src/share/vm/services/memoryManager.cpp

Mon, 21 Nov 2011 09:24:56 -0800

author
johnc
date
Mon, 21 Nov 2011 09:24:56 -0800
changeset 3291
b5a5f30c483d
parent 3202
436b4a3231bf
child 3471
bf864f701a4a
permissions
-rw-r--r--

7110173: GCNotifier::pushNotification publishes stale data.
Summary: GCNotifier::pushNotification() references GCMemoryManager::_last_gc_stat but is called from GCMemoryManager::gc_end() before GCMemoryManager::_last_gc_stat is set up using the values in GCMemoryManager::_current_gc_stat. As a result the GC notification code accesses unitialized or stale data. Move the notification call after GCMemoryManager::_las_gc_stat is set, but inside the same if-block.
Reviewed-by: poonam, dholmes, fparain, mchung

     1 /*
     2  * Copyright (c) 2003, 2011, 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  */
    25 #include "precompiled.hpp"
    26 #include "classfile/systemDictionary.hpp"
    27 #include "classfile/vmSymbols.hpp"
    28 #include "oops/oop.inline.hpp"
    29 #include "runtime/handles.inline.hpp"
    30 #include "runtime/javaCalls.hpp"
    31 #include "services/lowMemoryDetector.hpp"
    32 #include "services/management.hpp"
    33 #include "services/memoryManager.hpp"
    34 #include "services/memoryPool.hpp"
    35 #include "services/memoryService.hpp"
    36 #include "services/gcNotifier.hpp"
    37 #include "utilities/dtrace.hpp"
    39 #ifndef USDT2
    40 HS_DTRACE_PROBE_DECL8(hotspot, mem__pool__gc__begin, char*, int, char*, int,
    41   size_t, size_t, size_t, size_t);
    42 HS_DTRACE_PROBE_DECL8(hotspot, mem__pool__gc__end, char*, int, char*, int,
    43   size_t, size_t, size_t, size_t);
    44 #endif /* !USDT2 */
    46 MemoryManager::MemoryManager() {
    47   _num_pools = 0;
    48   _memory_mgr_obj = NULL;
    49 }
    51 void MemoryManager::add_pool(MemoryPool* pool) {
    52   assert(_num_pools < MemoryManager::max_num_pools, "_num_pools exceeds the max");
    53   if (_num_pools < MemoryManager::max_num_pools) {
    54     _pools[_num_pools] = pool;
    55     _num_pools++;
    56   }
    57   pool->add_manager(this);
    58 }
    60 MemoryManager* MemoryManager::get_code_cache_memory_manager() {
    61   return (MemoryManager*) new CodeCacheMemoryManager();
    62 }
    64 GCMemoryManager* MemoryManager::get_copy_memory_manager() {
    65   return (GCMemoryManager*) new CopyMemoryManager();
    66 }
    68 GCMemoryManager* MemoryManager::get_msc_memory_manager() {
    69   return (GCMemoryManager*) new MSCMemoryManager();
    70 }
    72 GCMemoryManager* MemoryManager::get_parnew_memory_manager() {
    73   return (GCMemoryManager*) new ParNewMemoryManager();
    74 }
    76 GCMemoryManager* MemoryManager::get_cms_memory_manager() {
    77   return (GCMemoryManager*) new CMSMemoryManager();
    78 }
    80 GCMemoryManager* MemoryManager::get_psScavenge_memory_manager() {
    81   return (GCMemoryManager*) new PSScavengeMemoryManager();
    82 }
    84 GCMemoryManager* MemoryManager::get_psMarkSweep_memory_manager() {
    85   return (GCMemoryManager*) new PSMarkSweepMemoryManager();
    86 }
    88 GCMemoryManager* MemoryManager::get_g1YoungGen_memory_manager() {
    89   return (GCMemoryManager*) new G1YoungGenMemoryManager();
    90 }
    92 GCMemoryManager* MemoryManager::get_g1OldGen_memory_manager() {
    93   return (GCMemoryManager*) new G1OldGenMemoryManager();
    94 }
    96 instanceOop MemoryManager::get_memory_manager_instance(TRAPS) {
    97   // Must do an acquire so as to force ordering of subsequent
    98   // loads from anything _memory_mgr_obj points to or implies.
    99   instanceOop mgr_obj = (instanceOop)OrderAccess::load_ptr_acquire(&_memory_mgr_obj);
   100   if (mgr_obj == NULL) {
   101     // It's ok for more than one thread to execute the code up to the locked region.
   102     // Extra manager instances will just be gc'ed.
   103     klassOop k = Management::sun_management_ManagementFactory_klass(CHECK_0);
   104     instanceKlassHandle ik(THREAD, k);
   106     Handle mgr_name = java_lang_String::create_from_str(name(), CHECK_0);
   108     JavaValue result(T_OBJECT);
   109     JavaCallArguments args;
   110     args.push_oop(mgr_name);    // Argument 1
   112     Symbol* method_name = NULL;
   113     Symbol* signature = NULL;
   114     if (is_gc_memory_manager()) {
   115       method_name = vmSymbols::createGarbageCollector_name();
   116       signature = vmSymbols::createGarbageCollector_signature();
   117       args.push_oop(Handle());      // Argument 2 (for future extension)
   118     } else {
   119       method_name = vmSymbols::createMemoryManager_name();
   120       signature = vmSymbols::createMemoryManager_signature();
   121     }
   123     JavaCalls::call_static(&result,
   124                            ik,
   125                            method_name,
   126                            signature,
   127                            &args,
   128                            CHECK_0);
   130     instanceOop m = (instanceOop) result.get_jobject();
   131     instanceHandle mgr(THREAD, m);
   133     {
   134       // Get lock before setting _memory_mgr_obj
   135       // since another thread may have created the instance
   136       MutexLocker ml(Management_lock);
   138       // Check if another thread has created the management object.  We reload
   139       // _memory_mgr_obj here because some other thread may have initialized
   140       // it while we were executing the code before the lock.
   141       //
   142       // The lock has done an acquire, so the load can't float above it, but
   143       // we need to do a load_acquire as above.
   144       mgr_obj = (instanceOop)OrderAccess::load_ptr_acquire(&_memory_mgr_obj);
   145       if (mgr_obj != NULL) {
   146          return mgr_obj;
   147       }
   149       // Get the address of the object we created via call_special.
   150       mgr_obj = mgr();
   152       // Use store barrier to make sure the memory accesses associated
   153       // with creating the management object are visible before publishing
   154       // its address.  The unlock will publish the store to _memory_mgr_obj
   155       // because it does a release first.
   156       OrderAccess::release_store_ptr(&_memory_mgr_obj, mgr_obj);
   157     }
   158   }
   160   return mgr_obj;
   161 }
   163 void MemoryManager::oops_do(OopClosure* f) {
   164   f->do_oop((oop*) &_memory_mgr_obj);
   165 }
   167 GCStatInfo::GCStatInfo(int num_pools) {
   168   // initialize the arrays for memory usage
   169   _before_gc_usage_array = (MemoryUsage*) NEW_C_HEAP_ARRAY(MemoryUsage, num_pools);
   170   _after_gc_usage_array  = (MemoryUsage*) NEW_C_HEAP_ARRAY(MemoryUsage, num_pools);
   171   _usage_array_size = num_pools;
   172   clear();
   173 }
   175 GCStatInfo::~GCStatInfo() {
   176   FREE_C_HEAP_ARRAY(MemoryUsage*, _before_gc_usage_array);
   177   FREE_C_HEAP_ARRAY(MemoryUsage*, _after_gc_usage_array);
   178 }
   180 void GCStatInfo::set_gc_usage(int pool_index, MemoryUsage usage, bool before_gc) {
   181   MemoryUsage* gc_usage_array;
   182   if (before_gc) {
   183     gc_usage_array = _before_gc_usage_array;
   184   } else {
   185     gc_usage_array = _after_gc_usage_array;
   186   }
   187   gc_usage_array[pool_index] = usage;
   188 }
   190 void GCStatInfo::clear() {
   191   _index = 0;
   192   _start_time = 0L;
   193   _end_time = 0L;
   194   size_t len = _usage_array_size * sizeof(MemoryUsage);
   195   memset(_before_gc_usage_array, 0, len);
   196   memset(_after_gc_usage_array, 0, len);
   197 }
   200 GCMemoryManager::GCMemoryManager() : MemoryManager() {
   201   _num_collections = 0;
   202   _last_gc_stat = NULL;
   203   _last_gc_lock = new Mutex(Mutex::leaf, "_last_gc_lock", true);
   204   _current_gc_stat = NULL;
   205   _num_gc_threads = 1;
   206   _notification_enabled = false;
   207 }
   209 GCMemoryManager::~GCMemoryManager() {
   210   delete _last_gc_stat;
   211   delete _last_gc_lock;
   212   delete _current_gc_stat;
   213 }
   215 void GCMemoryManager::initialize_gc_stat_info() {
   216   assert(MemoryService::num_memory_pools() > 0, "should have one or more memory pools");
   217   _last_gc_stat = new GCStatInfo(MemoryService::num_memory_pools());
   218   _current_gc_stat = new GCStatInfo(MemoryService::num_memory_pools());
   219   // tracking concurrent collections we need two objects: one to update, and one to
   220   // hold the publicly available "last (completed) gc" information.
   221 }
   223 void GCMemoryManager::gc_begin(bool recordGCBeginTime, bool recordPreGCUsage,
   224                                bool recordAccumulatedGCTime) {
   225   assert(_last_gc_stat != NULL && _current_gc_stat != NULL, "Just checking");
   226   if (recordAccumulatedGCTime) {
   227     _accumulated_timer.start();
   228   }
   229   // _num_collections now increases in gc_end, to count completed collections
   230   if (recordGCBeginTime) {
   231     _current_gc_stat->set_index(_num_collections+1);
   232     _current_gc_stat->set_start_time(Management::timestamp());
   233   }
   235   if (recordPreGCUsage) {
   236     // Keep memory usage of all memory pools
   237     for (int i = 0; i < MemoryService::num_memory_pools(); i++) {
   238       MemoryPool* pool = MemoryService::get_memory_pool(i);
   239       MemoryUsage usage = pool->get_memory_usage();
   240       _current_gc_stat->set_before_gc_usage(i, usage);
   241 #ifndef USDT2
   242       HS_DTRACE_PROBE8(hotspot, mem__pool__gc__begin,
   243         name(), strlen(name()),
   244         pool->name(), strlen(pool->name()),
   245         usage.init_size(), usage.used(),
   246         usage.committed(), usage.max_size());
   247 #else /* USDT2 */
   248       HOTSPOT_MEM_POOL_GC_BEGIN(
   249         (char *) name(), strlen(name()),
   250         (char *) pool->name(), strlen(pool->name()),
   251         usage.init_size(), usage.used(),
   252         usage.committed(), usage.max_size());
   253 #endif /* USDT2 */
   254     }
   255   }
   256 }
   258 // A collector MUST, even if it does not complete for some reason,
   259 // make a TraceMemoryManagerStats object where countCollection is true,
   260 // to ensure the current gc stat is placed in _last_gc_stat.
   261 void GCMemoryManager::gc_end(bool recordPostGCUsage,
   262                              bool recordAccumulatedGCTime,
   263                              bool recordGCEndTime, bool countCollection,
   264                              GCCause::Cause cause) {
   265   if (recordAccumulatedGCTime) {
   266     _accumulated_timer.stop();
   267   }
   268   if (recordGCEndTime) {
   269     _current_gc_stat->set_end_time(Management::timestamp());
   270   }
   272   if (recordPostGCUsage) {
   273     int i;
   274     // keep the last gc statistics for all memory pools
   275     for (i = 0; i < MemoryService::num_memory_pools(); i++) {
   276       MemoryPool* pool = MemoryService::get_memory_pool(i);
   277       MemoryUsage usage = pool->get_memory_usage();
   279 #ifndef USDT2
   280       HS_DTRACE_PROBE8(hotspot, mem__pool__gc__end,
   281         name(), strlen(name()),
   282         pool->name(), strlen(pool->name()),
   283         usage.init_size(), usage.used(),
   284         usage.committed(), usage.max_size());
   285 #else /* USDT2 */
   286       HOTSPOT_MEM_POOL_GC_END(
   287         (char *) name(), strlen(name()),
   288         (char *) pool->name(), strlen(pool->name()),
   289         usage.init_size(), usage.used(),
   290         usage.committed(), usage.max_size());
   291 #endif /* USDT2 */
   293       _current_gc_stat->set_after_gc_usage(i, usage);
   294     }
   296     // Set last collection usage of the memory pools managed by this collector
   297     for (i = 0; i < num_memory_pools(); i++) {
   298       MemoryPool* pool = get_memory_pool(i);
   299       MemoryUsage usage = pool->get_memory_usage();
   301       // Compare with GC usage threshold
   302       pool->set_last_collection_usage(usage);
   303       LowMemoryDetector::detect_after_gc_memory(pool);
   304     }
   305   }
   307   if (countCollection) {
   308     _num_collections++;
   309     // alternately update two objects making one public when complete
   310     {
   311       MutexLockerEx ml(_last_gc_lock, Mutex::_no_safepoint_check_flag);
   312       GCStatInfo *tmp = _last_gc_stat;
   313       _last_gc_stat = _current_gc_stat;
   314       _current_gc_stat = tmp;
   315       // reset the current stat for diagnosability purposes
   316       _current_gc_stat->clear();
   317     }
   319     if (is_notification_enabled()) {
   320       bool isMajorGC = this == MemoryService::get_major_gc_manager();
   321       GCNotifier::pushNotification(this, isMajorGC ? "end of major GC" : "end of minor GC",
   322                                    GCCause::to_string(cause));
   323     }
   324   }
   325 }
   327 size_t GCMemoryManager::get_last_gc_stat(GCStatInfo* dest) {
   328   MutexLockerEx ml(_last_gc_lock, Mutex::_no_safepoint_check_flag);
   329   if (_last_gc_stat->gc_index() != 0) {
   330     dest->set_index(_last_gc_stat->gc_index());
   331     dest->set_start_time(_last_gc_stat->start_time());
   332     dest->set_end_time(_last_gc_stat->end_time());
   333     assert(dest->usage_array_size() == _last_gc_stat->usage_array_size(),
   334            "Must have same array size");
   335     size_t len = dest->usage_array_size() * sizeof(MemoryUsage);
   336     memcpy(dest->before_gc_usage_array(), _last_gc_stat->before_gc_usage_array(), len);
   337     memcpy(dest->after_gc_usage_array(), _last_gc_stat->after_gc_usage_array(), len);
   338   }
   339   return _last_gc_stat->gc_index();
   340 }

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