30 Jan
2012
30 Jan
'12
12:40 p.m.
Hello,
On 1/30/12 6:35 PM, Peter Dunkley wrote:
Hi,
Any retransmission will cause the problem, so anyone using UDP over
the Internet to a Kamailio presence server where there is occasional
packet-loss will see it. It was just first noticed here under heavy load.
By creating a new transaction and absorbing the retransmissions, do
you mean calling t_newtran()/t_release() when the SUBSCRIBE is received?
yes, like in default config, using t_newtran() before handling the
subscribe. t_check_trans() is used to figure out of there is already a
transaction for that request and absorbs the request if it is
retransmissions.
Not sure t_release() is explicitly needed anymore, Andrei did some work
long time ago in this area, iirc, but if used it is harmless, so it is
still in the default config.
Cheers,
Daniel
If so I didn't think of that. It'd make sense to do that too. I
think the presence module should cope with retransmissions (especially
as we need it to cope in a multi-server environment with
load-balancers/fail-over and a shared database). But if using
t_newtran()/t_release() will handle retransmissions in the normal case
it should help reduce the load on the database.
Thanks,
Peter
On Mon, 2012-01-30 at 18:26 +0100, Daniel-Constantin Mierla wrote:
Hello,
it can be held for next minor release to be tested more, if you feel
it is better (we have to include something there as well :-) ). From
commit log I understood is happening usually under RLS heavy load
with retransmissions, does not help creating the transaction and
absorbing the retransmissions with tm?
Cheers,
Daniel
On 1/30/12 6:19 PM, Peter Dunkley wrote:
> Hello,
>
> I believe that this bug also affects the 3.2 branch, but the change
> is quite big and with the next release of 3.2 due tomorrow I thought
> it best to hold off "cherry-pick"ing it until after the release.
> That is, unless anyone else thinks it should go in there?
>
> Regards,
>
> Peter
>
> On Mon, 2012-01-30 at 18:16 +0100, Peter Dunkley wrote:
>> Module: sip-router
>> Branch: master
>> Commit: e6a50c5c0957a5ad3e08e57ede5be775a41ac24f
>>
URL:http://git.sip-router.org/cgi-bin/gitweb.cgi/sip-router/?a=commit;h=e6a…
>>
>> Author: pd<peter.dunkley(a)crocodile-rcs.com
<mailto:peter.dunkley@crocodile-rcs.com>>
>> Committer: pd<peter.dunkley(a)crocodile-rcs.com
<mailto:peter.dunkley@crocodile-rcs.com>>
>> Date: Mon Jan 30 17:06:42 2012 +0000
>>
>> modules_k/presence: Improved handling of retransmitted SUBSCRIBE requests
>>
>> - handle_subscribe() doesn't handle retransmitted SUBSCRIBEs properly. This
was
>> noticed with back-end SUBSCRIBEs from RLS under heavy load (also tried TCP
>> here but under-load this caused a different set of problems with buffer
>> sizes and buffers taking too long to process).
>> - Although this was originally observed with RLS back-end SUBSCRIBEs it
>> appears to be a general issue when UDP is used.
>> - There were two main problems:
>> 1) On an un-SUBSCRIBE the record in the hash-table or DB will be removed. If
>> the un-SUBSCRIBE is retransmitted there is no record to be found and
>> handle_subscribe() fails.
>> 2) After fixing 1, and on re-SUBSCRIBE, remote CSeq's with lower than
>> expected values cause failures. This can also happen when there are
>> retransmissions.
>> - The fix was to catch both these cases and treat them as a special class of
>> error. In these two cases and when the protocol is UDP, a correct-looking
>> 2XX response is sent, but no further processing (database updates, sending
>> NOTIFY, and so on) is performed on the SUBSCRIBE request.
>> - Also modified the query in get_database_info() to just use Call-ID, To-tag,
>> and From-tag for dialog matching (so it duplicates the query from
>> get_stored_info()) as the query that was there looked a little aggressive.
>>
--
Daniel-Constantin Mierla -- http://www.asipto.com
http://linkedin.com/in/miconda -- http://twitter.com/miconda