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3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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13  * accompanied this code).
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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 {
testIntervalOnce(int interval, boolean throwIfFailure)36   private static boolean testIntervalOnce(int interval, boolean throwIfFailure) {
37     HeapMonitor.resetEventStorage();
38     HeapMonitor.setSamplingInterval(interval);
39 
40     HeapMonitor.enableSamplingEvents();
41 
42     int allocationTotal = 10 * 1024 * 1024;
43     int allocationIterations = 10;
44 
45     double actualCount = 0;
46     for (int i = 0; i < allocationIterations; i++) {
47       HeapMonitor.resetEventStorage();
48       HeapMonitor.allocateSize(allocationTotal);
49       actualCount += HeapMonitor.getEventStorageElementCount();
50     }
51 
52     HeapMonitor.disableSamplingEvents();
53 
54     double expectedCount = allocationTotal * allocationIterations / interval;
55 
56     double error = Math.abs(actualCount - expectedCount);
57     double errorPercentage = error / expectedCount * 100;
58 
59     boolean success = (errorPercentage < 10.0);
60 
61     if (!success && throwIfFailure) {
62       throw new RuntimeException("Interval average over 10% for interval " + interval + " -> "
63           + actualCount + ", " + expectedCount);
64     }
65 
66     return success;
67   }
68 
69 
testInterval(int interval)70   private static void testInterval(int interval) {
71     // Test the interval twice, it can happen that the test is "unlucky" and the interval just goes above
72     // the 10% mark. So try again to squash flakiness.
73     // Flakiness is due to the fact that this test is dependent on the sampling interval, which is a
74     // statistical geometric variable around the sampling interval. This means that the test could be
75     // unlucky and not achieve the mean average fast enough for the test case.
76     if (!testIntervalOnce(interval, false)) {
77       testIntervalOnce(interval, true);
78     }
79   }
80 
main(String[] args)81   public static void main(String[] args) {
82     int[] tab = {1024, 8192};
83 
84     HeapMonitor.calculateAverageOneElementSize();
85 
86     for (int intervalIdx = 0; intervalIdx < tab.length; intervalIdx++) {
87       testInterval(tab[intervalIdx]);
88     }
89   }
90 }
91