Too many wait in auth process

[Justas]

Hey,

please refer to: https://doc.dovecot.org/admin_manual/login_processes/

We are using high-performance mode and it is serving 30k users with no 
problems.

Best,
Justas


On 2022-02-07 17:33, ismael.tanguy at univ-brest.fr wrote:
> Hello,
> 
> I'm currently benchmarking new hardware aimed to serve around 70k users
> For now, our IMAP server have 13k users.
> 
> To run imaptest, I've spwan some bench clients.
> Each bench client can run imaptest with 1000 clients.
> More than 1000 clients will load CPU of this bench client
> 
> imaptest command (command are chosen from usage stat on our other IMAP 
> servers):
> 
> imaptest host=xxxxx port=xxx userfile=userfile mbox=/root/dovecot-crlf
> 	pass=sxxxx seed=123 clients=1000 select=194 uidfetch=94 noop=70
> 	status=82 append=49 fetch=276 list=12 store=19 expunge=22
> 	msubs=4 search=4 logout=1 delete=81 no_pipelining
> 
> 
> With one bench client, everything runs smoothly.
> 
> # ps aux | grep dovecot | awk '{print $11,$12,$13,$14,$15,$16,$17,$18}' | sort | uniq  More than 1000 clients will load CPU of this bench client-c
>       1 anvil: [221 connections] (anvil)
>     1 auth: [13 wait, 0 passdb, 0 userdb] (auth)
>     1 dovecot/config
>     1 dovecot/imap
>    84 dovecot/imap-login
>     1 dovecot/log
>    20 dovecot/pop3-login
>     1 grep dovecot
>     1 stats: [1307 connections] (stats)
> 
> 
> When a second instance bench instance start imaptest, clients of first 
> and second instance begin to stall :
> 
>   1400 stalled for 20 secs in command: 1 LOGIN"fakeuser644 at mailbench...."  "password"
> 
> And :
> 
> # ps aux | grep dovecot | awk '{print $11,$12,$13,$14,$15,$16,$17,$18}' | sort | uniq -c
>     1 anvil: [221 connections] (anvil)
>     1 auth: [1227 wait, 0 passdb, 0 userdb] (auth)
>     1 dovecot/config
>     1 dovecot/imap
>    37 dovecot/imap-login
>     1 dovecot/log
>    20 dovecot/pop3-login
>     1 grep dovecot
>     1 stats: [680 connections] (stats)
> 
> Every auth go in wait, number of connection decreases.
> 
> Using mysql or a password file give same results.
> 
> I have used different values for service_count with also no success.
> 
> I think my use of imaptest could be false.
> My understanding of service auth is limited for now because I'm quite 
> new to Dovecot (I have previously worked with Cyrus).
> 
> Thank you for every hints.
> 
> 
> Ismaël Tanguy
> 
> 
>