190
191 // Although we never intentionally push references outside of the collection
192 // set, due to (benign) races in the claim mechanism during RSet scanning more
193 // than one thread might claim the same card. So the same card may be
194 // processed multiple times, and so we might get references into old gen here.
195 // So we need to redo this check.
196 const G1HeapRegionAttr region_attr = _g1h->region_attr(obj);
197 // References pushed onto the work stack should never point to a humongous region
198 // as they are not added to the collection set due to above precondition.
199 assert(!region_attr.is_humongous_candidate(),
200 "Obj " PTR_FORMAT " should not refer to humongous region %u from " PTR_FORMAT,
201 p2i(obj), _g1h->addr_to_region(obj), p2i(p));
202
203 if (!region_attr.is_in_cset()) {
204 // In this case somebody else already did all the work.
205 return;
206 }
207
208 markWord m = obj->mark();
209 if (m.is_marked()) {
210 obj = cast_to_oop(m.decode_pointer());
211 } else {
212 obj = do_copy_to_survivor_space(region_attr, obj, m);
213 }
214 RawAccess<IS_NOT_NULL>::oop_store(p, obj);
215
216 write_ref_field_post(p, obj);
217 }
218
219 MAYBE_INLINE_EVACUATION
220 void G1ParScanThreadState::do_partial_array(PartialArrayScanTask task) {
221 oop from_obj = task.to_source_array();
222
223 assert(_g1h->is_in_reserved(from_obj), "must be in heap.");
224 assert(from_obj->is_objArray(), "must be obj array");
225 assert(from_obj->is_forwarded(), "must be forwarded");
226
227 oop to_obj = from_obj->forwardee();
228 assert(from_obj != to_obj, "should not be chunking self-forwarded objects");
229 assert(to_obj->is_objArray(), "must be obj array");
230 objArrayOop to_array = objArrayOop(to_obj);
231
232 PartialArrayTaskStepper::Step step
233 = _partial_array_stepper.next(objArrayOop(from_obj),
234 to_array,
235 _partial_objarray_chunk_size);
236 for (uint i = 0; i < step._ncreate; ++i) {
237 push_on_queue(ScannerTask(PartialArrayScanTask(from_obj)));
238 }
239
240 G1HeapRegionAttr dest_attr = _g1h->region_attr(to_array);
241 G1SkipCardEnqueueSetter x(&_scanner, dest_attr.is_new_survivor());
242 // Process claimed task. The length of to_array is not correct, but
243 // fortunately the iteration ignores the length field and just relies
244 // on start/end.
245 to_array->oop_iterate_range(&_scanner,
246 step._index,
247 step._index + _partial_objarray_chunk_size);
248 }
249
250 MAYBE_INLINE_EVACUATION
251 void G1ParScanThreadState::start_partial_objarray(G1HeapRegionAttr dest_attr,
252 oop from_obj,
253 oop to_obj) {
254 assert(from_obj->is_objArray(), "precondition");
255 assert(from_obj->is_forwarded(), "precondition");
256 assert(from_obj->forwardee() == to_obj, "precondition");
257 assert(from_obj != to_obj, "should not be scanning self-forwarded objects");
258 assert(to_obj->is_objArray(), "precondition");
259
260 objArrayOop to_array = objArrayOop(to_obj);
261
262 PartialArrayTaskStepper::Step step
263 = _partial_array_stepper.start(objArrayOop(from_obj),
264 to_array,
265 _partial_objarray_chunk_size);
266
267 // Push any needed partial scan tasks. Pushed before processing the
268 // initial chunk to allow other workers to steal while we're processing.
269 for (uint i = 0; i < step._ncreate; ++i) {
270 push_on_queue(ScannerTask(PartialArrayScanTask(from_obj)));
271 }
272
273 // Skip the card enqueue iff the object (to_array) is in survivor region.
274 // However, HeapRegion::is_survivor() is too expensive here.
361 // no other space to try.
362 return nullptr;
363 }
364 }
365
366 G1HeapRegionAttr G1ParScanThreadState::next_region_attr(G1HeapRegionAttr const region_attr, markWord const m, uint& age) {
367 assert(region_attr.is_young() || region_attr.is_old(), "must be either Young or Old");
368
369 if (region_attr.is_young()) {
370 age = !m.has_displaced_mark_helper() ? m.age()
371 : m.displaced_mark_helper().age();
372 if (age < _tenuring_threshold) {
373 return region_attr;
374 }
375 }
376 // young-to-old (promotion) or old-to-old; destination is old in both cases.
377 return G1HeapRegionAttr::Old;
378 }
379
380 void G1ParScanThreadState::report_promotion_event(G1HeapRegionAttr const dest_attr,
381 oop const old, size_t word_sz, uint age,
382 HeapWord * const obj_ptr, uint node_index) const {
383 PLAB* alloc_buf = _plab_allocator->alloc_buffer(dest_attr, node_index);
384 if (alloc_buf->contains(obj_ptr)) {
385 _g1h->gc_tracer_stw()->report_promotion_in_new_plab_event(old->klass(), word_sz * HeapWordSize, age,
386 dest_attr.type() == G1HeapRegionAttr::Old,
387 alloc_buf->word_sz() * HeapWordSize);
388 } else {
389 _g1h->gc_tracer_stw()->report_promotion_outside_plab_event(old->klass(), word_sz * HeapWordSize, age,
390 dest_attr.type() == G1HeapRegionAttr::Old);
391 }
392 }
393
394 NOINLINE
395 HeapWord* G1ParScanThreadState::allocate_copy_slow(G1HeapRegionAttr* dest_attr,
396 oop old,
397 size_t word_sz,
398 uint age,
399 uint node_index) {
400 HeapWord* obj_ptr = nullptr;
401 // Try slow-path allocation unless we're allocating old and old is already full.
402 if (!(dest_attr->is_old() && _old_gen_is_full)) {
403 bool plab_refill_failed = false;
404 obj_ptr = _plab_allocator->allocate_direct_or_new_plab(*dest_attr,
405 word_sz,
406 &plab_refill_failed,
407 node_index);
408 if (obj_ptr == nullptr) {
409 obj_ptr = allocate_in_next_plab(dest_attr,
410 word_sz,
411 plab_refill_failed,
412 node_index);
413 }
414 }
415 if (obj_ptr != nullptr) {
416 update_numa_stats(node_index);
417 if (_g1h->gc_tracer_stw()->should_report_promotion_events()) {
418 // The events are checked individually as part of the actual commit
419 report_promotion_event(*dest_attr, old, word_sz, age, obj_ptr, node_index);
420 }
421 }
422 return obj_ptr;
423 }
424
425 #if EVAC_FAILURE_INJECTOR
426 bool G1ParScanThreadState::inject_evacuation_failure(uint region_idx) {
427 return _g1h->evac_failure_injector()->evacuation_should_fail(_evac_failure_inject_counter, region_idx);
428 }
429 #endif
430
431 NOINLINE
432 void G1ParScanThreadState::undo_allocation(G1HeapRegionAttr dest_attr,
433 HeapWord* obj_ptr,
434 size_t word_sz,
435 uint node_index) {
436 _plab_allocator->undo_allocation(dest_attr, obj_ptr, word_sz, node_index);
437 }
438
439 void G1ParScanThreadState::update_bot_after_copying(oop obj, size_t word_sz) {
440 HeapWord* obj_start = cast_from_oop<HeapWord*>(obj);
441 HeapRegion* region = _g1h->heap_region_containing(obj_start);
442 region->update_bot_for_obj(obj_start, word_sz);
443 }
444
445 // Private inline function, for direct internal use and providing the
446 // implementation of the public not-inline function.
447 MAYBE_INLINE_EVACUATION
448 oop G1ParScanThreadState::do_copy_to_survivor_space(G1HeapRegionAttr const region_attr,
449 oop const old,
450 markWord const old_mark) {
451 assert(region_attr.is_in_cset(),
452 "Unexpected region attr type: %s", region_attr.get_type_str());
453
454 // Get the klass once. We'll need it again later, and this avoids
455 // re-decoding when it's compressed.
456 Klass* klass = old->klass();
457 const size_t word_sz = old->size_given_klass(klass);
458
459 uint age = 0;
460 G1HeapRegionAttr dest_attr = next_region_attr(region_attr, old_mark, age);
461 HeapRegion* const from_region = _g1h->heap_region_containing(old);
462 uint node_index = from_region->node_index();
463
464 HeapWord* obj_ptr = _plab_allocator->plab_allocate(dest_attr, word_sz, node_index);
465
466 // PLAB allocations should succeed most of the time, so we'll
467 // normally check against null once and that's it.
468 if (obj_ptr == nullptr) {
469 obj_ptr = allocate_copy_slow(&dest_attr, old, word_sz, age, node_index);
470 if (obj_ptr == nullptr) {
471 // This will either forward-to-self, or detect that someone else has
472 // installed a forwarding pointer.
473 return handle_evacuation_failure_par(old, old_mark, word_sz);
474 }
475 }
476
477 assert(obj_ptr != nullptr, "when we get here, allocation should have succeeded");
478 assert(_g1h->is_in_reserved(obj_ptr), "Allocated memory should be in the heap");
479
480 // Should this evacuation fail?
481 if (inject_evacuation_failure(from_region->hrm_index())) {
482 // Doing this after all the allocation attempts also tests the
483 // undo_allocation() method too.
484 undo_allocation(dest_attr, obj_ptr, word_sz, node_index);
485 return handle_evacuation_failure_par(old, old_mark, word_sz);
486 }
487
488 // We're going to allocate linearly, so might as well prefetch ahead.
489 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
603 delete pss;
604 _states[worker_id] = nullptr;
605 }
606 _flushed = true;
607 }
608
609 void G1ParScanThreadStateSet::record_unused_optional_region(HeapRegion* hr) {
610 for (uint worker_index = 0; worker_index < _num_workers; ++worker_index) {
611 G1ParScanThreadState* pss = _states[worker_index];
612 assert(pss != nullptr, "must be initialized");
613
614 size_t used_memory = pss->oops_into_optional_region(hr)->used_memory();
615 _g1h->phase_times()->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanHR, worker_index, used_memory, G1GCPhaseTimes::ScanHRUsedMemory);
616 }
617 }
618
619 NOINLINE
620 oop G1ParScanThreadState::handle_evacuation_failure_par(oop old, markWord m, size_t word_sz) {
621 assert(_g1h->is_in_cset(old), "Object " PTR_FORMAT " should be in the CSet", p2i(old));
622
623 oop forward_ptr = old->forward_to_atomic(old, m, memory_order_relaxed);
624 if (forward_ptr == nullptr) {
625 // Forward-to-self succeeded. We are the "owner" of the object.
626 HeapRegion* r = _g1h->heap_region_containing(old);
627
628 if (_evac_failure_regions->record(r->hrm_index())) {
629 _g1h->hr_printer()->evac_failure(r);
630 }
631
632 // Mark the failing object in the marking bitmap and later use the bitmap to handle
633 // evacuation failure recovery.
634 _g1h->mark_evac_failure_object(_worker_id, old, word_sz);
635
636 _preserved_marks->push_if_necessary(old, m);
637
638 ContinuationGCSupport::transform_stack_chunk(old);
639
640 _evacuation_failed_info.register_copy_failure(word_sz);
641
642 // For iterating objects that failed evacuation currently we can reuse the
643 // existing closure to scan evacuated objects because:
|
190
191 // Although we never intentionally push references outside of the collection
192 // set, due to (benign) races in the claim mechanism during RSet scanning more
193 // than one thread might claim the same card. So the same card may be
194 // processed multiple times, and so we might get references into old gen here.
195 // So we need to redo this check.
196 const G1HeapRegionAttr region_attr = _g1h->region_attr(obj);
197 // References pushed onto the work stack should never point to a humongous region
198 // as they are not added to the collection set due to above precondition.
199 assert(!region_attr.is_humongous_candidate(),
200 "Obj " PTR_FORMAT " should not refer to humongous region %u from " PTR_FORMAT,
201 p2i(obj), _g1h->addr_to_region(obj), p2i(p));
202
203 if (!region_attr.is_in_cset()) {
204 // In this case somebody else already did all the work.
205 return;
206 }
207
208 markWord m = obj->mark();
209 if (m.is_marked()) {
210 obj = obj->forwardee(m);
211 } else {
212 obj = do_copy_to_survivor_space(region_attr, obj, m);
213 }
214 RawAccess<IS_NOT_NULL>::oop_store(p, obj);
215
216 write_ref_field_post(p, obj);
217 }
218
219 MAYBE_INLINE_EVACUATION
220 void G1ParScanThreadState::do_partial_array(PartialArrayScanTask task) {
221 oop from_obj = task.to_source_array();
222
223 assert(_g1h->is_in_reserved(from_obj), "must be in heap.");
224 assert(from_obj->forward_safe_klass()->is_objArray_klass(), "must be obj array");
225 assert(from_obj->is_forwarded(), "must be forwarded");
226
227 oop to_obj = from_obj->forwardee();
228 assert(from_obj != to_obj, "should not be chunking self-forwarded objects");
229 assert(to_obj->is_objArray(), "must be obj array");
230 objArrayOop to_array = objArrayOop(to_obj);
231
232 PartialArrayTaskStepper::Step step
233 = _partial_array_stepper.next(objArrayOop(from_obj),
234 to_array,
235 _partial_objarray_chunk_size);
236 for (uint i = 0; i < step._ncreate; ++i) {
237 push_on_queue(ScannerTask(PartialArrayScanTask(from_obj)));
238 }
239
240 G1HeapRegionAttr dest_attr = _g1h->region_attr(to_array);
241 G1SkipCardEnqueueSetter x(&_scanner, dest_attr.is_new_survivor());
242 // Process claimed task. The length of to_array is not correct, but
243 // fortunately the iteration ignores the length field and just relies
244 // on start/end.
245 to_array->oop_iterate_range(&_scanner,
246 step._index,
247 step._index + _partial_objarray_chunk_size);
248 }
249
250 MAYBE_INLINE_EVACUATION
251 void G1ParScanThreadState::start_partial_objarray(G1HeapRegionAttr dest_attr,
252 oop from_obj,
253 oop to_obj) {
254 assert(from_obj->forward_safe_klass()->is_objArray_klass(), "precondition");
255 assert(from_obj->is_forwarded(), "precondition");
256 assert(from_obj->forwardee() == to_obj, "precondition");
257 assert(from_obj != to_obj, "should not be scanning self-forwarded objects");
258 assert(to_obj->is_objArray(), "precondition");
259
260 objArrayOop to_array = objArrayOop(to_obj);
261
262 PartialArrayTaskStepper::Step step
263 = _partial_array_stepper.start(objArrayOop(from_obj),
264 to_array,
265 _partial_objarray_chunk_size);
266
267 // Push any needed partial scan tasks. Pushed before processing the
268 // initial chunk to allow other workers to steal while we're processing.
269 for (uint i = 0; i < step._ncreate; ++i) {
270 push_on_queue(ScannerTask(PartialArrayScanTask(from_obj)));
271 }
272
273 // Skip the card enqueue iff the object (to_array) is in survivor region.
274 // However, HeapRegion::is_survivor() is too expensive here.
361 // no other space to try.
362 return nullptr;
363 }
364 }
365
366 G1HeapRegionAttr G1ParScanThreadState::next_region_attr(G1HeapRegionAttr const region_attr, markWord const m, uint& age) {
367 assert(region_attr.is_young() || region_attr.is_old(), "must be either Young or Old");
368
369 if (region_attr.is_young()) {
370 age = !m.has_displaced_mark_helper() ? m.age()
371 : m.displaced_mark_helper().age();
372 if (age < _tenuring_threshold) {
373 return region_attr;
374 }
375 }
376 // young-to-old (promotion) or old-to-old; destination is old in both cases.
377 return G1HeapRegionAttr::Old;
378 }
379
380 void G1ParScanThreadState::report_promotion_event(G1HeapRegionAttr const dest_attr,
381 Klass* klass, size_t word_sz, uint age,
382 HeapWord * const obj_ptr, uint node_index) const {
383 PLAB* alloc_buf = _plab_allocator->alloc_buffer(dest_attr, node_index);
384 if (alloc_buf->contains(obj_ptr)) {
385 _g1h->gc_tracer_stw()->report_promotion_in_new_plab_event(klass, word_sz * HeapWordSize, age,
386 dest_attr.type() == G1HeapRegionAttr::Old,
387 alloc_buf->word_sz() * HeapWordSize);
388 } else {
389 _g1h->gc_tracer_stw()->report_promotion_outside_plab_event(klass, word_sz * HeapWordSize, age,
390 dest_attr.type() == G1HeapRegionAttr::Old);
391 }
392 }
393
394 NOINLINE
395 HeapWord* G1ParScanThreadState::allocate_copy_slow(G1HeapRegionAttr* dest_attr,
396 Klass* klass,
397 size_t word_sz,
398 uint age,
399 uint node_index) {
400 HeapWord* obj_ptr = nullptr;
401 // Try slow-path allocation unless we're allocating old and old is already full.
402 if (!(dest_attr->is_old() && _old_gen_is_full)) {
403 bool plab_refill_failed = false;
404 obj_ptr = _plab_allocator->allocate_direct_or_new_plab(*dest_attr,
405 word_sz,
406 &plab_refill_failed,
407 node_index);
408 if (obj_ptr == nullptr) {
409 obj_ptr = allocate_in_next_plab(dest_attr,
410 word_sz,
411 plab_refill_failed,
412 node_index);
413 }
414 }
415 if (obj_ptr != nullptr) {
416 update_numa_stats(node_index);
417 if (_g1h->gc_tracer_stw()->should_report_promotion_events()) {
418 // The events are checked individually as part of the actual commit
419 report_promotion_event(*dest_attr, klass, word_sz, age, obj_ptr, node_index);
420 }
421 }
422 return obj_ptr;
423 }
424
425 #if EVAC_FAILURE_INJECTOR
426 bool G1ParScanThreadState::inject_evacuation_failure(uint region_idx) {
427 return _g1h->evac_failure_injector()->evacuation_should_fail(_evac_failure_inject_counter, region_idx);
428 }
429 #endif
430
431 NOINLINE
432 void G1ParScanThreadState::undo_allocation(G1HeapRegionAttr dest_attr,
433 HeapWord* obj_ptr,
434 size_t word_sz,
435 uint node_index) {
436 _plab_allocator->undo_allocation(dest_attr, obj_ptr, word_sz, node_index);
437 }
438
439 void G1ParScanThreadState::update_bot_after_copying(oop obj, size_t word_sz) {
440 HeapWord* obj_start = cast_from_oop<HeapWord*>(obj);
441 HeapRegion* region = _g1h->heap_region_containing(obj_start);
442 region->update_bot_for_obj(obj_start, word_sz);
443 }
444
445 // Private inline function, for direct internal use and providing the
446 // implementation of the public not-inline function.
447 MAYBE_INLINE_EVACUATION
448 oop G1ParScanThreadState::do_copy_to_survivor_space(G1HeapRegionAttr const region_attr,
449 oop const old,
450 markWord const old_mark) {
451 assert(region_attr.is_in_cset(),
452 "Unexpected region attr type: %s", region_attr.get_type_str());
453
454 // Get the klass once. We'll need it again later, and this avoids
455 // re-decoding when it's compressed.
456 // NOTE: With compact headers, it is not safe to load the Klass* from o, because
457 // that would access the mark-word, and the mark-word might change at any time by
458 // concurrent promotion. The promoted mark-word would point to the forwardee, which
459 // may not yet have completed copying. Therefore we must load the Klass* from
460 // the mark-word that we have already loaded. This is safe, because we have checked
461 // that this is not yet forwarded in the caller.
462 Klass* klass = old->forward_safe_klass(old_mark);
463 const size_t word_sz = old->size_given_klass(klass);
464
465 uint age = 0;
466 G1HeapRegionAttr dest_attr = next_region_attr(region_attr, old_mark, age);
467 HeapRegion* const from_region = _g1h->heap_region_containing(old);
468 uint node_index = from_region->node_index();
469
470 HeapWord* obj_ptr = _plab_allocator->plab_allocate(dest_attr, word_sz, node_index);
471
472 // PLAB allocations should succeed most of the time, so we'll
473 // normally check against null once and that's it.
474 if (obj_ptr == nullptr) {
475 obj_ptr = allocate_copy_slow(&dest_attr, klass, word_sz, age, node_index);
476 if (obj_ptr == nullptr) {
477 // This will either forward-to-self, or detect that someone else has
478 // installed a forwarding pointer.
479 return handle_evacuation_failure_par(old, old_mark, word_sz);
480 }
481 }
482
483 assert(obj_ptr != nullptr, "when we get here, allocation should have succeeded");
484 assert(_g1h->is_in_reserved(obj_ptr), "Allocated memory should be in the heap");
485
486 // Should this evacuation fail?
487 if (inject_evacuation_failure(from_region->hrm_index())) {
488 // Doing this after all the allocation attempts also tests the
489 // undo_allocation() method too.
490 undo_allocation(dest_attr, obj_ptr, word_sz, node_index);
491 return handle_evacuation_failure_par(old, old_mark, word_sz);
492 }
493
494 // We're going to allocate linearly, so might as well prefetch ahead.
495 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
609 delete pss;
610 _states[worker_id] = nullptr;
611 }
612 _flushed = true;
613 }
614
615 void G1ParScanThreadStateSet::record_unused_optional_region(HeapRegion* hr) {
616 for (uint worker_index = 0; worker_index < _num_workers; ++worker_index) {
617 G1ParScanThreadState* pss = _states[worker_index];
618 assert(pss != nullptr, "must be initialized");
619
620 size_t used_memory = pss->oops_into_optional_region(hr)->used_memory();
621 _g1h->phase_times()->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanHR, worker_index, used_memory, G1GCPhaseTimes::ScanHRUsedMemory);
622 }
623 }
624
625 NOINLINE
626 oop G1ParScanThreadState::handle_evacuation_failure_par(oop old, markWord m, size_t word_sz) {
627 assert(_g1h->is_in_cset(old), "Object " PTR_FORMAT " should be in the CSet", p2i(old));
628
629 oop forward_ptr = old->forward_to_self_atomic(m, memory_order_relaxed);
630 if (forward_ptr == nullptr) {
631 // Forward-to-self succeeded. We are the "owner" of the object.
632 HeapRegion* r = _g1h->heap_region_containing(old);
633
634 if (_evac_failure_regions->record(r->hrm_index())) {
635 _g1h->hr_printer()->evac_failure(r);
636 }
637
638 // Mark the failing object in the marking bitmap and later use the bitmap to handle
639 // evacuation failure recovery.
640 _g1h->mark_evac_failure_object(_worker_id, old, word_sz);
641
642 _preserved_marks->push_if_necessary(old, m);
643
644 ContinuationGCSupport::transform_stack_chunk(old);
645
646 _evacuation_failed_info.register_copy_failure(word_sz);
647
648 // For iterating objects that failed evacuation currently we can reuse the
649 // existing closure to scan evacuated objects because:
|