Stubborn Processes

[stevenerat at yahoo.com (Steven Erat)]

Hello, 

This is my first post on this list, although I've attended BLU meetings
off and on since 99, including last night's.

I'm trying to help a client with a (C++ based) web application server on
Redhat 7.2 and Apache 1.3.20 and the client has encountered a situation
that I've not seen before.  

The app server has a mechanism to restart itself if the request pool
stacks up with hung threads, and it logs when an attempt to do so is made.
 The app server is reporting that is restarting itself based on this
mechanism, however the client finds that the same processes with same
process ids are continuing to run though.  

The part that I've never seen is that while logged in as root the client
reports that he cannot kill the processes (after already having tried the
manual stop script). The client reports that after determining the parent
process and then try to kill it with a kill -9 <pid>, kill -15 <pid>, or a
killall <processname> that the processes do not die.  

My question is how can it be that root cannot kill a process?  

Conceivably, the app server might be making calls to custom-built,
external C++ routines though the app server API to do so, and maybe that
C++ routine could be somehow nicing the priority of the app server pid to
set it higher than the kernel pid, but that's a real stretch and the
client says they are not using such C++ routines.

Any suggestions or explanations would be very much appreciated.

Thanks,
Steven Erat



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