1 /*

     2  * Copyright (c) 2018, Google 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 MyPackage;

    25 

    26 /**

    27  * @test

    28  * @summary Verifies the JVMTI Heap Monitor sampling interval average.

    29  * @build Frame HeapMonitor

    30  * @compile HeapMonitorStatIntervalTest.java

    31  * @requires vm.compMode != "Xcomp"

    32  * @run main/othervm/native -agentlib:HeapMonitorTest MyPackage.HeapMonitorStatIntervalTest

    33  */

    34 

    35 public class HeapMonitorStatIntervalTest {

    36 

    37   private native static double getAverageInterval();

    38 

    39   private static boolean testIntervalOnce(int interval, boolean throwIfFailure) {

    40     HeapMonitor.resetEventStorage();

    41     HeapMonitor.setSamplingInterval(interval);

    42 

    43     HeapMonitor.enableSamplingEvents();

    44 

    45     int allocationTotal = 10 * 1024 * 1024;

    46     int allocationIterations = 10;

    47 

    48     double actualCount = 0;

    49     for (int i = 0; i < allocationIterations; i++) {

    50       HeapMonitor.resetEventStorage();

    51       HeapMonitor.allocateSize(allocationTotal);

    52       actualCount += HeapMonitor.getEventStorageElementCount();

    53     }

    54 

    55     HeapMonitor.disableSamplingEvents();

    56 

    57     double expectedCount = allocationTotal * allocationIterations / interval;

    58 

    59     double error = Math.abs(actualCount - expectedCount);

    60     double errorPercentage = error / expectedCount * 100;

    61 

    62     boolean success = (errorPercentage < 10.0);

    63 

    64     if (!success && throwIfFailure) {

    65       throw new RuntimeException("Interval average over 10% for interval " + interval + " -> "

    66           + actualCount + ", " + expectedCount);

    67     }

    68 

    69     return success;

    70   }

    71 

    72 

    73   private static void testInterval(int interval) {

    74     // Test the interval twice, it can happen that the test is "unlucky" and the interval just goes above

    75     // the 10% mark. So try again to squash flakiness.

    76     // Flakiness is due to the fact that this test is dependent on the sampling interval, which is a

    77     // statistical geometric variable around the sampling interval. This means that the test could be

    78     // unlucky and not achieve the mean average fast enough for the test case.

    79     if (!testIntervalOnce(interval, false)) {

    80       testIntervalOnce(interval, true);

    81     }

    82   }

    83 

    84   public static void main(String[] args) {

    85     int[] tab = {1024, 8192};

    86 

    87     for (int intervalIdx = 0; intervalIdx < tab.length; intervalIdx++) {

    88       testInterval(tab[intervalIdx]);

    89     }

    90   }

    91 }