Process handlers, and zombies, or preap(1)

[John Baldwin]

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).

-- 
John Baldwin