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