Thu, 21 Aug 2014 16:44:41 +0200
8055098: WB API should be extended to provide information about size and age of object.
Summary: Extend the WhiteBox API to provide information about the size and age of objects. Further add a mechanism to trigger a young GC.
Reviewed-by: tschatzl, sjohanss
Contributed-by: Leonid Mesnik <leonid.mesnik@oracle.com>
jmasa@2821 | 1 | /* |
sla@5237 | 2 | * Copyright (c) 2011, 2013, Oracle and/or its affiliates. All rights reserved. |
jmasa@2821 | 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
jmasa@2821 | 4 | * |
jmasa@2821 | 5 | * This code is free software; you can redistribute it and/or modify it |
jmasa@2821 | 6 | * under the terms of the GNU General Public License version 2 only, as |
jmasa@2821 | 7 | * published by the Free Software Foundation. |
jmasa@2821 | 8 | * |
jmasa@2821 | 9 | * This code is distributed in the hope that it will be useful, but WITHOUT |
jmasa@2821 | 10 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
jmasa@2821 | 11 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
jmasa@2821 | 12 | * version 2 for more details (a copy is included in the LICENSE file that |
jmasa@2821 | 13 | * accompanied this code). |
jmasa@2821 | 14 | * |
jmasa@2821 | 15 | * You should have received a copy of the GNU General Public License version |
jmasa@2821 | 16 | * 2 along with this work; if not, write to the Free Software Foundation, |
jmasa@2821 | 17 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
jmasa@2821 | 18 | * |
jmasa@2821 | 19 | * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
jmasa@2821 | 20 | * or visit www.oracle.com if you need additional information or have any |
jmasa@2821 | 21 | * questions. |
jmasa@2821 | 22 | * |
jmasa@2821 | 23 | */ |
jmasa@2821 | 24 | |
jmasa@2821 | 25 | #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1MONITORINGSUPPORT_HPP |
jmasa@2821 | 26 | #define SHARE_VM_GC_IMPLEMENTATION_G1_G1MONITORINGSUPPORT_HPP |
jmasa@2821 | 27 | |
jmasa@2821 | 28 | #include "gc_implementation/shared/hSpaceCounters.hpp" |
jmasa@2821 | 29 | |
jmasa@2821 | 30 | class G1CollectedHeap; |
jmasa@2821 | 31 | |
tonyp@3176 | 32 | // Class for monitoring logical spaces in G1. It provides data for |
tonyp@3176 | 33 | // both G1's jstat counters as well as G1's memory pools. |
jmasa@2821 | 34 | // |
tonyp@3176 | 35 | // G1 splits the heap into heap regions and each heap region belongs |
tonyp@3176 | 36 | // to one of the following categories: |
jmasa@2821 | 37 | // |
tonyp@3176 | 38 | // * eden : regions that have been allocated since the last GC |
tonyp@3176 | 39 | // * survivors : regions with objects that survived the last few GCs |
tonyp@3176 | 40 | // * old : long-lived non-humongous regions |
tonyp@3176 | 41 | // * humongous : humongous regions |
tonyp@3176 | 42 | // * free : free regions |
jmasa@2821 | 43 | // |
tonyp@3176 | 44 | // The combination of eden and survivor regions form the equivalent of |
tonyp@3176 | 45 | // the young generation in the other GCs. The combination of old and |
tonyp@3176 | 46 | // humongous regions form the equivalent of the old generation in the |
tonyp@3176 | 47 | // other GCs. Free regions do not have a good equivalent in the other |
tonyp@3176 | 48 | // GCs given that they can be allocated as any of the other region types. |
jmasa@2821 | 49 | // |
tonyp@3176 | 50 | // The monitoring tools expect the heap to contain a number of |
tonyp@3176 | 51 | // generations (young, old, perm) and each generation to contain a |
tonyp@3176 | 52 | // number of spaces (young: eden, survivors, old). Given that G1 does |
tonyp@3176 | 53 | // not maintain those spaces physically (e.g., the set of |
tonyp@3176 | 54 | // non-contiguous eden regions can be considered as a "logical" |
tonyp@3176 | 55 | // space), we'll provide the illusion that those generations and |
tonyp@3176 | 56 | // spaces exist. In reality, each generation and space refers to a set |
tonyp@3176 | 57 | // of heap regions that are potentially non-contiguous. |
jmasa@2821 | 58 | // |
tonyp@3176 | 59 | // This class provides interfaces to access the min, current, and max |
tonyp@3176 | 60 | // capacity and current occupancy for each of G1's logical spaces and |
tonyp@3176 | 61 | // generations we expose to the monitoring tools. Also provided are |
tonyp@3176 | 62 | // counters for G1 concurrent collections and stop-the-world full heap |
tonyp@3176 | 63 | // collections. |
jmasa@2821 | 64 | // |
tonyp@3176 | 65 | // Below is a description of how the various sizes are calculated. |
jmasa@2821 | 66 | // |
tonyp@3176 | 67 | // * Current Capacity |
jmasa@2821 | 68 | // |
tonyp@3176 | 69 | // - heap_capacity = current heap capacity (e.g., current committed size) |
tonyp@3176 | 70 | // - young_gen_capacity = current max young gen target capacity |
tonyp@3176 | 71 | // (i.e., young gen target capacity + max allowed expansion capacity) |
tonyp@3176 | 72 | // - survivor_capacity = current survivor region capacity |
tonyp@3176 | 73 | // - eden_capacity = young_gen_capacity - survivor_capacity |
tonyp@3176 | 74 | // - old_capacity = heap_capacity - young_gen_capacity |
jmasa@2821 | 75 | // |
tonyp@3176 | 76 | // What we do in the above is to distribute the free regions among |
tonyp@3176 | 77 | // eden_capacity and old_capacity. |
jmasa@2821 | 78 | // |
tonyp@3176 | 79 | // * Occupancy |
jmasa@2821 | 80 | // |
tonyp@3176 | 81 | // - young_gen_used = current young region capacity |
tonyp@3176 | 82 | // - survivor_used = survivor_capacity |
tonyp@3176 | 83 | // - eden_used = young_gen_used - survivor_used |
tonyp@3176 | 84 | // - old_used = overall_used - young_gen_used |
jmasa@2821 | 85 | // |
tonyp@3176 | 86 | // Unfortunately, we currently only keep track of the number of |
tonyp@3176 | 87 | // currently allocated young and survivor regions + the overall used |
tonyp@3176 | 88 | // bytes in the heap, so the above can be a little inaccurate. |
jmasa@2821 | 89 | // |
tonyp@3176 | 90 | // * Min Capacity |
tonyp@3176 | 91 | // |
tonyp@3459 | 92 | // We set this to 0 for all spaces. |
tonyp@3176 | 93 | // |
tonyp@3176 | 94 | // * Max Capacity |
tonyp@3176 | 95 | // |
tonyp@3176 | 96 | // For jstat, we set the max capacity of all spaces to heap_capacity, |
tonyp@3459 | 97 | // given that we don't always have a reasonable upper bound on how big |
tonyp@3459 | 98 | // each space can grow. For the memory pools, we make the max |
tonyp@3459 | 99 | // capacity undefined with the exception of the old memory pool for |
tonyp@3459 | 100 | // which we make the max capacity same as the max heap capacity. |
tonyp@3176 | 101 | // |
tonyp@3176 | 102 | // If we had more accurate occupancy / capacity information per |
tonyp@3176 | 103 | // region set the above calculations would be greatly simplified and |
tonyp@3176 | 104 | // be made more accurate. |
tonyp@3176 | 105 | // |
tonyp@3176 | 106 | // We update all the above synchronously and we store the results in |
tonyp@3176 | 107 | // fields so that we just read said fields when needed. A subtle point |
tonyp@3176 | 108 | // is that all the above sizes need to be recalculated when the old |
tonyp@3176 | 109 | // gen changes capacity (after a GC or after a humongous allocation) |
tonyp@3176 | 110 | // but only the eden occupancy changes when a new eden region is |
tonyp@3176 | 111 | // allocated. So, in the latter case we have minimal recalcuation to |
tonyp@3176 | 112 | // do which is important as we want to keep the eden region allocation |
tonyp@3176 | 113 | // path as low-overhead as possible. |
jmasa@2821 | 114 | |
zgu@3900 | 115 | class G1MonitoringSupport : public CHeapObj<mtGC> { |
tonyp@3180 | 116 | friend class VMStructs; |
tonyp@3180 | 117 | |
jmasa@2821 | 118 | G1CollectedHeap* _g1h; |
jmasa@2821 | 119 | |
jmasa@2821 | 120 | // jstat performance counters |
tonyp@3337 | 121 | // incremental collections both young and mixed |
jmasa@2821 | 122 | CollectorCounters* _incremental_collection_counters; |
jmasa@2821 | 123 | // full stop-the-world collections |
jmasa@2821 | 124 | CollectorCounters* _full_collection_counters; |
jmasa@2821 | 125 | // young collection set counters. The _eden_counters, |
jmasa@2821 | 126 | // _from_counters, and _to_counters are associated with |
jmasa@2821 | 127 | // this "generational" counter. |
jmasa@2821 | 128 | GenerationCounters* _young_collection_counters; |
tonyp@3176 | 129 | // old collection set counters. The _old_space_counters |
jmasa@2821 | 130 | // below are associated with this "generational" counter. |
tonyp@3176 | 131 | GenerationCounters* _old_collection_counters; |
jmasa@2821 | 132 | // Counters for the capacity and used for |
jmasa@2821 | 133 | // the whole heap |
jmasa@2821 | 134 | HSpaceCounters* _old_space_counters; |
jmasa@2821 | 135 | // the young collection |
jmasa@2821 | 136 | HSpaceCounters* _eden_counters; |
jmasa@2821 | 137 | // the survivor collection (only one, _to_counters, is actively used) |
jmasa@2821 | 138 | HSpaceCounters* _from_counters; |
jmasa@2821 | 139 | HSpaceCounters* _to_counters; |
jmasa@2821 | 140 | |
tonyp@3176 | 141 | // When it's appropriate to recalculate the various sizes (at the |
tonyp@3176 | 142 | // end of a GC, when a new eden region is allocated, etc.) we store |
tonyp@3176 | 143 | // them here so that we can easily report them when needed and not |
tonyp@3176 | 144 | // have to recalculate them every time. |
tonyp@3176 | 145 | |
tonyp@3176 | 146 | size_t _overall_reserved; |
tonyp@3176 | 147 | size_t _overall_committed; |
tonyp@3176 | 148 | size_t _overall_used; |
tonyp@3176 | 149 | |
tonyp@3713 | 150 | uint _young_region_num; |
tonyp@3176 | 151 | size_t _young_gen_committed; |
tonyp@3176 | 152 | size_t _eden_committed; |
tonyp@3176 | 153 | size_t _eden_used; |
tonyp@3176 | 154 | size_t _survivor_committed; |
tonyp@3176 | 155 | size_t _survivor_used; |
tonyp@3176 | 156 | |
tonyp@3176 | 157 | size_t _old_committed; |
tonyp@3176 | 158 | size_t _old_used; |
tonyp@3176 | 159 | |
tonyp@3176 | 160 | G1CollectedHeap* g1h() { return _g1h; } |
tonyp@3176 | 161 | |
jmasa@2821 | 162 | // It returns x - y if x > y, 0 otherwise. |
jmasa@2821 | 163 | // As described in the comment above, some of the inputs to the |
jmasa@2821 | 164 | // calculations we have to do are obtained concurrently and hence |
jmasa@2821 | 165 | // may be inconsistent with each other. So, this provides a |
jmasa@2821 | 166 | // defensive way of performing the subtraction and avoids the value |
jmasa@2821 | 167 | // going negative (which would mean a very large result, given that |
jmasa@2821 | 168 | // the parameter are size_t). |
jmasa@2821 | 169 | static size_t subtract_up_to_zero(size_t x, size_t y) { |
jmasa@2821 | 170 | if (x > y) { |
jmasa@2821 | 171 | return x - y; |
jmasa@2821 | 172 | } else { |
jmasa@2821 | 173 | return 0; |
jmasa@2821 | 174 | } |
jmasa@2821 | 175 | } |
jmasa@2821 | 176 | |
tonyp@3176 | 177 | // Recalculate all the sizes. |
tonyp@3176 | 178 | void recalculate_sizes(); |
tonyp@3176 | 179 | // Recalculate only what's necessary when a new eden region is allocated. |
tonyp@3176 | 180 | void recalculate_eden_size(); |
tonyp@3176 | 181 | |
jmasa@2821 | 182 | public: |
tonyp@3176 | 183 | G1MonitoringSupport(G1CollectedHeap* g1h); |
jmasa@2821 | 184 | |
tonyp@3176 | 185 | // Unfortunately, the jstat tool assumes that no space has 0 |
tonyp@3176 | 186 | // capacity. In our case, given that each space is logical, it's |
tonyp@3176 | 187 | // possible that no regions will be allocated to it, hence to have 0 |
tonyp@3176 | 188 | // capacity (e.g., if there are no survivor regions, the survivor |
tonyp@3176 | 189 | // space has 0 capacity). The way we deal with this is to always pad |
tonyp@3176 | 190 | // each capacity value we report to jstat by a very small amount to |
tonyp@3176 | 191 | // make sure that it's never zero. Given that we sometimes have to |
tonyp@3176 | 192 | // report a capacity of a generation that contains several spaces |
tonyp@3176 | 193 | // (e.g., young gen includes one eden, two survivor spaces), the |
tonyp@3176 | 194 | // mult parameter is provided in order to adding the appropriate |
tonyp@3176 | 195 | // padding multiple times so that the capacities add up correctly. |
tonyp@3176 | 196 | static size_t pad_capacity(size_t size_bytes, size_t mult = 1) { |
tonyp@3176 | 197 | return size_bytes + MinObjAlignmentInBytes * mult; |
tonyp@3176 | 198 | } |
jmasa@2821 | 199 | |
tonyp@3176 | 200 | // Recalculate all the sizes from scratch and update all the jstat |
tonyp@3176 | 201 | // counters accordingly. |
tonyp@3176 | 202 | void update_sizes(); |
tonyp@3176 | 203 | // Recalculate only what's necessary when a new eden region is |
tonyp@3176 | 204 | // allocated and update any jstat counters that need to be updated. |
tonyp@3176 | 205 | void update_eden_size(); |
jmasa@2821 | 206 | |
jmasa@2821 | 207 | CollectorCounters* incremental_collection_counters() { |
jmasa@2821 | 208 | return _incremental_collection_counters; |
jmasa@2821 | 209 | } |
jmasa@2821 | 210 | CollectorCounters* full_collection_counters() { |
jmasa@2821 | 211 | return _full_collection_counters; |
jmasa@2821 | 212 | } |
tonyp@3176 | 213 | GenerationCounters* young_collection_counters() { |
tonyp@3176 | 214 | return _young_collection_counters; |
tonyp@3176 | 215 | } |
tonyp@3176 | 216 | GenerationCounters* old_collection_counters() { |
tonyp@3176 | 217 | return _old_collection_counters; |
jmasa@2821 | 218 | } |
jmasa@2821 | 219 | HSpaceCounters* old_space_counters() { return _old_space_counters; } |
jmasa@2821 | 220 | HSpaceCounters* eden_counters() { return _eden_counters; } |
jmasa@2821 | 221 | HSpaceCounters* from_counters() { return _from_counters; } |
jmasa@2821 | 222 | HSpaceCounters* to_counters() { return _to_counters; } |
jmasa@2821 | 223 | |
jmasa@2821 | 224 | // Monitoring support used by |
jmasa@2821 | 225 | // MemoryService |
jmasa@2821 | 226 | // jstat counters |
sla@5237 | 227 | // Tracing |
jmasa@2821 | 228 | |
tonyp@3176 | 229 | size_t overall_reserved() { return _overall_reserved; } |
tonyp@3176 | 230 | size_t overall_committed() { return _overall_committed; } |
tonyp@3176 | 231 | size_t overall_used() { return _overall_used; } |
jmasa@2821 | 232 | |
tonyp@3176 | 233 | size_t young_gen_committed() { return _young_gen_committed; } |
tonyp@3176 | 234 | size_t young_gen_max() { return overall_reserved(); } |
tonyp@3176 | 235 | size_t eden_space_committed() { return _eden_committed; } |
tonyp@3176 | 236 | size_t eden_space_used() { return _eden_used; } |
tonyp@3176 | 237 | size_t survivor_space_committed() { return _survivor_committed; } |
tonyp@3176 | 238 | size_t survivor_space_used() { return _survivor_used; } |
jmasa@2821 | 239 | |
tonyp@3176 | 240 | size_t old_gen_committed() { return old_space_committed(); } |
tonyp@3176 | 241 | size_t old_gen_max() { return overall_reserved(); } |
tonyp@3176 | 242 | size_t old_space_committed() { return _old_committed; } |
tonyp@3176 | 243 | size_t old_space_used() { return _old_used; } |
tonyp@3176 | 244 | }; |
tonyp@3176 | 245 | |
tonyp@3176 | 246 | class G1GenerationCounters: public GenerationCounters { |
tonyp@3176 | 247 | protected: |
tonyp@3176 | 248 | G1MonitoringSupport* _g1mm; |
tonyp@3176 | 249 | |
tonyp@3176 | 250 | public: |
tonyp@3176 | 251 | G1GenerationCounters(G1MonitoringSupport* g1mm, |
tonyp@3176 | 252 | const char* name, int ordinal, int spaces, |
tonyp@3176 | 253 | size_t min_capacity, size_t max_capacity, |
tonyp@3176 | 254 | size_t curr_capacity); |
tonyp@3176 | 255 | }; |
tonyp@3176 | 256 | |
tonyp@3176 | 257 | class G1YoungGenerationCounters: public G1GenerationCounters { |
tonyp@3176 | 258 | public: |
tonyp@3176 | 259 | G1YoungGenerationCounters(G1MonitoringSupport* g1mm, const char* name); |
tonyp@3176 | 260 | virtual void update_all(); |
tonyp@3176 | 261 | }; |
tonyp@3176 | 262 | |
tonyp@3176 | 263 | class G1OldGenerationCounters: public G1GenerationCounters { |
tonyp@3176 | 264 | public: |
tonyp@3176 | 265 | G1OldGenerationCounters(G1MonitoringSupport* g1mm, const char* name); |
tonyp@3176 | 266 | virtual void update_all(); |
jmasa@2821 | 267 | }; |
jmasa@2821 | 268 | |
jmasa@2821 | 269 | #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1MONITORINGSUPPORT_HPP |