1 /* 2 * Copyright (c) 2014 Oracle 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. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 package org.openjdk.bench.java.util.concurrent; 26 27 import org.openjdk.jmh.annotations.*; 28 29 import java.util.ArrayList; 30 import java.util.List; 31 import java.util.Random; 32 import java.util.concurrent.ThreadLocalRandom; 33 import java.util.concurrent.TimeUnit; 34 35 @BenchmarkMode(Mode.AverageTime) 36 @OutputTimeUnit(TimeUnit.NANOSECONDS) 37 public class ThreadLocalRandomNextInt { 38 39 @State(Scope.Benchmark) 40 public static class Global { 41 public ThreadLocal<Random> tlr; 42 private List<ThreadLocal<Integer>> contaminators; // reachable, non-garbage-collectable 43 44 @Setup(Level.Trial) 45 public void setup() { 46 tlr = new ThreadLocal<Random>() { 47 @Override 48 protected Random initialValue() { 49 return java.util.concurrent.ThreadLocalRandom.current(); 50 } 51 }; 52 53 // contaminate ThreadLocals 54 int contaminatorCount = Integer.getInteger("contaminators", 0); 55 contaminators = new ArrayList<>(contaminatorCount); 56 for (int i = 0; i < contaminatorCount; i++) { 57 final int finalI = i; 58 ThreadLocal<Integer> tl = new ThreadLocal<Integer>() { 59 @Override 60 protected Integer initialValue() { 61 return finalI; 62 } 63 }; 64 contaminators.add(tl); 65 tl.get(); 66 } 67 } 68 } 69 70 @State(Scope.Thread) 71 public static class Local { 72 public java.util.concurrent.ThreadLocalRandom tlr; 73 74 @Setup(Level.Trial) 75 public void setup() { 76 tlr = java.util.concurrent.ThreadLocalRandom.current(); 77 } 78 } 79 80 @Benchmark 81 public int baseline(Local l) { 82 return l.tlr.nextInt(); 83 } 84 85 @Benchmark 86 public int testJUC() { 87 return java.util.concurrent.ThreadLocalRandom.current().nextInt(); 88 } 89 90 @Benchmark 91 public int testLang(Global g) { 92 return g.tlr.get().nextInt(); 93 } 94 95 }