Hi,

# dovecot --version 2.3.3 (dcead646b)

# doveinfo Nombre d'utilisateurs : 1151 Sockets IMAP : 4356 Process dovecot/imap : 4357 Process dovecot/imap-login : 1339 Process dovecot/pop3 : 0 Process dovecot/pop3-login : 0 Process dovecot/auth : 1 Process dovecot/auth -w : 2 Process dovecot/anvil : 1 Process dovecot/log : 1 Process dovecot/config : 1 Process dovecot/stats : 1

Since I am using dovecot 2.3.X I got the following messages

/var/log/dovecot-20180930:Sep 28 17:33:38 balcha dovecot: master: Warning: service(stats): client_limit (1000) reached, client connections are being dropped

Users complain the system became slow.

I happen when dovecot/imap process grows above 1000.

With 2.2.X no default were defined (#default_client_limit = 1000) and I have no such log and no performance problems.

With 2.3.3 I first increase default_client_limit to 4096

but the following message come again when dovecot/imap grow above 4096

====== Nov 6 12:09:12 balcha dovecot: master: Warning: service(stats): client_limit (4096) reached, client connections are being dropped Nov 6 12:09:25 balcha dovecot: imap: Error: net_connect_unix(/var/run/dovecot//stats-writer) failed: Resource temporarily unavailable ... many same lines as above

Now 8192 solve my problem default_client_limit = 8192

I don't understand why the first Warning is related to service(stats) instead of service(imap) and why the socket stats-writer became temporarily unavailable

# ls -l /var/run/dovecot/stats-writer srw-rw---- 1 root dovecot 0 Nov 8 02:44 /var/run/dovecot/stats-writer

PS.

# dovecot --version 2.3.3 (dcead646b)

# dovecot -n # 2.3.3 (dcead646b): /usr/local/dovecot-2.3.3/etc/dovecot/dovecot.conf # Pigeonhole version 0.5.3 (f018bbab) # OS: Linux 2.6.32-696.30.1.el6.x86_64 x86_64 Red Hat Enterprise Linux Server release 6.9 (Santiago) # Hostname: balcha.onera base_dir = /var/run/dovecot/ default_client_limit = 8192 <<< default with dovecot 2.2.X changed to 4096 then 8192 disable_plaintext_auth = no listen = * mail_location = maildir:~/Maildir:INDEX=~/Maildir:CONTROL=~/Maildir mail_plugins = quota managesieve_notify_capability = mailto managesieve_sieve_capability = fileinto reject envelope encoded-character vacation subaddress comparator-i;ascii-numeric relational regex imap4flags copy include variables body enotify environment mailbox date index ihave duplicate mime foreverypart extracttext mbox_write_locks = fcntl passdb { args = %s driver = pam } plugin { quota = maildir:User quota quota_grace = 6%% quota_rule = ?:storage=6G quota_rule2 = Trash:storage=+5%% quota_warning = storage=95%% quota-warning 95 %u quota_warning2 = storage=80%% quota-warning 80 %u sieve = file:~/sieve;active=~/.dovecot.sieve } postmaster_address = postmaster@onera.fr quota_full_tempfail = yes rejection_reason = Votre message à <%t> est mis en attente; raison : %n% r rejection_subject = Message (Objet: %s) mis en attente de livraison service anvil { client_limit = 4299 } service auth { client_limit = 5320 } service imap-login { client_limit = 8192 process_limit = 4096 } service imap { process_limit = 8192 } service quota-warning { executable = script /usr/local/bin/quota-warning.sh unix_listener quota-warning { group = root mode = 0666 user = root } user = root } ssl_cert = </usr/local/dovecot/etc/certs/dovecot.pem ssl_dh = # hidden, use -P to show it ssl_key = # hidden, use -P to show it syslog_facility = local1 userdb { driver = passwd } protocol lda { mail_plugins = quota sieve } protocol imap { mail_plugins = quota imap_quota } protocol pop3 { mail_plugins = quota pop3_reuse_xuidl = yes }

-- Christian Pélissier ONERA DSI/ISR BP72 92322 Chatillon CEDEX  34419