Extreme slowness of 5/2/2023
- Thread starter GasBandit
- Start date
GasBandit
Staff member
None, actually. It was a MySQL problem I created by pruning 6,600+ spam accounts from our user table.
Did you know that when you delete a user, it instigates a cleanup of several different unindexed tables, resulting in tying up the MySQL connection for about 40 seconds per user deleted?
I didn't.
Until after the batch delete.
So the slowness would have persisted for about 72 hours and change to work out on its own. Instead, it lasted about 3 hours because that's how long it took me to figure out where the problem was, research it, find a solution, and implement it.
Those 40 second table cleanups now take about 0.15 seconds, because I manually created indexes for the tables in question.
GasBandit
Staff member
It came about as sort of a culmination of tech debt, I think. The tables in question were for functions that didn't get added in until later (like reacting to posts), and even then, you'd only notice it if you went to delete many users at once.
It was fixed in XenForo v2.2 - which we don't have because our license ran out forever ago. But for our purposes, just creating the indexes is all that really needed to be done.
