org.openjdk.jmh.samples.JMHSample_26_BatchSize Maven / Gradle / Ivy

/*
 * Copyright (c) 2014, Oracle America, Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *  * Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *
 *  * Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 *  * Neither the name of Oracle nor the names of its contributors may be used
 *    to endorse or promote products derived from this software without
 *    specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 * THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.openjdk.jmh.samples;

import org.openjdk.jmh.annotations.Benchmark;
import org.openjdk.jmh.annotations.BenchmarkMode;
import org.openjdk.jmh.annotations.Level;
import org.openjdk.jmh.annotations.Measurement;
import org.openjdk.jmh.annotations.Mode;
import org.openjdk.jmh.annotations.Scope;
import org.openjdk.jmh.annotations.Setup;
import org.openjdk.jmh.annotations.State;
import org.openjdk.jmh.annotations.Warmup;
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;

import java.util.LinkedList;
import java.util.List;

@State(Scope.Thread)
public class JMHSample_26_BatchSize {

    /*
     * Sometimes you need to evaluate operation which doesn't have
     * the steady state. The cost of a benchmarked operation may
     * significantly vary from invocation to invocation.
     *
     * In this case, using the timed measurements is not a good idea,
     * and the only acceptable benchmark mode is a single shot. On the
     * other hand, the operation may be too small for reliable single
     * shot measurement.
     *
     * We can use "batch size" parameter to describe the number of
     * @Benchmark invocations to do per one "shot" without looping the method
     * manually and protect from problems described in JMHSample_11_Loops.
     * If there are any @Setup/@TearDown(Level.Invocation), they still run
     * per each @Benchmark invocation.
     */

    /*
     * Suppose we want to measure insertion in the middle of the list.
     */

    List list = new LinkedList<>();

    @Benchmark
    @Warmup(iterations = 5, time = 1)
    @Measurement(iterations = 5, time = 1)
    @BenchmarkMode(Mode.AverageTime)
    public List measureWrong_1() {
        list.add(list.size() / 2, "something");
        return list;
    }

    @Benchmark
    @Warmup(iterations = 5, time = 5)
    @Measurement(iterations = 5, time = 5)
    @BenchmarkMode(Mode.AverageTime)
    public List measureWrong_5() {
        list.add(list.size() / 2, "something");
        return list;
    }

    /*
     * This is what you do with JMH.
     */
    @Benchmark
    @Warmup(iterations = 5, batchSize = 5000)
    @Measurement(iterations = 5, batchSize = 5000)
    @BenchmarkMode(Mode.SingleShotTime)
    public List measureRight() {
        list.add(list.size() / 2, "something");
        return list;
    }

    @Setup(Level.Iteration)
    public void setup(){
        list.clear();
    }

    /*
     * ============================== HOW TO RUN THIS TEST: ====================================
     *
     * You can see completely different results for measureWrong_1 and measureWrong_5; this
     * is because the workload has no steady state. The result of the workload is dependent
     * on the measurement time. measureRight does not have this drawback, because it measures
     * the N invocations of the test method and measures it's time.
     *
     * We measure batch of 5000 invocations and consider the batch as the single operation.
     *
     * You can run this test:
     *
     * a) Via the command line:
     *    $ mvn clean install
     *    $ java -jar target/benchmarks.jar JMHSample_26 -f 1
     *
     * b) Via the Java API:
     *    (see the JMH homepage for possible caveats when running from IDE:
     *      http://openjdk.java.net/projects/code-tools/jmh/)
     */

    public static void main(String[] args) throws RunnerException {
        Options opt = new OptionsBuilder()
                .include(JMHSample_26_BatchSize.class.getSimpleName())
                .forks(1)
                .build();

        new Runner(opt).run();
    }

}