User have noted that a message they receive from an Lp mailing list may take hours or days appear in the archive. It was observed that there can be a backlog of messages in mailman/qfiles/archive, possibly 1000s of messages from the previous week.
This issue appears to be caused by giant archives, which need to regenerate all the index pages and many messages when a new message is added. Lp indexes are in reverse order, newest to oldest, so when a message is added, a message is pushed to the previous index. Process names on the server imply a lot of time is spent adding messages to https://lists.launchpad.net/ubuntu-x-swat/date.html which has more than 100,000 messages.
Lp could consider changing the index order for large lists so less work in needed.
Another route is modify Lp's mailman configuration to process a larger slice or archive messages. Lp processes one message at at a time in each queue, but it clearly takes longer to archive one message than it does to send a 1000 messages. The archive qrunner could process 2 or 3 messages to keep up, but this will in fact slow down the other queue slightly.
We can improve the queuing issue by updating the QRUNNERS tuple in
lib/
to a multiple of 2 (only documented in mailman itself). eg:
('ArchRunner', 4)
will archive 4 messages per sent message.
test_mm_