1 /*
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   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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   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
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  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
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  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  * @modules java.base/sun.misc
  32  *          java.management
  33  */
  34 
  35 import java.util.regex.Pattern;
  36 import java.util.regex.Matcher;
  37 import java.util.LinkedList;
  38 
  39 import jdk.test.lib.OutputAnalyzer;
  40 import jdk.test.lib.ProcessTools;
  41 import jdk.test.lib.Asserts;
  42 
  43 class ReclaimRegionFast {
  44     public static final int M = 1024*1024;
  45 
  46     public static LinkedList<Object> garbageList = new LinkedList<Object>();
  47 
  48     public static void genGarbage() {
  49         for (int i = 0; i < 32*1024; i++) {
  50             garbageList.add(new int[100]);
  51         }
  52         garbageList.clear();
  53     }
  54 
  55     // A large object referenced by a static.
  56     static int[] filler = new int[10 * M];
  57 
  58     public static void main(String[] args) {
  59 
  60         int[] large = new int[M];
  61 
  62         Object ref_from_stack = large;
  63 
  64         for (int i = 0; i < 100; i++) {
  65             // A large object that will be reclaimed eagerly.
  66             large = new int[6*M];
  67             genGarbage();
  68             // Make sure that the compiler cannot completely remove
  69             // the allocation of the large object until here.
  70             System.out.println(large);
  71         }
  72 
  73         // Keep the reference to the first object alive.
  74         System.out.println(ref_from_stack);
  75     }
  76 }
  77 
  78 public class TestEagerReclaimHumongousRegions {
  79     public static void main(String[] args) throws Exception {
  80         ProcessBuilder pb = ProcessTools.createJavaProcessBuilder(
  81             "-XX:+UseG1GC",
  82             "-Xms128M",
  83             "-Xmx128M",
  84             "-Xmn16M",
  85             "-XX:+PrintGC",
  86             ReclaimRegionFast.class.getName());
  87 
  88         Pattern p = Pattern.compile("Full GC");
  89 
  90         OutputAnalyzer output = new OutputAnalyzer(pb.start());
  91 
  92         int found = 0;
  93         Matcher m = p.matcher(output.getStdout());
  94         while (m.find()) { found++; }
  95         System.out.println("Issued " + found + " Full GCs");
  96         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");
  97 
  98         output.shouldHaveExitValue(0);
  99     }
 100 }
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