[Haskell-cafe] Re: Waiting for thread to finish

[Andrew Coppin]

Bryan O'Sullivan wrote:
> But wait, there's more!  If you're using the threaded RTS, you often 
> need to know how many threads you can run concurrently, for example to 
> explicitly split up a compute-bound task.  This value is exposed at 
> runtime by the numCapabilities variable in the GHC.Conc module.
>
> http://www.haskell.org/ghc/docs/latest/html/libraries/base-3.0.0.0/GHC-Conc.html#v%3AnumCapabilities 
>
>
> This variable is new in GHC 6.8.1 (thanks, Simon!), so don't try to 
> use it with an older release.

Hmm... I was *sure* this was exposed in Control.Concurrent already... 
but, apparently, no. It seems you can only get at it from GHC.Conc. 
That's kind of a pitty... oh well! ;-)