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