188
189 // Although we never intentionally push references outside of the collection
190 // set, due to (benign) races in the claim mechanism during RSet scanning more
191 // than one thread might claim the same card. So the same card may be
192 // processed multiple times, and so we might get references into old gen here.
193 // So we need to redo this check.
194 const G1HeapRegionAttr region_attr = _g1h->region_attr(obj);
195 // References pushed onto the work stack should never point to a humongous region
196 // as they are not added to the collection set due to above precondition.
197 assert(!region_attr.is_humongous(),
198 "Obj " PTR_FORMAT " should not refer to humongous region %u from " PTR_FORMAT,
199 p2i(obj), _g1h->addr_to_region(cast_from_oop<HeapWord*>(obj)), p2i(p));
200
201 if (!region_attr.is_in_cset()) {
202 // In this case somebody else already did all the work.
203 return;
204 }
205
206 markWord m = obj->mark();
207 if (m.is_marked()) {
208 obj = cast_to_oop(m.decode_pointer());
209 } else {
210 obj = do_copy_to_survivor_space(region_attr, obj, m);
211 }
212 RawAccess<IS_NOT_NULL>::oop_store(p, obj);
213
214 write_ref_field_post(p, obj);
215 }
216
217 MAYBE_INLINE_EVACUATION
218 void G1ParScanThreadState::do_partial_array(PartialArrayScanTask task) {
219 oop from_obj = task.to_source_array();
220
221 assert(_g1h->is_in_reserved(from_obj), "must be in heap.");
222 assert(from_obj->is_objArray(), "must be obj array");
223 assert(from_obj->is_forwarded(), "must be forwarded");
224
225 oop to_obj = from_obj->forwardee();
226 assert(from_obj != to_obj, "should not be chunking self-forwarded objects");
227 assert(to_obj->is_objArray(), "must be obj array");
228 objArrayOop to_array = objArrayOop(to_obj);
229
230 PartialArrayTaskStepper::Step step
231 = _partial_array_stepper.next(objArrayOop(from_obj),
232 to_array,
233 _partial_objarray_chunk_size);
234 for (uint i = 0; i < step._ncreate; ++i) {
235 push_on_queue(ScannerTask(PartialArrayScanTask(from_obj)));
236 }
237
238 G1HeapRegionAttr dest_attr = _g1h->region_attr(to_array);
239 G1SkipCardEnqueueSetter x(&_scanner, dest_attr.is_new_survivor());
240 // Process claimed task. The length of to_array is not correct, but
241 // fortunately the iteration ignores the length field and just relies
242 // on start/end.
243 to_array->oop_iterate_range(&_scanner,
244 step._index,
245 step._index + _partial_objarray_chunk_size);
246 }
247
248 MAYBE_INLINE_EVACUATION
249 void G1ParScanThreadState::start_partial_objarray(G1HeapRegionAttr dest_attr,
250 oop from_obj,
251 oop to_obj) {
252 assert(from_obj->is_objArray(), "precondition");
253 assert(from_obj->is_forwarded(), "precondition");
254 assert(from_obj->forwardee() == to_obj, "precondition");
255 assert(from_obj != to_obj, "should not be scanning self-forwarded objects");
256 assert(to_obj->is_objArray(), "precondition");
257
258 objArrayOop to_array = objArrayOop(to_obj);
259
260 PartialArrayTaskStepper::Step step
261 = _partial_array_stepper.start(objArrayOop(from_obj),
262 to_array,
263 _partial_objarray_chunk_size);
264
265 // Push any needed partial scan tasks. Pushed before processing the
266 // intitial chunk to allow other workers to steal while we're processing.
267 for (uint i = 0; i < step._ncreate; ++i) {
268 push_on_queue(ScannerTask(PartialArrayScanTask(from_obj)));
269 }
270
271 // Skip the card enqueue iff the object (to_array) is in survivor region.
272 // However, HeapRegion::is_survivor() is too expensive here.
359 // no other space to try.
360 return NULL;
361 }
362 }
363
364 G1HeapRegionAttr G1ParScanThreadState::next_region_attr(G1HeapRegionAttr const region_attr, markWord const m, uint& age) {
365 assert(region_attr.is_young() || region_attr.is_old(), "must be either Young or Old");
366
367 if (region_attr.is_young()) {
368 age = !m.has_displaced_mark_helper() ? m.age()
369 : m.displaced_mark_helper().age();
370 if (age < _tenuring_threshold) {
371 return region_attr;
372 }
373 }
374 // young-to-old (promotion) or old-to-old; destination is old in both cases.
375 return G1HeapRegionAttr::Old;
376 }
377
378 void G1ParScanThreadState::report_promotion_event(G1HeapRegionAttr const dest_attr,
379 oop const old, size_t word_sz, uint age,
380 HeapWord * const obj_ptr, uint node_index) const {
381 PLAB* alloc_buf = _plab_allocator->alloc_buffer(dest_attr, node_index);
382 if (alloc_buf->contains(obj_ptr)) {
383 _g1h->gc_tracer_stw()->report_promotion_in_new_plab_event(old->klass(), word_sz * HeapWordSize, age,
384 dest_attr.type() == G1HeapRegionAttr::Old,
385 alloc_buf->word_sz() * HeapWordSize);
386 } else {
387 _g1h->gc_tracer_stw()->report_promotion_outside_plab_event(old->klass(), word_sz * HeapWordSize, age,
388 dest_attr.type() == G1HeapRegionAttr::Old);
389 }
390 }
391
392 NOINLINE
393 HeapWord* G1ParScanThreadState::allocate_copy_slow(G1HeapRegionAttr* dest_attr,
394 oop old,
395 size_t word_sz,
396 uint age,
397 uint node_index) {
398 HeapWord* obj_ptr = NULL;
399 // Try slow-path allocation unless we're allocating old and old is already full.
400 if (!(dest_attr->is_old() && _old_gen_is_full)) {
401 bool plab_refill_failed = false;
402 obj_ptr = _plab_allocator->allocate_direct_or_new_plab(*dest_attr,
403 word_sz,
404 &plab_refill_failed,
405 node_index);
406 if (obj_ptr == NULL) {
407 obj_ptr = allocate_in_next_plab(dest_attr,
408 word_sz,
409 plab_refill_failed,
410 node_index);
411 }
412 }
413 if (obj_ptr != NULL) {
414 update_numa_stats(node_index);
415 if (_g1h->gc_tracer_stw()->should_report_promotion_events()) {
416 // The events are checked individually as part of the actual commit
417 report_promotion_event(*dest_attr, old, word_sz, age, obj_ptr, node_index);
418 }
419 }
420 return obj_ptr;
421 }
422
423 #if EVAC_FAILURE_INJECTOR
424 bool G1ParScanThreadState::inject_evacuation_failure(uint region_idx) {
425 return _g1h->evac_failure_injector()->evacuation_should_fail(_evac_failure_inject_counter, region_idx);
426 }
427 #endif
428
429 NOINLINE
430 void G1ParScanThreadState::undo_allocation(G1HeapRegionAttr dest_attr,
431 HeapWord* obj_ptr,
432 size_t word_sz,
433 uint node_index) {
434 _plab_allocator->undo_allocation(dest_attr, obj_ptr, word_sz, node_index);
435 }
436
437 // Private inline function, for direct internal use and providing the
438 // implementation of the public not-inline function.
439 MAYBE_INLINE_EVACUATION
440 oop G1ParScanThreadState::do_copy_to_survivor_space(G1HeapRegionAttr const region_attr,
441 oop const old,
442 markWord const old_mark) {
443 assert(region_attr.is_in_cset(),
444 "Unexpected region attr type: %s", region_attr.get_type_str());
445
446 // Get the klass once. We'll need it again later, and this avoids
447 // re-decoding when it's compressed.
448 Klass* klass = old->klass();
449 const size_t word_sz = old->size_given_klass(klass);
450
451 uint age = 0;
452 G1HeapRegionAttr dest_attr = next_region_attr(region_attr, old_mark, age);
453 HeapRegion* const from_region = _g1h->heap_region_containing(old);
454 uint node_index = from_region->node_index();
455
456 HeapWord* obj_ptr = _plab_allocator->plab_allocate(dest_attr, word_sz, node_index);
457
458 // PLAB allocations should succeed most of the time, so we'll
459 // normally check against NULL once and that's it.
460 if (obj_ptr == NULL) {
461 obj_ptr = allocate_copy_slow(&dest_attr, old, word_sz, age, node_index);
462 if (obj_ptr == NULL) {
463 // This will either forward-to-self, or detect that someone else has
464 // installed a forwarding pointer.
465 return handle_evacuation_failure_par(old, old_mark, word_sz);
466 }
467 }
468
469 assert(obj_ptr != NULL, "when we get here, allocation should have succeeded");
470 assert(_g1h->is_in_reserved(obj_ptr), "Allocated memory should be in the heap");
471
472 // Should this evacuation fail?
473 if (inject_evacuation_failure(from_region->hrm_index())) {
474 // Doing this after all the allocation attempts also tests the
475 // undo_allocation() method too.
476 undo_allocation(dest_attr, obj_ptr, word_sz, node_index);
477 return handle_evacuation_failure_par(old, old_mark, word_sz);
478 }
479
480 // We're going to allocate linearly, so might as well prefetch ahead.
481 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
595 delete pss;
596 _states[worker_id] = NULL;
597 }
598 _flushed = true;
599 }
600
601 void G1ParScanThreadStateSet::record_unused_optional_region(HeapRegion* hr) {
602 for (uint worker_index = 0; worker_index < _n_workers; ++worker_index) {
603 G1ParScanThreadState* pss = _states[worker_index];
604 assert(pss != nullptr, "must be initialized");
605
606 size_t used_memory = pss->oops_into_optional_region(hr)->used_memory();
607 _g1h->phase_times()->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanHR, worker_index, used_memory, G1GCPhaseTimes::ScanHRUsedMemory);
608 }
609 }
610
611 NOINLINE
612 oop G1ParScanThreadState::handle_evacuation_failure_par(oop old, markWord m, size_t word_sz) {
613 assert(_g1h->is_in_cset(old), "Object " PTR_FORMAT " should be in the CSet", p2i(old));
614
615 oop forward_ptr = old->forward_to_atomic(old, m, memory_order_relaxed);
616 if (forward_ptr == NULL) {
617 // Forward-to-self succeeded. We are the "owner" of the object.
618 HeapRegion* r = _g1h->heap_region_containing(old);
619 // Records evac failure objs, this will help speed up iteration
620 // of these objs later in *remove self forward* phase of post evacuation.
621 r->record_evac_failure_obj(old);
622
623 if (_evac_failure_regions->record(r->hrm_index())) {
624 _g1h->hr_printer()->evac_failure(r);
625 }
626
627 _preserved_marks->push_if_necessary(old, m);
628 _evacuation_failed_info.register_copy_failure(word_sz);
629
630 // For iterating objects that failed evacuation currently we can reuse the
631 // existing closure to scan evacuated objects because:
632 // - for objects referring into the collection set we do not need to gather
633 // cards at this time. The regions they are in will be unconditionally turned
634 // to old regions without remembered sets.
635 // - since we are iterating from a collection set region (i.e. never a Survivor
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188
189 // Although we never intentionally push references outside of the collection
190 // set, due to (benign) races in the claim mechanism during RSet scanning more
191 // than one thread might claim the same card. So the same card may be
192 // processed multiple times, and so we might get references into old gen here.
193 // So we need to redo this check.
194 const G1HeapRegionAttr region_attr = _g1h->region_attr(obj);
195 // References pushed onto the work stack should never point to a humongous region
196 // as they are not added to the collection set due to above precondition.
197 assert(!region_attr.is_humongous(),
198 "Obj " PTR_FORMAT " should not refer to humongous region %u from " PTR_FORMAT,
199 p2i(obj), _g1h->addr_to_region(cast_from_oop<HeapWord*>(obj)), p2i(p));
200
201 if (!region_attr.is_in_cset()) {
202 // In this case somebody else already did all the work.
203 return;
204 }
205
206 markWord m = obj->mark();
207 if (m.is_marked()) {
208 obj = obj->forwardee(m);
209 } else {
210 obj = do_copy_to_survivor_space(region_attr, obj, m);
211 }
212 RawAccess<IS_NOT_NULL>::oop_store(p, obj);
213
214 write_ref_field_post(p, obj);
215 }
216
217 MAYBE_INLINE_EVACUATION
218 void G1ParScanThreadState::do_partial_array(PartialArrayScanTask task) {
219 oop from_obj = task.to_source_array();
220
221 assert(_g1h->is_in_reserved(from_obj), "must be in heap.");
222 assert(from_obj->is_forwarded(), "must be forwarded");
223
224 oop to_obj = from_obj->forwardee();
225 assert(from_obj != to_obj, "should not be chunking self-forwarded objects");
226 assert(to_obj->is_objArray(), "must be obj array");
227 objArrayOop to_array = objArrayOop(to_obj);
228
229 PartialArrayTaskStepper::Step step
230 = _partial_array_stepper.next(objArrayOop(from_obj),
231 to_array,
232 _partial_objarray_chunk_size);
233 for (uint i = 0; i < step._ncreate; ++i) {
234 push_on_queue(ScannerTask(PartialArrayScanTask(from_obj)));
235 }
236
237 G1HeapRegionAttr dest_attr = _g1h->region_attr(to_array);
238 G1SkipCardEnqueueSetter x(&_scanner, dest_attr.is_new_survivor());
239 // Process claimed task. The length of to_array is not correct, but
240 // fortunately the iteration ignores the length field and just relies
241 // on start/end.
242 to_array->oop_iterate_range(&_scanner,
243 step._index,
244 step._index + _partial_objarray_chunk_size);
245 }
246
247 MAYBE_INLINE_EVACUATION
248 void G1ParScanThreadState::start_partial_objarray(G1HeapRegionAttr dest_attr,
249 oop from_obj,
250 oop to_obj) {
251 assert(from_obj->is_forwarded(), "precondition");
252 assert(from_obj->forwardee() == to_obj, "precondition");
253 assert(from_obj != to_obj, "should not be scanning self-forwarded objects");
254 assert(to_obj->is_objArray(), "precondition");
255
256 objArrayOop to_array = objArrayOop(to_obj);
257
258 PartialArrayTaskStepper::Step step
259 = _partial_array_stepper.start(objArrayOop(from_obj),
260 to_array,
261 _partial_objarray_chunk_size);
262
263 // Push any needed partial scan tasks. Pushed before processing the
264 // intitial chunk to allow other workers to steal while we're processing.
265 for (uint i = 0; i < step._ncreate; ++i) {
266 push_on_queue(ScannerTask(PartialArrayScanTask(from_obj)));
267 }
268
269 // Skip the card enqueue iff the object (to_array) is in survivor region.
270 // However, HeapRegion::is_survivor() is too expensive here.
357 // no other space to try.
358 return NULL;
359 }
360 }
361
362 G1HeapRegionAttr G1ParScanThreadState::next_region_attr(G1HeapRegionAttr const region_attr, markWord const m, uint& age) {
363 assert(region_attr.is_young() || region_attr.is_old(), "must be either Young or Old");
364
365 if (region_attr.is_young()) {
366 age = !m.has_displaced_mark_helper() ? m.age()
367 : m.displaced_mark_helper().age();
368 if (age < _tenuring_threshold) {
369 return region_attr;
370 }
371 }
372 // young-to-old (promotion) or old-to-old; destination is old in both cases.
373 return G1HeapRegionAttr::Old;
374 }
375
376 void G1ParScanThreadState::report_promotion_event(G1HeapRegionAttr const dest_attr,
377 oop const old, Klass* klass, size_t word_sz, uint age,
378 HeapWord * const obj_ptr, uint node_index) const {
379 PLAB* alloc_buf = _plab_allocator->alloc_buffer(dest_attr, node_index);
380 if (alloc_buf->contains(obj_ptr)) {
381 _g1h->gc_tracer_stw()->report_promotion_in_new_plab_event(klass, word_sz * HeapWordSize, age,
382 dest_attr.type() == G1HeapRegionAttr::Old,
383 alloc_buf->word_sz() * HeapWordSize);
384 } else {
385 _g1h->gc_tracer_stw()->report_promotion_outside_plab_event(klass, word_sz * HeapWordSize, age,
386 dest_attr.type() == G1HeapRegionAttr::Old);
387 }
388 }
389
390 NOINLINE
391 HeapWord* G1ParScanThreadState::allocate_copy_slow(G1HeapRegionAttr* dest_attr,
392 oop old,
393 Klass* klass,
394 size_t word_sz,
395 uint age,
396 uint node_index) {
397 HeapWord* obj_ptr = NULL;
398 // Try slow-path allocation unless we're allocating old and old is already full.
399 if (!(dest_attr->is_old() && _old_gen_is_full)) {
400 bool plab_refill_failed = false;
401 obj_ptr = _plab_allocator->allocate_direct_or_new_plab(*dest_attr,
402 word_sz,
403 &plab_refill_failed,
404 node_index);
405 if (obj_ptr == NULL) {
406 obj_ptr = allocate_in_next_plab(dest_attr,
407 word_sz,
408 plab_refill_failed,
409 node_index);
410 }
411 }
412 if (obj_ptr != NULL) {
413 update_numa_stats(node_index);
414 if (_g1h->gc_tracer_stw()->should_report_promotion_events()) {
415 // The events are checked individually as part of the actual commit
416 report_promotion_event(*dest_attr, old, klass, word_sz, age, obj_ptr, node_index);
417 }
418 }
419 return obj_ptr;
420 }
421
422 #if EVAC_FAILURE_INJECTOR
423 bool G1ParScanThreadState::inject_evacuation_failure(uint region_idx) {
424 return _g1h->evac_failure_injector()->evacuation_should_fail(_evac_failure_inject_counter, region_idx);
425 }
426 #endif
427
428 NOINLINE
429 void G1ParScanThreadState::undo_allocation(G1HeapRegionAttr dest_attr,
430 HeapWord* obj_ptr,
431 size_t word_sz,
432 uint node_index) {
433 _plab_allocator->undo_allocation(dest_attr, obj_ptr, word_sz, node_index);
434 }
435
436 // Private inline function, for direct internal use and providing the
437 // implementation of the public not-inline function.
438 MAYBE_INLINE_EVACUATION
439 oop G1ParScanThreadState::do_copy_to_survivor_space(G1HeapRegionAttr const region_attr,
440 oop const old,
441 markWord const old_mark) {
442 assert(region_attr.is_in_cset(),
443 "Unexpected region attr type: %s", region_attr.get_type_str());
444
445 if (old_mark.is_marked()) {
446 // Already forwarded by somebody else, return forwardee.
447 return old->forwardee(old_mark);
448 }
449 // Get the klass once. We'll need it again later, and this avoids
450 // re-decoding when it's compressed.
451 #ifdef _LP64
452 Klass* klass = old_mark.safe_klass();
453 #else
454 Klass* klass = old->klass();
455 #endif
456 const size_t word_sz = old->size_given_klass(klass);
457
458 uint age = 0;
459 G1HeapRegionAttr dest_attr = next_region_attr(region_attr, old_mark, age);
460 HeapRegion* const from_region = _g1h->heap_region_containing(old);
461 uint node_index = from_region->node_index();
462
463 HeapWord* obj_ptr = _plab_allocator->plab_allocate(dest_attr, word_sz, node_index);
464
465 // PLAB allocations should succeed most of the time, so we'll
466 // normally check against NULL once and that's it.
467 if (obj_ptr == NULL) {
468 obj_ptr = allocate_copy_slow(&dest_attr, old, klass, word_sz, age, node_index);
469 if (obj_ptr == NULL) {
470 // This will either forward-to-self, or detect that someone else has
471 // installed a forwarding pointer.
472 return handle_evacuation_failure_par(old, old_mark, word_sz);
473 }
474 }
475
476 assert(obj_ptr != NULL, "when we get here, allocation should have succeeded");
477 assert(_g1h->is_in_reserved(obj_ptr), "Allocated memory should be in the heap");
478
479 // Should this evacuation fail?
480 if (inject_evacuation_failure(from_region->hrm_index())) {
481 // Doing this after all the allocation attempts also tests the
482 // undo_allocation() method too.
483 undo_allocation(dest_attr, obj_ptr, word_sz, node_index);
484 return handle_evacuation_failure_par(old, old_mark, word_sz);
485 }
486
487 // We're going to allocate linearly, so might as well prefetch ahead.
488 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
602 delete pss;
603 _states[worker_id] = NULL;
604 }
605 _flushed = true;
606 }
607
608 void G1ParScanThreadStateSet::record_unused_optional_region(HeapRegion* hr) {
609 for (uint worker_index = 0; worker_index < _n_workers; ++worker_index) {
610 G1ParScanThreadState* pss = _states[worker_index];
611 assert(pss != nullptr, "must be initialized");
612
613 size_t used_memory = pss->oops_into_optional_region(hr)->used_memory();
614 _g1h->phase_times()->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanHR, worker_index, used_memory, G1GCPhaseTimes::ScanHRUsedMemory);
615 }
616 }
617
618 NOINLINE
619 oop G1ParScanThreadState::handle_evacuation_failure_par(oop old, markWord m, size_t word_sz) {
620 assert(_g1h->is_in_cset(old), "Object " PTR_FORMAT " should be in the CSet", p2i(old));
621
622 oop forward_ptr = old->forward_to_self_atomic(m, memory_order_relaxed);
623 if (forward_ptr == NULL) {
624 // Forward-to-self succeeded. We are the "owner" of the object.
625 HeapRegion* r = _g1h->heap_region_containing(old);
626 // Records evac failure objs, this will help speed up iteration
627 // of these objs later in *remove self forward* phase of post evacuation.
628 r->record_evac_failure_obj(old);
629
630 if (_evac_failure_regions->record(r->hrm_index())) {
631 _g1h->hr_printer()->evac_failure(r);
632 }
633
634 _preserved_marks->push_if_necessary(old, m);
635 _evacuation_failed_info.register_copy_failure(word_sz);
636
637 // For iterating objects that failed evacuation currently we can reuse the
638 // existing closure to scan evacuated objects because:
639 // - for objects referring into the collection set we do not need to gather
640 // cards at this time. The regions they are in will be unconditionally turned
641 // to old regions without remembered sets.
642 // - since we are iterating from a collection set region (i.e. never a Survivor
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