1 /*
   2  * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "jvm.h"
  27 #include "classfile/classLoader.hpp"
  28 #include "classfile/javaClasses.hpp"
  29 #include "classfile/moduleEntry.hpp"
  30 #include "classfile/systemDictionary.hpp"
  31 #include "classfile/vmSymbols.hpp"
  32 #include "code/codeCache.hpp"
  33 #include "code/scopeDesc.hpp"
  34 #include "compiler/compileBroker.hpp"
  35 #include "compiler/compileTask.hpp"
  36 #include "gc/shared/barrierSet.hpp"
  37 #include "gc/shared/gcId.hpp"
  38 #include "gc/shared/gcLocker.inline.hpp"
  39 #include "gc/shared/workgroup.hpp"
  40 #include "interpreter/interpreter.hpp"
  41 #include "interpreter/linkResolver.hpp"
  42 #include "interpreter/oopMapCache.hpp"
  43 #include "jfr/jfrEvents.hpp"
  44 #include "jfr/support/jfrThreadId.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 "prims/privilegedStack.hpp"
  65 #include "runtime/arguments.hpp"
  66 #include "runtime/atomic.hpp"
  67 #include "runtime/biasedLocking.hpp"
  68 #include "runtime/fieldDescriptor.inline.hpp"
  69 #include "runtime/flags/jvmFlagConstraintList.hpp"
  70 #include "runtime/flags/jvmFlagRangeList.hpp"
  71 #include "runtime/flags/jvmFlagWriteableList.hpp"
  72 #include "runtime/deoptimization.hpp"
  73 #include "runtime/frame.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/vm_operations.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/jvmciCompiler.hpp"
 122 #include "jvmci/jvmciRuntime.hpp"
 123 #include "logging/logHandle.hpp"
 124 #endif
 125 #ifdef COMPILER1
 126 #include "c1/c1_Compiler.hpp"
 127 #endif
 128 #ifdef COMPILER2
 129 #include "opto/c2compiler.hpp"
 130 #include "opto/idealGraphPrinter.hpp"
 131 #endif
 132 #if INCLUDE_RTM_OPT
 133 #include "runtime/rtmLocking.hpp"
 134 #endif
 135 #if INCLUDE_JFR
 136 #include "jfr/jfr.hpp"
 137 #endif
 138 
 139 // Initialization after module runtime initialization
 140 void universe_post_module_init();  // must happen after call_initPhase2
 141 
 142 #ifdef DTRACE_ENABLED
 143 
 144 // Only bother with this argument setup if dtrace is available
 145 
 146   #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
 147   #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
 148 
 149   #define DTRACE_THREAD_PROBE(probe, javathread)                           \
 150     {                                                                      \
 151       ResourceMark rm(this);                                               \
 152       int len = 0;                                                         \
 153       const char* name = (javathread)->get_thread_name();                  \
 154       len = strlen(name);                                                  \
 155       HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */               \
 156         (char *) name, len,                                                \
 157         java_lang_Thread::thread_id((javathread)->threadObj()),            \
 158         (uintptr_t) (javathread)->osthread()->thread_id(),                 \
 159         java_lang_Thread::is_daemon((javathread)->threadObj()));           \
 160     }
 161 
 162 #else //  ndef DTRACE_ENABLED
 163 
 164   #define DTRACE_THREAD_PROBE(probe, javathread)
 165 
 166 #endif // ndef DTRACE_ENABLED
 167 
 168 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 169 // Current thread is maintained as a thread-local variable
 170 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
 171 #endif
 172 
 173 // ======= Thread ========
 174 // Support for forcing alignment of thread objects for biased locking
 175 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
 176   if (UseBiasedLocking) {
 177     const int alignment = markOopDesc::biased_lock_alignment;
 178     size_t aligned_size = size + (alignment - sizeof(intptr_t));
 179     void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
 180                                           : AllocateHeap(aligned_size, flags, CURRENT_PC,
 181                                                          AllocFailStrategy::RETURN_NULL);
 182     void* aligned_addr     = align_up(real_malloc_addr, alignment);
 183     assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
 184            ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
 185            "JavaThread alignment code overflowed allocated storage");
 186     if (aligned_addr != real_malloc_addr) {
 187       log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
 188                               p2i(real_malloc_addr),
 189                               p2i(aligned_addr));
 190     }
 191     ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
 192     return aligned_addr;
 193   } else {
 194     return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
 195                        : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
 196   }
 197 }
 198 
 199 void Thread::operator delete(void* p) {
 200   if (UseBiasedLocking) {
 201     FreeHeap(((Thread*) p)->_real_malloc_address);
 202   } else {
 203     FreeHeap(p);
 204   }
 205 }
 206 
 207 void JavaThread::smr_delete() {
 208   if (_on_thread_list) {
 209     ThreadsSMRSupport::smr_delete(this);
 210   } else {
 211     delete this;
 212   }
 213 }
 214 
 215 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
 216 // JavaThread
 217 
 218 
 219 Thread::Thread() {
 220   // stack and get_thread
 221   set_stack_base(NULL);
 222   set_stack_size(0);
 223   set_self_raw_id(0);
 224   set_lgrp_id(-1);
 225   DEBUG_ONLY(clear_suspendible_thread();)
 226 
 227   // allocated data structures
 228   set_osthread(NULL);
 229   set_resource_area(new (mtThread)ResourceArea());
 230   DEBUG_ONLY(_current_resource_mark = NULL;)
 231   set_handle_area(new (mtThread) HandleArea(NULL));
 232   set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
 233   set_active_handles(NULL);
 234   set_free_handle_block(NULL);
 235   set_last_handle_mark(NULL);
 236 
 237   // This initial value ==> never claimed.
 238   _oops_do_parity = 0;
 239   _threads_hazard_ptr = NULL;
 240   _threads_list_ptr = NULL;
 241   _nested_threads_hazard_ptr_cnt = 0;
 242   _rcu_counter = 0;
 243 
 244   // the handle mark links itself to last_handle_mark
 245   new HandleMark(this);
 246 
 247   // plain initialization
 248   debug_only(_owned_locks = NULL;)
 249   debug_only(_allow_allocation_count = 0;)
 250   NOT_PRODUCT(_allow_safepoint_count = 0;)
 251   NOT_PRODUCT(_skip_gcalot = false;)
 252   _jvmti_env_iteration_count = 0;
 253   set_allocated_bytes(0);
 254   _vm_operation_started_count = 0;
 255   _vm_operation_completed_count = 0;
 256   _current_pending_monitor = NULL;
 257   _current_pending_monitor_is_from_java = true;
 258   _current_waiting_monitor = NULL;
 259   _num_nested_signal = 0;
 260   omFreeList = NULL;
 261   omFreeCount = 0;
 262   omFreeProvision = 32;
 263   omInUseList = NULL;
 264   omInUseCount = 0;
 265 
 266 #ifdef ASSERT
 267   _visited_for_critical_count = false;
 268 #endif
 269 
 270   _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
 271                          Monitor::_safepoint_check_sometimes);
 272   _suspend_flags = 0;
 273 
 274   // thread-specific hashCode stream generator state - Marsaglia shift-xor form
 275   _hashStateX = os::random();
 276   _hashStateY = 842502087;
 277   _hashStateZ = 0x8767;    // (int)(3579807591LL & 0xffff) ;
 278   _hashStateW = 273326509;
 279 
 280   _OnTrap   = 0;
 281   _Stalled  = 0;
 282   _TypeTag  = 0x2BAD;
 283 
 284   // Many of the following fields are effectively final - immutable
 285   // Note that nascent threads can't use the Native Monitor-Mutex
 286   // construct until the _MutexEvent is initialized ...
 287   // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
 288   // we might instead use a stack of ParkEvents that we could provision on-demand.
 289   // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
 290   // and ::Release()
 291   _ParkEvent   = ParkEvent::Allocate(this);
 292   _SleepEvent  = ParkEvent::Allocate(this);
 293   _MutexEvent  = ParkEvent::Allocate(this);
 294   _MuxEvent    = ParkEvent::Allocate(this);
 295 
 296 #ifdef CHECK_UNHANDLED_OOPS
 297   if (CheckUnhandledOops) {
 298     _unhandled_oops = new UnhandledOops(this);
 299   }
 300 #endif // CHECK_UNHANDLED_OOPS
 301 #ifdef ASSERT
 302   if (UseBiasedLocking) {
 303     assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
 304     assert(this == _real_malloc_address ||
 305            this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment),
 306            "bug in forced alignment of thread objects");
 307   }
 308 #endif // ASSERT
 309 
 310   // Notify the barrier set that a thread is being created. Note that some
 311   // threads are created before a barrier set is available. The call to
 312   // BarrierSet::on_thread_create() for these threads is therefore deferred
 313   // to BarrierSet::set_barrier_set().
 314   BarrierSet* const barrier_set = BarrierSet::barrier_set();
 315   if (barrier_set != NULL) {
 316     barrier_set->on_thread_create(this);
 317   } else {
 318     DEBUG_ONLY(Threads::inc_threads_before_barrier_set();)
 319   }
 320 }
 321 
 322 void Thread::initialize_thread_current() {
 323 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 324   assert(_thr_current == NULL, "Thread::current already initialized");
 325   _thr_current = this;
 326 #endif
 327   assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
 328   ThreadLocalStorage::set_thread(this);
 329   assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
 330 }
 331 
 332 void Thread::clear_thread_current() {
 333   assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
 334 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 335   _thr_current = NULL;
 336 #endif
 337   ThreadLocalStorage::set_thread(NULL);
 338 }
 339 
 340 void Thread::record_stack_base_and_size() {
 341   set_stack_base(os::current_stack_base());
 342   set_stack_size(os::current_stack_size());
 343   // CR 7190089: on Solaris, primordial thread's stack is adjusted
 344   // in initialize_thread(). Without the adjustment, stack size is
 345   // incorrect if stack is set to unlimited (ulimit -s unlimited).
 346   // So far, only Solaris has real implementation of initialize_thread().
 347   //
 348   // set up any platform-specific state.
 349   os::initialize_thread(this);
 350 
 351   // Set stack limits after thread is initialized.
 352   if (is_Java_thread()) {
 353     ((JavaThread*) this)->set_stack_overflow_limit();
 354     ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
 355   }
 356 #if INCLUDE_NMT
 357   // record thread's native stack, stack grows downward
 358   MemTracker::record_thread_stack(stack_end(), stack_size());
 359 #endif // INCLUDE_NMT
 360   log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
 361     PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
 362     os::current_thread_id(), p2i(stack_base() - stack_size()),
 363     p2i(stack_base()), stack_size()/1024);
 364 }
 365 
 366 
 367 Thread::~Thread() {
 368   JFR_ONLY(Jfr::on_thread_destruct(this);)
 369 
 370   // Notify the barrier set that a thread is being destroyed. Note that a barrier
 371   // set might not be available if we encountered errors during bootstrapping.
 372   BarrierSet* const barrier_set = BarrierSet::barrier_set();
 373   if (barrier_set != NULL) {
 374     barrier_set->on_thread_destroy(this);
 375   }
 376 
 377 
 378   // stack_base can be NULL if the thread is never started or exited before
 379   // record_stack_base_and_size called. Although, we would like to ensure
 380   // that all started threads do call record_stack_base_and_size(), there is
 381   // not proper way to enforce that.
 382 #if INCLUDE_NMT
 383   if (_stack_base != NULL) {
 384     MemTracker::release_thread_stack(stack_end(), stack_size());
 385 #ifdef ASSERT
 386     set_stack_base(NULL);
 387 #endif
 388   }
 389 #endif // INCLUDE_NMT
 390 
 391   // deallocate data structures
 392   delete resource_area();
 393   // since the handle marks are using the handle area, we have to deallocated the root
 394   // handle mark before deallocating the thread's handle area,
 395   assert(last_handle_mark() != NULL, "check we have an element");
 396   delete last_handle_mark();
 397   assert(last_handle_mark() == NULL, "check we have reached the end");
 398 
 399   // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
 400   // We NULL out the fields for good hygiene.
 401   ParkEvent::Release(_ParkEvent); _ParkEvent   = NULL;
 402   ParkEvent::Release(_SleepEvent); _SleepEvent  = NULL;
 403   ParkEvent::Release(_MutexEvent); _MutexEvent  = NULL;
 404   ParkEvent::Release(_MuxEvent); _MuxEvent    = NULL;
 405 
 406   delete handle_area();
 407   delete metadata_handles();
 408 
 409   // SR_handler uses this as a termination indicator -
 410   // needs to happen before os::free_thread()
 411   delete _SR_lock;
 412   _SR_lock = NULL;
 413 
 414   // osthread() can be NULL, if creation of thread failed.
 415   if (osthread() != NULL) os::free_thread(osthread());
 416 
 417   // clear Thread::current if thread is deleting itself.
 418   // Needed to ensure JNI correctly detects non-attached threads.
 419   if (this == Thread::current()) {
 420     clear_thread_current();
 421   }
 422 
 423   CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
 424 }
 425 
 426 // NOTE: dummy function for assertion purpose.
 427 void Thread::run() {
 428   ShouldNotReachHere();
 429 }
 430 
 431 #ifdef ASSERT
 432 // A JavaThread is considered "dangling" if it is not the current
 433 // thread, has been added the Threads list, the system is not at a
 434 // safepoint and the Thread is not "protected".
 435 //
 436 void Thread::check_for_dangling_thread_pointer(Thread *thread) {
 437   assert(!thread->is_Java_thread() || Thread::current() == thread ||
 438          !((JavaThread *) thread)->on_thread_list() ||
 439          SafepointSynchronize::is_at_safepoint() ||
 440          ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread),
 441          "possibility of dangling Thread pointer");
 442 }
 443 #endif
 444 
 445 ThreadPriority Thread::get_priority(const Thread* const thread) {
 446   ThreadPriority priority;
 447   // Can return an error!
 448   (void)os::get_priority(thread, priority);
 449   assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
 450   return priority;
 451 }
 452 
 453 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
 454   debug_only(check_for_dangling_thread_pointer(thread);)
 455   // Can return an error!
 456   (void)os::set_priority(thread, priority);
 457 }
 458 
 459 
 460 void Thread::start(Thread* thread) {
 461   // Start is different from resume in that its safety is guaranteed by context or
 462   // being called from a Java method synchronized on the Thread object.
 463   if (!DisableStartThread) {
 464     if (thread->is_Java_thread()) {
 465       // Initialize the thread state to RUNNABLE before starting this thread.
 466       // Can not set it after the thread started because we do not know the
 467       // exact thread state at that time. It could be in MONITOR_WAIT or
 468       // in SLEEPING or some other state.
 469       java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
 470                                           java_lang_Thread::RUNNABLE);
 471     }
 472     os::start_thread(thread);
 473   }
 474 }
 475 
 476 // Enqueue a VM_Operation to do the job for us - sometime later
 477 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
 478   VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
 479   VMThread::execute(vm_stop);
 480 }
 481 
 482 
 483 // Check if an external suspend request has completed (or has been
 484 // cancelled). Returns true if the thread is externally suspended and
 485 // false otherwise.
 486 //
 487 // The bits parameter returns information about the code path through
 488 // the routine. Useful for debugging:
 489 //
 490 // set in is_ext_suspend_completed():
 491 // 0x00000001 - routine was entered
 492 // 0x00000010 - routine return false at end
 493 // 0x00000100 - thread exited (return false)
 494 // 0x00000200 - suspend request cancelled (return false)
 495 // 0x00000400 - thread suspended (return true)
 496 // 0x00001000 - thread is in a suspend equivalent state (return true)
 497 // 0x00002000 - thread is native and walkable (return true)
 498 // 0x00004000 - thread is native_trans and walkable (needed retry)
 499 //
 500 // set in wait_for_ext_suspend_completion():
 501 // 0x00010000 - routine was entered
 502 // 0x00020000 - suspend request cancelled before loop (return false)
 503 // 0x00040000 - thread suspended before loop (return true)
 504 // 0x00080000 - suspend request cancelled in loop (return false)
 505 // 0x00100000 - thread suspended in loop (return true)
 506 // 0x00200000 - suspend not completed during retry loop (return false)
 507 
 508 // Helper class for tracing suspend wait debug bits.
 509 //
 510 // 0x00000100 indicates that the target thread exited before it could
 511 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
 512 // 0x00080000 each indicate a cancelled suspend request so they don't
 513 // count as wait failures either.
 514 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
 515 
 516 class TraceSuspendDebugBits : public StackObj {
 517  private:
 518   JavaThread * jt;
 519   bool         is_wait;
 520   bool         called_by_wait;  // meaningful when !is_wait
 521   uint32_t *   bits;
 522 
 523  public:
 524   TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
 525                         uint32_t *_bits) {
 526     jt             = _jt;
 527     is_wait        = _is_wait;
 528     called_by_wait = _called_by_wait;
 529     bits           = _bits;
 530   }
 531 
 532   ~TraceSuspendDebugBits() {
 533     if (!is_wait) {
 534 #if 1
 535       // By default, don't trace bits for is_ext_suspend_completed() calls.
 536       // That trace is very chatty.
 537       return;
 538 #else
 539       if (!called_by_wait) {
 540         // If tracing for is_ext_suspend_completed() is enabled, then only
 541         // trace calls to it from wait_for_ext_suspend_completion()
 542         return;
 543       }
 544 #endif
 545     }
 546 
 547     if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
 548       if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
 549         MutexLocker ml(Threads_lock);  // needed for get_thread_name()
 550         ResourceMark rm;
 551 
 552         tty->print_cr(
 553                       "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
 554                       jt->get_thread_name(), *bits);
 555 
 556         guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
 557       }
 558     }
 559   }
 560 };
 561 #undef DEBUG_FALSE_BITS
 562 
 563 
 564 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
 565                                           uint32_t *bits) {
 566   TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
 567 
 568   bool did_trans_retry = false;  // only do thread_in_native_trans retry once
 569   bool do_trans_retry;           // flag to force the retry
 570 
 571   *bits |= 0x00000001;
 572 
 573   do {
 574     do_trans_retry = false;
 575 
 576     if (is_exiting()) {
 577       // Thread is in the process of exiting. This is always checked
 578       // first to reduce the risk of dereferencing a freed JavaThread.
 579       *bits |= 0x00000100;
 580       return false;
 581     }
 582 
 583     if (!is_external_suspend()) {
 584       // Suspend request is cancelled. This is always checked before
 585       // is_ext_suspended() to reduce the risk of a rogue resume
 586       // confusing the thread that made the suspend request.
 587       *bits |= 0x00000200;
 588       return false;
 589     }
 590 
 591     if (is_ext_suspended()) {
 592       // thread is suspended
 593       *bits |= 0x00000400;
 594       return true;
 595     }
 596 
 597     // Now that we no longer do hard suspends of threads running
 598     // native code, the target thread can be changing thread state
 599     // while we are in this routine:
 600     //
 601     //   _thread_in_native -> _thread_in_native_trans -> _thread_blocked
 602     //
 603     // We save a copy of the thread state as observed at this moment
 604     // and make our decision about suspend completeness based on the
 605     // copy. This closes the race where the thread state is seen as
 606     // _thread_in_native_trans in the if-thread_blocked check, but is
 607     // seen as _thread_blocked in if-thread_in_native_trans check.
 608     JavaThreadState save_state = thread_state();
 609 
 610     if (save_state == _thread_blocked && is_suspend_equivalent()) {
 611       // If the thread's state is _thread_blocked and this blocking
 612       // condition is known to be equivalent to a suspend, then we can
 613       // consider the thread to be externally suspended. This means that
 614       // the code that sets _thread_blocked has been modified to do
 615       // self-suspension if the blocking condition releases. We also
 616       // used to check for CONDVAR_WAIT here, but that is now covered by
 617       // the _thread_blocked with self-suspension check.
 618       //
 619       // Return true since we wouldn't be here unless there was still an
 620       // external suspend request.
 621       *bits |= 0x00001000;
 622       return true;
 623     } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
 624       // Threads running native code will self-suspend on native==>VM/Java
 625       // transitions. If its stack is walkable (should always be the case
 626       // unless this function is called before the actual java_suspend()
 627       // call), then the wait is done.
 628       *bits |= 0x00002000;
 629       return true;
 630     } else if (!called_by_wait && !did_trans_retry &&
 631                save_state == _thread_in_native_trans &&
 632                frame_anchor()->walkable()) {
 633       // The thread is transitioning from thread_in_native to another
 634       // thread state. check_safepoint_and_suspend_for_native_trans()
 635       // will force the thread to self-suspend. If it hasn't gotten
 636       // there yet we may have caught the thread in-between the native
 637       // code check above and the self-suspend. Lucky us. If we were
 638       // called by wait_for_ext_suspend_completion(), then it
 639       // will be doing the retries so we don't have to.
 640       //
 641       // Since we use the saved thread state in the if-statement above,
 642       // there is a chance that the thread has already transitioned to
 643       // _thread_blocked by the time we get here. In that case, we will
 644       // make a single unnecessary pass through the logic below. This
 645       // doesn't hurt anything since we still do the trans retry.
 646 
 647       *bits |= 0x00004000;
 648 
 649       // Once the thread leaves thread_in_native_trans for another
 650       // thread state, we break out of this retry loop. We shouldn't
 651       // need this flag to prevent us from getting back here, but
 652       // sometimes paranoia is good.
 653       did_trans_retry = true;
 654 
 655       // We wait for the thread to transition to a more usable state.
 656       for (int i = 1; i <= SuspendRetryCount; i++) {
 657         // We used to do an "os::yield_all(i)" call here with the intention
 658         // that yielding would increase on each retry. However, the parameter
 659         // is ignored on Linux which means the yield didn't scale up. Waiting
 660         // on the SR_lock below provides a much more predictable scale up for
 661         // the delay. It also provides a simple/direct point to check for any
 662         // safepoint requests from the VMThread
 663 
 664         // temporarily drops SR_lock while doing wait with safepoint check
 665         // (if we're a JavaThread - the WatcherThread can also call this)
 666         // and increase delay with each retry
 667         SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 668 
 669         // check the actual thread state instead of what we saved above
 670         if (thread_state() != _thread_in_native_trans) {
 671           // the thread has transitioned to another thread state so
 672           // try all the checks (except this one) one more time.
 673           do_trans_retry = true;
 674           break;
 675         }
 676       } // end retry loop
 677 
 678 
 679     }
 680   } while (do_trans_retry);
 681 
 682   *bits |= 0x00000010;
 683   return false;
 684 }
 685 
 686 // Wait for an external suspend request to complete (or be cancelled).
 687 // Returns true if the thread is externally suspended and false otherwise.
 688 //
 689 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
 690                                                  uint32_t *bits) {
 691   TraceSuspendDebugBits tsdb(this, true /* is_wait */,
 692                              false /* !called_by_wait */, bits);
 693 
 694   // local flag copies to minimize SR_lock hold time
 695   bool is_suspended;
 696   bool pending;
 697   uint32_t reset_bits;
 698 
 699   // set a marker so is_ext_suspend_completed() knows we are the caller
 700   *bits |= 0x00010000;
 701 
 702   // We use reset_bits to reinitialize the bits value at the top of
 703   // each retry loop. This allows the caller to make use of any
 704   // unused bits for their own marking purposes.
 705   reset_bits = *bits;
 706 
 707   {
 708     MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
 709     is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 710                                             delay, bits);
 711     pending = is_external_suspend();
 712   }
 713   // must release SR_lock to allow suspension to complete
 714 
 715   if (!pending) {
 716     // A cancelled suspend request is the only false return from
 717     // is_ext_suspend_completed() that keeps us from entering the
 718     // retry loop.
 719     *bits |= 0x00020000;
 720     return false;
 721   }
 722 
 723   if (is_suspended) {
 724     *bits |= 0x00040000;
 725     return true;
 726   }
 727 
 728   for (int i = 1; i <= retries; i++) {
 729     *bits = reset_bits;  // reinit to only track last retry
 730 
 731     // We used to do an "os::yield_all(i)" call here with the intention
 732     // that yielding would increase on each retry. However, the parameter
 733     // is ignored on Linux which means the yield didn't scale up. Waiting
 734     // on the SR_lock below provides a much more predictable scale up for
 735     // the delay. It also provides a simple/direct point to check for any
 736     // safepoint requests from the VMThread
 737 
 738     {
 739       MutexLocker ml(SR_lock());
 740       // wait with safepoint check (if we're a JavaThread - the WatcherThread
 741       // can also call this)  and increase delay with each retry
 742       SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 743 
 744       is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 745                                               delay, bits);
 746 
 747       // It is possible for the external suspend request to be cancelled
 748       // (by a resume) before the actual suspend operation is completed.
 749       // Refresh our local copy to see if we still need to wait.
 750       pending = is_external_suspend();
 751     }
 752 
 753     if (!pending) {
 754       // A cancelled suspend request is the only false return from
 755       // is_ext_suspend_completed() that keeps us from staying in the
 756       // retry loop.
 757       *bits |= 0x00080000;
 758       return false;
 759     }
 760 
 761     if (is_suspended) {
 762       *bits |= 0x00100000;
 763       return true;
 764     }
 765   } // end retry loop
 766 
 767   // thread did not suspend after all our retries
 768   *bits |= 0x00200000;
 769   return false;
 770 }
 771 
 772 // Called from API entry points which perform stack walking. If the
 773 // associated JavaThread is the current thread, then wait_for_suspend
 774 // is not used. Otherwise, it determines if we should wait for the
 775 // "other" thread to complete external suspension. (NOTE: in future
 776 // releases the suspension mechanism should be reimplemented so this
 777 // is not necessary.)
 778 //
 779 bool
 780 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) {
 781   if (this != JavaThread::current()) {
 782     // "other" threads require special handling.
 783     if (wait_for_suspend) {
 784       // We are allowed to wait for the external suspend to complete
 785       // so give the other thread a chance to get suspended.
 786       if (!wait_for_ext_suspend_completion(SuspendRetryCount,
 787                                            SuspendRetryDelay, bits)) {
 788         // Didn't make it so let the caller know.
 789         return false;
 790       }
 791     }
 792     // We aren't allowed to wait for the external suspend to complete
 793     // so if the other thread isn't externally suspended we need to
 794     // let the caller know.
 795     else if (!is_ext_suspend_completed_with_lock(bits)) {
 796       return false;
 797     }
 798   }
 799 
 800   return true;
 801 }
 802 
 803 #ifndef PRODUCT
 804 void JavaThread::record_jump(address target, address instr, const char* file,
 805                              int line) {
 806 
 807   // This should not need to be atomic as the only way for simultaneous
 808   // updates is via interrupts. Even then this should be rare or non-existent
 809   // and we don't care that much anyway.
 810 
 811   int index = _jmp_ring_index;
 812   _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
 813   _jmp_ring[index]._target = (intptr_t) target;
 814   _jmp_ring[index]._instruction = (intptr_t) instr;
 815   _jmp_ring[index]._file = file;
 816   _jmp_ring[index]._line = line;
 817 }
 818 #endif // PRODUCT
 819 
 820 void Thread::interrupt(Thread* thread) {
 821   debug_only(check_for_dangling_thread_pointer(thread);)
 822   os::interrupt(thread);
 823 }
 824 
 825 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
 826   debug_only(check_for_dangling_thread_pointer(thread);)
 827   // Note:  If clear_interrupted==false, this simply fetches and
 828   // returns the value of the field osthread()->interrupted().
 829   return os::is_interrupted(thread, clear_interrupted);
 830 }
 831 
 832 
 833 // GC Support
 834 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
 835   int thread_parity = _oops_do_parity;
 836   if (thread_parity != strong_roots_parity) {
 837     jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
 838     if (res == thread_parity) {
 839       return true;
 840     } else {
 841       guarantee(res == strong_roots_parity, "Or else what?");
 842       return false;
 843     }
 844   }
 845   return false;
 846 }
 847 
 848 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
 849   active_handles()->oops_do(f);
 850   // Do oop for ThreadShadow
 851   f->do_oop((oop*)&_pending_exception);
 852   handle_area()->oops_do(f);
 853 
 854   // We scan thread local monitor lists here, and the remaining global
 855   // monitors in ObjectSynchronizer::oops_do().
 856   ObjectSynchronizer::thread_local_used_oops_do(this, f);
 857 }
 858 
 859 void Thread::metadata_handles_do(void f(Metadata*)) {
 860   // Only walk the Handles in Thread.
 861   if (metadata_handles() != NULL) {
 862     for (int i = 0; i< metadata_handles()->length(); i++) {
 863       f(metadata_handles()->at(i));
 864     }
 865   }
 866 }
 867 
 868 void Thread::print_on(outputStream* st, bool print_extended_info) const {
 869   // get_priority assumes osthread initialized
 870   if (osthread() != NULL) {
 871     int os_prio;
 872     if (os::get_native_priority(this, &os_prio) == OS_OK) {
 873       st->print("os_prio=%d ", os_prio);
 874     }
 875 
 876     st->print("cpu=%.2fms ",
 877               os::thread_cpu_time(const_cast<Thread*>(this), true) / 1000000.0
 878               );
 879     st->print("elapsed=%.2fs ",
 880               _statistical_info.getElapsedTime() / 1000.0
 881               );
 882     if (is_Java_thread() && (PrintExtendedThreadInfo || print_extended_info)) {
 883       size_t allocated_bytes = (size_t) const_cast<Thread*>(this)->cooked_allocated_bytes();
 884       st->print("allocated=" SIZE_FORMAT "%s ",
 885                 byte_size_in_proper_unit(allocated_bytes),
 886                 proper_unit_for_byte_size(allocated_bytes)
 887                 );
 888       st->print("defined_classes=" INT64_FORMAT " ", _statistical_info.getDefineClassCount());
 889     }
 890 
 891     st->print("tid=" INTPTR_FORMAT " ", p2i(this));
 892     osthread()->print_on(st);
 893   }
 894   ThreadsSMRSupport::print_info_on(this, st);
 895   st->print(" ");
 896   debug_only(if (WizardMode) print_owned_locks_on(st);)
 897 }
 898 
 899 // Thread::print_on_error() is called by fatal error handler. Don't use
 900 // any lock or allocate memory.
 901 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
 902   assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
 903 
 904   if (is_VM_thread())                 { st->print("VMThread"); }
 905   else if (is_GC_task_thread())       { st->print("GCTaskThread"); }
 906   else if (is_Watcher_thread())       { st->print("WatcherThread"); }
 907   else if (is_ConcurrentGC_thread())  { st->print("ConcurrentGCThread"); }
 908   else                                { st->print("Thread"); }
 909 
 910   if (is_Named_thread()) {
 911     st->print(" \"%s\"", name());
 912   }
 913 
 914   st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
 915             p2i(stack_end()), p2i(stack_base()));
 916 
 917   if (osthread()) {
 918     st->print(" [id=%d]", osthread()->thread_id());
 919   }
 920 
 921   ThreadsSMRSupport::print_info_on(this, st);
 922 }
 923 
 924 void Thread::print_value_on(outputStream* st) const {
 925   if (is_Named_thread()) {
 926     st->print(" \"%s\" ", name());
 927   }
 928   st->print(INTPTR_FORMAT, p2i(this));   // print address
 929 }
 930 
 931 #ifdef ASSERT
 932 void Thread::print_owned_locks_on(outputStream* st) const {
 933   Monitor *cur = _owned_locks;
 934   if (cur == NULL) {
 935     st->print(" (no locks) ");
 936   } else {
 937     st->print_cr(" Locks owned:");
 938     while (cur) {
 939       cur->print_on(st);
 940       cur = cur->next();
 941     }
 942   }
 943 }
 944 
 945 static int ref_use_count  = 0;
 946 
 947 bool Thread::owns_locks_but_compiled_lock() const {
 948   for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 949     if (cur != Compile_lock) return true;
 950   }
 951   return false;
 952 }
 953 
 954 
 955 #endif
 956 
 957 #ifndef PRODUCT
 958 
 959 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially
 960 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that
 961 // no locks which allow_vm_block's are held
 962 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
 963   // Check if current thread is allowed to block at a safepoint
 964   if (!(_allow_safepoint_count == 0)) {
 965     fatal("Possible safepoint reached by thread that does not allow it");
 966   }
 967   if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
 968     fatal("LEAF method calling lock?");
 969   }
 970 
 971 #ifdef ASSERT
 972   if (potential_vm_operation && is_Java_thread()
 973       && !Universe::is_bootstrapping()) {
 974     // Make sure we do not hold any locks that the VM thread also uses.
 975     // This could potentially lead to deadlocks
 976     for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 977       // Threads_lock is special, since the safepoint synchronization will not start before this is
 978       // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
 979       // since it is used to transfer control between JavaThreads and the VMThread
 980       // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
 981       if ((cur->allow_vm_block() &&
 982            cur != Threads_lock &&
 983            cur != Compile_lock &&               // Temporary: should not be necessary when we get separate compilation
 984            cur != VMOperationRequest_lock &&
 985            cur != VMOperationQueue_lock) ||
 986            cur->rank() == Mutex::special) {
 987         fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
 988       }
 989     }
 990   }
 991 
 992   if (GCALotAtAllSafepoints) {
 993     // We could enter a safepoint here and thus have a gc
 994     InterfaceSupport::check_gc_alot();
 995   }
 996 #endif
 997 }
 998 #endif
 999 
1000 bool Thread::is_in_stack(address adr) const {
1001   assert(Thread::current() == this, "is_in_stack can only be called from current thread");
1002   address end = os::current_stack_pointer();
1003   // Allow non Java threads to call this without stack_base
1004   if (_stack_base == NULL) return true;
1005   if (stack_base() >= adr && adr >= end) return true;
1006 
1007   return false;
1008 }
1009 
1010 bool Thread::is_in_usable_stack(address adr) const {
1011   size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
1012   size_t usable_stack_size = _stack_size - stack_guard_size;
1013 
1014   return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
1015 }
1016 
1017 
1018 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
1019 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
1020 // used for compilation in the future. If that change is made, the need for these methods
1021 // should be revisited, and they should be removed if possible.
1022 
1023 bool Thread::is_lock_owned(address adr) const {
1024   return on_local_stack(adr);
1025 }
1026 
1027 bool Thread::set_as_starting_thread() {
1028   // NOTE: this must be called inside the main thread.
1029   return os::create_main_thread((JavaThread*)this);
1030 }
1031 
1032 static void initialize_class(Symbol* class_name, TRAPS) {
1033   Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
1034   InstanceKlass::cast(klass)->initialize(CHECK);
1035 }
1036 
1037 
1038 // Creates the initial ThreadGroup
1039 static Handle create_initial_thread_group(TRAPS) {
1040   Handle system_instance = JavaCalls::construct_new_instance(
1041                             SystemDictionary::ThreadGroup_klass(),
1042                             vmSymbols::void_method_signature(),
1043                             CHECK_NH);
1044   Universe::set_system_thread_group(system_instance());
1045 
1046   Handle string = java_lang_String::create_from_str("main", CHECK_NH);
1047   Handle main_instance = JavaCalls::construct_new_instance(
1048                             SystemDictionary::ThreadGroup_klass(),
1049                             vmSymbols::threadgroup_string_void_signature(),
1050                             system_instance,
1051                             string,
1052                             CHECK_NH);
1053   return main_instance;
1054 }
1055 
1056 // Creates the initial Thread
1057 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
1058                                  TRAPS) {
1059   InstanceKlass* ik = SystemDictionary::Thread_klass();
1060   assert(ik->is_initialized(), "must be");
1061   instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
1062 
1063   // Cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1064   // constructor calls Thread.current(), which must be set here for the
1065   // initial thread.
1066   java_lang_Thread::set_thread(thread_oop(), thread);
1067   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1068   thread->set_threadObj(thread_oop());
1069 
1070   Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1071 
1072   JavaValue result(T_VOID);
1073   JavaCalls::call_special(&result, thread_oop,
1074                           ik,
1075                           vmSymbols::object_initializer_name(),
1076                           vmSymbols::threadgroup_string_void_signature(),
1077                           thread_group,
1078                           string,
1079                           CHECK_NULL);
1080   return thread_oop();
1081 }
1082 
1083 char java_runtime_name[128] = "";
1084 char java_runtime_version[128] = "";
1085 
1086 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1087 static const char* get_java_runtime_name(TRAPS) {
1088   Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1089                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1090   fieldDescriptor fd;
1091   bool found = k != NULL &&
1092                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1093                                                         vmSymbols::string_signature(), &fd);
1094   if (found) {
1095     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1096     if (name_oop == NULL) {
1097       return NULL;
1098     }
1099     const char* name = java_lang_String::as_utf8_string(name_oop,
1100                                                         java_runtime_name,
1101                                                         sizeof(java_runtime_name));
1102     return name;
1103   } else {
1104     return NULL;
1105   }
1106 }
1107 
1108 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1109 static const char* get_java_runtime_version(TRAPS) {
1110   Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1111                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1112   fieldDescriptor fd;
1113   bool found = k != NULL &&
1114                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1115                                                         vmSymbols::string_signature(), &fd);
1116   if (found) {
1117     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1118     if (name_oop == NULL) {
1119       return NULL;
1120     }
1121     const char* name = java_lang_String::as_utf8_string(name_oop,
1122                                                         java_runtime_version,
1123                                                         sizeof(java_runtime_version));
1124     return name;
1125   } else {
1126     return NULL;
1127   }
1128 }
1129 
1130 // General purpose hook into Java code, run once when the VM is initialized.
1131 // The Java library method itself may be changed independently from the VM.
1132 static void call_postVMInitHook(TRAPS) {
1133   Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1134   if (klass != NULL) {
1135     JavaValue result(T_VOID);
1136     JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1137                            vmSymbols::void_method_signature(),
1138                            CHECK);
1139   }
1140 }
1141 
1142 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1143                                     bool daemon, TRAPS) {
1144   assert(thread_group.not_null(), "thread group should be specified");
1145   assert(threadObj() == NULL, "should only create Java thread object once");
1146 
1147   InstanceKlass* ik = SystemDictionary::Thread_klass();
1148   assert(ik->is_initialized(), "must be");
1149   instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1150 
1151   // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon.
1152   // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1153   // constructor calls Thread.current(), which must be set here.
1154   java_lang_Thread::set_thread(thread_oop(), this);
1155   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1156   set_threadObj(thread_oop());
1157 
1158   JavaValue result(T_VOID);
1159   if (thread_name != NULL) {
1160     Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1161     // Thread gets assigned specified name and null target
1162     JavaCalls::call_special(&result,
1163                             thread_oop,
1164                             ik,
1165                             vmSymbols::object_initializer_name(),
1166                             vmSymbols::threadgroup_string_void_signature(),
1167                             thread_group,
1168                             name,
1169                             THREAD);
1170   } else {
1171     // Thread gets assigned name "Thread-nnn" and null target
1172     // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1173     JavaCalls::call_special(&result,
1174                             thread_oop,
1175                             ik,
1176                             vmSymbols::object_initializer_name(),
1177                             vmSymbols::threadgroup_runnable_void_signature(),
1178                             thread_group,
1179                             Handle(),
1180                             THREAD);
1181   }
1182 
1183 
1184   if (daemon) {
1185     java_lang_Thread::set_daemon(thread_oop());
1186   }
1187 
1188   if (HAS_PENDING_EXCEPTION) {
1189     return;
1190   }
1191 
1192   Klass* group =  SystemDictionary::ThreadGroup_klass();
1193   Handle threadObj(THREAD, this->threadObj());
1194 
1195   JavaCalls::call_special(&result,
1196                           thread_group,
1197                           group,
1198                           vmSymbols::add_method_name(),
1199                           vmSymbols::thread_void_signature(),
1200                           threadObj,          // Arg 1
1201                           THREAD);
1202 }
1203 
1204 // List of all NonJavaThreads and safe iteration over that list.
1205 
1206 class NonJavaThread::List {
1207 public:
1208   NonJavaThread* volatile _head;
1209   SingleWriterSynchronizer _protect;
1210 
1211   List() : _head(NULL), _protect() {}
1212 };
1213 
1214 NonJavaThread::List NonJavaThread::_the_list;
1215 
1216 NonJavaThread::Iterator::Iterator() :
1217   _protect_enter(_the_list._protect.enter()),
1218   _current(OrderAccess::load_acquire(&_the_list._head))
1219 {}
1220 
1221 NonJavaThread::Iterator::~Iterator() {
1222   _the_list._protect.exit(_protect_enter);
1223 }
1224 
1225 void NonJavaThread::Iterator::step() {
1226   assert(!end(), "precondition");
1227   _current = OrderAccess::load_acquire(&_current->_next);
1228 }
1229 
1230 NonJavaThread::NonJavaThread() : Thread(), _next(NULL) {
1231   // Add this thread to _the_list.
1232   MutexLockerEx lock(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1233   _next = _the_list._head;
1234   OrderAccess::release_store(&_the_list._head, this);
1235 }
1236 
1237 NonJavaThread::~NonJavaThread() {
1238   // Remove this thread from _the_list.
1239   MutexLockerEx lock(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1240   NonJavaThread* volatile* p = &_the_list._head;
1241   for (NonJavaThread* t = *p; t != NULL; p = &t->_next, t = *p) {
1242     if (t == this) {
1243       *p = this->_next;
1244       // Wait for any in-progress iterators.
1245       _the_list._protect.synchronize();
1246       break;
1247     }
1248   }
1249 }
1250 
1251 // NamedThread --  non-JavaThread subclasses with multiple
1252 // uniquely named instances should derive from this.
1253 NamedThread::NamedThread() :
1254   NonJavaThread(),
1255   _name(NULL),
1256   _processed_thread(NULL),
1257   _gc_id(GCId::undefined())
1258 {}
1259 
1260 NamedThread::~NamedThread() {
1261   if (_name != NULL) {
1262     FREE_C_HEAP_ARRAY(char, _name);
1263     _name = NULL;
1264   }
1265 }
1266 
1267 void NamedThread::set_name(const char* format, ...) {
1268   guarantee(_name == NULL, "Only get to set name once.");
1269   _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1270   guarantee(_name != NULL, "alloc failure");
1271   va_list ap;
1272   va_start(ap, format);
1273   jio_vsnprintf(_name, max_name_len, format, ap);
1274   va_end(ap);
1275 }
1276 
1277 void NamedThread::initialize_named_thread() {
1278   set_native_thread_name(name());
1279 }
1280 
1281 void NamedThread::print_on(outputStream* st) const {
1282   st->print("\"%s\" ", name());
1283   Thread::print_on(st);
1284   st->cr();
1285 }
1286 
1287 
1288 // ======= WatcherThread ========
1289 
1290 // The watcher thread exists to simulate timer interrupts.  It should
1291 // be replaced by an abstraction over whatever native support for
1292 // timer interrupts exists on the platform.
1293 
1294 WatcherThread* WatcherThread::_watcher_thread   = NULL;
1295 bool WatcherThread::_startable = false;
1296 volatile bool  WatcherThread::_should_terminate = false;
1297 
1298 WatcherThread::WatcherThread() : NonJavaThread() {
1299   assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1300   if (os::create_thread(this, os::watcher_thread)) {
1301     _watcher_thread = this;
1302 
1303     // Set the watcher thread to the highest OS priority which should not be
1304     // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1305     // is created. The only normal thread using this priority is the reference
1306     // handler thread, which runs for very short intervals only.
1307     // If the VMThread's priority is not lower than the WatcherThread profiling
1308     // will be inaccurate.
1309     os::set_priority(this, MaxPriority);
1310     if (!DisableStartThread) {
1311       os::start_thread(this);
1312     }
1313   }
1314 }
1315 
1316 int WatcherThread::sleep() const {
1317   MutexLocker ml(PeriodicTask_lock);
1318 
1319   if (_should_terminate) {
1320     // check for termination before we do any housekeeping or wait
1321     return 0;  // we did not sleep.
1322   }
1323 
1324   // remaining will be zero if there are no tasks,
1325   // causing the WatcherThread to sleep until a task is
1326   // enrolled
1327   int remaining = PeriodicTask::time_to_wait();
1328   int time_slept = 0;
1329 
1330   // we expect this to timeout - we only ever get unparked when
1331   // we should terminate or when a new task has been enrolled
1332   OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1333 
1334   jlong time_before_loop = os::javaTimeNanos();
1335 
1336   while (true) {
1337     bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1338                                             remaining);
1339     jlong now = os::javaTimeNanos();
1340 
1341     if (remaining == 0) {
1342       // if we didn't have any tasks we could have waited for a long time
1343       // consider the time_slept zero and reset time_before_loop
1344       time_slept = 0;
1345       time_before_loop = now;
1346     } else {
1347       // need to recalculate since we might have new tasks in _tasks
1348       time_slept = (int) ((now - time_before_loop) / 1000000);
1349     }
1350 
1351     // Change to task list or spurious wakeup of some kind
1352     if (timedout || _should_terminate) {
1353       break;
1354     }
1355 
1356     remaining = PeriodicTask::time_to_wait();
1357     if (remaining == 0) {
1358       // Last task was just disenrolled so loop around and wait until
1359       // another task gets enrolled
1360       continue;
1361     }
1362 
1363     remaining -= time_slept;
1364     if (remaining <= 0) {
1365       break;
1366     }
1367   }
1368 
1369   return time_slept;
1370 }
1371 
1372 void WatcherThread::run() {
1373   assert(this == watcher_thread(), "just checking");
1374 
1375   this->record_stack_base_and_size();
1376   this->set_native_thread_name(this->name());
1377   this->set_active_handles(JNIHandleBlock::allocate_block());
1378   while (true) {
1379     assert(watcher_thread() == Thread::current(), "thread consistency check");
1380     assert(watcher_thread() == this, "thread consistency check");
1381 
1382     // Calculate how long it'll be until the next PeriodicTask work
1383     // should be done, and sleep that amount of time.
1384     int time_waited = sleep();
1385 
1386     if (VMError::is_error_reported()) {
1387       // A fatal error has happened, the error handler(VMError::report_and_die)
1388       // should abort JVM after creating an error log file. However in some
1389       // rare cases, the error handler itself might deadlock. Here periodically
1390       // check for error reporting timeouts, and if it happens, just proceed to
1391       // abort the VM.
1392 
1393       // This code is in WatcherThread because WatcherThread wakes up
1394       // periodically so the fatal error handler doesn't need to do anything;
1395       // also because the WatcherThread is less likely to crash than other
1396       // threads.
1397 
1398       for (;;) {
1399         // Note: we use naked sleep in this loop because we want to avoid using
1400         // any kind of VM infrastructure which may be broken at this point.
1401         if (VMError::check_timeout()) {
1402           // We hit error reporting timeout. Error reporting was interrupted and
1403           // will be wrapping things up now (closing files etc). Give it some more
1404           // time, then quit the VM.
1405           os::naked_short_sleep(200);
1406           // Print a message to stderr.
1407           fdStream err(defaultStream::output_fd());
1408           err.print_raw_cr("# [ timer expired, abort... ]");
1409           // skip atexit/vm_exit/vm_abort hooks
1410           os::die();
1411         }
1412 
1413         // Wait a second, then recheck for timeout.
1414         os::naked_short_sleep(999);
1415       }
1416     }
1417 
1418     if (_should_terminate) {
1419       // check for termination before posting the next tick
1420       break;
1421     }
1422 
1423     PeriodicTask::real_time_tick(time_waited);
1424   }
1425 
1426   // Signal that it is terminated
1427   {
1428     MutexLocker mu(Terminator_lock);
1429     _watcher_thread = NULL;
1430     Terminator_lock->notify();
1431   }
1432 }
1433 
1434 void WatcherThread::start() {
1435   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1436 
1437   if (watcher_thread() == NULL && _startable) {
1438     _should_terminate = false;
1439     // Create the single instance of WatcherThread
1440     new WatcherThread();
1441   }
1442 }
1443 
1444 void WatcherThread::make_startable() {
1445   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1446   _startable = true;
1447 }
1448 
1449 void WatcherThread::stop() {
1450   {
1451     // Follow normal safepoint aware lock enter protocol since the
1452     // WatcherThread is stopped by another JavaThread.
1453     MutexLocker ml(PeriodicTask_lock);
1454     _should_terminate = true;
1455 
1456     WatcherThread* watcher = watcher_thread();
1457     if (watcher != NULL) {
1458       // unpark the WatcherThread so it can see that it should terminate
1459       watcher->unpark();
1460     }
1461   }
1462 
1463   MutexLocker mu(Terminator_lock);
1464 
1465   while (watcher_thread() != NULL) {
1466     // This wait should make safepoint checks, wait without a timeout,
1467     // and wait as a suspend-equivalent condition.
1468     Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1469                           Mutex::_as_suspend_equivalent_flag);
1470   }
1471 }
1472 
1473 void WatcherThread::unpark() {
1474   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1475   PeriodicTask_lock->notify();
1476 }
1477 
1478 void WatcherThread::print_on(outputStream* st) const {
1479   st->print("\"%s\" ", name());
1480   Thread::print_on(st);
1481   st->cr();
1482 }
1483 
1484 // ======= JavaThread ========
1485 
1486 #if INCLUDE_JVMCI
1487 
1488 jlong* JavaThread::_jvmci_old_thread_counters;
1489 
1490 bool jvmci_counters_include(JavaThread* thread) {
1491   return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1492 }
1493 
1494 void JavaThread::collect_counters(typeArrayOop array) {
1495   if (JVMCICounterSize > 0) {
1496     JavaThreadIteratorWithHandle jtiwh;
1497     for (int i = 0; i < array->length(); i++) {
1498       array->long_at_put(i, _jvmci_old_thread_counters[i]);
1499     }
1500     for (; JavaThread *tp = jtiwh.next(); ) {
1501       if (jvmci_counters_include(tp)) {
1502         for (int i = 0; i < array->length(); i++) {
1503           array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1504         }
1505       }
1506     }
1507   }
1508 }
1509 
1510 #endif // INCLUDE_JVMCI
1511 
1512 // A JavaThread is a normal Java thread
1513 
1514 void JavaThread::initialize() {
1515   // Initialize fields
1516 
1517   set_saved_exception_pc(NULL);
1518   set_threadObj(NULL);
1519   _anchor.clear();
1520   set_entry_point(NULL);
1521   set_jni_functions(jni_functions());
1522   set_callee_target(NULL);
1523   set_vm_result(NULL);
1524   set_vm_result_2(NULL);
1525   set_vframe_array_head(NULL);
1526   set_vframe_array_last(NULL);
1527   set_deferred_locals(NULL);
1528   set_deopt_mark(NULL);
1529   set_deopt_compiled_method(NULL);
1530   clear_must_deopt_id();
1531   set_monitor_chunks(NULL);
1532   set_next(NULL);
1533   _on_thread_list = false;
1534   set_thread_state(_thread_new);
1535   _terminated = _not_terminated;
1536   _privileged_stack_top = NULL;
1537   _array_for_gc = NULL;
1538   _suspend_equivalent = false;
1539   _in_deopt_handler = 0;
1540   _doing_unsafe_access = false;
1541   _stack_guard_state = stack_guard_unused;
1542 #if INCLUDE_JVMCI
1543   _pending_monitorenter = false;
1544   _pending_deoptimization = -1;
1545   _pending_failed_speculation = 0;
1546   _pending_transfer_to_interpreter = false;
1547   _adjusting_comp_level = false;
1548   _in_retryable_allocation = false;
1549   _jvmci._alternate_call_target = NULL;
1550   assert(_jvmci._implicit_exception_pc == NULL, "must be");
1551   if (JVMCICounterSize > 0) {
1552     _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1553     memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1554   } else {
1555     _jvmci_counters = NULL;
1556   }
1557 #endif // INCLUDE_JVMCI
1558   _reserved_stack_activation = NULL;  // stack base not known yet
1559   (void)const_cast<oop&>(_exception_oop = oop(NULL));
1560   _exception_pc  = 0;
1561   _exception_handler_pc = 0;
1562   _is_method_handle_return = 0;
1563   _jvmti_thread_state= NULL;
1564   _should_post_on_exceptions_flag = JNI_FALSE;
1565   _interp_only_mode    = 0;
1566   _special_runtime_exit_condition = _no_async_condition;
1567   _pending_async_exception = NULL;
1568   _thread_stat = NULL;
1569   _thread_stat = new ThreadStatistics();
1570   _blocked_on_compilation = false;
1571   _jni_active_critical = 0;
1572   _pending_jni_exception_check_fn = NULL;
1573   _do_not_unlock_if_synchronized = false;
1574   _cached_monitor_info = NULL;
1575   _parker = Parker::Allocate(this);
1576 
1577 #ifndef PRODUCT
1578   _jmp_ring_index = 0;
1579   for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1580     record_jump(NULL, NULL, NULL, 0);
1581   }
1582 #endif // PRODUCT
1583 
1584   // Setup safepoint state info for this thread
1585   ThreadSafepointState::create(this);
1586 
1587   debug_only(_java_call_counter = 0);
1588 
1589   // JVMTI PopFrame support
1590   _popframe_condition = popframe_inactive;
1591   _popframe_preserved_args = NULL;
1592   _popframe_preserved_args_size = 0;
1593   _frames_to_pop_failed_realloc = 0;
1594 
1595   if (SafepointMechanism::uses_thread_local_poll()) {
1596     SafepointMechanism::initialize_header(this);
1597   }
1598 
1599   pd_initialize();
1600 }
1601 
1602 JavaThread::JavaThread(bool is_attaching_via_jni) :
1603                        Thread() {
1604   initialize();
1605   if (is_attaching_via_jni) {
1606     _jni_attach_state = _attaching_via_jni;
1607   } else {
1608     _jni_attach_state = _not_attaching_via_jni;
1609   }
1610   assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1611 }
1612 
1613 bool JavaThread::reguard_stack(address cur_sp) {
1614   if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1615       && _stack_guard_state != stack_guard_reserved_disabled) {
1616     return true; // Stack already guarded or guard pages not needed.
1617   }
1618 
1619   if (register_stack_overflow()) {
1620     // For those architectures which have separate register and
1621     // memory stacks, we must check the register stack to see if
1622     // it has overflowed.
1623     return false;
1624   }
1625 
1626   // Java code never executes within the yellow zone: the latter is only
1627   // there to provoke an exception during stack banging.  If java code
1628   // is executing there, either StackShadowPages should be larger, or
1629   // some exception code in c1, c2 or the interpreter isn't unwinding
1630   // when it should.
1631   guarantee(cur_sp > stack_reserved_zone_base(),
1632             "not enough space to reguard - increase StackShadowPages");
1633   if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1634     enable_stack_yellow_reserved_zone();
1635     if (reserved_stack_activation() != stack_base()) {
1636       set_reserved_stack_activation(stack_base());
1637     }
1638   } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1639     set_reserved_stack_activation(stack_base());
1640     enable_stack_reserved_zone();
1641   }
1642   return true;
1643 }
1644 
1645 bool JavaThread::reguard_stack(void) {
1646   return reguard_stack(os::current_stack_pointer());
1647 }
1648 
1649 
1650 void JavaThread::block_if_vm_exited() {
1651   if (_terminated == _vm_exited) {
1652     // _vm_exited is set at safepoint, and Threads_lock is never released
1653     // we will block here forever
1654     Threads_lock->lock_without_safepoint_check();
1655     ShouldNotReachHere();
1656   }
1657 }
1658 
1659 
1660 // Remove this ifdef when C1 is ported to the compiler interface.
1661 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1662 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1663 
1664 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1665                        Thread() {
1666   initialize();
1667   _jni_attach_state = _not_attaching_via_jni;
1668   set_entry_point(entry_point);
1669   // Create the native thread itself.
1670   // %note runtime_23
1671   os::ThreadType thr_type = os::java_thread;
1672   thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1673                                                      os::java_thread;
1674   os::create_thread(this, thr_type, stack_sz);
1675   // The _osthread may be NULL here because we ran out of memory (too many threads active).
1676   // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1677   // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1678   // the exception consists of creating the exception object & initializing it, initialization
1679   // will leave the VM via a JavaCall and then all locks must be unlocked).
1680   //
1681   // The thread is still suspended when we reach here. Thread must be explicit started
1682   // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1683   // by calling Threads:add. The reason why this is not done here, is because the thread
1684   // object must be fully initialized (take a look at JVM_Start)
1685 }
1686 
1687 JavaThread::~JavaThread() {
1688 
1689   // JSR166 -- return the parker to the free list
1690   Parker::Release(_parker);
1691   _parker = NULL;
1692 
1693   // Free any remaining  previous UnrollBlock
1694   vframeArray* old_array = vframe_array_last();
1695 
1696   if (old_array != NULL) {
1697     Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1698     old_array->set_unroll_block(NULL);
1699     delete old_info;
1700     delete old_array;
1701   }
1702 
1703   GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1704   if (deferred != NULL) {
1705     // This can only happen if thread is destroyed before deoptimization occurs.
1706     assert(deferred->length() != 0, "empty array!");
1707     do {
1708       jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1709       deferred->remove_at(0);
1710       // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1711       delete dlv;
1712     } while (deferred->length() != 0);
1713     delete deferred;
1714   }
1715 
1716   // All Java related clean up happens in exit
1717   ThreadSafepointState::destroy(this);
1718   if (_thread_stat != NULL) delete _thread_stat;
1719 
1720 #if INCLUDE_JVMCI
1721   if (JVMCICounterSize > 0) {
1722     if (jvmci_counters_include(this)) {
1723       for (int i = 0; i < JVMCICounterSize; i++) {
1724         _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1725       }
1726     }
1727     FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1728   }
1729 #endif // INCLUDE_JVMCI
1730 }
1731 
1732 
1733 // The first routine called by a new Java thread
1734 void JavaThread::run() {
1735   // initialize thread-local alloc buffer related fields
1736   this->initialize_tlab();
1737 
1738   // used to test validity of stack trace backs
1739   this->record_base_of_stack_pointer();
1740 
1741   // Record real stack base and size.
1742   this->record_stack_base_and_size();
1743 
1744   this->create_stack_guard_pages();
1745 
1746   this->cache_global_variables();
1747 
1748   // Thread is now sufficient initialized to be handled by the safepoint code as being
1749   // in the VM. Change thread state from _thread_new to _thread_in_vm
1750   ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1751 
1752   assert(JavaThread::current() == this, "sanity check");
1753   assert(!Thread::current()->owns_locks(), "sanity check");
1754 
1755   DTRACE_THREAD_PROBE(start, this);
1756 
1757   // This operation might block. We call that after all safepoint checks for a new thread has
1758   // been completed.
1759   this->set_active_handles(JNIHandleBlock::allocate_block());
1760 
1761   if (JvmtiExport::should_post_thread_life()) {
1762     JvmtiExport::post_thread_start(this);
1763   }
1764 
1765   EventThreadStart event;
1766   if (event.should_commit()) {
1767     event.set_thread(JFR_THREAD_ID(this));
1768     event.commit();
1769   }
1770 
1771   // We call another function to do the rest so we are sure that the stack addresses used
1772   // from there will be lower than the stack base just computed
1773   thread_main_inner();
1774 
1775   // Note, thread is no longer valid at this point!
1776 }
1777 
1778 
1779 void JavaThread::thread_main_inner() {
1780   assert(JavaThread::current() == this, "sanity check");
1781   assert(this->threadObj() != NULL, "just checking");
1782 
1783   // Execute thread entry point unless this thread has a pending exception
1784   // or has been stopped before starting.
1785   // Note: Due to JVM_StopThread we can have pending exceptions already!
1786   if (!this->has_pending_exception() &&
1787       !java_lang_Thread::is_stillborn(this->threadObj())) {
1788     {
1789       ResourceMark rm(this);
1790       this->set_native_thread_name(this->get_thread_name());
1791     }
1792     HandleMark hm(this);
1793     this->entry_point()(this, this);
1794   }
1795 
1796   DTRACE_THREAD_PROBE(stop, this);
1797 
1798   this->exit(false);
1799   this->smr_delete();
1800 }
1801 
1802 
1803 static void ensure_join(JavaThread* thread) {
1804   // We do not need to grab the Threads_lock, since we are operating on ourself.
1805   Handle threadObj(thread, thread->threadObj());
1806   assert(threadObj.not_null(), "java thread object must exist");
1807   ObjectLocker lock(threadObj, thread);
1808   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1809   thread->clear_pending_exception();
1810   // Thread is exiting. So set thread_status field in  java.lang.Thread class to TERMINATED.
1811   java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1812   // Clear the native thread instance - this makes isAlive return false and allows the join()
1813   // to complete once we've done the notify_all below
1814   java_lang_Thread::set_thread(threadObj(), NULL);
1815   lock.notify_all(thread);
1816   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1817   thread->clear_pending_exception();
1818 }
1819 
1820 
1821 // For any new cleanup additions, please check to see if they need to be applied to
1822 // cleanup_failed_attach_current_thread as well.
1823 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1824   assert(this == JavaThread::current(), "thread consistency check");
1825 
1826   elapsedTimer _timer_exit_phase1;
1827   elapsedTimer _timer_exit_phase2;
1828   elapsedTimer _timer_exit_phase3;
1829   elapsedTimer _timer_exit_phase4;
1830 
1831   if (log_is_enabled(Debug, os, thread, timer)) {
1832     _timer_exit_phase1.start();
1833   }
1834 
1835   HandleMark hm(this);
1836   Handle uncaught_exception(this, this->pending_exception());
1837   this->clear_pending_exception();
1838   Handle threadObj(this, this->threadObj());
1839   assert(threadObj.not_null(), "Java thread object should be created");
1840 
1841   // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1842   {
1843     EXCEPTION_MARK;
1844 
1845     CLEAR_PENDING_EXCEPTION;
1846   }
1847   if (!destroy_vm) {
1848     if (uncaught_exception.not_null()) {
1849       EXCEPTION_MARK;
1850       // Call method Thread.dispatchUncaughtException().
1851       Klass* thread_klass = SystemDictionary::Thread_klass();
1852       JavaValue result(T_VOID);
1853       JavaCalls::call_virtual(&result,
1854                               threadObj, thread_klass,
1855                               vmSymbols::dispatchUncaughtException_name(),
1856                               vmSymbols::throwable_void_signature(),
1857                               uncaught_exception,
1858                               THREAD);
1859       if (HAS_PENDING_EXCEPTION) {
1860         ResourceMark rm(this);
1861         jio_fprintf(defaultStream::error_stream(),
1862                     "\nException: %s thrown from the UncaughtExceptionHandler"
1863                     " in thread \"%s\"\n",
1864                     pending_exception()->klass()->external_name(),
1865                     get_thread_name());
1866         CLEAR_PENDING_EXCEPTION;
1867       }
1868     }
1869 
1870     // Called before the java thread exit since we want to read info
1871     // from java_lang_Thread object
1872     EventThreadEnd event;
1873     if (event.should_commit()) {
1874       event.set_thread(JFR_THREAD_ID(this));
1875       event.commit();
1876     }
1877 
1878     // Call after last event on thread
1879     JFR_ONLY(Jfr::on_thread_exit(this);)
1880 
1881     // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1882     // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1883     // is deprecated anyhow.
1884     if (!is_Compiler_thread()) {
1885       int count = 3;
1886       while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1887         EXCEPTION_MARK;
1888         JavaValue result(T_VOID);
1889         Klass* thread_klass = SystemDictionary::Thread_klass();
1890         JavaCalls::call_virtual(&result,
1891                                 threadObj, thread_klass,
1892                                 vmSymbols::exit_method_name(),
1893                                 vmSymbols::void_method_signature(),
1894                                 THREAD);
1895         CLEAR_PENDING_EXCEPTION;
1896       }
1897     }
1898     // notify JVMTI
1899     if (JvmtiExport::should_post_thread_life()) {
1900       JvmtiExport::post_thread_end(this);
1901     }
1902 
1903     // We have notified the agents that we are exiting, before we go on,
1904     // we must check for a pending external suspend request and honor it
1905     // in order to not surprise the thread that made the suspend request.
1906     while (true) {
1907       {
1908         MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1909         if (!is_external_suspend()) {
1910           set_terminated(_thread_exiting);
1911           ThreadService::current_thread_exiting(this);
1912           break;
1913         }
1914         // Implied else:
1915         // Things get a little tricky here. We have a pending external
1916         // suspend request, but we are holding the SR_lock so we
1917         // can't just self-suspend. So we temporarily drop the lock
1918         // and then self-suspend.
1919       }
1920 
1921       ThreadBlockInVM tbivm(this);
1922       java_suspend_self();
1923 
1924       // We're done with this suspend request, but we have to loop around
1925       // and check again. Eventually we will get SR_lock without a pending
1926       // external suspend request and will be able to mark ourselves as
1927       // exiting.
1928     }
1929     // no more external suspends are allowed at this point
1930   } else {
1931     // before_exit() has already posted JVMTI THREAD_END events
1932   }
1933 
1934   if (log_is_enabled(Debug, os, thread, timer)) {
1935     _timer_exit_phase1.stop();
1936     _timer_exit_phase2.start();
1937   }
1938   // Notify waiters on thread object. This has to be done after exit() is called
1939   // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1940   // group should have the destroyed bit set before waiters are notified).
1941   ensure_join(this);
1942   assert(!this->has_pending_exception(), "ensure_join should have cleared");
1943 
1944   if (log_is_enabled(Debug, os, thread, timer)) {
1945     _timer_exit_phase2.stop();
1946     _timer_exit_phase3.start();
1947   }
1948   // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1949   // held by this thread must be released. The spec does not distinguish
1950   // between JNI-acquired and regular Java monitors. We can only see
1951   // regular Java monitors here if monitor enter-exit matching is broken.
1952   //
1953   // ensure_join() ignores IllegalThreadStateExceptions, and so does
1954   // ObjectSynchronizer::release_monitors_owned_by_thread().
1955   if (exit_type == jni_detach) {
1956     // Sanity check even though JNI DetachCurrentThread() would have
1957     // returned JNI_ERR if there was a Java frame. JavaThread exit
1958     // should be done executing Java code by the time we get here.
1959     assert(!this->has_last_Java_frame(),
1960            "should not have a Java frame when detaching or exiting");
1961     ObjectSynchronizer::release_monitors_owned_by_thread(this);
1962     assert(!this->has_pending_exception(), "release_monitors should have cleared");
1963   }
1964 
1965   // These things needs to be done while we are still a Java Thread. Make sure that thread
1966   // is in a consistent state, in case GC happens
1967   assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1968 
1969   if (active_handles() != NULL) {
1970     JNIHandleBlock* block = active_handles();
1971     set_active_handles(NULL);
1972     JNIHandleBlock::release_block(block);
1973   }
1974 
1975   if (free_handle_block() != NULL) {
1976     JNIHandleBlock* block = free_handle_block();
1977     set_free_handle_block(NULL);
1978     JNIHandleBlock::release_block(block);
1979   }
1980 
1981   // These have to be removed while this is still a valid thread.
1982   remove_stack_guard_pages();
1983 
1984   if (UseTLAB) {
1985     tlab().retire();
1986   }
1987 
1988   if (JvmtiEnv::environments_might_exist()) {
1989     JvmtiExport::cleanup_thread(this);
1990   }
1991 
1992   // We must flush any deferred card marks and other various GC barrier
1993   // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer)
1994   // before removing a thread from the list of active threads.
1995   BarrierSet::barrier_set()->on_thread_detach(this);
1996 
1997   log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
1998     exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
1999     os::current_thread_id());
2000 
2001   if (log_is_enabled(Debug, os, thread, timer)) {
2002     _timer_exit_phase3.stop();
2003     _timer_exit_phase4.start();
2004   }
2005   // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
2006   Threads::remove(this);
2007 
2008   if (log_is_enabled(Debug, os, thread, timer)) {
2009     _timer_exit_phase4.stop();
2010     ResourceMark rm(this);
2011     log_debug(os, thread, timer)("name='%s'"
2012                                  ", exit-phase1=" JLONG_FORMAT
2013                                  ", exit-phase2=" JLONG_FORMAT
2014                                  ", exit-phase3=" JLONG_FORMAT
2015                                  ", exit-phase4=" JLONG_FORMAT,
2016                                  get_thread_name(),
2017                                  _timer_exit_phase1.milliseconds(),
2018                                  _timer_exit_phase2.milliseconds(),
2019                                  _timer_exit_phase3.milliseconds(),
2020                                  _timer_exit_phase4.milliseconds());
2021   }
2022 }
2023 
2024 void JavaThread::cleanup_failed_attach_current_thread() {
2025   if (active_handles() != NULL) {
2026     JNIHandleBlock* block = active_handles();
2027     set_active_handles(NULL);
2028     JNIHandleBlock::release_block(block);
2029   }
2030 
2031   if (free_handle_block() != NULL) {
2032     JNIHandleBlock* block = free_handle_block();
2033     set_free_handle_block(NULL);
2034     JNIHandleBlock::release_block(block);
2035   }
2036 
2037   // These have to be removed while this is still a valid thread.
2038   remove_stack_guard_pages();
2039 
2040   if (UseTLAB) {
2041     tlab().retire();
2042   }
2043 
2044   BarrierSet::barrier_set()->on_thread_detach(this);
2045 
2046   Threads::remove(this);
2047   this->smr_delete();
2048 }
2049 
2050 JavaThread* JavaThread::active() {
2051   Thread* thread = Thread::current();
2052   if (thread->is_Java_thread()) {
2053     return (JavaThread*) thread;
2054   } else {
2055     assert(thread->is_VM_thread(), "this must be a vm thread");
2056     VM_Operation* op = ((VMThread*) thread)->vm_operation();
2057     JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2058     assert(ret->is_Java_thread(), "must be a Java thread");
2059     return ret;
2060   }
2061 }
2062 
2063 bool JavaThread::is_lock_owned(address adr) const {
2064   if (Thread::is_lock_owned(adr)) return true;
2065 
2066   for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2067     if (chunk->contains(adr)) return true;
2068   }
2069 
2070   return false;
2071 }
2072 
2073 
2074 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2075   chunk->set_next(monitor_chunks());
2076   set_monitor_chunks(chunk);
2077 }
2078 
2079 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2080   guarantee(monitor_chunks() != NULL, "must be non empty");
2081   if (monitor_chunks() == chunk) {
2082     set_monitor_chunks(chunk->next());
2083   } else {
2084     MonitorChunk* prev = monitor_chunks();
2085     while (prev->next() != chunk) prev = prev->next();
2086     prev->set_next(chunk->next());
2087   }
2088 }
2089 
2090 // JVM support.
2091 
2092 // Note: this function shouldn't block if it's called in
2093 // _thread_in_native_trans state (such as from
2094 // check_special_condition_for_native_trans()).
2095 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2096 
2097   if (has_last_Java_frame() && has_async_condition()) {
2098     // If we are at a polling page safepoint (not a poll return)
2099     // then we must defer async exception because live registers
2100     // will be clobbered by the exception path. Poll return is
2101     // ok because the call we a returning from already collides
2102     // with exception handling registers and so there is no issue.
2103     // (The exception handling path kills call result registers but
2104     //  this is ok since the exception kills the result anyway).
2105 
2106     if (is_at_poll_safepoint()) {
2107       // if the code we are returning to has deoptimized we must defer
2108       // the exception otherwise live registers get clobbered on the
2109       // exception path before deoptimization is able to retrieve them.
2110       //
2111       RegisterMap map(this, false);
2112       frame caller_fr = last_frame().sender(&map);
2113       assert(caller_fr.is_compiled_frame(), "what?");
2114       if (caller_fr.is_deoptimized_frame()) {
2115         log_info(exceptions)("deferred async exception at compiled safepoint");
2116         return;
2117       }
2118     }
2119   }
2120 
2121   JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2122   if (condition == _no_async_condition) {
2123     // Conditions have changed since has_special_runtime_exit_condition()
2124     // was called:
2125     // - if we were here only because of an external suspend request,
2126     //   then that was taken care of above (or cancelled) so we are done
2127     // - if we were here because of another async request, then it has
2128     //   been cleared between the has_special_runtime_exit_condition()
2129     //   and now so again we are done
2130     return;
2131   }
2132 
2133   // Check for pending async. exception
2134   if (_pending_async_exception != NULL) {
2135     // Only overwrite an already pending exception, if it is not a threadDeath.
2136     if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2137 
2138       // We cannot call Exceptions::_throw(...) here because we cannot block
2139       set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2140 
2141       LogTarget(Info, exceptions) lt;
2142       if (lt.is_enabled()) {
2143         ResourceMark rm;
2144         LogStream ls(lt);
2145         ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2146           if (has_last_Java_frame()) {
2147             frame f = last_frame();
2148            ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2149           }
2150         ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2151       }
2152       _pending_async_exception = NULL;
2153       clear_has_async_exception();
2154     }
2155   }
2156 
2157   if (check_unsafe_error &&
2158       condition == _async_unsafe_access_error && !has_pending_exception()) {
2159     condition = _no_async_condition;  // done
2160     switch (thread_state()) {
2161     case _thread_in_vm: {
2162       JavaThread* THREAD = this;
2163       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2164     }
2165     case _thread_in_native: {
2166       ThreadInVMfromNative tiv(this);
2167       JavaThread* THREAD = this;
2168       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2169     }
2170     case _thread_in_Java: {
2171       ThreadInVMfromJava tiv(this);
2172       JavaThread* THREAD = this;
2173       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2174     }
2175     default:
2176       ShouldNotReachHere();
2177     }
2178   }
2179 
2180   assert(condition == _no_async_condition || has_pending_exception() ||
2181          (!check_unsafe_error && condition == _async_unsafe_access_error),
2182          "must have handled the async condition, if no exception");
2183 }
2184 
2185 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2186   //
2187   // Check for pending external suspend. Internal suspend requests do
2188   // not use handle_special_runtime_exit_condition().
2189   // If JNIEnv proxies are allowed, don't self-suspend if the target
2190   // thread is not the current thread. In older versions of jdbx, jdbx
2191   // threads could call into the VM with another thread's JNIEnv so we
2192   // can be here operating on behalf of a suspended thread (4432884).
2193   bool do_self_suspend = is_external_suspend_with_lock();
2194   if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2195     //
2196     // Because thread is external suspended the safepoint code will count
2197     // thread as at a safepoint. This can be odd because we can be here
2198     // as _thread_in_Java which would normally transition to _thread_blocked
2199     // at a safepoint. We would like to mark the thread as _thread_blocked
2200     // before calling java_suspend_self like all other callers of it but
2201     // we must then observe proper safepoint protocol. (We can't leave
2202     // _thread_blocked with a safepoint in progress). However we can be
2203     // here as _thread_in_native_trans so we can't use a normal transition
2204     // constructor/destructor pair because they assert on that type of
2205     // transition. We could do something like:
2206     //
2207     // JavaThreadState state = thread_state();
2208     // set_thread_state(_thread_in_vm);
2209     // {
2210     //   ThreadBlockInVM tbivm(this);
2211     //   java_suspend_self()
2212     // }
2213     // set_thread_state(_thread_in_vm_trans);
2214     // if (safepoint) block;
2215     // set_thread_state(state);
2216     //
2217     // but that is pretty messy. Instead we just go with the way the
2218     // code has worked before and note that this is the only path to
2219     // java_suspend_self that doesn't put the thread in _thread_blocked
2220     // mode.
2221 
2222     frame_anchor()->make_walkable(this);
2223     java_suspend_self();
2224 
2225     // We might be here for reasons in addition to the self-suspend request
2226     // so check for other async requests.
2227   }
2228 
2229   if (check_asyncs) {
2230     check_and_handle_async_exceptions();
2231   }
2232 
2233   JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);)
2234 }
2235 
2236 void JavaThread::send_thread_stop(oop java_throwable)  {
2237   assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2238   assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2239   assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2240 
2241   // Do not throw asynchronous exceptions against the compiler thread
2242   // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2243   if (!can_call_java()) return;
2244 
2245   {
2246     // Actually throw the Throwable against the target Thread - however
2247     // only if there is no thread death exception installed already.
2248     if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2249       // If the topmost frame is a runtime stub, then we are calling into
2250       // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2251       // must deoptimize the caller before continuing, as the compiled  exception handler table
2252       // may not be valid
2253       if (has_last_Java_frame()) {
2254         frame f = last_frame();
2255         if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2256           // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2257           RegisterMap reg_map(this, UseBiasedLocking);
2258           frame compiled_frame = f.sender(&reg_map);
2259           if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2260             Deoptimization::deoptimize(this, compiled_frame, &reg_map);
2261           }
2262         }
2263       }
2264 
2265       // Set async. pending exception in thread.
2266       set_pending_async_exception(java_throwable);
2267 
2268       if (log_is_enabled(Info, exceptions)) {
2269          ResourceMark rm;
2270         log_info(exceptions)("Pending Async. exception installed of type: %s",
2271                              InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2272       }
2273       // for AbortVMOnException flag
2274       Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2275     }
2276   }
2277 
2278 
2279   // Interrupt thread so it will wake up from a potential wait()
2280   Thread::interrupt(this);
2281 }
2282 
2283 // External suspension mechanism.
2284 //
2285 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2286 // to any VM_locks and it is at a transition
2287 // Self-suspension will happen on the transition out of the vm.
2288 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2289 //
2290 // Guarantees on return:
2291 //   + Target thread will not execute any new bytecode (that's why we need to
2292 //     force a safepoint)
2293 //   + Target thread will not enter any new monitors
2294 //
2295 void JavaThread::java_suspend() {
2296   ThreadsListHandle tlh;
2297   if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) {
2298     return;
2299   }
2300 
2301   { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2302     if (!is_external_suspend()) {
2303       // a racing resume has cancelled us; bail out now
2304       return;
2305     }
2306 
2307     // suspend is done
2308     uint32_t debug_bits = 0;
2309     // Warning: is_ext_suspend_completed() may temporarily drop the
2310     // SR_lock to allow the thread to reach a stable thread state if
2311     // it is currently in a transient thread state.
2312     if (is_ext_suspend_completed(false /* !called_by_wait */,
2313                                  SuspendRetryDelay, &debug_bits)) {
2314       return;
2315     }
2316   }
2317 
2318   VM_ThreadSuspend vm_suspend;
2319   VMThread::execute(&vm_suspend);
2320 }
2321 
2322 // Part II of external suspension.
2323 // A JavaThread self suspends when it detects a pending external suspend
2324 // request. This is usually on transitions. It is also done in places
2325 // where continuing to the next transition would surprise the caller,
2326 // e.g., monitor entry.
2327 //
2328 // Returns the number of times that the thread self-suspended.
2329 //
2330 // Note: DO NOT call java_suspend_self() when you just want to block current
2331 //       thread. java_suspend_self() is the second stage of cooperative
2332 //       suspension for external suspend requests and should only be used
2333 //       to complete an external suspend request.
2334 //
2335 int JavaThread::java_suspend_self() {
2336   int ret = 0;
2337 
2338   // we are in the process of exiting so don't suspend
2339   if (is_exiting()) {
2340     clear_external_suspend();
2341     return ret;
2342   }
2343 
2344   assert(_anchor.walkable() ||
2345          (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2346          "must have walkable stack");
2347 
2348   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2349 
2350   assert(!this->is_ext_suspended(),
2351          "a thread trying to self-suspend should not already be suspended");
2352 
2353   if (this->is_suspend_equivalent()) {
2354     // If we are self-suspending as a result of the lifting of a
2355     // suspend equivalent condition, then the suspend_equivalent
2356     // flag is not cleared until we set the ext_suspended flag so
2357     // that wait_for_ext_suspend_completion() returns consistent
2358     // results.
2359     this->clear_suspend_equivalent();
2360   }
2361 
2362   // A racing resume may have cancelled us before we grabbed SR_lock
2363   // above. Or another external suspend request could be waiting for us
2364   // by the time we return from SR_lock()->wait(). The thread
2365   // that requested the suspension may already be trying to walk our
2366   // stack and if we return now, we can change the stack out from under
2367   // it. This would be a "bad thing (TM)" and cause the stack walker
2368   // to crash. We stay self-suspended until there are no more pending
2369   // external suspend requests.
2370   while (is_external_suspend()) {
2371     ret++;
2372     this->set_ext_suspended();
2373 
2374     // _ext_suspended flag is cleared by java_resume()
2375     while (is_ext_suspended()) {
2376       this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2377     }
2378   }
2379 
2380   return ret;
2381 }
2382 
2383 #ifdef ASSERT
2384 // Verify the JavaThread has not yet been published in the Threads::list, and
2385 // hence doesn't need protection from concurrent access at this stage.
2386 void JavaThread::verify_not_published() {
2387   // Cannot create a ThreadsListHandle here and check !tlh.includes(this)
2388   // since an unpublished JavaThread doesn't participate in the
2389   // Thread-SMR protocol for keeping a ThreadsList alive.
2390   assert(!on_thread_list(), "JavaThread shouldn't have been published yet!");
2391 }
2392 #endif
2393 
2394 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2395 // progress or when _suspend_flags is non-zero.
2396 // Current thread needs to self-suspend if there is a suspend request and/or
2397 // block if a safepoint is in progress.
2398 // Async exception ISN'T checked.
2399 // Note only the ThreadInVMfromNative transition can call this function
2400 // directly and when thread state is _thread_in_native_trans
2401 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2402   assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2403 
2404   JavaThread *curJT = JavaThread::current();
2405   bool do_self_suspend = thread->is_external_suspend();
2406 
2407   assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2408 
2409   // If JNIEnv proxies are allowed, don't self-suspend if the target
2410   // thread is not the current thread. In older versions of jdbx, jdbx
2411   // threads could call into the VM with another thread's JNIEnv so we
2412   // can be here operating on behalf of a suspended thread (4432884).
2413   if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2414     JavaThreadState state = thread->thread_state();
2415 
2416     // We mark this thread_blocked state as a suspend-equivalent so
2417     // that a caller to is_ext_suspend_completed() won't be confused.
2418     // The suspend-equivalent state is cleared by java_suspend_self().
2419     thread->set_suspend_equivalent();
2420 
2421     // If the safepoint code sees the _thread_in_native_trans state, it will
2422     // wait until the thread changes to other thread state. There is no
2423     // guarantee on how soon we can obtain the SR_lock and complete the
2424     // self-suspend request. It would be a bad idea to let safepoint wait for
2425     // too long. Temporarily change the state to _thread_blocked to
2426     // let the VM thread know that this thread is ready for GC. The problem
2427     // of changing thread state is that safepoint could happen just after
2428     // java_suspend_self() returns after being resumed, and VM thread will
2429     // see the _thread_blocked state. We must check for safepoint
2430     // after restoring the state and make sure we won't leave while a safepoint
2431     // is in progress.
2432     thread->set_thread_state(_thread_blocked);
2433     thread->java_suspend_self();
2434     thread->set_thread_state(state);
2435 
2436     InterfaceSupport::serialize_thread_state_with_handler(thread);
2437   }
2438 
2439   SafepointMechanism::block_if_requested(curJT);
2440 
2441   if (thread->is_deopt_suspend()) {
2442     thread->clear_deopt_suspend();
2443     RegisterMap map(thread, false);
2444     frame f = thread->last_frame();
2445     while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2446       f = f.sender(&map);
2447     }
2448     if (f.id() == thread->must_deopt_id()) {
2449       thread->clear_must_deopt_id();
2450       f.deoptimize(thread);
2451     } else {
2452       fatal("missed deoptimization!");
2453     }
2454   }
2455 
2456   JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(thread);)
2457 }
2458 
2459 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2460 // progress or when _suspend_flags is non-zero.
2461 // Current thread needs to self-suspend if there is a suspend request and/or
2462 // block if a safepoint is in progress.
2463 // Also check for pending async exception (not including unsafe access error).
2464 // Note only the native==>VM/Java barriers can call this function and when
2465 // thread state is _thread_in_native_trans.
2466 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2467   check_safepoint_and_suspend_for_native_trans(thread);
2468 
2469   if (thread->has_async_exception()) {
2470     // We are in _thread_in_native_trans state, don't handle unsafe
2471     // access error since that may block.
2472     thread->check_and_handle_async_exceptions(false);
2473   }
2474 }
2475 
2476 // This is a variant of the normal
2477 // check_special_condition_for_native_trans with slightly different
2478 // semantics for use by critical native wrappers.  It does all the
2479 // normal checks but also performs the transition back into
2480 // thread_in_Java state.  This is required so that critical natives
2481 // can potentially block and perform a GC if they are the last thread
2482 // exiting the GCLocker.
2483 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2484   check_special_condition_for_native_trans(thread);
2485 
2486   // Finish the transition
2487   thread->set_thread_state(_thread_in_Java);
2488 
2489   if (thread->do_critical_native_unlock()) {
2490     ThreadInVMfromJavaNoAsyncException tiv(thread);
2491     GCLocker::unlock_critical(thread);
2492     thread->clear_critical_native_unlock();
2493   }
2494 }
2495 
2496 // We need to guarantee the Threads_lock here, since resumes are not
2497 // allowed during safepoint synchronization
2498 // Can only resume from an external suspension
2499 void JavaThread::java_resume() {
2500   assert_locked_or_safepoint(Threads_lock);
2501 
2502   // Sanity check: thread is gone, has started exiting or the thread
2503   // was not externally suspended.
2504   ThreadsListHandle tlh;
2505   if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) {
2506     return;
2507   }
2508 
2509   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2510 
2511   clear_external_suspend();
2512 
2513   if (is_ext_suspended()) {
2514     clear_ext_suspended();
2515     SR_lock()->notify_all();
2516   }
2517 }
2518 
2519 size_t JavaThread::_stack_red_zone_size = 0;
2520 size_t JavaThread::_stack_yellow_zone_size = 0;
2521 size_t JavaThread::_stack_reserved_zone_size = 0;
2522 size_t JavaThread::_stack_shadow_zone_size = 0;
2523 
2524 void JavaThread::create_stack_guard_pages() {
2525   if (!os::uses_stack_guard_pages() ||
2526       _stack_guard_state != stack_guard_unused ||
2527       (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) {
2528       log_info(os, thread)("Stack guard page creation for thread "
2529                            UINTX_FORMAT " disabled", os::current_thread_id());
2530     return;
2531   }
2532   address low_addr = stack_end();
2533   size_t len = stack_guard_zone_size();
2534 
2535   assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2536   assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2537 
2538   int must_commit = os::must_commit_stack_guard_pages();
2539   // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2540 
2541   if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2542     log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2543     return;
2544   }
2545 
2546   if (os::guard_memory((char *) low_addr, len)) {
2547     _stack_guard_state = stack_guard_enabled;
2548   } else {
2549     log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2550       PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2551     if (os::uncommit_memory((char *) low_addr, len)) {
2552       log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2553     }
2554     return;
2555   }
2556 
2557   log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2558     PTR_FORMAT "-" PTR_FORMAT ".",
2559     os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2560 }
2561 
2562 void JavaThread::remove_stack_guard_pages() {
2563   assert(Thread::current() == this, "from different thread");
2564   if (_stack_guard_state == stack_guard_unused) return;
2565   address low_addr = stack_end();
2566   size_t len = stack_guard_zone_size();
2567 
2568   if (os::must_commit_stack_guard_pages()) {
2569     if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2570       _stack_guard_state = stack_guard_unused;
2571     } else {
2572       log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2573         PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2574       return;
2575     }
2576   } else {
2577     if (_stack_guard_state == stack_guard_unused) return;
2578     if (os::unguard_memory((char *) low_addr, len)) {
2579       _stack_guard_state = stack_guard_unused;
2580     } else {
2581       log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2582         PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2583       return;
2584     }
2585   }
2586 
2587   log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2588     PTR_FORMAT "-" PTR_FORMAT ".",
2589     os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2590 }
2591 
2592 void JavaThread::enable_stack_reserved_zone() {
2593   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2594   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2595 
2596   // The base notation is from the stack's point of view, growing downward.
2597   // We need to adjust it to work correctly with guard_memory()
2598   address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2599 
2600   guarantee(base < stack_base(),"Error calculating stack reserved zone");
2601   guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2602 
2603   if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2604     _stack_guard_state = stack_guard_enabled;
2605   } else {
2606     warning("Attempt to guard stack reserved zone failed.");
2607   }
2608   enable_register_stack_guard();
2609 }
2610 
2611 void JavaThread::disable_stack_reserved_zone() {
2612   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2613   assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2614 
2615   // Simply return if called for a thread that does not use guard pages.
2616   if (_stack_guard_state == stack_guard_unused) return;
2617 
2618   // The base notation is from the stack's point of view, growing downward.
2619   // We need to adjust it to work correctly with guard_memory()
2620   address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2621 
2622   if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2623     _stack_guard_state = stack_guard_reserved_disabled;
2624   } else {
2625     warning("Attempt to unguard stack reserved zone failed.");
2626   }
2627   disable_register_stack_guard();
2628 }
2629 
2630 void JavaThread::enable_stack_yellow_reserved_zone() {
2631   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2632   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2633 
2634   // The base notation is from the stacks point of view, growing downward.
2635   // We need to adjust it to work correctly with guard_memory()
2636   address base = stack_red_zone_base();
2637 
2638   guarantee(base < stack_base(), "Error calculating stack yellow zone");
2639   guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2640 
2641   if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2642     _stack_guard_state = stack_guard_enabled;
2643   } else {
2644     warning("Attempt to guard stack yellow zone failed.");
2645   }
2646   enable_register_stack_guard();
2647 }
2648 
2649 void JavaThread::disable_stack_yellow_reserved_zone() {
2650   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2651   assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2652 
2653   // Simply return if called for a thread that does not use guard pages.
2654   if (_stack_guard_state == stack_guard_unused) return;
2655 
2656   // The base notation is from the stacks point of view, growing downward.
2657   // We need to adjust it to work correctly with guard_memory()
2658   address base = stack_red_zone_base();
2659 
2660   if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2661     _stack_guard_state = stack_guard_yellow_reserved_disabled;
2662   } else {
2663     warning("Attempt to unguard stack yellow zone failed.");
2664   }
2665   disable_register_stack_guard();
2666 }
2667 
2668 void JavaThread::enable_stack_red_zone() {
2669   // The base notation is from the stacks point of view, growing downward.
2670   // We need to adjust it to work correctly with guard_memory()
2671   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2672   address base = stack_red_zone_base() - stack_red_zone_size();
2673 
2674   guarantee(base < stack_base(), "Error calculating stack red zone");
2675   guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2676 
2677   if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2678     warning("Attempt to guard stack red zone failed.");
2679   }
2680 }
2681 
2682 void JavaThread::disable_stack_red_zone() {
2683   // The base notation is from the stacks point of view, growing downward.
2684   // We need to adjust it to work correctly with guard_memory()
2685   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2686   address base = stack_red_zone_base() - stack_red_zone_size();
2687   if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2688     warning("Attempt to unguard stack red zone failed.");
2689   }
2690 }
2691 
2692 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2693   // ignore is there is no stack
2694   if (!has_last_Java_frame()) return;
2695   // traverse the stack frames. Starts from top frame.
2696   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2697     frame* fr = fst.current();
2698     f(fr, fst.register_map());
2699   }
2700 }
2701 
2702 
2703 #ifndef PRODUCT
2704 // Deoptimization
2705 // Function for testing deoptimization
2706 void JavaThread::deoptimize() {
2707   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2708   StackFrameStream fst(this, UseBiasedLocking);
2709   bool deopt = false;           // Dump stack only if a deopt actually happens.
2710   bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2711   // Iterate over all frames in the thread and deoptimize
2712   for (; !fst.is_done(); fst.next()) {
2713     if (fst.current()->can_be_deoptimized()) {
2714 
2715       if (only_at) {
2716         // Deoptimize only at particular bcis.  DeoptimizeOnlyAt
2717         // consists of comma or carriage return separated numbers so
2718         // search for the current bci in that string.
2719         address pc = fst.current()->pc();
2720         nmethod* nm =  (nmethod*) fst.current()->cb();
2721         ScopeDesc* sd = nm->scope_desc_at(pc);
2722         char buffer[8];
2723         jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2724         size_t len = strlen(buffer);
2725         const char * found = strstr(DeoptimizeOnlyAt, buffer);
2726         while (found != NULL) {
2727           if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2728               (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2729             // Check that the bci found is bracketed by terminators.
2730             break;
2731           }
2732           found = strstr(found + 1, buffer);
2733         }
2734         if (!found) {
2735           continue;
2736         }
2737       }
2738 
2739       if (DebugDeoptimization && !deopt) {
2740         deopt = true; // One-time only print before deopt
2741         tty->print_cr("[BEFORE Deoptimization]");
2742         trace_frames();
2743         trace_stack();
2744       }
2745       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2746     }
2747   }
2748 
2749   if (DebugDeoptimization && deopt) {
2750     tty->print_cr("[AFTER Deoptimization]");
2751     trace_frames();
2752   }
2753 }
2754 
2755 
2756 // Make zombies
2757 void JavaThread::make_zombies() {
2758   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2759     if (fst.current()->can_be_deoptimized()) {
2760       // it is a Java nmethod
2761       nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2762       nm->make_not_entrant();
2763     }
2764   }
2765 }
2766 #endif // PRODUCT
2767 
2768 
2769 void JavaThread::deoptimized_wrt_marked_nmethods() {
2770   if (!has_last_Java_frame()) return;
2771   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2772   StackFrameStream fst(this, UseBiasedLocking);
2773   for (; !fst.is_done(); fst.next()) {
2774     if (fst.current()->should_be_deoptimized()) {
2775       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2776     }
2777   }
2778 }
2779 
2780 
2781 // If the caller is a NamedThread, then remember, in the current scope,
2782 // the given JavaThread in its _processed_thread field.
2783 class RememberProcessedThread: public StackObj {
2784   NamedThread* _cur_thr;
2785  public:
2786   RememberProcessedThread(JavaThread* jthr) {
2787     Thread* thread = Thread::current();
2788     if (thread->is_Named_thread()) {
2789       _cur_thr = (NamedThread *)thread;
2790       _cur_thr->set_processed_thread(jthr);
2791     } else {
2792       _cur_thr = NULL;
2793     }
2794   }
2795 
2796   ~RememberProcessedThread() {
2797     if (_cur_thr) {
2798       _cur_thr->set_processed_thread(NULL);
2799     }
2800   }
2801 };
2802 
2803 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2804   // Verify that the deferred card marks have been flushed.
2805   assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2806 
2807   // Traverse the GCHandles
2808   Thread::oops_do(f, cf);
2809 
2810   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2811          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2812 
2813   if (has_last_Java_frame()) {
2814     // Record JavaThread to GC thread
2815     RememberProcessedThread rpt(this);
2816 
2817     // Traverse the privileged stack
2818     if (_privileged_stack_top != NULL) {
2819       _privileged_stack_top->oops_do(f);
2820     }
2821 
2822     // traverse the registered growable array
2823     if (_array_for_gc != NULL) {
2824       for (int index = 0; index < _array_for_gc->length(); index++) {
2825         f->do_oop(_array_for_gc->adr_at(index));
2826       }
2827     }
2828 
2829     // Traverse the monitor chunks
2830     for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2831       chunk->oops_do(f);
2832     }
2833 
2834     // Traverse the execution stack
2835     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2836       fst.current()->oops_do(f, cf, fst.register_map());
2837     }
2838   }
2839 
2840   // callee_target is never live across a gc point so NULL it here should
2841   // it still contain a methdOop.
2842 
2843   set_callee_target(NULL);
2844 
2845   assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2846   // If we have deferred set_locals there might be oops waiting to be
2847   // written
2848   GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2849   if (list != NULL) {
2850     for (int i = 0; i < list->length(); i++) {
2851       list->at(i)->oops_do(f);
2852     }
2853   }
2854 
2855   // Traverse instance variables at the end since the GC may be moving things
2856   // around using this function
2857   f->do_oop((oop*) &_threadObj);
2858   f->do_oop((oop*) &_vm_result);
2859   f->do_oop((oop*) &_exception_oop);
2860   f->do_oop((oop*) &_pending_async_exception);
2861 
2862   if (jvmti_thread_state() != NULL) {
2863     jvmti_thread_state()->oops_do(f);
2864   }
2865 }
2866 
2867 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2868   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2869          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2870 
2871   if (has_last_Java_frame()) {
2872     // Traverse the execution stack
2873     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2874       fst.current()->nmethods_do(cf);
2875     }
2876   }
2877 }
2878 
2879 void JavaThread::metadata_do(void f(Metadata*)) {
2880   if (has_last_Java_frame()) {
2881     // Traverse the execution stack to call f() on the methods in the stack
2882     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2883       fst.current()->metadata_do(f);
2884     }
2885   } else if (is_Compiler_thread()) {
2886     // need to walk ciMetadata in current compile tasks to keep alive.
2887     CompilerThread* ct = (CompilerThread*)this;
2888     if (ct->env() != NULL) {
2889       ct->env()->metadata_do(f);
2890     }
2891     CompileTask* task = ct->task();
2892     if (task != NULL) {
2893       task->metadata_do(f);
2894     }
2895   }
2896 }
2897 
2898 // Printing
2899 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2900   switch (_thread_state) {
2901   case _thread_uninitialized:     return "_thread_uninitialized";
2902   case _thread_new:               return "_thread_new";
2903   case _thread_new_trans:         return "_thread_new_trans";
2904   case _thread_in_native:         return "_thread_in_native";
2905   case _thread_in_native_trans:   return "_thread_in_native_trans";
2906   case _thread_in_vm:             return "_thread_in_vm";
2907   case _thread_in_vm_trans:       return "_thread_in_vm_trans";
2908   case _thread_in_Java:           return "_thread_in_Java";
2909   case _thread_in_Java_trans:     return "_thread_in_Java_trans";
2910   case _thread_blocked:           return "_thread_blocked";
2911   case _thread_blocked_trans:     return "_thread_blocked_trans";
2912   default:                        return "unknown thread state";
2913   }
2914 }
2915 
2916 #ifndef PRODUCT
2917 void JavaThread::print_thread_state_on(outputStream *st) const {
2918   st->print_cr("   JavaThread state: %s", _get_thread_state_name(_thread_state));
2919 };
2920 void JavaThread::print_thread_state() const {
2921   print_thread_state_on(tty);
2922 }
2923 #endif // PRODUCT
2924 
2925 // Called by Threads::print() for VM_PrintThreads operation
2926 void JavaThread::print_on(outputStream *st, bool print_extended_info) const {
2927   st->print_raw("\"");
2928   st->print_raw(get_thread_name());
2929   st->print_raw("\" ");
2930   oop thread_oop = threadObj();
2931   if (thread_oop != NULL) {
2932     st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
2933     if (java_lang_Thread::is_daemon(thread_oop))  st->print("daemon ");
2934     st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2935   }
2936   Thread::print_on(st, print_extended_info);
2937   // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2938   st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2939   if (thread_oop != NULL) {
2940     st->print_cr("   java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2941   }
2942 #ifndef PRODUCT
2943   print_thread_state_on(st);
2944   _safepoint_state->print_on(st);
2945 #endif // PRODUCT
2946   if (is_Compiler_thread()) {
2947     CompileTask *task = ((CompilerThread*)this)->task();
2948     if (task != NULL) {
2949       st->print("   Compiling: ");
2950       task->print(st, NULL, true, false);
2951     } else {
2952       st->print("   No compile task");
2953     }
2954     st->cr();
2955   }
2956 }
2957 
2958 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2959   st->print("%s", get_thread_name_string(buf, buflen));
2960 }
2961 
2962 // Called by fatal error handler. The difference between this and
2963 // JavaThread::print() is that we can't grab lock or allocate memory.
2964 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2965   st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2966   oop thread_obj = threadObj();
2967   if (thread_obj != NULL) {
2968     if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2969   }
2970   st->print(" [");
2971   st->print("%s", _get_thread_state_name(_thread_state));
2972   if (osthread()) {
2973     st->print(", id=%d", osthread()->thread_id());
2974   }
2975   st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2976             p2i(stack_end()), p2i(stack_base()));
2977   st->print("]");
2978 
2979   ThreadsSMRSupport::print_info_on(this, st);
2980   return;
2981 }
2982 
2983 // Verification
2984 
2985 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2986 
2987 void JavaThread::verify() {
2988   // Verify oops in the thread.
2989   oops_do(&VerifyOopClosure::verify_oop, NULL);
2990 
2991   // Verify the stack frames.
2992   frames_do(frame_verify);
2993 }
2994 
2995 // CR 6300358 (sub-CR 2137150)
2996 // Most callers of this method assume that it can't return NULL but a
2997 // thread may not have a name whilst it is in the process of attaching to
2998 // the VM - see CR 6412693, and there are places where a JavaThread can be
2999 // seen prior to having it's threadObj set (eg JNI attaching threads and
3000 // if vm exit occurs during initialization). These cases can all be accounted
3001 // for such that this method never returns NULL.
3002 const char* JavaThread::get_thread_name() const {
3003 #ifdef ASSERT
3004   // early safepoints can hit while current thread does not yet have TLS
3005   if (!SafepointSynchronize::is_at_safepoint()) {
3006     Thread *cur = Thread::current();
3007     if (!(cur->is_Java_thread() && cur == this)) {
3008       // Current JavaThreads are allowed to get their own name without
3009       // the Threads_lock.
3010       assert_locked_or_safepoint(Threads_lock);
3011     }
3012   }
3013 #endif // ASSERT
3014   return get_thread_name_string();
3015 }
3016 
3017 // Returns a non-NULL representation of this thread's name, or a suitable
3018 // descriptive string if there is no set name
3019 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3020   const char* name_str;
3021   oop thread_obj = threadObj();
3022   if (thread_obj != NULL) {
3023     oop name = java_lang_Thread::name(thread_obj);
3024     if (name != NULL) {
3025       if (buf == NULL) {
3026         name_str = java_lang_String::as_utf8_string(name);
3027       } else {
3028         name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3029       }
3030     } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3031       name_str = "<no-name - thread is attaching>";
3032     } else {
3033       name_str = Thread::name();
3034     }
3035   } else {
3036     name_str = Thread::name();
3037   }
3038   assert(name_str != NULL, "unexpected NULL thread name");
3039   return name_str;
3040 }
3041 
3042 
3043 const char* JavaThread::get_threadgroup_name() const {
3044   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3045   oop thread_obj = threadObj();
3046   if (thread_obj != NULL) {
3047     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3048     if (thread_group != NULL) {
3049       // ThreadGroup.name can be null
3050       return java_lang_ThreadGroup::name(thread_group);
3051     }
3052   }
3053   return NULL;
3054 }
3055 
3056 const char* JavaThread::get_parent_name() const {
3057   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3058   oop thread_obj = threadObj();
3059   if (thread_obj != NULL) {
3060     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3061     if (thread_group != NULL) {
3062       oop parent = java_lang_ThreadGroup::parent(thread_group);
3063       if (parent != NULL) {
3064         // ThreadGroup.name can be null
3065         return java_lang_ThreadGroup::name(parent);
3066       }
3067     }
3068   }
3069   return NULL;
3070 }
3071 
3072 ThreadPriority JavaThread::java_priority() const {
3073   oop thr_oop = threadObj();
3074   if (thr_oop == NULL) return NormPriority; // Bootstrapping
3075   ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3076   assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3077   return priority;
3078 }
3079 
3080 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3081 
3082   assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3083   // Link Java Thread object <-> C++ Thread
3084 
3085   // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3086   // and put it into a new Handle.  The Handle "thread_oop" can then
3087   // be used to pass the C++ thread object to other methods.
3088 
3089   // Set the Java level thread object (jthread) field of the
3090   // new thread (a JavaThread *) to C++ thread object using the
3091   // "thread_oop" handle.
3092 
3093   // Set the thread field (a JavaThread *) of the
3094   // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3095 
3096   Handle thread_oop(Thread::current(),
3097                     JNIHandles::resolve_non_null(jni_thread));
3098   assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3099          "must be initialized");
3100   set_threadObj(thread_oop());
3101   java_lang_Thread::set_thread(thread_oop(), this);
3102 
3103   if (prio == NoPriority) {
3104     prio = java_lang_Thread::priority(thread_oop());
3105     assert(prio != NoPriority, "A valid priority should be present");
3106   }
3107 
3108   // Push the Java priority down to the native thread; needs Threads_lock
3109   Thread::set_priority(this, prio);
3110 
3111   // Add the new thread to the Threads list and set it in motion.
3112   // We must have threads lock in order to call Threads::add.
3113   // It is crucial that we do not block before the thread is
3114   // added to the Threads list for if a GC happens, then the java_thread oop
3115   // will not be visited by GC.
3116   Threads::add(this);
3117 }
3118 
3119 oop JavaThread::current_park_blocker() {
3120   // Support for JSR-166 locks
3121   oop thread_oop = threadObj();
3122   if (thread_oop != NULL &&
3123       JDK_Version::current().supports_thread_park_blocker()) {
3124     return java_lang_Thread::park_blocker(thread_oop);
3125   }
3126   return NULL;
3127 }
3128 
3129 
3130 void JavaThread::print_stack_on(outputStream* st) {
3131   if (!has_last_Java_frame()) return;
3132   ResourceMark rm;
3133   HandleMark   hm;
3134 
3135   RegisterMap reg_map(this);
3136   vframe* start_vf = last_java_vframe(&reg_map);
3137   int count = 0;
3138   for (vframe* f = start_vf; f != NULL; f = f->sender()) {
3139     if (f->is_java_frame()) {
3140       javaVFrame* jvf = javaVFrame::cast(f);
3141       java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3142 
3143       // Print out lock information
3144       if (JavaMonitorsInStackTrace) {
3145         jvf->print_lock_info_on(st, count);
3146       }
3147     } else {
3148       // Ignore non-Java frames
3149     }
3150 
3151     // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
3152     count++;
3153     if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
3154   }
3155 }
3156 
3157 
3158 // JVMTI PopFrame support
3159 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3160   assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3161   if (in_bytes(size_in_bytes) != 0) {
3162     _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3163     _popframe_preserved_args_size = in_bytes(size_in_bytes);
3164     Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3165   }
3166 }
3167 
3168 void* JavaThread::popframe_preserved_args() {
3169   return _popframe_preserved_args;
3170 }
3171 
3172 ByteSize JavaThread::popframe_preserved_args_size() {
3173   return in_ByteSize(_popframe_preserved_args_size);
3174 }
3175 
3176 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3177   int sz = in_bytes(popframe_preserved_args_size());
3178   assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3179   return in_WordSize(sz / wordSize);
3180 }
3181 
3182 void JavaThread::popframe_free_preserved_args() {
3183   assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3184   FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3185   _popframe_preserved_args = NULL;
3186   _popframe_preserved_args_size = 0;
3187 }
3188 
3189 #ifndef PRODUCT
3190 
3191 void JavaThread::trace_frames() {
3192   tty->print_cr("[Describe stack]");
3193   int frame_no = 1;
3194   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3195     tty->print("  %d. ", frame_no++);
3196     fst.current()->print_value_on(tty, this);
3197     tty->cr();
3198   }
3199 }
3200 
3201 class PrintAndVerifyOopClosure: public OopClosure {
3202  protected:
3203   template <class T> inline void do_oop_work(T* p) {
3204     oop obj = RawAccess<>::oop_load(p);
3205     if (obj == NULL) return;
3206     tty->print(INTPTR_FORMAT ": ", p2i(p));
3207     if (oopDesc::is_oop_or_null(obj)) {
3208       if (obj->is_objArray()) {
3209         tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3210       } else {
3211         obj->print();
3212       }
3213     } else {
3214       tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3215     }
3216     tty->cr();
3217   }
3218  public:
3219   virtual void do_oop(oop* p) { do_oop_work(p); }
3220   virtual void do_oop(narrowOop* p)  { do_oop_work(p); }
3221 };
3222 
3223 
3224 static void oops_print(frame* f, const RegisterMap *map) {
3225   PrintAndVerifyOopClosure print;
3226   f->print_value();
3227   f->oops_do(&print, NULL, (RegisterMap*)map);
3228 }
3229 
3230 // Print our all the locations that contain oops and whether they are
3231 // valid or not.  This useful when trying to find the oldest frame
3232 // where an oop has gone bad since the frame walk is from youngest to
3233 // oldest.
3234 void JavaThread::trace_oops() {
3235   tty->print_cr("[Trace oops]");
3236   frames_do(oops_print);
3237 }
3238 
3239 
3240 #ifdef ASSERT
3241 // Print or validate the layout of stack frames
3242 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3243   ResourceMark rm;
3244   PRESERVE_EXCEPTION_MARK;
3245   FrameValues values;
3246   int frame_no = 0;
3247   for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3248     fst.current()->describe(values, ++frame_no);
3249     if (depth == frame_no) break;
3250   }
3251   if (validate_only) {
3252     values.validate();
3253   } else {
3254     tty->print_cr("[Describe stack layout]");
3255     values.print(this);
3256   }
3257 }
3258 #endif
3259 
3260 void JavaThread::trace_stack_from(vframe* start_vf) {
3261   ResourceMark rm;
3262   int vframe_no = 1;
3263   for (vframe* f = start_vf; f; f = f->sender()) {
3264     if (f->is_java_frame()) {
3265       javaVFrame::cast(f)->print_activation(vframe_no++);
3266     } else {
3267       f->print();
3268     }
3269     if (vframe_no > StackPrintLimit) {
3270       tty->print_cr("...<more frames>...");
3271       return;
3272     }
3273   }
3274 }
3275 
3276 
3277 void JavaThread::trace_stack() {
3278   if (!has_last_Java_frame()) return;
3279   ResourceMark rm;
3280   HandleMark   hm;
3281   RegisterMap reg_map(this);
3282   trace_stack_from(last_java_vframe(&reg_map));
3283 }
3284 
3285 
3286 #endif // PRODUCT
3287 
3288 
3289 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3290   assert(reg_map != NULL, "a map must be given");
3291   frame f = last_frame();
3292   for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3293     if (vf->is_java_frame()) return javaVFrame::cast(vf);
3294   }
3295   return NULL;
3296 }
3297 
3298 
3299 Klass* JavaThread::security_get_caller_class(int depth) {
3300   vframeStream vfst(this);
3301   vfst.security_get_caller_frame(depth);
3302   if (!vfst.at_end()) {
3303     return vfst.method()->method_holder();
3304   }
3305   return NULL;
3306 }
3307 
3308 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3309   assert(thread->is_Compiler_thread(), "must be compiler thread");
3310   CompileBroker::compiler_thread_loop();
3311 }
3312 
3313 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3314   NMethodSweeper::sweeper_loop();
3315 }
3316 
3317 // Create a CompilerThread
3318 CompilerThread::CompilerThread(CompileQueue* queue,
3319                                CompilerCounters* counters)
3320                                : JavaThread(&compiler_thread_entry) {
3321   _env   = NULL;
3322   _log   = NULL;
3323   _task  = NULL;
3324   _queue = queue;
3325   _counters = counters;
3326   _buffer_blob = NULL;
3327   _compiler = NULL;
3328 
3329   // Compiler uses resource area for compilation, let's bias it to mtCompiler
3330   resource_area()->bias_to(mtCompiler);
3331 
3332 #ifndef PRODUCT
3333   _ideal_graph_printer = NULL;
3334 #endif
3335 }
3336 
3337 CompilerThread::~CompilerThread() {
3338   // Delete objects which were allocated on heap.
3339   delete _counters;
3340 }
3341 
3342 bool CompilerThread::can_call_java() const {
3343   return _compiler != NULL && _compiler->is_jvmci();
3344 }
3345 
3346 // Create sweeper thread
3347 CodeCacheSweeperThread::CodeCacheSweeperThread()
3348 : JavaThread(&sweeper_thread_entry) {
3349   _scanned_compiled_method = NULL;
3350 }
3351 
3352 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3353   JavaThread::oops_do(f, cf);
3354   if (_scanned_compiled_method != NULL && cf != NULL) {
3355     // Safepoints can occur when the sweeper is scanning an nmethod so
3356     // process it here to make sure it isn't unloaded in the middle of
3357     // a scan.
3358     cf->do_code_blob(_scanned_compiled_method);
3359   }
3360 }
3361 
3362 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3363   JavaThread::nmethods_do(cf);
3364   if (_scanned_compiled_method != NULL && cf != NULL) {
3365     // Safepoints can occur when the sweeper is scanning an nmethod so
3366     // process it here to make sure it isn't unloaded in the middle of
3367     // a scan.
3368     cf->do_code_blob(_scanned_compiled_method);
3369   }
3370 }
3371 
3372 
3373 // ======= Threads ========
3374 
3375 // The Threads class links together all active threads, and provides
3376 // operations over all threads. It is protected by the Threads_lock,
3377 // which is also used in other global contexts like safepointing.
3378 // ThreadsListHandles are used to safely perform operations on one
3379 // or more threads without the risk of the thread exiting during the
3380 // operation.
3381 //
3382 // Note: The Threads_lock is currently more widely used than we
3383 // would like. We are actively migrating Threads_lock uses to other
3384 // mechanisms in order to reduce Threads_lock contention.
3385 
3386 JavaThread* Threads::_thread_list = NULL;
3387 int         Threads::_number_of_threads = 0;
3388 int         Threads::_number_of_non_daemon_threads = 0;
3389 int         Threads::_return_code = 0;
3390 int         Threads::_thread_claim_parity = 0;
3391 size_t      JavaThread::_stack_size_at_create = 0;
3392 
3393 #ifdef ASSERT
3394 bool        Threads::_vm_complete = false;
3395 size_t      Threads::_threads_before_barrier_set = 0;
3396 #endif
3397 
3398 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
3399   Prefetch::read((void*)addr, prefetch_interval);
3400   return *addr;
3401 }
3402 
3403 // Possibly the ugliest for loop the world has seen. C++ does not allow
3404 // multiple types in the declaration section of the for loop. In this case
3405 // we are only dealing with pointers and hence can cast them. It looks ugly
3406 // but macros are ugly and therefore it's fine to make things absurdly ugly.
3407 #define DO_JAVA_THREADS(LIST, X)                                                                                          \
3408     for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes,                           \
3409              *MACRO_list = (JavaThread*)(LIST),                                                                           \
3410              **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(),  \
3411              **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(),                                     \
3412              *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval);                 \
3413          MACRO_current_p != MACRO_end;                                                                                    \
3414          MACRO_current_p++,                                                                                               \
3415              X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval))
3416 
3417 // All JavaThreads
3418 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X)
3419 
3420 // All NonJavaThreads (i.e., every non-JavaThread in the system).
3421 void Threads::non_java_threads_do(ThreadClosure* tc) {
3422   NoSafepointVerifier nsv(!SafepointSynchronize::is_at_safepoint(), false);
3423   for (NonJavaThread::Iterator njti; !njti.end(); njti.step()) {
3424     tc->do_thread(njti.current());
3425   }
3426 }
3427 
3428 // All JavaThreads
3429 void Threads::java_threads_do(ThreadClosure* tc) {
3430   assert_locked_or_safepoint(Threads_lock);
3431   // ALL_JAVA_THREADS iterates through all JavaThreads.
3432   ALL_JAVA_THREADS(p) {
3433     tc->do_thread(p);
3434   }
3435 }
3436 
3437 void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) {
3438   assert_locked_or_safepoint(Threads_lock);
3439   java_threads_do(tc);
3440   tc->do_thread(VMThread::vm_thread());
3441 }
3442 
3443 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system).
3444 void Threads::threads_do(ThreadClosure* tc) {
3445   assert_locked_or_safepoint(Threads_lock);
3446   java_threads_do(tc);
3447   non_java_threads_do(tc);
3448 }
3449 
3450 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
3451   int cp = Threads::thread_claim_parity();
3452   ALL_JAVA_THREADS(p) {
3453     if (p->claim_oops_do(is_par, cp)) {
3454       tc->do_thread(p);
3455     }
3456   }
3457   VMThread* vmt = VMThread::vm_thread();
3458   if (vmt->claim_oops_do(is_par, cp)) {
3459     tc->do_thread(vmt);
3460   }
3461 }
3462 
3463 // The system initialization in the library has three phases.
3464 //
3465 // Phase 1: java.lang.System class initialization
3466 //     java.lang.System is a primordial class loaded and initialized
3467 //     by the VM early during startup.  java.lang.System.<clinit>
3468 //     only does registerNatives and keeps the rest of the class
3469 //     initialization work later until thread initialization completes.
3470 //
3471 //     System.initPhase1 initializes the system properties, the static
3472 //     fields in, out, and err. Set up java signal handlers, OS-specific
3473 //     system settings, and thread group of the main thread.
3474 static void call_initPhase1(TRAPS) {
3475   Klass* klass =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3476   JavaValue result(T_VOID);
3477   JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3478                                          vmSymbols::void_method_signature(), CHECK);
3479 }
3480 
3481 // Phase 2. Module system initialization
3482 //     This will initialize the module system.  Only java.base classes
3483 //     can be loaded until phase 2 completes.
3484 //
3485 //     Call System.initPhase2 after the compiler initialization and jsr292
3486 //     classes get initialized because module initialization runs a lot of java
3487 //     code, that for performance reasons, should be compiled.  Also, this will
3488 //     enable the startup code to use lambda and other language features in this
3489 //     phase and onward.
3490 //
3491 //     After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3492 static void call_initPhase2(TRAPS) {
3493   TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3494 
3495   Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3496 
3497   JavaValue result(T_INT);
3498   JavaCallArguments args;
3499   args.push_int(DisplayVMOutputToStderr);
3500   args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3501   JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3502                                          vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3503   if (result.get_jint() != JNI_OK) {
3504     vm_exit_during_initialization(); // no message or exception
3505   }
3506 
3507   universe_post_module_init();
3508 }
3509 
3510 // Phase 3. final setup - set security manager, system class loader and TCCL
3511 //
3512 //     This will instantiate and set the security manager, set the system class
3513 //     loader as well as the thread context class loader.  The security manager
3514 //     and system class loader may be a custom class loaded from -Xbootclasspath/a,
3515 //     other modules or the application's classpath.
3516 static void call_initPhase3(TRAPS) {
3517   Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3518   JavaValue result(T_VOID);
3519   JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3520                                          vmSymbols::void_method_signature(), CHECK);
3521 }
3522 
3523 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3524   TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3525 
3526   if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3527     create_vm_init_libraries();
3528   }
3529 
3530   initialize_class(vmSymbols::java_lang_String(), CHECK);
3531 
3532   // Inject CompactStrings value after the static initializers for String ran.
3533   java_lang_String::set_compact_strings(CompactStrings);
3534 
3535   // Initialize java_lang.System (needed before creating the thread)
3536   initialize_class(vmSymbols::java_lang_System(), CHECK);
3537   // The VM creates & returns objects of this class. Make sure it's initialized.
3538   initialize_class(vmSymbols::java_lang_Class(), CHECK);
3539   initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3540   Handle thread_group = create_initial_thread_group(CHECK);
3541   Universe::set_main_thread_group(thread_group());
3542   initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3543   oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3544   main_thread->set_threadObj(thread_object);
3545   // Set thread status to running since main thread has
3546   // been started and running.
3547   java_lang_Thread::set_thread_status(thread_object,
3548                                       java_lang_Thread::RUNNABLE);
3549 
3550   // The VM creates objects of this class.
3551   initialize_class(vmSymbols::java_lang_Module(), CHECK);
3552 
3553   // The VM preresolves methods to these classes. Make sure that they get initialized
3554   initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3555   initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3556 
3557   // Phase 1 of the system initialization in the library, java.lang.System class initialization
3558   call_initPhase1(CHECK);
3559 
3560   // get the Java runtime name after java.lang.System is initialized
3561   JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3562   JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3563 
3564   // an instance of OutOfMemory exception has been allocated earlier
3565   initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3566   initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3567   initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3568   initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3569   initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3570   initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3571   initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3572   initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3573 }
3574 
3575 void Threads::initialize_jsr292_core_classes(TRAPS) {
3576   TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3577 
3578   initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3579   initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3580   initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3581   initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3582 }
3583 
3584 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3585   extern void JDK_Version_init();
3586 
3587   // Preinitialize version info.
3588   VM_Version::early_initialize();
3589 
3590   // Check version
3591   if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3592 
3593   // Initialize library-based TLS
3594   ThreadLocalStorage::init();
3595 
3596   // Initialize the output stream module
3597   ostream_init();
3598 
3599   // Process java launcher properties.
3600   Arguments::process_sun_java_launcher_properties(args);
3601 
3602   // Initialize the os module
3603   os::init();
3604 
3605   // Record VM creation timing statistics
3606   TraceVmCreationTime create_vm_timer;
3607   create_vm_timer.start();
3608 
3609   // Initialize system properties.
3610   Arguments::init_system_properties();
3611 
3612   // So that JDK version can be used as a discriminator when parsing arguments
3613   JDK_Version_init();
3614 
3615   // Update/Initialize System properties after JDK version number is known
3616   Arguments::init_version_specific_system_properties();
3617 
3618   // Make sure to initialize log configuration *before* parsing arguments
3619   LogConfiguration::initialize(create_vm_timer.begin_time());
3620 
3621   // Parse arguments
3622   // Note: this internally calls os::init_container_support()
3623   jint parse_result = Arguments::parse(args);
3624   if (parse_result != JNI_OK) return parse_result;
3625 
3626   os::init_before_ergo();
3627 
3628   jint ergo_result = Arguments::apply_ergo();
3629   if (ergo_result != JNI_OK) return ergo_result;
3630 
3631   // Final check of all ranges after ergonomics which may change values.
3632   if (!JVMFlagRangeList::check_ranges()) {
3633     return JNI_EINVAL;
3634   }
3635 
3636   // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3637   bool constraint_result = JVMFlagConstraintList::check_constraints(JVMFlagConstraint::AfterErgo);
3638   if (!constraint_result) {
3639     return JNI_EINVAL;
3640   }
3641 
3642   JVMFlagWriteableList::mark_startup();
3643 
3644   if (PauseAtStartup) {
3645     os::pause();
3646   }
3647 
3648   HOTSPOT_VM_INIT_BEGIN();
3649 
3650   // Timing (must come after argument parsing)
3651   TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3652 
3653 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT
3654   // Initialize assert poison page mechanism.
3655   if (ShowRegistersOnAssert) {
3656     initialize_assert_poison();
3657   }
3658 #endif // CAN_SHOW_REGISTERS_ON_ASSERT
3659 
3660   // Initialize the os module after parsing the args
3661   jint os_init_2_result = os::init_2();
3662   if (os_init_2_result != JNI_OK) return os_init_2_result;
3663 
3664   SafepointMechanism::initialize();
3665 
3666   jint adjust_after_os_result = Arguments::adjust_after_os();
3667   if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3668 
3669   // Initialize output stream logging
3670   ostream_init_log();
3671 
3672   // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3673   // Must be before create_vm_init_agents()
3674   if (Arguments::init_libraries_at_startup()) {
3675     convert_vm_init_libraries_to_agents();
3676   }
3677 
3678   // Launch -agentlib/-agentpath and converted -Xrun agents
3679   if (Arguments::init_agents_at_startup()) {
3680     create_vm_init_agents();
3681   }
3682 
3683   // Initialize Threads state
3684   _thread_list = NULL;
3685   _number_of_threads = 0;
3686   _number_of_non_daemon_threads = 0;
3687 
3688   // Initialize global data structures and create system classes in heap
3689   vm_init_globals();
3690 
3691 #if INCLUDE_JVMCI
3692   if (JVMCICounterSize > 0) {
3693     JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3694     memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3695   } else {
3696     JavaThread::_jvmci_old_thread_counters = NULL;
3697   }
3698 #endif // INCLUDE_JVMCI
3699 
3700   // Attach the main thread to this os thread
3701   JavaThread* main_thread = new JavaThread();
3702   main_thread->set_thread_state(_thread_in_vm);
3703   main_thread->initialize_thread_current();
3704   // must do this before set_active_handles
3705   main_thread->record_stack_base_and_size();
3706   main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3707 
3708   if (!main_thread->set_as_starting_thread()) {
3709     vm_shutdown_during_initialization(
3710                                       "Failed necessary internal allocation. Out of swap space");
3711     main_thread->smr_delete();
3712     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3713     return JNI_ENOMEM;
3714   }
3715 
3716   // Enable guard page *after* os::create_main_thread(), otherwise it would
3717   // crash Linux VM, see notes in os_linux.cpp.
3718   main_thread->create_stack_guard_pages();
3719 
3720   // Initialize Java-Level synchronization subsystem
3721   ObjectMonitor::Initialize();
3722 
3723   // Initialize global modules
3724   jint status = init_globals();
3725   if (status != JNI_OK) {
3726     main_thread->smr_delete();
3727     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3728     return status;
3729   }
3730 
3731   JFR_ONLY(Jfr::on_vm_init();)
3732 
3733   // Should be done after the heap is fully created
3734   main_thread->cache_global_variables();
3735 
3736   HandleMark hm;
3737 
3738   { MutexLocker mu(Threads_lock);
3739     Threads::add(main_thread);
3740   }
3741 
3742   // Any JVMTI raw monitors entered in onload will transition into
3743   // real raw monitor. VM is setup enough here for raw monitor enter.
3744   JvmtiExport::transition_pending_onload_raw_monitors();
3745 
3746   // Create the VMThread
3747   { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3748 
3749   VMThread::create();
3750     Thread* vmthread = VMThread::vm_thread();
3751 
3752     if (!os::create_thread(vmthread, os::vm_thread)) {
3753       vm_exit_during_initialization("Cannot create VM thread. "
3754                                     "Out of system resources.");
3755     }
3756 
3757     // Wait for the VM thread to become ready, and VMThread::run to initialize
3758     // Monitors can have spurious returns, must always check another state flag
3759     {
3760       MutexLocker ml(Notify_lock);
3761       os::start_thread(vmthread);
3762       while (vmthread->active_handles() == NULL) {
3763         Notify_lock->wait();
3764       }
3765     }
3766   }
3767 
3768   assert(Universe::is_fully_initialized(), "not initialized");
3769   if (VerifyDuringStartup) {
3770     // Make sure we're starting with a clean slate.
3771     VM_Verify verify_op;
3772     VMThread::execute(&verify_op);
3773   }
3774 
3775   // We need this to update the java.vm.info property in case any flags used
3776   // to initially define it have been changed. This is needed for both CDS and
3777   // AOT, since UseSharedSpaces and UseAOT may be changed after java.vm.info
3778   // is initially computed. See Abstract_VM_Version::vm_info_string().
3779   // This update must happen before we initialize the java classes, but
3780   // after any initialization logic that might modify the flags.
3781   Arguments::update_vm_info_property(VM_Version::vm_info_string());
3782 
3783   Thread* THREAD = Thread::current();
3784 
3785   // Always call even when there are not JVMTI environments yet, since environments
3786   // may be attached late and JVMTI must track phases of VM execution
3787   JvmtiExport::enter_early_start_phase();
3788 
3789   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3790   JvmtiExport::post_early_vm_start();
3791 
3792   initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3793 
3794   quicken_jni_functions();
3795 
3796   // No more stub generation allowed after that point.
3797   StubCodeDesc::freeze();
3798 
3799   // Set flag that basic initialization has completed. Used by exceptions and various
3800   // debug stuff, that does not work until all basic classes have been initialized.
3801   set_init_completed();
3802 
3803   LogConfiguration::post_initialize();
3804   Metaspace::post_initialize();
3805 
3806   HOTSPOT_VM_INIT_END();
3807 
3808   // record VM initialization completion time
3809 #if INCLUDE_MANAGEMENT
3810   Management::record_vm_init_completed();
3811 #endif // INCLUDE_MANAGEMENT
3812 
3813   // Signal Dispatcher needs to be started before VMInit event is posted
3814   os::initialize_jdk_signal_support(CHECK_JNI_ERR);
3815 
3816   // Start Attach Listener if +StartAttachListener or it can't be started lazily
3817   if (!DisableAttachMechanism) {
3818     AttachListener::vm_start();
3819     if (StartAttachListener || AttachListener::init_at_startup()) {
3820       AttachListener::init();
3821     }
3822   }
3823 
3824   // Launch -Xrun agents
3825   // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3826   // back-end can launch with -Xdebug -Xrunjdwp.
3827   if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3828     create_vm_init_libraries();
3829   }
3830 
3831   if (CleanChunkPoolAsync) {
3832     Chunk::start_chunk_pool_cleaner_task();
3833   }
3834 
3835   // initialize compiler(s)
3836 #if defined(COMPILER1) || COMPILER2_OR_JVMCI
3837 #if INCLUDE_JVMCI
3838   bool force_JVMCI_intialization = false;
3839   if (EnableJVMCI) {
3840     // Initialize JVMCI eagerly when it is explicitly requested.
3841     // Or when JVMCIPrintProperties is enabled.
3842     // The JVMCI Java initialization code will read this flag and
3843     // do the printing if it's set.
3844     force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties;
3845 
3846     if (!force_JVMCI_intialization) {
3847       // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3848       // compilations via JVMCI will not actually block until JVMCI is initialized.
3849       force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3850     }
3851   }
3852 #endif
3853   CompileBroker::compilation_init_phase1(CHECK_JNI_ERR);
3854   // Postpone completion of compiler initialization to after JVMCI
3855   // is initialized to avoid timeouts of blocking compilations.
3856   if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) {
3857     CompileBroker::compilation_init_phase2();
3858   }
3859 #endif
3860 
3861   // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3862   // It is done after compilers are initialized, because otherwise compilations of
3863   // signature polymorphic MH intrinsics can be missed
3864   // (see SystemDictionary::find_method_handle_intrinsic).
3865   initialize_jsr292_core_classes(CHECK_JNI_ERR);
3866 
3867   // This will initialize the module system.  Only java.base classes can be
3868   // loaded until phase 2 completes
3869   call_initPhase2(CHECK_JNI_ERR);
3870 
3871   // Always call even when there are not JVMTI environments yet, since environments
3872   // may be attached late and JVMTI must track phases of VM execution
3873   JvmtiExport::enter_start_phase();
3874 
3875   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3876   JvmtiExport::post_vm_start();
3877 
3878   // Final system initialization including security manager and system class loader
3879   call_initPhase3(CHECK_JNI_ERR);
3880 
3881   // cache the system and platform class loaders
3882   SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
3883 
3884 #if INCLUDE_CDS
3885   if (DumpSharedSpaces) {
3886     // capture the module path info from the ModuleEntryTable
3887     ClassLoader::initialize_module_path(THREAD);
3888   }
3889 #endif
3890 
3891 #if INCLUDE_JVMCI
3892   if (force_JVMCI_intialization) {
3893     JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
3894     CompileBroker::compilation_init_phase2();
3895   }
3896 #endif
3897 
3898   // Always call even when there are not JVMTI environments yet, since environments
3899   // may be attached late and JVMTI must track phases of VM execution
3900   JvmtiExport::enter_live_phase();
3901 
3902   // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3903   JvmtiExport::post_vm_initialized();
3904 
3905   JFR_ONLY(Jfr::on_vm_start();)
3906 
3907 #if INCLUDE_MANAGEMENT
3908   Management::initialize(THREAD);
3909 
3910   if (HAS_PENDING_EXCEPTION) {
3911     // management agent fails to start possibly due to
3912     // configuration problem and is responsible for printing
3913     // stack trace if appropriate. Simply exit VM.
3914     vm_exit(1);
3915   }
3916 #endif // INCLUDE_MANAGEMENT
3917 
3918   if (MemProfiling)                   MemProfiler::engage();
3919   StatSampler::engage();
3920   if (CheckJNICalls)                  JniPeriodicChecker::engage();
3921 
3922   BiasedLocking::init();
3923 
3924 #if INCLUDE_RTM_OPT
3925   RTMLockingCounters::init();
3926 #endif
3927 
3928   if (JDK_Version::current().post_vm_init_hook_enabled()) {
3929     call_postVMInitHook(THREAD);
3930     // The Java side of PostVMInitHook.run must deal with all
3931     // exceptions and provide means of diagnosis.
3932     if (HAS_PENDING_EXCEPTION) {
3933       CLEAR_PENDING_EXCEPTION;
3934     }
3935   }
3936 
3937   {
3938     MutexLocker ml(PeriodicTask_lock);
3939     // Make sure the WatcherThread can be started by WatcherThread::start()
3940     // or by dynamic enrollment.
3941     WatcherThread::make_startable();
3942     // Start up the WatcherThread if there are any periodic tasks
3943     // NOTE:  All PeriodicTasks should be registered by now. If they
3944     //   aren't, late joiners might appear to start slowly (we might
3945     //   take a while to process their first tick).
3946     if (PeriodicTask::num_tasks() > 0) {
3947       WatcherThread::start();
3948     }
3949   }
3950 
3951   create_vm_timer.end();
3952 #ifdef ASSERT
3953   _vm_complete = true;
3954 #endif
3955 
3956   if (DumpSharedSpaces) {
3957     MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3958     ShouldNotReachHere();
3959   }
3960 
3961   return JNI_OK;
3962 }
3963 
3964 // type for the Agent_OnLoad and JVM_OnLoad entry points
3965 extern "C" {
3966   typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3967 }
3968 // Find a command line agent library and return its entry point for
3969 //         -agentlib:  -agentpath:   -Xrun
3970 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3971 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3972                                     const char *on_load_symbols[],
3973                                     size_t num_symbol_entries) {
3974   OnLoadEntry_t on_load_entry = NULL;
3975   void *library = NULL;
3976 
3977   if (!agent->valid()) {
3978     char buffer[JVM_MAXPATHLEN];
3979     char ebuf[1024] = "";
3980     const char *name = agent->name();
3981     const char *msg = "Could not find agent library ";
3982 
3983     // First check to see if agent is statically linked into executable
3984     if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3985       library = agent->os_lib();
3986     } else if (agent->is_absolute_path()) {
3987       library = os::dll_load(name, ebuf, sizeof ebuf);
3988       if (library == NULL) {
3989         const char *sub_msg = " in absolute path, with error: ";
3990         size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3991         char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3992         jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3993         // If we can't find the agent, exit.
3994         vm_exit_during_initialization(buf, NULL);
3995         FREE_C_HEAP_ARRAY(char, buf);
3996       }
3997     } else {
3998       // Try to load the agent from the standard dll directory
3999       if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
4000                              name)) {
4001         library = os::dll_load(buffer, ebuf, sizeof ebuf);
4002       }
4003       if (library == NULL) { // Try the library path directory.
4004         if (os::dll_build_name(buffer, sizeof(buffer), name)) {
4005           library = os::dll_load(buffer, ebuf, sizeof ebuf);
4006         }
4007         if (library == NULL) {
4008           const char *sub_msg = " on the library path, with error: ";
4009           const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image.";
4010 
4011           size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) +
4012                        strlen(ebuf) + strlen(sub_msg2) + 1;
4013           char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4014           if (!agent->is_instrument_lib()) {
4015             jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4016           } else {
4017             jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2);
4018           }
4019           // If we can't find the agent, exit.
4020           vm_exit_during_initialization(buf, NULL);
4021           FREE_C_HEAP_ARRAY(char, buf);
4022         }
4023       }
4024     }
4025     agent->set_os_lib(library);
4026     agent->set_valid();
4027   }
4028 
4029   // Find the OnLoad function.
4030   on_load_entry =
4031     CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
4032                                                           false,
4033                                                           on_load_symbols,
4034                                                           num_symbol_entries));
4035   return on_load_entry;
4036 }
4037 
4038 // Find the JVM_OnLoad entry point
4039 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
4040   const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
4041   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4042 }
4043 
4044 // Find the Agent_OnLoad entry point
4045 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
4046   const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
4047   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4048 }
4049 
4050 // For backwards compatibility with -Xrun
4051 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
4052 // treated like -agentpath:
4053 // Must be called before agent libraries are created
4054 void Threads::convert_vm_init_libraries_to_agents() {
4055   AgentLibrary* agent;
4056   AgentLibrary* next;
4057 
4058   for (agent = Arguments::libraries(); agent != NULL; agent = next) {
4059     next = agent->next();  // cache the next agent now as this agent may get moved off this list
4060     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4061 
4062     // If there is an JVM_OnLoad function it will get called later,
4063     // otherwise see if there is an Agent_OnLoad
4064     if (on_load_entry == NULL) {
4065       on_load_entry = lookup_agent_on_load(agent);
4066       if (on_load_entry != NULL) {
4067         // switch it to the agent list -- so that Agent_OnLoad will be called,
4068         // JVM_OnLoad won't be attempted and Agent_OnUnload will
4069         Arguments::convert_library_to_agent(agent);
4070       } else {
4071         vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
4072       }
4073     }
4074   }
4075 }
4076 
4077 // Create agents for -agentlib:  -agentpath:  and converted -Xrun
4078 // Invokes Agent_OnLoad
4079 // Called very early -- before JavaThreads exist
4080 void Threads::create_vm_init_agents() {
4081   extern struct JavaVM_ main_vm;
4082   AgentLibrary* agent;
4083 
4084   JvmtiExport::enter_onload_phase();
4085 
4086   for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4087     OnLoadEntry_t  on_load_entry = lookup_agent_on_load(agent);
4088 
4089     if (on_load_entry != NULL) {
4090       // Invoke the Agent_OnLoad function
4091       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4092       if (err != JNI_OK) {
4093         vm_exit_during_initialization("agent library failed to init", agent->name());
4094       }
4095     } else {
4096       vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4097     }
4098   }
4099   JvmtiExport::enter_primordial_phase();
4100 }
4101 
4102 extern "C" {
4103   typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4104 }
4105 
4106 void Threads::shutdown_vm_agents() {
4107   // Send any Agent_OnUnload notifications
4108   const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4109   size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4110   extern struct JavaVM_ main_vm;
4111   for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4112 
4113     // Find the Agent_OnUnload function.
4114     Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4115                                                    os::find_agent_function(agent,
4116                                                    false,
4117                                                    on_unload_symbols,
4118                                                    num_symbol_entries));
4119 
4120     // Invoke the Agent_OnUnload function
4121     if (unload_entry != NULL) {
4122       JavaThread* thread = JavaThread::current();
4123       ThreadToNativeFromVM ttn(thread);
4124       HandleMark hm(thread);
4125       (*unload_entry)(&main_vm);
4126     }
4127   }
4128 }
4129 
4130 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4131 // Invokes JVM_OnLoad
4132 void Threads::create_vm_init_libraries() {
4133   extern struct JavaVM_ main_vm;
4134   AgentLibrary* agent;
4135 
4136   for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4137     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4138 
4139     if (on_load_entry != NULL) {
4140       // Invoke the JVM_OnLoad function
4141       JavaThread* thread = JavaThread::current();
4142       ThreadToNativeFromVM ttn(thread);
4143       HandleMark hm(thread);
4144       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4145       if (err != JNI_OK) {
4146         vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4147       }
4148     } else {
4149       vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4150     }
4151   }
4152 }
4153 
4154 
4155 // Last thread running calls java.lang.Shutdown.shutdown()
4156 void JavaThread::invoke_shutdown_hooks() {
4157   HandleMark hm(this);
4158 
4159   // We could get here with a pending exception, if so clear it now.
4160   if (this->has_pending_exception()) {
4161     this->clear_pending_exception();
4162   }
4163 
4164   EXCEPTION_MARK;
4165   Klass* shutdown_klass =
4166     SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4167                                       THREAD);
4168   if (shutdown_klass != NULL) {
4169     // SystemDictionary::resolve_or_null will return null if there was
4170     // an exception.  If we cannot load the Shutdown class, just don't
4171     // call Shutdown.shutdown() at all.  This will mean the shutdown hooks
4172     // won't be run.  Note that if a shutdown hook was registered,
4173     // the Shutdown class would have already been loaded
4174     // (Runtime.addShutdownHook will load it).
4175     JavaValue result(T_VOID);
4176     JavaCalls::call_static(&result,
4177                            shutdown_klass,
4178                            vmSymbols::shutdown_method_name(),
4179                            vmSymbols::void_method_signature(),
4180                            THREAD);
4181   }
4182   CLEAR_PENDING_EXCEPTION;
4183 }
4184 
4185 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4186 // the program falls off the end of main(). Another VM exit path is through
4187 // vm_exit() when the program calls System.exit() to return a value or when
4188 // there is a serious error in VM. The two shutdown paths are not exactly
4189 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4190 // and VM_Exit op at VM level.
4191 //
4192 // Shutdown sequence:
4193 //   + Shutdown native memory tracking if it is on
4194 //   + Wait until we are the last non-daemon thread to execute
4195 //     <-- every thing is still working at this moment -->
4196 //   + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4197 //        shutdown hooks
4198 //   + Call before_exit(), prepare for VM exit
4199 //      > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4200 //        currently the only user of this mechanism is File.deleteOnExit())
4201 //      > stop StatSampler, watcher thread, CMS threads,
4202 //        post thread end and vm death events to JVMTI,
4203 //        stop signal thread
4204 //   + Call JavaThread::exit(), it will:
4205 //      > release JNI handle blocks, remove stack guard pages
4206 //      > remove this thread from Threads list
4207 //     <-- no more Java code from this thread after this point -->
4208 //   + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4209 //     the compiler threads at safepoint
4210 //     <-- do not use anything that could get blocked by Safepoint -->
4211 //   + Disable tracing at JNI/JVM barriers
4212 //   + Set _vm_exited flag for threads that are still running native code
4213 //   + Call exit_globals()
4214 //      > deletes tty
4215 //      > deletes PerfMemory resources
4216 //   + Delete this thread
4217 //   + Return to caller
4218 
4219 bool Threads::destroy_vm() {
4220   JavaThread* thread = JavaThread::current();
4221 
4222 #ifdef ASSERT
4223   _vm_complete = false;
4224 #endif
4225   // Wait until we are the last non-daemon thread to execute
4226   { MutexLocker nu(Threads_lock);
4227     while (Threads::number_of_non_daemon_threads() > 1)
4228       // This wait should make safepoint checks, wait without a timeout,
4229       // and wait as a suspend-equivalent condition.
4230       Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4231                          Mutex::_as_suspend_equivalent_flag);
4232   }
4233 
4234   EventShutdown e;
4235   if (e.should_commit()) {
4236     e.set_reason("No remaining non-daemon Java threads");
4237     e.commit();
4238   }
4239 
4240   // Hang forever on exit if we are reporting an error.
4241   if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4242     os::infinite_sleep();
4243   }
4244   os::wait_for_keypress_at_exit();
4245 
4246   // run Java level shutdown hooks
4247   thread->invoke_shutdown_hooks();
4248 
4249   before_exit(thread);
4250 
4251   thread->exit(true);
4252   // thread will never call smr_delete, instead of implicit cancel
4253   // in wait_for_vm_thread_exit we do it explicit.
4254   thread->cancel_handshake();
4255 
4256   // Stop VM thread.
4257   {
4258     // 4945125 The vm thread comes to a safepoint during exit.
4259     // GC vm_operations can get caught at the safepoint, and the
4260     // heap is unparseable if they are caught. Grab the Heap_lock
4261     // to prevent this. The GC vm_operations will not be able to
4262     // queue until after the vm thread is dead. After this point,
4263     // we'll never emerge out of the safepoint before the VM exits.
4264 
4265     MutexLocker ml(Heap_lock);
4266 
4267     VMThread::wait_for_vm_thread_exit();
4268     assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4269     VMThread::destroy();
4270   }
4271 
4272   // Now, all Java threads are gone except daemon threads. Daemon threads
4273   // running Java code or in VM are stopped by the Safepoint. However,
4274   // daemon threads executing native code are still running.  But they
4275   // will be stopped at native=>Java/VM barriers. Note that we can't
4276   // simply kill or suspend them, as it is inherently deadlock-prone.
4277 
4278   VM_Exit::set_vm_exited();
4279 
4280   // Clean up ideal graph printers after the VMThread has started
4281   // the final safepoint which will block all the Compiler threads.
4282   // Note that this Thread has already logically exited so the
4283   // clean_up() function's use of a JavaThreadIteratorWithHandle
4284   // would be a problem except set_vm_exited() has remembered the
4285   // shutdown thread which is granted a policy exception.
4286 #if defined(COMPILER2) && !defined(PRODUCT)
4287   IdealGraphPrinter::clean_up();
4288 #endif
4289 
4290   notify_vm_shutdown();
4291 
4292   // exit_globals() will delete tty
4293   exit_globals();
4294 
4295   // We are after VM_Exit::set_vm_exited() so we can't call
4296   // thread->smr_delete() or we will block on the Threads_lock.
4297   // Deleting the shutdown thread here is safe because another
4298   // JavaThread cannot have an active ThreadsListHandle for
4299   // this JavaThread.
4300   delete thread;
4301 
4302 #if INCLUDE_JVMCI
4303   if (JVMCICounterSize > 0) {
4304     FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4305   }
4306 #endif
4307 
4308   LogConfiguration::finalize();
4309 
4310   return true;
4311 }
4312 
4313 
4314 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4315   if (version == JNI_VERSION_1_1) return JNI_TRUE;
4316   return is_supported_jni_version(version);
4317 }
4318 
4319 
4320 jboolean Threads::is_supported_jni_version(jint version) {
4321   if (version == JNI_VERSION_1_2) return JNI_TRUE;
4322   if (version == JNI_VERSION_1_4) return JNI_TRUE;
4323   if (version == JNI_VERSION_1_6) return JNI_TRUE;
4324   if (version == JNI_VERSION_1_8) return JNI_TRUE;
4325   if (version == JNI_VERSION_9) return JNI_TRUE;
4326   if (version == JNI_VERSION_10) return JNI_TRUE;
4327   return JNI_FALSE;
4328 }
4329 
4330 
4331 void Threads::add(JavaThread* p, bool force_daemon) {
4332   // The threads lock must be owned at this point
4333   assert_locked_or_safepoint(Threads_lock);
4334 
4335   BarrierSet::barrier_set()->on_thread_attach(p);
4336 
4337   p->set_next(_thread_list);
4338   _thread_list = p;
4339 
4340   // Once a JavaThread is added to the Threads list, smr_delete() has
4341   // to be used to delete it. Otherwise we can just delete it directly.
4342   p->set_on_thread_list();
4343 
4344   _number_of_threads++;
4345   oop threadObj = p->threadObj();
4346   bool daemon = true;
4347   // Bootstrapping problem: threadObj can be null for initial
4348   // JavaThread (or for threads attached via JNI)
4349   if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4350     _number_of_non_daemon_threads++;
4351     daemon = false;
4352   }
4353 
4354   ThreadService::add_thread(p, daemon);
4355 
4356   // Maintain fast thread list
4357   ThreadsSMRSupport::add_thread(p);
4358 
4359   // Possible GC point.
4360   Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4361 }
4362 
4363 void Threads::remove(JavaThread* p) {
4364 
4365   // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread.
4366   ObjectSynchronizer::omFlush(p);
4367 
4368   // Extra scope needed for Thread_lock, so we can check
4369   // that we do not remove thread without safepoint code notice
4370   { MutexLocker ml(Threads_lock);
4371 
4372     assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present");
4373 
4374     // Maintain fast thread list
4375     ThreadsSMRSupport::remove_thread(p);
4376 
4377     JavaThread* current = _thread_list;
4378     JavaThread* prev    = NULL;
4379 
4380     while (current != p) {
4381       prev    = current;
4382       current = current->next();
4383     }
4384 
4385     if (prev) {
4386       prev->set_next(current->next());
4387     } else {
4388       _thread_list = p->next();
4389     }
4390 
4391     _number_of_threads--;
4392     oop threadObj = p->threadObj();
4393     bool daemon = true;
4394     if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4395       _number_of_non_daemon_threads--;
4396       daemon = false;
4397 
4398       // Only one thread left, do a notify on the Threads_lock so a thread waiting
4399       // on destroy_vm will wake up.
4400       if (number_of_non_daemon_threads() == 1) {
4401         Threads_lock->notify_all();
4402       }
4403     }
4404     ThreadService::remove_thread(p, daemon);
4405 
4406     // Make sure that safepoint code disregard this thread. This is needed since
4407     // the thread might mess around with locks after this point. This can cause it
4408     // to do callbacks into the safepoint code. However, the safepoint code is not aware
4409     // of this thread since it is removed from the queue.
4410     p->set_terminated_value();
4411   } // unlock Threads_lock
4412 
4413   // Since Events::log uses a lock, we grab it outside the Threads_lock
4414   Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4415 }
4416 
4417 // Operations on the Threads list for GC.  These are not explicitly locked,
4418 // but the garbage collector must provide a safe context for them to run.
4419 // In particular, these things should never be called when the Threads_lock
4420 // is held by some other thread. (Note: the Safepoint abstraction also
4421 // uses the Threads_lock to guarantee this property. It also makes sure that
4422 // all threads gets blocked when exiting or starting).
4423 
4424 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4425   ALL_JAVA_THREADS(p) {
4426     p->oops_do(f, cf);
4427   }
4428   VMThread::vm_thread()->oops_do(f, cf);
4429 }
4430 
4431 void Threads::change_thread_claim_parity() {
4432   // Set the new claim parity.
4433   assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4434          "Not in range.");
4435   _thread_claim_parity++;
4436   if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4437   assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4438          "Not in range.");
4439 }
4440 
4441 #ifdef ASSERT
4442 void Threads::assert_all_threads_claimed() {
4443   ALL_JAVA_THREADS(p) {
4444     const int thread_parity = p->oops_do_parity();
4445     assert((thread_parity == _thread_claim_parity),
4446            "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4447   }
4448   VMThread* vmt = VMThread::vm_thread();
4449   const int thread_parity = vmt->oops_do_parity();
4450   assert((thread_parity == _thread_claim_parity),
4451          "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity);
4452 }
4453 #endif // ASSERT
4454 
4455 class ParallelOopsDoThreadClosure : public ThreadClosure {
4456 private:
4457   OopClosure* _f;
4458   CodeBlobClosure* _cf;
4459 public:
4460   ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {}
4461   void do_thread(Thread* t) {
4462     t->oops_do(_f, _cf);
4463   }
4464 };
4465 
4466 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4467   ParallelOopsDoThreadClosure tc(f, cf);
4468   possibly_parallel_threads_do(is_par, &tc);
4469 }
4470 
4471 void Threads::nmethods_do(CodeBlobClosure* cf) {
4472   ALL_JAVA_THREADS(p) {
4473     // This is used by the code cache sweeper to mark nmethods that are active
4474     // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4475     // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4476     if(!p->is_Code_cache_sweeper_thread()) {
4477       p->nmethods_do(cf);
4478     }
4479   }
4480 }
4481 
4482 void Threads::metadata_do(void f(Metadata*)) {
4483   ALL_JAVA_THREADS(p) {
4484     p->metadata_do(f);
4485   }
4486 }
4487 
4488 class ThreadHandlesClosure : public ThreadClosure {
4489   void (*_f)(Metadata*);
4490  public:
4491   ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4492   virtual void do_thread(Thread* thread) {
4493     thread->metadata_handles_do(_f);
4494   }
4495 };
4496 
4497 void Threads::metadata_handles_do(void f(Metadata*)) {
4498   // Only walk the Handles in Thread.
4499   ThreadHandlesClosure handles_closure(f);
4500   threads_do(&handles_closure);
4501 }
4502 
4503 void Threads::deoptimized_wrt_marked_nmethods() {
4504   ALL_JAVA_THREADS(p) {
4505     p->deoptimized_wrt_marked_nmethods();
4506   }
4507 }
4508 
4509 
4510 // Get count Java threads that are waiting to enter the specified monitor.
4511 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
4512                                                          int count,
4513                                                          address monitor) {
4514   GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4515 
4516   int i = 0;
4517   DO_JAVA_THREADS(t_list, p) {
4518     if (!p->can_call_java()) continue;
4519 
4520     address pending = (address)p->current_pending_monitor();
4521     if (pending == monitor) {             // found a match
4522       if (i < count) result->append(p);   // save the first count matches
4523       i++;
4524     }
4525   }
4526 
4527   return result;
4528 }
4529 
4530 
4531 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
4532                                                       address owner) {
4533   // NULL owner means not locked so we can skip the search
4534   if (owner == NULL) return NULL;
4535 
4536   DO_JAVA_THREADS(t_list, p) {
4537     // first, see if owner is the address of a Java thread
4538     if (owner == (address)p) return p;
4539   }
4540 
4541   // Cannot assert on lack of success here since this function may be
4542   // used by code that is trying to report useful problem information
4543   // like deadlock detection.
4544   if (UseHeavyMonitors) return NULL;
4545 
4546   // If we didn't find a matching Java thread and we didn't force use of
4547   // heavyweight monitors, then the owner is the stack address of the
4548   // Lock Word in the owning Java thread's stack.
4549   //
4550   JavaThread* the_owner = NULL;
4551   DO_JAVA_THREADS(t_list, q) {
4552     if (q->is_lock_owned(owner)) {
4553       the_owner = q;
4554       break;
4555     }
4556   }
4557 
4558   // cannot assert on lack of success here; see above comment
4559   return the_owner;
4560 }
4561 
4562 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4563 void Threads::print_on(outputStream* st, bool print_stacks,
4564                        bool internal_format, bool print_concurrent_locks,
4565                        bool print_extended_info) {
4566   char buf[32];
4567   st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4568 
4569   st->print_cr("Full thread dump %s (%s %s):",
4570                Abstract_VM_Version::vm_name(),
4571                Abstract_VM_Version::vm_release(),
4572                Abstract_VM_Version::vm_info_string());
4573   st->cr();
4574 
4575 #if INCLUDE_SERVICES
4576   // Dump concurrent locks
4577   ConcurrentLocksDump concurrent_locks;
4578   if (print_concurrent_locks) {
4579     concurrent_locks.dump_at_safepoint();
4580   }
4581 #endif // INCLUDE_SERVICES
4582 
4583   ThreadsSMRSupport::print_info_on(st);
4584   st->cr();
4585 
4586   ALL_JAVA_THREADS(p) {
4587     ResourceMark rm;
4588     p->print_on(st, print_extended_info);
4589     if (print_stacks) {
4590       if (internal_format) {
4591         p->trace_stack();
4592       } else {
4593         p->print_stack_on(st);
4594       }
4595     }
4596     st->cr();
4597 #if INCLUDE_SERVICES
4598     if (print_concurrent_locks) {
4599       concurrent_locks.print_locks_on(p, st);
4600     }
4601 #endif // INCLUDE_SERVICES
4602   }
4603 
4604   VMThread::vm_thread()->print_on(st);
4605   st->cr();
4606   Universe::heap()->print_gc_threads_on(st);
4607   WatcherThread* wt = WatcherThread::watcher_thread();
4608   if (wt != NULL) {
4609     wt->print_on(st);
4610     st->cr();
4611   }
4612 
4613   st->flush();
4614 }
4615 
4616 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4617                              int buflen, bool* found_current) {
4618   if (this_thread != NULL) {
4619     bool is_current = (current == this_thread);
4620     *found_current = *found_current || is_current;
4621     st->print("%s", is_current ? "=>" : "  ");
4622 
4623     st->print(PTR_FORMAT, p2i(this_thread));
4624     st->print(" ");
4625     this_thread->print_on_error(st, buf, buflen);
4626     st->cr();
4627   }
4628 }
4629 
4630 class PrintOnErrorClosure : public ThreadClosure {
4631   outputStream* _st;
4632   Thread* _current;
4633   char* _buf;
4634   int _buflen;
4635   bool* _found_current;
4636  public:
4637   PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4638                       int buflen, bool* found_current) :
4639    _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4640 
4641   virtual void do_thread(Thread* thread) {
4642     Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4643   }
4644 };
4645 
4646 // Threads::print_on_error() is called by fatal error handler. It's possible
4647 // that VM is not at safepoint and/or current thread is inside signal handler.
4648 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4649 // memory (even in resource area), it might deadlock the error handler.
4650 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4651                              int buflen) {
4652   ThreadsSMRSupport::print_info_on(st);
4653   st->cr();
4654 
4655   bool found_current = false;
4656   st->print_cr("Java Threads: ( => current thread )");
4657   ALL_JAVA_THREADS(thread) {
4658     print_on_error(thread, st, current, buf, buflen, &found_current);
4659   }
4660   st->cr();
4661 
4662   st->print_cr("Other Threads:");
4663   print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4664   print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4665 
4666   PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4667   Universe::heap()->gc_threads_do(&print_closure);
4668 
4669   if (!found_current) {
4670     st->cr();
4671     st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4672     current->print_on_error(st, buf, buflen);
4673     st->cr();
4674   }
4675   st->cr();
4676 
4677   st->print_cr("Threads with active compile tasks:");
4678   print_threads_compiling(st, buf, buflen);
4679 }
4680 
4681 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4682   ALL_JAVA_THREADS(thread) {
4683     if (thread->is_Compiler_thread()) {
4684       CompilerThread* ct = (CompilerThread*) thread;
4685 
4686       // Keep task in local variable for NULL check.
4687       // ct->_task might be set to NULL by concurring compiler thread
4688       // because it completed the compilation. The task is never freed,
4689       // though, just returned to a free list.
4690       CompileTask* task = ct->task();
4691       if (task != NULL) {
4692         thread->print_name_on_error(st, buf, buflen);
4693         task->print(st, NULL, true, true);
4694       }
4695     }
4696   }
4697 }
4698 
4699 
4700 // Internal SpinLock and Mutex
4701 // Based on ParkEvent
4702 
4703 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4704 //
4705 // We employ SpinLocks _only for low-contention, fixed-length
4706 // short-duration critical sections where we're concerned
4707 // about native mutex_t or HotSpot Mutex:: latency.
4708 // The mux construct provides a spin-then-block mutual exclusion
4709 // mechanism.
4710 //
4711 // Testing has shown that contention on the ListLock guarding gFreeList
4712 // is common.  If we implement ListLock as a simple SpinLock it's common
4713 // for the JVM to devolve to yielding with little progress.  This is true
4714 // despite the fact that the critical sections protected by ListLock are
4715 // extremely short.
4716 //
4717 // TODO-FIXME: ListLock should be of type SpinLock.
4718 // We should make this a 1st-class type, integrated into the lock
4719 // hierarchy as leaf-locks.  Critically, the SpinLock structure
4720 // should have sufficient padding to avoid false-sharing and excessive
4721 // cache-coherency traffic.
4722 
4723 
4724 typedef volatile int SpinLockT;
4725 
4726 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4727   if (Atomic::cmpxchg (1, adr, 0) == 0) {
4728     return;   // normal fast-path return
4729   }
4730 
4731   // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4732   int ctr = 0;
4733   int Yields = 0;
4734   for (;;) {
4735     while (*adr != 0) {
4736       ++ctr;
4737       if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4738         if (Yields > 5) {
4739           os::naked_short_sleep(1);
4740         } else {
4741           os::naked_yield();
4742           ++Yields;
4743         }
4744       } else {
4745         SpinPause();
4746       }
4747     }
4748     if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4749   }
4750 }
4751 
4752 void Thread::SpinRelease(volatile int * adr) {
4753   assert(*adr != 0, "invariant");
4754   OrderAccess::fence();      // guarantee at least release consistency.
4755   // Roach-motel semantics.
4756   // It's safe if subsequent LDs and STs float "up" into the critical section,
4757   // but prior LDs and STs within the critical section can't be allowed
4758   // to reorder or float past the ST that releases the lock.
4759   // Loads and stores in the critical section - which appear in program
4760   // order before the store that releases the lock - must also appear
4761   // before the store that releases the lock in memory visibility order.
4762   // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4763   // the ST of 0 into the lock-word which releases the lock, so fence
4764   // more than covers this on all platforms.
4765   *adr = 0;
4766 }
4767 
4768 // muxAcquire and muxRelease:
4769 //
4770 // *  muxAcquire and muxRelease support a single-word lock-word construct.
4771 //    The LSB of the word is set IFF the lock is held.
4772 //    The remainder of the word points to the head of a singly-linked list
4773 //    of threads blocked on the lock.
4774 //
4775 // *  The current implementation of muxAcquire-muxRelease uses its own
4776 //    dedicated Thread._MuxEvent instance.  If we're interested in
4777 //    minimizing the peak number of extant ParkEvent instances then
4778 //    we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4779 //    as certain invariants were satisfied.  Specifically, care would need
4780 //    to be taken with regards to consuming unpark() "permits".
4781 //    A safe rule of thumb is that a thread would never call muxAcquire()
4782 //    if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4783 //    park().  Otherwise the _ParkEvent park() operation in muxAcquire() could
4784 //    consume an unpark() permit intended for monitorenter, for instance.
4785 //    One way around this would be to widen the restricted-range semaphore
4786 //    implemented in park().  Another alternative would be to provide
4787 //    multiple instances of the PlatformEvent() for each thread.  One
4788 //    instance would be dedicated to muxAcquire-muxRelease, for instance.
4789 //
4790 // *  Usage:
4791 //    -- Only as leaf locks
4792 //    -- for short-term locking only as muxAcquire does not perform
4793 //       thread state transitions.
4794 //
4795 // Alternatives:
4796 // *  We could implement muxAcquire and muxRelease with MCS or CLH locks
4797 //    but with parking or spin-then-park instead of pure spinning.
4798 // *  Use Taura-Oyama-Yonenzawa locks.
4799 // *  It's possible to construct a 1-0 lock if we encode the lockword as
4800 //    (List,LockByte).  Acquire will CAS the full lockword while Release
4801 //    will STB 0 into the LockByte.  The 1-0 scheme admits stranding, so
4802 //    acquiring threads use timers (ParkTimed) to detect and recover from
4803 //    the stranding window.  Thread/Node structures must be aligned on 256-byte
4804 //    boundaries by using placement-new.
4805 // *  Augment MCS with advisory back-link fields maintained with CAS().
4806 //    Pictorially:  LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4807 //    The validity of the backlinks must be ratified before we trust the value.
4808 //    If the backlinks are invalid the exiting thread must back-track through the
4809 //    the forward links, which are always trustworthy.
4810 // *  Add a successor indication.  The LockWord is currently encoded as
4811 //    (List, LOCKBIT:1).  We could also add a SUCCBIT or an explicit _succ variable
4812 //    to provide the usual futile-wakeup optimization.
4813 //    See RTStt for details.
4814 //
4815 
4816 
4817 const intptr_t LOCKBIT = 1;
4818 
4819 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4820   intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4821   if (w == 0) return;
4822   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4823     return;
4824   }
4825 
4826   ParkEvent * const Self = Thread::current()->_MuxEvent;
4827   assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4828   for (;;) {
4829     int its = (os::is_MP() ? 100 : 0) + 1;
4830 
4831     // Optional spin phase: spin-then-park strategy
4832     while (--its >= 0) {
4833       w = *Lock;
4834       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4835         return;
4836       }
4837     }
4838 
4839     Self->reset();
4840     Self->OnList = intptr_t(Lock);
4841     // The following fence() isn't _strictly necessary as the subsequent
4842     // CAS() both serializes execution and ratifies the fetched *Lock value.
4843     OrderAccess::fence();
4844     for (;;) {
4845       w = *Lock;
4846       if ((w & LOCKBIT) == 0) {
4847         if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4848           Self->OnList = 0;   // hygiene - allows stronger asserts
4849           return;
4850         }
4851         continue;      // Interference -- *Lock changed -- Just retry
4852       }
4853       assert(w & LOCKBIT, "invariant");
4854       Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4855       if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4856     }
4857 
4858     while (Self->OnList != 0) {
4859       Self->park();
4860     }
4861   }
4862 }
4863 
4864 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4865   intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4866   if (w == 0) return;
4867   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4868     return;
4869   }
4870 
4871   ParkEvent * ReleaseAfter = NULL;
4872   if (ev == NULL) {
4873     ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4874   }
4875   assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4876   for (;;) {
4877     guarantee(ev->OnList == 0, "invariant");
4878     int its = (os::is_MP() ? 100 : 0) + 1;
4879 
4880     // Optional spin phase: spin-then-park strategy
4881     while (--its >= 0) {
4882       w = *Lock;
4883       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4884         if (ReleaseAfter != NULL) {
4885           ParkEvent::Release(ReleaseAfter);
4886         }
4887         return;
4888       }
4889     }
4890 
4891     ev->reset();
4892     ev->OnList = intptr_t(Lock);
4893     // The following fence() isn't _strictly necessary as the subsequent
4894     // CAS() both serializes execution and ratifies the fetched *Lock value.
4895     OrderAccess::fence();
4896     for (;;) {
4897       w = *Lock;
4898       if ((w & LOCKBIT) == 0) {
4899         if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4900           ev->OnList = 0;
4901           // We call ::Release while holding the outer lock, thus
4902           // artificially lengthening the critical section.
4903           // Consider deferring the ::Release() until the subsequent unlock(),
4904           // after we've dropped the outer lock.
4905           if (ReleaseAfter != NULL) {
4906             ParkEvent::Release(ReleaseAfter);
4907           }
4908           return;
4909         }
4910         continue;      // Interference -- *Lock changed -- Just retry
4911       }
4912       assert(w & LOCKBIT, "invariant");
4913       ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4914       if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4915     }
4916 
4917     while (ev->OnList != 0) {
4918       ev->park();
4919     }
4920   }
4921 }
4922 
4923 // Release() must extract a successor from the list and then wake that thread.
4924 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4925 // similar to that used by ParkEvent::Allocate() and ::Release().  DMR-based
4926 // Release() would :
4927 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4928 // (B) Extract a successor from the private list "in-hand"
4929 // (C) attempt to CAS() the residual back into *Lock over null.
4930 //     If there were any newly arrived threads and the CAS() would fail.
4931 //     In that case Release() would detach the RATs, re-merge the list in-hand
4932 //     with the RATs and repeat as needed.  Alternately, Release() might
4933 //     detach and extract a successor, but then pass the residual list to the wakee.
4934 //     The wakee would be responsible for reattaching and remerging before it
4935 //     competed for the lock.
4936 //
4937 // Both "pop" and DMR are immune from ABA corruption -- there can be
4938 // multiple concurrent pushers, but only one popper or detacher.
4939 // This implementation pops from the head of the list.  This is unfair,
4940 // but tends to provide excellent throughput as hot threads remain hot.
4941 // (We wake recently run threads first).
4942 //
4943 // All paths through muxRelease() will execute a CAS.
4944 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4945 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4946 // executed within the critical section are complete and globally visible before the
4947 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4948 void Thread::muxRelease(volatile intptr_t * Lock)  {
4949   for (;;) {
4950     const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT);
4951     assert(w & LOCKBIT, "invariant");
4952     if (w == LOCKBIT) return;
4953     ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4954     assert(List != NULL, "invariant");
4955     assert(List->OnList == intptr_t(Lock), "invariant");
4956     ParkEvent * const nxt = List->ListNext;
4957     guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4958 
4959     // The following CAS() releases the lock and pops the head element.
4960     // The CAS() also ratifies the previously fetched lock-word value.
4961     if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) {
4962       continue;
4963     }
4964     List->OnList = 0;
4965     OrderAccess::fence();
4966     List->unpark();
4967     return;
4968   }
4969 }
4970 
4971 
4972 void Threads::verify() {
4973   ALL_JAVA_THREADS(p) {
4974     p->verify();
4975   }
4976   VMThread* thread = VMThread::vm_thread();
4977   if (thread != NULL) thread->verify();
4978 }