[Pymilter] How to shut down milter properly

[Stuart D. Gathman]

On Tue, 23 Mar 2004, Chris Gonnerman wrote:

> How do you shut down a Python Milter gracefully?  I want a
> chance to clean up.  I know it's a signals thing but I'm not even
> sure how to know which of the threads to send the signal to.

Method 1 - libmilter responds to SIGTERM.  It spawns a signal thread to
listen for signals.  On earlier version of Linux (RH7.3), each thread is
a separate process entry.  The signal thread for libmilter can be
recognized by 'rt_sig':

  set - `ps -e -o pid,wchan,cmd | grep "rt_sig ${python} bms.py"`
  [ "$3" != "grep" ] && kill $1

The sysv init script provided with the RPM does this for the bms milter.

On other systems, like AIX and later Linux distros, there is only one
process entry for a multi-threaded process.  Send the signal to that 
process - and it goes to the signal thread(s).

Method 2 - when your milter decides to shutdown based on some other event,
it can call milter.stop.  It could be listening on a socket for commands,
like RELOAD config and SHUTDOWN.

-- 
			Stuart D. Gathman <stuart at bmsi.com>
      Business Management Systems Inc.  Phone: 703 591-0911 Fax: 703 591-6154
      "Very few of our customers are going to have a pure Unix
      or pure Windows environment." - Dennis Oldroyd, Microsoft Corporation