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_DECL 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   _num_nested_signal = 0;
 262   om_free_list = NULL;
 263   om_free_count = 0;
 264   om_free_provision = 32;
 265   om_in_use_list = NULL;
 266   om_in_use_count = 0;
 267 
 268 #ifdef ASSERT
 269   _visited_for_critical_count = false;
 270 #endif
 271 
 272   _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
 273                          Monitor::_safepoint_check_sometimes);
 274   _suspend_flags = 0;
 275 
 276   // thread-specific hashCode stream generator state - Marsaglia shift-xor form
 277   _hashStateX = os::random();
 278   _hashStateY = 842502087;
 279   _hashStateZ = 0x8767;    // (int)(3579807591LL & 0xffff) ;
 280   _hashStateW = 273326509;
 281 
 282   _OnTrap   = 0;
 283   _Stalled  = 0;
 284   _TypeTag  = 0x2BAD;
 285 
 286   // Many of the following fields are effectively final - immutable
 287   // Note that nascent threads can't use the Native Monitor-Mutex
 288   // construct until the _MutexEvent is initialized ...
 289   // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
 290   // we might instead use a stack of ParkEvents that we could provision on-demand.
 291   // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
 292   // and ::Release()
 293   _ParkEvent   = ParkEvent::Allocate(this);
 294   _MuxEvent    = ParkEvent::Allocate(this);
 295 
 296 #ifdef CHECK_UNHANDLED_OOPS
 297   if (CheckUnhandledOops) {
 298     _unhandled_oops = new UnhandledOops(this);
 299   }
 300 #endif // CHECK_UNHANDLED_OOPS
 301 #ifdef ASSERT
 302   if (UseBiasedLocking) {
 303     assert(is_aligned(this, markWord::biased_lock_alignment), "forced alignment of thread object failed");
 304     assert(this == _real_malloc_address ||
 305            this == align_up(_real_malloc_address, markWord::biased_lock_alignment),
 306            "bug in forced alignment of thread objects");
 307   }
 308 #endif // ASSERT
 309 
 310   // Notify the barrier set that a thread is being created. The initial
 311   // thread is created before the barrier set is available.  The call to
 312   // BarrierSet::on_thread_create() for this thread is therefore deferred
 313   // to BarrierSet::set_barrier_set().
 314   BarrierSet* const barrier_set = BarrierSet::barrier_set();
 315   if (barrier_set != NULL) {
 316     barrier_set->on_thread_create(this);
 317   } else {
 318     // Only the main thread should be created before the barrier set
 319     // and that happens just before Thread::current is set. No other thread
 320     // can attach as the VM is not created yet, so they can't execute this code.
 321     // If the main thread creates other threads before the barrier set that is an error.
 322     assert(Thread::current_or_null() == NULL, "creating thread before barrier set");
 323   }
 324 }
 325 
 326 void Thread::initialize_thread_current() {
 327 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 328   assert(_thr_current == NULL, "Thread::current already initialized");
 329   _thr_current = this;
 330 #endif
 331   assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
 332   ThreadLocalStorage::set_thread(this);
 333   assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
 334 }
 335 
 336 void Thread::clear_thread_current() {
 337   assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
 338 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 339   _thr_current = NULL;
 340 #endif
 341   ThreadLocalStorage::set_thread(NULL);
 342 }
 343 
 344 void Thread::record_stack_base_and_size() {
 345   // Note: at this point, Thread object is not yet initialized. Do not rely on
 346   // any members being initialized. Do not rely on Thread::current() being set.
 347   // If possible, refrain from doing anything which may crash or assert since
 348   // quite probably those crash dumps will be useless.
 349   set_stack_base(os::current_stack_base());
 350   set_stack_size(os::current_stack_size());
 351 
 352 #ifdef SOLARIS
 353   if (os::is_primordial_thread()) {
 354     os::Solaris::correct_stack_boundaries_for_primordial_thread(this);
 355   }
 356 #endif
 357 
 358   // Set stack limits after thread is initialized.
 359   if (is_Java_thread()) {
 360     ((JavaThread*) this)->set_stack_overflow_limit();
 361     ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
 362   }
 363 }
 364 
 365 #if INCLUDE_NMT
 366 void Thread::register_thread_stack_with_NMT() {
 367   MemTracker::record_thread_stack(stack_end(), stack_size());
 368 }
 369 #endif // INCLUDE_NMT
 370 
 371 void Thread::call_run() {
 372   DEBUG_ONLY(_run_state = CALL_RUN;)
 373 
 374   // At this point, Thread object should be fully initialized and
 375   // Thread::current() should be set.
 376 
 377   assert(Thread::current_or_null() != NULL, "current thread is unset");
 378   assert(Thread::current_or_null() == this, "current thread is wrong");
 379 
 380   // Perform common initialization actions
 381 
 382   register_thread_stack_with_NMT();
 383 
 384   JFR_ONLY(Jfr::on_thread_start(this);)
 385 
 386   log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
 387     PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
 388     os::current_thread_id(), p2i(stack_base() - stack_size()),
 389     p2i(stack_base()), stack_size()/1024);
 390 
 391   // Perform <ChildClass> initialization actions
 392   DEBUG_ONLY(_run_state = PRE_RUN;)
 393   this->pre_run();
 394 
 395   // Invoke <ChildClass>::run()
 396   DEBUG_ONLY(_run_state = RUN;)
 397   this->run();
 398   // Returned from <ChildClass>::run(). Thread finished.
 399 
 400   // Perform common tear-down actions
 401 
 402   assert(Thread::current_or_null() != NULL, "current thread is unset");
 403   assert(Thread::current_or_null() == this, "current thread is wrong");
 404 
 405   // Perform <ChildClass> tear-down actions
 406   DEBUG_ONLY(_run_state = POST_RUN;)
 407   this->post_run();
 408 
 409   // Note: at this point the thread object may already have deleted itself,
 410   // so from here on do not dereference *this*. Not all thread types currently
 411   // delete themselves when they terminate. But no thread should ever be deleted
 412   // asynchronously with respect to its termination - that is what _run_state can
 413   // be used to check.
 414 
 415   assert(Thread::current_or_null() == NULL, "current thread still present");
 416 }
 417 
 418 Thread::~Thread() {
 419 
 420   // Attached threads will remain in PRE_CALL_RUN, as will threads that don't actually
 421   // get started due to errors etc. Any active thread should at least reach post_run
 422   // before it is deleted (usually in post_run()).
 423   assert(_run_state == PRE_CALL_RUN ||
 424          _run_state == POST_RUN, "Active Thread deleted before post_run(): "
 425          "_run_state=%d", (int)_run_state);
 426 
 427   // Notify the barrier set that a thread is being destroyed. Note that a barrier
 428   // set might not be available if we encountered errors during bootstrapping.
 429   BarrierSet* const barrier_set = BarrierSet::barrier_set();
 430   if (barrier_set != NULL) {
 431     barrier_set->on_thread_destroy(this);
 432   }
 433 
 434   // stack_base can be NULL if the thread is never started or exited before
 435   // record_stack_base_and_size called. Although, we would like to ensure
 436   // that all started threads do call record_stack_base_and_size(), there is
 437   // not proper way to enforce that.
 438 #if INCLUDE_NMT
 439   if (_stack_base != NULL) {
 440     MemTracker::release_thread_stack(stack_end(), stack_size());
 441 #ifdef ASSERT
 442     set_stack_base(NULL);
 443 #endif
 444   }
 445 #endif // INCLUDE_NMT
 446 
 447   // deallocate data structures
 448   delete resource_area();
 449   // since the handle marks are using the handle area, we have to deallocated the root
 450   // handle mark before deallocating the thread's handle area,
 451   assert(last_handle_mark() != NULL, "check we have an element");
 452   delete last_handle_mark();
 453   assert(last_handle_mark() == NULL, "check we have reached the end");
 454 
 455   // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
 456   // We NULL out the fields for good hygiene.
 457   ParkEvent::Release(_ParkEvent); _ParkEvent   = NULL;
 458   ParkEvent::Release(_MuxEvent); _MuxEvent    = NULL;
 459 
 460   delete handle_area();
 461   delete metadata_handles();
 462 
 463   // SR_handler uses this as a termination indicator -
 464   // needs to happen before os::free_thread()
 465   delete _SR_lock;
 466   _SR_lock = NULL;
 467 
 468   // osthread() can be NULL, if creation of thread failed.
 469   if (osthread() != NULL) os::free_thread(osthread());
 470 
 471   // Clear Thread::current if thread is deleting itself and it has not
 472   // already been done. This must be done before the memory is deallocated.
 473   // Needed to ensure JNI correctly detects non-attached threads.
 474   if (this == Thread::current_or_null()) {
 475     Thread::clear_thread_current();
 476   }
 477 
 478   CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
 479 }
 480 
 481 #ifdef ASSERT
 482 // A JavaThread is considered "dangling" if it is not the current
 483 // thread, has been added the Threads list, the system is not at a
 484 // safepoint and the Thread is not "protected".
 485 //
 486 void Thread::check_for_dangling_thread_pointer(Thread *thread) {
 487   assert(!thread->is_Java_thread() || Thread::current() == thread ||
 488          !((JavaThread *) thread)->on_thread_list() ||
 489          SafepointSynchronize::is_at_safepoint() ||
 490          ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread),
 491          "possibility of dangling Thread pointer");
 492 }
 493 #endif
 494 
 495 ThreadPriority Thread::get_priority(const Thread* const thread) {
 496   ThreadPriority priority;
 497   // Can return an error!
 498   (void)os::get_priority(thread, priority);
 499   assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
 500   return priority;
 501 }
 502 
 503 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
 504   debug_only(check_for_dangling_thread_pointer(thread);)
 505   // Can return an error!
 506   (void)os::set_priority(thread, priority);
 507 }
 508 
 509 
 510 void Thread::start(Thread* thread) {
 511   // Start is different from resume in that its safety is guaranteed by context or
 512   // being called from a Java method synchronized on the Thread object.
 513   if (!DisableStartThread) {
 514     if (thread->is_Java_thread()) {
 515       // Initialize the thread state to RUNNABLE before starting this thread.
 516       // Can not set it after the thread started because we do not know the
 517       // exact thread state at that time. It could be in MONITOR_WAIT or
 518       // in SLEEPING or some other state.
 519       java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
 520                                           java_lang_Thread::RUNNABLE);
 521     }
 522     os::start_thread(thread);
 523   }
 524 }
 525 
 526 // Enqueue a VM_Operation to do the job for us - sometime later
 527 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
 528   VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
 529   VMThread::execute(vm_stop);
 530 }
 531 
 532 
 533 // Check if an external suspend request has completed (or has been
 534 // cancelled). Returns true if the thread is externally suspended and
 535 // false otherwise.
 536 //
 537 // The bits parameter returns information about the code path through
 538 // the routine. Useful for debugging:
 539 //
 540 // set in is_ext_suspend_completed():
 541 // 0x00000001 - routine was entered
 542 // 0x00000010 - routine return false at end
 543 // 0x00000100 - thread exited (return false)
 544 // 0x00000200 - suspend request cancelled (return false)
 545 // 0x00000400 - thread suspended (return true)
 546 // 0x00001000 - thread is in a suspend equivalent state (return true)
 547 // 0x00002000 - thread is native and walkable (return true)
 548 // 0x00004000 - thread is native_trans and walkable (needed retry)
 549 //
 550 // set in wait_for_ext_suspend_completion():
 551 // 0x00010000 - routine was entered
 552 // 0x00020000 - suspend request cancelled before loop (return false)
 553 // 0x00040000 - thread suspended before loop (return true)
 554 // 0x00080000 - suspend request cancelled in loop (return false)
 555 // 0x00100000 - thread suspended in loop (return true)
 556 // 0x00200000 - suspend not completed during retry loop (return false)
 557 
 558 // Helper class for tracing suspend wait debug bits.
 559 //
 560 // 0x00000100 indicates that the target thread exited before it could
 561 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
 562 // 0x00080000 each indicate a cancelled suspend request so they don't
 563 // count as wait failures either.
 564 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
 565 
 566 class TraceSuspendDebugBits : public StackObj {
 567  private:
 568   JavaThread * jt;
 569   bool         is_wait;
 570   bool         called_by_wait;  // meaningful when !is_wait
 571   uint32_t *   bits;
 572 
 573  public:
 574   TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
 575                         uint32_t *_bits) {
 576     jt             = _jt;
 577     is_wait        = _is_wait;
 578     called_by_wait = _called_by_wait;
 579     bits           = _bits;
 580   }
 581 
 582   ~TraceSuspendDebugBits() {
 583     if (!is_wait) {
 584 #if 1
 585       // By default, don't trace bits for is_ext_suspend_completed() calls.
 586       // That trace is very chatty.
 587       return;
 588 #else
 589       if (!called_by_wait) {
 590         // If tracing for is_ext_suspend_completed() is enabled, then only
 591         // trace calls to it from wait_for_ext_suspend_completion()
 592         return;
 593       }
 594 #endif
 595     }
 596 
 597     if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
 598       if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
 599         MutexLocker ml(Threads_lock);  // needed for get_thread_name()
 600         ResourceMark rm;
 601 
 602         tty->print_cr(
 603                       "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
 604                       jt->get_thread_name(), *bits);
 605 
 606         guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
 607       }
 608     }
 609   }
 610 };
 611 #undef DEBUG_FALSE_BITS
 612 
 613 
 614 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
 615                                           uint32_t *bits) {
 616   TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
 617 
 618   bool did_trans_retry = false;  // only do thread_in_native_trans retry once
 619   bool do_trans_retry;           // flag to force the retry
 620 
 621   *bits |= 0x00000001;
 622 
 623   do {
 624     do_trans_retry = false;
 625 
 626     if (is_exiting()) {
 627       // Thread is in the process of exiting. This is always checked
 628       // first to reduce the risk of dereferencing a freed JavaThread.
 629       *bits |= 0x00000100;
 630       return false;
 631     }
 632 
 633     if (!is_external_suspend()) {
 634       // Suspend request is cancelled. This is always checked before
 635       // is_ext_suspended() to reduce the risk of a rogue resume
 636       // confusing the thread that made the suspend request.
 637       *bits |= 0x00000200;
 638       return false;
 639     }
 640 
 641     if (is_ext_suspended()) {
 642       // thread is suspended
 643       *bits |= 0x00000400;
 644       return true;
 645     }
 646 
 647     // Now that we no longer do hard suspends of threads running
 648     // native code, the target thread can be changing thread state
 649     // while we are in this routine:
 650     //
 651     //   _thread_in_native -> _thread_in_native_trans -> _thread_blocked
 652     //
 653     // We save a copy of the thread state as observed at this moment
 654     // and make our decision about suspend completeness based on the
 655     // copy. This closes the race where the thread state is seen as
 656     // _thread_in_native_trans in the if-thread_blocked check, but is
 657     // seen as _thread_blocked in if-thread_in_native_trans check.
 658     JavaThreadState save_state = thread_state();
 659 
 660     if (save_state == _thread_blocked && is_suspend_equivalent()) {
 661       // If the thread's state is _thread_blocked and this blocking
 662       // condition is known to be equivalent to a suspend, then we can
 663       // consider the thread to be externally suspended. This means that
 664       // the code that sets _thread_blocked has been modified to do
 665       // self-suspension if the blocking condition releases. We also
 666       // used to check for CONDVAR_WAIT here, but that is now covered by
 667       // the _thread_blocked with self-suspension check.
 668       //
 669       // Return true since we wouldn't be here unless there was still an
 670       // external suspend request.
 671       *bits |= 0x00001000;
 672       return true;
 673     } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
 674       // Threads running native code will self-suspend on native==>VM/Java
 675       // transitions. If its stack is walkable (should always be the case
 676       // unless this function is called before the actual java_suspend()
 677       // call), then the wait is done.
 678       *bits |= 0x00002000;
 679       return true;
 680     } else if (!called_by_wait && !did_trans_retry &&
 681                save_state == _thread_in_native_trans &&
 682                frame_anchor()->walkable()) {
 683       // The thread is transitioning from thread_in_native to another
 684       // thread state. check_safepoint_and_suspend_for_native_trans()
 685       // will force the thread to self-suspend. If it hasn't gotten
 686       // there yet we may have caught the thread in-between the native
 687       // code check above and the self-suspend. Lucky us. If we were
 688       // called by wait_for_ext_suspend_completion(), then it
 689       // will be doing the retries so we don't have to.
 690       //
 691       // Since we use the saved thread state in the if-statement above,
 692       // there is a chance that the thread has already transitioned to
 693       // _thread_blocked by the time we get here. In that case, we will
 694       // make a single unnecessary pass through the logic below. This
 695       // doesn't hurt anything since we still do the trans retry.
 696 
 697       *bits |= 0x00004000;
 698 
 699       // Once the thread leaves thread_in_native_trans for another
 700       // thread state, we break out of this retry loop. We shouldn't
 701       // need this flag to prevent us from getting back here, but
 702       // sometimes paranoia is good.
 703       did_trans_retry = true;
 704 
 705       // We wait for the thread to transition to a more usable state.
 706       for (int i = 1; i <= SuspendRetryCount; i++) {
 707         // We used to do an "os::yield_all(i)" call here with the intention
 708         // that yielding would increase on each retry. However, the parameter
 709         // is ignored on Linux which means the yield didn't scale up. Waiting
 710         // on the SR_lock below provides a much more predictable scale up for
 711         // the delay. It also provides a simple/direct point to check for any
 712         // safepoint requests from the VMThread
 713 
 714         // temporarily drops SR_lock while doing wait with safepoint check
 715         // (if we're a JavaThread - the WatcherThread can also call this)
 716         // and increase delay with each retry
 717         if (Thread::current()->is_Java_thread()) {
 718           SR_lock()->wait(i * delay);
 719         } else {
 720           SR_lock()->wait_without_safepoint_check(i * delay);
 721         }
 722 
 723         // check the actual thread state instead of what we saved above
 724         if (thread_state() != _thread_in_native_trans) {
 725           // the thread has transitioned to another thread state so
 726           // try all the checks (except this one) one more time.
 727           do_trans_retry = true;
 728           break;
 729         }
 730       } // end retry loop
 731 
 732 
 733     }
 734   } while (do_trans_retry);
 735 
 736   *bits |= 0x00000010;
 737   return false;
 738 }
 739 
 740 // Wait for an external suspend request to complete (or be cancelled).
 741 // Returns true if the thread is externally suspended and false otherwise.
 742 //
 743 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
 744                                                  uint32_t *bits) {
 745   TraceSuspendDebugBits tsdb(this, true /* is_wait */,
 746                              false /* !called_by_wait */, bits);
 747 
 748   // local flag copies to minimize SR_lock hold time
 749   bool is_suspended;
 750   bool pending;
 751   uint32_t reset_bits;
 752 
 753   // set a marker so is_ext_suspend_completed() knows we are the caller
 754   *bits |= 0x00010000;
 755 
 756   // We use reset_bits to reinitialize the bits value at the top of
 757   // each retry loop. This allows the caller to make use of any
 758   // unused bits for their own marking purposes.
 759   reset_bits = *bits;
 760 
 761   {
 762     MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
 763     is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 764                                             delay, bits);
 765     pending = is_external_suspend();
 766   }
 767   // must release SR_lock to allow suspension to complete
 768 
 769   if (!pending) {
 770     // A cancelled suspend request is the only false return from
 771     // is_ext_suspend_completed() that keeps us from entering the
 772     // retry loop.
 773     *bits |= 0x00020000;
 774     return false;
 775   }
 776 
 777   if (is_suspended) {
 778     *bits |= 0x00040000;
 779     return true;
 780   }
 781 
 782   for (int i = 1; i <= retries; i++) {
 783     *bits = reset_bits;  // reinit to only track last retry
 784 
 785     // We used to do an "os::yield_all(i)" call here with the intention
 786     // that yielding would increase on each retry. However, the parameter
 787     // is ignored on Linux which means the yield didn't scale up. Waiting
 788     // on the SR_lock below provides a much more predictable scale up for
 789     // the delay. It also provides a simple/direct point to check for any
 790     // safepoint requests from the VMThread
 791 
 792     {
 793       Thread* t = Thread::current();
 794       MonitorLocker ml(SR_lock(),
 795                        t->is_Java_thread() ? Mutex::_safepoint_check_flag : Mutex::_no_safepoint_check_flag);
 796       // wait with safepoint check (if we're a JavaThread - the WatcherThread
 797       // can also call this)  and increase delay with each retry
 798       ml.wait(i * delay);
 799 
 800       is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 801                                               delay, bits);
 802 
 803       // It is possible for the external suspend request to be cancelled
 804       // (by a resume) before the actual suspend operation is completed.
 805       // Refresh our local copy to see if we still need to wait.
 806       pending = is_external_suspend();
 807     }
 808 
 809     if (!pending) {
 810       // A cancelled suspend request is the only false return from
 811       // is_ext_suspend_completed() that keeps us from staying in the
 812       // retry loop.
 813       *bits |= 0x00080000;
 814       return false;
 815     }
 816 
 817     if (is_suspended) {
 818       *bits |= 0x00100000;
 819       return true;
 820     }
 821   } // end retry loop
 822 
 823   // thread did not suspend after all our retries
 824   *bits |= 0x00200000;
 825   return false;
 826 }
 827 
 828 // Called from API entry points which perform stack walking. If the
 829 // associated JavaThread is the current thread, then wait_for_suspend
 830 // is not used. Otherwise, it determines if we should wait for the
 831 // "other" thread to complete external suspension. (NOTE: in future
 832 // releases the suspension mechanism should be reimplemented so this
 833 // is not necessary.)
 834 //
 835 bool
 836 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) {
 837   if (this != JavaThread::current()) {
 838     // "other" threads require special handling.
 839     if (wait_for_suspend) {
 840       // We are allowed to wait for the external suspend to complete
 841       // so give the other thread a chance to get suspended.
 842       if (!wait_for_ext_suspend_completion(SuspendRetryCount,
 843                                            SuspendRetryDelay, bits)) {
 844         // Didn't make it so let the caller know.
 845         return false;
 846       }
 847     }
 848     // We aren't allowed to wait for the external suspend to complete
 849     // so if the other thread isn't externally suspended we need to
 850     // let the caller know.
 851     else if (!is_ext_suspend_completed_with_lock(bits)) {
 852       return false;
 853     }
 854   }
 855 
 856   return true;
 857 }
 858 
 859 void Thread::interrupt(Thread* thread) {
 860   debug_only(check_for_dangling_thread_pointer(thread);)
 861   os::interrupt(thread);
 862 }
 863 
 864 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
 865   debug_only(check_for_dangling_thread_pointer(thread);)
 866   // Note:  If clear_interrupted==false, this simply fetches and
 867   // returns the value of the field osthread()->interrupted().
 868   return os::is_interrupted(thread, clear_interrupted);
 869 }
 870 
 871 
 872 // GC Support
 873 bool Thread::claim_par_threads_do(uintx claim_token) {
 874   uintx token = _threads_do_token;
 875   if (token != claim_token) {
 876     uintx res = Atomic::cmpxchg(claim_token, &_threads_do_token, token);
 877     if (res == token) {
 878       return true;
 879     }
 880     guarantee(res == claim_token, "invariant");
 881   }
 882   return false;
 883 }
 884 
 885 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
 886   active_handles()->oops_do(f);
 887   // Do oop for ThreadShadow
 888   f->do_oop((oop*)&_pending_exception);
 889   handle_area()->oops_do(f);
 890 
 891   // We scan thread local monitor lists here, and the remaining global
 892   // monitors in ObjectSynchronizer::oops_do().
 893   ObjectSynchronizer::thread_local_used_oops_do(this, f);
 894 }
 895 
 896 void Thread::metadata_handles_do(void f(Metadata*)) {
 897   // Only walk the Handles in Thread.
 898   if (metadata_handles() != NULL) {
 899     for (int i = 0; i< metadata_handles()->length(); i++) {
 900       f(metadata_handles()->at(i));
 901     }
 902   }
 903 }
 904 
 905 void Thread::print_on(outputStream* st, bool print_extended_info) const {
 906   // get_priority assumes osthread initialized
 907   if (osthread() != NULL) {
 908     int os_prio;
 909     if (os::get_native_priority(this, &os_prio) == OS_OK) {
 910       st->print("os_prio=%d ", os_prio);
 911     }
 912 
 913     st->print("cpu=%.2fms ",
 914               os::thread_cpu_time(const_cast<Thread*>(this), true) / 1000000.0
 915               );
 916     st->print("elapsed=%.2fs ",
 917               _statistical_info.getElapsedTime() / 1000.0
 918               );
 919     if (is_Java_thread() && (PrintExtendedThreadInfo || print_extended_info)) {
 920       size_t allocated_bytes = (size_t) const_cast<Thread*>(this)->cooked_allocated_bytes();
 921       st->print("allocated=" SIZE_FORMAT "%s ",
 922                 byte_size_in_proper_unit(allocated_bytes),
 923                 proper_unit_for_byte_size(allocated_bytes)
 924                 );
 925       st->print("defined_classes=" INT64_FORMAT " ", _statistical_info.getDefineClassCount());
 926     }
 927 
 928     st->print("tid=" INTPTR_FORMAT " ", p2i(this));
 929     osthread()->print_on(st);
 930   }
 931   ThreadsSMRSupport::print_info_on(this, st);
 932   st->print(" ");
 933   debug_only(if (WizardMode) print_owned_locks_on(st);)
 934 }
 935 
 936 void Thread::print() const { print_on(tty); }
 937 
 938 // Thread::print_on_error() is called by fatal error handler. Don't use
 939 // any lock or allocate memory.
 940 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
 941   assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
 942 
 943   if (is_VM_thread())                 { st->print("VMThread"); }
 944   else if (is_GC_task_thread())       { st->print("GCTaskThread"); }
 945   else if (is_Watcher_thread())       { st->print("WatcherThread"); }
 946   else if (is_ConcurrentGC_thread())  { st->print("ConcurrentGCThread"); }
 947   else                                { st->print("Thread"); }
 948 
 949   if (is_Named_thread()) {
 950     st->print(" \"%s\"", name());
 951   }
 952 
 953   st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
 954             p2i(stack_end()), p2i(stack_base()));
 955 
 956   if (osthread()) {
 957     st->print(" [id=%d]", osthread()->thread_id());
 958   }
 959 
 960   ThreadsSMRSupport::print_info_on(this, st);
 961 }
 962 
 963 void Thread::print_value_on(outputStream* st) const {
 964   if (is_Named_thread()) {
 965     st->print(" \"%s\" ", name());
 966   }
 967   st->print(INTPTR_FORMAT, p2i(this));   // print address
 968 }
 969 
 970 #ifdef ASSERT
 971 void Thread::print_owned_locks_on(outputStream* st) const {
 972   Mutex* cur = _owned_locks;
 973   if (cur == NULL) {
 974     st->print(" (no locks) ");
 975   } else {
 976     st->print_cr(" Locks owned:");
 977     while (cur) {
 978       cur->print_on(st);
 979       cur = cur->next();
 980     }
 981   }
 982 }
 983 
 984 // Checks safepoint allowed and clears unhandled oops at potential safepoints.
 985 void Thread::check_possible_safepoint() {
 986   if (!is_Java_thread()) return;
 987 
 988   if (_no_safepoint_count > 0) {
 989     fatal("Possible safepoint reached by thread that does not allow it");
 990   }
 991 #ifdef CHECK_UNHANDLED_OOPS
 992   // Clear unhandled oops in JavaThreads so we get a crash right away.
 993   clear_unhandled_oops();
 994 #endif // CHECK_UNHANDLED_OOPS
 995 }
 996 
 997 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially
 998 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that
 999 // no locks which allow_vm_block's are held
1000 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
1001   if (!is_Java_thread()) return;
1002 
1003   check_possible_safepoint();
1004 
1005   if (((JavaThread*)this)->thread_state() != _thread_in_vm) {
1006     fatal("LEAF method calling lock?");
1007   }
1008 
1009   if (potential_vm_operation && !Universe::is_bootstrapping()) {
1010     // Make sure we do not hold any locks that the VM thread also uses.
1011     // This could potentially lead to deadlocks
1012     for (Mutex* cur = _owned_locks; cur; cur = cur->next()) {
1013       // Threads_lock is special, since the safepoint synchronization will not start before this is
1014       // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
1015       // since it is used to transfer control between JavaThreads and the VMThread
1016       // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
1017       if ((cur->allow_vm_block() &&
1018            cur != Threads_lock &&
1019            cur != Compile_lock &&               // Temporary: should not be necessary when we get separate compilation
1020            cur != VMOperationRequest_lock &&
1021            cur != VMOperationQueue_lock) ||
1022            cur->rank() == Mutex::special) {
1023         fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
1024       }
1025     }
1026   }
1027 
1028   if (GCALotAtAllSafepoints) {
1029     // We could enter a safepoint here and thus have a gc
1030     InterfaceSupport::check_gc_alot();
1031   }
1032 }
1033 #endif // ASSERT
1034 
1035 bool Thread::is_in_stack(address adr) const {
1036   assert(Thread::current() == this, "is_in_stack can only be called from current thread");
1037   address end = os::current_stack_pointer();
1038   // Allow non Java threads to call this without stack_base
1039   if (_stack_base == NULL) return true;
1040   if (stack_base() >= adr && adr >= end) return true;
1041 
1042   return false;
1043 }
1044 
1045 bool Thread::is_in_usable_stack(address adr) const {
1046   size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
1047   size_t usable_stack_size = _stack_size - stack_guard_size;
1048 
1049   return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
1050 }
1051 
1052 
1053 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
1054 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
1055 // used for compilation in the future. If that change is made, the need for these methods
1056 // should be revisited, and they should be removed if possible.
1057 
1058 bool Thread::is_lock_owned(address adr) const {
1059   return on_local_stack(adr);
1060 }
1061 
1062 bool Thread::set_as_starting_thread() {
1063   assert(_starting_thread == NULL, "already initialized: "
1064          "_starting_thread=" INTPTR_FORMAT, p2i(_starting_thread));
1065   // NOTE: this must be called inside the main thread.
1066   DEBUG_ONLY(_starting_thread = this;)
1067   return os::create_main_thread((JavaThread*)this);
1068 }
1069 
1070 static void initialize_class(Symbol* class_name, TRAPS) {
1071   Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
1072   InstanceKlass::cast(klass)->initialize(CHECK);
1073 }
1074 
1075 
1076 // Creates the initial ThreadGroup
1077 static Handle create_initial_thread_group(TRAPS) {
1078   Handle system_instance = JavaCalls::construct_new_instance(
1079                             SystemDictionary::ThreadGroup_klass(),
1080                             vmSymbols::void_method_signature(),
1081                             CHECK_NH);
1082   Universe::set_system_thread_group(system_instance());
1083 
1084   Handle string = java_lang_String::create_from_str("main", CHECK_NH);
1085   Handle main_instance = JavaCalls::construct_new_instance(
1086                             SystemDictionary::ThreadGroup_klass(),
1087                             vmSymbols::threadgroup_string_void_signature(),
1088                             system_instance,
1089                             string,
1090                             CHECK_NH);
1091   return main_instance;
1092 }
1093 
1094 // Creates the initial Thread
1095 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
1096                                  TRAPS) {
1097   InstanceKlass* ik = SystemDictionary::Thread_klass();
1098   assert(ik->is_initialized(), "must be");
1099   instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
1100 
1101   // Cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1102   // constructor calls Thread.current(), which must be set here for the
1103   // initial thread.
1104   java_lang_Thread::set_thread(thread_oop(), thread);
1105   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1106   thread->set_threadObj(thread_oop());
1107 
1108   Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1109 
1110   JavaValue result(T_VOID);
1111   JavaCalls::call_special(&result, thread_oop,
1112                           ik,
1113                           vmSymbols::object_initializer_name(),
1114                           vmSymbols::threadgroup_string_void_signature(),
1115                           thread_group,
1116                           string,
1117                           CHECK_NULL);
1118   return thread_oop();
1119 }
1120 
1121 char java_runtime_name[128] = "";
1122 char java_runtime_version[128] = "";
1123 
1124 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1125 static const char* get_java_runtime_name(TRAPS) {
1126   Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1127                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1128   fieldDescriptor fd;
1129   bool found = k != NULL &&
1130                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1131                                                         vmSymbols::string_signature(), &fd);
1132   if (found) {
1133     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1134     if (name_oop == NULL) {
1135       return NULL;
1136     }
1137     const char* name = java_lang_String::as_utf8_string(name_oop,
1138                                                         java_runtime_name,
1139                                                         sizeof(java_runtime_name));
1140     return name;
1141   } else {
1142     return NULL;
1143   }
1144 }
1145 
1146 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1147 static const char* get_java_runtime_version(TRAPS) {
1148   Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1149                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1150   fieldDescriptor fd;
1151   bool found = k != NULL &&
1152                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1153                                                         vmSymbols::string_signature(), &fd);
1154   if (found) {
1155     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1156     if (name_oop == NULL) {
1157       return NULL;
1158     }
1159     const char* name = java_lang_String::as_utf8_string(name_oop,
1160                                                         java_runtime_version,
1161                                                         sizeof(java_runtime_version));
1162     return name;
1163   } else {
1164     return NULL;
1165   }
1166 }
1167 
1168 // General purpose hook into Java code, run once when the VM is initialized.
1169 // The Java library method itself may be changed independently from the VM.
1170 static void call_postVMInitHook(TRAPS) {
1171   Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1172   if (klass != NULL) {
1173     JavaValue result(T_VOID);
1174     JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1175                            vmSymbols::void_method_signature(),
1176                            CHECK);
1177   }
1178 }
1179 
1180 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1181                                     bool daemon, TRAPS) {
1182   assert(thread_group.not_null(), "thread group should be specified");
1183   assert(threadObj() == NULL, "should only create Java thread object once");
1184 
1185   InstanceKlass* ik = SystemDictionary::Thread_klass();
1186   assert(ik->is_initialized(), "must be");
1187   instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1188 
1189   // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon.
1190   // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1191   // constructor calls Thread.current(), which must be set here.
1192   java_lang_Thread::set_thread(thread_oop(), this);
1193   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1194   set_threadObj(thread_oop());
1195 
1196   JavaValue result(T_VOID);
1197   if (thread_name != NULL) {
1198     Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1199     // Thread gets assigned specified name and null target
1200     JavaCalls::call_special(&result,
1201                             thread_oop,
1202                             ik,
1203                             vmSymbols::object_initializer_name(),
1204                             vmSymbols::threadgroup_string_void_signature(),
1205                             thread_group,
1206                             name,
1207                             THREAD);
1208   } else {
1209     // Thread gets assigned name "Thread-nnn" and null target
1210     // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1211     JavaCalls::call_special(&result,
1212                             thread_oop,
1213                             ik,
1214                             vmSymbols::object_initializer_name(),
1215                             vmSymbols::threadgroup_runnable_void_signature(),
1216                             thread_group,
1217                             Handle(),
1218                             THREAD);
1219   }
1220 
1221 
1222   if (daemon) {
1223     java_lang_Thread::set_daemon(thread_oop());
1224   }
1225 
1226   if (HAS_PENDING_EXCEPTION) {
1227     return;
1228   }
1229 
1230   Klass* group =  SystemDictionary::ThreadGroup_klass();
1231   Handle threadObj(THREAD, this->threadObj());
1232 
1233   JavaCalls::call_special(&result,
1234                           thread_group,
1235                           group,
1236                           vmSymbols::add_method_name(),
1237                           vmSymbols::thread_void_signature(),
1238                           threadObj,          // Arg 1
1239                           THREAD);
1240 }
1241 
1242 // List of all NonJavaThreads and safe iteration over that list.
1243 
1244 class NonJavaThread::List {
1245 public:
1246   NonJavaThread* volatile _head;
1247   SingleWriterSynchronizer _protect;
1248 
1249   List() : _head(NULL), _protect() {}
1250 };
1251 
1252 NonJavaThread::List NonJavaThread::_the_list;
1253 
1254 NonJavaThread::Iterator::Iterator() :
1255   _protect_enter(_the_list._protect.enter()),
1256   _current(OrderAccess::load_acquire(&_the_list._head))
1257 {}
1258 
1259 NonJavaThread::Iterator::~Iterator() {
1260   _the_list._protect.exit(_protect_enter);
1261 }
1262 
1263 void NonJavaThread::Iterator::step() {
1264   assert(!end(), "precondition");
1265   _current = OrderAccess::load_acquire(&_current->_next);
1266 }
1267 
1268 NonJavaThread::NonJavaThread() : Thread(), _next(NULL) {
1269   assert(BarrierSet::barrier_set() != NULL, "NonJavaThread created too soon!");
1270 }
1271 
1272 NonJavaThread::~NonJavaThread() { }
1273 
1274 void NonJavaThread::add_to_the_list() {
1275   MutexLocker ml(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1276   // Initialize BarrierSet-related data before adding to list.
1277   BarrierSet::barrier_set()->on_thread_attach(this);
1278   OrderAccess::release_store(&_next, _the_list._head);
1279   OrderAccess::release_store(&_the_list._head, this);
1280 }
1281 
1282 void NonJavaThread::remove_from_the_list() {
1283   {
1284     MutexLocker ml(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1285     // Cleanup BarrierSet-related data before removing from list.
1286     BarrierSet::barrier_set()->on_thread_detach(this);
1287     NonJavaThread* volatile* p = &_the_list._head;
1288     for (NonJavaThread* t = *p; t != NULL; p = &t->_next, t = *p) {
1289       if (t == this) {
1290         *p = _next;
1291         break;
1292       }
1293     }
1294   }
1295   // Wait for any in-progress iterators.  Concurrent synchronize is not
1296   // allowed, so do it while holding a dedicated lock.  Outside and distinct
1297   // from NJTList_lock in case an iteration attempts to lock it.
1298   MutexLocker ml(NonJavaThreadsListSync_lock, Mutex::_no_safepoint_check_flag);
1299   _the_list._protect.synchronize();
1300   _next = NULL;                 // Safe to drop the link now.
1301 }
1302 
1303 void NonJavaThread::pre_run() {
1304   add_to_the_list();
1305 
1306   // This is slightly odd in that NamedThread is a subclass, but
1307   // in fact name() is defined in Thread
1308   assert(this->name() != NULL, "thread name was not set before it was started");
1309   this->set_native_thread_name(this->name());
1310 }
1311 
1312 void NonJavaThread::post_run() {
1313   JFR_ONLY(Jfr::on_thread_exit(this);)
1314   remove_from_the_list();
1315   // Ensure thread-local-storage is cleared before termination.
1316   Thread::clear_thread_current();
1317 }
1318 
1319 // NamedThread --  non-JavaThread subclasses with multiple
1320 // uniquely named instances should derive from this.
1321 NamedThread::NamedThread() :
1322   NonJavaThread(),
1323   _name(NULL),
1324   _processed_thread(NULL),
1325   _gc_id(GCId::undefined())
1326 {}
1327 
1328 NamedThread::~NamedThread() {
1329   FREE_C_HEAP_ARRAY(char, _name);
1330 }
1331 
1332 void NamedThread::set_name(const char* format, ...) {
1333   guarantee(_name == NULL, "Only get to set name once.");
1334   _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1335   va_list ap;
1336   va_start(ap, format);
1337   jio_vsnprintf(_name, max_name_len, format, ap);
1338   va_end(ap);
1339 }
1340 
1341 void NamedThread::print_on(outputStream* st) const {
1342   st->print("\"%s\" ", name());
1343   Thread::print_on(st);
1344   st->cr();
1345 }
1346 
1347 
1348 // ======= WatcherThread ========
1349 
1350 // The watcher thread exists to simulate timer interrupts.  It should
1351 // be replaced by an abstraction over whatever native support for
1352 // timer interrupts exists on the platform.
1353 
1354 WatcherThread* WatcherThread::_watcher_thread   = NULL;
1355 bool WatcherThread::_startable = false;
1356 volatile bool  WatcherThread::_should_terminate = false;
1357 
1358 WatcherThread::WatcherThread() : NonJavaThread() {
1359   assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1360   if (os::create_thread(this, os::watcher_thread)) {
1361     _watcher_thread = this;
1362 
1363     // Set the watcher thread to the highest OS priority which should not be
1364     // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1365     // is created. The only normal thread using this priority is the reference
1366     // handler thread, which runs for very short intervals only.
1367     // If the VMThread's priority is not lower than the WatcherThread profiling
1368     // will be inaccurate.
1369     os::set_priority(this, MaxPriority);
1370     if (!DisableStartThread) {
1371       os::start_thread(this);
1372     }
1373   }
1374 }
1375 
1376 int WatcherThread::sleep() const {
1377   // The WatcherThread does not participate in the safepoint protocol
1378   // for the PeriodicTask_lock because it is not a JavaThread.
1379   MonitorLocker ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1380 
1381   if (_should_terminate) {
1382     // check for termination before we do any housekeeping or wait
1383     return 0;  // we did not sleep.
1384   }
1385 
1386   // remaining will be zero if there are no tasks,
1387   // causing the WatcherThread to sleep until a task is
1388   // enrolled
1389   int remaining = PeriodicTask::time_to_wait();
1390   int time_slept = 0;
1391 
1392   // we expect this to timeout - we only ever get unparked when
1393   // we should terminate or when a new task has been enrolled
1394   OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1395 
1396   jlong time_before_loop = os::javaTimeNanos();
1397 
1398   while (true) {
1399     bool timedout = ml.wait(remaining);
1400     jlong now = os::javaTimeNanos();
1401 
1402     if (remaining == 0) {
1403       // if we didn't have any tasks we could have waited for a long time
1404       // consider the time_slept zero and reset time_before_loop
1405       time_slept = 0;
1406       time_before_loop = now;
1407     } else {
1408       // need to recalculate since we might have new tasks in _tasks
1409       time_slept = (int) ((now - time_before_loop) / 1000000);
1410     }
1411 
1412     // Change to task list or spurious wakeup of some kind
1413     if (timedout || _should_terminate) {
1414       break;
1415     }
1416 
1417     remaining = PeriodicTask::time_to_wait();
1418     if (remaining == 0) {
1419       // Last task was just disenrolled so loop around and wait until
1420       // another task gets enrolled
1421       continue;
1422     }
1423 
1424     remaining -= time_slept;
1425     if (remaining <= 0) {
1426       break;
1427     }
1428   }
1429 
1430   return time_slept;
1431 }
1432 
1433 void WatcherThread::run() {
1434   assert(this == watcher_thread(), "just checking");
1435 
1436   this->set_active_handles(JNIHandleBlock::allocate_block());
1437   while (true) {
1438     assert(watcher_thread() == Thread::current(), "thread consistency check");
1439     assert(watcher_thread() == this, "thread consistency check");
1440 
1441     // Calculate how long it'll be until the next PeriodicTask work
1442     // should be done, and sleep that amount of time.
1443     int time_waited = sleep();
1444 
1445     if (VMError::is_error_reported()) {
1446       // A fatal error has happened, the error handler(VMError::report_and_die)
1447       // should abort JVM after creating an error log file. However in some
1448       // rare cases, the error handler itself might deadlock. Here periodically
1449       // check for error reporting timeouts, and if it happens, just proceed to
1450       // abort the VM.
1451 
1452       // This code is in WatcherThread because WatcherThread wakes up
1453       // periodically so the fatal error handler doesn't need to do anything;
1454       // also because the WatcherThread is less likely to crash than other
1455       // threads.
1456 
1457       for (;;) {
1458         // Note: we use naked sleep in this loop because we want to avoid using
1459         // any kind of VM infrastructure which may be broken at this point.
1460         if (VMError::check_timeout()) {
1461           // We hit error reporting timeout. Error reporting was interrupted and
1462           // will be wrapping things up now (closing files etc). Give it some more
1463           // time, then quit the VM.
1464           os::naked_short_sleep(200);
1465           // Print a message to stderr.
1466           fdStream err(defaultStream::output_fd());
1467           err.print_raw_cr("# [ timer expired, abort... ]");
1468           // skip atexit/vm_exit/vm_abort hooks
1469           os::die();
1470         }
1471 
1472         // Wait a second, then recheck for timeout.
1473         os::naked_short_sleep(999);
1474       }
1475     }
1476 
1477     if (_should_terminate) {
1478       // check for termination before posting the next tick
1479       break;
1480     }
1481 
1482     PeriodicTask::real_time_tick(time_waited);
1483   }
1484 
1485   // Signal that it is terminated
1486   {
1487     MutexLocker mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1488     _watcher_thread = NULL;
1489     Terminator_lock->notify_all();
1490   }
1491 }
1492 
1493 void WatcherThread::start() {
1494   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1495 
1496   if (watcher_thread() == NULL && _startable) {
1497     _should_terminate = false;
1498     // Create the single instance of WatcherThread
1499     new WatcherThread();
1500   }
1501 }
1502 
1503 void WatcherThread::make_startable() {
1504   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1505   _startable = true;
1506 }
1507 
1508 void WatcherThread::stop() {
1509   {
1510     // Follow normal safepoint aware lock enter protocol since the
1511     // WatcherThread is stopped by another JavaThread.
1512     MutexLocker ml(PeriodicTask_lock);
1513     _should_terminate = true;
1514 
1515     WatcherThread* watcher = watcher_thread();
1516     if (watcher != NULL) {
1517       // unpark the WatcherThread so it can see that it should terminate
1518       watcher->unpark();
1519     }
1520   }
1521 
1522   MonitorLocker mu(Terminator_lock);
1523 
1524   while (watcher_thread() != NULL) {
1525     // This wait should make safepoint checks, wait without a timeout,
1526     // and wait as a suspend-equivalent condition.
1527     mu.wait(0, Mutex::_as_suspend_equivalent_flag);
1528   }
1529 }
1530 
1531 void WatcherThread::unpark() {
1532   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1533   PeriodicTask_lock->notify();
1534 }
1535 
1536 void WatcherThread::print_on(outputStream* st) const {
1537   st->print("\"%s\" ", name());
1538   Thread::print_on(st);
1539   st->cr();
1540 }
1541 
1542 // ======= JavaThread ========
1543 
1544 #if INCLUDE_JVMCI
1545 
1546 jlong* JavaThread::_jvmci_old_thread_counters;
1547 
1548 bool jvmci_counters_include(JavaThread* thread) {
1549   return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1550 }
1551 
1552 void JavaThread::collect_counters(jlong* array, int length) {
1553   assert(length == JVMCICounterSize, "wrong value");
1554   for (int i = 0; i < length; i++) {
1555     array[i] = _jvmci_old_thread_counters[i];
1556   }
1557   for (JavaThreadIteratorWithHandle jtiwh; JavaThread *tp = jtiwh.next(); ) {
1558     if (jvmci_counters_include(tp)) {
1559       for (int i = 0; i < length; i++) {
1560         array[i] += tp->_jvmci_counters[i];
1561       }
1562     }
1563   }
1564 }
1565 
1566 // Attempt to enlarge the array for per thread counters.
1567 jlong* resize_counters_array(jlong* old_counters, int current_size, int new_size) {
1568   jlong* new_counters = NEW_C_HEAP_ARRAY(jlong, new_size, mtJVMCI);
1569   if (new_counters == NULL) {
1570     return NULL;
1571   }
1572   if (old_counters == NULL) {
1573     old_counters = new_counters;
1574     memset(old_counters, 0, sizeof(jlong) * new_size);
1575   } else {
1576     for (int i = 0; i < MIN2((int) current_size, new_size); i++) {
1577       new_counters[i] = old_counters[i];
1578     }
1579     if (new_size > current_size) {
1580       memset(new_counters + current_size, 0, sizeof(jlong) * (new_size - current_size));
1581     }
1582     FREE_C_HEAP_ARRAY(jlong, old_counters);
1583   }
1584   return new_counters;
1585 }
1586 
1587 // Attempt to enlarge the array for per thread counters.
1588 bool JavaThread::resize_counters(int current_size, int new_size) {
1589   jlong* new_counters = resize_counters_array(_jvmci_counters, current_size, new_size);
1590   if (new_counters == NULL) {
1591     return false;
1592   } else {
1593     _jvmci_counters = new_counters;
1594     return true;
1595   }
1596 }
1597 
1598 class VM_JVMCIResizeCounters : public VM_Operation {
1599  private:
1600   int _new_size;
1601   bool _failed;
1602 
1603  public:
1604   VM_JVMCIResizeCounters(int new_size) : _new_size(new_size), _failed(false) { }
1605   VMOp_Type type()                  const        { return VMOp_JVMCIResizeCounters; }
1606   bool allow_nested_vm_operations() const        { return true; }
1607   void doit() {
1608     // Resize the old thread counters array
1609     jlong* new_counters = resize_counters_array(JavaThread::_jvmci_old_thread_counters, JVMCICounterSize, _new_size);
1610     if (new_counters == NULL) {
1611       _failed = true;
1612       return;
1613     } else {
1614       JavaThread::_jvmci_old_thread_counters = new_counters;
1615     }
1616 
1617     // Now resize each threads array
1618     for (JavaThreadIteratorWithHandle jtiwh; JavaThread *tp = jtiwh.next(); ) {
1619       if (!tp->resize_counters(JVMCICounterSize, _new_size)) {
1620         _failed = true;
1621         break;
1622       }
1623     }
1624     if (!_failed) {
1625       JVMCICounterSize = _new_size;
1626     }
1627   }
1628 
1629   bool failed() { return _failed; }
1630 };
1631 
1632 bool JavaThread::resize_all_jvmci_counters(int new_size) {
1633   VM_JVMCIResizeCounters op(new_size);
1634   VMThread::execute(&op);
1635   return !op.failed();
1636 }
1637 
1638 #endif // INCLUDE_JVMCI
1639 
1640 // A JavaThread is a normal Java thread
1641 
1642 void JavaThread::initialize() {
1643   // Initialize fields
1644 
1645   set_saved_exception_pc(NULL);
1646   set_threadObj(NULL);
1647   _anchor.clear();
1648   set_entry_point(NULL);
1649   set_jni_functions(jni_functions());
1650   set_callee_target(NULL);
1651   set_vm_result(NULL);
1652   set_vm_result_2(NULL);
1653   set_vframe_array_head(NULL);
1654   set_vframe_array_last(NULL);
1655   set_deferred_locals(NULL);
1656   set_deopt_mark(NULL);
1657   set_deopt_compiled_method(NULL);
1658   set_monitor_chunks(NULL);
1659   _on_thread_list = false;
1660   set_thread_state(_thread_new);
1661   _terminated = _not_terminated;
1662   _array_for_gc = NULL;
1663   _suspend_equivalent = false;
1664   _in_deopt_handler = 0;
1665   _doing_unsafe_access = false;
1666   _stack_guard_state = stack_guard_unused;
1667 #if INCLUDE_JVMCI
1668   _pending_monitorenter = false;
1669   _pending_deoptimization = -1;
1670   _pending_failed_speculation = 0;
1671   _pending_transfer_to_interpreter = false;
1672   _in_retryable_allocation = false;
1673   _jvmci._alternate_call_target = NULL;
1674   assert(_jvmci._implicit_exception_pc == NULL, "must be");
1675   _jvmci_counters = NULL;
1676   if (JVMCICounterSize > 0) {
1677     resize_counters(0, (int) JVMCICounterSize);
1678   }
1679 #endif // INCLUDE_JVMCI
1680   _reserved_stack_activation = NULL;  // stack base not known yet
1681   (void)const_cast<oop&>(_exception_oop = oop(NULL));
1682   _exception_pc  = 0;
1683   _exception_handler_pc = 0;
1684   _is_method_handle_return = 0;
1685   _jvmti_thread_state= NULL;
1686   _should_post_on_exceptions_flag = JNI_FALSE;
1687   _interp_only_mode    = 0;
1688   _special_runtime_exit_condition = _no_async_condition;
1689   _pending_async_exception = NULL;
1690   _thread_stat = NULL;
1691   _thread_stat = new ThreadStatistics();
1692   _jni_active_critical = 0;
1693   _pending_jni_exception_check_fn = NULL;
1694   _do_not_unlock_if_synchronized = false;
1695   _cached_monitor_info = NULL;
1696   _parker = Parker::Allocate(this);
1697   _SleepEvent = ParkEvent::Allocate(this);
1698   // Setup safepoint state info for this thread
1699   ThreadSafepointState::create(this);
1700 
1701   debug_only(_java_call_counter = 0);
1702 
1703   // JVMTI PopFrame support
1704   _popframe_condition = popframe_inactive;
1705   _popframe_preserved_args = NULL;
1706   _popframe_preserved_args_size = 0;
1707   _frames_to_pop_failed_realloc = 0;
1708 
1709   if (SafepointMechanism::uses_thread_local_poll()) {
1710     SafepointMechanism::initialize_header(this);
1711   }
1712 
1713   _class_to_be_initialized = NULL;
1714 
1715   pd_initialize();
1716 }
1717 
1718 JavaThread::JavaThread(bool is_attaching_via_jni) :
1719                        Thread() {
1720   initialize();
1721   if (is_attaching_via_jni) {
1722     _jni_attach_state = _attaching_via_jni;
1723   } else {
1724     _jni_attach_state = _not_attaching_via_jni;
1725   }
1726   assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1727 }
1728 
1729 bool JavaThread::reguard_stack(address cur_sp) {
1730   if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1731       && _stack_guard_state != stack_guard_reserved_disabled) {
1732     return true; // Stack already guarded or guard pages not needed.
1733   }
1734 
1735   if (register_stack_overflow()) {
1736     // For those architectures which have separate register and
1737     // memory stacks, we must check the register stack to see if
1738     // it has overflowed.
1739     return false;
1740   }
1741 
1742   // Java code never executes within the yellow zone: the latter is only
1743   // there to provoke an exception during stack banging.  If java code
1744   // is executing there, either StackShadowPages should be larger, or
1745   // some exception code in c1, c2 or the interpreter isn't unwinding
1746   // when it should.
1747   guarantee(cur_sp > stack_reserved_zone_base(),
1748             "not enough space to reguard - increase StackShadowPages");
1749   if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1750     enable_stack_yellow_reserved_zone();
1751     if (reserved_stack_activation() != stack_base()) {
1752       set_reserved_stack_activation(stack_base());
1753     }
1754   } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1755     set_reserved_stack_activation(stack_base());
1756     enable_stack_reserved_zone();
1757   }
1758   return true;
1759 }
1760 
1761 bool JavaThread::reguard_stack(void) {
1762   return reguard_stack(os::current_stack_pointer());
1763 }
1764 
1765 
1766 void JavaThread::block_if_vm_exited() {
1767   if (_terminated == _vm_exited) {
1768     // _vm_exited is set at safepoint, and Threads_lock is never released
1769     // we will block here forever
1770     Threads_lock->lock();
1771     ShouldNotReachHere();
1772   }
1773 }
1774 
1775 
1776 // Remove this ifdef when C1 is ported to the compiler interface.
1777 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1778 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1779 
1780 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1781                        Thread() {
1782   initialize();
1783   _jni_attach_state = _not_attaching_via_jni;
1784   set_entry_point(entry_point);
1785   // Create the native thread itself.
1786   // %note runtime_23
1787   os::ThreadType thr_type = os::java_thread;
1788   thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1789                                                      os::java_thread;
1790   os::create_thread(this, thr_type, stack_sz);
1791   // The _osthread may be NULL here because we ran out of memory (too many threads active).
1792   // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1793   // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1794   // the exception consists of creating the exception object & initializing it, initialization
1795   // will leave the VM via a JavaCall and then all locks must be unlocked).
1796   //
1797   // The thread is still suspended when we reach here. Thread must be explicit started
1798   // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1799   // by calling Threads:add. The reason why this is not done here, is because the thread
1800   // object must be fully initialized (take a look at JVM_Start)
1801 }
1802 
1803 JavaThread::~JavaThread() {
1804 
1805   // JSR166 -- return the parker to the free list
1806   Parker::Release(_parker);
1807   _parker = NULL;
1808 
1809   // Return the sleep event to the free list
1810   ParkEvent::Release(_SleepEvent);
1811   _SleepEvent = NULL;
1812 
1813   // Free any remaining  previous UnrollBlock
1814   vframeArray* old_array = vframe_array_last();
1815 
1816   if (old_array != NULL) {
1817     Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1818     old_array->set_unroll_block(NULL);
1819     delete old_info;
1820     delete old_array;
1821   }
1822 
1823   GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1824   if (deferred != NULL) {
1825     // This can only happen if thread is destroyed before deoptimization occurs.
1826     assert(deferred->length() != 0, "empty array!");
1827     do {
1828       jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1829       deferred->remove_at(0);
1830       // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1831       delete dlv;
1832     } while (deferred->length() != 0);
1833     delete deferred;
1834   }
1835 
1836   // All Java related clean up happens in exit
1837   ThreadSafepointState::destroy(this);
1838   if (_thread_stat != NULL) delete _thread_stat;
1839 
1840 #if INCLUDE_JVMCI
1841   if (JVMCICounterSize > 0) {
1842     if (jvmci_counters_include(this)) {
1843       for (int i = 0; i < JVMCICounterSize; i++) {
1844         _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1845       }
1846     }
1847     FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1848   }
1849 #endif // INCLUDE_JVMCI
1850 }
1851 
1852 
1853 // First JavaThread specific code executed by a new Java thread.
1854 void JavaThread::pre_run() {
1855   // empty - see comments in run()
1856 }
1857 
1858 // The main routine called by a new Java thread. This isn't overridden
1859 // by subclasses, instead different subclasses define a different "entry_point"
1860 // which defines the actual logic for that kind of thread.
1861 void JavaThread::run() {
1862   // initialize thread-local alloc buffer related fields
1863   this->initialize_tlab();
1864 
1865   // Used to test validity of stack trace backs.
1866   // This can't be moved into pre_run() else we invalidate
1867   // the requirement that thread_main_inner is lower on
1868   // the stack. Consequently all the initialization logic
1869   // stays here in run() rather than pre_run().
1870   this->record_base_of_stack_pointer();
1871 
1872   this->create_stack_guard_pages();
1873 
1874   this->cache_global_variables();
1875 
1876   // Thread is now sufficiently initialized to be handled by the safepoint code as being
1877   // in the VM. Change thread state from _thread_new to _thread_in_vm
1878   ThreadStateTransition::transition(this, _thread_new, _thread_in_vm);
1879   // Before a thread is on the threads list it is always safe, so after leaving the
1880   // _thread_new we should emit a instruction barrier. The distance to modified code
1881   // from here is probably far enough, but this is consistent and safe.
1882   OrderAccess::cross_modify_fence();
1883 
1884   assert(JavaThread::current() == this, "sanity check");
1885   assert(!Thread::current()->owns_locks(), "sanity check");
1886 
1887   DTRACE_THREAD_PROBE(start, this);
1888 
1889   // This operation might block. We call that after all safepoint checks for a new thread has
1890   // been completed.
1891   this->set_active_handles(JNIHandleBlock::allocate_block());
1892 
1893   if (JvmtiExport::should_post_thread_life()) {
1894     JvmtiExport::post_thread_start(this);
1895 
1896   }
1897 
1898   // We call another function to do the rest so we are sure that the stack addresses used
1899   // from there will be lower than the stack base just computed.
1900   thread_main_inner();
1901 }
1902 
1903 void JavaThread::thread_main_inner() {
1904   assert(JavaThread::current() == this, "sanity check");
1905   assert(this->threadObj() != NULL, "just checking");
1906 
1907   // Execute thread entry point unless this thread has a pending exception
1908   // or has been stopped before starting.
1909   // Note: Due to JVM_StopThread we can have pending exceptions already!
1910   if (!this->has_pending_exception() &&
1911       !java_lang_Thread::is_stillborn(this->threadObj())) {
1912     {
1913       ResourceMark rm(this);
1914       this->set_native_thread_name(this->get_thread_name());
1915     }
1916     HandleMark hm(this);
1917     this->entry_point()(this, this);
1918   }
1919 
1920   DTRACE_THREAD_PROBE(stop, this);
1921 
1922   // Cleanup is handled in post_run()
1923 }
1924 
1925 // Shared teardown for all JavaThreads
1926 void JavaThread::post_run() {
1927   this->exit(false);
1928   // Defer deletion to here to ensure 'this' is still referenceable in call_run
1929   // for any shared tear-down.
1930   this->smr_delete();
1931 }
1932 
1933 static void ensure_join(JavaThread* thread) {
1934   // We do not need to grab the Threads_lock, since we are operating on ourself.
1935   Handle threadObj(thread, thread->threadObj());
1936   assert(threadObj.not_null(), "java thread object must exist");
1937   ObjectLocker lock(threadObj, thread);
1938   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1939   thread->clear_pending_exception();
1940   // Thread is exiting. So set thread_status field in  java.lang.Thread class to TERMINATED.
1941   java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1942   // Clear the native thread instance - this makes isAlive return false and allows the join()
1943   // to complete once we've done the notify_all below
1944   java_lang_Thread::set_thread(threadObj(), NULL);
1945   lock.notify_all(thread);
1946   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1947   thread->clear_pending_exception();
1948 }
1949 
1950 static bool is_daemon(oop threadObj) {
1951   return (threadObj != NULL && java_lang_Thread::is_daemon(threadObj));
1952 }
1953 
1954 // For any new cleanup additions, please check to see if they need to be applied to
1955 // cleanup_failed_attach_current_thread as well.
1956 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1957   assert(this == JavaThread::current(), "thread consistency check");
1958 
1959   elapsedTimer _timer_exit_phase1;
1960   elapsedTimer _timer_exit_phase2;
1961   elapsedTimer _timer_exit_phase3;
1962   elapsedTimer _timer_exit_phase4;
1963 
1964   if (log_is_enabled(Debug, os, thread, timer)) {
1965     _timer_exit_phase1.start();
1966   }
1967 
1968   HandleMark hm(this);
1969   Handle uncaught_exception(this, this->pending_exception());
1970   this->clear_pending_exception();
1971   Handle threadObj(this, this->threadObj());
1972   assert(threadObj.not_null(), "Java thread object should be created");
1973 
1974   // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1975   {
1976     EXCEPTION_MARK;
1977 
1978     CLEAR_PENDING_EXCEPTION;
1979   }
1980   if (!destroy_vm) {
1981     if (uncaught_exception.not_null()) {
1982       EXCEPTION_MARK;
1983       // Call method Thread.dispatchUncaughtException().
1984       Klass* thread_klass = SystemDictionary::Thread_klass();
1985       JavaValue result(T_VOID);
1986       JavaCalls::call_virtual(&result,
1987                               threadObj, thread_klass,
1988                               vmSymbols::dispatchUncaughtException_name(),
1989                               vmSymbols::throwable_void_signature(),
1990                               uncaught_exception,
1991                               THREAD);
1992       if (HAS_PENDING_EXCEPTION) {
1993         ResourceMark rm(this);
1994         jio_fprintf(defaultStream::error_stream(),
1995                     "\nException: %s thrown from the UncaughtExceptionHandler"
1996                     " in thread \"%s\"\n",
1997                     pending_exception()->klass()->external_name(),
1998                     get_thread_name());
1999         CLEAR_PENDING_EXCEPTION;
2000       }
2001     }
2002     JFR_ONLY(Jfr::on_java_thread_dismantle(this);)
2003 
2004     // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
2005     // the execution of the method. If that is not enough, then we don't really care. Thread.stop
2006     // is deprecated anyhow.
2007     if (!is_Compiler_thread()) {
2008       int count = 3;
2009       while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
2010         EXCEPTION_MARK;
2011         JavaValue result(T_VOID);
2012         Klass* thread_klass = SystemDictionary::Thread_klass();
2013         JavaCalls::call_virtual(&result,
2014                                 threadObj, thread_klass,
2015                                 vmSymbols::exit_method_name(),
2016                                 vmSymbols::void_method_signature(),
2017                                 THREAD);
2018         CLEAR_PENDING_EXCEPTION;
2019       }
2020     }
2021     // notify JVMTI
2022     if (JvmtiExport::should_post_thread_life()) {
2023       JvmtiExport::post_thread_end(this);
2024     }
2025 
2026     // We have notified the agents that we are exiting, before we go on,
2027     // we must check for a pending external suspend request and honor it
2028     // in order to not surprise the thread that made the suspend request.
2029     while (true) {
2030       {
2031         MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2032         if (!is_external_suspend()) {
2033           set_terminated(_thread_exiting);
2034           ThreadService::current_thread_exiting(this, is_daemon(threadObj()));
2035           break;
2036         }
2037         // Implied else:
2038         // Things get a little tricky here. We have a pending external
2039         // suspend request, but we are holding the SR_lock so we
2040         // can't just self-suspend. So we temporarily drop the lock
2041         // and then self-suspend.
2042       }
2043 
2044       ThreadBlockInVM tbivm(this);
2045       java_suspend_self();
2046 
2047       // We're done with this suspend request, but we have to loop around
2048       // and check again. Eventually we will get SR_lock without a pending
2049       // external suspend request and will be able to mark ourselves as
2050       // exiting.
2051     }
2052     // no more external suspends are allowed at this point
2053   } else {
2054     assert(!is_terminated() && !is_exiting(), "must not be exiting");
2055     // before_exit() has already posted JVMTI THREAD_END events
2056   }
2057 
2058   if (log_is_enabled(Debug, os, thread, timer)) {
2059     _timer_exit_phase1.stop();
2060     _timer_exit_phase2.start();
2061   }
2062 
2063   // Capture daemon status before the thread is marked as terminated.
2064   bool daemon = is_daemon(threadObj());
2065 
2066   // Notify waiters on thread object. This has to be done after exit() is called
2067   // on the thread (if the thread is the last thread in a daemon ThreadGroup the
2068   // group should have the destroyed bit set before waiters are notified).
2069   ensure_join(this);
2070   assert(!this->has_pending_exception(), "ensure_join should have cleared");
2071 
2072   if (log_is_enabled(Debug, os, thread, timer)) {
2073     _timer_exit_phase2.stop();
2074     _timer_exit_phase3.start();
2075   }
2076   // 6282335 JNI DetachCurrentThread spec states that all Java monitors
2077   // held by this thread must be released. The spec does not distinguish
2078   // between JNI-acquired and regular Java monitors. We can only see
2079   // regular Java monitors here if monitor enter-exit matching is broken.
2080   //
2081   // ensure_join() ignores IllegalThreadStateExceptions, and so does
2082   // ObjectSynchronizer::release_monitors_owned_by_thread().
2083   if (exit_type == jni_detach) {
2084     // Sanity check even though JNI DetachCurrentThread() would have
2085     // returned JNI_ERR if there was a Java frame. JavaThread exit
2086     // should be done executing Java code by the time we get here.
2087     assert(!this->has_last_Java_frame(),
2088            "should not have a Java frame when detaching or exiting");
2089     ObjectSynchronizer::release_monitors_owned_by_thread(this);
2090     assert(!this->has_pending_exception(), "release_monitors should have cleared");
2091   }
2092 
2093   // These things needs to be done while we are still a Java Thread. Make sure that thread
2094   // is in a consistent state, in case GC happens
2095   JFR_ONLY(Jfr::on_thread_exit(this);)
2096 
2097   if (active_handles() != NULL) {
2098     JNIHandleBlock* block = active_handles();
2099     set_active_handles(NULL);
2100     JNIHandleBlock::release_block(block);
2101   }
2102 
2103   if (free_handle_block() != NULL) {
2104     JNIHandleBlock* block = free_handle_block();
2105     set_free_handle_block(NULL);
2106     JNIHandleBlock::release_block(block);
2107   }
2108 
2109   // These have to be removed while this is still a valid thread.
2110   remove_stack_guard_pages();
2111 
2112   if (UseTLAB) {
2113     tlab().retire();
2114   }
2115 
2116   if (JvmtiEnv::environments_might_exist()) {
2117     JvmtiExport::cleanup_thread(this);
2118   }
2119 
2120   // We must flush any deferred card marks and other various GC barrier
2121   // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer)
2122   // before removing a thread from the list of active threads.
2123   BarrierSet::barrier_set()->on_thread_detach(this);
2124 
2125   log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
2126     exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
2127     os::current_thread_id());
2128 
2129   if (log_is_enabled(Debug, os, thread, timer)) {
2130     _timer_exit_phase3.stop();
2131     _timer_exit_phase4.start();
2132   }
2133   // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
2134   Threads::remove(this, daemon);
2135 
2136   if (log_is_enabled(Debug, os, thread, timer)) {
2137     _timer_exit_phase4.stop();
2138     ResourceMark rm(this);
2139     log_debug(os, thread, timer)("name='%s'"
2140                                  ", exit-phase1=" JLONG_FORMAT
2141                                  ", exit-phase2=" JLONG_FORMAT
2142                                  ", exit-phase3=" JLONG_FORMAT
2143                                  ", exit-phase4=" JLONG_FORMAT,
2144                                  get_thread_name(),
2145                                  _timer_exit_phase1.milliseconds(),
2146                                  _timer_exit_phase2.milliseconds(),
2147                                  _timer_exit_phase3.milliseconds(),
2148                                  _timer_exit_phase4.milliseconds());
2149   }
2150 }
2151 
2152 void JavaThread::cleanup_failed_attach_current_thread(bool is_daemon) {
2153   if (active_handles() != NULL) {
2154     JNIHandleBlock* block = active_handles();
2155     set_active_handles(NULL);
2156     JNIHandleBlock::release_block(block);
2157   }
2158 
2159   if (free_handle_block() != NULL) {
2160     JNIHandleBlock* block = free_handle_block();
2161     set_free_handle_block(NULL);
2162     JNIHandleBlock::release_block(block);
2163   }
2164 
2165   // These have to be removed while this is still a valid thread.
2166   remove_stack_guard_pages();
2167 
2168   if (UseTLAB) {
2169     tlab().retire();
2170   }
2171 
2172   BarrierSet::barrier_set()->on_thread_detach(this);
2173 
2174   Threads::remove(this, is_daemon);
2175   this->smr_delete();
2176 }
2177 
2178 JavaThread* JavaThread::active() {
2179   Thread* thread = Thread::current();
2180   if (thread->is_Java_thread()) {
2181     return (JavaThread*) thread;
2182   } else {
2183     assert(thread->is_VM_thread(), "this must be a vm thread");
2184     VM_Operation* op = ((VMThread*) thread)->vm_operation();
2185     JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2186     assert(ret->is_Java_thread(), "must be a Java thread");
2187     return ret;
2188   }
2189 }
2190 
2191 bool JavaThread::is_lock_owned(address adr) const {
2192   if (Thread::is_lock_owned(adr)) return true;
2193 
2194   for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2195     if (chunk->contains(adr)) return true;
2196   }
2197 
2198   return false;
2199 }
2200 
2201 
2202 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2203   chunk->set_next(monitor_chunks());
2204   set_monitor_chunks(chunk);
2205 }
2206 
2207 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2208   guarantee(monitor_chunks() != NULL, "must be non empty");
2209   if (monitor_chunks() == chunk) {
2210     set_monitor_chunks(chunk->next());
2211   } else {
2212     MonitorChunk* prev = monitor_chunks();
2213     while (prev->next() != chunk) prev = prev->next();
2214     prev->set_next(chunk->next());
2215   }
2216 }
2217 
2218 // JVM support.
2219 
2220 // Note: this function shouldn't block if it's called in
2221 // _thread_in_native_trans state (such as from
2222 // check_special_condition_for_native_trans()).
2223 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2224 
2225   if (has_last_Java_frame() && has_async_condition()) {
2226     // If we are at a polling page safepoint (not a poll return)
2227     // then we must defer async exception because live registers
2228     // will be clobbered by the exception path. Poll return is
2229     // ok because the call we a returning from already collides
2230     // with exception handling registers and so there is no issue.
2231     // (The exception handling path kills call result registers but
2232     //  this is ok since the exception kills the result anyway).
2233 
2234     if (is_at_poll_safepoint()) {
2235       // if the code we are returning to has deoptimized we must defer
2236       // the exception otherwise live registers get clobbered on the
2237       // exception path before deoptimization is able to retrieve them.
2238       //
2239       RegisterMap map(this, false);
2240       frame caller_fr = last_frame().sender(&map);
2241       assert(caller_fr.is_compiled_frame(), "what?");
2242       if (caller_fr.is_deoptimized_frame()) {
2243         log_info(exceptions)("deferred async exception at compiled safepoint");
2244         return;
2245       }
2246     }
2247   }
2248 
2249   JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2250   if (condition == _no_async_condition) {
2251     // Conditions have changed since has_special_runtime_exit_condition()
2252     // was called:
2253     // - if we were here only because of an external suspend request,
2254     //   then that was taken care of above (or cancelled) so we are done
2255     // - if we were here because of another async request, then it has
2256     //   been cleared between the has_special_runtime_exit_condition()
2257     //   and now so again we are done
2258     return;
2259   }
2260 
2261   // Check for pending async. exception
2262   if (_pending_async_exception != NULL) {
2263     // Only overwrite an already pending exception, if it is not a threadDeath.
2264     if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2265 
2266       // We cannot call Exceptions::_throw(...) here because we cannot block
2267       set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2268 
2269       LogTarget(Info, exceptions) lt;
2270       if (lt.is_enabled()) {
2271         ResourceMark rm;
2272         LogStream ls(lt);
2273         ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2274           if (has_last_Java_frame()) {
2275             frame f = last_frame();
2276            ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2277           }
2278         ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2279       }
2280       _pending_async_exception = NULL;
2281       clear_has_async_exception();
2282     }
2283   }
2284 
2285   if (check_unsafe_error &&
2286       condition == _async_unsafe_access_error && !has_pending_exception()) {
2287     condition = _no_async_condition;  // done
2288     switch (thread_state()) {
2289     case _thread_in_vm: {
2290       JavaThread* THREAD = this;
2291       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2292     }
2293     case _thread_in_native: {
2294       ThreadInVMfromNative tiv(this);
2295       JavaThread* THREAD = this;
2296       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2297     }
2298     case _thread_in_Java: {
2299       ThreadInVMfromJava tiv(this);
2300       JavaThread* THREAD = this;
2301       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2302     }
2303     default:
2304       ShouldNotReachHere();
2305     }
2306   }
2307 
2308   assert(condition == _no_async_condition || has_pending_exception() ||
2309          (!check_unsafe_error && condition == _async_unsafe_access_error),
2310          "must have handled the async condition, if no exception");
2311 }
2312 
2313 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2314 
2315   // Check for pending external suspend.
2316   if (is_external_suspend_with_lock()) {
2317     frame_anchor()->make_walkable(this);
2318     java_suspend_self_with_safepoint_check();
2319   }
2320 
2321   // We might be here for reasons in addition to the self-suspend request
2322   // so check for other async requests.
2323   if (check_asyncs) {
2324     check_and_handle_async_exceptions();
2325   }
2326 
2327   JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);)
2328 }
2329 
2330 void JavaThread::send_thread_stop(oop java_throwable)  {
2331   assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2332   assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2333   assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2334 
2335   // Do not throw asynchronous exceptions against the compiler thread
2336   // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2337   if (!can_call_java()) return;
2338 
2339   {
2340     // Actually throw the Throwable against the target Thread - however
2341     // only if there is no thread death exception installed already.
2342     if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2343       // If the topmost frame is a runtime stub, then we are calling into
2344       // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2345       // must deoptimize the caller before continuing, as the compiled  exception handler table
2346       // may not be valid
2347       if (has_last_Java_frame()) {
2348         frame f = last_frame();
2349         if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2350           // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2351           RegisterMap reg_map(this, UseBiasedLocking);
2352           frame compiled_frame = f.sender(&reg_map);
2353           if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2354             Deoptimization::deoptimize(this, compiled_frame, &reg_map);
2355           }
2356         }
2357       }
2358 
2359       // Set async. pending exception in thread.
2360       set_pending_async_exception(java_throwable);
2361 
2362       if (log_is_enabled(Info, exceptions)) {
2363          ResourceMark rm;
2364         log_info(exceptions)("Pending Async. exception installed of type: %s",
2365                              InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2366       }
2367       // for AbortVMOnException flag
2368       Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2369     }
2370   }
2371 
2372 
2373   // Interrupt thread so it will wake up from a potential wait()
2374   Thread::interrupt(this);
2375 }
2376 
2377 // External suspension mechanism.
2378 //
2379 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2380 // to any VM_locks and it is at a transition
2381 // Self-suspension will happen on the transition out of the vm.
2382 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2383 //
2384 // Guarantees on return:
2385 //   + Target thread will not execute any new bytecode (that's why we need to
2386 //     force a safepoint)
2387 //   + Target thread will not enter any new monitors
2388 //
2389 void JavaThread::java_suspend() {
2390   ThreadsListHandle tlh;
2391   if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) {
2392     return;
2393   }
2394 
2395   { MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2396     if (!is_external_suspend()) {
2397       // a racing resume has cancelled us; bail out now
2398       return;
2399     }
2400 
2401     // suspend is done
2402     uint32_t debug_bits = 0;
2403     // Warning: is_ext_suspend_completed() may temporarily drop the
2404     // SR_lock to allow the thread to reach a stable thread state if
2405     // it is currently in a transient thread state.
2406     if (is_ext_suspend_completed(false /* !called_by_wait */,
2407                                  SuspendRetryDelay, &debug_bits)) {
2408       return;
2409     }
2410   }
2411 
2412   if (Thread::current() == this) {
2413     // Safely self-suspend.
2414     // If we don't do this explicitly it will implicitly happen
2415     // before we transition back to Java, and on some other thread-state
2416     // transition paths, but not as we exit a JVM TI SuspendThread call.
2417     // As SuspendThread(current) must not return (until resumed) we must
2418     // self-suspend here.
2419     ThreadBlockInVM tbivm(this);
2420     java_suspend_self();
2421   } else {
2422     VM_ThreadSuspend vm_suspend;
2423     VMThread::execute(&vm_suspend);
2424   }
2425 }
2426 
2427 // Part II of external suspension.
2428 // A JavaThread self suspends when it detects a pending external suspend
2429 // request. This is usually on transitions. It is also done in places
2430 // where continuing to the next transition would surprise the caller,
2431 // e.g., monitor entry.
2432 //
2433 // Returns the number of times that the thread self-suspended.
2434 //
2435 // Note: DO NOT call java_suspend_self() when you just want to block current
2436 //       thread. java_suspend_self() is the second stage of cooperative
2437 //       suspension for external suspend requests and should only be used
2438 //       to complete an external suspend request.
2439 //
2440 int JavaThread::java_suspend_self() {
2441   assert(thread_state() == _thread_blocked, "wrong state for java_suspend_self()");
2442   int ret = 0;
2443 
2444   // we are in the process of exiting so don't suspend
2445   if (is_exiting()) {
2446     clear_external_suspend();
2447     return ret;
2448   }
2449 
2450   assert(_anchor.walkable() ||
2451          (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2452          "must have walkable stack");
2453 
2454   MonitorLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2455 
2456   assert(!this->is_ext_suspended(),
2457          "a thread trying to self-suspend should not already be suspended");
2458 
2459   if (this->is_suspend_equivalent()) {
2460     // If we are self-suspending as a result of the lifting of a
2461     // suspend equivalent condition, then the suspend_equivalent
2462     // flag is not cleared until we set the ext_suspended flag so
2463     // that wait_for_ext_suspend_completion() returns consistent
2464     // results.
2465     this->clear_suspend_equivalent();
2466   }
2467 
2468   // A racing resume may have cancelled us before we grabbed SR_lock
2469   // above. Or another external suspend request could be waiting for us
2470   // by the time we return from SR_lock()->wait(). The thread
2471   // that requested the suspension may already be trying to walk our
2472   // stack and if we return now, we can change the stack out from under
2473   // it. This would be a "bad thing (TM)" and cause the stack walker
2474   // to crash. We stay self-suspended until there are no more pending
2475   // external suspend requests.
2476   while (is_external_suspend()) {
2477     ret++;
2478     this->set_ext_suspended();
2479 
2480     // _ext_suspended flag is cleared by java_resume()
2481     while (is_ext_suspended()) {
2482       ml.wait();
2483     }
2484   }
2485   return ret;
2486 }
2487 
2488 // Helper routine to set up the correct thread state before calling java_suspend_self.
2489 // This is called when regular thread-state transition helpers can't be used because
2490 // we can be in various states, in particular _thread_in_native_trans.
2491 // Because this thread is external suspended the safepoint code will count it as at
2492 // a safepoint, regardless of what its actual current thread-state is. But
2493 // is_ext_suspend_completed() may be waiting to see a thread transition from
2494 // _thread_in_native_trans to _thread_blocked. So we set the thread state directly
2495 // to _thread_blocked. The problem with setting thread state directly is that a
2496 // safepoint could happen just after java_suspend_self() returns after being resumed,
2497 // and the VM thread will see the _thread_blocked state. So we must check for a safepoint
2498 // after restoring the state to make sure we won't leave while a safepoint is in progress.
2499 // However, not all initial-states are allowed when performing a safepoint check, as we
2500 // should never be blocking at a safepoint whilst in those states. Of these 'bad' states
2501 // only _thread_in_native is possible when executing this code (based on our two callers).
2502 // A thread that is _thread_in_native is already safepoint-safe and so it doesn't matter
2503 // whether the VMThread sees the _thread_blocked state, or the _thread_in_native state,
2504 // and so we don't need the explicit safepoint check.
2505 
2506 void JavaThread::java_suspend_self_with_safepoint_check() {
2507   assert(this == Thread::current(), "invariant");
2508   JavaThreadState state = thread_state();
2509   set_thread_state(_thread_blocked);
2510   java_suspend_self();
2511   set_thread_state_fence(state);
2512   // Since we are not using a regular thread-state transition helper here,
2513   // we must manually emit the instruction barrier after leaving a safe state.
2514   OrderAccess::cross_modify_fence();
2515   if (state != _thread_in_native) {
2516     SafepointMechanism::block_if_requested(this);
2517   }
2518 }
2519 
2520 #ifdef ASSERT
2521 // Verify the JavaThread has not yet been published in the Threads::list, and
2522 // hence doesn't need protection from concurrent access at this stage.
2523 void JavaThread::verify_not_published() {
2524   // Cannot create a ThreadsListHandle here and check !tlh.includes(this)
2525   // since an unpublished JavaThread doesn't participate in the
2526   // Thread-SMR protocol for keeping a ThreadsList alive.
2527   assert(!on_thread_list(), "JavaThread shouldn't have been published yet!");
2528 }
2529 #endif
2530 
2531 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2532 // progress or when _suspend_flags is non-zero.
2533 // Current thread needs to self-suspend if there is a suspend request and/or
2534 // block if a safepoint is in progress.
2535 // Async exception ISN'T checked.
2536 // Note only the ThreadInVMfromNative transition can call this function
2537 // directly and when thread state is _thread_in_native_trans
2538 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2539   assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2540 
2541   assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2542 
2543   if (thread->is_external_suspend()) {
2544     thread->java_suspend_self_with_safepoint_check();
2545   } else {
2546     SafepointMechanism::block_if_requested(thread);
2547   }
2548 
2549   JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(thread);)
2550 }
2551 
2552 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2553 // progress or when _suspend_flags is non-zero.
2554 // Current thread needs to self-suspend if there is a suspend request and/or
2555 // block if a safepoint is in progress.
2556 // Also check for pending async exception (not including unsafe access error).
2557 // Note only the native==>VM/Java barriers can call this function and when
2558 // thread state is _thread_in_native_trans.
2559 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2560   check_safepoint_and_suspend_for_native_trans(thread);
2561 
2562   if (thread->has_async_exception()) {
2563     // We are in _thread_in_native_trans state, don't handle unsafe
2564     // access error since that may block.
2565     thread->check_and_handle_async_exceptions(false);
2566   }
2567 }
2568 
2569 // This is a variant of the normal
2570 // check_special_condition_for_native_trans with slightly different
2571 // semantics for use by critical native wrappers.  It does all the
2572 // normal checks but also performs the transition back into
2573 // thread_in_Java state.  This is required so that critical natives
2574 // can potentially block and perform a GC if they are the last thread
2575 // exiting the GCLocker.
2576 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2577   check_special_condition_for_native_trans(thread);
2578 
2579   // Finish the transition
2580   thread->set_thread_state(_thread_in_Java);
2581 
2582   if (thread->do_critical_native_unlock()) {
2583     ThreadInVMfromJavaNoAsyncException tiv(thread);
2584     GCLocker::unlock_critical(thread);
2585     thread->clear_critical_native_unlock();
2586   }
2587 }
2588 
2589 // We need to guarantee the Threads_lock here, since resumes are not
2590 // allowed during safepoint synchronization
2591 // Can only resume from an external suspension
2592 void JavaThread::java_resume() {
2593   assert_locked_or_safepoint(Threads_lock);
2594 
2595   // Sanity check: thread is gone, has started exiting or the thread
2596   // was not externally suspended.
2597   ThreadsListHandle tlh;
2598   if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) {
2599     return;
2600   }
2601 
2602   MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2603 
2604   clear_external_suspend();
2605 
2606   if (is_ext_suspended()) {
2607     clear_ext_suspended();
2608     SR_lock()->notify_all();
2609   }
2610 }
2611 
2612 size_t JavaThread::_stack_red_zone_size = 0;
2613 size_t JavaThread::_stack_yellow_zone_size = 0;
2614 size_t JavaThread::_stack_reserved_zone_size = 0;
2615 size_t JavaThread::_stack_shadow_zone_size = 0;
2616 
2617 void JavaThread::create_stack_guard_pages() {
2618   if (!os::uses_stack_guard_pages() ||
2619       _stack_guard_state != stack_guard_unused ||
2620       (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) {
2621       log_info(os, thread)("Stack guard page creation for thread "
2622                            UINTX_FORMAT " disabled", os::current_thread_id());
2623     return;
2624   }
2625   address low_addr = stack_end();
2626   size_t len = stack_guard_zone_size();
2627 
2628   assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2629   assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2630 
2631   int must_commit = os::must_commit_stack_guard_pages();
2632   // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2633 
2634   if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2635     log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2636     return;
2637   }
2638 
2639   if (os::guard_memory((char *) low_addr, len)) {
2640     _stack_guard_state = stack_guard_enabled;
2641   } else {
2642     log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2643       PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2644     if (os::uncommit_memory((char *) low_addr, len)) {
2645       log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2646     }
2647     return;
2648   }
2649 
2650   log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2651     PTR_FORMAT "-" PTR_FORMAT ".",
2652     os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2653 }
2654 
2655 void JavaThread::remove_stack_guard_pages() {
2656   assert(Thread::current() == this, "from different thread");
2657   if (_stack_guard_state == stack_guard_unused) return;
2658   address low_addr = stack_end();
2659   size_t len = stack_guard_zone_size();
2660 
2661   if (os::must_commit_stack_guard_pages()) {
2662     if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2663       _stack_guard_state = stack_guard_unused;
2664     } else {
2665       log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2666         PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2667       return;
2668     }
2669   } else {
2670     if (_stack_guard_state == stack_guard_unused) return;
2671     if (os::unguard_memory((char *) low_addr, len)) {
2672       _stack_guard_state = stack_guard_unused;
2673     } else {
2674       log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2675         PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2676       return;
2677     }
2678   }
2679 
2680   log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2681     PTR_FORMAT "-" PTR_FORMAT ".",
2682     os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2683 }
2684 
2685 void JavaThread::enable_stack_reserved_zone() {
2686   assert(_stack_guard_state == stack_guard_reserved_disabled, "inconsistent state");
2687 
2688   // The base notation is from the stack's point of view, growing downward.
2689   // We need to adjust it to work correctly with guard_memory()
2690   address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2691 
2692   guarantee(base < stack_base(),"Error calculating stack reserved zone");
2693   guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2694 
2695   if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2696     _stack_guard_state = stack_guard_enabled;
2697   } else {
2698     warning("Attempt to guard stack reserved zone failed.");
2699   }
2700   enable_register_stack_guard();
2701 }
2702 
2703 void JavaThread::disable_stack_reserved_zone() {
2704   assert(_stack_guard_state == stack_guard_enabled, "inconsistent state");
2705 
2706   // Simply return if called for a thread that does not use guard pages.
2707   if (_stack_guard_state != stack_guard_enabled) return;
2708 
2709   // The base notation is from the stack's point of view, growing downward.
2710   // We need to adjust it to work correctly with guard_memory()
2711   address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2712 
2713   if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2714     _stack_guard_state = stack_guard_reserved_disabled;
2715   } else {
2716     warning("Attempt to unguard stack reserved zone failed.");
2717   }
2718   disable_register_stack_guard();
2719 }
2720 
2721 void JavaThread::enable_stack_yellow_reserved_zone() {
2722   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2723   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2724 
2725   // The base notation is from the stacks point of view, growing downward.
2726   // We need to adjust it to work correctly with guard_memory()
2727   address base = stack_red_zone_base();
2728 
2729   guarantee(base < stack_base(), "Error calculating stack yellow zone");
2730   guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2731 
2732   if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2733     _stack_guard_state = stack_guard_enabled;
2734   } else {
2735     warning("Attempt to guard stack yellow zone failed.");
2736   }
2737   enable_register_stack_guard();
2738 }
2739 
2740 void JavaThread::disable_stack_yellow_reserved_zone() {
2741   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2742   assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2743 
2744   // Simply return if called for a thread that does not use guard pages.
2745   if (_stack_guard_state == stack_guard_unused) return;
2746 
2747   // The base notation is from the stacks point of view, growing downward.
2748   // We need to adjust it to work correctly with guard_memory()
2749   address base = stack_red_zone_base();
2750 
2751   if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2752     _stack_guard_state = stack_guard_yellow_reserved_disabled;
2753   } else {
2754     warning("Attempt to unguard stack yellow zone failed.");
2755   }
2756   disable_register_stack_guard();
2757 }
2758 
2759 void JavaThread::enable_stack_red_zone() {
2760   // The base notation is from the stacks point of view, growing downward.
2761   // We need to adjust it to work correctly with guard_memory()
2762   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2763   address base = stack_red_zone_base() - stack_red_zone_size();
2764 
2765   guarantee(base < stack_base(), "Error calculating stack red zone");
2766   guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2767 
2768   if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2769     warning("Attempt to guard stack red zone failed.");
2770   }
2771 }
2772 
2773 void JavaThread::disable_stack_red_zone() {
2774   // The base notation is from the stacks point of view, growing downward.
2775   // We need to adjust it to work correctly with guard_memory()
2776   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2777   address base = stack_red_zone_base() - stack_red_zone_size();
2778   if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2779     warning("Attempt to unguard stack red zone failed.");
2780   }
2781 }
2782 
2783 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2784   // ignore is there is no stack
2785   if (!has_last_Java_frame()) return;
2786   // traverse the stack frames. Starts from top frame.
2787   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2788     frame* fr = fst.current();
2789     f(fr, fst.register_map());
2790   }
2791 }
2792 
2793 
2794 #ifndef PRODUCT
2795 // Deoptimization
2796 // Function for testing deoptimization
2797 void JavaThread::deoptimize() {
2798   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2799   StackFrameStream fst(this, UseBiasedLocking);
2800   bool deopt = false;           // Dump stack only if a deopt actually happens.
2801   bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2802   // Iterate over all frames in the thread and deoptimize
2803   for (; !fst.is_done(); fst.next()) {
2804     if (fst.current()->can_be_deoptimized()) {
2805 
2806       if (only_at) {
2807         // Deoptimize only at particular bcis.  DeoptimizeOnlyAt
2808         // consists of comma or carriage return separated numbers so
2809         // search for the current bci in that string.
2810         address pc = fst.current()->pc();
2811         nmethod* nm =  (nmethod*) fst.current()->cb();
2812         ScopeDesc* sd = nm->scope_desc_at(pc);
2813         char buffer[8];
2814         jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2815         size_t len = strlen(buffer);
2816         const char * found = strstr(DeoptimizeOnlyAt, buffer);
2817         while (found != NULL) {
2818           if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2819               (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2820             // Check that the bci found is bracketed by terminators.
2821             break;
2822           }
2823           found = strstr(found + 1, buffer);
2824         }
2825         if (!found) {
2826           continue;
2827         }
2828       }
2829 
2830       if (DebugDeoptimization && !deopt) {
2831         deopt = true; // One-time only print before deopt
2832         tty->print_cr("[BEFORE Deoptimization]");
2833         trace_frames();
2834         trace_stack();
2835       }
2836       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2837     }
2838   }
2839 
2840   if (DebugDeoptimization && deopt) {
2841     tty->print_cr("[AFTER Deoptimization]");
2842     trace_frames();
2843   }
2844 }
2845 
2846 
2847 // Make zombies
2848 void JavaThread::make_zombies() {
2849   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2850     if (fst.current()->can_be_deoptimized()) {
2851       // it is a Java nmethod
2852       nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2853       nm->make_not_entrant();
2854     }
2855   }
2856 }
2857 #endif // PRODUCT
2858 
2859 
2860 void JavaThread::deoptimize_marked_methods() {
2861   if (!has_last_Java_frame()) return;
2862   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2863   StackFrameStream fst(this, UseBiasedLocking);
2864   for (; !fst.is_done(); fst.next()) {
2865     if (fst.current()->should_be_deoptimized()) {
2866       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2867     }
2868   }
2869 }
2870 
2871 // If the caller is a NamedThread, then remember, in the current scope,
2872 // the given JavaThread in its _processed_thread field.
2873 class RememberProcessedThread: public StackObj {
2874   NamedThread* _cur_thr;
2875  public:
2876   RememberProcessedThread(JavaThread* jthr) {
2877     Thread* thread = Thread::current();
2878     if (thread->is_Named_thread()) {
2879       _cur_thr = (NamedThread *)thread;
2880       _cur_thr->set_processed_thread(jthr);
2881     } else {
2882       _cur_thr = NULL;
2883     }
2884   }
2885 
2886   ~RememberProcessedThread() {
2887     if (_cur_thr) {
2888       _cur_thr->set_processed_thread(NULL);
2889     }
2890   }
2891 };
2892 
2893 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2894   // Verify that the deferred card marks have been flushed.
2895   assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2896 
2897   // Traverse the GCHandles
2898   Thread::oops_do(f, cf);
2899 
2900   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2901          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2902 
2903   if (has_last_Java_frame()) {
2904     // Record JavaThread to GC thread
2905     RememberProcessedThread rpt(this);
2906 
2907     // traverse the registered growable array
2908     if (_array_for_gc != NULL) {
2909       for (int index = 0; index < _array_for_gc->length(); index++) {
2910         f->do_oop(_array_for_gc->adr_at(index));
2911       }
2912     }
2913 
2914     // Traverse the monitor chunks
2915     for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2916       chunk->oops_do(f);
2917     }
2918 
2919     // Traverse the execution stack
2920     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2921       fst.current()->oops_do(f, cf, fst.register_map());
2922     }
2923   }
2924 
2925   assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2926   // If we have deferred set_locals there might be oops waiting to be
2927   // written
2928   GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2929   if (list != NULL) {
2930     for (int i = 0; i < list->length(); i++) {
2931       list->at(i)->oops_do(f);
2932     }
2933   }
2934 
2935   // Traverse instance variables at the end since the GC may be moving things
2936   // around using this function
2937   f->do_oop((oop*) &_threadObj);
2938   f->do_oop((oop*) &_vm_result);
2939   f->do_oop((oop*) &_exception_oop);
2940   f->do_oop((oop*) &_pending_async_exception);
2941 
2942   if (jvmti_thread_state() != NULL) {
2943     jvmti_thread_state()->oops_do(f);
2944   }
2945 }
2946 
2947 #ifdef ASSERT
2948 void JavaThread::verify_states_for_handshake() {
2949   // This checks that the thread has a correct frame state during a handshake.
2950   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2951          (has_last_Java_frame() && java_call_counter() > 0),
2952          "unexpected frame info: has_last_frame=%d, java_call_counter=%d",
2953          has_last_Java_frame(), java_call_counter());
2954 }
2955 #endif
2956 
2957 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2958   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2959          (has_last_Java_frame() && java_call_counter() > 0),
2960          "unexpected frame info: has_last_frame=%d, java_call_counter=%d",
2961          has_last_Java_frame(), java_call_counter());
2962 
2963   if (has_last_Java_frame()) {
2964     // Traverse the execution stack
2965     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2966       fst.current()->nmethods_do(cf);
2967     }
2968   }
2969 }
2970 
2971 void JavaThread::metadata_do(MetadataClosure* f) {
2972   if (has_last_Java_frame()) {
2973     // Traverse the execution stack to call f() on the methods in the stack
2974     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2975       fst.current()->metadata_do(f);
2976     }
2977   } else if (is_Compiler_thread()) {
2978     // need to walk ciMetadata in current compile tasks to keep alive.
2979     CompilerThread* ct = (CompilerThread*)this;
2980     if (ct->env() != NULL) {
2981       ct->env()->metadata_do(f);
2982     }
2983     CompileTask* task = ct->task();
2984     if (task != NULL) {
2985       task->metadata_do(f);
2986     }
2987   }
2988 }
2989 
2990 // Printing
2991 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2992   switch (_thread_state) {
2993   case _thread_uninitialized:     return "_thread_uninitialized";
2994   case _thread_new:               return "_thread_new";
2995   case _thread_new_trans:         return "_thread_new_trans";
2996   case _thread_in_native:         return "_thread_in_native";
2997   case _thread_in_native_trans:   return "_thread_in_native_trans";
2998   case _thread_in_vm:             return "_thread_in_vm";
2999   case _thread_in_vm_trans:       return "_thread_in_vm_trans";
3000   case _thread_in_Java:           return "_thread_in_Java";
3001   case _thread_in_Java_trans:     return "_thread_in_Java_trans";
3002   case _thread_blocked:           return "_thread_blocked";
3003   case _thread_blocked_trans:     return "_thread_blocked_trans";
3004   default:                        return "unknown thread state";
3005   }
3006 }
3007 
3008 #ifndef PRODUCT
3009 void JavaThread::print_thread_state_on(outputStream *st) const {
3010   st->print_cr("   JavaThread state: %s", _get_thread_state_name(_thread_state));
3011 };
3012 #endif // PRODUCT
3013 
3014 // Called by Threads::print() for VM_PrintThreads operation
3015 void JavaThread::print_on(outputStream *st, bool print_extended_info) const {
3016   st->print_raw("\"");
3017   st->print_raw(get_thread_name());
3018   st->print_raw("\" ");
3019   oop thread_oop = threadObj();
3020   if (thread_oop != NULL) {
3021     st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
3022     if (java_lang_Thread::is_daemon(thread_oop))  st->print("daemon ");
3023     st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
3024   }
3025   Thread::print_on(st, print_extended_info);
3026   // print guess for valid stack memory region (assume 4K pages); helps lock debugging
3027   st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
3028   if (thread_oop != NULL) {
3029     st->print_cr("   java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
3030   }
3031 #ifndef PRODUCT
3032   _safepoint_state->print_on(st);
3033 #endif // PRODUCT
3034   if (is_Compiler_thread()) {
3035     CompileTask *task = ((CompilerThread*)this)->task();
3036     if (task != NULL) {
3037       st->print("   Compiling: ");
3038       task->print(st, NULL, true, false);
3039     } else {
3040       st->print("   No compile task");
3041     }
3042     st->cr();
3043   }
3044 }
3045 
3046 void JavaThread::print() const { print_on(tty); }
3047 
3048 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
3049   st->print("%s", get_thread_name_string(buf, buflen));
3050 }
3051 
3052 // Called by fatal error handler. The difference between this and
3053 // JavaThread::print() is that we can't grab lock or allocate memory.
3054 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
3055   st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
3056   oop thread_obj = threadObj();
3057   if (thread_obj != NULL) {
3058     if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
3059   }
3060   st->print(" [");
3061   st->print("%s", _get_thread_state_name(_thread_state));
3062   if (osthread()) {
3063     st->print(", id=%d", osthread()->thread_id());
3064   }
3065   st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
3066             p2i(stack_end()), p2i(stack_base()));
3067   st->print("]");
3068 
3069   ThreadsSMRSupport::print_info_on(this, st);
3070   return;
3071 }
3072 
3073 // Verification
3074 
3075 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
3076 
3077 void JavaThread::verify() {
3078   // Verify oops in the thread.
3079   oops_do(&VerifyOopClosure::verify_oop, NULL);
3080 
3081   // Verify the stack frames.
3082   frames_do(frame_verify);
3083 }
3084 
3085 // CR 6300358 (sub-CR 2137150)
3086 // Most callers of this method assume that it can't return NULL but a
3087 // thread may not have a name whilst it is in the process of attaching to
3088 // the VM - see CR 6412693, and there are places where a JavaThread can be
3089 // seen prior to having it's threadObj set (eg JNI attaching threads and
3090 // if vm exit occurs during initialization). These cases can all be accounted
3091 // for such that this method never returns NULL.
3092 const char* JavaThread::get_thread_name() const {
3093 #ifdef ASSERT
3094   // early safepoints can hit while current thread does not yet have TLS
3095   if (!SafepointSynchronize::is_at_safepoint()) {
3096     Thread *cur = Thread::current();
3097     if (!(cur->is_Java_thread() && cur == this)) {
3098       // Current JavaThreads are allowed to get their own name without
3099       // the Threads_lock.
3100       assert_locked_or_safepoint(Threads_lock);
3101     }
3102   }
3103 #endif // ASSERT
3104   return get_thread_name_string();
3105 }
3106 
3107 // Returns a non-NULL representation of this thread's name, or a suitable
3108 // descriptive string if there is no set name
3109 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3110   const char* name_str;
3111   oop thread_obj = threadObj();
3112   if (thread_obj != NULL) {
3113     oop name = java_lang_Thread::name(thread_obj);
3114     if (name != NULL) {
3115       if (buf == NULL) {
3116         name_str = java_lang_String::as_utf8_string(name);
3117       } else {
3118         name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3119       }
3120     } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3121       name_str = "<no-name - thread is attaching>";
3122     } else {
3123       name_str = Thread::name();
3124     }
3125   } else {
3126     name_str = Thread::name();
3127   }
3128   assert(name_str != NULL, "unexpected NULL thread name");
3129   return name_str;
3130 }
3131 
3132 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3133 
3134   assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3135   assert(NoPriority <= prio && prio <= MaxPriority, "sanity check");
3136   // Link Java Thread object <-> C++ Thread
3137 
3138   // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3139   // and put it into a new Handle.  The Handle "thread_oop" can then
3140   // be used to pass the C++ thread object to other methods.
3141 
3142   // Set the Java level thread object (jthread) field of the
3143   // new thread (a JavaThread *) to C++ thread object using the
3144   // "thread_oop" handle.
3145 
3146   // Set the thread field (a JavaThread *) of the
3147   // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3148 
3149   Handle thread_oop(Thread::current(),
3150                     JNIHandles::resolve_non_null(jni_thread));
3151   assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3152          "must be initialized");
3153   set_threadObj(thread_oop());
3154   java_lang_Thread::set_thread(thread_oop(), this);
3155 
3156   if (prio == NoPriority) {
3157     prio = java_lang_Thread::priority(thread_oop());
3158     assert(prio != NoPriority, "A valid priority should be present");
3159   }
3160 
3161   // Push the Java priority down to the native thread; needs Threads_lock
3162   Thread::set_priority(this, prio);
3163 
3164   // Add the new thread to the Threads list and set it in motion.
3165   // We must have threads lock in order to call Threads::add.
3166   // It is crucial that we do not block before the thread is
3167   // added to the Threads list for if a GC happens, then the java_thread oop
3168   // will not be visited by GC.
3169   Threads::add(this);
3170 }
3171 
3172 oop JavaThread::current_park_blocker() {
3173   // Support for JSR-166 locks
3174   oop thread_oop = threadObj();
3175   if (thread_oop != NULL) {
3176     return java_lang_Thread::park_blocker(thread_oop);
3177   }
3178   return NULL;
3179 }
3180 
3181 
3182 void JavaThread::print_stack_on(outputStream* st) {
3183   if (!has_last_Java_frame()) return;
3184   ResourceMark rm;
3185   HandleMark   hm;
3186 
3187   RegisterMap reg_map(this);
3188   vframe* start_vf = last_java_vframe(&reg_map);
3189   int count = 0;
3190   for (vframe* f = start_vf; f != NULL; f = f->sender()) {
3191     if (f->is_java_frame()) {
3192       javaVFrame* jvf = javaVFrame::cast(f);
3193       java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3194 
3195       // Print out lock information
3196       if (JavaMonitorsInStackTrace) {
3197         jvf->print_lock_info_on(st, count);
3198       }
3199     } else {
3200       // Ignore non-Java frames
3201     }
3202 
3203     // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
3204     count++;
3205     if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
3206   }
3207 }
3208 
3209 
3210 // JVMTI PopFrame support
3211 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3212   assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3213   if (in_bytes(size_in_bytes) != 0) {
3214     _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3215     _popframe_preserved_args_size = in_bytes(size_in_bytes);
3216     Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3217   }
3218 }
3219 
3220 void* JavaThread::popframe_preserved_args() {
3221   return _popframe_preserved_args;
3222 }
3223 
3224 ByteSize JavaThread::popframe_preserved_args_size() {
3225   return in_ByteSize(_popframe_preserved_args_size);
3226 }
3227 
3228 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3229   int sz = in_bytes(popframe_preserved_args_size());
3230   assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3231   return in_WordSize(sz / wordSize);
3232 }
3233 
3234 void JavaThread::popframe_free_preserved_args() {
3235   assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3236   FREE_C_HEAP_ARRAY(char, (char*)_popframe_preserved_args);
3237   _popframe_preserved_args = NULL;
3238   _popframe_preserved_args_size = 0;
3239 }
3240 
3241 #ifndef PRODUCT
3242 
3243 void JavaThread::trace_frames() {
3244   tty->print_cr("[Describe stack]");
3245   int frame_no = 1;
3246   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3247     tty->print("  %d. ", frame_no++);
3248     fst.current()->print_value_on(tty, this);
3249     tty->cr();
3250   }
3251 }
3252 
3253 class PrintAndVerifyOopClosure: public OopClosure {
3254  protected:
3255   template <class T> inline void do_oop_work(T* p) {
3256     oop obj = RawAccess<>::oop_load(p);
3257     if (obj == NULL) return;
3258     tty->print(INTPTR_FORMAT ": ", p2i(p));
3259     if (oopDesc::is_oop_or_null(obj)) {
3260       if (obj->is_objArray()) {
3261         tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3262       } else {
3263         obj->print();
3264       }
3265     } else {
3266       tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3267     }
3268     tty->cr();
3269   }
3270  public:
3271   virtual void do_oop(oop* p) { do_oop_work(p); }
3272   virtual void do_oop(narrowOop* p)  { do_oop_work(p); }
3273 };
3274 
3275 #ifdef ASSERT
3276 // Print or validate the layout of stack frames
3277 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3278   ResourceMark rm;
3279   PRESERVE_EXCEPTION_MARK;
3280   FrameValues values;
3281   int frame_no = 0;
3282   for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3283     fst.current()->describe(values, ++frame_no);
3284     if (depth == frame_no) break;
3285   }
3286   if (validate_only) {
3287     values.validate();
3288   } else {
3289     tty->print_cr("[Describe stack layout]");
3290     values.print(this);
3291   }
3292 }
3293 #endif
3294 
3295 void JavaThread::trace_stack_from(vframe* start_vf) {
3296   ResourceMark rm;
3297   int vframe_no = 1;
3298   for (vframe* f = start_vf; f; f = f->sender()) {
3299     if (f->is_java_frame()) {
3300       javaVFrame::cast(f)->print_activation(vframe_no++);
3301     } else {
3302       f->print();
3303     }
3304     if (vframe_no > StackPrintLimit) {
3305       tty->print_cr("...<more frames>...");
3306       return;
3307     }
3308   }
3309 }
3310 
3311 
3312 void JavaThread::trace_stack() {
3313   if (!has_last_Java_frame()) return;
3314   ResourceMark rm;
3315   HandleMark   hm;
3316   RegisterMap reg_map(this);
3317   trace_stack_from(last_java_vframe(&reg_map));
3318 }
3319 
3320 
3321 #endif // PRODUCT
3322 
3323 
3324 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3325   assert(reg_map != NULL, "a map must be given");
3326   frame f = last_frame();
3327   for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3328     if (vf->is_java_frame()) return javaVFrame::cast(vf);
3329   }
3330   return NULL;
3331 }
3332 
3333 
3334 Klass* JavaThread::security_get_caller_class(int depth) {
3335   vframeStream vfst(this);
3336   vfst.security_get_caller_frame(depth);
3337   if (!vfst.at_end()) {
3338     return vfst.method()->method_holder();
3339   }
3340   return NULL;
3341 }
3342 
3343 // java.lang.Thread.sleep support
3344 // Returns true if sleep time elapsed as expected, and false
3345 // if the thread was interrupted.
3346 bool JavaThread::sleep(jlong millis) {
3347   assert(this == Thread::current(),  "thread consistency check");
3348 
3349   ParkEvent * const slp = this->_SleepEvent;
3350   // Because there can be races with thread interruption sending an unpark()
3351   // to the event, we explicitly reset it here to avoid an immediate return.
3352   // The actual interrupt state will be checked before we park().
3353   slp->reset();
3354   // Thread interruption establishes a happens-before ordering in the
3355   // Java Memory Model, so we need to ensure we synchronize with the
3356   // interrupt state.
3357   OrderAccess::fence();
3358 
3359   jlong prevtime = os::javaTimeNanos();
3360 
3361   for (;;) {
3362     // interruption has precedence over timing out
3363     if (os::is_interrupted(this, true)) {
3364       return false;
3365     }
3366 
3367     if (millis <= 0) {
3368       return true;
3369     }
3370 
3371     {
3372       ThreadBlockInVM tbivm(this);
3373       OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
3374 
3375       this->set_suspend_equivalent();
3376       // cleared by handle_special_suspend_equivalent_condition() or
3377       // java_suspend_self() via check_and_wait_while_suspended()
3378 
3379       slp->park(millis);
3380 
3381       // were we externally suspended while we were waiting?
3382       this->check_and_wait_while_suspended();
3383     }
3384 
3385     // Update elapsed time tracking
3386     jlong newtime = os::javaTimeNanos();
3387     if (newtime - prevtime < 0) {
3388       // time moving backwards, should only happen if no monotonic clock
3389       // not a guarantee() because JVM should not abort on kernel/glibc bugs
3390       assert(!os::supports_monotonic_clock(),
3391              "unexpected time moving backwards detected in os::sleep()");
3392     } else {
3393       millis -= (newtime - prevtime) / NANOSECS_PER_MILLISEC;
3394     }
3395     prevtime = newtime;
3396   }
3397 }
3398 
3399 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3400   assert(thread->is_Compiler_thread(), "must be compiler thread");
3401   CompileBroker::compiler_thread_loop();
3402 }
3403 
3404 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3405   NMethodSweeper::sweeper_loop();
3406 }
3407 
3408 // Create a CompilerThread
3409 CompilerThread::CompilerThread(CompileQueue* queue,
3410                                CompilerCounters* counters)
3411                                : JavaThread(&compiler_thread_entry) {
3412   _env   = NULL;
3413   _log   = NULL;
3414   _task  = NULL;
3415   _queue = queue;
3416   _counters = counters;
3417   _buffer_blob = NULL;
3418   _compiler = NULL;
3419 
3420   // Compiler uses resource area for compilation, let's bias it to mtCompiler
3421   resource_area()->bias_to(mtCompiler);
3422 
3423 #ifndef PRODUCT
3424   _ideal_graph_printer = NULL;
3425 #endif
3426 }
3427 
3428 CompilerThread::~CompilerThread() {
3429   // Delete objects which were allocated on heap.
3430   delete _counters;
3431 }
3432 
3433 bool CompilerThread::can_call_java() const {
3434   return _compiler != NULL && _compiler->is_jvmci();
3435 }
3436 
3437 // Create sweeper thread
3438 CodeCacheSweeperThread::CodeCacheSweeperThread()
3439 : JavaThread(&sweeper_thread_entry) {
3440   _scanned_compiled_method = NULL;
3441 }
3442 
3443 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3444   JavaThread::oops_do(f, cf);
3445   if (_scanned_compiled_method != NULL && cf != NULL) {
3446     // Safepoints can occur when the sweeper is scanning an nmethod so
3447     // process it here to make sure it isn't unloaded in the middle of
3448     // a scan.
3449     cf->do_code_blob(_scanned_compiled_method);
3450   }
3451 }
3452 
3453 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3454   JavaThread::nmethods_do(cf);
3455   if (_scanned_compiled_method != NULL && cf != NULL) {
3456     // Safepoints can occur when the sweeper is scanning an nmethod so
3457     // process it here to make sure it isn't unloaded in the middle of
3458     // a scan.
3459     cf->do_code_blob(_scanned_compiled_method);
3460   }
3461 }
3462 
3463 
3464 // ======= Threads ========
3465 
3466 // The Threads class links together all active threads, and provides
3467 // operations over all threads. It is protected by the Threads_lock,
3468 // which is also used in other global contexts like safepointing.
3469 // ThreadsListHandles are used to safely perform operations on one
3470 // or more threads without the risk of the thread exiting during the
3471 // operation.
3472 //
3473 // Note: The Threads_lock is currently more widely used than we
3474 // would like. We are actively migrating Threads_lock uses to other
3475 // mechanisms in order to reduce Threads_lock contention.
3476 
3477 int         Threads::_number_of_threads = 0;
3478 int         Threads::_number_of_non_daemon_threads = 0;
3479 int         Threads::_return_code = 0;
3480 uintx       Threads::_thread_claim_token = 1; // Never zero.
3481 size_t      JavaThread::_stack_size_at_create = 0;
3482 
3483 #ifdef ASSERT
3484 bool        Threads::_vm_complete = false;
3485 #endif
3486 
3487 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
3488   Prefetch::read((void*)addr, prefetch_interval);
3489   return *addr;
3490 }
3491 
3492 // Possibly the ugliest for loop the world has seen. C++ does not allow
3493 // multiple types in the declaration section of the for loop. In this case
3494 // we are only dealing with pointers and hence can cast them. It looks ugly
3495 // but macros are ugly and therefore it's fine to make things absurdly ugly.
3496 #define DO_JAVA_THREADS(LIST, X)                                                                                          \
3497     for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes,                           \
3498              *MACRO_list = (JavaThread*)(LIST),                                                                           \
3499              **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(),  \
3500              **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(),                                     \
3501              *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval);                 \
3502          MACRO_current_p != MACRO_end;                                                                                    \
3503          MACRO_current_p++,                                                                                               \
3504              X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval))
3505 
3506 // All JavaThreads
3507 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X)
3508 
3509 // All NonJavaThreads (i.e., every non-JavaThread in the system).
3510 void Threads::non_java_threads_do(ThreadClosure* tc) {
3511   NoSafepointVerifier nsv;
3512   for (NonJavaThread::Iterator njti; !njti.end(); njti.step()) {
3513     tc->do_thread(njti.current());
3514   }
3515 }
3516 
3517 // All JavaThreads
3518 void Threads::java_threads_do(ThreadClosure* tc) {
3519   assert_locked_or_safepoint(Threads_lock);
3520   // ALL_JAVA_THREADS iterates through all JavaThreads.
3521   ALL_JAVA_THREADS(p) {
3522     tc->do_thread(p);
3523   }
3524 }
3525 
3526 void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) {
3527   assert_locked_or_safepoint(Threads_lock);
3528   java_threads_do(tc);
3529   tc->do_thread(VMThread::vm_thread());
3530 }
3531 
3532 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system).
3533 void Threads::threads_do(ThreadClosure* tc) {
3534   assert_locked_or_safepoint(Threads_lock);
3535   java_threads_do(tc);
3536   non_java_threads_do(tc);
3537 }
3538 
3539 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
3540   uintx claim_token = Threads::thread_claim_token();
3541   ALL_JAVA_THREADS(p) {
3542     if (p->claim_threads_do(is_par, claim_token)) {
3543       tc->do_thread(p);
3544     }
3545   }
3546   VMThread* vmt = VMThread::vm_thread();
3547   if (vmt->claim_threads_do(is_par, claim_token)) {
3548     tc->do_thread(vmt);
3549   }
3550 }
3551 
3552 // The system initialization in the library has three phases.
3553 //
3554 // Phase 1: java.lang.System class initialization
3555 //     java.lang.System is a primordial class loaded and initialized
3556 //     by the VM early during startup.  java.lang.System.<clinit>
3557 //     only does registerNatives and keeps the rest of the class
3558 //     initialization work later until thread initialization completes.
3559 //
3560 //     System.initPhase1 initializes the system properties, the static
3561 //     fields in, out, and err. Set up java signal handlers, OS-specific
3562 //     system settings, and thread group of the main thread.
3563 static void call_initPhase1(TRAPS) {
3564   Klass* klass =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3565   JavaValue result(T_VOID);
3566   JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3567                                          vmSymbols::void_method_signature(), CHECK);
3568 }
3569 
3570 // Phase 2. Module system initialization
3571 //     This will initialize the module system.  Only java.base classes
3572 //     can be loaded until phase 2 completes.
3573 //
3574 //     Call System.initPhase2 after the compiler initialization and jsr292
3575 //     classes get initialized because module initialization runs a lot of java
3576 //     code, that for performance reasons, should be compiled.  Also, this will
3577 //     enable the startup code to use lambda and other language features in this
3578 //     phase and onward.
3579 //
3580 //     After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3581 static void call_initPhase2(TRAPS) {
3582   TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3583 
3584   Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3585 
3586   JavaValue result(T_INT);
3587   JavaCallArguments args;
3588   args.push_int(DisplayVMOutputToStderr);
3589   args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3590   JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3591                                          vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3592   if (result.get_jint() != JNI_OK) {
3593     vm_exit_during_initialization(); // no message or exception
3594   }
3595 
3596   universe_post_module_init();
3597 }
3598 
3599 // Phase 3. final setup - set security manager, system class loader and TCCL
3600 //
3601 //     This will instantiate and set the security manager, set the system class
3602 //     loader as well as the thread context class loader.  The security manager
3603 //     and system class loader may be a custom class loaded from -Xbootclasspath/a,
3604 //     other modules or the application's classpath.
3605 static void call_initPhase3(TRAPS) {
3606   Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3607   JavaValue result(T_VOID);
3608   JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3609                                          vmSymbols::void_method_signature(), CHECK);
3610 }
3611 
3612 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3613   TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3614 
3615   if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3616     create_vm_init_libraries();
3617   }
3618 
3619   initialize_class(vmSymbols::java_lang_String(), CHECK);
3620 
3621   // Inject CompactStrings value after the static initializers for String ran.
3622   java_lang_String::set_compact_strings(CompactStrings);
3623 
3624   // Initialize java_lang.System (needed before creating the thread)
3625   initialize_class(vmSymbols::java_lang_System(), CHECK);
3626   // The VM creates & returns objects of this class. Make sure it's initialized.
3627   initialize_class(vmSymbols::java_lang_Class(), CHECK);
3628   initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3629   Handle thread_group = create_initial_thread_group(CHECK);
3630   Universe::set_main_thread_group(thread_group());
3631   initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3632   oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3633   main_thread->set_threadObj(thread_object);
3634 
3635   // Set thread status to running since main thread has
3636   // been started and running.
3637   java_lang_Thread::set_thread_status(thread_object,
3638                                       java_lang_Thread::RUNNABLE);
3639 
3640   // The VM creates objects of this class.
3641   initialize_class(vmSymbols::java_lang_Module(), CHECK);
3642 
3643 #ifdef ASSERT
3644   InstanceKlass *k = SystemDictionary::UnsafeConstants_klass();
3645   assert(k->is_not_initialized(), "UnsafeConstants should not already be initialized");
3646 #endif
3647 
3648   // initialize the hardware-specific constants needed by Unsafe
3649   initialize_class(vmSymbols::jdk_internal_misc_UnsafeConstants(), CHECK);
3650   jdk_internal_misc_UnsafeConstants::set_unsafe_constants();
3651 
3652   // The VM preresolves methods to these classes. Make sure that they get initialized
3653   initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3654   initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3655 
3656   // Phase 1 of the system initialization in the library, java.lang.System class initialization
3657   call_initPhase1(CHECK);
3658 
3659   // get the Java runtime name after java.lang.System is initialized
3660   JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3661   JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3662 
3663   // an instance of OutOfMemory exception has been allocated earlier
3664   initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3665   initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3666   initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3667   initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3668   initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3669   initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3670   initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3671   initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3672 
3673   // Eager box cache initialization only if AOT is on and any library is loaded.
3674   AOTLoader::initialize_box_caches(CHECK);
3675 }
3676 
3677 void Threads::initialize_jsr292_core_classes(TRAPS) {
3678   TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3679 
3680   initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3681   initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3682   initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3683   initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3684 }
3685 
3686 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3687   extern void JDK_Version_init();
3688 
3689   // Preinitialize version info.
3690   VM_Version::early_initialize();
3691 
3692   // Check version
3693   if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3694 
3695   // Initialize library-based TLS
3696   ThreadLocalStorage::init();
3697 
3698   // Initialize the output stream module
3699   ostream_init();
3700 
3701   // Process java launcher properties.
3702   Arguments::process_sun_java_launcher_properties(args);
3703 
3704   // Initialize the os module
3705   os::init();
3706 
3707   // Record VM creation timing statistics
3708   TraceVmCreationTime create_vm_timer;
3709   create_vm_timer.start();
3710 
3711   // Initialize system properties.
3712   Arguments::init_system_properties();
3713 
3714   // So that JDK version can be used as a discriminator when parsing arguments
3715   JDK_Version_init();
3716 
3717   // Update/Initialize System properties after JDK version number is known
3718   Arguments::init_version_specific_system_properties();
3719 
3720   // Make sure to initialize log configuration *before* parsing arguments
3721   LogConfiguration::initialize(create_vm_timer.begin_time());
3722 
3723   // Parse arguments
3724   // Note: this internally calls os::init_container_support()
3725   jint parse_result = Arguments::parse(args);
3726   if (parse_result != JNI_OK) return parse_result;
3727 
3728   os::init_before_ergo();
3729 
3730   jint ergo_result = Arguments::apply_ergo();
3731   if (ergo_result != JNI_OK) return ergo_result;
3732 
3733   // Final check of all ranges after ergonomics which may change values.
3734   if (!JVMFlagRangeList::check_ranges()) {
3735     return JNI_EINVAL;
3736   }
3737 
3738   // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3739   bool constraint_result = JVMFlagConstraintList::check_constraints(JVMFlagConstraint::AfterErgo);
3740   if (!constraint_result) {
3741     return JNI_EINVAL;
3742   }
3743 
3744   JVMFlagWriteableList::mark_startup();
3745 
3746   if (PauseAtStartup) {
3747     os::pause();
3748   }
3749 
3750   HOTSPOT_VM_INIT_BEGIN();
3751 
3752   // Timing (must come after argument parsing)
3753   TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3754 
3755   // Initialize the os module after parsing the args
3756   jint os_init_2_result = os::init_2();
3757   if (os_init_2_result != JNI_OK) return os_init_2_result;
3758 
3759 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT
3760   // Initialize assert poison page mechanism.
3761   if (ShowRegistersOnAssert) {
3762     initialize_assert_poison();
3763   }
3764 #endif // CAN_SHOW_REGISTERS_ON_ASSERT
3765 
3766   SafepointMechanism::initialize();
3767 
3768   jint adjust_after_os_result = Arguments::adjust_after_os();
3769   if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3770 
3771   // Initialize output stream logging
3772   ostream_init_log();
3773 
3774   // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3775   // Must be before create_vm_init_agents()
3776   if (Arguments::init_libraries_at_startup()) {
3777     convert_vm_init_libraries_to_agents();
3778   }
3779 
3780   // Launch -agentlib/-agentpath and converted -Xrun agents
3781   if (Arguments::init_agents_at_startup()) {
3782     create_vm_init_agents();
3783   }
3784 
3785   // Initialize Threads state
3786   _number_of_threads = 0;
3787   _number_of_non_daemon_threads = 0;
3788 
3789   // Initialize global data structures and create system classes in heap
3790   vm_init_globals();
3791 
3792 #if INCLUDE_JVMCI
3793   if (JVMCICounterSize > 0) {
3794     JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtJVMCI);
3795     memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3796   } else {
3797     JavaThread::_jvmci_old_thread_counters = NULL;
3798   }
3799 #endif // INCLUDE_JVMCI
3800 
3801   // Attach the main thread to this os thread
3802   JavaThread* main_thread = new JavaThread();
3803   main_thread->set_thread_state(_thread_in_vm);
3804   main_thread->initialize_thread_current();
3805   // must do this before set_active_handles
3806   main_thread->record_stack_base_and_size();
3807   main_thread->register_thread_stack_with_NMT();
3808   main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3809 
3810   if (!main_thread->set_as_starting_thread()) {
3811     vm_shutdown_during_initialization(
3812                                       "Failed necessary internal allocation. Out of swap space");
3813     main_thread->smr_delete();
3814     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3815     return JNI_ENOMEM;
3816   }
3817 
3818   // Enable guard page *after* os::create_main_thread(), otherwise it would
3819   // crash Linux VM, see notes in os_linux.cpp.
3820   main_thread->create_stack_guard_pages();
3821 
3822   // Initialize Java-Level synchronization subsystem
3823   ObjectMonitor::Initialize();
3824 
3825   // Initialize global modules
3826   jint status = init_globals();
3827   if (status != JNI_OK) {
3828     main_thread->smr_delete();
3829     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3830     return status;
3831   }
3832 
3833   JFR_ONLY(Jfr::on_vm_init();)
3834 
3835   // Should be done after the heap is fully created
3836   main_thread->cache_global_variables();
3837 
3838   HandleMark hm;
3839 
3840   { MutexLocker mu(Threads_lock);
3841     Threads::add(main_thread);
3842   }
3843 
3844   // Any JVMTI raw monitors entered in onload will transition into
3845   // real raw monitor. VM is setup enough here for raw monitor enter.
3846   JvmtiExport::transition_pending_onload_raw_monitors();
3847 
3848   // Create the VMThread
3849   { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3850 
3851   VMThread::create();
3852     Thread* vmthread = VMThread::vm_thread();
3853 
3854     if (!os::create_thread(vmthread, os::vm_thread)) {
3855       vm_exit_during_initialization("Cannot create VM thread. "
3856                                     "Out of system resources.");
3857     }
3858 
3859     // Wait for the VM thread to become ready, and VMThread::run to initialize
3860     // Monitors can have spurious returns, must always check another state flag
3861     {
3862       MonitorLocker ml(Notify_lock);
3863       os::start_thread(vmthread);
3864       while (vmthread->active_handles() == NULL) {
3865         ml.wait();
3866       }
3867     }
3868   }
3869 
3870   assert(Universe::is_fully_initialized(), "not initialized");
3871   if (VerifyDuringStartup) {
3872     // Make sure we're starting with a clean slate.
3873     VM_Verify verify_op;
3874     VMThread::execute(&verify_op);
3875   }
3876 
3877   // We need this to update the java.vm.info property in case any flags used
3878   // to initially define it have been changed. This is needed for both CDS and
3879   // AOT, since UseSharedSpaces and UseAOT may be changed after java.vm.info
3880   // is initially computed. See Abstract_VM_Version::vm_info_string().
3881   // This update must happen before we initialize the java classes, but
3882   // after any initialization logic that might modify the flags.
3883   Arguments::update_vm_info_property(VM_Version::vm_info_string());
3884 
3885   Thread* THREAD = Thread::current();
3886 
3887   // Always call even when there are not JVMTI environments yet, since environments
3888   // may be attached late and JVMTI must track phases of VM execution
3889   JvmtiExport::enter_early_start_phase();
3890 
3891   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3892   JvmtiExport::post_early_vm_start();
3893 
3894   initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3895 
3896   quicken_jni_functions();
3897 
3898   // No more stub generation allowed after that point.
3899   StubCodeDesc::freeze();
3900 
3901   // Set flag that basic initialization has completed. Used by exceptions and various
3902   // debug stuff, that does not work until all basic classes have been initialized.
3903   set_init_completed();
3904 
3905   LogConfiguration::post_initialize();
3906   Metaspace::post_initialize();
3907 
3908   HOTSPOT_VM_INIT_END();
3909 
3910   // record VM initialization completion time
3911 #if INCLUDE_MANAGEMENT
3912   Management::record_vm_init_completed();
3913 #endif // INCLUDE_MANAGEMENT
3914 
3915   // Signal Dispatcher needs to be started before VMInit event is posted
3916   os::initialize_jdk_signal_support(CHECK_JNI_ERR);
3917 
3918   // Start Attach Listener if +StartAttachListener or it can't be started lazily
3919   if (!DisableAttachMechanism) {
3920     AttachListener::vm_start();
3921     if (StartAttachListener || AttachListener::init_at_startup()) {
3922       AttachListener::init();
3923     }
3924   }
3925 
3926   // Launch -Xrun agents
3927   // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3928   // back-end can launch with -Xdebug -Xrunjdwp.
3929   if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3930     create_vm_init_libraries();
3931   }
3932 
3933   if (CleanChunkPoolAsync) {
3934     Chunk::start_chunk_pool_cleaner_task();
3935   }
3936 
3937 
3938   // initialize compiler(s)
3939 #if defined(COMPILER1) || COMPILER2_OR_JVMCI
3940 #if INCLUDE_JVMCI
3941   bool force_JVMCI_intialization = false;
3942   if (EnableJVMCI) {
3943     // Initialize JVMCI eagerly when it is explicitly requested.
3944     // Or when JVMCILibDumpJNIConfig or JVMCIPrintProperties is enabled.
3945     force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties || JVMCILibDumpJNIConfig;
3946 
3947     if (!force_JVMCI_intialization) {
3948       // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3949       // compilations via JVMCI will not actually block until JVMCI is initialized.
3950       force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3951     }
3952   }
3953 #endif
3954   CompileBroker::compilation_init_phase1(CHECK_JNI_ERR);
3955   // Postpone completion of compiler initialization to after JVMCI
3956   // is initialized to avoid timeouts of blocking compilations.
3957   if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) {
3958     CompileBroker::compilation_init_phase2();
3959   }
3960 #endif
3961 
3962   // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3963   // It is done after compilers are initialized, because otherwise compilations of
3964   // signature polymorphic MH intrinsics can be missed
3965   // (see SystemDictionary::find_method_handle_intrinsic).
3966   initialize_jsr292_core_classes(CHECK_JNI_ERR);
3967 
3968   // This will initialize the module system.  Only java.base classes can be
3969   // loaded until phase 2 completes
3970   call_initPhase2(CHECK_JNI_ERR);
3971 
3972   // Always call even when there are not JVMTI environments yet, since environments
3973   // may be attached late and JVMTI must track phases of VM execution
3974   JvmtiExport::enter_start_phase();
3975 
3976   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3977   JvmtiExport::post_vm_start();
3978 
3979   // Final system initialization including security manager and system class loader
3980   call_initPhase3(CHECK_JNI_ERR);
3981 
3982   // cache the system and platform class loaders
3983   SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
3984 
3985 #if INCLUDE_CDS
3986   // capture the module path info from the ModuleEntryTable
3987   ClassLoader::initialize_module_path(THREAD);
3988 #endif
3989 
3990 #if INCLUDE_JVMCI
3991   if (force_JVMCI_intialization) {
3992     JVMCI::initialize_compiler(CHECK_JNI_ERR);
3993     CompileBroker::compilation_init_phase2();
3994   }
3995 #endif
3996 
3997   // Always call even when there are not JVMTI environments yet, since environments
3998   // may be attached late and JVMTI must track phases of VM execution
3999   JvmtiExport::enter_live_phase();
4000 
4001   // Make perfmemory accessible
4002   PerfMemory::set_accessible(true);
4003 
4004   // Notify JVMTI agents that VM initialization is complete - nop if no agents.
4005   JvmtiExport::post_vm_initialized();
4006 
4007   JFR_ONLY(Jfr::on_vm_start();)
4008 
4009 #if INCLUDE_MANAGEMENT
4010   Management::initialize(THREAD);
4011 
4012   if (HAS_PENDING_EXCEPTION) {
4013     // management agent fails to start possibly due to
4014     // configuration problem and is responsible for printing
4015     // stack trace if appropriate. Simply exit VM.
4016     vm_exit(1);
4017   }
4018 #endif // INCLUDE_MANAGEMENT
4019 
4020   if (MemProfiling)                   MemProfiler::engage();
4021   StatSampler::engage();
4022   if (CheckJNICalls)                  JniPeriodicChecker::engage();
4023 
4024   BiasedLocking::init();
4025 
4026 #if INCLUDE_RTM_OPT
4027   RTMLockingCounters::init();
4028 #endif
4029 
4030   call_postVMInitHook(THREAD);
4031   // The Java side of PostVMInitHook.run must deal with all
4032   // exceptions and provide means of diagnosis.
4033   if (HAS_PENDING_EXCEPTION) {
4034     CLEAR_PENDING_EXCEPTION;
4035   }
4036 
4037   {
4038     MutexLocker ml(PeriodicTask_lock);
4039     // Make sure the WatcherThread can be started by WatcherThread::start()
4040     // or by dynamic enrollment.
4041     WatcherThread::make_startable();
4042     // Start up the WatcherThread if there are any periodic tasks
4043     // NOTE:  All PeriodicTasks should be registered by now. If they
4044     //   aren't, late joiners might appear to start slowly (we might
4045     //   take a while to process their first tick).
4046     if (PeriodicTask::num_tasks() > 0) {
4047       WatcherThread::start();
4048     }
4049   }
4050 
4051   create_vm_timer.end();
4052 #ifdef ASSERT
4053   _vm_complete = true;
4054 #endif
4055 
4056   if (DumpSharedSpaces) {
4057     MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
4058     ShouldNotReachHere();
4059   }
4060 
4061   return JNI_OK;
4062 }
4063 
4064 // type for the Agent_OnLoad and JVM_OnLoad entry points
4065 extern "C" {
4066   typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
4067 }
4068 // Find a command line agent library and return its entry point for
4069 //         -agentlib:  -agentpath:   -Xrun
4070 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
4071 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
4072                                     const char *on_load_symbols[],
4073                                     size_t num_symbol_entries) {
4074   OnLoadEntry_t on_load_entry = NULL;
4075   void *library = NULL;
4076 
4077   if (!agent->valid()) {
4078     char buffer[JVM_MAXPATHLEN];
4079     char ebuf[1024] = "";
4080     const char *name = agent->name();
4081     const char *msg = "Could not find agent library ";
4082 
4083     // First check to see if agent is statically linked into executable
4084     if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
4085       library = agent->os_lib();
4086     } else if (agent->is_absolute_path()) {
4087       library = os::dll_load(name, ebuf, sizeof ebuf);
4088       if (library == NULL) {
4089         const char *sub_msg = " in absolute path, with error: ";
4090         size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
4091         char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4092         jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4093         // If we can't find the agent, exit.
4094         vm_exit_during_initialization(buf, NULL);
4095         FREE_C_HEAP_ARRAY(char, buf);
4096       }
4097     } else {
4098       // Try to load the agent from the standard dll directory
4099       if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
4100                              name)) {
4101         library = os::dll_load(buffer, ebuf, sizeof ebuf);
4102       }
4103       if (library == NULL) { // Try the library path directory.
4104         if (os::dll_build_name(buffer, sizeof(buffer), name)) {
4105           library = os::dll_load(buffer, ebuf, sizeof ebuf);
4106         }
4107         if (library == NULL) {
4108           const char *sub_msg = " on the library path, with error: ";
4109           const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image.";
4110 
4111           size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) +
4112                        strlen(ebuf) + strlen(sub_msg2) + 1;
4113           char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4114           if (!agent->is_instrument_lib()) {
4115             jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4116           } else {
4117             jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2);
4118           }
4119           // If we can't find the agent, exit.
4120           vm_exit_during_initialization(buf, NULL);
4121           FREE_C_HEAP_ARRAY(char, buf);
4122         }
4123       }
4124     }
4125     agent->set_os_lib(library);
4126     agent->set_valid();
4127   }
4128 
4129   // Find the OnLoad function.
4130   on_load_entry =
4131     CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
4132                                                           false,
4133                                                           on_load_symbols,
4134                                                           num_symbol_entries));
4135   return on_load_entry;
4136 }
4137 
4138 // Find the JVM_OnLoad entry point
4139 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
4140   const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
4141   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4142 }
4143 
4144 // Find the Agent_OnLoad entry point
4145 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
4146   const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
4147   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4148 }
4149 
4150 // For backwards compatibility with -Xrun
4151 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
4152 // treated like -agentpath:
4153 // Must be called before agent libraries are created
4154 void Threads::convert_vm_init_libraries_to_agents() {
4155   AgentLibrary* agent;
4156   AgentLibrary* next;
4157 
4158   for (agent = Arguments::libraries(); agent != NULL; agent = next) {
4159     next = agent->next();  // cache the next agent now as this agent may get moved off this list
4160     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4161 
4162     // If there is an JVM_OnLoad function it will get called later,
4163     // otherwise see if there is an Agent_OnLoad
4164     if (on_load_entry == NULL) {
4165       on_load_entry = lookup_agent_on_load(agent);
4166       if (on_load_entry != NULL) {
4167         // switch it to the agent list -- so that Agent_OnLoad will be called,
4168         // JVM_OnLoad won't be attempted and Agent_OnUnload will
4169         Arguments::convert_library_to_agent(agent);
4170       } else {
4171         vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
4172       }
4173     }
4174   }
4175 }
4176 
4177 // Create agents for -agentlib:  -agentpath:  and converted -Xrun
4178 // Invokes Agent_OnLoad
4179 // Called very early -- before JavaThreads exist
4180 void Threads::create_vm_init_agents() {
4181   extern struct JavaVM_ main_vm;
4182   AgentLibrary* agent;
4183 
4184   JvmtiExport::enter_onload_phase();
4185 
4186   for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4187     // CDS dumping does not support native JVMTI agent.
4188     // CDS dumping supports Java agent if the AllowArchivingWithJavaAgent diagnostic option is specified.
4189     if (DumpSharedSpaces || DynamicDumpSharedSpaces) {
4190       if(!agent->is_instrument_lib()) {
4191         vm_exit_during_cds_dumping("CDS dumping does not support native JVMTI agent, name", agent->name());
4192       } else if (!AllowArchivingWithJavaAgent) {
4193         vm_exit_during_cds_dumping(
4194           "Must enable AllowArchivingWithJavaAgent in order to run Java agent during CDS dumping");
4195       }
4196     }
4197 
4198     OnLoadEntry_t  on_load_entry = lookup_agent_on_load(agent);
4199 
4200     if (on_load_entry != NULL) {
4201       // Invoke the Agent_OnLoad function
4202       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4203       if (err != JNI_OK) {
4204         vm_exit_during_initialization("agent library failed to init", agent->name());
4205       }
4206     } else {
4207       vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4208     }
4209   }
4210 
4211   JvmtiExport::enter_primordial_phase();
4212 }
4213 
4214 extern "C" {
4215   typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4216 }
4217 
4218 void Threads::shutdown_vm_agents() {
4219   // Send any Agent_OnUnload notifications
4220   const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4221   size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4222   extern struct JavaVM_ main_vm;
4223   for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4224 
4225     // Find the Agent_OnUnload function.
4226     Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4227                                                    os::find_agent_function(agent,
4228                                                    false,
4229                                                    on_unload_symbols,
4230                                                    num_symbol_entries));
4231 
4232     // Invoke the Agent_OnUnload function
4233     if (unload_entry != NULL) {
4234       JavaThread* thread = JavaThread::current();
4235       ThreadToNativeFromVM ttn(thread);
4236       HandleMark hm(thread);
4237       (*unload_entry)(&main_vm);
4238     }
4239   }
4240 }
4241 
4242 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4243 // Invokes JVM_OnLoad
4244 void Threads::create_vm_init_libraries() {
4245   extern struct JavaVM_ main_vm;
4246   AgentLibrary* agent;
4247 
4248   for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4249     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4250 
4251     if (on_load_entry != NULL) {
4252       // Invoke the JVM_OnLoad function
4253       JavaThread* thread = JavaThread::current();
4254       ThreadToNativeFromVM ttn(thread);
4255       HandleMark hm(thread);
4256       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4257       if (err != JNI_OK) {
4258         vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4259       }
4260     } else {
4261       vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4262     }
4263   }
4264 }
4265 
4266 
4267 // Last thread running calls java.lang.Shutdown.shutdown()
4268 void JavaThread::invoke_shutdown_hooks() {
4269   HandleMark hm(this);
4270 
4271   // We could get here with a pending exception, if so clear it now.
4272   if (this->has_pending_exception()) {
4273     this->clear_pending_exception();
4274   }
4275 
4276   EXCEPTION_MARK;
4277   Klass* shutdown_klass =
4278     SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4279                                       THREAD);
4280   if (shutdown_klass != NULL) {
4281     // SystemDictionary::resolve_or_null will return null if there was
4282     // an exception.  If we cannot load the Shutdown class, just don't
4283     // call Shutdown.shutdown() at all.  This will mean the shutdown hooks
4284     // won't be run.  Note that if a shutdown hook was registered,
4285     // the Shutdown class would have already been loaded
4286     // (Runtime.addShutdownHook will load it).
4287     JavaValue result(T_VOID);
4288     JavaCalls::call_static(&result,
4289                            shutdown_klass,
4290                            vmSymbols::shutdown_name(),
4291                            vmSymbols::void_method_signature(),
4292                            THREAD);
4293   }
4294   CLEAR_PENDING_EXCEPTION;
4295 }
4296 
4297 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4298 // the program falls off the end of main(). Another VM exit path is through
4299 // vm_exit() when the program calls System.exit() to return a value or when
4300 // there is a serious error in VM. The two shutdown paths are not exactly
4301 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4302 // and VM_Exit op at VM level.
4303 //
4304 // Shutdown sequence:
4305 //   + Shutdown native memory tracking if it is on
4306 //   + Wait until we are the last non-daemon thread to execute
4307 //     <-- every thing is still working at this moment -->
4308 //   + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4309 //        shutdown hooks
4310 //   + Call before_exit(), prepare for VM exit
4311 //      > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4312 //        currently the only user of this mechanism is File.deleteOnExit())
4313 //      > stop StatSampler, watcher thread, CMS threads,
4314 //        post thread end and vm death events to JVMTI,
4315 //        stop signal thread
4316 //   + Call JavaThread::exit(), it will:
4317 //      > release JNI handle blocks, remove stack guard pages
4318 //      > remove this thread from Threads list
4319 //     <-- no more Java code from this thread after this point -->
4320 //   + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4321 //     the compiler threads at safepoint
4322 //     <-- do not use anything that could get blocked by Safepoint -->
4323 //   + Disable tracing at JNI/JVM barriers
4324 //   + Set _vm_exited flag for threads that are still running native code
4325 //   + Call exit_globals()
4326 //      > deletes tty
4327 //      > deletes PerfMemory resources
4328 //   + Delete this thread
4329 //   + Return to caller
4330 
4331 bool Threads::destroy_vm() {
4332   JavaThread* thread = JavaThread::current();
4333 
4334 #ifdef ASSERT
4335   _vm_complete = false;
4336 #endif
4337   // Wait until we are the last non-daemon thread to execute
4338   { MonitorLocker nu(Threads_lock);
4339     while (Threads::number_of_non_daemon_threads() > 1)
4340       // This wait should make safepoint checks, wait without a timeout,
4341       // and wait as a suspend-equivalent condition.
4342       nu.wait(0, Mutex::_as_suspend_equivalent_flag);
4343   }
4344 
4345   EventShutdown e;
4346   if (e.should_commit()) {
4347     e.set_reason("No remaining non-daemon Java threads");
4348     e.commit();
4349   }
4350 
4351   // Hang forever on exit if we are reporting an error.
4352   if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4353     os::infinite_sleep();
4354   }
4355   os::wait_for_keypress_at_exit();
4356 
4357   // run Java level shutdown hooks
4358   thread->invoke_shutdown_hooks();
4359 
4360   before_exit(thread);
4361 
4362   thread->exit(true);
4363 
4364   // Stop VM thread.
4365   {
4366     // 4945125 The vm thread comes to a safepoint during exit.
4367     // GC vm_operations can get caught at the safepoint, and the
4368     // heap is unparseable if they are caught. Grab the Heap_lock
4369     // to prevent this. The GC vm_operations will not be able to
4370     // queue until after the vm thread is dead. After this point,
4371     // we'll never emerge out of the safepoint before the VM exits.
4372 
4373     MutexLocker ml(Heap_lock, Mutex::_no_safepoint_check_flag);
4374 
4375     VMThread::wait_for_vm_thread_exit();
4376     assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4377     VMThread::destroy();
4378   }
4379 
4380   // Now, all Java threads are gone except daemon threads. Daemon threads
4381   // running Java code or in VM are stopped by the Safepoint. However,
4382   // daemon threads executing native code are still running.  But they
4383   // will be stopped at native=>Java/VM barriers. Note that we can't
4384   // simply kill or suspend them, as it is inherently deadlock-prone.
4385 
4386   VM_Exit::set_vm_exited();
4387 
4388   // Clean up ideal graph printers after the VMThread has started
4389   // the final safepoint which will block all the Compiler threads.
4390   // Note that this Thread has already logically exited so the
4391   // clean_up() function's use of a JavaThreadIteratorWithHandle
4392   // would be a problem except set_vm_exited() has remembered the
4393   // shutdown thread which is granted a policy exception.
4394 #if defined(COMPILER2) && !defined(PRODUCT)
4395   IdealGraphPrinter::clean_up();
4396 #endif
4397 
4398   notify_vm_shutdown();
4399 
4400   // exit_globals() will delete tty
4401   exit_globals();
4402 
4403   // We are after VM_Exit::set_vm_exited() so we can't call
4404   // thread->smr_delete() or we will block on the Threads_lock.
4405   // Deleting the shutdown thread here is safe because another
4406   // JavaThread cannot have an active ThreadsListHandle for
4407   // this JavaThread.
4408   delete thread;
4409 
4410 #if INCLUDE_JVMCI
4411   if (JVMCICounterSize > 0) {
4412     FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4413   }
4414 #endif
4415 
4416   LogConfiguration::finalize();
4417 
4418   return true;
4419 }
4420 
4421 
4422 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4423   if (version == JNI_VERSION_1_1) return JNI_TRUE;
4424   return is_supported_jni_version(version);
4425 }
4426 
4427 
4428 jboolean Threads::is_supported_jni_version(jint version) {
4429   if (version == JNI_VERSION_1_2) return JNI_TRUE;
4430   if (version == JNI_VERSION_1_4) return JNI_TRUE;
4431   if (version == JNI_VERSION_1_6) return JNI_TRUE;
4432   if (version == JNI_VERSION_1_8) return JNI_TRUE;
4433   if (version == JNI_VERSION_9) return JNI_TRUE;
4434   if (version == JNI_VERSION_10) return JNI_TRUE;
4435   return JNI_FALSE;
4436 }
4437 
4438 
4439 void Threads::add(JavaThread* p, bool force_daemon) {
4440   // The threads lock must be owned at this point
4441   assert(Threads_lock->owned_by_self(), "must have threads lock");
4442 
4443   BarrierSet::barrier_set()->on_thread_attach(p);
4444 
4445   // Once a JavaThread is added to the Threads list, smr_delete() has
4446   // to be used to delete it. Otherwise we can just delete it directly.
4447   p->set_on_thread_list();
4448 
4449   _number_of_threads++;
4450   oop threadObj = p->threadObj();
4451   bool daemon = true;
4452   // Bootstrapping problem: threadObj can be null for initial
4453   // JavaThread (or for threads attached via JNI)
4454   if ((!force_daemon) && !is_daemon((threadObj))) {
4455     _number_of_non_daemon_threads++;
4456     daemon = false;
4457   }
4458 
4459   ThreadService::add_thread(p, daemon);
4460 
4461   // Maintain fast thread list
4462   ThreadsSMRSupport::add_thread(p);
4463 
4464   // Possible GC point.
4465   Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4466 }
4467 
4468 void Threads::remove(JavaThread* p, bool is_daemon) {
4469 
4470   // Reclaim the ObjectMonitors from the om_in_use_list and om_free_list of the moribund thread.
4471   ObjectSynchronizer::om_flush(p);
4472 
4473   // Extra scope needed for Thread_lock, so we can check
4474   // that we do not remove thread without safepoint code notice
4475   { MonitorLocker ml(Threads_lock);
4476 
4477     assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present");
4478 
4479     // Maintain fast thread list
4480     ThreadsSMRSupport::remove_thread(p);
4481 
4482     _number_of_threads--;
4483     if (!is_daemon) {
4484       _number_of_non_daemon_threads--;
4485 
4486       // Only one thread left, do a notify on the Threads_lock so a thread waiting
4487       // on destroy_vm will wake up.
4488       if (number_of_non_daemon_threads() == 1) {
4489         ml.notify_all();
4490       }
4491     }
4492     ThreadService::remove_thread(p, is_daemon);
4493 
4494     // Make sure that safepoint code disregard this thread. This is needed since
4495     // the thread might mess around with locks after this point. This can cause it
4496     // to do callbacks into the safepoint code. However, the safepoint code is not aware
4497     // of this thread since it is removed from the queue.
4498     p->set_terminated_value();
4499   } // unlock Threads_lock
4500 
4501   // Since Events::log uses a lock, we grab it outside the Threads_lock
4502   Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4503 }
4504 
4505 // Operations on the Threads list for GC.  These are not explicitly locked,
4506 // but the garbage collector must provide a safe context for them to run.
4507 // In particular, these things should never be called when the Threads_lock
4508 // is held by some other thread. (Note: the Safepoint abstraction also
4509 // uses the Threads_lock to guarantee this property. It also makes sure that
4510 // all threads gets blocked when exiting or starting).
4511 
4512 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4513   ALL_JAVA_THREADS(p) {
4514     p->oops_do(f, cf);
4515   }
4516   VMThread::vm_thread()->oops_do(f, cf);
4517 }
4518 
4519 void Threads::change_thread_claim_token() {
4520   if (++_thread_claim_token == 0) {
4521     // On overflow of the token counter, there is a risk of future
4522     // collisions between a new global token value and a stale token
4523     // for a thread, because not all iterations visit all threads.
4524     // (Though it's pretty much a theoretical concern for non-trivial
4525     // token counter sizes.)  To deal with the possibility, reset all
4526     // the thread tokens to zero on global token overflow.
4527     struct ResetClaims : public ThreadClosure {
4528       virtual void do_thread(Thread* t) {
4529         t->claim_threads_do(false, 0);
4530       }
4531     } reset_claims;
4532     Threads::threads_do(&reset_claims);
4533     // On overflow, update the global token to non-zero, to
4534     // avoid the special "never claimed" initial thread value.
4535     _thread_claim_token = 1;
4536   }
4537 }
4538 
4539 #ifdef ASSERT
4540 void assert_thread_claimed(const char* kind, Thread* t, uintx expected) {
4541   const uintx token = t->threads_do_token();
4542   assert(token == expected,
4543          "%s " PTR_FORMAT " has incorrect value " UINTX_FORMAT " != "
4544          UINTX_FORMAT, kind, p2i(t), token, expected);
4545 }
4546 
4547 void Threads::assert_all_threads_claimed() {
4548   ALL_JAVA_THREADS(p) {
4549     assert_thread_claimed("Thread", p, _thread_claim_token);
4550   }
4551   assert_thread_claimed("VMThread", VMThread::vm_thread(), _thread_claim_token);
4552 }
4553 #endif // ASSERT
4554 
4555 class ParallelOopsDoThreadClosure : public ThreadClosure {
4556 private:
4557   OopClosure* _f;
4558   CodeBlobClosure* _cf;
4559 public:
4560   ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {}
4561   void do_thread(Thread* t) {
4562     t->oops_do(_f, _cf);
4563   }
4564 };
4565 
4566 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4567   ParallelOopsDoThreadClosure tc(f, cf);
4568   possibly_parallel_threads_do(is_par, &tc);
4569 }
4570 
4571 void Threads::nmethods_do(CodeBlobClosure* cf) {
4572   ALL_JAVA_THREADS(p) {
4573     // This is used by the code cache sweeper to mark nmethods that are active
4574     // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4575     // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4576     if(!p->is_Code_cache_sweeper_thread()) {
4577       p->nmethods_do(cf);
4578     }
4579   }
4580 }
4581 
4582 void Threads::metadata_do(MetadataClosure* f) {
4583   ALL_JAVA_THREADS(p) {
4584     p->metadata_do(f);
4585   }
4586 }
4587 
4588 class ThreadHandlesClosure : public ThreadClosure {
4589   void (*_f)(Metadata*);
4590  public:
4591   ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4592   virtual void do_thread(Thread* thread) {
4593     thread->metadata_handles_do(_f);
4594   }
4595 };
4596 
4597 void Threads::metadata_handles_do(void f(Metadata*)) {
4598   // Only walk the Handles in Thread.
4599   ThreadHandlesClosure handles_closure(f);
4600   threads_do(&handles_closure);
4601 }
4602 
4603 // Get count Java threads that are waiting to enter the specified monitor.
4604 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
4605                                                          int count,
4606                                                          address monitor) {
4607   GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4608 
4609   int i = 0;
4610   DO_JAVA_THREADS(t_list, p) {
4611     if (!p->can_call_java()) continue;
4612 
4613     address pending = (address)p->current_pending_monitor();
4614     if (pending == monitor) {             // found a match
4615       if (i < count) result->append(p);   // save the first count matches
4616       i++;
4617     }
4618   }
4619 
4620   return result;
4621 }
4622 
4623 
4624 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
4625                                                       address owner) {
4626   // NULL owner means not locked so we can skip the search
4627   if (owner == NULL) return NULL;
4628 
4629   DO_JAVA_THREADS(t_list, p) {
4630     // first, see if owner is the address of a Java thread
4631     if (owner == (address)p) return p;
4632   }
4633 
4634   // Cannot assert on lack of success here since this function may be
4635   // used by code that is trying to report useful problem information
4636   // like deadlock detection.
4637   if (UseHeavyMonitors) return NULL;
4638 
4639   // If we didn't find a matching Java thread and we didn't force use of
4640   // heavyweight monitors, then the owner is the stack address of the
4641   // Lock Word in the owning Java thread's stack.
4642   //
4643   JavaThread* the_owner = NULL;
4644   DO_JAVA_THREADS(t_list, q) {
4645     if (q->is_lock_owned(owner)) {
4646       the_owner = q;
4647       break;
4648     }
4649   }
4650 
4651   // cannot assert on lack of success here; see above comment
4652   return the_owner;
4653 }
4654 
4655 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4656 void Threads::print_on(outputStream* st, bool print_stacks,
4657                        bool internal_format, bool print_concurrent_locks,
4658                        bool print_extended_info) {
4659   char buf[32];
4660   st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4661 
4662   st->print_cr("Full thread dump %s (%s %s):",
4663                VM_Version::vm_name(),
4664                VM_Version::vm_release(),
4665                VM_Version::vm_info_string());
4666   st->cr();
4667 
4668 #if INCLUDE_SERVICES
4669   // Dump concurrent locks
4670   ConcurrentLocksDump concurrent_locks;
4671   if (print_concurrent_locks) {
4672     concurrent_locks.dump_at_safepoint();
4673   }
4674 #endif // INCLUDE_SERVICES
4675 
4676   ThreadsSMRSupport::print_info_on(st);
4677   st->cr();
4678 
4679   ALL_JAVA_THREADS(p) {
4680     ResourceMark rm;
4681     p->print_on(st, print_extended_info);
4682     if (print_stacks) {
4683       if (internal_format) {
4684         p->trace_stack();
4685       } else {
4686         p->print_stack_on(st);
4687       }
4688     }
4689     st->cr();
4690 #if INCLUDE_SERVICES
4691     if (print_concurrent_locks) {
4692       concurrent_locks.print_locks_on(p, st);
4693     }
4694 #endif // INCLUDE_SERVICES
4695   }
4696 
4697   VMThread::vm_thread()->print_on(st);
4698   st->cr();
4699   Universe::heap()->print_gc_threads_on(st);
4700   WatcherThread* wt = WatcherThread::watcher_thread();
4701   if (wt != NULL) {
4702     wt->print_on(st);
4703     st->cr();
4704   }
4705 
4706   st->flush();
4707 }
4708 
4709 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4710                              int buflen, bool* found_current) {
4711   if (this_thread != NULL) {
4712     bool is_current = (current == this_thread);
4713     *found_current = *found_current || is_current;
4714     st->print("%s", is_current ? "=>" : "  ");
4715 
4716     st->print(PTR_FORMAT, p2i(this_thread));
4717     st->print(" ");
4718     this_thread->print_on_error(st, buf, buflen);
4719     st->cr();
4720   }
4721 }
4722 
4723 class PrintOnErrorClosure : public ThreadClosure {
4724   outputStream* _st;
4725   Thread* _current;
4726   char* _buf;
4727   int _buflen;
4728   bool* _found_current;
4729  public:
4730   PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4731                       int buflen, bool* found_current) :
4732    _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4733 
4734   virtual void do_thread(Thread* thread) {
4735     Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4736   }
4737 };
4738 
4739 // Threads::print_on_error() is called by fatal error handler. It's possible
4740 // that VM is not at safepoint and/or current thread is inside signal handler.
4741 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4742 // memory (even in resource area), it might deadlock the error handler.
4743 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4744                              int buflen) {
4745   ThreadsSMRSupport::print_info_on(st);
4746   st->cr();
4747 
4748   bool found_current = false;
4749   st->print_cr("Java Threads: ( => current thread )");
4750   ALL_JAVA_THREADS(thread) {
4751     print_on_error(thread, st, current, buf, buflen, &found_current);
4752   }
4753   st->cr();
4754 
4755   st->print_cr("Other Threads:");
4756   print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4757   print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4758 
4759   PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4760   Universe::heap()->gc_threads_do(&print_closure);
4761 
4762   if (!found_current) {
4763     st->cr();
4764     st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4765     current->print_on_error(st, buf, buflen);
4766     st->cr();
4767   }
4768   st->cr();
4769 
4770   st->print_cr("Threads with active compile tasks:");
4771   print_threads_compiling(st, buf, buflen);
4772 }
4773 
4774 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen, bool short_form) {
4775   ALL_JAVA_THREADS(thread) {
4776     if (thread->is_Compiler_thread()) {
4777       CompilerThread* ct = (CompilerThread*) thread;
4778 
4779       // Keep task in local variable for NULL check.
4780       // ct->_task might be set to NULL by concurring compiler thread
4781       // because it completed the compilation. The task is never freed,
4782       // though, just returned to a free list.
4783       CompileTask* task = ct->task();
4784       if (task != NULL) {
4785         thread->print_name_on_error(st, buf, buflen);
4786         st->print("  ");
4787         task->print(st, NULL, short_form, true);
4788       }
4789     }
4790   }
4791 }
4792 
4793 
4794 // Internal SpinLock and Mutex
4795 // Based on ParkEvent
4796 
4797 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4798 //
4799 // We employ SpinLocks _only for low-contention, fixed-length
4800 // short-duration critical sections where we're concerned
4801 // about native mutex_t or HotSpot Mutex:: latency.
4802 // The mux construct provides a spin-then-block mutual exclusion
4803 // mechanism.
4804 //
4805 // Testing has shown that contention on the ListLock guarding gFreeList
4806 // is common.  If we implement ListLock as a simple SpinLock it's common
4807 // for the JVM to devolve to yielding with little progress.  This is true
4808 // despite the fact that the critical sections protected by ListLock are
4809 // extremely short.
4810 //
4811 // TODO-FIXME: ListLock should be of type SpinLock.
4812 // We should make this a 1st-class type, integrated into the lock
4813 // hierarchy as leaf-locks.  Critically, the SpinLock structure
4814 // should have sufficient padding to avoid false-sharing and excessive
4815 // cache-coherency traffic.
4816 
4817 
4818 typedef volatile int SpinLockT;
4819 
4820 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4821   if (Atomic::cmpxchg (1, adr, 0) == 0) {
4822     return;   // normal fast-path return
4823   }
4824 
4825   // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4826   int ctr = 0;
4827   int Yields = 0;
4828   for (;;) {
4829     while (*adr != 0) {
4830       ++ctr;
4831       if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4832         if (Yields > 5) {
4833           os::naked_short_sleep(1);
4834         } else {
4835           os::naked_yield();
4836           ++Yields;
4837         }
4838       } else {
4839         SpinPause();
4840       }
4841     }
4842     if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4843   }
4844 }
4845 
4846 void Thread::SpinRelease(volatile int * adr) {
4847   assert(*adr != 0, "invariant");
4848   OrderAccess::fence();      // guarantee at least release consistency.
4849   // Roach-motel semantics.
4850   // It's safe if subsequent LDs and STs float "up" into the critical section,
4851   // but prior LDs and STs within the critical section can't be allowed
4852   // to reorder or float past the ST that releases the lock.
4853   // Loads and stores in the critical section - which appear in program
4854   // order before the store that releases the lock - must also appear
4855   // before the store that releases the lock in memory visibility order.
4856   // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4857   // the ST of 0 into the lock-word which releases the lock, so fence
4858   // more than covers this on all platforms.
4859   *adr = 0;
4860 }
4861 
4862 // muxAcquire and muxRelease:
4863 //
4864 // *  muxAcquire and muxRelease support a single-word lock-word construct.
4865 //    The LSB of the word is set IFF the lock is held.
4866 //    The remainder of the word points to the head of a singly-linked list
4867 //    of threads blocked on the lock.
4868 //
4869 // *  The current implementation of muxAcquire-muxRelease uses its own
4870 //    dedicated Thread._MuxEvent instance.  If we're interested in
4871 //    minimizing the peak number of extant ParkEvent instances then
4872 //    we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4873 //    as certain invariants were satisfied.  Specifically, care would need
4874 //    to be taken with regards to consuming unpark() "permits".
4875 //    A safe rule of thumb is that a thread would never call muxAcquire()
4876 //    if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4877 //    park().  Otherwise the _ParkEvent park() operation in muxAcquire() could
4878 //    consume an unpark() permit intended for monitorenter, for instance.
4879 //    One way around this would be to widen the restricted-range semaphore
4880 //    implemented in park().  Another alternative would be to provide
4881 //    multiple instances of the PlatformEvent() for each thread.  One
4882 //    instance would be dedicated to muxAcquire-muxRelease, for instance.
4883 //
4884 // *  Usage:
4885 //    -- Only as leaf locks
4886 //    -- for short-term locking only as muxAcquire does not perform
4887 //       thread state transitions.
4888 //
4889 // Alternatives:
4890 // *  We could implement muxAcquire and muxRelease with MCS or CLH locks
4891 //    but with parking or spin-then-park instead of pure spinning.
4892 // *  Use Taura-Oyama-Yonenzawa locks.
4893 // *  It's possible to construct a 1-0 lock if we encode the lockword as
4894 //    (List,LockByte).  Acquire will CAS the full lockword while Release
4895 //    will STB 0 into the LockByte.  The 1-0 scheme admits stranding, so
4896 //    acquiring threads use timers (ParkTimed) to detect and recover from
4897 //    the stranding window.  Thread/Node structures must be aligned on 256-byte
4898 //    boundaries by using placement-new.
4899 // *  Augment MCS with advisory back-link fields maintained with CAS().
4900 //    Pictorially:  LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4901 //    The validity of the backlinks must be ratified before we trust the value.
4902 //    If the backlinks are invalid the exiting thread must back-track through the
4903 //    the forward links, which are always trustworthy.
4904 // *  Add a successor indication.  The LockWord is currently encoded as
4905 //    (List, LOCKBIT:1).  We could also add a SUCCBIT or an explicit _succ variable
4906 //    to provide the usual futile-wakeup optimization.
4907 //    See RTStt for details.
4908 //
4909 
4910 
4911 const intptr_t LOCKBIT = 1;
4912 
4913 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4914   intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4915   if (w == 0) return;
4916   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4917     return;
4918   }
4919 
4920   ParkEvent * const Self = Thread::current()->_MuxEvent;
4921   assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4922   for (;;) {
4923     int its = (os::is_MP() ? 100 : 0) + 1;
4924 
4925     // Optional spin phase: spin-then-park strategy
4926     while (--its >= 0) {
4927       w = *Lock;
4928       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4929         return;
4930       }
4931     }
4932 
4933     Self->reset();
4934     Self->OnList = intptr_t(Lock);
4935     // The following fence() isn't _strictly necessary as the subsequent
4936     // CAS() both serializes execution and ratifies the fetched *Lock value.
4937     OrderAccess::fence();
4938     for (;;) {
4939       w = *Lock;
4940       if ((w & LOCKBIT) == 0) {
4941         if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4942           Self->OnList = 0;   // hygiene - allows stronger asserts
4943           return;
4944         }
4945         continue;      // Interference -- *Lock changed -- Just retry
4946       }
4947       assert(w & LOCKBIT, "invariant");
4948       Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4949       if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4950     }
4951 
4952     while (Self->OnList != 0) {
4953       Self->park();
4954     }
4955   }
4956 }
4957 
4958 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4959   intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4960   if (w == 0) return;
4961   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4962     return;
4963   }
4964 
4965   ParkEvent * ReleaseAfter = NULL;
4966   if (ev == NULL) {
4967     ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4968   }
4969   assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4970   for (;;) {
4971     guarantee(ev->OnList == 0, "invariant");
4972     int its = (os::is_MP() ? 100 : 0) + 1;
4973 
4974     // Optional spin phase: spin-then-park strategy
4975     while (--its >= 0) {
4976       w = *Lock;
4977       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4978         if (ReleaseAfter != NULL) {
4979           ParkEvent::Release(ReleaseAfter);
4980         }
4981         return;
4982       }
4983     }
4984 
4985     ev->reset();
4986     ev->OnList = intptr_t(Lock);
4987     // The following fence() isn't _strictly necessary as the subsequent
4988     // CAS() both serializes execution and ratifies the fetched *Lock value.
4989     OrderAccess::fence();
4990     for (;;) {
4991       w = *Lock;
4992       if ((w & LOCKBIT) == 0) {
4993         if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4994           ev->OnList = 0;
4995           // We call ::Release while holding the outer lock, thus
4996           // artificially lengthening the critical section.
4997           // Consider deferring the ::Release() until the subsequent unlock(),
4998           // after we've dropped the outer lock.
4999           if (ReleaseAfter != NULL) {
5000             ParkEvent::Release(ReleaseAfter);
5001           }
5002           return;
5003         }
5004         continue;      // Interference -- *Lock changed -- Just retry
5005       }
5006       assert(w & LOCKBIT, "invariant");
5007       ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
5008       if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
5009     }
5010 
5011     while (ev->OnList != 0) {
5012       ev->park();
5013     }
5014   }
5015 }
5016 
5017 // Release() must extract a successor from the list and then wake that thread.
5018 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
5019 // similar to that used by ParkEvent::Allocate() and ::Release().  DMR-based
5020 // Release() would :
5021 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
5022 // (B) Extract a successor from the private list "in-hand"
5023 // (C) attempt to CAS() the residual back into *Lock over null.
5024 //     If there were any newly arrived threads and the CAS() would fail.
5025 //     In that case Release() would detach the RATs, re-merge the list in-hand
5026 //     with the RATs and repeat as needed.  Alternately, Release() might
5027 //     detach and extract a successor, but then pass the residual list to the wakee.
5028 //     The wakee would be responsible for reattaching and remerging before it
5029 //     competed for the lock.
5030 //
5031 // Both "pop" and DMR are immune from ABA corruption -- there can be
5032 // multiple concurrent pushers, but only one popper or detacher.
5033 // This implementation pops from the head of the list.  This is unfair,
5034 // but tends to provide excellent throughput as hot threads remain hot.
5035 // (We wake recently run threads first).
5036 //
5037 // All paths through muxRelease() will execute a CAS.
5038 // Release consistency -- We depend on the CAS in muxRelease() to provide full
5039 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
5040 // executed within the critical section are complete and globally visible before the
5041 // store (CAS) to the lock-word that releases the lock becomes globally visible.
5042 void Thread::muxRelease(volatile intptr_t * Lock)  {
5043   for (;;) {
5044     const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT);
5045     assert(w & LOCKBIT, "invariant");
5046     if (w == LOCKBIT) return;
5047     ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
5048     assert(List != NULL, "invariant");
5049     assert(List->OnList == intptr_t(Lock), "invariant");
5050     ParkEvent * const nxt = List->ListNext;
5051     guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
5052 
5053     // The following CAS() releases the lock and pops the head element.
5054     // The CAS() also ratifies the previously fetched lock-word value.
5055     if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) {
5056       continue;
5057     }
5058     List->OnList = 0;
5059     OrderAccess::fence();
5060     List->unpark();
5061     return;
5062   }
5063 }
5064 
5065 
5066 void Threads::verify() {
5067   ALL_JAVA_THREADS(p) {
5068     p->verify();
5069   }
5070   VMThread* thread = VMThread::vm_thread();
5071   if (thread != NULL) thread->verify();
5072 }