stack_guard_reserved_disabled) {
1782     return true; // Stack already guarded or guard pages not needed.
1783   }
1784 
1785   if (register_stack_overflow()) {
1786     // For those architectures which have separate register and
1787     // memory stacks, we must check the register stack to see if
1788     // it has overflowed.
1789     return false;
1790   }
1791 
1792   // Java code never executes within the yellow zone: the latter is only
1793   // there to provoke an exception during stack banging.  If java code
1794   // is executing there, either StackShadowPages should be larger, or
1795   // some exception code in c1, c2 or the interpreter isn't unwinding
1796   // when it should.
1797   guarantee(cur_sp > stack_reserved_zone_base(),
1798             "not enough space to reguard - increase StackShadowPages");
1799   if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1800     enable_stack_yellow_reserved_zone();
1801     if (reserved_stack_activation() != stack_base()) {
1802       set_reserved_stack_activation(stack_base());
1803     }
1804   } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1805     set_reserved_stack_activation(stack_base());
1806     enable_stack_reserved_zone();
1807   }
1808   return true;
1809 }
1810 
1811 bool JavaThread::reguard_stack(void) {
1812   return reguard_stack(os::current_stack_pointer());
1813 }
1814 
1815 
1816 void JavaThread::block_if_vm_exited() {
1817   if (_terminated == _vm_exited) {
1818     // _vm_exited is set at safepoint, and Threads_lock is never released
1819     // we will block here forever.
1820     // Here we can be doing a jump from a safe state to an unsafe state without
1821     // proper transition, but it happens after the final safepoint has begun.
1822     set_thread_state(_thread_in_vm);
1823     Threads_lock->lock();
1824     ShouldNotReachHere();
1825   }
1826 }
1827 
1828 
1829 // Remove this ifdef when C1 is ported to the compiler interface.
1830 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1831 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1832 
1833 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1834                        Thread() {
1835   initialize();
1836   _jni_attach_state = _not_attaching_via_jni;
1837   set_entry_point(entry_point);
1838   // Create the native thread itself.
1839   // %note runtime_23
1840   os::ThreadType thr_type = os::java_thread;
1841   thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1842                                                      os::java_thread;
1843   os::create_thread(this, thr_type, stack_sz);
1844   // The _osthread may be NULL here because we ran out of memory (too many threads active).
1845   // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1846   // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1847   // the exception consists of creating the exception object & initializing it, initialization
1848   // will leave the VM via a JavaCall and then all locks must be unlocked).
1849   //
1850   // The thread is still suspended when we reach here. Thread must be explicit started
1851   // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1852   // by calling Threads:add. The reason why this is not done here, is because the thread
1853   // object must be fully initialized (take a look at JVM_Start)
1854 }
1855 
1856 JavaThread::~JavaThread() {
1857 
1858   // JSR166 -- return the parker to the free list
1859   Parker::Release(_parker);
1860   _parker = NULL;
1861 
1862   // Return the sleep event to the free list
1863   ParkEvent::Release(_SleepEvent);
1864   _SleepEvent = NULL;
1865 
1866   // Free any remaining  previous UnrollBlock
1867   vframeArray* old_array = vframe_array_last();
1868 
1869   if (old_array != NULL) {
1870     Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1871     old_array->set_unroll_block(NULL);
1872     delete old_info;
1873     delete old_array;
1874   }
1875 
1876   GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1877   if (deferred != NULL) {
1878     // This can only happen if thread is destroyed before deoptimization occurs.
1879     assert(deferred->length() != 0, "empty array!");
1880     do {
1881       jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1882       deferred->remove_at(0);
1883       // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1884       delete dlv;
1885     } while (deferred->length() != 0);
1886     delete deferred;
1887   }
1888 
1889   // All Java related clean up happens in exit
1890   ThreadSafepointState::destroy(this);
1891   if (_thread_stat != NULL) delete _thread_stat;
1892 
1893 #if INCLUDE_JVMCI
1894   if (JVMCICounterSize > 0) {
1895     if (jvmci_counters_include(this)) {
1896       for (int i = 0; i < JVMCICounterSize; i++) {
1897         _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1898       }
1899     }
1900     FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1901   }
1902 #endif // INCLUDE_JVMCI
1903 }
1904 
1905 
1906 // First JavaThread specific code executed by a new Java thread.
1907 void JavaThread::pre_run() {
1908   // empty - see comments in run()
1909 }
1910 
1911 // The main routine called by a new Java thread. This isn't overridden
1912 // by subclasses, instead different subclasses define a different "entry_point"
1913 // which defines the actual logic for that kind of thread.
1914 void JavaThread::run() {
1915   // initialize thread-local alloc buffer related fields
1916   this->initialize_tlab();
1917 
1918   // Used to test validity of stack trace backs.
1919   // This can't be moved into pre_run() else we invalidate
1920   // the requirement that thread_main_inner is lower on
1921   // the stack. Consequently all the initialization logic
1922   // stays here in run() rather than pre_run().
1923   this->record_base_of_stack_pointer();
1924 
1925   this->create_stack_guard_pages();
1926 
1927   this->cache_global_variables();
1928 
1929   // Thread is now sufficiently initialized to be handled by the safepoint code as being
1930   // in the VM. Change thread state from _thread_new to _thread_in_vm
1931   ThreadStateTransition::transition(this, _thread_new, _thread_in_vm);
1932   // Before a thread is on the threads list it is always safe, so after leaving the
1933   // _thread_new we should emit a instruction barrier. The distance to modified code
1934   // from here is probably far enough, but this is consistent and safe.
1935   OrderAccess::cross_modify_fence();
1936 
1937   assert(JavaThread::current() == this, "sanity check");
1938   assert(!Thread::current()->owns_locks(), "sanity check");
1939 
1940   DTRACE_THREAD_PROBE(start, this);
1941 
1942   // This operation might block. We call that after all safepoint checks for a new thread has
1943   // been completed.
1944   this->set_active_handles(JNIHandleBlock::allocate_block());
1945 
1946   if (JvmtiExport::should_post_thread_life()) {
1947     JvmtiExport::post_thread_start(this);
1948 
1949   }
1950 
1951   // We call another function to do the rest so we are sure that the stack addresses used
1952   // from there will be lower than the stack base just computed.
1953   thread_main_inner();
1954 }
1955 
1956 void JavaThread::thread_main_inner() {
1957   assert(JavaThread::current() == this, "sanity check");
1958   assert(this->threadObj() != NULL, "just checking");
1959 
1960   // Execute thread entry point unless this thread has a pending exception
1961   // or has been stopped before starting.
1962   // Note: Due to JVM_StopThread we can have pending exceptions already!
1963   if (!this->has_pending_exception() &&
1964       !java_lang_Thread::is_stillborn(this->threadObj())) {
1965     {
1966       ResourceMark rm(this);
1967       this->set_native_thread_name(this->get_thread_name());
1968     }
1969     HandleMark hm(this);
1970     this->entry_point()(this, this);
1971   }
1972 
1973   DTRACE_THREAD_PROBE(stop, this);
1974 
1975   // Cleanup is handled in post_run()
1976 }
1977 
1978 // Shared teardown for all JavaThreads
1979 void JavaThread::post_run() {
1980   this->exit(false);
1981   // Defer deletion to here to ensure 'this' is still referenceable in call_run
1982   // for any shared tear-down.
1983   this->smr_delete();
1984 }
1985 
1986 static void ensure_join(JavaThread* thread) {
1987   // We do not need to grab the Threads_lock, since we are operating on ourself.
1988   Handle threadObj(thread, thread->threadObj());
1989   assert(threadObj.not_null(), "java thread object must exist");
1990   ObjectLocker lock(threadObj, thread);
1991   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1992   thread->clear_pending_exception();
1993   // Thread is exiting. So set thread_status field in  java.lang.Thread class to TERMINATED.
1994   java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1995   // Clear the native thread instance - this makes isAlive return false and allows the join()
1996   // to complete once we've done the notify_all below
1997   java_lang_Thread::set_thread(threadObj(), NULL);
1998   lock.notify_all(thread);
1999   // Ignore pending exception (ThreadDeath), since we are exiting anyway
2000   thread->clear_pending_exception();
2001 }
2002 
2003 static bool is_daemon(oop threadObj) {
2004   return (threadObj != NULL && java_lang_Thread::is_daemon(threadObj));
2005 }
2006 
2007 // For any new cleanup additions, please check to see if they need to be applied to
2008 // cleanup_failed_attach_current_thread as well.
2009 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
2010   assert(this == JavaThread::current(), "thread consistency check");
2011 
2012   elapsedTimer _timer_exit_phase1;
2013   elapsedTimer _timer_exit_phase2;
2014   elapsedTimer _timer_exit_phase3;
2015   elapsedTimer _timer_exit_phase4;
2016 
2017   if (log_is_enabled(Debug, os, thread, timer)) {
2018     _timer_exit_phase1.start();
2019   }
2020 
2021   HandleMark hm(this);
2022   Handle uncaught_exception(this, this->pending_exception());
2023   this->clear_pending_exception();
2024   Handle threadObj(this, this->threadObj());
2025   assert(threadObj.not_null(), "Java thread object should be created");
2026 
2027   // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
2028   {
2029     EXCEPTION_MARK;
2030 
2031     CLEAR_PENDING_EXCEPTION;
2032   }
2033   if (!destroy_vm) {
2034     if (uncaught_exception.not_null()) {
2035       EXCEPTION_MARK;
2036       // Call method Thread.dispatchUncaughtException().
2037       Klass* thread_klass = SystemDictionary::Thread_klass();
2038       JavaValue result(T_VOID);
2039       JavaCalls::call_virtual(&result,
2040                               threadObj, thread_klass,
2041                               vmSymbols::dispatchUncaughtException_name(),
2042                               vmSymbols::throwable_void_signature(),
2043                               uncaught_exception,
2044                               THREAD);
2045       if (HAS_PENDING_EXCEPTION) {
2046         ResourceMark rm(this);
2047         jio_fprintf(defaultStream::error_stream(),
2048                     "\nException: %s thrown from the UncaughtExceptionHandler"
2049                     " in thread \"%s\"\n",
2050                     pending_exception()->klass()->external_name(),
2051                     get_thread_name());
2052         CLEAR_PENDING_EXCEPTION;
2053       }
2054     }
2055     JFR_ONLY(Jfr::on_java_thread_dismantle(this);)
2056 
2057     // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
2058     // the execution of the method. If that is not enough, then we don't really care. Thread.stop
2059     // is deprecated anyhow.
2060     if (!is_Compiler_thread()) {
2061       int count = 3;
2062       while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
2063         EXCEPTION_MARK;
2064         JavaValue result(T_VOID);
2065         Klass* thread_klass = SystemDictionary::Thread_klass();
2066         JavaCalls::call_virtual(&result,
2067                                 threadObj, thread_klass,
2068                                 vmSymbols::exit_method_name(),
2069                                 vmSymbols::void_method_signature(),
2070                                 THREAD);
2071         CLEAR_PENDING_EXCEPTION;
2072       }
2073     }
2074     // notify JVMTI
2075     if (JvmtiExport::should_post_thread_life()) {
2076       JvmtiExport::post_thread_end(this);
2077     }
2078 
2079     // We have notified the agents that we are exiting, before we go on,
2080     // we must check for a pending external suspend request and honor it
2081     // in order to not surprise the thread that made the suspend request.
2082     while (true) {
2083       {
2084         MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2085         if (!is_external_suspend()) {
2086           set_terminated(_thread_exiting);
2087           ThreadService::current_thread_exiting(this, is_daemon(threadObj()));
2088           break;
2089         }
2090         // Implied else:
2091         // Things get a little tricky here. We have a pending external
2092         // suspend request, but we are holding the SR_lock so we
2093         // can't just self-suspend. So we temporarily drop the lock
2094         // and then self-suspend.
2095       }
2096 
2097       ThreadBlockInVM tbivm(this);
2098       java_suspend_self();
2099 
2100       // We're done with this suspend request, but we have to loop around
2101       // and check again. Eventually we will get SR_lock without a pending
2102       // external suspend request and will be able to mark ourselves as
2103       // exiting.
2104     }
2105     // no more external suspends are allowed at this point
2106   } else {
2107     assert(!is_terminated() && !is_exiting(), "must not be exiting");
2108     // before_exit() has already posted JVMTI THREAD_END events
2109   }
2110 
2111   if (log_is_enabled(Debug, os, thread, timer)) {
2112     _timer_exit_phase1.stop();
2113     _timer_exit_phase2.start();
2114   }
2115 
2116   // Capture daemon status before the thread is marked as terminated.
2117   bool daemon = is_daemon(threadObj());
2118 
2119   // Notify waiters on thread object. This has to be done after exit() is called
2120   // on the thread (if the thread is the last thread in a daemon ThreadGroup the
2121   // group should have the destroyed bit set before waiters are notified).
2122   ensure_join(this);
2123   assert(!this->has_pending_exception(), "ensure_join should have cleared");
2124 
2125   if (log_is_enabled(Debug, os, thread, timer)) {
2126     _timer_exit_phase2.stop();
2127     _timer_exit_phase3.start();
2128   }
2129   // 6282335 JNI DetachCurrentThread spec states that all Java monitors
2130   // held by this thread must be released. The spec does not distinguish
2131   // between JNI-acquired and regular Java monitors. We can only see
2132   // regular Java monitors here if monitor enter-exit matching is broken.
2133   //
2134   // ensure_join() ignores IllegalThreadStateExceptions, and so does
2135   // ObjectSynchronizer::release_monitors_owned_by_thread().
2136   if (exit_type == jni_detach) {
2137     // Sanity check even though JNI DetachCurrentThread() would have
2138     // returned JNI_ERR if there was a Java frame. JavaThread exit
2139     // should be done executing Java code by the time we get here.
2140     assert(!this->has_last_Java_frame(),
2141            "should not have a Java frame when detaching or exiting");
2142     ObjectSynchronizer::release_monitors_owned_by_thread(this);
2143     assert(!this->has_pending_exception(), "release_monitors should have cleared");
2144   }
2145 
2146   // These things needs to be done while we are still a Java Thread. Make sure that thread
2147   // is in a consistent state, in case GC happens
2148   JFR_ONLY(Jfr::on_thread_exit(this);)
2149 
2150   if (active_handles() != NULL) {
2151     JNIHandleBlock* block = active_handles();
2152     set_active_handles(NULL);
2153     JNIHandleBlock::release_block(block);
2154   }
2155 
2156   if (free_handle_block() != NULL) {
2157     JNIHandleBlock* block = free_handle_block();
2158     set_free_handle_block(NULL);
2159     JNIHandleBlock::release_block(block);
2160   }
2161 
2162   // These have to be removed while this is still a valid thread.
2163   remove_stack_guard_pages();
2164 
2165   if (UseTLAB) {
2166     tlab().retire();
2167   }
2168 
2169   if (JvmtiEnv::environments_might_exist()) {
2170     JvmtiExport::cleanup_thread(this);
2171   }
2172 
2173   // We must flush any deferred card marks and other various GC barrier
2174   // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer)
2175   // before removing a thread from the list of active threads.
2176   BarrierSet::barrier_set()->on_thread_detach(this);
2177 
2178   log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
2179     exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
2180     os::current_thread_id());
2181 
2182   if (log_is_enabled(Debug, os, thread, timer)) {
2183     _timer_exit_phase3.stop();
2184     _timer_exit_phase4.start();
2185   }
2186   // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
2187   Threads::remove(this, daemon);
2188 
2189   if (log_is_enabled(Debug, os, thread, timer)) {
2190     _timer_exit_phase4.stop();
2191     ResourceMark rm(this);
2192     log_debug(os, thread, timer)("name='%s'"
2193                                  ", exit-phase1=" JLONG_FORMAT
2194                                  ", exit-phase2=" JLONG_FORMAT
2195                                  ", exit-phase3=" JLONG_FORMAT
2196                                  ", exit-phase4=" JLONG_FORMAT,
2197                                  get_thread_name(),
2198                                  _timer_exit_phase1.milliseconds(),
2199                                  _timer_exit_phase2.milliseconds(),
2200                                  _timer_exit_phase3.milliseconds(),
2201                                  _timer_exit_phase4.milliseconds());
2202   }
2203 }
2204 
2205 void JavaThread::cleanup_failed_attach_current_thread(bool is_daemon) {
2206   if (active_handles() != NULL) {
2207     JNIHandleBlock* block = active_handles();
2208     set_active_handles(NULL);
2209     JNIHandleBlock::release_block(block);
2210   }
2211 
2212   if (free_handle_block() != NULL) {
2213     JNIHandleBlock* block = free_handle_block();
2214     set_free_handle_block(NULL);
2215     JNIHandleBlock::release_block(block);
2216   }
2217 
2218   // These have to be removed while this is still a valid thread.
2219   remove_stack_guard_pages();
2220 
2221   if (UseTLAB) {
2222     tlab().retire();
2223   }
2224 
2225   BarrierSet::barrier_set()->on_thread_detach(this);
2226 
2227   Threads::remove(this, is_daemon);
2228   this->smr_delete();
2229 }
2230 
2231 JavaThread* JavaThread::active() {
2232   Thread* thread = Thread::current();
2233   if (thread->is_Java_thread()) {
2234     return (JavaThread*) thread;
2235   } else {
2236     assert(thread->is_VM_thread(), "this must be a vm thread");
2237     VM_Operation* op = ((VMThread*) thread)->vm_operation();
2238     JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2239     assert(ret->is_Java_thread(), "must be a Java thread");
2240     return ret;
2241   }
2242 }
2243 
2244 bool JavaThread::is_lock_owned(address adr) const {
2245   if (Thread::is_lock_owned(adr)) return true;
2246 
2247   for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2248     if (chunk->contains(adr)) return true;
2249   }
2250 
2251   return false;
2252 }
2253 
2254 
2255 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2256   chunk->set_next(monitor_chunks());
2257   set_monitor_chunks(chunk);
2258 }
2259 
2260 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2261   guarantee(monitor_chunks() != NULL, "must be non empty");
2262   if (monitor_chunks() == chunk) {
2263     set_monitor_chunks(chunk->next());
2264   } else {
2265     MonitorChunk* prev = monitor_chunks();
2266     while (prev->next() != chunk) prev = prev->next();
2267     prev->set_next(chunk->next());
2268   }
2269 }
2270 
2271 // JVM support.
2272 
2273 // Note: this function shouldn't block if it's called in
2274 // _thread_in_native_trans state (such as from
2275 // check_special_condition_for_native_trans()).
2276 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2277 
2278   if (has_last_Java_frame() && has_async_condition()) {
2279     // If we are at a polling page safepoint (not a poll return)
2280     // then we must defer async exception because live registers
2281     // will be clobbered by the exception path. Poll return is
2282     // ok because the call we a returning from already collides
2283     // with exception handling registers and so there is no issue.
2284     // (The exception handling path kills call result registers but
2285     //  this is ok since the exception kills the result anyway).
2286 
2287     if (is_at_poll_safepoint()) {
2288       // if the code we are returning to has deoptimized we must defer
2289       // the exception otherwise live registers get clobbered on the
2290       // exception path before deoptimization is able to retrieve them.
2291       //
2292       RegisterMap map(this, false);
2293       frame caller_fr = last_frame().sender(&map);
2294       assert(caller_fr.is_compiled_frame(), "what?");
2295       if (caller_fr.is_deoptimized_frame()) {
2296         log_info(exceptions)("deferred async exception at compiled safepoint");
2297         return;
2298       }
2299     }
2300   }
2301 
2302   JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2303   if (condition == _no_async_condition) {
2304     // Conditions have changed since has_special_runtime_exit_condition()
2305     // was called:
2306     // - if we were here only because of an external suspend request,
2307     //   then that was taken care of above (or cancelled) so we are done
2308     // - if we were here because of another async request, then it has
2309     //   been cleared between the has_special_runtime_exit_condition()
2310     //   and now so again we are done
2311     return;
2312   }
2313 
2314   // Check for pending async. exception
2315   if (_pending_async_exception != NULL) {
2316     // Only overwrite an already pending exception, if it is not a threadDeath.
2317     if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2318 
2319       // We cannot call Exceptions::_throw(...) here because we cannot block
2320       set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2321 
2322       LogTarget(Info, exceptions) lt;
2323       if (lt.is_enabled()) {
2324         ResourceMark rm;
2325         LogStream ls(lt);
2326         ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2327           if (has_last_Java_frame()) {
2328             frame f = last_frame();
2329            ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2330           }
2331         ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2332       }
2333       _pending_async_exception = NULL;
2334       clear_has_async_exception();
2335     }
2336   }
2337 
2338   if (check_unsafe_error &&
2339       condition == _async_unsafe_access_error && !has_pending_exception()) {
2340     condition = _no_async_condition;  // done
2341     switch (thread_state()) {
2342     case _thread_in_vm: {
2343       JavaThread* THREAD = this;
2344       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2345     }
2346     case _thread_in_native: {
2347       ThreadInVMfromNative tiv(this);
2348       JavaThread* THREAD = this;
2349       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2350     }
2351     case _thread_in_Java: {
2352       ThreadInVMfromJava tiv(this);
2353       JavaThread* THREAD = this;
2354       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2355     }
2356     default:
2357       ShouldNotReachHere();
2358     }
2359   }
2360 
2361   assert(condition == _no_async_condition || has_pending_exception() ||
2362          (!check_unsafe_error && condition == _async_unsafe_access_error),
2363          "must have handled the async condition, if no exception");
2364 }
2365 
2366 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2367 
2368   // Check for pending external suspend.
2369   if (is_external_suspend_with_lock()) {
2370     frame_anchor()->make_walkable(this);
2371     java_suspend_self_with_safepoint_check();
2372   }
2373 
2374   // We might be here for reasons in addition to the self-suspend request
2375   // so check for other async requests.
2376   if (check_asyncs) {
2377     check_and_handle_async_exceptions();
2378   }
2379 
2380   JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);)
2381 }
2382 
2383 void JavaThread::send_thread_stop(oop java_throwable)  {
2384   assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2385   assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2386   assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2387 
2388   // Do not throw asynchronous exceptions against the compiler thread
2389   // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2390   if (!can_call_java()) return;
2391 
2392   {
2393     // Actually throw the Throwable against the target Thread - however
2394     // only if there is no thread death exception installed already.
2395     if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2396       // If the topmost frame is a runtime stub, then we are calling into
2397       // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2398       // must deoptimize the caller before continuing, as the compiled  exception handler table
2399       // may not be valid
2400       if (has_last_Java_frame()) {
2401         frame f = last_frame();
2402         if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2403           // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2404           RegisterMap reg_map(this, UseBiasedLocking);
2405           frame compiled_frame = f.sender(&reg_map);
2406           if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2407             Deoptimization::deoptimize(this, compiled_frame, &reg_map);
2408           }
2409         }
2410       }
2411 
2412       // Set async. pending exception in thread.
2413       set_pending_async_exception(java_throwable);
2414 
2415       if (log_is_enabled(Info, exceptions)) {
2416          ResourceMark rm;
2417         log_info(exceptions)("Pending Async. exception installed of type: %s",
2418                              InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2419       }
2420       // for AbortVMOnException flag
2421       Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2422     }
2423   }
2424 
2425 
2426   // Interrupt thread so it will wake up from a potential wait()/sleep()/park()
2427   java_lang_Thread::set_interrupted(threadObj(), true);
2428   this->interrupt();
2429 }
2430 
2431 // External suspension mechanism.
2432 //
2433 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2434 // to any VM_locks and it is at a transition
2435 // Self-suspension will happen on the transition out of the vm.
2436 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2437 //
2438 // Guarantees on return:
2439 //   + Target thread will not execute any new bytecode (that's why we need to
2440 //     force a safepoint)
2441 //   + Target thread will not enter any new monitors
2442 //
2443 void JavaThread::java_suspend() {
2444   ThreadsListHandle tlh;
2445   if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) {
2446     return;
2447   }
2448 
2449   { MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2450     if (!is_external_suspend()) {
2451       // a racing resume has cancelled us; bail out now
2452       return;
2453     }
2454 
2455     // suspend is done
2456     uint32_t debug_bits = 0;
2457     // Warning: is_ext_suspend_completed() may temporarily drop the
2458     // SR_lock to allow the thread to reach a stable thread state if
2459     // it is currently in a transient thread state.
2460     if (is_ext_suspend_completed(false /* !called_by_wait */,
2461                                  SuspendRetryDelay, &debug_bits)) {
2462       return;
2463     }
2464   }
2465 
2466   if (Thread::current() == this) {
2467     // Safely self-suspend.
2468     // If we don't do this explicitly it will implicitly happen
2469     // before we transition back to Java, and on some other thread-state
2470     // transition paths, but not as we exit a JVM TI SuspendThread call.
2471     // As SuspendThread(current) must not return (until resumed) we must
2472     // self-suspend here.
2473     ThreadBlockInVM tbivm(this);
2474     java_suspend_self();
2475   } else {
2476     VM_ThreadSuspend vm_suspend;
2477     VMThread::execute(&vm_suspend);
2478   }
2479 }
2480 
2481 // Part II of external suspension.
2482 // A JavaThread self suspends when it detects a pending external suspend
2483 // request. This is usually on transitions. It is also done in places
2484 // where continuing to the next transition would surprise the caller,
2485 // e.g., monitor entry.
2486 //
2487 // Returns the number of times that the thread self-suspended.
2488 //
2489 // Note: DO NOT call java_suspend_self() when you just want to block current
2490 //       thread. java_suspend_self() is the second stage of cooperative
2491 //       suspension for external suspend requests and should only be used
2492 //       to complete an external suspend request.
2493 //
2494 int JavaThread::java_suspend_self() {
2495   assert(thread_state() == _thread_blocked, "wrong state for java_suspend_self()");
2496   int ret = 0;
2497 
2498   // we are in the process of exiting so don't suspend
2499   if (is_exiting()) {
2500     clear_external_suspend();
2501     return ret;
2502   }
2503 
2504   assert(_anchor.walkable() ||
2505          (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2506          "must have walkable stack");
2507 
2508   MonitorLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2509 
2510   assert(!this->is_ext_suspended(),
2511          "a thread trying to self-suspend should not already be suspended");
2512 
2513   if (this->is_suspend_equivalent()) {
2514     // If we are self-suspending as a result of the lifting of a
2515     // suspend equivalent condition, then the suspend_equivalent
2516     // flag is not cleared until we set the ext_suspended flag so
2517     // that wait_for_ext_suspend_completion() returns consistent
2518     // results.
2519     this->clear_suspend_equivalent();
2520   }
2521 
2522   // A racing resume may have cancelled us before we grabbed SR_lock
2523   // above. Or another external suspend request could be waiting for us
2524   // by the time we return from SR_lock()->wait(). The thread
2525   // that requested the suspension may already be trying to walk our
2526   // stack and if we return now, we can change the stack out from under
2527   // it. This would be a "bad thing (TM)" and cause the stack walker
2528   // to crash. We stay self-suspended until there are no more pending
2529   // external suspend requests.
2530   while (is_external_suspend()) {
2531     ret++;
2532     this->set_ext_suspended();
2533 
2534     // _ext_suspended flag is cleared by java_resume()
2535     while (is_ext_suspended()) {
2536       ml.wait();
2537     }
2538   }
2539   return ret;
2540 }
2541 
2542 // Helper routine to set up the correct thread state before calling java_suspend_self.
2543 // This is called when regular thread-state transition helpers can't be used because
2544 // we can be in various states, in particular _thread_in_native_trans.
2545 // Because this thread is external suspended the safepoint code will count it as at
2546 // a safepoint, regardless of what its actual current thread-state is. But
2547 // is_ext_suspend_completed() may be waiting to see a thread transition from
2548 // _thread_in_native_trans to _thread_blocked. So we set the thread state directly
2549 // to _thread_blocked. The problem with setting thread state directly is that a
2550 // safepoint could happen just after java_suspend_self() returns after being resumed,
2551 // and the VM thread will see the _thread_blocked state. So we must check for a safepoint
2552 // after restoring the state to make sure we won't leave while a safepoint is in progress.
2553 // However, not all initial-states are allowed when performing a safepoint check, as we
2554 // should never be blocking at a safepoint whilst in those states. Of these 'bad' states
2555 // only _thread_in_native is possible when executing this code (based on our two callers).
2556 // A thread that is _thread_in_native is already safepoint-safe and so it doesn't matter
2557 // whether the VMThread sees the _thread_blocked state, or the _thread_in_native state,
2558 // and so we don't need the explicit safepoint check.
2559 
2560 void JavaThread::java_suspend_self_with_safepoint_check() {
2561   assert(this == Thread::current(), "invariant");
2562   JavaThreadState state = thread_state();
2563   set_thread_state(_thread_blocked);
2564   java_suspend_self();
2565   set_thread_state_fence(state);
2566   // Since we are not using a regular thread-state transition helper here,
2567   // we must manually emit the instruction barrier after leaving a safe state.
2568   OrderAccess::cross_modify_fence();
2569   if (state != _thread_in_native) {
2570     SafepointMechanism::block_if_requested(this);
2571   }
2572 }
2573 
2574 #ifdef ASSERT
2575 // Verify the JavaThread has not yet been published in the Threads::list, and
2576 // hence doesn't need protection from concurrent access at this stage.
2577 void JavaThread::verify_not_published() {
2578   // Cannot create a ThreadsListHandle here and check !tlh.includes(this)
2579   // since an unpublished JavaThread doesn't participate in the
2580   // Thread-SMR protocol for keeping a ThreadsList alive.
2581   assert(!on_thread_list(), "JavaThread shouldn't have been published yet!");
2582 }
2583 #endif
2584 
2585 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2586 // progress or when _suspend_flags is non-zero.
2587 // Current thread needs to self-suspend if there is a suspend request and/or
2588 // block if a safepoint is in progress.
2589 // Async exception ISN'T checked.
2590 // Note only the ThreadInVMfromNative transition can call this function
2591 // directly and when thread state is _thread_in_native_trans
2592 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2593   assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2594 
2595   assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2596 
2597   if (thread->is_external_suspend()) {
2598     thread->java_suspend_self_with_safepoint_check();
2599   } else {
2600     SafepointMechanism::block_if_requested(thread);
2601   }
2602 
2603   JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(thread);)
2604 }
2605 
2606 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2607 // progress or when _suspend_flags is non-zero.
2608 // Current thread needs to self-suspend if there is a suspend request and/or
2609 // block if a safepoint is in progress.
2610 // Also check for pending async exception (not including unsafe access error).
2611 // Note only the native==>VM/Java barriers can call this function and when
2612 // thread state is _thread_in_native_trans.
2613 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2614   check_safepoint_and_suspend_for_native_trans(thread);
2615 
2616   if (thread->has_async_exception()) {
2617     // We are in _thread_in_native_trans state, don't handle unsafe
2618     // access error since that may block.
2619     thread->check_and_handle_async_exceptions(false);
2620   }
2621 }
2622 
2623 // This is a variant of the normal
2624 // check_special_condition_for_native_trans with slightly different
2625 // semantics for use by critical native wrappers.  It does all the
2626 // normal checks but also performs the transition back into
2627 // thread_in_Java state.  This is required so that critical natives
2628 // can potentially block and perform a GC if they are the last thread
2629 // exiting the GCLocker.
2630 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2631   check_special_condition_for_native_trans(thread);
2632 
2633   // Finish the transition
2634   thread->set_thread_state(_thread_in_Java);
2635 
2636   if (thread->do_critical_native_unlock()) {
2637     ThreadInVMfromJavaNoAsyncException tiv(thread);
2638     GCLocker::unlock_critical(thread);
2639     thread->clear_critical_native_unlock();
2640   }
2641 }
2642 
2643 // We need to guarantee the Threads_lock here, since resumes are not
2644 // allowed during safepoint synchronization
2645 // Can only resume from an external suspension
2646 void JavaThread::java_resume() {
2647   assert_locked_or_safepoint(Threads_lock);
2648 
2649   // Sanity check: thread is gone, has started exiting or the thread
2650   // was not externally suspended.
2651   ThreadsListHandle tlh;
2652   if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) {
2653     return;
2654   }
2655 
2656   MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2657 
2658   clear_external_suspend();
2659 
2660   if (is_ext_suspended()) {
2661     clear_ext_suspended();
2662     SR_lock()->notify_all();
2663   }
2664 }
2665 
2666 size_t JavaThread::_stack_red_zone_size = 0;
2667 size_t JavaThread::_stack_yellow_zone_size = 0;
2668 size_t JavaThread::_stack_reserved_zone_size = 0;
2669 size_t JavaThread::_stack_shadow_zone_size = 0;
2670 
2671 void JavaThread::create_stack_guard_pages() {
2672   if (!os::uses_stack_guard_pages() ||
2673       _stack_guard_state != stack_guard_unused ||
2674       (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) {
2675       log_info(os, thread)("Stack guard page creation for thread "
2676                            UINTX_FORMAT " disabled", os::current_thread_id());
2677     return;
2678   }
2679   address low_addr = stack_end();
2680   size_t len = stack_guard_zone_size();
2681 
2682   assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2683   assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2684 
2685   int must_commit = os::must_commit_stack_guard_pages();
2686   // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2687 
2688   if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2689     log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2690     return;
2691   }
2692 
2693   if (os::guard_memory((char *) low_addr, len)) {
2694     _stack_guard_state = stack_guard_enabled;
2695   } else {
2696     log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2697       PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2698     if (os::uncommit_memory((char *) low_addr, len)) {
2699       log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2700     }
2701     return;
2702   }
2703 
2704   log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2705     PTR_FORMAT "-" PTR_FORMAT ".",
2706     os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2707 }
2708 
2709 void JavaThread::remove_stack_guard_pages() {
2710   assert(Thread::current() == this, "from different thread");
2711   if (_stack_guard_state == stack_guard_unused) return;
2712   address low_addr = stack_end();
2713   size_t len = stack_guard_zone_size();
2714 
2715   if (os::must_commit_stack_guard_pages()) {
2716     if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2717       _stack_guard_state = stack_guard_unused;
2718     } else {
2719       log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2720         PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2721       return;
2722     }
2723   } else {
2724     if (_stack_guard_state == stack_guard_unused) return;
2725     if (os::unguard_memory((char *) low_addr, len)) {
2726       _stack_guard_state = stack_guard_unused;
2727     } else {
2728       log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2729         PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2730       return;
2731     }
2732   }
2733 
2734   log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2735     PTR_FORMAT "-" PTR_FORMAT ".",
2736     os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2737 }
2738 
2739 void JavaThread::enable_stack_reserved_zone() {
2740   assert(_stack_guard_state == stack_guard_reserved_disabled, "inconsistent state");
2741 
2742   // The base notation is from the stack's point of view, growing downward.
2743   // We need to adjust it to work correctly with guard_memory()
2744   address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2745 
2746   guarantee(base < stack_base(),"Error calculating stack reserved zone");
2747   guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2748 
2749   if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2750     _stack_guard_state = stack_guard_enabled;
2751   } else {
2752     warning("Attempt to guard stack reserved zone failed.");
2753   }
2754   enable_register_stack_guard();
2755 }
2756 
2757 void JavaThread::disable_stack_reserved_zone() {
2758   assert(_stack_guard_state == stack_guard_enabled, "inconsistent state");
2759 
2760   // Simply return if called for a thread that does not use guard pages.
2761   if (_stack_guard_state != stack_guard_enabled) return;
2762 
2763   // The base notation is from the stack's point of view, growing downward.
2764   // We need to adjust it to work correctly with guard_memory()
2765   address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2766 
2767   if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2768     _stack_guard_state = stack_guard_reserved_disabled;
2769   } else {
2770     warning("Attempt to unguard stack reserved zone failed.");
2771   }
2772   disable_register_stack_guard();
2773 }
2774 
2775 void JavaThread::enable_stack_yellow_reserved_zone() {
2776   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2777   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2778 
2779   // The base notation is from the stacks point of view, growing downward.
2780   // We need to adjust it to work correctly with guard_memory()
2781   address base = stack_red_zone_base();
2782 
2783   guarantee(base < stack_base(), "Error calculating stack yellow zone");
2784   guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2785 
2786   if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2787     _stack_guard_state = stack_guard_enabled;
2788   } else {
2789     warning("Attempt to guard stack yellow zone failed.");
2790   }
2791   enable_register_stack_guard();
2792 }
2793 
2794 void JavaThread::disable_stack_yellow_reserved_zone() {
2795   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2796   assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2797 
2798   // Simply return if called for a thread that does not use guard pages.
2799   if (_stack_guard_state == stack_guard_unused) return;
2800 
2801   // The base notation is from the stacks point of view, growing downward.
2802   // We need to adjust it to work correctly with guard_memory()
2803   address base = stack_red_zone_base();
2804 
2805   if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2806     _stack_guard_state = stack_guard_yellow_reserved_disabled;
2807   } else {
2808     warning("Attempt to unguard stack yellow zone failed.");
2809   }
2810   disable_register_stack_guard();
2811 }
2812 
2813 void JavaThread::enable_stack_red_zone() {
2814   // The base notation is from the stacks point of view, growing downward.
2815   // We need to adjust it to work correctly with guard_memory()
2816   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2817   address base = stack_red_zone_base() - stack_red_zone_size();
2818 
2819   guarantee(base < stack_base(), "Error calculating stack red zone");
2820   guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2821 
2822   if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2823     warning("Attempt to guard stack red zone failed.");
2824   }
2825 }
2826 
2827 void JavaThread::disable_stack_red_zone() {
2828   // The base notation is from the stacks point of view, growing downward.
2829   // We need to adjust it to work correctly with guard_memory()
2830   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2831   address base = stack_red_zone_base() - stack_red_zone_size();
2832   if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2833     warning("Attempt to unguard stack red zone failed.");
2834   }
2835 }
2836 
2837 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2838   // ignore is there is no stack
2839   if (!has_last_Java_frame()) return;
2840   // traverse the stack frames. Starts from top frame.
2841   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2842     frame* fr = fst.current();
2843     f(fr, fst.register_map());
2844   }
2845 }
2846 
2847 
2848 #ifndef PRODUCT
2849 // Deoptimization
2850 // Function for testing deoptimization
2851 void JavaThread::deoptimize() {
2852   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2853   StackFrameStream fst(this, UseBiasedLocking);
2854   bool deopt = false;           // Dump stack only if a deopt actually happens.
2855   bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2856   // Iterate over all frames in the thread and deoptimize
2857   for (; !fst.is_done(); fst.next()) {
2858     if (fst.current()->can_be_deoptimized()) {
2859 
2860       if (only_at) {
2861         // Deoptimize only at particular bcis.  DeoptimizeOnlyAt
2862         // consists of comma or carriage return separated numbers so
2863         // search for the current bci in that string.
2864         address pc = fst.current()->pc();
2865         nmethod* nm =  (nmethod*) fst.current()->cb();
2866         ScopeDesc* sd = nm->scope_desc_at(pc);
2867         char buffer[8];
2868         jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2869         size_t len = strlen(buffer);
2870         const char * found = strstr(DeoptimizeOnlyAt, buffer);
2871         while (found != NULL) {
2872           if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2873               (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2874             // Check that the bci found is bracketed by terminators.
2875             break;
2876           }
2877           found = strstr(found + 1, buffer);
2878         }
2879         if (!found) {
2880           continue;
2881         }
2882       }
2883 
2884       if (DebugDeoptimization && !deopt) {
2885         deopt = true; // One-time only print before deopt
2886         tty->print_cr("[BEFORE Deoptimization]");
2887         trace_frames();
2888         trace_stack();
2889       }
2890       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2891     }
2892   }
2893 
2894   if (DebugDeoptimization && deopt) {
2895     tty->print_cr("[AFTER Deoptimization]");
2896     trace_frames();
2897   }
2898 }
2899 
2900 
2901 // Make zombies
2902 void JavaThread::make_zombies() {
2903   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2904     if (fst.current()->can_be_deoptimized()) {
2905       // it is a Java nmethod
2906       nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2907       nm->make_not_entrant();
2908     }
2909   }
2910 }
2911 #endif // PRODUCT
2912 
2913 
2914 void JavaThread::deoptimize_marked_methods() {
2915   if (!has_last_Java_frame()) return;
2916   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2917   StackFrameStream fst(this, UseBiasedLocking);
2918   for (; !fst.is_done(); fst.next()) {
2919     if (fst.current()->should_be_deoptimized()) {
2920       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2921     }
2922   }
2923 }
2924 
2925 // If the caller is a NamedThread, then remember, in the current scope,
2926 // the given JavaThread in its _processed_thread field.
2927 class RememberProcessedThread: public StackObj {
2928   NamedThread* _cur_thr;
2929  public:
2930   RememberProcessedThread(JavaThread* jthr) {
2931     Thread* thread = Thread::current();
2932     if (thread->is_Named_thread()) {
2933       _cur_thr = (NamedThread *)thread;
2934       _cur_thr->set_processed_thread(jthr);
2935     } else {
2936       _cur_thr = NULL;
2937     }
2938   }
2939 
2940   ~RememberProcessedThread() {
2941     if (_cur_thr) {
2942       _cur_thr->set_processed_thread(NULL);
2943     }
2944   }
2945 };
2946 
2947 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2948   // Verify that the deferred card marks have been flushed.
2949   assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2950 
2951   // Traverse the GCHandles
2952   Thread::oops_do(f, cf);
2953 
2954   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2955          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2956 
2957   if (has_last_Java_frame()) {
2958     // Record JavaThread to GC thread
2959     RememberProcessedThread rpt(this);
2960 
2961     // traverse the registered growable array
2962     if (_array_for_gc != NULL) {
2963       for (int index = 0; index < _array_for_gc->length(); index++) {
2964         f->do_oop(_array_for_gc->adr_at(index));
2965       }
2966     }
2967 
2968     // Traverse the monitor chunks
2969     for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2970       chunk->oops_do(f);
2971     }
2972 
2973     // Traverse the execution stack
2974     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2975       fst.current()->oops_do(f, cf, fst.register_map());
2976     }
2977   }
2978 
2979   assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2980   // If we have deferred set_locals there might be oops waiting to be
2981   // written
2982   GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2983   if (list != NULL) {
2984     for (int i = 0; i < list->length(); i++) {
2985       list->at(i)->oops_do(f);
2986     }
2987   }
2988 
2989   // Traverse instance variables at the end since the GC may be moving things
2990   // around using this function
2991   f->do_oop((oop*) &_threadObj);
2992   f->do_oop((oop*) &_vm_result);
2993   f->do_oop((oop*) &_exception_oop);
2994   f->do_oop((oop*) &_pending_async_exception);
2995 
2996   if (jvmti_thread_state() != NULL) {
2997     jvmti_thread_state()->oops_do(f);
2998   }
2999 }
3000 
3001 #ifdef ASSERT
3002 void JavaThread::verify_states_for_handshake() {
3003   // This checks that the thread has a correct frame state during a handshake.
3004   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
3005          (has_last_Java_frame() && java_call_counter() > 0),
3006          "unexpected frame info: has_last_frame=%d, java_call_counter=%d",
3007          has_last_Java_frame(), java_call_counter());
3008 }
3009 #endif
3010 
3011 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
3012   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
3013          (has_last_Java_frame() && java_call_counter() > 0),
3014          "unexpected frame info: has_last_frame=%d, java_call_counter=%d",
3015          has_last_Java_frame(), java_call_counter());
3016 
3017   if (has_last_Java_frame()) {
3018     // Traverse the execution stack
3019     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3020       fst.current()->nmethods_do(cf);
3021     }
3022   }
3023 }
3024 
3025 void JavaThread::metadata_do(MetadataClosure* f) {
3026   if (has_last_Java_frame()) {
3027     // Traverse the execution stack to call f() on the methods in the stack
3028     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3029       fst.current()->metadata_do(f);
3030     }
3031   } else if (is_Compiler_thread()) {
3032     // need to walk ciMetadata in current compile tasks to keep alive.
3033     CompilerThread* ct = (CompilerThread*)this;
3034     if (ct->env() != NULL) {
3035       ct->env()->metadata_do(f);
3036     }
3037     CompileTask* task = ct->task();
3038     if (task != NULL) {
3039       task->metadata_do(f);
3040     }
3041   }
3042 }
3043 
3044 // Printing
3045 const char* _get_thread_state_name(JavaThreadState _thread_state) {
3046   switch (_thread_state) {
3047   case _thread_uninitialized:     return "_thread_uninitialized";
3048   case _thread_new:               return "_thread_new";
3049   case _thread_new_trans:         return "_thread_new_trans";
3050   case _thread_in_native:         return "_thread_in_native";
3051   case _thread_in_native_trans:   return "_thread_in_native_trans";
3052   case _thread_in_vm:             return "_thread_in_vm";
3053   case _thread_in_vm_trans:       return "_thread_in_vm_trans";
3054   case _thread_in_Java:           return "_thread_in_Java";
3055   case _thread_in_Java_trans:     return "_thread_in_Java_trans";
3056   case _thread_blocked:           return "_thread_blocked";
3057   case _thread_blocked_trans:     return "_thread_blocked_trans";
3058   default:                        return "unknown thread state";
3059   }
3060 }
3061 
3062 #ifndef PRODUCT
3063 void JavaThread::print_thread_state_on(outputStream *st) const {
3064   st->print_cr("   JavaThread state: %s", _get_thread_state_name(_thread_state));
3065 };
3066 #endif // PRODUCT
3067 
3068 // Called by Threads::print() for VM_PrintThreads operation
3069 void JavaThread::print_on(outputStream *st, bool print_extended_info) const {
3070   st->print_raw("\"");
3071   st->print_raw(get_thread_name());
3072   st->print_raw("\" ");
3073   oop thread_oop = threadObj();
3074   if (thread_oop != NULL) {
3075     st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
3076     if (java_lang_Thread::is_daemon(thread_oop))  st->print("daemon ");
3077     st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
3078   }
3079   Thread::print_on(st, print_extended_info);
3080   // print guess for valid stack memory region (assume 4K pages); helps lock debugging
3081   st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
3082   if (thread_oop != NULL) {
3083     st->print_cr("   java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
3084   }
3085 #ifndef PRODUCT
3086   _safepoint_state->print_on(st);
3087 #endif // PRODUCT
3088   if (is_Compiler_thread()) {
3089     CompileTask *task = ((CompilerThread*)this)->task();
3090     if (task != NULL) {
3091       st->print("   Compiling: ");
3092       task->print(st, NULL, true, false);
3093     } else {
3094       st->print("   No compile task");
3095     }
3096     st->cr();
3097   }
3098 }
3099 
3100 void JavaThread::print() const { print_on(tty); }
3101 
3102 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
3103   st->print("%s", get_thread_name_string(buf, buflen));
3104 }
3105 
3106 // Called by fatal error handler. The difference between this and
3107 // JavaThread::print() is that we can't grab lock or allocate memory.
3108 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
3109   st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
3110   oop thread_obj = threadObj();
3111   if (thread_obj != NULL) {
3112     if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
3113   }
3114   st->print(" [");
3115   st->print("%s", _get_thread_state_name(_thread_state));
3116   if (osthread()) {
3117     st->print(", id=%d", osthread()->thread_id());
3118   }
3119   st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
3120             p2i(stack_end()), p2i(stack_base()));
3121   st->print("]");
3122 
3123   ThreadsSMRSupport::print_info_on(this, st);
3124   return;
3125 }
3126 
3127 // Verification
3128 
3129 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
3130 
3131 void JavaThread::verify() {
3132   // Verify oops in the thread.
3133   oops_do(&VerifyOopClosure::verify_oop, NULL);
3134 
3135   // Verify the stack frames.
3136   frames_do(frame_verify);
3137 }
3138 
3139 // CR 6300358 (sub-CR 2137150)
3140 // Most callers of this method assume that it can't return NULL but a
3141 // thread may not have a name whilst it is in the process of attaching to
3142 // the VM - see CR 6412693, and there are places where a JavaThread can be
3143 // seen prior to having it's threadObj set (eg JNI attaching threads and
3144 // if vm exit occurs during initialization). These cases can all be accounted
3145 // for such that this method never returns NULL.
3146 const char* JavaThread::get_thread_name() const {
3147 #ifdef ASSERT
3148   // early safepoints can hit while current thread does not yet have TLS
3149   if (!SafepointSynchronize::is_at_safepoint()) {
3150     Thread *cur = Thread::current();
3151     if (!(cur->is_Java_thread() && cur == this)) {
3152       // Current JavaThreads are allowed to get their own name without
3153       // the Threads_lock.
3154       assert_locked_or_safepoint(Threads_lock);
3155     }
3156   }
3157 #endif // ASSERT
3158   return get_thread_name_string();
3159 }
3160 
3161 // Returns a non-NULL representation of this thread's name, or a suitable
3162 // descriptive string if there is no set name
3163 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3164   const char* name_str;
3165   oop thread_obj = threadObj();
3166   if (thread_obj != NULL) {
3167     oop name = java_lang_Thread::name(thread_obj);
3168     if (name != NULL) {
3169       if (buf == NULL) {
3170         name_str = java_lang_String::as_utf8_string(name);
3171       } else {
3172         name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3173       }
3174     } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3175       name_str = "<no-name - thread is attaching>";
3176     } else {
3177       name_str = Thread::name();
3178     }
3179   } else {
3180     name_str = Thread::name();
3181   }
3182   assert(name_str != NULL, "unexpected NULL thread name");
3183   return name_str;
3184 }
3185 
3186 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3187 
3188   assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3189   assert(NoPriority <= prio && prio <= MaxPriority, "sanity check");
3190   // Link Java Thread object <-> C++ Thread
3191 
3192   // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3193   // and put it into a new Handle.  The Handle "thread_oop" can then
3194   // be used to pass the C++ thread object to other methods.
3195 
3196   // Set the Java level thread object (jthread) field of the
3197   // new thread (a JavaThread *) to C++ thread object using the
3198   // "thread_oop" handle.
3199 
3200   // Set the thread field (a JavaThread *) of the
3201   // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3202 
3203   Handle thread_oop(Thread::current(),
3204                     JNIHandles::resolve_non_null(jni_thread));
3205   assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3206          "must be initialized");
3207   set_threadObj(thread_oop());
3208   java_lang_Thread::set_thread(thread_oop(), this);
3209 
3210   if (prio == NoPriority) {
3211     prio = java_lang_Thread::priority(thread_oop());
3212     assert(prio != NoPriority, "A valid priority should be present");
3213   }
3214 
3215   // Push the Java priority down to the native thread; needs Threads_lock
3216   Thread::set_priority(this, prio);
3217 
3218   // Add the new thread to the Threads list and set it in motion.
3219   // We must have threads lock in order to call Threads::add.
3220   // It is crucial that we do not block before the thread is
3221   // added to the Threads list for if a GC happens, then the java_thread oop
3222   // will not be visited by GC.
3223   Threads::add(this);
3224 }
3225 
3226 oop JavaThread::current_park_blocker() {
3227   // Support for JSR-166 locks
3228   oop thread_oop = threadObj();
3229   if (thread_oop != NULL) {
3230     return java_lang_Thread::park_blocker(thread_oop);
3231   }
3232   return NULL;
3233 }
3234 
3235 
3236 void JavaThread::print_stack_on(outputStream* st) {
3237   if (!has_last_Java_frame()) return;
3238   ResourceMark rm;
3239   HandleMark   hm;
3240 
3241   RegisterMap reg_map(this);
3242   vframe* start_vf = last_java_vframe(&reg_map);
3243   int count = 0;
3244   for (vframe* f = start_vf; f != NULL; f = f->sender()) {
3245     if (f->is_java_frame()) {
3246       javaVFrame* jvf = javaVFrame::cast(f);
3247       java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3248 
3249       // Print out lock information
3250       if (JavaMonitorsInStackTrace) {
3251         jvf->print_lock_info_on(st, count);
3252       }
3253     } else {
3254       // Ignore non-Java frames
3255     }
3256 
3257     // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
3258     count++;
3259     if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
3260   }
3261 }
3262 
3263 
3264 // JVMTI PopFrame support
3265 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3266   assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3267   if (in_bytes(size_in_bytes) != 0) {
3268     _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3269     _popframe_preserved_args_size = in_bytes(size_in_bytes);
3270     Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3271   }
3272 }
3273 
3274 void* JavaThread::popframe_preserved_args() {
3275   return _popframe_preserved_args;
3276 }
3277 
3278 ByteSize JavaThread::popframe_preserved_args_size() {
3279   return in_ByteSize(_popframe_preserved_args_size);
3280 }
3281 
3282 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3283   int sz = in_bytes(popframe_preserved_args_size());
3284   assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3285   return in_WordSize(sz / wordSize);
3286 }
3287 
3288 void JavaThread::popframe_free_preserved_args() {
3289   assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3290   FREE_C_HEAP_ARRAY(char, (char*)_popframe_preserved_args);
3291   _popframe_preserved_args = NULL;
3292   _popframe_preserved_args_size = 0;
3293 }
3294 
3295 #ifndef PRODUCT
3296 
3297 void JavaThread::trace_frames() {
3298   tty->print_cr("[Describe stack]");
3299   int frame_no = 1;
3300   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3301     tty->print("  %d. ", frame_no++);
3302     fst.current()->print_value_on(tty, this);
3303     tty->cr();
3304   }
3305 }
3306 
3307 class PrintAndVerifyOopClosure: public OopClosure {
3308  protected:
3309   template <class T> inline void do_oop_work(T* p) {
3310     oop obj = RawAccess<>::oop_load(p);
3311     if (obj == NULL) return;
3312     tty->print(INTPTR_FORMAT ": ", p2i(p));
3313     if (oopDesc::is_oop_or_null(obj)) {
3314       if (obj->is_objArray()) {
3315         tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3316       } else {
3317         obj->print();
3318       }
3319     } else {
3320       tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3321     }
3322     tty->cr();
3323   }
3324  public:
3325   virtual void do_oop(oop* p) { do_oop_work(p); }
3326   virtual void do_oop(narrowOop* p)  { do_oop_work(p); }
3327 };
3328 
3329 #ifdef ASSERT
3330 // Print or validate the layout of stack frames
3331 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3332   ResourceMark rm;
3333   PRESERVE_EXCEPTION_MARK;
3334   FrameValues values;
3335   int frame_no = 0;
3336   for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3337     fst.current()->describe(values, ++frame_no);
3338     if (depth == frame_no) break;
3339   }
3340   if (validate_only) {
3341     values.validate();
3342   } else {
3343     tty->print_cr("[Describe stack layout]");
3344     values.print(this);
3345   }
3346 }
3347 #endif
3348 
3349 void JavaThread::trace_stack_from(vframe* start_vf) {
3350   ResourceMark rm;
3351   int vframe_no = 1;
3352   for (vframe* f = start_vf; f; f = f->sender()) {
3353     if (f->is_java_frame()) {
3354       javaVFrame::cast(f)->print_activation(vframe_no++);
3355     } else {
3356       f->print();
3357     }
3358     if (vframe_no > StackPrintLimit) {
3359       tty->print_cr("...<more frames>...");
3360       return;
3361     }
3362   }
3363 }
3364 
3365 
3366 void JavaThread::trace_stack() {
3367   if (!has_last_Java_frame()) return;
3368   ResourceMark rm;
3369   HandleMark   hm;
3370   RegisterMap reg_map(this);
3371   trace_stack_from(last_java_vframe(&reg_map));
3372 }
3373 
3374 
3375 #endif // PRODUCT
3376 
3377 
3378 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3379   assert(reg_map != NULL, "a map must be given");
3380   frame f = last_frame();
3381   for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3382     if (vf->is_java_frame()) return javaVFrame::cast(vf);
3383   }
3384   return NULL;
3385 }
3386 
3387 
3388 Klass* JavaThread::security_get_caller_class(int depth) {
3389   vframeStream vfst(this);
3390   vfst.security_get_caller_frame(depth);
3391   if (!vfst.at_end()) {
3392     return vfst.method()->method_holder();
3393   }
3394   return NULL;
3395 }
3396 
3397 // java.lang.Thread.sleep support
3398 // Returns true if sleep time elapsed as expected, and false
3399 // if the thread was interrupted.
3400 bool JavaThread::sleep(jlong millis) {
3401   assert(this == Thread::current(),  "thread consistency check");
3402 
3403   ParkEvent * const slp = this->_SleepEvent;
3404   // Because there can be races with thread interruption sending an unpark()
3405   // to the event, we explicitly reset it here to avoid an immediate return.
3406   // The actual interrupt state will be checked before we park().
3407   slp->reset();
3408   // Thread interruption establishes a happens-before ordering in the
3409   // Java Memory Model, so we need to ensure we synchronize with the
3410   // interrupt state.
3411   OrderAccess::fence();
3412 
3413   jlong prevtime = os::javaTimeNanos();
3414 
3415   for (;;) {
3416     // interruption has precedence over timing out
3417     if (this->is_interrupted(true)) {
3418       return false;
3419     }
3420 
3421     if (millis <= 0) {
3422       return true;
3423     }
3424 
3425     {
3426       ThreadBlockInVM tbivm(this);
3427       OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
3428 
3429       this->set_suspend_equivalent();
3430       // cleared by handle_special_suspend_equivalent_condition() or
3431       // java_suspend_self() via check_and_wait_while_suspended()
3432 
3433       slp->park(millis);
3434 
3435       // were we externally suspended while we were waiting?
3436       this->check_and_wait_while_suspended();
3437     }
3438 
3439     // Update elapsed time tracking
3440     jlong newtime = os::javaTimeNanos();
3441     if (newtime - prevtime < 0) {
3442       // time moving backwards, should only happen if no monotonic clock
3443       // not a guarantee() because JVM should not abort on kernel/glibc bugs
3444       assert(!os::supports_monotonic_clock(),
3445              "unexpected time moving backwards detected in JavaThread::sleep()");
3446     } else {
3447       millis -= (newtime - prevtime) / NANOSECS_PER_MILLISEC;
3448     }
3449     prevtime = newtime;
3450   }
3451 }
3452 
3453 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3454   assert(thread->is_Compiler_thread(), "must be compiler thread");
3455   CompileBroker::compiler_thread_loop();
3456 }
3457 
3458 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3459   NMethodSweeper::sweeper_loop();
3460 }
3461 
3462 // Create a CompilerThread
3463 CompilerThread::CompilerThread(CompileQueue* queue,
3464                                CompilerCounters* counters)
3465                                : JavaThread(&compiler_thread_entry) {
3466   _env   = NULL;
3467   _log   = NULL;
3468   _task  = NULL;
3469   _queue = queue;
3470   _counters = counters;
3471   _buffer_blob = NULL;
3472   _compiler = NULL;
3473 
3474   // Compiler uses resource area for compilation, let's bias it to mtCompiler
3475   resource_area()->bias_to(mtCompiler);
3476 
3477 #ifndef PRODUCT
3478   _ideal_graph_printer = NULL;
3479 #endif
3480 }
3481 
3482 CompilerThread::~CompilerThread() {
3483   // Delete objects which were allocated on heap.
3484   delete _counters;
3485 }
3486 
3487 bool CompilerThread::can_call_java() const {
3488   return _compiler != NULL && _compiler->is_jvmci();
3489 }
3490 
3491 // Create sweeper thread
3492 CodeCacheSweeperThread::CodeCacheSweeperThread()
3493 : JavaThread(&sweeper_thread_entry) {
3494   _scanned_compiled_method = NULL;
3495 }
3496 
3497 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3498   JavaThread::oops_do(f, cf);
3499   if (_scanned_compiled_method != NULL && cf != NULL) {
3500     // Safepoints can occur when the sweeper is scanning an nmethod so
3501     // process it here to make sure it isn't unloaded in the middle of
3502     // a scan.
3503     cf->do_code_blob(_scanned_compiled_method);
3504   }
3505 }
3506 
3507 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3508   JavaThread::nmethods_do(cf);
3509   if (_scanned_compiled_method != NULL && cf != NULL) {
3510     // Safepoints can occur when the sweeper is scanning an nmethod so
3511     // process it here to make sure it isn't unloaded in the middle of
3512     // a scan.
3513     cf->do_code_blob(_scanned_compiled_method);
3514   }
3515 }
3516 
3517 
3518 // ======= Threads ========
3519 
3520 // The Threads class links together all active threads, and provides
3521 // operations over all threads. It is protected by the Threads_lock,
3522 // which is also used in other global contexts like safepointing.
3523 // ThreadsListHandles are used to safely perform operations on one
3524 // or more threads without the risk of the thread exiting during the
3525 // operation.
3526 //
3527 // Note: The Threads_lock is currently more widely used than we
3528 // would like. We are actively migrating Threads_lock uses to other
3529 // mechanisms in order to reduce Threads_lock contention.
3530 
3531 int         Threads::_number_of_threads = 0;
3532 int         Threads::_number_of_non_daemon_threads = 0;
3533 int         Threads::_return_code = 0;
3534 uintx       Threads::_thread_claim_token = 1; // Never zero.
3535 size_t      JavaThread::_stack_size_at_create = 0;
3536 
3537 #ifdef ASSERT
3538 bool        Threads::_vm_complete = false;
3539 #endif
3540 
3541 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
3542   Prefetch::read((void*)addr, prefetch_interval);
3543   return *addr;
3544 }
3545 
3546 // Possibly the ugliest for loop the world has seen. C++ does not allow
3547 // multiple types in the declaration section of the for loop. In this case
3548 // we are only dealing with pointers and hence can cast them. It looks ugly
3549 // but macros are ugly and therefore it's fine to make things absurdly ugly.
3550 #define DO_JAVA_THREADS(LIST, X)                                                                                          \
3551     for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes,                           \
3552              *MACRO_list = (JavaThread*)(LIST),                                                                           \
3553              **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(),  \
3554              **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(),                                     \
3555              *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval);                 \
3556          MACRO_current_p != MACRO_end;                                                                                    \
3557          MACRO_current_p++,                                                                                               \
3558              X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval))
3559 
3560 // All JavaThreads
3561 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X)
3562 
3563 // All NonJavaThreads (i.e., every non-JavaThread in the system).
3564 void Threads::non_java_threads_do(ThreadClosure* tc) {
3565   NoSafepointVerifier nsv;
3566   for (NonJavaThread::Iterator njti; !njti.end(); njti.step()) {
3567     tc->do_thread(njti.current());
3568   }
3569 }
3570 
3571 // All JavaThreads
3572 void Threads::java_threads_do(ThreadClosure* tc) {
3573   assert_locked_or_safepoint(Threads_lock);
3574   // ALL_JAVA_THREADS iterates through all JavaThreads.
3575   ALL_JAVA_THREADS(p) {
3576     tc->do_thread(p);
3577   }
3578 }
3579 
3580 void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) {
3581   assert_locked_or_safepoint(Threads_lock);
3582   java_threads_do(tc);
3583   tc->do_thread(VMThread::vm_thread());
3584 }
3585 
3586 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system).
3587 void Threads::threads_do(ThreadClosure* tc) {
3588   assert_locked_or_safepoint(Threads_lock);
3589   java_threads_do(tc);
3590   non_java_threads_do(tc);
3591 }
3592 
3593 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
3594   uintx claim_token = Threads::thread_claim_token();
3595   ALL_JAVA_THREADS(p) {
3596     if (p->claim_threads_do(is_par, claim_token)) {
3597       tc->do_thread(p);
3598     }
3599   }
3600   VMThread* vmt = VMThread::vm_thread();
3601   if (vmt->claim_threads_do(is_par, claim_token)) {
3602     tc->do_thread(vmt);
3603   }
3604 }
3605 
3606 // The system initialization in the library has three phases.
3607 //
3608 // Phase 1: java.lang.System class initialization
3609 //     java.lang.System is a primordial class loaded and initialized
3610 //     by the VM early during startup.  java.lang.System.<clinit>
3611 //     only does registerNatives and keeps the rest of the class
3612 //     initialization work later until thread initialization completes.
3613 //
3614 //     System.initPhase1 initializes the system properties, the static
3615 //     fields in, out, and err. Set up java signal handlers, OS-specific
3616 //     system settings, and thread group of the main thread.
3617 static void call_initPhase1(TRAPS) {
3618   Klass* klass =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3619   JavaValue result(T_VOID);
3620   JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3621                                          vmSymbols::void_method_signature(), CHECK);
3622 }
3623 
3624 // Phase 2. Module system initialization
3625 //     This will initialize the module system.  Only java.base classes
3626 //     can be loaded until phase 2 completes.
3627 //
3628 //     Call System.initPhase2 after the compiler initialization and jsr292
3629 //     classes get initialized because module initialization runs a lot of java
3630 //     code, that for performance reasons, should be compiled.  Also, this will
3631 //     enable the startup code to use lambda and other language features in this
3632 //     phase and onward.
3633 //
3634 //     After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3635 static void call_initPhase2(TRAPS) {
3636   TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3637 
3638   Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3639 
3640   JavaValue result(T_INT);
3641   JavaCallArguments args;
3642   args.push_int(DisplayVMOutputToStderr);
3643   args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3644   JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3645                                          vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3646   if (result.get_jint() != JNI_OK) {
3647     vm_exit_during_initialization(); // no message or exception
3648   }
3649 
3650   universe_post_module_init();
3651 }
3652 
3653 // Phase 3. final setup - set security manager, system class loader and TCCL
3654 //
3655 //     This will instantiate and set the security manager, set the system class
3656 //     loader as well as the thread context class loader.  The security manager
3657 //     and system class loader may be a custom class loaded from -Xbootclasspath/a,
3658 //     other modules or the application's classpath.
3659 static void call_initPhase3(TRAPS) {
3660   Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3661   JavaValue result(T_VOID);
3662   JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3663                                          vmSymbols::void_method_signature(), CHECK);
3664 }
3665 
3666 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3667   TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3668 
3669   if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3670     create_vm_init_libraries();
3671   }
3672 
3673   initialize_class(vmSymbols::java_lang_String(), CHECK);
3674 
3675   // Inject CompactStrings value after the static initializers for String ran.
3676   java_lang_String::set_compact_strings(CompactStrings);
3677 
3678   // Initialize java_lang.System (needed before creating the thread)
3679   initialize_class(vmSymbols::java_lang_System(), CHECK);
3680   // The VM creates & returns objects of this class. Make sure it's initialized.
3681   initialize_class(vmSymbols::java_lang_Class(), CHECK);
3682   initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3683   Handle thread_group = create_initial_thread_group(CHECK);
3684   Universe::set_main_thread_group(thread_group());
3685   initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3686   oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3687   main_thread->set_threadObj(thread_object);
3688 
3689   // Set thread status to running since main thread has
3690   // been started and running.
3691   java_lang_Thread::set_thread_status(thread_object,
3692                                       java_lang_Thread::RUNNABLE);
3693 
3694   // The VM creates objects of this class.
3695   initialize_class(vmSymbols::java_lang_Module(), CHECK);
3696 
3697 #ifdef ASSERT
3698   InstanceKlass *k = SystemDictionary::UnsafeConstants_klass();
3699   assert(k->is_not_initialized(), "UnsafeConstants should not already be initialized");
3700 #endif
3701 
3702   // initialize the hardware-specific constants needed by Unsafe
3703   initialize_class(vmSymbols::jdk_internal_misc_UnsafeConstants(), CHECK);
3704   jdk_internal_misc_UnsafeConstants::set_unsafe_constants();
3705 
3706   // The VM preresolves methods to these classes. Make sure that they get initialized
3707   initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3708   initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3709 
3710   // Phase 1 of the system initialization in the library, java.lang.System class initialization
3711   call_initPhase1(CHECK);
3712 
3713   // get the Java runtime name, version, and vendor info after java.lang.System is initialized
3714   JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3715   JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3716   JDK_Version::set_runtime_vendor_version(get_java_runtime_vendor_version(THREAD));
3717   JDK_Version::set_runtime_vendor_vm_bug_url(get_java_runtime_vendor_vm_bug_url(THREAD));
3718 
3719   // an instance of OutOfMemory exception has been allocated earlier
3720   initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3721   initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3722   initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3723   initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3724   initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3725   initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3726   initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3727   initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3728 
3729   // Eager box cache initialization only if AOT is on and any library is loaded.
3730   AOTLoader::initialize_box_caches(CHECK);
3731 }
3732 
3733 void Threads::initialize_jsr292_core_classes(TRAPS) {
3734   TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3735 
3736   initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3737   initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3738   initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3739   initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3740 }
3741 
3742 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3743   extern void JDK_Version_init();
3744 
3745   // Preinitialize version info.
3746   VM_Version::early_initialize();
3747 
3748   // Check version
3749   if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3750 
3751   // Initialize library-based TLS
3752   ThreadLocalStorage::init();
3753 
3754   // Initialize the output stream module
3755   ostream_init();
3756 
3757   // Process java launcher properties.
3758   Arguments::process_sun_java_launcher_properties(args);
3759 
3760   // Initialize the os module
3761   os::init();
3762 
3763   // Record VM creation timing statistics
3764   TraceVmCreationTime create_vm_timer;
3765   create_vm_timer.start();
3766 
3767   // Initialize system properties.
3768   Arguments::init_system_properties();
3769 
3770   // So that JDK version can be used as a discriminator when parsing arguments
3771   JDK_Version_init();
3772 
3773   // Update/Initialize System properties after JDK version number is known
3774   Arguments::init_version_specific_system_properties();
3775 
3776   // Make sure to initialize log configuration *before* parsing arguments
3777   LogConfiguration::initialize(create_vm_timer.begin_time());
3778 
3779   // Parse arguments
3780   // Note: this internally calls os::init_container_support()
3781   jint parse_result = Arguments::parse(args);
3782   if (parse_result != JNI_OK) return parse_result;
3783 
3784   os::init_before_ergo();
3785 
3786   jint ergo_result = Arguments::apply_ergo();
3787   if (ergo_result != JNI_OK) return ergo_result;
3788 
3789   // Final check of all ranges after ergonomics which may change values.
3790   if (!JVMFlagRangeList::check_ranges()) {
3791     return JNI_EINVAL;
3792   }
3793 
3794   // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3795   bool constraint_result = JVMFlagConstraintList::check_constraints(JVMFlagConstraint::AfterErgo);
3796   if (!constraint_result) {
3797     return JNI_EINVAL;
3798   }
3799 
3800   JVMFlagWriteableList::mark_startup();
3801 
3802   if (PauseAtStartup) {
3803     os::pause();
3804   }
3805 
3806   HOTSPOT_VM_INIT_BEGIN();
3807 
3808   // Timing (must come after argument parsing)
3809   TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3810 
3811   // Initialize the os module after parsing the args
3812   jint os_init_2_result = os::init_2();
3813   if (os_init_2_result != JNI_OK) return os_init_2_result;
3814 
3815 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT
3816   // Initialize assert poison page mechanism.
3817   if (ShowRegistersOnAssert) {
3818     initialize_assert_poison();
3819   }
3820 #endif // CAN_SHOW_REGISTERS_ON_ASSERT
3821 
3822   SafepointMechanism::initialize();
3823 
3824   jint adjust_after_os_result = Arguments::adjust_after_os();
3825   if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3826 
3827   // Initialize output stream logging
3828   ostream_init_log();
3829 
3830   // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3831   // Must be before create_vm_init_agents()
3832   if (Arguments::init_libraries_at_startup()) {
3833     convert_vm_init_libraries_to_agents();
3834   }
3835 
3836   // Launch -agentlib/-agentpath and converted -Xrun agents
3837   if (Arguments::init_agents_at_startup()) {
3838     create_vm_init_agents();
3839   }
3840 
3841   // Initialize Threads state
3842   _number_of_threads = 0;
3843   _number_of_non_daemon_threads = 0;
3844 
3845   // Initialize global data structures and create system classes in heap
3846   vm_init_globals();
3847 
3848 #if INCLUDE_JVMCI
3849   if (JVMCICounterSize > 0) {
3850     JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtJVMCI);
3851     memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3852   } else {
3853     JavaThread::_jvmci_old_thread_counters = NULL;
3854   }
3855 #endif // INCLUDE_JVMCI
3856 
3857   // Attach the main thread to this os thread
3858   JavaThread* main_thread = new JavaThread();
3859   main_thread->set_thread_state(_thread_in_vm);
3860   main_thread->initialize_thread_current();
3861   // must do this before set_active_handles
3862   main_thread->record_stack_base_and_size();
3863   main_thread->register_thread_stack_with_NMT();
3864   main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3865 
3866   if (!main_thread->set_as_starting_thread()) {
3867     vm_shutdown_during_initialization(
3868                                       "Failed necessary internal allocation. Out of swap space");
3869     main_thread->smr_delete();
3870     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3871     return JNI_ENOMEM;
3872   }
3873 
3874   // Enable guard page *after* os::create_main_thread(), otherwise it would
3875   // crash Linux VM, see notes in os_linux.cpp.
3876   main_thread->create_stack_guard_pages();
3877 
3878   // Initialize Java-Level synchronization subsystem
3879   ObjectMonitor::Initialize();
3880 
3881   // Initialize global modules
3882   jint status = init_globals();
3883   if (status != JNI_OK) {
3884     main_thread->smr_delete();
3885     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3886     return status;
3887   }
3888 
3889   JFR_ONLY(Jfr::on_create_vm_1();)
3890 
3891   // Should be done after the heap is fully created
3892   main_thread->cache_global_variables();
3893 
3894   HandleMark hm;
3895 
3896   { MutexLocker mu(Threads_lock);
3897     Threads::add(main_thread);
3898   }
3899 
3900   // Any JVMTI raw monitors entered in onload will transition into
3901   // real raw monitor. VM is setup enough here for raw monitor enter.
3902   JvmtiExport::transition_pending_onload_raw_monitors();
3903 
3904   // Create the VMThread
3905   { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3906 
3907     VMThread::create();
3908     Thread* vmthread = VMThread::vm_thread();
3909 
3910     if (!os::create_thread(vmthread, os::vm_thread)) {
3911       vm_exit_during_initialization("Cannot create VM thread. "
3912                                     "Out of system resources.");
3913     }
3914 
3915     // Wait for the VM thread to become ready, and VMThread::run to initialize
3916     // Monitors can have spurious returns, must always check another state flag
3917     {
3918       MonitorLocker ml(Notify_lock);
3919       os::start_thread(vmthread);
3920       while (vmthread->active_handles() == NULL) {
3921         ml.wait();
3922       }
3923     }
3924   }
3925 
3926   assert(Universe::is_fully_initialized(), "not initialized");
3927   if (VerifyDuringStartup) {
3928     // Make sure we're starting with a clean slate.
3929     VM_Verify verify_op;
3930     VMThread::execute(&verify_op);
3931   }
3932 
3933   // We need this to update the java.vm.info property in case any flags used
3934   // to initially define it have been changed. This is needed for both CDS and
3935   // AOT, since UseSharedSpaces and UseAOT may be changed after java.vm.info
3936   // is initially computed. See Abstract_VM_Version::vm_info_string().
3937   // This update must happen before we initialize the java classes, but
3938   // after any initialization logic that might modify the flags.
3939   Arguments::update_vm_info_property(VM_Version::vm_info_string());
3940 
3941   Thread* THREAD = Thread::current();
3942 
3943   // Always call even when there are not JVMTI environments yet, since environments
3944   // may be attached late and JVMTI must track phases of VM execution
3945   JvmtiExport::enter_early_start_phase();
3946 
3947   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3948   JvmtiExport::post_early_vm_start();
3949 
3950   initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3951 
3952   quicken_jni_functions();
3953 
3954   // No more stub generation allowed after that point.
3955   StubCodeDesc::freeze();
3956 
3957   // Set flag that basic initialization has completed. Used by exceptions and various
3958   // debug stuff, that does not work until all basic classes have been initialized.
3959   set_init_completed();
3960 
3961   LogConfiguration::post_initialize();
3962   Metaspace::post_initialize();
3963 
3964   HOTSPOT_VM_INIT_END();
3965 
3966   // record VM initialization completion time
3967 #if INCLUDE_MANAGEMENT
3968   Management::record_vm_init_completed();
3969 #endif // INCLUDE_MANAGEMENT
3970 
3971   // Signal Dispatcher needs to be started before VMInit event is posted
3972   os::initialize_jdk_signal_support(CHECK_JNI_ERR);
3973 
3974   // Start Attach Listener if +StartAttachListener or it can't be started lazily
3975   if (!DisableAttachMechanism) {
3976     AttachListener::vm_start();
3977     if (StartAttachListener || AttachListener::init_at_startup()) {
3978       AttachListener::init();
3979     }
3980   }
3981 
3982   // Launch -Xrun agents
3983   // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3984   // back-end can launch with -Xdebug -Xrunjdwp.
3985   if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3986     create_vm_init_libraries();
3987   }
3988 
3989   if (CleanChunkPoolAsync) {
3990     Chunk::start_chunk_pool_cleaner_task();
3991   }
3992 
3993 
3994   // initialize compiler(s)
3995 #if defined(COMPILER1) || COMPILER2_OR_JVMCI
3996 #if INCLUDE_JVMCI
3997   bool force_JVMCI_intialization = false;
3998   if (EnableJVMCI) {
3999     // Initialize JVMCI eagerly when it is explicitly requested.
4000     // Or when JVMCILibDumpJNIConfig or JVMCIPrintProperties is enabled.
4001     force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties || JVMCILibDumpJNIConfig;
4002 
4003     if (!force_JVMCI_intialization) {
4004       // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
4005       // compilations via JVMCI will not actually block until JVMCI is initialized.
4006       force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
4007     }
4008   }
4009 #endif
4010   CompileBroker::compilation_init_phase1(CHECK_JNI_ERR);
4011   // Postpone completion of compiler initialization to after JVMCI
4012   // is initialized to avoid timeouts of blocking compilations.
4013   if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) {
4014     CompileBroker::compilation_init_phase2();
4015   }
4016 #endif
4017 
4018   // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
4019   // It is done after compilers are initialized, because otherwise compilations of
4020   // signature polymorphic MH intrinsics can be missed
4021   // (see SystemDictionary::find_method_handle_intrinsic).
4022   initialize_jsr292_core_classes(CHECK_JNI_ERR);
4023 
4024   // This will initialize the module system.  Only java.base classes can be
4025   // loaded until phase 2 completes
4026   call_initPhase2(CHECK_JNI_ERR);
4027 
4028   JFR_ONLY(Jfr::on_create_vm_2();)
4029 
4030   // Always call even when there are not JVMTI environments yet, since environments
4031   // may be attached late and JVMTI must track phases of VM execution
4032   JvmtiExport::enter_start_phase();
4033 
4034   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
4035   JvmtiExport::post_vm_start();
4036 
4037   // Final system initialization including security manager and system class loader
4038   call_initPhase3(CHECK_JNI_ERR);
4039 
4040   // cache the system and platform class loaders
4041   SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
4042 
4043 #if INCLUDE_CDS
4044   // capture the module path info from the ModuleEntryTable
4045   ClassLoader::initialize_module_path(THREAD);
4046 #endif
4047 
4048 #if INCLUDE_JVMCI
4049   if (force_JVMCI_intialization) {
4050     JVMCI::initialize_compiler(CHECK_JNI_ERR);
4051     CompileBroker::compilation_init_phase2();
4052   }
4053 #endif
4054 
4055   // Always call even when there are not JVMTI environments yet, since environments
4056   // may be attached late and JVMTI must track phases of VM execution
4057   JvmtiExport::enter_live_phase();
4058 
4059   // Make perfmemory accessible
4060   PerfMemory::set_accessible(true);
4061 
4062   // Notify JVMTI agents that VM initialization is complete - nop if no agents.
4063   JvmtiExport::post_vm_initialized();
4064 
4065   JFR_ONLY(Jfr::on_create_vm_3();)
4066 
4067 #if INCLUDE_MANAGEMENT
4068   Management::initialize(THREAD);
4069 
4070   if (HAS_PENDING_EXCEPTION) {
4071     // management agent fails to start possibly due to
4072     // configuration problem and is responsible for printing
4073     // stack trace if appropriate. Simply exit VM.
4074     vm_exit(1);
4075   }
4076 #endif // INCLUDE_MANAGEMENT
4077 
4078   if (MemProfiling)                   MemProfiler::engage();
4079   StatSampler::engage();
4080   if (CheckJNICalls)                  JniPeriodicChecker::engage();
4081 
4082   BiasedLocking::init();
4083 
4084 #if INCLUDE_RTM_OPT
4085   RTMLockingCounters::init();
4086 #endif
4087 
4088   call_postVMInitHook(THREAD);
4089   // The Java side of PostVMInitHook.run must deal with all
4090   // exceptions and provide means of diagnosis.
4091   if (HAS_PENDING_EXCEPTION) {
4092     CLEAR_PENDING_EXCEPTION;
4093   }
4094 
4095   {
4096     MutexLocker ml(PeriodicTask_lock);
4097     // Make sure the WatcherThread can be started by WatcherThread::start()
4098     // or by dynamic enrollment.
4099     WatcherThread::make_startable();
4100     // Start up the WatcherThread if there are any periodic tasks
4101     // NOTE:  All PeriodicTasks should be registered by now. If they
4102     //   aren't, late joiners might appear to start slowly (we might
4103     //   take a while to process their first tick).
4104     if (PeriodicTask::num_tasks() > 0) {
4105       WatcherThread::start();
4106     }
4107   }
4108 
4109   create_vm_timer.end();
4110 #ifdef ASSERT
4111   _vm_complete = true;
4112 #endif
4113 
4114   if (DumpSharedSpaces) {
4115     MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
4116     ShouldNotReachHere();
4117   }
4118 
4119   return JNI_OK;
4120 }
4121 
4122 // type for the Agent_OnLoad and JVM_OnLoad entry points
4123 extern "C" {
4124   typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
4125 }
4126 // Find a command line agent library and return its entry point for
4127 //         -agentlib:  -agentpath:   -Xrun
4128 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
4129 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
4130                                     const char *on_load_symbols[],
4131                                     size_t num_symbol_entries) {
4132   OnLoadEntry_t on_load_entry = NULL;
4133   void *library = NULL;
4134 
4135   if (!agent->valid()) {
4136     char buffer[JVM_MAXPATHLEN];
4137     char ebuf[1024] = "";
4138     const char *name = agent->name();
4139     const char *msg = "Could not find agent library ";
4140 
4141     // First check to see if agent is statically linked into executable
4142     if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
4143       library = agent->os_lib();
4144     } else if (agent->is_absolute_path()) {
4145       library = os::dll_load(name, ebuf, sizeof ebuf);
4146       if (library == NULL) {
4147         const char *sub_msg = " in absolute path, with error: ";
4148         size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
4149         char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4150         jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4151         // If we can't find the agent, exit.
4152         vm_exit_during_initialization(buf, NULL);
4153         FREE_C_HEAP_ARRAY(char, buf);
4154       }
4155     } else {
4156       // Try to load the agent from the standard dll directory
4157       if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
4158                              name)) {
4159         library = os::dll_load(buffer, ebuf, sizeof ebuf);
4160       }
4161       if (library == NULL) { // Try the library path directory.
4162         if (os::dll_build_name(buffer, sizeof(buffer), name)) {
4163           library = os::dll_load(buffer, ebuf, sizeof ebuf);
4164         }
4165         if (library == NULL) {
4166           const char *sub_msg = " on the library path, with error: ";
4167           const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image.";
4168 
4169           size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) +
4170                        strlen(ebuf) + strlen(sub_msg2) + 1;
4171           char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4172           if (!agent->is_instrument_lib()) {
4173             jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4174           } else {
4175             jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2);
4176           }
4177           // If we can't find the agent, exit.
4178           vm_exit_during_initialization(buf, NULL);
4179           FREE_C_HEAP_ARRAY(char, buf);
4180         }
4181       }
4182     }
4183     agent->set_os_lib(library);
4184     agent->set_valid();
4185   }
4186 
4187   // Find the OnLoad function.
4188   on_load_entry =
4189     CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
4190                                                           false,
4191                                                           on_load_symbols,
4192                                                           num_symbol_entries));
4193   return on_load_entry;
4194 }
4195 
4196 // Find the JVM_OnLoad entry point
4197 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
4198   const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
4199   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4200 }
4201 
4202 // Find the Agent_OnLoad entry point
4203 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
4204   const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
4205   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4206 }
4207 
4208 // For backwards compatibility with -Xrun
4209 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
4210 // treated like -agentpath:
4211 // Must be called before agent libraries are created
4212 void Threads::convert_vm_init_libraries_to_agents() {
4213   AgentLibrary* agent;
4214   AgentLibrary* next;
4215 
4216   for (agent = Arguments::libraries(); agent != NULL; agent = next) {
4217     next = agent->next();  // cache the next agent now as this agent may get moved off this list
4218     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4219 
4220     // If there is an JVM_OnLoad function it will get called later,
4221     // otherwise see if there is an Agent_OnLoad
4222     if (on_load_entry == NULL) {
4223       on_load_entry = lookup_agent_on_load(agent);
4224       if (on_load_entry != NULL) {
4225         // switch it to the agent list -- so that Agent_OnLoad will be called,
4226         // JVM_OnLoad won't be attempted and Agent_OnUnload will
4227         Arguments::convert_library_to_agent(agent);
4228       } else {
4229         vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
4230       }
4231     }
4232   }
4233 }
4234 
4235 // Create agents for -agentlib:  -agentpath:  and converted -Xrun
4236 // Invokes Agent_OnLoad
4237 // Called very early -- before JavaThreads exist
4238 void Threads::create_vm_init_agents() {
4239   extern struct JavaVM_ main_vm;
4240   AgentLibrary* agent;
4241 
4242   JvmtiExport::enter_onload_phase();
4243 
4244   for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4245     // CDS dumping does not support native JVMTI agent.
4246     // CDS dumping supports Java agent if the AllowArchivingWithJavaAgent diagnostic option is specified.
4247     if (Arguments::is_dumping_archive()) {
4248       if(!agent->is_instrument_lib()) {
4249         vm_exit_during_cds_dumping("CDS dumping does not support native JVMTI agent, name", agent->name());
4250       } else if (!AllowArchivingWithJavaAgent) {
4251         vm_exit_during_cds_dumping(
4252           "Must enable AllowArchivingWithJavaAgent in order to run Java agent during CDS dumping");
4253       }
4254     }
4255 
4256     OnLoadEntry_t  on_load_entry = lookup_agent_on_load(agent);
4257 
4258     if (on_load_entry != NULL) {
4259       // Invoke the Agent_OnLoad function
4260       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4261       if (err != JNI_OK) {
4262         vm_exit_during_initialization("agent library failed to init", agent->name());
4263       }
4264     } else {
4265       vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4266     }
4267   }
4268 
4269   JvmtiExport::enter_primordial_phase();
4270 }
4271 
4272 extern "C" {
4273   typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4274 }
4275 
4276 void Threads::shutdown_vm_agents() {
4277   // Send any Agent_OnUnload notifications
4278   const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4279   size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4280   extern struct JavaVM_ main_vm;
4281   for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4282 
4283     // Find the Agent_OnUnload function.
4284     Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4285                                                    os::find_agent_function(agent,
4286                                                    false,
4287                                                    on_unload_symbols,
4288                                                    num_symbol_entries));
4289 
4290     // Invoke the Agent_OnUnload function
4291     if (unload_entry != NULL) {
4292       JavaThread* thread = JavaThread::current();
4293       ThreadToNativeFromVM ttn(thread);
4294       HandleMark hm(thread);
4295       (*unload_entry)(&main_vm);
4296     }
4297   }
4298 }
4299 
4300 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4301 // Invokes JVM_OnLoad
4302 void Threads::create_vm_init_libraries() {
4303   extern struct JavaVM_ main_vm;
4304   AgentLibrary* agent;
4305 
4306   for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4307     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4308 
4309     if (on_load_entry != NULL) {
4310       // Invoke the JVM_OnLoad function
4311       JavaThread* thread = JavaThread::current();
4312       ThreadToNativeFromVM ttn(thread);
4313       HandleMark hm(thread);
4314       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4315       if (err != JNI_OK) {
4316         vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4317       }
4318     } else {
4319       vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4320     }
4321   }
4322 }
4323 
4324 
4325 // Last thread running calls java.lang.Shutdown.shutdown()
4326 void JavaThread::invoke_shutdown_hooks() {
4327   HandleMark hm(this);
4328 
4329   // We could get here with a pending exception, if so clear it now.
4330   if (this->has_pending_exception()) {
4331     this->clear_pending_exception();
4332   }
4333 
4334   EXCEPTION_MARK;
4335   Klass* shutdown_klass =
4336     SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4337                                       THREAD);
4338   if (shutdown_klass != NULL) {
4339     // SystemDictionary::resolve_or_null will return null if there was
4340     // an exception.  If we cannot load the Shutdown class, just don't
4341     // call Shutdown.shutdown() at all.  This will mean the shutdown hooks
4342     // won't be run.  Note that if a shutdown hook was registered,
4343     // the Shutdown class would have already been loaded
4344     // (Runtime.addShutdownHook will load it).
4345     JavaValue result(T_VOID);
4346     JavaCalls::call_static(&result,
4347                            shutdown_klass,
4348                            vmSymbols::shutdown_name(),
4349                            vmSymbols::void_method_signature(),
4350                            THREAD);
4351   }
4352   CLEAR_PENDING_EXCEPTION;
4353 }
4354 
4355 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4356 // the program falls off the end of main(). Another VM exit path is through
4357 // vm_exit() when the program calls System.exit() to return a value or when
4358 // there is a serious error in VM. The two shutdown paths are not exactly
4359 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4360 // and VM_Exit op at VM level.
4361 //
4362 // Shutdown sequence:
4363 //   + Shutdown native memory tracking if it is on
4364 //   + Wait until we are the last non-daemon thread to execute
4365 //     <-- every thing is still working at this moment -->
4366 //   + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4367 //        shutdown hooks
4368 //   + Call before_exit(), prepare for VM exit
4369 //      > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4370 //        currently the only user of this mechanism is File.deleteOnExit())
4371 //      > stop StatSampler, watcher thread,
4372 //        post thread end and vm death events to JVMTI,
4373 //        stop signal thread
4374 //   + Call JavaThread::exit(), it will:
4375 //      > release JNI handle blocks, remove stack guard pages
4376 //      > remove this thread from Threads list
4377 //     <-- no more Java code from this thread after this point -->
4378 //   + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4379 //     the compiler threads at safepoint
4380 //     <-- do not use anything that could get blocked by Safepoint -->
4381 //   + Disable tracing at JNI/JVM barriers
4382 //   + Set _vm_exited flag for threads that are still running native code
4383 //   + Call exit_globals()
4384 //      > deletes tty
4385 //      > deletes PerfMemory resources
4386 //   + Delete this thread
4387 //   + Return to caller
4388 
4389 bool Threads::destroy_vm() {
4390   JavaThread* thread = JavaThread::current();
4391 
4392 #ifdef ASSERT
4393   _vm_complete = false;
4394 #endif
4395   // Wait until we are the last non-daemon thread to execute
4396   { MonitorLocker nu(Threads_lock);
4397     while (Threads::number_of_non_daemon_threads() > 1)
4398       // This wait should make safepoint checks, wait without a timeout,
4399       // and wait as a suspend-equivalent condition.
4400       nu.wait(0, Mutex::_as_suspend_equivalent_flag);
4401   }
4402 
4403   EventShutdown e;
4404   if (e.should_commit()) {
4405     e.set_reason("No remaining non-daemon Java threads");
4406     e.commit();
4407   }
4408 
4409   // Hang forever on exit if we are reporting an error.
4410   if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4411     os::infinite_sleep();
4412   }
4413   os::wait_for_keypress_at_exit();
4414 
4415   // run Java level shutdown hooks
4416   thread->invoke_shutdown_hooks();
4417 
4418   before_exit(thread);
4419 
4420   thread->exit(true);
4421 
4422   // Stop VM thread.
4423   {
4424     // 4945125 The vm thread comes to a safepoint during exit.
4425     // GC vm_operations can get caught at the safepoint, and the
4426     // heap is unparseable if they are caught. Grab the Heap_lock
4427     // to prevent this. The GC vm_operations will not be able to
4428     // queue until after the vm thread is dead. After this point,
4429     // we'll never emerge out of the safepoint before the VM exits.
4430 
4431     MutexLocker ml(Heap_lock, Mutex::_no_safepoint_check_flag);
4432 
4433     VMThread::wait_for_vm_thread_exit();
4434     assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4435     VMThread::destroy();
4436   }
4437 
4438   // Now, all Java threads are gone except daemon threads. Daemon threads
4439   // running Java code or in VM are stopped by the Safepoint. However,
4440   // daemon threads executing native code are still running.  But they
4441   // will be stopped at native=>Java/VM barriers. Note that we can't
4442   // simply kill or suspend them, as it is inherently deadlock-prone.
4443 
4444   VM_Exit::set_vm_exited();
4445 
4446   // Clean up ideal graph printers after the VMThread has started
4447   // the final safepoint which will block all the Compiler threads.
4448   // Note that this Thread has already logically exited so the
4449   // clean_up() function's use of a JavaThreadIteratorWithHandle
4450   // would be a problem except set_vm_exited() has remembered the
4451   // shutdown thread which is granted a policy exception.
4452 #if defined(COMPILER2) && !defined(PRODUCT)
4453   IdealGraphPrinter::clean_up();
4454 #endif
4455 
4456   notify_vm_shutdown();
4457 
4458   // exit_globals() will delete tty
4459   exit_globals();
4460 
4461   // We are after VM_Exit::set_vm_exited() so we can't call
4462   // thread->smr_delete() or we will block on the Threads_lock.
4463   // Deleting the shutdown thread here is safe because another
4464   // JavaThread cannot have an active ThreadsListHandle for
4465   // this JavaThread.
4466   delete thread;
4467 
4468 #if INCLUDE_JVMCI
4469   if (JVMCICounterSize > 0) {
4470     FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4471   }
4472 #endif
4473 
4474   LogConfiguration::finalize();
4475 
4476   return true;
4477 }
4478 
4479 
4480 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4481   if (version == JNI_VERSION_1_1) return JNI_TRUE;
4482   return is_supported_jni_version(version);
4483 }
4484 
4485 
4486 jboolean Threads::is_supported_jni_version(jint version) {
4487   if (version == JNI_VERSION_1_2) return JNI_TRUE;
4488   if (version == JNI_VERSION_1_4) return JNI_TRUE;
4489   if (version == JNI_VERSION_1_6) return JNI_TRUE;
4490   if (version == JNI_VERSION_1_8) return JNI_TRUE;
4491   if (version == JNI_VERSION_9) return JNI_TRUE;
4492   if (version == JNI_VERSION_10) return JNI_TRUE;
4493   return JNI_FALSE;
4494 }
4495 
4496 
4497 void Threads::add(JavaThread* p, bool force_daemon) {
4498   // The threads lock must be owned at this point
4499   assert(Threads_lock->owned_by_self(), "must have threads lock");
4500 
4501   BarrierSet::barrier_set()->on_thread_attach(p);
4502 
4503   // Once a JavaThread is added to the Threads list, smr_delete() has
4504   // to be used to delete it. Otherwise we can just delete it directly.
4505   p->set_on_thread_list();
4506 
4507   _number_of_threads++;
4508   oop threadObj = p->threadObj();
4509   bool daemon = true;
4510   // Bootstrapping problem: threadObj can be null for initial
4511   // JavaThread (or for threads attached via JNI)
4512   if ((!force_daemon) && !is_daemon((threadObj))) {
4513     _number_of_non_daemon_threads++;
4514     daemon = false;
4515   }
4516 
4517   ThreadService::add_thread(p, daemon);
4518 
4519   // Maintain fast thread list
4520   ThreadsSMRSupport::add_thread(p);
4521 
4522   // Possible GC point.
4523   Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4524 }
4525 
4526 void Threads::remove(JavaThread* p, bool is_daemon) {
4527 
4528   // Reclaim the ObjectMonitors from the om_in_use_list and om_free_list of the moribund thread.
4529   ObjectSynchronizer::om_flush(p);
4530 
4531   // Extra scope needed for Thread_lock, so we can check
4532   // that we do not remove thread without safepoint code notice
4533   { MonitorLocker ml(Threads_lock);
4534 
4535     assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present");
4536 
4537     // Maintain fast thread list
4538     ThreadsSMRSupport::remove_thread(p);
4539 
4540     _number_of_threads--;
4541     if (!is_daemon) {
4542       _number_of_non_daemon_threads--;
4543 
4544       // Only one thread left, do a notify on the Threads_lock so a thread waiting
4545       // on destroy_vm will wake up.
4546       if (number_of_non_daemon_threads() == 1) {
4547         ml.notify_all();
4548       }
4549     }
4550     ThreadService::remove_thread(p, is_daemon);
4551 
4552     // Make sure that safepoint code disregard this thread. This is needed since
4553     // the thread might mess around with locks after this point. This can cause it
4554     // to do callbacks into the safepoint code. However, the safepoint code is not aware
4555     // of this thread since it is removed from the queue.
4556     p->set_terminated_value();
4557   } // unlock Threads_lock
4558 
4559   // Since Events::log uses a lock, we grab it outside the Threads_lock
4560   Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4561 }
4562 
4563 // Operations on the Threads list for GC.  These are not explicitly locked,
4564 // but the garbage collector must provide a safe context for them to run.
4565 // In particular, these things should never be called when the Threads_lock
4566 // is held by some other thread. (Note: the Safepoint abstraction also
4567 // uses the Threads_lock to guarantee this property. It also makes sure that
4568 // all threads gets blocked when exiting or starting).
4569 
4570 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4571   ALL_JAVA_THREADS(p) {
4572     p->oops_do(f, cf);
4573   }
4574   VMThread::vm_thread()->oops_do(f, cf);
4575 }
4576 
4577 void Threads::change_thread_claim_token() {
4578   if (++_thread_claim_token == 0) {
4579     // On overflow of the token counter, there is a risk of future
4580     // collisions between a new global token value and a stale token
4581     // for a thread, because not all iterations visit all threads.
4582     // (Though it's pretty much a theoretical concern for non-trivial
4583     // token counter sizes.)  To deal with the possibility, reset all
4584     // the thread tokens to zero on global token overflow.
4585     struct ResetClaims : public ThreadClosure {
4586       virtual void do_thread(Thread* t) {
4587         t->claim_threads_do(false, 0);
4588       }
4589     } reset_claims;
4590     Threads::threads_do(&reset_claims);
4591     // On overflow, update the global token to non-zero, to
4592     // avoid the special "never claimed" initial thread value.
4593     _thread_claim_token = 1;
4594   }
4595 }
4596 
4597 #ifdef ASSERT
4598 void assert_thread_claimed(const char* kind, Thread* t, uintx expected) {
4599   const uintx token = t->threads_do_token();
4600   assert(token == expected,
4601          "%s " PTR_FORMAT " has incorrect value " UINTX_FORMAT " != "
4602          UINTX_FORMAT, kind, p2i(t), token, expected);
4603 }
4604 
4605 void Threads::assert_all_threads_claimed() {
4606   ALL_JAVA_THREADS(p) {
4607     assert_thread_claimed("Thread", p, _thread_claim_token);
4608   }
4609   assert_thread_claimed("VMThread", VMThread::vm_thread(), _thread_claim_token);
4610 }
4611 #endif // ASSERT
4612 
4613 class ParallelOopsDoThreadClosure : public ThreadClosure {
4614 private:
4615   OopClosure* _f;
4616   CodeBlobClosure* _cf;
4617 public:
4618   ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {}
4619   void do_thread(Thread* t) {
4620     t->oops_do(_f, _cf);
4621   }
4622 };
4623 
4624 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4625   ParallelOopsDoThreadClosure tc(f, cf);
4626   possibly_parallel_threads_do(is_par, &tc);
4627 }
4628 
4629 void Threads::nmethods_do(CodeBlobClosure* cf) {
4630   ALL_JAVA_THREADS(p) {
4631     // This is used by the code cache sweeper to mark nmethods that are active
4632     // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4633     // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4634     if(!p->is_Code_cache_sweeper_thread()) {
4635       p->nmethods_do(cf);
4636     }
4637   }
4638 }
4639 
4640 void Threads::metadata_do(MetadataClosure* f) {
4641   ALL_JAVA_THREADS(p) {
4642     p->metadata_do(f);
4643   }
4644 }
4645 
4646 class ThreadHandlesClosure : public ThreadClosure {
4647   void (*_f)(Metadata*);
4648  public:
4649   ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4650   virtual void do_thread(Thread* thread) {
4651     thread->metadata_handles_do(_f);
4652   }
4653 };
4654 
4655 void Threads::metadata_handles_do(void f(Metadata*)) {
4656   // Only walk the Handles in Thread.
4657   ThreadHandlesClosure handles_closure(f);
4658   threads_do(&handles_closure);
4659 }
4660 
4661 // Get count Java threads that are waiting to enter the specified monitor.
4662 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
4663                                                          int count,
4664                                                          address monitor) {
4665   GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4666 
4667   int i = 0;
4668   DO_JAVA_THREADS(t_list, p) {
4669     if (!p->can_call_java()) continue;
4670 
4671     address pending = (address)p->current_pending_monitor();
4672     if (pending == monitor) {             // found a match
4673       if (i < count) result->append(p);   // save the first count matches
4674       i++;
4675     }
4676   }
4677 
4678   return result;
4679 }
4680 
4681 
4682 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
4683                                                       address owner) {
4684   // NULL owner means not locked so we can skip the search
4685   if (owner == NULL) return NULL;
4686 
4687   DO_JAVA_THREADS(t_list, p) {
4688     // first, see if owner is the address of a Java thread
4689     if (owner == (address)p) return p;
4690   }
4691 
4692   // Cannot assert on lack of success here since this function may be
4693   // used by code that is trying to report useful problem information
4694   // like deadlock detection.
4695   if (UseHeavyMonitors) return NULL;
4696 
4697   // If we didn't find a matching Java thread and we didn't force use of
4698   // heavyweight monitors, then the owner is the stack address of the
4699   // Lock Word in the owning Java thread's stack.
4700   //
4701   JavaThread* the_owner = NULL;
4702   DO_JAVA_THREADS(t_list, q) {
4703     if (q->is_lock_owned(owner)) {
4704       the_owner = q;
4705       break;
4706     }
4707   }
4708 
4709   // cannot assert on lack of success here; see above comment
4710   return the_owner;
4711 }
4712 
4713 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4714 void Threads::print_on(outputStream* st, bool print_stacks,
4715                        bool internal_format, bool print_concurrent_locks,
4716                        bool print_extended_info) {
4717   char buf[32];
4718   st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4719 
4720   st->print_cr("Full thread dump %s (%s %s):",
4721                VM_Version::vm_name(),
4722                VM_Version::vm_release(),
4723                VM_Version::vm_info_string());
4724   st->cr();
4725 
4726 #if INCLUDE_SERVICES
4727   // Dump concurrent locks
4728   ConcurrentLocksDump concurrent_locks;
4729   if (print_concurrent_locks) {
4730     concurrent_locks.dump_at_safepoint();
4731   }
4732 #endif // INCLUDE_SERVICES
4733 
4734   ThreadsSMRSupport::print_info_on(st);
4735   st->cr();
4736 
4737   ALL_JAVA_THREADS(p) {
4738     ResourceMark rm;
4739     p->print_on(st, print_extended_info);
4740     if (print_stacks) {
4741       if (internal_format) {
4742         p->trace_stack();
4743       } else {
4744         p->print_stack_on(st);
4745       }
4746     }
4747     st->cr();
4748 #if INCLUDE_SERVICES
4749     if (print_concurrent_locks) {
4750       concurrent_locks.print_locks_on(p, st);
4751     }
4752 #endif // INCLUDE_SERVICES
4753   }
4754 
4755   VMThread::vm_thread()->print_on(st);
4756   st->cr();
4757   Universe::heap()->print_gc_threads_on(st);
4758   WatcherThread* wt = WatcherThread::watcher_thread();
4759   if (wt != NULL) {
4760     wt->print_on(st);
4761     st->cr();
4762   }
4763 
4764   st->flush();
4765 }
4766 
4767 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4768                              int buflen, bool* found_current) {
4769   if (this_thread != NULL) {
4770     bool is_current = (current == this_thread);
4771     *found_current = *found_current || is_current;
4772     st->print("%s", is_current ? "=>" : "  ");
4773 
4774     st->print(PTR_FORMAT, p2i(this_thread));
4775     st->print(" ");
4776     this_thread->print_on_error(st, buf, buflen);
4777     st->cr();
4778   }
4779 }
4780 
4781 class PrintOnErrorClosure : public ThreadClosure {
4782   outputStream* _st;
4783   Thread* _current;
4784   char* _buf;
4785   int _buflen;
4786   bool* _found_current;
4787  public:
4788   PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4789                       int buflen, bool* found_current) :
4790    _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4791 
4792   virtual void do_thread(Thread* thread) {
4793     Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4794   }
4795 };
4796 
4797 // Threads::print_on_error() is called by fatal error handler. It's possible
4798 // that VM is not at safepoint and/or current thread is inside signal handler.
4799 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4800 // memory (even in resource area), it might deadlock the error handler.
4801 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4802                              int buflen) {
4803   ThreadsSMRSupport::print_info_on(st);
4804   st->cr();
4805 
4806   bool found_current = false;
4807   st->print_cr("Java Threads: ( => current thread )");
4808   ALL_JAVA_THREADS(thread) {
4809     print_on_error(thread, st, current, buf, buflen, &found_current);
4810   }
4811   st->cr();
4812 
4813   st->print_cr("Other Threads:");
4814   print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4815   print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4816 
4817   PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4818   Universe::heap()->gc_threads_do(&print_closure);
4819 
4820   if (!found_current) {
4821     st->cr();
4822     st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4823     current->print_on_error(st, buf, buflen);
4824     st->cr();
4825   }
4826   st->cr();
4827 
4828   st->print_cr("Threads with active compile tasks:");
4829   print_threads_compiling(st, buf, buflen);
4830 }
4831 
4832 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen, bool short_form) {
4833   ALL_JAVA_THREADS(thread) {
4834     if (thread->is_Compiler_thread()) {
4835       CompilerThread* ct = (CompilerThread*) thread;
4836 
4837       // Keep task in local variable for NULL check.
4838       // ct->_task might be set to NULL by concurring compiler thread
4839       // because it completed the compilation. The task is never freed,
4840       // though, just returned to a free list.
4841       CompileTask* task = ct->task();
4842       if (task != NULL) {
4843         thread->print_name_on_error(st, buf, buflen);
4844         st->print("  ");
4845         task->print(st, NULL, short_form, true);
4846       }
4847     }
4848   }
4849 }
4850 
4851 
4852 // Internal SpinLock and Mutex
4853 // Based on ParkEvent
4854 
4855 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4856 //
4857 // We employ SpinLocks _only for low-contention, fixed-length
4858 // short-duration critical sections where we're concerned
4859 // about native mutex_t or HotSpot Mutex:: latency.
4860 // The mux construct provides a spin-then-block mutual exclusion
4861 // mechanism.
4862 //
4863 // Testing has shown that contention on the ListLock guarding gFreeList
4864 // is common.  If we implement ListLock as a simple SpinLock it's common
4865 // for the JVM to devolve to yielding with little progress.  This is true
4866 // despite the fact that the critical sections protected by ListLock are
4867 // extremely short.
4868 //
4869 // TODO-FIXME: ListLock should be of type SpinLock.
4870 // We should make this a 1st-class type, integrated into the lock
4871 // hierarchy as leaf-locks.  Critically, the SpinLock structure
4872 // should have sufficient padding to avoid false-sharing and excessive
4873 // cache-coherency traffic.
4874 
4875 
4876 typedef volatile int SpinLockT;
4877 
4878 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4879   if (Atomic::cmpxchg(adr, 0, 1) == 0) {
4880     return;   // normal fast-path return
4881   }
4882 
4883   // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4884   int ctr = 0;
4885   int Yields = 0;
4886   for (;;) {
4887     while (*adr != 0) {
4888       ++ctr;
4889       if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4890         if (Yields > 5) {
4891           os::naked_short_sleep(1);
4892         } else {
4893           os::naked_yield();
4894           ++Yields;
4895         }
4896       } else {
4897         SpinPause();
4898       }
4899     }
4900     if (Atomic::cmpxchg(adr, 0, 1) == 0) return;
4901   }
4902 }
4903 
4904 void Thread::SpinRelease(volatile int * adr) {
4905   assert(*adr != 0, "invariant");
4906   OrderAccess::fence();      // guarantee at least release consistency.
4907   // Roach-motel semantics.
4908   // It's safe if subsequent LDs and STs float "up" into the critical section,
4909   // but prior LDs and STs within the critical section can't be allowed
4910   // to reorder or float past the ST that releases the lock.
4911   // Loads and stores in the critical section - which appear in program
4912   // order before the store that releases the lock - must also appear
4913   // before the store that releases the lock in memory visibility order.
4914   // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4915   // the ST of 0 into the lock-word which releases the lock, so fence
4916   // more than covers this on all platforms.
4917   *adr = 0;
4918 }
4919 
4920 // muxAcquire and muxRelease:
4921 //
4922 // *  muxAcquire and muxRelease support a single-word lock-word construct.
4923 //    The LSB of the word is set IFF the lock is held.
4924 //    The remainder of the word points to the head of a singly-linked list
4925 //    of threads blocked on the lock.
4926 //
4927 // *  The current implementation of muxAcquire-muxRelease uses its own
4928 //    dedicated Thread._MuxEvent instance.  If we're interested in
4929 //    minimizing the peak number of extant ParkEvent instances then
4930 //    we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4931 //    as certain invariants were satisfied.  Specifically, care would need
4932 //    to be taken with regards to consuming unpark() "permits".
4933 //    A safe rule of thumb is that a thread would never call muxAcquire()
4934 //    if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4935 //    park().  Otherwise the _ParkEvent park() operation in muxAcquire() could
4936 //    consume an unpark() permit intended for monitorenter, for instance.
4937 //    One way around this would be to widen the restricted-range semaphore
4938 //    implemented in park().  Another alternative would be to provide
4939 //    multiple instances of the PlatformEvent() for each thread.  One
4940 //    instance would be dedicated to muxAcquire-muxRelease, for instance.
4941 //
4942 // *  Usage:
4943 //    -- Only as leaf locks
4944 //    -- for short-term locking only as muxAcquire does not perform
4945 //       thread state transitions.
4946 //
4947 // Alternatives:
4948 // *  We could implement muxAcquire and muxRelease with MCS or CLH locks
4949 //    but with parking or spin-then-park instead of pure spinning.
4950 // *  Use Taura-Oyama-Yonenzawa locks.
4951 // *  It's possible to construct a 1-0 lock if we encode the lockword as
4952 //    (List,LockByte).  Acquire will CAS the full lockword while Release
4953 //    will STB 0 into the LockByte.  The 1-0 scheme admits stranding, so
4954 //    acquiring threads use timers (ParkTimed) to detect and recover from
4955 //    the stranding window.  Thread/Node structures must be aligned on 256-byte
4956 //    boundaries by using placement-new.
4957 // *  Augment MCS with advisory back-link fields maintained with CAS().
4958 //    Pictorially:  LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4959 //    The validity of the backlinks must be ratified before we trust the value.
4960 //    If the backlinks are invalid the exiting thread must back-track through the
4961 //    the forward links, which are always trustworthy.
4962 // *  Add a successor indication.  The LockWord is currently encoded as
4963 //    (List, LOCKBIT:1).  We could also add a SUCCBIT or an explicit _succ variable
4964 //    to provide the usual futile-wakeup optimization.
4965 //    See RTStt for details.
4966 //
4967 
4968 
4969 const intptr_t LOCKBIT = 1;
4970 
4971 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4972   intptr_t w = Atomic::cmpxchg(Lock, (intptr_t)0, LOCKBIT);
4973   if (w == 0) return;
4974   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(Lock, w, w|LOCKBIT) == w) {
4975     return;
4976   }
4977 
4978   ParkEvent * const Self = Thread::current()->_MuxEvent;
4979   assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4980   for (;;) {
4981     int its = (os::is_MP() ? 100 : 0) + 1;
4982 
4983     // Optional spin phase: spin-then-park strategy
4984     while (--its >= 0) {
4985       w = *Lock;
4986       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(Lock, w, w|LOCKBIT) == w) {
4987         return;
4988       }
4989     }
4990 
4991     Self->reset();
4992     Self->OnList = intptr_t(Lock);
4993     // The following fence() isn't _strictly necessary as the subsequent
4994     // CAS() both serializes execution and ratifies the fetched *Lock value.
4995     OrderAccess::fence();
4996     for (;;) {
4997       w = *Lock;
4998       if ((w & LOCKBIT) == 0) {
4999         if (Atomic::cmpxchg(Lock, w, w|LOCKBIT) == w) {
5000           Self->OnList = 0;   // hygiene - allows stronger asserts
5001           return;
5002         }
5003         continue;      // Interference -- *Lock changed -- Just retry
5004       }
5005       assert(w & LOCKBIT, "invariant");
5006       Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
5007       if (Atomic::cmpxchg(Lock, w, intptr_t(Self)|LOCKBIT) == w) break;
5008     }
5009 
5010     while (Self->OnList != 0) {
5011       Self->park();
5012     }
5013   }
5014 }
5015 
5016 // Release() must extract a successor from the list and then wake that thread.
5017 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
5018 // similar to that used by ParkEvent::Allocate() and ::Release().  DMR-based
5019 // Release() would :
5020 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
5021 // (B) Extract a successor from the private list "in-hand"
5022 // (C) attempt to CAS() the residual back into *Lock over null.
5023 //     If there were any newly arrived threads and the CAS() would fail.
5024 //     In that case Release() would detach the RATs, re-merge the list in-hand
5025 //     with the RATs and repeat as needed.  Alternately, Release() might
5026 //     detach and extract a successor, but then pass the residual list to the wakee.
5027 //     The wakee would be responsible for reattaching and remerging before it
5028 //     competed for the lock.
5029 //
5030 // Both "pop" and DMR are immune from ABA corruption -- there can be
5031 // multiple concurrent pushers, but only one popper or detacher.
5032 // This implementation pops from the head of the list.  This is unfair,
5033 // but tends to provide excellent throughput as hot threads remain hot.
5034 // (We wake recently run threads first).
5035 //
5036 // All paths through muxRelease() will execute a CAS.
5037 // Release consistency -- We depend on the CAS in muxRelease() to provide full
5038 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
5039 // executed within the critical section are complete and globally visible before the
5040 // store (CAS) to the lock-word that releases the lock becomes globally visible.
5041 void Thread::muxRelease(volatile intptr_t * Lock)  {
5042   for (;;) {
5043     const intptr_t w = Atomic::cmpxchg(Lock, LOCKBIT, (intptr_t)0);
5044     assert(w & LOCKBIT, "invariant");
5045     if (w == LOCKBIT) return;
5046     ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
5047     assert(List != NULL, "invariant");
5048     assert(List->OnList == intptr_t(Lock), "invariant");
5049     ParkEvent * const nxt = List->ListNext;
5050     guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
5051 
5052     // The following CAS() releases the lock and pops the head element.
5053     // The CAS() also ratifies the previously fetched lock-word value.
5054     if (Atomic::cmpxchg(Lock, w, intptr_t(nxt)) != w) {
5055       continue;
5056     }
5057     List->OnList = 0;
5058     OrderAccess::fence();
5059     List->unpark();
5060     return;
5061   }
5062 }
5063 
5064 
5065 void Threads::verify() {
5066   ALL_JAVA_THREADS(p) {
5067     p->verify();
5068   }
5069   VMThread* thread = VMThread::vm_thread();
5070   if (thread != NULL) thread->verify();
5071 }
--- EOF ---