Mercurial > jdk8-mips64-public > hotspot / file revision

 /*

  * 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

  * questions.

  */

 /**

  * @test TestHumongousShrinkHeap

  * @bug 8036025 8056043

  * @summary Verify that heap shrinks after GC in the presence of fragmentation due to humongous objects

  * @library /testlibrary

  * @run main/othervm -XX:MinHeapFreeRatio=10 -XX:MaxHeapFreeRatio=50 -XX:+UseG1GC -XX:G1HeapRegionSize=1M -verbose:gc TestHumongousShrinkHeap

  */

 import java.lang.management.ManagementFactory;

 import java.lang.management.MemoryUsage;

 import java.util.ArrayList;

 import java.util.List;

 import sun.management.ManagementFactoryHelper;

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

 public class TestHumongousShrinkHeap {

     public static final String MIN_FREE_RATIO_FLAG_NAME = "MinHeapFreeRatio";

     public static final String MAX_FREE_RATIO_FLAG_NAME = "MaxHeapFreeRatio";

     private static final ArrayList<ArrayList<byte[]>> garbage = new ArrayList<>();

     private static final int PAGE_SIZE = 1024 * 1024; // 1M

     private static final int PAGES_NUM = 5;

     public static void main(String[] args) {

         new TestHumongousShrinkHeap().test();

     }

     private final void test() {

         System.gc();

         MemoryUsagePrinter.printMemoryUsage("init");

         eat();

         MemoryUsagePrinter.printMemoryUsage("eaten");

         MemoryUsage muFull = ManagementFactory.getMemoryMXBean().getHeapMemoryUsage();

         free();

         MemoryUsagePrinter.printMemoryUsage("free");

         MemoryUsage muFree = ManagementFactory.getMemoryMXBean().getHeapMemoryUsage();

         assertLessThan(muFree.getCommitted(), muFull.getCommitted(), String.format(

                 "committed free heap size is not less than committed full heap size, heap hasn't been shrunk?%n"

                 + "%s = %s%n%s = %s",

                 MIN_FREE_RATIO_FLAG_NAME,

                 ManagementFactoryHelper.getDiagnosticMXBean().getVMOption(MIN_FREE_RATIO_FLAG_NAME).getValue(),

                 MAX_FREE_RATIO_FLAG_NAME,

                 ManagementFactoryHelper.getDiagnosticMXBean().getVMOption(MAX_FREE_RATIO_FLAG_NAME).getValue()

         ));

     }

     private void eat() {

         int HumongousObjectSize = Math.round(.9f * PAGE_SIZE);

         System.out.println("Will allocate objects of size=" +

                 MemoryUsagePrinter.humanReadableByteCount(HumongousObjectSize, true));

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

             ArrayList<byte[]> stuff = new ArrayList<>();

             eatList(stuff, 100, HumongousObjectSize);

             MemoryUsagePrinter.printMemoryUsage("eat #" + i);

             garbage.add(stuff);

         }

     }

     private void free() {

         // do not free last one list

         garbage.subList(0, garbage.size() - 1).clear();

         // do not free last one element from last list

         ArrayList stuff = garbage.get(garbage.size() - 1);

         stuff.subList(0, stuff.size() - 1).clear();

         System.gc();

     }

     private static void eatList(List garbage, int count, int size) {

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

             garbage.add(new byte[size]);

         }

     }

 }

 /**

  * Prints memory usage to standard output

  */

 class MemoryUsagePrinter {

     public static String humanReadableByteCount(long bytes, boolean si) {

         int unit = si ? 1000 : 1024;

         if (bytes < unit) {

             return bytes + " B";

         }

         int exp = (int) (Math.log(bytes) / Math.log(unit));

         String pre = (si ? "kMGTPE" : "KMGTPE").charAt(exp - 1) + (si ? "" : "i");

         return String.format("%.1f %sB", bytes / Math.pow(unit, exp), pre);

     }

     public static void printMemoryUsage(String label) {

         MemoryUsage memusage = ManagementFactory.getMemoryMXBean().getHeapMemoryUsage();

         float freeratio = 1f - (float) memusage.getUsed() / memusage.getCommitted();

         System.out.format("[%-24s] init: %-7s, used: %-7s, comm: %-7s, freeRatio ~= %.1f%%%n",

                 label,

                 humanReadableByteCount(memusage.getInit(), true),

                 humanReadableByteCount(memusage.getUsed(), true),

                 humanReadableByteCount(memusage.getCommitted(), true),

                 freeratio * 100

         );

     }

 }