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

[Till Berger]

>>> So I am not sure if this is a bug in Criterion itself, the Statistics
>>> package or any dependency or if I am doing something obviously wrong. I
>>> would be grateful if someone could look into this as it is holding me
>>> back from using Criterion for benchmarking my code.
>>>
>> I would suspect Statistics.Resampling.resample. From quick glance
>> criterion doesn't use any concurrent stuff. I'll try create smaller test
>> case
>
> It looks like I'm wrong. I obtained event log from crashing program  
> and resample completed its work without problems. Crash occured  
> later. Next
> suspect is bootstrapBCA itself. It uses monad-par to obtain parallelism[1].
>
> I tried to create smaller test case without any success.
>
>
>
> [1]  
> https://github.com/bos/statistics/blob/master/Statistics/Resampling/Bootstrap.hs#L84

Replacing "runPar $ parMap" with a simple "map" on that line seems to  
fix the bug. At least I could not reproduce it anymore on several runs  
with my original test case. So it seems to be a bug in the Par monad  
package as this change shouldn't alter the program's behaviour, should  
it?

Regards,
Till