dovecot, many imap/pop3 login processes

Hello,

I usually have 30-40 dovecot processes but sometimes there are like 120-150

24401 dovecot 21:45 pop3-login 24412 dovecot 21:45 pop3-login 24423 dovecot 21:45 pop3-login 24483 dovecot 21:45 imap-login 24512 dovecot 21:45 imap-login 24526 dovecot 21:45 imap-login

and memory consumption grows, however there certainly cannot be that many active logins

some of them never end

maillog shows that every connection is successfully closed:

Dec 15 21:22:09 ns1 dovecot: imap-login: Login: user=<anna-test.ee>, method=PLAIN, rip=::ffff:127.0.0.1, lip=::ffff:127.0.0.1, secured
Dec 15 21:22:09 ns1 dovecot: IMAP(anna-test.ee): Connection closed
Dec 15 21:22:42 ns1 dovecot: imap-login: Login: user=<info-hello.eu>, method=PLAIN, rip=::ffff:127.0.0.1, lip=::ffff:127.0.0.1, secured
Dec 15 21:22:42 ns1 dovecot: IMAP(info-hello.eu): Connection closed
Dec 15 21:22:50 ns1 dovecot: imap-login: Login: user=<info-hello.eu>, method=PLAIN, rip=::ffff:127.0.0.1, lip=::ffff:127.0.0.1, secured
Dec 15 21:22:50 ns1 dovecot: IMAP(info-hello.eu): Connection closed
Dec 15 21:22:54 ns1 dovecot: imap-login: Login: user=<info-erudiit.ee>, method=PLAIN, rip=::ffff:127.0.0.1, lip=::ffff:127.0.0.1, secured
Dec 15 21:22:54 ns1 dovecot: IMAP(info-erudiit.ee): Connection closed
Dec 15 21:23:09 ns1 dovecot: imap-login: Login: user=<anna-test.ee>, method=PLAIN, rip=::ffff:127.0.0.1, lip=::ffff:127.0.0.1, secured
Dec 15 21:23:09 ns1 dovecot: IMAP(anna-test.ee): Connection closed
Dec 15 21:23:42 ns1 dovecot: imap-login: Login: user=<info-hello.eu>, method=PLAIN, rip=::ffff:127.0.0.1, lip=::ffff:127.0.0.1, secured
Dec 15 21:23:42 ns1 dovecot: IMAP(info-hello.eu): Connection closed
Dec 15 21:23:50 ns1 dovecot: imap-login: Login: user=<info-hello.eu>, method=PLAIN, rip=::ffff:127.0.0.1, lip=::ffff:127.0.0.1, secured
Dec 15 21:23:50 ns1 dovecot: IMAP(info-hello.eu): Connection closed
Dec 15 21:24:09 ns1 dovecot: imap-login: Login: user=<anna-test.ee>, method=PLAIN, rip=::ffff:127.0.0.1, lip=::ffff:127.0.0.1, secured
Dec 15 21:24:09 ns1 dovecot: IMAP(anna-test.ee): Connection closed
Dec 15 21:24:42 ns1 dovecot: imap-login: Login: user=<info-hello.eu>, method=PLAIN, rip=::ffff:127.0.0.1, lip=::ffff:127.0.0.1, secured
Dec 15 21:24:42 ns1 dovecot: IMAP(info-hello.eu): Connection closed
Dec 15 21:24:50 ns1 dovecot: imap-login: Login: user=<info-hello.eu>, method=PLAIN, rip=::ffff:127.0.0.1, lip=::ffff:127.0.0.1, secured
Dec 15 21:24:50 ns1 dovecot: IMAP(info-hello.eu): Connection closed

but why do they remain if connections were closed?

and can i somehow regulate lifetime of those luggy imap/pop3 procceses?