Hi Giulio,
Giulio Harding wrote:
The disparity between the two sides of the TCP connections is probably
due to backlog - only 5 TCP connections are ever established with the
HTTP server at a time, but the rest of the connections from Kannel are
'pending' as per OS/apache TCP backlog limits. These connections won't
receive a 'connection refused', they'll simply wait until resources are
available, whereupon they'll be fully established.
Because these connections aren't explicitly failing, and because of the
rate of incoming MO messages, smsbox appears to be simply creating HTTP
connections faster than they are being used. The only solution is to
forcibly reduce the rate of message delivery, or to limit the number of
HTTP connections to the application HTTP server (as mentioned by
Alexander Malysh in his reply to my original email).
Also, those 'strange' sockets that Kannel has look like they've been
closed on the other side (by the application HTTP server) and are thus
useless, and simply haven't been cleaned up. When a HTTP connection is
closed by the server, it should be cleaned up on Kannel's side as soon
as possible. They should really be cleaned up before attempting to
create new HTTP connections.
I agree in this analysis.
I think this is the crux of the problem: this TODO, and our issue would
be addressed by the patch that Alexander has offered - given that he's
indicated that it is a fairly simple patch, and the issue seems (to me)
quite serious, I think this is worth focussing on ASAP.
agreeing too.
These look like they may be directly related to the problem we're
experiencing - is anyone working on these tasks, and if so, is there
an ETA to implementation?
can you please retry to leaverage the MO load with let's say 2-4
smsbox connections....
It's still curious why sockets are keept open that way...
Ok, I'll try this out, with multiple smsboxes on the same machine, and
possibly multiple smsboxes on multiple machines (if I can source some)
- I'll also try fiddling with the priority of the bearerbox process
(using nice) to see if I can get the SMPP and HTTP processing better
balanced...
However, none of these workarounds will guarantee correct behaviour
under load, as there is nothing preventing Kannel from opening too many
sockets. As I mentioned before, I think this is a bug.
yep, can you please add this to a full but report to http://bugs.kannel.org/, in
order we have a correct track of the issue? Thanks in advance.
Stipe
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