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Bug#575534: libc6: periodic timers hang fork()

Hi Aruelien,

Am Samstag, den 15.05.2010, 12:28 +0200 schrieb Aurelien Jarno:
> On Fri, May 14, 2010 at 10:38:17PM +0200, Joachim Breitner wrote:
> > I’d like to follow up on this issue. According to the libc bug reporting
> > guidelines, one should hear from the Debian maintainers whether the bug
> > could possibly be Debian-specific before reporting them upstream. Can
> > you comment on that?
> > 
> > The bug might look like it is a weird corner case, but it causes serious
> > trouble with building large haskell packages on some arches, and thus
> > the transition of such packages to testing.
> > 
> I am not sure it is GNU libc bug, and I am not sure there is an
> acceptable solution. The timer interrupts the clone syscall itself, so
> everything happens in the kernel.
> Maybe stopping the timer before the clone syscall and restoring it
> after is something acceptable?

I’m by far not an expert in these areas, but seeing the same problem
happen with different uses (profiling a C binary, running Haskell code)
seems that the problem is either in the shared code (the libc), or in
the usage of it.

In the example C code with profiling, if the bug is not a libc bug, then
it is a bug in the compiler generating the profiling code? Or should it
be libc’s responsibility to disable timers while running clone? Is that
even possible? Would this cause other problems?

I created a ticket against ghc, the haskell compiler, and asked if they
think they should and can disable the timer as well:


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

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