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Re: pwait(1) added

On Tue, Mar 03, 2015 at 01:34:03PM -0500, Christos Zoulas wrote:
> It is a tool from FreeBSD that lets you wait for a set of abtrary pids
> to exit. Do you think this tool is useful or should I remove it? Joerg
> asked for a timeout feature. Is that something that should be added?

My problem with the tool as is: it is a very limited subset of a process
monitor. I question the usefulness in the current form. Lack of timeout
is one issue. Problems we have for pkgsrc bulk builds that could be
solved by a more useful process monitor are:

(1) Finding and reporting orphans. Something leaves a
bonobo-activation-server around, no idea what.

(2) Reporting hanging builds. Typical examples here is lang/onyx, which
often just stops making progress. Another example is lang/mono. The hang
means they don't consume CPU, so normal ulimit -t doesn't apply.
Progress is normally not made by the root of a process hierachy, but
some child. A basic indicator would forking, but overall CPU time could
also work. I'm not sure that can be currently obtained though.

So the real question is what is such a tool supposed to address and what
do we need on the kernel side to enable it.


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