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

Bryan O'Sullivan bos at serpentine.com
Wed Nov 28 17:30:07 EST 2007

Andrew Coppin wrote:
> Dan Weston wrote:
>> Silly or not, if I compile with -threaded, I always link in the 
>> one-liner C file:
>>   char *ghc_rts_opts = "-N2";
> Ah... you learn something useful every day! I was going to ask on IRC 
> whether there's any way to do this - but now I don't need to bother. :-)

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.


This variable is new in GHC 6.8.1 (thanks, Simon!), so don't try to use 
it with an older release.


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