1 /*
2 * Copyright (c) 2012, 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 #include "precompiled.hpp"
25
26 #include "runtime/atomic.hpp"
27 #include "runtime/interfaceSupport.hpp"
28 #include "runtime/mutexLocker.hpp"
29 #include "runtime/safepoint.hpp"
30 #include "runtime/threadCritical.hpp"
31 #include "services/memPtr.hpp"
32 #include "services/memReporter.hpp"
33 #include "services/memTracker.hpp"
34 #include "utilities/decoder.hpp"
35 #include "utilities/globalDefinitions.hpp"
36
37 bool NMT_track_callsite = false;
38
39 // walk all 'known' threads at NMT sync point, and collect their recorders
40 void SyncThreadRecorderClosure::do_thread(Thread* thread) {
41 assert(SafepointSynchronize::is_at_safepoint(), "Safepoint required");
42 if (thread->is_Java_thread()) {
43 JavaThread* javaThread = (JavaThread*)thread;
44 MemRecorder* recorder = javaThread->get_recorder();
45 if (recorder != NULL) {
46 MemTracker::enqueue_pending_recorder(recorder);
47 javaThread->set_recorder(NULL);
48 }
49 }
50 _thread_count ++;
51 }
52
53
54 MemRecorder* MemTracker::_global_recorder = NULL;
55 MemSnapshot* MemTracker::_snapshot = NULL;
56 MemBaseline MemTracker::_baseline;
57 Mutex* MemTracker::_query_lock = NULL;
58 volatile MemRecorder* MemTracker::_merge_pending_queue = NULL;
59 volatile MemRecorder* MemTracker::_pooled_recorders = NULL;
60 MemTrackWorker* MemTracker::_worker_thread = NULL;
61 int MemTracker::_sync_point_skip_count = 0;
62 MemTracker::NMTLevel MemTracker::_tracking_level = MemTracker::NMT_off;
63 volatile MemTracker::NMTStates MemTracker::_state = NMT_uninited;
64 MemTracker::ShutdownReason MemTracker::_reason = NMT_shutdown_none;
65 int MemTracker::_thread_count = 255;
66 volatile jint MemTracker::_pooled_recorder_count = 0;
67 debug_only(intx MemTracker::_main_thread_tid = 0;)
68 NOT_PRODUCT(volatile jint MemTracker::_pending_recorder_count = 0;)
69
70 void MemTracker::init_tracking_options(const char* option_line) {
71 _tracking_level = NMT_off;
72 if (strcmp(option_line, "=summary") == 0) {
73 _tracking_level = NMT_summary;
74 } else if (strcmp(option_line, "=detail") == 0) {
75 _tracking_level = NMT_detail;
76 } else if (strcmp(option_line, "=off") != 0) {
77 vm_exit_during_initialization("Syntax error, expecting -XX:NativeMemoryTracking=[off|summary|detail]", NULL);
78 }
79 }
80
81 // first phase of bootstrapping, when VM is still in single-threaded mode.
82 void MemTracker::bootstrap_single_thread() {
83 if (_tracking_level > NMT_off) {
84 assert(_state == NMT_uninited, "wrong state");
85
86 // NMT is not supported with UseMallocOnly is on. NMT can NOT
87 // handle the amount of malloc data without significantly impacting
88 // runtime performance when this flag is on.
89 if (UseMallocOnly) {
90 shutdown(NMT_use_malloc_only);
91 return;
92 }
93
94 _query_lock = new (std::nothrow) Mutex(Monitor::max_nonleaf, "NMT_queryLock");
95 if (_query_lock == NULL) {
96 shutdown(NMT_out_of_memory);
97 return;
98 }
99
100 debug_only(_main_thread_tid = os::current_thread_id();)
101 _state = NMT_bootstrapping_single_thread;
102 NMT_track_callsite = (_tracking_level == NMT_detail && can_walk_stack());
103 }
104 }
105
106 // second phase of bootstrapping, when VM is about to or already entered multi-theaded mode.
107 void MemTracker::bootstrap_multi_thread() {
108 if (_tracking_level > NMT_off && _state == NMT_bootstrapping_single_thread) {
109 // create nmt lock for multi-thread execution
110 assert(_main_thread_tid == os::current_thread_id(), "wrong thread");
111 _state = NMT_bootstrapping_multi_thread;
112 NMT_track_callsite = (_tracking_level == NMT_detail && can_walk_stack());
113 }
114 }
115
116 // fully start nmt
117 void MemTracker::start() {
118 // Native memory tracking is off from command line option
119 if (_tracking_level == NMT_off || shutdown_in_progress()) return;
120
121 assert(_main_thread_tid == os::current_thread_id(), "wrong thread");
122 assert(_state == NMT_bootstrapping_multi_thread, "wrong state");
123
124 _snapshot = new (std::nothrow)MemSnapshot();
125 if (_snapshot != NULL && !_snapshot->out_of_memory()) {
126 if (start_worker()) {
127 _state = NMT_started;
128 NMT_track_callsite = (_tracking_level == NMT_detail && can_walk_stack());
129 return;
130 }
131 }
132
133 // fail to start native memory tracking, shut it down
134 shutdown(NMT_initialization);
135 }
136
137 /**
138 * Shutting down native memory tracking.
139 * We can not shutdown native memory tracking immediately, so we just
140 * setup shutdown pending flag, every native memory tracking component
141 * should orderly shut itself down.
142 *
143 * The shutdown sequences:
144 * 1. MemTracker::shutdown() sets MemTracker to shutdown pending state
145 * 2. Worker thread calls MemTracker::final_shutdown(), which transites
146 * MemTracker to final shutdown state.
147 * 3. At sync point, MemTracker does final cleanup, before sets memory
148 * tracking level to off to complete shutdown.
149 */
150 void MemTracker::shutdown(ShutdownReason reason) {
151 if (_tracking_level == NMT_off) return;
152
153 if (_state <= NMT_bootstrapping_single_thread) {
154 // we still in single thread mode, there is not contention
155 _state = NMT_shutdown_pending;
156 _reason = reason;
157 } else {
158 // we want to know who initialized shutdown
159 if ((jint)NMT_started == Atomic::cmpxchg((jint)NMT_shutdown_pending,
160 (jint*)&_state, (jint)NMT_started)) {
161 _reason = reason;
162 }
163 }
164 }
165
166 // final phase of shutdown
167 void MemTracker::final_shutdown() {
168 // delete all pending recorders and pooled recorders
169 delete_all_pending_recorders();
170 delete_all_pooled_recorders();
171
172 {
173 // shared baseline and snapshot are the only objects needed to
174 // create query results
175 MutexLockerEx locker(_query_lock, true);
176 // cleanup baseline data and snapshot
177 _baseline.clear();
178 delete _snapshot;
179 _snapshot = NULL;
180 }
181
182 // shutdown shared decoder instance, since it is only
183 // used by native memory tracking so far.
184 Decoder::shutdown();
185
186 MemTrackWorker* worker = NULL;
187 {
188 ThreadCritical tc;
189 // can not delete worker inside the thread critical
190 if (_worker_thread != NULL && Thread::current() == _worker_thread) {
191 worker = _worker_thread;
192 _worker_thread = NULL;
193 }
194 }
195 if (worker != NULL) {
196 delete worker;
197 }
198 _state = NMT_final_shutdown;
199 }
200
201 // delete all pooled recorders
202 void MemTracker::delete_all_pooled_recorders() {
203 // free all pooled recorders
204 volatile MemRecorder* cur_head = _pooled_recorders;
205 if (cur_head != NULL) {
206 MemRecorder* null_ptr = NULL;
207 while (cur_head != NULL && (void*)cur_head != Atomic::cmpxchg_ptr((void*)null_ptr,
208 (void*)&_pooled_recorders, (void*)cur_head)) {
209 cur_head = _pooled_recorders;
210 }
211 if (cur_head != NULL) {
212 delete cur_head;
213 _pooled_recorder_count = 0;
214 }
215 }
216 }
217
218 // delete all recorders in pending queue
219 void MemTracker::delete_all_pending_recorders() {
220 // free all pending recorders
221 MemRecorder* pending_head = get_pending_recorders();
222 if (pending_head != NULL) {
223 delete pending_head;
224 }
225 }
226
227 /*
228 * retrieve per-thread recorder of specified thread.
229 * if thread == NULL, it means global recorder
230 */
231 MemRecorder* MemTracker::get_thread_recorder(JavaThread* thread) {
232 if (shutdown_in_progress()) return NULL;
233
234 MemRecorder* rc;
235 if (thread == NULL) {
236 rc = _global_recorder;
237 } else {
238 rc = thread->get_recorder();
239 }
240
241 if (rc != NULL && rc->is_full()) {
242 enqueue_pending_recorder(rc);
243 rc = NULL;
244 }
245
246 if (rc == NULL) {
247 rc = get_new_or_pooled_instance();
248 if (thread == NULL) {
249 _global_recorder = rc;
250 } else {
251 thread->set_recorder(rc);
252 }
253 }
254 return rc;
255 }
256
257 /*
258 * get a per-thread recorder from pool, or create a new one if
259 * there is not one available.
260 */
261 MemRecorder* MemTracker::get_new_or_pooled_instance() {
262 MemRecorder* cur_head = const_cast<MemRecorder*> (_pooled_recorders);
263 if (cur_head == NULL) {
264 MemRecorder* rec = new (std::nothrow)MemRecorder();
265 if (rec == NULL || rec->out_of_memory()) {
266 shutdown(NMT_out_of_memory);
267 if (rec != NULL) {
268 delete rec;
269 rec = NULL;
270 }
271 }
272 return rec;
273 } else {
274 MemRecorder* next_head = cur_head->next();
275 if ((void*)cur_head != Atomic::cmpxchg_ptr((void*)next_head, (void*)&_pooled_recorders,
276 (void*)cur_head)) {
277 return get_new_or_pooled_instance();
278 }
279 cur_head->set_next(NULL);
280 Atomic::dec(&_pooled_recorder_count);
281 debug_only(cur_head->set_generation();)
282 return cur_head;
283 }
284 }
285
286 /*
287 * retrieve all recorders in pending queue, and empty the queue
288 */
289 MemRecorder* MemTracker::get_pending_recorders() {
290 MemRecorder* cur_head = const_cast<MemRecorder*>(_merge_pending_queue);
291 MemRecorder* null_ptr = NULL;
292 while ((void*)cur_head != Atomic::cmpxchg_ptr((void*)null_ptr, (void*)&_merge_pending_queue,
293 (void*)cur_head)) {
294 cur_head = const_cast<MemRecorder*>(_merge_pending_queue);
295 }
296 NOT_PRODUCT(Atomic::store(0, &_pending_recorder_count));
297 return cur_head;
298 }
299
300 /*
301 * release a recorder to recorder pool.
302 */
303 void MemTracker::release_thread_recorder(MemRecorder* rec) {
304 assert(rec != NULL, "null recorder");
305 // we don't want to pool too many recorders
306 rec->set_next(NULL);
307 if (shutdown_in_progress() || _pooled_recorder_count > _thread_count * 2) {
308 delete rec;
309 return;
310 }
311
312 rec->clear();
313 MemRecorder* cur_head = const_cast<MemRecorder*>(_pooled_recorders);
314 rec->set_next(cur_head);
315 while ((void*)cur_head != Atomic::cmpxchg_ptr((void*)rec, (void*)&_pooled_recorders,
316 (void*)cur_head)) {
317 cur_head = const_cast<MemRecorder*>(_pooled_recorders);
318 rec->set_next(cur_head);
319 }
320 Atomic::inc(&_pooled_recorder_count);
321 }
322
323 /*
324 * This is the most important method in whole nmt implementation.
325 *
326 * Create a memory record.
327 * 1. When nmt is in single-threaded bootstrapping mode, no lock is needed as VM
328 * still in single thread mode.
329 * 2. For all threads other than JavaThread, ThreadCritical is needed
330 * to write to recorders to global recorder.
331 * 3. For JavaThreads that are not longer visible by safepoint, also
332 * need to take ThreadCritical and records are written to global
333 * recorders, since these threads are NOT walked by Threads.do_thread().
334 * 4. JavaThreads that are running in native state, have to transition
335 * to VM state before writing to per-thread recorders.
336 * 5. JavaThreads that are running in VM state do not need any lock and
337 * records are written to per-thread recorders.
338 * 6. For a thread has yet to attach VM 'Thread', they need to take
339 * ThreadCritical to write to global recorder.
340 *
341 * Important note:
342 * NO LOCK should be taken inside ThreadCritical lock !!!
343 */
344 void MemTracker::create_memory_record(address addr, MEMFLAGS flags,
345 size_t size, address pc, Thread* thread) {
346 assert(addr != NULL, "Sanity check");
347 if (!shutdown_in_progress()) {
348 // single thread, we just write records direct to global recorder,'
349 // with any lock
350 if (_state == NMT_bootstrapping_single_thread) {
351 assert(_main_thread_tid == os::current_thread_id(), "wrong thread");
352 thread = NULL;
353 } else {
354 if (thread == NULL) {
355 // don't use Thread::current(), since it is possible that
356 // the calling thread has yet to attach to VM 'Thread',
357 // which will result assertion failure
358 thread = ThreadLocalStorage::thread();
359 }
360 }
361
362 if (thread != NULL) {
363 if (thread->is_Java_thread() && ((JavaThread*)thread)->is_safepoint_visible()) {
364 JavaThread* java_thread = (JavaThread*)thread;
365 JavaThreadState state = java_thread->thread_state();
366 if (SafepointSynchronize::safepoint_safe(java_thread, state)) {
367 // JavaThreads that are safepoint safe, can run through safepoint,
368 // so ThreadCritical is needed to ensure no threads at safepoint create
369 // new records while the records are being gathered and the sequence number is changing
370 ThreadCritical tc;
371 create_record_in_recorder(addr, flags, size, pc, java_thread);
372 } else {
373 create_record_in_recorder(addr, flags, size, pc, java_thread);
374 }
375 } else {
376 // other threads, such as worker and watcher threads, etc. need to
377 // take ThreadCritical to write to global recorder
378 ThreadCritical tc;
379 create_record_in_recorder(addr, flags, size, pc, NULL);
380 }
381 } else {
382 if (_state == NMT_bootstrapping_single_thread) {
383 // single thread, no lock needed
384 create_record_in_recorder(addr, flags, size, pc, NULL);
385 } else {
386 // for thread has yet to attach VM 'Thread', we can not use VM mutex.
387 // use native thread critical instead
388 ThreadCritical tc;
389 create_record_in_recorder(addr, flags, size, pc, NULL);
390 }
391 }
392 }
393 }
394
395 // write a record to proper recorder. No lock can be taken from this method
396 // down.
397 void MemTracker::create_record_in_recorder(address addr, MEMFLAGS flags,
398 size_t size, address pc, JavaThread* thread) {
399
400 MemRecorder* rc = get_thread_recorder(thread);
401 if (rc != NULL) {
402 rc->record(addr, flags, size, pc);
403 }
404 }
405
406 /**
407 * enqueue a recorder to pending queue
408 */
409 void MemTracker::enqueue_pending_recorder(MemRecorder* rec) {
410 assert(rec != NULL, "null recorder");
411
412 // we are shutting down, so just delete it
413 if (shutdown_in_progress()) {
414 rec->set_next(NULL);
415 delete rec;
416 return;
417 }
418
419 MemRecorder* cur_head = const_cast<MemRecorder*>(_merge_pending_queue);
420 rec->set_next(cur_head);
421 while ((void*)cur_head != Atomic::cmpxchg_ptr((void*)rec, (void*)&_merge_pending_queue,
422 (void*)cur_head)) {
423 cur_head = const_cast<MemRecorder*>(_merge_pending_queue);
424 rec->set_next(cur_head);
425 }
426 NOT_PRODUCT(Atomic::inc(&_pending_recorder_count);)
427 }
428
429 /*
430 * The method is called at global safepoint
431 * during it synchronization process.
432 * 1. enqueue all JavaThreads' per-thread recorders
433 * 2. enqueue global recorder
434 * 3. retrieve all pending recorders
435 * 4. reset global sequence number generator
436 * 5. call worker's sync
437 */
438 #define MAX_SAFEPOINTS_TO_SKIP 128
439 #define SAFE_SEQUENCE_THRESHOLD 30
440 #define HIGH_GENERATION_THRESHOLD 60
441
442 void MemTracker::sync() {
443 assert(_tracking_level > NMT_off, "NMT is not enabled");
444 assert(SafepointSynchronize::is_at_safepoint(), "Safepoint required");
445
446 // Some GC tests hit large number of safepoints in short period of time
447 // without meaningful activities. We should prevent going to
448 // sync point in these cases, which can potentially exhaust generation buffer.
449 // Here is the factots to determine if we should go into sync point:
450 // 1. not to overflow sequence number
451 // 2. if we are in danger to overflow generation buffer
452 // 3. how many safepoints we already skipped sync point
453 if (_state == NMT_started) {
454 // worker thread is not ready, no one can manage generation
455 // buffer, so skip this safepoint
456 if (_worker_thread == NULL) return;
457
458 if (_sync_point_skip_count < MAX_SAFEPOINTS_TO_SKIP) {
459 int per_seq_in_use = SequenceGenerator::peek() * 100 / max_jint;
460 int per_gen_in_use = _worker_thread->generations_in_use() * 100 / MAX_GENERATIONS;
461 if (per_seq_in_use < SAFE_SEQUENCE_THRESHOLD && per_gen_in_use >= HIGH_GENERATION_THRESHOLD) {
462 _sync_point_skip_count ++;
463 return;
464 }
465 }
466 _sync_point_skip_count = 0;
467 {
468 // This method is running at safepoint, with ThreadCritical lock,
469 // it should guarantee that NMT is fully sync-ed.
470 ThreadCritical tc;
471
472 SequenceGenerator::reset();
473
474 // walk all JavaThreads to collect recorders
475 SyncThreadRecorderClosure stc;
476 Threads::threads_do(&stc);
477
478 _thread_count = stc.get_thread_count();
479 MemRecorder* pending_recorders = get_pending_recorders();
480
481 if (_global_recorder != NULL) {
482 _global_recorder->set_next(pending_recorders);
483 pending_recorders = _global_recorder;
484 _global_recorder = NULL;
485 }
486 // check _worker_thread with lock to avoid racing condition
487 if (_worker_thread != NULL) {
488 _worker_thread->at_sync_point(pending_recorders);
489 }
490
491 assert(SequenceGenerator::peek() == 1, "Should not have memory activities during sync-point");
492 }
493 }
494
495 // now, it is the time to shut whole things off
496 if (_state == NMT_final_shutdown) {
497 // walk all JavaThreads to delete all recorders
498 SyncThreadRecorderClosure stc;
499 Threads::threads_do(&stc);
500 // delete global recorder
501 {
502 ThreadCritical tc;
503 if (_global_recorder != NULL) {
504 delete _global_recorder;
505 _global_recorder = NULL;
506 }
507 }
508 MemRecorder* pending_recorders = get_pending_recorders();
509 if (pending_recorders != NULL) {
510 delete pending_recorders;
511 }
512 // try at a later sync point to ensure MemRecorder instance drops to zero to
513 // completely shutdown NMT
514 if (MemRecorder::_instance_count == 0) {
515 _state = NMT_shutdown;
516 _tracking_level = NMT_off;
517 }
518 }
519 }
520
521 /*
522 * Start worker thread.
523 */
524 bool MemTracker::start_worker() {
525 assert(_worker_thread == NULL, "Just Check");
526 _worker_thread = new (std::nothrow) MemTrackWorker();
527 if (_worker_thread == NULL || _worker_thread->has_error()) {
528 shutdown(NMT_initialization);
529 return false;
530 }
531 _worker_thread->start();
532 return true;
533 }
534
535 /*
536 * We need to collect a JavaThread's per-thread recorder
537 * before it exits.
538 */
539 void MemTracker::thread_exiting(JavaThread* thread) {
540 if (is_on()) {
541 MemRecorder* rec = thread->get_recorder();
542 if (rec != NULL) {
543 enqueue_pending_recorder(rec);
544 thread->set_recorder(NULL);
545 }
546 }
547 }
548
549 // baseline current memory snapshot
550 bool MemTracker::baseline() {
551 MutexLockerEx lock(_query_lock, true);
552 MemSnapshot* snapshot = get_snapshot();
553 if (snapshot != NULL) {
554 return _baseline.baseline(*snapshot, false);
555 }
556 return false;
557 }
558
559 // print memory usage from current snapshot
560 bool MemTracker::print_memory_usage(BaselineOutputer& out, size_t unit, bool summary_only) {
561 MemBaseline baseline;
562 MutexLockerEx lock(_query_lock, true);
563 MemSnapshot* snapshot = get_snapshot();
564 if (snapshot != NULL && baseline.baseline(*snapshot, summary_only)) {
565 BaselineReporter reporter(out, unit);
566 reporter.report_baseline(baseline, summary_only);
567 return true;
568 }
569 return false;
570 }
571
572 // compare memory usage between current snapshot and baseline
573 bool MemTracker::compare_memory_usage(BaselineOutputer& out, size_t unit, bool summary_only) {
574 MutexLockerEx lock(_query_lock, true);
575 if (_baseline.baselined()) {
576 MemBaseline baseline;
577 MemSnapshot* snapshot = get_snapshot();
578 if (snapshot != NULL && baseline.baseline(*snapshot, summary_only)) {
579 BaselineReporter reporter(out, unit);
580 reporter.diff_baselines(baseline, _baseline, summary_only);
581 return true;
582 }
583 }
584 return false;
585 }
586
587 #ifndef PRODUCT
588 void MemTracker::walk_stack(int toSkip, char* buf, int len) {
589 int cur_len = 0;
590 char tmp[1024];
591 address pc;
592
593 while (cur_len < len) {
594 pc = os::get_caller_pc(toSkip + 1);
595 if (pc != NULL && os::dll_address_to_function_name(pc, tmp, sizeof(tmp), NULL)) {
596 jio_snprintf(&buf[cur_len], (len - cur_len), "%s\n", tmp);
597 cur_len = (int)strlen(buf);
598 } else {
599 buf[cur_len] = '\0';
600 break;
601 }
602 toSkip ++;
603 }
604 }
605
606 void MemTracker::print_tracker_stats(outputStream* st) {
607 st->print_cr("\nMemory Tracker Stats:");
608 st->print_cr("\tMax sequence number = %d", SequenceGenerator::max_seq_num());
609 st->print_cr("\tthead count = %d", _thread_count);
610 st->print_cr("\tArena instance = %d", Arena::_instance_count);
611 st->print_cr("\tpooled recorder count = %d", _pooled_recorder_count);
612 st->print_cr("\tqueued recorder count = %d", _pending_recorder_count);
613 st->print_cr("\tmemory recorder instance count = %d", MemRecorder::_instance_count);
614 if (_worker_thread != NULL) {
615 st->print_cr("\tWorker thread:");
616 st->print_cr("\t\tSync point count = %d", _worker_thread->_sync_point_count);
617 st->print_cr("\t\tpending recorder count = %d", _worker_thread->count_pending_recorders());
618 st->print_cr("\t\tmerge count = %d", _worker_thread->_merge_count);
619 } else {
620 st->print_cr("\tWorker thread is not started");
621 }
622 st->print_cr(" ");
623
624 if (_snapshot != NULL) {
625 _snapshot->print_snapshot_stats(st);
626 } else {
627 st->print_cr("No snapshot");
628 }
629 }
630 #endif
631