What is causing mysql to run out of memory?

[jdaviescoates]

I'm assuming it's the Broken Links Checker plugin I've got installed on one of my WordPress sites, but how can I check?

Thanks!

[nebulon]

I think the only option here is to disable things you think are causing that issue one-by-one and verify that it either is or is not the issue.

[marcusquinn]

@jdaviescoates I seem to remember Broken Links Checker is on the do not use list of many managed WP hosts for this reason.

These any use?

• https://wordpress.org/plugins/query-monitor/
• https://wordpress.org/plugins/debug-bar/

Although, don't leave running on Production as they have a performance cost too.

[jdaviescoates]

@nebulon said in What is causing mysql to run out of memory?:

I think the only option here is to disable things you think are causing that issue one-by-one and verify that it either is or is not the issue.

Is there anyway to at least narrow it down to what app caused it to run out of memory?

[nebulon]

@jdaviescoates not that I am aware of, I don't think mysql reports memory usage by database connection.

[jdaviescoates]

@nebulon I thought it was perhaps the Broken Links Checker on one of my WordPress installs, as as @marcusquinn noted it's widely known to sometimes cause such issues, but I've disabled that and I'm still getting these /mysql was restarted (OOM) (although they don't seem to appear in the event log?).

I note that the most recent one happened 5 minutes after my backups are due to start, and the other previous two times it's been 7-9mins before updates are due to run.

I wonder if either of those (backup/ update) processes might have something to do with it?

I guess I could just give mysql more memory and not worry, but be nice to know what's happening and why...