BiasedTrollingTest.java

/*

Benchmark                  (doTrolling)  Mode  Cnt   Score   Error  Units
BiasedTrollingTest.string         false  avgt    5   6.672 ± 1.246  ns/op
BiasedTrollingTest.string          true  avgt    5  22.096 ± 4.520  ns/op

 */

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.ThreadLocalRandom;
import java.util.concurrent.TimeUnit;

import org.openjdk.jmh.annotations.*;
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;

/**
 * Note: Has to be run with -XX:BiasedLockingStartupDelay=0
 * <p>
 * (red) hat tip @shipilev
 *
 * @author [email protected]
 * @since 2017-01-16
 */
@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.NANOSECONDS)
@Fork(1)
@Warmup(iterations = 1, time = 1000, timeUnit = TimeUnit.MILLISECONDS)
@Measurement(iterations = 5, time = 5000, timeUnit = TimeUnit.MILLISECONDS)
@Threads(1)
@State(Scope.Benchmark)
public class BiasedTrollingTest {

    StringBuffer buffer;

    @Param( {"false", "true"})
    boolean doTrolling;

    @Setup
    public void setup() throws InterruptedException {
        buffer = new StringBuffer();

        final int count = 100;

        if (doTrolling) {
            final StringBuffer[] trololos = new StringBuffer[count];
            for (int i = 0; i < count; i++) {
                trololos[i] = new StringBuffer();
            }
            ExecutorService executor = Executors.newFixedThreadPool(4);

            for (int t = 0; t < 4; t++) {
                executor.submit(() -> {
                    final ThreadLocalRandom random = ThreadLocalRandom.current();
                    for (int c = 0; c < 10_000; c++) {
                        trololos[random.nextInt(count)].append('c');
                    }
                });
            }

            executor.shutdown();
            executor.awaitTermination(1, TimeUnit.DAYS);
        }
    }

    @Benchmark
    public String string() {
        return buffer.toString();
    }

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

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