[Mailman-Users] Is it possible that a list loses its members?

[Mark Sapiro]

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Sebastian Hagedorn wrote:
|
| we're running Mailman 2.1.9. Today I encountered something that's a
| mystery to me. A few weeks ago we created a list using our custom
| list-creation script that we always use. The list was apparently created
| correctly, like they always are. There were three initial list members
| and I can see them being added in /var/log/mailman/subscribe. Our script
| adds members using the add_members tool.
|
| Every Saturday we run a cronjob that looks for empty lists, i.e. lists
| with no members. The list in question popped up. So I wrote to the list
| owner to ask him why the list was empty. He was completely unaware of
| that. He had received the notifications about the new list members when
| the list was created and nothing since. That's corroborated by the fact
| that there are no unsubscribe lines in any of the log files. Still the
| list was empty.
|
| I'm at a loss to explain what might have happened. Any ideas?


I can't explain what happened, but the only way I can see something like
this happening is if there was a failure in list locking. I.e. if some
other process was updating the list at the same time that add_members
was running and the other process locked the list first, then
add_members locked the list, added the members and saved and unlocked
the list, and finally the other process saved the list without the members.

I don't think this can result from a simple failure of some process to
lock the list since an unlocked list cannot be saved, and locking a list
refreshes the data. If there is an issue, it has to be in the locking
mechanism itself, but this seems sound and there are no known issues
with this, although coincidentally (and I'm sure it's just a rare and
strange coincidence) I saw an apparent locking failure last week. See
<http://mail.python.org/pipermail/mailman-developers/2008-May/020190.html>.

So now we have two reports of possible locking failures. We'll have to
keep watching.


Brad Knowles wrote:
| What is in the "bounce" log?  The automatic bounce processing could have
| unsubscribed them, although I would have thought that the results of that
| would show up in the "subscribe" log.

Yes - unsubscribes by bounce processing are logged in the "subscribe"
log as is every other removal of a member except for low level
manipulation by a withlist or other script.

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

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