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