[Haskell-cafe] Possible bug in Criterion or Statistics package

Aleksey Khudyakov alexey.skladnoy at gmail.com
Mon Aug 13 18:32:40 CEST 2012

On 13.08.2012 20:26, Till Berger wrote:
>> Terrible! Quite sorry that this seems to be a bug in the monad-par
>> library.
>> I'm copying some of the other monad-par authors and we hopefully can
>> get to
>> the bottom of this. If it's not possible to create a smaller reproducer,
>> is it possible to share the original test that triggers this problem? In
>> the meantime, it's good that you can at least run without parallelism.
> I have attached an even simpler test that directly uses the monad-par
> library. The function "test" simply adds one to a list of numbers
> indefinitely using "parMap" and displays every intermediate result. When
> running the program on multiple cores the bug occurs every time for me.
> Thanks for looking into this!
I've tried your test case and it indeed fails every time. Usually it 
fails with "blocked on MVar indefinitely" but sometimes it fails with:

test: Impossible state in globalWorkComplete.

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