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 rate average.

    29  * @build Frame HeapMonitor

    30  * @compile HeapMonitorStatRateTest.java

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

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

    33  */

    34 

    35 public class HeapMonitorStatRateTest {

    36 

    37   private native static double getAverageRate();

    38 

    39   private static boolean testRateOnce(int rate, boolean throwIfFailure) {

    40     HeapMonitor.resetEventStorage();

    41     HeapMonitor.setSamplingRate(rate);

    42 

    43     HeapMonitor.enableSamplingEvents();

    44 

    45     int allocationTotal = 10 * 1024 * 1024;

    46     HeapMonitor.allocateSize(allocationTotal);

    47 

    48     HeapMonitor.disableSamplingEvents();

    49 

    50     double actualCount = HeapMonitor.getEventStorageElementCount();

    51     double expectedCount = allocationTotal / rate;

    52 

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

    54     double errorPercentage = error / expectedCount * 100;

    55 

    56     boolean failure = (errorPercentage > 10.0);

    57 

    58     if (failure && throwIfFailure) {

    59       throw new RuntimeException("Rate average over 10% for rate " + rate + " -> " + actualCount

    60           + ", " + expectedCount);

    61     }

    62 

    63     return failure;

    64   }

    65 

    66 

    67   private static void testRate(int rate) {

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

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

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

    71     // statistical geometric variable around the sampling rate. This means that the test could be

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

    73     if (!testRateOnce(rate, false)) {

    74       testRateOnce(rate, true);

    75     }

    76   }

    77 

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

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

    80 

    81     for (int rateIdx = 0; rateIdx < tab.length; rateIdx++) {

    82       testRate(tab[rateIdx]);

    83     }

    84   }

    85 }