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annotate src/share/vm/services/lowMemoryDetector.hpp @ 6024:973046802b6f
7162955: Attach api on Solaris, too many open files
Summary: Release server-side socket after client receives it.
Reviewed-by: sla, dsamersoff, dcubed, acorn
Contributed-by: dean.long@oracle.com
author | dlong |
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date | Thu, 26 Apr 2012 16:24:15 -0400 |
parents | bf8517f4e4d0 |
children | d2a62e0f25eb |
rev | line source |
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0 | 1 /* |
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2 * Copyright (c) 2003, 2011, Oracle and/or its affiliates. All rights reserved. |
0 | 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 * | |
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
0 | 22 * |
23 */ | |
24 | |
1972 | 25 #ifndef SHARE_VM_SERVICES_LOWMEMORYDETECTOR_HPP |
26 #define SHARE_VM_SERVICES_LOWMEMORYDETECTOR_HPP | |
27 | |
28 #include "memory/allocation.hpp" | |
29 #include "services/memoryPool.hpp" | |
30 #include "services/memoryService.hpp" | |
31 | |
0 | 32 // Low Memory Detection Support |
33 // Two memory alarms in the JDK (we called them sensors). | |
34 // - Heap memory sensor | |
35 // - Non-heap memory sensor | |
36 // When the VM detects if the memory usage of a memory pool has reached | |
37 // or exceeded its threshold, it will trigger the sensor for the type | |
38 // of the memory pool (heap or nonheap or both). | |
39 // | |
40 // If threshold == -1, no low memory detection is supported and | |
41 // the threshold value is not allowed to be changed. | |
42 // If threshold == 0, no low memory detection is performed for | |
43 // that memory pool. The threshold can be set to any non-negative | |
44 // value. | |
45 // | |
46 // The default threshold of the Hotspot memory pools are: | |
47 // Eden space -1 | |
48 // Survivor space 1 -1 | |
49 // Survivor space 2 -1 | |
50 // Old generation 0 | |
51 // Perm generation 0 | |
52 // CodeCache 0 | |
53 // | |
54 // For heap memory, detection will be performed when GC finishes | |
55 // and also in the slow path allocation. | |
56 // For Code cache, detection will be performed in the allocation | |
57 // and deallocation. | |
58 // | |
59 // May need to deal with hysteresis effect. | |
60 // | |
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61 // Memory detection code runs in the Service thread (serviceThread.hpp). |
0 | 62 |
63 class OopClosure; | |
64 class MemoryPool; | |
65 | |
66 class ThresholdSupport : public CHeapObj { | |
67 private: | |
68 bool _support_high_threshold; | |
69 bool _support_low_threshold; | |
70 size_t _high_threshold; | |
71 size_t _low_threshold; | |
72 public: | |
73 ThresholdSupport(bool support_high, bool support_low) { | |
74 _support_high_threshold = support_high; | |
75 _support_low_threshold = support_low; | |
76 _high_threshold = 0; | |
77 _low_threshold= 0; | |
78 } | |
79 | |
80 size_t high_threshold() const { return _high_threshold; } | |
81 size_t low_threshold() const { return _low_threshold; } | |
82 bool is_high_threshold_supported() { return _support_high_threshold; } | |
83 bool is_low_threshold_supported() { return _support_low_threshold; } | |
84 | |
85 bool is_high_threshold_crossed(MemoryUsage usage) { | |
86 if (_support_high_threshold && _high_threshold > 0) { | |
87 return (usage.used() >= _high_threshold); | |
88 } | |
89 return false; | |
90 } | |
91 bool is_low_threshold_crossed(MemoryUsage usage) { | |
92 if (_support_low_threshold && _low_threshold > 0) { | |
93 return (usage.used() < _low_threshold); | |
94 } | |
95 return false; | |
96 } | |
97 | |
98 size_t set_high_threshold(size_t new_threshold) { | |
99 assert(_support_high_threshold, "can only be set if supported"); | |
100 assert(new_threshold >= _low_threshold, "new_threshold must be >= _low_threshold"); | |
101 size_t prev = _high_threshold; | |
102 _high_threshold = new_threshold; | |
103 return prev; | |
104 } | |
105 | |
106 size_t set_low_threshold(size_t new_threshold) { | |
107 assert(_support_low_threshold, "can only be set if supported"); | |
108 assert(new_threshold <= _high_threshold, "new_threshold must be <= _high_threshold"); | |
109 size_t prev = _low_threshold; | |
110 _low_threshold = new_threshold; | |
111 return prev; | |
112 } | |
113 }; | |
114 | |
115 class SensorInfo : public CHeapObj { | |
116 private: | |
117 instanceOop _sensor_obj; | |
118 bool _sensor_on; | |
119 size_t _sensor_count; | |
120 | |
121 // before the actual sensor on flag and sensor count are set | |
122 // we maintain the number of pending triggers and clears. | |
123 // _pending_trigger_count means the number of pending triggers | |
124 // and the sensor count should be incremented by the same number. | |
125 | |
126 int _pending_trigger_count; | |
127 | |
128 // _pending_clear_count takes precedence if it's > 0 which | |
129 // indicates the resulting sensor will be off | |
130 // Sensor trigger requests will reset this clear count to | |
131 // indicate the resulting flag should be on. | |
132 | |
133 int _pending_clear_count; | |
134 | |
135 MemoryUsage _usage; | |
136 | |
137 void clear(int count, TRAPS); | |
138 void trigger(int count, TRAPS); | |
139 public: | |
140 SensorInfo(); | |
141 void set_sensor(instanceOop sensor) { | |
142 assert(_sensor_obj == NULL, "Should be set only once"); | |
143 _sensor_obj = sensor; | |
144 } | |
145 | |
146 bool has_pending_requests() { | |
147 return (_pending_trigger_count > 0 || _pending_clear_count > 0); | |
148 } | |
149 | |
150 int pending_trigger_count() { return _pending_trigger_count; } | |
151 int pending_clear_count() { return _pending_clear_count; } | |
152 | |
153 // When this method is used, the memory usage is monitored | |
154 // as a gauge attribute. High and low thresholds are designed | |
155 // to provide a hysteresis mechanism to avoid repeated triggering | |
156 // of notifications when the attribute value makes small oscillations | |
157 // around the high or low threshold value. | |
158 // | |
159 // The sensor will be triggered if: | |
160 // (1) the usage is crossing above the high threshold and | |
161 // the sensor is currently off and no pending | |
162 // trigger requests; or | |
163 // (2) the usage is crossing above the high threshold and | |
164 // the sensor will be off (i.e. sensor is currently on | |
165 // and has pending clear requests). | |
166 // | |
167 // Subsequent crossings of the high threshold value do not cause | |
168 // any triggers unless the usage becomes less than the low threshold. | |
169 // | |
170 // The sensor will be cleared if: | |
171 // (1) the usage is crossing below the low threshold and | |
172 // the sensor is currently on and no pending | |
173 // clear requests; or | |
174 // (2) the usage is crossing below the low threshold and | |
175 // the sensor will be on (i.e. sensor is currently off | |
176 // and has pending trigger requests). | |
177 // | |
178 // Subsequent crossings of the low threshold value do not cause | |
179 // any clears unless the usage becomes greater than or equal | |
180 // to the high threshold. | |
181 // | |
182 // If the current level is between high and low threhsold, no change. | |
183 // | |
184 void set_gauge_sensor_level(MemoryUsage usage, ThresholdSupport* high_low_threshold); | |
185 | |
186 // When this method is used, the memory usage is monitored as a | |
187 // simple counter attribute. The sensor will be triggered | |
188 // whenever the usage is crossing the threshold to keep track | |
189 // of the number of times the VM detects such a condition occurs. | |
190 // | |
191 // The sensor will be triggered if: | |
192 // - the usage is crossing above the high threshold regardless | |
193 // of the current sensor state. | |
194 // | |
195 // The sensor will be cleared if: | |
196 // (1) the usage is crossing below the low threshold and | |
197 // the sensor is currently on; or | |
198 // (2) the usage is crossing below the low threshold and | |
199 // the sensor will be on (i.e. sensor is currently off | |
200 // and has pending trigger requests). | |
201 // | |
202 void set_counter_sensor_level(MemoryUsage usage, ThresholdSupport* counter_threshold); | |
203 | |
204 void process_pending_requests(TRAPS); | |
205 void oops_do(OopClosure* f); | |
206 | |
207 #ifndef PRODUCT | |
208 // printing on default output stream; | |
209 void print(); | |
210 #endif // PRODUCT | |
211 }; | |
212 | |
213 class LowMemoryDetector : public AllStatic { | |
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214 friend class LowMemoryDetectorDisabler; |
bf8517f4e4d0
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kamg
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215 friend class ServiceThread; |
0 | 216 private: |
217 // true if any collected heap has low memory detection enabled | |
218 static volatile bool _enabled_for_collected_pools; | |
219 // > 0 if temporary disabed | |
220 static volatile jint _disabled_count; | |
221 | |
222 static void check_memory_usage(); | |
223 static bool has_pending_requests(); | |
224 static bool temporary_disabled() { return _disabled_count > 0; } | |
225 static void disable() { Atomic::inc(&_disabled_count); } | |
226 static void enable() { Atomic::dec(&_disabled_count); } | |
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227 static void process_sensor_changes(TRAPS); |
0 | 228 |
229 public: | |
230 static void detect_low_memory(); | |
231 static void detect_low_memory(MemoryPool* pool); | |
232 static void detect_after_gc_memory(MemoryPool* pool); | |
233 | |
234 static bool is_enabled(MemoryPool* pool) { | |
235 // low memory detection is enabled for collected memory pools | |
236 // iff one of the collected memory pool has a sensor and the | |
237 // threshold set non-zero | |
238 if (pool->usage_sensor() == NULL) { | |
239 return false; | |
240 } else { | |
241 ThresholdSupport* threshold_support = pool->usage_threshold(); | |
242 return (threshold_support->is_high_threshold_supported() ? | |
243 (threshold_support->high_threshold() > 0) : false); | |
244 } | |
245 } | |
246 | |
247 // indicates if low memory detection is enabled for any collected | |
248 // memory pools | |
249 static inline bool is_enabled_for_collected_pools() { | |
250 return !temporary_disabled() && _enabled_for_collected_pools; | |
251 } | |
252 | |
253 // recompute enabled flag | |
254 static void recompute_enabled_for_collected_pools(); | |
255 | |
256 // low memory detection for collected memory pools. | |
257 static inline void detect_low_memory_for_collected_pools() { | |
258 // no-op if low memory detection not enabled | |
259 if (!is_enabled_for_collected_pools()) { | |
260 return; | |
261 } | |
262 int num_memory_pools = MemoryService::num_memory_pools(); | |
263 for (int i=0; i<num_memory_pools; i++) { | |
264 MemoryPool* pool = MemoryService::get_memory_pool(i); | |
265 | |
266 // if low memory detection is enabled then check if the | |
267 // current used exceeds the high threshold | |
268 if (pool->is_collected_pool() && is_enabled(pool)) { | |
269 size_t used = pool->used_in_bytes(); | |
270 size_t high = pool->usage_threshold()->high_threshold(); | |
271 if (used > high) { | |
272 detect_low_memory(pool); | |
273 } | |
274 } | |
275 } | |
276 } | |
277 }; | |
278 | |
279 class LowMemoryDetectorDisabler: public StackObj { | |
280 public: | |
281 LowMemoryDetectorDisabler() | |
282 { | |
283 LowMemoryDetector::disable(); | |
284 } | |
285 ~LowMemoryDetectorDisabler() | |
286 { | |
287 assert(LowMemoryDetector::temporary_disabled(), "should be disabled!"); | |
288 LowMemoryDetector::enable(); | |
289 } | |
290 }; | |
1972 | 291 |
292 #endif // SHARE_VM_SERVICES_LOWMEMORYDETECTOR_HPP |