[asterisk-dev] Asterisk 1.8 SIP_CAUSE performance regression

[Matthew Nicholson]

When chan_sip sets MASTER_CHANNEL(HASH(SIP_CAUSE,<chan name>)) the
MASTER_CHANNEL function scans the channel list which can be a slow
operation. Under moderate traffic loads this causes delays in processing
sip messages which can cause retransmission timers to expire.

There is no other way to know the response code of a SIP message, but
depending on what you are using the response codes for, you may be able
to accomplish the same thing a different way. What are you using the
codes for?

Also be aware that this feature is not going away, it simply will be
disabled by default.

On Thu, 2011-08-18 at 15:49 +0300, ik wrote:
> I'm using it.
> 
> Can you please provide more information on the issue with this
> feature ? 
> Is there another way to know the response code of SIP ?
> 
> Thanks,
> 
> Ido
> 
> On Thu, Aug 18, 2011 at 15:42, Matthew Nicholson
> <mnicholson at digium.com> wrote:
>         Greetings,
>         
>         Recently a performance regression in chan_sip was discovered
>         in Asterisk
>         1.8. The regression is caused by chan_sip setting
>         MASTER_CHANNEL(HASH(SIP_CAUSE,<chan name>)) after each
>         response received
>         on a channel. That feature has been made optional in the
>         latest 1.8 SVN
>         code, but is currently still enabled by default. After some
>         internal
>         discussion, we decided to consider disabling this feature by
>         default in
>         future 1.8 versions. This would be an unexpected behavior
>         change for
>         anyone depending on that SIP_CAUSE update in their dialplan.
>         Alternatively, with this feature enabled, anyone upgrading
>         from Asterisk
>         1.4 will see a 60% decrease in the amount of SIP traffic they
>         can handle
>         before encountering problems.
>         
>         Before disabling this feature, we wanted to get a feel for how
>         many
>         people are using it. If you use this feature, please respond
>         to this
>         email and let us know.
>         --
>         Matthew Nicholson
>         Digium, Inc. | Software Developer
>         
>         
>         
>         
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-- 
Matthew Nicholson
Digium, Inc. | Software Developer