Stop threads after a certain time

Question

I want to create a program that wants to do some work simultaneously, but each thread will return back after some time, however I do not want to wait forever so I want to stop all active threads after say 1 minute. Below is what I am doing but I am unable to stop the executing threads:
ThreadPoolExecutor tpe = new ThreadPoolExecutor(
tpSize, tpSize, 5, TimeUnit.MILLISECONDS,
new LinkedBlockingQueue<Runnable>());
Task[] tasks = new Task[nTasks];
for (int i = 0; i < nTasks; i++) {
tasks[i] = new Task(n, "Task " + i);
tpe.execute(tasks[i]);
tpe.shutdown();
System.out.println("Done!");
try {
tpe.awaitTermination(5, TimeUnit.MILLISECONDS);
catch (Exception e) {e.printStackTrace();}
class Task implements Runnable {
long n;
String id;
private long fib(long n) {
if (n == 0)
return 0L;
if (n == 1)
return 1L;
return fib(n - 1) + fib(n - 2);
public Task(long n, String id) {
this.n = n;
this.id = id;
public void run() {
Date d = new Date();
DateFormat df = new SimpleDateFormat("HH:mm:ss:SSS");
long startTime = System.currentTimeMillis();
d.setTime(startTime);
System.out.println("Starting task " + id + " at " + df.format(d));
System.out.print("Fib: " + fib(n));
long endTime = System.currentTimeMillis();
d.setTime(endTime);
System.out.println(" Ending task " + id + " at " + df.format(d) + " after " + (endTime - startTime) + " milliseconds");
How come the threads do not stop especially when I have set a 5 Millisecond timeout?
How do I go about stopping active threads?
Message was edited by:
dawuad

Answer 1

I want to create a program that wants to do some work simultaneously, but each thread will return back after some time, however I do not want to wait forever so I want to stop all active threads after say 1 minute. Below is what I am doing but I am unable to stop the executing threads:
ThreadPoolExecutor tpe = new ThreadPoolExecutor(
tpSize, tpSize, 5, TimeUnit.MILLISECONDS,
new LinkedBlockingQueue<Runnable>());
Task[] tasks = new Task[nTasks];
for (int i = 0; i < nTasks; i++) {
tasks = new Task(n, "Task " + i);
tpe.execute(tasks);
tpe.shutdown();
System.out.println("Done!");
try {
tpe.awaitTermination(5, TimeUnit.MILLISECONDS);
catch (Exception e) {e.printStackTrace();}
class Task implements Runnable {
long n;
String id;
private long fib(long n) {
if (n == 0)
return 0L;
if (n == 1)
return 1L;
return fib(n - 1) + fib(n - 2);
public Task(long n, String id) {
this.n = n;
this.id = id;
public void run() {
Date d = new Date();
DateFormat df = new SimpleDateFormat("HH:mm:ss:SSS");
long startTime = System.currentTimeMillis();
d.setTime(startTime);
System.out.println("Starting task " + id + " at " + df.format(d));
System.out.print("Fib: " + fib(n));
long endTime = System.currentTimeMillis();
d.setTime(endTime);
System.out.println(" Ending task " + id + " at " + df.format(d) + " after " + (endTime - startTime) + " milliseconds");
How come the threads do not stop especially when I have set a 5 Millisecond timeout?
How do I go about stopping active threads?
Is ThreadPoolExecutor right for me?