[grapefruit] SystemMonitor

Wolfgang Jeltsch g9ks157k at acme.softbase.org
Tue Apr 7 10:09:33 EDT 2009

Am Montag, 6. April 2009 14:15 schrieb Peter Verswyvelen:
> Can you tell a bit about the fix? Or is it clear from a diff on the
> sources?

I had accidently written readMVar instead of takeMVar in some module.

I use MVars only because I fear that using IORefs might result in race 
conditions. I don’t know whether GHC automatically multithreads expression 
evaluation. If it does, using IORefs might be dangerous when they are 
accessed from within unsafePerformIO. Does anybody know more about the 
relationship between expression evaluation, multithreading and IORefs?

Best wishes,

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