org.openjdk.jmh.samples.JMHSample_06_FixtureLevel Maven / Gradle / Ivy
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package org.openjdk.jmh.samples;
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;
@State(Scope.Thread)
public class JMHSample_06_FixtureLevel {
double x;
/*
* Fixture methods have different levels to control when they should be run.
* There are at least three Levels available to the user. These are, from
* top to bottom:
*
* Level.Trial: before or after the entire benchmark run (the sequence of iterations)
* Level.Iteration: before or after the benchmark iteration (the sequence of invocations)
* Level.Invocation; before or after the benchmark method invocation (WARNING: read the Javadoc before using)
*
* Time spent in fixture methods does not count into the performance
* metrics, so you can use this to do some heavy-lifting.
*/
@TearDown(Level.Iteration)
public void check() {
assert x > Math.PI : "Nothing changed?";
}
@Benchmark
public void measureRight() {
x++;
}
@Benchmark
public void measureWrong() {
double x = 0;
x++;
}
/*
* ============================== HOW TO RUN THIS TEST: ====================================
*
* You can see measureRight() yields the result, and measureWrong() fires
* the assert at the end of first iteration! This will not generate the results
* for measureWrong(). You can also prevent JMH for proceeding further by
* requiring "fail on error".
*
* You can run this test:
*
* a) Via the command line:
* $ mvn clean install
* $ java -ea -jar target/benchmarks.jar JMHSample_06 -f 1
* (we requested single fork; there are also other options, see -h)
*
* You can optionally supply -foe to fail the complete run.
*
* 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_06_FixtureLevel.class.getSimpleName())
.forks(1)
.jvmArgs("-ea")
.shouldFailOnError(false) // switch to "true" to fail the complete run
.build();
new Runner(opt).run();
}
}