[ZODB-Dev] mkzeoinst.py without ZOPE

[Jeremy Hylton]

On Wed, 2004-01-07 at 19:20, John Belmonte wrote:
> Jeremy Hylton wrote:
> > Actually, daemon mode is a bit different.  Running runzeo.py will run a
> > ZEO server.  Running it under the control of zdaemon will run it as a
> > daemon program.
> 
> I see.  The zdaemon system seems a little overkill to me, or I should 
> say that the idea of needing to babysit a server to restart in case of a 
> crash doesn't give me much confidence in ZEO.  I attempted to use 
> Debian's start-stop-daemon instead, but for some reason I can't connect 
> to the ZEO server when I use the background option.

zdaemon provides a separation of concerns.  The old ZEO/start.py script
had the same basic functionality, but the integration of zdaemon in the
same process was messy.  I believe the daemontools package takes a
similar approach.

I don't think you should see the use of zdaemon as a reflection on ZEO
reliability.  There are plenty of reasons you might want to restart a
daemon process or you might want to send it a signal when you rotate log
files.

> I wish zdaemon supported a pid file, which is a standard thing for 
> daemon programs.  In my case I have a cron job that does some 
> maintenance on my database, and I was using the ZEO server pid file to 
> let the job know that it's safe to run.  Now I guess I'll have to run 
> "zdctl status" and parse the output, which seems a bit fragile.

I think that's the best strategy.  I'll note that the old start.py had
bugs that left stale PID files around, so that approach was somewhat
fragile, too.

Jeremy