[Haskell-cafe] 7.10.2 : Compilation slowdown.

[aditya siram]

I unfortunately don't have time to pare it down to a small example, but
fortunately I found that the latest HList on Hackage exhibits the same
approximate behavior.

When building the tests for HList-0.4.1.0, on 7.10.2 the module
`Properties.LengthDependentSplice` (
http://hackage.haskell.org/package/HList-0.4.1.0/src/examples/Properties/LengthDependentSplice.hs)
takes 2m30secs to compile. The same file takes ~50secs on 7.8.4.

Thanks!
-deech

On Wed, Sep 30, 2015 at 6:22 PM, David Kraeutmann <kane at kane.cx> wrote:

> Can you post a minimal example that exhibits the compile time increase?
>
> On Thu, Oct 1, 2015 at 12:25 AM, aditya siram <aditya.siram at gmail.com>
> wrote:
> > I'm not using any -O* flags and I'm not using Template Haskell. Not sure
> if
> > this means anything but I do have the context-stack set to 220.
> >
> > Thanks!
> > -deech
> >
> > On Wed, Sep 30, 2015 at 8:47 AM, Carter Schonwald
> > <carter.schonwald at gmail.com> wrote:
> >>
> >> Have you checked how changing the optimization level affects build
> times?
> >> Are you using template Haskell?
> >>
> >>
> >> On Tuesday, September 29, 2015, aditya siram <aditya.siram at gmail.com>
> >> wrote:
> >>>
> >>> Hi all,
> >>> Since upgrading to 7.10.2 from 7.8.4 I'm seeing a significant increase
> in
> >>> compilation time. I understand this is a known issue but since I'm
> seeing
> >>> something like a 3x slowdown but not across the board, I thought I'd
> ask.
> >>>
> >>> Compilation time for the library I'm writing has remained about the
> same.
> >>> I am seeing the slowdown when compiling executables that use the
> library.
> >>> There are no other dependencies except base so I'm guessing it
> something in
> >>> my library causing the issue.
> >>>
> >>> I lean heavily on the FFI, OverlappingInstances and HList style
> >>> programming in my library which leads me to believe that one of these
> is
> >>> causing it. I am seeing no difference in compilation speeds by adding
> the
> >>> per instance OVERLAPPING pragmas.
> >>>
> >>> Can anyone advise or instruct me on how to profile the compiler?
> >>>
> >>> Thanks!
> >>> -deech
> >>>
> >>>
> >
> >
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> >
>
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