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Re: [PATCH] Attempt at improving the perlipc docs

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Steffen Schwigon
April 19, 2010 16:32
Re: [PATCH] Attempt at improving the perlipc docs
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Leon Timmermans <> writes:
> On Mon, Apr 19, 2010 at 7:02 PM, Maik Hentsche <> wrote:
>> Hi,
>> I was recently confused by the way signal handlers using wait() behave
>> in collaboration with qx() or system().
>> When you have a signal handler for SIGCHLD that calls wait() and use
>> qx() or system() in your parent, the signal handler will be called.
>> Yet, because qx/system already wait()ed for their child the wait in the
>> signal handler would block. I doubt everyone will understand this in
>> the first place. Thus, I wrote an improvement for the documentation to
>> tell people about this issue. Please find the patch attached. It
>> applies to the current git HEAD.
> Mentioning a problem is a good start, but what I'm missing is how to
> deal with this. That is far more valuable (and probably more
> complicated to do in a portable manner).

For me who was also hit by this the mentioning would have already
helped a lot. How to solve the problem was discussed (here?) some
months ago and it was kind of consensus that it's a natural problem
that needs not to be “fixed”. So at least targeting the possible
confusion sounds ok to me.

> Also, adding it three times may be an overkill. Personally don't
> think adding it to the system() documentation too adds much. You
> shouldn't be thinking about this when using system(), you should
> when using wait() IMO.


Steffen Schwigon <>

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