1 /*
2 * Copyright (c) 2015, 2020, Red Hat, Inc. All rights reserved.
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.
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
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23 */
24
25 #ifndef SHARE_GC_SHENANDOAH_SHENANDOAHHEAP_INLINE_HPP
26 #define SHARE_GC_SHENANDOAH_SHENANDOAHHEAP_INLINE_HPP
27
28 #include "gc/shenandoah/shenandoahHeap.hpp"
29
30 #include "classfile/javaClasses.inline.hpp"
31 #include "gc/shared/markBitMap.inline.hpp"
32 #include "gc/shared/threadLocalAllocBuffer.inline.hpp"
33 #include "gc/shared/continuationGCSupport.inline.hpp"
34 #include "gc/shared/suspendibleThreadSet.hpp"
35 #include "gc/shared/tlab_globals.hpp"
36 #include "gc/shenandoah/shenandoahAsserts.hpp"
37 #include "gc/shenandoah/shenandoahBarrierSet.inline.hpp"
38 #include "gc/shenandoah/shenandoahCollectionSet.inline.hpp"
39 #include "gc/shenandoah/shenandoahForwarding.inline.hpp"
40 #include "gc/shenandoah/shenandoahWorkGroup.hpp"
41 #include "gc/shenandoah/shenandoahHeapRegionSet.inline.hpp"
42 #include "gc/shenandoah/shenandoahHeapRegion.inline.hpp"
43 #include "gc/shenandoah/shenandoahControlThread.hpp"
44 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
45 #include "gc/shenandoah/shenandoahScanRemembered.inline.hpp"
46 #include "gc/shenandoah/shenandoahThreadLocalData.hpp"
47 #include "gc/shenandoah/shenandoahScanRemembered.inline.hpp"
48 #include "gc/shenandoah/mode/shenandoahMode.hpp"
49 #include "oops/compressedOops.inline.hpp"
50 #include "oops/oop.inline.hpp"
51 #include "runtime/atomic.hpp"
52 #include "runtime/javaThread.hpp"
53 #include "runtime/prefetch.inline.hpp"
54 #include "utilities/copy.hpp"
55 #include "utilities/globalDefinitions.hpp"
56
57 inline ShenandoahHeap* ShenandoahHeap::heap() {
58 return named_heap<ShenandoahHeap>(CollectedHeap::Shenandoah);
59 }
60
61 inline ShenandoahHeapRegion* ShenandoahRegionIterator::next() {
62 size_t new_index = Atomic::add(&_index, (size_t) 1, memory_order_relaxed);
63 // get_region() provides the bounds-check and returns NULL on OOB.
64 return _heap->get_region(new_index - 1);
65 }
66
67 inline bool ShenandoahHeap::has_forwarded_objects() const {
68 return _gc_state.is_set(HAS_FORWARDED);
69 }
70
71 inline WorkerThreads* ShenandoahHeap::workers() const {
72 return _workers;
73 }
74
75 inline WorkerThreads* ShenandoahHeap::safepoint_workers() {
76 return _safepoint_workers;
77 }
78
79 inline size_t ShenandoahHeap::heap_region_index_containing(const void* addr) const {
80 uintptr_t region_start = ((uintptr_t) addr);
81 uintptr_t index = (region_start - (uintptr_t) base()) >> ShenandoahHeapRegion::region_size_bytes_shift();
82 assert(index < num_regions(), "Region index is in bounds: " PTR_FORMAT, p2i(addr));
83 return index;
84 }
85
86 inline ShenandoahHeapRegion* const ShenandoahHeap::heap_region_containing(const void* addr) const {
87 size_t index = heap_region_index_containing(addr);
88 ShenandoahHeapRegion* const result = get_region(index);
89 assert(addr >= result->bottom() && addr < result->end(), "Heap region contains the address: " PTR_FORMAT, p2i(addr));
90 return result;
91 }
92
93 inline void ShenandoahHeap::enter_evacuation(Thread* t) {
94 _oom_evac_handler.enter_evacuation(t);
95 }
96
97 inline void ShenandoahHeap::leave_evacuation(Thread* t) {
98 _oom_evac_handler.leave_evacuation(t);
99 }
100
101 template <class T>
102 inline void ShenandoahHeap::update_with_forwarded(T* p) {
103 T o = RawAccess<>::oop_load(p);
104 if (!CompressedOops::is_null(o)) {
105 oop obj = CompressedOops::decode_not_null(o);
106 if (in_collection_set(obj)) {
107 // Corner case: when evacuation fails, there are objects in collection
108 // set that are not really forwarded. We can still go and try and update them
109 // (uselessly) to simplify the common path.
110 shenandoah_assert_forwarded_except(p, obj, cancelled_gc());
111 oop fwd = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
112 shenandoah_assert_not_in_cset_except(p, fwd, cancelled_gc());
113
114 // Unconditionally store the update: no concurrent updates expected.
115 RawAccess<IS_NOT_NULL>::oop_store(p, fwd);
116 }
117 }
118 }
119
120 template <class T>
121 inline void ShenandoahHeap::conc_update_with_forwarded(T* p) {
122 T o = RawAccess<>::oop_load(p);
123 if (!CompressedOops::is_null(o)) {
124 oop obj = CompressedOops::decode_not_null(o);
125 if (in_collection_set(obj)) {
126 // Corner case: when evacuation fails, there are objects in collection
127 // set that are not really forwarded. We can still go and try CAS-update them
128 // (uselessly) to simplify the common path.
129 shenandoah_assert_forwarded_except(p, obj, cancelled_gc());
130 oop fwd = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
131 shenandoah_assert_not_in_cset_except(p, fwd, cancelled_gc());
132
133 // Sanity check: we should not be updating the cset regions themselves,
134 // unless we are recovering from the evacuation failure.
135 shenandoah_assert_not_in_cset_loc_except(p, !is_in(p) || cancelled_gc());
136
137 // Either we succeed in updating the reference, or something else gets in our way.
138 // We don't care if that is another concurrent GC update, or another mutator update.
139 atomic_update_oop(fwd, p, obj);
140 }
141 }
142 }
143
144 // Atomic updates of heap location. This is only expected to work with updating the same
145 // logical object with its forwardee. The reason why we need stronger-than-relaxed memory
146 // ordering has to do with coordination with GC barriers and mutator accesses.
147 //
148 // In essence, stronger CAS access is required to maintain the transitive chains that mutator
149 // accesses build by themselves. To illustrate this point, consider the following example.
150 //
151 // Suppose "o" is the object that has a field "x" and the reference to "o" is stored
152 // to field at "addr", which happens to be Java volatile field. Normally, the accesses to volatile
153 // field at "addr" would be matched with release/acquire barriers. This changes when GC moves
154 // the object under mutator feet.
155 //
156 // Thread 1 (Java)
157 // // --- previous access starts here
158 // ...
159 // T1.1: store(&o.x, 1, mo_relaxed)
160 // T1.2: store(&addr, o, mo_release) // volatile store
161 //
162 // // --- new access starts here
163 // // LRB: copy and install the new copy to fwdptr
164 // T1.3: var copy = copy(o)
165 // T1.4: cas(&fwd, t, copy, mo_release) // pointer-mediated publication
166 // <access continues>
167 //
168 // Thread 2 (GC updater)
169 // T2.1: var f = load(&fwd, mo_{consume|acquire}) // pointer-mediated acquisition
170 // T2.2: cas(&addr, o, f, mo_release) // this method
171 //
172 // Thread 3 (Java)
173 // T3.1: var o = load(&addr, mo_acquire) // volatile read
174 // T3.2: if (o != null)
175 // T3.3: var r = load(&o.x, mo_relaxed)
176 //
177 // r is guaranteed to contain "1".
178 //
179 // Without GC involvement, there is synchronizes-with edge from T1.2 to T3.1,
180 // which guarantees this. With GC involvement, when LRB copies the object and
181 // another thread updates the reference to it, we need to have the transitive edge
182 // from T1.4 to T2.1 (that one is guaranteed by forwarding accesses), plus the edge
183 // from T2.2 to T3.1 (which is brought by this CAS).
184 //
185 // Note that we do not need to "acquire" in these methods, because we do not read the
186 // failure witnesses contents on any path, and "release" is enough.
187 //
188
189 inline void ShenandoahHeap::atomic_update_oop(oop update, oop* addr, oop compare) {
190 assert(is_aligned(addr, HeapWordSize), "Address should be aligned: " PTR_FORMAT, p2i(addr));
191 Atomic::cmpxchg(addr, compare, update, memory_order_release);
192 }
193
194 inline void ShenandoahHeap::atomic_update_oop(oop update, narrowOop* addr, narrowOop compare) {
195 assert(is_aligned(addr, sizeof(narrowOop)), "Address should be aligned: " PTR_FORMAT, p2i(addr));
196 narrowOop u = CompressedOops::encode(update);
197 Atomic::cmpxchg(addr, compare, u, memory_order_release);
198 }
199
200 inline void ShenandoahHeap::atomic_update_oop(oop update, narrowOop* addr, oop compare) {
201 assert(is_aligned(addr, sizeof(narrowOop)), "Address should be aligned: " PTR_FORMAT, p2i(addr));
202 narrowOop c = CompressedOops::encode(compare);
203 narrowOop u = CompressedOops::encode(update);
204 Atomic::cmpxchg(addr, c, u, memory_order_release);
205 }
206
207 inline bool ShenandoahHeap::atomic_update_oop_check(oop update, oop* addr, oop compare) {
208 assert(is_aligned(addr, HeapWordSize), "Address should be aligned: " PTR_FORMAT, p2i(addr));
209 return (oop) Atomic::cmpxchg(addr, compare, update, memory_order_release) == compare;
210 }
211
212 inline bool ShenandoahHeap::atomic_update_oop_check(oop update, narrowOop* addr, narrowOop compare) {
213 assert(is_aligned(addr, sizeof(narrowOop)), "Address should be aligned: " PTR_FORMAT, p2i(addr));
214 narrowOop u = CompressedOops::encode(update);
215 return (narrowOop) Atomic::cmpxchg(addr, compare, u, memory_order_release) == compare;
216 }
217
218 inline bool ShenandoahHeap::atomic_update_oop_check(oop update, narrowOop* addr, oop compare) {
219 assert(is_aligned(addr, sizeof(narrowOop)), "Address should be aligned: " PTR_FORMAT, p2i(addr));
220 narrowOop c = CompressedOops::encode(compare);
221 narrowOop u = CompressedOops::encode(update);
222 return CompressedOops::decode(Atomic::cmpxchg(addr, c, u, memory_order_release)) == compare;
223 }
224
225 // The memory ordering discussion above does not apply for methods that store NULLs:
226 // then, there is no transitive reads in mutator (as we see NULLs), and we can do
227 // relaxed memory ordering there.
228
229 inline void ShenandoahHeap::atomic_clear_oop(oop* addr, oop compare) {
230 assert(is_aligned(addr, HeapWordSize), "Address should be aligned: " PTR_FORMAT, p2i(addr));
231 Atomic::cmpxchg(addr, compare, oop(), memory_order_relaxed);
232 }
233
234 inline void ShenandoahHeap::atomic_clear_oop(narrowOop* addr, oop compare) {
235 assert(is_aligned(addr, sizeof(narrowOop)), "Address should be aligned: " PTR_FORMAT, p2i(addr));
236 narrowOop cmp = CompressedOops::encode(compare);
237 Atomic::cmpxchg(addr, cmp, narrowOop(), memory_order_relaxed);
238 }
239
240 inline void ShenandoahHeap::atomic_clear_oop(narrowOop* addr, narrowOop compare) {
241 assert(is_aligned(addr, sizeof(narrowOop)), "Address should be aligned: " PTR_FORMAT, p2i(addr));
242 Atomic::cmpxchg(addr, compare, narrowOop(), memory_order_relaxed);
243 }
244
245 inline bool ShenandoahHeap::cancelled_gc() const {
246 return _cancelled_gc.get() == CANCELLED;
247 }
248
249 inline bool ShenandoahHeap::check_cancelled_gc_and_yield(bool sts_active) {
250 if (! (sts_active && ShenandoahSuspendibleWorkers)) {
251 return cancelled_gc();
252 }
253
254 jbyte prev = _cancelled_gc.cmpxchg(NOT_CANCELLED, CANCELLABLE);
255 if (prev == CANCELLABLE || prev == NOT_CANCELLED) {
256 if (SuspendibleThreadSet::should_yield()) {
257 SuspendibleThreadSet::yield();
258 }
259
260 // Back to CANCELLABLE. The thread that poked NOT_CANCELLED first gets
261 // to restore to CANCELLABLE.
262 if (prev == CANCELLABLE) {
263 _cancelled_gc.set(CANCELLABLE);
264 }
265 return false;
266 } else {
267 return true;
268 }
269 }
270
271 inline void ShenandoahHeap::clear_cancelled_gc(bool clear_oom_handler) {
272 _cancelled_gc.set(CANCELLABLE);
273 if (_cancel_requested_time > 0) {
274 double cancel_time = os::elapsedTime() - _cancel_requested_time;
275 log_info(gc)("GC cancellation took %.3fs", cancel_time);
276 _cancel_requested_time = 0;
277 }
278
279 if (clear_oom_handler) {
280 _oom_evac_handler.clear();
281 }
282 }
283
284 inline HeapWord* ShenandoahHeap::allocate_from_gclab(Thread* thread, size_t size) {
285 assert(UseTLAB, "TLABs should be enabled");
286
287 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
288 if (gclab == NULL) {
289 assert(!thread->is_Java_thread() && !thread->is_Worker_thread(),
290 "Performance: thread should have GCLAB: %s", thread->name());
291 // No GCLABs in this thread, fallback to shared allocation
292 return NULL;
293 }
294 HeapWord* obj = gclab->allocate(size);
295 if (obj != NULL) {
296 return obj;
297 }
298 return allocate_from_gclab_slow(thread, size);
299 }
300
301 inline HeapWord* ShenandoahHeap::allocate_from_plab(Thread* thread, size_t size, bool is_promotion) {
302 assert(UseTLAB, "TLABs should be enabled");
303
304 PLAB* plab = ShenandoahThreadLocalData::plab(thread);
305 HeapWord* obj;
306 if (plab == NULL) {
307 assert(!thread->is_Java_thread() && !thread->is_Worker_thread(), "Performance: thread should have PLAB: %s", thread->name());
308 // No PLABs in this thread, fallback to shared allocation
309 return nullptr;
310 } else if (is_promotion && (plab->words_remaining() > 0) && !ShenandoahThreadLocalData::allow_plab_promotions(thread)) {
311 return nullptr;
312 }
313 // if plab->word_size() <= 0, thread's plab not yet initialized for this pass, so allow_plab_promotions() is not trustworthy
314 obj = plab->allocate(size);
315 if ((obj == nullptr) && (plab->words_remaining() < PLAB::min_size())) {
316 // allocate_from_plab_slow will establish allow_plab_promotions(thread) for future invocations
317 obj = allocate_from_plab_slow(thread, size, is_promotion);
318 }
319 // if plab->words_remaining() >= PLAB::min_size(), just return nullptr so we can use a shared allocation
320 if (obj == nullptr) {
321 return nullptr;
322 }
323
324 if (is_promotion) {
325 ShenandoahThreadLocalData::add_to_plab_promoted(thread, size * HeapWordSize);
326 } else {
327 ShenandoahThreadLocalData::add_to_plab_evacuated(thread, size * HeapWordSize);
328 }
329 return obj;
330 }
331
332 inline oop ShenandoahHeap::evacuate_object(oop p, Thread* thread) {
333 assert(thread == Thread::current(), "Expected thread parameter to be current thread.");
334 if (ShenandoahThreadLocalData::is_oom_during_evac(thread)) {
335 // This thread went through the OOM during evac protocol and it is safe to return
336 // the forward pointer. It must not attempt to evacuate any more.
337 return ShenandoahBarrierSet::resolve_forwarded(p);
338 }
339
340 assert(ShenandoahThreadLocalData::is_evac_allowed(thread), "must be enclosed in oom-evac scope");
341
342 ShenandoahHeapRegion* r = heap_region_containing(p);
343 assert(!r->is_humongous(), "never evacuate humongous objects");
344
345 ShenandoahRegionAffiliation target_gen = r->affiliation();
346 if (mode()->is_generational() && ShenandoahHeap::heap()->is_gc_generation_young() &&
347 target_gen == YOUNG_GENERATION && ShenandoahPromoteTenuredObjects) {
348 markWord mark = p->mark();
349 if (mark.is_marked()) {
350 // Already forwarded.
351 return ShenandoahBarrierSet::resolve_forwarded(p);
352 }
353 if (mark.has_displaced_mark_helper()) {
354 // We don't want to deal with MT here just to ensure we read the right mark word.
355 // Skip the potential promotion attempt for this one.
356 } else if (r->age() + mark.age() >= InitialTenuringThreshold) {
357 oop result = try_evacuate_object(p, thread, r, OLD_GENERATION);
358 if (result != NULL) {
359 return result;
360 }
361 // If we failed to promote this aged object, we'll fall through to code below and evacuate to young-gen.
362 }
363 }
364 return try_evacuate_object(p, thread, r, target_gen);
365 }
366
367 // try_evacuate_object registers the object and dirties the associated remembered set information when evacuating
368 // to OLD_GENERATION.
369 inline oop ShenandoahHeap::try_evacuate_object(oop p, Thread* thread, ShenandoahHeapRegion* from_region,
370 ShenandoahRegionAffiliation target_gen) {
371 bool alloc_from_lab = true;
372 bool has_plab = false;
373 HeapWord* copy = NULL;
374 size_t size = p->size();
375 bool is_promotion = (target_gen == OLD_GENERATION) && from_region->is_young();
376
377 #ifdef ASSERT
378 if (ShenandoahOOMDuringEvacALot &&
379 (os::random() & 1) == 0) { // Simulate OOM every ~2nd slow-path call
380 copy = NULL;
381 } else {
382 #endif
383 if (UseTLAB) {
384 switch (target_gen) {
385 case YOUNG_GENERATION: {
386 copy = allocate_from_gclab(thread, size);
387 if ((copy == nullptr) && (size < ShenandoahThreadLocalData::gclab_size(thread))) {
388 // GCLAB allocation failed because we are bumping up against the limit on young evacuation reserve. Try resetting
389 // the desired GCLAB size and retry GCLAB allocation to avoid cascading of shared memory allocations.
390 ShenandoahThreadLocalData::set_gclab_size(thread, PLAB::min_size());
391 copy = allocate_from_gclab(thread, size);
392 // If we still get nullptr, we'll try a shared allocation below.
393 }
394 break;
395 }
396 case OLD_GENERATION: {
397 if (ShenandoahUsePLAB) {
398 PLAB* plab = ShenandoahThreadLocalData::plab(thread);
399 if (plab != nullptr) {
400 has_plab = true;
401 }
402 copy = allocate_from_plab(thread, size, is_promotion);
403 if ((copy == nullptr) && (size < ShenandoahThreadLocalData::plab_size(thread)) &&
404 ShenandoahThreadLocalData::plab_retries_enabled(thread)) {
405 // PLAB allocation failed because we are bumping up against the limit on old evacuation reserve or because
406 // the requested object does not fit within the current plab but the plab still has an "abundance" of memory,
407 // where abundance is defined as >= PLAB::min_size(). In the former case, we try resetting the desired
408 // PLAB size and retry PLAB allocation to avoid cascading of shared memory allocations.
409
410 // In this situation, PLAB memory is precious. We'll try to preserve our existing PLAB by forcing
411 // this particular allocation to be shared.
412 if (plab->words_remaining() < PLAB::min_size()) {
413 ShenandoahThreadLocalData::set_plab_size(thread, PLAB::min_size());
414 copy = allocate_from_plab(thread, size, is_promotion);
415 // If we still get nullptr, we'll try a shared allocation below.
416 if (copy == nullptr) {
417 // If retry fails, don't continue to retry until we have success (probably in next GC pass)
418 ShenandoahThreadLocalData::disable_plab_retries(thread);
419 }
420 }
421 // else, copy still equals nullptr. this causes shared allocation below, preserving this plab for future needs.
422 }
423 }
424 break;
425 }
426 default: {
427 ShouldNotReachHere();
428 break;
429 }
430 }
431 }
432
433 if (copy == NULL) {
434 // If we failed to allocate in LAB, we'll try a shared allocation.
435 if (!is_promotion || !has_plab || (size > PLAB::min_size())) {
436 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared_gc(size, target_gen);
437 copy = allocate_memory(req, is_promotion);
438 alloc_from_lab = false;
439 }
440 // else, we leave copy equal to NULL, signaling a promotion failure below if appropriate.
441 // We choose not to promote objects smaller than PLAB::min_size() by way of shared allocations, as this is too
442 // costly. Instead, we'll simply "evacuate" to young-gen memory (using a GCLAB) and will promote in a future
443 // evacuation pass. This condition is denoted by: is_promotion && has_plab && (size <= PLAB::min_size())
444 }
445 #ifdef ASSERT
446 }
447 #endif
448
449 if (copy == NULL) {
450 if (target_gen == OLD_GENERATION) {
451 assert(mode()->is_generational(), "Should only be here in generational mode.");
452 if (from_region->is_young()) {
453 // Signal that promotion failed. Will evacuate this old object somewhere in young gen.
454
455 // We squelch excessive reports to reduce noise in logs. Squelch enforcement is not "perfect" because
456 // this same code can be in-lined in multiple contexts, and each context will have its own copy of the static
457 // last_report_epoch and this_epoch_report_count variables.
458 const uint MaxReportsPerEpoch = 4;
459 static uint last_report_epoch = 0;
460 static uint epoch_report_count = 0;
461 PLAB* plab = ShenandoahThreadLocalData::plab(thread);
462 size_t words_remaining = (plab == nullptr)? 0: plab->words_remaining();
463 const char* promote_enabled = ShenandoahThreadLocalData::allow_plab_promotions(thread)? "enabled": "disabled";
464 size_t promotion_reserve;
465 size_t promotion_expended;
466 // We can only query GCId::current() if current thread is a named thread. If current thread is not a
467 // named thread, then we don't even try to squelch the promotion failure report, we don't update the
468 // the last_report_epoch, and we don't increment the epoch_report_count
469 if (thread->is_Named_thread()) {
470 uint gc_id = GCId::current();
471 if ((gc_id != last_report_epoch) || (epoch_report_count++ < MaxReportsPerEpoch)) {
472 {
473 // Promotion failures should be very rare. Invest in providing useful diagnostic info.
474 ShenandoahHeapLocker locker(lock());
475 promotion_reserve = get_promoted_reserve();
476 promotion_expended = get_promoted_expended();
477 }
478 log_info(gc, ergo)("Promotion failed, size " SIZE_FORMAT ", has plab? %s, PLAB remaining: " SIZE_FORMAT
479 ", plab promotions %s, promotion reserve: " SIZE_FORMAT ", promotion expended: " SIZE_FORMAT,
480 size, plab == nullptr? "no": "yes",
481 words_remaining, promote_enabled, promotion_reserve, promotion_expended);
482 if ((gc_id == last_report_epoch) && (epoch_report_count >= MaxReportsPerEpoch)) {
483 log_info(gc, ergo)("Squelching additional promotion failure reports for epoch %d\n", last_report_epoch);
484 } else if (gc_id != last_report_epoch) {
485 last_report_epoch = gc_id;;
486 epoch_report_count = 1;
487 }
488 }
489 } else if (epoch_report_count < MaxReportsPerEpoch) {
490 // Unnamed threads are much less common than named threads. In the rare case that an unnamed thread experiences
491 // a promotion failure before a named thread within a given epoch, the report for the unnamed thread will be squelched.
492 {
493 // Promotion failures should be very rare. Invest in providing useful diagnostic info.
494 ShenandoahHeapLocker locker(lock());
495 promotion_reserve = get_promoted_reserve();
496 promotion_expended = get_promoted_expended();
497 }
498 log_info(gc, ergo)("Promotion failed (unfiltered), size " SIZE_FORMAT ", has plab? %s, PLAB remaining: " SIZE_FORMAT
499 ", plab promotions %s, promotion reserve: " SIZE_FORMAT ", promotion expended: " SIZE_FORMAT,
500 size, plab == nullptr? "no": "yes",
501 words_remaining, promote_enabled, promotion_reserve, promotion_expended);
502 }
503 handle_promotion_failure();
504 return NULL;
505 } else {
506 // Remember that evacuation to old gen failed. We'll want to trigger a full gc to recover from this
507 // after the evacuation threads have finished.
508 handle_old_evacuation_failure();
509 }
510 }
511
512 control_thread()->handle_alloc_failure_evac(size);
513
514 _oom_evac_handler.handle_out_of_memory_during_evacuation();
515
516 return ShenandoahBarrierSet::resolve_forwarded(p);
517 }
518
519 // Copy the object:
520 Copy::aligned_disjoint_words(cast_from_oop<HeapWord*>(p), copy, size);
521
522 oop copy_val = cast_to_oop(copy);
523
524 if (mode()->is_generational() && target_gen == YOUNG_GENERATION && is_aging_cycle()) {
525 ShenandoahHeap::increase_object_age(copy_val, from_region->age() + 1);
526 }
527
528 // Try to install the new forwarding pointer.
529 ContinuationGCSupport::relativize_stack_chunk(copy_val);
530
531 oop result = ShenandoahForwarding::try_update_forwardee(p, copy_val);
532 if (result == copy_val) {
533 // Successfully evacuated. Our copy is now the public one!
534 if (mode()->is_generational() && target_gen == OLD_GENERATION) {
535 handle_old_evacuation(copy, size, from_region->is_young());
536 }
537 shenandoah_assert_correct(NULL, copy_val);
538 return copy_val;
539 } else {
540 // Failed to evacuate. We need to deal with the object that is left behind. Since this
541 // new allocation is certainly after TAMS, it will be considered live in the next cycle.
542 // But if it happens to contain references to evacuated regions, those references would
543 // not get updated for this stale copy during this cycle, and we will crash while scanning
544 // it the next cycle.
545 if (alloc_from_lab) {
546 // For LAB allocations, it is enough to rollback the allocation ptr. Either the next
547 // object will overwrite this stale copy, or the filler object on LAB retirement will
548 // do this.
549 switch (target_gen) {
550 case YOUNG_GENERATION: {
551 ShenandoahThreadLocalData::gclab(thread)->undo_allocation(copy, size);
552 break;
553 }
554 case OLD_GENERATION: {
555 ShenandoahThreadLocalData::plab(thread)->undo_allocation(copy, size);
556 if (is_promotion) {
557 ShenandoahThreadLocalData::subtract_from_plab_promoted(thread, size * HeapWordSize);
558 } else {
559 ShenandoahThreadLocalData::subtract_from_plab_evacuated(thread, size * HeapWordSize);
560 }
561 break;
562 }
563 default: {
564 ShouldNotReachHere();
565 break;
566 }
567 }
568 } else {
569 // For non-LAB allocations, we have no way to retract the allocation, and
570 // have to explicitly overwrite the copy with the filler object. With that overwrite,
571 // we have to keep the fwdptr initialized and pointing to our (stale) copy.
572 fill_with_object(copy, size);
573 shenandoah_assert_correct(NULL, copy_val);
574 // For non-LAB allocations, the object has already been registered
575 }
576 shenandoah_assert_correct(NULL, result);
577 return result;
578 }
579 }
580
581 void ShenandoahHeap::increase_object_age(oop obj, uint additional_age) {
582 markWord w = obj->has_displaced_mark() ? obj->displaced_mark() : obj->mark();
583 w = w.set_age(MIN2(markWord::max_age, w.age() + additional_age));
584 if (obj->has_displaced_mark()) {
585 obj->set_displaced_mark(w);
586 } else {
587 obj->set_mark(w);
588 }
589 }
590
591 inline bool ShenandoahHeap::clear_old_evacuation_failure() {
592 return _old_gen_oom_evac.try_unset();
593 }
594
595 inline bool ShenandoahHeap::is_old(oop obj) const {
596 return is_gc_generation_young() && is_in_old(obj);
597 }
598
599 inline bool ShenandoahHeap::requires_marking(const void* entry) const {
600 oop obj = cast_to_oop(entry);
601 return !_marking_context->is_marked_strong(obj);
602 }
603
604 inline bool ShenandoahHeap::in_collection_set(oop p) const {
605 assert(collection_set() != NULL, "Sanity");
606 return collection_set()->is_in(p);
607 }
608
609 inline bool ShenandoahHeap::in_collection_set_loc(void* p) const {
610 assert(collection_set() != NULL, "Sanity");
611 return collection_set()->is_in_loc(p);
612 }
613
614 inline bool ShenandoahHeap::is_stable() const {
615 return _gc_state.is_clear();
616 }
617
618 inline bool ShenandoahHeap::is_idle() const {
619 return _gc_state.is_unset(YOUNG_MARKING | OLD_MARKING | EVACUATION | UPDATEREFS);
620 }
621
622 inline bool ShenandoahHeap::is_concurrent_mark_in_progress() const {
623 return _gc_state.is_set(YOUNG_MARKING | OLD_MARKING);
624 }
625
626 inline bool ShenandoahHeap::is_concurrent_young_mark_in_progress() const {
627 return _gc_state.is_set(YOUNG_MARKING);
628 }
629
630 inline bool ShenandoahHeap::is_concurrent_old_mark_in_progress() const {
631 return _gc_state.is_set(OLD_MARKING);
632 }
633
634 inline bool ShenandoahHeap::is_evacuation_in_progress() const {
635 return _gc_state.is_set(EVACUATION);
636 }
637
638 inline bool ShenandoahHeap::is_gc_in_progress_mask(uint mask) const {
639 return _gc_state.is_set(mask);
640 }
641
642 inline bool ShenandoahHeap::is_degenerated_gc_in_progress() const {
643 return _degenerated_gc_in_progress.is_set();
644 }
645
646 inline bool ShenandoahHeap::is_full_gc_in_progress() const {
647 return _full_gc_in_progress.is_set();
648 }
649
650 inline bool ShenandoahHeap::is_full_gc_move_in_progress() const {
651 return _full_gc_move_in_progress.is_set();
652 }
653
654 inline bool ShenandoahHeap::is_update_refs_in_progress() const {
655 return _gc_state.is_set(UPDATEREFS);
656 }
657
658 inline bool ShenandoahHeap::is_stw_gc_in_progress() const {
659 return is_full_gc_in_progress() || is_degenerated_gc_in_progress();
660 }
661
662 inline bool ShenandoahHeap::is_concurrent_strong_root_in_progress() const {
663 return _concurrent_strong_root_in_progress.is_set();
664 }
665
666 inline bool ShenandoahHeap::is_concurrent_weak_root_in_progress() const {
667 return _gc_state.is_set(WEAK_ROOTS);
668 }
669
670 inline bool ShenandoahHeap::is_aging_cycle() const {
671 return _is_aging_cycle.is_set();
672 }
673
674 inline bool ShenandoahHeap::is_prepare_for_old_mark_in_progress() const {
675 return _prepare_for_old_mark;
676 }
677
678 inline size_t ShenandoahHeap::set_promoted_reserve(size_t new_val) {
679 size_t orig = _promoted_reserve;
680 _promoted_reserve = new_val;
681 return orig;
682 }
683
684 inline size_t ShenandoahHeap::get_promoted_reserve() const {
685 return _promoted_reserve;
686 }
687
688 // returns previous value
689 size_t ShenandoahHeap::capture_old_usage(size_t old_usage) {
690 size_t previous_value = _captured_old_usage;
691 _captured_old_usage = old_usage;
692 return previous_value;
693 }
694
695 void ShenandoahHeap::set_previous_promotion(size_t promoted_bytes) {
696 shenandoah_assert_heaplocked();
697 _previous_promotion = promoted_bytes;
698 }
699
700 size_t ShenandoahHeap::get_previous_promotion() const {
701 return _previous_promotion;
702 }
703
704 inline size_t ShenandoahHeap::set_old_evac_reserve(size_t new_val) {
705 size_t orig = _old_evac_reserve;
706 _old_evac_reserve = new_val;
707 return orig;
708 }
709
710 inline size_t ShenandoahHeap::get_old_evac_reserve() const {
711 return _old_evac_reserve;
712 }
713
714 inline void ShenandoahHeap::reset_old_evac_expended() {
715 Atomic::store(&_old_evac_expended, (size_t) 0);
716 }
717
718 inline size_t ShenandoahHeap::expend_old_evac(size_t increment) {
719 return Atomic::add(&_old_evac_expended, increment);
720 }
721
722 inline size_t ShenandoahHeap::get_old_evac_expended() {
723 return Atomic::load(&_old_evac_expended);
724 }
725
726 inline void ShenandoahHeap::reset_promoted_expended() {
727 Atomic::store(&_promoted_expended, (size_t) 0);
728 }
729
730 inline size_t ShenandoahHeap::expend_promoted(size_t increment) {
731 return Atomic::add(&_promoted_expended, increment);
732 }
733
734 inline size_t ShenandoahHeap::unexpend_promoted(size_t decrement) {
735 return Atomic::sub(&_promoted_expended, decrement);
736 }
737
738 inline size_t ShenandoahHeap::get_promoted_expended() {
739 return Atomic::load(&_promoted_expended);
740 }
741
742 inline size_t ShenandoahHeap::set_young_evac_reserve(size_t new_val) {
743 size_t orig = _young_evac_reserve;
744 _young_evac_reserve = new_val;
745 return orig;
746 }
747
748 inline size_t ShenandoahHeap::get_young_evac_reserve() const {
749 return _young_evac_reserve;
750 }
751
752 inline intptr_t ShenandoahHeap::set_alloc_supplement_reserve(intptr_t new_val) {
753 intptr_t orig = _alloc_supplement_reserve;
754 _alloc_supplement_reserve = new_val;
755 return orig;
756 }
757
758 inline intptr_t ShenandoahHeap::get_alloc_supplement_reserve() const {
759 return _alloc_supplement_reserve;
760 }
761
762 template<class T>
763 inline void ShenandoahHeap::marked_object_iterate(ShenandoahHeapRegion* region, T* cl) {
764 marked_object_iterate(region, cl, region->top());
765 }
766
767 template<class T>
768 inline void ShenandoahHeap::marked_object_iterate(ShenandoahHeapRegion* region, T* cl, HeapWord* limit) {
769 assert(! region->is_humongous_continuation(), "no humongous continuation regions here");
770
771 ShenandoahMarkingContext* const ctx = marking_context();
772
773 HeapWord* tams = ctx->top_at_mark_start(region);
774
775 size_t skip_bitmap_delta = 1;
776 HeapWord* start = region->bottom();
777 HeapWord* end = MIN2(tams, region->end());
778
779 // Step 1. Scan below the TAMS based on bitmap data.
780 HeapWord* limit_bitmap = MIN2(limit, tams);
781
782 // Try to scan the initial candidate. If the candidate is above the TAMS, it would
783 // fail the subsequent "< limit_bitmap" checks, and fall through to Step 2.
784 HeapWord* cb = ctx->get_next_marked_addr(start, end);
785
786 intx dist = ShenandoahMarkScanPrefetch;
787 if (dist > 0) {
788 // Batched scan that prefetches the oop data, anticipating the access to
789 // either header, oop field, or forwarding pointer. Not that we cannot
790 // touch anything in oop, while it still being prefetched to get enough
791 // time for prefetch to work. This is why we try to scan the bitmap linearly,
792 // disregarding the object size. However, since we know forwarding pointer
793 // precedes the object, we can skip over it. Once we cannot trust the bitmap,
794 // there is no point for prefetching the oop contents, as oop->size() will
795 // touch it prematurely.
796
797 // No variable-length arrays in standard C++, have enough slots to fit
798 // the prefetch distance.
799 static const int SLOT_COUNT = 256;
800 guarantee(dist <= SLOT_COUNT, "adjust slot count");
801 HeapWord* slots[SLOT_COUNT];
802
803 int avail;
804 do {
805 avail = 0;
806 for (int c = 0; (c < dist) && (cb < limit_bitmap); c++) {
807 Prefetch::read(cb, oopDesc::mark_offset_in_bytes());
808 slots[avail++] = cb;
809 cb += skip_bitmap_delta;
810 if (cb < limit_bitmap) {
811 cb = ctx->get_next_marked_addr(cb, limit_bitmap);
812 }
813 }
814
815 for (int c = 0; c < avail; c++) {
816 assert (slots[c] < tams, "only objects below TAMS here: " PTR_FORMAT " (" PTR_FORMAT ")", p2i(slots[c]), p2i(tams));
817 assert (slots[c] < limit, "only objects below limit here: " PTR_FORMAT " (" PTR_FORMAT ")", p2i(slots[c]), p2i(limit));
818 oop obj = cast_to_oop(slots[c]);
819 assert(oopDesc::is_oop(obj), "sanity");
820 assert(ctx->is_marked(obj), "object expected to be marked");
821 cl->do_object(obj);
822 }
823 } while (avail > 0);
824 } else {
825 while (cb < limit_bitmap) {
826 assert (cb < tams, "only objects below TAMS here: " PTR_FORMAT " (" PTR_FORMAT ")", p2i(cb), p2i(tams));
827 assert (cb < limit, "only objects below limit here: " PTR_FORMAT " (" PTR_FORMAT ")", p2i(cb), p2i(limit));
828 oop obj = cast_to_oop(cb);
829 assert(oopDesc::is_oop(obj), "sanity");
830 assert(ctx->is_marked(obj), "object expected to be marked");
831 cl->do_object(obj);
832 cb += skip_bitmap_delta;
833 if (cb < limit_bitmap) {
834 cb = ctx->get_next_marked_addr(cb, limit_bitmap);
835 }
836 }
837 }
838
839 // Step 2. Accurate size-based traversal, happens past the TAMS.
840 // This restarts the scan at TAMS, which makes sure we traverse all objects,
841 // regardless of what happened at Step 1.
842 HeapWord* cs = tams;
843 while (cs < limit) {
844 assert (cs >= tams, "only objects past TAMS here: " PTR_FORMAT " (" PTR_FORMAT ")", p2i(cs), p2i(tams));
845 assert (cs < limit, "only objects below limit here: " PTR_FORMAT " (" PTR_FORMAT ")", p2i(cs), p2i(limit));
846 oop obj = cast_to_oop(cs);
847 assert(oopDesc::is_oop(obj), "sanity");
848 assert(ctx->is_marked(obj), "object expected to be marked");
849 size_t size = obj->size();
850 cl->do_object(obj);
851 cs += size;
852 }
853 }
854
855 template <class T>
856 class ShenandoahObjectToOopClosure : public ObjectClosure {
857 T* _cl;
858 public:
859 ShenandoahObjectToOopClosure(T* cl) : _cl(cl) {}
860
861 void do_object(oop obj) {
862 obj->oop_iterate(_cl);
863 }
864 };
865
866 template <class T>
867 class ShenandoahObjectToOopBoundedClosure : public ObjectClosure {
868 T* _cl;
869 MemRegion _bounds;
870 public:
871 ShenandoahObjectToOopBoundedClosure(T* cl, HeapWord* bottom, HeapWord* top) :
872 _cl(cl), _bounds(bottom, top) {}
873
874 void do_object(oop obj) {
875 obj->oop_iterate(_cl, _bounds);
876 }
877 };
878
879 template<class T>
880 inline void ShenandoahHeap::marked_object_oop_iterate(ShenandoahHeapRegion* region, T* cl, HeapWord* top) {
881 if (region->is_humongous()) {
882 HeapWord* bottom = region->bottom();
883 if (top > bottom) {
884 region = region->humongous_start_region();
885 ShenandoahObjectToOopBoundedClosure<T> objs(cl, bottom, top);
886 marked_object_iterate(region, &objs);
887 }
888 } else {
889 ShenandoahObjectToOopClosure<T> objs(cl);
890 marked_object_iterate(region, &objs, top);
891 }
892 }
893
894 inline ShenandoahHeapRegion* const ShenandoahHeap::get_region(size_t region_idx) const {
895 if (region_idx < _num_regions) {
896 return _regions[region_idx];
897 } else {
898 return NULL;
899 }
900 }
901
902 inline ShenandoahMarkingContext* ShenandoahHeap::complete_marking_context() const {
903 assert (_marking_context->is_complete()," sanity");
904 return _marking_context;
905 }
906
907 inline ShenandoahMarkingContext* ShenandoahHeap::marking_context() const {
908 return _marking_context;
909 }
910
911 inline void ShenandoahHeap::clear_cards_for(ShenandoahHeapRegion* region) {
912 if (mode()->is_generational()) {
913 _card_scan->mark_range_as_empty(region->bottom(), pointer_delta(region->end(), region->bottom()));
914 }
915 }
916
917 inline void ShenandoahHeap::dirty_cards(HeapWord* start, HeapWord* end) {
918 assert(mode()->is_generational(), "Should only be used for generational mode");
919 size_t words = pointer_delta(end, start);
920 _card_scan->mark_range_as_dirty(start, words);
921 }
922
923 inline void ShenandoahHeap::clear_cards(HeapWord* start, HeapWord* end) {
924 assert(mode()->is_generational(), "Should only be used for generational mode");
925 size_t words = pointer_delta(end, start);
926 _card_scan->mark_range_as_clean(start, words);
927 }
928
929 inline void ShenandoahHeap::mark_card_as_dirty(void* location) {
930 if (mode()->is_generational()) {
931 _card_scan->mark_card_as_dirty((HeapWord*)location);
932 }
933 }
934
935 #endif // SHARE_GC_SHENANDOAH_SHENANDOAHHEAP_INLINE_HPP