FFI: number of worker threads?

[Seth Kurtzberg]

Simon,

Thanks for the response.

The doc I was referring to is the library haddock doc for Control.Concurrent.

Seth

On Wed, 21 Jun 2006 12:41:52 +0100
Simon Marlow <simonmarhaskell at gmail.com> wrote:

> Seth Kurtzberg wrote:
> > I have a related question.  The docs state that in some environments O/S threads are used when the -threaded flag is used with ghc, and non-O/S threads are used otherwise (presumably these are non-preemptive).  Does this apply as well to the worker threads that are the subject of this email?
> 
> It sounds like the docs are a bit unclear.  Which bit of doc in 
> particular are you referring to?
> 
> forkIO always creates a lightweight thread.  With -threaded, if a thread 
> makes a safe foreign call, then that call might execute concurrently 
> with other threads, because another OS thread (a worker thread) takes 
> over in the runtime.  In the HEAD (which will be 6.6), we now allow 
> multiple OS threads in the runtime, so you also get to run multiple 
> Haskell threads simultaneously, which is particularly useful if you have 
> more than one CPU.
> 
> Cheers,
> 	Simon
>