1 /*
2 * Copyright (c) 2014, 2015, Red Hat, Inc. and/or its affiliates.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation.
7 *
8 * This code is distributed in the hope that it will be useful, but WITHOUT
9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
11 * version 2 for more details (a copy is included in the LICENSE file that
12 * accompanied this code).
13 *
14 * You should have received a copy of the GNU General Public License version
15 * 2 along with this work; if not, write to the Free Software Foundation,
16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
17 *
18 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
19 * or visit www.oracle.com if you need additional information or have any
20 * questions.
21 *
22 */
23
24 #ifndef SHARE_VM_GC_SHENANDOAH_SHENANDOAHMARKCOMPACT_HPP
25 #define SHARE_VM_GC_SHENANDOAH_SHENANDOAHMARKCOMPACT_HPP
26
27 #include "gc_implementation/shared/gcTimer.hpp"
28 #include "gc_implementation/shenandoah/shenandoahHeap.hpp"
29 #include "gc_implementation/shenandoah/shenandoahHeapRegionSet.hpp"
30
31 class HeapWord;
32
33 /**
34 * This implements Full GC (e.g. when invoking System.gc()) using a mark-compact algorithm.
35 *
36 * Current implementation is parallel sliding Lisp-2-style algorithm, based on
37 * "Parallel Garbage Collection for Shared Memory Multiprocessors", by Christine Flood et al.
38 * http://people.csail.mit.edu/shanir/publications/dfsz2001.pdf
39 *
40 * It is implemented in four phases:
41 *
42 * 1. Mark all live objects of the heap by traversing objects starting at GC roots.
43 * 2. Calculate the new location of each live object. This is done by sequentially scanning
44 * the heap, keeping track of a next-location-pointer, which is then written to each
45 * object's fwdptr field.
46 * 3. Update all references. This is implemented by another scan of the heap, and updates
47 * all references in live objects by what's stored in the target object's fwdptr.
48 * 4. Compact the heap by copying all live objects to their new location.
49 *
50 * Parallelization is handled by assigning each GC worker the slice of the heap (the set of regions)
51 * where it does sliding compaction, without interfering with other threads.
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1 /*
2 * Copyright (c) 2014, 2018, Red Hat, Inc. All rights reserved.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation.
7 *
8 * This code is distributed in the hope that it will be useful, but WITHOUT
9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
11 * version 2 for more details (a copy is included in the LICENSE file that
12 * accompanied this code).
13 *
14 * You should have received a copy of the GNU General Public License version
15 * 2 along with this work; if not, write to the Free Software Foundation,
16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
17 *
18 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
19 * or visit www.oracle.com if you need additional information or have any
20 * questions.
21 *
22 */
23
24 #ifndef SHARE_VM_GC_SHENANDOAH_SHENANDOAHMARKCOMPACT_HPP
25 #define SHARE_VM_GC_SHENANDOAH_SHENANDOAHMARKCOMPACT_HPP
26
27 #include "gc_implementation/shared/gcTimer.hpp"
28 #include "gc_implementation/shenandoah/shenandoahHeap.hpp"
29 #include "gc_implementation/shenandoah/shenandoahHeapRegionSet.hpp"
30
31 /**
32 * This implements Full GC (e.g. when invoking System.gc()) using a mark-compact algorithm.
33 *
34 * Current implementation is parallel sliding Lisp-2-style algorithm, based on
35 * "Parallel Garbage Collection for Shared Memory Multiprocessors", by Christine Flood et al.
36 * http://people.csail.mit.edu/shanir/publications/dfsz2001.pdf
37 *
38 * It is implemented in four phases:
39 *
40 * 1. Mark all live objects of the heap by traversing objects starting at GC roots.
41 * 2. Calculate the new location of each live object. This is done by sequentially scanning
42 * the heap, keeping track of a next-location-pointer, which is then written to each
43 * object's fwdptr field.
44 * 3. Update all references. This is implemented by another scan of the heap, and updates
45 * all references in live objects by what's stored in the target object's fwdptr.
46 * 4. Compact the heap by copying all live objects to their new location.
47 *
48 * Parallelization is handled by assigning each GC worker the slice of the heap (the set of regions)
49 * where it does sliding compaction, without interfering with other threads.
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