I'm guessing the problem is not so much pgsql traffic, than password veriication. If you are using heavy algorithm like ARGON2 or CRYPT-SHA512 (e.g.) you need to use a worker to distribute the password hashing effort, otherwise it'll be all done by the main auth process which can become a bottleneck. Aki
On 13/02/2025 16:54 EET Anatoliy Zhestov via dovecot <dovecot@dovecot.org> wrote:
2.4 docs "The auth workers are used to execute ___blocking___ passdb and userdb queries (e.g., MySQL and PAM). They are automatically created and destroyed as necessary."
postgresql is a non blocking db allowing async queries.
But I'll try to check it on the nearest days.
On Thu, Feb 13, 2025 at 6:35 PM Aki Tuomi <aki.tuomi@open-xchange.com> wrote:
You should be able to use https://doc.dovecot.org/2.4.0/core/summaries/settings.html#passdb_use_worker with pgsql too.
Aki
On 13/02/2025 15:47 EET Anatoliy Zhestov via dovecot <dovecot@dovecot.org> wrote:
Well, I try, but according to documentation - auth-workers are used for mysql and not for postgres. Nothing changes. auth process raises cpu% to 100 and performance not raised anyway.
On Thu, Feb 13, 2025 at 5:08 PM Aki Tuomi <aki.tuomi@open-xchange.com> wrote:
Try setting
auth_cache_verify_password_with_worker=yes
and see if this helps?
Aki
On 13/02/2025 14:55 EET Anatoliy Zhestov via dovecot <
dovecot@dovecot.org> wrote:
I set up a test server and started testing it by multiple threads
(1-200),
using all the advice given to me. 1 I disabled the postlogin script 2 raised maxconns to 200 3 set service_count = 400, process_min_avail = 100 4 increase auth_cache 5 increase the pool in postgres 6 enable high-performance mode for imap-login
However, the performance of the auth service seems limited by one core
and
cannot rise above 30-40 logins per second for our processor (60-70 with warm cache).
Still, is there any way to parallelize this? Having 48 cores to be limited by the performance of the one is too sad.
On Tue, Feb 4, 2025 at 1:23 PM Timo Sirainen <timo@sirainen.com> wrote:
On 3. Feb 2025, at 20.18, Anatoliy Zhestov via dovecot < dovecot@dovecot.org> wrote:
Are you sure the problem is authentication / pgsql? You could test
with
looping "doveadm auth lookup $user" rapidly. Of course for different
users
to avoid them coming from cache. Or if you can reproduce it that
way,
try
if the same happens for repeating the same user so it does come from cache.
i test in condition when 90% of imap connection is already
established.
auth cache is enabled so i guess tests with the same user are not
relevant.
-------- less loaded server ps waux|grep imap-login|wc -l 24977
Oh, somehow I missed that you have this many concurrent connections.
echo "13285 / 343" |bc 38 (per second)
So with this speed 24977 users would take 11 minutes to login back,
which
is a bit slow.
Some ideas:
1) If pgsql is the bottleneck, try multiple pgsql connections: Add maxconns=4 (or whatever) to the dovecot-sql.conf.ext's connect line.
2) In your Dovecot proxy (assuming you have one?) you can configure it
to
spread over disconnections over a long time, if the issue is that
backend
disconnects everyone at once. login_proxy_max_disconnect_delay setting
does
this.
3) With that many connections and to make logins faster, you'd be
better
off using
https://doc.dovecot.org/2.3/admin_manual/login_processes/#high-performance-m...
4) To optimize login performance, it would be best to get rid of the post-login script. Also:
service imap { service_count = 1000 process_min_avail = 10 }
5) auth_cache_size is rather small. Likely could be increased much
larger.
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