Mercurial > hg > graal-compiler
annotate src/share/vm/memory/collectorPolicy.cpp @ 452:00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
Summary: When we encounter marking stack overflow during precleaning of Reference lists, we were using the overflow list mechanism, which can cause problems on account of mutating the mark word of the header because of conflicts with mutator accesses and updates of that field. Instead we should use the usual mechanism for overflow handling in concurrent phases, namely dirtying of the card on which the overflowed object lies. Since precleaning effectively does a form of discovered list processing, albeit with discovery enabled, we needed to adjust some code to be correct in the face of interleaved processing and discovery.
Reviewed-by: apetrusenko, jcoomes
author | ysr |
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date | Thu, 20 Nov 2008 12:27:41 -0800 |
parents | 1ee8caae33af |
children | 473cce303f13 |
rev | line source |
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0 | 1 /* |
196 | 2 * Copyright 2001-2008 Sun Microsystems, Inc. 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 * | |
19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, | |
20 * CA 95054 USA or visit www.sun.com if you need additional information or | |
21 * have any questions. | |
22 * | |
23 */ | |
24 | |
25 # include "incls/_precompiled.incl" | |
26 # include "incls/_collectorPolicy.cpp.incl" | |
27 | |
28 // CollectorPolicy methods. | |
29 | |
30 void CollectorPolicy::initialize_flags() { | |
31 if (PermSize > MaxPermSize) { | |
32 MaxPermSize = PermSize; | |
33 } | |
342
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34 PermSize = MAX2(min_alignment(), align_size_down_(PermSize, min_alignment())); |
0 | 35 MaxPermSize = align_size_up(MaxPermSize, max_alignment()); |
36 | |
342
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37 MinPermHeapExpansion = MAX2(min_alignment(), align_size_down_(MinPermHeapExpansion, min_alignment())); |
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38 MaxPermHeapExpansion = MAX2(min_alignment(), align_size_down_(MaxPermHeapExpansion, min_alignment())); |
0 | 39 |
40 MinHeapDeltaBytes = align_size_up(MinHeapDeltaBytes, min_alignment()); | |
41 | |
42 SharedReadOnlySize = align_size_up(SharedReadOnlySize, max_alignment()); | |
43 SharedReadWriteSize = align_size_up(SharedReadWriteSize, max_alignment()); | |
44 SharedMiscDataSize = align_size_up(SharedMiscDataSize, max_alignment()); | |
45 | |
46 assert(PermSize % min_alignment() == 0, "permanent space alignment"); | |
47 assert(MaxPermSize % max_alignment() == 0, "maximum permanent space alignment"); | |
48 assert(SharedReadOnlySize % max_alignment() == 0, "read-only space alignment"); | |
49 assert(SharedReadWriteSize % max_alignment() == 0, "read-write space alignment"); | |
50 assert(SharedMiscDataSize % max_alignment() == 0, "misc-data space alignment"); | |
51 if (PermSize < M) { | |
52 vm_exit_during_initialization("Too small initial permanent heap"); | |
53 } | |
54 } | |
55 | |
56 void CollectorPolicy::initialize_size_info() { | |
57 // User inputs from -mx and ms are aligned | |
342
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58 set_initial_heap_byte_size(Arguments::initial_heap_size()); |
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59 if (initial_heap_byte_size() == 0) { |
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60 set_initial_heap_byte_size(NewSize + OldSize); |
0 | 61 } |
342
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62 set_initial_heap_byte_size(align_size_up(_initial_heap_byte_size, |
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63 min_alignment())); |
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64 |
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65 set_min_heap_byte_size(Arguments::min_heap_size()); |
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66 if (min_heap_byte_size() == 0) { |
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67 set_min_heap_byte_size(NewSize + OldSize); |
0 | 68 } |
342
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69 set_min_heap_byte_size(align_size_up(_min_heap_byte_size, |
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70 min_alignment())); |
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71 |
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72 set_max_heap_byte_size(align_size_up(MaxHeapSize, max_alignment())); |
0 | 73 |
74 // Check heap parameter properties | |
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75 if (initial_heap_byte_size() < M) { |
0 | 76 vm_exit_during_initialization("Too small initial heap"); |
77 } | |
78 // Check heap parameter properties | |
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79 if (min_heap_byte_size() < M) { |
0 | 80 vm_exit_during_initialization("Too small minimum heap"); |
81 } | |
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82 if (initial_heap_byte_size() <= NewSize) { |
0 | 83 // make sure there is at least some room in old space |
84 vm_exit_during_initialization("Too small initial heap for new size specified"); | |
85 } | |
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86 if (max_heap_byte_size() < min_heap_byte_size()) { |
0 | 87 vm_exit_during_initialization("Incompatible minimum and maximum heap sizes specified"); |
88 } | |
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89 if (initial_heap_byte_size() < min_heap_byte_size()) { |
0 | 90 vm_exit_during_initialization("Incompatible minimum and initial heap sizes specified"); |
91 } | |
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92 if (max_heap_byte_size() < initial_heap_byte_size()) { |
0 | 93 vm_exit_during_initialization("Incompatible initial and maximum heap sizes specified"); |
94 } | |
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95 |
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96 if (PrintGCDetails && Verbose) { |
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97 gclog_or_tty->print_cr("Minimum heap " SIZE_FORMAT " Initial heap " |
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98 SIZE_FORMAT " Maximum heap " SIZE_FORMAT, |
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99 min_heap_byte_size(), initial_heap_byte_size(), max_heap_byte_size()); |
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100 } |
0 | 101 } |
102 | |
103 void CollectorPolicy::initialize_perm_generation(PermGen::Name pgnm) { | |
104 _permanent_generation = | |
105 new PermanentGenerationSpec(pgnm, PermSize, MaxPermSize, | |
106 SharedReadOnlySize, | |
107 SharedReadWriteSize, | |
108 SharedMiscDataSize, | |
109 SharedMiscCodeSize); | |
110 if (_permanent_generation == NULL) { | |
111 vm_exit_during_initialization("Unable to allocate gen spec"); | |
112 } | |
113 } | |
114 | |
115 | |
116 GenRemSet* CollectorPolicy::create_rem_set(MemRegion whole_heap, | |
117 int max_covered_regions) { | |
118 switch (rem_set_name()) { | |
119 case GenRemSet::CardTable: { | |
120 CardTableRS* res = new CardTableRS(whole_heap, max_covered_regions); | |
121 return res; | |
122 } | |
123 default: | |
124 guarantee(false, "unrecognized GenRemSet::Name"); | |
125 return NULL; | |
126 } | |
127 } | |
128 | |
129 // GenCollectorPolicy methods. | |
130 | |
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131 size_t GenCollectorPolicy::scale_by_NewRatio_aligned(size_t base_size) { |
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132 size_t x = base_size / (NewRatio+1); |
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133 size_t new_gen_size = x > min_alignment() ? |
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134 align_size_down(x, min_alignment()) : |
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135 min_alignment(); |
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136 return new_gen_size; |
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137 } |
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138 |
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139 size_t GenCollectorPolicy::bound_minus_alignment(size_t desired_size, |
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140 size_t maximum_size) { |
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141 size_t alignment = min_alignment(); |
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142 size_t max_minus = maximum_size - alignment; |
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143 return desired_size < max_minus ? desired_size : max_minus; |
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144 } |
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145 |
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146 |
0 | 147 void GenCollectorPolicy::initialize_size_policy(size_t init_eden_size, |
148 size_t init_promo_size, | |
149 size_t init_survivor_size) { | |
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150 const double max_gc_minor_pause_sec = ((double) MaxGCMinorPauseMillis)/1000.0; |
0 | 151 _size_policy = new AdaptiveSizePolicy(init_eden_size, |
152 init_promo_size, | |
153 init_survivor_size, | |
154 max_gc_minor_pause_sec, | |
155 GCTimeRatio); | |
156 } | |
157 | |
158 size_t GenCollectorPolicy::compute_max_alignment() { | |
159 // The card marking array and the offset arrays for old generations are | |
160 // committed in os pages as well. Make sure they are entirely full (to | |
161 // avoid partial page problems), e.g. if 512 bytes heap corresponds to 1 | |
162 // byte entry and the os page size is 4096, the maximum heap size should | |
163 // be 512*4096 = 2MB aligned. | |
164 size_t alignment = GenRemSet::max_alignment_constraint(rem_set_name()); | |
165 | |
166 // Parallel GC does its own alignment of the generations to avoid requiring a | |
167 // large page (256M on some platforms) for the permanent generation. The | |
168 // other collectors should also be updated to do their own alignment and then | |
169 // this use of lcm() should be removed. | |
170 if (UseLargePages && !UseParallelGC) { | |
171 // in presence of large pages we have to make sure that our | |
172 // alignment is large page aware | |
173 alignment = lcm(os::large_page_size(), alignment); | |
174 } | |
175 | |
176 return alignment; | |
177 } | |
178 | |
179 void GenCollectorPolicy::initialize_flags() { | |
180 // All sizes must be multiples of the generation granularity. | |
181 set_min_alignment((uintx) Generation::GenGrain); | |
182 set_max_alignment(compute_max_alignment()); | |
183 assert(max_alignment() >= min_alignment() && | |
184 max_alignment() % min_alignment() == 0, | |
185 "invalid alignment constraints"); | |
186 | |
187 CollectorPolicy::initialize_flags(); | |
188 | |
189 // All generational heaps have a youngest gen; handle those flags here. | |
190 | |
191 // Adjust max size parameters | |
192 if (NewSize > MaxNewSize) { | |
193 MaxNewSize = NewSize; | |
194 } | |
195 NewSize = align_size_down(NewSize, min_alignment()); | |
196 MaxNewSize = align_size_down(MaxNewSize, min_alignment()); | |
197 | |
198 // Check validity of heap flags | |
199 assert(NewSize % min_alignment() == 0, "eden space alignment"); | |
200 assert(MaxNewSize % min_alignment() == 0, "survivor space alignment"); | |
201 | |
202 if (NewSize < 3*min_alignment()) { | |
203 // make sure there room for eden and two survivor spaces | |
204 vm_exit_during_initialization("Too small new size specified"); | |
205 } | |
206 if (SurvivorRatio < 1 || NewRatio < 1) { | |
207 vm_exit_during_initialization("Invalid heap ratio specified"); | |
208 } | |
209 } | |
210 | |
211 void TwoGenerationCollectorPolicy::initialize_flags() { | |
212 GenCollectorPolicy::initialize_flags(); | |
213 | |
214 OldSize = align_size_down(OldSize, min_alignment()); | |
215 if (NewSize + OldSize > MaxHeapSize) { | |
216 MaxHeapSize = NewSize + OldSize; | |
217 } | |
218 MaxHeapSize = align_size_up(MaxHeapSize, max_alignment()); | |
219 | |
220 always_do_update_barrier = UseConcMarkSweepGC; | |
221 BlockOffsetArrayUseUnallocatedBlock = | |
222 BlockOffsetArrayUseUnallocatedBlock || ParallelGCThreads > 0; | |
223 | |
224 // Check validity of heap flags | |
225 assert(OldSize % min_alignment() == 0, "old space alignment"); | |
226 assert(MaxHeapSize % max_alignment() == 0, "maximum heap alignment"); | |
227 } | |
228 | |
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229 // Values set on the command line win over any ergonomically |
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230 // set command line parameters. |
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231 // Ergonomic choice of parameters are done before this |
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232 // method is called. Values for command line parameters such as NewSize |
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233 // and MaxNewSize feed those ergonomic choices into this method. |
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234 // This method makes the final generation sizings consistent with |
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235 // themselves and with overall heap sizings. |
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236 // In the absence of explicitly set command line flags, policies |
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237 // such as the use of NewRatio are used to size the generation. |
0 | 238 void GenCollectorPolicy::initialize_size_info() { |
239 CollectorPolicy::initialize_size_info(); | |
240 | |
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241 // min_alignment() is used for alignment within a generation. |
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242 // There is additional alignment done down stream for some |
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243 // collectors that sometimes causes unwanted rounding up of |
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244 // generations sizes. |
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245 |
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246 // Determine maximum size of gen0 |
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247 |
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248 size_t max_new_size = 0; |
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249 if (FLAG_IS_CMDLINE(MaxNewSize)) { |
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250 if (MaxNewSize < min_alignment()) { |
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251 max_new_size = min_alignment(); |
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252 } else if (MaxNewSize >= max_heap_byte_size()) { |
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253 max_new_size = align_size_down(max_heap_byte_size() - min_alignment(), |
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254 min_alignment()); |
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255 warning("MaxNewSize (" SIZE_FORMAT "k) is equal to or " |
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256 "greater than the entire heap (" SIZE_FORMAT "k). A " |
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257 "new generation size of " SIZE_FORMAT "k will be used.", |
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258 MaxNewSize/K, max_heap_byte_size()/K, max_new_size/K); |
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259 } else { |
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260 max_new_size = align_size_down(MaxNewSize, min_alignment()); |
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261 } |
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262 |
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263 // The case for FLAG_IS_ERGO(MaxNewSize) could be treated |
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264 // specially at this point to just use an ergonomically set |
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265 // MaxNewSize to set max_new_size. For cases with small |
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266 // heaps such a policy often did not work because the MaxNewSize |
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267 // was larger than the entire heap. The interpretation given |
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268 // to ergonomically set flags is that the flags are set |
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269 // by different collectors for their own special needs but |
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270 // are not allowed to badly shape the heap. This allows the |
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271 // different collectors to decide what's best for themselves |
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272 // without having to factor in the overall heap shape. It |
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273 // can be the case in the future that the collectors would |
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274 // only make "wise" ergonomics choices and this policy could |
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275 // just accept those choices. The choices currently made are |
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276 // not always "wise". |
0 | 277 } else { |
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278 max_new_size = scale_by_NewRatio_aligned(max_heap_byte_size()); |
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279 // Bound the maximum size by NewSize below (since it historically |
0 | 280 // would have been NewSize and because the NewRatio calculation could |
281 // yield a size that is too small) and bound it by MaxNewSize above. | |
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282 // Ergonomics plays here by previously calculating the desired |
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283 // NewSize and MaxNewSize. |
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284 max_new_size = MIN2(MAX2(max_new_size, NewSize), MaxNewSize); |
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285 } |
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286 assert(max_new_size > 0, "All paths should set max_new_size"); |
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287 |
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288 // Given the maximum gen0 size, determine the initial and |
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289 // minimum sizes. |
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290 |
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291 if (max_heap_byte_size() == min_heap_byte_size()) { |
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292 // The maximum and minimum heap sizes are the same so |
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293 // the generations minimum and initial must be the |
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294 // same as its maximum. |
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295 set_min_gen0_size(max_new_size); |
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296 set_initial_gen0_size(max_new_size); |
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297 set_max_gen0_size(max_new_size); |
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298 } else { |
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299 size_t desired_new_size = 0; |
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300 if (!FLAG_IS_DEFAULT(NewSize)) { |
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301 // If NewSize is set ergonomically (for example by cms), it |
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302 // would make sense to use it. If it is used, also use it |
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303 // to set the initial size. Although there is no reason |
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304 // the minimum size and the initial size have to be the same, |
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305 // the current implementation gets into trouble during the calculation |
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306 // of the tenured generation sizes if they are different. |
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307 // Note that this makes the initial size and the minimum size |
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308 // generally small compared to the NewRatio calculation. |
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309 _min_gen0_size = NewSize; |
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310 desired_new_size = NewSize; |
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311 max_new_size = MAX2(max_new_size, NewSize); |
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312 } else { |
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313 // For the case where NewSize is the default, use NewRatio |
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314 // to size the minimum and initial generation sizes. |
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315 // Use the default NewSize as the floor for these values. If |
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316 // NewRatio is overly large, the resulting sizes can be too |
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317 // small. |
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318 _min_gen0_size = MAX2(scale_by_NewRatio_aligned(min_heap_byte_size()), |
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319 NewSize); |
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320 desired_new_size = |
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321 MAX2(scale_by_NewRatio_aligned(initial_heap_byte_size()), |
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322 NewSize); |
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323 } |
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324 |
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325 assert(_min_gen0_size > 0, "Sanity check"); |
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326 set_initial_gen0_size(desired_new_size); |
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327 set_max_gen0_size(max_new_size); |
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328 |
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329 // At this point the desirable initial and minimum sizes have been |
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330 // determined without regard to the maximum sizes. |
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331 |
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332 // Bound the sizes by the corresponding overall heap sizes. |
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333 set_min_gen0_size( |
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334 bound_minus_alignment(_min_gen0_size, min_heap_byte_size())); |
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335 set_initial_gen0_size( |
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336 bound_minus_alignment(_initial_gen0_size, initial_heap_byte_size())); |
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337 set_max_gen0_size( |
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338 bound_minus_alignment(_max_gen0_size, max_heap_byte_size())); |
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339 |
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340 // At this point all three sizes have been checked against the |
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341 // maximum sizes but have not been checked for consistency |
342
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342 // among the three. |
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343 |
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344 // Final check min <= initial <= max |
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345 set_min_gen0_size(MIN2(_min_gen0_size, _max_gen0_size)); |
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346 set_initial_gen0_size( |
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347 MAX2(MIN2(_initial_gen0_size, _max_gen0_size), _min_gen0_size)); |
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348 set_min_gen0_size(MIN2(_min_gen0_size, _initial_gen0_size)); |
0 | 349 } |
350 | |
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351 if (PrintGCDetails && Verbose) { |
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352 gclog_or_tty->print_cr("Minimum gen0 " SIZE_FORMAT " Initial gen0 " |
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353 SIZE_FORMAT " Maximum gen0 " SIZE_FORMAT, |
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354 min_gen0_size(), initial_gen0_size(), max_gen0_size()); |
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355 } |
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356 } |
0 | 357 |
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358 // Call this method during the sizing of the gen1 to make |
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359 // adjustments to gen0 because of gen1 sizing policy. gen0 initially has |
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360 // the most freedom in sizing because it is done before the |
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361 // policy for gen1 is applied. Once gen1 policies have been applied, |
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362 // there may be conflicts in the shape of the heap and this method |
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363 // is used to make the needed adjustments. The application of the |
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364 // policies could be more sophisticated (iterative for example) but |
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365 // keeping it simple also seems a worthwhile goal. |
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366 bool TwoGenerationCollectorPolicy::adjust_gen0_sizes(size_t* gen0_size_ptr, |
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367 size_t* gen1_size_ptr, |
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368 size_t heap_size, |
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369 size_t min_gen0_size) { |
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370 bool result = false; |
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371 if ((*gen1_size_ptr + *gen0_size_ptr) > heap_size) { |
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372 if (((*gen0_size_ptr + OldSize) > heap_size) && |
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373 (heap_size - min_gen0_size) >= min_alignment()) { |
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374 // Adjust gen0 down to accomodate OldSize |
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375 *gen0_size_ptr = heap_size - min_gen0_size; |
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376 *gen0_size_ptr = |
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377 MAX2((uintx)align_size_down(*gen0_size_ptr, min_alignment()), |
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378 min_alignment()); |
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379 assert(*gen0_size_ptr > 0, "Min gen0 is too large"); |
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380 result = true; |
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381 } else { |
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382 *gen1_size_ptr = heap_size - *gen0_size_ptr; |
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383 *gen1_size_ptr = |
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384 MAX2((uintx)align_size_down(*gen1_size_ptr, min_alignment()), |
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385 min_alignment()); |
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386 } |
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387 } |
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388 return result; |
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389 } |
0 | 390 |
13
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391 // Minimum sizes of the generations may be different than |
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392 // the initial sizes. An inconsistently is permitted here |
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393 // in the total size that can be specified explicitly by |
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394 // command line specification of OldSize and NewSize and |
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395 // also a command line specification of -Xms. Issue a warning |
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396 // but allow the values to pass. |
0 | 397 |
398 void TwoGenerationCollectorPolicy::initialize_size_info() { | |
399 GenCollectorPolicy::initialize_size_info(); | |
400 | |
13
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401 // At this point the minimum, initial and maximum sizes |
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402 // of the overall heap and of gen0 have been determined. |
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403 // The maximum gen1 size can be determined from the maximum gen0 |
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404 // and maximum heap size since not explicit flags exits |
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405 // for setting the gen1 maximum. |
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406 _max_gen1_size = max_heap_byte_size() - _max_gen0_size; |
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407 _max_gen1_size = |
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408 MAX2((uintx)align_size_down(_max_gen1_size, min_alignment()), |
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409 min_alignment()); |
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410 // If no explicit command line flag has been set for the |
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411 // gen1 size, use what is left for gen1. |
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412 if (FLAG_IS_DEFAULT(OldSize) || FLAG_IS_ERGO(OldSize)) { |
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413 // The user has not specified any value or ergonomics |
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414 // has chosen a value (which may or may not be consistent |
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415 // with the overall heap size). In either case make |
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416 // the minimum, maximum and initial sizes consistent |
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417 // with the gen0 sizes and the overall heap sizes. |
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418 assert(min_heap_byte_size() > _min_gen0_size, |
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419 "gen0 has an unexpected minimum size"); |
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420 set_min_gen1_size(min_heap_byte_size() - min_gen0_size()); |
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421 set_min_gen1_size( |
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422 MAX2((uintx)align_size_down(_min_gen1_size, min_alignment()), |
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423 min_alignment())); |
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424 set_initial_gen1_size(initial_heap_byte_size() - initial_gen0_size()); |
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425 set_initial_gen1_size( |
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426 MAX2((uintx)align_size_down(_initial_gen1_size, min_alignment()), |
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427 min_alignment())); |
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428 |
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429 } else { |
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430 // It's been explicitly set on the command line. Use the |
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431 // OldSize and then determine the consequences. |
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432 set_min_gen1_size(OldSize); |
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433 set_initial_gen1_size(OldSize); |
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434 |
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435 // If the user has explicitly set an OldSize that is inconsistent |
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436 // with other command line flags, issue a warning. |
0 | 437 // The generation minimums and the overall heap mimimum should |
438 // be within one heap alignment. | |
13
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439 if ((_min_gen1_size + _min_gen0_size + min_alignment()) < |
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440 min_heap_byte_size()) { |
0 | 441 warning("Inconsistency between minimum heap size and minimum " |
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442 "generation sizes: using minimum heap = " SIZE_FORMAT, |
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443 min_heap_byte_size()); |
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444 } |
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445 if ((OldSize > _max_gen1_size)) { |
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446 warning("Inconsistency between maximum heap size and maximum " |
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447 "generation sizes: using maximum heap = " SIZE_FORMAT |
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448 " -XX:OldSize flag is being ignored", |
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449 max_heap_byte_size()); |
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450 } |
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451 // If there is an inconsistency between the OldSize and the minimum and/or |
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452 // initial size of gen0, since OldSize was explicitly set, OldSize wins. |
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453 if (adjust_gen0_sizes(&_min_gen0_size, &_min_gen1_size, |
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454 min_heap_byte_size(), OldSize)) { |
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455 if (PrintGCDetails && Verbose) { |
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456 gclog_or_tty->print_cr("Minimum gen0 " SIZE_FORMAT " Initial gen0 " |
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457 SIZE_FORMAT " Maximum gen0 " SIZE_FORMAT, |
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458 min_gen0_size(), initial_gen0_size(), max_gen0_size()); |
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459 } |
0 | 460 } |
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461 // Initial size |
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462 if (adjust_gen0_sizes(&_initial_gen0_size, &_initial_gen1_size, |
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463 initial_heap_byte_size(), OldSize)) { |
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464 if (PrintGCDetails && Verbose) { |
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465 gclog_or_tty->print_cr("Minimum gen0 " SIZE_FORMAT " Initial gen0 " |
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466 SIZE_FORMAT " Maximum gen0 " SIZE_FORMAT, |
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467 min_gen0_size(), initial_gen0_size(), max_gen0_size()); |
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468 } |
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469 } |
0 | 470 } |
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471 // Enforce the maximum gen1 size. |
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472 set_min_gen1_size(MIN2(_min_gen1_size, _max_gen1_size)); |
0 | 473 |
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474 // Check that min gen1 <= initial gen1 <= max gen1 |
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475 set_initial_gen1_size(MAX2(_initial_gen1_size, _min_gen1_size)); |
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476 set_initial_gen1_size(MIN2(_initial_gen1_size, _max_gen1_size)); |
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477 |
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478 if (PrintGCDetails && Verbose) { |
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479 gclog_or_tty->print_cr("Minimum gen1 " SIZE_FORMAT " Initial gen1 " |
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480 SIZE_FORMAT " Maximum gen1 " SIZE_FORMAT, |
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481 min_gen1_size(), initial_gen1_size(), max_gen1_size()); |
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482 } |
0 | 483 } |
484 | |
485 HeapWord* GenCollectorPolicy::mem_allocate_work(size_t size, | |
486 bool is_tlab, | |
487 bool* gc_overhead_limit_was_exceeded) { | |
488 GenCollectedHeap *gch = GenCollectedHeap::heap(); | |
489 | |
490 debug_only(gch->check_for_valid_allocation_state()); | |
491 assert(gch->no_gc_in_progress(), "Allocation during gc not allowed"); | |
492 HeapWord* result = NULL; | |
493 | |
494 // Loop until the allocation is satisified, | |
495 // or unsatisfied after GC. | |
496 for (int try_count = 1; /* return or throw */; try_count += 1) { | |
497 HandleMark hm; // discard any handles allocated in each iteration | |
498 | |
499 // First allocation attempt is lock-free. | |
500 Generation *gen0 = gch->get_gen(0); | |
501 assert(gen0->supports_inline_contig_alloc(), | |
502 "Otherwise, must do alloc within heap lock"); | |
503 if (gen0->should_allocate(size, is_tlab)) { | |
504 result = gen0->par_allocate(size, is_tlab); | |
505 if (result != NULL) { | |
506 assert(gch->is_in_reserved(result), "result not in heap"); | |
507 return result; | |
508 } | |
509 } | |
510 unsigned int gc_count_before; // read inside the Heap_lock locked region | |
511 { | |
512 MutexLocker ml(Heap_lock); | |
513 if (PrintGC && Verbose) { | |
514 gclog_or_tty->print_cr("TwoGenerationCollectorPolicy::mem_allocate_work:" | |
515 " attempting locked slow path allocation"); | |
516 } | |
517 // Note that only large objects get a shot at being | |
518 // allocated in later generations. | |
519 bool first_only = ! should_try_older_generation_allocation(size); | |
520 | |
521 result = gch->attempt_allocation(size, is_tlab, first_only); | |
522 if (result != NULL) { | |
523 assert(gch->is_in_reserved(result), "result not in heap"); | |
524 return result; | |
525 } | |
526 | |
527 // There are NULL's returned for different circumstances below. | |
528 // In general gc_overhead_limit_was_exceeded should be false so | |
529 // set it so here and reset it to true only if the gc time | |
530 // limit is being exceeded as checked below. | |
531 *gc_overhead_limit_was_exceeded = false; | |
532 | |
533 if (GC_locker::is_active_and_needs_gc()) { | |
534 if (is_tlab) { | |
535 return NULL; // Caller will retry allocating individual object | |
536 } | |
537 if (!gch->is_maximal_no_gc()) { | |
538 // Try and expand heap to satisfy request | |
539 result = expand_heap_and_allocate(size, is_tlab); | |
540 // result could be null if we are out of space | |
541 if (result != NULL) { | |
542 return result; | |
543 } | |
544 } | |
545 | |
546 // If this thread is not in a jni critical section, we stall | |
547 // the requestor until the critical section has cleared and | |
548 // GC allowed. When the critical section clears, a GC is | |
549 // initiated by the last thread exiting the critical section; so | |
550 // we retry the allocation sequence from the beginning of the loop, | |
551 // rather than causing more, now probably unnecessary, GC attempts. | |
552 JavaThread* jthr = JavaThread::current(); | |
553 if (!jthr->in_critical()) { | |
554 MutexUnlocker mul(Heap_lock); | |
555 // Wait for JNI critical section to be exited | |
556 GC_locker::stall_until_clear(); | |
557 continue; | |
558 } else { | |
559 if (CheckJNICalls) { | |
560 fatal("Possible deadlock due to allocating while" | |
561 " in jni critical section"); | |
562 } | |
563 return NULL; | |
564 } | |
565 } | |
566 | |
567 // Read the gc count while the heap lock is held. | |
568 gc_count_before = Universe::heap()->total_collections(); | |
569 } | |
570 | |
571 // Allocation has failed and a collection is about | |
572 // to be done. If the gc time limit was exceeded the | |
573 // last time a collection was done, return NULL so | |
574 // that an out-of-memory will be thrown. Clear | |
575 // gc_time_limit_exceeded so that subsequent attempts | |
576 // at a collection will be made. | |
577 if (size_policy()->gc_time_limit_exceeded()) { | |
578 *gc_overhead_limit_was_exceeded = true; | |
579 size_policy()->set_gc_time_limit_exceeded(false); | |
580 return NULL; | |
581 } | |
582 | |
583 VM_GenCollectForAllocation op(size, | |
584 is_tlab, | |
585 gc_count_before); | |
586 VMThread::execute(&op); | |
587 if (op.prologue_succeeded()) { | |
588 result = op.result(); | |
589 if (op.gc_locked()) { | |
590 assert(result == NULL, "must be NULL if gc_locked() is true"); | |
591 continue; // retry and/or stall as necessary | |
592 } | |
593 assert(result == NULL || gch->is_in_reserved(result), | |
594 "result not in heap"); | |
595 return result; | |
596 } | |
597 | |
598 // Give a warning if we seem to be looping forever. | |
599 if ((QueuedAllocationWarningCount > 0) && | |
600 (try_count % QueuedAllocationWarningCount == 0)) { | |
601 warning("TwoGenerationCollectorPolicy::mem_allocate_work retries %d times \n\t" | |
602 " size=%d %s", try_count, size, is_tlab ? "(TLAB)" : ""); | |
603 } | |
604 } | |
605 } | |
606 | |
607 HeapWord* GenCollectorPolicy::expand_heap_and_allocate(size_t size, | |
608 bool is_tlab) { | |
609 GenCollectedHeap *gch = GenCollectedHeap::heap(); | |
610 HeapWord* result = NULL; | |
611 for (int i = number_of_generations() - 1; i >= 0 && result == NULL; i--) { | |
612 Generation *gen = gch->get_gen(i); | |
613 if (gen->should_allocate(size, is_tlab)) { | |
614 result = gen->expand_and_allocate(size, is_tlab); | |
615 } | |
616 } | |
617 assert(result == NULL || gch->is_in_reserved(result), "result not in heap"); | |
618 return result; | |
619 } | |
620 | |
621 HeapWord* GenCollectorPolicy::satisfy_failed_allocation(size_t size, | |
622 bool is_tlab) { | |
623 GenCollectedHeap *gch = GenCollectedHeap::heap(); | |
624 GCCauseSetter x(gch, GCCause::_allocation_failure); | |
625 HeapWord* result = NULL; | |
626 | |
627 assert(size != 0, "Precondition violated"); | |
628 if (GC_locker::is_active_and_needs_gc()) { | |
629 // GC locker is active; instead of a collection we will attempt | |
630 // to expand the heap, if there's room for expansion. | |
631 if (!gch->is_maximal_no_gc()) { | |
632 result = expand_heap_and_allocate(size, is_tlab); | |
633 } | |
634 return result; // could be null if we are out of space | |
635 } else if (!gch->incremental_collection_will_fail()) { | |
636 // The gc_prologues have not executed yet. The value | |
637 // for incremental_collection_will_fail() is the remanent | |
638 // of the last collection. | |
639 // Do an incremental collection. | |
640 gch->do_collection(false /* full */, | |
641 false /* clear_all_soft_refs */, | |
642 size /* size */, | |
643 is_tlab /* is_tlab */, | |
644 number_of_generations() - 1 /* max_level */); | |
645 } else { | |
646 // Try a full collection; see delta for bug id 6266275 | |
647 // for the original code and why this has been simplified | |
648 // with from-space allocation criteria modified and | |
649 // such allocation moved out of the safepoint path. | |
650 gch->do_collection(true /* full */, | |
651 false /* clear_all_soft_refs */, | |
652 size /* size */, | |
653 is_tlab /* is_tlab */, | |
654 number_of_generations() - 1 /* max_level */); | |
655 } | |
656 | |
657 result = gch->attempt_allocation(size, is_tlab, false /*first_only*/); | |
658 | |
659 if (result != NULL) { | |
660 assert(gch->is_in_reserved(result), "result not in heap"); | |
661 return result; | |
662 } | |
663 | |
664 // OK, collection failed, try expansion. | |
665 result = expand_heap_and_allocate(size, is_tlab); | |
666 if (result != NULL) { | |
667 return result; | |
668 } | |
669 | |
670 // If we reach this point, we're really out of memory. Try every trick | |
671 // we can to reclaim memory. Force collection of soft references. Force | |
672 // a complete compaction of the heap. Any additional methods for finding | |
673 // free memory should be here, especially if they are expensive. If this | |
674 // attempt fails, an OOM exception will be thrown. | |
675 { | |
676 IntFlagSetting flag_change(MarkSweepAlwaysCompactCount, 1); // Make sure the heap is fully compacted | |
677 | |
678 gch->do_collection(true /* full */, | |
679 true /* clear_all_soft_refs */, | |
680 size /* size */, | |
681 is_tlab /* is_tlab */, | |
682 number_of_generations() - 1 /* max_level */); | |
683 } | |
684 | |
685 result = gch->attempt_allocation(size, is_tlab, false /* first_only */); | |
686 if (result != NULL) { | |
687 assert(gch->is_in_reserved(result), "result not in heap"); | |
688 return result; | |
689 } | |
690 | |
691 // What else? We might try synchronous finalization later. If the total | |
692 // space available is large enough for the allocation, then a more | |
693 // complete compaction phase than we've tried so far might be | |
694 // appropriate. | |
695 return NULL; | |
696 } | |
697 | |
698 size_t GenCollectorPolicy::large_typearray_limit() { | |
699 return FastAllocateSizeLimit; | |
700 } | |
701 | |
702 // Return true if any of the following is true: | |
703 // . the allocation won't fit into the current young gen heap | |
704 // . gc locker is occupied (jni critical section) | |
705 // . heap memory is tight -- the most recent previous collection | |
706 // was a full collection because a partial collection (would | |
707 // have) failed and is likely to fail again | |
708 bool GenCollectorPolicy::should_try_older_generation_allocation( | |
709 size_t word_size) const { | |
710 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
711 size_t gen0_capacity = gch->get_gen(0)->capacity_before_gc(); | |
712 return (word_size > heap_word_size(gen0_capacity)) | |
713 || (GC_locker::is_active_and_needs_gc()) | |
714 || ( gch->last_incremental_collection_failed() | |
715 && gch->incremental_collection_will_fail()); | |
716 } | |
717 | |
718 | |
719 // | |
720 // MarkSweepPolicy methods | |
721 // | |
722 | |
723 MarkSweepPolicy::MarkSweepPolicy() { | |
724 initialize_all(); | |
725 } | |
726 | |
727 void MarkSweepPolicy::initialize_generations() { | |
728 initialize_perm_generation(PermGen::MarkSweepCompact); | |
729 _generations = new GenerationSpecPtr[number_of_generations()]; | |
730 if (_generations == NULL) | |
731 vm_exit_during_initialization("Unable to allocate gen spec"); | |
732 | |
733 if (UseParNewGC && ParallelGCThreads > 0) { | |
734 _generations[0] = new GenerationSpec(Generation::ParNew, _initial_gen0_size, _max_gen0_size); | |
735 } else { | |
736 _generations[0] = new GenerationSpec(Generation::DefNew, _initial_gen0_size, _max_gen0_size); | |
737 } | |
738 _generations[1] = new GenerationSpec(Generation::MarkSweepCompact, _initial_gen1_size, _max_gen1_size); | |
739 | |
740 if (_generations[0] == NULL || _generations[1] == NULL) | |
741 vm_exit_during_initialization("Unable to allocate gen spec"); | |
742 } | |
743 | |
744 void MarkSweepPolicy::initialize_gc_policy_counters() { | |
745 // initialize the policy counters - 2 collectors, 3 generations | |
746 if (UseParNewGC && ParallelGCThreads > 0) { | |
747 _gc_policy_counters = new GCPolicyCounters("ParNew:MSC", 2, 3); | |
748 } | |
749 else { | |
750 _gc_policy_counters = new GCPolicyCounters("Copy:MSC", 2, 3); | |
751 } | |
752 } |