org.openjdk.jmh.samples.JMHSample_18_Control Maven / Gradle / Ivy

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 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
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package org.openjdk.jmh.samples;

import org.openjdk.jmh.annotations.GenerateMicroBenchmark;
import org.openjdk.jmh.annotations.Group;
import org.openjdk.jmh.annotations.Scope;
import org.openjdk.jmh.annotations.State;
import org.openjdk.jmh.logic.Control;
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.concurrent.atomic.AtomicBoolean;

@State(Scope.Group)
public class JMHSample_18_Control {

    /*
     * Sometimes you need the tap into the harness mind to get the info
     * on the transition change. For this, we have the experimental state object,
     * Control, which is updated by JMH as we go.
     */

    /*
     * In this example, we want to estimate the ping-pong speed for the simple
     * AtomicBoolean. Unfortunately, doing that in naive manner will livelock
     * one of the threads, because the executions of ping/pong are not paired
     * perfectly. We need the escape hatch to terminate the loop if threads
     * are about to leave the measurement.
     */

    public final AtomicBoolean flag = new AtomicBoolean();

    @GenerateMicroBenchmark
    @Group("pingpong")
    public void ping(Control cnt) {
        while (!cnt.stopMeasurement && !flag.compareAndSet(false, true)) {
            // this body is intentionally left blank
        }
    }

    @GenerateMicroBenchmark
    @Group("pingpong")
    public void pong(Control cnt) {
        while (!cnt.stopMeasurement && !flag.compareAndSet(true, false)) {
            // this body is intentionally left blank
        }
    }

    /*
     * ============================== HOW TO RUN THIS TEST: ====================================
     *
     * You can run this test:
     *
     * a) Via the command line:
     *    $ mvn clean install
     *    $ java -jar target/microbenchmarks.jar ".*JMHSample_18.*" -wi 1 -i 5 -t 2 -f 1
     *    (we requested 1 warmup iterations, 5 iterations, 2 threads, and single fork)
     *
     * b) Via the Java API:
     */

    public static void main(String[] args) throws RunnerException {
        Options opt = new OptionsBuilder()
                .include(".*" + JMHSample_18_Control.class.getSimpleName() + ".*")
                .warmupIterations(1)
                .measurementIterations(5)
                .threads(2)
                .forks(1)
                .build();

        new Runner(opt).run();
    }

}