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comparison test/gc/g1/TestEagerReclaimHumongousRegions.java @ 20296:a3953c777565

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8027959: Early reclamation of large objects in G1 Summary: Try to reclaim humongous objects at every young collection after doing a conservative estimate of its liveness. Reviewed-by: brutisso, mgerdin
author tschatzl
date Wed, 23 Jul 2014 09:03:32 +0200
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20295:3f2894c5052e 20296:a3953c777565
1 /*
2 * Copyright (c) 2014, 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 * @test TestEagerReclaimHumongousRegions
26 * @bug 8027959
27 * @summary Test to make sure that eager reclaim of humongous objects work. We simply try to fill
28 * up the heap with humongous objects that should be eagerly reclaimable to avoid Full GC.
29 * @key gc
30 * @library /testlibrary
31 */
32
33 import java.util.regex.Pattern;
34 import java.util.regex.Matcher;
35 import java.util.LinkedList;
36
37 import com.oracle.java.testlibrary.OutputAnalyzer;
38 import com.oracle.java.testlibrary.ProcessTools;
39 import com.oracle.java.testlibrary.Asserts;
40
41 class ReclaimRegionFast {
42 public static final int M = 1024*1024;
43
44 public static LinkedList<Object> garbageList = new LinkedList<Object>();
45
46 public static void genGarbage() {
47 for (int i = 0; i < 32*1024; i++) {
48 garbageList.add(new int[100]);
49 }
50 garbageList.clear();
51 }
52
53 // A large object referenced by a static.
54 static int[] filler = new int[10 * M];
55
56 public static void main(String[] args) {
57
58 int[] large = new int[M];
59
60 Object ref_from_stack = large;
61
62 for (int i = 0; i < 100; i++) {
63 // A large object that will be reclaimed eagerly.
64 large = new int[6*M];
65 genGarbage();
66 // Make sure that the compiler cannot completely remove
67 // the allocation of the large object until here.
68 System.out.println(large);
69 }
70
71 // Keep the reference to the first object alive.
72 System.out.println(ref_from_stack);
73 }
74 }
75
76 public class TestEagerReclaimHumongousRegions {
77 public static void main(String[] args) throws Exception {
78 ProcessBuilder pb = ProcessTools.createJavaProcessBuilder(
79 "-XX:+UseG1GC",
80 "-Xms128M",
81 "-Xmx128M",
82 "-Xmn16M",
83 "-XX:+PrintGC",
84 ReclaimRegionFast.class.getName());
85
86 Pattern p = Pattern.compile("Full GC");
87
88 OutputAnalyzer output = new OutputAnalyzer(pb.start());
89
90 int found = 0;
91 Matcher m = p.matcher(output.getStdout());
92 while (m.find()) { found++; }
93 System.out.println("Issued " + found + " Full GCs");
94 Asserts.assertLT(found, 10, "Found that " + found + " Full GCs were issued. This is larger than the bound. Eager reclaim seems to not work at all");
95
96 output.shouldHaveExitValue(0);
97 }
98 }