Re: libpq contention due to gss even when not using gss

> On Mon, Jun 10, 2024 at 11:12:12AM GMT, Andres Freund wrote:
> Hi,
>
> To investigate a report of both postgres and pgbouncer having issues when a
> lot of new connections aree established, I used pgbench -C.  Oddly, on an
> early attempt, the bottleneck wasn't postgres+pgbouncer, it was pgbench. But
> only when using TCP, not with unix sockets.
>
> c=40;pgbench -C -n -c$c -j$c -T5 -f <(echo 'select 1') 'port=6432 host=127.0.0.1 user=test dbname=postgres
password=fake'
>
> host=127.0.0.1:                           16465
> host=127.0.0.1,gssencmode=disable         20860
> host=/tmp:                                49286
>
> Note that the server does *not* support gss, yet gss has a substantial
> performance impact.
>
> Obviously the connection rates here absurdly high and outside of badly written
> applications likely never practically relevant. However, the number of cores
> in systems are going up, and this quite possibly will become relevant in more
> realistic scenarios (lock contention kicks in earlier the more cores you
> have).

By not supporting gss I assume you mean having built with --with-gssapi,
but only host (not hostgssenc) records in pg_hba, right?