rev 50464 : Thread Dump Extension (memory allocation)

   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/timer.hpp"
  97 #include "runtime/timerTrace.hpp"
  98 #include "runtime/vframe.inline.hpp"
  99 #include "runtime/vframeArray.hpp"
 100 #include "runtime/vframe_hp.hpp"
 101 #include "runtime/vmThread.hpp"
 102 #include "runtime/vm_operations.hpp"
 103 #include "runtime/vm_version.hpp"
 104 #include "services/attachListener.hpp"
 105 #include "services/management.hpp"
 106 #include "services/memTracker.hpp"
 107 #include "services/threadService.hpp"
 108 #include "utilities/align.hpp"
 109 #include "utilities/copy.hpp"
 110 #include "utilities/defaultStream.hpp"
 111 #include "utilities/dtrace.hpp"
 112 #include "utilities/events.hpp"
 113 #include "utilities/macros.hpp"
 114 #include "utilities/preserveException.hpp"
 115 #include "utilities/vmError.hpp"
 116 #if INCLUDE_JVMCI
 117 #include "jvmci/jvmciCompiler.hpp"
 118 #include "jvmci/jvmciRuntime.hpp"
 119 #include "logging/logHandle.hpp"
 120 #endif
 121 #ifdef COMPILER1
 122 #include "c1/c1_Compiler.hpp"
 123 #endif
 124 #ifdef COMPILER2
 125 #include "opto/c2compiler.hpp"
 126 #include "opto/idealGraphPrinter.hpp"
 127 #endif
 128 #if INCLUDE_RTM_OPT
 129 #include "runtime/rtmLocking.hpp"
 130 #endif
 131 #if INCLUDE_JFR
 132 #include "jfr/jfr.hpp"
 133 #endif
 134 
 135 // Initialization after module runtime initialization
 136 void universe_post_module_init();  // must happen after call_initPhase2
 137 
 138 #ifdef DTRACE_ENABLED
 139 
 140 // Only bother with this argument setup if dtrace is available
 141 
 142   #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
 143   #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
 144 
 145   #define DTRACE_THREAD_PROBE(probe, javathread)                           \
 146     {                                                                      \
 147       ResourceMark rm(this);                                               \
 148       int len = 0;                                                         \
 149       const char* name = (javathread)->get_thread_name();                  \
 150       len = strlen(name);                                                  \
 151       HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */               \
 152         (char *) name, len,                                                \
 153         java_lang_Thread::thread_id((javathread)->threadObj()),            \
 154         (uintptr_t) (javathread)->osthread()->thread_id(),                 \
 155         java_lang_Thread::is_daemon((javathread)->threadObj()));           \
 156     }
 157 
 158 #else //  ndef DTRACE_ENABLED
 159 
 160   #define DTRACE_THREAD_PROBE(probe, javathread)
 161 
 162 #endif // ndef DTRACE_ENABLED
 163 
 164 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 165 // Current thread is maintained as a thread-local variable
 166 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
 167 #endif
 168 // Class hierarchy
 169 // - Thread
 170 //   - VMThread
 171 //   - WatcherThread
 172 //   - ConcurrentMarkSweepThread
 173 //   - JavaThread
 174 //     - CompilerThread
 175 
 176 // ======= Thread ========
 177 // Support for forcing alignment of thread objects for biased locking
 178 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
 179   if (UseBiasedLocking) {
 180     const int alignment = markOopDesc::biased_lock_alignment;
 181     size_t aligned_size = size + (alignment - sizeof(intptr_t));
 182     void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
 183                                           : AllocateHeap(aligned_size, flags, CURRENT_PC,
 184                                                          AllocFailStrategy::RETURN_NULL);
 185     void* aligned_addr     = align_up(real_malloc_addr, alignment);
 186     assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
 187            ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
 188            "JavaThread alignment code overflowed allocated storage");
 189     if (aligned_addr != real_malloc_addr) {
 190       log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
 191                               p2i(real_malloc_addr),
 192                               p2i(aligned_addr));
 193     }
 194     ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
 195     return aligned_addr;
 196   } else {
 197     return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
 198                        : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
 199   }
 200 }
 201 
 202 void Thread::operator delete(void* p) {
 203   if (UseBiasedLocking) {
 204     FreeHeap(((Thread*) p)->_real_malloc_address);
 205   } else {
 206     FreeHeap(p);
 207   }
 208 }
 209 
 210 void JavaThread::smr_delete() {
 211   if (_on_thread_list) {
 212     ThreadsSMRSupport::smr_delete(this);
 213   } else {
 214     delete this;
 215   }
 216 }
 217 
 218 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
 219 // JavaThread
 220 
 221 
 222 Thread::Thread() {
 223   // stack and get_thread
 224   set_stack_base(NULL);
 225   set_stack_size(0);
 226   set_self_raw_id(0);
 227   set_lgrp_id(-1);
 228   DEBUG_ONLY(clear_suspendible_thread();)
 229 
 230   // allocated data structures
 231   set_osthread(NULL);
 232   set_resource_area(new (mtThread)ResourceArea());
 233   DEBUG_ONLY(_current_resource_mark = NULL;)
 234   set_handle_area(new (mtThread) HandleArea(NULL));
 235   set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
 236   set_active_handles(NULL);
 237   set_free_handle_block(NULL);
 238   set_last_handle_mark(NULL);
 239 



 240   // This initial value ==> never claimed.
 241   _oops_do_parity = 0;
 242   _threads_hazard_ptr = NULL;
 243   _threads_list_ptr = NULL;
 244   _nested_threads_hazard_ptr_cnt = 0;
 245   _rcu_counter = 0;
 246 
 247   // the handle mark links itself to last_handle_mark
 248   new HandleMark(this);
 249 
 250   // plain initialization
 251   debug_only(_owned_locks = NULL;)
 252   debug_only(_allow_allocation_count = 0;)
 253   NOT_PRODUCT(_allow_safepoint_count = 0;)
 254   NOT_PRODUCT(_skip_gcalot = false;)
 255   _jvmti_env_iteration_count = 0;
 256   set_allocated_bytes(0);
 257   _vm_operation_started_count = 0;
 258   _vm_operation_completed_count = 0;
 259   _current_pending_monitor = NULL;
 260   _current_pending_monitor_is_from_java = true;
 261   _current_waiting_monitor = NULL;
 262   _num_nested_signal = 0;
 263   omFreeList = NULL;
 264   omFreeCount = 0;
 265   omFreeProvision = 32;
 266   omInUseList = NULL;
 267   omInUseCount = 0;
 268 
 269 #ifdef ASSERT
 270   _visited_for_critical_count = false;
 271 #endif
 272 
 273   _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
 274                          Monitor::_safepoint_check_sometimes);
 275   _suspend_flags = 0;
 276 
 277   // thread-specific hashCode stream generator state - Marsaglia shift-xor form
 278   _hashStateX = os::random();
 279   _hashStateY = 842502087;
 280   _hashStateZ = 0x8767;    // (int)(3579807591LL & 0xffff) ;
 281   _hashStateW = 273326509;
 282 
 283   _OnTrap   = 0;
 284   _schedctl = NULL;
 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) 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     st->print("tid=" INTPTR_FORMAT " ", p2i(this));
 880     osthread()->print_on(st);
 881   }
 882   ThreadsSMRSupport::print_info_on(this, st);
 883   st->print(" ");
 884   debug_only(if (WizardMode) print_owned_locks_on(st);)
 885 }
 886 
 887 // Thread::print_on_error() is called by fatal error handler. Don't use
 888 // any lock or allocate memory.
 889 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
 890   assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
 891 
 892   if (is_VM_thread())                 { st->print("VMThread"); }
 893   else if (is_GC_task_thread())       { st->print("GCTaskThread"); }
 894   else if (is_Watcher_thread())       { st->print("WatcherThread"); }
 895   else if (is_ConcurrentGC_thread())  { st->print("ConcurrentGCThread"); }
 896   else                                { st->print("Thread"); }
 897 
 898   if (is_Named_thread()) {
 899     st->print(" \"%s\"", name());
 900   }
 901 
 902   st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
 903             p2i(stack_end()), p2i(stack_base()));
 904 
 905   if (osthread()) {
 906     st->print(" [id=%d]", osthread()->thread_id());
 907   }
 908 
 909   ThreadsSMRSupport::print_info_on(this, st);
 910 }
 911 
 912 void Thread::print_value_on(outputStream* st) const {
 913   if (is_Named_thread()) {
 914     st->print(" \"%s\" ", name());
 915   }
 916   st->print(INTPTR_FORMAT, p2i(this));   // print address
 917 }
 918 
 919 #ifdef ASSERT
 920 void Thread::print_owned_locks_on(outputStream* st) const {
 921   Monitor *cur = _owned_locks;
 922   if (cur == NULL) {
 923     st->print(" (no locks) ");
 924   } else {
 925     st->print_cr(" Locks owned:");
 926     while (cur) {
 927       cur->print_on(st);
 928       cur = cur->next();
 929     }
 930   }
 931 }
 932 
 933 static int ref_use_count  = 0;
 934 
 935 bool Thread::owns_locks_but_compiled_lock() const {
 936   for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 937     if (cur != Compile_lock) return true;
 938   }
 939   return false;
 940 }
 941 
 942 
 943 #endif
 944 
 945 #ifndef PRODUCT
 946 
 947 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially
 948 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that
 949 // no threads which allow_vm_block's are held
 950 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
 951   // Check if current thread is allowed to block at a safepoint
 952   if (!(_allow_safepoint_count == 0)) {
 953     fatal("Possible safepoint reached by thread that does not allow it");
 954   }
 955   if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
 956     fatal("LEAF method calling lock?");
 957   }
 958 
 959 #ifdef ASSERT
 960   if (potential_vm_operation && is_Java_thread()
 961       && !Universe::is_bootstrapping()) {
 962     // Make sure we do not hold any locks that the VM thread also uses.
 963     // This could potentially lead to deadlocks
 964     for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 965       // Threads_lock is special, since the safepoint synchronization will not start before this is
 966       // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
 967       // since it is used to transfer control between JavaThreads and the VMThread
 968       // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
 969       if ((cur->allow_vm_block() &&
 970            cur != Threads_lock &&
 971            cur != Compile_lock &&               // Temporary: should not be necessary when we get separate compilation
 972            cur != VMOperationRequest_lock &&
 973            cur != VMOperationQueue_lock) ||
 974            cur->rank() == Mutex::special) {
 975         fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
 976       }
 977     }
 978   }
 979 
 980   if (GCALotAtAllSafepoints) {
 981     // We could enter a safepoint here and thus have a gc
 982     InterfaceSupport::check_gc_alot();
 983   }
 984 #endif
 985 }
 986 #endif
 987 
 988 bool Thread::is_in_stack(address adr) const {
 989   assert(Thread::current() == this, "is_in_stack can only be called from current thread");
 990   address end = os::current_stack_pointer();
 991   // Allow non Java threads to call this without stack_base
 992   if (_stack_base == NULL) return true;
 993   if (stack_base() >= adr && adr >= end) return true;
 994 
 995   return false;
 996 }
 997 
 998 bool Thread::is_in_usable_stack(address adr) const {
 999   size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
1000   size_t usable_stack_size = _stack_size - stack_guard_size;
1001 
1002   return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
1003 }
1004 
1005 
1006 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
1007 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
1008 // used for compilation in the future. If that change is made, the need for these methods
1009 // should be revisited, and they should be removed if possible.
1010 
1011 bool Thread::is_lock_owned(address adr) const {
1012   return on_local_stack(adr);
1013 }
1014 
1015 bool Thread::set_as_starting_thread() {
1016   // NOTE: this must be called inside the main thread.
1017   return os::create_main_thread((JavaThread*)this);
1018 }
1019 
1020 static void initialize_class(Symbol* class_name, TRAPS) {
1021   Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
1022   InstanceKlass::cast(klass)->initialize(CHECK);
1023 }
1024 
1025 
1026 // Creates the initial ThreadGroup
1027 static Handle create_initial_thread_group(TRAPS) {
1028   Handle system_instance = JavaCalls::construct_new_instance(
1029                             SystemDictionary::ThreadGroup_klass(),
1030                             vmSymbols::void_method_signature(),
1031                             CHECK_NH);
1032   Universe::set_system_thread_group(system_instance());
1033 
1034   Handle string = java_lang_String::create_from_str("main", CHECK_NH);
1035   Handle main_instance = JavaCalls::construct_new_instance(
1036                             SystemDictionary::ThreadGroup_klass(),
1037                             vmSymbols::threadgroup_string_void_signature(),
1038                             system_instance,
1039                             string,
1040                             CHECK_NH);
1041   return main_instance;
1042 }
1043 
1044 // Creates the initial Thread
1045 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
1046                                  TRAPS) {
1047   InstanceKlass* ik = SystemDictionary::Thread_klass();
1048   assert(ik->is_initialized(), "must be");
1049   instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
1050 
1051   // Cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1052   // constructor calls Thread.current(), which must be set here for the
1053   // initial thread.
1054   java_lang_Thread::set_thread(thread_oop(), thread);
1055   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1056   thread->set_threadObj(thread_oop());
1057 
1058   Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1059 
1060   JavaValue result(T_VOID);
1061   JavaCalls::call_special(&result, thread_oop,
1062                           ik,
1063                           vmSymbols::object_initializer_name(),
1064                           vmSymbols::threadgroup_string_void_signature(),
1065                           thread_group,
1066                           string,
1067                           CHECK_NULL);
1068   return thread_oop();
1069 }
1070 
1071 char java_runtime_name[128] = "";
1072 char java_runtime_version[128] = "";
1073 
1074 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1075 static const char* get_java_runtime_name(TRAPS) {
1076   Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1077                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1078   fieldDescriptor fd;
1079   bool found = k != NULL &&
1080                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1081                                                         vmSymbols::string_signature(), &fd);
1082   if (found) {
1083     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1084     if (name_oop == NULL) {
1085       return NULL;
1086     }
1087     const char* name = java_lang_String::as_utf8_string(name_oop,
1088                                                         java_runtime_name,
1089                                                         sizeof(java_runtime_name));
1090     return name;
1091   } else {
1092     return NULL;
1093   }
1094 }
1095 
1096 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1097 static const char* get_java_runtime_version(TRAPS) {
1098   Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1099                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1100   fieldDescriptor fd;
1101   bool found = k != NULL &&
1102                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1103                                                         vmSymbols::string_signature(), &fd);
1104   if (found) {
1105     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1106     if (name_oop == NULL) {
1107       return NULL;
1108     }
1109     const char* name = java_lang_String::as_utf8_string(name_oop,
1110                                                         java_runtime_version,
1111                                                         sizeof(java_runtime_version));
1112     return name;
1113   } else {
1114     return NULL;
1115   }
1116 }
1117 
1118 // General purpose hook into Java code, run once when the VM is initialized.
1119 // The Java library method itself may be changed independently from the VM.
1120 static void call_postVMInitHook(TRAPS) {
1121   Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1122   if (klass != NULL) {
1123     JavaValue result(T_VOID);
1124     JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1125                            vmSymbols::void_method_signature(),
1126                            CHECK);
1127   }
1128 }
1129 
1130 static void reset_vm_info_property(TRAPS) {
1131   // the vm info string
1132   ResourceMark rm(THREAD);
1133   const char *vm_info = VM_Version::vm_info_string();
1134 
1135   // update the native system property first
1136   Arguments::PropertyList_update_value(Arguments::system_properties(), "java.vm.info", vm_info);
1137 
1138   // java.lang.System class
1139   Klass* klass =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1140 
1141   // setProperty arguments
1142   Handle key_str    = java_lang_String::create_from_str("java.vm.info", CHECK);
1143   Handle value_str  = java_lang_String::create_from_str(vm_info, CHECK);
1144 
1145   // return value
1146   JavaValue r(T_OBJECT);
1147 
1148   // public static String setProperty(String key, String value);
1149   JavaCalls::call_static(&r,
1150                          klass,
1151                          vmSymbols::setProperty_name(),
1152                          vmSymbols::string_string_string_signature(),
1153                          key_str,
1154                          value_str,
1155                          CHECK);
1156 }
1157 
1158 
1159 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1160                                     bool daemon, TRAPS) {
1161   assert(thread_group.not_null(), "thread group should be specified");
1162   assert(threadObj() == NULL, "should only create Java thread object once");
1163 
1164   InstanceKlass* ik = SystemDictionary::Thread_klass();
1165   assert(ik->is_initialized(), "must be");
1166   instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1167 
1168   // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon.
1169   // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1170   // constructor calls Thread.current(), which must be set here.
1171   java_lang_Thread::set_thread(thread_oop(), this);
1172   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1173   set_threadObj(thread_oop());
1174 
1175   JavaValue result(T_VOID);
1176   if (thread_name != NULL) {
1177     Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1178     // Thread gets assigned specified name and null target
1179     JavaCalls::call_special(&result,
1180                             thread_oop,
1181                             ik,
1182                             vmSymbols::object_initializer_name(),
1183                             vmSymbols::threadgroup_string_void_signature(),
1184                             thread_group,
1185                             name,
1186                             THREAD);
1187   } else {
1188     // Thread gets assigned name "Thread-nnn" and null target
1189     // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1190     JavaCalls::call_special(&result,
1191                             thread_oop,
1192                             ik,
1193                             vmSymbols::object_initializer_name(),
1194                             vmSymbols::threadgroup_runnable_void_signature(),
1195                             thread_group,
1196                             Handle(),
1197                             THREAD);
1198   }
1199 
1200 
1201   if (daemon) {
1202     java_lang_Thread::set_daemon(thread_oop());
1203   }
1204 
1205   if (HAS_PENDING_EXCEPTION) {
1206     return;
1207   }
1208 
1209   Klass* group =  SystemDictionary::ThreadGroup_klass();
1210   Handle threadObj(THREAD, this->threadObj());
1211 
1212   JavaCalls::call_special(&result,
1213                           thread_group,
1214                           group,
1215                           vmSymbols::add_method_name(),
1216                           vmSymbols::thread_void_signature(),
1217                           threadObj,          // Arg 1
1218                           THREAD);
1219 }
1220 
1221 // NamedThread --  non-JavaThread subclasses with multiple
1222 // uniquely named instances should derive from this.
1223 NamedThread::NamedThread() : Thread() {
1224   _name = NULL;
1225   _processed_thread = NULL;
1226   _gc_id = GCId::undefined();
1227 }
1228 
1229 NamedThread::~NamedThread() {
1230   if (_name != NULL) {
1231     FREE_C_HEAP_ARRAY(char, _name);
1232     _name = NULL;
1233   }
1234 }
1235 
1236 void NamedThread::set_name(const char* format, ...) {
1237   guarantee(_name == NULL, "Only get to set name once.");
1238   _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1239   guarantee(_name != NULL, "alloc failure");
1240   va_list ap;
1241   va_start(ap, format);
1242   jio_vsnprintf(_name, max_name_len, format, ap);
1243   va_end(ap);
1244 }
1245 
1246 void NamedThread::initialize_named_thread() {
1247   set_native_thread_name(name());
1248 }
1249 
1250 void NamedThread::print_on(outputStream* st) const {
1251   st->print("\"%s\" ", name());
1252   Thread::print_on(st);
1253   st->cr();
1254 }
1255 
1256 
1257 // ======= WatcherThread ========
1258 
1259 // The watcher thread exists to simulate timer interrupts.  It should
1260 // be replaced by an abstraction over whatever native support for
1261 // timer interrupts exists on the platform.
1262 
1263 WatcherThread* WatcherThread::_watcher_thread   = NULL;
1264 bool WatcherThread::_startable = false;
1265 volatile bool  WatcherThread::_should_terminate = false;
1266 
1267 WatcherThread::WatcherThread() : Thread() {
1268   assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1269   if (os::create_thread(this, os::watcher_thread)) {
1270     _watcher_thread = this;
1271 
1272     // Set the watcher thread to the highest OS priority which should not be
1273     // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1274     // is created. The only normal thread using this priority is the reference
1275     // handler thread, which runs for very short intervals only.
1276     // If the VMThread's priority is not lower than the WatcherThread profiling
1277     // will be inaccurate.
1278     os::set_priority(this, MaxPriority);
1279     if (!DisableStartThread) {
1280       os::start_thread(this);
1281     }
1282   }
1283 }
1284 
1285 int WatcherThread::sleep() const {
1286   // The WatcherThread does not participate in the safepoint protocol
1287   // for the PeriodicTask_lock because it is not a JavaThread.
1288   MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1289 
1290   if (_should_terminate) {
1291     // check for termination before we do any housekeeping or wait
1292     return 0;  // we did not sleep.
1293   }
1294 
1295   // remaining will be zero if there are no tasks,
1296   // causing the WatcherThread to sleep until a task is
1297   // enrolled
1298   int remaining = PeriodicTask::time_to_wait();
1299   int time_slept = 0;
1300 
1301   // we expect this to timeout - we only ever get unparked when
1302   // we should terminate or when a new task has been enrolled
1303   OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1304 
1305   jlong time_before_loop = os::javaTimeNanos();
1306 
1307   while (true) {
1308     bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1309                                             remaining);
1310     jlong now = os::javaTimeNanos();
1311 
1312     if (remaining == 0) {
1313       // if we didn't have any tasks we could have waited for a long time
1314       // consider the time_slept zero and reset time_before_loop
1315       time_slept = 0;
1316       time_before_loop = now;
1317     } else {
1318       // need to recalculate since we might have new tasks in _tasks
1319       time_slept = (int) ((now - time_before_loop) / 1000000);
1320     }
1321 
1322     // Change to task list or spurious wakeup of some kind
1323     if (timedout || _should_terminate) {
1324       break;
1325     }
1326 
1327     remaining = PeriodicTask::time_to_wait();
1328     if (remaining == 0) {
1329       // Last task was just disenrolled so loop around and wait until
1330       // another task gets enrolled
1331       continue;
1332     }
1333 
1334     remaining -= time_slept;
1335     if (remaining <= 0) {
1336       break;
1337     }
1338   }
1339 
1340   return time_slept;
1341 }
1342 
1343 void WatcherThread::run() {
1344   assert(this == watcher_thread(), "just checking");
1345 
1346   this->record_stack_base_and_size();
1347   this->set_native_thread_name(this->name());
1348   this->set_active_handles(JNIHandleBlock::allocate_block());
1349   while (true) {
1350     assert(watcher_thread() == Thread::current(), "thread consistency check");
1351     assert(watcher_thread() == this, "thread consistency check");
1352 
1353     // Calculate how long it'll be until the next PeriodicTask work
1354     // should be done, and sleep that amount of time.
1355     int time_waited = sleep();
1356 
1357     if (VMError::is_error_reported()) {
1358       // A fatal error has happened, the error handler(VMError::report_and_die)
1359       // should abort JVM after creating an error log file. However in some
1360       // rare cases, the error handler itself might deadlock. Here periodically
1361       // check for error reporting timeouts, and if it happens, just proceed to
1362       // abort the VM.
1363 
1364       // This code is in WatcherThread because WatcherThread wakes up
1365       // periodically so the fatal error handler doesn't need to do anything;
1366       // also because the WatcherThread is less likely to crash than other
1367       // threads.
1368 
1369       for (;;) {
1370         // Note: we use naked sleep in this loop because we want to avoid using
1371         // any kind of VM infrastructure which may be broken at this point.
1372         if (VMError::check_timeout()) {
1373           // We hit error reporting timeout. Error reporting was interrupted and
1374           // will be wrapping things up now (closing files etc). Give it some more
1375           // time, then quit the VM.
1376           os::naked_short_sleep(200);
1377           // Print a message to stderr.
1378           fdStream err(defaultStream::output_fd());
1379           err.print_raw_cr("# [ timer expired, abort... ]");
1380           // skip atexit/vm_exit/vm_abort hooks
1381           os::die();
1382         }
1383 
1384         // Wait a second, then recheck for timeout.
1385         os::naked_short_sleep(999);
1386       }
1387     }
1388 
1389     if (_should_terminate) {
1390       // check for termination before posting the next tick
1391       break;
1392     }
1393 
1394     PeriodicTask::real_time_tick(time_waited);
1395   }
1396 
1397   // Signal that it is terminated
1398   {
1399     MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1400     _watcher_thread = NULL;
1401     Terminator_lock->notify();
1402   }
1403 }
1404 
1405 void WatcherThread::start() {
1406   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1407 
1408   if (watcher_thread() == NULL && _startable) {
1409     _should_terminate = false;
1410     // Create the single instance of WatcherThread
1411     new WatcherThread();
1412   }
1413 }
1414 
1415 void WatcherThread::make_startable() {
1416   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1417   _startable = true;
1418 }
1419 
1420 void WatcherThread::stop() {
1421   {
1422     // Follow normal safepoint aware lock enter protocol since the
1423     // WatcherThread is stopped by another JavaThread.
1424     MutexLocker ml(PeriodicTask_lock);
1425     _should_terminate = true;
1426 
1427     WatcherThread* watcher = watcher_thread();
1428     if (watcher != NULL) {
1429       // unpark the WatcherThread so it can see that it should terminate
1430       watcher->unpark();
1431     }
1432   }
1433 
1434   MutexLocker mu(Terminator_lock);
1435 
1436   while (watcher_thread() != NULL) {
1437     // This wait should make safepoint checks, wait without a timeout,
1438     // and wait as a suspend-equivalent condition.
1439     Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1440                           Mutex::_as_suspend_equivalent_flag);
1441   }
1442 }
1443 
1444 void WatcherThread::unpark() {
1445   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1446   PeriodicTask_lock->notify();
1447 }
1448 
1449 void WatcherThread::print_on(outputStream* st) const {
1450   st->print("\"%s\" ", name());
1451   Thread::print_on(st);
1452   st->cr();
1453 }
1454 
1455 // ======= JavaThread ========
1456 
1457 #if INCLUDE_JVMCI
1458 
1459 jlong* JavaThread::_jvmci_old_thread_counters;
1460 
1461 bool jvmci_counters_include(JavaThread* thread) {
1462   return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1463 }
1464 
1465 void JavaThread::collect_counters(typeArrayOop array) {
1466   if (JVMCICounterSize > 0) {
1467     JavaThreadIteratorWithHandle jtiwh;
1468     for (int i = 0; i < array->length(); i++) {
1469       array->long_at_put(i, _jvmci_old_thread_counters[i]);
1470     }
1471     for (; JavaThread *tp = jtiwh.next(); ) {
1472       if (jvmci_counters_include(tp)) {
1473         for (int i = 0; i < array->length(); i++) {
1474           array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1475         }
1476       }
1477     }
1478   }
1479 }
1480 
1481 #endif // INCLUDE_JVMCI
1482 
1483 // A JavaThread is a normal Java thread
1484 
1485 void JavaThread::initialize() {
1486   // Initialize fields
1487 
1488   set_saved_exception_pc(NULL);
1489   set_threadObj(NULL);
1490   _anchor.clear();
1491   set_entry_point(NULL);
1492   set_jni_functions(jni_functions());
1493   set_callee_target(NULL);
1494   set_vm_result(NULL);
1495   set_vm_result_2(NULL);
1496   set_vframe_array_head(NULL);
1497   set_vframe_array_last(NULL);
1498   set_deferred_locals(NULL);
1499   set_deopt_mark(NULL);
1500   set_deopt_compiled_method(NULL);
1501   clear_must_deopt_id();
1502   set_monitor_chunks(NULL);
1503   set_next(NULL);
1504   _on_thread_list = false;
1505   set_thread_state(_thread_new);
1506   _terminated = _not_terminated;
1507   _privileged_stack_top = NULL;
1508   _array_for_gc = NULL;
1509   _suspend_equivalent = false;
1510   _in_deopt_handler = 0;
1511   _doing_unsafe_access = false;
1512   _stack_guard_state = stack_guard_unused;
1513 #if INCLUDE_JVMCI
1514   _pending_monitorenter = false;
1515   _pending_deoptimization = -1;
1516   _pending_failed_speculation = NULL;
1517   _pending_transfer_to_interpreter = false;
1518   _adjusting_comp_level = false;
1519   _jvmci._alternate_call_target = NULL;
1520   assert(_jvmci._implicit_exception_pc == NULL, "must be");
1521   if (JVMCICounterSize > 0) {
1522     _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1523     memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1524   } else {
1525     _jvmci_counters = NULL;
1526   }
1527 #endif // INCLUDE_JVMCI
1528   _reserved_stack_activation = NULL;  // stack base not known yet
1529   (void)const_cast<oop&>(_exception_oop = oop(NULL));
1530   _exception_pc  = 0;
1531   _exception_handler_pc = 0;
1532   _is_method_handle_return = 0;
1533   _jvmti_thread_state= NULL;
1534   _should_post_on_exceptions_flag = JNI_FALSE;
1535   _jvmti_get_loaded_classes_closure = NULL;
1536   _interp_only_mode    = 0;
1537   _special_runtime_exit_condition = _no_async_condition;
1538   _pending_async_exception = NULL;
1539   _thread_stat = NULL;
1540   _thread_stat = new ThreadStatistics();
1541   _blocked_on_compilation = false;
1542   _jni_active_critical = 0;
1543   _pending_jni_exception_check_fn = NULL;
1544   _do_not_unlock_if_synchronized = false;
1545   _cached_monitor_info = NULL;
1546   _parker = Parker::Allocate(this);
1547 
1548 #ifndef PRODUCT
1549   _jmp_ring_index = 0;
1550   for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1551     record_jump(NULL, NULL, NULL, 0);
1552   }
1553 #endif // PRODUCT
1554 
1555   // Setup safepoint state info for this thread
1556   ThreadSafepointState::create(this);
1557 
1558   debug_only(_java_call_counter = 0);
1559 
1560   // JVMTI PopFrame support
1561   _popframe_condition = popframe_inactive;
1562   _popframe_preserved_args = NULL;
1563   _popframe_preserved_args_size = 0;
1564   _frames_to_pop_failed_realloc = 0;
1565 
1566   if (SafepointMechanism::uses_thread_local_poll()) {
1567     SafepointMechanism::initialize_header(this);
1568   }
1569 
1570   pd_initialize();
1571 }
1572 
1573 JavaThread::JavaThread(bool is_attaching_via_jni) :
1574                        Thread() {
1575   initialize();
1576   if (is_attaching_via_jni) {
1577     _jni_attach_state = _attaching_via_jni;
1578   } else {
1579     _jni_attach_state = _not_attaching_via_jni;
1580   }
1581   assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1582 }
1583 
1584 bool JavaThread::reguard_stack(address cur_sp) {
1585   if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1586       && _stack_guard_state != stack_guard_reserved_disabled) {
1587     return true; // Stack already guarded or guard pages not needed.
1588   }
1589 
1590   if (register_stack_overflow()) {
1591     // For those architectures which have separate register and
1592     // memory stacks, we must check the register stack to see if
1593     // it has overflowed.
1594     return false;
1595   }
1596 
1597   // Java code never executes within the yellow zone: the latter is only
1598   // there to provoke an exception during stack banging.  If java code
1599   // is executing there, either StackShadowPages should be larger, or
1600   // some exception code in c1, c2 or the interpreter isn't unwinding
1601   // when it should.
1602   guarantee(cur_sp > stack_reserved_zone_base(),
1603             "not enough space to reguard - increase StackShadowPages");
1604   if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1605     enable_stack_yellow_reserved_zone();
1606     if (reserved_stack_activation() != stack_base()) {
1607       set_reserved_stack_activation(stack_base());
1608     }
1609   } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1610     set_reserved_stack_activation(stack_base());
1611     enable_stack_reserved_zone();
1612   }
1613   return true;
1614 }
1615 
1616 bool JavaThread::reguard_stack(void) {
1617   return reguard_stack(os::current_stack_pointer());
1618 }
1619 
1620 
1621 void JavaThread::block_if_vm_exited() {
1622   if (_terminated == _vm_exited) {
1623     // _vm_exited is set at safepoint, and Threads_lock is never released
1624     // we will block here forever
1625     Threads_lock->lock_without_safepoint_check();
1626     ShouldNotReachHere();
1627   }
1628 }
1629 
1630 
1631 // Remove this ifdef when C1 is ported to the compiler interface.
1632 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1633 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1634 
1635 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1636                        Thread() {
1637   initialize();
1638   _jni_attach_state = _not_attaching_via_jni;
1639   set_entry_point(entry_point);
1640   // Create the native thread itself.
1641   // %note runtime_23
1642   os::ThreadType thr_type = os::java_thread;
1643   thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1644                                                      os::java_thread;
1645   os::create_thread(this, thr_type, stack_sz);
1646   // The _osthread may be NULL here because we ran out of memory (too many threads active).
1647   // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1648   // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1649   // the exception consists of creating the exception object & initializing it, initialization
1650   // will leave the VM via a JavaCall and then all locks must be unlocked).
1651   //
1652   // The thread is still suspended when we reach here. Thread must be explicit started
1653   // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1654   // by calling Threads:add. The reason why this is not done here, is because the thread
1655   // object must be fully initialized (take a look at JVM_Start)
1656 }
1657 
1658 JavaThread::~JavaThread() {
1659 
1660   // JSR166 -- return the parker to the free list
1661   Parker::Release(_parker);
1662   _parker = NULL;
1663 
1664   // Free any remaining  previous UnrollBlock
1665   vframeArray* old_array = vframe_array_last();
1666 
1667   if (old_array != NULL) {
1668     Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1669     old_array->set_unroll_block(NULL);
1670     delete old_info;
1671     delete old_array;
1672   }
1673 
1674   GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1675   if (deferred != NULL) {
1676     // This can only happen if thread is destroyed before deoptimization occurs.
1677     assert(deferred->length() != 0, "empty array!");
1678     do {
1679       jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1680       deferred->remove_at(0);
1681       // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1682       delete dlv;
1683     } while (deferred->length() != 0);
1684     delete deferred;
1685   }
1686 
1687   // All Java related clean up happens in exit
1688   ThreadSafepointState::destroy(this);
1689   if (_thread_stat != NULL) delete _thread_stat;
1690 
1691 #if INCLUDE_JVMCI
1692   if (JVMCICounterSize > 0) {
1693     if (jvmci_counters_include(this)) {
1694       for (int i = 0; i < JVMCICounterSize; i++) {
1695         _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1696       }
1697     }
1698     FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1699   }
1700 #endif // INCLUDE_JVMCI
1701 }
1702 
1703 
1704 // The first routine called by a new Java thread
1705 void JavaThread::run() {
1706   // initialize thread-local alloc buffer related fields
1707   this->initialize_tlab();
1708 
1709   // used to test validity of stack trace backs
1710   this->record_base_of_stack_pointer();
1711 
1712   // Record real stack base and size.
1713   this->record_stack_base_and_size();
1714 
1715   this->create_stack_guard_pages();
1716 
1717   this->cache_global_variables();
1718 
1719   // Thread is now sufficient initialized to be handled by the safepoint code as being
1720   // in the VM. Change thread state from _thread_new to _thread_in_vm
1721   ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1722 
1723   assert(JavaThread::current() == this, "sanity check");
1724   assert(!Thread::current()->owns_locks(), "sanity check");
1725 
1726   DTRACE_THREAD_PROBE(start, this);
1727 
1728   // This operation might block. We call that after all safepoint checks for a new thread has
1729   // been completed.
1730   this->set_active_handles(JNIHandleBlock::allocate_block());
1731 
1732   if (JvmtiExport::should_post_thread_life()) {
1733     JvmtiExport::post_thread_start(this);
1734   }
1735 
1736   EventThreadStart event;
1737   if (event.should_commit()) {
1738     event.set_thread(JFR_THREAD_ID(this));
1739     event.commit();
1740   }
1741 
1742   // We call another function to do the rest so we are sure that the stack addresses used
1743   // from there will be lower than the stack base just computed
1744   thread_main_inner();
1745 
1746   // Note, thread is no longer valid at this point!
1747 }
1748 
1749 
1750 void JavaThread::thread_main_inner() {
1751   assert(JavaThread::current() == this, "sanity check");
1752   assert(this->threadObj() != NULL, "just checking");
1753 
1754   // Execute thread entry point unless this thread has a pending exception
1755   // or has been stopped before starting.
1756   // Note: Due to JVM_StopThread we can have pending exceptions already!
1757   if (!this->has_pending_exception() &&
1758       !java_lang_Thread::is_stillborn(this->threadObj())) {
1759     {
1760       ResourceMark rm(this);
1761       this->set_native_thread_name(this->get_thread_name());
1762     }
1763     HandleMark hm(this);
1764     this->entry_point()(this, this);
1765   }
1766 
1767   DTRACE_THREAD_PROBE(stop, this);
1768 
1769   this->exit(false);
1770   this->smr_delete();
1771 }
1772 
1773 
1774 static void ensure_join(JavaThread* thread) {
1775   // We do not need to grab the Threads_lock, since we are operating on ourself.
1776   Handle threadObj(thread, thread->threadObj());
1777   assert(threadObj.not_null(), "java thread object must exist");
1778   ObjectLocker lock(threadObj, thread);
1779   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1780   thread->clear_pending_exception();
1781   // Thread is exiting. So set thread_status field in  java.lang.Thread class to TERMINATED.
1782   java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1783   // Clear the native thread instance - this makes isAlive return false and allows the join()
1784   // to complete once we've done the notify_all below
1785   java_lang_Thread::set_thread(threadObj(), NULL);
1786   lock.notify_all(thread);
1787   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1788   thread->clear_pending_exception();
1789 }
1790 
1791 
1792 // For any new cleanup additions, please check to see if they need to be applied to
1793 // cleanup_failed_attach_current_thread as well.
1794 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1795   assert(this == JavaThread::current(), "thread consistency check");
1796 
1797   elapsedTimer _timer_exit_phase1;
1798   elapsedTimer _timer_exit_phase2;
1799   elapsedTimer _timer_exit_phase3;
1800   elapsedTimer _timer_exit_phase4;
1801 
1802   if (log_is_enabled(Debug, os, thread, timer)) {
1803     _timer_exit_phase1.start();
1804   }
1805 
1806   HandleMark hm(this);
1807   Handle uncaught_exception(this, this->pending_exception());
1808   this->clear_pending_exception();
1809   Handle threadObj(this, this->threadObj());
1810   assert(threadObj.not_null(), "Java thread object should be created");
1811 
1812   // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1813   {
1814     EXCEPTION_MARK;
1815 
1816     CLEAR_PENDING_EXCEPTION;
1817   }
1818   if (!destroy_vm) {
1819     if (uncaught_exception.not_null()) {
1820       EXCEPTION_MARK;
1821       // Call method Thread.dispatchUncaughtException().
1822       Klass* thread_klass = SystemDictionary::Thread_klass();
1823       JavaValue result(T_VOID);
1824       JavaCalls::call_virtual(&result,
1825                               threadObj, thread_klass,
1826                               vmSymbols::dispatchUncaughtException_name(),
1827                               vmSymbols::throwable_void_signature(),
1828                               uncaught_exception,
1829                               THREAD);
1830       if (HAS_PENDING_EXCEPTION) {
1831         ResourceMark rm(this);
1832         jio_fprintf(defaultStream::error_stream(),
1833                     "\nException: %s thrown from the UncaughtExceptionHandler"
1834                     " in thread \"%s\"\n",
1835                     pending_exception()->klass()->external_name(),
1836                     get_thread_name());
1837         CLEAR_PENDING_EXCEPTION;
1838       }
1839     }
1840 
1841     // Called before the java thread exit since we want to read info
1842     // from java_lang_Thread object
1843     EventThreadEnd event;
1844     if (event.should_commit()) {
1845       event.set_thread(JFR_THREAD_ID(this));
1846       event.commit();
1847     }
1848 
1849     // Call after last event on thread
1850     JFR_ONLY(Jfr::on_thread_exit(this);)
1851 
1852     // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1853     // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1854     // is deprecated anyhow.
1855     if (!is_Compiler_thread()) {
1856       int count = 3;
1857       while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1858         EXCEPTION_MARK;
1859         JavaValue result(T_VOID);
1860         Klass* thread_klass = SystemDictionary::Thread_klass();
1861         JavaCalls::call_virtual(&result,
1862                                 threadObj, thread_klass,
1863                                 vmSymbols::exit_method_name(),
1864                                 vmSymbols::void_method_signature(),
1865                                 THREAD);
1866         CLEAR_PENDING_EXCEPTION;
1867       }
1868     }
1869     // notify JVMTI
1870     if (JvmtiExport::should_post_thread_life()) {
1871       JvmtiExport::post_thread_end(this);
1872     }
1873 
1874     // We have notified the agents that we are exiting, before we go on,
1875     // we must check for a pending external suspend request and honor it
1876     // in order to not surprise the thread that made the suspend request.
1877     while (true) {
1878       {
1879         MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1880         if (!is_external_suspend()) {
1881           set_terminated(_thread_exiting);
1882           ThreadService::current_thread_exiting(this);
1883           break;
1884         }
1885         // Implied else:
1886         // Things get a little tricky here. We have a pending external
1887         // suspend request, but we are holding the SR_lock so we
1888         // can't just self-suspend. So we temporarily drop the lock
1889         // and then self-suspend.
1890       }
1891 
1892       ThreadBlockInVM tbivm(this);
1893       java_suspend_self();
1894 
1895       // We're done with this suspend request, but we have to loop around
1896       // and check again. Eventually we will get SR_lock without a pending
1897       // external suspend request and will be able to mark ourselves as
1898       // exiting.
1899     }
1900     // no more external suspends are allowed at this point
1901   } else {
1902     // before_exit() has already posted JVMTI THREAD_END events
1903   }
1904 
1905   if (log_is_enabled(Debug, os, thread, timer)) {
1906     _timer_exit_phase1.stop();
1907     _timer_exit_phase2.start();
1908   }
1909   // Notify waiters on thread object. This has to be done after exit() is called
1910   // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1911   // group should have the destroyed bit set before waiters are notified).
1912   ensure_join(this);
1913   assert(!this->has_pending_exception(), "ensure_join should have cleared");
1914 
1915   if (log_is_enabled(Debug, os, thread, timer)) {
1916     _timer_exit_phase2.stop();
1917     _timer_exit_phase3.start();
1918   }
1919   // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1920   // held by this thread must be released. The spec does not distinguish
1921   // between JNI-acquired and regular Java monitors. We can only see
1922   // regular Java monitors here if monitor enter-exit matching is broken.
1923   //
1924   // Optionally release any monitors for regular JavaThread exits. This
1925   // is provided as a work around for any bugs in monitor enter-exit
1926   // matching. This can be expensive so it is not enabled by default.
1927   //
1928   // ensure_join() ignores IllegalThreadStateExceptions, and so does
1929   // ObjectSynchronizer::release_monitors_owned_by_thread().
1930   if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) {
1931     // Sanity check even though JNI DetachCurrentThread() would have
1932     // returned JNI_ERR if there was a Java frame. JavaThread exit
1933     // should be done executing Java code by the time we get here.
1934     assert(!this->has_last_Java_frame(),
1935            "should not have a Java frame when detaching or exiting");
1936     ObjectSynchronizer::release_monitors_owned_by_thread(this);
1937     assert(!this->has_pending_exception(), "release_monitors should have cleared");
1938   }
1939 
1940   // These things needs to be done while we are still a Java Thread. Make sure that thread
1941   // is in a consistent state, in case GC happens
1942   assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1943 
1944   if (active_handles() != NULL) {
1945     JNIHandleBlock* block = active_handles();
1946     set_active_handles(NULL);
1947     JNIHandleBlock::release_block(block);
1948   }
1949 
1950   if (free_handle_block() != NULL) {
1951     JNIHandleBlock* block = free_handle_block();
1952     set_free_handle_block(NULL);
1953     JNIHandleBlock::release_block(block);
1954   }
1955 
1956   // These have to be removed while this is still a valid thread.
1957   remove_stack_guard_pages();
1958 
1959   if (UseTLAB) {
1960     tlab().make_parsable(true);  // retire TLAB
1961   }
1962 
1963   if (JvmtiEnv::environments_might_exist()) {
1964     JvmtiExport::cleanup_thread(this);
1965   }
1966 
1967   // We must flush any deferred card marks and other various GC barrier
1968   // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer)
1969   // before removing a thread from the list of active threads.
1970   BarrierSet::barrier_set()->on_thread_detach(this);
1971 
1972   log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
1973     exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
1974     os::current_thread_id());
1975 
1976   if (log_is_enabled(Debug, os, thread, timer)) {
1977     _timer_exit_phase3.stop();
1978     _timer_exit_phase4.start();
1979   }
1980   // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1981   Threads::remove(this);
1982 
1983   if (log_is_enabled(Debug, os, thread, timer)) {
1984     _timer_exit_phase4.stop();
1985     ResourceMark rm(this);
1986     log_debug(os, thread, timer)("name='%s'"
1987                                  ", exit-phase1=" JLONG_FORMAT
1988                                  ", exit-phase2=" JLONG_FORMAT
1989                                  ", exit-phase3=" JLONG_FORMAT
1990                                  ", exit-phase4=" JLONG_FORMAT,
1991                                  get_thread_name(),
1992                                  _timer_exit_phase1.milliseconds(),
1993                                  _timer_exit_phase2.milliseconds(),
1994                                  _timer_exit_phase3.milliseconds(),
1995                                  _timer_exit_phase4.milliseconds());
1996   }
1997 }
1998 
1999 void JavaThread::cleanup_failed_attach_current_thread() {
2000   if (active_handles() != NULL) {
2001     JNIHandleBlock* block = active_handles();
2002     set_active_handles(NULL);
2003     JNIHandleBlock::release_block(block);
2004   }
2005 
2006   if (free_handle_block() != NULL) {
2007     JNIHandleBlock* block = free_handle_block();
2008     set_free_handle_block(NULL);
2009     JNIHandleBlock::release_block(block);
2010   }
2011 
2012   // These have to be removed while this is still a valid thread.
2013   remove_stack_guard_pages();
2014 
2015   if (UseTLAB) {
2016     tlab().make_parsable(true);  // retire TLAB, if any
2017   }
2018 
2019   BarrierSet::barrier_set()->on_thread_detach(this);
2020 
2021   Threads::remove(this);
2022   this->smr_delete();
2023 }
2024 
2025 JavaThread* JavaThread::active() {
2026   Thread* thread = Thread::current();
2027   if (thread->is_Java_thread()) {
2028     return (JavaThread*) thread;
2029   } else {
2030     assert(thread->is_VM_thread(), "this must be a vm thread");
2031     VM_Operation* op = ((VMThread*) thread)->vm_operation();
2032     JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2033     assert(ret->is_Java_thread(), "must be a Java thread");
2034     return ret;
2035   }
2036 }
2037 
2038 bool JavaThread::is_lock_owned(address adr) const {
2039   if (Thread::is_lock_owned(adr)) return true;
2040 
2041   for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2042     if (chunk->contains(adr)) return true;
2043   }
2044 
2045   return false;
2046 }
2047 
2048 
2049 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2050   chunk->set_next(monitor_chunks());
2051   set_monitor_chunks(chunk);
2052 }
2053 
2054 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2055   guarantee(monitor_chunks() != NULL, "must be non empty");
2056   if (monitor_chunks() == chunk) {
2057     set_monitor_chunks(chunk->next());
2058   } else {
2059     MonitorChunk* prev = monitor_chunks();
2060     while (prev->next() != chunk) prev = prev->next();
2061     prev->set_next(chunk->next());
2062   }
2063 }
2064 
2065 // JVM support.
2066 
2067 // Note: this function shouldn't block if it's called in
2068 // _thread_in_native_trans state (such as from
2069 // check_special_condition_for_native_trans()).
2070 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2071 
2072   if (has_last_Java_frame() && has_async_condition()) {
2073     // If we are at a polling page safepoint (not a poll return)
2074     // then we must defer async exception because live registers
2075     // will be clobbered by the exception path. Poll return is
2076     // ok because the call we a returning from already collides
2077     // with exception handling registers and so there is no issue.
2078     // (The exception handling path kills call result registers but
2079     //  this is ok since the exception kills the result anyway).
2080 
2081     if (is_at_poll_safepoint()) {
2082       // if the code we are returning to has deoptimized we must defer
2083       // the exception otherwise live registers get clobbered on the
2084       // exception path before deoptimization is able to retrieve them.
2085       //
2086       RegisterMap map(this, false);
2087       frame caller_fr = last_frame().sender(&map);
2088       assert(caller_fr.is_compiled_frame(), "what?");
2089       if (caller_fr.is_deoptimized_frame()) {
2090         log_info(exceptions)("deferred async exception at compiled safepoint");
2091         return;
2092       }
2093     }
2094   }
2095 
2096   JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2097   if (condition == _no_async_condition) {
2098     // Conditions have changed since has_special_runtime_exit_condition()
2099     // was called:
2100     // - if we were here only because of an external suspend request,
2101     //   then that was taken care of above (or cancelled) so we are done
2102     // - if we were here because of another async request, then it has
2103     //   been cleared between the has_special_runtime_exit_condition()
2104     //   and now so again we are done
2105     return;
2106   }
2107 
2108   // Check for pending async. exception
2109   if (_pending_async_exception != NULL) {
2110     // Only overwrite an already pending exception, if it is not a threadDeath.
2111     if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2112 
2113       // We cannot call Exceptions::_throw(...) here because we cannot block
2114       set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2115 
2116       LogTarget(Info, exceptions) lt;
2117       if (lt.is_enabled()) {
2118         ResourceMark rm;
2119         LogStream ls(lt);
2120         ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2121           if (has_last_Java_frame()) {
2122             frame f = last_frame();
2123            ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2124           }
2125         ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2126       }
2127       _pending_async_exception = NULL;
2128       clear_has_async_exception();
2129     }
2130   }
2131 
2132   if (check_unsafe_error &&
2133       condition == _async_unsafe_access_error && !has_pending_exception()) {
2134     condition = _no_async_condition;  // done
2135     switch (thread_state()) {
2136     case _thread_in_vm: {
2137       JavaThread* THREAD = this;
2138       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2139     }
2140     case _thread_in_native: {
2141       ThreadInVMfromNative tiv(this);
2142       JavaThread* THREAD = this;
2143       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2144     }
2145     case _thread_in_Java: {
2146       ThreadInVMfromJava tiv(this);
2147       JavaThread* THREAD = this;
2148       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2149     }
2150     default:
2151       ShouldNotReachHere();
2152     }
2153   }
2154 
2155   assert(condition == _no_async_condition || has_pending_exception() ||
2156          (!check_unsafe_error && condition == _async_unsafe_access_error),
2157          "must have handled the async condition, if no exception");
2158 }
2159 
2160 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2161   //
2162   // Check for pending external suspend. Internal suspend requests do
2163   // not use handle_special_runtime_exit_condition().
2164   // If JNIEnv proxies are allowed, don't self-suspend if the target
2165   // thread is not the current thread. In older versions of jdbx, jdbx
2166   // threads could call into the VM with another thread's JNIEnv so we
2167   // can be here operating on behalf of a suspended thread (4432884).
2168   bool do_self_suspend = is_external_suspend_with_lock();
2169   if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2170     //
2171     // Because thread is external suspended the safepoint code will count
2172     // thread as at a safepoint. This can be odd because we can be here
2173     // as _thread_in_Java which would normally transition to _thread_blocked
2174     // at a safepoint. We would like to mark the thread as _thread_blocked
2175     // before calling java_suspend_self like all other callers of it but
2176     // we must then observe proper safepoint protocol. (We can't leave
2177     // _thread_blocked with a safepoint in progress). However we can be
2178     // here as _thread_in_native_trans so we can't use a normal transition
2179     // constructor/destructor pair because they assert on that type of
2180     // transition. We could do something like:
2181     //
2182     // JavaThreadState state = thread_state();
2183     // set_thread_state(_thread_in_vm);
2184     // {
2185     //   ThreadBlockInVM tbivm(this);
2186     //   java_suspend_self()
2187     // }
2188     // set_thread_state(_thread_in_vm_trans);
2189     // if (safepoint) block;
2190     // set_thread_state(state);
2191     //
2192     // but that is pretty messy. Instead we just go with the way the
2193     // code has worked before and note that this is the only path to
2194     // java_suspend_self that doesn't put the thread in _thread_blocked
2195     // mode.
2196 
2197     frame_anchor()->make_walkable(this);
2198     java_suspend_self();
2199 
2200     // We might be here for reasons in addition to the self-suspend request
2201     // so check for other async requests.
2202   }
2203 
2204   if (check_asyncs) {
2205     check_and_handle_async_exceptions();
2206   }
2207 
2208   JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);)
2209 }
2210 
2211 void JavaThread::send_thread_stop(oop java_throwable)  {
2212   assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2213   assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2214   assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2215 
2216   // Do not throw asynchronous exceptions against the compiler thread
2217   // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2218   if (!can_call_java()) return;
2219 
2220   {
2221     // Actually throw the Throwable against the target Thread - however
2222     // only if there is no thread death exception installed already.
2223     if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2224       // If the topmost frame is a runtime stub, then we are calling into
2225       // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2226       // must deoptimize the caller before continuing, as the compiled  exception handler table
2227       // may not be valid
2228       if (has_last_Java_frame()) {
2229         frame f = last_frame();
2230         if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2231           // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2232           RegisterMap reg_map(this, UseBiasedLocking);
2233           frame compiled_frame = f.sender(&reg_map);
2234           if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2235             Deoptimization::deoptimize(this, compiled_frame, &reg_map);
2236           }
2237         }
2238       }
2239 
2240       // Set async. pending exception in thread.
2241       set_pending_async_exception(java_throwable);
2242 
2243       if (log_is_enabled(Info, exceptions)) {
2244          ResourceMark rm;
2245         log_info(exceptions)("Pending Async. exception installed of type: %s",
2246                              InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2247       }
2248       // for AbortVMOnException flag
2249       Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2250     }
2251   }
2252 
2253 
2254   // Interrupt thread so it will wake up from a potential wait()
2255   Thread::interrupt(this);
2256 }
2257 
2258 // External suspension mechanism.
2259 //
2260 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2261 // to any VM_locks and it is at a transition
2262 // Self-suspension will happen on the transition out of the vm.
2263 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2264 //
2265 // Guarantees on return:
2266 //   + Target thread will not execute any new bytecode (that's why we need to
2267 //     force a safepoint)
2268 //   + Target thread will not enter any new monitors
2269 //
2270 void JavaThread::java_suspend() {
2271   ThreadsListHandle tlh;
2272   if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) {
2273     return;
2274   }
2275 
2276   { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2277     if (!is_external_suspend()) {
2278       // a racing resume has cancelled us; bail out now
2279       return;
2280     }
2281 
2282     // suspend is done
2283     uint32_t debug_bits = 0;
2284     // Warning: is_ext_suspend_completed() may temporarily drop the
2285     // SR_lock to allow the thread to reach a stable thread state if
2286     // it is currently in a transient thread state.
2287     if (is_ext_suspend_completed(false /* !called_by_wait */,
2288                                  SuspendRetryDelay, &debug_bits)) {
2289       return;
2290     }
2291   }
2292 
2293   VM_ThreadSuspend vm_suspend;
2294   VMThread::execute(&vm_suspend);
2295 }
2296 
2297 // Part II of external suspension.
2298 // A JavaThread self suspends when it detects a pending external suspend
2299 // request. This is usually on transitions. It is also done in places
2300 // where continuing to the next transition would surprise the caller,
2301 // e.g., monitor entry.
2302 //
2303 // Returns the number of times that the thread self-suspended.
2304 //
2305 // Note: DO NOT call java_suspend_self() when you just want to block current
2306 //       thread. java_suspend_self() is the second stage of cooperative
2307 //       suspension for external suspend requests and should only be used
2308 //       to complete an external suspend request.
2309 //
2310 int JavaThread::java_suspend_self() {
2311   int ret = 0;
2312 
2313   // we are in the process of exiting so don't suspend
2314   if (is_exiting()) {
2315     clear_external_suspend();
2316     return ret;
2317   }
2318 
2319   assert(_anchor.walkable() ||
2320          (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2321          "must have walkable stack");
2322 
2323   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2324 
2325   assert(!this->is_ext_suspended(),
2326          "a thread trying to self-suspend should not already be suspended");
2327 
2328   if (this->is_suspend_equivalent()) {
2329     // If we are self-suspending as a result of the lifting of a
2330     // suspend equivalent condition, then the suspend_equivalent
2331     // flag is not cleared until we set the ext_suspended flag so
2332     // that wait_for_ext_suspend_completion() returns consistent
2333     // results.
2334     this->clear_suspend_equivalent();
2335   }
2336 
2337   // A racing resume may have cancelled us before we grabbed SR_lock
2338   // above. Or another external suspend request could be waiting for us
2339   // by the time we return from SR_lock()->wait(). The thread
2340   // that requested the suspension may already be trying to walk our
2341   // stack and if we return now, we can change the stack out from under
2342   // it. This would be a "bad thing (TM)" and cause the stack walker
2343   // to crash. We stay self-suspended until there are no more pending
2344   // external suspend requests.
2345   while (is_external_suspend()) {
2346     ret++;
2347     this->set_ext_suspended();
2348 
2349     // _ext_suspended flag is cleared by java_resume()
2350     while (is_ext_suspended()) {
2351       this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2352     }
2353   }
2354 
2355   return ret;
2356 }
2357 
2358 #ifdef ASSERT
2359 // Verify the JavaThread has not yet been published in the Threads::list, and
2360 // hence doesn't need protection from concurrent access at this stage.
2361 void JavaThread::verify_not_published() {
2362   // Cannot create a ThreadsListHandle here and check !tlh.includes(this)
2363   // since an unpublished JavaThread doesn't participate in the
2364   // Thread-SMR protocol for keeping a ThreadsList alive.
2365   assert(!on_thread_list(), "JavaThread shouldn't have been published yet!");
2366 }
2367 #endif
2368 
2369 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2370 // progress or when _suspend_flags is non-zero.
2371 // Current thread needs to self-suspend if there is a suspend request and/or
2372 // block if a safepoint is in progress.
2373 // Async exception ISN'T checked.
2374 // Note only the ThreadInVMfromNative transition can call this function
2375 // directly and when thread state is _thread_in_native_trans
2376 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2377   assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2378 
2379   JavaThread *curJT = JavaThread::current();
2380   bool do_self_suspend = thread->is_external_suspend();
2381 
2382   assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2383 
2384   // If JNIEnv proxies are allowed, don't self-suspend if the target
2385   // thread is not the current thread. In older versions of jdbx, jdbx
2386   // threads could call into the VM with another thread's JNIEnv so we
2387   // can be here operating on behalf of a suspended thread (4432884).
2388   if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2389     JavaThreadState state = thread->thread_state();
2390 
2391     // We mark this thread_blocked state as a suspend-equivalent so
2392     // that a caller to is_ext_suspend_completed() won't be confused.
2393     // The suspend-equivalent state is cleared by java_suspend_self().
2394     thread->set_suspend_equivalent();
2395 
2396     // If the safepoint code sees the _thread_in_native_trans state, it will
2397     // wait until the thread changes to other thread state. There is no
2398     // guarantee on how soon we can obtain the SR_lock and complete the
2399     // self-suspend request. It would be a bad idea to let safepoint wait for
2400     // too long. Temporarily change the state to _thread_blocked to
2401     // let the VM thread know that this thread is ready for GC. The problem
2402     // of changing thread state is that safepoint could happen just after
2403     // java_suspend_self() returns after being resumed, and VM thread will
2404     // see the _thread_blocked state. We must check for safepoint
2405     // after restoring the state and make sure we won't leave while a safepoint
2406     // is in progress.
2407     thread->set_thread_state(_thread_blocked);
2408     thread->java_suspend_self();
2409     thread->set_thread_state(state);
2410 
2411     InterfaceSupport::serialize_thread_state_with_handler(thread);
2412   }
2413 
2414   SafepointMechanism::block_if_requested(curJT);
2415 
2416   if (thread->is_deopt_suspend()) {
2417     thread->clear_deopt_suspend();
2418     RegisterMap map(thread, false);
2419     frame f = thread->last_frame();
2420     while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2421       f = f.sender(&map);
2422     }
2423     if (f.id() == thread->must_deopt_id()) {
2424       thread->clear_must_deopt_id();
2425       f.deoptimize(thread);
2426     } else {
2427       fatal("missed deoptimization!");
2428     }
2429   }
2430 
2431   JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(thread);)
2432 }
2433 
2434 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2435 // progress or when _suspend_flags is non-zero.
2436 // Current thread needs to self-suspend if there is a suspend request and/or
2437 // block if a safepoint is in progress.
2438 // Also check for pending async exception (not including unsafe access error).
2439 // Note only the native==>VM/Java barriers can call this function and when
2440 // thread state is _thread_in_native_trans.
2441 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2442   check_safepoint_and_suspend_for_native_trans(thread);
2443 
2444   if (thread->has_async_exception()) {
2445     // We are in _thread_in_native_trans state, don't handle unsafe
2446     // access error since that may block.
2447     thread->check_and_handle_async_exceptions(false);
2448   }
2449 }
2450 
2451 // This is a variant of the normal
2452 // check_special_condition_for_native_trans with slightly different
2453 // semantics for use by critical native wrappers.  It does all the
2454 // normal checks but also performs the transition back into
2455 // thread_in_Java state.  This is required so that critical natives
2456 // can potentially block and perform a GC if they are the last thread
2457 // exiting the GCLocker.
2458 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2459   check_special_condition_for_native_trans(thread);
2460 
2461   // Finish the transition
2462   thread->set_thread_state(_thread_in_Java);
2463 
2464   if (thread->do_critical_native_unlock()) {
2465     ThreadInVMfromJavaNoAsyncException tiv(thread);
2466     GCLocker::unlock_critical(thread);
2467     thread->clear_critical_native_unlock();
2468   }
2469 }
2470 
2471 // We need to guarantee the Threads_lock here, since resumes are not
2472 // allowed during safepoint synchronization
2473 // Can only resume from an external suspension
2474 void JavaThread::java_resume() {
2475   assert_locked_or_safepoint(Threads_lock);
2476 
2477   // Sanity check: thread is gone, has started exiting or the thread
2478   // was not externally suspended.
2479   ThreadsListHandle tlh;
2480   if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) {
2481     return;
2482   }
2483 
2484   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2485 
2486   clear_external_suspend();
2487 
2488   if (is_ext_suspended()) {
2489     clear_ext_suspended();
2490     SR_lock()->notify_all();
2491   }
2492 }
2493 
2494 size_t JavaThread::_stack_red_zone_size = 0;
2495 size_t JavaThread::_stack_yellow_zone_size = 0;
2496 size_t JavaThread::_stack_reserved_zone_size = 0;
2497 size_t JavaThread::_stack_shadow_zone_size = 0;
2498 
2499 void JavaThread::create_stack_guard_pages() {
2500   if (!os::uses_stack_guard_pages() ||
2501       _stack_guard_state != stack_guard_unused ||
2502       (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) {
2503       log_info(os, thread)("Stack guard page creation for thread "
2504                            UINTX_FORMAT " disabled", os::current_thread_id());
2505     return;
2506   }
2507   address low_addr = stack_end();
2508   size_t len = stack_guard_zone_size();
2509 
2510   assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2511   assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2512 
2513   int must_commit = os::must_commit_stack_guard_pages();
2514   // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2515 
2516   if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2517     log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2518     return;
2519   }
2520 
2521   if (os::guard_memory((char *) low_addr, len)) {
2522     _stack_guard_state = stack_guard_enabled;
2523   } else {
2524     log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2525       PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2526     if (os::uncommit_memory((char *) low_addr, len)) {
2527       log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2528     }
2529     return;
2530   }
2531 
2532   log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2533     PTR_FORMAT "-" PTR_FORMAT ".",
2534     os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2535 }
2536 
2537 void JavaThread::remove_stack_guard_pages() {
2538   assert(Thread::current() == this, "from different thread");
2539   if (_stack_guard_state == stack_guard_unused) return;
2540   address low_addr = stack_end();
2541   size_t len = stack_guard_zone_size();
2542 
2543   if (os::must_commit_stack_guard_pages()) {
2544     if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2545       _stack_guard_state = stack_guard_unused;
2546     } else {
2547       log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2548         PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2549       return;
2550     }
2551   } else {
2552     if (_stack_guard_state == stack_guard_unused) return;
2553     if (os::unguard_memory((char *) low_addr, len)) {
2554       _stack_guard_state = stack_guard_unused;
2555     } else {
2556       log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2557         PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2558       return;
2559     }
2560   }
2561 
2562   log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2563     PTR_FORMAT "-" PTR_FORMAT ".",
2564     os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2565 }
2566 
2567 void JavaThread::enable_stack_reserved_zone() {
2568   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2569   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2570 
2571   // The base notation is from the stack's point of view, growing downward.
2572   // We need to adjust it to work correctly with guard_memory()
2573   address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2574 
2575   guarantee(base < stack_base(),"Error calculating stack reserved zone");
2576   guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2577 
2578   if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2579     _stack_guard_state = stack_guard_enabled;
2580   } else {
2581     warning("Attempt to guard stack reserved zone failed.");
2582   }
2583   enable_register_stack_guard();
2584 }
2585 
2586 void JavaThread::disable_stack_reserved_zone() {
2587   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2588   assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2589 
2590   // Simply return if called for a thread that does not use guard pages.
2591   if (_stack_guard_state == stack_guard_unused) return;
2592 
2593   // The base notation is from the stack's point of view, growing downward.
2594   // We need to adjust it to work correctly with guard_memory()
2595   address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2596 
2597   if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2598     _stack_guard_state = stack_guard_reserved_disabled;
2599   } else {
2600     warning("Attempt to unguard stack reserved zone failed.");
2601   }
2602   disable_register_stack_guard();
2603 }
2604 
2605 void JavaThread::enable_stack_yellow_reserved_zone() {
2606   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2607   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2608 
2609   // The base notation is from the stacks point of view, growing downward.
2610   // We need to adjust it to work correctly with guard_memory()
2611   address base = stack_red_zone_base();
2612 
2613   guarantee(base < stack_base(), "Error calculating stack yellow zone");
2614   guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2615 
2616   if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2617     _stack_guard_state = stack_guard_enabled;
2618   } else {
2619     warning("Attempt to guard stack yellow zone failed.");
2620   }
2621   enable_register_stack_guard();
2622 }
2623 
2624 void JavaThread::disable_stack_yellow_reserved_zone() {
2625   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2626   assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2627 
2628   // Simply return if called for a thread that does not use guard pages.
2629   if (_stack_guard_state == stack_guard_unused) return;
2630 
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   address base = stack_red_zone_base();
2634 
2635   if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2636     _stack_guard_state = stack_guard_yellow_reserved_disabled;
2637   } else {
2638     warning("Attempt to unguard stack yellow zone failed.");
2639   }
2640   disable_register_stack_guard();
2641 }
2642 
2643 void JavaThread::enable_stack_red_zone() {
2644   // The base notation is from the stacks point of view, growing downward.
2645   // We need to adjust it to work correctly with guard_memory()
2646   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2647   address base = stack_red_zone_base() - stack_red_zone_size();
2648 
2649   guarantee(base < stack_base(), "Error calculating stack red zone");
2650   guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2651 
2652   if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2653     warning("Attempt to guard stack red zone failed.");
2654   }
2655 }
2656 
2657 void JavaThread::disable_stack_red_zone() {
2658   // The base notation is from the stacks point of view, growing downward.
2659   // We need to adjust it to work correctly with guard_memory()
2660   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2661   address base = stack_red_zone_base() - stack_red_zone_size();
2662   if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2663     warning("Attempt to unguard stack red zone failed.");
2664   }
2665 }
2666 
2667 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2668   // ignore is there is no stack
2669   if (!has_last_Java_frame()) return;
2670   // traverse the stack frames. Starts from top frame.
2671   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2672     frame* fr = fst.current();
2673     f(fr, fst.register_map());
2674   }
2675 }
2676 
2677 
2678 #ifndef PRODUCT
2679 // Deoptimization
2680 // Function for testing deoptimization
2681 void JavaThread::deoptimize() {
2682   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2683   StackFrameStream fst(this, UseBiasedLocking);
2684   bool deopt = false;           // Dump stack only if a deopt actually happens.
2685   bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2686   // Iterate over all frames in the thread and deoptimize
2687   for (; !fst.is_done(); fst.next()) {
2688     if (fst.current()->can_be_deoptimized()) {
2689 
2690       if (only_at) {
2691         // Deoptimize only at particular bcis.  DeoptimizeOnlyAt
2692         // consists of comma or carriage return separated numbers so
2693         // search for the current bci in that string.
2694         address pc = fst.current()->pc();
2695         nmethod* nm =  (nmethod*) fst.current()->cb();
2696         ScopeDesc* sd = nm->scope_desc_at(pc);
2697         char buffer[8];
2698         jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2699         size_t len = strlen(buffer);
2700         const char * found = strstr(DeoptimizeOnlyAt, buffer);
2701         while (found != NULL) {
2702           if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2703               (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2704             // Check that the bci found is bracketed by terminators.
2705             break;
2706           }
2707           found = strstr(found + 1, buffer);
2708         }
2709         if (!found) {
2710           continue;
2711         }
2712       }
2713 
2714       if (DebugDeoptimization && !deopt) {
2715         deopt = true; // One-time only print before deopt
2716         tty->print_cr("[BEFORE Deoptimization]");
2717         trace_frames();
2718         trace_stack();
2719       }
2720       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2721     }
2722   }
2723 
2724   if (DebugDeoptimization && deopt) {
2725     tty->print_cr("[AFTER Deoptimization]");
2726     trace_frames();
2727   }
2728 }
2729 
2730 
2731 // Make zombies
2732 void JavaThread::make_zombies() {
2733   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2734     if (fst.current()->can_be_deoptimized()) {
2735       // it is a Java nmethod
2736       nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2737       nm->make_not_entrant();
2738     }
2739   }
2740 }
2741 #endif // PRODUCT
2742 
2743 
2744 void JavaThread::deoptimized_wrt_marked_nmethods() {
2745   if (!has_last_Java_frame()) return;
2746   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2747   StackFrameStream fst(this, UseBiasedLocking);
2748   for (; !fst.is_done(); fst.next()) {
2749     if (fst.current()->should_be_deoptimized()) {
2750       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2751     }
2752   }
2753 }
2754 
2755 
2756 // If the caller is a NamedThread, then remember, in the current scope,
2757 // the given JavaThread in its _processed_thread field.
2758 class RememberProcessedThread: public StackObj {
2759   NamedThread* _cur_thr;
2760  public:
2761   RememberProcessedThread(JavaThread* jthr) {
2762     Thread* thread = Thread::current();
2763     if (thread->is_Named_thread()) {
2764       _cur_thr = (NamedThread *)thread;
2765       _cur_thr->set_processed_thread(jthr);
2766     } else {
2767       _cur_thr = NULL;
2768     }
2769   }
2770 
2771   ~RememberProcessedThread() {
2772     if (_cur_thr) {
2773       _cur_thr->set_processed_thread(NULL);
2774     }
2775   }
2776 };
2777 
2778 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2779   // Verify that the deferred card marks have been flushed.
2780   assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2781 
2782   // Traverse the GCHandles
2783   Thread::oops_do(f, cf);
2784 
2785   JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);)
2786 
2787   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2788          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2789 
2790   if (has_last_Java_frame()) {
2791     // Record JavaThread to GC thread
2792     RememberProcessedThread rpt(this);
2793 
2794     // Traverse the privileged stack
2795     if (_privileged_stack_top != NULL) {
2796       _privileged_stack_top->oops_do(f);
2797     }
2798 
2799     // traverse the registered growable array
2800     if (_array_for_gc != NULL) {
2801       for (int index = 0; index < _array_for_gc->length(); index++) {
2802         f->do_oop(_array_for_gc->adr_at(index));
2803       }
2804     }
2805 
2806     // Traverse the monitor chunks
2807     for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2808       chunk->oops_do(f);
2809     }
2810 
2811     // Traverse the execution stack
2812     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2813       fst.current()->oops_do(f, cf, fst.register_map());
2814     }
2815   }
2816 
2817   // callee_target is never live across a gc point so NULL it here should
2818   // it still contain a methdOop.
2819 
2820   set_callee_target(NULL);
2821 
2822   assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2823   // If we have deferred set_locals there might be oops waiting to be
2824   // written
2825   GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2826   if (list != NULL) {
2827     for (int i = 0; i < list->length(); i++) {
2828       list->at(i)->oops_do(f);
2829     }
2830   }
2831 
2832   // Traverse instance variables at the end since the GC may be moving things
2833   // around using this function
2834   f->do_oop((oop*) &_threadObj);
2835   f->do_oop((oop*) &_vm_result);
2836   f->do_oop((oop*) &_exception_oop);
2837   f->do_oop((oop*) &_pending_async_exception);
2838 
2839   if (jvmti_thread_state() != NULL) {
2840     jvmti_thread_state()->oops_do(f);
2841   }
2842 }
2843 
2844 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2845   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2846          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2847 
2848   if (has_last_Java_frame()) {
2849     // Traverse the execution stack
2850     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2851       fst.current()->nmethods_do(cf);
2852     }
2853   }
2854 }
2855 
2856 void JavaThread::metadata_do(void f(Metadata*)) {
2857   if (has_last_Java_frame()) {
2858     // Traverse the execution stack to call f() on the methods in the stack
2859     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2860       fst.current()->metadata_do(f);
2861     }
2862   } else if (is_Compiler_thread()) {
2863     // need to walk ciMetadata in current compile tasks to keep alive.
2864     CompilerThread* ct = (CompilerThread*)this;
2865     if (ct->env() != NULL) {
2866       ct->env()->metadata_do(f);
2867     }
2868     CompileTask* task = ct->task();
2869     if (task != NULL) {
2870       task->metadata_do(f);
2871     }
2872   }
2873 }
2874 
2875 // Printing
2876 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2877   switch (_thread_state) {
2878   case _thread_uninitialized:     return "_thread_uninitialized";
2879   case _thread_new:               return "_thread_new";
2880   case _thread_new_trans:         return "_thread_new_trans";
2881   case _thread_in_native:         return "_thread_in_native";
2882   case _thread_in_native_trans:   return "_thread_in_native_trans";
2883   case _thread_in_vm:             return "_thread_in_vm";
2884   case _thread_in_vm_trans:       return "_thread_in_vm_trans";
2885   case _thread_in_Java:           return "_thread_in_Java";
2886   case _thread_in_Java_trans:     return "_thread_in_Java_trans";
2887   case _thread_blocked:           return "_thread_blocked";
2888   case _thread_blocked_trans:     return "_thread_blocked_trans";
2889   default:                        return "unknown thread state";
2890   }
2891 }
2892 
2893 #ifndef PRODUCT
2894 void JavaThread::print_thread_state_on(outputStream *st) const {
2895   st->print_cr("   JavaThread state: %s", _get_thread_state_name(_thread_state));
2896 };
2897 void JavaThread::print_thread_state() const {
2898   print_thread_state_on(tty);
2899 }
2900 #endif // PRODUCT
2901 
2902 // Called by Threads::print() for VM_PrintThreads operation
2903 void JavaThread::print_on(outputStream *st) const {
2904   st->print_raw("\"");
2905   st->print_raw(get_thread_name());
2906   st->print_raw("\" ");
2907   oop thread_oop = threadObj();
2908   if (thread_oop != NULL) {
2909     st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
2910     if (java_lang_Thread::is_daemon(thread_oop))  st->print("daemon ");
2911     st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2912   }
2913   Thread::print_on(st);
2914   // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2915   st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2916   if (thread_oop != NULL) {
2917     st->print_cr("   java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2918   }
2919 #ifndef PRODUCT
2920   print_thread_state_on(st);
2921   _safepoint_state->print_on(st);
2922 #endif // PRODUCT
2923   if (is_Compiler_thread()) {
2924     CompileTask *task = ((CompilerThread*)this)->task();
2925     if (task != NULL) {
2926       st->print("   Compiling: ");
2927       task->print(st, NULL, true, false);
2928     } else {
2929       st->print("   No compile task");
2930     }
2931     st->cr();
2932   }
2933 }
2934 
2935 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2936   st->print("%s", get_thread_name_string(buf, buflen));
2937 }
2938 
2939 // Called by fatal error handler. The difference between this and
2940 // JavaThread::print() is that we can't grab lock or allocate memory.
2941 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2942   st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2943   oop thread_obj = threadObj();
2944   if (thread_obj != NULL) {
2945     if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2946   }
2947   st->print(" [");
2948   st->print("%s", _get_thread_state_name(_thread_state));
2949   if (osthread()) {
2950     st->print(", id=%d", osthread()->thread_id());
2951   }
2952   st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2953             p2i(stack_end()), p2i(stack_base()));
2954   st->print("]");
2955 
2956   ThreadsSMRSupport::print_info_on(this, st);
2957   return;
2958 }
2959 
2960 // Verification
2961 
2962 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2963 
2964 void JavaThread::verify() {
2965   // Verify oops in the thread.
2966   oops_do(&VerifyOopClosure::verify_oop, NULL);
2967 
2968   // Verify the stack frames.
2969   frames_do(frame_verify);
2970 }
2971 
2972 // CR 6300358 (sub-CR 2137150)
2973 // Most callers of this method assume that it can't return NULL but a
2974 // thread may not have a name whilst it is in the process of attaching to
2975 // the VM - see CR 6412693, and there are places where a JavaThread can be
2976 // seen prior to having it's threadObj set (eg JNI attaching threads and
2977 // if vm exit occurs during initialization). These cases can all be accounted
2978 // for such that this method never returns NULL.
2979 const char* JavaThread::get_thread_name() const {
2980 #ifdef ASSERT
2981   // early safepoints can hit while current thread does not yet have TLS
2982   if (!SafepointSynchronize::is_at_safepoint()) {
2983     Thread *cur = Thread::current();
2984     if (!(cur->is_Java_thread() && cur == this)) {
2985       // Current JavaThreads are allowed to get their own name without
2986       // the Threads_lock.
2987       assert_locked_or_safepoint(Threads_lock);
2988     }
2989   }
2990 #endif // ASSERT
2991   return get_thread_name_string();
2992 }
2993 
2994 // Returns a non-NULL representation of this thread's name, or a suitable
2995 // descriptive string if there is no set name
2996 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
2997   const char* name_str;
2998   oop thread_obj = threadObj();
2999   if (thread_obj != NULL) {
3000     oop name = java_lang_Thread::name(thread_obj);
3001     if (name != NULL) {
3002       if (buf == NULL) {
3003         name_str = java_lang_String::as_utf8_string(name);
3004       } else {
3005         name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3006       }
3007     } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3008       name_str = "<no-name - thread is attaching>";
3009     } else {
3010       name_str = Thread::name();
3011     }
3012   } else {
3013     name_str = Thread::name();
3014   }
3015   assert(name_str != NULL, "unexpected NULL thread name");
3016   return name_str;
3017 }
3018 
3019 
3020 const char* JavaThread::get_threadgroup_name() const {
3021   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3022   oop thread_obj = threadObj();
3023   if (thread_obj != NULL) {
3024     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3025     if (thread_group != NULL) {
3026       // ThreadGroup.name can be null
3027       return java_lang_ThreadGroup::name(thread_group);
3028     }
3029   }
3030   return NULL;
3031 }
3032 
3033 const char* JavaThread::get_parent_name() const {
3034   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3035   oop thread_obj = threadObj();
3036   if (thread_obj != NULL) {
3037     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3038     if (thread_group != NULL) {
3039       oop parent = java_lang_ThreadGroup::parent(thread_group);
3040       if (parent != NULL) {
3041         // ThreadGroup.name can be null
3042         return java_lang_ThreadGroup::name(parent);
3043       }
3044     }
3045   }
3046   return NULL;
3047 }
3048 
3049 ThreadPriority JavaThread::java_priority() const {
3050   oop thr_oop = threadObj();
3051   if (thr_oop == NULL) return NormPriority; // Bootstrapping
3052   ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3053   assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3054   return priority;
3055 }
3056 
3057 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3058 
3059   assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3060   // Link Java Thread object <-> C++ Thread
3061 
3062   // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3063   // and put it into a new Handle.  The Handle "thread_oop" can then
3064   // be used to pass the C++ thread object to other methods.
3065 
3066   // Set the Java level thread object (jthread) field of the
3067   // new thread (a JavaThread *) to C++ thread object using the
3068   // "thread_oop" handle.
3069 
3070   // Set the thread field (a JavaThread *) of the
3071   // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3072 
3073   Handle thread_oop(Thread::current(),
3074                     JNIHandles::resolve_non_null(jni_thread));
3075   assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3076          "must be initialized");
3077   set_threadObj(thread_oop());
3078   java_lang_Thread::set_thread(thread_oop(), this);
3079 
3080   if (prio == NoPriority) {
3081     prio = java_lang_Thread::priority(thread_oop());
3082     assert(prio != NoPriority, "A valid priority should be present");
3083   }
3084 
3085   // Push the Java priority down to the native thread; needs Threads_lock
3086   Thread::set_priority(this, prio);
3087 
3088   // Add the new thread to the Threads list and set it in motion.
3089   // We must have threads lock in order to call Threads::add.
3090   // It is crucial that we do not block before the thread is
3091   // added to the Threads list for if a GC happens, then the java_thread oop
3092   // will not be visited by GC.
3093   Threads::add(this);
3094 }
3095 
3096 oop JavaThread::current_park_blocker() {
3097   // Support for JSR-166 locks
3098   oop thread_oop = threadObj();
3099   if (thread_oop != NULL &&
3100       JDK_Version::current().supports_thread_park_blocker()) {
3101     return java_lang_Thread::park_blocker(thread_oop);
3102   }
3103   return NULL;
3104 }
3105 
3106 
3107 void JavaThread::print_stack_on(outputStream* st) {
3108   if (!has_last_Java_frame()) return;
3109   ResourceMark rm;
3110   HandleMark   hm;
3111 
3112   RegisterMap reg_map(this);
3113   vframe* start_vf = last_java_vframe(&reg_map);
3114   int count = 0;
3115   for (vframe* f = start_vf; f != NULL; f = f->sender()) {
3116     if (f->is_java_frame()) {
3117       javaVFrame* jvf = javaVFrame::cast(f);
3118       java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3119 
3120       // Print out lock information
3121       if (JavaMonitorsInStackTrace) {
3122         jvf->print_lock_info_on(st, count);
3123       }
3124     } else {
3125       // Ignore non-Java frames
3126     }
3127 
3128     // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
3129     count++;
3130     if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
3131   }
3132 }
3133 
3134 
3135 // JVMTI PopFrame support
3136 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3137   assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3138   if (in_bytes(size_in_bytes) != 0) {
3139     _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3140     _popframe_preserved_args_size = in_bytes(size_in_bytes);
3141     Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3142   }
3143 }
3144 
3145 void* JavaThread::popframe_preserved_args() {
3146   return _popframe_preserved_args;
3147 }
3148 
3149 ByteSize JavaThread::popframe_preserved_args_size() {
3150   return in_ByteSize(_popframe_preserved_args_size);
3151 }
3152 
3153 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3154   int sz = in_bytes(popframe_preserved_args_size());
3155   assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3156   return in_WordSize(sz / wordSize);
3157 }
3158 
3159 void JavaThread::popframe_free_preserved_args() {
3160   assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3161   FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3162   _popframe_preserved_args = NULL;
3163   _popframe_preserved_args_size = 0;
3164 }
3165 
3166 #ifndef PRODUCT
3167 
3168 void JavaThread::trace_frames() {
3169   tty->print_cr("[Describe stack]");
3170   int frame_no = 1;
3171   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3172     tty->print("  %d. ", frame_no++);
3173     fst.current()->print_value_on(tty, this);
3174     tty->cr();
3175   }
3176 }
3177 
3178 class PrintAndVerifyOopClosure: public OopClosure {
3179  protected:
3180   template <class T> inline void do_oop_work(T* p) {
3181     oop obj = RawAccess<>::oop_load(p);
3182     if (obj == NULL) return;
3183     tty->print(INTPTR_FORMAT ": ", p2i(p));
3184     if (oopDesc::is_oop_or_null(obj)) {
3185       if (obj->is_objArray()) {
3186         tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3187       } else {
3188         obj->print();
3189       }
3190     } else {
3191       tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3192     }
3193     tty->cr();
3194   }
3195  public:
3196   virtual void do_oop(oop* p) { do_oop_work(p); }
3197   virtual void do_oop(narrowOop* p)  { do_oop_work(p); }
3198 };
3199 
3200 
3201 static void oops_print(frame* f, const RegisterMap *map) {
3202   PrintAndVerifyOopClosure print;
3203   f->print_value();
3204   f->oops_do(&print, NULL, (RegisterMap*)map);
3205 }
3206 
3207 // Print our all the locations that contain oops and whether they are
3208 // valid or not.  This useful when trying to find the oldest frame
3209 // where an oop has gone bad since the frame walk is from youngest to
3210 // oldest.
3211 void JavaThread::trace_oops() {
3212   tty->print_cr("[Trace oops]");
3213   frames_do(oops_print);
3214 }
3215 
3216 
3217 #ifdef ASSERT
3218 // Print or validate the layout of stack frames
3219 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3220   ResourceMark rm;
3221   PRESERVE_EXCEPTION_MARK;
3222   FrameValues values;
3223   int frame_no = 0;
3224   for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3225     fst.current()->describe(values, ++frame_no);
3226     if (depth == frame_no) break;
3227   }
3228   if (validate_only) {
3229     values.validate();
3230   } else {
3231     tty->print_cr("[Describe stack layout]");
3232     values.print(this);
3233   }
3234 }
3235 #endif
3236 
3237 void JavaThread::trace_stack_from(vframe* start_vf) {
3238   ResourceMark rm;
3239   int vframe_no = 1;
3240   for (vframe* f = start_vf; f; f = f->sender()) {
3241     if (f->is_java_frame()) {
3242       javaVFrame::cast(f)->print_activation(vframe_no++);
3243     } else {
3244       f->print();
3245     }
3246     if (vframe_no > StackPrintLimit) {
3247       tty->print_cr("...<more frames>...");
3248       return;
3249     }
3250   }
3251 }
3252 
3253 
3254 void JavaThread::trace_stack() {
3255   if (!has_last_Java_frame()) return;
3256   ResourceMark rm;
3257   HandleMark   hm;
3258   RegisterMap reg_map(this);
3259   trace_stack_from(last_java_vframe(&reg_map));
3260 }
3261 
3262 
3263 #endif // PRODUCT
3264 
3265 
3266 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3267   assert(reg_map != NULL, "a map must be given");
3268   frame f = last_frame();
3269   for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3270     if (vf->is_java_frame()) return javaVFrame::cast(vf);
3271   }
3272   return NULL;
3273 }
3274 
3275 
3276 Klass* JavaThread::security_get_caller_class(int depth) {
3277   vframeStream vfst(this);
3278   vfst.security_get_caller_frame(depth);
3279   if (!vfst.at_end()) {
3280     return vfst.method()->method_holder();
3281   }
3282   return NULL;
3283 }
3284 
3285 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3286   assert(thread->is_Compiler_thread(), "must be compiler thread");
3287   CompileBroker::compiler_thread_loop();
3288 }
3289 
3290 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3291   NMethodSweeper::sweeper_loop();
3292 }
3293 
3294 // Create a CompilerThread
3295 CompilerThread::CompilerThread(CompileQueue* queue,
3296                                CompilerCounters* counters)
3297                                : JavaThread(&compiler_thread_entry) {
3298   _env   = NULL;
3299   _log   = NULL;
3300   _task  = NULL;
3301   _queue = queue;
3302   _counters = counters;
3303   _buffer_blob = NULL;
3304   _compiler = NULL;
3305 
3306   // Compiler uses resource area for compilation, let's bias it to mtCompiler
3307   resource_area()->bias_to(mtCompiler);
3308 
3309 #ifndef PRODUCT
3310   _ideal_graph_printer = NULL;
3311 #endif
3312 }
3313 
3314 CompilerThread::~CompilerThread() {
3315   // Delete objects which were allocated on heap.
3316   delete _counters;
3317 }
3318 
3319 bool CompilerThread::can_call_java() const {
3320   return _compiler != NULL && _compiler->is_jvmci();
3321 }
3322 
3323 // Create sweeper thread
3324 CodeCacheSweeperThread::CodeCacheSweeperThread()
3325 : JavaThread(&sweeper_thread_entry) {
3326   _scanned_compiled_method = NULL;
3327 }
3328 
3329 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3330   JavaThread::oops_do(f, 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 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3340   JavaThread::nmethods_do(cf);
3341   if (_scanned_compiled_method != NULL && cf != NULL) {
3342     // Safepoints can occur when the sweeper is scanning an nmethod so
3343     // process it here to make sure it isn't unloaded in the middle of
3344     // a scan.
3345     cf->do_code_blob(_scanned_compiled_method);
3346   }
3347 }
3348 
3349 
3350 // ======= Threads ========
3351 
3352 // The Threads class links together all active threads, and provides
3353 // operations over all threads. It is protected by the Threads_lock,
3354 // which is also used in other global contexts like safepointing.
3355 // ThreadsListHandles are used to safely perform operations on one
3356 // or more threads without the risk of the thread exiting during the
3357 // operation.
3358 //
3359 // Note: The Threads_lock is currently more widely used than we
3360 // would like. We are actively migrating Threads_lock uses to other
3361 // mechanisms in order to reduce Threads_lock contention.
3362 
3363 JavaThread* Threads::_thread_list = NULL;
3364 int         Threads::_number_of_threads = 0;
3365 int         Threads::_number_of_non_daemon_threads = 0;
3366 int         Threads::_return_code = 0;
3367 int         Threads::_thread_claim_parity = 0;
3368 size_t      JavaThread::_stack_size_at_create = 0;
3369 
3370 #ifdef ASSERT
3371 bool        Threads::_vm_complete = false;
3372 #endif
3373 
3374 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
3375   Prefetch::read((void*)addr, prefetch_interval);
3376   return *addr;
3377 }
3378 
3379 // Possibly the ugliest for loop the world has seen. C++ does not allow
3380 // multiple types in the declaration section of the for loop. In this case
3381 // we are only dealing with pointers and hence can cast them. It looks ugly
3382 // but macros are ugly and therefore it's fine to make things absurdly ugly.
3383 #define DO_JAVA_THREADS(LIST, X)                                                                                          \
3384     for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes,                           \
3385              *MACRO_list = (JavaThread*)(LIST),                                                                           \
3386              **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(),  \
3387              **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(),                                     \
3388              *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval);                 \
3389          MACRO_current_p != MACRO_end;                                                                                    \
3390          MACRO_current_p++,                                                                                               \
3391              X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval))
3392 
3393 // All JavaThreads
3394 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X)
3395 
3396 // All non-JavaThreads (i.e., every non-JavaThread in the system).
3397 void Threads::non_java_threads_do(ThreadClosure* tc) {
3398   // Someday we could have a table or list of all non-JavaThreads.
3399   // For now, just manually iterate through them.
3400   tc->do_thread(VMThread::vm_thread());
3401   if (Universe::heap() != NULL) {
3402     Universe::heap()->gc_threads_do(tc);
3403   }
3404   WatcherThread *wt = WatcherThread::watcher_thread();
3405   // Strictly speaking, the following NULL check isn't sufficient to make sure
3406   // the data for WatcherThread is still valid upon being examined. However,
3407   // considering that WatchThread terminates when the VM is on the way to
3408   // exit at safepoint, the chance of the above is extremely small. The right
3409   // way to prevent termination of WatcherThread would be to acquire
3410   // Terminator_lock, but we can't do that without violating the lock rank
3411   // checking in some cases.
3412   if (wt != NULL) {
3413     tc->do_thread(wt);
3414   }
3415 
3416 #if INCLUDE_JFR
3417   Thread* sampler_thread = Jfr::sampler_thread();
3418   if (sampler_thread != NULL) {
3419     tc->do_thread(sampler_thread);
3420   }
3421 
3422 #endif
3423 
3424   // If CompilerThreads ever become non-JavaThreads, add them here
3425 }
3426 
3427 // All JavaThreads
3428 void Threads::java_threads_do(ThreadClosure* tc) {
3429   assert_locked_or_safepoint(Threads_lock);
3430   // ALL_JAVA_THREADS iterates through all JavaThreads.
3431   ALL_JAVA_THREADS(p) {
3432     tc->do_thread(p);
3433   }
3434 }
3435 
3436 void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) {
3437   assert_locked_or_safepoint(Threads_lock);
3438   java_threads_do(tc);
3439   tc->do_thread(VMThread::vm_thread());
3440 }
3441 
3442 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system).
3443 void Threads::threads_do(ThreadClosure* tc) {
3444   assert_locked_or_safepoint(Threads_lock);
3445   java_threads_do(tc);
3446   non_java_threads_do(tc);
3447 }
3448 
3449 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
3450   int cp = Threads::thread_claim_parity();
3451   ALL_JAVA_THREADS(p) {
3452     if (p->claim_oops_do(is_par, cp)) {
3453       tc->do_thread(p);
3454     }
3455   }
3456   VMThread* vmt = VMThread::vm_thread();
3457   if (vmt->claim_oops_do(is_par, cp)) {
3458     tc->do_thread(vmt);
3459   }
3460 }
3461 
3462 // The system initialization in the library has three phases.
3463 //
3464 // Phase 1: java.lang.System class initialization
3465 //     java.lang.System is a primordial class loaded and initialized
3466 //     by the VM early during startup.  java.lang.System.<clinit>
3467 //     only does registerNatives and keeps the rest of the class
3468 //     initialization work later until thread initialization completes.
3469 //
3470 //     System.initPhase1 initializes the system properties, the static
3471 //     fields in, out, and err. Set up java signal handlers, OS-specific
3472 //     system settings, and thread group of the main thread.
3473 static void call_initPhase1(TRAPS) {
3474   Klass* klass =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3475   JavaValue result(T_VOID);
3476   JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3477                                          vmSymbols::void_method_signature(), CHECK);
3478 }
3479 
3480 // Phase 2. Module system initialization
3481 //     This will initialize the module system.  Only java.base classes
3482 //     can be loaded until phase 2 completes.
3483 //
3484 //     Call System.initPhase2 after the compiler initialization and jsr292
3485 //     classes get initialized because module initialization runs a lot of java
3486 //     code, that for performance reasons, should be compiled.  Also, this will
3487 //     enable the startup code to use lambda and other language features in this
3488 //     phase and onward.
3489 //
3490 //     After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3491 static void call_initPhase2(TRAPS) {
3492   TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3493 
3494   Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3495 
3496   JavaValue result(T_INT);
3497   JavaCallArguments args;
3498   args.push_int(DisplayVMOutputToStderr);
3499   args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3500   JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3501                                          vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3502   if (result.get_jint() != JNI_OK) {
3503     vm_exit_during_initialization(); // no message or exception
3504   }
3505 
3506   universe_post_module_init();
3507 }
3508 
3509 // Phase 3. final setup - set security manager, system class loader and TCCL
3510 //
3511 //     This will instantiate and set the security manager, set the system class
3512 //     loader as well as the thread context class loader.  The security manager
3513 //     and system class loader may be a custom class loaded from -Xbootclasspath/a,
3514 //     other modules or the application's classpath.
3515 static void call_initPhase3(TRAPS) {
3516   Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3517   JavaValue result(T_VOID);
3518   JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3519                                          vmSymbols::void_method_signature(), CHECK);
3520 }
3521 
3522 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3523   TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3524 
3525   if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3526     create_vm_init_libraries();
3527   }
3528 
3529   initialize_class(vmSymbols::java_lang_String(), CHECK);
3530 
3531   // Inject CompactStrings value after the static initializers for String ran.
3532   java_lang_String::set_compact_strings(CompactStrings);
3533 
3534   // Initialize java_lang.System (needed before creating the thread)
3535   initialize_class(vmSymbols::java_lang_System(), CHECK);
3536   // The VM creates & returns objects of this class. Make sure it's initialized.
3537   initialize_class(vmSymbols::java_lang_Class(), CHECK);
3538   initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3539   Handle thread_group = create_initial_thread_group(CHECK);
3540   Universe::set_main_thread_group(thread_group());
3541   initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3542   oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3543   main_thread->set_threadObj(thread_object);
3544   // Set thread status to running since main thread has
3545   // been started and running.
3546   java_lang_Thread::set_thread_status(thread_object,
3547                                       java_lang_Thread::RUNNABLE);
3548 
3549   // The VM creates objects of this class.
3550   initialize_class(vmSymbols::java_lang_Module(), CHECK);
3551 
3552   // The VM preresolves methods to these classes. Make sure that they get initialized
3553   initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3554   initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3555 
3556   // Phase 1 of the system initialization in the library, java.lang.System class initialization
3557   call_initPhase1(CHECK);
3558 
3559   // get the Java runtime name after java.lang.System is initialized
3560   JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3561   JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3562 
3563   // an instance of OutOfMemory exception has been allocated earlier
3564   initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3565   initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3566   initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3567   initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3568   initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3569   initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3570   initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3571   initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3572 }
3573 
3574 void Threads::initialize_jsr292_core_classes(TRAPS) {
3575   TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3576 
3577   initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3578   initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3579   initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3580   initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3581 }
3582 
3583 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3584   extern void JDK_Version_init();
3585 
3586   // Preinitialize version info.
3587   VM_Version::early_initialize();
3588 
3589   // Check version
3590   if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3591 
3592   // Initialize library-based TLS
3593   ThreadLocalStorage::init();
3594 
3595   // Initialize the output stream module
3596   ostream_init();
3597 
3598   // Process java launcher properties.
3599   Arguments::process_sun_java_launcher_properties(args);
3600 
3601   // Initialize the os module
3602   os::init();
3603 
3604   // Record VM creation timing statistics
3605   TraceVmCreationTime create_vm_timer;
3606   create_vm_timer.start();
3607 
3608   // Initialize system properties.
3609   Arguments::init_system_properties();
3610 
3611   // So that JDK version can be used as a discriminator when parsing arguments
3612   JDK_Version_init();
3613 
3614   // Update/Initialize System properties after JDK version number is known
3615   Arguments::init_version_specific_system_properties();
3616 
3617   // Make sure to initialize log configuration *before* parsing arguments
3618   LogConfiguration::initialize(create_vm_timer.begin_time());
3619 
3620   // Parse arguments
3621   // Note: this internally calls os::init_container_support()
3622   jint parse_result = Arguments::parse(args);
3623   if (parse_result != JNI_OK) return parse_result;
3624 
3625   os::init_before_ergo();
3626 
3627   jint ergo_result = Arguments::apply_ergo();
3628   if (ergo_result != JNI_OK) return ergo_result;
3629 
3630   // Final check of all ranges after ergonomics which may change values.
3631   if (!JVMFlagRangeList::check_ranges()) {
3632     return JNI_EINVAL;
3633   }
3634 
3635   // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3636   bool constraint_result = JVMFlagConstraintList::check_constraints(JVMFlagConstraint::AfterErgo);
3637   if (!constraint_result) {
3638     return JNI_EINVAL;
3639   }
3640 
3641   JVMFlagWriteableList::mark_startup();
3642 
3643   if (PauseAtStartup) {
3644     os::pause();
3645   }
3646 
3647   HOTSPOT_VM_INIT_BEGIN();
3648 
3649   // Timing (must come after argument parsing)
3650   TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3651 
3652 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT
3653   // Initialize assert poison page mechanism.
3654   if (ShowRegistersOnAssert) {
3655     initialize_assert_poison();
3656   }
3657 #endif // CAN_SHOW_REGISTERS_ON_ASSERT
3658 
3659   // Initialize the os module after parsing the args
3660   jint os_init_2_result = os::init_2();
3661   if (os_init_2_result != JNI_OK) return os_init_2_result;
3662 
3663   SafepointMechanism::initialize();
3664 
3665   jint adjust_after_os_result = Arguments::adjust_after_os();
3666   if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3667 
3668   // Initialize output stream logging
3669   ostream_init_log();
3670 
3671   // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3672   // Must be before create_vm_init_agents()
3673   if (Arguments::init_libraries_at_startup()) {
3674     convert_vm_init_libraries_to_agents();
3675   }
3676 
3677   // Launch -agentlib/-agentpath and converted -Xrun agents
3678   if (Arguments::init_agents_at_startup()) {
3679     create_vm_init_agents();
3680   }
3681 
3682   // Initialize Threads state
3683   _thread_list = NULL;
3684   _number_of_threads = 0;
3685   _number_of_non_daemon_threads = 0;
3686 
3687   // Initialize global data structures and create system classes in heap
3688   vm_init_globals();
3689 
3690 #if INCLUDE_JVMCI
3691   if (JVMCICounterSize > 0) {
3692     JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3693     memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3694   } else {
3695     JavaThread::_jvmci_old_thread_counters = NULL;
3696   }
3697 #endif // INCLUDE_JVMCI
3698 
3699   // Attach the main thread to this os thread
3700   JavaThread* main_thread = new JavaThread();
3701   main_thread->set_thread_state(_thread_in_vm);
3702   main_thread->initialize_thread_current();
3703   // must do this before set_active_handles
3704   main_thread->record_stack_base_and_size();
3705   main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3706 
3707   if (!main_thread->set_as_starting_thread()) {
3708     vm_shutdown_during_initialization(
3709                                       "Failed necessary internal allocation. Out of swap space");
3710     main_thread->smr_delete();
3711     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3712     return JNI_ENOMEM;
3713   }
3714 
3715   // Enable guard page *after* os::create_main_thread(), otherwise it would
3716   // crash Linux VM, see notes in os_linux.cpp.
3717   main_thread->create_stack_guard_pages();
3718 
3719   // Initialize Java-Level synchronization subsystem
3720   ObjectMonitor::Initialize();
3721 
3722   // Initialize global modules
3723   jint status = init_globals();
3724   if (status != JNI_OK) {
3725     main_thread->smr_delete();
3726     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3727     return status;
3728   }
3729 
3730   JFR_ONLY(Jfr::on_vm_init();)
3731 
3732   // Should be done after the heap is fully created
3733   main_thread->cache_global_variables();
3734 
3735   HandleMark hm;
3736 
3737   { MutexLocker mu(Threads_lock);
3738     Threads::add(main_thread);
3739   }
3740 
3741   // Any JVMTI raw monitors entered in onload will transition into
3742   // real raw monitor. VM is setup enough here for raw monitor enter.
3743   JvmtiExport::transition_pending_onload_raw_monitors();
3744 
3745   // Create the VMThread
3746   { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3747 
3748   VMThread::create();
3749     Thread* vmthread = VMThread::vm_thread();
3750 
3751     if (!os::create_thread(vmthread, os::vm_thread)) {
3752       vm_exit_during_initialization("Cannot create VM thread. "
3753                                     "Out of system resources.");
3754     }
3755 
3756     // Wait for the VM thread to become ready, and VMThread::run to initialize
3757     // Monitors can have spurious returns, must always check another state flag
3758     {
3759       MutexLocker ml(Notify_lock);
3760       os::start_thread(vmthread);
3761       while (vmthread->active_handles() == NULL) {
3762         Notify_lock->wait();
3763       }
3764     }
3765   }
3766 
3767   assert(Universe::is_fully_initialized(), "not initialized");
3768   if (VerifyDuringStartup) {
3769     // Make sure we're starting with a clean slate.
3770     VM_Verify verify_op;
3771     VMThread::execute(&verify_op);
3772   }
3773 
3774   Thread* THREAD = Thread::current();
3775 
3776   // Always call even when there are not JVMTI environments yet, since environments
3777   // may be attached late and JVMTI must track phases of VM execution
3778   JvmtiExport::enter_early_start_phase();
3779 
3780   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3781   JvmtiExport::post_early_vm_start();
3782 
3783   initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3784 
3785   // We need this to update the java.vm.info property in case any flags used
3786   // to initially define it have been changed. This is needed for both CDS and
3787   // AOT, since UseSharedSpaces and UseAOT may be changed after java.vm.info
3788   // is initially computed. See Abstract_VM_Version::vm_info_string().
3789   reset_vm_info_property(CHECK_JNI_ERR);
3790 
3791   quicken_jni_functions();
3792 
3793   // No more stub generation allowed after that point.
3794   StubCodeDesc::freeze();
3795 
3796   // Set flag that basic initialization has completed. Used by exceptions and various
3797   // debug stuff, that does not work until all basic classes have been initialized.
3798   set_init_completed();
3799 
3800   LogConfiguration::post_initialize();
3801   Metaspace::post_initialize();
3802 
3803   HOTSPOT_VM_INIT_END();
3804 
3805   // record VM initialization completion time
3806 #if INCLUDE_MANAGEMENT
3807   Management::record_vm_init_completed();
3808 #endif // INCLUDE_MANAGEMENT
3809 
3810   // Signal Dispatcher needs to be started before VMInit event is posted
3811   os::initialize_jdk_signal_support(CHECK_JNI_ERR);
3812 
3813   // Start Attach Listener if +StartAttachListener or it can't be started lazily
3814   if (!DisableAttachMechanism) {
3815     AttachListener::vm_start();
3816     if (StartAttachListener || AttachListener::init_at_startup()) {
3817       AttachListener::init();
3818     }
3819   }
3820 
3821   // Launch -Xrun agents
3822   // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3823   // back-end can launch with -Xdebug -Xrunjdwp.
3824   if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3825     create_vm_init_libraries();
3826   }
3827 
3828   if (CleanChunkPoolAsync) {
3829     Chunk::start_chunk_pool_cleaner_task();
3830   }
3831 
3832   // initialize compiler(s)
3833 #if defined(COMPILER1) || COMPILER2_OR_JVMCI
3834 #if INCLUDE_JVMCI
3835   bool force_JVMCI_intialization = false;
3836   if (EnableJVMCI) {
3837     // Initialize JVMCI eagerly when it is explicitly requested.
3838     // Or when JVMCIPrintProperties is enabled.
3839     // The JVMCI Java initialization code will read this flag and
3840     // do the printing if it's set.
3841     force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties;
3842 
3843     if (!force_JVMCI_intialization) {
3844       // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3845       // compilations via JVMCI will not actually block until JVMCI is initialized.
3846       force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3847     }
3848   }
3849 #endif
3850   CompileBroker::compilation_init_phase1(CHECK_JNI_ERR);
3851   // Postpone completion of compiler initialization to after JVMCI
3852   // is initialized to avoid timeouts of blocking compilations.
3853   if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) {
3854     CompileBroker::compilation_init_phase2();
3855   }
3856 #endif
3857 
3858   // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3859   // It is done after compilers are initialized, because otherwise compilations of
3860   // signature polymorphic MH intrinsics can be missed
3861   // (see SystemDictionary::find_method_handle_intrinsic).
3862   initialize_jsr292_core_classes(CHECK_JNI_ERR);
3863 
3864   // This will initialize the module system.  Only java.base classes can be
3865   // loaded until phase 2 completes
3866   call_initPhase2(CHECK_JNI_ERR);
3867 
3868   // Always call even when there are not JVMTI environments yet, since environments
3869   // may be attached late and JVMTI must track phases of VM execution
3870   JvmtiExport::enter_start_phase();
3871 
3872   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3873   JvmtiExport::post_vm_start();
3874 
3875   // Final system initialization including security manager and system class loader
3876   call_initPhase3(CHECK_JNI_ERR);
3877 
3878   // cache the system and platform class loaders
3879   SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
3880 
3881 #if INCLUDE_CDS
3882   if (DumpSharedSpaces) {
3883     // capture the module path info from the ModuleEntryTable
3884     ClassLoader::initialize_module_path(THREAD);
3885   }
3886 #endif
3887 
3888 #if INCLUDE_JVMCI
3889   if (force_JVMCI_intialization) {
3890     JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
3891     CompileBroker::compilation_init_phase2();
3892   }
3893 #endif
3894 
3895   // Always call even when there are not JVMTI environments yet, since environments
3896   // may be attached late and JVMTI must track phases of VM execution
3897   JvmtiExport::enter_live_phase();
3898 
3899   // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3900   JvmtiExport::post_vm_initialized();
3901 
3902   JFR_ONLY(Jfr::on_vm_start();)
3903 
3904 #if INCLUDE_MANAGEMENT
3905   Management::initialize(THREAD);
3906 
3907   if (HAS_PENDING_EXCEPTION) {
3908     // management agent fails to start possibly due to
3909     // configuration problem and is responsible for printing
3910     // stack trace if appropriate. Simply exit VM.
3911     vm_exit(1);
3912   }
3913 #endif // INCLUDE_MANAGEMENT
3914 
3915   if (MemProfiling)                   MemProfiler::engage();
3916   StatSampler::engage();
3917   if (CheckJNICalls)                  JniPeriodicChecker::engage();
3918 
3919   BiasedLocking::init();
3920 
3921 #if INCLUDE_RTM_OPT
3922   RTMLockingCounters::init();
3923 #endif
3924 
3925   if (JDK_Version::current().post_vm_init_hook_enabled()) {
3926     call_postVMInitHook(THREAD);
3927     // The Java side of PostVMInitHook.run must deal with all
3928     // exceptions and provide means of diagnosis.
3929     if (HAS_PENDING_EXCEPTION) {
3930       CLEAR_PENDING_EXCEPTION;
3931     }
3932   }
3933 
3934   {
3935     MutexLocker ml(PeriodicTask_lock);
3936     // Make sure the WatcherThread can be started by WatcherThread::start()
3937     // or by dynamic enrollment.
3938     WatcherThread::make_startable();
3939     // Start up the WatcherThread if there are any periodic tasks
3940     // NOTE:  All PeriodicTasks should be registered by now. If they
3941     //   aren't, late joiners might appear to start slowly (we might
3942     //   take a while to process their first tick).
3943     if (PeriodicTask::num_tasks() > 0) {
3944       WatcherThread::start();
3945     }
3946   }
3947 
3948   create_vm_timer.end();
3949 #ifdef ASSERT
3950   _vm_complete = true;
3951 #endif
3952 
3953   if (DumpSharedSpaces) {
3954     MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3955     ShouldNotReachHere();
3956   }
3957 
3958   return JNI_OK;
3959 }
3960 
3961 // type for the Agent_OnLoad and JVM_OnLoad entry points
3962 extern "C" {
3963   typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3964 }
3965 // Find a command line agent library and return its entry point for
3966 //         -agentlib:  -agentpath:   -Xrun
3967 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3968 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3969                                     const char *on_load_symbols[],
3970                                     size_t num_symbol_entries) {
3971   OnLoadEntry_t on_load_entry = NULL;
3972   void *library = NULL;
3973 
3974   if (!agent->valid()) {
3975     char buffer[JVM_MAXPATHLEN];
3976     char ebuf[1024] = "";
3977     const char *name = agent->name();
3978     const char *msg = "Could not find agent library ";
3979 
3980     // First check to see if agent is statically linked into executable
3981     if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3982       library = agent->os_lib();
3983     } else if (agent->is_absolute_path()) {
3984       library = os::dll_load(name, ebuf, sizeof ebuf);
3985       if (library == NULL) {
3986         const char *sub_msg = " in absolute path, with error: ";
3987         size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3988         char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3989         jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3990         // If we can't find the agent, exit.
3991         vm_exit_during_initialization(buf, NULL);
3992         FREE_C_HEAP_ARRAY(char, buf);
3993       }
3994     } else {
3995       // Try to load the agent from the standard dll directory
3996       if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
3997                              name)) {
3998         library = os::dll_load(buffer, ebuf, sizeof ebuf);
3999       }
4000       if (library == NULL) { // Try the library path directory.
4001         if (os::dll_build_name(buffer, sizeof(buffer), name)) {
4002           library = os::dll_load(buffer, ebuf, sizeof ebuf);
4003         }
4004         if (library == NULL) {
4005           const char *sub_msg = " on the library path, with error: ";
4006           const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image.";
4007 
4008           size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) +
4009                        strlen(ebuf) + strlen(sub_msg2) + 1;
4010           char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4011           if (!agent->is_instrument_lib()) {
4012             jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4013           } else {
4014             jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2);
4015           }
4016           // If we can't find the agent, exit.
4017           vm_exit_during_initialization(buf, NULL);
4018           FREE_C_HEAP_ARRAY(char, buf);
4019         }
4020       }
4021     }
4022     agent->set_os_lib(library);
4023     agent->set_valid();
4024   }
4025 
4026   // Find the OnLoad function.
4027   on_load_entry =
4028     CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
4029                                                           false,
4030                                                           on_load_symbols,
4031                                                           num_symbol_entries));
4032   return on_load_entry;
4033 }
4034 
4035 // Find the JVM_OnLoad entry point
4036 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
4037   const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
4038   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4039 }
4040 
4041 // Find the Agent_OnLoad entry point
4042 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
4043   const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
4044   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4045 }
4046 
4047 // For backwards compatibility with -Xrun
4048 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
4049 // treated like -agentpath:
4050 // Must be called before agent libraries are created
4051 void Threads::convert_vm_init_libraries_to_agents() {
4052   AgentLibrary* agent;
4053   AgentLibrary* next;
4054 
4055   for (agent = Arguments::libraries(); agent != NULL; agent = next) {
4056     next = agent->next();  // cache the next agent now as this agent may get moved off this list
4057     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4058 
4059     // If there is an JVM_OnLoad function it will get called later,
4060     // otherwise see if there is an Agent_OnLoad
4061     if (on_load_entry == NULL) {
4062       on_load_entry = lookup_agent_on_load(agent);
4063       if (on_load_entry != NULL) {
4064         // switch it to the agent list -- so that Agent_OnLoad will be called,
4065         // JVM_OnLoad won't be attempted and Agent_OnUnload will
4066         Arguments::convert_library_to_agent(agent);
4067       } else {
4068         vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
4069       }
4070     }
4071   }
4072 }
4073 
4074 // Create agents for -agentlib:  -agentpath:  and converted -Xrun
4075 // Invokes Agent_OnLoad
4076 // Called very early -- before JavaThreads exist
4077 void Threads::create_vm_init_agents() {
4078   extern struct JavaVM_ main_vm;
4079   AgentLibrary* agent;
4080 
4081   JvmtiExport::enter_onload_phase();
4082 
4083   for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4084     OnLoadEntry_t  on_load_entry = lookup_agent_on_load(agent);
4085 
4086     if (on_load_entry != NULL) {
4087       // Invoke the Agent_OnLoad function
4088       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4089       if (err != JNI_OK) {
4090         vm_exit_during_initialization("agent library failed to init", agent->name());
4091       }
4092     } else {
4093       vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4094     }
4095   }
4096   JvmtiExport::enter_primordial_phase();
4097 }
4098 
4099 extern "C" {
4100   typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4101 }
4102 
4103 void Threads::shutdown_vm_agents() {
4104   // Send any Agent_OnUnload notifications
4105   const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4106   size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4107   extern struct JavaVM_ main_vm;
4108   for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4109 
4110     // Find the Agent_OnUnload function.
4111     Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4112                                                    os::find_agent_function(agent,
4113                                                    false,
4114                                                    on_unload_symbols,
4115                                                    num_symbol_entries));
4116 
4117     // Invoke the Agent_OnUnload function
4118     if (unload_entry != NULL) {
4119       JavaThread* thread = JavaThread::current();
4120       ThreadToNativeFromVM ttn(thread);
4121       HandleMark hm(thread);
4122       (*unload_entry)(&main_vm);
4123     }
4124   }
4125 }
4126 
4127 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4128 // Invokes JVM_OnLoad
4129 void Threads::create_vm_init_libraries() {
4130   extern struct JavaVM_ main_vm;
4131   AgentLibrary* agent;
4132 
4133   for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4134     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4135 
4136     if (on_load_entry != NULL) {
4137       // Invoke the JVM_OnLoad function
4138       JavaThread* thread = JavaThread::current();
4139       ThreadToNativeFromVM ttn(thread);
4140       HandleMark hm(thread);
4141       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4142       if (err != JNI_OK) {
4143         vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4144       }
4145     } else {
4146       vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4147     }
4148   }
4149 }
4150 
4151 
4152 // Last thread running calls java.lang.Shutdown.shutdown()
4153 void JavaThread::invoke_shutdown_hooks() {
4154   HandleMark hm(this);
4155 
4156   // We could get here with a pending exception, if so clear it now.
4157   if (this->has_pending_exception()) {
4158     this->clear_pending_exception();
4159   }
4160 
4161   EXCEPTION_MARK;
4162   Klass* shutdown_klass =
4163     SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4164                                       THREAD);
4165   if (shutdown_klass != NULL) {
4166     // SystemDictionary::resolve_or_null will return null if there was
4167     // an exception.  If we cannot load the Shutdown class, just don't
4168     // call Shutdown.shutdown() at all.  This will mean the shutdown hooks
4169     // won't be run.  Note that if a shutdown hook was registered,
4170     // the Shutdown class would have already been loaded
4171     // (Runtime.addShutdownHook will load it).
4172     JavaValue result(T_VOID);
4173     JavaCalls::call_static(&result,
4174                            shutdown_klass,
4175                            vmSymbols::shutdown_method_name(),
4176                            vmSymbols::void_method_signature(),
4177                            THREAD);
4178   }
4179   CLEAR_PENDING_EXCEPTION;
4180 }
4181 
4182 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4183 // the program falls off the end of main(). Another VM exit path is through
4184 // vm_exit() when the program calls System.exit() to return a value or when
4185 // there is a serious error in VM. The two shutdown paths are not exactly
4186 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4187 // and VM_Exit op at VM level.
4188 //
4189 // Shutdown sequence:
4190 //   + Shutdown native memory tracking if it is on
4191 //   + Wait until we are the last non-daemon thread to execute
4192 //     <-- every thing is still working at this moment -->
4193 //   + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4194 //        shutdown hooks
4195 //   + Call before_exit(), prepare for VM exit
4196 //      > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4197 //        currently the only user of this mechanism is File.deleteOnExit())
4198 //      > stop StatSampler, watcher thread, CMS threads,
4199 //        post thread end and vm death events to JVMTI,
4200 //        stop signal thread
4201 //   + Call JavaThread::exit(), it will:
4202 //      > release JNI handle blocks, remove stack guard pages
4203 //      > remove this thread from Threads list
4204 //     <-- no more Java code from this thread after this point -->
4205 //   + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4206 //     the compiler threads at safepoint
4207 //     <-- do not use anything that could get blocked by Safepoint -->
4208 //   + Disable tracing at JNI/JVM barriers
4209 //   + Set _vm_exited flag for threads that are still running native code
4210 //   + Delete this thread
4211 //   + Call exit_globals()
4212 //      > deletes tty
4213 //      > deletes PerfMemory resources
4214 //   + Return to caller
4215 
4216 bool Threads::destroy_vm() {
4217   JavaThread* thread = JavaThread::current();
4218 
4219 #ifdef ASSERT
4220   _vm_complete = false;
4221 #endif
4222   // Wait until we are the last non-daemon thread to execute
4223   { MutexLocker nu(Threads_lock);
4224     while (Threads::number_of_non_daemon_threads() > 1)
4225       // This wait should make safepoint checks, wait without a timeout,
4226       // and wait as a suspend-equivalent condition.
4227       Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4228                          Mutex::_as_suspend_equivalent_flag);
4229   }
4230 
4231   EventShutdown e;
4232   if (e.should_commit()) {
4233     e.set_reason("No remaining non-daemon Java threads");
4234     e.commit();
4235   }
4236 
4237   // Hang forever on exit if we are reporting an error.
4238   if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4239     os::infinite_sleep();
4240   }
4241   os::wait_for_keypress_at_exit();
4242 
4243   // run Java level shutdown hooks
4244   thread->invoke_shutdown_hooks();
4245 
4246   before_exit(thread);
4247 
4248   thread->exit(true);
4249 
4250   // Stop VM thread.
4251   {
4252     // 4945125 The vm thread comes to a safepoint during exit.
4253     // GC vm_operations can get caught at the safepoint, and the
4254     // heap is unparseable if they are caught. Grab the Heap_lock
4255     // to prevent this. The GC vm_operations will not be able to
4256     // queue until after the vm thread is dead. After this point,
4257     // we'll never emerge out of the safepoint before the VM exits.
4258 
4259     MutexLocker ml(Heap_lock);
4260 
4261     VMThread::wait_for_vm_thread_exit();
4262     assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4263     VMThread::destroy();
4264   }
4265 
4266   // Now, all Java threads are gone except daemon threads. Daemon threads
4267   // running Java code or in VM are stopped by the Safepoint. However,
4268   // daemon threads executing native code are still running.  But they
4269   // will be stopped at native=>Java/VM barriers. Note that we can't
4270   // simply kill or suspend them, as it is inherently deadlock-prone.
4271 
4272   VM_Exit::set_vm_exited();
4273 
4274   // Clean up ideal graph printers after the VMThread has started
4275   // the final safepoint which will block all the Compiler threads.
4276   // Note that this Thread has already logically exited so the
4277   // clean_up() function's use of a JavaThreadIteratorWithHandle
4278   // would be a problem except set_vm_exited() has remembered the
4279   // shutdown thread which is granted a policy exception.
4280 #if defined(COMPILER2) && !defined(PRODUCT)
4281   IdealGraphPrinter::clean_up();
4282 #endif
4283 
4284   notify_vm_shutdown();
4285 
4286   // We are after VM_Exit::set_vm_exited() so we can't call
4287   // thread->smr_delete() or we will block on the Threads_lock.
4288   // Deleting the shutdown thread here is safe because another
4289   // JavaThread cannot have an active ThreadsListHandle for
4290   // this JavaThread.
4291   delete thread;
4292 
4293 #if INCLUDE_JVMCI
4294   if (JVMCICounterSize > 0) {
4295     FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4296   }
4297 #endif
4298 
4299   // exit_globals() will delete tty
4300   exit_globals();
4301 
4302   LogConfiguration::finalize();
4303 
4304   return true;
4305 }
4306 
4307 
4308 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4309   if (version == JNI_VERSION_1_1) return JNI_TRUE;
4310   return is_supported_jni_version(version);
4311 }
4312 
4313 
4314 jboolean Threads::is_supported_jni_version(jint version) {
4315   if (version == JNI_VERSION_1_2) return JNI_TRUE;
4316   if (version == JNI_VERSION_1_4) return JNI_TRUE;
4317   if (version == JNI_VERSION_1_6) return JNI_TRUE;
4318   if (version == JNI_VERSION_1_8) return JNI_TRUE;
4319   if (version == JNI_VERSION_9) return JNI_TRUE;
4320   if (version == JNI_VERSION_10) return JNI_TRUE;
4321   return JNI_FALSE;
4322 }
4323 
4324 
4325 void Threads::add(JavaThread* p, bool force_daemon) {
4326   // The threads lock must be owned at this point
4327   assert_locked_or_safepoint(Threads_lock);
4328 
4329   BarrierSet::barrier_set()->on_thread_attach(p);
4330 
4331   p->set_next(_thread_list);
4332   _thread_list = p;
4333 
4334   // Once a JavaThread is added to the Threads list, smr_delete() has
4335   // to be used to delete it. Otherwise we can just delete it directly.
4336   p->set_on_thread_list();
4337 
4338   _number_of_threads++;
4339   oop threadObj = p->threadObj();
4340   bool daemon = true;
4341   // Bootstrapping problem: threadObj can be null for initial
4342   // JavaThread (or for threads attached via JNI)
4343   if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4344     _number_of_non_daemon_threads++;
4345     daemon = false;
4346   }
4347 
4348   ThreadService::add_thread(p, daemon);
4349 
4350   // Maintain fast thread list
4351   ThreadsSMRSupport::add_thread(p);
4352 
4353   // Possible GC point.
4354   Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4355 }
4356 
4357 void Threads::remove(JavaThread* p) {
4358 
4359   // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread.
4360   ObjectSynchronizer::omFlush(p);
4361 
4362   // Extra scope needed for Thread_lock, so we can check
4363   // that we do not remove thread without safepoint code notice
4364   { MutexLocker ml(Threads_lock);
4365 
4366     assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present");
4367 
4368     // Maintain fast thread list
4369     ThreadsSMRSupport::remove_thread(p);
4370 
4371     JavaThread* current = _thread_list;
4372     JavaThread* prev    = NULL;
4373 
4374     while (current != p) {
4375       prev    = current;
4376       current = current->next();
4377     }
4378 
4379     if (prev) {
4380       prev->set_next(current->next());
4381     } else {
4382       _thread_list = p->next();
4383     }
4384 
4385     _number_of_threads--;
4386     oop threadObj = p->threadObj();
4387     bool daemon = true;
4388     if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4389       _number_of_non_daemon_threads--;
4390       daemon = false;
4391 
4392       // Only one thread left, do a notify on the Threads_lock so a thread waiting
4393       // on destroy_vm will wake up.
4394       if (number_of_non_daemon_threads() == 1) {
4395         Threads_lock->notify_all();
4396       }
4397     }
4398     ThreadService::remove_thread(p, daemon);
4399 
4400     // Make sure that safepoint code disregard this thread. This is needed since
4401     // the thread might mess around with locks after this point. This can cause it
4402     // to do callbacks into the safepoint code. However, the safepoint code is not aware
4403     // of this thread since it is removed from the queue.
4404     p->set_terminated_value();
4405   } // unlock Threads_lock
4406 
4407   // Since Events::log uses a lock, we grab it outside the Threads_lock
4408   Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4409 }
4410 
4411 // Operations on the Threads list for GC.  These are not explicitly locked,
4412 // but the garbage collector must provide a safe context for them to run.
4413 // In particular, these things should never be called when the Threads_lock
4414 // is held by some other thread. (Note: the Safepoint abstraction also
4415 // uses the Threads_lock to guarantee this property. It also makes sure that
4416 // all threads gets blocked when exiting or starting).
4417 
4418 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4419   ALL_JAVA_THREADS(p) {
4420     p->oops_do(f, cf);
4421   }
4422   VMThread::vm_thread()->oops_do(f, cf);
4423 }
4424 
4425 void Threads::change_thread_claim_parity() {
4426   // Set the new claim parity.
4427   assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4428          "Not in range.");
4429   _thread_claim_parity++;
4430   if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4431   assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4432          "Not in range.");
4433 }
4434 
4435 #ifdef ASSERT
4436 void Threads::assert_all_threads_claimed() {
4437   ALL_JAVA_THREADS(p) {
4438     const int thread_parity = p->oops_do_parity();
4439     assert((thread_parity == _thread_claim_parity),
4440            "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4441   }
4442   VMThread* vmt = VMThread::vm_thread();
4443   const int thread_parity = vmt->oops_do_parity();
4444   assert((thread_parity == _thread_claim_parity),
4445          "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity);
4446 }
4447 #endif // ASSERT
4448 
4449 class ParallelOopsDoThreadClosure : public ThreadClosure {
4450 private:
4451   OopClosure* _f;
4452   CodeBlobClosure* _cf;
4453 public:
4454   ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {}
4455   void do_thread(Thread* t) {
4456     t->oops_do(_f, _cf);
4457   }
4458 };
4459 
4460 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4461   ParallelOopsDoThreadClosure tc(f, cf);
4462   possibly_parallel_threads_do(is_par, &tc);
4463 }
4464 
4465 void Threads::nmethods_do(CodeBlobClosure* cf) {
4466   ALL_JAVA_THREADS(p) {
4467     // This is used by the code cache sweeper to mark nmethods that are active
4468     // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4469     // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4470     if(!p->is_Code_cache_sweeper_thread()) {
4471       p->nmethods_do(cf);
4472     }
4473   }
4474 }
4475 
4476 void Threads::metadata_do(void f(Metadata*)) {
4477   ALL_JAVA_THREADS(p) {
4478     p->metadata_do(f);
4479   }
4480 }
4481 
4482 class ThreadHandlesClosure : public ThreadClosure {
4483   void (*_f)(Metadata*);
4484  public:
4485   ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4486   virtual void do_thread(Thread* thread) {
4487     thread->metadata_handles_do(_f);
4488   }
4489 };
4490 
4491 void Threads::metadata_handles_do(void f(Metadata*)) {
4492   // Only walk the Handles in Thread.
4493   ThreadHandlesClosure handles_closure(f);
4494   threads_do(&handles_closure);
4495 }
4496 
4497 void Threads::deoptimized_wrt_marked_nmethods() {
4498   ALL_JAVA_THREADS(p) {
4499     p->deoptimized_wrt_marked_nmethods();
4500   }
4501 }
4502 
4503 
4504 // Get count Java threads that are waiting to enter the specified monitor.
4505 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
4506                                                          int count,
4507                                                          address monitor) {
4508   GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4509 
4510   int i = 0;
4511   DO_JAVA_THREADS(t_list, p) {
4512     if (!p->can_call_java()) continue;
4513 
4514     address pending = (address)p->current_pending_monitor();
4515     if (pending == monitor) {             // found a match
4516       if (i < count) result->append(p);   // save the first count matches
4517       i++;
4518     }
4519   }
4520 
4521   return result;
4522 }
4523 
4524 
4525 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
4526                                                       address owner) {
4527   // NULL owner means not locked so we can skip the search
4528   if (owner == NULL) return NULL;
4529 
4530   DO_JAVA_THREADS(t_list, p) {
4531     // first, see if owner is the address of a Java thread
4532     if (owner == (address)p) return p;
4533   }
4534 
4535   // Cannot assert on lack of success here since this function may be
4536   // used by code that is trying to report useful problem information
4537   // like deadlock detection.
4538   if (UseHeavyMonitors) return NULL;
4539 
4540   // If we didn't find a matching Java thread and we didn't force use of
4541   // heavyweight monitors, then the owner is the stack address of the
4542   // Lock Word in the owning Java thread's stack.
4543   //
4544   JavaThread* the_owner = NULL;
4545   DO_JAVA_THREADS(t_list, q) {
4546     if (q->is_lock_owned(owner)) {
4547       the_owner = q;
4548       break;
4549     }
4550   }
4551 
4552   // cannot assert on lack of success here; see above comment
4553   return the_owner;
4554 }
4555 
4556 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4557 void Threads::print_on(outputStream* st, bool print_stacks,
4558                        bool internal_format, bool print_concurrent_locks) {

4559   char buf[32];
4560   st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4561 
4562   st->print_cr("Full thread dump %s (%s %s):",
4563                Abstract_VM_Version::vm_name(),
4564                Abstract_VM_Version::vm_release(),
4565                Abstract_VM_Version::vm_info_string());
4566   st->cr();
4567 
4568 #if INCLUDE_SERVICES
4569   // Dump concurrent locks
4570   ConcurrentLocksDump concurrent_locks;
4571   if (print_concurrent_locks) {
4572     concurrent_locks.dump_at_safepoint();
4573   }
4574 #endif // INCLUDE_SERVICES
4575 
4576   ThreadsSMRSupport::print_info_on(st);
4577   st->cr();
4578 
4579   ALL_JAVA_THREADS(p) {
4580     ResourceMark rm;
4581     p->print_on(st);
4582     if (print_stacks) {
4583       if (internal_format) {
4584         p->trace_stack();
4585       } else {
4586         p->print_stack_on(st);
4587       }
4588     }
4589     st->cr();
4590 #if INCLUDE_SERVICES
4591     if (print_concurrent_locks) {
4592       concurrent_locks.print_locks_on(p, st);
4593     }
4594 #endif // INCLUDE_SERVICES
4595   }
4596 
4597   VMThread::vm_thread()->print_on(st);
4598   st->cr();
4599   Universe::heap()->print_gc_threads_on(st);
4600   WatcherThread* wt = WatcherThread::watcher_thread();
4601   if (wt != NULL) {
4602     wt->print_on(st);
4603     st->cr();
4604   }
4605 
4606   st->flush();
4607 }
4608 
4609 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4610                              int buflen, bool* found_current) {
4611   if (this_thread != NULL) {
4612     bool is_current = (current == this_thread);
4613     *found_current = *found_current || is_current;
4614     st->print("%s", is_current ? "=>" : "  ");
4615 
4616     st->print(PTR_FORMAT, p2i(this_thread));
4617     st->print(" ");
4618     this_thread->print_on_error(st, buf, buflen);
4619     st->cr();
4620   }
4621 }
4622 
4623 class PrintOnErrorClosure : public ThreadClosure {
4624   outputStream* _st;
4625   Thread* _current;
4626   char* _buf;
4627   int _buflen;
4628   bool* _found_current;
4629  public:
4630   PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4631                       int buflen, bool* found_current) :
4632    _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4633 
4634   virtual void do_thread(Thread* thread) {
4635     Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4636   }
4637 };
4638 
4639 // Threads::print_on_error() is called by fatal error handler. It's possible
4640 // that VM is not at safepoint and/or current thread is inside signal handler.
4641 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4642 // memory (even in resource area), it might deadlock the error handler.
4643 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4644                              int buflen) {
4645   ThreadsSMRSupport::print_info_on(st);
4646   st->cr();
4647 
4648   bool found_current = false;
4649   st->print_cr("Java Threads: ( => current thread )");
4650   ALL_JAVA_THREADS(thread) {
4651     print_on_error(thread, st, current, buf, buflen, &found_current);
4652   }
4653   st->cr();
4654 
4655   st->print_cr("Other Threads:");
4656   print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4657   print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4658 
4659   PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4660   Universe::heap()->gc_threads_do(&print_closure);
4661 
4662   if (!found_current) {
4663     st->cr();
4664     st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4665     current->print_on_error(st, buf, buflen);
4666     st->cr();
4667   }
4668   st->cr();
4669 
4670   st->print_cr("Threads with active compile tasks:");
4671   print_threads_compiling(st, buf, buflen);
4672 }
4673 
4674 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4675   ALL_JAVA_THREADS(thread) {
4676     if (thread->is_Compiler_thread()) {
4677       CompilerThread* ct = (CompilerThread*) thread;
4678 
4679       // Keep task in local variable for NULL check.
4680       // ct->_task might be set to NULL by concurring compiler thread
4681       // because it completed the compilation. The task is never freed,
4682       // though, just returned to a free list.
4683       CompileTask* task = ct->task();
4684       if (task != NULL) {
4685         thread->print_name_on_error(st, buf, buflen);
4686         task->print(st, NULL, true, true);
4687       }
4688     }
4689   }
4690 }
4691 
4692 
4693 // Internal SpinLock and Mutex
4694 // Based on ParkEvent
4695 
4696 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4697 //
4698 // We employ SpinLocks _only for low-contention, fixed-length
4699 // short-duration critical sections where we're concerned
4700 // about native mutex_t or HotSpot Mutex:: latency.
4701 // The mux construct provides a spin-then-block mutual exclusion
4702 // mechanism.
4703 //
4704 // Testing has shown that contention on the ListLock guarding gFreeList
4705 // is common.  If we implement ListLock as a simple SpinLock it's common
4706 // for the JVM to devolve to yielding with little progress.  This is true
4707 // despite the fact that the critical sections protected by ListLock are
4708 // extremely short.
4709 //
4710 // TODO-FIXME: ListLock should be of type SpinLock.
4711 // We should make this a 1st-class type, integrated into the lock
4712 // hierarchy as leaf-locks.  Critically, the SpinLock structure
4713 // should have sufficient padding to avoid false-sharing and excessive
4714 // cache-coherency traffic.
4715 
4716 
4717 typedef volatile int SpinLockT;
4718 
4719 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4720   if (Atomic::cmpxchg (1, adr, 0) == 0) {
4721     return;   // normal fast-path return
4722   }
4723 
4724   // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4725   TEVENT(SpinAcquire - ctx);
4726   int ctr = 0;
4727   int Yields = 0;
4728   for (;;) {
4729     while (*adr != 0) {
4730       ++ctr;
4731       if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4732         if (Yields > 5) {
4733           os::naked_short_sleep(1);
4734         } else {
4735           os::naked_yield();
4736           ++Yields;
4737         }
4738       } else {
4739         SpinPause();
4740       }
4741     }
4742     if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4743   }
4744 }
4745 
4746 void Thread::SpinRelease(volatile int * adr) {
4747   assert(*adr != 0, "invariant");
4748   OrderAccess::fence();      // guarantee at least release consistency.
4749   // Roach-motel semantics.
4750   // It's safe if subsequent LDs and STs float "up" into the critical section,
4751   // but prior LDs and STs within the critical section can't be allowed
4752   // to reorder or float past the ST that releases the lock.
4753   // Loads and stores in the critical section - which appear in program
4754   // order before the store that releases the lock - must also appear
4755   // before the store that releases the lock in memory visibility order.
4756   // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4757   // the ST of 0 into the lock-word which releases the lock, so fence
4758   // more than covers this on all platforms.
4759   *adr = 0;
4760 }
4761 
4762 // muxAcquire and muxRelease:
4763 //
4764 // *  muxAcquire and muxRelease support a single-word lock-word construct.
4765 //    The LSB of the word is set IFF the lock is held.
4766 //    The remainder of the word points to the head of a singly-linked list
4767 //    of threads blocked on the lock.
4768 //
4769 // *  The current implementation of muxAcquire-muxRelease uses its own
4770 //    dedicated Thread._MuxEvent instance.  If we're interested in
4771 //    minimizing the peak number of extant ParkEvent instances then
4772 //    we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4773 //    as certain invariants were satisfied.  Specifically, care would need
4774 //    to be taken with regards to consuming unpark() "permits".
4775 //    A safe rule of thumb is that a thread would never call muxAcquire()
4776 //    if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4777 //    park().  Otherwise the _ParkEvent park() operation in muxAcquire() could
4778 //    consume an unpark() permit intended for monitorenter, for instance.
4779 //    One way around this would be to widen the restricted-range semaphore
4780 //    implemented in park().  Another alternative would be to provide
4781 //    multiple instances of the PlatformEvent() for each thread.  One
4782 //    instance would be dedicated to muxAcquire-muxRelease, for instance.
4783 //
4784 // *  Usage:
4785 //    -- Only as leaf locks
4786 //    -- for short-term locking only as muxAcquire does not perform
4787 //       thread state transitions.
4788 //
4789 // Alternatives:
4790 // *  We could implement muxAcquire and muxRelease with MCS or CLH locks
4791 //    but with parking or spin-then-park instead of pure spinning.
4792 // *  Use Taura-Oyama-Yonenzawa locks.
4793 // *  It's possible to construct a 1-0 lock if we encode the lockword as
4794 //    (List,LockByte).  Acquire will CAS the full lockword while Release
4795 //    will STB 0 into the LockByte.  The 1-0 scheme admits stranding, so
4796 //    acquiring threads use timers (ParkTimed) to detect and recover from
4797 //    the stranding window.  Thread/Node structures must be aligned on 256-byte
4798 //    boundaries by using placement-new.
4799 // *  Augment MCS with advisory back-link fields maintained with CAS().
4800 //    Pictorially:  LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4801 //    The validity of the backlinks must be ratified before we trust the value.
4802 //    If the backlinks are invalid the exiting thread must back-track through the
4803 //    the forward links, which are always trustworthy.
4804 // *  Add a successor indication.  The LockWord is currently encoded as
4805 //    (List, LOCKBIT:1).  We could also add a SUCCBIT or an explicit _succ variable
4806 //    to provide the usual futile-wakeup optimization.
4807 //    See RTStt for details.
4808 // *  Consider schedctl.sc_nopreempt to cover the critical section.
4809 //
4810 
4811 
4812 const intptr_t LOCKBIT = 1;
4813 
4814 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4815   intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4816   if (w == 0) return;
4817   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4818     return;
4819   }
4820 
4821   TEVENT(muxAcquire - Contention);
4822   ParkEvent * const Self = Thread::current()->_MuxEvent;
4823   assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4824   for (;;) {
4825     int its = (os::is_MP() ? 100 : 0) + 1;
4826 
4827     // Optional spin phase: spin-then-park strategy
4828     while (--its >= 0) {
4829       w = *Lock;
4830       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4831         return;
4832       }
4833     }
4834 
4835     Self->reset();
4836     Self->OnList = intptr_t(Lock);
4837     // The following fence() isn't _strictly necessary as the subsequent
4838     // CAS() both serializes execution and ratifies the fetched *Lock value.
4839     OrderAccess::fence();
4840     for (;;) {
4841       w = *Lock;
4842       if ((w & LOCKBIT) == 0) {
4843         if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4844           Self->OnList = 0;   // hygiene - allows stronger asserts
4845           return;
4846         }
4847         continue;      // Interference -- *Lock changed -- Just retry
4848       }
4849       assert(w & LOCKBIT, "invariant");
4850       Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4851       if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4852     }
4853 
4854     while (Self->OnList != 0) {
4855       Self->park();
4856     }
4857   }
4858 }
4859 
4860 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4861   intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4862   if (w == 0) return;
4863   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4864     return;
4865   }
4866 
4867   TEVENT(muxAcquire - Contention);
4868   ParkEvent * ReleaseAfter = NULL;
4869   if (ev == NULL) {
4870     ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4871   }
4872   assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4873   for (;;) {
4874     guarantee(ev->OnList == 0, "invariant");
4875     int its = (os::is_MP() ? 100 : 0) + 1;
4876 
4877     // Optional spin phase: spin-then-park strategy
4878     while (--its >= 0) {
4879       w = *Lock;
4880       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4881         if (ReleaseAfter != NULL) {
4882           ParkEvent::Release(ReleaseAfter);
4883         }
4884         return;
4885       }
4886     }
4887 
4888     ev->reset();
4889     ev->OnList = intptr_t(Lock);
4890     // The following fence() isn't _strictly necessary as the subsequent
4891     // CAS() both serializes execution and ratifies the fetched *Lock value.
4892     OrderAccess::fence();
4893     for (;;) {
4894       w = *Lock;
4895       if ((w & LOCKBIT) == 0) {
4896         if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4897           ev->OnList = 0;
4898           // We call ::Release while holding the outer lock, thus
4899           // artificially lengthening the critical section.
4900           // Consider deferring the ::Release() until the subsequent unlock(),
4901           // after we've dropped the outer lock.
4902           if (ReleaseAfter != NULL) {
4903             ParkEvent::Release(ReleaseAfter);
4904           }
4905           return;
4906         }
4907         continue;      // Interference -- *Lock changed -- Just retry
4908       }
4909       assert(w & LOCKBIT, "invariant");
4910       ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4911       if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4912     }
4913 
4914     while (ev->OnList != 0) {
4915       ev->park();
4916     }
4917   }
4918 }
4919 
4920 // Release() must extract a successor from the list and then wake that thread.
4921 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4922 // similar to that used by ParkEvent::Allocate() and ::Release().  DMR-based
4923 // Release() would :
4924 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4925 // (B) Extract a successor from the private list "in-hand"
4926 // (C) attempt to CAS() the residual back into *Lock over null.
4927 //     If there were any newly arrived threads and the CAS() would fail.
4928 //     In that case Release() would detach the RATs, re-merge the list in-hand
4929 //     with the RATs and repeat as needed.  Alternately, Release() might
4930 //     detach and extract a successor, but then pass the residual list to the wakee.
4931 //     The wakee would be responsible for reattaching and remerging before it
4932 //     competed for the lock.
4933 //
4934 // Both "pop" and DMR are immune from ABA corruption -- there can be
4935 // multiple concurrent pushers, but only one popper or detacher.
4936 // This implementation pops from the head of the list.  This is unfair,
4937 // but tends to provide excellent throughput as hot threads remain hot.
4938 // (We wake recently run threads first).
4939 //
4940 // All paths through muxRelease() will execute a CAS.
4941 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4942 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4943 // executed within the critical section are complete and globally visible before the
4944 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4945 void Thread::muxRelease(volatile intptr_t * Lock)  {
4946   for (;;) {
4947     const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT);
4948     assert(w & LOCKBIT, "invariant");
4949     if (w == LOCKBIT) return;
4950     ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4951     assert(List != NULL, "invariant");
4952     assert(List->OnList == intptr_t(Lock), "invariant");
4953     ParkEvent * const nxt = List->ListNext;
4954     guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4955 
4956     // The following CAS() releases the lock and pops the head element.
4957     // The CAS() also ratifies the previously fetched lock-word value.
4958     if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) {
4959       continue;
4960     }
4961     List->OnList = 0;
4962     OrderAccess::fence();
4963     List->unpark();
4964     return;
4965   }
4966 }
4967 
4968 
4969 void Threads::verify() {
4970   ALL_JAVA_THREADS(p) {
4971     p->verify();
4972   }
4973   VMThread* thread = VMThread::vm_thread();
4974   if (thread != NULL) thread->verify();
4975 }
--- EOF ---