Mercurial > hg > truffle
annotate src/share/vm/runtime/safepoint.cpp @ 6901:fe4a4ea5bed9
7158804: Improve config file parsing
Summary: Check buffer length when reading
Reviewed-by: dholmes, dcubed
| author | kamg |
|---|---|
| date | Fri, 08 Jun 2012 12:49:12 -0400 |
| parents | 541c4a5e7b88 |
| children | e9140bf80b4a |
| rev | line source |
|---|---|
| 0 | 1 /* |
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2 * Copyright (c) 1997, 2012, Oracle and/or its affiliates. All rights reserved. |
| 0 | 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 * | |
|
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
| 0 | 22 * |
| 23 */ | |
| 24 | |
| 1972 | 25 #include "precompiled.hpp" |
| 26 #include "classfile/systemDictionary.hpp" | |
| 27 #include "code/codeCache.hpp" | |
| 28 #include "code/icBuffer.hpp" | |
| 29 #include "code/nmethod.hpp" | |
| 30 #include "code/pcDesc.hpp" | |
| 31 #include "code/scopeDesc.hpp" | |
| 32 #include "gc_interface/collectedHeap.hpp" | |
| 33 #include "interpreter/interpreter.hpp" | |
| 34 #include "memory/resourceArea.hpp" | |
| 35 #include "memory/universe.inline.hpp" | |
| 36 #include "oops/oop.inline.hpp" | |
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37 #include "oops/symbol.hpp" |
| 1972 | 38 #include "runtime/compilationPolicy.hpp" |
| 39 #include "runtime/deoptimization.hpp" | |
| 40 #include "runtime/frame.inline.hpp" | |
| 41 #include "runtime/interfaceSupport.hpp" | |
| 42 #include "runtime/mutexLocker.hpp" | |
| 43 #include "runtime/osThread.hpp" | |
| 44 #include "runtime/safepoint.hpp" | |
| 45 #include "runtime/signature.hpp" | |
| 46 #include "runtime/stubCodeGenerator.hpp" | |
| 47 #include "runtime/stubRoutines.hpp" | |
| 48 #include "runtime/sweeper.hpp" | |
| 49 #include "runtime/synchronizer.hpp" | |
| 50 #include "services/runtimeService.hpp" | |
| 51 #include "utilities/events.hpp" | |
| 52 #ifdef TARGET_ARCH_x86 | |
| 53 # include "nativeInst_x86.hpp" | |
| 54 # include "vmreg_x86.inline.hpp" | |
| 55 #endif | |
| 56 #ifdef TARGET_ARCH_sparc | |
| 57 # include "nativeInst_sparc.hpp" | |
| 58 # include "vmreg_sparc.inline.hpp" | |
| 59 #endif | |
| 60 #ifdef TARGET_ARCH_zero | |
| 61 # include "nativeInst_zero.hpp" | |
| 62 # include "vmreg_zero.inline.hpp" | |
| 63 #endif | |
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64 #ifdef TARGET_ARCH_arm |
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65 # include "nativeInst_arm.hpp" |
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66 # include "vmreg_arm.inline.hpp" |
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67 #endif |
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68 #ifdef TARGET_ARCH_ppc |
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69 # include "nativeInst_ppc.hpp" |
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70 # include "vmreg_ppc.inline.hpp" |
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71 #endif |
| 1972 | 72 #ifdef TARGET_OS_FAMILY_linux |
| 73 # include "thread_linux.inline.hpp" | |
| 74 #endif | |
| 75 #ifdef TARGET_OS_FAMILY_solaris | |
| 76 # include "thread_solaris.inline.hpp" | |
| 77 #endif | |
| 78 #ifdef TARGET_OS_FAMILY_windows | |
| 79 # include "thread_windows.inline.hpp" | |
| 80 #endif | |
| 3960 | 81 #ifdef TARGET_OS_FAMILY_bsd |
| 82 # include "thread_bsd.inline.hpp" | |
| 83 #endif | |
| 1972 | 84 #ifndef SERIALGC |
| 85 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp" | |
| 86 #include "gc_implementation/shared/concurrentGCThread.hpp" | |
| 87 #endif | |
| 88 #ifdef COMPILER1 | |
| 89 #include "c1/c1_globals.hpp" | |
| 90 #endif | |
| 0 | 91 |
| 92 // -------------------------------------------------------------------------------------------------- | |
| 93 // Implementation of Safepoint begin/end | |
| 94 | |
| 95 SafepointSynchronize::SynchronizeState volatile SafepointSynchronize::_state = SafepointSynchronize::_not_synchronized; | |
| 96 volatile int SafepointSynchronize::_waiting_to_block = 0; | |
| 97 volatile int SafepointSynchronize::_safepoint_counter = 0; | |
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98 int SafepointSynchronize::_current_jni_active_count = 0; |
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99 long SafepointSynchronize::_end_of_last_safepoint = 0; |
| 0 | 100 static volatile int PageArmed = 0 ; // safepoint polling page is RO|RW vs PROT_NONE |
| 101 static volatile int TryingToBlock = 0 ; // proximate value -- for advisory use only | |
| 102 static bool timeout_error_printed = false; | |
| 103 | |
| 104 // Roll all threads forward to a safepoint and suspend them all | |
| 105 void SafepointSynchronize::begin() { | |
| 106 | |
| 107 Thread* myThread = Thread::current(); | |
| 108 assert(myThread->is_VM_thread(), "Only VM thread may execute a safepoint"); | |
| 109 | |
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110 if (PrintSafepointStatistics || PrintSafepointStatisticsTimeout > 0) { |
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111 _safepoint_begin_time = os::javaTimeNanos(); |
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112 _ts_of_current_safepoint = tty->time_stamp().seconds(); |
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113 } |
| 0 | 114 |
| 115 #ifndef SERIALGC | |
| 116 if (UseConcMarkSweepGC) { | |
| 117 // In the future we should investigate whether CMS can use the | |
| 118 // more-general mechanism below. DLD (01/05). | |
| 119 ConcurrentMarkSweepThread::synchronize(false); | |
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120 } else if (UseG1GC) { |
| 0 | 121 ConcurrentGCThread::safepoint_synchronize(); |
| 122 } | |
| 123 #endif // SERIALGC | |
| 124 | |
| 125 // By getting the Threads_lock, we assure that no threads are about to start or | |
| 126 // exit. It is released again in SafepointSynchronize::end(). | |
| 127 Threads_lock->lock(); | |
| 128 | |
| 129 assert( _state == _not_synchronized, "trying to safepoint synchronize with wrong state"); | |
| 130 | |
| 131 int nof_threads = Threads::number_of_threads(); | |
| 132 | |
| 133 if (TraceSafepoint) { | |
| 134 tty->print_cr("Safepoint synchronization initiated. (%d)", nof_threads); | |
| 135 } | |
| 136 | |
| 137 RuntimeService::record_safepoint_begin(); | |
| 138 | |
| 139 MutexLocker mu(Safepoint_lock); | |
| 140 | |
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141 // Reset the count of active JNI critical threads |
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142 _current_jni_active_count = 0; |
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143 |
| 0 | 144 // Set number of threads to wait for, before we initiate the callbacks |
| 145 _waiting_to_block = nof_threads; | |
| 146 TryingToBlock = 0 ; | |
| 147 int still_running = nof_threads; | |
| 148 | |
| 149 // Save the starting time, so that it can be compared to see if this has taken | |
| 150 // too long to complete. | |
| 151 jlong safepoint_limit_time; | |
| 152 timeout_error_printed = false; | |
| 153 | |
| 1003 | 154 // PrintSafepointStatisticsTimeout can be specified separately. When |
| 155 // specified, PrintSafepointStatistics will be set to true in | |
| 156 // deferred_initialize_stat method. The initialization has to be done | |
| 157 // early enough to avoid any races. See bug 6880029 for details. | |
| 158 if (PrintSafepointStatistics || PrintSafepointStatisticsTimeout > 0) { | |
| 159 deferred_initialize_stat(); | |
| 160 } | |
| 161 | |
| 0 | 162 // Begin the process of bringing the system to a safepoint. |
| 163 // Java threads can be in several different states and are | |
| 164 // stopped by different mechanisms: | |
| 165 // | |
| 166 // 1. Running interpreted | |
| 167 // The interpeter dispatch table is changed to force it to | |
| 168 // check for a safepoint condition between bytecodes. | |
| 169 // 2. Running in native code | |
| 170 // When returning from the native code, a Java thread must check | |
| 171 // the safepoint _state to see if we must block. If the | |
| 172 // VM thread sees a Java thread in native, it does | |
| 173 // not wait for this thread to block. The order of the memory | |
| 174 // writes and reads of both the safepoint state and the Java | |
| 175 // threads state is critical. In order to guarantee that the | |
| 176 // memory writes are serialized with respect to each other, | |
| 177 // the VM thread issues a memory barrier instruction | |
| 178 // (on MP systems). In order to avoid the overhead of issuing | |
| 179 // a memory barrier for each Java thread making native calls, each Java | |
| 180 // thread performs a write to a single memory page after changing | |
| 181 // the thread state. The VM thread performs a sequence of | |
| 182 // mprotect OS calls which forces all previous writes from all | |
| 183 // Java threads to be serialized. This is done in the | |
| 184 // os::serialize_thread_states() call. This has proven to be | |
| 185 // much more efficient than executing a membar instruction | |
| 186 // on every call to native code. | |
| 187 // 3. Running compiled Code | |
| 188 // Compiled code reads a global (Safepoint Polling) page that | |
| 189 // is set to fault if we are trying to get to a safepoint. | |
| 190 // 4. Blocked | |
| 191 // A thread which is blocked will not be allowed to return from the | |
| 192 // block condition until the safepoint operation is complete. | |
| 193 // 5. In VM or Transitioning between states | |
| 194 // If a Java thread is currently running in the VM or transitioning | |
| 195 // between states, the safepointing code will wait for the thread to | |
| 196 // block itself when it attempts transitions to a new state. | |
| 197 // | |
| 198 _state = _synchronizing; | |
| 199 OrderAccess::fence(); | |
| 200 | |
| 201 // Flush all thread states to memory | |
| 202 if (!UseMembar) { | |
| 203 os::serialize_thread_states(); | |
| 204 } | |
| 205 | |
| 206 // Make interpreter safepoint aware | |
| 207 Interpreter::notice_safepoints(); | |
| 208 | |
| 209 if (UseCompilerSafepoints && DeferPollingPageLoopCount < 0) { | |
| 210 // Make polling safepoint aware | |
| 211 guarantee (PageArmed == 0, "invariant") ; | |
| 212 PageArmed = 1 ; | |
| 213 os::make_polling_page_unreadable(); | |
| 214 } | |
| 215 | |
| 216 // Consider using active_processor_count() ... but that call is expensive. | |
| 217 int ncpus = os::processor_count() ; | |
| 218 | |
| 219 #ifdef ASSERT | |
| 220 for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) { | |
| 221 assert(cur->safepoint_state()->is_running(), "Illegal initial state"); | |
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222 // Clear the visited flag to ensure that the critical counts are collected properly. |
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223 cur->set_visited_for_critical_count(false); |
| 0 | 224 } |
| 225 #endif // ASSERT | |
| 226 | |
| 227 if (SafepointTimeout) | |
| 228 safepoint_limit_time = os::javaTimeNanos() + (jlong)SafepointTimeoutDelay * MICROUNITS; | |
| 229 | |
| 230 // Iterate through all threads until it have been determined how to stop them all at a safepoint | |
| 231 unsigned int iterations = 0; | |
| 232 int steps = 0 ; | |
| 233 while(still_running > 0) { | |
| 234 for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) { | |
| 235 assert(!cur->is_ConcurrentGC_thread(), "A concurrent GC thread is unexpectly being suspended"); | |
| 236 ThreadSafepointState *cur_state = cur->safepoint_state(); | |
| 237 if (cur_state->is_running()) { | |
| 238 cur_state->examine_state_of_thread(); | |
| 239 if (!cur_state->is_running()) { | |
| 240 still_running--; | |
| 241 // consider adjusting steps downward: | |
| 242 // steps = 0 | |
| 243 // steps -= NNN | |
| 244 // steps >>= 1 | |
| 245 // steps = MIN(steps, 2000-100) | |
| 246 // if (iterations != 0) steps -= NNN | |
| 247 } | |
| 248 if (TraceSafepoint && Verbose) cur_state->print(); | |
| 249 } | |
| 250 } | |
| 251 | |
| 1003 | 252 if (PrintSafepointStatistics && iterations == 0) { |
| 0 | 253 begin_statistics(nof_threads, still_running); |
| 254 } | |
| 255 | |
| 256 if (still_running > 0) { | |
| 257 // Check for if it takes to long | |
| 258 if (SafepointTimeout && safepoint_limit_time < os::javaTimeNanos()) { | |
| 259 print_safepoint_timeout(_spinning_timeout); | |
| 260 } | |
| 261 | |
| 262 // Spin to avoid context switching. | |
| 263 // There's a tension between allowing the mutators to run (and rendezvous) | |
| 264 // vs spinning. As the VM thread spins, wasting cycles, it consumes CPU that | |
| 265 // a mutator might otherwise use profitably to reach a safepoint. Excessive | |
| 266 // spinning by the VM thread on a saturated system can increase rendezvous latency. | |
| 267 // Blocking or yielding incur their own penalties in the form of context switching | |
| 268 // and the resultant loss of $ residency. | |
| 269 // | |
| 270 // Further complicating matters is that yield() does not work as naively expected | |
| 271 // on many platforms -- yield() does not guarantee that any other ready threads | |
| 272 // will run. As such we revert yield_all() after some number of iterations. | |
| 273 // Yield_all() is implemented as a short unconditional sleep on some platforms. | |
| 274 // Typical operating systems round a "short" sleep period up to 10 msecs, so sleeping | |
| 275 // can actually increase the time it takes the VM thread to detect that a system-wide | |
| 276 // stop-the-world safepoint has been reached. In a pathological scenario such as that | |
| 277 // described in CR6415670 the VMthread may sleep just before the mutator(s) become safe. | |
| 278 // In that case the mutators will be stalled waiting for the safepoint to complete and the | |
| 279 // the VMthread will be sleeping, waiting for the mutators to rendezvous. The VMthread | |
| 280 // will eventually wake up and detect that all mutators are safe, at which point | |
| 281 // we'll again make progress. | |
| 282 // | |
| 283 // Beware too that that the VMThread typically runs at elevated priority. | |
| 284 // Its default priority is higher than the default mutator priority. | |
| 285 // Obviously, this complicates spinning. | |
| 286 // | |
| 287 // Note too that on Windows XP SwitchThreadTo() has quite different behavior than Sleep(0). | |
| 288 // Sleep(0) will _not yield to lower priority threads, while SwitchThreadTo() will. | |
| 289 // | |
| 290 // See the comments in synchronizer.cpp for additional remarks on spinning. | |
| 291 // | |
| 292 // In the future we might: | |
| 293 // 1. Modify the safepoint scheme to avoid potentally unbounded spinning. | |
| 294 // This is tricky as the path used by a thread exiting the JVM (say on | |
| 295 // on JNI call-out) simply stores into its state field. The burden | |
| 296 // is placed on the VM thread, which must poll (spin). | |
| 297 // 2. Find something useful to do while spinning. If the safepoint is GC-related | |
| 298 // we might aggressively scan the stacks of threads that are already safe. | |
| 299 // 3. Use Solaris schedctl to examine the state of the still-running mutators. | |
| 300 // If all the mutators are ONPROC there's no reason to sleep or yield. | |
| 301 // 4. YieldTo() any still-running mutators that are ready but OFFPROC. | |
| 302 // 5. Check system saturation. If the system is not fully saturated then | |
| 303 // simply spin and avoid sleep/yield. | |
| 304 // 6. As still-running mutators rendezvous they could unpark the sleeping | |
| 305 // VMthread. This works well for still-running mutators that become | |
| 306 // safe. The VMthread must still poll for mutators that call-out. | |
| 307 // 7. Drive the policy on time-since-begin instead of iterations. | |
| 308 // 8. Consider making the spin duration a function of the # of CPUs: | |
| 309 // Spin = (((ncpus-1) * M) + K) + F(still_running) | |
| 310 // Alternately, instead of counting iterations of the outer loop | |
| 311 // we could count the # of threads visited in the inner loop, above. | |
| 312 // 9. On windows consider using the return value from SwitchThreadTo() | |
| 313 // to drive subsequent spin/SwitchThreadTo()/Sleep(N) decisions. | |
| 314 | |
| 315 if (UseCompilerSafepoints && int(iterations) == DeferPollingPageLoopCount) { | |
| 316 guarantee (PageArmed == 0, "invariant") ; | |
| 317 PageArmed = 1 ; | |
| 318 os::make_polling_page_unreadable(); | |
| 319 } | |
| 320 | |
| 321 // Instead of (ncpus > 1) consider either (still_running < (ncpus + EPSILON)) or | |
| 322 // ((still_running + _waiting_to_block - TryingToBlock)) < ncpus) | |
| 323 ++steps ; | |
| 324 if (ncpus > 1 && steps < SafepointSpinBeforeYield) { | |
| 325 SpinPause() ; // MP-Polite spin | |
| 326 } else | |
| 327 if (steps < DeferThrSuspendLoopCount) { | |
| 328 os::NakedYield() ; | |
| 329 } else { | |
| 330 os::yield_all(steps) ; | |
| 331 // Alternately, the VM thread could transiently depress its scheduling priority or | |
| 332 // transiently increase the priority of the tardy mutator(s). | |
| 333 } | |
| 334 | |
| 335 iterations ++ ; | |
| 336 } | |
| 337 assert(iterations < (uint)max_jint, "We have been iterating in the safepoint loop too long"); | |
| 338 } | |
| 339 assert(still_running == 0, "sanity check"); | |
| 340 | |
| 341 if (PrintSafepointStatistics) { | |
| 342 update_statistics_on_spin_end(); | |
| 343 } | |
| 344 | |
| 345 // wait until all threads are stopped | |
| 346 while (_waiting_to_block > 0) { | |
| 347 if (TraceSafepoint) tty->print_cr("Waiting for %d thread(s) to block", _waiting_to_block); | |
| 348 if (!SafepointTimeout || timeout_error_printed) { | |
| 349 Safepoint_lock->wait(true); // true, means with no safepoint checks | |
| 350 } else { | |
| 351 // Compute remaining time | |
| 352 jlong remaining_time = safepoint_limit_time - os::javaTimeNanos(); | |
| 353 | |
| 354 // If there is no remaining time, then there is an error | |
| 355 if (remaining_time < 0 || Safepoint_lock->wait(true, remaining_time / MICROUNITS)) { | |
| 356 print_safepoint_timeout(_blocking_timeout); | |
| 357 } | |
| 358 } | |
| 359 } | |
| 360 assert(_waiting_to_block == 0, "sanity check"); | |
| 361 | |
| 362 #ifndef PRODUCT | |
| 363 if (SafepointTimeout) { | |
| 364 jlong current_time = os::javaTimeNanos(); | |
| 365 if (safepoint_limit_time < current_time) { | |
| 366 tty->print_cr("# SafepointSynchronize: Finished after " | |
| 367 INT64_FORMAT_W(6) " ms", | |
| 368 ((current_time - safepoint_limit_time) / MICROUNITS + | |
| 369 SafepointTimeoutDelay)); | |
| 370 } | |
| 371 } | |
| 372 #endif | |
| 373 | |
| 374 assert((_safepoint_counter & 0x1) == 0, "must be even"); | |
| 375 assert(Threads_lock->owned_by_self(), "must hold Threads_lock"); | |
| 376 _safepoint_counter ++; | |
| 377 | |
| 378 // Record state | |
| 379 _state = _synchronized; | |
| 380 | |
| 381 OrderAccess::fence(); | |
| 382 | |
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383 #ifdef ASSERT |
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384 for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) { |
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385 // make sure all the threads were visited |
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386 assert(cur->was_visited_for_critical_count(), "missed a thread"); |
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387 } |
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388 #endif // ASSERT |
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389 |
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390 // Update the count of active JNI critical regions |
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391 GC_locker::set_jni_lock_count(_current_jni_active_count); |
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392 |
| 0 | 393 if (TraceSafepoint) { |
| 394 VM_Operation *op = VMThread::vm_operation(); | |
| 395 tty->print_cr("Entering safepoint region: %s", (op != NULL) ? op->name() : "no vm operation"); | |
| 396 } | |
| 397 | |
| 398 RuntimeService::record_safepoint_synchronized(); | |
| 399 if (PrintSafepointStatistics) { | |
| 400 update_statistics_on_sync_end(os::javaTimeNanos()); | |
| 401 } | |
| 402 | |
| 403 // Call stuff that needs to be run when a safepoint is just about to be completed | |
| 404 do_cleanup_tasks(); | |
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405 |
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406 if (PrintSafepointStatistics) { |
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407 // Record how much time spend on the above cleanup tasks |
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408 update_statistics_on_cleanup_end(os::javaTimeNanos()); |
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409 } |
| 0 | 410 } |
| 411 | |
| 412 // Wake up all threads, so they are ready to resume execution after the safepoint | |
| 413 // operation has been carried out | |
| 414 void SafepointSynchronize::end() { | |
| 415 | |
| 416 assert(Threads_lock->owned_by_self(), "must hold Threads_lock"); | |
| 417 assert((_safepoint_counter & 0x1) == 1, "must be odd"); | |
| 418 _safepoint_counter ++; | |
| 419 // memory fence isn't required here since an odd _safepoint_counter | |
| 420 // value can do no harm and a fence is issued below anyway. | |
| 421 | |
| 422 DEBUG_ONLY(Thread* myThread = Thread::current();) | |
| 423 assert(myThread->is_VM_thread(), "Only VM thread can execute a safepoint"); | |
| 424 | |
| 425 if (PrintSafepointStatistics) { | |
| 426 end_statistics(os::javaTimeNanos()); | |
| 427 } | |
| 428 | |
| 429 #ifdef ASSERT | |
| 430 // A pending_exception cannot be installed during a safepoint. The threads | |
| 431 // may install an async exception after they come back from a safepoint into | |
| 432 // pending_exception after they unblock. But that should happen later. | |
| 433 for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) { | |
| 434 assert (!(cur->has_pending_exception() && | |
| 435 cur->safepoint_state()->is_at_poll_safepoint()), | |
| 436 "safepoint installed a pending exception"); | |
| 437 } | |
| 438 #endif // ASSERT | |
| 439 | |
| 440 if (PageArmed) { | |
| 441 // Make polling safepoint aware | |
| 442 os::make_polling_page_readable(); | |
| 443 PageArmed = 0 ; | |
| 444 } | |
| 445 | |
| 446 // Remove safepoint check from interpreter | |
| 447 Interpreter::ignore_safepoints(); | |
| 448 | |
| 449 { | |
| 450 MutexLocker mu(Safepoint_lock); | |
| 451 | |
| 452 assert(_state == _synchronized, "must be synchronized before ending safepoint synchronization"); | |
| 453 | |
| 454 // Set to not synchronized, so the threads will not go into the signal_thread_blocked method | |
| 455 // when they get restarted. | |
| 456 _state = _not_synchronized; | |
| 457 OrderAccess::fence(); | |
| 458 | |
| 459 if (TraceSafepoint) { | |
| 460 tty->print_cr("Leaving safepoint region"); | |
| 461 } | |
| 462 | |
| 463 // Start suspended threads | |
| 464 for(JavaThread *current = Threads::first(); current; current = current->next()) { | |
| 605 | 465 // A problem occurring on Solaris is when attempting to restart threads |
| 0 | 466 // the first #cpus - 1 go well, but then the VMThread is preempted when we get |
| 467 // to the next one (since it has been running the longest). We then have | |
| 468 // to wait for a cpu to become available before we can continue restarting | |
| 469 // threads. | |
| 470 // FIXME: This causes the performance of the VM to degrade when active and with | |
| 471 // large numbers of threads. Apparently this is due to the synchronous nature | |
| 472 // of suspending threads. | |
| 473 // | |
| 474 // TODO-FIXME: the comments above are vestigial and no longer apply. | |
| 475 // Furthermore, using solaris' schedctl in this particular context confers no benefit | |
| 476 if (VMThreadHintNoPreempt) { | |
| 477 os::hint_no_preempt(); | |
| 478 } | |
| 479 ThreadSafepointState* cur_state = current->safepoint_state(); | |
| 480 assert(cur_state->type() != ThreadSafepointState::_running, "Thread not suspended at safepoint"); | |
| 481 cur_state->restart(); | |
| 482 assert(cur_state->is_running(), "safepoint state has not been reset"); | |
| 483 } | |
| 484 | |
| 485 RuntimeService::record_safepoint_end(); | |
| 486 | |
| 487 // Release threads lock, so threads can be created/destroyed again. It will also starts all threads | |
| 488 // blocked in signal_thread_blocked | |
| 489 Threads_lock->unlock(); | |
| 490 | |
| 491 } | |
| 492 #ifndef SERIALGC | |
| 493 // If there are any concurrent GC threads resume them. | |
| 494 if (UseConcMarkSweepGC) { | |
| 495 ConcurrentMarkSweepThread::desynchronize(false); | |
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496 } else if (UseG1GC) { |
| 0 | 497 ConcurrentGCThread::safepoint_desynchronize(); |
| 498 } | |
| 499 #endif // SERIALGC | |
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500 // record this time so VMThread can keep track how much time has elasped |
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501 // since last safepoint. |
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502 _end_of_last_safepoint = os::javaTimeMillis(); |
| 0 | 503 } |
| 504 | |
| 505 bool SafepointSynchronize::is_cleanup_needed() { | |
| 506 // Need a safepoint if some inline cache buffers is non-empty | |
| 507 if (!InlineCacheBuffer::is_empty()) return true; | |
| 508 return false; | |
| 509 } | |
| 510 | |
| 511 | |
| 512 | |
| 513 // Various cleaning tasks that should be done periodically at safepoints | |
| 514 void SafepointSynchronize::do_cleanup_tasks() { | |
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515 { |
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516 TraceTime t1("deflating idle monitors", TraceSafepointCleanupTime); |
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517 ObjectSynchronizer::deflate_idle_monitors(); |
| 0 | 518 } |
| 519 | |
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520 { |
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521 TraceTime t2("updating inline caches", TraceSafepointCleanupTime); |
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522 InlineCacheBuffer::update_inline_caches(); |
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523 } |
| 1783 | 524 { |
| 525 TraceTime t3("compilation policy safepoint handler", TraceSafepointCleanupTime); | |
| 526 CompilationPolicy::policy()->do_safepoint_work(); | |
| 0 | 527 } |
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528 |
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529 TraceTime t4("sweeping nmethods", TraceSafepointCleanupTime); |
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530 NMethodSweeper::scan_stacks(); |
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531 |
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532 // rotate log files? |
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533 if (UseGCLogFileRotation) { |
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534 gclog_or_tty->rotate_log(); |
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535 } |
| 0 | 536 } |
| 537 | |
| 538 | |
| 539 bool SafepointSynchronize::safepoint_safe(JavaThread *thread, JavaThreadState state) { | |
| 540 switch(state) { | |
| 541 case _thread_in_native: | |
| 542 // native threads are safe if they have no java stack or have walkable stack | |
| 543 return !thread->has_last_Java_frame() || thread->frame_anchor()->walkable(); | |
| 544 | |
| 545 // blocked threads should have already have walkable stack | |
| 546 case _thread_blocked: | |
| 547 assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "blocked and not walkable"); | |
| 548 return true; | |
| 549 | |
| 550 default: | |
| 551 return false; | |
| 552 } | |
| 553 } | |
| 554 | |
| 555 | |
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556 // See if the thread is running inside a lazy critical native and |
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557 // update the thread critical count if so. Also set a suspend flag to |
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558 // cause the native wrapper to return into the JVM to do the unlock |
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559 // once the native finishes. |
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560 void SafepointSynchronize::check_for_lazy_critical_native(JavaThread *thread, JavaThreadState state) { |
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561 if (state == _thread_in_native && |
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562 thread->has_last_Java_frame() && |
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563 thread->frame_anchor()->walkable()) { |
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564 // This thread might be in a critical native nmethod so look at |
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565 // the top of the stack and increment the critical count if it |
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566 // is. |
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567 frame wrapper_frame = thread->last_frame(); |
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568 CodeBlob* stub_cb = wrapper_frame.cb(); |
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569 if (stub_cb != NULL && |
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570 stub_cb->is_nmethod() && |
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571 stub_cb->as_nmethod_or_null()->is_lazy_critical_native()) { |
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572 // A thread could potentially be in a critical native across |
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573 // more than one safepoint, so only update the critical state on |
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574 // the first one. When it returns it will perform the unlock. |
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575 if (!thread->do_critical_native_unlock()) { |
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576 #ifdef ASSERT |
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577 if (!thread->in_critical()) { |
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578 GC_locker::increment_debug_jni_lock_count(); |
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579 } |
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580 #endif |
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581 thread->enter_critical(); |
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582 // Make sure the native wrapper calls back on return to |
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583 // perform the needed critical unlock. |
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584 thread->set_critical_native_unlock(); |
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585 } |
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586 } |
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587 } |
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588 } |
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589 |
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590 |
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591 |
| 0 | 592 // ------------------------------------------------------------------------------------------------------- |
| 593 // Implementation of Safepoint callback point | |
| 594 | |
| 595 void SafepointSynchronize::block(JavaThread *thread) { | |
| 596 assert(thread != NULL, "thread must be set"); | |
| 597 assert(thread->is_Java_thread(), "not a Java thread"); | |
| 598 | |
| 599 // Threads shouldn't block if they are in the middle of printing, but... | |
| 600 ttyLocker::break_tty_lock_for_safepoint(os::current_thread_id()); | |
| 601 | |
| 602 // Only bail from the block() call if the thread is gone from the | |
| 603 // thread list; starting to exit should still block. | |
| 604 if (thread->is_terminated()) { | |
| 605 // block current thread if we come here from native code when VM is gone | |
| 606 thread->block_if_vm_exited(); | |
| 607 | |
| 608 // otherwise do nothing | |
| 609 return; | |
| 610 } | |
| 611 | |
| 612 JavaThreadState state = thread->thread_state(); | |
| 613 thread->frame_anchor()->make_walkable(thread); | |
| 614 | |
| 615 // Check that we have a valid thread_state at this point | |
| 616 switch(state) { | |
| 617 case _thread_in_vm_trans: | |
| 618 case _thread_in_Java: // From compiled code | |
| 619 | |
| 620 // We are highly likely to block on the Safepoint_lock. In order to avoid blocking in this case, | |
| 621 // we pretend we are still in the VM. | |
| 622 thread->set_thread_state(_thread_in_vm); | |
| 623 | |
| 624 if (is_synchronizing()) { | |
| 625 Atomic::inc (&TryingToBlock) ; | |
| 626 } | |
| 627 | |
| 628 // We will always be holding the Safepoint_lock when we are examine the state | |
| 629 // of a thread. Hence, the instructions between the Safepoint_lock->lock() and | |
| 630 // Safepoint_lock->unlock() are happening atomic with regards to the safepoint code | |
| 631 Safepoint_lock->lock_without_safepoint_check(); | |
| 632 if (is_synchronizing()) { | |
| 633 // Decrement the number of threads to wait for and signal vm thread | |
| 634 assert(_waiting_to_block > 0, "sanity check"); | |
| 635 _waiting_to_block--; | |
| 636 thread->safepoint_state()->set_has_called_back(true); | |
| 637 | |
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638 DEBUG_ONLY(thread->set_visited_for_critical_count(true)); |
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639 if (thread->in_critical()) { |
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640 // Notice that this thread is in a critical section |
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641 increment_jni_active_count(); |
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642 } |
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643 |
| 0 | 644 // Consider (_waiting_to_block < 2) to pipeline the wakeup of the VM thread |
| 645 if (_waiting_to_block == 0) { | |
| 646 Safepoint_lock->notify_all(); | |
| 647 } | |
| 648 } | |
| 649 | |
| 650 // We transition the thread to state _thread_blocked here, but | |
| 651 // we can't do our usual check for external suspension and then | |
| 652 // self-suspend after the lock_without_safepoint_check() call | |
| 653 // below because we are often called during transitions while | |
| 654 // we hold different locks. That would leave us suspended while | |
| 655 // holding a resource which results in deadlocks. | |
| 656 thread->set_thread_state(_thread_blocked); | |
| 657 Safepoint_lock->unlock(); | |
| 658 | |
| 659 // We now try to acquire the threads lock. Since this lock is hold by the VM thread during | |
| 660 // the entire safepoint, the threads will all line up here during the safepoint. | |
| 661 Threads_lock->lock_without_safepoint_check(); | |
| 662 // restore original state. This is important if the thread comes from compiled code, so it | |
| 663 // will continue to execute with the _thread_in_Java state. | |
| 664 thread->set_thread_state(state); | |
| 665 Threads_lock->unlock(); | |
| 666 break; | |
| 667 | |
| 668 case _thread_in_native_trans: | |
| 669 case _thread_blocked_trans: | |
| 670 case _thread_new_trans: | |
| 671 if (thread->safepoint_state()->type() == ThreadSafepointState::_call_back) { | |
| 672 thread->print_thread_state(); | |
| 673 fatal("Deadlock in safepoint code. " | |
| 674 "Should have called back to the VM before blocking."); | |
| 675 } | |
| 676 | |
| 677 // We transition the thread to state _thread_blocked here, but | |
| 678 // we can't do our usual check for external suspension and then | |
| 679 // self-suspend after the lock_without_safepoint_check() call | |
| 680 // below because we are often called during transitions while | |
| 681 // we hold different locks. That would leave us suspended while | |
| 682 // holding a resource which results in deadlocks. | |
| 683 thread->set_thread_state(_thread_blocked); | |
| 684 | |
| 685 // It is not safe to suspend a thread if we discover it is in _thread_in_native_trans. Hence, | |
| 686 // the safepoint code might still be waiting for it to block. We need to change the state here, | |
| 687 // so it can see that it is at a safepoint. | |
| 688 | |
| 689 // Block until the safepoint operation is completed. | |
| 690 Threads_lock->lock_without_safepoint_check(); | |
| 691 | |
| 692 // Restore state | |
| 693 thread->set_thread_state(state); | |
| 694 | |
| 695 Threads_lock->unlock(); | |
| 696 break; | |
| 697 | |
| 698 default: | |
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699 fatal(err_msg("Illegal threadstate encountered: %d", state)); |
| 0 | 700 } |
| 701 | |
| 702 // Check for pending. async. exceptions or suspends - except if the | |
| 703 // thread was blocked inside the VM. has_special_runtime_exit_condition() | |
| 704 // is called last since it grabs a lock and we only want to do that when | |
| 705 // we must. | |
| 706 // | |
| 707 // Note: we never deliver an async exception at a polling point as the | |
| 708 // compiler may not have an exception handler for it. The polling | |
| 709 // code will notice the async and deoptimize and the exception will | |
| 710 // be delivered. (Polling at a return point is ok though). Sure is | |
| 711 // a lot of bother for a deprecated feature... | |
| 712 // | |
| 713 // We don't deliver an async exception if the thread state is | |
| 714 // _thread_in_native_trans so JNI functions won't be called with | |
| 715 // a surprising pending exception. If the thread state is going back to java, | |
| 716 // async exception is checked in check_special_condition_for_native_trans(). | |
| 717 | |
| 718 if (state != _thread_blocked_trans && | |
| 719 state != _thread_in_vm_trans && | |
| 720 thread->has_special_runtime_exit_condition()) { | |
| 721 thread->handle_special_runtime_exit_condition( | |
| 722 !thread->is_at_poll_safepoint() && (state != _thread_in_native_trans)); | |
| 723 } | |
| 724 } | |
| 725 | |
| 726 // ------------------------------------------------------------------------------------------------------ | |
| 727 // Exception handlers | |
| 728 | |
| 729 #ifndef PRODUCT | |
| 730 #ifdef _LP64 | |
| 731 #define PTR_PAD "" | |
| 732 #else | |
| 733 #define PTR_PAD " " | |
| 734 #endif | |
| 735 | |
| 736 static void print_ptrs(intptr_t oldptr, intptr_t newptr, bool wasoop) { | |
| 737 bool is_oop = newptr ? ((oop)newptr)->is_oop() : false; | |
| 738 tty->print_cr(PTR_FORMAT PTR_PAD " %s %c " PTR_FORMAT PTR_PAD " %s %s", | |
| 739 oldptr, wasoop?"oop":" ", oldptr == newptr ? ' ' : '!', | |
| 740 newptr, is_oop?"oop":" ", (wasoop && !is_oop) ? "STALE" : ((wasoop==false&&is_oop==false&&oldptr !=newptr)?"STOMP":" ")); | |
| 741 } | |
| 742 | |
| 743 static void print_longs(jlong oldptr, jlong newptr, bool wasoop) { | |
| 744 bool is_oop = newptr ? ((oop)(intptr_t)newptr)->is_oop() : false; | |
| 745 tty->print_cr(PTR64_FORMAT " %s %c " PTR64_FORMAT " %s %s", | |
| 746 oldptr, wasoop?"oop":" ", oldptr == newptr ? ' ' : '!', | |
| 747 newptr, is_oop?"oop":" ", (wasoop && !is_oop) ? "STALE" : ((wasoop==false&&is_oop==false&&oldptr !=newptr)?"STOMP":" ")); | |
| 748 } | |
| 749 | |
| 750 #ifdef SPARC | |
| 751 static void print_me(intptr_t *new_sp, intptr_t *old_sp, bool *was_oops) { | |
| 752 #ifdef _LP64 | |
| 753 tty->print_cr("--------+------address-----+------before-----------+-------after----------+"); | |
| 754 const int incr = 1; // Increment to skip a long, in units of intptr_t | |
| 755 #else | |
| 756 tty->print_cr("--------+--address-+------before-----------+-------after----------+"); | |
| 757 const int incr = 2; // Increment to skip a long, in units of intptr_t | |
| 758 #endif | |
| 759 tty->print_cr("---SP---|"); | |
| 760 for( int i=0; i<16; i++ ) { | |
| 761 tty->print("blob %c%d |"PTR_FORMAT" ","LO"[i>>3],i&7,new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); } | |
| 762 tty->print_cr("--------|"); | |
| 763 for( int i1=0; i1<frame::memory_parameter_word_sp_offset-16; i1++ ) { | |
| 764 tty->print("argv pad|"PTR_FORMAT" ",new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); } | |
| 765 tty->print(" pad|"PTR_FORMAT" ",new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); | |
| 766 tty->print_cr("--------|"); | |
| 767 tty->print(" G1 |"PTR_FORMAT" ",new_sp); print_longs(*(jlong*)old_sp,*(jlong*)new_sp,was_oops[incr-1]); old_sp += incr; new_sp += incr; was_oops += incr; | |
| 768 tty->print(" G3 |"PTR_FORMAT" ",new_sp); print_longs(*(jlong*)old_sp,*(jlong*)new_sp,was_oops[incr-1]); old_sp += incr; new_sp += incr; was_oops += incr; | |
| 769 tty->print(" G4 |"PTR_FORMAT" ",new_sp); print_longs(*(jlong*)old_sp,*(jlong*)new_sp,was_oops[incr-1]); old_sp += incr; new_sp += incr; was_oops += incr; | |
| 770 tty->print(" G5 |"PTR_FORMAT" ",new_sp); print_longs(*(jlong*)old_sp,*(jlong*)new_sp,was_oops[incr-1]); old_sp += incr; new_sp += incr; was_oops += incr; | |
| 771 tty->print_cr(" FSR |"PTR_FORMAT" "PTR64_FORMAT" "PTR64_FORMAT,new_sp,*(jlong*)old_sp,*(jlong*)new_sp); | |
| 772 old_sp += incr; new_sp += incr; was_oops += incr; | |
| 773 // Skip the floats | |
| 774 tty->print_cr("--Float-|"PTR_FORMAT,new_sp); | |
| 775 tty->print_cr("---FP---|"); | |
| 776 old_sp += incr*32; new_sp += incr*32; was_oops += incr*32; | |
| 777 for( int i2=0; i2<16; i2++ ) { | |
| 778 tty->print("call %c%d |"PTR_FORMAT" ","LI"[i2>>3],i2&7,new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); } | |
| 779 tty->print_cr(""); | |
| 780 } | |
| 781 #endif // SPARC | |
| 782 #endif // PRODUCT | |
| 783 | |
| 784 | |
| 785 void SafepointSynchronize::handle_polling_page_exception(JavaThread *thread) { | |
| 786 assert(thread->is_Java_thread(), "polling reference encountered by VM thread"); | |
| 787 assert(thread->thread_state() == _thread_in_Java, "should come from Java code"); | |
| 788 assert(SafepointSynchronize::is_synchronizing(), "polling encountered outside safepoint synchronization"); | |
| 789 | |
| 790 // Uncomment this to get some serious before/after printing of the | |
| 791 // Sparc safepoint-blob frame structure. | |
| 792 /* | |
| 793 intptr_t* sp = thread->last_Java_sp(); | |
| 794 intptr_t stack_copy[150]; | |
| 795 for( int i=0; i<150; i++ ) stack_copy[i] = sp[i]; | |
| 796 bool was_oops[150]; | |
| 797 for( int i=0; i<150; i++ ) | |
| 798 was_oops[i] = stack_copy[i] ? ((oop)stack_copy[i])->is_oop() : false; | |
| 799 */ | |
| 800 | |
| 801 if (ShowSafepointMsgs) { | |
| 802 tty->print("handle_polling_page_exception: "); | |
| 803 } | |
| 804 | |
| 805 if (PrintSafepointStatistics) { | |
| 806 inc_page_trap_count(); | |
| 807 } | |
| 808 | |
| 809 ThreadSafepointState* state = thread->safepoint_state(); | |
| 810 | |
| 811 state->handle_polling_page_exception(); | |
| 812 // print_me(sp,stack_copy,was_oops); | |
| 813 } | |
| 814 | |
| 815 | |
| 816 void SafepointSynchronize::print_safepoint_timeout(SafepointTimeoutReason reason) { | |
| 817 if (!timeout_error_printed) { | |
| 818 timeout_error_printed = true; | |
| 819 // Print out the thread infor which didn't reach the safepoint for debugging | |
| 820 // purposes (useful when there are lots of threads in the debugger). | |
| 821 tty->print_cr(""); | |
| 822 tty->print_cr("# SafepointSynchronize::begin: Timeout detected:"); | |
| 823 if (reason == _spinning_timeout) { | |
| 824 tty->print_cr("# SafepointSynchronize::begin: Timed out while spinning to reach a safepoint."); | |
| 825 } else if (reason == _blocking_timeout) { | |
| 826 tty->print_cr("# SafepointSynchronize::begin: Timed out while waiting for threads to stop."); | |
| 827 } | |
| 828 | |
| 829 tty->print_cr("# SafepointSynchronize::begin: Threads which did not reach the safepoint:"); | |
| 830 ThreadSafepointState *cur_state; | |
| 831 ResourceMark rm; | |
| 832 for(JavaThread *cur_thread = Threads::first(); cur_thread; | |
| 833 cur_thread = cur_thread->next()) { | |
| 834 cur_state = cur_thread->safepoint_state(); | |
| 835 | |
| 836 if (cur_thread->thread_state() != _thread_blocked && | |
| 837 ((reason == _spinning_timeout && cur_state->is_running()) || | |
| 838 (reason == _blocking_timeout && !cur_state->has_called_back()))) { | |
| 839 tty->print("# "); | |
| 840 cur_thread->print(); | |
| 841 tty->print_cr(""); | |
| 842 } | |
| 843 } | |
| 844 tty->print_cr("# SafepointSynchronize::begin: (End of list)"); | |
| 845 } | |
| 846 | |
| 847 // To debug the long safepoint, specify both DieOnSafepointTimeout & | |
| 848 // ShowMessageBoxOnError. | |
| 849 if (DieOnSafepointTimeout) { | |
| 850 char msg[1024]; | |
| 851 VM_Operation *op = VMThread::vm_operation(); | |
|
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852 sprintf(msg, "Safepoint sync time longer than " INTX_FORMAT "ms detected when executing %s.", |
| 0 | 853 SafepointTimeoutDelay, |
| 854 op != NULL ? op->name() : "no vm operation"); | |
| 855 fatal(msg); | |
| 856 } | |
| 857 } | |
| 858 | |
| 859 | |
| 860 // ------------------------------------------------------------------------------------------------------- | |
| 861 // Implementation of ThreadSafepointState | |
| 862 | |
| 863 ThreadSafepointState::ThreadSafepointState(JavaThread *thread) { | |
| 864 _thread = thread; | |
| 865 _type = _running; | |
| 866 _has_called_back = false; | |
| 867 _at_poll_safepoint = false; | |
| 868 } | |
| 869 | |
| 870 void ThreadSafepointState::create(JavaThread *thread) { | |
| 871 ThreadSafepointState *state = new ThreadSafepointState(thread); | |
| 872 thread->set_safepoint_state(state); | |
| 873 } | |
| 874 | |
| 875 void ThreadSafepointState::destroy(JavaThread *thread) { | |
| 876 if (thread->safepoint_state()) { | |
| 877 delete(thread->safepoint_state()); | |
| 878 thread->set_safepoint_state(NULL); | |
| 879 } | |
| 880 } | |
| 881 | |
| 882 void ThreadSafepointState::examine_state_of_thread() { | |
| 883 assert(is_running(), "better be running or just have hit safepoint poll"); | |
| 884 | |
| 885 JavaThreadState state = _thread->thread_state(); | |
| 886 | |
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887 // Save the state at the start of safepoint processing. |
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888 _orig_thread_state = state; |
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889 |
| 0 | 890 // Check for a thread that is suspended. Note that thread resume tries |
| 891 // to grab the Threads_lock which we own here, so a thread cannot be | |
| 892 // resumed during safepoint synchronization. | |
| 893 | |
| 979 | 894 // We check to see if this thread is suspended without locking to |
| 895 // avoid deadlocking with a third thread that is waiting for this | |
| 896 // thread to be suspended. The third thread can notice the safepoint | |
| 897 // that we're trying to start at the beginning of its SR_lock->wait() | |
| 898 // call. If that happens, then the third thread will block on the | |
| 899 // safepoint while still holding the underlying SR_lock. We won't be | |
| 900 // able to get the SR_lock and we'll deadlock. | |
| 901 // | |
| 902 // We don't need to grab the SR_lock here for two reasons: | |
| 903 // 1) The suspend flags are both volatile and are set with an | |
| 904 // Atomic::cmpxchg() call so we should see the suspended | |
| 905 // state right away. | |
| 906 // 2) We're being called from the safepoint polling loop; if | |
| 907 // we don't see the suspended state on this iteration, then | |
| 908 // we'll come around again. | |
| 909 // | |
| 910 bool is_suspended = _thread->is_ext_suspended(); | |
| 0 | 911 if (is_suspended) { |
| 912 roll_forward(_at_safepoint); | |
| 913 return; | |
| 914 } | |
| 915 | |
| 916 // Some JavaThread states have an initial safepoint state of | |
| 917 // running, but are actually at a safepoint. We will happily | |
| 918 // agree and update the safepoint state here. | |
| 919 if (SafepointSynchronize::safepoint_safe(_thread, state)) { | |
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920 SafepointSynchronize::check_for_lazy_critical_native(_thread, state); |
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921 roll_forward(_at_safepoint); |
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922 return; |
| 0 | 923 } |
| 924 | |
| 925 if (state == _thread_in_vm) { | |
| 926 roll_forward(_call_back); | |
| 927 return; | |
| 928 } | |
| 929 | |
| 930 // All other thread states will continue to run until they | |
| 931 // transition and self-block in state _blocked | |
| 932 // Safepoint polling in compiled code causes the Java threads to do the same. | |
| 933 // Note: new threads may require a malloc so they must be allowed to finish | |
| 934 | |
| 935 assert(is_running(), "examine_state_of_thread on non-running thread"); | |
| 936 return; | |
| 937 } | |
| 938 | |
| 939 // Returns true is thread could not be rolled forward at present position. | |
| 940 void ThreadSafepointState::roll_forward(suspend_type type) { | |
| 941 _type = type; | |
| 942 | |
| 943 switch(_type) { | |
| 944 case _at_safepoint: | |
| 945 SafepointSynchronize::signal_thread_at_safepoint(); | |
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946 DEBUG_ONLY(_thread->set_visited_for_critical_count(true)); |
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947 if (_thread->in_critical()) { |
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948 // Notice that this thread is in a critical section |
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949 SafepointSynchronize::increment_jni_active_count(); |
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950 } |
| 0 | 951 break; |
| 952 | |
| 953 case _call_back: | |
| 954 set_has_called_back(false); | |
| 955 break; | |
| 956 | |
| 957 case _running: | |
| 958 default: | |
| 959 ShouldNotReachHere(); | |
| 960 } | |
| 961 } | |
| 962 | |
| 963 void ThreadSafepointState::restart() { | |
| 964 switch(type()) { | |
| 965 case _at_safepoint: | |
| 966 case _call_back: | |
| 967 break; | |
| 968 | |
| 969 case _running: | |
| 970 default: | |
| 971 tty->print_cr("restart thread "INTPTR_FORMAT" with state %d", | |
| 972 _thread, _type); | |
| 973 _thread->print(); | |
| 974 ShouldNotReachHere(); | |
| 975 } | |
| 976 _type = _running; | |
| 977 set_has_called_back(false); | |
| 978 } | |
| 979 | |
| 980 | |
| 981 void ThreadSafepointState::print_on(outputStream *st) const { | |
| 982 const char *s; | |
| 983 | |
| 984 switch(_type) { | |
| 985 case _running : s = "_running"; break; | |
| 986 case _at_safepoint : s = "_at_safepoint"; break; | |
| 987 case _call_back : s = "_call_back"; break; | |
| 988 default: | |
| 989 ShouldNotReachHere(); | |
| 990 } | |
| 991 | |
| 992 st->print_cr("Thread: " INTPTR_FORMAT | |
| 993 " [0x%2x] State: %s _has_called_back %d _at_poll_safepoint %d", | |
| 994 _thread, _thread->osthread()->thread_id(), s, _has_called_back, | |
| 995 _at_poll_safepoint); | |
| 996 | |
| 997 _thread->print_thread_state_on(st); | |
| 998 } | |
| 999 | |
| 1000 | |
| 1001 // --------------------------------------------------------------------------------------------------------------------- | |
| 1002 | |
| 1003 // Block the thread at the safepoint poll or poll return. | |
| 1004 void ThreadSafepointState::handle_polling_page_exception() { | |
| 1005 | |
| 1006 // Check state. block() will set thread state to thread_in_vm which will | |
| 1007 // cause the safepoint state _type to become _call_back. | |
| 1008 assert(type() == ThreadSafepointState::_running, | |
| 1009 "polling page exception on thread not running state"); | |
| 1010 | |
| 1011 // Step 1: Find the nmethod from the return address | |
| 1012 if (ShowSafepointMsgs && Verbose) { | |
| 1013 tty->print_cr("Polling page exception at " INTPTR_FORMAT, thread()->saved_exception_pc()); | |
| 1014 } | |
| 1015 address real_return_addr = thread()->saved_exception_pc(); | |
| 1016 | |
| 1017 CodeBlob *cb = CodeCache::find_blob(real_return_addr); | |
| 1018 assert(cb != NULL && cb->is_nmethod(), "return address should be in nmethod"); | |
| 1019 nmethod* nm = (nmethod*)cb; | |
| 1020 | |
| 1021 // Find frame of caller | |
| 1022 frame stub_fr = thread()->last_frame(); | |
| 1023 CodeBlob* stub_cb = stub_fr.cb(); | |
| 1024 assert(stub_cb->is_safepoint_stub(), "must be a safepoint stub"); | |
| 1025 RegisterMap map(thread(), true); | |
| 1026 frame caller_fr = stub_fr.sender(&map); | |
| 1027 | |
| 1028 // Should only be poll_return or poll | |
| 1029 assert( nm->is_at_poll_or_poll_return(real_return_addr), "should not be at call" ); | |
| 1030 | |
| 1031 // This is a poll immediately before a return. The exception handling code | |
| 1032 // has already had the effect of causing the return to occur, so the execution | |
| 1033 // will continue immediately after the call. In addition, the oopmap at the | |
| 1034 // return point does not mark the return value as an oop (if it is), so | |
| 1035 // it needs a handle here to be updated. | |
| 1036 if( nm->is_at_poll_return(real_return_addr) ) { | |
| 1037 // See if return type is an oop. | |
| 1038 bool return_oop = nm->method()->is_returning_oop(); | |
| 1039 Handle return_value; | |
| 1040 if (return_oop) { | |
| 1041 // The oop result has been saved on the stack together with all | |
| 1042 // the other registers. In order to preserve it over GCs we need | |
| 1043 // to keep it in a handle. | |
| 1044 oop result = caller_fr.saved_oop_result(&map); | |
| 1045 assert(result == NULL || result->is_oop(), "must be oop"); | |
| 1046 return_value = Handle(thread(), result); | |
| 1047 assert(Universe::heap()->is_in_or_null(result), "must be heap pointer"); | |
| 1048 } | |
| 1049 | |
| 1050 // Block the thread | |
| 1051 SafepointSynchronize::block(thread()); | |
| 1052 | |
| 1053 // restore oop result, if any | |
| 1054 if (return_oop) { | |
| 1055 caller_fr.set_saved_oop_result(&map, return_value()); | |
| 1056 } | |
| 1057 } | |
| 1058 | |
| 1059 // This is a safepoint poll. Verify the return address and block. | |
| 1060 else { | |
| 1061 set_at_poll_safepoint(true); | |
| 1062 | |
| 1063 // verify the blob built the "return address" correctly | |
| 1064 assert(real_return_addr == caller_fr.pc(), "must match"); | |
| 1065 | |
| 1066 // Block the thread | |
| 1067 SafepointSynchronize::block(thread()); | |
| 1068 set_at_poll_safepoint(false); | |
| 1069 | |
| 1070 // If we have a pending async exception deoptimize the frame | |
| 1071 // as otherwise we may never deliver it. | |
| 1072 if (thread()->has_async_condition()) { | |
| 1073 ThreadInVMfromJavaNoAsyncException __tiv(thread()); | |
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1074 Deoptimization::deoptimize_frame(thread(), caller_fr.id()); |
| 0 | 1075 } |
| 1076 | |
| 1077 // If an exception has been installed we must check for a pending deoptimization | |
| 1078 // Deoptimize frame if exception has been thrown. | |
| 1079 | |
| 1080 if (thread()->has_pending_exception() ) { | |
| 1081 RegisterMap map(thread(), true); | |
| 1082 frame caller_fr = stub_fr.sender(&map); | |
| 1083 if (caller_fr.is_deoptimized_frame()) { | |
| 1084 // The exception patch will destroy registers that are still | |
| 1085 // live and will be needed during deoptimization. Defer the | |
| 1086 // Async exception should have defered the exception until the | |
| 1087 // next safepoint which will be detected when we get into | |
| 1088 // the interpreter so if we have an exception now things | |
| 1089 // are messed up. | |
| 1090 | |
| 1091 fatal("Exception installed and deoptimization is pending"); | |
| 1092 } | |
| 1093 } | |
| 1094 } | |
| 1095 } | |
| 1096 | |
| 1097 | |
| 1098 // | |
| 1099 // Statistics & Instrumentations | |
| 1100 // | |
| 1101 SafepointSynchronize::SafepointStats* SafepointSynchronize::_safepoint_stats = NULL; | |
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1102 jlong SafepointSynchronize::_safepoint_begin_time = 0; |
| 0 | 1103 int SafepointSynchronize::_cur_stat_index = 0; |
| 1104 julong SafepointSynchronize::_safepoint_reasons[VM_Operation::VMOp_Terminating]; | |
| 1105 julong SafepointSynchronize::_coalesced_vmop_count = 0; | |
| 1106 jlong SafepointSynchronize::_max_sync_time = 0; | |
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1107 jlong SafepointSynchronize::_max_vmop_time = 0; |
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1108 float SafepointSynchronize::_ts_of_current_safepoint = 0.0f; |
| 0 | 1109 |
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1110 static jlong cleanup_end_time = 0; |
| 0 | 1111 static bool need_to_track_page_armed_status = false; |
| 1112 static bool init_done = false; | |
| 1113 | |
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1114 // Helper method to print the header. |
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1115 static void print_header() { |
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1116 tty->print(" vmop " |
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1117 "[threads: total initially_running wait_to_block] "); |
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1118 tty->print("[time: spin block sync cleanup vmop] "); |
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1119 |
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1120 // no page armed status printed out if it is always armed. |
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1121 if (need_to_track_page_armed_status) { |
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1122 tty->print("page_armed "); |
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1123 } |
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1124 |
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1125 tty->print_cr("page_trap_count"); |
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1126 } |
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1127 |
| 0 | 1128 void SafepointSynchronize::deferred_initialize_stat() { |
| 1129 if (init_done) return; | |
| 1130 | |
| 1131 if (PrintSafepointStatisticsCount <= 0) { | |
| 1132 fatal("Wrong PrintSafepointStatisticsCount"); | |
| 1133 } | |
| 1134 | |
| 1135 // If PrintSafepointStatisticsTimeout is specified, the statistics data will | |
| 1136 // be printed right away, in which case, _safepoint_stats will regress to | |
| 1137 // a single element array. Otherwise, it is a circular ring buffer with default | |
| 1138 // size of PrintSafepointStatisticsCount. | |
| 1139 int stats_array_size; | |
| 1140 if (PrintSafepointStatisticsTimeout > 0) { | |
| 1141 stats_array_size = 1; | |
| 1142 PrintSafepointStatistics = true; | |
| 1143 } else { | |
| 1144 stats_array_size = PrintSafepointStatisticsCount; | |
| 1145 } | |
| 1146 _safepoint_stats = (SafepointStats*)os::malloc(stats_array_size | |
| 1147 * sizeof(SafepointStats)); | |
| 1148 guarantee(_safepoint_stats != NULL, | |
| 1149 "not enough memory for safepoint instrumentation data"); | |
| 1150 | |
| 1151 if (UseCompilerSafepoints && DeferPollingPageLoopCount >= 0) { | |
| 1152 need_to_track_page_armed_status = true; | |
| 1153 } | |
| 1154 init_done = true; | |
| 1155 } | |
| 1156 | |
| 1157 void SafepointSynchronize::begin_statistics(int nof_threads, int nof_running) { | |
| 1003 | 1158 assert(init_done, "safepoint statistics array hasn't been initialized"); |
| 0 | 1159 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; |
| 1160 | |
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1161 spstat->_time_stamp = _ts_of_current_safepoint; |
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1162 |
| 0 | 1163 VM_Operation *op = VMThread::vm_operation(); |
| 1164 spstat->_vmop_type = (op != NULL ? op->type() : -1); | |
| 1165 if (op != NULL) { | |
| 1166 _safepoint_reasons[spstat->_vmop_type]++; | |
| 1167 } | |
| 1168 | |
| 1169 spstat->_nof_total_threads = nof_threads; | |
| 1170 spstat->_nof_initial_running_threads = nof_running; | |
| 1171 spstat->_nof_threads_hit_page_trap = 0; | |
| 1172 | |
| 1173 // Records the start time of spinning. The real time spent on spinning | |
| 1174 // will be adjusted when spin is done. Same trick is applied for time | |
| 1175 // spent on waiting for threads to block. | |
| 1176 if (nof_running != 0) { | |
| 1177 spstat->_time_to_spin = os::javaTimeNanos(); | |
| 1178 } else { | |
| 1179 spstat->_time_to_spin = 0; | |
| 1180 } | |
| 1181 } | |
| 1182 | |
| 1183 void SafepointSynchronize::update_statistics_on_spin_end() { | |
| 1184 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; | |
| 1185 | |
| 1186 jlong cur_time = os::javaTimeNanos(); | |
| 1187 | |
| 1188 spstat->_nof_threads_wait_to_block = _waiting_to_block; | |
| 1189 if (spstat->_nof_initial_running_threads != 0) { | |
| 1190 spstat->_time_to_spin = cur_time - spstat->_time_to_spin; | |
| 1191 } | |
| 1192 | |
| 1193 if (need_to_track_page_armed_status) { | |
| 1194 spstat->_page_armed = (PageArmed == 1); | |
| 1195 } | |
| 1196 | |
| 1197 // Records the start time of waiting for to block. Updated when block is done. | |
| 1198 if (_waiting_to_block != 0) { | |
| 1199 spstat->_time_to_wait_to_block = cur_time; | |
| 1200 } else { | |
| 1201 spstat->_time_to_wait_to_block = 0; | |
| 1202 } | |
| 1203 } | |
| 1204 | |
| 1205 void SafepointSynchronize::update_statistics_on_sync_end(jlong end_time) { | |
| 1206 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; | |
| 1207 | |
| 1208 if (spstat->_nof_threads_wait_to_block != 0) { | |
| 1209 spstat->_time_to_wait_to_block = end_time - | |
| 1210 spstat->_time_to_wait_to_block; | |
| 1211 } | |
| 1212 | |
| 1213 // Records the end time of sync which will be used to calculate the total | |
| 1214 // vm operation time. Again, the real time spending in syncing will be deducted | |
| 1215 // from the start of the sync time later when end_statistics is called. | |
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1216 spstat->_time_to_sync = end_time - _safepoint_begin_time; |
| 0 | 1217 if (spstat->_time_to_sync > _max_sync_time) { |
| 1218 _max_sync_time = spstat->_time_to_sync; | |
| 1219 } | |
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1220 |
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1221 spstat->_time_to_do_cleanups = end_time; |
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1222 } |
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1223 |
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1224 void SafepointSynchronize::update_statistics_on_cleanup_end(jlong end_time) { |
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1225 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; |
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1226 |
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1227 // Record how long spent in cleanup tasks. |
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1228 spstat->_time_to_do_cleanups = end_time - spstat->_time_to_do_cleanups; |
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1229 |
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1230 cleanup_end_time = end_time; |
| 0 | 1231 } |
| 1232 | |
| 1233 void SafepointSynchronize::end_statistics(jlong vmop_end_time) { | |
| 1234 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; | |
| 1235 | |
| 1236 // Update the vm operation time. | |
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1237 spstat->_time_to_exec_vmop = vmop_end_time - cleanup_end_time; |
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1238 if (spstat->_time_to_exec_vmop > _max_vmop_time) { |
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1239 _max_vmop_time = spstat->_time_to_exec_vmop; |
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1240 } |
| 0 | 1241 // Only the sync time longer than the specified |
| 1242 // PrintSafepointStatisticsTimeout will be printed out right away. | |
| 1243 // By default, it is -1 meaning all samples will be put into the list. | |
| 1244 if ( PrintSafepointStatisticsTimeout > 0) { | |
| 1245 if (spstat->_time_to_sync > PrintSafepointStatisticsTimeout * MICROUNITS) { | |
| 1246 print_statistics(); | |
| 1247 } | |
| 1248 } else { | |
| 1249 // The safepoint statistics will be printed out when the _safepoin_stats | |
| 1250 // array fills up. | |
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1251 if (_cur_stat_index == PrintSafepointStatisticsCount - 1) { |
| 0 | 1252 print_statistics(); |
| 1253 _cur_stat_index = 0; | |
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1254 } else { |
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1255 _cur_stat_index++; |
| 0 | 1256 } |
| 1257 } | |
| 1258 } | |
| 1259 | |
| 1260 void SafepointSynchronize::print_statistics() { | |
| 1261 SafepointStats* sstats = _safepoint_stats; | |
| 1262 | |
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1263 for (int index = 0; index <= _cur_stat_index; index++) { |
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1264 if (index % 30 == 0) { |
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1265 print_header(); |
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1266 } |
| 0 | 1267 sstats = &_safepoint_stats[index]; |
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1268 tty->print("%.3f: ", sstats->_time_stamp); |
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1269 tty->print("%-26s [" |
| 0 | 1270 INT32_FORMAT_W(8)INT32_FORMAT_W(11)INT32_FORMAT_W(15) |
|
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1271 " ] ", |
| 0 | 1272 sstats->_vmop_type == -1 ? "no vm operation" : |
| 1273 VM_Operation::name(sstats->_vmop_type), | |
| 1274 sstats->_nof_total_threads, | |
| 1275 sstats->_nof_initial_running_threads, | |
| 1276 sstats->_nof_threads_wait_to_block); | |
| 1277 // "/ MICROUNITS " is to convert the unit from nanos to millis. | |
|
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1278 tty->print(" [" |
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1279 INT64_FORMAT_W(6)INT64_FORMAT_W(6) |
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1280 INT64_FORMAT_W(6)INT64_FORMAT_W(6) |
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1281 INT64_FORMAT_W(6)" ] ", |
| 0 | 1282 sstats->_time_to_spin / MICROUNITS, |
| 1283 sstats->_time_to_wait_to_block / MICROUNITS, | |
| 1284 sstats->_time_to_sync / MICROUNITS, | |
|
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1285 sstats->_time_to_do_cleanups / MICROUNITS, |
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1286 sstats->_time_to_exec_vmop / MICROUNITS); |
| 0 | 1287 |
| 1288 if (need_to_track_page_armed_status) { | |
| 1289 tty->print(INT32_FORMAT" ", sstats->_page_armed); | |
| 1290 } | |
| 1291 tty->print_cr(INT32_FORMAT" ", sstats->_nof_threads_hit_page_trap); | |
| 1292 } | |
| 1293 } | |
| 1294 | |
| 1295 // This method will be called when VM exits. It will first call | |
| 1296 // print_statistics to print out the rest of the sampling. Then | |
| 1297 // it tries to summarize the sampling. | |
| 1298 void SafepointSynchronize::print_stat_on_exit() { | |
| 1299 if (_safepoint_stats == NULL) return; | |
| 1300 | |
| 1301 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; | |
| 1302 | |
| 1303 // During VM exit, end_statistics may not get called and in that | |
| 1304 // case, if the sync time is less than PrintSafepointStatisticsTimeout, | |
| 1305 // don't print it out. | |
| 1306 // Approximate the vm op time. | |
| 1307 _safepoint_stats[_cur_stat_index]._time_to_exec_vmop = | |
|
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1308 os::javaTimeNanos() - cleanup_end_time; |
| 0 | 1309 |
| 1310 if ( PrintSafepointStatisticsTimeout < 0 || | |
| 1311 spstat->_time_to_sync > PrintSafepointStatisticsTimeout * MICROUNITS) { | |
| 1312 print_statistics(); | |
| 1313 } | |
| 1314 tty->print_cr(""); | |
| 1315 | |
| 1316 // Print out polling page sampling status. | |
| 1317 if (!need_to_track_page_armed_status) { | |
| 1318 if (UseCompilerSafepoints) { | |
| 1319 tty->print_cr("Polling page always armed"); | |
| 1320 } | |
| 1321 } else { | |
| 1322 tty->print_cr("Defer polling page loop count = %d\n", | |
| 1323 DeferPollingPageLoopCount); | |
| 1324 } | |
| 1325 | |
| 1326 for (int index = 0; index < VM_Operation::VMOp_Terminating; index++) { | |
| 1327 if (_safepoint_reasons[index] != 0) { | |
| 1328 tty->print_cr("%-26s"UINT64_FORMAT_W(10), VM_Operation::name(index), | |
| 1329 _safepoint_reasons[index]); | |
| 1330 } | |
| 1331 } | |
| 1332 | |
| 1333 tty->print_cr(UINT64_FORMAT_W(5)" VM operations coalesced during safepoint", | |
| 1334 _coalesced_vmop_count); | |
| 1335 tty->print_cr("Maximum sync time "INT64_FORMAT_W(5)" ms", | |
| 1336 _max_sync_time / MICROUNITS); | |
|
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1337 tty->print_cr("Maximum vm operation time (except for Exit VM operation) " |
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1338 INT64_FORMAT_W(5)" ms", |
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1339 _max_vmop_time / MICROUNITS); |
| 0 | 1340 } |
| 1341 | |
| 1342 // ------------------------------------------------------------------------------------------------ | |
| 1343 // Non-product code | |
| 1344 | |
| 1345 #ifndef PRODUCT | |
| 1346 | |
| 1347 void SafepointSynchronize::print_state() { | |
| 1348 if (_state == _not_synchronized) { | |
| 1349 tty->print_cr("not synchronized"); | |
| 1350 } else if (_state == _synchronizing || _state == _synchronized) { | |
| 1351 tty->print_cr("State: %s", (_state == _synchronizing) ? "synchronizing" : | |
| 1352 "synchronized"); | |
| 1353 | |
| 1354 for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) { | |
| 1355 cur->safepoint_state()->print(); | |
| 1356 } | |
| 1357 } | |
| 1358 } | |
| 1359 | |
| 1360 void SafepointSynchronize::safepoint_msg(const char* format, ...) { | |
| 1361 if (ShowSafepointMsgs) { | |
| 1362 va_list ap; | |
| 1363 va_start(ap, format); | |
| 1364 tty->vprint_cr(format, ap); | |
| 1365 va_end(ap); | |
| 1366 } | |
| 1367 } | |
| 1368 | |
| 1369 #endif // !PRODUCT |