1 /*
2  * Copyright (c) 2015, 2019, 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 package gc;
25 
26 /*
27  * @test TestDisableExplicitGC
28  * @requires vm.opt.DisableExplicitGC == null
29  * @summary Verify GC behavior with DisableExplicitGC flag.
30  * @library /test/lib
31  * @modules java.base/jdk.internal.misc
32  * @modules jdk.management/com.sun.management.internal
33  * @run main/othervm                             -Xlog:gc=debug gc.TestDisableExplicitGC
34  * @run main/othervm/fail -XX:+DisableExplicitGC -Xlog:gc=debug gc.TestDisableExplicitGC
35  * @run main/othervm      -XX:-DisableExplicitGC -Xlog:gc=debug gc.TestDisableExplicitGC
36  */
37 import java.lang.management.GarbageCollectorMXBean;
38 import java.util.List;
39 import static jdk.test.lib.Asserts.*;
40 
41 public class TestDisableExplicitGC {
42 
main(String[] args)43     public static void main(String[] args) throws InterruptedException {
44         List<GarbageCollectorMXBean> list = java.lang.management.ManagementFactory.getGarbageCollectorMXBeans();
45         long collectionCountBefore = getCollectionCount(list);
46         System.gc();
47         long collectionCountAfter = getCollectionCount(list);
48         assertLT(collectionCountBefore, collectionCountAfter);
49     }
50 
getCollectionCount(List<GarbageCollectorMXBean> list)51     private static long getCollectionCount(List<GarbageCollectorMXBean> list) {
52         int collectionCount = 0;
53         for (GarbageCollectorMXBean gcMXBean : list) {
54             collectionCount += gcMXBean.getCollectionCount();
55         }
56         return collectionCount;
57     }
58 }
59