Increased memory usage with GHC 7.10.1

Simon Peyton Jones simonpj at microsoft.com
Fri May 1 15:05:04 UTC 2015


It would be amazingly helpful if someone (anyone) could diagnose a bit.

It may be a bug in GHC but it may also be a bug in the pragmas in a library.   If someone can produce evidence for the former, I’ll gladly look at it.

Simon

From: Greg Weber [mailto:greg at gregweber.info]
Sent: 01 May 2015 16:01
To: Simon Peyton Jones
Cc: Paolino; George Colpitts; Manuel Chakravarty; glasgow-haskell-users at haskell.org
Subject: Re: Increased memory usage with GHC 7.10.1

We have observed issues with compile-time inlining taking much longer in newer versions of GHC in some cases
https://github.com/larskuhtz/toCaseFoldBuildTimes
This particular issue was reported to the text repo: https://github.com/bos/text/issues/116

On Fri, May 1, 2015 at 7:49 AM, Simon Peyton Jones <simonpj at microsoft.com<mailto:simonpj at microsoft.com>> wrote:
It would be great if someone could

•         create a ticket for Paolio

•         investigate what is happening
This smaller test case uses Repa, so it’s not clear that GHC is doing anything wrong. Maybe repa is inlining too much?  We need insight.

Thanks

SImon

From: Glasgow-haskell-users [mailto:glasgow-haskell-users-bounces at haskell.org<mailto:glasgow-haskell-users-bounces at haskell.org>] On Behalf Of Paolino
Sent: 01 May 2015 15:30
To: George Colpitts
Cc: glasgow-haskell-users at haskell.org<mailto:glasgow-haskell-users at haskell.org>
Subject: Re: Increased memory usage with GHC 7.10.1

here is another file , which is small, which cannot be compiled within 4GB  memory.

https://raw.githubusercontent.com/benl23x5/gloss/master/gloss-examples/raster/Fluid/src-repa/Stage/Linear.hs
I'd just want to add that this problem is a nasty one if one doesn't set the max heap: a remote machine frozen that must be rebooted is not a nice adventure , hoping the crash remains confined to the vm.
hth, paolino



2015-05-01 15:31 GMT+02:00 George Colpitts <george.colpitts at gmail.com<mailto:george.colpitts at gmail.com>>:
Should we recommend that all library developers compile their libraries with a max heap of 4G (to pick an arbitrary number) so that we can catch some of these issues earlier?

On Fri, May 1, 2015 at 5:42 AM, Paolino <paolo.veronelli at gmail.com<mailto:paolo.veronelli at gmail.com>> wrote:
Hello, I'm using ghc 7.10.1 to compile OpenGLRaw which is now impossible with -O1 and -O2 due to "ghc : out of memory error" on a 4GB linux host. The file making memory explode is  Graphics.Rendering.OpenGL.Raw.Functions<https://hackage.haskell.org/package/OpenGLRaw-2.4.1.0/docs/src/Graphics-Rendering-OpenGL-Raw-Functions.html>. With -O0 it uses 600 MB.
The file is really huge, but I could compile it with prior versions of ghc.
Regards
paolino

2015-04-17 1:33 GMT+02:00 David Laing <dave.laing.80 at gmail.com<mailto:dave.laing.80 at gmail.com>>:
Hi all,
I've been playing around with profiling GHC recently, so I thought I'd chime in with a pointer that might save people searching for the right docs - you could configure a cabal sandbox to work with multiple version of ghc, which I've found useful:

https://www.haskell.org/cabal/users-guide/installing-packages.html#sandboxes-advanced-usage

Cheers,

Dave

On Fri, Apr 17, 2015 at 6:01 AM, Michal Terepeta <michal.terepeta at gmail.com<mailto:michal.terepeta at gmail.com>> wrote:
Hi Richard,

Thanks updating the ticket! What I did was: build GHC HEAD/7.8.4 with build flavor 'prof' then get the haskell-src-exts sources, install the dependencies and finally add +RTS -p -RTS to the cabal file and compile it, the resulting ghc.prof contains the profiling information.

For anyone interested about CallArity slowness, the problem is tracked in https://ghc.haskell.org/trac/ghc/ticket/10293

Cheers,
Michal

On Wed, Apr 15, 2015 at 1:40 AM Richard Eisenberg <eir at cis.upenn.edu<mailto:eir at cis.upenn.edu>> wrote:
I've pasted Michal's numbers in #9630, which seems like a good place to track this. Michal, would you mind fleshing out a bit precisely what you did to get those numbers? That would be helpful (though you've already been very helpful indeed in getting the data together)!

Thanks,
Richard

On Apr 14, 2015, at 9:09 PM, Joachim Breitner <mail at joachim-breitner.de<mailto:mail at joachim-breitner.de>> wrote:

> Hi,
>
> Am Dienstag, den 14.04.2015, 21:54 +0200 schrieb Michal Terepeta:
>> On Mon, Apr 13, 2015 at 10:34 PM, Christiaan Baaij
>> <christiaan.baaij at gmail.com<mailto:christiaan.baaij at gmail.com>> wrote:
>>> Actually, I meant only with -fno-specialise.
>>
>> Done. Helps quite a bit but CallArity is still a pretty expensive.
>
> I’m on that, and I think I have a quite neat fix for it. I’ll report on
> that in the trac ticket:
> https://ghc.haskell.org/trac/ghc/ticket/10293#comment:4
>
> Greetings,
> Joachim
>
> --
> Joachim “nomeata” Breitner
>  mail at joachim-breitner.de<mailto:mail at joachim-breitner.de> • http://www.joachim-breitner.de/
>  Jabber: nomeata at joachim-breitner.de<mailto:nomeata at joachim-breitner.de>  • GPG-Key: 0xF0FBF51F
>  Debian Developer: nomeata at debian.org<mailto:nomeata at debian.org>
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