src/hotspot/share/gc/g1/g1EvacFailure.cpp - platform/libcore - Git at Google

 /*
  * Copyright (c) 2012, 2020, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  *
  */

 #include "precompiled.hpp"
 #include "gc/g1/g1CollectedHeap.inline.hpp"
 #include "gc/g1/g1CollectorState.hpp"
 #include "gc/g1/g1ConcurrentMark.inline.hpp"
 #include "gc/g1/g1EvacFailure.hpp"
 #include "gc/g1/g1HeapVerifier.hpp"
 #include "gc/g1/g1OopClosures.inline.hpp"
 #include "gc/g1/g1RedirtyCardsQueue.hpp"
 #include "gc/g1/heapRegion.hpp"
 #include "gc/g1/heapRegionRemSet.hpp"
 #include "gc/shared/preservedMarks.inline.hpp"
 #include "oops/access.inline.hpp"
 #include "oops/compressedOops.inline.hpp"
 #include "oops/oop.inline.hpp"

 class UpdateLogBuffersDeferred : public BasicOopIterateClosure {
 private:
   G1CollectedHeap* _g1h;
   G1RedirtyCardsQueue* _rdcq;
   G1CardTable*    _ct;

   // Remember the last enqueued card to avoid enqueuing the same card over and over;
   // since we only ever handle a card once, this is sufficient.
   size_t _last_enqueued_card;

 public:
   UpdateLogBuffersDeferred(G1RedirtyCardsQueue* rdcq) :
     _g1h(G1CollectedHeap::heap()), _rdcq(rdcq), _ct(_g1h->card_table()), _last_enqueued_card(SIZE_MAX) {}

   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
   virtual void do_oop(      oop* p) { do_oop_work(p); }
   template <class T> void do_oop_work(T* p) {
     assert(_g1h->heap_region_containing(p)->is_in_reserved(p), "paranoia");
     assert(!_g1h->heap_region_containing(p)->is_survivor(), "Unexpected evac failure in survivor region");

     T const o = RawAccess<>::oop_load(p);
     if (CompressedOops::is_null(o)) {
       return;
     }

     if (HeapRegion::is_in_same_region(p, CompressedOops::decode(o))) {
       return;
     }
     size_t card_index = _ct->index_for(p);
     if (card_index != _last_enqueued_card) {
       _rdcq->enqueue(_ct->byte_for_index(card_index));
       _last_enqueued_card = card_index;
     }
   }
 };

 class RemoveSelfForwardPtrObjClosure: public ObjectClosure {
   G1CollectedHeap* _g1h;
   G1ConcurrentMark* _cm;
   HeapRegion* _hr;
   size_t _marked_bytes;
   UpdateLogBuffersDeferred* _log_buffer_cl;
   bool _during_concurrent_start;
   uint _worker_id;
   HeapWord* _last_forwarded_object_end;

 public:
   RemoveSelfForwardPtrObjClosure(HeapRegion* hr,
                                  UpdateLogBuffersDeferred* log_buffer_cl,
                                  bool during_concurrent_start,
                                  uint worker_id) :
     _g1h(G1CollectedHeap::heap()),
     _cm(_g1h->concurrent_mark()),
     _hr(hr),
     _marked_bytes(0),
     _log_buffer_cl(log_buffer_cl),
     _during_concurrent_start(during_concurrent_start),
     _worker_id(worker_id),
     _last_forwarded_object_end(hr->bottom()) { }

   size_t marked_bytes() { return _marked_bytes; }

   // Iterate over the live objects in the region to find self-forwarded objects
   // that need to be kept live. We need to update the remembered sets of these
   // objects. Further update the BOT and marks.
   // We can coalesce and overwrite the remaining heap contents with dummy objects
   // as they have either been dead or evacuated (which are unreferenced now, i.e.
   // dead too) already.
   void do_object(oop obj) {
     HeapWord* obj_addr = cast_from_oop<HeapWord*>(obj);
     assert(_hr->is_in(obj_addr), "sanity");

     if (obj->is_forwarded() && obj->forwardee() == obj) {
       // The object failed to move.

       zap_dead_objects(_last_forwarded_object_end, obj_addr);
       // We consider all objects that we find self-forwarded to be
       // live. What we'll do is that we'll update the prev marking
       // info so that they are all under PTAMS and explicitly marked.
       if (!_cm->is_marked_in_prev_bitmap(obj)) {
         _cm->mark_in_prev_bitmap(obj);
       }
       if (_during_concurrent_start) {
         // For the next marking info we'll only mark the
         // self-forwarded objects explicitly if we are during
         // concurrent start (since, normally, we only mark objects pointed
         // to by roots if we succeed in copying them). By marking all
         // self-forwarded objects we ensure that we mark any that are
         // still pointed to be roots. During concurrent marking, and
         // after concurrent start, we don't need to mark any objects
         // explicitly and all objects in the CSet are considered
         // (implicitly) live. So, we won't mark them explicitly and
         // we'll leave them over NTAMS.
         _cm->mark_in_next_bitmap(_worker_id, _hr, obj);
       }
       size_t obj_size = obj->size();

       _marked_bytes += (obj_size * HeapWordSize);
       PreservedMarks::init_forwarded_mark(obj);

       // While we were processing RSet buffers during the collection,
       // we actually didn't scan any cards on the collection set,
       // since we didn't want to update remembered sets with entries
       // that point into the collection set, given that live objects
       // from the collection set are about to move and such entries
       // will be stale very soon.
       // This change also dealt with a reliability issue which
       // involved scanning a card in the collection set and coming
       // across an array that was being chunked and looking malformed.
       // The problem is that, if evacuation fails, we might have
       // remembered set entries missing given that we skipped cards on
       // the collection set. So, we'll recreate such entries now.
       obj->oop_iterate(_log_buffer_cl);

       HeapWord* obj_end = obj_addr + obj_size;
       _last_forwarded_object_end = obj_end;
       _hr->cross_threshold(obj_addr, obj_end);
     }
   }

   // Fill the memory area from start to end with filler objects, and update the BOT
   // and the mark bitmap accordingly.
   void zap_dead_objects(HeapWord* start, HeapWord* end) {
     if (start == end) {
       return;
     }

     size_t gap_size = pointer_delta(end, start);
     MemRegion mr(start, gap_size);
     if (gap_size >= CollectedHeap::min_fill_size()) {
       CollectedHeap::fill_with_objects(start, gap_size);

       HeapWord* end_first_obj = start + ((oop)start)->size();
       _hr->cross_threshold(start, end_first_obj);
       // Fill_with_objects() may have created multiple (i.e. two)
       // objects, as the max_fill_size() is half a region.
       // After updating the BOT for the first object, also update the
       // BOT for the second object to make the BOT complete.
       if (end_first_obj != end) {
         _hr->cross_threshold(end_first_obj, end);
 #ifdef ASSERT
         size_t size_second_obj = ((oop)end_first_obj)->size();
         HeapWord* end_of_second_obj = end_first_obj + size_second_obj;
         assert(end == end_of_second_obj,
                "More than two objects were used to fill the area from " PTR_FORMAT " to " PTR_FORMAT ", "
                "second objects size " SIZE_FORMAT " ends at " PTR_FORMAT,
                p2i(start), p2i(end), size_second_obj, p2i(end_of_second_obj));
 #endif
       }
     }
     _cm->clear_range_in_prev_bitmap(mr);
   }

   void zap_remainder() {
     zap_dead_objects(_last_forwarded_object_end, _hr->top());
   }
 };

 class RemoveSelfForwardPtrHRClosure: public HeapRegionClosure {
   G1CollectedHeap* _g1h;
   uint _worker_id;

   G1RedirtyCardsLocalQueueSet _rdc_local_qset;
   G1RedirtyCardsQueue _rdcq;
   UpdateLogBuffersDeferred _log_buffer_cl;

 public:
   RemoveSelfForwardPtrHRClosure(G1RedirtyCardsQueueSet* rdcqs, uint worker_id) :
     _g1h(G1CollectedHeap::heap()),
     _worker_id(worker_id),
     _rdc_local_qset(rdcqs),
     _rdcq(&_rdc_local_qset),
     _log_buffer_cl(&_rdcq) {
   }

   ~RemoveSelfForwardPtrHRClosure() {
     _rdcq.flush();
     _rdc_local_qset.flush();
   }

   size_t remove_self_forward_ptr_by_walking_hr(HeapRegion* hr,
                                                bool during_concurrent_start) {
     RemoveSelfForwardPtrObjClosure rspc(hr,
                                         &_log_buffer_cl,
                                         during_concurrent_start,
                                         _worker_id);
     hr->object_iterate(&rspc);
     // Need to zap the remainder area of the processed region.
     rspc.zap_remainder();

     return rspc.marked_bytes();
   }

   bool do_heap_region(HeapRegion *hr) {
     assert(!hr->is_pinned(), "Unexpected pinned region at index %u", hr->hrm_index());
     assert(hr->in_collection_set(), "bad CS");

     if (hr->evacuation_failed()) {
       hr->clear_index_in_opt_cset();

       bool during_concurrent_start = _g1h->collector_state()->in_concurrent_start_gc();
       bool during_concurrent_mark = _g1h->collector_state()->mark_or_rebuild_in_progress();

       hr->note_self_forwarding_removal_start(during_concurrent_start,
                                              during_concurrent_mark);
       _g1h->verifier()->check_bitmaps("Self-Forwarding Ptr Removal", hr);

       hr->reset_bot();

       size_t live_bytes = remove_self_forward_ptr_by_walking_hr(hr, during_concurrent_start);

       hr->rem_set()->clean_strong_code_roots(hr);
       hr->rem_set()->clear_locked(true);

       hr->note_self_forwarding_removal_end(live_bytes);
     }
     return false;
   }
 };

 G1ParRemoveSelfForwardPtrsTask::G1ParRemoveSelfForwardPtrsTask(G1RedirtyCardsQueueSet* rdcqs) :
   AbstractGangTask("G1 Remove Self-forwarding Pointers"),
   _g1h(G1CollectedHeap::heap()),
   _rdcqs(rdcqs),
   _hrclaimer(_g1h->workers()->active_workers()) { }

 void G1ParRemoveSelfForwardPtrsTask::work(uint worker_id) {
   RemoveSelfForwardPtrHRClosure rsfp_cl(_rdcqs, worker_id);

   // We need to check all collection set regions whether they need self forward
   // removals, not only the last collection set increment. The reason is that
   // reference processing (e.g. finalizers) can make it necessary to resurrect an
   // otherwise unreachable object at the very end of the collection. That object
   // might cause an evacuation failure in any region in the collection set.
   _g1h->collection_set_par_iterate_all(&rsfp_cl, &_hrclaimer, worker_id);
 }
	/*
	* Copyright (c) 2012, 2020, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation.
	*
	* This code is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*
	*/

	#include "precompiled.hpp"
	#include "gc/g1/g1CollectedHeap.inline.hpp"
	#include "gc/g1/g1CollectorState.hpp"
	#include "gc/g1/g1ConcurrentMark.inline.hpp"
	#include "gc/g1/g1EvacFailure.hpp"
	#include "gc/g1/g1HeapVerifier.hpp"
	#include "gc/g1/g1OopClosures.inline.hpp"
	#include "gc/g1/g1RedirtyCardsQueue.hpp"
	#include "gc/g1/heapRegion.hpp"
	#include "gc/g1/heapRegionRemSet.hpp"
	#include "gc/shared/preservedMarks.inline.hpp"
	#include "oops/access.inline.hpp"
	#include "oops/compressedOops.inline.hpp"
	#include "oops/oop.inline.hpp"

	class UpdateLogBuffersDeferred : public BasicOopIterateClosure {
	private:
	G1CollectedHeap* _g1h;
	G1RedirtyCardsQueue* _rdcq;
	G1CardTable* _ct;

	// Remember the last enqueued card to avoid enqueuing the same card over and over;
	// since we only ever handle a card once, this is sufficient.
	size_t _last_enqueued_card;

	public:
	UpdateLogBuffersDeferred(G1RedirtyCardsQueue* rdcq) :
	_g1h(G1CollectedHeap::heap()), _rdcq(rdcq), _ct(_g1h->card_table()), _last_enqueued_card(SIZE_MAX) {}

	virtual void do_oop(narrowOop* p) { do_oop_work(p); }
	virtual void do_oop( oop* p) { do_oop_work(p); }
	template <class T> void do_oop_work(T* p) {
	assert(_g1h->heap_region_containing(p)->is_in_reserved(p), "paranoia");
	assert(!_g1h->heap_region_containing(p)->is_survivor(), "Unexpected evac failure in survivor region");

	T const o = RawAccess<>::oop_load(p);
	if (CompressedOops::is_null(o)) {
	return;
	}

	if (HeapRegion::is_in_same_region(p, CompressedOops::decode(o))) {
	return;
	}
	size_t card_index = _ct->index_for(p);
	if (card_index != _last_enqueued_card) {
	_rdcq->enqueue(_ct->byte_for_index(card_index));
	_last_enqueued_card = card_index;
	}
	}
	};

	class RemoveSelfForwardPtrObjClosure: public ObjectClosure {
	G1CollectedHeap* _g1h;
	G1ConcurrentMark* _cm;
	HeapRegion* _hr;
	size_t _marked_bytes;
	UpdateLogBuffersDeferred* _log_buffer_cl;
	bool _during_concurrent_start;
	uint _worker_id;
	HeapWord* _last_forwarded_object_end;

	public:
	RemoveSelfForwardPtrObjClosure(HeapRegion* hr,
	UpdateLogBuffersDeferred* log_buffer_cl,
	bool during_concurrent_start,
	uint worker_id) :
	_g1h(G1CollectedHeap::heap()),
	_cm(_g1h->concurrent_mark()),
	_hr(hr),
	_marked_bytes(0),
	_log_buffer_cl(log_buffer_cl),
	_during_concurrent_start(during_concurrent_start),
	_worker_id(worker_id),
	_last_forwarded_object_end(hr->bottom()) { }

	size_t marked_bytes() { return _marked_bytes; }

	// Iterate over the live objects in the region to find self-forwarded objects
	// that need to be kept live. We need to update the remembered sets of these
	// objects. Further update the BOT and marks.
	// We can coalesce and overwrite the remaining heap contents with dummy objects
	// as they have either been dead or evacuated (which are unreferenced now, i.e.
	// dead too) already.
	void do_object(oop obj) {
	HeapWord* obj_addr = cast_from_oop<HeapWord*>(obj);
	assert(_hr->is_in(obj_addr), "sanity");

	if (obj->is_forwarded() && obj->forwardee() == obj) {
	// The object failed to move.

	zap_dead_objects(_last_forwarded_object_end, obj_addr);
	// We consider all objects that we find self-forwarded to be
	// live. What we'll do is that we'll update the prev marking
	// info so that they are all under PTAMS and explicitly marked.
	if (!_cm->is_marked_in_prev_bitmap(obj)) {
	_cm->mark_in_prev_bitmap(obj);
	}
	if (_during_concurrent_start) {
	// For the next marking info we'll only mark the
	// self-forwarded objects explicitly if we are during
	// concurrent start (since, normally, we only mark objects pointed
	// to by roots if we succeed in copying them). By marking all
	// self-forwarded objects we ensure that we mark any that are
	// still pointed to be roots. During concurrent marking, and
	// after concurrent start, we don't need to mark any objects
	// explicitly and all objects in the CSet are considered
	// (implicitly) live. So, we won't mark them explicitly and
	// we'll leave them over NTAMS.
	_cm->mark_in_next_bitmap(_worker_id, _hr, obj);
	}
	size_t obj_size = obj->size();

	_marked_bytes += (obj_size * HeapWordSize);
	PreservedMarks::init_forwarded_mark(obj);

	// While we were processing RSet buffers during the collection,
	// we actually didn't scan any cards on the collection set,
	// since we didn't want to update remembered sets with entries
	// that point into the collection set, given that live objects
	// from the collection set are about to move and such entries
	// will be stale very soon.
	// This change also dealt with a reliability issue which
	// involved scanning a card in the collection set and coming
	// across an array that was being chunked and looking malformed.
	// The problem is that, if evacuation fails, we might have
	// remembered set entries missing given that we skipped cards on
	// the collection set. So, we'll recreate such entries now.
	obj->oop_iterate(_log_buffer_cl);

	HeapWord* obj_end = obj_addr + obj_size;
	_last_forwarded_object_end = obj_end;
	_hr->cross_threshold(obj_addr, obj_end);
	}
	}

	// Fill the memory area from start to end with filler objects, and update the BOT
	// and the mark bitmap accordingly.
	void zap_dead_objects(HeapWord* start, HeapWord* end) {
	if (start == end) {
	return;
	}

	size_t gap_size = pointer_delta(end, start);
	MemRegion mr(start, gap_size);
	if (gap_size >= CollectedHeap::min_fill_size()) {
	CollectedHeap::fill_with_objects(start, gap_size);

	HeapWord* end_first_obj = start + ((oop)start)->size();
	_hr->cross_threshold(start, end_first_obj);
	// Fill_with_objects() may have created multiple (i.e. two)
	// objects, as the max_fill_size() is half a region.
	// After updating the BOT for the first object, also update the
	// BOT for the second object to make the BOT complete.
	if (end_first_obj != end) {
	_hr->cross_threshold(end_first_obj, end);
	#ifdef ASSERT
	size_t size_second_obj = ((oop)end_first_obj)->size();
	HeapWord* end_of_second_obj = end_first_obj + size_second_obj;
	assert(end == end_of_second_obj,
	"More than two objects were used to fill the area from " PTR_FORMAT " to " PTR_FORMAT ", "
	"second objects size " SIZE_FORMAT " ends at " PTR_FORMAT,
	p2i(start), p2i(end), size_second_obj, p2i(end_of_second_obj));
	#endif
	}
	}
	_cm->clear_range_in_prev_bitmap(mr);
	}

	void zap_remainder() {
	zap_dead_objects(_last_forwarded_object_end, _hr->top());
	}
	};

	class RemoveSelfForwardPtrHRClosure: public HeapRegionClosure {
	G1CollectedHeap* _g1h;
	uint _worker_id;

	G1RedirtyCardsLocalQueueSet _rdc_local_qset;
	G1RedirtyCardsQueue _rdcq;
	UpdateLogBuffersDeferred _log_buffer_cl;

	public:
	RemoveSelfForwardPtrHRClosure(G1RedirtyCardsQueueSet* rdcqs, uint worker_id) :
	_g1h(G1CollectedHeap::heap()),
	_worker_id(worker_id),
	_rdc_local_qset(rdcqs),
	_rdcq(&_rdc_local_qset),
	_log_buffer_cl(&_rdcq) {
	}

	~RemoveSelfForwardPtrHRClosure() {
	_rdcq.flush();
	_rdc_local_qset.flush();
	}

	size_t remove_self_forward_ptr_by_walking_hr(HeapRegion* hr,
	bool during_concurrent_start) {
	RemoveSelfForwardPtrObjClosure rspc(hr,
	&_log_buffer_cl,
	during_concurrent_start,
	_worker_id);
	hr->object_iterate(&rspc);
	// Need to zap the remainder area of the processed region.
	rspc.zap_remainder();

	return rspc.marked_bytes();
	}

	bool do_heap_region(HeapRegion *hr) {
	assert(!hr->is_pinned(), "Unexpected pinned region at index %u", hr->hrm_index());
	assert(hr->in_collection_set(), "bad CS");

	if (hr->evacuation_failed()) {
	hr->clear_index_in_opt_cset();

	bool during_concurrent_start = _g1h->collector_state()->in_concurrent_start_gc();
	bool during_concurrent_mark = _g1h->collector_state()->mark_or_rebuild_in_progress();

	hr->note_self_forwarding_removal_start(during_concurrent_start,
	during_concurrent_mark);
	_g1h->verifier()->check_bitmaps("Self-Forwarding Ptr Removal", hr);

	hr->reset_bot();

	size_t live_bytes = remove_self_forward_ptr_by_walking_hr(hr, during_concurrent_start);

	hr->rem_set()->clean_strong_code_roots(hr);
	hr->rem_set()->clear_locked(true);

	hr->note_self_forwarding_removal_end(live_bytes);
	}
	return false;
	}
	};

	G1ParRemoveSelfForwardPtrsTask::G1ParRemoveSelfForwardPtrsTask(G1RedirtyCardsQueueSet* rdcqs) :
	AbstractGangTask("G1 Remove Self-forwarding Pointers"),
	_g1h(G1CollectedHeap::heap()),
	_rdcqs(rdcqs),
	_hrclaimer(_g1h->workers()->active_workers()) { }

	void G1ParRemoveSelfForwardPtrsTask::work(uint worker_id) {
	RemoveSelfForwardPtrHRClosure rsfp_cl(_rdcqs, worker_id);

	// We need to check all collection set regions whether they need self forward
	// removals, not only the last collection set increment. The reason is that
	// reference processing (e.g. finalizers) can make it necessary to resurrect an
	// otherwise unreachable object at the very end of the collection. That object
	// might cause an evacuation failure in any region in the collection set.
	_g1h->collection_set_par_iterate_all(&rsfp_cl, &_hrclaimer, worker_id);
	}