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 TestHumongousShrinkHeap
  26  * @bug 8036025
  27  * @summary Verify that heap shrinking after GC of hard defragmented by humongous object heap
  28  * @library /testlibrary
  29  * @run main/othervm -XX:MinHeapFreeRatio=10 -XX:MaxHeapFreeRatio=50 -XX:+UseG1GC -XX:G1HeapRegionSize=1M -Xloggc:gc_10_50.log TestHumongousShrinkHeap
  30  */
  31 
  32 import com.oracle.java.testlibrary.gc.MemoryUsagePrinter;
  33 import com.oracle.java.testlibrary.TestDynamicVMOption;
  34 import java.lang.management.ManagementFactory;
  35 import java.lang.management.MemoryUsage;
  36 import java.util.ArrayList;
  37 import java.util.List;
  38 import sun.management.ManagementFactoryHelper;
  39 import static com.oracle.java.testlibrary.Asserts.*;
  40 
  41 public class TestHumongousShrinkHeap {
  42 
  43     private static final ArrayList<ArrayList<byte[]>> garbage = new ArrayList<>();
  44     private static final int PAGE_SIZE = 1024 * 1024; // 1M 
  45     private static final int PAGES_NUM = 5;
  46 
  47     
  48     public static void main(String[] args) {
  49         new TestHumongousShrinkHeap().test();
  50     }
  51 
  52     private final void test() {
  53         System.gc();
  54         MemoryUsagePrinter.printMemoryUsage("init");
  55 
  56         eat();        
  57         MemoryUsagePrinter.printMemoryUsage("eaten");
  58         MemoryUsage muFull = ManagementFactory.getMemoryMXBean().getHeapMemoryUsage();
  59         
  60         free();
  61         MemoryUsagePrinter.printMemoryUsage("free");
  62         MemoryUsage muFree = ManagementFactory.getMemoryMXBean().getHeapMemoryUsage();
  63 
  64         assertLessThan(muFree.getCommitted(), muFull.getCommitted(), String.format(
  65                 "committed free heap size is not less than committed full heap size, heap hasn't been shrunk?%n"
  66                 + "%s = %s%n%s = %s",
  67                 TestDynamicVMOption.MIN_FREE_RATIO_FLAG_NAME,
  68                 ManagementFactoryHelper.getDiagnosticMXBean().getVMOption(TestDynamicVMOption.MIN_FREE_RATIO_FLAG_NAME).getValue(),
  69                 TestDynamicVMOption.MAX_FREE_RATIO_FLAG_NAME,
  70                 ManagementFactoryHelper.getDiagnosticMXBean().getVMOption(TestDynamicVMOption.MAX_FREE_RATIO_FLAG_NAME).getValue()
  71         ));
  72     }
  73 
  74     private void eat() {
  75         int HumongousObjectSize = Math.round(.9f * PAGE_SIZE);
  76         System.out.println("Will allocate objects of size=" + 
  77                 MemoryUsagePrinter.humanReadableByteCount(HumongousObjectSize, true));
  78          
  79         for (int i = 0; i < PAGES_NUM; i++) {
  80             ArrayList<byte[]> stuff = new ArrayList<>();
  81             eatList(stuff, 100, HumongousObjectSize);
  82             MemoryUsagePrinter.printMemoryUsage("eat #" + i);
  83             garbage.add(stuff);
  84         }
  85     }
  86 
  87     private void free() {
  88         // do not free last one list
  89         garbage.subList(0, garbage.size() - 1).clear();
  90 
  91         // do not free last one element from last list
  92         ArrayList stuff = garbage.get(garbage.size() - 1);
  93         stuff.subList(0, stuff.size() - 1).clear();
  94         System.gc();
  95     }
  96 
  97     private static void eatList(List garbage, int count, int size) {
  98         for (int i = 0; i < count; i++) {
  99             garbage.add(new byte[size]);
 100         }
 101     }
 102 }