VolatileVsThreadLocalBenchmark.java

package net.tixxit.snippets;

import org.openjdk.jmh.annotations.GenerateMicroBenchmark;
import org.openjdk.jmh.annotations.Scope;
import org.openjdk.jmh.annotations.State;

public class VolatileVsThreadLocalBenchmark {

  @State(Scope.Benchmark)
  public static class ThreadLocalState {
    ThreadLocal<Integer> tl = new ThreadLocal<Integer>();

    public Integer inc() {
      Integer x = tl.get();
      if (x == null) x = 0;
      tl.set(x + 1);
      return x;
    }
  }

  @State(Scope.Thread)
  public static class VolatileState {
    volatile Integer vo = null;

    public Integer inc() {
      Integer x = vo;
      if (x == null) x = 0;
      vo = x + 1;
      return x;
    }
  }

  @GenerateMicroBenchmark
  public int testThreadLocal(ThreadLocalState state) {
    return state.inc();
  }

  @GenerateMicroBenchmark
  public int testVolatile(VolatileState state) {
    return state.inc();
  }
}

Benchmark                                                Mode   Samples         Mean   Mean error    Units
n.t.s.VolatileVsThreadLocalBenchmark.testThreadLocal    thrpt         5   153081.466    25534.485   ops/ms
n.t.s.VolatileVsThreadLocalBenchmark.testVolatile       thrpt         5    61799.546     6802.259   ops/ms