Mike Machado wrote:
>a snake got into a PG&E power box down the street and took
>out power for 6 ours and our UPS could not hold out that long :)
No backup generator?
Brian E. Lavender wrote:
>I noticed when I run top I have two zombie processes. How do I get
>rid of them without rebooting?
[...I hope this makes sense to someone...]
Okay the deal on zombie processes they are already dead, can not be killed,
and are not a problem (unless you have a few hundred). They only get
created by poorly written code when a program calls fork(2) and the
child process exits but the parent doesn't do the right thing. From the
time the child exits until the parent calls wait there is a "zombie"
process... which holds the return code and stuff from the child.
The parent should do one of two things:
- when kernel sends the parent a signal (SIGCHLD) saying a child's
exit status is ready to wait(2) for, the parent calls should call wait.
- say with sigaction(2) that it doesn't care about the return status
of any of it's children so when they exit the kernel wipes up after
the zombie processes automatically (*).
Older Unix's could easily be wiped out by a few zombies because it
saved all memory associated with a exited child process (zombie)
until it was reaped by a wait call.
So there is a program that is launching child processes and is not
properly cleaning up after them. One of several correct ways to deal
with this:
- fix the misbehaving program
- stop using the misbehaving program
- complain to the authors about the misbehaving program
- exit the misbehaving program periodically
You can figure out which program is spawning these zombie processes
with a pstree or some such. ... Shame it's KDE huh? ;)
TTFN,
Mike Simons
* - the "parent process" of any child and zombie change to process id 1
(init) when the real parent exits. Init periodically calls wait
to reap random zombie processes on the system.
This archive was generated by hypermail 2b29 : Fri Feb 11 2000 - 16:20:22 PST