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 }