[trac] Avoid deadlock in DB cleanup cronjobs

[matze]

Subject: Cron <trac@issues1> mysql -utrac -p'O7780D8nFJl2onW' 
trac_orders --execute ' INSERT INTO session_attribute (sid, 
authenticated, name, value) SELECT sid, authenticated, name, value FROM 
trac.session_attribute WHERE authenticated = 1 AND name IN ("email", 
"password") ON DUPLICATE KEY UPDATE value=VALUES(value) ' >/dev/null
Date: Tue, 18 Aug 2015 02:00:01 +0000 (UTC)
From: Cron Daemon <***@adblockplus.org>
To: ***@adblockplus.org

ERROR 1213 (40001) at line 1: Deadlock found when trying to get lock; try restarting transaction

[ferris]

We've landed the related commit: ​https://hg.adblockplus.org/infrastructure/rev/cd9c254fe4c7

Rolling it out on issues1 now and we'll see over time if the cron job runs more stable.

[ferris]

It seems that the other cron-job collides as well. Just added a second patch: ​https://codereview.adblockplus.org/29369517

I've manually applied the change in the issues1 cronjobs for now to see how they run over the holidays. Obviously, it's not critical if these cronjobs fail now and then.

[ferris]

Looking good, no more complaints from this cronjob the last days. I suggest we close this ticket as soon as we've got the second review done, and the changes properly synced to issues1.

[abpbot]

A commit referencing this issue has landed:
​Issue 2924 - Move session cleanup to not collide with sync