ndmitchell at gmail.com
Sat Jun 26 10:32:42 EDT 2010
> My understanding was that this error occurred when one thread was blocked,
> waiting on an MVar, and no other thread in the program has a reference to
> that MVar (this can be detected during GC). Ergo, the blocked thread will
> end up waiting forever because no-one can ever wake it up again.
That certainly seems a sensible rule - I'll see if that can help me
debug my problem.
> Do you actually have use of MVars in your program directly, or are they
> being used via a library? And do you at least know which thread is
> throwing this exception? It should be catchable so you can probably wrap
> the arguments to your forkIO calls with a catcher than indicates which
> thread blew up.
I use MVar's directly, use Chan/QSem, and have about 5 concurrency
data types built on top of MVar's - they're everywhere.
I also have a thread pool structure, so tasks move between threads
regularly - knowing which thread got blocked isn't very interesting.
Thanks for the information,
More information about the Glasgow-haskell-users