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