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Java example source code file (PerfTestUtils.java)

This example Java source code file (PerfTestUtils.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

callable, default_repeat_chunk, default_repeat_stat, double, exception, nano_to_milli, perftestutils, random, runtest, statisticalsummary, string, summarystatistics, suppresswarnings, threading, threads, util

The PerfTestUtils.java Java example source code

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.commons.math3;

import java.util.Random;
import java.util.concurrent.Callable;
import org.apache.commons.math3.stat.descriptive.SummaryStatistics;
import org.apache.commons.math3.stat.descriptive.StatisticalSummary;
import org.apache.commons.math3.exception.MathIllegalStateException;
import org.apache.commons.math3.exception.util.LocalizedFormats;

/**
 * Simple benchmarking utilities.
 */
public class PerfTestUtils {
    /** Nanoseconds to milliseconds conversion factor ({@value}). */
    public static final double NANO_TO_MILLI = 1e-6;
    /** Default number of code repeat per timed block. */
    private static final int DEFAULT_REPEAT_CHUNK = 1000;
    /** Default number of code repeats for computing the average run time. */
    private static final int DEFAULT_REPEAT_STAT = 10000;
    /** RNG. */
    private static Random rng = new Random();

    /**
     * Timing.
     *
     * @param repeatChunk Each timing measurement will done done for that
     * number of repeats of the code.
     * @param repeatStat Timing will be averaged over that number of runs.
     * @param runGC Call {@code System.gc()} between each timed block. When
     * set to {@code true}, the test will run much slower.
     * @param methods Codes being timed.
     * @return for each of the given {@code methods}, a
     * {@link StatisticalSummary} of the average times (in milliseconds)
     * taken by a single call to the {@code call} method (i.e. the time
     * taken by each timed block divided by {@code repeatChunk}).
     */
    @SuppressWarnings("unchecked")
    public static StatisticalSummary[] time(int repeatChunk,
                                            int repeatStat,
                                            boolean runGC,
                                            Callable<Double> ... methods) {
        final double[][][] times = timesAndResults(repeatChunk,
                                                   repeatStat,
                                                   runGC,
                                                   methods);

        final int len = methods.length;
        final StatisticalSummary[] stats = new StatisticalSummary[len];
        for (int j = 0; j < len; j++) {
            final SummaryStatistics s = new SummaryStatistics();
            for (int k = 0; k < repeatStat; k++) {
                s.addValue(times[j][k][0]);
            }
            stats[j] = s.getSummary();
        }

        return stats;
    }

    /**
     * Timing.
     *
     * @param repeatChunk Each timing measurement will done done for that
     * number of repeats of the code.
     * @param repeatStat Timing will be averaged over that number of runs.
     * @param runGC Call {@code System.gc()} between each timed block. When
     * set to {@code true}, the test will run much slower.
     * @param methods Codes being timed.
     * @return for each of the given {@code methods} (first dimension), and
     * each of the {@code repeatStat} runs (second dimension):
     * <ul>
     *  <li>
     *   the average time (in milliseconds) taken by a single call to the
     *   {@code call} method (i.e. the time taken by each timed block divided
     *   by {@code repeatChunk})
     *  </li>
     *  <li>
     *   the result returned by the {@code call} method.
     *  </li>
     * </ul>
     */
    @SuppressWarnings("unchecked")
    public static double[][][] timesAndResults(int repeatChunk,
                                               int repeatStat,
                                               boolean runGC,
                                               Callable<Double> ... methods) {
        final int numMethods = methods.length;
        final double[][][] timesAndResults = new double[numMethods][repeatStat][2];

        try {
            for (int k = 0; k < repeatStat; k++) {
                for (int j = 0; j < numMethods; j++) {
                    if (runGC) {
                        // Try to perform GC outside the timed block.
                        System.gc();
                    }

                    final Callable<Double> r = methods[j];
                    final double[] result = new double[repeatChunk];

                    // Timed block.
                    final long start = System.nanoTime();
                    for (int i = 0; i < repeatChunk; i++) {
                        result[i] = r.call().doubleValue();
                    }
                    final long stop = System.nanoTime();

                    // Collect run time.
                    timesAndResults[j][k][0] = (stop - start) * NANO_TO_MILLI;
                    // Keep track of a randomly selected result.
                    timesAndResults[j][k][1] = result[rng.nextInt(repeatChunk)];
                }
            }
        } catch (Exception e) {
            // Abort benchmarking if codes throw exceptions.
            throw new MathIllegalStateException(LocalizedFormats.SIMPLE_MESSAGE, e.getMessage());
        }

        final double normFactor = 1d / repeatChunk;
        for (int j = 0; j < numMethods; j++) {
            for (int k = 0; k < repeatStat; k++) {
                timesAndResults[j][k][0] *= normFactor;
            }
        }

        return timesAndResults;
    }

    /**
     * Timing and report (to standard output) the average time and standard
     * deviation of a single call.
     * The timing is performed by calling the
     * {@link #time(int,int,boolean,Callable[]) time} method.
     *
     * @param title Title of the test (for the report).
     * @param repeatChunk Each timing measurement will done done for that
     * number of repeats of the code.
     * @param repeatStat Timing will be averaged over that number of runs.
     * @param runGC Call {@code System.gc()} between each timed block. When
     * set to {@code true}, the test will run much slower.
     * @param methods Codes being timed.
     * @return for each of the given {@code methods}, a statistics of the
     * average times (in milliseconds) taken by a single call to the
     * {@code call} method (i.e. the time taken by each timed block divided
     * by {@code repeatChunk}).
     */
    @SuppressWarnings("boxing")
    public static StatisticalSummary[] timeAndReport(String title,
                                                     int repeatChunk,
                                                     int repeatStat,
                                                     boolean runGC,
                                                     RunTest ... methods) {
        // Header format.
        final String hFormat = "%s (calls per timed block: %d, timed blocks: %d, time unit: ms)";

        // Width of the longest name.
        int nameLength = 0;
        for (RunTest m : methods) {
            int len = m.getName().length();
            if (len > nameLength) {
                nameLength = len;
            }
        }
        final String nameLengthFormat = "%" + nameLength + "s";

        // Column format.
        final String cFormat = nameLengthFormat + " %14s %14s %10s %10s %15s";
        // Result format.
        final String format = nameLengthFormat + " %.8e %.8e %.4e %.4e % .8e";

        System.out.println(String.format(hFormat,
                                         title,
                                         repeatChunk,
                                         repeatStat));
        System.out.println(String.format(cFormat,
                                         "name",
                                         "time/call",
                                         "std error",
                                         "total time",
                                         "ratio",
                                         "difference"));
        final StatisticalSummary[] time = time(repeatChunk,
                                               repeatStat,
                                               runGC,
                                               methods);
        final double refSum = time[0].getSum() * repeatChunk;
        for (int i = 0, max = time.length; i < max; i++) {
            final StatisticalSummary s = time[i];
            final double sum = s.getSum() * repeatChunk;
            System.out.println(String.format(format,
                                             methods[i].getName(),
                                             s.getMean(),
                                             s.getStandardDeviation(),
                                             sum,
                                             sum / refSum,
                                             sum - refSum));
        }

        return time;
    }

    /**
     * Timing and report (to standard output).
     * This method calls {@link #timeAndReport(String,int,int,boolean,RunTest[])
     * timeAndReport(title, 1000, 10000, false, methods)}.
     *
     * @param title Title of the test (for the report).
     * @param methods Codes being timed.
     * @return for each of the given {@code methods}, a statistics of the
     * average times (in milliseconds) taken by a single call to the
     * {@code call} method (i.e. the time taken by each timed block divided
     * by {@code repeatChunk}).
     */
    public static StatisticalSummary[] timeAndReport(String title,
                                                     RunTest ... methods) {
        return timeAndReport(title,
                             DEFAULT_REPEAT_CHUNK,
                             DEFAULT_REPEAT_STAT,
                             false,
                             methods);
    }

    /**
     * Utility class for storing a test label.
     */
    public static abstract class RunTest implements Callable<Double> {
        private final String name;

        /**
         * @param name Test name.
         */
        public RunTest(String name) {
            this.name = name;
        }

        /**
         * @return the name of this test.
         */
        public String getName() {
            return name;
        }

        /** {@inheritDoc} */
        public abstract Double call() throws Exception;
    }
}

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