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 /*

  * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.

  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

  *

  * This code is free software; you can redistribute it and/or modify it

  * under the terms of the GNU General Public License version 2 only, as

  * published by the Free Software Foundation.

  *

  * This code is distributed in the hope that it will be useful, but WITHOUT

  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

  * version 2 for more details (a copy is included in the LICENSE file that

  * accompanied this code).

  *

  * You should have received a copy of the GNU General Public License version

  * 2 along with this work; if not, write to the Free Software Foundation,

  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

  *

  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

  * or visit www.oracle.com if you need additional information or have any

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  */

 /*

  * @test TestEagerReclaimHumongousRegionsWithRefs

  * @bug 8048179

  * @summary Test to make sure that eager reclaim of humongous objects that have previously

  * been referenced by other old gen regions work. We simply try to fill

  * up the heap with humongous objects and create a remembered set entry from an object by

  * referencing that we know is in the old gen. After changing this reference, the object

  * should still be eagerly reclaimable to avoid Full GC.

  * @key gc

  * @library /testlibrary

  */

 import java.util.regex.Pattern;

 import java.util.regex.Matcher;

 import java.util.LinkedList;

 import com.oracle.java.testlibrary.OutputAnalyzer;

 import com.oracle.java.testlibrary.ProcessTools;

 import static com.oracle.java.testlibrary.Asserts.*;

 class RefHolder {

   Object ref;

 }

 class ReclaimRegionFast {

     public static final int M = 1024*1024;

     public static LinkedList<Object> garbageList = new LinkedList<Object>();

     public static void genGarbage() {

         for (int i = 0; i < 32*1024; i++) {

             garbageList.add(new int[100]);

         }

         garbageList.clear();

     }

     // A large object referenced by a static.

     static int[] filler = new int[10 * M];

     // Old gen object referencing the large object, generating remembered

     // set entries.

     static RefHolder fromOld = new RefHolder();

     public static void main(String[] args) {

         int[] large = new int[M];

         Object ref_from_stack = large;

         for (int i = 0; i < 100; i++) {

             // A large object that will be reclaimed eagerly.

             large = new int[6*M];

             fromOld.ref = large;

             genGarbage();

         }

         // Keep the reference to the first object alive.

         System.out.println(ref_from_stack);

     }

 }

 public class TestEagerReclaimHumongousRegionsWithRefs {

     public static void main(String[] args) throws Exception {

         ProcessBuilder pb = ProcessTools.createJavaProcessBuilder(

             "-XX:+UseG1GC",

             "-Xms128M",

             "-Xmx128M",

             "-Xmn16M",

             "-XX:+PrintGC",

             ReclaimRegionFast.class.getName());

         Pattern p = Pattern.compile("Full GC");

         OutputAnalyzer output = new OutputAnalyzer(pb.start());

         int found = 0;

         Matcher m = p.matcher(output.getStdout());

         while (m.find()) {

             found++;

         }

         System.out.println("Issued " + found + " Full GCs");

         assertLessThan(found, 10, "Found that " + found + " Full GCs were issued. This is larger than the bound. Eager reclaim of objects once referenced from old gen seems to not work at all");

         output.shouldHaveExitValue(0);

     }

 }