[Mongrel] [ANN] Another mongrel_cluster prerelease

Zed A. Shaw zedshaw at zedshaw.com
Thu Apr 12 13:40:28 EDT 2007

On Thu, 12 Apr 2007 10:15:13 -0700
"Michael A. Schoen" <schoenm at earthlink.net> wrote:

> Matt Zukowski wrote:
> > Just a suggestion, but maybe the stop command should wait until all the
> > servers are actually down before it exits. What Michael describes below
> > is a fairly frustrating aspect of using mongrel_cluster. The restart
> > process right now kind of sucks, and I suspect that making it behave
> > more gracefully would make a lot of people happy.
> And Mongrel itself does support a more graceful restart, mongrel_cluster 
> just doesn't use it at the moment. Even given the constraint that a true 
> restart won't re-read the cluster config, still seems worth being 
> available as an option.

I think I'm going to say, no, you don't get this in mongrel_cluster.
When we had it there were way too many problems because how Rails does
this kind of soft restart isn't very clear.  It's basically a bunch of
black magic ruby that reloads all the stuff like in debug mode.  That
also means that it doesn't work with modules and systems that are
outside of rails.  For example, you can't hook into this restart
process so that you can properly close connections to Jabber servers.

This lead to people having weird problems like Mongrel not actually
restarting and memory leaks.  Of course, they don't blame Rails or the
plugin they're using, they blame Mongrel.  In order to keep the support
problems to a minimum, we just stop the server and restart.

What's wrong with that for people?  Apparently you all need constant
and completely available up-time for your web applications.  Great.
You can't get this from Mongrel, or from Rails, you need to look
outside at your proxy server, network architecture, and other sources.

However, you do have access to it.  Every time mongrel starts up it
tells you what posix signals cause what actions.  If you want a
graceful restart and you know it will work then you just hit your
mongrels with that signal.

Zed A. Shaw, MUDCRAP-CE Master Black Belt Sifu
http://www.awprofessional.com/title/0321483502 -- The Mongrel Book

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