Re: Need help identifying a periodic performance issue.

From: Thomas Munro <thomas(dot)munro(at)gmail(dot)com>
To: Robert Creager <robertc(at)spectralogic(dot)com>
Cc: "pgsql-performance(at)lists(dot)postgresql(dot)org" <pgsql-performance(at)lists(dot)postgresql(dot)org>
Subject: Re: Need help identifying a periodic performance issue.
Date: 2021-11-16 05:50:18
Message-ID: CA+hUKG+iKkdeS9g1=866pypHZwPMQL2ho+oFWLSpRjV=-PvuCg@mail.gmail.com
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On Tue, Nov 16, 2021 at 5:43 PM Robert Creager <robertc(at)spectralogic(dot)com> wrote:
> One CPU is pegged, the data has been sent over STDIN, so Postgres is not waiting for more, there are no other queries running using this select:

So PostgreSQL is eating 100% CPU, with no value shown in
wait_event_type, and small numbers of system calls are counted. In
that case, is there an interesting user stack that jumps out with a
profiler during the slowdown (or the kernel version, stack())?

sudo dtrace -n 'profile-99 /arg0/ { @[ustack()] = count(); } tick-10s
{ exit(0); }'

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