imap error

May 12 18:03:23 server dovecot: log(9551): Warning: Shutting down logging for 'imap: ' with 2 clients May 12 18:03:23 server dovecot: log(9551): Warning: Shutting down logging for 'imap-login: ' with 2 clients May 12 18:03:23 server dovecot: log(9551): Warning: Shutting down logging for 'auth: ' with 1 clients May 12 18:03:23 server dovecot: log(9551): Warning: Killed with signal 15 (by pid=9631 uid=0 code=kill)