Re: backend suddenly becomes slow, then remains slow

Andrew Dunstan <andrew(dot)dunstan(at)pgexperts(dot)com> writes:
> One of my clients has an odd problem. Every so often a backend will
> suddenly become very slow. The odd thing is that once this has happened
> it remains slowed down, for all subsequent queries. Zone reclaim is off.
> There is no IO or CPU spike, no checkpoint issues or stats timeouts, no
> other symptom that we can see. The problem was a lot worse that it is
> now, but two steps have alleviated it mostly, but not completely: much
> less aggressive autovacuuming and reducing the maximum lifetime of
> backends in the connection pooler to 30 minutes.

> It's got us rather puzzled. Has anyone seen anything like this?

Maybe the kernel is auto-nice'ing the process once it's accumulated X
amount of CPU time?

regards, tom lane