Re: 2.4.29: Zombies not detected or removed

[Marcelo Tosatti <marcelo.tosatti@cyclades.com>]

On Mon, Feb 21, 2005 at 12:32:33PM +0100, Schwarz wrote:
> 
> 
> Hi everyone,
> 
> since 2.4.29 we discovered a strange behaviour.
> 
> Severall tasks are no longer detected as destroyed.
> means, these tasks have ended but arn't removed from
> the processlist.
> 
> An example from today:
> 
> [root@d102 ]# date
> Mon Feb 21 10:14:06 CET 2005
> [root@d102 ]# strace -p 33326
> attach: ptrace(PTRACE_ATTACH, ...): No such process
> [root@d102 ]# ps aux | grep 29579
> 33326    29579  0.0  0.2 10696 4332 ?        SN   10:11   0:00 -f
> /home/ajondoco
> root     19168  0.0  0.0  1768  628 pts/0    S    10:15   0:00 grep 29579
> [root@d102 ]# strace -p 33326
> attach: ptrace(PTRACE_ATTACH, ...): No such process
> [root@d102 ]#
> 
> As you can see the process in question "29579" was started
> 10:11 , but as finished its activity already. After 10
> minutes it's still not removed from the processlist and 
> it's not detected as a zombie.  
> 
> the task was an Apache 1.3.3 child over a wrapper calling php
> with -f option. 
> 
> We think it's unimportant if its forked or execev(),because on
> another maschine it was not even an apache invoked. 
> 
> Some of the these processes enter zombie state, but were never
> fully removed !
> 
> Any ideas why it and what happens?

I don't, no. Quite strange.

Can you reproduce this? If sys_ptrace() failed the process is not present. 

Can you please "cat /proc/<pid>/status" when ptrace fails but the ps shows the 
process existance ?

I suppose you haven't been seeing this behaviour with v2.4.28 ?