Memory leaks in MySQL

[Anon]

Anybody ever notice memory leaks in mysql? When I started it a week ago it used 2MB per process / 1.5MB shared. Today, 1M pages later, it was using 12MB per process / 1.5MB shared. I restarted it this morning (2MB again), now it's up to 4MB per process.

[[deleted]]

That doesn't have to be a memory leak, MySQL (and all databases) cache everything they can get their hands on. And that's a good thing, or performance would drop like a brick.

[Anon]

I know - but it seems like it's growing quite a bit (continuously), plus I'd think that everything that would be cached would be so not long after starting mysql. I have about 15-20 tables and there aren't very many inserts per day (maybe 100). Anything in show status/variables that might explain it?

[smarlowe]

The shared memory isn't going up? If the shared memory isn't going up I would not suspect the cache to be the problem with memory use increase. Caches are almost universally shared memory in databases, and I'm sure MySQL does the same.

Without running MySQL under a debugger that can check it for leaks, I can't really comment on whether it's a real memory leak or maybe a local cache / global cache architechture I'm not familiar with.

But generally a crowing cache shows directly in an increased shared memory usage.

[Anon]

No - it's exactly the same (1.5MB while each proc now is 9.7M😎. I don't know what is causing this, but two things I might check in to further are: I'm using standard connection - if there was a leak there I presume persistents would reduce the leak; there's 100K's of temporary tables that have been created, maybe something's going on there.

I also let PHP do all the cleanup (closing connections, etc.) but there shouldn't be a problem there.