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