Sorry I meant putting modparam("tm", "auto_inv_100_reason", "Trying") as
parameter.
As per tm module , auto_inv_100 parameter is by default set as 1 , but still
Kamailio is not sending it, is there some function that trigger it ?
-----Original Message-----
From: sr-users <[email protected]> On Behalf Of Ali Taher
Sent: Thursday, December 12, 2019 4:39 PM
To: Kamailio (SER) - Users Mailing List <[email protected]>
Subject: Re: [SR-Users] Kamailio delayed reponse in case of database load
Thanks Alex for drawing my attention regarding escaping $rU before using it in
sql queries. But I'm not sure where to use sql.val in this case ? Do you mean I
can use either {s.escape.common} or {sql.val} ?
Regarding the 100 trying , should I put modparam("tm", "auto_inv_100_reason",
"Trying") in the beginning of if (is_method("INVITE")) block ?
Regards,
Ali Taher
-----Original Message-----
From: sr-users <[email protected]> On Behalf Of Alex Balashov
Sent: Tuesday, December 10, 2019 11:21 AM
To: Kamailio (SER) - Users Mailing List <[email protected]>
Subject: Re: [SR-Users] Kamailio delayed reponse in case of database load
Ali,
If Kamailio is performing a database-bound workload, there's no way to make it
respond faster if the database is being slow. Excluding things like caching of
route responses, how would that be logically possible?
:-)
Since we use PostgreSQL (and prefix_range) very extensively, I can say that
such extreme slow-downs when loading data are abnormal; relational databases in
general, and Postgres's MVCC in particular, are specifically designed to deal
with concurrently servicing intensive read operations amidst bulk writes.
Speculating purely a priori, these delays are probably caused by very high I/O
demand of a slow storage subsystem; you can attempt to ascertain that by
running 'iostat -x 1' while loading the new data and looking at percentage
utilisation on the relevant storage interface, or with 'iotop' or similar tools.
But if the database responds slowly due to high background I/O load, you can't
make Kamailio render an answer any faster. About the only thing you can do is
to try mitigate the negative effects of this on the SIP level:
(1) Send a '100 Trying' pre-emptively before initiating the query; this will
dampen the retransmissions that otherwise occur, and whose proliferation could
cause a positive feedback loop and deepen your problems in a database slow-down
scenario;
(2) Do asynchronous processing of the SQL query with t_suspend() /
t_continue() -- though, you should carefully weigh the downsides of this given
the (small) additional overhead of suspending/resuming every transaction under
normal operating conditions.
For more background on this topic, consider a look at my blog post on the
subject from some years ago:
http://www.evaristesys.com/blog/tuning-kamailio-for-high-throughput-and-performance/
Hope that helps!
Cheers,
-- Alex
PS. You may wish to escape the value of '$rU' and not lift it directly into
your SQL queries, e.g.
https://www.kamailio.org/wiki/cookbooks/5.3.x/transformations#sescapecommon
https://www.kamailio.org/wiki/cookbooks/5.3.x/transformations#sqlval
Otherwise, you may be exposing yourself to a possible SQL injection attack,
i.e. if I get creative with what I put in the user part of the request URI in a
way that doesn't jam Kamailio's SIP parser.
--
Alex Balashov | Principal | Evariste Systems LLC
Tel: +1-706-510-6800 / +1-800-250-5920 (toll-free)
Web: http://www.evaristesys.com/, http://www.csrpswitch.com/
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