[Mailman-Users] Multi-Server install

[Stephen J. Turnbull]

Hi Roger,

First let me apologize on behalf of the project for the delay in
distribution of your post.  It appears a few posts got trapped in
limbo for about 10 days, and the delay was definitely between
Mailman's MTA and mine.

Roger writes:

 > I inherited a mult-server install of Mailman.
 > 
 > During a recent upgrade of the servers, I'm realizing the
 > master-qrunner.pid file is in the 'data' directory which is shared
 > between the two servers.

What version is Mailman?  I believe that recent versions put the PID
file in the 'lock' directory.

On my Debian installation, that directory is /var/lib/mailman/lock,
which is actually a symlink to /var/lock/mailman.  I suspect this
setup is intended to resolve exactly this kind of issue.

 > I have the  lock file set to use the hostname in the name of the lock file.
 > 
 > Shouldn't the PID file be in a local directory?

Yes.  You don't want the operation of local processes to be subject to
network issues.

 > the old servers had a cron entry to re-start mailman every night.  I'm
 > wondering if there was flakiness with a shared PID file going on that was
 > 'fixed' by rebooting mailman nightly.

If the name of the host is in the name of the lock file, this should
not cause "flakiness" problems because a conflict between the systems.
However, in my Debian install, I have both master-qrunner and
master-qrunner.<host>.<pid>, hardlinked to the same file which
contains the full pathname (in /var/lib/mailman/lock).

I think it's more likely that either the whole system including the
network was flaky, or that Mailman isn't designed to be robust in a
multi-host configuration.  It's generally designed to be robust
against various failures, so it's probably OK, but "multihost
operation with shared filesystem" was not an explicit design
criterion.

Steve