[web-devel] problem with yesod, persist and enumerations

Anton Cheshkov acheshkov at gmail.com
Sat Apr 16 19:35:43 CEST 2011


I worry about the future of haskell (ghc). I know at least three problems

- not memory releasing
- optimization issues
- multi-core execution issue  (works bad with more than 4 core)

sadly ... (

2011/4/16 Michael Snoyman <michael at snoyman.com>

>
>
> On Sat, Apr 16, 2011 at 5:54 PM, Chris Casinghino <
> chris.casinghino at gmail.com> wrote:
>
>> On Sat, Apr 16, 2011 at 10:45 AM, Greg Weber <greg at gregweber.info> wrote:
>> >  Are you compiling with the development server or doing a cabal build/
>>
>> I'm doing a cabal build.  To reproduce this, I run (cabal configure &&
>> cabal build) from the command line in the project directory.
>>
>>
> I can confirm that this happens. However, it *only* happens when building
> with cabal. When building with "ghc --make", using runghc or
> wai-handler-devel, everything works fine. So I tried compiling with "ghc
> --make -O", and sure enough the same bug appeared.
>
> I don't think there's anything we can do in the libraries to avoid this, it
> looks like a bug in GHC. You can modify your ghc-options line in the cabal
> file to pass in "-O0" to disable optimizations, though this is obviously not
> optimal (bad pun intended). I think we need to report this to the GHC team.
>
> I know virtually nothing about GHC internals, but in case this means
> something to someone else, here's some of the output from "ghc --make -O -v
> test.hs":
>
> *** Simplify:
> *** CorePrep:
> *** ByteCodeGen:
> *** Desugar:
>     Result size = 8699
> *** Simplifier SimplMode {Phase = InitialPhase [Gentle],
>                       no inline,
>                       rules,
>                       eta-expand,
>                       no case-of-case} max-iterations=4:
>     Result size = 9841
>     Result size = 9797
>     Result size = 9797
> *** Specialise:
>     Result size = 9797
> *** Float out(FOS {Lam = Just 0, Consts = True, PAPs = False}):
>     Result size = 13259
> *** Float inwards:
>     Result size = 13259
> *** Simplifier SimplMode {Phase = 2 [main],
>                       inline,
>                       rules,
>                       eta-expand,
>                       case-of-case} max-iterations=4:
>     Result size = 677741
>     Result size = 850762
>     Result size = 1028928
>     Result size = 1028928
> *** Simplifier SimplMode {Phase = 1 [main],
>                       inline,
>                       rules,
>                       eta-expand,
>                       case-of-case} max-iterations=4:
>     Result size = 1026905
>     Result size = 1026876
>     Result size = 1026876
> *** Simplifier SimplMode {Phase = 0 [main],
>                       inline,
>                       rules,
>                       eta-expand,
>                       case-of-case} max-iterations=4:
>
> Michael
>
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>
>


-- 
Best regards,
Cheshkov Anton
Phone: +7 909 005 18 82
Skype: cheshkov_anton
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