1 /* 2 * Copyright (c) 1997, 2011, 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 "classfile/classLoader.hpp" 27 #include "classfile/javaClasses.hpp" 28 #include "classfile/systemDictionary.hpp" 29 #include "classfile/vmSymbols.hpp" 30 #include "code/scopeDesc.hpp" 31 #include "compiler/compileBroker.hpp" 32 #include "interpreter/interpreter.hpp" 33 #include "interpreter/linkResolver.hpp" 34 #include "jvmtifiles/jvmtiEnv.hpp" 35 #include "memory/oopFactory.hpp" 36 #include "memory/universe.inline.hpp" 37 #include "oops/instanceKlass.hpp" 38 #include "oops/objArrayOop.hpp" 39 #include "oops/oop.inline.hpp" 40 #include "oops/symbol.hpp" 41 #include "prims/jvm_misc.hpp" 42 #include "prims/jvmtiExport.hpp" 43 #include "prims/jvmtiThreadState.hpp" 44 #include "prims/privilegedStack.hpp" 45 #include "runtime/aprofiler.hpp" 46 #include "runtime/arguments.hpp" 47 #include "runtime/biasedLocking.hpp" 48 #include "runtime/deoptimization.hpp" 49 #include "runtime/fprofiler.hpp" 50 #include "runtime/frame.inline.hpp" 51 #include "runtime/init.hpp" 52 #include "runtime/interfaceSupport.hpp" 53 #include "runtime/java.hpp" 54 #include "runtime/javaCalls.hpp" 55 #include "runtime/jniPeriodicChecker.hpp" 56 #include "runtime/memprofiler.hpp" 57 #include "runtime/mutexLocker.hpp" 58 #include "runtime/objectMonitor.hpp" 59 #include "runtime/osThread.hpp" 60 #include "runtime/safepoint.hpp" 61 #include "runtime/sharedRuntime.hpp" 62 #include "runtime/statSampler.hpp" 63 #include "runtime/stubRoutines.hpp" 64 #include "runtime/task.hpp" 65 #include "runtime/threadCritical.hpp" 66 #include "runtime/threadLocalStorage.hpp" 67 #include "runtime/vframe.hpp" 68 #include "runtime/vframeArray.hpp" 69 #include "runtime/vframe_hp.hpp" 70 #include "runtime/vmThread.hpp" 71 #include "runtime/vm_operations.hpp" 72 #include "services/attachListener.hpp" 73 #include "services/management.hpp" 74 #include "services/threadService.hpp" 75 #include "utilities/defaultStream.hpp" 76 #include "utilities/dtrace.hpp" 77 #include "utilities/events.hpp" 78 #include "utilities/preserveException.hpp" 79 #ifdef TARGET_OS_FAMILY_linux 80 # include "os_linux.inline.hpp" 81 # include "thread_linux.inline.hpp" 82 #endif 83 #ifdef TARGET_OS_FAMILY_solaris 84 # include "os_solaris.inline.hpp" 85 # include "thread_solaris.inline.hpp" 86 #endif 87 #ifdef TARGET_OS_FAMILY_windows 88 # include "os_windows.inline.hpp" 89 # include "thread_windows.inline.hpp" 90 #endif 91 #ifndef SERIALGC 92 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp" 93 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp" 94 #include "gc_implementation/parallelScavenge/pcTasks.hpp" 95 #endif 96 #ifdef COMPILER1 97 #include "c1/c1_Compiler.hpp" 98 #endif 99 #ifdef COMPILER2 100 #include "opto/c2compiler.hpp" 101 #include "opto/idealGraphPrinter.hpp" 102 #endif 103 104 #ifdef DTRACE_ENABLED 105 106 // Only bother with this argument setup if dtrace is available 107 108 HS_DTRACE_PROBE_DECL(hotspot, vm__init__begin); 109 HS_DTRACE_PROBE_DECL(hotspot, vm__init__end); 110 HS_DTRACE_PROBE_DECL5(hotspot, thread__start, char*, intptr_t, 111 intptr_t, intptr_t, bool); 112 HS_DTRACE_PROBE_DECL5(hotspot, thread__stop, char*, intptr_t, 113 intptr_t, intptr_t, bool); 114 115 #define DTRACE_THREAD_PROBE(probe, javathread) \ 116 { \ 117 ResourceMark rm(this); \ 118 int len = 0; \ 119 const char* name = (javathread)->get_thread_name(); \ 120 len = strlen(name); \ 121 HS_DTRACE_PROBE5(hotspot, thread__##probe, \ 122 name, len, \ 123 java_lang_Thread::thread_id((javathread)->threadObj()), \ 124 (javathread)->osthread()->thread_id(), \ 125 java_lang_Thread::is_daemon((javathread)->threadObj())); \ 126 } 127 128 #else // ndef DTRACE_ENABLED 129 130 #define DTRACE_THREAD_PROBE(probe, javathread) 131 132 #endif // ndef DTRACE_ENABLED 133 134 // Class hierarchy 135 // - Thread 136 // - VMThread 137 // - WatcherThread 138 // - ConcurrentMarkSweepThread 139 // - JavaThread 140 // - CompilerThread 141 142 // ======= Thread ======== 143 144 // Support for forcing alignment of thread objects for biased locking 145 void* Thread::operator new(size_t size) { 146 if (UseBiasedLocking) { 147 const int alignment = markOopDesc::biased_lock_alignment; 148 size_t aligned_size = size + (alignment - sizeof(intptr_t)); 149 void* real_malloc_addr = CHeapObj::operator new(aligned_size); 150 void* aligned_addr = (void*) align_size_up((intptr_t) real_malloc_addr, alignment); 151 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <= 152 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size), 153 "JavaThread alignment code overflowed allocated storage"); 154 if (TraceBiasedLocking) { 155 if (aligned_addr != real_malloc_addr) 156 tty->print_cr("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT, 157 real_malloc_addr, aligned_addr); 158 } 159 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr; 160 return aligned_addr; 161 } else { 162 return CHeapObj::operator new(size); 163 } 164 } 165 166 void Thread::operator delete(void* p) { 167 if (UseBiasedLocking) { 168 void* real_malloc_addr = ((Thread*) p)->_real_malloc_address; 169 CHeapObj::operator delete(real_malloc_addr); 170 } else { 171 CHeapObj::operator delete(p); 172 } 173 } 174 175 176 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread, 177 // JavaThread 178 179 180 Thread::Thread() { 181 // stack and get_thread 182 set_stack_base(NULL); 183 set_stack_size(0); 184 set_self_raw_id(0); 185 set_lgrp_id(-1); 186 187 // allocated data structures 188 set_osthread(NULL); 189 set_resource_area(new ResourceArea()); 190 set_handle_area(new HandleArea(NULL)); 191 set_active_handles(NULL); 192 set_free_handle_block(NULL); 193 set_last_handle_mark(NULL); 194 195 // This initial value ==> never claimed. 196 _oops_do_parity = 0; 197 198 // the handle mark links itself to last_handle_mark 199 new HandleMark(this); 200 201 // plain initialization 202 debug_only(_owned_locks = NULL;) 203 debug_only(_allow_allocation_count = 0;) 204 NOT_PRODUCT(_allow_safepoint_count = 0;) 205 NOT_PRODUCT(_skip_gcalot = false;) 206 CHECK_UNHANDLED_OOPS_ONLY(_gc_locked_out_count = 0;) 207 _jvmti_env_iteration_count = 0; 208 set_allocated_bytes(0); 209 _vm_operation_started_count = 0; 210 _vm_operation_completed_count = 0; 211 _current_pending_monitor = NULL; 212 _current_pending_monitor_is_from_java = true; 213 _current_waiting_monitor = NULL; 214 _num_nested_signal = 0; 215 omFreeList = NULL ; 216 omFreeCount = 0 ; 217 omFreeProvision = 32 ; 218 omInUseList = NULL ; 219 omInUseCount = 0 ; 220 221 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true); 222 _suspend_flags = 0; 223 224 // thread-specific hashCode stream generator state - Marsaglia shift-xor form 225 _hashStateX = os::random() ; 226 _hashStateY = 842502087 ; 227 _hashStateZ = 0x8767 ; // (int)(3579807591LL & 0xffff) ; 228 _hashStateW = 273326509 ; 229 230 _OnTrap = 0 ; 231 _schedctl = NULL ; 232 _Stalled = 0 ; 233 _TypeTag = 0x2BAD ; 234 235 // Many of the following fields are effectively final - immutable 236 // Note that nascent threads can't use the Native Monitor-Mutex 237 // construct until the _MutexEvent is initialized ... 238 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents 239 // we might instead use a stack of ParkEvents that we could provision on-demand. 240 // The stack would act as a cache to avoid calls to ParkEvent::Allocate() 241 // and ::Release() 242 _ParkEvent = ParkEvent::Allocate (this) ; 243 _SleepEvent = ParkEvent::Allocate (this) ; 244 _MutexEvent = ParkEvent::Allocate (this) ; 245 _MuxEvent = ParkEvent::Allocate (this) ; 246 247 #ifdef CHECK_UNHANDLED_OOPS 248 if (CheckUnhandledOops) { 249 _unhandled_oops = new UnhandledOops(this); 250 } 251 #endif // CHECK_UNHANDLED_OOPS 252 #ifdef ASSERT 253 if (UseBiasedLocking) { 254 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed"); 255 assert(this == _real_malloc_address || 256 this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment), 257 "bug in forced alignment of thread objects"); 258 } 259 #endif /* ASSERT */ 260 } 261 262 void Thread::initialize_thread_local_storage() { 263 // Note: Make sure this method only calls 264 // non-blocking operations. Otherwise, it might not work 265 // with the thread-startup/safepoint interaction. 266 267 // During Java thread startup, safepoint code should allow this 268 // method to complete because it may need to allocate memory to 269 // store information for the new thread. 270 271 // initialize structure dependent on thread local storage 272 ThreadLocalStorage::set_thread(this); 273 274 // set up any platform-specific state. 275 os::initialize_thread(); 276 277 } 278 279 void Thread::record_stack_base_and_size() { 280 set_stack_base(os::current_stack_base()); 281 set_stack_size(os::current_stack_size()); 282 } 283 284 285 Thread::~Thread() { 286 // Reclaim the objectmonitors from the omFreeList of the moribund thread. 287 ObjectSynchronizer::omFlush (this) ; 288 289 // deallocate data structures 290 delete resource_area(); 291 // since the handle marks are using the handle area, we have to deallocated the root 292 // handle mark before deallocating the thread's handle area, 293 assert(last_handle_mark() != NULL, "check we have an element"); 294 delete last_handle_mark(); 295 assert(last_handle_mark() == NULL, "check we have reached the end"); 296 297 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads. 298 // We NULL out the fields for good hygiene. 299 ParkEvent::Release (_ParkEvent) ; _ParkEvent = NULL ; 300 ParkEvent::Release (_SleepEvent) ; _SleepEvent = NULL ; 301 ParkEvent::Release (_MutexEvent) ; _MutexEvent = NULL ; 302 ParkEvent::Release (_MuxEvent) ; _MuxEvent = NULL ; 303 304 delete handle_area(); 305 306 // osthread() can be NULL, if creation of thread failed. 307 if (osthread() != NULL) os::free_thread(osthread()); 308 309 delete _SR_lock; 310 311 // clear thread local storage if the Thread is deleting itself 312 if (this == Thread::current()) { 313 ThreadLocalStorage::set_thread(NULL); 314 } else { 315 // In the case where we're not the current thread, invalidate all the 316 // caches in case some code tries to get the current thread or the 317 // thread that was destroyed, and gets stale information. 318 ThreadLocalStorage::invalidate_all(); 319 } 320 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();) 321 } 322 323 // NOTE: dummy function for assertion purpose. 324 void Thread::run() { 325 ShouldNotReachHere(); 326 } 327 328 #ifdef ASSERT 329 // Private method to check for dangling thread pointer 330 void check_for_dangling_thread_pointer(Thread *thread) { 331 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(), 332 "possibility of dangling Thread pointer"); 333 } 334 #endif 335 336 337 #ifndef PRODUCT 338 // Tracing method for basic thread operations 339 void Thread::trace(const char* msg, const Thread* const thread) { 340 if (!TraceThreadEvents) return; 341 ResourceMark rm; 342 ThreadCritical tc; 343 const char *name = "non-Java thread"; 344 int prio = -1; 345 if (thread->is_Java_thread() 346 && !thread->is_Compiler_thread()) { 347 // The Threads_lock must be held to get information about 348 // this thread but may not be in some situations when 349 // tracing thread events. 350 bool release_Threads_lock = false; 351 if (!Threads_lock->owned_by_self()) { 352 Threads_lock->lock(); 353 release_Threads_lock = true; 354 } 355 JavaThread* jt = (JavaThread *)thread; 356 name = (char *)jt->get_thread_name(); 357 oop thread_oop = jt->threadObj(); 358 if (thread_oop != NULL) { 359 prio = java_lang_Thread::priority(thread_oop); 360 } 361 if (release_Threads_lock) { 362 Threads_lock->unlock(); 363 } 364 } 365 tty->print_cr("Thread::%s " INTPTR_FORMAT " [%lx] %s (prio: %d)", msg, thread, thread->osthread()->thread_id(), name, prio); 366 } 367 #endif 368 369 370 ThreadPriority Thread::get_priority(const Thread* const thread) { 371 trace("get priority", thread); 372 ThreadPriority priority; 373 // Can return an error! 374 (void)os::get_priority(thread, priority); 375 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found"); 376 return priority; 377 } 378 379 void Thread::set_priority(Thread* thread, ThreadPriority priority) { 380 trace("set priority", thread); 381 debug_only(check_for_dangling_thread_pointer(thread);) 382 // Can return an error! 383 (void)os::set_priority(thread, priority); 384 } 385 386 387 void Thread::start(Thread* thread) { 388 trace("start", thread); 389 // Start is different from resume in that its safety is guaranteed by context or 390 // being called from a Java method synchronized on the Thread object. 391 if (!DisableStartThread) { 392 if (thread->is_Java_thread()) { 393 // Initialize the thread state to RUNNABLE before starting this thread. 394 // Can not set it after the thread started because we do not know the 395 // exact thread state at that time. It could be in MONITOR_WAIT or 396 // in SLEEPING or some other state. 397 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(), 398 java_lang_Thread::RUNNABLE); 399 } 400 os::start_thread(thread); 401 } 402 } 403 404 // Enqueue a VM_Operation to do the job for us - sometime later 405 void Thread::send_async_exception(oop java_thread, oop java_throwable) { 406 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable); 407 VMThread::execute(vm_stop); 408 } 409 410 411 // 412 // Check if an external suspend request has completed (or has been 413 // cancelled). Returns true if the thread is externally suspended and 414 // false otherwise. 415 // 416 // The bits parameter returns information about the code path through 417 // the routine. Useful for debugging: 418 // 419 // set in is_ext_suspend_completed(): 420 // 0x00000001 - routine was entered 421 // 0x00000010 - routine return false at end 422 // 0x00000100 - thread exited (return false) 423 // 0x00000200 - suspend request cancelled (return false) 424 // 0x00000400 - thread suspended (return true) 425 // 0x00001000 - thread is in a suspend equivalent state (return true) 426 // 0x00002000 - thread is native and walkable (return true) 427 // 0x00004000 - thread is native_trans and walkable (needed retry) 428 // 429 // set in wait_for_ext_suspend_completion(): 430 // 0x00010000 - routine was entered 431 // 0x00020000 - suspend request cancelled before loop (return false) 432 // 0x00040000 - thread suspended before loop (return true) 433 // 0x00080000 - suspend request cancelled in loop (return false) 434 // 0x00100000 - thread suspended in loop (return true) 435 // 0x00200000 - suspend not completed during retry loop (return false) 436 // 437 438 // Helper class for tracing suspend wait debug bits. 439 // 440 // 0x00000100 indicates that the target thread exited before it could 441 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and 442 // 0x00080000 each indicate a cancelled suspend request so they don't 443 // count as wait failures either. 444 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000) 445 446 class TraceSuspendDebugBits : public StackObj { 447 private: 448 JavaThread * jt; 449 bool is_wait; 450 bool called_by_wait; // meaningful when !is_wait 451 uint32_t * bits; 452 453 public: 454 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait, 455 uint32_t *_bits) { 456 jt = _jt; 457 is_wait = _is_wait; 458 called_by_wait = _called_by_wait; 459 bits = _bits; 460 } 461 462 ~TraceSuspendDebugBits() { 463 if (!is_wait) { 464 #if 1 465 // By default, don't trace bits for is_ext_suspend_completed() calls. 466 // That trace is very chatty. 467 return; 468 #else 469 if (!called_by_wait) { 470 // If tracing for is_ext_suspend_completed() is enabled, then only 471 // trace calls to it from wait_for_ext_suspend_completion() 472 return; 473 } 474 #endif 475 } 476 477 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) { 478 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) { 479 MutexLocker ml(Threads_lock); // needed for get_thread_name() 480 ResourceMark rm; 481 482 tty->print_cr( 483 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)", 484 jt->get_thread_name(), *bits); 485 486 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed"); 487 } 488 } 489 } 490 }; 491 #undef DEBUG_FALSE_BITS 492 493 494 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, uint32_t *bits) { 495 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits); 496 497 bool did_trans_retry = false; // only do thread_in_native_trans retry once 498 bool do_trans_retry; // flag to force the retry 499 500 *bits |= 0x00000001; 501 502 do { 503 do_trans_retry = false; 504 505 if (is_exiting()) { 506 // Thread is in the process of exiting. This is always checked 507 // first to reduce the risk of dereferencing a freed JavaThread. 508 *bits |= 0x00000100; 509 return false; 510 } 511 512 if (!is_external_suspend()) { 513 // Suspend request is cancelled. This is always checked before 514 // is_ext_suspended() to reduce the risk of a rogue resume 515 // confusing the thread that made the suspend request. 516 *bits |= 0x00000200; 517 return false; 518 } 519 520 if (is_ext_suspended()) { 521 // thread is suspended 522 *bits |= 0x00000400; 523 return true; 524 } 525 526 // Now that we no longer do hard suspends of threads running 527 // native code, the target thread can be changing thread state 528 // while we are in this routine: 529 // 530 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked 531 // 532 // We save a copy of the thread state as observed at this moment 533 // and make our decision about suspend completeness based on the 534 // copy. This closes the race where the thread state is seen as 535 // _thread_in_native_trans in the if-thread_blocked check, but is 536 // seen as _thread_blocked in if-thread_in_native_trans check. 537 JavaThreadState save_state = thread_state(); 538 539 if (save_state == _thread_blocked && is_suspend_equivalent()) { 540 // If the thread's state is _thread_blocked and this blocking 541 // condition is known to be equivalent to a suspend, then we can 542 // consider the thread to be externally suspended. This means that 543 // the code that sets _thread_blocked has been modified to do 544 // self-suspension if the blocking condition releases. We also 545 // used to check for CONDVAR_WAIT here, but that is now covered by 546 // the _thread_blocked with self-suspension check. 547 // 548 // Return true since we wouldn't be here unless there was still an 549 // external suspend request. 550 *bits |= 0x00001000; 551 return true; 552 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) { 553 // Threads running native code will self-suspend on native==>VM/Java 554 // transitions. If its stack is walkable (should always be the case 555 // unless this function is called before the actual java_suspend() 556 // call), then the wait is done. 557 *bits |= 0x00002000; 558 return true; 559 } else if (!called_by_wait && !did_trans_retry && 560 save_state == _thread_in_native_trans && 561 frame_anchor()->walkable()) { 562 // The thread is transitioning from thread_in_native to another 563 // thread state. check_safepoint_and_suspend_for_native_trans() 564 // will force the thread to self-suspend. If it hasn't gotten 565 // there yet we may have caught the thread in-between the native 566 // code check above and the self-suspend. Lucky us. If we were 567 // called by wait_for_ext_suspend_completion(), then it 568 // will be doing the retries so we don't have to. 569 // 570 // Since we use the saved thread state in the if-statement above, 571 // there is a chance that the thread has already transitioned to 572 // _thread_blocked by the time we get here. In that case, we will 573 // make a single unnecessary pass through the logic below. This 574 // doesn't hurt anything since we still do the trans retry. 575 576 *bits |= 0x00004000; 577 578 // Once the thread leaves thread_in_native_trans for another 579 // thread state, we break out of this retry loop. We shouldn't 580 // need this flag to prevent us from getting back here, but 581 // sometimes paranoia is good. 582 did_trans_retry = true; 583 584 // We wait for the thread to transition to a more usable state. 585 for (int i = 1; i <= SuspendRetryCount; i++) { 586 // We used to do an "os::yield_all(i)" call here with the intention 587 // that yielding would increase on each retry. However, the parameter 588 // is ignored on Linux which means the yield didn't scale up. Waiting 589 // on the SR_lock below provides a much more predictable scale up for 590 // the delay. It also provides a simple/direct point to check for any 591 // safepoint requests from the VMThread 592 593 // temporarily drops SR_lock while doing wait with safepoint check 594 // (if we're a JavaThread - the WatcherThread can also call this) 595 // and increase delay with each retry 596 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 597 598 // check the actual thread state instead of what we saved above 599 if (thread_state() != _thread_in_native_trans) { 600 // the thread has transitioned to another thread state so 601 // try all the checks (except this one) one more time. 602 do_trans_retry = true; 603 break; 604 } 605 } // end retry loop 606 607 608 } 609 } while (do_trans_retry); 610 611 *bits |= 0x00000010; 612 return false; 613 } 614 615 // 616 // Wait for an external suspend request to complete (or be cancelled). 617 // Returns true if the thread is externally suspended and false otherwise. 618 // 619 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay, 620 uint32_t *bits) { 621 TraceSuspendDebugBits tsdb(this, true /* is_wait */, 622 false /* !called_by_wait */, bits); 623 624 // local flag copies to minimize SR_lock hold time 625 bool is_suspended; 626 bool pending; 627 uint32_t reset_bits; 628 629 // set a marker so is_ext_suspend_completed() knows we are the caller 630 *bits |= 0x00010000; 631 632 // We use reset_bits to reinitialize the bits value at the top of 633 // each retry loop. This allows the caller to make use of any 634 // unused bits for their own marking purposes. 635 reset_bits = *bits; 636 637 { 638 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 639 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 640 delay, bits); 641 pending = is_external_suspend(); 642 } 643 // must release SR_lock to allow suspension to complete 644 645 if (!pending) { 646 // A cancelled suspend request is the only false return from 647 // is_ext_suspend_completed() that keeps us from entering the 648 // retry loop. 649 *bits |= 0x00020000; 650 return false; 651 } 652 653 if (is_suspended) { 654 *bits |= 0x00040000; 655 return true; 656 } 657 658 for (int i = 1; i <= retries; i++) { 659 *bits = reset_bits; // reinit to only track last retry 660 661 // We used to do an "os::yield_all(i)" call here with the intention 662 // that yielding would increase on each retry. However, the parameter 663 // is ignored on Linux which means the yield didn't scale up. Waiting 664 // on the SR_lock below provides a much more predictable scale up for 665 // the delay. It also provides a simple/direct point to check for any 666 // safepoint requests from the VMThread 667 668 { 669 MutexLocker ml(SR_lock()); 670 // wait with safepoint check (if we're a JavaThread - the WatcherThread 671 // can also call this) and increase delay with each retry 672 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 673 674 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 675 delay, bits); 676 677 // It is possible for the external suspend request to be cancelled 678 // (by a resume) before the actual suspend operation is completed. 679 // Refresh our local copy to see if we still need to wait. 680 pending = is_external_suspend(); 681 } 682 683 if (!pending) { 684 // A cancelled suspend request is the only false return from 685 // is_ext_suspend_completed() that keeps us from staying in the 686 // retry loop. 687 *bits |= 0x00080000; 688 return false; 689 } 690 691 if (is_suspended) { 692 *bits |= 0x00100000; 693 return true; 694 } 695 } // end retry loop 696 697 // thread did not suspend after all our retries 698 *bits |= 0x00200000; 699 return false; 700 } 701 702 #ifndef PRODUCT 703 void JavaThread::record_jump(address target, address instr, const char* file, int line) { 704 705 // This should not need to be atomic as the only way for simultaneous 706 // updates is via interrupts. Even then this should be rare or non-existant 707 // and we don't care that much anyway. 708 709 int index = _jmp_ring_index; 710 _jmp_ring_index = (index + 1 ) & (jump_ring_buffer_size - 1); 711 _jmp_ring[index]._target = (intptr_t) target; 712 _jmp_ring[index]._instruction = (intptr_t) instr; 713 _jmp_ring[index]._file = file; 714 _jmp_ring[index]._line = line; 715 } 716 #endif /* PRODUCT */ 717 718 // Called by flat profiler 719 // Callers have already called wait_for_ext_suspend_completion 720 // The assertion for that is currently too complex to put here: 721 bool JavaThread::profile_last_Java_frame(frame* _fr) { 722 bool gotframe = false; 723 // self suspension saves needed state. 724 if (has_last_Java_frame() && _anchor.walkable()) { 725 *_fr = pd_last_frame(); 726 gotframe = true; 727 } 728 return gotframe; 729 } 730 731 void Thread::interrupt(Thread* thread) { 732 trace("interrupt", thread); 733 debug_only(check_for_dangling_thread_pointer(thread);) 734 os::interrupt(thread); 735 } 736 737 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) { 738 trace("is_interrupted", thread); 739 debug_only(check_for_dangling_thread_pointer(thread);) 740 // Note: If clear_interrupted==false, this simply fetches and 741 // returns the value of the field osthread()->interrupted(). 742 return os::is_interrupted(thread, clear_interrupted); 743 } 744 745 746 // GC Support 747 bool Thread::claim_oops_do_par_case(int strong_roots_parity) { 748 jint thread_parity = _oops_do_parity; 749 if (thread_parity != strong_roots_parity) { 750 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity); 751 if (res == thread_parity) return true; 752 else { 753 guarantee(res == strong_roots_parity, "Or else what?"); 754 assert(SharedHeap::heap()->n_par_threads() > 0, 755 "Should only fail when parallel."); 756 return false; 757 } 758 } 759 assert(SharedHeap::heap()->n_par_threads() > 0, 760 "Should only fail when parallel."); 761 return false; 762 } 763 764 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 765 active_handles()->oops_do(f); 766 // Do oop for ThreadShadow 767 f->do_oop((oop*)&_pending_exception); 768 handle_area()->oops_do(f); 769 } 770 771 void Thread::nmethods_do(CodeBlobClosure* cf) { 772 // no nmethods in a generic thread... 773 } 774 775 void Thread::print_on(outputStream* st) const { 776 // get_priority assumes osthread initialized 777 if (osthread() != NULL) { 778 st->print("prio=%d tid=" INTPTR_FORMAT " ", get_priority(this), this); 779 osthread()->print_on(st); 780 } 781 debug_only(if (WizardMode) print_owned_locks_on(st);) 782 } 783 784 // Thread::print_on_error() is called by fatal error handler. Don't use 785 // any lock or allocate memory. 786 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const { 787 if (is_VM_thread()) st->print("VMThread"); 788 else if (is_Compiler_thread()) st->print("CompilerThread"); 789 else if (is_Java_thread()) st->print("JavaThread"); 790 else if (is_GC_task_thread()) st->print("GCTaskThread"); 791 else if (is_Watcher_thread()) st->print("WatcherThread"); 792 else if (is_ConcurrentGC_thread()) st->print("ConcurrentGCThread"); 793 else st->print("Thread"); 794 795 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]", 796 _stack_base - _stack_size, _stack_base); 797 798 if (osthread()) { 799 st->print(" [id=%d]", osthread()->thread_id()); 800 } 801 } 802 803 #ifdef ASSERT 804 void Thread::print_owned_locks_on(outputStream* st) const { 805 Monitor *cur = _owned_locks; 806 if (cur == NULL) { 807 st->print(" (no locks) "); 808 } else { 809 st->print_cr(" Locks owned:"); 810 while(cur) { 811 cur->print_on(st); 812 cur = cur->next(); 813 } 814 } 815 } 816 817 static int ref_use_count = 0; 818 819 bool Thread::owns_locks_but_compiled_lock() const { 820 for(Monitor *cur = _owned_locks; cur; cur = cur->next()) { 821 if (cur != Compile_lock) return true; 822 } 823 return false; 824 } 825 826 827 #endif 828 829 #ifndef PRODUCT 830 831 // The flag: potential_vm_operation notifies if this particular safepoint state could potential 832 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that 833 // no threads which allow_vm_block's are held 834 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) { 835 // Check if current thread is allowed to block at a safepoint 836 if (!(_allow_safepoint_count == 0)) 837 fatal("Possible safepoint reached by thread that does not allow it"); 838 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) { 839 fatal("LEAF method calling lock?"); 840 } 841 842 #ifdef ASSERT 843 if (potential_vm_operation && is_Java_thread() 844 && !Universe::is_bootstrapping()) { 845 // Make sure we do not hold any locks that the VM thread also uses. 846 // This could potentially lead to deadlocks 847 for(Monitor *cur = _owned_locks; cur; cur = cur->next()) { 848 // Threads_lock is special, since the safepoint synchronization will not start before this is 849 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock, 850 // since it is used to transfer control between JavaThreads and the VMThread 851 // Do not *exclude* any locks unless you are absolutly sure it is correct. Ask someone else first! 852 if ( (cur->allow_vm_block() && 853 cur != Threads_lock && 854 cur != Compile_lock && // Temporary: should not be necessary when we get spearate compilation 855 cur != VMOperationRequest_lock && 856 cur != VMOperationQueue_lock) || 857 cur->rank() == Mutex::special) { 858 warning("Thread holding lock at safepoint that vm can block on: %s", cur->name()); 859 } 860 } 861 } 862 863 if (GCALotAtAllSafepoints) { 864 // We could enter a safepoint here and thus have a gc 865 InterfaceSupport::check_gc_alot(); 866 } 867 #endif 868 } 869 #endif 870 871 bool Thread::is_in_stack(address adr) const { 872 assert(Thread::current() == this, "is_in_stack can only be called from current thread"); 873 address end = os::current_stack_pointer(); 874 if (stack_base() >= adr && adr >= end) return true; 875 876 return false; 877 } 878 879 880 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter 881 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being 882 // used for compilation in the future. If that change is made, the need for these methods 883 // should be revisited, and they should be removed if possible. 884 885 bool Thread::is_lock_owned(address adr) const { 886 return on_local_stack(adr); 887 } 888 889 bool Thread::set_as_starting_thread() { 890 // NOTE: this must be called inside the main thread. 891 return os::create_main_thread((JavaThread*)this); 892 } 893 894 static void initialize_class(Symbol* class_name, TRAPS) { 895 klassOop klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK); 896 instanceKlass::cast(klass)->initialize(CHECK); 897 } 898 899 900 // Creates the initial ThreadGroup 901 static Handle create_initial_thread_group(TRAPS) { 902 klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH); 903 instanceKlassHandle klass (THREAD, k); 904 905 Handle system_instance = klass->allocate_instance_handle(CHECK_NH); 906 { 907 JavaValue result(T_VOID); 908 JavaCalls::call_special(&result, 909 system_instance, 910 klass, 911 vmSymbols::object_initializer_name(), 912 vmSymbols::void_method_signature(), 913 CHECK_NH); 914 } 915 Universe::set_system_thread_group(system_instance()); 916 917 Handle main_instance = klass->allocate_instance_handle(CHECK_NH); 918 { 919 JavaValue result(T_VOID); 920 Handle string = java_lang_String::create_from_str("main", CHECK_NH); 921 JavaCalls::call_special(&result, 922 main_instance, 923 klass, 924 vmSymbols::object_initializer_name(), 925 vmSymbols::threadgroup_string_void_signature(), 926 system_instance, 927 string, 928 CHECK_NH); 929 } 930 return main_instance; 931 } 932 933 // Creates the initial Thread 934 static oop create_initial_thread(Handle thread_group, JavaThread* thread, TRAPS) { 935 klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL); 936 instanceKlassHandle klass (THREAD, k); 937 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL); 938 939 java_lang_Thread::set_thread(thread_oop(), thread); 940 java_lang_Thread::set_priority(thread_oop(), NormPriority); 941 thread->set_threadObj(thread_oop()); 942 943 Handle string = java_lang_String::create_from_str("main", CHECK_NULL); 944 945 JavaValue result(T_VOID); 946 JavaCalls::call_special(&result, thread_oop, 947 klass, 948 vmSymbols::object_initializer_name(), 949 vmSymbols::threadgroup_string_void_signature(), 950 thread_group, 951 string, 952 CHECK_NULL); 953 return thread_oop(); 954 } 955 956 static void call_initializeSystemClass(TRAPS) { 957 klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 958 instanceKlassHandle klass (THREAD, k); 959 960 JavaValue result(T_VOID); 961 JavaCalls::call_static(&result, klass, vmSymbols::initializeSystemClass_name(), 962 vmSymbols::void_method_signature(), CHECK); 963 } 964 965 // General purpose hook into Java code, run once when the VM is initialized. 966 // The Java library method itself may be changed independently from the VM. 967 static void call_postVMInitHook(TRAPS) { 968 klassOop k = SystemDictionary::sun_misc_PostVMInitHook_klass(); 969 instanceKlassHandle klass (THREAD, k); 970 if (klass.not_null()) { 971 JavaValue result(T_VOID); 972 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(), 973 vmSymbols::void_method_signature(), 974 CHECK); 975 } 976 } 977 978 static void reset_vm_info_property(TRAPS) { 979 // the vm info string 980 ResourceMark rm(THREAD); 981 const char *vm_info = VM_Version::vm_info_string(); 982 983 // java.lang.System class 984 klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 985 instanceKlassHandle klass (THREAD, k); 986 987 // setProperty arguments 988 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK); 989 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK); 990 991 // return value 992 JavaValue r(T_OBJECT); 993 994 // public static String setProperty(String key, String value); 995 JavaCalls::call_static(&r, 996 klass, 997 vmSymbols::setProperty_name(), 998 vmSymbols::string_string_string_signature(), 999 key_str, 1000 value_str, 1001 CHECK); 1002 } 1003 1004 1005 void JavaThread::allocate_threadObj(Handle thread_group, char* thread_name, bool daemon, TRAPS) { 1006 assert(thread_group.not_null(), "thread group should be specified"); 1007 assert(threadObj() == NULL, "should only create Java thread object once"); 1008 1009 klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK); 1010 instanceKlassHandle klass (THREAD, k); 1011 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK); 1012 1013 java_lang_Thread::set_thread(thread_oop(), this); 1014 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1015 set_threadObj(thread_oop()); 1016 1017 JavaValue result(T_VOID); 1018 if (thread_name != NULL) { 1019 Handle name = java_lang_String::create_from_str(thread_name, CHECK); 1020 // Thread gets assigned specified name and null target 1021 JavaCalls::call_special(&result, 1022 thread_oop, 1023 klass, 1024 vmSymbols::object_initializer_name(), 1025 vmSymbols::threadgroup_string_void_signature(), 1026 thread_group, // Argument 1 1027 name, // Argument 2 1028 THREAD); 1029 } else { 1030 // Thread gets assigned name "Thread-nnn" and null target 1031 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument) 1032 JavaCalls::call_special(&result, 1033 thread_oop, 1034 klass, 1035 vmSymbols::object_initializer_name(), 1036 vmSymbols::threadgroup_runnable_void_signature(), 1037 thread_group, // Argument 1 1038 Handle(), // Argument 2 1039 THREAD); 1040 } 1041 1042 1043 if (daemon) { 1044 java_lang_Thread::set_daemon(thread_oop()); 1045 } 1046 1047 if (HAS_PENDING_EXCEPTION) { 1048 return; 1049 } 1050 1051 KlassHandle group(this, SystemDictionary::ThreadGroup_klass()); 1052 Handle threadObj(this, this->threadObj()); 1053 1054 JavaCalls::call_special(&result, 1055 thread_group, 1056 group, 1057 vmSymbols::add_method_name(), 1058 vmSymbols::thread_void_signature(), 1059 threadObj, // Arg 1 1060 THREAD); 1061 1062 1063 } 1064 1065 // NamedThread -- non-JavaThread subclasses with multiple 1066 // uniquely named instances should derive from this. 1067 NamedThread::NamedThread() : Thread() { 1068 _name = NULL; 1069 _processed_thread = NULL; 1070 } 1071 1072 NamedThread::~NamedThread() { 1073 if (_name != NULL) { 1074 FREE_C_HEAP_ARRAY(char, _name); 1075 _name = NULL; 1076 } 1077 } 1078 1079 void NamedThread::set_name(const char* format, ...) { 1080 guarantee(_name == NULL, "Only get to set name once."); 1081 _name = NEW_C_HEAP_ARRAY(char, max_name_len); 1082 guarantee(_name != NULL, "alloc failure"); 1083 va_list ap; 1084 va_start(ap, format); 1085 jio_vsnprintf(_name, max_name_len, format, ap); 1086 va_end(ap); 1087 } 1088 1089 // ======= WatcherThread ======== 1090 1091 // The watcher thread exists to simulate timer interrupts. It should 1092 // be replaced by an abstraction over whatever native support for 1093 // timer interrupts exists on the platform. 1094 1095 WatcherThread* WatcherThread::_watcher_thread = NULL; 1096 volatile bool WatcherThread::_should_terminate = false; 1097 1098 WatcherThread::WatcherThread() : Thread() { 1099 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread"); 1100 if (os::create_thread(this, os::watcher_thread)) { 1101 _watcher_thread = this; 1102 1103 // Set the watcher thread to the highest OS priority which should not be 1104 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY 1105 // is created. The only normal thread using this priority is the reference 1106 // handler thread, which runs for very short intervals only. 1107 // If the VMThread's priority is not lower than the WatcherThread profiling 1108 // will be inaccurate. 1109 os::set_priority(this, MaxPriority); 1110 if (!DisableStartThread) { 1111 os::start_thread(this); 1112 } 1113 } 1114 } 1115 1116 void WatcherThread::run() { 1117 assert(this == watcher_thread(), "just checking"); 1118 1119 this->record_stack_base_and_size(); 1120 this->initialize_thread_local_storage(); 1121 this->set_active_handles(JNIHandleBlock::allocate_block()); 1122 while(!_should_terminate) { 1123 assert(watcher_thread() == Thread::current(), "thread consistency check"); 1124 assert(watcher_thread() == this, "thread consistency check"); 1125 1126 // Calculate how long it'll be until the next PeriodicTask work 1127 // should be done, and sleep that amount of time. 1128 size_t time_to_wait = PeriodicTask::time_to_wait(); 1129 1130 // we expect this to timeout - we only ever get unparked when 1131 // we should terminate 1132 { 1133 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */); 1134 1135 jlong prev_time = os::javaTimeNanos(); 1136 for (;;) { 1137 int res= _SleepEvent->park(time_to_wait); 1138 if (res == OS_TIMEOUT || _should_terminate) 1139 break; 1140 // spurious wakeup of some kind 1141 jlong now = os::javaTimeNanos(); 1142 time_to_wait -= (now - prev_time) / 1000000; 1143 if (time_to_wait <= 0) 1144 break; 1145 prev_time = now; 1146 } 1147 } 1148 1149 if (is_error_reported()) { 1150 // A fatal error has happened, the error handler(VMError::report_and_die) 1151 // should abort JVM after creating an error log file. However in some 1152 // rare cases, the error handler itself might deadlock. Here we try to 1153 // kill JVM if the fatal error handler fails to abort in 2 minutes. 1154 // 1155 // This code is in WatcherThread because WatcherThread wakes up 1156 // periodically so the fatal error handler doesn't need to do anything; 1157 // also because the WatcherThread is less likely to crash than other 1158 // threads. 1159 1160 for (;;) { 1161 if (!ShowMessageBoxOnError 1162 && (OnError == NULL || OnError[0] == '\0') 1163 && Arguments::abort_hook() == NULL) { 1164 os::sleep(this, 2 * 60 * 1000, false); 1165 fdStream err(defaultStream::output_fd()); 1166 err.print_raw_cr("# [ timer expired, abort... ]"); 1167 // skip atexit/vm_exit/vm_abort hooks 1168 os::die(); 1169 } 1170 1171 // Wake up 5 seconds later, the fatal handler may reset OnError or 1172 // ShowMessageBoxOnError when it is ready to abort. 1173 os::sleep(this, 5 * 1000, false); 1174 } 1175 } 1176 1177 PeriodicTask::real_time_tick(time_to_wait); 1178 1179 // If we have no more tasks left due to dynamic disenrollment, 1180 // shut down the thread since we don't currently support dynamic enrollment 1181 if (PeriodicTask::num_tasks() == 0) { 1182 _should_terminate = true; 1183 } 1184 } 1185 1186 // Signal that it is terminated 1187 { 1188 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag); 1189 _watcher_thread = NULL; 1190 Terminator_lock->notify(); 1191 } 1192 1193 // Thread destructor usually does this.. 1194 ThreadLocalStorage::set_thread(NULL); 1195 } 1196 1197 void WatcherThread::start() { 1198 if (watcher_thread() == NULL) { 1199 _should_terminate = false; 1200 // Create the single instance of WatcherThread 1201 new WatcherThread(); 1202 } 1203 } 1204 1205 void WatcherThread::stop() { 1206 // it is ok to take late safepoints here, if needed 1207 MutexLocker mu(Terminator_lock); 1208 _should_terminate = true; 1209 OrderAccess::fence(); // ensure WatcherThread sees update in main loop 1210 1211 Thread* watcher = watcher_thread(); 1212 if (watcher != NULL) 1213 watcher->_SleepEvent->unpark(); 1214 1215 while(watcher_thread() != NULL) { 1216 // This wait should make safepoint checks, wait without a timeout, 1217 // and wait as a suspend-equivalent condition. 1218 // 1219 // Note: If the FlatProfiler is running, then this thread is waiting 1220 // for the WatcherThread to terminate and the WatcherThread, via the 1221 // FlatProfiler task, is waiting for the external suspend request on 1222 // this thread to complete. wait_for_ext_suspend_completion() will 1223 // eventually timeout, but that takes time. Making this wait a 1224 // suspend-equivalent condition solves that timeout problem. 1225 // 1226 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 1227 Mutex::_as_suspend_equivalent_flag); 1228 } 1229 } 1230 1231 void WatcherThread::print_on(outputStream* st) const { 1232 st->print("\"%s\" ", name()); 1233 Thread::print_on(st); 1234 st->cr(); 1235 } 1236 1237 // ======= JavaThread ======== 1238 1239 // A JavaThread is a normal Java thread 1240 1241 void JavaThread::initialize() { 1242 // Initialize fields 1243 1244 // Set the claimed par_id to -1 (ie not claiming any par_ids) 1245 set_claimed_par_id(-1); 1246 1247 set_saved_exception_pc(NULL); 1248 set_threadObj(NULL); 1249 _anchor.clear(); 1250 set_entry_point(NULL); 1251 set_jni_functions(jni_functions()); 1252 set_callee_target(NULL); 1253 set_vm_result(NULL); 1254 set_vm_result_2(NULL); 1255 set_vframe_array_head(NULL); 1256 set_vframe_array_last(NULL); 1257 set_deferred_locals(NULL); 1258 set_deopt_mark(NULL); 1259 set_deopt_nmethod(NULL); 1260 clear_must_deopt_id(); 1261 set_monitor_chunks(NULL); 1262 set_next(NULL); 1263 set_thread_state(_thread_new); 1264 _terminated = _not_terminated; 1265 _privileged_stack_top = NULL; 1266 _array_for_gc = NULL; 1267 _suspend_equivalent = false; 1268 _in_deopt_handler = 0; 1269 _doing_unsafe_access = false; 1270 _stack_guard_state = stack_guard_unused; 1271 _exception_oop = NULL; 1272 _exception_pc = 0; 1273 _exception_handler_pc = 0; 1274 _exception_stack_size = 0; 1275 _is_method_handle_return = 0; 1276 _jvmti_thread_state= NULL; 1277 _should_post_on_exceptions_flag = JNI_FALSE; 1278 _jvmti_get_loaded_classes_closure = NULL; 1279 _interp_only_mode = 0; 1280 _special_runtime_exit_condition = _no_async_condition; 1281 _pending_async_exception = NULL; 1282 _is_compiling = false; 1283 _thread_stat = NULL; 1284 _thread_stat = new ThreadStatistics(); 1285 _blocked_on_compilation = false; 1286 _jni_active_critical = 0; 1287 _do_not_unlock_if_synchronized = false; 1288 _cached_monitor_info = NULL; 1289 _parker = Parker::Allocate(this) ; 1290 1291 #ifndef PRODUCT 1292 _jmp_ring_index = 0; 1293 for (int ji = 0 ; ji < jump_ring_buffer_size ; ji++ ) { 1294 record_jump(NULL, NULL, NULL, 0); 1295 } 1296 #endif /* PRODUCT */ 1297 1298 set_thread_profiler(NULL); 1299 if (FlatProfiler::is_active()) { 1300 // This is where we would decide to either give each thread it's own profiler 1301 // or use one global one from FlatProfiler, 1302 // or up to some count of the number of profiled threads, etc. 1303 ThreadProfiler* pp = new ThreadProfiler(); 1304 pp->engage(); 1305 set_thread_profiler(pp); 1306 } 1307 1308 // Setup safepoint state info for this thread 1309 ThreadSafepointState::create(this); 1310 1311 debug_only(_java_call_counter = 0); 1312 1313 // JVMTI PopFrame support 1314 _popframe_condition = popframe_inactive; 1315 _popframe_preserved_args = NULL; 1316 _popframe_preserved_args_size = 0; 1317 1318 pd_initialize(); 1319 } 1320 1321 #ifndef SERIALGC 1322 SATBMarkQueueSet JavaThread::_satb_mark_queue_set; 1323 DirtyCardQueueSet JavaThread::_dirty_card_queue_set; 1324 #endif // !SERIALGC 1325 1326 JavaThread::JavaThread(bool is_attaching) : 1327 Thread() 1328 #ifndef SERIALGC 1329 , _satb_mark_queue(&_satb_mark_queue_set), 1330 _dirty_card_queue(&_dirty_card_queue_set) 1331 #endif // !SERIALGC 1332 { 1333 initialize(); 1334 _is_attaching = is_attaching; 1335 assert(_deferred_card_mark.is_empty(), "Default MemRegion ctor"); 1336 } 1337 1338 bool JavaThread::reguard_stack(address cur_sp) { 1339 if (_stack_guard_state != stack_guard_yellow_disabled) { 1340 return true; // Stack already guarded or guard pages not needed. 1341 } 1342 1343 if (register_stack_overflow()) { 1344 // For those architectures which have separate register and 1345 // memory stacks, we must check the register stack to see if 1346 // it has overflowed. 1347 return false; 1348 } 1349 1350 // Java code never executes within the yellow zone: the latter is only 1351 // there to provoke an exception during stack banging. If java code 1352 // is executing there, either StackShadowPages should be larger, or 1353 // some exception code in c1, c2 or the interpreter isn't unwinding 1354 // when it should. 1355 guarantee(cur_sp > stack_yellow_zone_base(), "not enough space to reguard - increase StackShadowPages"); 1356 1357 enable_stack_yellow_zone(); 1358 return true; 1359 } 1360 1361 bool JavaThread::reguard_stack(void) { 1362 return reguard_stack(os::current_stack_pointer()); 1363 } 1364 1365 1366 void JavaThread::block_if_vm_exited() { 1367 if (_terminated == _vm_exited) { 1368 // _vm_exited is set at safepoint, and Threads_lock is never released 1369 // we will block here forever 1370 Threads_lock->lock_without_safepoint_check(); 1371 ShouldNotReachHere(); 1372 } 1373 } 1374 1375 1376 // Remove this ifdef when C1 is ported to the compiler interface. 1377 static void compiler_thread_entry(JavaThread* thread, TRAPS); 1378 1379 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) : 1380 Thread() 1381 #ifndef SERIALGC 1382 , _satb_mark_queue(&_satb_mark_queue_set), 1383 _dirty_card_queue(&_dirty_card_queue_set) 1384 #endif // !SERIALGC 1385 { 1386 if (TraceThreadEvents) { 1387 tty->print_cr("creating thread %p", this); 1388 } 1389 initialize(); 1390 _is_attaching = false; 1391 set_entry_point(entry_point); 1392 // Create the native thread itself. 1393 // %note runtime_23 1394 os::ThreadType thr_type = os::java_thread; 1395 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread : 1396 os::java_thread; 1397 os::create_thread(this, thr_type, stack_sz); 1398 1399 // The _osthread may be NULL here because we ran out of memory (too many threads active). 1400 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller 1401 // may hold a lock and all locks must be unlocked before throwing the exception (throwing 1402 // the exception consists of creating the exception object & initializing it, initialization 1403 // will leave the VM via a JavaCall and then all locks must be unlocked). 1404 // 1405 // The thread is still suspended when we reach here. Thread must be explicit started 1406 // by creator! Furthermore, the thread must also explicitly be added to the Threads list 1407 // by calling Threads:add. The reason why this is not done here, is because the thread 1408 // object must be fully initialized (take a look at JVM_Start) 1409 } 1410 1411 JavaThread::~JavaThread() { 1412 if (TraceThreadEvents) { 1413 tty->print_cr("terminate thread %p", this); 1414 } 1415 1416 // JSR166 -- return the parker to the free list 1417 Parker::Release(_parker); 1418 _parker = NULL ; 1419 1420 // Free any remaining previous UnrollBlock 1421 vframeArray* old_array = vframe_array_last(); 1422 1423 if (old_array != NULL) { 1424 Deoptimization::UnrollBlock* old_info = old_array->unroll_block(); 1425 old_array->set_unroll_block(NULL); 1426 delete old_info; 1427 delete old_array; 1428 } 1429 1430 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals(); 1431 if (deferred != NULL) { 1432 // This can only happen if thread is destroyed before deoptimization occurs. 1433 assert(deferred->length() != 0, "empty array!"); 1434 do { 1435 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0); 1436 deferred->remove_at(0); 1437 // individual jvmtiDeferredLocalVariableSet are CHeapObj's 1438 delete dlv; 1439 } while (deferred->length() != 0); 1440 delete deferred; 1441 } 1442 1443 // All Java related clean up happens in exit 1444 ThreadSafepointState::destroy(this); 1445 if (_thread_profiler != NULL) delete _thread_profiler; 1446 if (_thread_stat != NULL) delete _thread_stat; 1447 } 1448 1449 1450 // The first routine called by a new Java thread 1451 void JavaThread::run() { 1452 // initialize thread-local alloc buffer related fields 1453 this->initialize_tlab(); 1454 1455 // used to test validitity of stack trace backs 1456 this->record_base_of_stack_pointer(); 1457 1458 // Record real stack base and size. 1459 this->record_stack_base_and_size(); 1460 1461 // Initialize thread local storage; set before calling MutexLocker 1462 this->initialize_thread_local_storage(); 1463 1464 this->create_stack_guard_pages(); 1465 1466 this->cache_global_variables(); 1467 1468 // Thread is now sufficient initialized to be handled by the safepoint code as being 1469 // in the VM. Change thread state from _thread_new to _thread_in_vm 1470 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm); 1471 1472 assert(JavaThread::current() == this, "sanity check"); 1473 assert(!Thread::current()->owns_locks(), "sanity check"); 1474 1475 DTRACE_THREAD_PROBE(start, this); 1476 1477 // This operation might block. We call that after all safepoint checks for a new thread has 1478 // been completed. 1479 this->set_active_handles(JNIHandleBlock::allocate_block()); 1480 1481 if (JvmtiExport::should_post_thread_life()) { 1482 JvmtiExport::post_thread_start(this); 1483 } 1484 1485 // We call another function to do the rest so we are sure that the stack addresses used 1486 // from there will be lower than the stack base just computed 1487 thread_main_inner(); 1488 1489 // Note, thread is no longer valid at this point! 1490 } 1491 1492 1493 void JavaThread::thread_main_inner() { 1494 assert(JavaThread::current() == this, "sanity check"); 1495 assert(this->threadObj() != NULL, "just checking"); 1496 1497 // Execute thread entry point unless this thread has a pending exception 1498 // or has been stopped before starting. 1499 // Note: Due to JVM_StopThread we can have pending exceptions already! 1500 if (!this->has_pending_exception() && 1501 !java_lang_Thread::is_stillborn(this->threadObj())) { 1502 HandleMark hm(this); 1503 this->entry_point()(this, this); 1504 } 1505 1506 DTRACE_THREAD_PROBE(stop, this); 1507 1508 this->exit(false); 1509 delete this; 1510 } 1511 1512 1513 static void ensure_join(JavaThread* thread) { 1514 // We do not need to grap the Threads_lock, since we are operating on ourself. 1515 Handle threadObj(thread, thread->threadObj()); 1516 assert(threadObj.not_null(), "java thread object must exist"); 1517 ObjectLocker lock(threadObj, thread); 1518 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1519 thread->clear_pending_exception(); 1520 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED. 1521 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED); 1522 // Clear the native thread instance - this makes isAlive return false and allows the join() 1523 // to complete once we've done the notify_all below 1524 java_lang_Thread::set_thread(threadObj(), NULL); 1525 lock.notify_all(thread); 1526 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1527 thread->clear_pending_exception(); 1528 } 1529 1530 1531 // For any new cleanup additions, please check to see if they need to be applied to 1532 // cleanup_failed_attach_current_thread as well. 1533 void JavaThread::exit(bool destroy_vm, ExitType exit_type) { 1534 assert(this == JavaThread::current(), "thread consistency check"); 1535 if (!InitializeJavaLangSystem) return; 1536 1537 HandleMark hm(this); 1538 Handle uncaught_exception(this, this->pending_exception()); 1539 this->clear_pending_exception(); 1540 Handle threadObj(this, this->threadObj()); 1541 assert(threadObj.not_null(), "Java thread object should be created"); 1542 1543 if (get_thread_profiler() != NULL) { 1544 get_thread_profiler()->disengage(); 1545 ResourceMark rm; 1546 get_thread_profiler()->print(get_thread_name()); 1547 } 1548 1549 1550 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place 1551 { 1552 EXCEPTION_MARK; 1553 1554 CLEAR_PENDING_EXCEPTION; 1555 } 1556 // FIXIT: The is_null check is only so it works better on JDK1.2 VM's. This 1557 // has to be fixed by a runtime query method 1558 if (!destroy_vm || JDK_Version::is_jdk12x_version()) { 1559 // JSR-166: change call from from ThreadGroup.uncaughtException to 1560 // java.lang.Thread.dispatchUncaughtException 1561 if (uncaught_exception.not_null()) { 1562 Handle group(this, java_lang_Thread::threadGroup(threadObj())); 1563 Events::log("uncaught exception INTPTR_FORMAT " " INTPTR_FORMAT " " INTPTR_FORMAT", 1564 (address)uncaught_exception(), (address)threadObj(), (address)group()); 1565 { 1566 EXCEPTION_MARK; 1567 // Check if the method Thread.dispatchUncaughtException() exists. If so 1568 // call it. Otherwise we have an older library without the JSR-166 changes, 1569 // so call ThreadGroup.uncaughtException() 1570 KlassHandle recvrKlass(THREAD, threadObj->klass()); 1571 CallInfo callinfo; 1572 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass()); 1573 LinkResolver::resolve_virtual_call(callinfo, threadObj, recvrKlass, thread_klass, 1574 vmSymbols::dispatchUncaughtException_name(), 1575 vmSymbols::throwable_void_signature(), 1576 KlassHandle(), false, false, THREAD); 1577 CLEAR_PENDING_EXCEPTION; 1578 methodHandle method = callinfo.selected_method(); 1579 if (method.not_null()) { 1580 JavaValue result(T_VOID); 1581 JavaCalls::call_virtual(&result, 1582 threadObj, thread_klass, 1583 vmSymbols::dispatchUncaughtException_name(), 1584 vmSymbols::throwable_void_signature(), 1585 uncaught_exception, 1586 THREAD); 1587 } else { 1588 KlassHandle thread_group(THREAD, SystemDictionary::ThreadGroup_klass()); 1589 JavaValue result(T_VOID); 1590 JavaCalls::call_virtual(&result, 1591 group, thread_group, 1592 vmSymbols::uncaughtException_name(), 1593 vmSymbols::thread_throwable_void_signature(), 1594 threadObj, // Arg 1 1595 uncaught_exception, // Arg 2 1596 THREAD); 1597 } 1598 if (HAS_PENDING_EXCEPTION) { 1599 ResourceMark rm(this); 1600 jio_fprintf(defaultStream::error_stream(), 1601 "\nException: %s thrown from the UncaughtExceptionHandler" 1602 " in thread \"%s\"\n", 1603 Klass::cast(pending_exception()->klass())->external_name(), 1604 get_thread_name()); 1605 CLEAR_PENDING_EXCEPTION; 1606 } 1607 } 1608 } 1609 1610 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during 1611 // the execution of the method. If that is not enough, then we don't really care. Thread.stop 1612 // is deprecated anyhow. 1613 { int count = 3; 1614 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) { 1615 EXCEPTION_MARK; 1616 JavaValue result(T_VOID); 1617 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass()); 1618 JavaCalls::call_virtual(&result, 1619 threadObj, thread_klass, 1620 vmSymbols::exit_method_name(), 1621 vmSymbols::void_method_signature(), 1622 THREAD); 1623 CLEAR_PENDING_EXCEPTION; 1624 } 1625 } 1626 1627 // notify JVMTI 1628 if (JvmtiExport::should_post_thread_life()) { 1629 JvmtiExport::post_thread_end(this); 1630 } 1631 1632 // We have notified the agents that we are exiting, before we go on, 1633 // we must check for a pending external suspend request and honor it 1634 // in order to not surprise the thread that made the suspend request. 1635 while (true) { 1636 { 1637 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 1638 if (!is_external_suspend()) { 1639 set_terminated(_thread_exiting); 1640 ThreadService::current_thread_exiting(this); 1641 break; 1642 } 1643 // Implied else: 1644 // Things get a little tricky here. We have a pending external 1645 // suspend request, but we are holding the SR_lock so we 1646 // can't just self-suspend. So we temporarily drop the lock 1647 // and then self-suspend. 1648 } 1649 1650 ThreadBlockInVM tbivm(this); 1651 java_suspend_self(); 1652 1653 // We're done with this suspend request, but we have to loop around 1654 // and check again. Eventually we will get SR_lock without a pending 1655 // external suspend request and will be able to mark ourselves as 1656 // exiting. 1657 } 1658 // no more external suspends are allowed at this point 1659 } else { 1660 // before_exit() has already posted JVMTI THREAD_END events 1661 } 1662 1663 // Notify waiters on thread object. This has to be done after exit() is called 1664 // on the thread (if the thread is the last thread in a daemon ThreadGroup the 1665 // group should have the destroyed bit set before waiters are notified). 1666 ensure_join(this); 1667 assert(!this->has_pending_exception(), "ensure_join should have cleared"); 1668 1669 // 6282335 JNI DetachCurrentThread spec states that all Java monitors 1670 // held by this thread must be released. A detach operation must only 1671 // get here if there are no Java frames on the stack. Therefore, any 1672 // owned monitors at this point MUST be JNI-acquired monitors which are 1673 // pre-inflated and in the monitor cache. 1674 // 1675 // ensure_join() ignores IllegalThreadStateExceptions, and so does this. 1676 if (exit_type == jni_detach && JNIDetachReleasesMonitors) { 1677 assert(!this->has_last_Java_frame(), "detaching with Java frames?"); 1678 ObjectSynchronizer::release_monitors_owned_by_thread(this); 1679 assert(!this->has_pending_exception(), "release_monitors should have cleared"); 1680 } 1681 1682 // These things needs to be done while we are still a Java Thread. Make sure that thread 1683 // is in a consistent state, in case GC happens 1684 assert(_privileged_stack_top == NULL, "must be NULL when we get here"); 1685 1686 if (active_handles() != NULL) { 1687 JNIHandleBlock* block = active_handles(); 1688 set_active_handles(NULL); 1689 JNIHandleBlock::release_block(block); 1690 } 1691 1692 if (free_handle_block() != NULL) { 1693 JNIHandleBlock* block = free_handle_block(); 1694 set_free_handle_block(NULL); 1695 JNIHandleBlock::release_block(block); 1696 } 1697 1698 // These have to be removed while this is still a valid thread. 1699 remove_stack_guard_pages(); 1700 1701 if (UseTLAB) { 1702 tlab().make_parsable(true); // retire TLAB 1703 } 1704 1705 if (JvmtiEnv::environments_might_exist()) { 1706 JvmtiExport::cleanup_thread(this); 1707 } 1708 1709 #ifndef SERIALGC 1710 // We must flush G1-related buffers before removing a thread from 1711 // the list of active threads. 1712 if (UseG1GC) { 1713 flush_barrier_queues(); 1714 } 1715 #endif 1716 1717 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread 1718 Threads::remove(this); 1719 } 1720 1721 #ifndef SERIALGC 1722 // Flush G1-related queues. 1723 void JavaThread::flush_barrier_queues() { 1724 satb_mark_queue().flush(); 1725 dirty_card_queue().flush(); 1726 } 1727 1728 void JavaThread::initialize_queues() { 1729 assert(!SafepointSynchronize::is_at_safepoint(), 1730 "we should not be at a safepoint"); 1731 1732 ObjPtrQueue& satb_queue = satb_mark_queue(); 1733 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set(); 1734 // The SATB queue should have been constructed with its active 1735 // field set to false. 1736 assert(!satb_queue.is_active(), "SATB queue should not be active"); 1737 assert(satb_queue.is_empty(), "SATB queue should be empty"); 1738 // If we are creating the thread during a marking cycle, we should 1739 // set the active field of the SATB queue to true. 1740 if (satb_queue_set.is_active()) { 1741 satb_queue.set_active(true); 1742 } 1743 1744 DirtyCardQueue& dirty_queue = dirty_card_queue(); 1745 // The dirty card queue should have been constructed with its 1746 // active field set to true. 1747 assert(dirty_queue.is_active(), "dirty card queue should be active"); 1748 } 1749 #endif // !SERIALGC 1750 1751 void JavaThread::cleanup_failed_attach_current_thread() { 1752 if (get_thread_profiler() != NULL) { 1753 get_thread_profiler()->disengage(); 1754 ResourceMark rm; 1755 get_thread_profiler()->print(get_thread_name()); 1756 } 1757 1758 if (active_handles() != NULL) { 1759 JNIHandleBlock* block = active_handles(); 1760 set_active_handles(NULL); 1761 JNIHandleBlock::release_block(block); 1762 } 1763 1764 if (free_handle_block() != NULL) { 1765 JNIHandleBlock* block = free_handle_block(); 1766 set_free_handle_block(NULL); 1767 JNIHandleBlock::release_block(block); 1768 } 1769 1770 // These have to be removed while this is still a valid thread. 1771 remove_stack_guard_pages(); 1772 1773 if (UseTLAB) { 1774 tlab().make_parsable(true); // retire TLAB, if any 1775 } 1776 1777 #ifndef SERIALGC 1778 if (UseG1GC) { 1779 flush_barrier_queues(); 1780 } 1781 #endif 1782 1783 Threads::remove(this); 1784 delete this; 1785 } 1786 1787 1788 1789 1790 JavaThread* JavaThread::active() { 1791 Thread* thread = ThreadLocalStorage::thread(); 1792 assert(thread != NULL, "just checking"); 1793 if (thread->is_Java_thread()) { 1794 return (JavaThread*) thread; 1795 } else { 1796 assert(thread->is_VM_thread(), "this must be a vm thread"); 1797 VM_Operation* op = ((VMThread*) thread)->vm_operation(); 1798 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread(); 1799 assert(ret->is_Java_thread(), "must be a Java thread"); 1800 return ret; 1801 } 1802 } 1803 1804 bool JavaThread::is_lock_owned(address adr) const { 1805 if (Thread::is_lock_owned(adr)) return true; 1806 1807 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 1808 if (chunk->contains(adr)) return true; 1809 } 1810 1811 return false; 1812 } 1813 1814 1815 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) { 1816 chunk->set_next(monitor_chunks()); 1817 set_monitor_chunks(chunk); 1818 } 1819 1820 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) { 1821 guarantee(monitor_chunks() != NULL, "must be non empty"); 1822 if (monitor_chunks() == chunk) { 1823 set_monitor_chunks(chunk->next()); 1824 } else { 1825 MonitorChunk* prev = monitor_chunks(); 1826 while (prev->next() != chunk) prev = prev->next(); 1827 prev->set_next(chunk->next()); 1828 } 1829 } 1830 1831 // JVM support. 1832 1833 // Note: this function shouldn't block if it's called in 1834 // _thread_in_native_trans state (such as from 1835 // check_special_condition_for_native_trans()). 1836 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) { 1837 1838 if (has_last_Java_frame() && has_async_condition()) { 1839 // If we are at a polling page safepoint (not a poll return) 1840 // then we must defer async exception because live registers 1841 // will be clobbered by the exception path. Poll return is 1842 // ok because the call we a returning from already collides 1843 // with exception handling registers and so there is no issue. 1844 // (The exception handling path kills call result registers but 1845 // this is ok since the exception kills the result anyway). 1846 1847 if (is_at_poll_safepoint()) { 1848 // if the code we are returning to has deoptimized we must defer 1849 // the exception otherwise live registers get clobbered on the 1850 // exception path before deoptimization is able to retrieve them. 1851 // 1852 RegisterMap map(this, false); 1853 frame caller_fr = last_frame().sender(&map); 1854 assert(caller_fr.is_compiled_frame(), "what?"); 1855 if (caller_fr.is_deoptimized_frame()) { 1856 if (TraceExceptions) { 1857 ResourceMark rm; 1858 tty->print_cr("deferred async exception at compiled safepoint"); 1859 } 1860 return; 1861 } 1862 } 1863 } 1864 1865 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition(); 1866 if (condition == _no_async_condition) { 1867 // Conditions have changed since has_special_runtime_exit_condition() 1868 // was called: 1869 // - if we were here only because of an external suspend request, 1870 // then that was taken care of above (or cancelled) so we are done 1871 // - if we were here because of another async request, then it has 1872 // been cleared between the has_special_runtime_exit_condition() 1873 // and now so again we are done 1874 return; 1875 } 1876 1877 // Check for pending async. exception 1878 if (_pending_async_exception != NULL) { 1879 // Only overwrite an already pending exception, if it is not a threadDeath. 1880 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) { 1881 1882 // We cannot call Exceptions::_throw(...) here because we cannot block 1883 set_pending_exception(_pending_async_exception, __FILE__, __LINE__); 1884 1885 if (TraceExceptions) { 1886 ResourceMark rm; 1887 tty->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", this); 1888 if (has_last_Java_frame() ) { 1889 frame f = last_frame(); 1890 tty->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", f.pc(), f.sp()); 1891 } 1892 tty->print_cr(" of type: %s", instanceKlass::cast(_pending_async_exception->klass())->external_name()); 1893 } 1894 _pending_async_exception = NULL; 1895 clear_has_async_exception(); 1896 } 1897 } 1898 1899 if (check_unsafe_error && 1900 condition == _async_unsafe_access_error && !has_pending_exception()) { 1901 condition = _no_async_condition; // done 1902 switch (thread_state()) { 1903 case _thread_in_vm: 1904 { 1905 JavaThread* THREAD = this; 1906 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 1907 } 1908 case _thread_in_native: 1909 { 1910 ThreadInVMfromNative tiv(this); 1911 JavaThread* THREAD = this; 1912 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 1913 } 1914 case _thread_in_Java: 1915 { 1916 ThreadInVMfromJava tiv(this); 1917 JavaThread* THREAD = this; 1918 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code"); 1919 } 1920 default: 1921 ShouldNotReachHere(); 1922 } 1923 } 1924 1925 assert(condition == _no_async_condition || has_pending_exception() || 1926 (!check_unsafe_error && condition == _async_unsafe_access_error), 1927 "must have handled the async condition, if no exception"); 1928 } 1929 1930 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) { 1931 // 1932 // Check for pending external suspend. Internal suspend requests do 1933 // not use handle_special_runtime_exit_condition(). 1934 // If JNIEnv proxies are allowed, don't self-suspend if the target 1935 // thread is not the current thread. In older versions of jdbx, jdbx 1936 // threads could call into the VM with another thread's JNIEnv so we 1937 // can be here operating on behalf of a suspended thread (4432884). 1938 bool do_self_suspend = is_external_suspend_with_lock(); 1939 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) { 1940 // 1941 // Because thread is external suspended the safepoint code will count 1942 // thread as at a safepoint. This can be odd because we can be here 1943 // as _thread_in_Java which would normally transition to _thread_blocked 1944 // at a safepoint. We would like to mark the thread as _thread_blocked 1945 // before calling java_suspend_self like all other callers of it but 1946 // we must then observe proper safepoint protocol. (We can't leave 1947 // _thread_blocked with a safepoint in progress). However we can be 1948 // here as _thread_in_native_trans so we can't use a normal transition 1949 // constructor/destructor pair because they assert on that type of 1950 // transition. We could do something like: 1951 // 1952 // JavaThreadState state = thread_state(); 1953 // set_thread_state(_thread_in_vm); 1954 // { 1955 // ThreadBlockInVM tbivm(this); 1956 // java_suspend_self() 1957 // } 1958 // set_thread_state(_thread_in_vm_trans); 1959 // if (safepoint) block; 1960 // set_thread_state(state); 1961 // 1962 // but that is pretty messy. Instead we just go with the way the 1963 // code has worked before and note that this is the only path to 1964 // java_suspend_self that doesn't put the thread in _thread_blocked 1965 // mode. 1966 1967 frame_anchor()->make_walkable(this); 1968 java_suspend_self(); 1969 1970 // We might be here for reasons in addition to the self-suspend request 1971 // so check for other async requests. 1972 } 1973 1974 if (check_asyncs) { 1975 check_and_handle_async_exceptions(); 1976 } 1977 } 1978 1979 void JavaThread::send_thread_stop(oop java_throwable) { 1980 assert(Thread::current()->is_VM_thread(), "should be in the vm thread"); 1981 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code"); 1982 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 1983 1984 // Do not throw asynchronous exceptions against the compiler thread 1985 // (the compiler thread should not be a Java thread -- fix in 1.4.2) 1986 if (is_Compiler_thread()) return; 1987 1988 { 1989 // Actually throw the Throwable against the target Thread - however 1990 // only if there is no thread death exception installed already. 1991 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) { 1992 // If the topmost frame is a runtime stub, then we are calling into 1993 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..) 1994 // must deoptimize the caller before continuing, as the compiled exception handler table 1995 // may not be valid 1996 if (has_last_Java_frame()) { 1997 frame f = last_frame(); 1998 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) { 1999 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2000 RegisterMap reg_map(this, UseBiasedLocking); 2001 frame compiled_frame = f.sender(®_map); 2002 if (compiled_frame.can_be_deoptimized()) { 2003 Deoptimization::deoptimize(this, compiled_frame, ®_map); 2004 } 2005 } 2006 } 2007 2008 // Set async. pending exception in thread. 2009 set_pending_async_exception(java_throwable); 2010 2011 if (TraceExceptions) { 2012 ResourceMark rm; 2013 tty->print_cr("Pending Async. exception installed of type: %s", instanceKlass::cast(_pending_async_exception->klass())->external_name()); 2014 } 2015 // for AbortVMOnException flag 2016 NOT_PRODUCT(Exceptions::debug_check_abort(instanceKlass::cast(_pending_async_exception->klass())->external_name())); 2017 } 2018 } 2019 2020 2021 // Interrupt thread so it will wake up from a potential wait() 2022 Thread::interrupt(this); 2023 } 2024 2025 // External suspension mechanism. 2026 // 2027 // Tell the VM to suspend a thread when ever it knows that it does not hold on 2028 // to any VM_locks and it is at a transition 2029 // Self-suspension will happen on the transition out of the vm. 2030 // Catch "this" coming in from JNIEnv pointers when the thread has been freed 2031 // 2032 // Guarantees on return: 2033 // + Target thread will not execute any new bytecode (that's why we need to 2034 // force a safepoint) 2035 // + Target thread will not enter any new monitors 2036 // 2037 void JavaThread::java_suspend() { 2038 { MutexLocker mu(Threads_lock); 2039 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) { 2040 return; 2041 } 2042 } 2043 2044 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2045 if (!is_external_suspend()) { 2046 // a racing resume has cancelled us; bail out now 2047 return; 2048 } 2049 2050 // suspend is done 2051 uint32_t debug_bits = 0; 2052 // Warning: is_ext_suspend_completed() may temporarily drop the 2053 // SR_lock to allow the thread to reach a stable thread state if 2054 // it is currently in a transient thread state. 2055 if (is_ext_suspend_completed(false /* !called_by_wait */, 2056 SuspendRetryDelay, &debug_bits) ) { 2057 return; 2058 } 2059 } 2060 2061 VM_ForceSafepoint vm_suspend; 2062 VMThread::execute(&vm_suspend); 2063 } 2064 2065 // Part II of external suspension. 2066 // A JavaThread self suspends when it detects a pending external suspend 2067 // request. This is usually on transitions. It is also done in places 2068 // where continuing to the next transition would surprise the caller, 2069 // e.g., monitor entry. 2070 // 2071 // Returns the number of times that the thread self-suspended. 2072 // 2073 // Note: DO NOT call java_suspend_self() when you just want to block current 2074 // thread. java_suspend_self() is the second stage of cooperative 2075 // suspension for external suspend requests and should only be used 2076 // to complete an external suspend request. 2077 // 2078 int JavaThread::java_suspend_self() { 2079 int ret = 0; 2080 2081 // we are in the process of exiting so don't suspend 2082 if (is_exiting()) { 2083 clear_external_suspend(); 2084 return ret; 2085 } 2086 2087 assert(_anchor.walkable() || 2088 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()), 2089 "must have walkable stack"); 2090 2091 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2092 2093 assert(!this->is_ext_suspended(), 2094 "a thread trying to self-suspend should not already be suspended"); 2095 2096 if (this->is_suspend_equivalent()) { 2097 // If we are self-suspending as a result of the lifting of a 2098 // suspend equivalent condition, then the suspend_equivalent 2099 // flag is not cleared until we set the ext_suspended flag so 2100 // that wait_for_ext_suspend_completion() returns consistent 2101 // results. 2102 this->clear_suspend_equivalent(); 2103 } 2104 2105 // A racing resume may have cancelled us before we grabbed SR_lock 2106 // above. Or another external suspend request could be waiting for us 2107 // by the time we return from SR_lock()->wait(). The thread 2108 // that requested the suspension may already be trying to walk our 2109 // stack and if we return now, we can change the stack out from under 2110 // it. This would be a "bad thing (TM)" and cause the stack walker 2111 // to crash. We stay self-suspended until there are no more pending 2112 // external suspend requests. 2113 while (is_external_suspend()) { 2114 ret++; 2115 this->set_ext_suspended(); 2116 2117 // _ext_suspended flag is cleared by java_resume() 2118 while (is_ext_suspended()) { 2119 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag); 2120 } 2121 } 2122 2123 return ret; 2124 } 2125 2126 #ifdef ASSERT 2127 // verify the JavaThread has not yet been published in the Threads::list, and 2128 // hence doesn't need protection from concurrent access at this stage 2129 void JavaThread::verify_not_published() { 2130 if (!Threads_lock->owned_by_self()) { 2131 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag); 2132 assert( !Threads::includes(this), 2133 "java thread shouldn't have been published yet!"); 2134 } 2135 else { 2136 assert( !Threads::includes(this), 2137 "java thread shouldn't have been published yet!"); 2138 } 2139 } 2140 #endif 2141 2142 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2143 // progress or when _suspend_flags is non-zero. 2144 // Current thread needs to self-suspend if there is a suspend request and/or 2145 // block if a safepoint is in progress. 2146 // Async exception ISN'T checked. 2147 // Note only the ThreadInVMfromNative transition can call this function 2148 // directly and when thread state is _thread_in_native_trans 2149 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) { 2150 assert(thread->thread_state() == _thread_in_native_trans, "wrong state"); 2151 2152 JavaThread *curJT = JavaThread::current(); 2153 bool do_self_suspend = thread->is_external_suspend(); 2154 2155 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition"); 2156 2157 // If JNIEnv proxies are allowed, don't self-suspend if the target 2158 // thread is not the current thread. In older versions of jdbx, jdbx 2159 // threads could call into the VM with another thread's JNIEnv so we 2160 // can be here operating on behalf of a suspended thread (4432884). 2161 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) { 2162 JavaThreadState state = thread->thread_state(); 2163 2164 // We mark this thread_blocked state as a suspend-equivalent so 2165 // that a caller to is_ext_suspend_completed() won't be confused. 2166 // The suspend-equivalent state is cleared by java_suspend_self(). 2167 thread->set_suspend_equivalent(); 2168 2169 // If the safepoint code sees the _thread_in_native_trans state, it will 2170 // wait until the thread changes to other thread state. There is no 2171 // guarantee on how soon we can obtain the SR_lock and complete the 2172 // self-suspend request. It would be a bad idea to let safepoint wait for 2173 // too long. Temporarily change the state to _thread_blocked to 2174 // let the VM thread know that this thread is ready for GC. The problem 2175 // of changing thread state is that safepoint could happen just after 2176 // java_suspend_self() returns after being resumed, and VM thread will 2177 // see the _thread_blocked state. We must check for safepoint 2178 // after restoring the state and make sure we won't leave while a safepoint 2179 // is in progress. 2180 thread->set_thread_state(_thread_blocked); 2181 thread->java_suspend_self(); 2182 thread->set_thread_state(state); 2183 // Make sure new state is seen by VM thread 2184 if (os::is_MP()) { 2185 if (UseMembar) { 2186 // Force a fence between the write above and read below 2187 OrderAccess::fence(); 2188 } else { 2189 // Must use this rather than serialization page in particular on Windows 2190 InterfaceSupport::serialize_memory(thread); 2191 } 2192 } 2193 } 2194 2195 if (SafepointSynchronize::do_call_back()) { 2196 // If we are safepointing, then block the caller which may not be 2197 // the same as the target thread (see above). 2198 SafepointSynchronize::block(curJT); 2199 } 2200 2201 if (thread->is_deopt_suspend()) { 2202 thread->clear_deopt_suspend(); 2203 RegisterMap map(thread, false); 2204 frame f = thread->last_frame(); 2205 while ( f.id() != thread->must_deopt_id() && ! f.is_first_frame()) { 2206 f = f.sender(&map); 2207 } 2208 if (f.id() == thread->must_deopt_id()) { 2209 thread->clear_must_deopt_id(); 2210 f.deoptimize(thread); 2211 } else { 2212 fatal("missed deoptimization!"); 2213 } 2214 } 2215 } 2216 2217 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2218 // progress or when _suspend_flags is non-zero. 2219 // Current thread needs to self-suspend if there is a suspend request and/or 2220 // block if a safepoint is in progress. 2221 // Also check for pending async exception (not including unsafe access error). 2222 // Note only the native==>VM/Java barriers can call this function and when 2223 // thread state is _thread_in_native_trans. 2224 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) { 2225 check_safepoint_and_suspend_for_native_trans(thread); 2226 2227 if (thread->has_async_exception()) { 2228 // We are in _thread_in_native_trans state, don't handle unsafe 2229 // access error since that may block. 2230 thread->check_and_handle_async_exceptions(false); 2231 } 2232 } 2233 2234 // We need to guarantee the Threads_lock here, since resumes are not 2235 // allowed during safepoint synchronization 2236 // Can only resume from an external suspension 2237 void JavaThread::java_resume() { 2238 assert_locked_or_safepoint(Threads_lock); 2239 2240 // Sanity check: thread is gone, has started exiting or the thread 2241 // was not externally suspended. 2242 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) { 2243 return; 2244 } 2245 2246 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2247 2248 clear_external_suspend(); 2249 2250 if (is_ext_suspended()) { 2251 clear_ext_suspended(); 2252 SR_lock()->notify_all(); 2253 } 2254 } 2255 2256 void JavaThread::create_stack_guard_pages() { 2257 if (! os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) return; 2258 address low_addr = stack_base() - stack_size(); 2259 size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size(); 2260 2261 int allocate = os::allocate_stack_guard_pages(); 2262 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len); 2263 2264 if (allocate && !os::create_stack_guard_pages((char *) low_addr, len)) { 2265 warning("Attempt to allocate stack guard pages failed."); 2266 return; 2267 } 2268 2269 if (os::guard_memory((char *) low_addr, len)) { 2270 _stack_guard_state = stack_guard_enabled; 2271 } else { 2272 warning("Attempt to protect stack guard pages failed."); 2273 if (os::uncommit_memory((char *) low_addr, len)) { 2274 warning("Attempt to deallocate stack guard pages failed."); 2275 } 2276 } 2277 } 2278 2279 void JavaThread::remove_stack_guard_pages() { 2280 if (_stack_guard_state == stack_guard_unused) return; 2281 address low_addr = stack_base() - stack_size(); 2282 size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size(); 2283 2284 if (os::allocate_stack_guard_pages()) { 2285 if (os::remove_stack_guard_pages((char *) low_addr, len)) { 2286 _stack_guard_state = stack_guard_unused; 2287 } else { 2288 warning("Attempt to deallocate stack guard pages failed."); 2289 } 2290 } else { 2291 if (_stack_guard_state == stack_guard_unused) return; 2292 if (os::unguard_memory((char *) low_addr, len)) { 2293 _stack_guard_state = stack_guard_unused; 2294 } else { 2295 warning("Attempt to unprotect stack guard pages failed."); 2296 } 2297 } 2298 } 2299 2300 void JavaThread::enable_stack_yellow_zone() { 2301 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2302 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2303 2304 // The base notation is from the stacks point of view, growing downward. 2305 // We need to adjust it to work correctly with guard_memory() 2306 address base = stack_yellow_zone_base() - stack_yellow_zone_size(); 2307 2308 guarantee(base < stack_base(),"Error calculating stack yellow zone"); 2309 guarantee(base < os::current_stack_pointer(),"Error calculating stack yellow zone"); 2310 2311 if (os::guard_memory((char *) base, stack_yellow_zone_size())) { 2312 _stack_guard_state = stack_guard_enabled; 2313 } else { 2314 warning("Attempt to guard stack yellow zone failed."); 2315 } 2316 enable_register_stack_guard(); 2317 } 2318 2319 void JavaThread::disable_stack_yellow_zone() { 2320 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2321 assert(_stack_guard_state != stack_guard_yellow_disabled, "already disabled"); 2322 2323 // Simply return if called for a thread that does not use guard pages. 2324 if (_stack_guard_state == stack_guard_unused) return; 2325 2326 // The base notation is from the stacks point of view, growing downward. 2327 // We need to adjust it to work correctly with guard_memory() 2328 address base = stack_yellow_zone_base() - stack_yellow_zone_size(); 2329 2330 if (os::unguard_memory((char *)base, stack_yellow_zone_size())) { 2331 _stack_guard_state = stack_guard_yellow_disabled; 2332 } else { 2333 warning("Attempt to unguard stack yellow zone failed."); 2334 } 2335 disable_register_stack_guard(); 2336 } 2337 2338 void JavaThread::enable_stack_red_zone() { 2339 // The base notation is from the stacks point of view, growing downward. 2340 // We need to adjust it to work correctly with guard_memory() 2341 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2342 address base = stack_red_zone_base() - stack_red_zone_size(); 2343 2344 guarantee(base < stack_base(),"Error calculating stack red zone"); 2345 guarantee(base < os::current_stack_pointer(),"Error calculating stack red zone"); 2346 2347 if(!os::guard_memory((char *) base, stack_red_zone_size())) { 2348 warning("Attempt to guard stack red zone failed."); 2349 } 2350 } 2351 2352 void JavaThread::disable_stack_red_zone() { 2353 // The base notation is from the stacks point of view, growing downward. 2354 // We need to adjust it to work correctly with guard_memory() 2355 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2356 address base = stack_red_zone_base() - stack_red_zone_size(); 2357 if (!os::unguard_memory((char *)base, stack_red_zone_size())) { 2358 warning("Attempt to unguard stack red zone failed."); 2359 } 2360 } 2361 2362 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) { 2363 // ignore is there is no stack 2364 if (!has_last_Java_frame()) return; 2365 // traverse the stack frames. Starts from top frame. 2366 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2367 frame* fr = fst.current(); 2368 f(fr, fst.register_map()); 2369 } 2370 } 2371 2372 2373 #ifndef PRODUCT 2374 // Deoptimization 2375 // Function for testing deoptimization 2376 void JavaThread::deoptimize() { 2377 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2378 StackFrameStream fst(this, UseBiasedLocking); 2379 bool deopt = false; // Dump stack only if a deopt actually happens. 2380 bool only_at = strlen(DeoptimizeOnlyAt) > 0; 2381 // Iterate over all frames in the thread and deoptimize 2382 for(; !fst.is_done(); fst.next()) { 2383 if(fst.current()->can_be_deoptimized()) { 2384 2385 if (only_at) { 2386 // Deoptimize only at particular bcis. DeoptimizeOnlyAt 2387 // consists of comma or carriage return separated numbers so 2388 // search for the current bci in that string. 2389 address pc = fst.current()->pc(); 2390 nmethod* nm = (nmethod*) fst.current()->cb(); 2391 ScopeDesc* sd = nm->scope_desc_at( pc); 2392 char buffer[8]; 2393 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci()); 2394 size_t len = strlen(buffer); 2395 const char * found = strstr(DeoptimizeOnlyAt, buffer); 2396 while (found != NULL) { 2397 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') && 2398 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) { 2399 // Check that the bci found is bracketed by terminators. 2400 break; 2401 } 2402 found = strstr(found + 1, buffer); 2403 } 2404 if (!found) { 2405 continue; 2406 } 2407 } 2408 2409 if (DebugDeoptimization && !deopt) { 2410 deopt = true; // One-time only print before deopt 2411 tty->print_cr("[BEFORE Deoptimization]"); 2412 trace_frames(); 2413 trace_stack(); 2414 } 2415 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2416 } 2417 } 2418 2419 if (DebugDeoptimization && deopt) { 2420 tty->print_cr("[AFTER Deoptimization]"); 2421 trace_frames(); 2422 } 2423 } 2424 2425 2426 // Make zombies 2427 void JavaThread::make_zombies() { 2428 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2429 if (fst.current()->can_be_deoptimized()) { 2430 // it is a Java nmethod 2431 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc()); 2432 nm->make_not_entrant(); 2433 } 2434 } 2435 } 2436 #endif // PRODUCT 2437 2438 2439 void JavaThread::deoptimized_wrt_marked_nmethods() { 2440 if (!has_last_Java_frame()) return; 2441 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2442 StackFrameStream fst(this, UseBiasedLocking); 2443 for(; !fst.is_done(); fst.next()) { 2444 if (fst.current()->should_be_deoptimized()) { 2445 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2446 } 2447 } 2448 } 2449 2450 2451 // GC support 2452 static void frame_gc_epilogue(frame* f, const RegisterMap* map) { f->gc_epilogue(); } 2453 2454 void JavaThread::gc_epilogue() { 2455 frames_do(frame_gc_epilogue); 2456 } 2457 2458 2459 static void frame_gc_prologue(frame* f, const RegisterMap* map) { f->gc_prologue(); } 2460 2461 void JavaThread::gc_prologue() { 2462 frames_do(frame_gc_prologue); 2463 } 2464 2465 // If the caller is a NamedThread, then remember, in the current scope, 2466 // the given JavaThread in its _processed_thread field. 2467 class RememberProcessedThread: public StackObj { 2468 NamedThread* _cur_thr; 2469 public: 2470 RememberProcessedThread(JavaThread* jthr) { 2471 Thread* thread = Thread::current(); 2472 if (thread->is_Named_thread()) { 2473 _cur_thr = (NamedThread *)thread; 2474 _cur_thr->set_processed_thread(jthr); 2475 } else { 2476 _cur_thr = NULL; 2477 } 2478 } 2479 2480 ~RememberProcessedThread() { 2481 if (_cur_thr) { 2482 _cur_thr->set_processed_thread(NULL); 2483 } 2484 } 2485 }; 2486 2487 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 2488 // Verify that the deferred card marks have been flushed. 2489 assert(deferred_card_mark().is_empty(), "Should be empty during GC"); 2490 2491 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do 2492 // since there may be more than one thread using each ThreadProfiler. 2493 2494 // Traverse the GCHandles 2495 Thread::oops_do(f, cf); 2496 2497 assert( (!has_last_Java_frame() && java_call_counter() == 0) || 2498 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2499 2500 if (has_last_Java_frame()) { 2501 // Record JavaThread to GC thread 2502 RememberProcessedThread rpt(this); 2503 2504 // Traverse the privileged stack 2505 if (_privileged_stack_top != NULL) { 2506 _privileged_stack_top->oops_do(f); 2507 } 2508 2509 // traverse the registered growable array 2510 if (_array_for_gc != NULL) { 2511 for (int index = 0; index < _array_for_gc->length(); index++) { 2512 f->do_oop(_array_for_gc->adr_at(index)); 2513 } 2514 } 2515 2516 // Traverse the monitor chunks 2517 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2518 chunk->oops_do(f); 2519 } 2520 2521 // Traverse the execution stack 2522 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2523 fst.current()->oops_do(f, cf, fst.register_map()); 2524 } 2525 } 2526 2527 // callee_target is never live across a gc point so NULL it here should 2528 // it still contain a methdOop. 2529 2530 set_callee_target(NULL); 2531 2532 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!"); 2533 // If we have deferred set_locals there might be oops waiting to be 2534 // written 2535 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals(); 2536 if (list != NULL) { 2537 for (int i = 0; i < list->length(); i++) { 2538 list->at(i)->oops_do(f); 2539 } 2540 } 2541 2542 // Traverse instance variables at the end since the GC may be moving things 2543 // around using this function 2544 f->do_oop((oop*) &_threadObj); 2545 f->do_oop((oop*) &_vm_result); 2546 f->do_oop((oop*) &_vm_result_2); 2547 f->do_oop((oop*) &_exception_oop); 2548 f->do_oop((oop*) &_pending_async_exception); 2549 2550 if (jvmti_thread_state() != NULL) { 2551 jvmti_thread_state()->oops_do(f); 2552 } 2553 } 2554 2555 void JavaThread::nmethods_do(CodeBlobClosure* cf) { 2556 Thread::nmethods_do(cf); // (super method is a no-op) 2557 2558 assert( (!has_last_Java_frame() && java_call_counter() == 0) || 2559 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2560 2561 if (has_last_Java_frame()) { 2562 // Traverse the execution stack 2563 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2564 fst.current()->nmethods_do(cf); 2565 } 2566 } 2567 } 2568 2569 // Printing 2570 const char* _get_thread_state_name(JavaThreadState _thread_state) { 2571 switch (_thread_state) { 2572 case _thread_uninitialized: return "_thread_uninitialized"; 2573 case _thread_new: return "_thread_new"; 2574 case _thread_new_trans: return "_thread_new_trans"; 2575 case _thread_in_native: return "_thread_in_native"; 2576 case _thread_in_native_trans: return "_thread_in_native_trans"; 2577 case _thread_in_vm: return "_thread_in_vm"; 2578 case _thread_in_vm_trans: return "_thread_in_vm_trans"; 2579 case _thread_in_Java: return "_thread_in_Java"; 2580 case _thread_in_Java_trans: return "_thread_in_Java_trans"; 2581 case _thread_blocked: return "_thread_blocked"; 2582 case _thread_blocked_trans: return "_thread_blocked_trans"; 2583 default: return "unknown thread state"; 2584 } 2585 } 2586 2587 #ifndef PRODUCT 2588 void JavaThread::print_thread_state_on(outputStream *st) const { 2589 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state)); 2590 }; 2591 void JavaThread::print_thread_state() const { 2592 print_thread_state_on(tty); 2593 }; 2594 #endif // PRODUCT 2595 2596 // Called by Threads::print() for VM_PrintThreads operation 2597 void JavaThread::print_on(outputStream *st) const { 2598 st->print("\"%s\" ", get_thread_name()); 2599 oop thread_oop = threadObj(); 2600 if (thread_oop != NULL && java_lang_Thread::is_daemon(thread_oop)) st->print("daemon "); 2601 Thread::print_on(st); 2602 // print guess for valid stack memory region (assume 4K pages); helps lock debugging 2603 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12)); 2604 if (thread_oop != NULL && JDK_Version::is_gte_jdk15x_version()) { 2605 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop)); 2606 } 2607 #ifndef PRODUCT 2608 print_thread_state_on(st); 2609 _safepoint_state->print_on(st); 2610 #endif // PRODUCT 2611 } 2612 2613 // Called by fatal error handler. The difference between this and 2614 // JavaThread::print() is that we can't grab lock or allocate memory. 2615 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const { 2616 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen)); 2617 oop thread_obj = threadObj(); 2618 if (thread_obj != NULL) { 2619 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon"); 2620 } 2621 st->print(" ["); 2622 st->print("%s", _get_thread_state_name(_thread_state)); 2623 if (osthread()) { 2624 st->print(", id=%d", osthread()->thread_id()); 2625 } 2626 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")", 2627 _stack_base - _stack_size, _stack_base); 2628 st->print("]"); 2629 return; 2630 } 2631 2632 // Verification 2633 2634 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); } 2635 2636 void JavaThread::verify() { 2637 // Verify oops in the thread. 2638 oops_do(&VerifyOopClosure::verify_oop, NULL); 2639 2640 // Verify the stack frames. 2641 frames_do(frame_verify); 2642 } 2643 2644 // CR 6300358 (sub-CR 2137150) 2645 // Most callers of this method assume that it can't return NULL but a 2646 // thread may not have a name whilst it is in the process of attaching to 2647 // the VM - see CR 6412693, and there are places where a JavaThread can be 2648 // seen prior to having it's threadObj set (eg JNI attaching threads and 2649 // if vm exit occurs during initialization). These cases can all be accounted 2650 // for such that this method never returns NULL. 2651 const char* JavaThread::get_thread_name() const { 2652 #ifdef ASSERT 2653 // early safepoints can hit while current thread does not yet have TLS 2654 if (!SafepointSynchronize::is_at_safepoint()) { 2655 Thread *cur = Thread::current(); 2656 if (!(cur->is_Java_thread() && cur == this)) { 2657 // Current JavaThreads are allowed to get their own name without 2658 // the Threads_lock. 2659 assert_locked_or_safepoint(Threads_lock); 2660 } 2661 } 2662 #endif // ASSERT 2663 return get_thread_name_string(); 2664 } 2665 2666 // Returns a non-NULL representation of this thread's name, or a suitable 2667 // descriptive string if there is no set name 2668 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const { 2669 const char* name_str; 2670 oop thread_obj = threadObj(); 2671 if (thread_obj != NULL) { 2672 typeArrayOop name = java_lang_Thread::name(thread_obj); 2673 if (name != NULL) { 2674 if (buf == NULL) { 2675 name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length()); 2676 } 2677 else { 2678 name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length(), buf, buflen); 2679 } 2680 } 2681 else if (is_attaching()) { // workaround for 6412693 - see 6404306 2682 name_str = "<no-name - thread is attaching>"; 2683 } 2684 else { 2685 name_str = Thread::name(); 2686 } 2687 } 2688 else { 2689 name_str = Thread::name(); 2690 } 2691 assert(name_str != NULL, "unexpected NULL thread name"); 2692 return name_str; 2693 } 2694 2695 2696 const char* JavaThread::get_threadgroup_name() const { 2697 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 2698 oop thread_obj = threadObj(); 2699 if (thread_obj != NULL) { 2700 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 2701 if (thread_group != NULL) { 2702 typeArrayOop name = java_lang_ThreadGroup::name(thread_group); 2703 // ThreadGroup.name can be null 2704 if (name != NULL) { 2705 const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length()); 2706 return str; 2707 } 2708 } 2709 } 2710 return NULL; 2711 } 2712 2713 const char* JavaThread::get_parent_name() const { 2714 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 2715 oop thread_obj = threadObj(); 2716 if (thread_obj != NULL) { 2717 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 2718 if (thread_group != NULL) { 2719 oop parent = java_lang_ThreadGroup::parent(thread_group); 2720 if (parent != NULL) { 2721 typeArrayOop name = java_lang_ThreadGroup::name(parent); 2722 // ThreadGroup.name can be null 2723 if (name != NULL) { 2724 const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length()); 2725 return str; 2726 } 2727 } 2728 } 2729 } 2730 return NULL; 2731 } 2732 2733 ThreadPriority JavaThread::java_priority() const { 2734 oop thr_oop = threadObj(); 2735 if (thr_oop == NULL) return NormPriority; // Bootstrapping 2736 ThreadPriority priority = java_lang_Thread::priority(thr_oop); 2737 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check"); 2738 return priority; 2739 } 2740 2741 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) { 2742 2743 assert(Threads_lock->owner() == Thread::current(), "must have threads lock"); 2744 // Link Java Thread object <-> C++ Thread 2745 2746 // Get the C++ thread object (an oop) from the JNI handle (a jthread) 2747 // and put it into a new Handle. The Handle "thread_oop" can then 2748 // be used to pass the C++ thread object to other methods. 2749 2750 // Set the Java level thread object (jthread) field of the 2751 // new thread (a JavaThread *) to C++ thread object using the 2752 // "thread_oop" handle. 2753 2754 // Set the thread field (a JavaThread *) of the 2755 // oop representing the java_lang_Thread to the new thread (a JavaThread *). 2756 2757 Handle thread_oop(Thread::current(), 2758 JNIHandles::resolve_non_null(jni_thread)); 2759 assert(instanceKlass::cast(thread_oop->klass())->is_linked(), 2760 "must be initialized"); 2761 set_threadObj(thread_oop()); 2762 java_lang_Thread::set_thread(thread_oop(), this); 2763 2764 if (prio == NoPriority) { 2765 prio = java_lang_Thread::priority(thread_oop()); 2766 assert(prio != NoPriority, "A valid priority should be present"); 2767 } 2768 2769 // Push the Java priority down to the native thread; needs Threads_lock 2770 Thread::set_priority(this, prio); 2771 2772 // Add the new thread to the Threads list and set it in motion. 2773 // We must have threads lock in order to call Threads::add. 2774 // It is crucial that we do not block before the thread is 2775 // added to the Threads list for if a GC happens, then the java_thread oop 2776 // will not be visited by GC. 2777 Threads::add(this); 2778 } 2779 2780 oop JavaThread::current_park_blocker() { 2781 // Support for JSR-166 locks 2782 oop thread_oop = threadObj(); 2783 if (thread_oop != NULL && 2784 JDK_Version::current().supports_thread_park_blocker()) { 2785 return java_lang_Thread::park_blocker(thread_oop); 2786 } 2787 return NULL; 2788 } 2789 2790 2791 void JavaThread::print_stack_on(outputStream* st) { 2792 if (!has_last_Java_frame()) return; 2793 ResourceMark rm; 2794 HandleMark hm; 2795 2796 RegisterMap reg_map(this); 2797 vframe* start_vf = last_java_vframe(®_map); 2798 int count = 0; 2799 for (vframe* f = start_vf; f; f = f->sender() ) { 2800 if (f->is_java_frame()) { 2801 javaVFrame* jvf = javaVFrame::cast(f); 2802 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci()); 2803 2804 // Print out lock information 2805 if (JavaMonitorsInStackTrace) { 2806 jvf->print_lock_info_on(st, count); 2807 } 2808 } else { 2809 // Ignore non-Java frames 2810 } 2811 2812 // Bail-out case for too deep stacks 2813 count++; 2814 if (MaxJavaStackTraceDepth == count) return; 2815 } 2816 } 2817 2818 2819 // JVMTI PopFrame support 2820 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) { 2821 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments"); 2822 if (in_bytes(size_in_bytes) != 0) { 2823 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes)); 2824 _popframe_preserved_args_size = in_bytes(size_in_bytes); 2825 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size); 2826 } 2827 } 2828 2829 void* JavaThread::popframe_preserved_args() { 2830 return _popframe_preserved_args; 2831 } 2832 2833 ByteSize JavaThread::popframe_preserved_args_size() { 2834 return in_ByteSize(_popframe_preserved_args_size); 2835 } 2836 2837 WordSize JavaThread::popframe_preserved_args_size_in_words() { 2838 int sz = in_bytes(popframe_preserved_args_size()); 2839 assert(sz % wordSize == 0, "argument size must be multiple of wordSize"); 2840 return in_WordSize(sz / wordSize); 2841 } 2842 2843 void JavaThread::popframe_free_preserved_args() { 2844 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice"); 2845 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args); 2846 _popframe_preserved_args = NULL; 2847 _popframe_preserved_args_size = 0; 2848 } 2849 2850 #ifndef PRODUCT 2851 2852 void JavaThread::trace_frames() { 2853 tty->print_cr("[Describe stack]"); 2854 int frame_no = 1; 2855 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2856 tty->print(" %d. ", frame_no++); 2857 fst.current()->print_value_on(tty,this); 2858 tty->cr(); 2859 } 2860 } 2861 2862 2863 void JavaThread::trace_stack_from(vframe* start_vf) { 2864 ResourceMark rm; 2865 int vframe_no = 1; 2866 for (vframe* f = start_vf; f; f = f->sender() ) { 2867 if (f->is_java_frame()) { 2868 javaVFrame::cast(f)->print_activation(vframe_no++); 2869 } else { 2870 f->print(); 2871 } 2872 if (vframe_no > StackPrintLimit) { 2873 tty->print_cr("...<more frames>..."); 2874 return; 2875 } 2876 } 2877 } 2878 2879 2880 void JavaThread::trace_stack() { 2881 if (!has_last_Java_frame()) return; 2882 ResourceMark rm; 2883 HandleMark hm; 2884 RegisterMap reg_map(this); 2885 trace_stack_from(last_java_vframe(®_map)); 2886 } 2887 2888 2889 #endif // PRODUCT 2890 2891 2892 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) { 2893 assert(reg_map != NULL, "a map must be given"); 2894 frame f = last_frame(); 2895 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender() ) { 2896 if (vf->is_java_frame()) return javaVFrame::cast(vf); 2897 } 2898 return NULL; 2899 } 2900 2901 2902 klassOop JavaThread::security_get_caller_class(int depth) { 2903 vframeStream vfst(this); 2904 vfst.security_get_caller_frame(depth); 2905 if (!vfst.at_end()) { 2906 return vfst.method()->method_holder(); 2907 } 2908 return NULL; 2909 } 2910 2911 static void compiler_thread_entry(JavaThread* thread, TRAPS) { 2912 assert(thread->is_Compiler_thread(), "must be compiler thread"); 2913 CompileBroker::compiler_thread_loop(); 2914 } 2915 2916 // Create a CompilerThread 2917 CompilerThread::CompilerThread(CompileQueue* queue, CompilerCounters* counters) 2918 : JavaThread(&compiler_thread_entry) { 2919 _env = NULL; 2920 _log = NULL; 2921 _task = NULL; 2922 _queue = queue; 2923 _counters = counters; 2924 _buffer_blob = NULL; 2925 2926 #ifndef PRODUCT 2927 _ideal_graph_printer = NULL; 2928 #endif 2929 } 2930 2931 2932 // ======= Threads ======== 2933 2934 // The Threads class links together all active threads, and provides 2935 // operations over all threads. It is protected by its own Mutex 2936 // lock, which is also used in other contexts to protect thread 2937 // operations from having the thread being operated on from exiting 2938 // and going away unexpectedly (e.g., safepoint synchronization) 2939 2940 JavaThread* Threads::_thread_list = NULL; 2941 int Threads::_number_of_threads = 0; 2942 int Threads::_number_of_non_daemon_threads = 0; 2943 int Threads::_return_code = 0; 2944 size_t JavaThread::_stack_size_at_create = 0; 2945 2946 // All JavaThreads 2947 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next()) 2948 2949 void os_stream(); 2950 2951 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system) 2952 void Threads::threads_do(ThreadClosure* tc) { 2953 assert_locked_or_safepoint(Threads_lock); 2954 // ALL_JAVA_THREADS iterates through all JavaThreads 2955 ALL_JAVA_THREADS(p) { 2956 tc->do_thread(p); 2957 } 2958 // Someday we could have a table or list of all non-JavaThreads. 2959 // For now, just manually iterate through them. 2960 tc->do_thread(VMThread::vm_thread()); 2961 Universe::heap()->gc_threads_do(tc); 2962 WatcherThread *wt = WatcherThread::watcher_thread(); 2963 // Strictly speaking, the following NULL check isn't sufficient to make sure 2964 // the data for WatcherThread is still valid upon being examined. However, 2965 // considering that WatchThread terminates when the VM is on the way to 2966 // exit at safepoint, the chance of the above is extremely small. The right 2967 // way to prevent termination of WatcherThread would be to acquire 2968 // Terminator_lock, but we can't do that without violating the lock rank 2969 // checking in some cases. 2970 if (wt != NULL) 2971 tc->do_thread(wt); 2972 2973 // If CompilerThreads ever become non-JavaThreads, add them here 2974 } 2975 2976 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) { 2977 2978 extern void JDK_Version_init(); 2979 2980 // Check version 2981 if (!is_supported_jni_version(args->version)) return JNI_EVERSION; 2982 2983 // Initialize the output stream module 2984 ostream_init(); 2985 2986 // Process java launcher properties. 2987 Arguments::process_sun_java_launcher_properties(args); 2988 2989 // Initialize the os module before using TLS 2990 os::init(); 2991 2992 // Initialize system properties. 2993 Arguments::init_system_properties(); 2994 2995 // So that JDK version can be used as a discrimintor when parsing arguments 2996 JDK_Version_init(); 2997 2998 // Update/Initialize System properties after JDK version number is known 2999 Arguments::init_version_specific_system_properties(); 3000 3001 // Parse arguments 3002 jint parse_result = Arguments::parse(args); 3003 if (parse_result != JNI_OK) return parse_result; 3004 3005 if (PauseAtStartup) { 3006 os::pause(); 3007 } 3008 3009 HS_DTRACE_PROBE(hotspot, vm__init__begin); 3010 3011 // Record VM creation timing statistics 3012 TraceVmCreationTime create_vm_timer; 3013 create_vm_timer.start(); 3014 3015 // Timing (must come after argument parsing) 3016 TraceTime timer("Create VM", TraceStartupTime); 3017 3018 // Initialize the os module after parsing the args 3019 jint os_init_2_result = os::init_2(); 3020 if (os_init_2_result != JNI_OK) return os_init_2_result; 3021 3022 // Initialize output stream logging 3023 ostream_init_log(); 3024 3025 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad 3026 // Must be before create_vm_init_agents() 3027 if (Arguments::init_libraries_at_startup()) { 3028 convert_vm_init_libraries_to_agents(); 3029 } 3030 3031 // Launch -agentlib/-agentpath and converted -Xrun agents 3032 if (Arguments::init_agents_at_startup()) { 3033 create_vm_init_agents(); 3034 } 3035 3036 // Initialize Threads state 3037 _thread_list = NULL; 3038 _number_of_threads = 0; 3039 _number_of_non_daemon_threads = 0; 3040 3041 // Initialize TLS 3042 ThreadLocalStorage::init(); 3043 3044 // Initialize global data structures and create system classes in heap 3045 vm_init_globals(); 3046 3047 // Attach the main thread to this os thread 3048 JavaThread* main_thread = new JavaThread(); 3049 main_thread->set_thread_state(_thread_in_vm); 3050 // must do this before set_active_handles and initialize_thread_local_storage 3051 // Note: on solaris initialize_thread_local_storage() will (indirectly) 3052 // change the stack size recorded here to one based on the java thread 3053 // stacksize. This adjusted size is what is used to figure the placement 3054 // of the guard pages. 3055 main_thread->record_stack_base_and_size(); 3056 main_thread->initialize_thread_local_storage(); 3057 3058 main_thread->set_active_handles(JNIHandleBlock::allocate_block()); 3059 3060 if (!main_thread->set_as_starting_thread()) { 3061 vm_shutdown_during_initialization( 3062 "Failed necessary internal allocation. Out of swap space"); 3063 delete main_thread; 3064 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3065 return JNI_ENOMEM; 3066 } 3067 3068 // Enable guard page *after* os::create_main_thread(), otherwise it would 3069 // crash Linux VM, see notes in os_linux.cpp. 3070 main_thread->create_stack_guard_pages(); 3071 3072 // Initialize Java-Level synchronization subsystem 3073 ObjectMonitor::Initialize() ; 3074 3075 // Initialize global modules 3076 jint status = init_globals(); 3077 if (status != JNI_OK) { 3078 delete main_thread; 3079 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3080 return status; 3081 } 3082 3083 // Should be done after the heap is fully created 3084 main_thread->cache_global_variables(); 3085 3086 HandleMark hm; 3087 3088 { MutexLocker mu(Threads_lock); 3089 Threads::add(main_thread); 3090 } 3091 3092 // Any JVMTI raw monitors entered in onload will transition into 3093 // real raw monitor. VM is setup enough here for raw monitor enter. 3094 JvmtiExport::transition_pending_onload_raw_monitors(); 3095 3096 if (VerifyBeforeGC && 3097 Universe::heap()->total_collections() >= VerifyGCStartAt) { 3098 Universe::heap()->prepare_for_verify(); 3099 Universe::verify(); // make sure we're starting with a clean slate 3100 } 3101 3102 // Create the VMThread 3103 { TraceTime timer("Start VMThread", TraceStartupTime); 3104 VMThread::create(); 3105 Thread* vmthread = VMThread::vm_thread(); 3106 3107 if (!os::create_thread(vmthread, os::vm_thread)) 3108 vm_exit_during_initialization("Cannot create VM thread. Out of system resources."); 3109 3110 // Wait for the VM thread to become ready, and VMThread::run to initialize 3111 // Monitors can have spurious returns, must always check another state flag 3112 { 3113 MutexLocker ml(Notify_lock); 3114 os::start_thread(vmthread); 3115 while (vmthread->active_handles() == NULL) { 3116 Notify_lock->wait(); 3117 } 3118 } 3119 } 3120 3121 assert (Universe::is_fully_initialized(), "not initialized"); 3122 EXCEPTION_MARK; 3123 3124 // At this point, the Universe is initialized, but we have not executed 3125 // any byte code. Now is a good time (the only time) to dump out the 3126 // internal state of the JVM for sharing. 3127 3128 if (DumpSharedSpaces) { 3129 Universe::heap()->preload_and_dump(CHECK_0); 3130 ShouldNotReachHere(); 3131 } 3132 3133 // Always call even when there are not JVMTI environments yet, since environments 3134 // may be attached late and JVMTI must track phases of VM execution 3135 JvmtiExport::enter_start_phase(); 3136 3137 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3138 JvmtiExport::post_vm_start(); 3139 3140 { 3141 TraceTime timer("Initialize java.lang classes", TraceStartupTime); 3142 3143 if (EagerXrunInit && Arguments::init_libraries_at_startup()) { 3144 create_vm_init_libraries(); 3145 } 3146 3147 if (InitializeJavaLangString) { 3148 initialize_class(vmSymbols::java_lang_String(), CHECK_0); 3149 } else { 3150 warning("java.lang.String not initialized"); 3151 } 3152 3153 if (AggressiveOpts) { 3154 { 3155 // Forcibly initialize java/util/HashMap and mutate the private 3156 // static final "frontCacheEnabled" field before we start creating instances 3157 #ifdef ASSERT 3158 klassOop tmp_k = SystemDictionary::find(vmSymbols::java_util_HashMap(), Handle(), Handle(), CHECK_0); 3159 assert(tmp_k == NULL, "java/util/HashMap should not be loaded yet"); 3160 #endif 3161 klassOop k_o = SystemDictionary::resolve_or_null(vmSymbols::java_util_HashMap(), Handle(), Handle(), CHECK_0); 3162 KlassHandle k = KlassHandle(THREAD, k_o); 3163 guarantee(k.not_null(), "Must find java/util/HashMap"); 3164 instanceKlassHandle ik = instanceKlassHandle(THREAD, k()); 3165 ik->initialize(CHECK_0); 3166 fieldDescriptor fd; 3167 // Possible we might not find this field; if so, don't break 3168 if (ik->find_local_field(vmSymbols::frontCacheEnabled_name(), vmSymbols::bool_signature(), &fd)) { 3169 k()->bool_field_put(fd.offset(), true); 3170 } 3171 } 3172 3173 if (UseStringCache) { 3174 // Forcibly initialize java/lang/StringValue and mutate the private 3175 // static final "stringCacheEnabled" field before we start creating instances 3176 klassOop k_o = SystemDictionary::resolve_or_null(vmSymbols::java_lang_StringValue(), Handle(), Handle(), CHECK_0); 3177 // Possible that StringValue isn't present: if so, silently don't break 3178 if (k_o != NULL) { 3179 KlassHandle k = KlassHandle(THREAD, k_o); 3180 instanceKlassHandle ik = instanceKlassHandle(THREAD, k()); 3181 ik->initialize(CHECK_0); 3182 fieldDescriptor fd; 3183 // Possible we might not find this field: if so, silently don't break 3184 if (ik->find_local_field(vmSymbols::stringCacheEnabled_name(), vmSymbols::bool_signature(), &fd)) { 3185 k()->bool_field_put(fd.offset(), true); 3186 } 3187 } 3188 } 3189 } 3190 3191 // Initialize java_lang.System (needed before creating the thread) 3192 if (InitializeJavaLangSystem) { 3193 initialize_class(vmSymbols::java_lang_System(), CHECK_0); 3194 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK_0); 3195 Handle thread_group = create_initial_thread_group(CHECK_0); 3196 Universe::set_main_thread_group(thread_group()); 3197 initialize_class(vmSymbols::java_lang_Thread(), CHECK_0); 3198 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK_0); 3199 main_thread->set_threadObj(thread_object); 3200 // Set thread status to running since main thread has 3201 // been started and running. 3202 java_lang_Thread::set_thread_status(thread_object, 3203 java_lang_Thread::RUNNABLE); 3204 3205 // The VM preresolve methods to these classes. Make sure that get initialized 3206 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK_0); 3207 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK_0); 3208 // The VM creates & returns objects of this class. Make sure it's initialized. 3209 initialize_class(vmSymbols::java_lang_Class(), CHECK_0); 3210 call_initializeSystemClass(CHECK_0); 3211 } else { 3212 warning("java.lang.System not initialized"); 3213 } 3214 3215 // an instance of OutOfMemory exception has been allocated earlier 3216 if (InitializeJavaLangExceptionsErrors) { 3217 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK_0); 3218 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK_0); 3219 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK_0); 3220 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK_0); 3221 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK_0); 3222 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK_0); 3223 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK_0); 3224 } else { 3225 warning("java.lang.OutOfMemoryError has not been initialized"); 3226 warning("java.lang.NullPointerException has not been initialized"); 3227 warning("java.lang.ClassCastException has not been initialized"); 3228 warning("java.lang.ArrayStoreException has not been initialized"); 3229 warning("java.lang.ArithmeticException has not been initialized"); 3230 warning("java.lang.StackOverflowError has not been initialized"); 3231 } 3232 } 3233 3234 // See : bugid 4211085. 3235 // Background : the static initializer of java.lang.Compiler tries to read 3236 // property"java.compiler" and read & write property "java.vm.info". 3237 // When a security manager is installed through the command line 3238 // option "-Djava.security.manager", the above properties are not 3239 // readable and the static initializer for java.lang.Compiler fails 3240 // resulting in a NoClassDefFoundError. This can happen in any 3241 // user code which calls methods in java.lang.Compiler. 3242 // Hack : the hack is to pre-load and initialize this class, so that only 3243 // system domains are on the stack when the properties are read. 3244 // Currently even the AWT code has calls to methods in java.lang.Compiler. 3245 // On the classic VM, java.lang.Compiler is loaded very early to load the JIT. 3246 // Future Fix : the best fix is to grant everyone permissions to read "java.compiler" and 3247 // read and write"java.vm.info" in the default policy file. See bugid 4211383 3248 // Once that is done, we should remove this hack. 3249 initialize_class(vmSymbols::java_lang_Compiler(), CHECK_0); 3250 3251 // More hackery - the static initializer of java.lang.Compiler adds the string "nojit" to 3252 // the java.vm.info property if no jit gets loaded through java.lang.Compiler (the hotspot 3253 // compiler does not get loaded through java.lang.Compiler). "java -version" with the 3254 // hotspot vm says "nojit" all the time which is confusing. So, we reset it here. 3255 // This should also be taken out as soon as 4211383 gets fixed. 3256 reset_vm_info_property(CHECK_0); 3257 3258 quicken_jni_functions(); 3259 3260 // Set flag that basic initialization has completed. Used by exceptions and various 3261 // debug stuff, that does not work until all basic classes have been initialized. 3262 set_init_completed(); 3263 3264 HS_DTRACE_PROBE(hotspot, vm__init__end); 3265 3266 // record VM initialization completion time 3267 Management::record_vm_init_completed(); 3268 3269 // Compute system loader. Note that this has to occur after set_init_completed, since 3270 // valid exceptions may be thrown in the process. 3271 // Note that we do not use CHECK_0 here since we are inside an EXCEPTION_MARK and 3272 // set_init_completed has just been called, causing exceptions not to be shortcut 3273 // anymore. We call vm_exit_during_initialization directly instead. 3274 SystemDictionary::compute_java_system_loader(THREAD); 3275 if (HAS_PENDING_EXCEPTION) { 3276 vm_exit_during_initialization(Handle(THREAD, PENDING_EXCEPTION)); 3277 } 3278 3279 #ifndef SERIALGC 3280 // Support for ConcurrentMarkSweep. This should be cleaned up 3281 // and better encapsulated. The ugly nested if test would go away 3282 // once things are properly refactored. XXX YSR 3283 if (UseConcMarkSweepGC || UseG1GC) { 3284 if (UseConcMarkSweepGC) { 3285 ConcurrentMarkSweepThread::makeSurrogateLockerThread(THREAD); 3286 } else { 3287 ConcurrentMarkThread::makeSurrogateLockerThread(THREAD); 3288 } 3289 if (HAS_PENDING_EXCEPTION) { 3290 vm_exit_during_initialization(Handle(THREAD, PENDING_EXCEPTION)); 3291 } 3292 } 3293 #endif // SERIALGC 3294 3295 // Always call even when there are not JVMTI environments yet, since environments 3296 // may be attached late and JVMTI must track phases of VM execution 3297 JvmtiExport::enter_live_phase(); 3298 3299 // Signal Dispatcher needs to be started before VMInit event is posted 3300 os::signal_init(); 3301 3302 // Start Attach Listener if +StartAttachListener or it can't be started lazily 3303 if (!DisableAttachMechanism) { 3304 if (StartAttachListener || AttachListener::init_at_startup()) { 3305 AttachListener::init(); 3306 } 3307 } 3308 3309 // Launch -Xrun agents 3310 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP 3311 // back-end can launch with -Xdebug -Xrunjdwp. 3312 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) { 3313 create_vm_init_libraries(); 3314 } 3315 3316 // Notify JVMTI agents that VM initialization is complete - nop if no agents. 3317 JvmtiExport::post_vm_initialized(); 3318 3319 Chunk::start_chunk_pool_cleaner_task(); 3320 3321 // initialize compiler(s) 3322 CompileBroker::compilation_init(); 3323 3324 Management::initialize(THREAD); 3325 if (HAS_PENDING_EXCEPTION) { 3326 // management agent fails to start possibly due to 3327 // configuration problem and is responsible for printing 3328 // stack trace if appropriate. Simply exit VM. 3329 vm_exit(1); 3330 } 3331 3332 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true); 3333 if (Arguments::has_alloc_profile()) AllocationProfiler::engage(); 3334 if (MemProfiling) MemProfiler::engage(); 3335 StatSampler::engage(); 3336 if (CheckJNICalls) JniPeriodicChecker::engage(); 3337 3338 BiasedLocking::init(); 3339 3340 if (JDK_Version::current().post_vm_init_hook_enabled()) { 3341 call_postVMInitHook(THREAD); 3342 // The Java side of PostVMInitHook.run must deal with all 3343 // exceptions and provide means of diagnosis. 3344 if (HAS_PENDING_EXCEPTION) { 3345 CLEAR_PENDING_EXCEPTION; 3346 } 3347 } 3348 3349 // Start up the WatcherThread if there are any periodic tasks 3350 // NOTE: All PeriodicTasks should be registered by now. If they 3351 // aren't, late joiners might appear to start slowly (we might 3352 // take a while to process their first tick). 3353 if (PeriodicTask::num_tasks() > 0) { 3354 WatcherThread::start(); 3355 } 3356 3357 // Give os specific code one last chance to start 3358 os::init_3(); 3359 3360 create_vm_timer.end(); 3361 return JNI_OK; 3362 } 3363 3364 // type for the Agent_OnLoad and JVM_OnLoad entry points 3365 extern "C" { 3366 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *); 3367 } 3368 // Find a command line agent library and return its entry point for 3369 // -agentlib: -agentpath: -Xrun 3370 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array. 3371 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, const char *on_load_symbols[], size_t num_symbol_entries) { 3372 OnLoadEntry_t on_load_entry = NULL; 3373 void *library = agent->os_lib(); // check if we have looked it up before 3374 3375 if (library == NULL) { 3376 char buffer[JVM_MAXPATHLEN]; 3377 char ebuf[1024]; 3378 const char *name = agent->name(); 3379 const char *msg = "Could not find agent library "; 3380 3381 if (agent->is_absolute_path()) { 3382 library = os::dll_load(name, ebuf, sizeof ebuf); 3383 if (library == NULL) { 3384 const char *sub_msg = " in absolute path, with error: "; 3385 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 3386 char *buf = NEW_C_HEAP_ARRAY(char, len); 3387 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 3388 // If we can't find the agent, exit. 3389 vm_exit_during_initialization(buf, NULL); 3390 FREE_C_HEAP_ARRAY(char, buf); 3391 } 3392 } else { 3393 // Try to load the agent from the standard dll directory 3394 os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(), name); 3395 library = os::dll_load(buffer, ebuf, sizeof ebuf); 3396 #ifdef KERNEL 3397 // Download instrument dll 3398 if (library == NULL && strcmp(name, "instrument") == 0) { 3399 char *props = Arguments::get_kernel_properties(); 3400 char *home = Arguments::get_java_home(); 3401 const char *fmt = "%s/bin/java %s -Dkernel.background.download=false" 3402 " sun.jkernel.DownloadManager -download client_jvm"; 3403 size_t length = strlen(props) + strlen(home) + strlen(fmt) + 1; 3404 char *cmd = NEW_C_HEAP_ARRAY(char, length); 3405 jio_snprintf(cmd, length, fmt, home, props); 3406 int status = os::fork_and_exec(cmd); 3407 FreeHeap(props); 3408 if (status == -1) { 3409 warning(cmd); 3410 vm_exit_during_initialization("fork_and_exec failed: %s", 3411 strerror(errno)); 3412 } 3413 FREE_C_HEAP_ARRAY(char, cmd); 3414 // when this comes back the instrument.dll should be where it belongs. 3415 library = os::dll_load(buffer, ebuf, sizeof ebuf); 3416 } 3417 #endif // KERNEL 3418 if (library == NULL) { // Try the local directory 3419 char ns[1] = {0}; 3420 os::dll_build_name(buffer, sizeof(buffer), ns, name); 3421 library = os::dll_load(buffer, ebuf, sizeof ebuf); 3422 if (library == NULL) { 3423 const char *sub_msg = " on the library path, with error: "; 3424 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 3425 char *buf = NEW_C_HEAP_ARRAY(char, len); 3426 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 3427 // If we can't find the agent, exit. 3428 vm_exit_during_initialization(buf, NULL); 3429 FREE_C_HEAP_ARRAY(char, buf); 3430 } 3431 } 3432 } 3433 agent->set_os_lib(library); 3434 } 3435 3436 // Find the OnLoad function. 3437 for (size_t symbol_index = 0; symbol_index < num_symbol_entries; symbol_index++) { 3438 on_load_entry = CAST_TO_FN_PTR(OnLoadEntry_t, os::dll_lookup(library, on_load_symbols[symbol_index])); 3439 if (on_load_entry != NULL) break; 3440 } 3441 return on_load_entry; 3442 } 3443 3444 // Find the JVM_OnLoad entry point 3445 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) { 3446 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS; 3447 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 3448 } 3449 3450 // Find the Agent_OnLoad entry point 3451 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) { 3452 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS; 3453 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 3454 } 3455 3456 // For backwards compatibility with -Xrun 3457 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be 3458 // treated like -agentpath: 3459 // Must be called before agent libraries are created 3460 void Threads::convert_vm_init_libraries_to_agents() { 3461 AgentLibrary* agent; 3462 AgentLibrary* next; 3463 3464 for (agent = Arguments::libraries(); agent != NULL; agent = next) { 3465 next = agent->next(); // cache the next agent now as this agent may get moved off this list 3466 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 3467 3468 // If there is an JVM_OnLoad function it will get called later, 3469 // otherwise see if there is an Agent_OnLoad 3470 if (on_load_entry == NULL) { 3471 on_load_entry = lookup_agent_on_load(agent); 3472 if (on_load_entry != NULL) { 3473 // switch it to the agent list -- so that Agent_OnLoad will be called, 3474 // JVM_OnLoad won't be attempted and Agent_OnUnload will 3475 Arguments::convert_library_to_agent(agent); 3476 } else { 3477 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name()); 3478 } 3479 } 3480 } 3481 } 3482 3483 // Create agents for -agentlib: -agentpath: and converted -Xrun 3484 // Invokes Agent_OnLoad 3485 // Called very early -- before JavaThreads exist 3486 void Threads::create_vm_init_agents() { 3487 extern struct JavaVM_ main_vm; 3488 AgentLibrary* agent; 3489 3490 JvmtiExport::enter_onload_phase(); 3491 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 3492 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent); 3493 3494 if (on_load_entry != NULL) { 3495 // Invoke the Agent_OnLoad function 3496 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 3497 if (err != JNI_OK) { 3498 vm_exit_during_initialization("agent library failed to init", agent->name()); 3499 } 3500 } else { 3501 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name()); 3502 } 3503 } 3504 JvmtiExport::enter_primordial_phase(); 3505 } 3506 3507 extern "C" { 3508 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *); 3509 } 3510 3511 void Threads::shutdown_vm_agents() { 3512 // Send any Agent_OnUnload notifications 3513 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS; 3514 extern struct JavaVM_ main_vm; 3515 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 3516 3517 // Find the Agent_OnUnload function. 3518 for (uint symbol_index = 0; symbol_index < ARRAY_SIZE(on_unload_symbols); symbol_index++) { 3519 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t, 3520 os::dll_lookup(agent->os_lib(), on_unload_symbols[symbol_index])); 3521 3522 // Invoke the Agent_OnUnload function 3523 if (unload_entry != NULL) { 3524 JavaThread* thread = JavaThread::current(); 3525 ThreadToNativeFromVM ttn(thread); 3526 HandleMark hm(thread); 3527 (*unload_entry)(&main_vm); 3528 break; 3529 } 3530 } 3531 } 3532 } 3533 3534 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries 3535 // Invokes JVM_OnLoad 3536 void Threads::create_vm_init_libraries() { 3537 extern struct JavaVM_ main_vm; 3538 AgentLibrary* agent; 3539 3540 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) { 3541 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 3542 3543 if (on_load_entry != NULL) { 3544 // Invoke the JVM_OnLoad function 3545 JavaThread* thread = JavaThread::current(); 3546 ThreadToNativeFromVM ttn(thread); 3547 HandleMark hm(thread); 3548 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 3549 if (err != JNI_OK) { 3550 vm_exit_during_initialization("-Xrun library failed to init", agent->name()); 3551 } 3552 } else { 3553 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name()); 3554 } 3555 } 3556 } 3557 3558 // Last thread running calls java.lang.Shutdown.shutdown() 3559 void JavaThread::invoke_shutdown_hooks() { 3560 HandleMark hm(this); 3561 3562 // We could get here with a pending exception, if so clear it now. 3563 if (this->has_pending_exception()) { 3564 this->clear_pending_exception(); 3565 } 3566 3567 EXCEPTION_MARK; 3568 klassOop k = 3569 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(), 3570 THREAD); 3571 if (k != NULL) { 3572 // SystemDictionary::resolve_or_null will return null if there was 3573 // an exception. If we cannot load the Shutdown class, just don't 3574 // call Shutdown.shutdown() at all. This will mean the shutdown hooks 3575 // and finalizers (if runFinalizersOnExit is set) won't be run. 3576 // Note that if a shutdown hook was registered or runFinalizersOnExit 3577 // was called, the Shutdown class would have already been loaded 3578 // (Runtime.addShutdownHook and runFinalizersOnExit will load it). 3579 instanceKlassHandle shutdown_klass (THREAD, k); 3580 JavaValue result(T_VOID); 3581 JavaCalls::call_static(&result, 3582 shutdown_klass, 3583 vmSymbols::shutdown_method_name(), 3584 vmSymbols::void_method_signature(), 3585 THREAD); 3586 } 3587 CLEAR_PENDING_EXCEPTION; 3588 } 3589 3590 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when 3591 // the program falls off the end of main(). Another VM exit path is through 3592 // vm_exit() when the program calls System.exit() to return a value or when 3593 // there is a serious error in VM. The two shutdown paths are not exactly 3594 // the same, but they share Shutdown.shutdown() at Java level and before_exit() 3595 // and VM_Exit op at VM level. 3596 // 3597 // Shutdown sequence: 3598 // + Wait until we are the last non-daemon thread to execute 3599 // <-- every thing is still working at this moment --> 3600 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level 3601 // shutdown hooks, run finalizers if finalization-on-exit 3602 // + Call before_exit(), prepare for VM exit 3603 // > run VM level shutdown hooks (they are registered through JVM_OnExit(), 3604 // currently the only user of this mechanism is File.deleteOnExit()) 3605 // > stop flat profiler, StatSampler, watcher thread, CMS threads, 3606 // post thread end and vm death events to JVMTI, 3607 // stop signal thread 3608 // + Call JavaThread::exit(), it will: 3609 // > release JNI handle blocks, remove stack guard pages 3610 // > remove this thread from Threads list 3611 // <-- no more Java code from this thread after this point --> 3612 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop 3613 // the compiler threads at safepoint 3614 // <-- do not use anything that could get blocked by Safepoint --> 3615 // + Disable tracing at JNI/JVM barriers 3616 // + Set _vm_exited flag for threads that are still running native code 3617 // + Delete this thread 3618 // + Call exit_globals() 3619 // > deletes tty 3620 // > deletes PerfMemory resources 3621 // + Return to caller 3622 3623 bool Threads::destroy_vm() { 3624 JavaThread* thread = JavaThread::current(); 3625 3626 // Wait until we are the last non-daemon thread to execute 3627 { MutexLocker nu(Threads_lock); 3628 while (Threads::number_of_non_daemon_threads() > 1 ) 3629 // This wait should make safepoint checks, wait without a timeout, 3630 // and wait as a suspend-equivalent condition. 3631 // 3632 // Note: If the FlatProfiler is running and this thread is waiting 3633 // for another non-daemon thread to finish, then the FlatProfiler 3634 // is waiting for the external suspend request on this thread to 3635 // complete. wait_for_ext_suspend_completion() will eventually 3636 // timeout, but that takes time. Making this wait a suspend- 3637 // equivalent condition solves that timeout problem. 3638 // 3639 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 3640 Mutex::_as_suspend_equivalent_flag); 3641 } 3642 3643 // Hang forever on exit if we are reporting an error. 3644 if (ShowMessageBoxOnError && is_error_reported()) { 3645 os::infinite_sleep(); 3646 } 3647 3648 if (JDK_Version::is_jdk12x_version()) { 3649 // We are the last thread running, so check if finalizers should be run. 3650 // For 1.3 or later this is done in thread->invoke_shutdown_hooks() 3651 HandleMark rm(thread); 3652 Universe::run_finalizers_on_exit(); 3653 } else { 3654 // run Java level shutdown hooks 3655 thread->invoke_shutdown_hooks(); 3656 } 3657 3658 before_exit(thread); 3659 3660 thread->exit(true); 3661 3662 // Stop VM thread. 3663 { 3664 // 4945125 The vm thread comes to a safepoint during exit. 3665 // GC vm_operations can get caught at the safepoint, and the 3666 // heap is unparseable if they are caught. Grab the Heap_lock 3667 // to prevent this. The GC vm_operations will not be able to 3668 // queue until after the vm thread is dead. 3669 MutexLocker ml(Heap_lock); 3670 3671 VMThread::wait_for_vm_thread_exit(); 3672 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint"); 3673 VMThread::destroy(); 3674 } 3675 3676 // clean up ideal graph printers 3677 #if defined(COMPILER2) && !defined(PRODUCT) 3678 IdealGraphPrinter::clean_up(); 3679 #endif 3680 3681 // Now, all Java threads are gone except daemon threads. Daemon threads 3682 // running Java code or in VM are stopped by the Safepoint. However, 3683 // daemon threads executing native code are still running. But they 3684 // will be stopped at native=>Java/VM barriers. Note that we can't 3685 // simply kill or suspend them, as it is inherently deadlock-prone. 3686 3687 #ifndef PRODUCT 3688 // disable function tracing at JNI/JVM barriers 3689 TraceJNICalls = false; 3690 TraceJVMCalls = false; 3691 TraceRuntimeCalls = false; 3692 #endif 3693 3694 VM_Exit::set_vm_exited(); 3695 3696 notify_vm_shutdown(); 3697 3698 delete thread; 3699 3700 // exit_globals() will delete tty 3701 exit_globals(); 3702 3703 return true; 3704 } 3705 3706 3707 jboolean Threads::is_supported_jni_version_including_1_1(jint version) { 3708 if (version == JNI_VERSION_1_1) return JNI_TRUE; 3709 return is_supported_jni_version(version); 3710 } 3711 3712 3713 jboolean Threads::is_supported_jni_version(jint version) { 3714 if (version == JNI_VERSION_1_2) return JNI_TRUE; 3715 if (version == JNI_VERSION_1_4) return JNI_TRUE; 3716 if (version == JNI_VERSION_1_6) return JNI_TRUE; 3717 return JNI_FALSE; 3718 } 3719 3720 3721 void Threads::add(JavaThread* p, bool force_daemon) { 3722 // The threads lock must be owned at this point 3723 assert_locked_or_safepoint(Threads_lock); 3724 3725 // See the comment for this method in thread.hpp for its purpose and 3726 // why it is called here. 3727 p->initialize_queues(); 3728 p->set_next(_thread_list); 3729 _thread_list = p; 3730 _number_of_threads++; 3731 oop threadObj = p->threadObj(); 3732 bool daemon = true; 3733 // Bootstrapping problem: threadObj can be null for initial 3734 // JavaThread (or for threads attached via JNI) 3735 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) { 3736 _number_of_non_daemon_threads++; 3737 daemon = false; 3738 } 3739 3740 ThreadService::add_thread(p, daemon); 3741 3742 // Possible GC point. 3743 Events::log("Thread added: " INTPTR_FORMAT, p); 3744 } 3745 3746 void Threads::remove(JavaThread* p) { 3747 // Extra scope needed for Thread_lock, so we can check 3748 // that we do not remove thread without safepoint code notice 3749 { MutexLocker ml(Threads_lock); 3750 3751 assert(includes(p), "p must be present"); 3752 3753 JavaThread* current = _thread_list; 3754 JavaThread* prev = NULL; 3755 3756 while (current != p) { 3757 prev = current; 3758 current = current->next(); 3759 } 3760 3761 if (prev) { 3762 prev->set_next(current->next()); 3763 } else { 3764 _thread_list = p->next(); 3765 } 3766 _number_of_threads--; 3767 oop threadObj = p->threadObj(); 3768 bool daemon = true; 3769 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) { 3770 _number_of_non_daemon_threads--; 3771 daemon = false; 3772 3773 // Only one thread left, do a notify on the Threads_lock so a thread waiting 3774 // on destroy_vm will wake up. 3775 if (number_of_non_daemon_threads() == 1) 3776 Threads_lock->notify_all(); 3777 } 3778 ThreadService::remove_thread(p, daemon); 3779 3780 // Make sure that safepoint code disregard this thread. This is needed since 3781 // the thread might mess around with locks after this point. This can cause it 3782 // to do callbacks into the safepoint code. However, the safepoint code is not aware 3783 // of this thread since it is removed from the queue. 3784 p->set_terminated_value(); 3785 } // unlock Threads_lock 3786 3787 // Since Events::log uses a lock, we grab it outside the Threads_lock 3788 Events::log("Thread exited: " INTPTR_FORMAT, p); 3789 } 3790 3791 // Threads_lock must be held when this is called (or must be called during a safepoint) 3792 bool Threads::includes(JavaThread* p) { 3793 assert(Threads_lock->is_locked(), "sanity check"); 3794 ALL_JAVA_THREADS(q) { 3795 if (q == p ) { 3796 return true; 3797 } 3798 } 3799 return false; 3800 } 3801 3802 // Operations on the Threads list for GC. These are not explicitly locked, 3803 // but the garbage collector must provide a safe context for them to run. 3804 // In particular, these things should never be called when the Threads_lock 3805 // is held by some other thread. (Note: the Safepoint abstraction also 3806 // uses the Threads_lock to gurantee this property. It also makes sure that 3807 // all threads gets blocked when exiting or starting). 3808 3809 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) { 3810 ALL_JAVA_THREADS(p) { 3811 p->oops_do(f, cf); 3812 } 3813 VMThread::vm_thread()->oops_do(f, cf); 3814 } 3815 3816 void Threads::possibly_parallel_oops_do(OopClosure* f, CodeBlobClosure* cf) { 3817 // Introduce a mechanism allowing parallel threads to claim threads as 3818 // root groups. Overhead should be small enough to use all the time, 3819 // even in sequential code. 3820 SharedHeap* sh = SharedHeap::heap(); 3821 bool is_par = (sh->n_par_threads() > 0); 3822 int cp = SharedHeap::heap()->strong_roots_parity(); 3823 ALL_JAVA_THREADS(p) { 3824 if (p->claim_oops_do(is_par, cp)) { 3825 p->oops_do(f, cf); 3826 } 3827 } 3828 VMThread* vmt = VMThread::vm_thread(); 3829 if (vmt->claim_oops_do(is_par, cp)) 3830 vmt->oops_do(f, cf); 3831 } 3832 3833 #ifndef SERIALGC 3834 // Used by ParallelScavenge 3835 void Threads::create_thread_roots_tasks(GCTaskQueue* q) { 3836 ALL_JAVA_THREADS(p) { 3837 q->enqueue(new ThreadRootsTask(p)); 3838 } 3839 q->enqueue(new ThreadRootsTask(VMThread::vm_thread())); 3840 } 3841 3842 // Used by Parallel Old 3843 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) { 3844 ALL_JAVA_THREADS(p) { 3845 q->enqueue(new ThreadRootsMarkingTask(p)); 3846 } 3847 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread())); 3848 } 3849 #endif // SERIALGC 3850 3851 void Threads::nmethods_do(CodeBlobClosure* cf) { 3852 ALL_JAVA_THREADS(p) { 3853 p->nmethods_do(cf); 3854 } 3855 VMThread::vm_thread()->nmethods_do(cf); 3856 } 3857 3858 void Threads::gc_epilogue() { 3859 ALL_JAVA_THREADS(p) { 3860 p->gc_epilogue(); 3861 } 3862 } 3863 3864 void Threads::gc_prologue() { 3865 ALL_JAVA_THREADS(p) { 3866 p->gc_prologue(); 3867 } 3868 } 3869 3870 void Threads::deoptimized_wrt_marked_nmethods() { 3871 ALL_JAVA_THREADS(p) { 3872 p->deoptimized_wrt_marked_nmethods(); 3873 } 3874 } 3875 3876 3877 // Get count Java threads that are waiting to enter the specified monitor. 3878 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count, 3879 address monitor, bool doLock) { 3880 assert(doLock || SafepointSynchronize::is_at_safepoint(), 3881 "must grab Threads_lock or be at safepoint"); 3882 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count); 3883 3884 int i = 0; 3885 { 3886 MutexLockerEx ml(doLock ? Threads_lock : NULL); 3887 ALL_JAVA_THREADS(p) { 3888 if (p->is_Compiler_thread()) continue; 3889 3890 address pending = (address)p->current_pending_monitor(); 3891 if (pending == monitor) { // found a match 3892 if (i < count) result->append(p); // save the first count matches 3893 i++; 3894 } 3895 } 3896 } 3897 return result; 3898 } 3899 3900 3901 JavaThread *Threads::owning_thread_from_monitor_owner(address owner, bool doLock) { 3902 assert(doLock || 3903 Threads_lock->owned_by_self() || 3904 SafepointSynchronize::is_at_safepoint(), 3905 "must grab Threads_lock or be at safepoint"); 3906 3907 // NULL owner means not locked so we can skip the search 3908 if (owner == NULL) return NULL; 3909 3910 { 3911 MutexLockerEx ml(doLock ? Threads_lock : NULL); 3912 ALL_JAVA_THREADS(p) { 3913 // first, see if owner is the address of a Java thread 3914 if (owner == (address)p) return p; 3915 } 3916 } 3917 assert(UseHeavyMonitors == false, "Did not find owning Java thread with UseHeavyMonitors enabled"); 3918 if (UseHeavyMonitors) return NULL; 3919 3920 // 3921 // If we didn't find a matching Java thread and we didn't force use of 3922 // heavyweight monitors, then the owner is the stack address of the 3923 // Lock Word in the owning Java thread's stack. 3924 // 3925 JavaThread* the_owner = NULL; 3926 { 3927 MutexLockerEx ml(doLock ? Threads_lock : NULL); 3928 ALL_JAVA_THREADS(q) { 3929 if (q->is_lock_owned(owner)) { 3930 the_owner = q; 3931 break; 3932 } 3933 } 3934 } 3935 assert(the_owner != NULL, "Did not find owning Java thread for lock word address"); 3936 return the_owner; 3937 } 3938 3939 // Threads::print_on() is called at safepoint by VM_PrintThreads operation. 3940 void Threads::print_on(outputStream* st, bool print_stacks, bool internal_format, bool print_concurrent_locks) { 3941 char buf[32]; 3942 st->print_cr(os::local_time_string(buf, sizeof(buf))); 3943 3944 st->print_cr("Full thread dump %s (%s %s):", 3945 Abstract_VM_Version::vm_name(), 3946 Abstract_VM_Version::vm_release(), 3947 Abstract_VM_Version::vm_info_string() 3948 ); 3949 st->cr(); 3950 3951 #ifndef SERIALGC 3952 // Dump concurrent locks 3953 ConcurrentLocksDump concurrent_locks; 3954 if (print_concurrent_locks) { 3955 concurrent_locks.dump_at_safepoint(); 3956 } 3957 #endif // SERIALGC 3958 3959 ALL_JAVA_THREADS(p) { 3960 ResourceMark rm; 3961 p->print_on(st); 3962 if (print_stacks) { 3963 if (internal_format) { 3964 p->trace_stack(); 3965 } else { 3966 p->print_stack_on(st); 3967 } 3968 } 3969 st->cr(); 3970 #ifndef SERIALGC 3971 if (print_concurrent_locks) { 3972 concurrent_locks.print_locks_on(p, st); 3973 } 3974 #endif // SERIALGC 3975 } 3976 3977 VMThread::vm_thread()->print_on(st); 3978 st->cr(); 3979 Universe::heap()->print_gc_threads_on(st); 3980 WatcherThread* wt = WatcherThread::watcher_thread(); 3981 if (wt != NULL) wt->print_on(st); 3982 st->cr(); 3983 CompileBroker::print_compiler_threads_on(st); 3984 st->flush(); 3985 } 3986 3987 // Threads::print_on_error() is called by fatal error handler. It's possible 3988 // that VM is not at safepoint and/or current thread is inside signal handler. 3989 // Don't print stack trace, as the stack may not be walkable. Don't allocate 3990 // memory (even in resource area), it might deadlock the error handler. 3991 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, int buflen) { 3992 bool found_current = false; 3993 st->print_cr("Java Threads: ( => current thread )"); 3994 ALL_JAVA_THREADS(thread) { 3995 bool is_current = (current == thread); 3996 found_current = found_current || is_current; 3997 3998 st->print("%s", is_current ? "=>" : " "); 3999 4000 st->print(PTR_FORMAT, thread); 4001 st->print(" "); 4002 thread->print_on_error(st, buf, buflen); 4003 st->cr(); 4004 } 4005 st->cr(); 4006 4007 st->print_cr("Other Threads:"); 4008 if (VMThread::vm_thread()) { 4009 bool is_current = (current == VMThread::vm_thread()); 4010 found_current = found_current || is_current; 4011 st->print("%s", current == VMThread::vm_thread() ? "=>" : " "); 4012 4013 st->print(PTR_FORMAT, VMThread::vm_thread()); 4014 st->print(" "); 4015 VMThread::vm_thread()->print_on_error(st, buf, buflen); 4016 st->cr(); 4017 } 4018 WatcherThread* wt = WatcherThread::watcher_thread(); 4019 if (wt != NULL) { 4020 bool is_current = (current == wt); 4021 found_current = found_current || is_current; 4022 st->print("%s", is_current ? "=>" : " "); 4023 4024 st->print(PTR_FORMAT, wt); 4025 st->print(" "); 4026 wt->print_on_error(st, buf, buflen); 4027 st->cr(); 4028 } 4029 if (!found_current) { 4030 st->cr(); 4031 st->print("=>" PTR_FORMAT " (exited) ", current); 4032 current->print_on_error(st, buf, buflen); 4033 st->cr(); 4034 } 4035 } 4036 4037 // Internal SpinLock and Mutex 4038 // Based on ParkEvent 4039 4040 // Ad-hoc mutual exclusion primitives: SpinLock and Mux 4041 // 4042 // We employ SpinLocks _only for low-contention, fixed-length 4043 // short-duration critical sections where we're concerned 4044 // about native mutex_t or HotSpot Mutex:: latency. 4045 // The mux construct provides a spin-then-block mutual exclusion 4046 // mechanism. 4047 // 4048 // Testing has shown that contention on the ListLock guarding gFreeList 4049 // is common. If we implement ListLock as a simple SpinLock it's common 4050 // for the JVM to devolve to yielding with little progress. This is true 4051 // despite the fact that the critical sections protected by ListLock are 4052 // extremely short. 4053 // 4054 // TODO-FIXME: ListLock should be of type SpinLock. 4055 // We should make this a 1st-class type, integrated into the lock 4056 // hierarchy as leaf-locks. Critically, the SpinLock structure 4057 // should have sufficient padding to avoid false-sharing and excessive 4058 // cache-coherency traffic. 4059 4060 4061 typedef volatile int SpinLockT ; 4062 4063 void Thread::SpinAcquire (volatile int * adr, const char * LockName) { 4064 if (Atomic::cmpxchg (1, adr, 0) == 0) { 4065 return ; // normal fast-path return 4066 } 4067 4068 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy. 4069 TEVENT (SpinAcquire - ctx) ; 4070 int ctr = 0 ; 4071 int Yields = 0 ; 4072 for (;;) { 4073 while (*adr != 0) { 4074 ++ctr ; 4075 if ((ctr & 0xFFF) == 0 || !os::is_MP()) { 4076 if (Yields > 5) { 4077 // Consider using a simple NakedSleep() instead. 4078 // Then SpinAcquire could be called by non-JVM threads 4079 Thread::current()->_ParkEvent->park(1) ; 4080 } else { 4081 os::NakedYield() ; 4082 ++Yields ; 4083 } 4084 } else { 4085 SpinPause() ; 4086 } 4087 } 4088 if (Atomic::cmpxchg (1, adr, 0) == 0) return ; 4089 } 4090 } 4091 4092 void Thread::SpinRelease (volatile int * adr) { 4093 assert (*adr != 0, "invariant") ; 4094 OrderAccess::fence() ; // guarantee at least release consistency. 4095 // Roach-motel semantics. 4096 // It's safe if subsequent LDs and STs float "up" into the critical section, 4097 // but prior LDs and STs within the critical section can't be allowed 4098 // to reorder or float past the ST that releases the lock. 4099 *adr = 0 ; 4100 } 4101 4102 // muxAcquire and muxRelease: 4103 // 4104 // * muxAcquire and muxRelease support a single-word lock-word construct. 4105 // The LSB of the word is set IFF the lock is held. 4106 // The remainder of the word points to the head of a singly-linked list 4107 // of threads blocked on the lock. 4108 // 4109 // * The current implementation of muxAcquire-muxRelease uses its own 4110 // dedicated Thread._MuxEvent instance. If we're interested in 4111 // minimizing the peak number of extant ParkEvent instances then 4112 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long 4113 // as certain invariants were satisfied. Specifically, care would need 4114 // to be taken with regards to consuming unpark() "permits". 4115 // A safe rule of thumb is that a thread would never call muxAcquire() 4116 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently 4117 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could 4118 // consume an unpark() permit intended for monitorenter, for instance. 4119 // One way around this would be to widen the restricted-range semaphore 4120 // implemented in park(). Another alternative would be to provide 4121 // multiple instances of the PlatformEvent() for each thread. One 4122 // instance would be dedicated to muxAcquire-muxRelease, for instance. 4123 // 4124 // * Usage: 4125 // -- Only as leaf locks 4126 // -- for short-term locking only as muxAcquire does not perform 4127 // thread state transitions. 4128 // 4129 // Alternatives: 4130 // * We could implement muxAcquire and muxRelease with MCS or CLH locks 4131 // but with parking or spin-then-park instead of pure spinning. 4132 // * Use Taura-Oyama-Yonenzawa locks. 4133 // * It's possible to construct a 1-0 lock if we encode the lockword as 4134 // (List,LockByte). Acquire will CAS the full lockword while Release 4135 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so 4136 // acquiring threads use timers (ParkTimed) to detect and recover from 4137 // the stranding window. Thread/Node structures must be aligned on 256-byte 4138 // boundaries by using placement-new. 4139 // * Augment MCS with advisory back-link fields maintained with CAS(). 4140 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner. 4141 // The validity of the backlinks must be ratified before we trust the value. 4142 // If the backlinks are invalid the exiting thread must back-track through the 4143 // the forward links, which are always trustworthy. 4144 // * Add a successor indication. The LockWord is currently encoded as 4145 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable 4146 // to provide the usual futile-wakeup optimization. 4147 // See RTStt for details. 4148 // * Consider schedctl.sc_nopreempt to cover the critical section. 4149 // 4150 4151 4152 typedef volatile intptr_t MutexT ; // Mux Lock-word 4153 enum MuxBits { LOCKBIT = 1 } ; 4154 4155 void Thread::muxAcquire (volatile intptr_t * Lock, const char * LockName) { 4156 intptr_t w = Atomic::cmpxchg_ptr (LOCKBIT, Lock, 0) ; 4157 if (w == 0) return ; 4158 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4159 return ; 4160 } 4161 4162 TEVENT (muxAcquire - Contention) ; 4163 ParkEvent * const Self = Thread::current()->_MuxEvent ; 4164 assert ((intptr_t(Self) & LOCKBIT) == 0, "invariant") ; 4165 for (;;) { 4166 int its = (os::is_MP() ? 100 : 0) + 1 ; 4167 4168 // Optional spin phase: spin-then-park strategy 4169 while (--its >= 0) { 4170 w = *Lock ; 4171 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4172 return ; 4173 } 4174 } 4175 4176 Self->reset() ; 4177 Self->OnList = intptr_t(Lock) ; 4178 // The following fence() isn't _strictly necessary as the subsequent 4179 // CAS() both serializes execution and ratifies the fetched *Lock value. 4180 OrderAccess::fence(); 4181 for (;;) { 4182 w = *Lock ; 4183 if ((w & LOCKBIT) == 0) { 4184 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4185 Self->OnList = 0 ; // hygiene - allows stronger asserts 4186 return ; 4187 } 4188 continue ; // Interference -- *Lock changed -- Just retry 4189 } 4190 assert (w & LOCKBIT, "invariant") ; 4191 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT ); 4192 if (Atomic::cmpxchg_ptr (intptr_t(Self)|LOCKBIT, Lock, w) == w) break ; 4193 } 4194 4195 while (Self->OnList != 0) { 4196 Self->park() ; 4197 } 4198 } 4199 } 4200 4201 void Thread::muxAcquireW (volatile intptr_t * Lock, ParkEvent * ev) { 4202 intptr_t w = Atomic::cmpxchg_ptr (LOCKBIT, Lock, 0) ; 4203 if (w == 0) return ; 4204 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4205 return ; 4206 } 4207 4208 TEVENT (muxAcquire - Contention) ; 4209 ParkEvent * ReleaseAfter = NULL ; 4210 if (ev == NULL) { 4211 ev = ReleaseAfter = ParkEvent::Allocate (NULL) ; 4212 } 4213 assert ((intptr_t(ev) & LOCKBIT) == 0, "invariant") ; 4214 for (;;) { 4215 guarantee (ev->OnList == 0, "invariant") ; 4216 int its = (os::is_MP() ? 100 : 0) + 1 ; 4217 4218 // Optional spin phase: spin-then-park strategy 4219 while (--its >= 0) { 4220 w = *Lock ; 4221 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4222 if (ReleaseAfter != NULL) { 4223 ParkEvent::Release (ReleaseAfter) ; 4224 } 4225 return ; 4226 } 4227 } 4228 4229 ev->reset() ; 4230 ev->OnList = intptr_t(Lock) ; 4231 // The following fence() isn't _strictly necessary as the subsequent 4232 // CAS() both serializes execution and ratifies the fetched *Lock value. 4233 OrderAccess::fence(); 4234 for (;;) { 4235 w = *Lock ; 4236 if ((w & LOCKBIT) == 0) { 4237 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4238 ev->OnList = 0 ; 4239 // We call ::Release while holding the outer lock, thus 4240 // artificially lengthening the critical section. 4241 // Consider deferring the ::Release() until the subsequent unlock(), 4242 // after we've dropped the outer lock. 4243 if (ReleaseAfter != NULL) { 4244 ParkEvent::Release (ReleaseAfter) ; 4245 } 4246 return ; 4247 } 4248 continue ; // Interference -- *Lock changed -- Just retry 4249 } 4250 assert (w & LOCKBIT, "invariant") ; 4251 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT ); 4252 if (Atomic::cmpxchg_ptr (intptr_t(ev)|LOCKBIT, Lock, w) == w) break ; 4253 } 4254 4255 while (ev->OnList != 0) { 4256 ev->park() ; 4257 } 4258 } 4259 } 4260 4261 // Release() must extract a successor from the list and then wake that thread. 4262 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme 4263 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based 4264 // Release() would : 4265 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list. 4266 // (B) Extract a successor from the private list "in-hand" 4267 // (C) attempt to CAS() the residual back into *Lock over null. 4268 // If there were any newly arrived threads and the CAS() would fail. 4269 // In that case Release() would detach the RATs, re-merge the list in-hand 4270 // with the RATs and repeat as needed. Alternately, Release() might 4271 // detach and extract a successor, but then pass the residual list to the wakee. 4272 // The wakee would be responsible for reattaching and remerging before it 4273 // competed for the lock. 4274 // 4275 // Both "pop" and DMR are immune from ABA corruption -- there can be 4276 // multiple concurrent pushers, but only one popper or detacher. 4277 // This implementation pops from the head of the list. This is unfair, 4278 // but tends to provide excellent throughput as hot threads remain hot. 4279 // (We wake recently run threads first). 4280 4281 void Thread::muxRelease (volatile intptr_t * Lock) { 4282 for (;;) { 4283 const intptr_t w = Atomic::cmpxchg_ptr (0, Lock, LOCKBIT) ; 4284 assert (w & LOCKBIT, "invariant") ; 4285 if (w == LOCKBIT) return ; 4286 ParkEvent * List = (ParkEvent *) (w & ~LOCKBIT) ; 4287 assert (List != NULL, "invariant") ; 4288 assert (List->OnList == intptr_t(Lock), "invariant") ; 4289 ParkEvent * nxt = List->ListNext ; 4290 4291 // The following CAS() releases the lock and pops the head element. 4292 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) { 4293 continue ; 4294 } 4295 List->OnList = 0 ; 4296 OrderAccess::fence() ; 4297 List->unpark () ; 4298 return ; 4299 } 4300 } 4301 4302 4303 void Threads::verify() { 4304 ALL_JAVA_THREADS(p) { 4305 p->verify(); 4306 } 4307 VMThread* thread = VMThread::vm_thread(); 4308 if (thread != NULL) thread->verify(); 4309 }