Created
September 13, 2018 09:46
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Java 8 parallelStream & ForkJoinPool
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import java.util.List; | |
import java.util.concurrent.Callable; | |
import java.util.concurrent.ForkJoinPool; | |
import java.util.stream.Collectors; | |
import java.util.stream.LongStream; | |
public class ParallelStreamTest { | |
private static boolean verbose = false; | |
private static int size = 50; | |
private static int sleepTime = 100; | |
public static void main(String[] args) throws Exception { | |
try { | |
stats(ForkJoinPool.commonPool()); | |
List<Long> list0 = LongStream.rangeClosed(1, size).boxed().collect(Collectors.toList()); | |
System.out.println("list0: " + list0); | |
System.out.println(""); | |
Callable<List<Long>> sequentalTask = () -> list0.stream().map(ParallelStreamTest::calculate).collect(Collectors.toList()); | |
Callable<List<Long>> parallelTask = () -> list0.parallelStream().map(ParallelStreamTest::calculate).collect(Collectors.toList()); | |
System.out.println("SEQUENTAL TASK:"); | |
long before = System.currentTimeMillis(); | |
List<Long> list1 = sequentalTask.call(); | |
System.out.println("elapsedTime: " + (System.currentTimeMillis() - before)); | |
System.out.println("list1: " + list1); | |
System.out.println(""); | |
System.out.println("PARALLEL TASK:"); | |
before = System.currentTimeMillis(); | |
List<Long> list2 = parallelTask.call(); | |
System.out.println("elapsedTime: " + (System.currentTimeMillis() - before)); | |
System.out.println("list2: " + list2); | |
System.out.println(""); | |
stats(ForkJoinPool.commonPool()); | |
System.out.println("PARALLEL TASK FORK-JOIN POOL:"); | |
ForkJoinPool threadPool = new ForkJoinPool(); | |
List<Long> list3 = threadPool.submit(parallelTask).get(); | |
System.out.println("elapsedTime: " + (System.currentTimeMillis() - before)); | |
System.out.println("list3: " + list3); | |
System.out.println(""); | |
stats(threadPool); | |
System.out.println("SEQUENTAL TASK FORK-JOIN POOL:"); | |
threadPool = new ForkJoinPool(); | |
List<Long> list4 = threadPool.submit(sequentalTask).get(); | |
System.out.println("elapsedTime: " + (System.currentTimeMillis() - before)); | |
System.out.println("list4: " + list4); | |
System.out.println(""); | |
stats(threadPool); | |
} catch (Exception e) { | |
System.out.println("" + e); | |
} | |
} | |
private static long calculate(long l){ | |
try { | |
if (verbose) System.out.println("[" + Thread.currentThread().getName() + "] " + l); | |
Thread.sleep(sleepTime); | |
} catch (InterruptedException e) { /**/ } | |
return l * 10; | |
} | |
private static void stats(ForkJoinPool fjp) { | |
System.out.println("availableProcessors: " + Runtime.getRuntime().availableProcessors()); | |
System.out.println(fjp.toString()); | |
} | |
} |
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