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 "interpreter/oopMapCache.hpp" 35 #include "jvmtifiles/jvmtiEnv.hpp" 36 #include "memory/oopFactory.hpp" 37 #include "memory/universe.inline.hpp" 38 #include "oops/instanceKlass.hpp" 39 #include "oops/objArrayOop.hpp" 40 #include "oops/oop.inline.hpp" 41 #include "oops/symbol.hpp" 42 #include "prims/jvm_misc.hpp" 43 #include "prims/jvmtiExport.hpp" 44 #include "prims/jvmtiThreadState.hpp" 45 #include "prims/privilegedStack.hpp" 46 #include "runtime/aprofiler.hpp" 47 #include "runtime/arguments.hpp" 48 #include "runtime/biasedLocking.hpp" 49 #include "runtime/deoptimization.hpp" 50 #include "runtime/fprofiler.hpp" 51 #include "runtime/frame.inline.hpp" 52 #include "runtime/init.hpp" 53 #include "runtime/interfaceSupport.hpp" 54 #include "runtime/java.hpp" 55 #include "runtime/javaCalls.hpp" 56 #include "runtime/jniPeriodicChecker.hpp" 57 #include "runtime/memprofiler.hpp" 58 #include "runtime/mutexLocker.hpp" 59 #include "runtime/objectMonitor.hpp" 60 #include "runtime/osThread.hpp" 61 #include "runtime/safepoint.hpp" 62 #include "runtime/sharedRuntime.hpp" 63 #include "runtime/statSampler.hpp" 64 #include "runtime/stubRoutines.hpp" 65 #include "runtime/task.hpp" 66 #include "runtime/threadCritical.hpp" 67 #include "runtime/threadLocalStorage.hpp" 68 #include "runtime/vframe.hpp" 69 #include "runtime/vframeArray.hpp" 70 #include "runtime/vframe_hp.hpp" 71 #include "runtime/vmThread.hpp" 72 #include "runtime/vm_operations.hpp" 73 #include "services/attachListener.hpp" 74 #include "services/management.hpp" 75 #include "services/threadService.hpp" 76 #include "utilities/defaultStream.hpp" 77 #include "utilities/dtrace.hpp" 78 #include "utilities/events.hpp" 79 #include "utilities/preserveException.hpp" 80 #ifdef TARGET_OS_FAMILY_linux 81 # include "os_linux.inline.hpp" 82 # include "thread_linux.inline.hpp" 83 #endif 84 #ifdef TARGET_OS_FAMILY_solaris 85 # include "os_solaris.inline.hpp" 86 # include "thread_solaris.inline.hpp" 87 #endif 88 #ifdef TARGET_OS_FAMILY_windows 89 # include "os_windows.inline.hpp" 90 # include "thread_windows.inline.hpp" 91 #endif 92 #ifndef SERIALGC 93 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp" 94 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp" 95 #include "gc_implementation/parallelScavenge/pcTasks.hpp" 96 #endif 97 #ifdef COMPILER1 98 #include "c1/c1_Compiler.hpp" 99 #endif 100 #ifdef COMPILER2 101 #include "opto/c2compiler.hpp" 102 #include "opto/idealGraphPrinter.hpp" 103 #endif 104 105 #ifdef DTRACE_ENABLED 106 107 // Only bother with this argument setup if dtrace is available 108 109 HS_DTRACE_PROBE_DECL(hotspot, vm__init__begin); 110 HS_DTRACE_PROBE_DECL(hotspot, vm__init__end); 111 HS_DTRACE_PROBE_DECL5(hotspot, thread__start, char*, intptr_t, 112 intptr_t, intptr_t, bool); 113 HS_DTRACE_PROBE_DECL5(hotspot, thread__stop, char*, intptr_t, 114 intptr_t, intptr_t, bool); 115 116 #define DTRACE_THREAD_PROBE(probe, javathread) \ 117 { \ 118 ResourceMark rm(this); \ 119 int len = 0; \ 120 const char* name = (javathread)->get_thread_name(); \ 121 len = strlen(name); \ 122 HS_DTRACE_PROBE5(hotspot, thread__##probe, \ 123 name, len, \ 124 java_lang_Thread::thread_id((javathread)->threadObj()), \ 125 (javathread)->osthread()->thread_id(), \ 126 java_lang_Thread::is_daemon((javathread)->threadObj())); \ 127 } 128 129 #else // ndef DTRACE_ENABLED 130 131 #define DTRACE_THREAD_PROBE(probe, javathread) 132 133 #endif // ndef DTRACE_ENABLED 134 135 // Class hierarchy 136 // - Thread 137 // - VMThread 138 // - WatcherThread 139 // - ConcurrentMarkSweepThread 140 // - JavaThread 141 // - CompilerThread 142 143 // ======= Thread ======== 144 145 // Support for forcing alignment of thread objects for biased locking 146 void* Thread::operator new(size_t size) { 147 if (UseBiasedLocking) { 148 const int alignment = markOopDesc::biased_lock_alignment; 149 size_t aligned_size = size + (alignment - sizeof(intptr_t)); 150 void* real_malloc_addr = CHeapObj::operator new(aligned_size); 151 void* aligned_addr = (void*) align_size_up((intptr_t) real_malloc_addr, alignment); 152 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <= 153 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size), 154 "JavaThread alignment code overflowed allocated storage"); 155 if (TraceBiasedLocking) { 156 if (aligned_addr != real_malloc_addr) 157 tty->print_cr("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT, 158 real_malloc_addr, aligned_addr); 159 } 160 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr; 161 return aligned_addr; 162 } else { 163 return CHeapObj::operator new(size); 164 } 165 } 166 167 void Thread::operator delete(void* p) { 168 if (UseBiasedLocking) { 169 void* real_malloc_addr = ((Thread*) p)->_real_malloc_address; 170 CHeapObj::operator delete(real_malloc_addr); 171 } else { 172 CHeapObj::operator delete(p); 173 } 174 } 175 176 177 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread, 178 // JavaThread 179 180 181 Thread::Thread() { 182 // stack and get_thread 183 set_stack_base(NULL); 184 set_stack_size(0); 185 set_self_raw_id(0); 186 set_lgrp_id(-1); 187 188 // allocated data structures 189 set_osthread(NULL); 190 set_resource_area(new ResourceArea()); 191 set_handle_area(new HandleArea(NULL)); 192 set_active_handles(NULL); 193 set_free_handle_block(NULL); 194 set_last_handle_mark(NULL); 195 196 // This initial value ==> never claimed. 197 _oops_do_parity = 0; 198 199 // the handle mark links itself to last_handle_mark 200 new HandleMark(this); 201 202 // plain initialization 203 debug_only(_owned_locks = NULL;) 204 debug_only(_allow_allocation_count = 0;) 205 NOT_PRODUCT(_allow_safepoint_count = 0;) 206 NOT_PRODUCT(_skip_gcalot = false;) 207 CHECK_UNHANDLED_OOPS_ONLY(_gc_locked_out_count = 0;) 208 _jvmti_env_iteration_count = 0; 209 set_allocated_bytes(0); 210 _vm_operation_started_count = 0; 211 _vm_operation_completed_count = 0; 212 _current_pending_monitor = NULL; 213 _current_pending_monitor_is_from_java = true; 214 _current_waiting_monitor = NULL; 215 _num_nested_signal = 0; 216 omFreeList = NULL ; 217 omFreeCount = 0 ; 218 omFreeProvision = 32 ; 219 omInUseList = NULL ; 220 omInUseCount = 0 ; 221 222 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true); 223 _suspend_flags = 0; 224 225 // thread-specific hashCode stream generator state - Marsaglia shift-xor form 226 _hashStateX = os::random() ; 227 _hashStateY = 842502087 ; 228 _hashStateZ = 0x8767 ; // (int)(3579807591LL & 0xffff) ; 229 _hashStateW = 273326509 ; 230 231 _OnTrap = 0 ; 232 _schedctl = NULL ; 233 _Stalled = 0 ; 234 _TypeTag = 0x2BAD ; 235 236 // Many of the following fields are effectively final - immutable 237 // Note that nascent threads can't use the Native Monitor-Mutex 238 // construct until the _MutexEvent is initialized ... 239 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents 240 // we might instead use a stack of ParkEvents that we could provision on-demand. 241 // The stack would act as a cache to avoid calls to ParkEvent::Allocate() 242 // and ::Release() 243 _ParkEvent = ParkEvent::Allocate (this) ; 244 _SleepEvent = ParkEvent::Allocate (this) ; 245 _MutexEvent = ParkEvent::Allocate (this) ; 246 _MuxEvent = ParkEvent::Allocate (this) ; 247 248 #ifdef CHECK_UNHANDLED_OOPS 249 if (CheckUnhandledOops) { 250 _unhandled_oops = new UnhandledOops(this); 251 } 252 #endif // CHECK_UNHANDLED_OOPS 253 #ifdef ASSERT 254 if (UseBiasedLocking) { 255 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed"); 256 assert(this == _real_malloc_address || 257 this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment), 258 "bug in forced alignment of thread objects"); 259 } 260 #endif /* ASSERT */ 261 } 262 263 void Thread::initialize_thread_local_storage() { 264 // Note: Make sure this method only calls 265 // non-blocking operations. Otherwise, it might not work 266 // with the thread-startup/safepoint interaction. 267 268 // During Java thread startup, safepoint code should allow this 269 // method to complete because it may need to allocate memory to 270 // store information for the new thread. 271 272 // initialize structure dependent on thread local storage 273 ThreadLocalStorage::set_thread(this); 274 275 // set up any platform-specific state. 276 os::initialize_thread(); 277 278 } 279 280 void Thread::record_stack_base_and_size() { 281 set_stack_base(os::current_stack_base()); 282 set_stack_size(os::current_stack_size()); 283 } 284 285 286 Thread::~Thread() { 287 // Reclaim the objectmonitors from the omFreeList of the moribund thread. 288 ObjectSynchronizer::omFlush (this) ; 289 290 // deallocate data structures 291 delete resource_area(); 292 // since the handle marks are using the handle area, we have to deallocated the root 293 // handle mark before deallocating the thread's handle area, 294 assert(last_handle_mark() != NULL, "check we have an element"); 295 delete last_handle_mark(); 296 assert(last_handle_mark() == NULL, "check we have reached the end"); 297 298 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads. 299 // We NULL out the fields for good hygiene. 300 ParkEvent::Release (_ParkEvent) ; _ParkEvent = NULL ; 301 ParkEvent::Release (_SleepEvent) ; _SleepEvent = NULL ; 302 ParkEvent::Release (_MutexEvent) ; _MutexEvent = NULL ; 303 ParkEvent::Release (_MuxEvent) ; _MuxEvent = NULL ; 304 305 delete handle_area(); 306 307 // osthread() can be NULL, if creation of thread failed. 308 if (osthread() != NULL) os::free_thread(osthread()); 309 310 delete _SR_lock; 311 312 // clear thread local storage if the Thread is deleting itself 313 if (this == Thread::current()) { 314 ThreadLocalStorage::set_thread(NULL); 315 } else { 316 // In the case where we're not the current thread, invalidate all the 317 // caches in case some code tries to get the current thread or the 318 // thread that was destroyed, and gets stale information. 319 ThreadLocalStorage::invalidate_all(); 320 } 321 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();) 322 } 323 324 // NOTE: dummy function for assertion purpose. 325 void Thread::run() { 326 ShouldNotReachHere(); 327 } 328 329 #ifdef ASSERT 330 // Private method to check for dangling thread pointer 331 void check_for_dangling_thread_pointer(Thread *thread) { 332 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(), 333 "possibility of dangling Thread pointer"); 334 } 335 #endif 336 337 338 #ifndef PRODUCT 339 // Tracing method for basic thread operations 340 void Thread::trace(const char* msg, const Thread* const thread) { 341 if (!TraceThreadEvents) return; 342 ResourceMark rm; 343 ThreadCritical tc; 344 const char *name = "non-Java thread"; 345 int prio = -1; 346 if (thread->is_Java_thread() 347 && !thread->is_Compiler_thread()) { 348 // The Threads_lock must be held to get information about 349 // this thread but may not be in some situations when 350 // tracing thread events. 351 bool release_Threads_lock = false; 352 if (!Threads_lock->owned_by_self()) { 353 Threads_lock->lock(); 354 release_Threads_lock = true; 355 } 356 JavaThread* jt = (JavaThread *)thread; 357 name = (char *)jt->get_thread_name(); 358 oop thread_oop = jt->threadObj(); 359 if (thread_oop != NULL) { 360 prio = java_lang_Thread::priority(thread_oop); 361 } 362 if (release_Threads_lock) { 363 Threads_lock->unlock(); 364 } 365 } 366 tty->print_cr("Thread::%s " INTPTR_FORMAT " [%lx] %s (prio: %d)", msg, thread, thread->osthread()->thread_id(), name, prio); 367 } 368 #endif 369 370 371 ThreadPriority Thread::get_priority(const Thread* const thread) { 372 trace("get priority", thread); 373 ThreadPriority priority; 374 // Can return an error! 375 (void)os::get_priority(thread, priority); 376 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found"); 377 return priority; 378 } 379 380 void Thread::set_priority(Thread* thread, ThreadPriority priority) { 381 trace("set priority", thread); 382 debug_only(check_for_dangling_thread_pointer(thread);) 383 // Can return an error! 384 (void)os::set_priority(thread, priority); 385 } 386 387 388 void Thread::start(Thread* thread) { 389 trace("start", thread); 390 // Start is different from resume in that its safety is guaranteed by context or 391 // being called from a Java method synchronized on the Thread object. 392 if (!DisableStartThread) { 393 if (thread->is_Java_thread()) { 394 // Initialize the thread state to RUNNABLE before starting this thread. 395 // Can not set it after the thread started because we do not know the 396 // exact thread state at that time. It could be in MONITOR_WAIT or 397 // in SLEEPING or some other state. 398 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(), 399 java_lang_Thread::RUNNABLE); 400 } 401 os::start_thread(thread); 402 } 403 } 404 405 // Enqueue a VM_Operation to do the job for us - sometime later 406 void Thread::send_async_exception(oop java_thread, oop java_throwable) { 407 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable); 408 VMThread::execute(vm_stop); 409 } 410 411 412 // 413 // Check if an external suspend request has completed (or has been 414 // cancelled). Returns true if the thread is externally suspended and 415 // false otherwise. 416 // 417 // The bits parameter returns information about the code path through 418 // the routine. Useful for debugging: 419 // 420 // set in is_ext_suspend_completed(): 421 // 0x00000001 - routine was entered 422 // 0x00000010 - routine return false at end 423 // 0x00000100 - thread exited (return false) 424 // 0x00000200 - suspend request cancelled (return false) 425 // 0x00000400 - thread suspended (return true) 426 // 0x00001000 - thread is in a suspend equivalent state (return true) 427 // 0x00002000 - thread is native and walkable (return true) 428 // 0x00004000 - thread is native_trans and walkable (needed retry) 429 // 430 // set in wait_for_ext_suspend_completion(): 431 // 0x00010000 - routine was entered 432 // 0x00020000 - suspend request cancelled before loop (return false) 433 // 0x00040000 - thread suspended before loop (return true) 434 // 0x00080000 - suspend request cancelled in loop (return false) 435 // 0x00100000 - thread suspended in loop (return true) 436 // 0x00200000 - suspend not completed during retry loop (return false) 437 // 438 439 // Helper class for tracing suspend wait debug bits. 440 // 441 // 0x00000100 indicates that the target thread exited before it could 442 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and 443 // 0x00080000 each indicate a cancelled suspend request so they don't 444 // count as wait failures either. 445 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000) 446 447 class TraceSuspendDebugBits : public StackObj { 448 private: 449 JavaThread * jt; 450 bool is_wait; 451 bool called_by_wait; // meaningful when !is_wait 452 uint32_t * bits; 453 454 public: 455 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait, 456 uint32_t *_bits) { 457 jt = _jt; 458 is_wait = _is_wait; 459 called_by_wait = _called_by_wait; 460 bits = _bits; 461 } 462 463 ~TraceSuspendDebugBits() { 464 if (!is_wait) { 465 #if 1 466 // By default, don't trace bits for is_ext_suspend_completed() calls. 467 // That trace is very chatty. 468 return; 469 #else 470 if (!called_by_wait) { 471 // If tracing for is_ext_suspend_completed() is enabled, then only 472 // trace calls to it from wait_for_ext_suspend_completion() 473 return; 474 } 475 #endif 476 } 477 478 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) { 479 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) { 480 MutexLocker ml(Threads_lock); // needed for get_thread_name() 481 ResourceMark rm; 482 483 tty->print_cr( 484 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)", 485 jt->get_thread_name(), *bits); 486 487 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed"); 488 } 489 } 490 } 491 }; 492 #undef DEBUG_FALSE_BITS 493 494 495 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, uint32_t *bits) { 496 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits); 497 498 bool did_trans_retry = false; // only do thread_in_native_trans retry once 499 bool do_trans_retry; // flag to force the retry 500 501 *bits |= 0x00000001; 502 503 do { 504 do_trans_retry = false; 505 506 if (is_exiting()) { 507 // Thread is in the process of exiting. This is always checked 508 // first to reduce the risk of dereferencing a freed JavaThread. 509 *bits |= 0x00000100; 510 return false; 511 } 512 513 if (!is_external_suspend()) { 514 // Suspend request is cancelled. This is always checked before 515 // is_ext_suspended() to reduce the risk of a rogue resume 516 // confusing the thread that made the suspend request. 517 *bits |= 0x00000200; 518 return false; 519 } 520 521 if (is_ext_suspended()) { 522 // thread is suspended 523 *bits |= 0x00000400; 524 return true; 525 } 526 527 // Now that we no longer do hard suspends of threads running 528 // native code, the target thread can be changing thread state 529 // while we are in this routine: 530 // 531 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked 532 // 533 // We save a copy of the thread state as observed at this moment 534 // and make our decision about suspend completeness based on the 535 // copy. This closes the race where the thread state is seen as 536 // _thread_in_native_trans in the if-thread_blocked check, but is 537 // seen as _thread_blocked in if-thread_in_native_trans check. 538 JavaThreadState save_state = thread_state(); 539 540 if (save_state == _thread_blocked && is_suspend_equivalent()) { 541 // If the thread's state is _thread_blocked and this blocking 542 // condition is known to be equivalent to a suspend, then we can 543 // consider the thread to be externally suspended. This means that 544 // the code that sets _thread_blocked has been modified to do 545 // self-suspension if the blocking condition releases. We also 546 // used to check for CONDVAR_WAIT here, but that is now covered by 547 // the _thread_blocked with self-suspension check. 548 // 549 // Return true since we wouldn't be here unless there was still an 550 // external suspend request. 551 *bits |= 0x00001000; 552 return true; 553 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) { 554 // Threads running native code will self-suspend on native==>VM/Java 555 // transitions. If its stack is walkable (should always be the case 556 // unless this function is called before the actual java_suspend() 557 // call), then the wait is done. 558 *bits |= 0x00002000; 559 return true; 560 } else if (!called_by_wait && !did_trans_retry && 561 save_state == _thread_in_native_trans && 562 frame_anchor()->walkable()) { 563 // The thread is transitioning from thread_in_native to another 564 // thread state. check_safepoint_and_suspend_for_native_trans() 565 // will force the thread to self-suspend. If it hasn't gotten 566 // there yet we may have caught the thread in-between the native 567 // code check above and the self-suspend. Lucky us. If we were 568 // called by wait_for_ext_suspend_completion(), then it 569 // will be doing the retries so we don't have to. 570 // 571 // Since we use the saved thread state in the if-statement above, 572 // there is a chance that the thread has already transitioned to 573 // _thread_blocked by the time we get here. In that case, we will 574 // make a single unnecessary pass through the logic below. This 575 // doesn't hurt anything since we still do the trans retry. 576 577 *bits |= 0x00004000; 578 579 // Once the thread leaves thread_in_native_trans for another 580 // thread state, we break out of this retry loop. We shouldn't 581 // need this flag to prevent us from getting back here, but 582 // sometimes paranoia is good. 583 did_trans_retry = true; 584 585 // We wait for the thread to transition to a more usable state. 586 for (int i = 1; i <= SuspendRetryCount; i++) { 587 // We used to do an "os::yield_all(i)" call here with the intention 588 // that yielding would increase on each retry. However, the parameter 589 // is ignored on Linux which means the yield didn't scale up. Waiting 590 // on the SR_lock below provides a much more predictable scale up for 591 // the delay. It also provides a simple/direct point to check for any 592 // safepoint requests from the VMThread 593 594 // temporarily drops SR_lock while doing wait with safepoint check 595 // (if we're a JavaThread - the WatcherThread can also call this) 596 // and increase delay with each retry 597 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 598 599 // check the actual thread state instead of what we saved above 600 if (thread_state() != _thread_in_native_trans) { 601 // the thread has transitioned to another thread state so 602 // try all the checks (except this one) one more time. 603 do_trans_retry = true; 604 break; 605 } 606 } // end retry loop 607 608 609 } 610 } while (do_trans_retry); 611 612 *bits |= 0x00000010; 613 return false; 614 } 615 616 // 617 // Wait for an external suspend request to complete (or be cancelled). 618 // Returns true if the thread is externally suspended and false otherwise. 619 // 620 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay, 621 uint32_t *bits) { 622 TraceSuspendDebugBits tsdb(this, true /* is_wait */, 623 false /* !called_by_wait */, bits); 624 625 // local flag copies to minimize SR_lock hold time 626 bool is_suspended; 627 bool pending; 628 uint32_t reset_bits; 629 630 // set a marker so is_ext_suspend_completed() knows we are the caller 631 *bits |= 0x00010000; 632 633 // We use reset_bits to reinitialize the bits value at the top of 634 // each retry loop. This allows the caller to make use of any 635 // unused bits for their own marking purposes. 636 reset_bits = *bits; 637 638 { 639 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 640 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 641 delay, bits); 642 pending = is_external_suspend(); 643 } 644 // must release SR_lock to allow suspension to complete 645 646 if (!pending) { 647 // A cancelled suspend request is the only false return from 648 // is_ext_suspend_completed() that keeps us from entering the 649 // retry loop. 650 *bits |= 0x00020000; 651 return false; 652 } 653 654 if (is_suspended) { 655 *bits |= 0x00040000; 656 return true; 657 } 658 659 for (int i = 1; i <= retries; i++) { 660 *bits = reset_bits; // reinit to only track last retry 661 662 // We used to do an "os::yield_all(i)" call here with the intention 663 // that yielding would increase on each retry. However, the parameter 664 // is ignored on Linux which means the yield didn't scale up. Waiting 665 // on the SR_lock below provides a much more predictable scale up for 666 // the delay. It also provides a simple/direct point to check for any 667 // safepoint requests from the VMThread 668 669 { 670 MutexLocker ml(SR_lock()); 671 // wait with safepoint check (if we're a JavaThread - the WatcherThread 672 // can also call this) and increase delay with each retry 673 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 674 675 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 676 delay, bits); 677 678 // It is possible for the external suspend request to be cancelled 679 // (by a resume) before the actual suspend operation is completed. 680 // Refresh our local copy to see if we still need to wait. 681 pending = is_external_suspend(); 682 } 683 684 if (!pending) { 685 // A cancelled suspend request is the only false return from 686 // is_ext_suspend_completed() that keeps us from staying in the 687 // retry loop. 688 *bits |= 0x00080000; 689 return false; 690 } 691 692 if (is_suspended) { 693 *bits |= 0x00100000; 694 return true; 695 } 696 } // end retry loop 697 698 // thread did not suspend after all our retries 699 *bits |= 0x00200000; 700 return false; 701 } 702 703 #ifndef PRODUCT 704 void JavaThread::record_jump(address target, address instr, const char* file, int line) { 705 706 // This should not need to be atomic as the only way for simultaneous 707 // updates is via interrupts. Even then this should be rare or non-existant 708 // and we don't care that much anyway. 709 710 int index = _jmp_ring_index; 711 _jmp_ring_index = (index + 1 ) & (jump_ring_buffer_size - 1); 712 _jmp_ring[index]._target = (intptr_t) target; 713 _jmp_ring[index]._instruction = (intptr_t) instr; 714 _jmp_ring[index]._file = file; 715 _jmp_ring[index]._line = line; 716 } 717 #endif /* PRODUCT */ 718 719 // Called by flat profiler 720 // Callers have already called wait_for_ext_suspend_completion 721 // The assertion for that is currently too complex to put here: 722 bool JavaThread::profile_last_Java_frame(frame* _fr) { 723 bool gotframe = false; 724 // self suspension saves needed state. 725 if (has_last_Java_frame() && _anchor.walkable()) { 726 *_fr = pd_last_frame(); 727 gotframe = true; 728 } 729 return gotframe; 730 } 731 732 void Thread::interrupt(Thread* thread) { 733 trace("interrupt", thread); 734 debug_only(check_for_dangling_thread_pointer(thread);) 735 os::interrupt(thread); 736 } 737 738 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) { 739 trace("is_interrupted", thread); 740 debug_only(check_for_dangling_thread_pointer(thread);) 741 // Note: If clear_interrupted==false, this simply fetches and 742 // returns the value of the field osthread()->interrupted(). 743 return os::is_interrupted(thread, clear_interrupted); 744 } 745 746 747 // GC Support 748 bool Thread::claim_oops_do_par_case(int strong_roots_parity) { 749 jint thread_parity = _oops_do_parity; 750 if (thread_parity != strong_roots_parity) { 751 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity); 752 if (res == thread_parity) { 753 return true; 754 } else { 755 guarantee(res == strong_roots_parity, "Or else what?"); 756 assert(SharedHeap::heap()->n_par_threads() > 0, 757 "Should only fail when parallel."); 758 return false; 759 } 760 } 761 assert(SharedHeap::heap()->n_par_threads() > 0, 762 "Should only fail when parallel."); 763 return false; 764 } 765 766 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 767 active_handles()->oops_do(f); 768 // Do oop for ThreadShadow 769 f->do_oop((oop*)&_pending_exception); 770 handle_area()->oops_do(f); 771 } 772 773 void Thread::nmethods_do(CodeBlobClosure* cf) { 774 // no nmethods in a generic thread... 775 } 776 777 void Thread::print_on(outputStream* st) const { 778 // get_priority assumes osthread initialized 779 if (osthread() != NULL) { 780 st->print("prio=%d tid=" INTPTR_FORMAT " ", get_priority(this), this); 781 osthread()->print_on(st); 782 } 783 debug_only(if (WizardMode) print_owned_locks_on(st);) 784 } 785 786 // Thread::print_on_error() is called by fatal error handler. Don't use 787 // any lock or allocate memory. 788 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const { 789 if (is_VM_thread()) st->print("VMThread"); 790 else if (is_Compiler_thread()) st->print("CompilerThread"); 791 else if (is_Java_thread()) st->print("JavaThread"); 792 else if (is_GC_task_thread()) st->print("GCTaskThread"); 793 else if (is_Watcher_thread()) st->print("WatcherThread"); 794 else if (is_ConcurrentGC_thread()) st->print("ConcurrentGCThread"); 795 else st->print("Thread"); 796 797 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]", 798 _stack_base - _stack_size, _stack_base); 799 800 if (osthread()) { 801 st->print(" [id=%d]", osthread()->thread_id()); 802 } 803 } 804 805 #ifdef ASSERT 806 void Thread::print_owned_locks_on(outputStream* st) const { 807 Monitor *cur = _owned_locks; 808 if (cur == NULL) { 809 st->print(" (no locks) "); 810 } else { 811 st->print_cr(" Locks owned:"); 812 while(cur) { 813 cur->print_on(st); 814 cur = cur->next(); 815 } 816 } 817 } 818 819 static int ref_use_count = 0; 820 821 bool Thread::owns_locks_but_compiled_lock() const { 822 for(Monitor *cur = _owned_locks; cur; cur = cur->next()) { 823 if (cur != Compile_lock) return true; 824 } 825 return false; 826 } 827 828 829 #endif 830 831 #ifndef PRODUCT 832 833 // The flag: potential_vm_operation notifies if this particular safepoint state could potential 834 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that 835 // no threads which allow_vm_block's are held 836 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) { 837 // Check if current thread is allowed to block at a safepoint 838 if (!(_allow_safepoint_count == 0)) 839 fatal("Possible safepoint reached by thread that does not allow it"); 840 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) { 841 fatal("LEAF method calling lock?"); 842 } 843 844 #ifdef ASSERT 845 if (potential_vm_operation && is_Java_thread() 846 && !Universe::is_bootstrapping()) { 847 // Make sure we do not hold any locks that the VM thread also uses. 848 // This could potentially lead to deadlocks 849 for(Monitor *cur = _owned_locks; cur; cur = cur->next()) { 850 // Threads_lock is special, since the safepoint synchronization will not start before this is 851 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock, 852 // since it is used to transfer control between JavaThreads and the VMThread 853 // Do not *exclude* any locks unless you are absolutly sure it is correct. Ask someone else first! 854 if ( (cur->allow_vm_block() && 855 cur != Threads_lock && 856 cur != Compile_lock && // Temporary: should not be necessary when we get spearate compilation 857 cur != VMOperationRequest_lock && 858 cur != VMOperationQueue_lock) || 859 cur->rank() == Mutex::special) { 860 warning("Thread holding lock at safepoint that vm can block on: %s", cur->name()); 861 } 862 } 863 } 864 865 if (GCALotAtAllSafepoints) { 866 // We could enter a safepoint here and thus have a gc 867 InterfaceSupport::check_gc_alot(); 868 } 869 #endif 870 } 871 #endif 872 873 bool Thread::is_in_stack(address adr) const { 874 assert(Thread::current() == this, "is_in_stack can only be called from current thread"); 875 address end = os::current_stack_pointer(); 876 if (stack_base() >= adr && adr >= end) return true; 877 878 return false; 879 } 880 881 882 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter 883 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being 884 // used for compilation in the future. If that change is made, the need for these methods 885 // should be revisited, and they should be removed if possible. 886 887 bool Thread::is_lock_owned(address adr) const { 888 return on_local_stack(adr); 889 } 890 891 bool Thread::set_as_starting_thread() { 892 // NOTE: this must be called inside the main thread. 893 return os::create_main_thread((JavaThread*)this); 894 } 895 896 static void initialize_class(Symbol* class_name, TRAPS) { 897 klassOop klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK); 898 instanceKlass::cast(klass)->initialize(CHECK); 899 } 900 901 902 // Creates the initial ThreadGroup 903 static Handle create_initial_thread_group(TRAPS) { 904 klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH); 905 instanceKlassHandle klass (THREAD, k); 906 907 Handle system_instance = klass->allocate_instance_handle(CHECK_NH); 908 { 909 JavaValue result(T_VOID); 910 JavaCalls::call_special(&result, 911 system_instance, 912 klass, 913 vmSymbols::object_initializer_name(), 914 vmSymbols::void_method_signature(), 915 CHECK_NH); 916 } 917 Universe::set_system_thread_group(system_instance()); 918 919 Handle main_instance = klass->allocate_instance_handle(CHECK_NH); 920 { 921 JavaValue result(T_VOID); 922 Handle string = java_lang_String::create_from_str("main", CHECK_NH); 923 JavaCalls::call_special(&result, 924 main_instance, 925 klass, 926 vmSymbols::object_initializer_name(), 927 vmSymbols::threadgroup_string_void_signature(), 928 system_instance, 929 string, 930 CHECK_NH); 931 } 932 return main_instance; 933 } 934 935 // Creates the initial Thread 936 static oop create_initial_thread(Handle thread_group, JavaThread* thread, TRAPS) { 937 klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL); 938 instanceKlassHandle klass (THREAD, k); 939 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL); 940 941 java_lang_Thread::set_thread(thread_oop(), thread); 942 java_lang_Thread::set_priority(thread_oop(), NormPriority); 943 thread->set_threadObj(thread_oop()); 944 945 Handle string = java_lang_String::create_from_str("main", CHECK_NULL); 946 947 JavaValue result(T_VOID); 948 JavaCalls::call_special(&result, thread_oop, 949 klass, 950 vmSymbols::object_initializer_name(), 951 vmSymbols::threadgroup_string_void_signature(), 952 thread_group, 953 string, 954 CHECK_NULL); 955 return thread_oop(); 956 } 957 958 static void call_initializeSystemClass(TRAPS) { 959 klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 960 instanceKlassHandle klass (THREAD, k); 961 962 JavaValue result(T_VOID); 963 JavaCalls::call_static(&result, klass, vmSymbols::initializeSystemClass_name(), 964 vmSymbols::void_method_signature(), CHECK); 965 } 966 967 // General purpose hook into Java code, run once when the VM is initialized. 968 // The Java library method itself may be changed independently from the VM. 969 static void call_postVMInitHook(TRAPS) { 970 klassOop k = SystemDictionary::sun_misc_PostVMInitHook_klass(); 971 instanceKlassHandle klass (THREAD, k); 972 if (klass.not_null()) { 973 JavaValue result(T_VOID); 974 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(), 975 vmSymbols::void_method_signature(), 976 CHECK); 977 } 978 } 979 980 static void reset_vm_info_property(TRAPS) { 981 // the vm info string 982 ResourceMark rm(THREAD); 983 const char *vm_info = VM_Version::vm_info_string(); 984 985 // java.lang.System class 986 klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 987 instanceKlassHandle klass (THREAD, k); 988 989 // setProperty arguments 990 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK); 991 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK); 992 993 // return value 994 JavaValue r(T_OBJECT); 995 996 // public static String setProperty(String key, String value); 997 JavaCalls::call_static(&r, 998 klass, 999 vmSymbols::setProperty_name(), 1000 vmSymbols::string_string_string_signature(), 1001 key_str, 1002 value_str, 1003 CHECK); 1004 } 1005 1006 1007 void JavaThread::allocate_threadObj(Handle thread_group, char* thread_name, bool daemon, TRAPS) { 1008 assert(thread_group.not_null(), "thread group should be specified"); 1009 assert(threadObj() == NULL, "should only create Java thread object once"); 1010 1011 klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK); 1012 instanceKlassHandle klass (THREAD, k); 1013 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK); 1014 1015 java_lang_Thread::set_thread(thread_oop(), this); 1016 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1017 set_threadObj(thread_oop()); 1018 1019 JavaValue result(T_VOID); 1020 if (thread_name != NULL) { 1021 Handle name = java_lang_String::create_from_str(thread_name, CHECK); 1022 // Thread gets assigned specified name and null target 1023 JavaCalls::call_special(&result, 1024 thread_oop, 1025 klass, 1026 vmSymbols::object_initializer_name(), 1027 vmSymbols::threadgroup_string_void_signature(), 1028 thread_group, // Argument 1 1029 name, // Argument 2 1030 THREAD); 1031 } else { 1032 // Thread gets assigned name "Thread-nnn" and null target 1033 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument) 1034 JavaCalls::call_special(&result, 1035 thread_oop, 1036 klass, 1037 vmSymbols::object_initializer_name(), 1038 vmSymbols::threadgroup_runnable_void_signature(), 1039 thread_group, // Argument 1 1040 Handle(), // Argument 2 1041 THREAD); 1042 } 1043 1044 1045 if (daemon) { 1046 java_lang_Thread::set_daemon(thread_oop()); 1047 } 1048 1049 if (HAS_PENDING_EXCEPTION) { 1050 return; 1051 } 1052 1053 KlassHandle group(this, SystemDictionary::ThreadGroup_klass()); 1054 Handle threadObj(this, this->threadObj()); 1055 1056 JavaCalls::call_special(&result, 1057 thread_group, 1058 group, 1059 vmSymbols::add_method_name(), 1060 vmSymbols::thread_void_signature(), 1061 threadObj, // Arg 1 1062 THREAD); 1063 1064 1065 } 1066 1067 // NamedThread -- non-JavaThread subclasses with multiple 1068 // uniquely named instances should derive from this. 1069 NamedThread::NamedThread() : Thread() { 1070 _name = NULL; 1071 _processed_thread = NULL; 1072 } 1073 1074 NamedThread::~NamedThread() { 1075 if (_name != NULL) { 1076 FREE_C_HEAP_ARRAY(char, _name); 1077 _name = NULL; 1078 } 1079 } 1080 1081 void NamedThread::set_name(const char* format, ...) { 1082 guarantee(_name == NULL, "Only get to set name once."); 1083 _name = NEW_C_HEAP_ARRAY(char, max_name_len); 1084 guarantee(_name != NULL, "alloc failure"); 1085 va_list ap; 1086 va_start(ap, format); 1087 jio_vsnprintf(_name, max_name_len, format, ap); 1088 va_end(ap); 1089 } 1090 1091 // ======= WatcherThread ======== 1092 1093 // The watcher thread exists to simulate timer interrupts. It should 1094 // be replaced by an abstraction over whatever native support for 1095 // timer interrupts exists on the platform. 1096 1097 WatcherThread* WatcherThread::_watcher_thread = NULL; 1098 volatile bool WatcherThread::_should_terminate = false; 1099 1100 WatcherThread::WatcherThread() : Thread() { 1101 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread"); 1102 if (os::create_thread(this, os::watcher_thread)) { 1103 _watcher_thread = this; 1104 1105 // Set the watcher thread to the highest OS priority which should not be 1106 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY 1107 // is created. The only normal thread using this priority is the reference 1108 // handler thread, which runs for very short intervals only. 1109 // If the VMThread's priority is not lower than the WatcherThread profiling 1110 // will be inaccurate. 1111 os::set_priority(this, MaxPriority); 1112 if (!DisableStartThread) { 1113 os::start_thread(this); 1114 } 1115 } 1116 } 1117 1118 void WatcherThread::run() { 1119 assert(this == watcher_thread(), "just checking"); 1120 1121 this->record_stack_base_and_size(); 1122 this->initialize_thread_local_storage(); 1123 this->set_active_handles(JNIHandleBlock::allocate_block()); 1124 while(!_should_terminate) { 1125 assert(watcher_thread() == Thread::current(), "thread consistency check"); 1126 assert(watcher_thread() == this, "thread consistency check"); 1127 1128 // Calculate how long it'll be until the next PeriodicTask work 1129 // should be done, and sleep that amount of time. 1130 size_t time_to_wait = PeriodicTask::time_to_wait(); 1131 1132 // we expect this to timeout - we only ever get unparked when 1133 // we should terminate 1134 { 1135 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */); 1136 1137 jlong prev_time = os::javaTimeNanos(); 1138 for (;;) { 1139 int res= _SleepEvent->park(time_to_wait); 1140 if (res == OS_TIMEOUT || _should_terminate) 1141 break; 1142 // spurious wakeup of some kind 1143 jlong now = os::javaTimeNanos(); 1144 time_to_wait -= (now - prev_time) / 1000000; 1145 if (time_to_wait <= 0) 1146 break; 1147 prev_time = now; 1148 } 1149 } 1150 1151 if (is_error_reported()) { 1152 // A fatal error has happened, the error handler(VMError::report_and_die) 1153 // should abort JVM after creating an error log file. However in some 1154 // rare cases, the error handler itself might deadlock. Here we try to 1155 // kill JVM if the fatal error handler fails to abort in 2 minutes. 1156 // 1157 // This code is in WatcherThread because WatcherThread wakes up 1158 // periodically so the fatal error handler doesn't need to do anything; 1159 // also because the WatcherThread is less likely to crash than other 1160 // threads. 1161 1162 for (;;) { 1163 if (!ShowMessageBoxOnError 1164 && (OnError == NULL || OnError[0] == '\0') 1165 && Arguments::abort_hook() == NULL) { 1166 os::sleep(this, 2 * 60 * 1000, false); 1167 fdStream err(defaultStream::output_fd()); 1168 err.print_raw_cr("# [ timer expired, abort... ]"); 1169 // skip atexit/vm_exit/vm_abort hooks 1170 os::die(); 1171 } 1172 1173 // Wake up 5 seconds later, the fatal handler may reset OnError or 1174 // ShowMessageBoxOnError when it is ready to abort. 1175 os::sleep(this, 5 * 1000, false); 1176 } 1177 } 1178 1179 PeriodicTask::real_time_tick(time_to_wait); 1180 1181 // If we have no more tasks left due to dynamic disenrollment, 1182 // shut down the thread since we don't currently support dynamic enrollment 1183 if (PeriodicTask::num_tasks() == 0) { 1184 _should_terminate = true; 1185 } 1186 } 1187 1188 // Signal that it is terminated 1189 { 1190 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag); 1191 _watcher_thread = NULL; 1192 Terminator_lock->notify(); 1193 } 1194 1195 // Thread destructor usually does this.. 1196 ThreadLocalStorage::set_thread(NULL); 1197 } 1198 1199 void WatcherThread::start() { 1200 if (watcher_thread() == NULL) { 1201 _should_terminate = false; 1202 // Create the single instance of WatcherThread 1203 new WatcherThread(); 1204 } 1205 } 1206 1207 void WatcherThread::stop() { 1208 // it is ok to take late safepoints here, if needed 1209 MutexLocker mu(Terminator_lock); 1210 _should_terminate = true; 1211 OrderAccess::fence(); // ensure WatcherThread sees update in main loop 1212 1213 Thread* watcher = watcher_thread(); 1214 if (watcher != NULL) 1215 watcher->_SleepEvent->unpark(); 1216 1217 while(watcher_thread() != NULL) { 1218 // This wait should make safepoint checks, wait without a timeout, 1219 // and wait as a suspend-equivalent condition. 1220 // 1221 // Note: If the FlatProfiler is running, then this thread is waiting 1222 // for the WatcherThread to terminate and the WatcherThread, via the 1223 // FlatProfiler task, is waiting for the external suspend request on 1224 // this thread to complete. wait_for_ext_suspend_completion() will 1225 // eventually timeout, but that takes time. Making this wait a 1226 // suspend-equivalent condition solves that timeout problem. 1227 // 1228 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 1229 Mutex::_as_suspend_equivalent_flag); 1230 } 1231 } 1232 1233 void WatcherThread::print_on(outputStream* st) const { 1234 st->print("\"%s\" ", name()); 1235 Thread::print_on(st); 1236 st->cr(); 1237 } 1238 1239 // ======= JavaThread ======== 1240 1241 // A JavaThread is a normal Java thread 1242 1243 void JavaThread::initialize() { 1244 // Initialize fields 1245 1246 // Set the claimed par_id to -1 (ie not claiming any par_ids) 1247 set_claimed_par_id(-1); 1248 1249 set_saved_exception_pc(NULL); 1250 set_threadObj(NULL); 1251 _anchor.clear(); 1252 set_entry_point(NULL); 1253 set_jni_functions(jni_functions()); 1254 set_callee_target(NULL); 1255 set_vm_result(NULL); 1256 set_vm_result_2(NULL); 1257 set_vframe_array_head(NULL); 1258 set_vframe_array_last(NULL); 1259 set_deferred_locals(NULL); 1260 set_deopt_mark(NULL); 1261 set_deopt_nmethod(NULL); 1262 clear_must_deopt_id(); 1263 set_monitor_chunks(NULL); 1264 set_next(NULL); 1265 set_thread_state(_thread_new); 1266 _terminated = _not_terminated; 1267 _privileged_stack_top = NULL; 1268 _array_for_gc = NULL; 1269 _suspend_equivalent = false; 1270 _in_deopt_handler = 0; 1271 _doing_unsafe_access = false; 1272 _stack_guard_state = stack_guard_unused; 1273 _exception_oop = NULL; 1274 _exception_pc = 0; 1275 _exception_handler_pc = 0; 1276 _is_method_handle_return = 0; 1277 _jvmti_thread_state= NULL; 1278 _should_post_on_exceptions_flag = JNI_FALSE; 1279 _jvmti_get_loaded_classes_closure = NULL; 1280 _interp_only_mode = 0; 1281 _special_runtime_exit_condition = _no_async_condition; 1282 _pending_async_exception = NULL; 1283 _is_compiling = false; 1284 _thread_stat = NULL; 1285 _thread_stat = new ThreadStatistics(); 1286 _blocked_on_compilation = false; 1287 _jni_active_critical = 0; 1288 _do_not_unlock_if_synchronized = false; 1289 _cached_monitor_info = NULL; 1290 _parker = Parker::Allocate(this) ; 1291 1292 #ifndef PRODUCT 1293 _jmp_ring_index = 0; 1294 for (int ji = 0 ; ji < jump_ring_buffer_size ; ji++ ) { 1295 record_jump(NULL, NULL, NULL, 0); 1296 } 1297 #endif /* PRODUCT */ 1298 1299 set_thread_profiler(NULL); 1300 if (FlatProfiler::is_active()) { 1301 // This is where we would decide to either give each thread it's own profiler 1302 // or use one global one from FlatProfiler, 1303 // or up to some count of the number of profiled threads, etc. 1304 ThreadProfiler* pp = new ThreadProfiler(); 1305 pp->engage(); 1306 set_thread_profiler(pp); 1307 } 1308 1309 // Setup safepoint state info for this thread 1310 ThreadSafepointState::create(this); 1311 1312 debug_only(_java_call_counter = 0); 1313 1314 // JVMTI PopFrame support 1315 _popframe_condition = popframe_inactive; 1316 _popframe_preserved_args = NULL; 1317 _popframe_preserved_args_size = 0; 1318 1319 pd_initialize(); 1320 } 1321 1322 #ifndef SERIALGC 1323 SATBMarkQueueSet JavaThread::_satb_mark_queue_set; 1324 DirtyCardQueueSet JavaThread::_dirty_card_queue_set; 1325 #endif // !SERIALGC 1326 1327 JavaThread::JavaThread(bool is_attaching) : 1328 Thread() 1329 #ifndef SERIALGC 1330 , _satb_mark_queue(&_satb_mark_queue_set), 1331 _dirty_card_queue(&_dirty_card_queue_set) 1332 #endif // !SERIALGC 1333 { 1334 initialize(); 1335 _is_attaching = is_attaching; 1336 assert(_deferred_card_mark.is_empty(), "Default MemRegion ctor"); 1337 } 1338 1339 bool JavaThread::reguard_stack(address cur_sp) { 1340 if (_stack_guard_state != stack_guard_yellow_disabled) { 1341 return true; // Stack already guarded or guard pages not needed. 1342 } 1343 1344 if (register_stack_overflow()) { 1345 // For those architectures which have separate register and 1346 // memory stacks, we must check the register stack to see if 1347 // it has overflowed. 1348 return false; 1349 } 1350 1351 // Java code never executes within the yellow zone: the latter is only 1352 // there to provoke an exception during stack banging. If java code 1353 // is executing there, either StackShadowPages should be larger, or 1354 // some exception code in c1, c2 or the interpreter isn't unwinding 1355 // when it should. 1356 guarantee(cur_sp > stack_yellow_zone_base(), "not enough space to reguard - increase StackShadowPages"); 1357 1358 enable_stack_yellow_zone(); 1359 return true; 1360 } 1361 1362 bool JavaThread::reguard_stack(void) { 1363 return reguard_stack(os::current_stack_pointer()); 1364 } 1365 1366 1367 void JavaThread::block_if_vm_exited() { 1368 if (_terminated == _vm_exited) { 1369 // _vm_exited is set at safepoint, and Threads_lock is never released 1370 // we will block here forever 1371 Threads_lock->lock_without_safepoint_check(); 1372 ShouldNotReachHere(); 1373 } 1374 } 1375 1376 1377 // Remove this ifdef when C1 is ported to the compiler interface. 1378 static void compiler_thread_entry(JavaThread* thread, TRAPS); 1379 1380 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) : 1381 Thread() 1382 #ifndef SERIALGC 1383 , _satb_mark_queue(&_satb_mark_queue_set), 1384 _dirty_card_queue(&_dirty_card_queue_set) 1385 #endif // !SERIALGC 1386 { 1387 if (TraceThreadEvents) { 1388 tty->print_cr("creating thread %p", this); 1389 } 1390 initialize(); 1391 _is_attaching = false; 1392 set_entry_point(entry_point); 1393 // Create the native thread itself. 1394 // %note runtime_23 1395 os::ThreadType thr_type = os::java_thread; 1396 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread : 1397 os::java_thread; 1398 os::create_thread(this, thr_type, stack_sz); 1399 1400 // The _osthread may be NULL here because we ran out of memory (too many threads active). 1401 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller 1402 // may hold a lock and all locks must be unlocked before throwing the exception (throwing 1403 // the exception consists of creating the exception object & initializing it, initialization 1404 // will leave the VM via a JavaCall and then all locks must be unlocked). 1405 // 1406 // The thread is still suspended when we reach here. Thread must be explicit started 1407 // by creator! Furthermore, the thread must also explicitly be added to the Threads list 1408 // by calling Threads:add. The reason why this is not done here, is because the thread 1409 // object must be fully initialized (take a look at JVM_Start) 1410 } 1411 1412 JavaThread::~JavaThread() { 1413 if (TraceThreadEvents) { 1414 tty->print_cr("terminate thread %p", this); 1415 } 1416 1417 // JSR166 -- return the parker to the free list 1418 Parker::Release(_parker); 1419 _parker = NULL ; 1420 1421 // Free any remaining previous UnrollBlock 1422 vframeArray* old_array = vframe_array_last(); 1423 1424 if (old_array != NULL) { 1425 Deoptimization::UnrollBlock* old_info = old_array->unroll_block(); 1426 old_array->set_unroll_block(NULL); 1427 delete old_info; 1428 delete old_array; 1429 } 1430 1431 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals(); 1432 if (deferred != NULL) { 1433 // This can only happen if thread is destroyed before deoptimization occurs. 1434 assert(deferred->length() != 0, "empty array!"); 1435 do { 1436 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0); 1437 deferred->remove_at(0); 1438 // individual jvmtiDeferredLocalVariableSet are CHeapObj's 1439 delete dlv; 1440 } while (deferred->length() != 0); 1441 delete deferred; 1442 } 1443 1444 // All Java related clean up happens in exit 1445 ThreadSafepointState::destroy(this); 1446 if (_thread_profiler != NULL) delete _thread_profiler; 1447 if (_thread_stat != NULL) delete _thread_stat; 1448 } 1449 1450 1451 // The first routine called by a new Java thread 1452 void JavaThread::run() { 1453 // initialize thread-local alloc buffer related fields 1454 this->initialize_tlab(); 1455 1456 // used to test validitity of stack trace backs 1457 this->record_base_of_stack_pointer(); 1458 1459 // Record real stack base and size. 1460 this->record_stack_base_and_size(); 1461 1462 // Initialize thread local storage; set before calling MutexLocker 1463 this->initialize_thread_local_storage(); 1464 1465 this->create_stack_guard_pages(); 1466 1467 this->cache_global_variables(); 1468 1469 // Thread is now sufficient initialized to be handled by the safepoint code as being 1470 // in the VM. Change thread state from _thread_new to _thread_in_vm 1471 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm); 1472 1473 assert(JavaThread::current() == this, "sanity check"); 1474 assert(!Thread::current()->owns_locks(), "sanity check"); 1475 1476 DTRACE_THREAD_PROBE(start, this); 1477 1478 // This operation might block. We call that after all safepoint checks for a new thread has 1479 // been completed. 1480 this->set_active_handles(JNIHandleBlock::allocate_block()); 1481 1482 if (JvmtiExport::should_post_thread_life()) { 1483 JvmtiExport::post_thread_start(this); 1484 } 1485 1486 // We call another function to do the rest so we are sure that the stack addresses used 1487 // from there will be lower than the stack base just computed 1488 thread_main_inner(); 1489 1490 // Note, thread is no longer valid at this point! 1491 } 1492 1493 1494 void JavaThread::thread_main_inner() { 1495 assert(JavaThread::current() == this, "sanity check"); 1496 assert(this->threadObj() != NULL, "just checking"); 1497 1498 // Execute thread entry point unless this thread has a pending exception 1499 // or has been stopped before starting. 1500 // Note: Due to JVM_StopThread we can have pending exceptions already! 1501 if (!this->has_pending_exception() && 1502 !java_lang_Thread::is_stillborn(this->threadObj())) { 1503 HandleMark hm(this); 1504 this->entry_point()(this, this); 1505 } 1506 1507 DTRACE_THREAD_PROBE(stop, this); 1508 1509 this->exit(false); 1510 delete this; 1511 } 1512 1513 1514 static void ensure_join(JavaThread* thread) { 1515 // We do not need to grap the Threads_lock, since we are operating on ourself. 1516 Handle threadObj(thread, thread->threadObj()); 1517 assert(threadObj.not_null(), "java thread object must exist"); 1518 ObjectLocker lock(threadObj, thread); 1519 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1520 thread->clear_pending_exception(); 1521 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED. 1522 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED); 1523 // Clear the native thread instance - this makes isAlive return false and allows the join() 1524 // to complete once we've done the notify_all below 1525 java_lang_Thread::set_thread(threadObj(), NULL); 1526 lock.notify_all(thread); 1527 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1528 thread->clear_pending_exception(); 1529 } 1530 1531 1532 // For any new cleanup additions, please check to see if they need to be applied to 1533 // cleanup_failed_attach_current_thread as well. 1534 void JavaThread::exit(bool destroy_vm, ExitType exit_type) { 1535 assert(this == JavaThread::current(), "thread consistency check"); 1536 if (!InitializeJavaLangSystem) return; 1537 1538 HandleMark hm(this); 1539 Handle uncaught_exception(this, this->pending_exception()); 1540 this->clear_pending_exception(); 1541 Handle threadObj(this, this->threadObj()); 1542 assert(threadObj.not_null(), "Java thread object should be created"); 1543 1544 if (get_thread_profiler() != NULL) { 1545 get_thread_profiler()->disengage(); 1546 ResourceMark rm; 1547 get_thread_profiler()->print(get_thread_name()); 1548 } 1549 1550 1551 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place 1552 { 1553 EXCEPTION_MARK; 1554 1555 CLEAR_PENDING_EXCEPTION; 1556 } 1557 // FIXIT: The is_null check is only so it works better on JDK1.2 VM's. This 1558 // has to be fixed by a runtime query method 1559 if (!destroy_vm || JDK_Version::is_jdk12x_version()) { 1560 // JSR-166: change call from from ThreadGroup.uncaughtException to 1561 // java.lang.Thread.dispatchUncaughtException 1562 if (uncaught_exception.not_null()) { 1563 Handle group(this, java_lang_Thread::threadGroup(threadObj())); 1564 Events::log("uncaught exception INTPTR_FORMAT " " INTPTR_FORMAT " " INTPTR_FORMAT", 1565 (address)uncaught_exception(), (address)threadObj(), (address)group()); 1566 { 1567 EXCEPTION_MARK; 1568 // Check if the method Thread.dispatchUncaughtException() exists. If so 1569 // call it. Otherwise we have an older library without the JSR-166 changes, 1570 // so call ThreadGroup.uncaughtException() 1571 KlassHandle recvrKlass(THREAD, threadObj->klass()); 1572 CallInfo callinfo; 1573 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass()); 1574 LinkResolver::resolve_virtual_call(callinfo, threadObj, recvrKlass, thread_klass, 1575 vmSymbols::dispatchUncaughtException_name(), 1576 vmSymbols::throwable_void_signature(), 1577 KlassHandle(), false, false, THREAD); 1578 CLEAR_PENDING_EXCEPTION; 1579 methodHandle method = callinfo.selected_method(); 1580 if (method.not_null()) { 1581 JavaValue result(T_VOID); 1582 JavaCalls::call_virtual(&result, 1583 threadObj, thread_klass, 1584 vmSymbols::dispatchUncaughtException_name(), 1585 vmSymbols::throwable_void_signature(), 1586 uncaught_exception, 1587 THREAD); 1588 } else { 1589 KlassHandle thread_group(THREAD, SystemDictionary::ThreadGroup_klass()); 1590 JavaValue result(T_VOID); 1591 JavaCalls::call_virtual(&result, 1592 group, thread_group, 1593 vmSymbols::uncaughtException_name(), 1594 vmSymbols::thread_throwable_void_signature(), 1595 threadObj, // Arg 1 1596 uncaught_exception, // Arg 2 1597 THREAD); 1598 } 1599 if (HAS_PENDING_EXCEPTION) { 1600 ResourceMark rm(this); 1601 jio_fprintf(defaultStream::error_stream(), 1602 "\nException: %s thrown from the UncaughtExceptionHandler" 1603 " in thread \"%s\"\n", 1604 Klass::cast(pending_exception()->klass())->external_name(), 1605 get_thread_name()); 1606 CLEAR_PENDING_EXCEPTION; 1607 } 1608 } 1609 } 1610 1611 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during 1612 // the execution of the method. If that is not enough, then we don't really care. Thread.stop 1613 // is deprecated anyhow. 1614 { int count = 3; 1615 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) { 1616 EXCEPTION_MARK; 1617 JavaValue result(T_VOID); 1618 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass()); 1619 JavaCalls::call_virtual(&result, 1620 threadObj, thread_klass, 1621 vmSymbols::exit_method_name(), 1622 vmSymbols::void_method_signature(), 1623 THREAD); 1624 CLEAR_PENDING_EXCEPTION; 1625 } 1626 } 1627 1628 // notify JVMTI 1629 if (JvmtiExport::should_post_thread_life()) { 1630 JvmtiExport::post_thread_end(this); 1631 } 1632 1633 // We have notified the agents that we are exiting, before we go on, 1634 // we must check for a pending external suspend request and honor it 1635 // in order to not surprise the thread that made the suspend request. 1636 while (true) { 1637 { 1638 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 1639 if (!is_external_suspend()) { 1640 set_terminated(_thread_exiting); 1641 ThreadService::current_thread_exiting(this); 1642 break; 1643 } 1644 // Implied else: 1645 // Things get a little tricky here. We have a pending external 1646 // suspend request, but we are holding the SR_lock so we 1647 // can't just self-suspend. So we temporarily drop the lock 1648 // and then self-suspend. 1649 } 1650 1651 ThreadBlockInVM tbivm(this); 1652 java_suspend_self(); 1653 1654 // We're done with this suspend request, but we have to loop around 1655 // and check again. Eventually we will get SR_lock without a pending 1656 // external suspend request and will be able to mark ourselves as 1657 // exiting. 1658 } 1659 // no more external suspends are allowed at this point 1660 } else { 1661 // before_exit() has already posted JVMTI THREAD_END events 1662 } 1663 1664 // Notify waiters on thread object. This has to be done after exit() is called 1665 // on the thread (if the thread is the last thread in a daemon ThreadGroup the 1666 // group should have the destroyed bit set before waiters are notified). 1667 ensure_join(this); 1668 assert(!this->has_pending_exception(), "ensure_join should have cleared"); 1669 1670 // 6282335 JNI DetachCurrentThread spec states that all Java monitors 1671 // held by this thread must be released. A detach operation must only 1672 // get here if there are no Java frames on the stack. Therefore, any 1673 // owned monitors at this point MUST be JNI-acquired monitors which are 1674 // pre-inflated and in the monitor cache. 1675 // 1676 // ensure_join() ignores IllegalThreadStateExceptions, and so does this. 1677 if (exit_type == jni_detach && JNIDetachReleasesMonitors) { 1678 assert(!this->has_last_Java_frame(), "detaching with Java frames?"); 1679 ObjectSynchronizer::release_monitors_owned_by_thread(this); 1680 assert(!this->has_pending_exception(), "release_monitors should have cleared"); 1681 } 1682 1683 // These things needs to be done while we are still a Java Thread. Make sure that thread 1684 // is in a consistent state, in case GC happens 1685 assert(_privileged_stack_top == NULL, "must be NULL when we get here"); 1686 1687 if (active_handles() != NULL) { 1688 JNIHandleBlock* block = active_handles(); 1689 set_active_handles(NULL); 1690 JNIHandleBlock::release_block(block); 1691 } 1692 1693 if (free_handle_block() != NULL) { 1694 JNIHandleBlock* block = free_handle_block(); 1695 set_free_handle_block(NULL); 1696 JNIHandleBlock::release_block(block); 1697 } 1698 1699 // These have to be removed while this is still a valid thread. 1700 remove_stack_guard_pages(); 1701 1702 if (UseTLAB) { 1703 tlab().make_parsable(true); // retire TLAB 1704 } 1705 1706 if (JvmtiEnv::environments_might_exist()) { 1707 JvmtiExport::cleanup_thread(this); 1708 } 1709 1710 #ifndef SERIALGC 1711 // We must flush G1-related buffers before removing a thread from 1712 // the list of active threads. 1713 if (UseG1GC) { 1714 flush_barrier_queues(); 1715 } 1716 #endif 1717 1718 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread 1719 Threads::remove(this); 1720 } 1721 1722 #ifndef SERIALGC 1723 // Flush G1-related queues. 1724 void JavaThread::flush_barrier_queues() { 1725 satb_mark_queue().flush(); 1726 dirty_card_queue().flush(); 1727 } 1728 1729 void JavaThread::initialize_queues() { 1730 assert(!SafepointSynchronize::is_at_safepoint(), 1731 "we should not be at a safepoint"); 1732 1733 ObjPtrQueue& satb_queue = satb_mark_queue(); 1734 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set(); 1735 // The SATB queue should have been constructed with its active 1736 // field set to false. 1737 assert(!satb_queue.is_active(), "SATB queue should not be active"); 1738 assert(satb_queue.is_empty(), "SATB queue should be empty"); 1739 // If we are creating the thread during a marking cycle, we should 1740 // set the active field of the SATB queue to true. 1741 if (satb_queue_set.is_active()) { 1742 satb_queue.set_active(true); 1743 } 1744 1745 DirtyCardQueue& dirty_queue = dirty_card_queue(); 1746 // The dirty card queue should have been constructed with its 1747 // active field set to true. 1748 assert(dirty_queue.is_active(), "dirty card queue should be active"); 1749 } 1750 #endif // !SERIALGC 1751 1752 void JavaThread::cleanup_failed_attach_current_thread() { 1753 if (get_thread_profiler() != NULL) { 1754 get_thread_profiler()->disengage(); 1755 ResourceMark rm; 1756 get_thread_profiler()->print(get_thread_name()); 1757 } 1758 1759 if (active_handles() != NULL) { 1760 JNIHandleBlock* block = active_handles(); 1761 set_active_handles(NULL); 1762 JNIHandleBlock::release_block(block); 1763 } 1764 1765 if (free_handle_block() != NULL) { 1766 JNIHandleBlock* block = free_handle_block(); 1767 set_free_handle_block(NULL); 1768 JNIHandleBlock::release_block(block); 1769 } 1770 1771 // These have to be removed while this is still a valid thread. 1772 remove_stack_guard_pages(); 1773 1774 if (UseTLAB) { 1775 tlab().make_parsable(true); // retire TLAB, if any 1776 } 1777 1778 #ifndef SERIALGC 1779 if (UseG1GC) { 1780 flush_barrier_queues(); 1781 } 1782 #endif 1783 1784 Threads::remove(this); 1785 delete this; 1786 } 1787 1788 1789 1790 1791 JavaThread* JavaThread::active() { 1792 Thread* thread = ThreadLocalStorage::thread(); 1793 assert(thread != NULL, "just checking"); 1794 if (thread->is_Java_thread()) { 1795 return (JavaThread*) thread; 1796 } else { 1797 assert(thread->is_VM_thread(), "this must be a vm thread"); 1798 VM_Operation* op = ((VMThread*) thread)->vm_operation(); 1799 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread(); 1800 assert(ret->is_Java_thread(), "must be a Java thread"); 1801 return ret; 1802 } 1803 } 1804 1805 bool JavaThread::is_lock_owned(address adr) const { 1806 if (Thread::is_lock_owned(adr)) return true; 1807 1808 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 1809 if (chunk->contains(adr)) return true; 1810 } 1811 1812 return false; 1813 } 1814 1815 1816 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) { 1817 chunk->set_next(monitor_chunks()); 1818 set_monitor_chunks(chunk); 1819 } 1820 1821 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) { 1822 guarantee(monitor_chunks() != NULL, "must be non empty"); 1823 if (monitor_chunks() == chunk) { 1824 set_monitor_chunks(chunk->next()); 1825 } else { 1826 MonitorChunk* prev = monitor_chunks(); 1827 while (prev->next() != chunk) prev = prev->next(); 1828 prev->set_next(chunk->next()); 1829 } 1830 } 1831 1832 // JVM support. 1833 1834 // Note: this function shouldn't block if it's called in 1835 // _thread_in_native_trans state (such as from 1836 // check_special_condition_for_native_trans()). 1837 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) { 1838 1839 if (has_last_Java_frame() && has_async_condition()) { 1840 // If we are at a polling page safepoint (not a poll return) 1841 // then we must defer async exception because live registers 1842 // will be clobbered by the exception path. Poll return is 1843 // ok because the call we a returning from already collides 1844 // with exception handling registers and so there is no issue. 1845 // (The exception handling path kills call result registers but 1846 // this is ok since the exception kills the result anyway). 1847 1848 if (is_at_poll_safepoint()) { 1849 // if the code we are returning to has deoptimized we must defer 1850 // the exception otherwise live registers get clobbered on the 1851 // exception path before deoptimization is able to retrieve them. 1852 // 1853 RegisterMap map(this, false); 1854 frame caller_fr = last_frame().sender(&map); 1855 assert(caller_fr.is_compiled_frame(), "what?"); 1856 if (caller_fr.is_deoptimized_frame()) { 1857 if (TraceExceptions) { 1858 ResourceMark rm; 1859 tty->print_cr("deferred async exception at compiled safepoint"); 1860 } 1861 return; 1862 } 1863 } 1864 } 1865 1866 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition(); 1867 if (condition == _no_async_condition) { 1868 // Conditions have changed since has_special_runtime_exit_condition() 1869 // was called: 1870 // - if we were here only because of an external suspend request, 1871 // then that was taken care of above (or cancelled) so we are done 1872 // - if we were here because of another async request, then it has 1873 // been cleared between the has_special_runtime_exit_condition() 1874 // and now so again we are done 1875 return; 1876 } 1877 1878 // Check for pending async. exception 1879 if (_pending_async_exception != NULL) { 1880 // Only overwrite an already pending exception, if it is not a threadDeath. 1881 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) { 1882 1883 // We cannot call Exceptions::_throw(...) here because we cannot block 1884 set_pending_exception(_pending_async_exception, __FILE__, __LINE__); 1885 1886 if (TraceExceptions) { 1887 ResourceMark rm; 1888 tty->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", this); 1889 if (has_last_Java_frame() ) { 1890 frame f = last_frame(); 1891 tty->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", f.pc(), f.sp()); 1892 } 1893 tty->print_cr(" of type: %s", instanceKlass::cast(_pending_async_exception->klass())->external_name()); 1894 } 1895 _pending_async_exception = NULL; 1896 clear_has_async_exception(); 1897 } 1898 } 1899 1900 if (check_unsafe_error && 1901 condition == _async_unsafe_access_error && !has_pending_exception()) { 1902 condition = _no_async_condition; // done 1903 switch (thread_state()) { 1904 case _thread_in_vm: 1905 { 1906 JavaThread* THREAD = this; 1907 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 1908 } 1909 case _thread_in_native: 1910 { 1911 ThreadInVMfromNative tiv(this); 1912 JavaThread* THREAD = this; 1913 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 1914 } 1915 case _thread_in_Java: 1916 { 1917 ThreadInVMfromJava tiv(this); 1918 JavaThread* THREAD = this; 1919 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code"); 1920 } 1921 default: 1922 ShouldNotReachHere(); 1923 } 1924 } 1925 1926 assert(condition == _no_async_condition || has_pending_exception() || 1927 (!check_unsafe_error && condition == _async_unsafe_access_error), 1928 "must have handled the async condition, if no exception"); 1929 } 1930 1931 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) { 1932 // 1933 // Check for pending external suspend. Internal suspend requests do 1934 // not use handle_special_runtime_exit_condition(). 1935 // If JNIEnv proxies are allowed, don't self-suspend if the target 1936 // thread is not the current thread. In older versions of jdbx, jdbx 1937 // threads could call into the VM with another thread's JNIEnv so we 1938 // can be here operating on behalf of a suspended thread (4432884). 1939 bool do_self_suspend = is_external_suspend_with_lock(); 1940 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) { 1941 // 1942 // Because thread is external suspended the safepoint code will count 1943 // thread as at a safepoint. This can be odd because we can be here 1944 // as _thread_in_Java which would normally transition to _thread_blocked 1945 // at a safepoint. We would like to mark the thread as _thread_blocked 1946 // before calling java_suspend_self like all other callers of it but 1947 // we must then observe proper safepoint protocol. (We can't leave 1948 // _thread_blocked with a safepoint in progress). However we can be 1949 // here as _thread_in_native_trans so we can't use a normal transition 1950 // constructor/destructor pair because they assert on that type of 1951 // transition. We could do something like: 1952 // 1953 // JavaThreadState state = thread_state(); 1954 // set_thread_state(_thread_in_vm); 1955 // { 1956 // ThreadBlockInVM tbivm(this); 1957 // java_suspend_self() 1958 // } 1959 // set_thread_state(_thread_in_vm_trans); 1960 // if (safepoint) block; 1961 // set_thread_state(state); 1962 // 1963 // but that is pretty messy. Instead we just go with the way the 1964 // code has worked before and note that this is the only path to 1965 // java_suspend_self that doesn't put the thread in _thread_blocked 1966 // mode. 1967 1968 frame_anchor()->make_walkable(this); 1969 java_suspend_self(); 1970 1971 // We might be here for reasons in addition to the self-suspend request 1972 // so check for other async requests. 1973 } 1974 1975 if (check_asyncs) { 1976 check_and_handle_async_exceptions(); 1977 } 1978 } 1979 1980 void JavaThread::send_thread_stop(oop java_throwable) { 1981 assert(Thread::current()->is_VM_thread(), "should be in the vm thread"); 1982 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code"); 1983 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 1984 1985 // Do not throw asynchronous exceptions against the compiler thread 1986 // (the compiler thread should not be a Java thread -- fix in 1.4.2) 1987 if (is_Compiler_thread()) return; 1988 1989 { 1990 // Actually throw the Throwable against the target Thread - however 1991 // only if there is no thread death exception installed already. 1992 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) { 1993 // If the topmost frame is a runtime stub, then we are calling into 1994 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..) 1995 // must deoptimize the caller before continuing, as the compiled exception handler table 1996 // may not be valid 1997 if (has_last_Java_frame()) { 1998 frame f = last_frame(); 1999 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) { 2000 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2001 RegisterMap reg_map(this, UseBiasedLocking); 2002 frame compiled_frame = f.sender(®_map); 2003 if (compiled_frame.can_be_deoptimized()) { 2004 Deoptimization::deoptimize(this, compiled_frame, ®_map); 2005 } 2006 } 2007 } 2008 2009 // Set async. pending exception in thread. 2010 set_pending_async_exception(java_throwable); 2011 2012 if (TraceExceptions) { 2013 ResourceMark rm; 2014 tty->print_cr("Pending Async. exception installed of type: %s", instanceKlass::cast(_pending_async_exception->klass())->external_name()); 2015 } 2016 // for AbortVMOnException flag 2017 NOT_PRODUCT(Exceptions::debug_check_abort(instanceKlass::cast(_pending_async_exception->klass())->external_name())); 2018 } 2019 } 2020 2021 2022 // Interrupt thread so it will wake up from a potential wait() 2023 Thread::interrupt(this); 2024 } 2025 2026 // External suspension mechanism. 2027 // 2028 // Tell the VM to suspend a thread when ever it knows that it does not hold on 2029 // to any VM_locks and it is at a transition 2030 // Self-suspension will happen on the transition out of the vm. 2031 // Catch "this" coming in from JNIEnv pointers when the thread has been freed 2032 // 2033 // Guarantees on return: 2034 // + Target thread will not execute any new bytecode (that's why we need to 2035 // force a safepoint) 2036 // + Target thread will not enter any new monitors 2037 // 2038 void JavaThread::java_suspend() { 2039 { MutexLocker mu(Threads_lock); 2040 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) { 2041 return; 2042 } 2043 } 2044 2045 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2046 if (!is_external_suspend()) { 2047 // a racing resume has cancelled us; bail out now 2048 return; 2049 } 2050 2051 // suspend is done 2052 uint32_t debug_bits = 0; 2053 // Warning: is_ext_suspend_completed() may temporarily drop the 2054 // SR_lock to allow the thread to reach a stable thread state if 2055 // it is currently in a transient thread state. 2056 if (is_ext_suspend_completed(false /* !called_by_wait */, 2057 SuspendRetryDelay, &debug_bits) ) { 2058 return; 2059 } 2060 } 2061 2062 VM_ForceSafepoint vm_suspend; 2063 VMThread::execute(&vm_suspend); 2064 } 2065 2066 // Part II of external suspension. 2067 // A JavaThread self suspends when it detects a pending external suspend 2068 // request. This is usually on transitions. It is also done in places 2069 // where continuing to the next transition would surprise the caller, 2070 // e.g., monitor entry. 2071 // 2072 // Returns the number of times that the thread self-suspended. 2073 // 2074 // Note: DO NOT call java_suspend_self() when you just want to block current 2075 // thread. java_suspend_self() is the second stage of cooperative 2076 // suspension for external suspend requests and should only be used 2077 // to complete an external suspend request. 2078 // 2079 int JavaThread::java_suspend_self() { 2080 int ret = 0; 2081 2082 // we are in the process of exiting so don't suspend 2083 if (is_exiting()) { 2084 clear_external_suspend(); 2085 return ret; 2086 } 2087 2088 assert(_anchor.walkable() || 2089 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()), 2090 "must have walkable stack"); 2091 2092 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2093 2094 assert(!this->is_ext_suspended(), 2095 "a thread trying to self-suspend should not already be suspended"); 2096 2097 if (this->is_suspend_equivalent()) { 2098 // If we are self-suspending as a result of the lifting of a 2099 // suspend equivalent condition, then the suspend_equivalent 2100 // flag is not cleared until we set the ext_suspended flag so 2101 // that wait_for_ext_suspend_completion() returns consistent 2102 // results. 2103 this->clear_suspend_equivalent(); 2104 } 2105 2106 // A racing resume may have cancelled us before we grabbed SR_lock 2107 // above. Or another external suspend request could be waiting for us 2108 // by the time we return from SR_lock()->wait(). The thread 2109 // that requested the suspension may already be trying to walk our 2110 // stack and if we return now, we can change the stack out from under 2111 // it. This would be a "bad thing (TM)" and cause the stack walker 2112 // to crash. We stay self-suspended until there are no more pending 2113 // external suspend requests. 2114 while (is_external_suspend()) { 2115 ret++; 2116 this->set_ext_suspended(); 2117 2118 // _ext_suspended flag is cleared by java_resume() 2119 while (is_ext_suspended()) { 2120 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag); 2121 } 2122 } 2123 2124 return ret; 2125 } 2126 2127 #ifdef ASSERT 2128 // verify the JavaThread has not yet been published in the Threads::list, and 2129 // hence doesn't need protection from concurrent access at this stage 2130 void JavaThread::verify_not_published() { 2131 if (!Threads_lock->owned_by_self()) { 2132 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag); 2133 assert( !Threads::includes(this), 2134 "java thread shouldn't have been published yet!"); 2135 } 2136 else { 2137 assert( !Threads::includes(this), 2138 "java thread shouldn't have been published yet!"); 2139 } 2140 } 2141 #endif 2142 2143 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2144 // progress or when _suspend_flags is non-zero. 2145 // Current thread needs to self-suspend if there is a suspend request and/or 2146 // block if a safepoint is in progress. 2147 // Async exception ISN'T checked. 2148 // Note only the ThreadInVMfromNative transition can call this function 2149 // directly and when thread state is _thread_in_native_trans 2150 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) { 2151 assert(thread->thread_state() == _thread_in_native_trans, "wrong state"); 2152 2153 JavaThread *curJT = JavaThread::current(); 2154 bool do_self_suspend = thread->is_external_suspend(); 2155 2156 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition"); 2157 2158 // If JNIEnv proxies are allowed, don't self-suspend if the target 2159 // thread is not the current thread. In older versions of jdbx, jdbx 2160 // threads could call into the VM with another thread's JNIEnv so we 2161 // can be here operating on behalf of a suspended thread (4432884). 2162 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) { 2163 JavaThreadState state = thread->thread_state(); 2164 2165 // We mark this thread_blocked state as a suspend-equivalent so 2166 // that a caller to is_ext_suspend_completed() won't be confused. 2167 // The suspend-equivalent state is cleared by java_suspend_self(). 2168 thread->set_suspend_equivalent(); 2169 2170 // If the safepoint code sees the _thread_in_native_trans state, it will 2171 // wait until the thread changes to other thread state. There is no 2172 // guarantee on how soon we can obtain the SR_lock and complete the 2173 // self-suspend request. It would be a bad idea to let safepoint wait for 2174 // too long. Temporarily change the state to _thread_blocked to 2175 // let the VM thread know that this thread is ready for GC. The problem 2176 // of changing thread state is that safepoint could happen just after 2177 // java_suspend_self() returns after being resumed, and VM thread will 2178 // see the _thread_blocked state. We must check for safepoint 2179 // after restoring the state and make sure we won't leave while a safepoint 2180 // is in progress. 2181 thread->set_thread_state(_thread_blocked); 2182 thread->java_suspend_self(); 2183 thread->set_thread_state(state); 2184 // Make sure new state is seen by VM thread 2185 if (os::is_MP()) { 2186 if (UseMembar) { 2187 // Force a fence between the write above and read below 2188 OrderAccess::fence(); 2189 } else { 2190 // Must use this rather than serialization page in particular on Windows 2191 InterfaceSupport::serialize_memory(thread); 2192 } 2193 } 2194 } 2195 2196 if (SafepointSynchronize::do_call_back()) { 2197 // If we are safepointing, then block the caller which may not be 2198 // the same as the target thread (see above). 2199 SafepointSynchronize::block(curJT); 2200 } 2201 2202 if (thread->is_deopt_suspend()) { 2203 thread->clear_deopt_suspend(); 2204 RegisterMap map(thread, false); 2205 frame f = thread->last_frame(); 2206 while ( f.id() != thread->must_deopt_id() && ! f.is_first_frame()) { 2207 f = f.sender(&map); 2208 } 2209 if (f.id() == thread->must_deopt_id()) { 2210 thread->clear_must_deopt_id(); 2211 f.deoptimize(thread); 2212 } else { 2213 fatal("missed deoptimization!"); 2214 } 2215 } 2216 } 2217 2218 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2219 // progress or when _suspend_flags is non-zero. 2220 // Current thread needs to self-suspend if there is a suspend request and/or 2221 // block if a safepoint is in progress. 2222 // Also check for pending async exception (not including unsafe access error). 2223 // Note only the native==>VM/Java barriers can call this function and when 2224 // thread state is _thread_in_native_trans. 2225 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) { 2226 check_safepoint_and_suspend_for_native_trans(thread); 2227 2228 if (thread->has_async_exception()) { 2229 // We are in _thread_in_native_trans state, don't handle unsafe 2230 // access error since that may block. 2231 thread->check_and_handle_async_exceptions(false); 2232 } 2233 } 2234 2235 // We need to guarantee the Threads_lock here, since resumes are not 2236 // allowed during safepoint synchronization 2237 // Can only resume from an external suspension 2238 void JavaThread::java_resume() { 2239 assert_locked_or_safepoint(Threads_lock); 2240 2241 // Sanity check: thread is gone, has started exiting or the thread 2242 // was not externally suspended. 2243 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) { 2244 return; 2245 } 2246 2247 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2248 2249 clear_external_suspend(); 2250 2251 if (is_ext_suspended()) { 2252 clear_ext_suspended(); 2253 SR_lock()->notify_all(); 2254 } 2255 } 2256 2257 void JavaThread::create_stack_guard_pages() { 2258 if (! os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) return; 2259 address low_addr = stack_base() - stack_size(); 2260 size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size(); 2261 2262 int allocate = os::allocate_stack_guard_pages(); 2263 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len); 2264 2265 if (allocate && !os::create_stack_guard_pages((char *) low_addr, len)) { 2266 warning("Attempt to allocate stack guard pages failed."); 2267 return; 2268 } 2269 2270 if (os::guard_memory((char *) low_addr, len)) { 2271 _stack_guard_state = stack_guard_enabled; 2272 } else { 2273 warning("Attempt to protect stack guard pages failed."); 2274 if (os::uncommit_memory((char *) low_addr, len)) { 2275 warning("Attempt to deallocate stack guard pages failed."); 2276 } 2277 } 2278 } 2279 2280 void JavaThread::remove_stack_guard_pages() { 2281 if (_stack_guard_state == stack_guard_unused) return; 2282 address low_addr = stack_base() - stack_size(); 2283 size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size(); 2284 2285 if (os::allocate_stack_guard_pages()) { 2286 if (os::remove_stack_guard_pages((char *) low_addr, len)) { 2287 _stack_guard_state = stack_guard_unused; 2288 } else { 2289 warning("Attempt to deallocate stack guard pages failed."); 2290 } 2291 } else { 2292 if (_stack_guard_state == stack_guard_unused) return; 2293 if (os::unguard_memory((char *) low_addr, len)) { 2294 _stack_guard_state = stack_guard_unused; 2295 } else { 2296 warning("Attempt to unprotect stack guard pages failed."); 2297 } 2298 } 2299 } 2300 2301 void JavaThread::enable_stack_yellow_zone() { 2302 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2303 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2304 2305 // The base notation is from the stacks point of view, growing downward. 2306 // We need to adjust it to work correctly with guard_memory() 2307 address base = stack_yellow_zone_base() - stack_yellow_zone_size(); 2308 2309 guarantee(base < stack_base(),"Error calculating stack yellow zone"); 2310 guarantee(base < os::current_stack_pointer(),"Error calculating stack yellow zone"); 2311 2312 if (os::guard_memory((char *) base, stack_yellow_zone_size())) { 2313 _stack_guard_state = stack_guard_enabled; 2314 } else { 2315 warning("Attempt to guard stack yellow zone failed."); 2316 } 2317 enable_register_stack_guard(); 2318 } 2319 2320 void JavaThread::disable_stack_yellow_zone() { 2321 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2322 assert(_stack_guard_state != stack_guard_yellow_disabled, "already disabled"); 2323 2324 // Simply return if called for a thread that does not use guard pages. 2325 if (_stack_guard_state == stack_guard_unused) return; 2326 2327 // The base notation is from the stacks point of view, growing downward. 2328 // We need to adjust it to work correctly with guard_memory() 2329 address base = stack_yellow_zone_base() - stack_yellow_zone_size(); 2330 2331 if (os::unguard_memory((char *)base, stack_yellow_zone_size())) { 2332 _stack_guard_state = stack_guard_yellow_disabled; 2333 } else { 2334 warning("Attempt to unguard stack yellow zone failed."); 2335 } 2336 disable_register_stack_guard(); 2337 } 2338 2339 void JavaThread::enable_stack_red_zone() { 2340 // The base notation is from the stacks point of view, growing downward. 2341 // We need to adjust it to work correctly with guard_memory() 2342 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2343 address base = stack_red_zone_base() - stack_red_zone_size(); 2344 2345 guarantee(base < stack_base(),"Error calculating stack red zone"); 2346 guarantee(base < os::current_stack_pointer(),"Error calculating stack red zone"); 2347 2348 if(!os::guard_memory((char *) base, stack_red_zone_size())) { 2349 warning("Attempt to guard stack red zone failed."); 2350 } 2351 } 2352 2353 void JavaThread::disable_stack_red_zone() { 2354 // The base notation is from the stacks point of view, growing downward. 2355 // We need to adjust it to work correctly with guard_memory() 2356 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2357 address base = stack_red_zone_base() - stack_red_zone_size(); 2358 if (!os::unguard_memory((char *)base, stack_red_zone_size())) { 2359 warning("Attempt to unguard stack red zone failed."); 2360 } 2361 } 2362 2363 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) { 2364 // ignore is there is no stack 2365 if (!has_last_Java_frame()) return; 2366 // traverse the stack frames. Starts from top frame. 2367 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2368 frame* fr = fst.current(); 2369 f(fr, fst.register_map()); 2370 } 2371 } 2372 2373 2374 #ifndef PRODUCT 2375 // Deoptimization 2376 // Function for testing deoptimization 2377 void JavaThread::deoptimize() { 2378 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2379 StackFrameStream fst(this, UseBiasedLocking); 2380 bool deopt = false; // Dump stack only if a deopt actually happens. 2381 bool only_at = strlen(DeoptimizeOnlyAt) > 0; 2382 // Iterate over all frames in the thread and deoptimize 2383 for(; !fst.is_done(); fst.next()) { 2384 if(fst.current()->can_be_deoptimized()) { 2385 2386 if (only_at) { 2387 // Deoptimize only at particular bcis. DeoptimizeOnlyAt 2388 // consists of comma or carriage return separated numbers so 2389 // search for the current bci in that string. 2390 address pc = fst.current()->pc(); 2391 nmethod* nm = (nmethod*) fst.current()->cb(); 2392 ScopeDesc* sd = nm->scope_desc_at( pc); 2393 char buffer[8]; 2394 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci()); 2395 size_t len = strlen(buffer); 2396 const char * found = strstr(DeoptimizeOnlyAt, buffer); 2397 while (found != NULL) { 2398 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') && 2399 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) { 2400 // Check that the bci found is bracketed by terminators. 2401 break; 2402 } 2403 found = strstr(found + 1, buffer); 2404 } 2405 if (!found) { 2406 continue; 2407 } 2408 } 2409 2410 if (DebugDeoptimization && !deopt) { 2411 deopt = true; // One-time only print before deopt 2412 tty->print_cr("[BEFORE Deoptimization]"); 2413 trace_frames(); 2414 trace_stack(); 2415 } 2416 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2417 } 2418 } 2419 2420 if (DebugDeoptimization && deopt) { 2421 tty->print_cr("[AFTER Deoptimization]"); 2422 trace_frames(); 2423 } 2424 } 2425 2426 2427 // Make zombies 2428 void JavaThread::make_zombies() { 2429 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2430 if (fst.current()->can_be_deoptimized()) { 2431 // it is a Java nmethod 2432 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc()); 2433 nm->make_not_entrant(); 2434 } 2435 } 2436 } 2437 #endif // PRODUCT 2438 2439 2440 void JavaThread::deoptimized_wrt_marked_nmethods() { 2441 if (!has_last_Java_frame()) return; 2442 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2443 StackFrameStream fst(this, UseBiasedLocking); 2444 for(; !fst.is_done(); fst.next()) { 2445 if (fst.current()->should_be_deoptimized()) { 2446 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2447 } 2448 } 2449 } 2450 2451 2452 // GC support 2453 static void frame_gc_epilogue(frame* f, const RegisterMap* map) { f->gc_epilogue(); } 2454 2455 void JavaThread::gc_epilogue() { 2456 frames_do(frame_gc_epilogue); 2457 } 2458 2459 2460 static void frame_gc_prologue(frame* f, const RegisterMap* map) { f->gc_prologue(); } 2461 2462 void JavaThread::gc_prologue() { 2463 frames_do(frame_gc_prologue); 2464 } 2465 2466 // If the caller is a NamedThread, then remember, in the current scope, 2467 // the given JavaThread in its _processed_thread field. 2468 class RememberProcessedThread: public StackObj { 2469 NamedThread* _cur_thr; 2470 public: 2471 RememberProcessedThread(JavaThread* jthr) { 2472 Thread* thread = Thread::current(); 2473 if (thread->is_Named_thread()) { 2474 _cur_thr = (NamedThread *)thread; 2475 _cur_thr->set_processed_thread(jthr); 2476 } else { 2477 _cur_thr = NULL; 2478 } 2479 } 2480 2481 ~RememberProcessedThread() { 2482 if (_cur_thr) { 2483 _cur_thr->set_processed_thread(NULL); 2484 } 2485 } 2486 }; 2487 2488 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 2489 // Verify that the deferred card marks have been flushed. 2490 assert(deferred_card_mark().is_empty(), "Should be empty during GC"); 2491 2492 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do 2493 // since there may be more than one thread using each ThreadProfiler. 2494 2495 // Traverse the GCHandles 2496 Thread::oops_do(f, cf); 2497 2498 assert( (!has_last_Java_frame() && java_call_counter() == 0) || 2499 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2500 2501 if (has_last_Java_frame()) { 2502 // Record JavaThread to GC thread 2503 RememberProcessedThread rpt(this); 2504 2505 // Traverse the privileged stack 2506 if (_privileged_stack_top != NULL) { 2507 _privileged_stack_top->oops_do(f); 2508 } 2509 2510 // traverse the registered growable array 2511 if (_array_for_gc != NULL) { 2512 for (int index = 0; index < _array_for_gc->length(); index++) { 2513 f->do_oop(_array_for_gc->adr_at(index)); 2514 } 2515 } 2516 2517 // Traverse the monitor chunks 2518 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2519 chunk->oops_do(f); 2520 } 2521 2522 // Traverse the execution stack 2523 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2524 fst.current()->oops_do(f, cf, fst.register_map()); 2525 } 2526 } 2527 2528 // callee_target is never live across a gc point so NULL it here should 2529 // it still contain a methdOop. 2530 2531 set_callee_target(NULL); 2532 2533 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!"); 2534 // If we have deferred set_locals there might be oops waiting to be 2535 // written 2536 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals(); 2537 if (list != NULL) { 2538 for (int i = 0; i < list->length(); i++) { 2539 list->at(i)->oops_do(f); 2540 } 2541 } 2542 2543 // Traverse instance variables at the end since the GC may be moving things 2544 // around using this function 2545 f->do_oop((oop*) &_threadObj); 2546 f->do_oop((oop*) &_vm_result); 2547 f->do_oop((oop*) &_vm_result_2); 2548 f->do_oop((oop*) &_exception_oop); 2549 f->do_oop((oop*) &_pending_async_exception); 2550 2551 if (jvmti_thread_state() != NULL) { 2552 jvmti_thread_state()->oops_do(f); 2553 } 2554 } 2555 2556 void JavaThread::nmethods_do(CodeBlobClosure* cf) { 2557 Thread::nmethods_do(cf); // (super method is a no-op) 2558 2559 assert( (!has_last_Java_frame() && java_call_counter() == 0) || 2560 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2561 2562 if (has_last_Java_frame()) { 2563 // Traverse the execution stack 2564 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2565 fst.current()->nmethods_do(cf); 2566 } 2567 } 2568 } 2569 2570 // Printing 2571 const char* _get_thread_state_name(JavaThreadState _thread_state) { 2572 switch (_thread_state) { 2573 case _thread_uninitialized: return "_thread_uninitialized"; 2574 case _thread_new: return "_thread_new"; 2575 case _thread_new_trans: return "_thread_new_trans"; 2576 case _thread_in_native: return "_thread_in_native"; 2577 case _thread_in_native_trans: return "_thread_in_native_trans"; 2578 case _thread_in_vm: return "_thread_in_vm"; 2579 case _thread_in_vm_trans: return "_thread_in_vm_trans"; 2580 case _thread_in_Java: return "_thread_in_Java"; 2581 case _thread_in_Java_trans: return "_thread_in_Java_trans"; 2582 case _thread_blocked: return "_thread_blocked"; 2583 case _thread_blocked_trans: return "_thread_blocked_trans"; 2584 default: return "unknown thread state"; 2585 } 2586 } 2587 2588 #ifndef PRODUCT 2589 void JavaThread::print_thread_state_on(outputStream *st) const { 2590 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state)); 2591 }; 2592 void JavaThread::print_thread_state() const { 2593 print_thread_state_on(tty); 2594 }; 2595 #endif // PRODUCT 2596 2597 // Called by Threads::print() for VM_PrintThreads operation 2598 void JavaThread::print_on(outputStream *st) const { 2599 st->print("\"%s\" ", get_thread_name()); 2600 oop thread_oop = threadObj(); 2601 if (thread_oop != NULL && java_lang_Thread::is_daemon(thread_oop)) st->print("daemon "); 2602 Thread::print_on(st); 2603 // print guess for valid stack memory region (assume 4K pages); helps lock debugging 2604 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12)); 2605 if (thread_oop != NULL && JDK_Version::is_gte_jdk15x_version()) { 2606 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop)); 2607 } 2608 #ifndef PRODUCT 2609 print_thread_state_on(st); 2610 _safepoint_state->print_on(st); 2611 #endif // PRODUCT 2612 } 2613 2614 // Called by fatal error handler. The difference between this and 2615 // JavaThread::print() is that we can't grab lock or allocate memory. 2616 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const { 2617 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen)); 2618 oop thread_obj = threadObj(); 2619 if (thread_obj != NULL) { 2620 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon"); 2621 } 2622 st->print(" ["); 2623 st->print("%s", _get_thread_state_name(_thread_state)); 2624 if (osthread()) { 2625 st->print(", id=%d", osthread()->thread_id()); 2626 } 2627 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")", 2628 _stack_base - _stack_size, _stack_base); 2629 st->print("]"); 2630 return; 2631 } 2632 2633 // Verification 2634 2635 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); } 2636 2637 void JavaThread::verify() { 2638 // Verify oops in the thread. 2639 oops_do(&VerifyOopClosure::verify_oop, NULL); 2640 2641 // Verify the stack frames. 2642 frames_do(frame_verify); 2643 } 2644 2645 // CR 6300358 (sub-CR 2137150) 2646 // Most callers of this method assume that it can't return NULL but a 2647 // thread may not have a name whilst it is in the process of attaching to 2648 // the VM - see CR 6412693, and there are places where a JavaThread can be 2649 // seen prior to having it's threadObj set (eg JNI attaching threads and 2650 // if vm exit occurs during initialization). These cases can all be accounted 2651 // for such that this method never returns NULL. 2652 const char* JavaThread::get_thread_name() const { 2653 #ifdef ASSERT 2654 // early safepoints can hit while current thread does not yet have TLS 2655 if (!SafepointSynchronize::is_at_safepoint()) { 2656 Thread *cur = Thread::current(); 2657 if (!(cur->is_Java_thread() && cur == this)) { 2658 // Current JavaThreads are allowed to get their own name without 2659 // the Threads_lock. 2660 assert_locked_or_safepoint(Threads_lock); 2661 } 2662 } 2663 #endif // ASSERT 2664 return get_thread_name_string(); 2665 } 2666 2667 // Returns a non-NULL representation of this thread's name, or a suitable 2668 // descriptive string if there is no set name 2669 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const { 2670 const char* name_str; 2671 oop thread_obj = threadObj(); 2672 if (thread_obj != NULL) { 2673 typeArrayOop name = java_lang_Thread::name(thread_obj); 2674 if (name != NULL) { 2675 if (buf == NULL) { 2676 name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length()); 2677 } 2678 else { 2679 name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length(), buf, buflen); 2680 } 2681 } 2682 else if (is_attaching()) { // workaround for 6412693 - see 6404306 2683 name_str = "<no-name - thread is attaching>"; 2684 } 2685 else { 2686 name_str = Thread::name(); 2687 } 2688 } 2689 else { 2690 name_str = Thread::name(); 2691 } 2692 assert(name_str != NULL, "unexpected NULL thread name"); 2693 return name_str; 2694 } 2695 2696 2697 const char* JavaThread::get_threadgroup_name() const { 2698 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 2699 oop thread_obj = threadObj(); 2700 if (thread_obj != NULL) { 2701 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 2702 if (thread_group != NULL) { 2703 typeArrayOop name = java_lang_ThreadGroup::name(thread_group); 2704 // ThreadGroup.name can be null 2705 if (name != NULL) { 2706 const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length()); 2707 return str; 2708 } 2709 } 2710 } 2711 return NULL; 2712 } 2713 2714 const char* JavaThread::get_parent_name() const { 2715 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 2716 oop thread_obj = threadObj(); 2717 if (thread_obj != NULL) { 2718 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 2719 if (thread_group != NULL) { 2720 oop parent = java_lang_ThreadGroup::parent(thread_group); 2721 if (parent != NULL) { 2722 typeArrayOop name = java_lang_ThreadGroup::name(parent); 2723 // ThreadGroup.name can be null 2724 if (name != NULL) { 2725 const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length()); 2726 return str; 2727 } 2728 } 2729 } 2730 } 2731 return NULL; 2732 } 2733 2734 ThreadPriority JavaThread::java_priority() const { 2735 oop thr_oop = threadObj(); 2736 if (thr_oop == NULL) return NormPriority; // Bootstrapping 2737 ThreadPriority priority = java_lang_Thread::priority(thr_oop); 2738 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check"); 2739 return priority; 2740 } 2741 2742 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) { 2743 2744 assert(Threads_lock->owner() == Thread::current(), "must have threads lock"); 2745 // Link Java Thread object <-> C++ Thread 2746 2747 // Get the C++ thread object (an oop) from the JNI handle (a jthread) 2748 // and put it into a new Handle. The Handle "thread_oop" can then 2749 // be used to pass the C++ thread object to other methods. 2750 2751 // Set the Java level thread object (jthread) field of the 2752 // new thread (a JavaThread *) to C++ thread object using the 2753 // "thread_oop" handle. 2754 2755 // Set the thread field (a JavaThread *) of the 2756 // oop representing the java_lang_Thread to the new thread (a JavaThread *). 2757 2758 Handle thread_oop(Thread::current(), 2759 JNIHandles::resolve_non_null(jni_thread)); 2760 assert(instanceKlass::cast(thread_oop->klass())->is_linked(), 2761 "must be initialized"); 2762 set_threadObj(thread_oop()); 2763 java_lang_Thread::set_thread(thread_oop(), this); 2764 2765 if (prio == NoPriority) { 2766 prio = java_lang_Thread::priority(thread_oop()); 2767 assert(prio != NoPriority, "A valid priority should be present"); 2768 } 2769 2770 // Push the Java priority down to the native thread; needs Threads_lock 2771 Thread::set_priority(this, prio); 2772 2773 // Add the new thread to the Threads list and set it in motion. 2774 // We must have threads lock in order to call Threads::add. 2775 // It is crucial that we do not block before the thread is 2776 // added to the Threads list for if a GC happens, then the java_thread oop 2777 // will not be visited by GC. 2778 Threads::add(this); 2779 } 2780 2781 oop JavaThread::current_park_blocker() { 2782 // Support for JSR-166 locks 2783 oop thread_oop = threadObj(); 2784 if (thread_oop != NULL && 2785 JDK_Version::current().supports_thread_park_blocker()) { 2786 return java_lang_Thread::park_blocker(thread_oop); 2787 } 2788 return NULL; 2789 } 2790 2791 2792 void JavaThread::print_stack_on(outputStream* st) { 2793 if (!has_last_Java_frame()) return; 2794 ResourceMark rm; 2795 HandleMark hm; 2796 2797 RegisterMap reg_map(this); 2798 vframe* start_vf = last_java_vframe(®_map); 2799 int count = 0; 2800 for (vframe* f = start_vf; f; f = f->sender() ) { 2801 if (f->is_java_frame()) { 2802 javaVFrame* jvf = javaVFrame::cast(f); 2803 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci()); 2804 2805 // Print out lock information 2806 if (JavaMonitorsInStackTrace) { 2807 jvf->print_lock_info_on(st, count); 2808 } 2809 } else { 2810 // Ignore non-Java frames 2811 } 2812 2813 // Bail-out case for too deep stacks 2814 count++; 2815 if (MaxJavaStackTraceDepth == count) return; 2816 } 2817 } 2818 2819 2820 // JVMTI PopFrame support 2821 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) { 2822 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments"); 2823 if (in_bytes(size_in_bytes) != 0) { 2824 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes)); 2825 _popframe_preserved_args_size = in_bytes(size_in_bytes); 2826 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size); 2827 } 2828 } 2829 2830 void* JavaThread::popframe_preserved_args() { 2831 return _popframe_preserved_args; 2832 } 2833 2834 ByteSize JavaThread::popframe_preserved_args_size() { 2835 return in_ByteSize(_popframe_preserved_args_size); 2836 } 2837 2838 WordSize JavaThread::popframe_preserved_args_size_in_words() { 2839 int sz = in_bytes(popframe_preserved_args_size()); 2840 assert(sz % wordSize == 0, "argument size must be multiple of wordSize"); 2841 return in_WordSize(sz / wordSize); 2842 } 2843 2844 void JavaThread::popframe_free_preserved_args() { 2845 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice"); 2846 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args); 2847 _popframe_preserved_args = NULL; 2848 _popframe_preserved_args_size = 0; 2849 } 2850 2851 #ifndef PRODUCT 2852 2853 void JavaThread::trace_frames() { 2854 tty->print_cr("[Describe stack]"); 2855 int frame_no = 1; 2856 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2857 tty->print(" %d. ", frame_no++); 2858 fst.current()->print_value_on(tty,this); 2859 tty->cr(); 2860 } 2861 } 2862 2863 class PrintAndVerifyOopClosure: public OopClosure { 2864 protected: 2865 template <class T> inline void do_oop_work(T* p) { 2866 oop obj = oopDesc::load_decode_heap_oop(p); 2867 if (obj == NULL) return; 2868 tty->print(INTPTR_FORMAT ": ", p); 2869 if (obj->is_oop_or_null()) { 2870 if (obj->is_objArray()) { 2871 tty->print_cr("valid objArray: " INTPTR_FORMAT, (oopDesc*) obj); 2872 } else { 2873 obj->print(); 2874 } 2875 } else { 2876 tty->print_cr("invalid oop: " INTPTR_FORMAT, (oopDesc*) obj); 2877 } 2878 tty->cr(); 2879 } 2880 public: 2881 virtual void do_oop(oop* p) { do_oop_work(p); } 2882 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 2883 }; 2884 2885 2886 static void oops_print(frame* f, const RegisterMap *map) { 2887 PrintAndVerifyOopClosure print; 2888 f->print_value(); 2889 f->oops_do(&print, NULL, (RegisterMap*)map); 2890 } 2891 2892 // Print our all the locations that contain oops and whether they are 2893 // valid or not. This useful when trying to find the oldest frame 2894 // where an oop has gone bad since the frame walk is from youngest to 2895 // oldest. 2896 void JavaThread::trace_oops() { 2897 tty->print_cr("[Trace oops]"); 2898 frames_do(oops_print); 2899 } 2900 2901 2902 #ifdef ASSERT 2903 // Print or validate the layout of stack frames 2904 void JavaThread::print_frame_layout(int depth, bool validate_only) { 2905 ResourceMark rm; 2906 PRESERVE_EXCEPTION_MARK; 2907 FrameValues values; 2908 int frame_no = 0; 2909 for(StackFrameStream fst(this, false); !fst.is_done(); fst.next()) { 2910 fst.current()->describe(values, ++frame_no); 2911 if (depth == frame_no) break; 2912 } 2913 if (validate_only) { 2914 values.validate(); 2915 } else { 2916 tty->print_cr("[Describe stack layout]"); 2917 values.print(); 2918 } 2919 } 2920 #endif 2921 2922 void JavaThread::trace_stack_from(vframe* start_vf) { 2923 ResourceMark rm; 2924 int vframe_no = 1; 2925 for (vframe* f = start_vf; f; f = f->sender() ) { 2926 if (f->is_java_frame()) { 2927 javaVFrame::cast(f)->print_activation(vframe_no++); 2928 } else { 2929 f->print(); 2930 } 2931 if (vframe_no > StackPrintLimit) { 2932 tty->print_cr("...<more frames>..."); 2933 return; 2934 } 2935 } 2936 } 2937 2938 2939 void JavaThread::trace_stack() { 2940 if (!has_last_Java_frame()) return; 2941 ResourceMark rm; 2942 HandleMark hm; 2943 RegisterMap reg_map(this); 2944 trace_stack_from(last_java_vframe(®_map)); 2945 } 2946 2947 2948 #endif // PRODUCT 2949 2950 2951 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) { 2952 assert(reg_map != NULL, "a map must be given"); 2953 frame f = last_frame(); 2954 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender() ) { 2955 if (vf->is_java_frame()) return javaVFrame::cast(vf); 2956 } 2957 return NULL; 2958 } 2959 2960 2961 klassOop JavaThread::security_get_caller_class(int depth) { 2962 vframeStream vfst(this); 2963 vfst.security_get_caller_frame(depth); 2964 if (!vfst.at_end()) { 2965 return vfst.method()->method_holder(); 2966 } 2967 return NULL; 2968 } 2969 2970 static void compiler_thread_entry(JavaThread* thread, TRAPS) { 2971 assert(thread->is_Compiler_thread(), "must be compiler thread"); 2972 CompileBroker::compiler_thread_loop(); 2973 } 2974 2975 // Create a CompilerThread 2976 CompilerThread::CompilerThread(CompileQueue* queue, CompilerCounters* counters) 2977 : JavaThread(&compiler_thread_entry) { 2978 _env = NULL; 2979 _log = NULL; 2980 _task = NULL; 2981 _queue = queue; 2982 _counters = counters; 2983 _buffer_blob = NULL; 2984 _scanned_nmethod = NULL; 2985 2986 #ifndef PRODUCT 2987 _ideal_graph_printer = NULL; 2988 #endif 2989 } 2990 2991 void CompilerThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 2992 JavaThread::oops_do(f, cf); 2993 if (_scanned_nmethod != NULL && cf != NULL) { 2994 // Safepoints can occur when the sweeper is scanning an nmethod so 2995 // process it here to make sure it isn't unloaded in the middle of 2996 // a scan. 2997 cf->do_code_blob(_scanned_nmethod); 2998 } 2999 } 3000 3001 // ======= Threads ======== 3002 3003 // The Threads class links together all active threads, and provides 3004 // operations over all threads. It is protected by its own Mutex 3005 // lock, which is also used in other contexts to protect thread 3006 // operations from having the thread being operated on from exiting 3007 // and going away unexpectedly (e.g., safepoint synchronization) 3008 3009 JavaThread* Threads::_thread_list = NULL; 3010 int Threads::_number_of_threads = 0; 3011 int Threads::_number_of_non_daemon_threads = 0; 3012 int Threads::_return_code = 0; 3013 size_t JavaThread::_stack_size_at_create = 0; 3014 3015 // All JavaThreads 3016 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next()) 3017 3018 void os_stream(); 3019 3020 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system) 3021 void Threads::threads_do(ThreadClosure* tc) { 3022 assert_locked_or_safepoint(Threads_lock); 3023 // ALL_JAVA_THREADS iterates through all JavaThreads 3024 ALL_JAVA_THREADS(p) { 3025 tc->do_thread(p); 3026 } 3027 // Someday we could have a table or list of all non-JavaThreads. 3028 // For now, just manually iterate through them. 3029 tc->do_thread(VMThread::vm_thread()); 3030 Universe::heap()->gc_threads_do(tc); 3031 WatcherThread *wt = WatcherThread::watcher_thread(); 3032 // Strictly speaking, the following NULL check isn't sufficient to make sure 3033 // the data for WatcherThread is still valid upon being examined. However, 3034 // considering that WatchThread terminates when the VM is on the way to 3035 // exit at safepoint, the chance of the above is extremely small. The right 3036 // way to prevent termination of WatcherThread would be to acquire 3037 // Terminator_lock, but we can't do that without violating the lock rank 3038 // checking in some cases. 3039 if (wt != NULL) 3040 tc->do_thread(wt); 3041 3042 // If CompilerThreads ever become non-JavaThreads, add them here 3043 } 3044 3045 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) { 3046 3047 extern void JDK_Version_init(); 3048 3049 // Check version 3050 if (!is_supported_jni_version(args->version)) return JNI_EVERSION; 3051 3052 // Initialize the output stream module 3053 ostream_init(); 3054 3055 // Process java launcher properties. 3056 Arguments::process_sun_java_launcher_properties(args); 3057 3058 // Initialize the os module before using TLS 3059 os::init(); 3060 3061 // Initialize system properties. 3062 Arguments::init_system_properties(); 3063 3064 // So that JDK version can be used as a discrimintor when parsing arguments 3065 JDK_Version_init(); 3066 3067 // Update/Initialize System properties after JDK version number is known 3068 Arguments::init_version_specific_system_properties(); 3069 3070 // Parse arguments 3071 jint parse_result = Arguments::parse(args); 3072 if (parse_result != JNI_OK) return parse_result; 3073 3074 if (PauseAtStartup) { 3075 os::pause(); 3076 } 3077 3078 HS_DTRACE_PROBE(hotspot, vm__init__begin); 3079 3080 // Record VM creation timing statistics 3081 TraceVmCreationTime create_vm_timer; 3082 create_vm_timer.start(); 3083 3084 // Timing (must come after argument parsing) 3085 TraceTime timer("Create VM", TraceStartupTime); 3086 3087 // Initialize the os module after parsing the args 3088 jint os_init_2_result = os::init_2(); 3089 if (os_init_2_result != JNI_OK) return os_init_2_result; 3090 3091 // Initialize output stream logging 3092 ostream_init_log(); 3093 3094 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad 3095 // Must be before create_vm_init_agents() 3096 if (Arguments::init_libraries_at_startup()) { 3097 convert_vm_init_libraries_to_agents(); 3098 } 3099 3100 // Launch -agentlib/-agentpath and converted -Xrun agents 3101 if (Arguments::init_agents_at_startup()) { 3102 create_vm_init_agents(); 3103 } 3104 3105 // Initialize Threads state 3106 _thread_list = NULL; 3107 _number_of_threads = 0; 3108 _number_of_non_daemon_threads = 0; 3109 3110 // Initialize TLS 3111 ThreadLocalStorage::init(); 3112 3113 // Initialize global data structures and create system classes in heap 3114 vm_init_globals(); 3115 3116 // Attach the main thread to this os thread 3117 JavaThread* main_thread = new JavaThread(); 3118 main_thread->set_thread_state(_thread_in_vm); 3119 // must do this before set_active_handles and initialize_thread_local_storage 3120 // Note: on solaris initialize_thread_local_storage() will (indirectly) 3121 // change the stack size recorded here to one based on the java thread 3122 // stacksize. This adjusted size is what is used to figure the placement 3123 // of the guard pages. 3124 main_thread->record_stack_base_and_size(); 3125 main_thread->initialize_thread_local_storage(); 3126 3127 main_thread->set_active_handles(JNIHandleBlock::allocate_block()); 3128 3129 if (!main_thread->set_as_starting_thread()) { 3130 vm_shutdown_during_initialization( 3131 "Failed necessary internal allocation. Out of swap space"); 3132 delete main_thread; 3133 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3134 return JNI_ENOMEM; 3135 } 3136 3137 // Enable guard page *after* os::create_main_thread(), otherwise it would 3138 // crash Linux VM, see notes in os_linux.cpp. 3139 main_thread->create_stack_guard_pages(); 3140 3141 // Initialize Java-Level synchronization subsystem 3142 ObjectMonitor::Initialize() ; 3143 3144 // Initialize global modules 3145 jint status = init_globals(); 3146 if (status != JNI_OK) { 3147 delete main_thread; 3148 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3149 return status; 3150 } 3151 3152 // Should be done after the heap is fully created 3153 main_thread->cache_global_variables(); 3154 3155 HandleMark hm; 3156 3157 { MutexLocker mu(Threads_lock); 3158 Threads::add(main_thread); 3159 } 3160 3161 // Any JVMTI raw monitors entered in onload will transition into 3162 // real raw monitor. VM is setup enough here for raw monitor enter. 3163 JvmtiExport::transition_pending_onload_raw_monitors(); 3164 3165 if (VerifyBeforeGC && 3166 Universe::heap()->total_collections() >= VerifyGCStartAt) { 3167 Universe::heap()->prepare_for_verify(); 3168 Universe::verify(); // make sure we're starting with a clean slate 3169 } 3170 3171 // Create the VMThread 3172 { TraceTime timer("Start VMThread", TraceStartupTime); 3173 VMThread::create(); 3174 Thread* vmthread = VMThread::vm_thread(); 3175 3176 if (!os::create_thread(vmthread, os::vm_thread)) 3177 vm_exit_during_initialization("Cannot create VM thread. Out of system resources."); 3178 3179 // Wait for the VM thread to become ready, and VMThread::run to initialize 3180 // Monitors can have spurious returns, must always check another state flag 3181 { 3182 MutexLocker ml(Notify_lock); 3183 os::start_thread(vmthread); 3184 while (vmthread->active_handles() == NULL) { 3185 Notify_lock->wait(); 3186 } 3187 } 3188 } 3189 3190 assert (Universe::is_fully_initialized(), "not initialized"); 3191 EXCEPTION_MARK; 3192 3193 // At this point, the Universe is initialized, but we have not executed 3194 // any byte code. Now is a good time (the only time) to dump out the 3195 // internal state of the JVM for sharing. 3196 3197 if (DumpSharedSpaces) { 3198 Universe::heap()->preload_and_dump(CHECK_0); 3199 ShouldNotReachHere(); 3200 } 3201 3202 // Always call even when there are not JVMTI environments yet, since environments 3203 // may be attached late and JVMTI must track phases of VM execution 3204 JvmtiExport::enter_start_phase(); 3205 3206 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3207 JvmtiExport::post_vm_start(); 3208 3209 { 3210 TraceTime timer("Initialize java.lang classes", TraceStartupTime); 3211 3212 if (EagerXrunInit && Arguments::init_libraries_at_startup()) { 3213 create_vm_init_libraries(); 3214 } 3215 3216 if (InitializeJavaLangString) { 3217 initialize_class(vmSymbols::java_lang_String(), CHECK_0); 3218 } else { 3219 warning("java.lang.String not initialized"); 3220 } 3221 3222 if (AggressiveOpts) { 3223 { 3224 // Forcibly initialize java/util/HashMap and mutate the private 3225 // static final "frontCacheEnabled" field before we start creating instances 3226 #ifdef ASSERT 3227 klassOop tmp_k = SystemDictionary::find(vmSymbols::java_util_HashMap(), Handle(), Handle(), CHECK_0); 3228 assert(tmp_k == NULL, "java/util/HashMap should not be loaded yet"); 3229 #endif 3230 klassOop k_o = SystemDictionary::resolve_or_null(vmSymbols::java_util_HashMap(), Handle(), Handle(), CHECK_0); 3231 KlassHandle k = KlassHandle(THREAD, k_o); 3232 guarantee(k.not_null(), "Must find java/util/HashMap"); 3233 instanceKlassHandle ik = instanceKlassHandle(THREAD, k()); 3234 ik->initialize(CHECK_0); 3235 fieldDescriptor fd; 3236 // Possible we might not find this field; if so, don't break 3237 if (ik->find_local_field(vmSymbols::frontCacheEnabled_name(), vmSymbols::bool_signature(), &fd)) { 3238 k()->java_mirror()->bool_field_put(fd.offset(), true); 3239 } 3240 } 3241 3242 if (UseStringCache) { 3243 // Forcibly initialize java/lang/StringValue and mutate the private 3244 // static final "stringCacheEnabled" field before we start creating instances 3245 klassOop k_o = SystemDictionary::resolve_or_null(vmSymbols::java_lang_StringValue(), Handle(), Handle(), CHECK_0); 3246 // Possible that StringValue isn't present: if so, silently don't break 3247 if (k_o != NULL) { 3248 KlassHandle k = KlassHandle(THREAD, k_o); 3249 instanceKlassHandle ik = instanceKlassHandle(THREAD, k()); 3250 ik->initialize(CHECK_0); 3251 fieldDescriptor fd; 3252 // Possible we might not find this field: if so, silently don't break 3253 if (ik->find_local_field(vmSymbols::stringCacheEnabled_name(), vmSymbols::bool_signature(), &fd)) { 3254 k()->java_mirror()->bool_field_put(fd.offset(), true); 3255 } 3256 } 3257 } 3258 } 3259 3260 // Initialize java_lang.System (needed before creating the thread) 3261 if (InitializeJavaLangSystem) { 3262 initialize_class(vmSymbols::java_lang_System(), CHECK_0); 3263 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK_0); 3264 Handle thread_group = create_initial_thread_group(CHECK_0); 3265 Universe::set_main_thread_group(thread_group()); 3266 initialize_class(vmSymbols::java_lang_Thread(), CHECK_0); 3267 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK_0); 3268 main_thread->set_threadObj(thread_object); 3269 // Set thread status to running since main thread has 3270 // been started and running. 3271 java_lang_Thread::set_thread_status(thread_object, 3272 java_lang_Thread::RUNNABLE); 3273 3274 // The VM preresolve methods to these classes. Make sure that get initialized 3275 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK_0); 3276 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK_0); 3277 // The VM creates & returns objects of this class. Make sure it's initialized. 3278 initialize_class(vmSymbols::java_lang_Class(), CHECK_0); 3279 call_initializeSystemClass(CHECK_0); 3280 } else { 3281 warning("java.lang.System not initialized"); 3282 } 3283 3284 // an instance of OutOfMemory exception has been allocated earlier 3285 if (InitializeJavaLangExceptionsErrors) { 3286 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK_0); 3287 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK_0); 3288 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK_0); 3289 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK_0); 3290 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK_0); 3291 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK_0); 3292 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK_0); 3293 } else { 3294 warning("java.lang.OutOfMemoryError has not been initialized"); 3295 warning("java.lang.NullPointerException has not been initialized"); 3296 warning("java.lang.ClassCastException has not been initialized"); 3297 warning("java.lang.ArrayStoreException has not been initialized"); 3298 warning("java.lang.ArithmeticException has not been initialized"); 3299 warning("java.lang.StackOverflowError has not been initialized"); 3300 } 3301 } 3302 3303 // See : bugid 4211085. 3304 // Background : the static initializer of java.lang.Compiler tries to read 3305 // property"java.compiler" and read & write property "java.vm.info". 3306 // When a security manager is installed through the command line 3307 // option "-Djava.security.manager", the above properties are not 3308 // readable and the static initializer for java.lang.Compiler fails 3309 // resulting in a NoClassDefFoundError. This can happen in any 3310 // user code which calls methods in java.lang.Compiler. 3311 // Hack : the hack is to pre-load and initialize this class, so that only 3312 // system domains are on the stack when the properties are read. 3313 // Currently even the AWT code has calls to methods in java.lang.Compiler. 3314 // On the classic VM, java.lang.Compiler is loaded very early to load the JIT. 3315 // Future Fix : the best fix is to grant everyone permissions to read "java.compiler" and 3316 // read and write"java.vm.info" in the default policy file. See bugid 4211383 3317 // Once that is done, we should remove this hack. 3318 initialize_class(vmSymbols::java_lang_Compiler(), CHECK_0); 3319 3320 // More hackery - the static initializer of java.lang.Compiler adds the string "nojit" to 3321 // the java.vm.info property if no jit gets loaded through java.lang.Compiler (the hotspot 3322 // compiler does not get loaded through java.lang.Compiler). "java -version" with the 3323 // hotspot vm says "nojit" all the time which is confusing. So, we reset it here. 3324 // This should also be taken out as soon as 4211383 gets fixed. 3325 reset_vm_info_property(CHECK_0); 3326 3327 quicken_jni_functions(); 3328 3329 // Set flag that basic initialization has completed. Used by exceptions and various 3330 // debug stuff, that does not work until all basic classes have been initialized. 3331 set_init_completed(); 3332 3333 HS_DTRACE_PROBE(hotspot, vm__init__end); 3334 3335 // record VM initialization completion time 3336 Management::record_vm_init_completed(); 3337 3338 // Compute system loader. Note that this has to occur after set_init_completed, since 3339 // valid exceptions may be thrown in the process. 3340 // Note that we do not use CHECK_0 here since we are inside an EXCEPTION_MARK and 3341 // set_init_completed has just been called, causing exceptions not to be shortcut 3342 // anymore. We call vm_exit_during_initialization directly instead. 3343 SystemDictionary::compute_java_system_loader(THREAD); 3344 if (HAS_PENDING_EXCEPTION) { 3345 vm_exit_during_initialization(Handle(THREAD, PENDING_EXCEPTION)); 3346 } 3347 3348 #ifndef SERIALGC 3349 // Support for ConcurrentMarkSweep. This should be cleaned up 3350 // and better encapsulated. The ugly nested if test would go away 3351 // once things are properly refactored. XXX YSR 3352 if (UseConcMarkSweepGC || UseG1GC) { 3353 if (UseConcMarkSweepGC) { 3354 ConcurrentMarkSweepThread::makeSurrogateLockerThread(THREAD); 3355 } else { 3356 ConcurrentMarkThread::makeSurrogateLockerThread(THREAD); 3357 } 3358 if (HAS_PENDING_EXCEPTION) { 3359 vm_exit_during_initialization(Handle(THREAD, PENDING_EXCEPTION)); 3360 } 3361 } 3362 #endif // SERIALGC 3363 3364 // Always call even when there are not JVMTI environments yet, since environments 3365 // may be attached late and JVMTI must track phases of VM execution 3366 JvmtiExport::enter_live_phase(); 3367 3368 // Signal Dispatcher needs to be started before VMInit event is posted 3369 os::signal_init(); 3370 3371 // Start Attach Listener if +StartAttachListener or it can't be started lazily 3372 if (!DisableAttachMechanism) { 3373 if (StartAttachListener || AttachListener::init_at_startup()) { 3374 AttachListener::init(); 3375 } 3376 } 3377 3378 // Launch -Xrun agents 3379 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP 3380 // back-end can launch with -Xdebug -Xrunjdwp. 3381 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) { 3382 create_vm_init_libraries(); 3383 } 3384 3385 // Notify JVMTI agents that VM initialization is complete - nop if no agents. 3386 JvmtiExport::post_vm_initialized(); 3387 3388 if (CleanChunkPoolAsync) { 3389 Chunk::start_chunk_pool_cleaner_task(); 3390 } 3391 3392 // initialize compiler(s) 3393 CompileBroker::compilation_init(); 3394 3395 Management::initialize(THREAD); 3396 if (HAS_PENDING_EXCEPTION) { 3397 // management agent fails to start possibly due to 3398 // configuration problem and is responsible for printing 3399 // stack trace if appropriate. Simply exit VM. 3400 vm_exit(1); 3401 } 3402 3403 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true); 3404 if (Arguments::has_alloc_profile()) AllocationProfiler::engage(); 3405 if (MemProfiling) MemProfiler::engage(); 3406 StatSampler::engage(); 3407 if (CheckJNICalls) JniPeriodicChecker::engage(); 3408 3409 BiasedLocking::init(); 3410 3411 if (JDK_Version::current().post_vm_init_hook_enabled()) { 3412 call_postVMInitHook(THREAD); 3413 // The Java side of PostVMInitHook.run must deal with all 3414 // exceptions and provide means of diagnosis. 3415 if (HAS_PENDING_EXCEPTION) { 3416 CLEAR_PENDING_EXCEPTION; 3417 } 3418 } 3419 3420 // Start up the WatcherThread if there are any periodic tasks 3421 // NOTE: All PeriodicTasks should be registered by now. If they 3422 // aren't, late joiners might appear to start slowly (we might 3423 // take a while to process their first tick). 3424 if (PeriodicTask::num_tasks() > 0) { 3425 WatcherThread::start(); 3426 } 3427 3428 // Give os specific code one last chance to start 3429 os::init_3(); 3430 3431 create_vm_timer.end(); 3432 return JNI_OK; 3433 } 3434 3435 // type for the Agent_OnLoad and JVM_OnLoad entry points 3436 extern "C" { 3437 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *); 3438 } 3439 // Find a command line agent library and return its entry point for 3440 // -agentlib: -agentpath: -Xrun 3441 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array. 3442 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, const char *on_load_symbols[], size_t num_symbol_entries) { 3443 OnLoadEntry_t on_load_entry = NULL; 3444 void *library = agent->os_lib(); // check if we have looked it up before 3445 3446 if (library == NULL) { 3447 char buffer[JVM_MAXPATHLEN]; 3448 char ebuf[1024]; 3449 const char *name = agent->name(); 3450 const char *msg = "Could not find agent library "; 3451 3452 if (agent->is_absolute_path()) { 3453 library = os::dll_load(name, ebuf, sizeof ebuf); 3454 if (library == NULL) { 3455 const char *sub_msg = " in absolute path, with error: "; 3456 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 3457 char *buf = NEW_C_HEAP_ARRAY(char, len); 3458 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 3459 // If we can't find the agent, exit. 3460 vm_exit_during_initialization(buf, NULL); 3461 FREE_C_HEAP_ARRAY(char, buf); 3462 } 3463 } else { 3464 // Try to load the agent from the standard dll directory 3465 os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(), name); 3466 library = os::dll_load(buffer, ebuf, sizeof ebuf); 3467 #ifdef KERNEL 3468 // Download instrument dll 3469 if (library == NULL && strcmp(name, "instrument") == 0) { 3470 char *props = Arguments::get_kernel_properties(); 3471 char *home = Arguments::get_java_home(); 3472 const char *fmt = "%s/bin/java %s -Dkernel.background.download=false" 3473 " sun.jkernel.DownloadManager -download client_jvm"; 3474 size_t length = strlen(props) + strlen(home) + strlen(fmt) + 1; 3475 char *cmd = NEW_C_HEAP_ARRAY(char, length); 3476 jio_snprintf(cmd, length, fmt, home, props); 3477 int status = os::fork_and_exec(cmd); 3478 FreeHeap(props); 3479 if (status == -1) { 3480 warning(cmd); 3481 vm_exit_during_initialization("fork_and_exec failed: %s", 3482 strerror(errno)); 3483 } 3484 FREE_C_HEAP_ARRAY(char, cmd); 3485 // when this comes back the instrument.dll should be where it belongs. 3486 library = os::dll_load(buffer, ebuf, sizeof ebuf); 3487 } 3488 #endif // KERNEL 3489 if (library == NULL) { // Try the local directory 3490 char ns[1] = {0}; 3491 os::dll_build_name(buffer, sizeof(buffer), ns, name); 3492 library = os::dll_load(buffer, ebuf, sizeof ebuf); 3493 if (library == NULL) { 3494 const char *sub_msg = " on the library path, with error: "; 3495 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 3496 char *buf = NEW_C_HEAP_ARRAY(char, len); 3497 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 3498 // If we can't find the agent, exit. 3499 vm_exit_during_initialization(buf, NULL); 3500 FREE_C_HEAP_ARRAY(char, buf); 3501 } 3502 } 3503 } 3504 agent->set_os_lib(library); 3505 } 3506 3507 // Find the OnLoad function. 3508 for (size_t symbol_index = 0; symbol_index < num_symbol_entries; symbol_index++) { 3509 on_load_entry = CAST_TO_FN_PTR(OnLoadEntry_t, os::dll_lookup(library, on_load_symbols[symbol_index])); 3510 if (on_load_entry != NULL) break; 3511 } 3512 return on_load_entry; 3513 } 3514 3515 // Find the JVM_OnLoad entry point 3516 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) { 3517 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS; 3518 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 3519 } 3520 3521 // Find the Agent_OnLoad entry point 3522 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) { 3523 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS; 3524 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 3525 } 3526 3527 // For backwards compatibility with -Xrun 3528 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be 3529 // treated like -agentpath: 3530 // Must be called before agent libraries are created 3531 void Threads::convert_vm_init_libraries_to_agents() { 3532 AgentLibrary* agent; 3533 AgentLibrary* next; 3534 3535 for (agent = Arguments::libraries(); agent != NULL; agent = next) { 3536 next = agent->next(); // cache the next agent now as this agent may get moved off this list 3537 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 3538 3539 // If there is an JVM_OnLoad function it will get called later, 3540 // otherwise see if there is an Agent_OnLoad 3541 if (on_load_entry == NULL) { 3542 on_load_entry = lookup_agent_on_load(agent); 3543 if (on_load_entry != NULL) { 3544 // switch it to the agent list -- so that Agent_OnLoad will be called, 3545 // JVM_OnLoad won't be attempted and Agent_OnUnload will 3546 Arguments::convert_library_to_agent(agent); 3547 } else { 3548 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name()); 3549 } 3550 } 3551 } 3552 } 3553 3554 // Create agents for -agentlib: -agentpath: and converted -Xrun 3555 // Invokes Agent_OnLoad 3556 // Called very early -- before JavaThreads exist 3557 void Threads::create_vm_init_agents() { 3558 extern struct JavaVM_ main_vm; 3559 AgentLibrary* agent; 3560 3561 JvmtiExport::enter_onload_phase(); 3562 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 3563 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent); 3564 3565 if (on_load_entry != NULL) { 3566 // Invoke the Agent_OnLoad function 3567 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 3568 if (err != JNI_OK) { 3569 vm_exit_during_initialization("agent library failed to init", agent->name()); 3570 } 3571 } else { 3572 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name()); 3573 } 3574 } 3575 JvmtiExport::enter_primordial_phase(); 3576 } 3577 3578 extern "C" { 3579 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *); 3580 } 3581 3582 void Threads::shutdown_vm_agents() { 3583 // Send any Agent_OnUnload notifications 3584 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS; 3585 extern struct JavaVM_ main_vm; 3586 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 3587 3588 // Find the Agent_OnUnload function. 3589 for (uint symbol_index = 0; symbol_index < ARRAY_SIZE(on_unload_symbols); symbol_index++) { 3590 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t, 3591 os::dll_lookup(agent->os_lib(), on_unload_symbols[symbol_index])); 3592 3593 // Invoke the Agent_OnUnload function 3594 if (unload_entry != NULL) { 3595 JavaThread* thread = JavaThread::current(); 3596 ThreadToNativeFromVM ttn(thread); 3597 HandleMark hm(thread); 3598 (*unload_entry)(&main_vm); 3599 break; 3600 } 3601 } 3602 } 3603 } 3604 3605 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries 3606 // Invokes JVM_OnLoad 3607 void Threads::create_vm_init_libraries() { 3608 extern struct JavaVM_ main_vm; 3609 AgentLibrary* agent; 3610 3611 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) { 3612 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 3613 3614 if (on_load_entry != NULL) { 3615 // Invoke the JVM_OnLoad function 3616 JavaThread* thread = JavaThread::current(); 3617 ThreadToNativeFromVM ttn(thread); 3618 HandleMark hm(thread); 3619 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 3620 if (err != JNI_OK) { 3621 vm_exit_during_initialization("-Xrun library failed to init", agent->name()); 3622 } 3623 } else { 3624 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name()); 3625 } 3626 } 3627 } 3628 3629 // Last thread running calls java.lang.Shutdown.shutdown() 3630 void JavaThread::invoke_shutdown_hooks() { 3631 HandleMark hm(this); 3632 3633 // We could get here with a pending exception, if so clear it now. 3634 if (this->has_pending_exception()) { 3635 this->clear_pending_exception(); 3636 } 3637 3638 EXCEPTION_MARK; 3639 klassOop k = 3640 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(), 3641 THREAD); 3642 if (k != NULL) { 3643 // SystemDictionary::resolve_or_null will return null if there was 3644 // an exception. If we cannot load the Shutdown class, just don't 3645 // call Shutdown.shutdown() at all. This will mean the shutdown hooks 3646 // and finalizers (if runFinalizersOnExit is set) won't be run. 3647 // Note that if a shutdown hook was registered or runFinalizersOnExit 3648 // was called, the Shutdown class would have already been loaded 3649 // (Runtime.addShutdownHook and runFinalizersOnExit will load it). 3650 instanceKlassHandle shutdown_klass (THREAD, k); 3651 JavaValue result(T_VOID); 3652 JavaCalls::call_static(&result, 3653 shutdown_klass, 3654 vmSymbols::shutdown_method_name(), 3655 vmSymbols::void_method_signature(), 3656 THREAD); 3657 } 3658 CLEAR_PENDING_EXCEPTION; 3659 } 3660 3661 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when 3662 // the program falls off the end of main(). Another VM exit path is through 3663 // vm_exit() when the program calls System.exit() to return a value or when 3664 // there is a serious error in VM. The two shutdown paths are not exactly 3665 // the same, but they share Shutdown.shutdown() at Java level and before_exit() 3666 // and VM_Exit op at VM level. 3667 // 3668 // Shutdown sequence: 3669 // + Wait until we are the last non-daemon thread to execute 3670 // <-- every thing is still working at this moment --> 3671 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level 3672 // shutdown hooks, run finalizers if finalization-on-exit 3673 // + Call before_exit(), prepare for VM exit 3674 // > run VM level shutdown hooks (they are registered through JVM_OnExit(), 3675 // currently the only user of this mechanism is File.deleteOnExit()) 3676 // > stop flat profiler, StatSampler, watcher thread, CMS threads, 3677 // post thread end and vm death events to JVMTI, 3678 // stop signal thread 3679 // + Call JavaThread::exit(), it will: 3680 // > release JNI handle blocks, remove stack guard pages 3681 // > remove this thread from Threads list 3682 // <-- no more Java code from this thread after this point --> 3683 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop 3684 // the compiler threads at safepoint 3685 // <-- do not use anything that could get blocked by Safepoint --> 3686 // + Disable tracing at JNI/JVM barriers 3687 // + Set _vm_exited flag for threads that are still running native code 3688 // + Delete this thread 3689 // + Call exit_globals() 3690 // > deletes tty 3691 // > deletes PerfMemory resources 3692 // + Return to caller 3693 3694 bool Threads::destroy_vm() { 3695 JavaThread* thread = JavaThread::current(); 3696 3697 // Wait until we are the last non-daemon thread to execute 3698 { MutexLocker nu(Threads_lock); 3699 while (Threads::number_of_non_daemon_threads() > 1 ) 3700 // This wait should make safepoint checks, wait without a timeout, 3701 // and wait as a suspend-equivalent condition. 3702 // 3703 // Note: If the FlatProfiler is running and this thread is waiting 3704 // for another non-daemon thread to finish, then the FlatProfiler 3705 // is waiting for the external suspend request on this thread to 3706 // complete. wait_for_ext_suspend_completion() will eventually 3707 // timeout, but that takes time. Making this wait a suspend- 3708 // equivalent condition solves that timeout problem. 3709 // 3710 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 3711 Mutex::_as_suspend_equivalent_flag); 3712 } 3713 3714 // Hang forever on exit if we are reporting an error. 3715 if (ShowMessageBoxOnError && is_error_reported()) { 3716 os::infinite_sleep(); 3717 } 3718 os::wait_for_keypress_at_exit(); 3719 3720 if (JDK_Version::is_jdk12x_version()) { 3721 // We are the last thread running, so check if finalizers should be run. 3722 // For 1.3 or later this is done in thread->invoke_shutdown_hooks() 3723 HandleMark rm(thread); 3724 Universe::run_finalizers_on_exit(); 3725 } else { 3726 // run Java level shutdown hooks 3727 thread->invoke_shutdown_hooks(); 3728 } 3729 3730 before_exit(thread); 3731 3732 thread->exit(true); 3733 3734 // Stop VM thread. 3735 { 3736 // 4945125 The vm thread comes to a safepoint during exit. 3737 // GC vm_operations can get caught at the safepoint, and the 3738 // heap is unparseable if they are caught. Grab the Heap_lock 3739 // to prevent this. The GC vm_operations will not be able to 3740 // queue until after the vm thread is dead. 3741 // After this point, we'll never emerge out of the safepoint before 3742 // the VM exits, so concurrent GC threads do not need to be explicitly 3743 // stopped; they remain inactive until the process exits. 3744 // Note: some concurrent G1 threads may be running during a safepoint, 3745 // but these will not be accessing the heap, just some G1-specific side 3746 // data structures that are not accessed by any other threads but them 3747 // after this point in a terminal safepoint. 3748 3749 MutexLocker ml(Heap_lock); 3750 3751 VMThread::wait_for_vm_thread_exit(); 3752 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint"); 3753 VMThread::destroy(); 3754 } 3755 3756 // clean up ideal graph printers 3757 #if defined(COMPILER2) && !defined(PRODUCT) 3758 IdealGraphPrinter::clean_up(); 3759 #endif 3760 3761 // Now, all Java threads are gone except daemon threads. Daemon threads 3762 // running Java code or in VM are stopped by the Safepoint. However, 3763 // daemon threads executing native code are still running. But they 3764 // will be stopped at native=>Java/VM barriers. Note that we can't 3765 // simply kill or suspend them, as it is inherently deadlock-prone. 3766 3767 #ifndef PRODUCT 3768 // disable function tracing at JNI/JVM barriers 3769 TraceJNICalls = false; 3770 TraceJVMCalls = false; 3771 TraceRuntimeCalls = false; 3772 #endif 3773 3774 VM_Exit::set_vm_exited(); 3775 3776 notify_vm_shutdown(); 3777 3778 delete thread; 3779 3780 // exit_globals() will delete tty 3781 exit_globals(); 3782 3783 return true; 3784 } 3785 3786 3787 jboolean Threads::is_supported_jni_version_including_1_1(jint version) { 3788 if (version == JNI_VERSION_1_1) return JNI_TRUE; 3789 return is_supported_jni_version(version); 3790 } 3791 3792 3793 jboolean Threads::is_supported_jni_version(jint version) { 3794 if (version == JNI_VERSION_1_2) return JNI_TRUE; 3795 if (version == JNI_VERSION_1_4) return JNI_TRUE; 3796 if (version == JNI_VERSION_1_6) return JNI_TRUE; 3797 return JNI_FALSE; 3798 } 3799 3800 3801 void Threads::add(JavaThread* p, bool force_daemon) { 3802 // The threads lock must be owned at this point 3803 assert_locked_or_safepoint(Threads_lock); 3804 3805 // See the comment for this method in thread.hpp for its purpose and 3806 // why it is called here. 3807 p->initialize_queues(); 3808 p->set_next(_thread_list); 3809 _thread_list = p; 3810 _number_of_threads++; 3811 oop threadObj = p->threadObj(); 3812 bool daemon = true; 3813 // Bootstrapping problem: threadObj can be null for initial 3814 // JavaThread (or for threads attached via JNI) 3815 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) { 3816 _number_of_non_daemon_threads++; 3817 daemon = false; 3818 } 3819 3820 ThreadService::add_thread(p, daemon); 3821 3822 // Possible GC point. 3823 Events::log("Thread added: " INTPTR_FORMAT, p); 3824 } 3825 3826 void Threads::remove(JavaThread* p) { 3827 // Extra scope needed for Thread_lock, so we can check 3828 // that we do not remove thread without safepoint code notice 3829 { MutexLocker ml(Threads_lock); 3830 3831 assert(includes(p), "p must be present"); 3832 3833 JavaThread* current = _thread_list; 3834 JavaThread* prev = NULL; 3835 3836 while (current != p) { 3837 prev = current; 3838 current = current->next(); 3839 } 3840 3841 if (prev) { 3842 prev->set_next(current->next()); 3843 } else { 3844 _thread_list = p->next(); 3845 } 3846 _number_of_threads--; 3847 oop threadObj = p->threadObj(); 3848 bool daemon = true; 3849 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) { 3850 _number_of_non_daemon_threads--; 3851 daemon = false; 3852 3853 // Only one thread left, do a notify on the Threads_lock so a thread waiting 3854 // on destroy_vm will wake up. 3855 if (number_of_non_daemon_threads() == 1) 3856 Threads_lock->notify_all(); 3857 } 3858 ThreadService::remove_thread(p, daemon); 3859 3860 // Make sure that safepoint code disregard this thread. This is needed since 3861 // the thread might mess around with locks after this point. This can cause it 3862 // to do callbacks into the safepoint code. However, the safepoint code is not aware 3863 // of this thread since it is removed from the queue. 3864 p->set_terminated_value(); 3865 } // unlock Threads_lock 3866 3867 // Since Events::log uses a lock, we grab it outside the Threads_lock 3868 Events::log("Thread exited: " INTPTR_FORMAT, p); 3869 } 3870 3871 // Threads_lock must be held when this is called (or must be called during a safepoint) 3872 bool Threads::includes(JavaThread* p) { 3873 assert(Threads_lock->is_locked(), "sanity check"); 3874 ALL_JAVA_THREADS(q) { 3875 if (q == p ) { 3876 return true; 3877 } 3878 } 3879 return false; 3880 } 3881 3882 // Operations on the Threads list for GC. These are not explicitly locked, 3883 // but the garbage collector must provide a safe context for them to run. 3884 // In particular, these things should never be called when the Threads_lock 3885 // is held by some other thread. (Note: the Safepoint abstraction also 3886 // uses the Threads_lock to gurantee this property. It also makes sure that 3887 // all threads gets blocked when exiting or starting). 3888 3889 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) { 3890 ALL_JAVA_THREADS(p) { 3891 p->oops_do(f, cf); 3892 } 3893 VMThread::vm_thread()->oops_do(f, cf); 3894 } 3895 3896 void Threads::possibly_parallel_oops_do(OopClosure* f, CodeBlobClosure* cf) { 3897 // Introduce a mechanism allowing parallel threads to claim threads as 3898 // root groups. Overhead should be small enough to use all the time, 3899 // even in sequential code. 3900 SharedHeap* sh = SharedHeap::heap(); 3901 bool is_par = (sh->n_par_threads() > 0); 3902 int cp = SharedHeap::heap()->strong_roots_parity(); 3903 ALL_JAVA_THREADS(p) { 3904 if (p->claim_oops_do(is_par, cp)) { 3905 p->oops_do(f, cf); 3906 } 3907 } 3908 VMThread* vmt = VMThread::vm_thread(); 3909 if (vmt->claim_oops_do(is_par, cp)) { 3910 vmt->oops_do(f, cf); 3911 } 3912 } 3913 3914 #ifndef SERIALGC 3915 // Used by ParallelScavenge 3916 void Threads::create_thread_roots_tasks(GCTaskQueue* q) { 3917 ALL_JAVA_THREADS(p) { 3918 q->enqueue(new ThreadRootsTask(p)); 3919 } 3920 q->enqueue(new ThreadRootsTask(VMThread::vm_thread())); 3921 } 3922 3923 // Used by Parallel Old 3924 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) { 3925 ALL_JAVA_THREADS(p) { 3926 q->enqueue(new ThreadRootsMarkingTask(p)); 3927 } 3928 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread())); 3929 } 3930 #endif // SERIALGC 3931 3932 void Threads::nmethods_do(CodeBlobClosure* cf) { 3933 ALL_JAVA_THREADS(p) { 3934 p->nmethods_do(cf); 3935 } 3936 VMThread::vm_thread()->nmethods_do(cf); 3937 } 3938 3939 void Threads::gc_epilogue() { 3940 ALL_JAVA_THREADS(p) { 3941 p->gc_epilogue(); 3942 } 3943 } 3944 3945 void Threads::gc_prologue() { 3946 ALL_JAVA_THREADS(p) { 3947 p->gc_prologue(); 3948 } 3949 } 3950 3951 void Threads::deoptimized_wrt_marked_nmethods() { 3952 ALL_JAVA_THREADS(p) { 3953 p->deoptimized_wrt_marked_nmethods(); 3954 } 3955 } 3956 3957 3958 // Get count Java threads that are waiting to enter the specified monitor. 3959 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count, 3960 address monitor, bool doLock) { 3961 assert(doLock || SafepointSynchronize::is_at_safepoint(), 3962 "must grab Threads_lock or be at safepoint"); 3963 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count); 3964 3965 int i = 0; 3966 { 3967 MutexLockerEx ml(doLock ? Threads_lock : NULL); 3968 ALL_JAVA_THREADS(p) { 3969 if (p->is_Compiler_thread()) continue; 3970 3971 address pending = (address)p->current_pending_monitor(); 3972 if (pending == monitor) { // found a match 3973 if (i < count) result->append(p); // save the first count matches 3974 i++; 3975 } 3976 } 3977 } 3978 return result; 3979 } 3980 3981 3982 JavaThread *Threads::owning_thread_from_monitor_owner(address owner, bool doLock) { 3983 assert(doLock || 3984 Threads_lock->owned_by_self() || 3985 SafepointSynchronize::is_at_safepoint(), 3986 "must grab Threads_lock or be at safepoint"); 3987 3988 // NULL owner means not locked so we can skip the search 3989 if (owner == NULL) return NULL; 3990 3991 { 3992 MutexLockerEx ml(doLock ? Threads_lock : NULL); 3993 ALL_JAVA_THREADS(p) { 3994 // first, see if owner is the address of a Java thread 3995 if (owner == (address)p) return p; 3996 } 3997 } 3998 assert(UseHeavyMonitors == false, "Did not find owning Java thread with UseHeavyMonitors enabled"); 3999 if (UseHeavyMonitors) return NULL; 4000 4001 // 4002 // If we didn't find a matching Java thread and we didn't force use of 4003 // heavyweight monitors, then the owner is the stack address of the 4004 // Lock Word in the owning Java thread's stack. 4005 // 4006 JavaThread* the_owner = NULL; 4007 { 4008 MutexLockerEx ml(doLock ? Threads_lock : NULL); 4009 ALL_JAVA_THREADS(q) { 4010 if (q->is_lock_owned(owner)) { 4011 the_owner = q; 4012 break; 4013 } 4014 } 4015 } 4016 assert(the_owner != NULL, "Did not find owning Java thread for lock word address"); 4017 return the_owner; 4018 } 4019 4020 // Threads::print_on() is called at safepoint by VM_PrintThreads operation. 4021 void Threads::print_on(outputStream* st, bool print_stacks, bool internal_format, bool print_concurrent_locks) { 4022 char buf[32]; 4023 st->print_cr(os::local_time_string(buf, sizeof(buf))); 4024 4025 st->print_cr("Full thread dump %s (%s %s):", 4026 Abstract_VM_Version::vm_name(), 4027 Abstract_VM_Version::vm_release(), 4028 Abstract_VM_Version::vm_info_string() 4029 ); 4030 st->cr(); 4031 4032 #ifndef SERIALGC 4033 // Dump concurrent locks 4034 ConcurrentLocksDump concurrent_locks; 4035 if (print_concurrent_locks) { 4036 concurrent_locks.dump_at_safepoint(); 4037 } 4038 #endif // SERIALGC 4039 4040 ALL_JAVA_THREADS(p) { 4041 ResourceMark rm; 4042 p->print_on(st); 4043 if (print_stacks) { 4044 if (internal_format) { 4045 p->trace_stack(); 4046 } else { 4047 p->print_stack_on(st); 4048 } 4049 } 4050 st->cr(); 4051 #ifndef SERIALGC 4052 if (print_concurrent_locks) { 4053 concurrent_locks.print_locks_on(p, st); 4054 } 4055 #endif // SERIALGC 4056 } 4057 4058 VMThread::vm_thread()->print_on(st); 4059 st->cr(); 4060 Universe::heap()->print_gc_threads_on(st); 4061 WatcherThread* wt = WatcherThread::watcher_thread(); 4062 if (wt != NULL) wt->print_on(st); 4063 st->cr(); 4064 CompileBroker::print_compiler_threads_on(st); 4065 st->flush(); 4066 } 4067 4068 // Threads::print_on_error() is called by fatal error handler. It's possible 4069 // that VM is not at safepoint and/or current thread is inside signal handler. 4070 // Don't print stack trace, as the stack may not be walkable. Don't allocate 4071 // memory (even in resource area), it might deadlock the error handler. 4072 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, int buflen) { 4073 bool found_current = false; 4074 st->print_cr("Java Threads: ( => current thread )"); 4075 ALL_JAVA_THREADS(thread) { 4076 bool is_current = (current == thread); 4077 found_current = found_current || is_current; 4078 4079 st->print("%s", is_current ? "=>" : " "); 4080 4081 st->print(PTR_FORMAT, thread); 4082 st->print(" "); 4083 thread->print_on_error(st, buf, buflen); 4084 st->cr(); 4085 } 4086 st->cr(); 4087 4088 st->print_cr("Other Threads:"); 4089 if (VMThread::vm_thread()) { 4090 bool is_current = (current == VMThread::vm_thread()); 4091 found_current = found_current || is_current; 4092 st->print("%s", current == VMThread::vm_thread() ? "=>" : " "); 4093 4094 st->print(PTR_FORMAT, VMThread::vm_thread()); 4095 st->print(" "); 4096 VMThread::vm_thread()->print_on_error(st, buf, buflen); 4097 st->cr(); 4098 } 4099 WatcherThread* wt = WatcherThread::watcher_thread(); 4100 if (wt != NULL) { 4101 bool is_current = (current == wt); 4102 found_current = found_current || is_current; 4103 st->print("%s", is_current ? "=>" : " "); 4104 4105 st->print(PTR_FORMAT, wt); 4106 st->print(" "); 4107 wt->print_on_error(st, buf, buflen); 4108 st->cr(); 4109 } 4110 if (!found_current) { 4111 st->cr(); 4112 st->print("=>" PTR_FORMAT " (exited) ", current); 4113 current->print_on_error(st, buf, buflen); 4114 st->cr(); 4115 } 4116 } 4117 4118 // Internal SpinLock and Mutex 4119 // Based on ParkEvent 4120 4121 // Ad-hoc mutual exclusion primitives: SpinLock and Mux 4122 // 4123 // We employ SpinLocks _only for low-contention, fixed-length 4124 // short-duration critical sections where we're concerned 4125 // about native mutex_t or HotSpot Mutex:: latency. 4126 // The mux construct provides a spin-then-block mutual exclusion 4127 // mechanism. 4128 // 4129 // Testing has shown that contention on the ListLock guarding gFreeList 4130 // is common. If we implement ListLock as a simple SpinLock it's common 4131 // for the JVM to devolve to yielding with little progress. This is true 4132 // despite the fact that the critical sections protected by ListLock are 4133 // extremely short. 4134 // 4135 // TODO-FIXME: ListLock should be of type SpinLock. 4136 // We should make this a 1st-class type, integrated into the lock 4137 // hierarchy as leaf-locks. Critically, the SpinLock structure 4138 // should have sufficient padding to avoid false-sharing and excessive 4139 // cache-coherency traffic. 4140 4141 4142 typedef volatile int SpinLockT ; 4143 4144 void Thread::SpinAcquire (volatile int * adr, const char * LockName) { 4145 if (Atomic::cmpxchg (1, adr, 0) == 0) { 4146 return ; // normal fast-path return 4147 } 4148 4149 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy. 4150 TEVENT (SpinAcquire - ctx) ; 4151 int ctr = 0 ; 4152 int Yields = 0 ; 4153 for (;;) { 4154 while (*adr != 0) { 4155 ++ctr ; 4156 if ((ctr & 0xFFF) == 0 || !os::is_MP()) { 4157 if (Yields > 5) { 4158 // Consider using a simple NakedSleep() instead. 4159 // Then SpinAcquire could be called by non-JVM threads 4160 Thread::current()->_ParkEvent->park(1) ; 4161 } else { 4162 os::NakedYield() ; 4163 ++Yields ; 4164 } 4165 } else { 4166 SpinPause() ; 4167 } 4168 } 4169 if (Atomic::cmpxchg (1, adr, 0) == 0) return ; 4170 } 4171 } 4172 4173 void Thread::SpinRelease (volatile int * adr) { 4174 assert (*adr != 0, "invariant") ; 4175 OrderAccess::fence() ; // guarantee at least release consistency. 4176 // Roach-motel semantics. 4177 // It's safe if subsequent LDs and STs float "up" into the critical section, 4178 // but prior LDs and STs within the critical section can't be allowed 4179 // to reorder or float past the ST that releases the lock. 4180 *adr = 0 ; 4181 } 4182 4183 // muxAcquire and muxRelease: 4184 // 4185 // * muxAcquire and muxRelease support a single-word lock-word construct. 4186 // The LSB of the word is set IFF the lock is held. 4187 // The remainder of the word points to the head of a singly-linked list 4188 // of threads blocked on the lock. 4189 // 4190 // * The current implementation of muxAcquire-muxRelease uses its own 4191 // dedicated Thread._MuxEvent instance. If we're interested in 4192 // minimizing the peak number of extant ParkEvent instances then 4193 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long 4194 // as certain invariants were satisfied. Specifically, care would need 4195 // to be taken with regards to consuming unpark() "permits". 4196 // A safe rule of thumb is that a thread would never call muxAcquire() 4197 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently 4198 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could 4199 // consume an unpark() permit intended for monitorenter, for instance. 4200 // One way around this would be to widen the restricted-range semaphore 4201 // implemented in park(). Another alternative would be to provide 4202 // multiple instances of the PlatformEvent() for each thread. One 4203 // instance would be dedicated to muxAcquire-muxRelease, for instance. 4204 // 4205 // * Usage: 4206 // -- Only as leaf locks 4207 // -- for short-term locking only as muxAcquire does not perform 4208 // thread state transitions. 4209 // 4210 // Alternatives: 4211 // * We could implement muxAcquire and muxRelease with MCS or CLH locks 4212 // but with parking or spin-then-park instead of pure spinning. 4213 // * Use Taura-Oyama-Yonenzawa locks. 4214 // * It's possible to construct a 1-0 lock if we encode the lockword as 4215 // (List,LockByte). Acquire will CAS the full lockword while Release 4216 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so 4217 // acquiring threads use timers (ParkTimed) to detect and recover from 4218 // the stranding window. Thread/Node structures must be aligned on 256-byte 4219 // boundaries by using placement-new. 4220 // * Augment MCS with advisory back-link fields maintained with CAS(). 4221 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner. 4222 // The validity of the backlinks must be ratified before we trust the value. 4223 // If the backlinks are invalid the exiting thread must back-track through the 4224 // the forward links, which are always trustworthy. 4225 // * Add a successor indication. The LockWord is currently encoded as 4226 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable 4227 // to provide the usual futile-wakeup optimization. 4228 // See RTStt for details. 4229 // * Consider schedctl.sc_nopreempt to cover the critical section. 4230 // 4231 4232 4233 typedef volatile intptr_t MutexT ; // Mux Lock-word 4234 enum MuxBits { LOCKBIT = 1 } ; 4235 4236 void Thread::muxAcquire (volatile intptr_t * Lock, const char * LockName) { 4237 intptr_t w = Atomic::cmpxchg_ptr (LOCKBIT, Lock, 0) ; 4238 if (w == 0) return ; 4239 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4240 return ; 4241 } 4242 4243 TEVENT (muxAcquire - Contention) ; 4244 ParkEvent * const Self = Thread::current()->_MuxEvent ; 4245 assert ((intptr_t(Self) & LOCKBIT) == 0, "invariant") ; 4246 for (;;) { 4247 int its = (os::is_MP() ? 100 : 0) + 1 ; 4248 4249 // Optional spin phase: spin-then-park strategy 4250 while (--its >= 0) { 4251 w = *Lock ; 4252 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4253 return ; 4254 } 4255 } 4256 4257 Self->reset() ; 4258 Self->OnList = intptr_t(Lock) ; 4259 // The following fence() isn't _strictly necessary as the subsequent 4260 // CAS() both serializes execution and ratifies the fetched *Lock value. 4261 OrderAccess::fence(); 4262 for (;;) { 4263 w = *Lock ; 4264 if ((w & LOCKBIT) == 0) { 4265 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4266 Self->OnList = 0 ; // hygiene - allows stronger asserts 4267 return ; 4268 } 4269 continue ; // Interference -- *Lock changed -- Just retry 4270 } 4271 assert (w & LOCKBIT, "invariant") ; 4272 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT ); 4273 if (Atomic::cmpxchg_ptr (intptr_t(Self)|LOCKBIT, Lock, w) == w) break ; 4274 } 4275 4276 while (Self->OnList != 0) { 4277 Self->park() ; 4278 } 4279 } 4280 } 4281 4282 void Thread::muxAcquireW (volatile intptr_t * Lock, ParkEvent * ev) { 4283 intptr_t w = Atomic::cmpxchg_ptr (LOCKBIT, Lock, 0) ; 4284 if (w == 0) return ; 4285 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4286 return ; 4287 } 4288 4289 TEVENT (muxAcquire - Contention) ; 4290 ParkEvent * ReleaseAfter = NULL ; 4291 if (ev == NULL) { 4292 ev = ReleaseAfter = ParkEvent::Allocate (NULL) ; 4293 } 4294 assert ((intptr_t(ev) & LOCKBIT) == 0, "invariant") ; 4295 for (;;) { 4296 guarantee (ev->OnList == 0, "invariant") ; 4297 int its = (os::is_MP() ? 100 : 0) + 1 ; 4298 4299 // Optional spin phase: spin-then-park strategy 4300 while (--its >= 0) { 4301 w = *Lock ; 4302 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4303 if (ReleaseAfter != NULL) { 4304 ParkEvent::Release (ReleaseAfter) ; 4305 } 4306 return ; 4307 } 4308 } 4309 4310 ev->reset() ; 4311 ev->OnList = intptr_t(Lock) ; 4312 // The following fence() isn't _strictly necessary as the subsequent 4313 // CAS() both serializes execution and ratifies the fetched *Lock value. 4314 OrderAccess::fence(); 4315 for (;;) { 4316 w = *Lock ; 4317 if ((w & LOCKBIT) == 0) { 4318 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4319 ev->OnList = 0 ; 4320 // We call ::Release while holding the outer lock, thus 4321 // artificially lengthening the critical section. 4322 // Consider deferring the ::Release() until the subsequent unlock(), 4323 // after we've dropped the outer lock. 4324 if (ReleaseAfter != NULL) { 4325 ParkEvent::Release (ReleaseAfter) ; 4326 } 4327 return ; 4328 } 4329 continue ; // Interference -- *Lock changed -- Just retry 4330 } 4331 assert (w & LOCKBIT, "invariant") ; 4332 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT ); 4333 if (Atomic::cmpxchg_ptr (intptr_t(ev)|LOCKBIT, Lock, w) == w) break ; 4334 } 4335 4336 while (ev->OnList != 0) { 4337 ev->park() ; 4338 } 4339 } 4340 } 4341 4342 // Release() must extract a successor from the list and then wake that thread. 4343 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme 4344 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based 4345 // Release() would : 4346 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list. 4347 // (B) Extract a successor from the private list "in-hand" 4348 // (C) attempt to CAS() the residual back into *Lock over null. 4349 // If there were any newly arrived threads and the CAS() would fail. 4350 // In that case Release() would detach the RATs, re-merge the list in-hand 4351 // with the RATs and repeat as needed. Alternately, Release() might 4352 // detach and extract a successor, but then pass the residual list to the wakee. 4353 // The wakee would be responsible for reattaching and remerging before it 4354 // competed for the lock. 4355 // 4356 // Both "pop" and DMR are immune from ABA corruption -- there can be 4357 // multiple concurrent pushers, but only one popper or detacher. 4358 // This implementation pops from the head of the list. This is unfair, 4359 // but tends to provide excellent throughput as hot threads remain hot. 4360 // (We wake recently run threads first). 4361 4362 void Thread::muxRelease (volatile intptr_t * Lock) { 4363 for (;;) { 4364 const intptr_t w = Atomic::cmpxchg_ptr (0, Lock, LOCKBIT) ; 4365 assert (w & LOCKBIT, "invariant") ; 4366 if (w == LOCKBIT) return ; 4367 ParkEvent * List = (ParkEvent *) (w & ~LOCKBIT) ; 4368 assert (List != NULL, "invariant") ; 4369 assert (List->OnList == intptr_t(Lock), "invariant") ; 4370 ParkEvent * nxt = List->ListNext ; 4371 4372 // The following CAS() releases the lock and pops the head element. 4373 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) { 4374 continue ; 4375 } 4376 List->OnList = 0 ; 4377 OrderAccess::fence() ; 4378 List->unpark () ; 4379 return ; 4380 } 4381 } 4382 4383 4384 void Threads::verify() { 4385 ALL_JAVA_THREADS(p) { 4386 p->verify(); 4387 } 4388 VMThread* thread = VMThread::vm_thread(); 4389 if (thread != NULL) thread->verify(); 4390 }