1 /*
  2  * Copyright (c) 2017, 2021, Oracle and/or its affiliates. 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.
 18  *
 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
 21  * questions.
 22  *
 23  */
 24 
 25 #include "precompiled.hpp"
 26 #include "gc/g1/g1CollectedHeap.hpp"
 27 #include "gc/g1/g1ConcurrentMarkBitMap.inline.hpp"
 28 #include "gc/g1/g1FullCollector.hpp"
 29 #include "gc/g1/g1FullCollector.inline.hpp"
 30 #include "gc/g1/g1FullGCCompactionPoint.hpp"
 31 #include "gc/g1/g1FullGCCompactTask.hpp"
 32 #include "gc/g1/heapRegion.inline.hpp"
 33 #include "gc/shared/gcTraceTime.inline.hpp"
 34 #include "gc/shared/slidingForwarding.inline.hpp"
 35 #include "logging/log.hpp"
 36 #include "oops/oop.inline.hpp"
 37 #include "utilities/ticks.hpp"
 38 
 39 // Do work for all skip-compacting regions.
 40 class G1ResetSkipCompactingClosure : public HeapRegionClosure {
 41   G1FullCollector* _collector;
 42 
 43 public:
 44   G1ResetSkipCompactingClosure(G1FullCollector* collector) : _collector(collector) { }
 45 
 46   bool do_heap_region(HeapRegion* r) {
 47     uint region_index = r->hrm_index();
 48     // Only for skip-compaction regions; early return otherwise.
 49     if (!_collector->is_skip_compacting(region_index)) {
 50 
 51       return false;
 52     }
 53     assert(_collector->live_words(region_index) > _collector->scope()->region_compaction_threshold() ||
 54          !r->is_starts_humongous() ||
 55          _collector->mark_bitmap()->is_marked(cast_to_oop(r->bottom())),
 56          "must be, otherwise reclaimed earlier");
 57     r->reset_skip_compacting_after_full_gc();
 58     return false;
 59   }
 60 };
 61 
 62 template <bool ALT_FWD>
 63 size_t G1FullGCCompactTask::G1CompactRegionClosure<ALT_FWD>::apply(oop obj) {
 64   size_t size = obj->size();
 65   if (!SlidingForwarding::is_forwarded(obj)) {
 66     // Object not moving
 67     return size;
 68   }
 69 
 70   HeapWord* destination = cast_from_oop<HeapWord*>(SlidingForwarding::forwardee<ALT_FWD>(obj));
 71 
 72   // copy object and reinit its mark
 73   HeapWord* obj_addr = cast_from_oop<HeapWord*>(obj);
 74   assert(obj_addr != destination, "everything in this pass should be moving");
 75   Copy::aligned_conjoint_words(obj_addr, destination, size);
 76   cast_to_oop(destination)->init_mark();
 77   assert(cast_to_oop(destination)->klass() != NULL, "should have a class");
 78 
 79   return size;
 80 }
 81 
 82 void G1FullGCCompactTask::compact_region(HeapRegion* hr) {
 83   assert(!hr->is_pinned(), "Should be no pinned region in compaction queue");
 84   assert(!hr->is_humongous(), "Should be no humongous regions in compaction queue");
 85   if (UseAltGCForwarding) {
 86     G1CompactRegionClosure<true> compact(collector()->mark_bitmap());
 87     hr->apply_to_marked_objects(collector()->mark_bitmap(), &compact);
 88   } else {
 89     G1CompactRegionClosure<false> compact(collector()->mark_bitmap());
 90     hr->apply_to_marked_objects(collector()->mark_bitmap(), &compact);
 91   }
 92   // Clear the liveness information for this region if necessary i.e. if we actually look at it
 93   // for bitmap verification. Otherwise it is sufficient that we move the TAMS to bottom().
 94   if (G1VerifyBitmaps) {
 95     collector()->mark_bitmap()->clear_region(hr);
 96   }
 97   hr->reset_compacted_after_full_gc();
 98 }
 99 
100 void G1FullGCCompactTask::work(uint worker_id) {
101   Ticks start = Ticks::now();
102   GrowableArray<HeapRegion*>* compaction_queue = collector()->compaction_point(worker_id)->regions();
103   for (GrowableArrayIterator<HeapRegion*> it = compaction_queue->begin();
104        it != compaction_queue->end();
105        ++it) {
106     compact_region(*it);
107   }
108 
109   G1ResetSkipCompactingClosure hc(collector());
110   G1CollectedHeap::heap()->heap_region_par_iterate_from_worker_offset(&hc, &_claimer, worker_id);
111   log_task("Compaction task", worker_id, start);
112 }
113 
114 void G1FullGCCompactTask::serial_compaction() {
115   GCTraceTime(Debug, gc, phases) tm("Phase 4: Serial Compaction", collector()->scope()->timer());
116   GrowableArray<HeapRegion*>* compaction_queue = collector()->serial_compaction_point()->regions();
117   for (GrowableArrayIterator<HeapRegion*> it = compaction_queue->begin();
118        it != compaction_queue->end();
119        ++it) {
120     compact_region(*it);
121   }
122 }