[Haskell-cafe] ghc leaking memory?

Joachim Breitner nomeata at debian.org
Mon Mar 8 08:30:29 EST 2010

Hi Simon,

Am Montag, den 08.03.2010, 11:07 +0000 schrieb Simon Marlow:
> > On Sat, Mar 6, 2010 at 11:57 AM, Joachim Breitner<nomeata at debian.org>  wrote:
> >> Hi,
> >>
> >> in Debian, we are having some problems building large libraries (such as
> >> agda, highlighting-kate, xmonad-contrib) on weaker architectures (sparc,
> >> armel, s390) which compile with -fvia-C, especially when building the
> >> profiling libraries.
> >>
> >> In the case of highlighting-kate, there were really issues with the
> >> code: A huge list of words which ghc seemed to try to inline caused it
> >> consuming a lot of memory.
> >>
> >> But in the case of agda, it even fails with relatively small modules:
> >> https://buildd.debian.org/fetch.cgi?pkg=agda&arch=sparc&ver=2.2.6-3&stamp=1267334936&file=log&as=raw
> >>
> >> Now, looking at the memory gauge on my computer while compiling such a
> >> program with Cabal (which compiles all modules in one ghc call), it
> >> looks like it is steadily increasing. I’d expect ghc to free a lot of
> >> memory when it is done with a module, but this does not seem to be the
> >> case.
> >>
> >> Is this a bug (i.e. memory leak) in ghc or expected behavior?
> Can you verify that it is GHC leaking memory, and not gcc?  I recommend 
> turning off -fvia-C in particular unless you're sure that you need it.

Sorry if I was not clear: The issues arise on “strange” architectures
(armel, s390, sparc, mips) where, as far as I know, -fvia-C is the only
option and thus the default. I was not setting this flag myself.

Isn’t GHC calling gcc once for each module? In that case, that can not
leak across modules, can it?


Joachim "nomeata" Breitner
Debian Developer
  nomeata at debian.org | ICQ# 74513189 | GPG-Keyid: 4743206C
  JID: nomeata at joachim-breitner.de | http://people.debian.org/~nomeata
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