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

[Ryan Newton]

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.

Best,
  -Ryan

On Sun, Aug 12, 2012 at 11:20 AM, Aleksey Khudyakov <
alexey.skladnoy at gmail.com> wrote:

> On 10.08.2012 22:20, Till Berger wrote:
>
>>  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<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?
>>
>>  Looks like this is the case. But reducing test case to reasonable size
> (e.g. removing most of criterion and statistics could be quite difficult
>
>
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