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Java class for testing usage of fork-join Actions by GraalVM native image generation.
package org.fabri1983.eternity2.forkjoin_solver;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ForkJoinPool;
import java.util.concurrent.RecursiveAction;
* This class intended for testing use of fork-join Actions in Graal native image generation.
* Building steps:
* <pre>
* %JAVA_HOME%/bin/javac
* %GRAALVM_HOME%/bin/native-image --verbose MainHelloWorldNative
* MainHelloWorldNative
* </pre>
public class MainHelloWorldNative extends RecursiveAction {
private static final long serialVersionUID = 1L;
final static int NUM_PROCESSES = 4;
int tag;
CountDownLatch startSignal;
CountDownLatch doneSignal;
public MainHelloWorldNative(int tag, CountDownLatch startSignal, CountDownLatch doneSignal) {
this.tag = tag;
this.startSignal = startSignal;
this.doneSignal = doneSignal;
protected void compute() {
try {
// await for starting signal
// start doing some work
System.out.println("Start task " + tag);
long count = 0L;
for (long x=0, c=Integer.MAX_VALUE; x < c; x++) {
System.out.println("Finish task " + tag + " with count " + count);
} catch (InterruptedException e) {
System.out.println("Exception on compute()");
} finally {
// arguments are passed using the text field below this editor
public static void main(String[] args) {
ForkJoinPool fjpool = new ForkJoinPool(NUM_PROCESSES, ForkJoinPool.defaultForkJoinWorkerThreadFactory, null, true);
// a start signal that prevents any ExplorationAction from proceeding until the orchestrator (this thread) is
// ready for them to proceed
final CountDownLatch startSignal = new CountDownLatch(1);
// a completion signal that allows the driver orchestrator (this thread) to wait until all ExplorationAction
// have completed
final CountDownLatch doneSignal = new CountDownLatch(NUM_PROCESSES);
// submit all fork join tasks
for (int i = 0; i < NUM_PROCESSES; ++i) {
System.out.println("RecursiveAction " + i + " submitted");
fjpool.submit(new MainHelloWorldNative(i, startSignal, doneSignal));
// let all threads proceed
// wait for all tasks to finish
try {
System.out.println("All tasks have finished!");
} catch (InterruptedException e) {
System.out.println("Exception on doneSignal.await()");
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