One more attempt: stuck processes
Hagedorn at uni-koeln.de
Fri Nov 16 05:27:09 EST 2007
--On 15. November 2007 19:25:19 +0100 Simon Matter <simon.matter at invoca.ch>
>> It's blinking red, which normally means a broken link. I'm not sure how
> The file 0 is a symbolic symlink which doesn't really point to a file,
> that's why the shell shows it blinking. Everything okay here.
Thanks. That's what I thought, but I wasn't sure.
>> reliable that is in this case. Anyway, lsof reports:
>> pop3d 25038 cyrus 0u IPv4 -64802663 TCP
>> It *thinks* the connections is still open. So does netstat:
>> # LANG=C netstat -a|grep p50865F5D
>> tcp 0 0 cyrus.rrz.uni-koeln.d:pop3s
>> But obviously that connection is dead. I don't know what conclusions to
>> draw from that ...
> Just two ideas come to mind:
> 1) Since it only happens on dialup connections, could it be that the
> dialin router at the providers end sends TCP/RST when a client hangs up
> and those packets are filtered somewhere, maybe on your firewall?
OK, let's run with that one.
a) We don't really have a firewall, we only use ACLs on the Cisco routers.
You can't even filter TCP/RST there.
b) Even *if* a TCP/RST had been dropped, lost or whatever, the server
*still* should timeout eventually!
> 2) Could it be that SO_LINGER should be used as socket option in
> service_create() in master/master.c.
I didn't remember that option, so I just read up on it. It seems as though
SO_LINGER is very dependent on implementation. If I get your intention
correctly SO_LINGER would have to be set with l_onoff set to non-zero and
l_linger to zero, right? So close() would return immediately? That might
make sense if the stack trace showed a call to close(). But if I understand
the code correctly, close() isn't called at all. The socket is closed as a
result of a call to exit(). And that defeats all use of SO_LINGER:
"When the socket is closed as part of exit(2), it always lingers in the
> If it's complete nonsense, ignore it.
I wouldn't know :-)
.:.Sebastian Hagedorn - RZKR-R1 (Gebäude 52), Zimmer 18.:.
Zentrum für angewandte Informatik - Universitätsweiter Service RRZK
.:.Universität zu Köln / Cologne University - ✆ +49-221-478-5587.:.
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