Re: gnus makes emacs lose response

[Ralf Angeli <angeli@iwi.uni-sb.de>]

* Ralf Angeli (2006-04-17) writes:

>> Lisp Backtrace:
>> "accept-process-output"
>> "imap-wait-for-tag"
>> "nnimap-retrieve-groups"
>> "gnus-retrieve-groups"
>
> Is there anything else I can do to help debugging this?
>
> I don't have the original report, so I don't know under which
> circumstances the hang happens there.  In my case it happens if I
> connect to the internet via modem, open an encrypted connection to an
> IMAP server, cut the internet connection, connect to the internet
> again, and try to connect to the IMAP server again.  I am not sure if
> this is a problem of Emacs, the programs used for opening the
> connection to the server, or the kernel.  I tried it now with openssl
> s_client, starttls, and gnutls-cli.  All three behave identically on
> GNU/Linux, i.e. the hang happens with all of them.
>
> BTW, in contrast to Emacs on GNU/Linux, the Windows port of Emacs does
> not hang.  Perhaps this information helps identifying the cause.

After some messing around I found the difference between between both
cases.  Under Windows the process (e.g. openssl s_client) dies as soon
as the modem connection is closed while on GNU/Linux it is kept alive.
That means after reconnecting to the internet under Windows a new
process is started which has no problem communicating to the server
while on GNU/Linux the old one is reused which obviously cannot cope
with the new internet connection.

I am not sure what the right course of action on GNU/Linux would be to
remedy the problem.  Should programs like openssl die when the
internet connection is being closed?  Or renegotiate a connection?
Should Emacs kill the respective processes if there is no answer after
a certain amount of time and start new ones?  I guess the latter
suggestion is not sensible because Emacs does not know why there is no
answer.  It could as well be that the server is down.

For now, I think, I can work around this problem by writing a script
which closes the internet connection as well as kills all openssl (and
similar) processes.

-- 
Ralf