--- /dev/null 2018-03-08 15:11:46.002676589 -0800 +++ new/test/hotspot/jtreg/serviceability/jvmti/HeapMonitor/MyPackage/HeapMonitorStatArrayCorrectnessTest.java 2018-03-19 14:01:27.657567433 -0700 @@ -0,0 +1,84 @@ +/* + * Copyright (c) 2018, Google and/or its affiliates. All rights reserved. + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. + * + * This code is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 only, as + * published by the Free Software Foundation. + * + * This code is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License + * version 2 for more details (a copy is included in the LICENSE file that + * accompanied this code). + * + * You should have received a copy of the GNU General Public License version + * 2 along with this work; if not, write to the Free Software Foundation, + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. + * + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA + * or visit www.oracle.com if you need additional information or have any + * questions. + */ + +package MyPackage; + +/** + * @test + * @build Frame HeapMonitor + * @summary Verifies the JVMTI Heap Monitor rate when allocating arrays. + * @compile HeapMonitorStatArrayCorrectnessTest.java + * @run main/othervm/native -agentlib:HeapMonitor MyPackage.HeapMonitorStatArrayCorrectnessTest + */ + +public class HeapMonitorStatArrayCorrectnessTest { + + // Do 100000 iterations and expect maxIteration / multiplier samples. + private static final int maxIteration = 100000; + private static int array[]; + + private static void allocate(int size) { + for (int j = 0; j < maxIteration; j++) { + array = new int[size]; + } + } + + public static void main(String[] args) { + int sizes[] = {1000, 10000, 100000}; + + for (int currentSize : sizes) { + System.out.println("Testing size " + currentSize); + + if (!HeapMonitor.eventStorageIsEmpty()) { + throw new RuntimeException("Should not have any events stored yet."); + } + + // 111 is as good a number as any. + final int samplingMultiplier = 111; + HeapMonitor.setSamplingRate(samplingMultiplier * currentSize); + + allocate(currentSize); + + // For simplifications, we ignore the array memory usage for array internals (with the array + // sizes requested, it should be a negligible oversight). + // + // That means that with maxIterations, the loop in the method allocate requests: + // maxIterations * currentSize * 4 bytes (4 for integers) + // + // Via the enable sampling, the code requests a sample every samplingMultiplier * currentSize bytes. + // + // Therefore, the expected sample number is: + // (maxIterations * currentSize * 4) / (samplingMultiplier * currentSize); + double expected = maxIteration; + expected *= 4; + expected /= samplingMultiplier; + + // 10% error ensures a sanity test without becoming flaky. + if (!HeapMonitor.statsHaveExpectedNumberSamples((int) expected, 10)) { + throw new RuntimeException("Statistics should show about " + expected + " samples."); + } + + HeapMonitor.resetEventStorage(); + } + } +}