--- a/hotspot/src/share/vm/services/memTracker.cpp Tue Aug 05 14:18:44 2014 +0000
+++ b/hotspot/src/share/vm/services/memTracker.cpp Thu Aug 07 12:18:58 2014 -0700
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012, 2014, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@@ -23,862 +23,308 @@
*/
#include "precompiled.hpp"
-#include "oops/instanceKlass.hpp"
-#include "runtime/atomic.inline.hpp"
-#include "runtime/interfaceSupport.hpp"
-#include "runtime/mutexLocker.hpp"
-#include "runtime/safepoint.hpp"
-#include "runtime/threadCritical.hpp"
-#include "runtime/thread.inline.hpp"
-#include "runtime/vm_operations.hpp"
-#include "services/memPtr.hpp"
+#include "runtime/mutex.hpp"
+#include "services/memBaseline.hpp"
#include "services/memReporter.hpp"
+#include "services/mallocTracker.inline.hpp"
#include "services/memTracker.hpp"
-#include "utilities/decoder.hpp"
#include "utilities/defaultStream.hpp"
-#include "utilities/globalDefinitions.hpp"
-bool NMT_track_callsite = false;
+#ifdef SOLARIS
+ volatile bool NMT_stack_walkable = false;
+#else
+ volatile bool NMT_stack_walkable = true;
+#endif
-// walk all 'known' threads at NMT sync point, and collect their recorders
-void SyncThreadRecorderClosure::do_thread(Thread* thread) {
- assert(SafepointSynchronize::is_at_safepoint(), "Safepoint required");
- if (thread->is_Java_thread()) {
- JavaThread* javaThread = (JavaThread*)thread;
- MemRecorder* recorder = javaThread->get_recorder();
- if (recorder != NULL) {
- MemTracker::enqueue_pending_recorder(recorder);
- javaThread->set_recorder(NULL);
- }
- }
- _thread_count ++;
-}
+volatile NMT_TrackingLevel MemTracker::_tracking_level = NMT_unknown;
+NMT_TrackingLevel MemTracker::_cmdline_tracking_level = NMT_unknown;
+
+NativeCallStack emptyStack(0, false);
+
+MemBaseline MemTracker::_baseline;
+Mutex* MemTracker::_query_lock = NULL;
+bool MemTracker::_is_nmt_env_valid = true;
-MemRecorder* volatile MemTracker::_global_recorder = NULL;
-MemSnapshot* MemTracker::_snapshot = NULL;
-MemBaseline MemTracker::_baseline;
-Mutex* MemTracker::_query_lock = NULL;
-MemRecorder* volatile MemTracker::_merge_pending_queue = NULL;
-MemRecorder* volatile MemTracker::_pooled_recorders = NULL;
-MemTrackWorker* MemTracker::_worker_thread = NULL;
-int MemTracker::_sync_point_skip_count = 0;
-MemTracker::NMTLevel MemTracker::_tracking_level = MemTracker::NMT_off;
-volatile MemTracker::NMTStates MemTracker::_state = NMT_uninited;
-MemTracker::ShutdownReason MemTracker::_reason = NMT_shutdown_none;
-int MemTracker::_thread_count = 255;
-volatile jint MemTracker::_pooled_recorder_count = 0;
-volatile unsigned long MemTracker::_processing_generation = 0;
-volatile bool MemTracker::_worker_thread_idle = false;
-volatile jint MemTracker::_pending_op_count = 0;
-volatile bool MemTracker::_slowdown_calling_thread = false;
-debug_only(intx MemTracker::_main_thread_tid = 0;)
-NOT_PRODUCT(volatile jint MemTracker::_pending_recorder_count = 0;)
-
-void MemTracker::init_tracking_options(const char* option_line) {
- _tracking_level = NMT_off;
- if (strcmp(option_line, "=summary") == 0) {
- _tracking_level = NMT_summary;
- } else if (strcmp(option_line, "=detail") == 0) {
- // detail relies on a stack-walking ability that may not
- // be available depending on platform and/or compiler flags
+NMT_TrackingLevel MemTracker::init_tracking_level() {
+ NMT_TrackingLevel level = NMT_off;
+ char buf[64];
+ char nmt_option[64];
+ jio_snprintf(buf, sizeof(buf), "NMT_LEVEL_%d", os::current_process_id());
+ if (os::getenv(buf, nmt_option, sizeof(nmt_option))) {
+ if (strcmp(nmt_option, "summary") == 0) {
+ level = NMT_summary;
+ } else if (strcmp(nmt_option, "detail") == 0) {
#if PLATFORM_NATIVE_STACK_WALKING_SUPPORTED
- _tracking_level = NMT_detail;
+ level = NMT_detail;
#else
- jio_fprintf(defaultStream::error_stream(),
- "NMT detail is not supported on this platform. Using NMT summary instead.\n");
- _tracking_level = NMT_summary;
-#endif
- } else if (strcmp(option_line, "=off") != 0) {
- vm_exit_during_initialization("Syntax error, expecting -XX:NativeMemoryTracking=[off|summary|detail]", NULL);
- }
-}
-
-// first phase of bootstrapping, when VM is still in single-threaded mode.
-void MemTracker::bootstrap_single_thread() {
- if (_tracking_level > NMT_off) {
- assert(_state == NMT_uninited, "wrong state");
-
- // NMT is not supported with UseMallocOnly is on. NMT can NOT
- // handle the amount of malloc data without significantly impacting
- // runtime performance when this flag is on.
- if (UseMallocOnly) {
- shutdown(NMT_use_malloc_only);
- return;
+ level = NMT_summary;
+#endif // PLATFORM_NATIVE_STACK_WALKING_SUPPORTED
+ } else if (strcmp(nmt_option, "off") != 0) {
+ // The option value is invalid
+ _is_nmt_env_valid = false;
}
- _query_lock = new (std::nothrow) Mutex(Monitor::max_nonleaf, "NMT_queryLock");
- if (_query_lock == NULL) {
- shutdown(NMT_out_of_memory);
- return;
- }
+ // Remove the environment variable to avoid leaking to child processes
+ os::unsetenv(buf);
+ }
- debug_only(_main_thread_tid = os::current_thread_id();)
- _state = NMT_bootstrapping_single_thread;
- NMT_track_callsite = (_tracking_level == NMT_detail && can_walk_stack());
+ if (!MallocTracker::initialize(level) ||
+ !VirtualMemoryTracker::initialize(level)) {
+ level = NMT_off;
}
+ return level;
}
-// second phase of bootstrapping, when VM is about to or already entered multi-theaded mode.
-void MemTracker::bootstrap_multi_thread() {
- if (_tracking_level > NMT_off && _state == NMT_bootstrapping_single_thread) {
- // create nmt lock for multi-thread execution
- assert(_main_thread_tid == os::current_thread_id(), "wrong thread");
- _state = NMT_bootstrapping_multi_thread;
- NMT_track_callsite = (_tracking_level == NMT_detail && can_walk_stack());
- }
-}
-
-// fully start nmt
-void MemTracker::start() {
- // Native memory tracking is off from command line option
- if (_tracking_level == NMT_off || shutdown_in_progress()) return;
-
- assert(_main_thread_tid == os::current_thread_id(), "wrong thread");
- assert(_state == NMT_bootstrapping_multi_thread, "wrong state");
-
- _snapshot = new (std::nothrow)MemSnapshot();
- if (_snapshot != NULL) {
- if (!_snapshot->out_of_memory() && start_worker(_snapshot)) {
- _state = NMT_started;
- NMT_track_callsite = (_tracking_level == NMT_detail && can_walk_stack());
- return;
- }
-
- delete _snapshot;
- _snapshot = NULL;
- }
-
- // fail to start native memory tracking, shut it down
- shutdown(NMT_initialization);
-}
-
-/**
- * Shutting down native memory tracking.
- * We can not shutdown native memory tracking immediately, so we just
- * setup shutdown pending flag, every native memory tracking component
- * should orderly shut itself down.
- *
- * The shutdown sequences:
- * 1. MemTracker::shutdown() sets MemTracker to shutdown pending state
- * 2. Worker thread calls MemTracker::final_shutdown(), which transites
- * MemTracker to final shutdown state.
- * 3. At sync point, MemTracker does final cleanup, before sets memory
- * tracking level to off to complete shutdown.
- */
-void MemTracker::shutdown(ShutdownReason reason) {
- if (_tracking_level == NMT_off) return;
-
- if (_state <= NMT_bootstrapping_single_thread) {
- // we still in single thread mode, there is not contention
- _state = NMT_shutdown_pending;
- _reason = reason;
- } else {
- // we want to know who initialized shutdown
- if ((jint)NMT_started == Atomic::cmpxchg((jint)NMT_shutdown_pending,
- (jint*)&_state, (jint)NMT_started)) {
- _reason = reason;
- }
- }
-}
-
-// final phase of shutdown
-void MemTracker::final_shutdown() {
- // delete all pending recorders and pooled recorders
- delete_all_pending_recorders();
- delete_all_pooled_recorders();
-
- {
- // shared baseline and snapshot are the only objects needed to
- // create query results
- MutexLockerEx locker(_query_lock, true);
- // cleanup baseline data and snapshot
- _baseline.clear();
- delete _snapshot;
- _snapshot = NULL;
- }
-
- // shutdown shared decoder instance, since it is only
- // used by native memory tracking so far.
- Decoder::shutdown();
-
- MemTrackWorker* worker = NULL;
- {
- ThreadCritical tc;
- // can not delete worker inside the thread critical
- if (_worker_thread != NULL && Thread::current() == _worker_thread) {
- worker = _worker_thread;
- _worker_thread = NULL;
- }
- }
- if (worker != NULL) {
- delete worker;
- }
- _state = NMT_final_shutdown;
-}
-
-// delete all pooled recorders
-void MemTracker::delete_all_pooled_recorders() {
- // free all pooled recorders
- MemRecorder* volatile cur_head = _pooled_recorders;
- if (cur_head != NULL) {
- MemRecorder* null_ptr = NULL;
- while (cur_head != NULL && (void*)cur_head != Atomic::cmpxchg_ptr((void*)null_ptr,
- (void*)&_pooled_recorders, (void*)cur_head)) {
- cur_head = _pooled_recorders;
- }
- if (cur_head != NULL) {
- delete cur_head;
- _pooled_recorder_count = 0;
+void MemTracker::init() {
+ if (tracking_level() >= NMT_summary) {
+ _query_lock = new (std::nothrow) Mutex(Monitor::max_nonleaf, "NMT_queryLock");
+ // Already OOM. It is unlikely, but still have to handle it.
+ if (_query_lock == NULL) {
+ shutdown();
}
}
}
-// delete all recorders in pending queue
-void MemTracker::delete_all_pending_recorders() {
- // free all pending recorders
- MemRecorder* pending_head = get_pending_recorders();
- if (pending_head != NULL) {
- delete pending_head;
+bool MemTracker::check_launcher_nmt_support(const char* value) {
+ if (strcmp(value, "=detail") == 0) {
+#if !PLATFORM_NATIVE_STACK_WALKING_SUPPORTED
+ jio_fprintf(defaultStream::error_stream(),
+ "NMT detail is not supported on this platform. Using NMT summary instead.\n");
+ if (MemTracker::tracking_level() != NMT_summary) {
+ return false;
+ }
+#else
+ if (MemTracker::tracking_level() != NMT_detail) {
+ return false;
+ }
+#endif
+ } else if (strcmp(value, "=summary") == 0) {
+ if (MemTracker::tracking_level() != NMT_summary) {
+ return false;
+ }
+ } else if (strcmp(value, "=off") == 0) {
+ if (MemTracker::tracking_level() != NMT_off) {
+ return false;
+ }
+ } else {
+ _is_nmt_env_valid = false;
+ }
+
+ return true;
+}
+
+bool MemTracker::verify_nmt_option() {
+ return _is_nmt_env_valid;
+}
+
+void* MemTracker::malloc_base(void* memblock) {
+ return MallocTracker::get_base(memblock);
+}
+
+void Tracker::record(address addr, size_t size) {
+ if (MemTracker::tracking_level() < NMT_summary) return;
+ switch(_type) {
+ case uncommit:
+ VirtualMemoryTracker::remove_uncommitted_region(addr, size);
+ break;
+ case release:
+ VirtualMemoryTracker::remove_released_region(addr, size);
+ break;
+ default:
+ ShouldNotReachHere();
}
}
-/*
- * retrieve per-thread recorder of specified thread.
- * if thread == NULL, it means global recorder
- */
-MemRecorder* MemTracker::get_thread_recorder(JavaThread* thread) {
- if (shutdown_in_progress()) return NULL;
+
+// Shutdown can only be issued via JCmd, and NMT JCmd is serialized
+// by lock
+void MemTracker::shutdown() {
+ // We can only shutdown NMT to minimal tracking level if it is
+ // ever on.
+ if (tracking_level () > NMT_minimal) {
+ transition_to(NMT_minimal);
+ }
+}
+
+bool MemTracker::transition_to(NMT_TrackingLevel level) {
+ NMT_TrackingLevel current_level = tracking_level();
- MemRecorder* rc;
- if (thread == NULL) {
- rc = _global_recorder;
+ if (current_level == level) {
+ return true;
+ } else if (current_level > level) {
+ // Downgrade tracking level, we want to lower the tracking
+ // level first
+ _tracking_level = level;
+ // Make _tracking_level visible immediately.
+ OrderAccess::fence();
+ VirtualMemoryTracker::transition(current_level, level);
+ MallocTracker::transition(current_level, level);
+
+ if (level == NMT_minimal) _baseline.reset();
} else {
- rc = thread->get_recorder();
- }
+ VirtualMemoryTracker::transition(current_level, level);
+ MallocTracker::transition(current_level, level);
- if (rc != NULL && rc->is_full()) {
- enqueue_pending_recorder(rc);
- rc = NULL;
+ _tracking_level = level;
+ // Make _tracking_level visible immediately.
+ OrderAccess::fence();
}
- if (rc == NULL) {
- rc = get_new_or_pooled_instance();
- if (thread == NULL) {
- _global_recorder = rc;
- } else {
- thread->set_recorder(rc);
- }
- }
- return rc;
+ return true;
}
-/*
- * get a per-thread recorder from pool, or create a new one if
- * there is not one available.
- */
-MemRecorder* MemTracker::get_new_or_pooled_instance() {
- MemRecorder* cur_head = const_cast<MemRecorder*> (_pooled_recorders);
- if (cur_head == NULL) {
- MemRecorder* rec = new (std::nothrow)MemRecorder();
- if (rec == NULL || rec->out_of_memory()) {
- shutdown(NMT_out_of_memory);
- if (rec != NULL) {
- delete rec;
- rec = NULL;
- }
- }
- return rec;
- } else {
- MemRecorder* next_head = cur_head->next();
- if ((void*)cur_head != Atomic::cmpxchg_ptr((void*)next_head, (void*)&_pooled_recorders,
- (void*)cur_head)) {
- return get_new_or_pooled_instance();
- }
- cur_head->set_next(NULL);
- Atomic::dec(&_pooled_recorder_count);
- cur_head->set_generation();
- return cur_head;
+void MemTracker::final_report(outputStream* output) {
+ assert(output != NULL, "No output stream");
+ if (tracking_level() >= NMT_summary) {
+ MallocMemorySnapshot* malloc_memory_snapshot =
+ MallocMemorySummary::as_snapshot();
+ malloc_memory_snapshot->make_adjustment();
+
+ VirtualMemorySnapshot* virtual_memory_snapshot =
+ VirtualMemorySummary::as_snapshot();
+
+ MemSummaryReporter rptr(malloc_memory_snapshot,
+ virtual_memory_snapshot, output);
+ rptr.report();
+ // shutdown NMT, the data no longer accurate
+ shutdown();
}
}
-/*
- * retrieve all recorders in pending queue, and empty the queue
- */
-MemRecorder* MemTracker::get_pending_recorders() {
- MemRecorder* cur_head = const_cast<MemRecorder*>(_merge_pending_queue);
- MemRecorder* null_ptr = NULL;
- while ((void*)cur_head != Atomic::cmpxchg_ptr((void*)null_ptr, (void*)&_merge_pending_queue,
- (void*)cur_head)) {
- cur_head = const_cast<MemRecorder*>(_merge_pending_queue);
- }
- NOT_PRODUCT(Atomic::store(0, &_pending_recorder_count));
- return cur_head;
-}
+// This is a walker to gather malloc site hashtable statistics,
+// the result is used for tuning.
+class StatisticsWalker : public MallocSiteWalker {
+ private:
+ enum Threshold {
+ // aggregates statistics over this threshold into one
+ // line item.
+ report_threshold = 20
+ };
-/*
- * release a recorder to recorder pool.
- */
-void MemTracker::release_thread_recorder(MemRecorder* rec) {
- assert(rec != NULL, "null recorder");
- // we don't want to pool too many recorders
- rec->set_next(NULL);
- if (shutdown_in_progress() || _pooled_recorder_count > _thread_count * 2) {
- delete rec;
- return;
- }
+ private:
+ // Number of allocation sites that have all memory freed
+ int _empty_entries;
+ // Total number of allocation sites, include empty sites
+ int _total_entries;
+ // Number of captured call stack distribution
+ int _stack_depth_distribution[NMT_TrackingStackDepth];
+ // Hash distribution
+ int _hash_distribution[report_threshold];
+ // Number of hash buckets that have entries over the threshold
+ int _bucket_over_threshold;
- rec->clear();
- MemRecorder* cur_head = const_cast<MemRecorder*>(_pooled_recorders);
- rec->set_next(cur_head);
- while ((void*)cur_head != Atomic::cmpxchg_ptr((void*)rec, (void*)&_pooled_recorders,
- (void*)cur_head)) {
- cur_head = const_cast<MemRecorder*>(_pooled_recorders);
- rec->set_next(cur_head);
- }
- Atomic::inc(&_pooled_recorder_count);
-}
-
-// write a record to proper recorder. No lock can be taken from this method
-// down.
-void MemTracker::write_tracking_record(address addr, MEMFLAGS flags,
- size_t size, jint seq, address pc, JavaThread* thread) {
+ // The hash bucket that walker is currently walking
+ int _current_hash_bucket;
+ // The length of current hash bucket
+ int _current_bucket_length;
+ // Number of hash buckets that are not empty
+ int _used_buckets;
+ // Longest hash bucket length
+ int _longest_bucket_length;
- MemRecorder* rc = get_thread_recorder(thread);
- if (rc != NULL) {
- rc->record(addr, flags, size, seq, pc);
+ public:
+ StatisticsWalker() : _empty_entries(0), _total_entries(0) {
+ int index = 0;
+ for (index = 0; index < NMT_TrackingStackDepth; index ++) {
+ _stack_depth_distribution[index] = 0;
}
-}
-
-/**
- * enqueue a recorder to pending queue
- */
-void MemTracker::enqueue_pending_recorder(MemRecorder* rec) {
- assert(rec != NULL, "null recorder");
-
- // we are shutting down, so just delete it
- if (shutdown_in_progress()) {
- rec->set_next(NULL);
- delete rec;
- return;
+ for (index = 0; index < report_threshold; index ++) {
+ _hash_distribution[index] = 0;
+ }
+ _bucket_over_threshold = 0;
+ _longest_bucket_length = 0;
+ _current_hash_bucket = -1;
+ _current_bucket_length = 0;
+ _used_buckets = 0;
}
- MemRecorder* cur_head = const_cast<MemRecorder*>(_merge_pending_queue);
- rec->set_next(cur_head);
- while ((void*)cur_head != Atomic::cmpxchg_ptr((void*)rec, (void*)&_merge_pending_queue,
- (void*)cur_head)) {
- cur_head = const_cast<MemRecorder*>(_merge_pending_queue);
- rec->set_next(cur_head);
+ virtual bool do_malloc_site(const MallocSite* e) {
+ if (e->size() == 0) _empty_entries ++;
+ _total_entries ++;
+
+ // stack depth distrubution
+ int frames = e->call_stack()->frames();
+ _stack_depth_distribution[frames - 1] ++;
+
+ // hash distribution
+ int hash_bucket = e->hash() % MallocSiteTable::hash_buckets();
+ if (_current_hash_bucket == -1) {
+ _current_hash_bucket = hash_bucket;
+ _current_bucket_length = 1;
+ } else if (_current_hash_bucket == hash_bucket) {
+ _current_bucket_length ++;
+ } else {
+ record_bucket_length(_current_bucket_length);
+ _current_hash_bucket = hash_bucket;
+ _current_bucket_length = 1;
+ }
+ return true;
}
- NOT_PRODUCT(Atomic::inc(&_pending_recorder_count);)
-}
-/*
- * The method is called at global safepoint
- * during it synchronization process.
- * 1. enqueue all JavaThreads' per-thread recorders
- * 2. enqueue global recorder
- * 3. retrieve all pending recorders
- * 4. reset global sequence number generator
- * 5. call worker's sync
- */
-#define MAX_SAFEPOINTS_TO_SKIP 128
-#define SAFE_SEQUENCE_THRESHOLD 30
-#define HIGH_GENERATION_THRESHOLD 60
-#define MAX_RECORDER_THREAD_RATIO 30
-#define MAX_RECORDER_PER_THREAD 100
-
-void MemTracker::sync() {
- assert(_tracking_level > NMT_off, "NMT is not enabled");
- assert(SafepointSynchronize::is_at_safepoint(), "Safepoint required");
+ // walk completed
+ void completed() {
+ record_bucket_length(_current_bucket_length);
+ }
- // Some GC tests hit large number of safepoints in short period of time
- // without meaningful activities. We should prevent going to
- // sync point in these cases, which can potentially exhaust generation buffer.
- // Here is the factots to determine if we should go into sync point:
- // 1. not to overflow sequence number
- // 2. if we are in danger to overflow generation buffer
- // 3. how many safepoints we already skipped sync point
- if (_state == NMT_started) {
- // worker thread is not ready, no one can manage generation
- // buffer, so skip this safepoint
- if (_worker_thread == NULL) return;
-
- if (_sync_point_skip_count < MAX_SAFEPOINTS_TO_SKIP) {
- int per_seq_in_use = SequenceGenerator::peek() * 100 / max_jint;
- int per_gen_in_use = _worker_thread->generations_in_use() * 100 / MAX_GENERATIONS;
- if (per_seq_in_use < SAFE_SEQUENCE_THRESHOLD && per_gen_in_use >= HIGH_GENERATION_THRESHOLD) {
- _sync_point_skip_count ++;
- return;
+ void report_statistics(outputStream* out) {
+ int index;
+ out->print_cr("Malloc allocation site table:");
+ out->print_cr("\tTotal entries: %d", _total_entries);
+ out->print_cr("\tEmpty entries: %d (%2.2f%%)", _empty_entries, ((float)_empty_entries * 100) / _total_entries);
+ out->print_cr(" ");
+ out->print_cr("Hash distribution:");
+ if (_used_buckets < MallocSiteTable::hash_buckets()) {
+ out->print_cr("empty bucket: %d", (MallocSiteTable::hash_buckets() - _used_buckets));
+ }
+ for (index = 0; index < report_threshold; index ++) {
+ if (_hash_distribution[index] != 0) {
+ if (index == 0) {
+ out->print_cr(" %d entry: %d", 1, _hash_distribution[0]);
+ } else if (index < 9) { // single digit
+ out->print_cr(" %d entries: %d", (index + 1), _hash_distribution[index]);
+ } else {
+ out->print_cr(" %d entries: %d", (index + 1), _hash_distribution[index]);
+ }
}
}
- {
- // This method is running at safepoint, with ThreadCritical lock,
- // it should guarantee that NMT is fully sync-ed.
- ThreadCritical tc;
-
- // We can NOT execute NMT sync-point if there are pending tracking ops.
- if (_pending_op_count == 0) {
- SequenceGenerator::reset();
- _sync_point_skip_count = 0;
-
- // walk all JavaThreads to collect recorders
- SyncThreadRecorderClosure stc;
- Threads::threads_do(&stc);
-
- _thread_count = stc.get_thread_count();
- MemRecorder* pending_recorders = get_pending_recorders();
-
- if (_global_recorder != NULL) {
- _global_recorder->set_next(pending_recorders);
- pending_recorders = _global_recorder;
- _global_recorder = NULL;
- }
-
- // see if NMT has too many outstanding recorder instances, it usually
- // means that worker thread is lagging behind in processing them.
- if (!AutoShutdownNMT) {
- _slowdown_calling_thread = (MemRecorder::_instance_count > MAX_RECORDER_THREAD_RATIO * _thread_count);
- } else {
- // If auto shutdown is on, enforce MAX_RECORDER_PER_THREAD threshold to prevent OOM
- if (MemRecorder::_instance_count >= _thread_count * MAX_RECORDER_PER_THREAD) {
- shutdown(NMT_out_of_memory);
- }
- }
-
- // check _worker_thread with lock to avoid racing condition
- if (_worker_thread != NULL) {
- _worker_thread->at_sync_point(pending_recorders, InstanceKlass::number_of_instance_classes());
- }
- assert(SequenceGenerator::peek() == 1, "Should not have memory activities during sync-point");
- } else {
- _sync_point_skip_count ++;
+ if (_bucket_over_threshold > 0) {
+ out->print_cr(" >%d entries: %d", report_threshold, _bucket_over_threshold);
+ }
+ out->print_cr("most entries: %d", _longest_bucket_length);
+ out->print_cr(" ");
+ out->print_cr("Call stack depth distribution:");
+ for (index = 0; index < NMT_TrackingStackDepth; index ++) {
+ if (_stack_depth_distribution[index] > 0) {
+ out->print_cr("\t%d: %d", index + 1, _stack_depth_distribution[index]);
}
}
}
- // now, it is the time to shut whole things off
- if (_state == NMT_final_shutdown) {
- // walk all JavaThreads to delete all recorders
- SyncThreadRecorderClosure stc;
- Threads::threads_do(&stc);
- // delete global recorder
- {
- ThreadCritical tc;
- if (_global_recorder != NULL) {
- delete _global_recorder;
- _global_recorder = NULL;
- }
- }
- MemRecorder* pending_recorders = get_pending_recorders();
- if (pending_recorders != NULL) {
- delete pending_recorders;
- }
- // try at a later sync point to ensure MemRecorder instance drops to zero to
- // completely shutdown NMT
- if (MemRecorder::_instance_count == 0) {
- _state = NMT_shutdown;
- _tracking_level = NMT_off;
+ private:
+ void record_bucket_length(int length) {
+ _used_buckets ++;
+ if (length <= report_threshold) {
+ _hash_distribution[length - 1] ++;
+ } else {
+ _bucket_over_threshold ++;
}
- }
-}
-
-/*
- * Start worker thread.
- */
-bool MemTracker::start_worker(MemSnapshot* snapshot) {
- assert(_worker_thread == NULL && _snapshot != NULL, "Just Check");
- _worker_thread = new (std::nothrow) MemTrackWorker(snapshot);
- if (_worker_thread == NULL) {
- return false;
- } else if (_worker_thread->has_error()) {
- delete _worker_thread;
- _worker_thread = NULL;
- return false;
- }
- _worker_thread->start();
- return true;
-}
-
-/*
- * We need to collect a JavaThread's per-thread recorder
- * before it exits.
- */
-void MemTracker::thread_exiting(JavaThread* thread) {
- if (is_on()) {
- MemRecorder* rec = thread->get_recorder();
- if (rec != NULL) {
- enqueue_pending_recorder(rec);
- thread->set_recorder(NULL);
- }
- }
-}
-
-// baseline current memory snapshot
-bool MemTracker::baseline() {
- MutexLocker lock(_query_lock);
- MemSnapshot* snapshot = get_snapshot();
- if (snapshot != NULL) {
- return _baseline.baseline(*snapshot, false);
- }
- return false;
-}
-
-// print memory usage from current snapshot
-bool MemTracker::print_memory_usage(BaselineOutputer& out, size_t unit, bool summary_only) {
- MemBaseline baseline;
- MutexLocker lock(_query_lock);
- MemSnapshot* snapshot = get_snapshot();
- if (snapshot != NULL && baseline.baseline(*snapshot, summary_only)) {
- BaselineReporter reporter(out, unit);
- reporter.report_baseline(baseline, summary_only);
- return true;
+ _longest_bucket_length = MAX2(_longest_bucket_length, length);
}
- return false;
-}
-
-// Whitebox API for blocking until the current generation of NMT data has been merged
-bool MemTracker::wbtest_wait_for_data_merge() {
- // NMT can't be shutdown while we're holding _query_lock
- MutexLocker lock(_query_lock);
- assert(_worker_thread != NULL, "Invalid query");
- // the generation at query time, so NMT will spin till this generation is processed
- unsigned long generation_at_query_time = SequenceGenerator::current_generation();
- unsigned long current_processing_generation = _processing_generation;
- // if generation counter overflown
- bool generation_overflown = (generation_at_query_time < current_processing_generation);
- long generations_to_wrap = MAX_UNSIGNED_LONG - current_processing_generation;
- // spin
- while (!shutdown_in_progress()) {
- if (!generation_overflown) {
- if (current_processing_generation > generation_at_query_time) {
- return true;
- }
- } else {
- assert(generations_to_wrap >= 0, "Sanity check");
- long current_generations_to_wrap = MAX_UNSIGNED_LONG - current_processing_generation;
- assert(current_generations_to_wrap >= 0, "Sanity check");
- // to overflow an unsigned long should take long time, so to_wrap check should be sufficient
- if (current_generations_to_wrap > generations_to_wrap &&
- current_processing_generation > generation_at_query_time) {
- return true;
- }
- }
-
- // if worker thread is idle, but generation is not advancing, that means
- // there is not safepoint to let NMT advance generation, force one.
- if (_worker_thread_idle) {
- VM_ForceSafepoint vfs;
- VMThread::execute(&vfs);
- }
- MemSnapshot* snapshot = get_snapshot();
- if (snapshot == NULL) {
- return false;
- }
- snapshot->wait(1000);
- current_processing_generation = _processing_generation;
- }
- // We end up here if NMT is shutting down before our data has been merged
- return false;
-}
-
-// compare memory usage between current snapshot and baseline
-bool MemTracker::compare_memory_usage(BaselineOutputer& out, size_t unit, bool summary_only) {
- MutexLocker lock(_query_lock);
- if (_baseline.baselined()) {
- MemBaseline baseline;
- MemSnapshot* snapshot = get_snapshot();
- if (snapshot != NULL && baseline.baseline(*snapshot, summary_only)) {
- BaselineReporter reporter(out, unit);
- reporter.diff_baselines(baseline, _baseline, summary_only);
- return true;
- }
- }
- return false;
-}
-
-#ifndef PRODUCT
-void MemTracker::walk_stack(int toSkip, char* buf, int len) {
- int cur_len = 0;
- char tmp[1024];
- address pc;
-
- while (cur_len < len) {
- pc = os::get_caller_pc(toSkip + 1);
- if (pc != NULL && os::dll_address_to_function_name(pc, tmp, sizeof(tmp), NULL)) {
- jio_snprintf(&buf[cur_len], (len - cur_len), "%s\n", tmp);
- cur_len = (int)strlen(buf);
- } else {
- buf[cur_len] = '\0';
- break;
- }
- toSkip ++;
- }
-}
-
-void MemTracker::print_tracker_stats(outputStream* st) {
- st->print_cr("\nMemory Tracker Stats:");
- st->print_cr("\tMax sequence number = %d", SequenceGenerator::max_seq_num());
- st->print_cr("\tthead count = %d", _thread_count);
- st->print_cr("\tArena instance = %d", Arena::_instance_count);
- st->print_cr("\tpooled recorder count = %d", _pooled_recorder_count);
- st->print_cr("\tqueued recorder count = %d", _pending_recorder_count);
- st->print_cr("\tmemory recorder instance count = %d", MemRecorder::_instance_count);
- if (_worker_thread != NULL) {
- st->print_cr("\tWorker thread:");
- st->print_cr("\t\tSync point count = %d", _worker_thread->_sync_point_count);
- st->print_cr("\t\tpending recorder count = %d", _worker_thread->count_pending_recorders());
- st->print_cr("\t\tmerge count = %d", _worker_thread->_merge_count);
- } else {
- st->print_cr("\tWorker thread is not started");
- }
- st->print_cr(" ");
-
- if (_snapshot != NULL) {
- _snapshot->print_snapshot_stats(st);
- } else {
- st->print_cr("No snapshot");
- }
-}
-#endif
+};
-// Tracker Implementation
+void MemTracker::tuning_statistics(outputStream* out) {
+ // NMT statistics
+ StatisticsWalker walker;
+ MallocSiteTable::walk_malloc_site(&walker);
+ walker.completed();
-/*
- * Create a tracker.
- * This is a fairly complicated constructor, as it has to make two important decisions:
- * 1) Does it need to take ThreadCritical lock to write tracking record
- * 2) Does it need to pre-reserve a sequence number for the tracking record
- *
- * The rules to determine if ThreadCritical is needed:
- * 1. When nmt is in single-threaded bootstrapping mode, no lock is needed as VM
- * still in single thread mode.
- * 2. For all threads other than JavaThread, ThreadCritical is needed
- * to write to recorders to global recorder.
- * 3. For JavaThreads that are no longer visible by safepoint, also
- * need to take ThreadCritical and records are written to global
- * recorders, since these threads are NOT walked by Threads.do_thread().
- * 4. JavaThreads that are running in safepoint-safe states do not stop
- * for safepoints, ThreadCritical lock should be taken to write
- * memory records.
- * 5. JavaThreads that are running in VM state do not need any lock and
- * records are written to per-thread recorders.
- * 6. For a thread has yet to attach VM 'Thread', they need to take
- * ThreadCritical to write to global recorder.
- *
- * The memory operations that need pre-reserve sequence numbers:
- * The memory operations that "release" memory blocks and the
- * operations can fail, need to pre-reserve sequence number. They
- * are realloc, uncommit and release.
- *
- * The reason for pre-reserve sequence number, is to prevent race condition:
- * Thread 1 Thread 2
- * <release>
- * <allocate>
- * <write allocate record>
- * <write release record>
- * if Thread 2 happens to obtain the memory address Thread 1 just released,
- * then NMT can mistakenly report the memory is free.
- *
- * Noticeably, free() does not need pre-reserve sequence number, because the call
- * does not fail, so we can alway write "release" record before the memory is actaully
- * freed.
- *
- * For realloc, uncommit and release, following coding pattern should be used:
- *
- * MemTracker::Tracker tkr = MemTracker::get_realloc_tracker();
- * ptr = ::realloc(...);
- * if (ptr == NULL) {
- * tkr.record(...)
- * } else {
- * tkr.discard();
- * }
- *
- * MemTracker::Tracker tkr = MemTracker::get_virtual_memory_uncommit_tracker();
- * if (uncommit(...)) {
- * tkr.record(...);
- * } else {
- * tkr.discard();
- * }
- *
- * MemTracker::Tracker tkr = MemTracker::get_virtual_memory_release_tracker();
- * if (release(...)) {
- * tkr.record(...);
- * } else {
- * tkr.discard();
- * }
- *
- * Since pre-reserved sequence number is only good for the generation that it is acquired,
- * when there is pending Tracker that reserved sequence number, NMT sync-point has
- * to be skipped to prevent from advancing generation. This is done by inc and dec
- * MemTracker::_pending_op_count, when MemTracker::_pending_op_count > 0, NMT sync-point is skipped.
- * Not all pre-reservation of sequence number will increment pending op count. For JavaThreads
- * that honor safepoints, safepoint can not occur during the memory operations, so the
- * pre-reserved sequence number won't cross the generation boundry.
- */
-MemTracker::Tracker::Tracker(MemoryOperation op, Thread* thr) {
- _op = NoOp;
- _seq = 0;
- if (MemTracker::is_on()) {
- _java_thread = NULL;
- _op = op;
-
- // figure out if ThreadCritical lock is needed to write this operation
- // to MemTracker
- if (MemTracker::is_single_threaded_bootstrap()) {
- thr = NULL;
- } else if (thr == NULL) {
- // don't use Thread::current(), since it is possible that
- // the calling thread has yet to attach to VM 'Thread',
- // which will result assertion failure
- thr = ThreadLocalStorage::thread();
- }
-
- if (thr != NULL) {
- // Check NMT load
- MemTracker::check_NMT_load(thr);
-
- if (thr->is_Java_thread() && ((JavaThread*)thr)->is_safepoint_visible()) {
- _java_thread = (JavaThread*)thr;
- JavaThreadState state = _java_thread->thread_state();
- // JavaThreads that are safepoint safe, can run through safepoint,
- // so ThreadCritical is needed to ensure no threads at safepoint create
- // new records while the records are being gathered and the sequence number is changing
- _need_thread_critical_lock =
- SafepointSynchronize::safepoint_safe(_java_thread, state);
- } else {
- _need_thread_critical_lock = true;
- }
- } else {
- _need_thread_critical_lock
- = !MemTracker::is_single_threaded_bootstrap();
- }
-
- // see if we need to pre-reserve sequence number for this operation
- if (_op == Realloc || _op == Uncommit || _op == Release) {
- if (_need_thread_critical_lock) {
- ThreadCritical tc;
- MemTracker::inc_pending_op_count();
- _seq = SequenceGenerator::next();
- } else {
- // for the threads that honor safepoints, no safepoint can occur
- // during the lifespan of tracker, so we don't need to increase
- // pending op count.
- _seq = SequenceGenerator::next();
- }
- }
- }
+ out->print_cr("Native Memory Tracking Statistics:");
+ out->print_cr("Malloc allocation site table size: %d", MallocSiteTable::hash_buckets());
+ out->print_cr(" Tracking stack depth: %d", NMT_TrackingStackDepth);
+ NOT_PRODUCT(out->print_cr("Peak concurrent access: %d", MallocSiteTable::access_peak_count());)
+ out->print_cr(" ");
+ walker.report_statistics(out);
}
-void MemTracker::Tracker::discard() {
- if (MemTracker::is_on() && _seq != 0) {
- if (_need_thread_critical_lock) {
- ThreadCritical tc;
- MemTracker::dec_pending_op_count();
- }
- _seq = 0;
- }
-}
-
-
-void MemTracker::Tracker::record(address old_addr, address new_addr, size_t size,
- MEMFLAGS flags, address pc) {
- assert(old_addr != NULL && new_addr != NULL, "Sanity check");
- assert(_op == Realloc || _op == NoOp, "Wrong call");
- if (MemTracker::is_on() && NMT_CAN_TRACK(flags) && _op != NoOp && !MemTracker::shutdown_in_progress()) {
- assert(_seq > 0, "Need pre-reserve sequence number");
- if (_need_thread_critical_lock) {
- ThreadCritical tc;
- // free old address, use pre-reserved sequence number
- MemTracker::write_tracking_record(old_addr, MemPointerRecord::free_tag(),
- 0, _seq, pc, _java_thread);
- MemTracker::write_tracking_record(new_addr, flags | MemPointerRecord::malloc_tag(),
- size, SequenceGenerator::next(), pc, _java_thread);
- // decrement MemTracker pending_op_count
- MemTracker::dec_pending_op_count();
- } else {
- // free old address, use pre-reserved sequence number
- MemTracker::write_tracking_record(old_addr, MemPointerRecord::free_tag(),
- 0, _seq, pc, _java_thread);
- MemTracker::write_tracking_record(new_addr, flags | MemPointerRecord::malloc_tag(),
- size, SequenceGenerator::next(), pc, _java_thread);
- }
- _seq = 0;
- }
-}
-
-void MemTracker::Tracker::record(address addr, size_t size, MEMFLAGS flags, address pc) {
- // OOM already?
- if (addr == NULL) return;
-
- if (MemTracker::is_on() && NMT_CAN_TRACK(flags) && _op != NoOp && !MemTracker::shutdown_in_progress()) {
- bool pre_reserved_seq = (_seq != 0);
- address pc = CALLER_CALLER_PC;
- MEMFLAGS orig_flags = flags;
-
- // or the tagging flags
- switch(_op) {
- case Malloc:
- flags |= MemPointerRecord::malloc_tag();
- break;
- case Free:
- flags = MemPointerRecord::free_tag();
- break;
- case Realloc:
- fatal("Use the other Tracker::record()");
- break;
- case Reserve:
- case ReserveAndCommit:
- flags |= MemPointerRecord::virtual_memory_reserve_tag();
- break;
- case Commit:
- flags = MemPointerRecord::virtual_memory_commit_tag();
- break;
- case Type:
- flags |= MemPointerRecord::virtual_memory_type_tag();
- break;
- case Uncommit:
- assert(pre_reserved_seq, "Need pre-reserve sequence number");
- flags = MemPointerRecord::virtual_memory_uncommit_tag();
- break;
- case Release:
- assert(pre_reserved_seq, "Need pre-reserve sequence number");
- flags = MemPointerRecord::virtual_memory_release_tag();
- break;
- case ArenaSize:
- // a bit of hack here, add a small postive offset to arena
- // address for its size record, so the size record is sorted
- // right after arena record.
- flags = MemPointerRecord::arena_size_tag();
- addr += sizeof(void*);
- break;
- case StackRelease:
- flags = MemPointerRecord::virtual_memory_release_tag();
- break;
- default:
- ShouldNotReachHere();
- }
-
- // write memory tracking record
- if (_need_thread_critical_lock) {
- ThreadCritical tc;
- if (_seq == 0) _seq = SequenceGenerator::next();
- MemTracker::write_tracking_record(addr, flags, size, _seq, pc, _java_thread);
- if (_op == ReserveAndCommit) {
- MemTracker::write_tracking_record(addr, orig_flags | MemPointerRecord::virtual_memory_commit_tag(),
- size, SequenceGenerator::next(), pc, _java_thread);
- }
- if (pre_reserved_seq) MemTracker::dec_pending_op_count();
- } else {
- if (_seq == 0) _seq = SequenceGenerator::next();
- MemTracker::write_tracking_record(addr, flags, size, _seq, pc, _java_thread);
- if (_op == ReserveAndCommit) {
- MemTracker::write_tracking_record(addr, orig_flags | MemPointerRecord::virtual_memory_commit_tag(),
- size, SequenceGenerator::next(), pc, _java_thread);
- }
- }
- _seq = 0;
- }
-}
-