Xref: utzoo comp.unix.questions:6805 comp.unix.wizards:8177 comp.unix.microport:570
Path: utzoo!mnetor!uunet!husc6!cmcl2!nrl-cmf!ames!killer!richardh
From: richardh@killer.UUCP (Richard Hargrove)
Newsgroups: comp.unix.questions,comp.unix.wizards,comp.unix.microport
Subject: Re: Trouble killing processes in SysV/AT
Message-ID: <3967@killer.UUCP>
Date: 1 May 88 15:13:26 GMT
References: <3950@killer.UUCP> <3951@killer.UUCP>
Organization: The Unix(R) Connection, Dallas, Texas
Lines: 35
Summary: also seen under old Xenix version; some musings

In article <3951@killer.UUCP>, wnp@killer.UUCP (Wolf Paul) writes:
> Can anyone enlighten me as to what causes a process to become "immortal"
> in System VR2,  or Microport UNIX System V/AT, to be more specific?
> 
> I have encountered this a number of times, where it would be impossible
> even for root to kill a process; 

Wolf,

While I've never seen this under Microport SYS V/AT, I have seen it under
Intel Xenix 3.4 (SYS III based). Like you, I was amazed when the command

kill -9 pid

executed by root didn't remove the process entry from the ps display. However
repeated invocations of "ps -elf" indicated that the process was always 
inactive and that it had a nice value of 20. Of course this could be subject
to error since my sample rate didn't approach the system's time-slice
quantum ;-). Actually there were two different activations of the same program,
the quite large Intel tool bld386 - both of which had terminated abnormally
due to system errors (ran out of disk space.) Also, there didn't appear to 
be any real system performance degradation (80286-based '(U|Xe)nix' systems 
suffer performance degradation very rapidly as I'm sure you've observed.)

Not having access to source code, I was left to speculate on what I observed.
I came to the conclusion that the actual processes were gone, but some
table or tables maintained by the kernel had been corrupted. I'm assuming
that ps reports only what it finds in the table(s) and that it doesn't check
their validity. As you experienced, rebooting the system cleared up
everything. If my diagnosis is correct, I know of no other way to clear up
the problem, though I would like to more about what was going on.

richard hargrove
...!{ihnp4 | codas | cbosgd}!killer!richardh
--------------------------------------------