jdk8-mips64-public/hotspot: src/share/vm/services/memTracker.cpp@1f4355cee9a2 (annotated)

src/share/vm/services/memTracker.cpp@1f4355cee9a2 (annotated)

src/share/vm/services/memTracker.cpp

Tue, 18 Jun 2013 08:44:08 -0400

author: zgu
date: Tue, 18 Jun 2013 08:44:08 -0400
changeset 5272: 1f4355cee9a2
parent 5188: fb14e9ed1594
child 5403: 90d6c221d4e5
child 5410: c9a5fab39234
permissions: -rw-r--r--

8013651: NMT: reserve/release sequence id's in incorrect order due to race
Summary: Fixed NMT race condition for realloc, uncommit and release
Reviewed-by: coleenp, ccheung

 /*
  * Copyright (c) 2012, 2013, 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
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  *
  */
 #include "precompiled.hpp"
 #include "oops/instanceKlass.hpp"
 #include "runtime/atomic.hpp"
 #include "runtime/interfaceSupport.hpp"
 #include "runtime/mutexLocker.hpp"
 #include "runtime/safepoint.hpp"
 #include "runtime/threadCritical.hpp"
 #include "runtime/vm_operations.hpp"
 #include "services/memPtr.hpp"
 #include "services/memReporter.hpp"
 #include "services/memTracker.hpp"
 #include "utilities/decoder.hpp"
 #include "utilities/defaultStream.hpp"
 #include "utilities/globalDefinitions.hpp"
 bool NMT_track_callsite = false;
 // 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 ++;
 }
 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
     if (PLATFORM_NMT_DETAIL_SUPPORTED) {
       _tracking_level = NMT_detail;
     } else {
       jio_fprintf(defaultStream::error_stream(),
         "NMT detail is not supported on this platform.  Using NMT summary instead.");
       _tracking_level = NMT_summary;
     }
   } 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;
     }
     _query_lock = new (std::nothrow) Mutex(Monitor::max_nonleaf, "NMT_queryLock");
     if (_query_lock == NULL) {
       shutdown(NMT_out_of_memory);
       return;
     }
     debug_only(_main_thread_tid = os::current_thread_id();)
     _state = NMT_bootstrapping_single_thread;
     NMT_track_callsite = (_tracking_level == NMT_detail && can_walk_stack());
   }
 }
 // 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;
     }
   }
 }
 // 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;
   }
 }
 /*
  * 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;
   MemRecorder* rc;
   if (thread == NULL) {
     rc = _global_recorder;
   } else {
     rc = thread->get_recorder();
   }
   if (rc != NULL && rc->is_full()) {
     enqueue_pending_recorder(rc);
     rc = NULL;
   }
   if (rc == NULL) {
     rc = get_new_or_pooled_instance();
     if (thread == NULL) {
       _global_recorder = rc;
     } else {
       thread->set_recorder(rc);
     }
   }
   return rc;
 }
 /*
  * 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;
   }
 }
 /*
  * 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;
 }
 /*
  * 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;
   }
   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) {
     MemRecorder* rc = get_thread_recorder(thread);
     if (rc != NULL) {
       rc->record(addr, flags, size, seq, pc);
     }
 }
 /**
  * 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;
   }
   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);
   }
   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
 void MemTracker::sync() {
   assert(_tracking_level > NMT_off, "NMT is not enabled");
   assert(SafepointSynchronize::is_at_safepoint(), "Safepoint required");
   // 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;
       }
     }
     {
       // 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);
         }
         // 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 ++;
       }
     }
   }
   // 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;
     }
   }
 }
 /*
  * 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;
   }
   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
 /*
  * 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();
       }
     }
   }
 }
 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) {
     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(),
 , _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(),
 , _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) {
     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;
   }
 }

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/services/memTracker.cpp@1f4355cee9a2 (annotated)

src/share/vm/services/memTracker.cpp