Re: [Exim] Zombie processes with Exim 4.30

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Author: Philip Hazel
Date:  
To: Tim Jackson
CC: exim-users
Subject: Re: [Exim] Zombie processes with Exim 4.30
On Sun, 21 Dec 2003, Tim Jackson wrote:

> I've noticed on a number of machines that since Exim 4.30, zombie/defunct
> processes seem to be appearing "randomly".

...
> and all lightly loaded.

      ^^^^^^^^^^^^^^^^^^
      ^^^^^^^^^^^^^^^^^^


This is probably the key. The Exim daemon only reaps completed
subprocesses when it wakes up for some other reason. So, if your system
is lightly loaded, it won't be waking up very often, and the last
subprocess it created may hang around as a zombie for a while. You
should only see a small number (usually no more than one, but I guess
more is possible) of such processes, and if you prod the daemon (telnet
to port 25 or wait for the next queue runner time), they should go away.

> - There is absolutely nothing in the logs. Indeed, a zombie process has
> appeared on my desktop machine since lunchtime today, which has done
> absolutely nothing except an hourly queue run (on an empty queue) all
> afternoon, it hasn't even processed a single mail.


Did the zombie remain after a queue run? If so, then there is something
odd going on.

> - Running "exiwhat" seemed to get rid of the defunct process in at least
> one instance.


Yup. That's another way of prodding the daemon.

Philip

--
Philip Hazel            University of Cambridge Computing Service,
ph10@???      Cambridge, England. Phone: +44 1223 334714.
Get the Exim 4 book:    http://www.uit.co.uk/exim-book