[Evolution] 1.5 FAQ answer: Hang while pinging imap server

[Not Zed <notzed ximian com>]

This applies to 1.5 more than 1.4, but some of it may apply there.  1.4 has some bugs that mean you get a hard hang instead of just a timeout hang.

Q: I keep getting a hang while "pinging IMAP server".

A: In 1.4.x, this may cause a hard lockup.  You need to quit evolution and restart.

In 1.5.x this will timeout when the underlying operating system times out.  When running a Linux kernel this is about 1-2 hours; so not very practical.  You can hit the "Cancel" button and then Send/Receive to reconnect the session as a workaround.

>From 1.5.9 onwards, we now set TCP_KEEPALIVE on the socket, and also provide an application defined timeout.  The timeout is 4 minutes, although the TCP_KEEPALIVE should keep the connection alive whilst idle and should only timeout if it has really gone down.  When keepalive is used however, the default idle time before it kicks in is 2 hours under Linux - which wont fix the problem since we're never idle more than 10 minutes at a time anyway by default.

To change the idle time before it kicks in on Linux (as root):
# echo 60 > /proc/sys/net/ipv4/tcp_keepalive_time 
#
This will cause the keepalive mechamism to kick in after 60 seconds.  Keepalive isn't without cost - extra network overhead, but should fix this specific problem if you suffer from it.

How to make this change permanent depends on your distribution.

Michael Zucchi <notzed ximian com> Ximian Evolution and Free Software Developer

Novell, Inc.