Process handlers, and zombies, or preap(1)

[John Baldwin]

On Tuesday, April 01, 2014 10:28:02 am Chris H wrote:
> > On Monday, March 31, 2014 4:06:43 pm Chris H wrote:
> >> Greetings,
> >>  I'm evaluating/experimenting on releng_9. The install, and now
> >> custom kernel have noting exotic, or anything out of the ordinary.
> >> top(1), and ps(1) indicate a (1) zombie, or <defunct> process. On
> >> my releng_8 systems, when I occasionally encounter one of these,
> >> they soon disappear (are reaped) from the process table. While I
> >> have not investigated this far enough on both versions to determine
> >> whether the parent process reaped the child on the releng_8 systems,
> >> and the parent on releng_9 is simply an irresponsible parent, eg;
> >> a different parent. Before I do, I was wondering if there was any
> >> specific difference between the 2 versions that might cause better
> >> handling of such situations. While I recognize that resource
> >> starvation is HIGHLY unlikely, except by perhaps a rouge parent
> >> spawning multitudes of zombies. I thought it might be useful for
> >> "housekeeping" to 1) provide a process table housekeeper (zombie
> >> reaper), or 2) create a system utility/command like SunOS/OpenSolaris
> >> has; preap(1).
> >>
> >> http://www.freebsd.org/cgi/man.cgi?query=preap&manpath=SunOS+5.10
> >>
> >> Thank you for your time, and consideration.
> >
> > Nothing is different with child processes in 9 vs 8.  It is most
> > likely a misbehaving parent (or the parent is stuck or hung).
> 
> Hello, John, and thank you for the reply.
> Right you are. Julian Elischer was kind enough to remind me that
> ps -alx
> would give me the information I needed to find the seemingly
> "lazy" parent process. But not before I had already (re)created
> a (Free)BSD version of preap(1), and cleared the entry from the
> proc table.
> However, it re-appeared again. So this time I traced it to it's
> parent, and now I can deal with it /properly/. It's an old port
> who's development was taken over by a Windows developer. So he
> doesn't have access to the *NIX-isms. I'll see if I can find
> the time to coordinate some effort(s) to clean it up, or branch
> a NIX version.
> 
> Thank you /very/ much for addressing my original question.

sysutils/pstree from ports can also be useful for figuring this
sort of thing out btw.

-- 
John Baldwin