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Date: Fri, 15 Mar 2013 17:02:32 +0100
From: oliver <oliver@first.in-berlin.de>
To: Matej Kosik <5764c029b688c1c0d24a2e97cd764f@gmail.com>
Cc: caml-list@inria.fr
Message-ID: <20130315160232.GB5664@siouxsie>
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X-Scanned-By: MIMEDefang_at_IN-Berlin_e.V. on 192.109.42.8
Subject: Re: [Caml-list] signal-unsafety of %!

On Fri, Mar 15, 2013 at 03:56:52PM +0000, Matej Kosik wrote:
> On 15/03/13 14:36, oliver wrote:
> > On Fri, Mar 15, 2013 at 02:30:29PM +0000, Matej Kosik wrote:
> >> Hi,
> >>
> >> When I compile the attached program
> >>
> >>   (with compilers available directly from Debian's repositories)
> >>
> >> I can observe a (non-deterministic) deadlock.
> >>
> >> When I remove
> >>
> >> 	%!
> >>
> >> from the printf function inside the SIGALRM's handler, the deadlock never seem to occur.
> >>
> >> Obviously, interference can be easily introduced in concurrent programs; I was just surprised that even something like
> > [...]
> > 
> > 
> > Whats going on today?
> > 
> > Use Unix.sigprocmask.
> > 
> > Ciao,
> >    Oliver
> > 
> 
> Right, printf simply isn't reentrant.
> 
> (what I was observing was a program that was busy-looping, but stuck. I guess because internal shared data might have been damaged.).

Ah, yes, you used it inside the signal handler.
Have overlooked it.

Ciao,
   Oliver