Thread pooling in AIO/

[Nord, James]

> Although the AsynchronousDatagramChannel is simple I wouldn't 
> expect the performance to be too bad. Is it keeping up with 
> the multicast load or are you seeing packet loss? I recall 
> you were trying out the multicast support in DatagramChannel 
> so I'm curious if this was the same load.

It is keeping up - 
but with CachedPool the load is much higher than with plain old java.net
and much higher than the synchronous nio2.
With a fixedPool (size of 8 on dual quad core box) the load is slightly
higher than java.net and synchronous nio2.

We are seeing the occaisonal lost packets with Async IO - but we're
experimenting to find the best tradeoff of load and packet loss.


> > But that is my point - you have to supply the pool (via the 
> executor) 
> > *and also* to the AsynchronousChannelGroup.
> >
> > E.g. for a fixed pool you need the following:
> > 	ExecutorService executor = Executors.newFixedThreadPool(8);
> > 	AsynchronousChannelGroup group =
> > AsynchronousChannelGroup.withFixedThreadPool(executor, 8);		
> >
> > And for a cached pool you need:
> > 	ExecutorService executor = Executors.newCachedThreadPool();
> > 	AsynchronousChannelGroup group =
> > AsynchronousChannelGroup.withCachedThreadPool(executor, 4);	
> >
> >
> > Why don't we just have
> > 	ExecutorService executor = // whatever executor type 
> you want / fixed 
> > cached etc...
> > 	AsynchronousChannelGroup group =
> > AsynchronousChannelGroup.withThreadPool(executor);
> >   
> Others have also commented on this so there is a
> withThreadPool(executor) in for the next build. It's identical to
> withCachedThreadPool(executor,0) as this method can be 
> invoked with any executor service.

> > Does the group really care if its fixed or cached - doesn't it just 
> > want something to do some work?
> >   
> This page attempts to explain it:
>   http://openjdk.java.net/projects/nio/resources/AsynchronousIo.html

OK.

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