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 }