[Mailman-Users] Will slices ever become permanent?

[Mark Sapiro]

On 04/07/2015 08:09 AM, Jeff Taylor wrote:
> I've been running the modified slice code (three slice servers plus one
> backup server) for the past couple years, and generally speaking it has
> run perfectly.  However every now and then I find that mailman is
> suddenly not running on any of the servers, with no helpful information
> showing in the log files.  And it always comes down to discovering that
> an update for mailman was released which overwrote the slice code that I
> had added to mailmanctl.


I almost never apply local patches to a packaged software distribution.
If I have a need to patch the code, I will generally install the
software from source so that I have control over when and how it is
upgraded and I don't have to worry that an automatic or semi-automatic
software update will revert my changes.


> This has been such a handy setup, I'm surprised that I haven't seen
> comments from anyone else using the code.  Surely I'm not the only one
> running multiple mailman servers?


As far as I know, there is no actual documented procedure/patch for
doing this outside the archives of this list.


> Anyway, I was wondering if there are any plans to ever make this a
> permanent part of mailman?  Since the QRUNNERS variable is only created
> for this setup, it seems it would be an easy check to determine which
> method a person is using, and run the appropriate code for each, so
> there would be no impact on people running the single-server setup.  The
> same is true for the backup server -- a single variable is defined ONLY
> on that machine, so the necessary code would only run if that variable
> were present.


Actually, the QRUNNERS list is defined in Defaults.py and used in every
installation, and slicing of queues to be shared across multiple runners
is a standard feature. Your changes address enabling the multiple
runners to run on different machines. That only slightly complicates
making this a general feature, but no, there are no plans to do so.

As you note above, there has been very little interest in a feature like
this expressed on this list. In fact, the threads beginning at
<https://mail.python.org/pipermail/mailman-users/2012-December/074537.html>
and
<https://mail.python.org/pipermail/mailman-users/2014-May/077068.html>,
both initiated by you are the only things I recall on this subject in
the last 7 years.

There may be interest, but I haven't seen it so I haven't been motivated
to do anything about it. Also, I'm not sure how many use cases there
might be. I.e. you have N production servers plus a backup that only
processes messages that haven't been picked up for a while by a
production server. Will there be people who want similar load sharing
with either zero or greater than one backup server. I.e., documenting
the configuration options and actually configuring a particular
installation is a more complex problem than patching the code.

I suggest if you really want it, you submit it as a feature request at
<https://bugs.launchpad.net/mailman/+filebug>, and tag it 'mailman3', as
it's more likely to be implemented in MM 3 than in MM 2.1.

-- 
Mark Sapiro <mark at msapiro.net>        The highway is for gamblers,
San Francisco Bay Area, California    better use your sense - B. Dylan