Fri, 30 Jul 2010 22:43:50 +0100
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
Summary: Management code enabled for use by a concurrent collector.
Reviewed-by: mchung, ysr
1 /*
2 * Copyright (c) 2003, 2005, 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 "incls/_precompiled.incl"
26 # include "incls/_memoryManager.cpp.incl"
28 HS_DTRACE_PROBE_DECL8(hotspot, mem__pool__gc__begin, char*, int, char*, int,
29 size_t, size_t, size_t, size_t);
30 HS_DTRACE_PROBE_DECL8(hotspot, mem__pool__gc__end, char*, int, char*, int,
31 size_t, size_t, size_t, size_t);
33 MemoryManager::MemoryManager() {
34 _num_pools = 0;
35 _memory_mgr_obj = NULL;
36 }
38 void MemoryManager::add_pool(MemoryPool* pool) {
39 assert(_num_pools < MemoryManager::max_num_pools, "_num_pools exceeds the max");
40 if (_num_pools < MemoryManager::max_num_pools) {
41 _pools[_num_pools] = pool;
42 _num_pools++;
43 }
44 pool->add_manager(this);
45 }
47 MemoryManager* MemoryManager::get_code_cache_memory_manager() {
48 return (MemoryManager*) new CodeCacheMemoryManager();
49 }
51 GCMemoryManager* MemoryManager::get_copy_memory_manager() {
52 return (GCMemoryManager*) new CopyMemoryManager();
53 }
55 GCMemoryManager* MemoryManager::get_msc_memory_manager() {
56 return (GCMemoryManager*) new MSCMemoryManager();
57 }
59 GCMemoryManager* MemoryManager::get_parnew_memory_manager() {
60 return (GCMemoryManager*) new ParNewMemoryManager();
61 }
63 GCMemoryManager* MemoryManager::get_cms_memory_manager() {
64 return (GCMemoryManager*) new CMSMemoryManager();
65 }
67 GCMemoryManager* MemoryManager::get_psScavenge_memory_manager() {
68 return (GCMemoryManager*) new PSScavengeMemoryManager();
69 }
71 GCMemoryManager* MemoryManager::get_psMarkSweep_memory_manager() {
72 return (GCMemoryManager*) new PSMarkSweepMemoryManager();
73 }
75 GCMemoryManager* MemoryManager::get_g1YoungGen_memory_manager() {
76 return (GCMemoryManager*) new G1YoungGenMemoryManager();
77 }
79 GCMemoryManager* MemoryManager::get_g1OldGen_memory_manager() {
80 return (GCMemoryManager*) new G1OldGenMemoryManager();
81 }
83 instanceOop MemoryManager::get_memory_manager_instance(TRAPS) {
84 // Must do an acquire so as to force ordering of subsequent
85 // loads from anything _memory_mgr_obj points to or implies.
86 instanceOop mgr_obj = (instanceOop)OrderAccess::load_ptr_acquire(&_memory_mgr_obj);
87 if (mgr_obj == NULL) {
88 // It's ok for more than one thread to execute the code up to the locked region.
89 // Extra manager instances will just be gc'ed.
90 klassOop k = Management::sun_management_ManagementFactory_klass(CHECK_0);
91 instanceKlassHandle ik(THREAD, k);
93 Handle mgr_name = java_lang_String::create_from_str(name(), CHECK_0);
95 JavaValue result(T_OBJECT);
96 JavaCallArguments args;
97 args.push_oop(mgr_name); // Argument 1
99 symbolHandle method_name;
100 symbolHandle signature;
101 if (is_gc_memory_manager()) {
102 method_name = vmSymbolHandles::createGarbageCollector_name();
103 signature = vmSymbolHandles::createGarbageCollector_signature();
104 args.push_oop(Handle()); // Argument 2 (for future extension)
105 } else {
106 method_name = vmSymbolHandles::createMemoryManager_name();
107 signature = vmSymbolHandles::createMemoryManager_signature();
108 }
110 JavaCalls::call_static(&result,
111 ik,
112 method_name,
113 signature,
114 &args,
115 CHECK_0);
117 instanceOop m = (instanceOop) result.get_jobject();
118 instanceHandle mgr(THREAD, m);
120 {
121 // Get lock before setting _memory_mgr_obj
122 // since another thread may have created the instance
123 MutexLocker ml(Management_lock);
125 // Check if another thread has created the management object. We reload
126 // _memory_mgr_obj here because some other thread may have initialized
127 // it while we were executing the code before the lock.
128 //
129 // The lock has done an acquire, so the load can't float above it, but
130 // we need to do a load_acquire as above.
131 mgr_obj = (instanceOop)OrderAccess::load_ptr_acquire(&_memory_mgr_obj);
132 if (mgr_obj != NULL) {
133 return mgr_obj;
134 }
136 // Get the address of the object we created via call_special.
137 mgr_obj = mgr();
139 // Use store barrier to make sure the memory accesses associated
140 // with creating the management object are visible before publishing
141 // its address. The unlock will publish the store to _memory_mgr_obj
142 // because it does a release first.
143 OrderAccess::release_store_ptr(&_memory_mgr_obj, mgr_obj);
144 }
145 }
147 return mgr_obj;
148 }
150 void MemoryManager::oops_do(OopClosure* f) {
151 f->do_oop((oop*) &_memory_mgr_obj);
152 }
154 GCStatInfo::GCStatInfo(int num_pools) {
155 // initialize the arrays for memory usage
156 _before_gc_usage_array = (MemoryUsage*) NEW_C_HEAP_ARRAY(MemoryUsage, num_pools);
157 _after_gc_usage_array = (MemoryUsage*) NEW_C_HEAP_ARRAY(MemoryUsage, num_pools);
158 size_t len = num_pools * sizeof(MemoryUsage);
159 memset(_before_gc_usage_array, 0, len);
160 memset(_after_gc_usage_array, 0, len);
161 _usage_array_size = num_pools;
162 }
164 GCStatInfo::~GCStatInfo() {
165 FREE_C_HEAP_ARRAY(MemoryUsage*, _before_gc_usage_array);
166 FREE_C_HEAP_ARRAY(MemoryUsage*, _after_gc_usage_array);
167 }
169 void GCStatInfo::set_gc_usage(int pool_index, MemoryUsage usage, bool before_gc) {
170 MemoryUsage* gc_usage_array;
171 if (before_gc) {
172 gc_usage_array = _before_gc_usage_array;
173 } else {
174 gc_usage_array = _after_gc_usage_array;
175 }
176 gc_usage_array[pool_index] = usage;
177 }
179 void GCStatInfo::clear() {
180 _index = 0;
181 _start_time = 0L;
182 _end_time = 0L;
183 size_t len = _usage_array_size * sizeof(MemoryUsage);
184 memset(_before_gc_usage_array, 0, len);
185 memset(_after_gc_usage_array, 0, len);
186 }
189 GCMemoryManager::GCMemoryManager() : MemoryManager() {
190 _num_collections = 0;
191 _last_gc_stat = NULL;
192 _last_gc_lock = new Mutex(Mutex::leaf, "_last_gc_lock", true);
193 _current_gc_stat = NULL;
194 _num_gc_threads = 1;
195 }
197 GCMemoryManager::~GCMemoryManager() {
198 delete _last_gc_stat;
199 delete _last_gc_lock;
200 delete _current_gc_stat;
201 }
203 void GCMemoryManager::initialize_gc_stat_info() {
204 assert(MemoryService::num_memory_pools() > 0, "should have one or more memory pools");
205 _last_gc_stat = new GCStatInfo(MemoryService::num_memory_pools());
206 _current_gc_stat = new GCStatInfo(MemoryService::num_memory_pools());
207 // tracking concurrent collections we need two objects: one to update, and one to
208 // hold the publicly available "last (completed) gc" information.
209 }
211 void GCMemoryManager::gc_begin(bool recordGCBeginTime, bool recordPreGCUsage,
212 bool recordAccumulatedGCTime) {
213 assert(_last_gc_stat != NULL && _current_gc_stat != NULL, "Just checking");
214 if (recordAccumulatedGCTime) {
215 _accumulated_timer.start();
216 }
217 // _num_collections now increases in gc_end, to count completed collections
218 if (recordGCBeginTime) {
219 _current_gc_stat->set_index(_num_collections+1);
220 _current_gc_stat->set_start_time(Management::timestamp());
221 }
223 if (recordPreGCUsage) {
224 // Keep memory usage of all memory pools
225 for (int i = 0; i < MemoryService::num_memory_pools(); i++) {
226 MemoryPool* pool = MemoryService::get_memory_pool(i);
227 MemoryUsage usage = pool->get_memory_usage();
228 _current_gc_stat->set_before_gc_usage(i, usage);
229 HS_DTRACE_PROBE8(hotspot, mem__pool__gc__begin,
230 name(), strlen(name()),
231 pool->name(), strlen(pool->name()),
232 usage.init_size(), usage.used(),
233 usage.committed(), usage.max_size());
234 }
235 }
236 }
238 // A collector MUST, even if it does not complete for some reason,
239 // make a TraceMemoryManagerStats object where countCollection is true,
240 // to ensure the current gc stat is placed in _last_gc_stat.
241 void GCMemoryManager::gc_end(bool recordPostGCUsage,
242 bool recordAccumulatedGCTime,
243 bool recordGCEndTime, bool countCollection) {
244 if (recordAccumulatedGCTime) {
245 _accumulated_timer.stop();
246 }
247 if (recordGCEndTime) {
248 _current_gc_stat->set_end_time(Management::timestamp());
249 }
251 if (recordPostGCUsage) {
252 int i;
253 // keep the last gc statistics for all memory pools
254 for (i = 0; i < MemoryService::num_memory_pools(); i++) {
255 MemoryPool* pool = MemoryService::get_memory_pool(i);
256 MemoryUsage usage = pool->get_memory_usage();
258 HS_DTRACE_PROBE8(hotspot, mem__pool__gc__end,
259 name(), strlen(name()),
260 pool->name(), strlen(pool->name()),
261 usage.init_size(), usage.used(),
262 usage.committed(), usage.max_size());
264 _current_gc_stat->set_after_gc_usage(i, usage);
265 }
267 // Set last collection usage of the memory pools managed by this collector
268 for (i = 0; i < num_memory_pools(); i++) {
269 MemoryPool* pool = get_memory_pool(i);
270 MemoryUsage usage = pool->get_memory_usage();
272 // Compare with GC usage threshold
273 pool->set_last_collection_usage(usage);
274 LowMemoryDetector::detect_after_gc_memory(pool);
275 }
276 }
277 if (countCollection) {
278 _num_collections++;
279 // alternately update two objects making one public when complete
280 {
281 MutexLockerEx ml(_last_gc_lock, Mutex::_no_safepoint_check_flag);
282 GCStatInfo *tmp = _last_gc_stat;
283 _last_gc_stat = _current_gc_stat;
284 _current_gc_stat = tmp;
285 // reset the current stat for diagnosability purposes
286 _current_gc_stat->clear();
287 }
288 }
289 }
291 size_t GCMemoryManager::get_last_gc_stat(GCStatInfo* dest) {
292 MutexLockerEx ml(_last_gc_lock, Mutex::_no_safepoint_check_flag);
293 if (_last_gc_stat->gc_index() != 0) {
294 dest->set_index(_last_gc_stat->gc_index());
295 dest->set_start_time(_last_gc_stat->start_time());
296 dest->set_end_time(_last_gc_stat->end_time());
297 assert(dest->usage_array_size() == _last_gc_stat->usage_array_size(),
298 "Must have same array size");
299 size_t len = dest->usage_array_size() * sizeof(MemoryUsage);
300 memcpy(dest->before_gc_usage_array(), _last_gc_stat->before_gc_usage_array(), len);
301 memcpy(dest->after_gc_usage_array(), _last_gc_stat->after_gc_usage_array(), len);
302 }
303 return _last_gc_stat->gc_index();
304 }