[ale] Boot script becomes a zombie?

Lightner, Jeff jlightner at water.com
Mon Feb 22 15:51:01 EST 2010


Interesting; is it a Sendmail job that is running or are you kicking of the daemon from cron or maybe have some sort of Sendmail daemon restart in cron that kicked off when Sendmail died?   I don't usually see Sendmail running as a child of cron.

I wasn't saying you should kill the parent - just saying that it does *sometimes* get rid of the child.   Since there is no guarantee it will get rid of the zombie and the zombie doesn't hurt anything by being there (usually) you could just ignore it.   The only time I really let zombies worry me is when I see dozens of them as it is typically an indication something is going horribly wrong (and of course they'll fill up process tables if there are enough of them).  The only sure way to get rid of a zombie is to reboot.

-----Original Message-----
From: ale-bounces at ale.org [mailto:ale-bounces at ale.org] On Behalf Of James Sumners
Sent: Monday, February 22, 2010 3:11 PM
To: Atlanta Linux Enthusiasts - Yes! We run Linux!
Subject: Re: [ale] Boot script becomes a zombie?

I'm loathe to kill the parent process because it has a second child --
sendmail. I kind of want sendmail running.

$ ps -eH
*snip*
 1599 ?        00:00:00   cron
 1606 ?        00:00:00     cron
 1614 ?        00:00:00       boot_fastcgi_bi <defunct>
 1629 ?        00:00:00       sendmail
*snip*

On Mon, Feb 22, 2010 at 2:58 PM, Lightner, Jeff <jlightner at water.com> wrote:
> In that situation sometimes (though not always) killing the parent will
> get rid of the zombie.
>
> As an HP presenter used to say at the start of his performance
> presentations:
> You can't kill a zombie because IT'S ALREADY DEAD!
>
> -----Original Message-----
> From: ale-bounces at ale.org [mailto:ale-bounces at ale.org] On Behalf Of
> Michael H. Warfield
> Sent: Monday, February 22, 2010 2:29 PM
> To: Atlanta Linux Enthusiasts - Yes! We run Linux!
> Cc: mhw at wittsend.com
> Subject: Re: [ale] Boot script becomes a zombie?
>
> On Sun, 2010-02-21 at 23:05 -0500, James Sumners wrote:
>> I have a script that looks runs several other scripts in turn. I use
>> this script to startup several FastCGI processes. This is the script:
>
>> ##########
>> #!/bin/bash
>> find /var/www/fastcgi/scripts/ -type f -execdir '{}' 2>&1 1>/dev/null
> \;
>> return $?
>> ##########
>
>> I then have the following crontab entry for root:
>> @reboot /path/to/boot_cgi_bin.sh
>
>> Every time I reboot my server, this boot_cgi_bin.sh script turns into
>> a zombie (the cgi bins do get started). Does anyone see a reason why
>> this script would hang up as a zombie process?
>
> A zombie process means that process terminated but the process (which
> would seem to be cron in this case) which started it has not reaped the
> child's status.  It's really all gone and only exists as an entry in the
> proc table.  This CAN happen if a child it invokes leaves it's file
> descriptors open and they're pipes back to the parent (it's what causes
> ssh to refuse to terminate after running a script which restarts
> services.).  I had to deal with that in the smbmount program when I was
> maintaining it.
>
> Do a ps -lp {process id} on that process id and then see what the parent
> process is (may be a shell).
>
> Might also redirect stdin from /dev/null just in case one of those
> scripts you're invoking is doing something funny with stdin.
>
> Mike
> --
> Michael H. Warfield (AI4NB) | (770) 985-6132 |  mhw at WittsEnd.com
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> http://www.wittsend.com/mhw/
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> of all
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-- 
James Sumners
http://james.roomfullofmirrors.com/

"All governments suffer a recurring problem: Power attracts
pathological personalities. It is not that power corrupts but that it
is magnetic to the corruptible. Such people have a tendency to become
drunk on violence, a condition to which they are quickly addicted."

Missionaria Protectiva, Text QIV (decto)
CH:D 59

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