1 /*
   2  * Copyright (c) 2019, 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 package gc.z;
  25 
  26 /*
  27  * @test TestUncommit
  28  * @requires vm.gc.Z & !vm.graal.enabled
  29  * @summary Test ZGC uncommit unused memory
  30  * @run main/othervm -XX:+UnlockExperimentalVMOptions -XX:+UseZGC -Xms128M -Xmx512M -XX:ZUncommitDelay=10 gc.z.TestUncommit true 3
  31  * @run main/othervm -XX:+UnlockExperimentalVMOptions -XX:+UseZGC -Xms512M -Xmx512M -XX:ZUncommitDelay=10 gc.z.TestUncommit false 1
  32  * @run main/othervm -XX:+UnlockExperimentalVMOptions -XX:+UseZGC -Xms128M -Xmx512M -XX:ZUncommitDelay=10 -XX:-ZUncommit gc.z.TestUncommit false 1
  33  */
  34 
  35 import java.util.ArrayList;
  36 
  37 public class TestUncommit {
  38     private static final int delay = 10; // seconds
  39     private static final int allocSize = 200 * 1024 * 1024; // 200M
  40     private static final int smallObjectSize = 4 * 1024; // 4K
  41     private static final int mediumObjectSize = 2 * 1024 * 1024; // 2M
  42     private static final int largeObjectSize = allocSize;
  43 
  44     private static volatile ArrayList<byte[]> keepAlive;
  45 
  46     private static long capacity() {
  47         return Runtime.getRuntime().totalMemory();
  48     }
  49 
  50     private static void allocate(int objectSize) {
  51         keepAlive = new ArrayList<>();
  52         for (int i = 0; i < allocSize; i+= objectSize) {
  53             keepAlive.add(new byte[objectSize]);
  54         }
  55     }
  56 
  57     private static void reclaim() {
  58         keepAlive = null;
  59         System.gc();
  60     }
  61 
  62     private static void test(boolean enabled, int objectSize) throws Exception {
  63         final var beforeAlloc = capacity();
  64 
  65         // Allocate memory
  66         allocate(objectSize);
  67 
  68         final var afterAlloc = capacity();
  69 
  70         // Reclaim memory
  71         reclaim();
  72 
  73         // Wait shorter than the uncommit delay
  74         Thread.sleep(delay * 1000 / 2);
  75 
  76         final var beforeUncommit = capacity();
  77 
  78         // Wait longer than the uncommit delay
  79         Thread.sleep(delay * 1000);
  80 
  81         final var afterUncommit = capacity();
  82 
  83         System.out.println("  Uncommit Enabled: " + enabled);
  84         System.out.println("    Uncommit Delay: " + delay);
  85         System.out.println("       Object Size: " + objectSize);
  86         System.out.println("        Alloc Size: " + allocSize);
  87         System.out.println("      Before Alloc: " + beforeAlloc);
  88         System.out.println("       After Alloc: " + afterAlloc);
  89         System.out.println("   Before Uncommit: " + beforeUncommit);
  90         System.out.println("    After Uncommit: " + afterUncommit);
  91         System.out.println();
  92 
  93         // Verify
  94         if (enabled) {
  95             if (beforeUncommit == beforeAlloc) {
  96                 throw new Exception("Uncommitted too fast");
  97             }
  98 
  99             if (afterUncommit >= afterAlloc) {
 100                 throw new Exception("Uncommitted too slow");
 101             }
 102 
 103             if (afterUncommit < beforeAlloc) {
 104                 throw new Exception("Uncommitted too much");
 105             }
 106 
 107             if (afterUncommit > beforeAlloc) {
 108                 throw new Exception("Uncommitted too little");
 109             }
 110         } else {
 111             if (afterAlloc > beforeUncommit ||
 112                 afterAlloc > afterUncommit) {
 113                 throw new Exception("Should not uncommit");
 114             }
 115         }
 116     }
 117 
 118     public static void main(String[] args) throws Exception {
 119         final boolean enabled = Boolean.parseBoolean(args[0]);
 120         final int iterations = Integer.parseInt(args[1]);
 121 
 122         for (int i = 0; i < iterations; i++) {
 123             System.out.println("Iteration " + i);
 124             test(enabled, smallObjectSize);
 125             test(enabled, mediumObjectSize);
 126             test(enabled, largeObjectSize);
 127         }
 128     }
 129 }