Mercurial > hg > truffle
annotate src/share/vm/gc_implementation/parNew/parCardTableModRefBS.cpp @ 1995:8df09fb45352
7005259: CMS: BubbleUpRef asserts referent(obj)->is_oop() failed: Enqueued a bad referent
Summary: Relaxed the assert by allowing NULL referents when discovery may be concurrent.
Reviewed-by: johnc, jcoomes
author | ysr |
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date | Thu, 09 Dec 2010 09:22:57 -0800 |
parents | f95d63e2154a |
children | c69b1043dfb1 |
rev | line source |
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0 | 1 /* |
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2 * Copyright (c) 2007, 2010 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 #include "precompiled.hpp" |
26 #include "memory/allocation.inline.hpp" | |
27 #include "memory/cardTableModRefBS.hpp" | |
28 #include "memory/cardTableRS.hpp" | |
29 #include "memory/sharedHeap.hpp" | |
30 #include "memory/space.inline.hpp" | |
31 #include "memory/universe.hpp" | |
32 #include "runtime/java.hpp" | |
33 #include "runtime/mutexLocker.hpp" | |
34 #include "runtime/virtualspace.hpp" | |
0 | 35 |
36 void CardTableModRefBS::par_non_clean_card_iterate_work(Space* sp, MemRegion mr, | |
37 DirtyCardToOopClosure* dcto_cl, | |
38 MemRegionClosure* cl, | |
39 bool clear, | |
40 int n_threads) { | |
41 if (n_threads > 0) { | |
845 | 42 assert((n_threads == 1 && ParallelGCThreads == 0) || |
43 n_threads <= (int)ParallelGCThreads, | |
44 "# worker threads != # requested!"); | |
45 // Make sure the LNC array is valid for the space. | |
0 | 46 jbyte** lowest_non_clean; |
47 uintptr_t lowest_non_clean_base_chunk_index; | |
48 size_t lowest_non_clean_chunk_size; | |
49 get_LNC_array_for_space(sp, lowest_non_clean, | |
50 lowest_non_clean_base_chunk_index, | |
51 lowest_non_clean_chunk_size); | |
52 | |
53 int n_strides = n_threads * StridesPerThread; | |
54 SequentialSubTasksDone* pst = sp->par_seq_tasks(); | |
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55 pst->set_n_threads(n_threads); |
0 | 56 pst->set_n_tasks(n_strides); |
57 | |
58 int stride = 0; | |
59 while (!pst->is_task_claimed(/* reference */ stride)) { | |
60 process_stride(sp, mr, stride, n_strides, dcto_cl, cl, clear, | |
61 lowest_non_clean, | |
62 lowest_non_clean_base_chunk_index, | |
63 lowest_non_clean_chunk_size); | |
64 } | |
65 if (pst->all_tasks_completed()) { | |
66 // Clear lowest_non_clean array for next time. | |
67 intptr_t first_chunk_index = addr_to_chunk_index(mr.start()); | |
68 uintptr_t last_chunk_index = addr_to_chunk_index(mr.last()); | |
69 for (uintptr_t ch = first_chunk_index; ch <= last_chunk_index; ch++) { | |
70 intptr_t ind = ch - lowest_non_clean_base_chunk_index; | |
71 assert(0 <= ind && ind < (intptr_t)lowest_non_clean_chunk_size, | |
72 "Bounds error"); | |
73 lowest_non_clean[ind] = NULL; | |
74 } | |
75 } | |
76 } | |
77 } | |
78 | |
79 void | |
80 CardTableModRefBS:: | |
81 process_stride(Space* sp, | |
82 MemRegion used, | |
83 jint stride, int n_strides, | |
84 DirtyCardToOopClosure* dcto_cl, | |
85 MemRegionClosure* cl, | |
86 bool clear, | |
87 jbyte** lowest_non_clean, | |
88 uintptr_t lowest_non_clean_base_chunk_index, | |
89 size_t lowest_non_clean_chunk_size) { | |
90 // We don't have to go downwards here; it wouldn't help anyway, | |
91 // because of parallelism. | |
92 | |
93 // Find the first card address of the first chunk in the stride that is | |
94 // at least "bottom" of the used region. | |
95 jbyte* start_card = byte_for(used.start()); | |
96 jbyte* end_card = byte_after(used.last()); | |
97 uintptr_t start_chunk = addr_to_chunk_index(used.start()); | |
98 uintptr_t start_chunk_stride_num = start_chunk % n_strides; | |
99 jbyte* chunk_card_start; | |
100 | |
101 if ((uintptr_t)stride >= start_chunk_stride_num) { | |
102 chunk_card_start = (jbyte*)(start_card + | |
103 (stride - start_chunk_stride_num) * | |
104 CardsPerStrideChunk); | |
105 } else { | |
106 // Go ahead to the next chunk group boundary, then to the requested stride. | |
107 chunk_card_start = (jbyte*)(start_card + | |
108 (n_strides - start_chunk_stride_num + stride) * | |
109 CardsPerStrideChunk); | |
110 } | |
111 | |
112 while (chunk_card_start < end_card) { | |
113 // We don't have to go downwards here; it wouldn't help anyway, | |
114 // because of parallelism. (We take care with "min_done"; see below.) | |
115 // Invariant: chunk_mr should be fully contained within the "used" region. | |
116 jbyte* chunk_card_end = chunk_card_start + CardsPerStrideChunk; | |
117 MemRegion chunk_mr = MemRegion(addr_for(chunk_card_start), | |
118 chunk_card_end >= end_card ? | |
119 used.end() : addr_for(chunk_card_end)); | |
120 assert(chunk_mr.word_size() > 0, "[chunk_card_start > used_end)"); | |
121 assert(used.contains(chunk_mr), "chunk_mr should be subset of used"); | |
122 | |
123 // Process the chunk. | |
124 process_chunk_boundaries(sp, | |
125 dcto_cl, | |
126 chunk_mr, | |
127 used, | |
128 lowest_non_clean, | |
129 lowest_non_clean_base_chunk_index, | |
130 lowest_non_clean_chunk_size); | |
131 | |
132 non_clean_card_iterate_work(chunk_mr, cl, clear); | |
133 | |
134 // Find the next chunk of the stride. | |
135 chunk_card_start += CardsPerStrideChunk * n_strides; | |
136 } | |
137 } | |
138 | |
139 void | |
140 CardTableModRefBS:: | |
141 process_chunk_boundaries(Space* sp, | |
142 DirtyCardToOopClosure* dcto_cl, | |
143 MemRegion chunk_mr, | |
144 MemRegion used, | |
145 jbyte** lowest_non_clean, | |
146 uintptr_t lowest_non_clean_base_chunk_index, | |
147 size_t lowest_non_clean_chunk_size) | |
148 { | |
149 // We must worry about the chunk boundaries. | |
150 | |
151 // First, set our max_to_do: | |
152 HeapWord* max_to_do = NULL; | |
153 uintptr_t cur_chunk_index = addr_to_chunk_index(chunk_mr.start()); | |
154 cur_chunk_index = cur_chunk_index - lowest_non_clean_base_chunk_index; | |
155 | |
156 if (chunk_mr.end() < used.end()) { | |
157 // This is not the last chunk in the used region. What is the last | |
158 // object? | |
159 HeapWord* last_block = sp->block_start(chunk_mr.end()); | |
160 assert(last_block <= chunk_mr.end(), "In case this property changes."); | |
161 if (last_block == chunk_mr.end() | |
162 || !sp->block_is_obj(last_block)) { | |
163 max_to_do = chunk_mr.end(); | |
164 | |
165 } else { | |
166 // It is an object and starts before the end of the current chunk. | |
167 // last_obj_card is the card corresponding to the start of the last object | |
168 // in the chunk. Note that the last object may not start in | |
169 // the chunk. | |
170 jbyte* last_obj_card = byte_for(last_block); | |
171 if (!card_may_have_been_dirty(*last_obj_card)) { | |
172 // The card containing the head is not dirty. Any marks in | |
173 // subsequent cards still in this chunk must have been made | |
174 // precisely; we can cap processing at the end. | |
175 max_to_do = chunk_mr.end(); | |
176 } else { | |
177 // The last object must be considered dirty, and extends onto the | |
178 // following chunk. Look for a dirty card in that chunk that will | |
179 // bound our processing. | |
180 jbyte* limit_card = NULL; | |
181 size_t last_block_size = sp->block_size(last_block); | |
182 jbyte* last_card_of_last_obj = | |
183 byte_for(last_block + last_block_size - 1); | |
184 jbyte* first_card_of_next_chunk = byte_for(chunk_mr.end()); | |
185 // This search potentially goes a long distance looking | |
186 // for the next card that will be scanned. For example, | |
187 // an object that is an array of primitives will not | |
188 // have any cards covering regions interior to the array | |
189 // that will need to be scanned. The scan can be terminated | |
190 // at the last card of the next chunk. That would leave | |
191 // limit_card as NULL and would result in "max_to_do" | |
192 // being set with the LNC value or with the end | |
193 // of the last block. | |
194 jbyte* last_card_of_next_chunk = first_card_of_next_chunk + | |
195 CardsPerStrideChunk; | |
196 assert(byte_for(chunk_mr.end()) - byte_for(chunk_mr.start()) | |
197 == CardsPerStrideChunk, "last card of next chunk may be wrong"); | |
198 jbyte* last_card_to_check = (jbyte*) MIN2(last_card_of_last_obj, | |
199 last_card_of_next_chunk); | |
200 for (jbyte* cur = first_card_of_next_chunk; | |
201 cur <= last_card_to_check; cur++) { | |
202 if (card_will_be_scanned(*cur)) { | |
203 limit_card = cur; break; | |
204 } | |
205 } | |
206 assert(0 <= cur_chunk_index+1 && | |
207 cur_chunk_index+1 < lowest_non_clean_chunk_size, | |
208 "Bounds error."); | |
209 // LNC for the next chunk | |
210 jbyte* lnc_card = lowest_non_clean[cur_chunk_index+1]; | |
211 if (limit_card == NULL) { | |
212 limit_card = lnc_card; | |
213 } | |
214 if (limit_card != NULL) { | |
215 if (lnc_card != NULL) { | |
216 limit_card = (jbyte*)MIN2((intptr_t)limit_card, | |
217 (intptr_t)lnc_card); | |
218 } | |
219 max_to_do = addr_for(limit_card); | |
220 } else { | |
221 max_to_do = last_block + last_block_size; | |
222 } | |
223 } | |
224 } | |
225 assert(max_to_do != NULL, "OOPS!"); | |
226 } else { | |
227 max_to_do = used.end(); | |
228 } | |
229 // Now we can set the closure we're using so it doesn't to beyond | |
230 // max_to_do. | |
231 dcto_cl->set_min_done(max_to_do); | |
232 #ifndef PRODUCT | |
233 dcto_cl->set_last_bottom(max_to_do); | |
234 #endif | |
235 | |
236 // Now we set *our" lowest_non_clean entry. | |
237 // Find the object that spans our boundary, if one exists. | |
238 // Nothing to do on the first chunk. | |
239 if (chunk_mr.start() > used.start()) { | |
240 // first_block is the block possibly spanning the chunk start | |
241 HeapWord* first_block = sp->block_start(chunk_mr.start()); | |
242 // Does the block span the start of the chunk and is it | |
243 // an object? | |
244 if (first_block < chunk_mr.start() && | |
245 sp->block_is_obj(first_block)) { | |
246 jbyte* first_dirty_card = NULL; | |
247 jbyte* last_card_of_first_obj = | |
248 byte_for(first_block + sp->block_size(first_block) - 1); | |
249 jbyte* first_card_of_cur_chunk = byte_for(chunk_mr.start()); | |
250 jbyte* last_card_of_cur_chunk = byte_for(chunk_mr.last()); | |
251 jbyte* last_card_to_check = | |
252 (jbyte*) MIN2((intptr_t) last_card_of_cur_chunk, | |
253 (intptr_t) last_card_of_first_obj); | |
254 for (jbyte* cur = first_card_of_cur_chunk; | |
255 cur <= last_card_to_check; cur++) { | |
256 if (card_will_be_scanned(*cur)) { | |
257 first_dirty_card = cur; break; | |
258 } | |
259 } | |
260 if (first_dirty_card != NULL) { | |
261 assert(0 <= cur_chunk_index && | |
262 cur_chunk_index < lowest_non_clean_chunk_size, | |
263 "Bounds error."); | |
264 lowest_non_clean[cur_chunk_index] = first_dirty_card; | |
265 } | |
266 } | |
267 } | |
268 } | |
269 | |
270 void | |
271 CardTableModRefBS:: | |
272 get_LNC_array_for_space(Space* sp, | |
273 jbyte**& lowest_non_clean, | |
274 uintptr_t& lowest_non_clean_base_chunk_index, | |
275 size_t& lowest_non_clean_chunk_size) { | |
276 | |
277 int i = find_covering_region_containing(sp->bottom()); | |
278 MemRegion covered = _covered[i]; | |
279 size_t n_chunks = chunks_to_cover(covered); | |
280 | |
281 // Only the first thread to obtain the lock will resize the | |
282 // LNC array for the covered region. Any later expansion can't affect | |
283 // the used_at_save_marks region. | |
284 // (I observed a bug in which the first thread to execute this would | |
285 // resize, and then it would cause "expand_and_allocates" that would | |
286 // Increase the number of chunks in the covered region. Then a second | |
287 // thread would come and execute this, see that the size didn't match, | |
288 // and free and allocate again. So the first thread would be using a | |
289 // freed "_lowest_non_clean" array.) | |
290 | |
291 // Do a dirty read here. If we pass the conditional then take the rare | |
292 // event lock and do the read again in case some other thread had already | |
293 // succeeded and done the resize. | |
294 int cur_collection = Universe::heap()->total_collections(); | |
295 if (_last_LNC_resizing_collection[i] != cur_collection) { | |
296 MutexLocker x(ParGCRareEvent_lock); | |
297 if (_last_LNC_resizing_collection[i] != cur_collection) { | |
298 if (_lowest_non_clean[i] == NULL || | |
299 n_chunks != _lowest_non_clean_chunk_size[i]) { | |
300 | |
301 // Should we delete the old? | |
302 if (_lowest_non_clean[i] != NULL) { | |
303 assert(n_chunks != _lowest_non_clean_chunk_size[i], | |
304 "logical consequence"); | |
305 FREE_C_HEAP_ARRAY(CardPtr, _lowest_non_clean[i]); | |
306 _lowest_non_clean[i] = NULL; | |
307 } | |
308 // Now allocate a new one if necessary. | |
309 if (_lowest_non_clean[i] == NULL) { | |
310 _lowest_non_clean[i] = NEW_C_HEAP_ARRAY(CardPtr, n_chunks); | |
311 _lowest_non_clean_chunk_size[i] = n_chunks; | |
312 _lowest_non_clean_base_chunk_index[i] = addr_to_chunk_index(covered.start()); | |
313 for (int j = 0; j < (int)n_chunks; j++) | |
314 _lowest_non_clean[i][j] = NULL; | |
315 } | |
316 } | |
317 _last_LNC_resizing_collection[i] = cur_collection; | |
318 } | |
319 } | |
320 // In any case, now do the initialization. | |
321 lowest_non_clean = _lowest_non_clean[i]; | |
322 lowest_non_clean_base_chunk_index = _lowest_non_clean_base_chunk_index[i]; | |
323 lowest_non_clean_chunk_size = _lowest_non_clean_chunk_size[i]; | |
324 } |