Understanding behavior of BlockedIndefinitelyOnMVar exception
brandon.m.simmons at gmail.com
Mon Jul 25 22:24:39 CEST 2011
On Sun, Jul 24, 2011 at 10:07 PM, Edward Z. Yang <ezyang at mit.edu> wrote:
> Excerpts from Felipe Almeida Lessa's message of Sun Jul 24 22:02:36 -0400 2011:
>> Does anything change if you somehow force a GC sometime after "good2"?
>> Perhaps with some calculation generating garbage, perhaps with
>> performGC. IIRC, the runtime detects BlockedIndefinitelyOnMVar on GC.
>> But I'm probably wrong =).
> That's correct.
> resurrectThreads is called after garbage collection on the list of
> threads found to be garbage. Each of these threads will be woken
> up and sent a signal: BlockedOnDeadMVar if the thread was blocked
> on an MVar, or NonTermination if the thread was blocked on a Black
Thanks, Edward. I'm going to take a look at the GHC source and see if
I can grok any of it. Any comment on whether it is correct behavior to
have the exception raised in all the threads attempting a readMVar at
once (if that's actually what's happening), even though an exception
handler will fill the MVar for subsequent threads?
I think I'm not totally clear on what qualifies as "indefinitely"
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