StringPerf.java

import java.util.concurrent.TimeUnit;

import org.openjdk.jmh.annotations.Benchmark;
import org.openjdk.jmh.annotations.BenchmarkMode;
import org.openjdk.jmh.annotations.Fork;
import org.openjdk.jmh.annotations.Measurement;
import org.openjdk.jmh.annotations.Mode;
import org.openjdk.jmh.annotations.OutputTimeUnit;
import org.openjdk.jmh.annotations.Param;
import org.openjdk.jmh.annotations.Scope;
import org.openjdk.jmh.annotations.Setup;
import org.openjdk.jmh.annotations.State;
import org.openjdk.jmh.annotations.Threads;
import org.openjdk.jmh.annotations.Warmup;
import org.openjdk.jmh.infra.Blackhole;
import org.openjdk.jmh.runner.Runner;
import org.openjdk.jmh.runner.RunnerException;
import org.openjdk.jmh.runner.options.Options;
import org.openjdk.jmh.runner.options.OptionsBuilder;

/**
 * Benchmark                 (size)  Mode  Cnt       Score       Error  Units    EveragePerSingleString
 * StringPerf.stringIntern        1  avgt    5       0.150 ±     0.009  us/op    0.15
 * StringPerf.stringIntern     1000  avgt    5     169.744 ±    10.045  us/op    0.169744
 * StringPerf.stringIntern    10000  avgt    5    1848.249 ±    42.983  us/op    0.1848249
 * StringPerf.stringIntern   100000  avgt    5   27577.632 ±  1922.913  us/op    0.27577632
 * StringPerf.stringIntern  1000000  avgt    5  773846.797 ± 66098.331  us/op    0.773846797
 *
 * @author vladimir.dolzhenko
 * @since 2016-11-11
 */
@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.MICROSECONDS)
@Fork(1)
@Warmup(iterations = 2, time = 1000, timeUnit = TimeUnit.MILLISECONDS)
@Measurement(iterations = 2, time = 1000, timeUnit = TimeUnit.MILLISECONDS)
@Threads(1)
public class StringPerf {

    @State(Scope.Benchmark)
    public static class BenchmarkState {
        @Param( {"1", "1000", "10000", "100000", "1000000"})
        public int size;

        public String[] strings;

        @Setup
        public void setUp() {
            strings = new String[size];
            for (int i = 0; i < size; i++) {
                strings[i] = "aaaaaaaaaa" + ('0' + i) + Integer.toString(i) + "zzzzzzzzzzzzz";
            }
        }
    }

    @Benchmark
    public void stringIntern(BenchmarkState state, Blackhole bh) {
        for (int i = 0; i < state.strings.length; i++) {
            bh.consume(state.strings[i].intern());
        }
    }

    public static void main(String[] args) throws RunnerException {
        Options opt = new OptionsBuilder()
                .include(StringPerf.class.getSimpleName())
                .warmupIterations(5)
                .measurementIterations(5)
                .build();

        new Runner(opt).run();
    }
}