multithreading - Catching thread exceptions from Java ExecutorService

Question

I'm working on a software development framework for parallel computing JavaSeis.org. I need a robust mechanism for reporting thread exceptions. During development, knowing where exceptions came from has high value, so I would like to err on the side of over-reporting. I would also like to be able to handle Junit4 testing in threads as well. Is the approach below reasonable or is there a better way ?

import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;

public class TestThreadFailure {

  public static void main(String[] args) {
    int size = 1;
    ExecutorService exec = Executors.newFixedThreadPool(size);
    ThreadFailTask worker = new ThreadFailTask();
    Future<Integer> result = exec.submit(worker);
    try {
      Integer value = result.get();
      System.out.println("Result: " + value);
    } catch (Throwable t) {
      System.out.println("Caught failure: " + t.toString());
      exec.shutdownNow();
      System.out.println("Stack Trace:");
      t.printStackTrace();
      return;
    }
    throw new RuntimeException("Did not catch failure !!");
  }

  public static class ThreadFailTask implements Callable<Integer> {
    @Override
    public Integer call() {
      int nbuf = 65536;
      double[][] buf = new double[nbuf][nbuf];
      return new Integer((int) buf[0][0]);
    }
  }
}

Answer 1

Consider calling execute() instead of submit() on the ExecutorService. A Thread invoked with execute() will invoke the Thread.UncaughtExceptionHandler when it fails.

Simply make a ThreadFactory that installs a Thread.UncaughtExceptionHandler on all Threads and then invoke your work with execute() on the ExecutorService instead of submit().

Have a look at this related stack overflow question.