Re: pwait(1) added

[Christian Koch <cfkoch%sdf.lonestar.org@localhost>]

On Tue, Mar 03, 2015 at 07:47:00PM +0100, Joerg Sonnenberger wrote:
> 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.
> 
> Joerg

I wonder, then, if it's more worth it to bring in something like svc(8) from
DragonFly:

    http://leaf.dragonflybsd.org/cgi/web-man?command=svc&section=8

It seems to address (1) pretty well, I think.

-Christian