Tue, 19 May 2015 15:49:27 +0200
8061715: gc/g1/TestShrinkAuxiliaryData15.java fails with java.lang.RuntimeException: heap decommit failed - after > before
Summary: added WhiteBox methods to count regions and exact aux data sizes
Reviewed-by: jwilhelm, brutisso
1 /*
2 * Copyright (c) 2011, 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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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).
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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,
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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23 */
25 #include "precompiled.hpp"
26 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
27 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
28 #include "runtime/orderAccess.inline.hpp"
30 G1CollectedHeap* G1AllocRegion::_g1h = NULL;
31 HeapRegion* G1AllocRegion::_dummy_region = NULL;
33 void G1AllocRegion::setup(G1CollectedHeap* g1h, HeapRegion* dummy_region) {
34 assert(_dummy_region == NULL, "should be set once");
35 assert(dummy_region != NULL, "pre-condition");
36 assert(dummy_region->free() == 0, "pre-condition");
38 // Make sure that any allocation attempt on this region will fail
39 // and will not trigger any asserts.
40 assert(allocate(dummy_region, 1, false) == NULL, "should fail");
41 assert(par_allocate(dummy_region, 1, false) == NULL, "should fail");
42 assert(allocate(dummy_region, 1, true) == NULL, "should fail");
43 assert(par_allocate(dummy_region, 1, true) == NULL, "should fail");
45 _g1h = g1h;
46 _dummy_region = dummy_region;
47 }
49 void G1AllocRegion::fill_up_remaining_space(HeapRegion* alloc_region,
50 bool bot_updates) {
51 assert(alloc_region != NULL && alloc_region != _dummy_region,
52 "pre-condition");
54 // Other threads might still be trying to allocate using a CAS out
55 // of the region we are trying to retire, as they can do so without
56 // holding the lock. So, we first have to make sure that noone else
57 // can allocate out of it by doing a maximal allocation. Even if our
58 // CAS attempt fails a few times, we'll succeed sooner or later
59 // given that failed CAS attempts mean that the region is getting
60 // closed to being full.
61 size_t free_word_size = alloc_region->free() / HeapWordSize;
63 // This is the minimum free chunk we can turn into a dummy
64 // object. If the free space falls below this, then noone can
65 // allocate in this region anyway (all allocation requests will be
66 // of a size larger than this) so we won't have to perform the dummy
67 // allocation.
68 size_t min_word_size_to_fill = CollectedHeap::min_fill_size();
70 while (free_word_size >= min_word_size_to_fill) {
71 HeapWord* dummy = par_allocate(alloc_region, free_word_size, bot_updates);
72 if (dummy != NULL) {
73 // If the allocation was successful we should fill in the space.
74 CollectedHeap::fill_with_object(dummy, free_word_size);
75 alloc_region->set_pre_dummy_top(dummy);
76 break;
77 }
79 free_word_size = alloc_region->free() / HeapWordSize;
80 // It's also possible that someone else beats us to the
81 // allocation and they fill up the region. In that case, we can
82 // just get out of the loop.
83 }
84 assert(alloc_region->free() / HeapWordSize < min_word_size_to_fill,
85 "post-condition");
86 }
88 void G1AllocRegion::retire(bool fill_up) {
89 assert(_alloc_region != NULL, ar_ext_msg(this, "not initialized properly"));
91 trace("retiring");
92 HeapRegion* alloc_region = _alloc_region;
93 if (alloc_region != _dummy_region) {
94 // We never have to check whether the active region is empty or not,
95 // and potentially free it if it is, given that it's guaranteed that
96 // it will never be empty.
97 assert(!alloc_region->is_empty(),
98 ar_ext_msg(this, "the alloc region should never be empty"));
100 if (fill_up) {
101 fill_up_remaining_space(alloc_region, _bot_updates);
102 }
104 assert(alloc_region->used() >= _used_bytes_before,
105 ar_ext_msg(this, "invariant"));
106 size_t allocated_bytes = alloc_region->used() - _used_bytes_before;
107 retire_region(alloc_region, allocated_bytes);
108 _used_bytes_before = 0;
109 _alloc_region = _dummy_region;
110 }
111 trace("retired");
112 }
114 HeapWord* G1AllocRegion::new_alloc_region_and_allocate(size_t word_size,
115 bool force) {
116 assert(_alloc_region == _dummy_region, ar_ext_msg(this, "pre-condition"));
117 assert(_used_bytes_before == 0, ar_ext_msg(this, "pre-condition"));
119 trace("attempting region allocation");
120 HeapRegion* new_alloc_region = allocate_new_region(word_size, force);
121 if (new_alloc_region != NULL) {
122 new_alloc_region->reset_pre_dummy_top();
123 // Need to do this before the allocation
124 _used_bytes_before = new_alloc_region->used();
125 HeapWord* result = allocate(new_alloc_region, word_size, _bot_updates);
126 assert(result != NULL, ar_ext_msg(this, "the allocation should succeeded"));
128 OrderAccess::storestore();
129 // Note that we first perform the allocation and then we store the
130 // region in _alloc_region. This is the reason why an active region
131 // can never be empty.
132 update_alloc_region(new_alloc_region);
133 trace("region allocation successful");
134 return result;
135 } else {
136 trace("region allocation failed");
137 return NULL;
138 }
139 ShouldNotReachHere();
140 }
142 void G1AllocRegion::fill_in_ext_msg(ar_ext_msg* msg, const char* message) {
143 msg->append("[%s] %s c: %u b: %s r: "PTR_FORMAT" u: "SIZE_FORMAT,
144 _name, message, _count, BOOL_TO_STR(_bot_updates),
145 p2i(_alloc_region), _used_bytes_before);
146 }
148 void G1AllocRegion::init() {
149 trace("initializing");
150 assert(_alloc_region == NULL && _used_bytes_before == 0,
151 ar_ext_msg(this, "pre-condition"));
152 assert(_dummy_region != NULL, ar_ext_msg(this, "should have been set"));
153 _alloc_region = _dummy_region;
154 _count = 0;
155 trace("initialized");
156 }
158 void G1AllocRegion::set(HeapRegion* alloc_region) {
159 trace("setting");
160 // We explicitly check that the region is not empty to make sure we
161 // maintain the "the alloc region cannot be empty" invariant.
162 assert(alloc_region != NULL && !alloc_region->is_empty(),
163 ar_ext_msg(this, "pre-condition"));
164 assert(_alloc_region == _dummy_region &&
165 _used_bytes_before == 0 && _count == 0,
166 ar_ext_msg(this, "pre-condition"));
168 _used_bytes_before = alloc_region->used();
169 _alloc_region = alloc_region;
170 _count += 1;
171 trace("set");
172 }
174 void G1AllocRegion::update_alloc_region(HeapRegion* alloc_region) {
175 trace("update");
176 // We explicitly check that the region is not empty to make sure we
177 // maintain the "the alloc region cannot be empty" invariant.
178 assert(alloc_region != NULL && !alloc_region->is_empty(),
179 ar_ext_msg(this, "pre-condition"));
181 _alloc_region = alloc_region;
182 _alloc_region->set_allocation_context(allocation_context());
183 _count += 1;
184 trace("updated");
185 }
187 HeapRegion* G1AllocRegion::release() {
188 trace("releasing");
189 HeapRegion* alloc_region = _alloc_region;
190 retire(false /* fill_up */);
191 assert(_alloc_region == _dummy_region,
192 ar_ext_msg(this, "post-condition of retire()"));
193 _alloc_region = NULL;
194 trace("released");
195 return (alloc_region == _dummy_region) ? NULL : alloc_region;
196 }
198 #if G1_ALLOC_REGION_TRACING
199 void G1AllocRegion::trace(const char* str, size_t word_size, HeapWord* result) {
200 // All the calls to trace that set either just the size or the size
201 // and the result are considered part of level 2 tracing and are
202 // skipped during level 1 tracing.
203 if ((word_size == 0 && result == NULL) || (G1_ALLOC_REGION_TRACING > 1)) {
204 const size_t buffer_length = 128;
205 char hr_buffer[buffer_length];
206 char rest_buffer[buffer_length];
208 HeapRegion* alloc_region = _alloc_region;
209 if (alloc_region == NULL) {
210 jio_snprintf(hr_buffer, buffer_length, "NULL");
211 } else if (alloc_region == _dummy_region) {
212 jio_snprintf(hr_buffer, buffer_length, "DUMMY");
213 } else {
214 jio_snprintf(hr_buffer, buffer_length,
215 HR_FORMAT, HR_FORMAT_PARAMS(alloc_region));
216 }
218 if (G1_ALLOC_REGION_TRACING > 1) {
219 if (result != NULL) {
220 jio_snprintf(rest_buffer, buffer_length, SIZE_FORMAT" "PTR_FORMAT,
221 word_size, result);
222 } else if (word_size != 0) {
223 jio_snprintf(rest_buffer, buffer_length, SIZE_FORMAT, word_size);
224 } else {
225 jio_snprintf(rest_buffer, buffer_length, "");
226 }
227 } else {
228 jio_snprintf(rest_buffer, buffer_length, "");
229 }
231 tty->print_cr("[%s] %u %s : %s %s",
232 _name, _count, hr_buffer, str, rest_buffer);
233 }
234 }
235 #endif // G1_ALLOC_REGION_TRACING
237 G1AllocRegion::G1AllocRegion(const char* name,
238 bool bot_updates)
239 : _name(name), _bot_updates(bot_updates),
240 _alloc_region(NULL), _count(0), _used_bytes_before(0),
241 _allocation_context(AllocationContext::system()) { }
244 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
245 bool force) {
246 return _g1h->new_mutator_alloc_region(word_size, force);
247 }
249 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
250 size_t allocated_bytes) {
251 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
252 }
254 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
255 bool force) {
256 assert(!force, "not supported for GC alloc regions");
257 return _g1h->new_gc_alloc_region(word_size, count(), InCSetState::Young);
258 }
260 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
261 size_t allocated_bytes) {
262 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes, InCSetState::Young);
263 }
265 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
266 bool force) {
267 assert(!force, "not supported for GC alloc regions");
268 return _g1h->new_gc_alloc_region(word_size, count(), InCSetState::Old);
269 }
271 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
272 size_t allocated_bytes) {
273 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes, InCSetState::Old);
274 }
276 HeapRegion* OldGCAllocRegion::release() {
277 HeapRegion* cur = get();
278 if (cur != NULL) {
279 // Determine how far we are from the next card boundary. If it is smaller than
280 // the minimum object size we can allocate into, expand into the next card.
281 HeapWord* top = cur->top();
282 HeapWord* aligned_top = (HeapWord*)align_ptr_up(top, G1BlockOffsetSharedArray::N_bytes);
284 size_t to_allocate_words = pointer_delta(aligned_top, top, HeapWordSize);
286 if (to_allocate_words != 0) {
287 // We are not at a card boundary. Fill up, possibly into the next, taking the
288 // end of the region and the minimum object size into account.
289 to_allocate_words = MIN2(pointer_delta(cur->end(), cur->top(), HeapWordSize),
290 MAX2(to_allocate_words, G1CollectedHeap::min_fill_size()));
292 // Skip allocation if there is not enough space to allocate even the smallest
293 // possible object. In this case this region will not be retained, so the
294 // original problem cannot occur.
295 if (to_allocate_words >= G1CollectedHeap::min_fill_size()) {
296 HeapWord* dummy = attempt_allocation(to_allocate_words, true /* bot_updates */);
297 CollectedHeap::fill_with_object(dummy, to_allocate_words);
298 }
299 }
300 }
301 return G1AllocRegion::release();
302 }