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 TestSmallHeap
  26  * @bug 8067438
  27  * @requires vm.gc=="null"
  28  * @summary Verify that starting the VM with a small heap works
  29  * @run main/othervm -Xmx4m -XX:+UseParallelGC TestSmallHeap
  30  * @run main/othervm -Xmx4m -XX:+UseSerialGC TestSmallHeap
  31  * @run main/othervm -Xmx4m -XX:+UseG1GC TestSmallHeap
  32  * @run main/othervm -Xmx4m -XX:+UseConcMarkSweepGC TestSmallHeap
  33  *
  34  * Note: It would be nice to verify the minimal heap size here, but that
  35  * turns out to be quite tricky since we align the heap size based on
  36  * the card table size. And the card table size is aligned based on the
  37  * minimal pages size provided by the os. This means that on most platforms,
  38  * where the minimal page size is 4k, we get a minimal heap size of 2m but
  39  * on Solaris/Sparc we have a page size of 8k and get a minimal heap size
  40  * of 8m.
  41  * There is also no check in the VM for verifying that the maximum heap size
  42  * is larger than the supported minimal heap size. This means that specifying
  43  * -Xmx1m on the command line is fine but will give a heap of 2m (or 4m).
  44  * To work around these rather strange behaviors this test uses 4m for all
  45  * platforms.
  46  */
  47 
  48 import sun.management.ManagementFactoryHelper;
  49 import static com.oracle.java.testlibrary.Asserts.*;
  50 
  51 public class TestSmallHeap {
  52 
  53     public static void main(String[] args) {
  54         String maxHeap = ManagementFactoryHelper.getDiagnosticMXBean().getVMOption("MaxHeapSize").getValue();
  55         String expectedMaxHeap = "4194304";
  56         assertEQ(maxHeap, expectedMaxHeap);
  57     }
  58 }