1.1 --- a/src/share/vm/services/memTracker.cpp Mon Jun 10 10:45:19 2013 -0400
1.2 +++ b/src/share/vm/services/memTracker.cpp Tue Jun 18 08:44:08 2013 -0400
1.3 @@ -69,6 +69,7 @@
1.4 volatile jint MemTracker::_pooled_recorder_count = 0;
1.5 volatile unsigned long MemTracker::_processing_generation = 0;
1.6 volatile bool MemTracker::_worker_thread_idle = false;
1.7 +volatile jint MemTracker::_pending_op_count = 0;
1.8 volatile bool MemTracker::_slowdown_calling_thread = false;
1.9 debug_only(intx MemTracker::_main_thread_tid = 0;)
1.10 NOT_PRODUCT(volatile jint MemTracker::_pending_recorder_count = 0;)
1.11 @@ -337,92 +338,14 @@
1.12 Atomic::inc(&_pooled_recorder_count);
1.13 }
1.14
1.15 -/*
1.16 - * This is the most important method in whole nmt implementation.
1.17 - *
1.18 - * Create a memory record.
1.19 - * 1. When nmt is in single-threaded bootstrapping mode, no lock is needed as VM
1.20 - * still in single thread mode.
1.21 - * 2. For all threads other than JavaThread, ThreadCritical is needed
1.22 - * to write to recorders to global recorder.
1.23 - * 3. For JavaThreads that are not longer visible by safepoint, also
1.24 - * need to take ThreadCritical and records are written to global
1.25 - * recorders, since these threads are NOT walked by Threads.do_thread().
1.26 - * 4. JavaThreads that are running in native state, have to transition
1.27 - * to VM state before writing to per-thread recorders.
1.28 - * 5. JavaThreads that are running in VM state do not need any lock and
1.29 - * records are written to per-thread recorders.
1.30 - * 6. For a thread has yet to attach VM 'Thread', they need to take
1.31 - * ThreadCritical to write to global recorder.
1.32 - *
1.33 - * Important note:
1.34 - * NO LOCK should be taken inside ThreadCritical lock !!!
1.35 - */
1.36 -void MemTracker::create_memory_record(address addr, MEMFLAGS flags,
1.37 - size_t size, address pc, Thread* thread) {
1.38 - assert(addr != NULL, "Sanity check");
1.39 - if (!shutdown_in_progress()) {
1.40 - // single thread, we just write records direct to global recorder,'
1.41 - // with any lock
1.42 - if (_state == NMT_bootstrapping_single_thread) {
1.43 - assert(_main_thread_tid == os::current_thread_id(), "wrong thread");
1.44 - thread = NULL;
1.45 - } else {
1.46 - if (thread == NULL) {
1.47 - // don't use Thread::current(), since it is possible that
1.48 - // the calling thread has yet to attach to VM 'Thread',
1.49 - // which will result assertion failure
1.50 - thread = ThreadLocalStorage::thread();
1.51 - }
1.52 - }
1.53 -
1.54 - if (thread != NULL) {
1.55 - // slow down all calling threads except NMT worker thread, so it
1.56 - // can catch up.
1.57 - if (_slowdown_calling_thread && thread != _worker_thread) {
1.58 - os::yield_all();
1.59 - }
1.60 -
1.61 - if (thread->is_Java_thread() && ((JavaThread*)thread)->is_safepoint_visible()) {
1.62 - JavaThread* java_thread = (JavaThread*)thread;
1.63 - JavaThreadState state = java_thread->thread_state();
1.64 - if (SafepointSynchronize::safepoint_safe(java_thread, state)) {
1.65 - // JavaThreads that are safepoint safe, can run through safepoint,
1.66 - // so ThreadCritical is needed to ensure no threads at safepoint create
1.67 - // new records while the records are being gathered and the sequence number is changing
1.68 - ThreadCritical tc;
1.69 - create_record_in_recorder(addr, flags, size, pc, java_thread);
1.70 - } else {
1.71 - create_record_in_recorder(addr, flags, size, pc, java_thread);
1.72 - }
1.73 - } else {
1.74 - // other threads, such as worker and watcher threads, etc. need to
1.75 - // take ThreadCritical to write to global recorder
1.76 - ThreadCritical tc;
1.77 - create_record_in_recorder(addr, flags, size, pc, NULL);
1.78 - }
1.79 - } else {
1.80 - if (_state == NMT_bootstrapping_single_thread) {
1.81 - // single thread, no lock needed
1.82 - create_record_in_recorder(addr, flags, size, pc, NULL);
1.83 - } else {
1.84 - // for thread has yet to attach VM 'Thread', we can not use VM mutex.
1.85 - // use native thread critical instead
1.86 - ThreadCritical tc;
1.87 - create_record_in_recorder(addr, flags, size, pc, NULL);
1.88 - }
1.89 - }
1.90 - }
1.91 -}
1.92 -
1.93 // write a record to proper recorder. No lock can be taken from this method
1.94 // down.
1.95 -void MemTracker::create_record_in_recorder(address addr, MEMFLAGS flags,
1.96 - size_t size, address pc, JavaThread* thread) {
1.97 +void MemTracker::write_tracking_record(address addr, MEMFLAGS flags,
1.98 + size_t size, jint seq, address pc, JavaThread* thread) {
1.99
1.100 MemRecorder* rc = get_thread_recorder(thread);
1.101 if (rc != NULL) {
1.102 - rc->record(addr, flags, size, pc);
1.103 + rc->record(addr, flags, size, seq, pc);
1.104 }
1.105 }
1.106
1.107 @@ -487,39 +410,43 @@
1.108 return;
1.109 }
1.110 }
1.111 - _sync_point_skip_count = 0;
1.112 {
1.113 // This method is running at safepoint, with ThreadCritical lock,
1.114 // it should guarantee that NMT is fully sync-ed.
1.115 ThreadCritical tc;
1.116
1.117 - SequenceGenerator::reset();
1.118 + // We can NOT execute NMT sync-point if there are pending tracking ops.
1.119 + if (_pending_op_count == 0) {
1.120 + SequenceGenerator::reset();
1.121 + _sync_point_skip_count = 0;
1.122
1.123 - // walk all JavaThreads to collect recorders
1.124 - SyncThreadRecorderClosure stc;
1.125 - Threads::threads_do(&stc);
1.126 + // walk all JavaThreads to collect recorders
1.127 + SyncThreadRecorderClosure stc;
1.128 + Threads::threads_do(&stc);
1.129
1.130 - _thread_count = stc.get_thread_count();
1.131 - MemRecorder* pending_recorders = get_pending_recorders();
1.132 + _thread_count = stc.get_thread_count();
1.133 + MemRecorder* pending_recorders = get_pending_recorders();
1.134
1.135 - if (_global_recorder != NULL) {
1.136 - _global_recorder->set_next(pending_recorders);
1.137 - pending_recorders = _global_recorder;
1.138 - _global_recorder = NULL;
1.139 + if (_global_recorder != NULL) {
1.140 + _global_recorder->set_next(pending_recorders);
1.141 + pending_recorders = _global_recorder;
1.142 + _global_recorder = NULL;
1.143 + }
1.144 +
1.145 + // see if NMT has too many outstanding recorder instances, it usually
1.146 + // means that worker thread is lagging behind in processing them.
1.147 + if (!AutoShutdownNMT) {
1.148 + _slowdown_calling_thread = (MemRecorder::_instance_count > MAX_RECORDER_THREAD_RATIO * _thread_count);
1.149 + }
1.150 +
1.151 + // check _worker_thread with lock to avoid racing condition
1.152 + if (_worker_thread != NULL) {
1.153 + _worker_thread->at_sync_point(pending_recorders, InstanceKlass::number_of_instance_classes());
1.154 + }
1.155 + assert(SequenceGenerator::peek() == 1, "Should not have memory activities during sync-point");
1.156 + } else {
1.157 + _sync_point_skip_count ++;
1.158 }
1.159 -
1.160 - // see if NMT has too many outstanding recorder instances, it usually
1.161 - // means that worker thread is lagging behind in processing them.
1.162 - if (!AutoShutdownNMT) {
1.163 - _slowdown_calling_thread = (MemRecorder::_instance_count > MAX_RECORDER_THREAD_RATIO * _thread_count);
1.164 - }
1.165 -
1.166 - // check _worker_thread with lock to avoid racing condition
1.167 - if (_worker_thread != NULL) {
1.168 - _worker_thread->at_sync_point(pending_recorders, InstanceKlass::number_of_instance_classes());
1.169 - }
1.170 -
1.171 - assert(SequenceGenerator::peek() == 1, "Should not have memory activities during sync-point");
1.172 }
1.173 }
1.174
1.175 @@ -708,3 +635,243 @@
1.176 }
1.177 #endif
1.178
1.179 +
1.180 +// Tracker Implementation
1.181 +
1.182 +/*
1.183 + * Create a tracker.
1.184 + * This is a fairly complicated constructor, as it has to make two important decisions:
1.185 + * 1) Does it need to take ThreadCritical lock to write tracking record
1.186 + * 2) Does it need to pre-reserve a sequence number for the tracking record
1.187 + *
1.188 + * The rules to determine if ThreadCritical is needed:
1.189 + * 1. When nmt is in single-threaded bootstrapping mode, no lock is needed as VM
1.190 + * still in single thread mode.
1.191 + * 2. For all threads other than JavaThread, ThreadCritical is needed
1.192 + * to write to recorders to global recorder.
1.193 + * 3. For JavaThreads that are no longer visible by safepoint, also
1.194 + * need to take ThreadCritical and records are written to global
1.195 + * recorders, since these threads are NOT walked by Threads.do_thread().
1.196 + * 4. JavaThreads that are running in safepoint-safe states do not stop
1.197 + * for safepoints, ThreadCritical lock should be taken to write
1.198 + * memory records.
1.199 + * 5. JavaThreads that are running in VM state do not need any lock and
1.200 + * records are written to per-thread recorders.
1.201 + * 6. For a thread has yet to attach VM 'Thread', they need to take
1.202 + * ThreadCritical to write to global recorder.
1.203 + *
1.204 + * The memory operations that need pre-reserve sequence numbers:
1.205 + * The memory operations that "release" memory blocks and the
1.206 + * operations can fail, need to pre-reserve sequence number. They
1.207 + * are realloc, uncommit and release.
1.208 + *
1.209 + * The reason for pre-reserve sequence number, is to prevent race condition:
1.210 + * Thread 1 Thread 2
1.211 + * <release>
1.212 + * <allocate>
1.213 + * <write allocate record>
1.214 + * <write release record>
1.215 + * if Thread 2 happens to obtain the memory address Thread 1 just released,
1.216 + * then NMT can mistakenly report the memory is free.
1.217 + *
1.218 + * Noticeably, free() does not need pre-reserve sequence number, because the call
1.219 + * does not fail, so we can alway write "release" record before the memory is actaully
1.220 + * freed.
1.221 + *
1.222 + * For realloc, uncommit and release, following coding pattern should be used:
1.223 + *
1.224 + * MemTracker::Tracker tkr = MemTracker::get_realloc_tracker();
1.225 + * ptr = ::realloc(...);
1.226 + * if (ptr == NULL) {
1.227 + * tkr.record(...)
1.228 + * } else {
1.229 + * tkr.discard();
1.230 + * }
1.231 + *
1.232 + * MemTracker::Tracker tkr = MemTracker::get_virtual_memory_uncommit_tracker();
1.233 + * if (uncommit(...)) {
1.234 + * tkr.record(...);
1.235 + * } else {
1.236 + * tkr.discard();
1.237 + * }
1.238 + *
1.239 + * MemTracker::Tracker tkr = MemTracker::get_virtual_memory_release_tracker();
1.240 + * if (release(...)) {
1.241 + * tkr.record(...);
1.242 + * } else {
1.243 + * tkr.discard();
1.244 + * }
1.245 + *
1.246 + * Since pre-reserved sequence number is only good for the generation that it is acquired,
1.247 + * when there is pending Tracker that reserved sequence number, NMT sync-point has
1.248 + * to be skipped to prevent from advancing generation. This is done by inc and dec
1.249 + * MemTracker::_pending_op_count, when MemTracker::_pending_op_count > 0, NMT sync-point is skipped.
1.250 + * Not all pre-reservation of sequence number will increment pending op count. For JavaThreads
1.251 + * that honor safepoints, safepoint can not occur during the memory operations, so the
1.252 + * pre-reserved sequence number won't cross the generation boundry.
1.253 + */
1.254 +MemTracker::Tracker::Tracker(MemoryOperation op, Thread* thr) {
1.255 + _op = NoOp;
1.256 + _seq = 0;
1.257 + if (MemTracker::is_on()) {
1.258 + _java_thread = NULL;
1.259 + _op = op;
1.260 +
1.261 + // figure out if ThreadCritical lock is needed to write this operation
1.262 + // to MemTracker
1.263 + if (MemTracker::is_single_threaded_bootstrap()) {
1.264 + thr = NULL;
1.265 + } else if (thr == NULL) {
1.266 + // don't use Thread::current(), since it is possible that
1.267 + // the calling thread has yet to attach to VM 'Thread',
1.268 + // which will result assertion failure
1.269 + thr = ThreadLocalStorage::thread();
1.270 + }
1.271 +
1.272 + if (thr != NULL) {
1.273 + // Check NMT load
1.274 + MemTracker::check_NMT_load(thr);
1.275 +
1.276 + if (thr->is_Java_thread() && ((JavaThread*)thr)->is_safepoint_visible()) {
1.277 + _java_thread = (JavaThread*)thr;
1.278 + JavaThreadState state = _java_thread->thread_state();
1.279 + // JavaThreads that are safepoint safe, can run through safepoint,
1.280 + // so ThreadCritical is needed to ensure no threads at safepoint create
1.281 + // new records while the records are being gathered and the sequence number is changing
1.282 + _need_thread_critical_lock =
1.283 + SafepointSynchronize::safepoint_safe(_java_thread, state);
1.284 + } else {
1.285 + _need_thread_critical_lock = true;
1.286 + }
1.287 + } else {
1.288 + _need_thread_critical_lock
1.289 + = !MemTracker::is_single_threaded_bootstrap();
1.290 + }
1.291 +
1.292 + // see if we need to pre-reserve sequence number for this operation
1.293 + if (_op == Realloc || _op == Uncommit || _op == Release) {
1.294 + if (_need_thread_critical_lock) {
1.295 + ThreadCritical tc;
1.296 + MemTracker::inc_pending_op_count();
1.297 + _seq = SequenceGenerator::next();
1.298 + } else {
1.299 + // for the threads that honor safepoints, no safepoint can occur
1.300 + // during the lifespan of tracker, so we don't need to increase
1.301 + // pending op count.
1.302 + _seq = SequenceGenerator::next();
1.303 + }
1.304 + }
1.305 + }
1.306 +}
1.307 +
1.308 +void MemTracker::Tracker::discard() {
1.309 + if (MemTracker::is_on() && _seq != 0) {
1.310 + if (_need_thread_critical_lock) {
1.311 + ThreadCritical tc;
1.312 + MemTracker::dec_pending_op_count();
1.313 + }
1.314 + _seq = 0;
1.315 + }
1.316 +}
1.317 +
1.318 +
1.319 +void MemTracker::Tracker::record(address old_addr, address new_addr, size_t size,
1.320 + MEMFLAGS flags, address pc) {
1.321 + assert(old_addr != NULL && new_addr != NULL, "Sanity check");
1.322 + assert(_op == Realloc || _op == NoOp, "Wrong call");
1.323 + if (MemTracker::is_on() && NMT_CAN_TRACK(flags) && _op != NoOp) {
1.324 + assert(_seq > 0, "Need pre-reserve sequence number");
1.325 + if (_need_thread_critical_lock) {
1.326 + ThreadCritical tc;
1.327 + // free old address, use pre-reserved sequence number
1.328 + MemTracker::write_tracking_record(old_addr, MemPointerRecord::free_tag(),
1.329 + 0, _seq, pc, _java_thread);
1.330 + MemTracker::write_tracking_record(new_addr, flags | MemPointerRecord::malloc_tag(),
1.331 + size, SequenceGenerator::next(), pc, _java_thread);
1.332 + // decrement MemTracker pending_op_count
1.333 + MemTracker::dec_pending_op_count();
1.334 + } else {
1.335 + // free old address, use pre-reserved sequence number
1.336 + MemTracker::write_tracking_record(old_addr, MemPointerRecord::free_tag(),
1.337 + 0, _seq, pc, _java_thread);
1.338 + MemTracker::write_tracking_record(new_addr, flags | MemPointerRecord::malloc_tag(),
1.339 + size, SequenceGenerator::next(), pc, _java_thread);
1.340 + }
1.341 + _seq = 0;
1.342 + }
1.343 +}
1.344 +
1.345 +void MemTracker::Tracker::record(address addr, size_t size, MEMFLAGS flags, address pc) {
1.346 + // OOM already?
1.347 + if (addr == NULL) return;
1.348 +
1.349 + if (MemTracker::is_on() && NMT_CAN_TRACK(flags) && _op != NoOp) {
1.350 + bool pre_reserved_seq = (_seq != 0);
1.351 + address pc = CALLER_CALLER_PC;
1.352 + MEMFLAGS orig_flags = flags;
1.353 +
1.354 + // or the tagging flags
1.355 + switch(_op) {
1.356 + case Malloc:
1.357 + flags |= MemPointerRecord::malloc_tag();
1.358 + break;
1.359 + case Free:
1.360 + flags = MemPointerRecord::free_tag();
1.361 + break;
1.362 + case Realloc:
1.363 + fatal("Use the other Tracker::record()");
1.364 + break;
1.365 + case Reserve:
1.366 + case ReserveAndCommit:
1.367 + flags |= MemPointerRecord::virtual_memory_reserve_tag();
1.368 + break;
1.369 + case Commit:
1.370 + flags = MemPointerRecord::virtual_memory_commit_tag();
1.371 + break;
1.372 + case Type:
1.373 + flags |= MemPointerRecord::virtual_memory_type_tag();
1.374 + break;
1.375 + case Uncommit:
1.376 + assert(pre_reserved_seq, "Need pre-reserve sequence number");
1.377 + flags = MemPointerRecord::virtual_memory_uncommit_tag();
1.378 + break;
1.379 + case Release:
1.380 + assert(pre_reserved_seq, "Need pre-reserve sequence number");
1.381 + flags = MemPointerRecord::virtual_memory_release_tag();
1.382 + break;
1.383 + case ArenaSize:
1.384 + // a bit of hack here, add a small postive offset to arena
1.385 + // address for its size record, so the size record is sorted
1.386 + // right after arena record.
1.387 + flags = MemPointerRecord::arena_size_tag();
1.388 + addr += sizeof(void*);
1.389 + break;
1.390 + case StackRelease:
1.391 + flags = MemPointerRecord::virtual_memory_release_tag();
1.392 + break;
1.393 + default:
1.394 + ShouldNotReachHere();
1.395 + }
1.396 +
1.397 + // write memory tracking record
1.398 + if (_need_thread_critical_lock) {
1.399 + ThreadCritical tc;
1.400 + if (_seq == 0) _seq = SequenceGenerator::next();
1.401 + MemTracker::write_tracking_record(addr, flags, size, _seq, pc, _java_thread);
1.402 + if (_op == ReserveAndCommit) {
1.403 + MemTracker::write_tracking_record(addr, orig_flags | MemPointerRecord::virtual_memory_commit_tag(),
1.404 + size, SequenceGenerator::next(), pc, _java_thread);
1.405 + }
1.406 + if (pre_reserved_seq) MemTracker::dec_pending_op_count();
1.407 + } else {
1.408 + if (_seq == 0) _seq = SequenceGenerator::next();
1.409 + MemTracker::write_tracking_record(addr, flags, size, _seq, pc, _java_thread);
1.410 + if (_op == ReserveAndCommit) {
1.411 + MemTracker::write_tracking_record(addr, orig_flags | MemPointerRecord::virtual_memory_commit_tag(),
1.412 + size, SequenceGenerator::next(), pc, _java_thread);
1.413 + }
1.414 + }
1.415 + _seq = 0;
1.416 + }
1.417 +}
1.418 +
