diff --git a/core-java-modules/core-java-concurrency-advanced-3/src/main/java/com/baeldung/workstealing/PrimeNumbers.java b/core-java-modules/core-java-concurrency-advanced-3/src/main/java/com/baeldung/workstealing/PrimeNumbers.java new file mode 100644 index 0000000000..5c1eddbf68 --- /dev/null +++ b/core-java-modules/core-java-concurrency-advanced-3/src/main/java/com/baeldung/workstealing/PrimeNumbers.java @@ -0,0 +1,84 @@ +package com.baeldung.workstealing; + +import java.util.ArrayList; +import java.util.Arrays; +import java.util.List; +import java.util.concurrent.ForkJoinTask; +import java.util.concurrent.RecursiveAction; +import java.util.concurrent.atomic.AtomicInteger; + +public class PrimeNumbers extends RecursiveAction { + + private int lowerBound; + private int upperBound; + private int granularity; + static final List GRANULARITIES + = Arrays.asList(1, 10, 100, 1000, 10000); + private AtomicInteger noOfPrimeNumbers = new AtomicInteger(); + + PrimeNumbers(int lowerBound, int upperBound, int granularity) { + this.lowerBound = lowerBound; + this.upperBound = upperBound; + this.granularity = granularity; + } + + PrimeNumbers(int upperBound) { + this(1, upperBound, 100); + } + + private PrimeNumbers(int lowerBound, int upperBound) { + this(lowerBound, upperBound, 100); + } + + private List subTasks() { + List subTasks = new ArrayList<>(); + + for (int i = 1; i <= this.upperBound / granularity; i++) { + int upper = i * granularity; + int lower = (upper - granularity) + 1; + subTasks.add(new PrimeNumbers(lower, upper)); + } + return subTasks; + } + + @Override + protected void compute() { + if (((upperBound + 1) - lowerBound) > granularity) { + ForkJoinTask.invokeAll(subTasks()); + } else { + findPrimeNumbers(); + } + } + + void findPrimeNumbers() { + for (int num = lowerBound; num <= upperBound; num++) { + if (isPrime(num)) { + noOfPrimeNumbers.getAndIncrement(); + } + } + } + + private boolean isPrime(int number) { + if (number == 2) { + return true; + } + + if (number == 1 || number % 2 == 0) { + return false; + } + + int noOfNaturalNumbers = 0; + + for (int i = 1; i <= number; i++) { + if (number % i == 0) { + noOfNaturalNumbers++; + } + } + + return noOfNaturalNumbers == 2; + } + + public int noOfPrimeNumbers() { + return noOfPrimeNumbers.intValue(); + } +} diff --git a/core-java-modules/core-java-concurrency-advanced-3/src/test/java/com/baeldung/workstealing/PrimeNumbersUnitTest.java b/core-java-modules/core-java-concurrency-advanced-3/src/test/java/com/baeldung/workstealing/PrimeNumbersUnitTest.java new file mode 100644 index 0000000000..123c29aeee --- /dev/null +++ b/core-java-modules/core-java-concurrency-advanced-3/src/test/java/com/baeldung/workstealing/PrimeNumbersUnitTest.java @@ -0,0 +1,101 @@ +package com.baeldung.workstealing; + + +import org.junit.Test; +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; + +import java.util.concurrent.Executors; +import java.util.concurrent.ForkJoinPool; +import java.util.concurrent.TimeUnit; +import java.util.logging.Logger; + +import static org.junit.Assert.fail; + +public class PrimeNumbersUnitTest { + + private static Logger logger = Logger.getAnonymousLogger(); + + @Test + public void givenPrimesCalculated_whenUsingPoolsAndOneThread_thenOneThreadSlowest() { + Options opt = new OptionsBuilder() + .include(Benchmarker.class.getSimpleName()) + .forks(1) + .build(); + + try { + new Runner(opt).run(); + } catch (RunnerException e) { + fail(); + } + } + + @Test + public void givenNewWorkStealingPool_whenGettingPrimes_thenStealCountChanges() { + StringBuilder info = new StringBuilder(); + + for (int granularity : PrimeNumbers.GRANULARITIES) { + int parallelism = ForkJoinPool.getCommonPoolParallelism(); + ForkJoinPool pool = + (ForkJoinPool) Executors.newWorkStealingPool(parallelism); + + stealCountInfo(info, granularity, pool); + } + logger.info("\nExecutors.newWorkStealingPool ->" + info.toString()); + } + + @Test + public void givenCommonPool_whenGettingPrimes_thenStealCountChangesSlowly() { + StringBuilder info = new StringBuilder(); + + for (int granularity : PrimeNumbers.GRANULARITIES) { + ForkJoinPool pool = ForkJoinPool.commonPool(); + stealCountInfo(info, granularity, pool); + } + logger.info("\nForkJoinPool.commonPool ->" + info.toString()); + } + + private void stealCountInfo(StringBuilder info, int granularity, ForkJoinPool forkJoinPool) { + PrimeNumbers primes = new PrimeNumbers(1, 10000, granularity); + forkJoinPool.invoke(primes); + forkJoinPool.shutdown(); + + long steals = forkJoinPool.getStealCount(); + String output = "\nGranularity: [" + granularity + "], Steals: [" + steals + "]"; + info.append(output); + } + + + @BenchmarkMode(Mode.AverageTime) + @OutputTimeUnit(TimeUnit.MILLISECONDS) + @State(Scope.Benchmark) + @Fork(value = 2, warmups = 1, jvmArgs = {"-Xms2G", "-Xmx2G"}) + public static class Benchmarker { + + @Benchmark + public void singleThread() { + PrimeNumbers primes = new PrimeNumbers(10000); + primes.findPrimeNumbers(); // get prime numbers using a single thread + } + + @Benchmark + public void commonPoolBenchmark() { + PrimeNumbers primes = new PrimeNumbers(10000); + ForkJoinPool pool = ForkJoinPool.commonPool(); + pool.invoke(primes); + pool.shutdown(); + } + + @Benchmark + public void newWorkStealingPoolBenchmark() { + PrimeNumbers primes = new PrimeNumbers(10000); + int parallelism = ForkJoinPool.getCommonPoolParallelism(); + ForkJoinPool stealer = (ForkJoinPool) Executors.newWorkStealingPool(parallelism); + stealer.invoke(primes); + stealer.shutdown(); + } + } +} diff --git a/parent-java/pom.xml b/parent-java/pom.xml index 47965fc36d..e4ec2255c6 100644 --- a/parent-java/pom.xml +++ b/parent-java/pom.xml @@ -27,11 +27,22 @@ commons-io ${commons.io.version} + + org.openjdk.jmh + jmh-core + ${jmh.version} + + + org.openjdk.jmh + jmh-generator-annprocess + ${jmh.version} + 23.0 2.6 + 1.19