After some discussions, it seems that the problem is related to the login_max_processes_count option. The dapper version of dovecot wasn't enforcing this limit - this would explain why the dapper backport was working smoothly on hardy. Hardy version properly handles the login_max_process_count option.
Moreover most of the clients are using imaps. According to http://wiki.dovecot.org/LoginProcess, the imap-login process acts as an SSL/TLS proxy in the case of ssl connections. Combined with the fact that imap clients such as thunderbird are known to open more than one imap connections, the maximum number of login processes can be hit with less than 50 users connected at the same time. I've attached a debdiff that logs a warning message when login_max_process_count is hit and no -login processes can be freed. It also add a note to the dovecot configuration. ** Changed in: dovecot (Ubuntu) Importance: Undecided => Medium Status: Incomplete => In Progress -- connection problems under load with hardy dovecot https://bugs.launchpad.net/bugs/189616 You received this bug notification because you are a member of Ubuntu Server Team, which is subscribed to dovecot in ubuntu. -- Ubuntu-server-bugs mailing list Ubuntu-server-bugs@lists.ubuntu.com Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-server-bugs
