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 }