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[SOLVED] Postgres using a lot of CPU since update (retrolemmy.com)

submitted 4 months ago* (last edited 4 months ago) by [email protected] to c/[email protected]

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EDIT: It seems to have been fixed thanks to @[email protected]. Running analyze verbose; in postgres.

After updating to 0.19.5 from 0.19.3 my postgres is often using up 500%+ of CPU according to docker stats and often going to 100% CPU on most cores according to htop. Also noticed in the uptime monitor:

htop shows one of the 5 postgres processes constantly on UPDATE. I think this might be part of the problem.

I'm not comfortable with postgres and am honestly completely in the dark how or where to mitigate or even pinpoint this issue.

Any help would be appreciated.

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[–] [email protected] 1 points 4 months ago* (last edited 4 months ago) (1 children)

Ah, you are using pretty different deployment then, even the used postgres image is different then the usual deployment ( pgautoupgrade/pgautoupgrade:16-alpine instead of postgres:16-alpine) this might or might not cause differences.

I would try increasing POSTGRES_POOL_SIZE to 10-20, but I am guessing here, the idea being that lemmy is hammering postgres through the default 5 conns which increases CPU but that is a bit of stretch

[–] [email protected] 2 points 4 months ago

It thankfully seems to have been fixed thanks to @[email protected]. Running analyze verbose; in postgres.

The pgautoupgrade was added for the new version because this deployment is an all-in-one solution for running lemmy. And upgrading the databases turned out to be quite the effort until some user pointed the maintainer towards pgautoupgrade here.

I tried running lemmy before I found out about this, but this just makes it so much more convenient to run.