Question

In my method I start multiple threads and then wait until they finish their work (something like fork-join pattern).

using (var countdownEvent = new CountdownEvent(runningThreadsCount))
{
    for (int i = 0; i < threadsCount; i++)
    {
        var thread = new Thread(new ThreadStart(delegate
                                                {
                                                   // Do something
                                                   countdownEvent.Signal(); 
                                                }));

        thread.Start();
    }

    countdownEvent.Wait();
}

Now I need to be able to catch exception in this threads (lets assume that // Do something may throw an exception), pass exception to the main thread, unblock it (since it is waiting on countdownEvent) and re-throw the exception.

What is the most elegant way to achieve that?

Answer 1

Solved my problem with Tasks API. Thanks flq for suggestion!

var cancellationTokenSource = new CancellationTokenSource();
var tasks = new Task[threadsCount]
for (int i = 0; i < threadsCount; i++)
{
    tasks[i] = Task.Factory.StartNew(
        delegate
            {
                // Do something
            }, cancellationTokenSource.Token);
}

try
{
    Task.WaitAll(tasks);
}
catch (AggregateException ae)
{
    cancellationTokenSource.Cancel();
    throw ae.InnerExceptions[0];
}