Hmm. I've now upgraded to Dovecot 0.99.10.4, and it doesn't appear to have helped much, if at all.
Between 18:28 yesterday and 10:58 today, the number of pop3-login processes has risen from 12 to 186.
Just for reference, I've gdb-ed the earliest of those processes again:
(gdb) p clients->nodes_count
$1 = 0
(gdb) p main_refcount
$2 = 2
(gdb) p auth_reconnect
$3 = 0
(gdb) p auth_waiting_handshake_count
$4 = 0
(gdb) p closing_down
$5 = 1
(gdb) p process_per_connection
$6 = 1
(gdb) p ssl_proxies->nodes_count
Error accessing memory address 0x10: Invalid argument.
(gdb) p ssl_proxies
$7 = (struct hash_table *) 0x0
(gdb) p io_master
$8 = (struct io *) 0x151e0
(gdb) p *io_master
$9 = {next = 0x0, fd = 3, condition = 1, destroyed = 0,
callback = 0x4c50
This looks exactly as before, except that the master_input function has moved by 32 bytes.
There's clearly still something going wrong, somewhere. )-8
Regards,
--Clive.