ExecutorService exception handling

[tpietzsch]

In several places we have code like this:

for ( final Future< Void > f : futures )
{
	try
	{
		f.get();
	}
	catch ( final InterruptedException e )
	{
		e.printStackTrace();
	}
	catch ( final ExecutionException e )
	{
		e.printStackTrace();
	}
}

This should be changed from e.printStackTrace() to something meaningful.

InterruptedException should Thread.currentThread().interrupt() and end method as fast as possible.

What should we do with ExecutionException? Just declare and throw it?

[ctrueden]

What should we do with ExecutionException? Just declare and throw it?

Makes sense to me, where possible. This method is waiting for code to execute, after all. Shouldn't it report when things go wrong?

[hanslovsky]

I fully agree. Should we provide a convenience method that does exactly that so people have an incentive to do that.
Something like

public static < T > List< T > waitForExecution(  List< Future< T > > futures )
throws ExecutionException, InterruptedException
{
	ArrayList< T > result = new ArrayList<>();
	for ( final Future< Void > f : futures )
	{
		try
		{
			result.add( f.get() );
		}
		catch ( final InterruptedException e )
		{
			Thread.currentThread().interrupt();
			throw e; // re-throw?
		}
	}
	return result;
}

What about ExecutorService.invokeAll throws InterruptedException? That should probably be handled in a similar fashion.