/* * 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; import java.util.ArrayList; import java.util.List; /** API for handling the underlying heap sampling monitoring system. */ public class HeapMonitor { private static int[][] arrays; private static int allocationIterations = 1000; static { try { System.loadLibrary("HeapMonitorTest"); } catch (UnsatisfiedLinkError ule) { System.err.println("Could not load HeapMonitor library"); System.err.println("java.library.path: " + System.getProperty("java.library.path")); throw ule; } } /** Set a specific sampling rate, 0 samples every allocation. */ public native static void setSamplingRate(int rate); public native static void enableSamplingEvents(); public native static boolean enableSamplingEventsForTwoThreads(Thread firstThread, Thread secondThread); public native static void disableSamplingEvents(); /** * Allocate memory but first create a stack trace of a particular depth. * * @return list of frames for the allocation. */ public static List allocate(int depth) { List frames = new ArrayList(); if (depth > 1) { createStackDepth(depth - 1, frames); frames.add(new Frame("allocate", "(I)Ljava/util/List;", "HeapMonitor.java", 58)); } else { actuallyAllocate(); frames.add(new Frame("actuallyAllocate", "()I", "HeapMonitor.java", 121)); frames.add(new Frame("allocate", "(I)Ljava/util/List;", "HeapMonitor.java", 61)); } return frames; } /** * Allocate memory but first create a stack trace. * * @return list of frames for the allocation. */ public static List allocate() { int sum = 0; List frames = new ArrayList(); allocate(frames); frames.add(new Frame("allocate", "()Ljava/util/List;", "HeapMonitor.java", 76)); return frames; } private static void createStackDepth(int depth, List frames) { if (depth > 1) { createStackDepth(depth - 1, frames); frames.add(new Frame("createStackDepth", "(ILjava/util/List;)V", "HeapMonitor.java", 83)); } else { allocate(frames); frames.add(new Frame("createStackDepth", "(ILjava/util/List;)V", "HeapMonitor.java", 86)); } } private static void allocate(List frames) { int sum = 0; for (int j = 0; j < allocationIterations; j++) { sum += actuallyAllocate(); } frames.add(new Frame("actuallyAllocate", "()I", "HeapMonitor.java", 121)); frames.add(new Frame("allocate", "(Ljava/util/List;)V", "HeapMonitor.java", 94)); } public static List repeatAllocate(int max) { List frames = null; for (int i = 0; i < max; i++) { frames = allocate(); } frames.add(new Frame("repeatAllocate", "(I)Ljava/util/List;", "HeapMonitor.java", 103)); return frames; } private static int actuallyAllocate() { int sum = 0; // Let us assume that a 1-element array is 24 bytes of memory and we want // 2MB allocated. int iterations = (1 << 19) / 6; if (arrays == null) { arrays = new int[iterations][]; } for (int i = 0; i < iterations; i++) { int tmp[] = new int[1]; // Force it to be kept and, at the same time, wipe out any previous data. arrays[i] = tmp; sum += arrays[0][0]; } return sum; } public static int allocateSize(int totalSize) { int sum = 0; // Let us assume that a 1-element array is 24 bytes. int iterations = totalSize / 24; if (arrays == null) { arrays = new int[iterations][]; } System.out.println("Allocating for " + iterations); for (int i = 0; i < iterations; i++) { int tmp[] = new int[1]; // Force it to be kept and, at the same time, wipe out any previous data. arrays[i] = tmp; sum += arrays[0][0]; } return sum; } /** Remove the reference to the global array to free data at the next GC. */ public static void freeStorage() { arrays = null; } public native static boolean obtainedEvents(Frame[] frames); public native static boolean garbageContains(Frame[] frames); public native static boolean eventStorageIsEmpty(); public native static void resetEventStorage(); public native static int getEventStorageElementCount(); public native static void forceGarbageCollection(); public static boolean statsHaveExpectedNumberSamples(int expected, int acceptedErrorPercentage) { double actual = getEventStorageElementCount(); double diffPercentage = Math.abs(actual - expected) / expected; return diffPercentage < acceptedErrorPercentage; } public static void setAllocationIterations(int iterations) { allocationIterations = iterations; } }