[Haskell-cafe] Hugs faster and more reliable than GHC for large list monad 'do' block

[Jeff Heard]

Yes, the GHC compiler will work on older kernels and CentOS kernels if
you bootstrap it with 6.4

On Thu, Aug 6, 2009 at 4:51 PM, Jason Dagit<dagit at codersbase.com> wrote:
>
>
> On Thu, Aug 6, 2009 at 1:39 PM, Henning Thielemann
> <lemming at henning-thielemann.de> wrote:
>>
>> Today a student has shown me a program that consists of a large 'do' block
>> for the list monad. The program looks like
>>
>>   do x1 <- [0..3]
>>      x2 <- [0..2]
>>      ...
>>      x600 <- [0..5]
>>      guard (x1+x2+2*x3 >= 0)
>>      ...
>>      return (x1,x2,....,x600)
>>
>> It was actually generated by another program. The results were:
>>
>>  GHC-6.4 was not able to compile that program at all, because it stopped
>> because of memory exhaustion.
>
> Did you try playing with optimization options?  I think someone just
> mentioned that compiling large amounts of static data in GHC is problematic
> and recommended something like -O0 to prevent GHC from analyzing it.  Of
> course, I wouldn't recommend having unoptimized code, but I'm curious how
> that changes the results here.
>
>
>>
>>  GHC-6.8.2 finished compilation after two minutes but the program aborted
>> quickly because of a corrupt thunk identifier.
>
> Oh that's icky.
>
>>
>>  GHC-6.10 not yet tested.
>>  Hugs-2006 executed the program without complaining and showed the first
>> result after a few seconds: (0,0,0,0,0,...,0).
>>
>> Eventually the program must run on a Linux cluster with a not up-to-date
>> Linux kernel, that is, I suspect newer GHC versions cannot be used due to
>> the 'timer_create' problem. (At least, the 'cabal' executable that I
>> generated with a GHC-6.8.2 had this problem when running on the cluster
>> which reminded me on the problems with GHC-6.8 itself running on older Linux
>> kernels.)
>
> I just googled this and found this:
> http://www.haskell.org/pipermail/glasgow-haskell-users/2008-March/014498.html
> That was linked from this discussion:
> http://www.nabble.com/ghc-6.8.2-and-timer_create-error-td16160635.html
>
> The second link seems to indicate that it's not a problem of antiquity but
> instead one related to what configure finds when building GHC for that
> system.  In other words, it should be possible to make a version of GHC
> locally that doesn't use timer_create and then your student should be good
> to go.
>
> Hope that helps,
> Jason
>
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