[Freeswitch-users] XML_CURL max connection limit

Wed Jun 12 20:54:37 MSD 2013

I don’t think Dave even mentioned anything about Windows his rant.

From: freeswitch-users-bounces at lists.freeswitch.org
[mailto:freeswitch-users-bounces at lists.freeswitch.org] On Behalf Of Cal
Leeming [Simplicity Media Ltd]
Sent: Wednesday, June 12, 2013 9:39 AM
To: FreeSWITCH Users Help
Subject: Re: [Freeswitch-users] XML_CURL max connection limit

Dave, with all due respect, every time the discussion of mod_xml_curl or
anything non-windows comes up you immediately throw in a negative note, and
it's starting to get a bit old now. Until one of the core devs steps up and
says "you shouldn't be using mod_xml_curl" then I don't think it's right to
be telling users that this is the wrong approach to be using - especially
when we don't even know if it's mod_xml_curl that is causing the problem in
this particular case. As mentioned in the last email, the next steps for OP
is to identify the root cause of these delays, either via profiling or print
statements.

OP - I think at this point, you really need to take this over to a JIRA
ticket to avoid spamming the mailing list, as the thread is starting to go a
bit stale.

Once you've created a ticket, let us know in this thread and we'll see about
getting a core dev to give it some eyes.

If this is an urgent matter, you could also pay for a few hours of FS
support which will get the immediate attention of a core dev :)

Cal

On Wed, Jun 12, 2013 at 5:19 PM, Dave R. Kompel <drk at drkngs.net> wrote:

Ok, this "square peg in rouond hole" thread is not getting anything solved.
You all need to take a step back, and look at the overall diesign of the
applcation you are trying to build from a top down approch.

First define what the application has to do, with all of it's requirements,
including load, resonse times, what information you need to look up per
call, and so on...

This seems to me like a backwards approch was taken, as the start of the
project, mod_xml_curl was the starting point, and then the application was
designed after the method was picked. Isn't this "bass awards"? I know if I
wasted my clients time and money by picking tech. before defining the
problem, I would have no clients!

One thing I can tell you for sure, is that using a design that involves both
client and server side synchronous technologies as the starting point, isn’t
going to scale out to carrier rate call handling. You can try throwing all
sorts of stuff like different web servers, caching proxies in the middle,
and a handful of other kludges at it, and all you’re going to get is a big
“Cluster F
”, that will be a nightmare to maintain and scale. You may also
become a slave to maintaining it, and monitoring your production
environment.

One other thing to remember about FreeSWITCH, is that mod_xml_curl is not
the only way of doing XML config binding to code. There are many modules
that use the callback to implement feeding FS with real time XML config on
demand. 

It may be time to re-design your application, rather then trying to build a
“better mousetrap” on the external side. We could discuss this on the
conference call today, and get input from all the folks on a design, given
your requirements

--Dave

  _____  

From: Muhammad Shahzad [mailto:shaheryarkh at gmail.com]
To: FreeSWITCH Users Help [mailto:freeswitch-users at lists.freeswitch.org]
Sent: Wed, 12 Jun 2013 07:57:18 -0700
Subject: Re: [Freeswitch-users] XML_CURL max connection limit

Well, per our observation, we don't see any load or delay from xml curl or
web server side. Also the delay is occurring exactly at one location that is
after sending 183 Early Media and sending first RTP packet of IVR. When CPS
is below 25 this delay is less then 0.20 seconds but after 30 CPS it goes
beyond 3.10 seconds. 

Regarding New Relic, we don't have WAN access on server, since its a closed
environment at telco data center. Also we see the behavior remains the same
if we add multiple FS serve by same web server. So, i think problem is on FS
side rather then web server side.

Thank you.

On Wed, Jun 12, 2013 at 4:31 PM, Cal Leeming [Simplicity Media Ltd]
<cal.leeming at simplicitymedialtd.co.uk> wrote:

Curious, I'm wondering if maybe excessive context switching is causing some
issues.. I'm wondering if the latency is actually caused by the overheads on
mod_xml_curl. 

Could you try putting New Relic on your application, and see what sort of
response times you get? That will identify which queries are taking a while
to process.

Cal 

On Wed, Jun 12, 2013 at 3:14 PM, Muhammad Shahzad <shaheryarkh at gmail.com>
wrote:

We are already monitoring using top and htop. Even per core view of top
shows no core every goes beyond 40%, average varies between 21 - 33%.

Thank you.

On Wed, Jun 12, 2013 at 4:02 PM, Cal Leeming [Simplicity Media Ltd]
<cal.leeming at simplicitymedialtd.co.uk> wrote:

You could either throw Cacti on the server, or use server density/new relic
trial for quick and easy graphing.. or you can just watch `top` and push
number 1 whilst running to see the CPU breakdown. 

Cal 

On Wed, Jun 12, 2013 at 1:19 PM, Muhammad Shahzad <shaheryarkh at gmail.com>
wrote:

Steven, i am using soft timer. Should i try another? Please suggest. 

Cal, no there is nothing unusually changes in RAM or CPU. BTW, i have 24 CPU
cores with 16 GB of RAM on each server. Regarding CPU graph, how can i
enable it.

Thank you.

On Wed, Jun 12, 2013 at 1:15 PM, Cal Leeming [Simplicity Media Ltd]
<cal.leeming at simplicitymedialtd.co.uk> wrote:

This sounds quite interesting.. From my own benchmarks, I've seen that IVRs
applications can be quite stressful on the server. 

Have you checked to see if there is a CPU util spike or context switching
spike during these tests? Perhaps you are hitting the floor limit of what
your CPU is capable of?

Do you have CPU graphs? If not, can you enable them and try again?

Cal 

On Wed, Jun 12, 2013 at 10:21 AM, Muhammad Shahzad <shaheryarkh at gmail.com>
wrote:

You are right. After many improvements and modifications to dail plan,
removing unnecessary modules and using Ngnix web server, things are much
better now. Except that directory information is fetched 3 times per call
and there are overall 4 HTTP hits in a single call (3 for user + 1 for dial
plan). 

Since Monday, we have started analyzing the results of load test, specially
looking into packet traces, voicemail recordings and so on. We observed a
strange thing, although we were able to test 1536 concurrent calls (the
limit we deliberately put in switch.xml.conf) at up to 64 calls per second
rate. But there is strange and unexplained delay in starting RTP from FS
side.

FS plays an IVR in early media state, then answers the call to directly
start recording voicemail. The problem is if call rate is under 25 CPS,
everything works fine. At 25 CPS there is minor delay in starting RTP in
early media state. This delay is negligible after processing few hundred
thousand calls but after about 1.2 million calls the delay has creeps up to
about 1.2 seconds. After 30 CPS this delay is significantly increases to 2
second after around 400 calls had done. At 50 CPS its ~3 second and after 60
CPS its around 4 seconds. Interesting thing is the delay is ONLY in starting
playing IVR in early media state, once the IVR starts playing everything
works perfectly fine. No call fails, but this delay would be annoying for
anyone using the servers with over 30 CPS.

Just to let you know, we checked everything, system resources, bandwidth
usage, IVR file formats etc. all seems to be fine. We even tested with
various FS start up options, e.g. -rp -nosql -nonat etc. etc. Nothing seems
to have any impact on the results.

I have run of out of possible explanations, so calling you guys for help.

Thank you.

On Fri, Jun 7, 2013 at 5:20 PM, Michael Jerris <mike at jerris.com> wrote:

I would need to see the specifics of your dialplan, but I suspect you have
some transfers or execute extension that are causing it to re-enter
dialplan.  Are you sure on all the others that they are making the exact
same requests?  Details here will be necessary to understand exactly what is
going on.. 

Mike

On Jun 7, 2013, at 4:07 AM, Muhammad Shahzad <shaheryarkh at gmail.com> wrote:

Guy, after detailed analysis i can confirm it was an Apache issue, and
changing Apache configuration changes the concurrent call limit. However,
one thing i observed about xml curl is that it makes several request with
same parameters per call. Even if we have no calls running on server, as
well as as Apache is completely free. I can see FS makes at least 

1). 3 hits for dialplan.

2). 2 hits for directory.

3). 4 hits for voicemail.

4). 3 hits for ivr.

5). 2 hits for sofia.

and so on..

While ideally only one hit should be sufficient to get all these
configurations. What is the point of making all these redundant hits? We
have roughly 15 - 20 hits made per call, which is huge and causes
significant load on Apache.

Both Apache and FS are running on dedicated machines and connected over
Gigabit Ethernet with zero packet loss, so i doubt these hits are
"re-transmission".

Thank you.

On Thu, Jun 6, 2013 at 1:24 AM, Muhammad Shahzad <shaheryarkh at gmail.com>
wrote:

Yes, its a feature, i know. I was just looking at how this feature was
tested, as mentioned in its logs, 

2010-01-04 15:01:51.945020 [INFO] mod_dialplan_xml.c:408 Processing
21653XXXXX->121637XXXXX in context termination
2010-01-04 15:01:52.054466 [ERR] mod_xml_curl.c:310 Received HTTP error 0
trying to fetch  <http://192.168.0.2/gateway.php>
http://192.168.0.2/gateway.php
2010-01-04 15:01:52.054545 [CONSOLE] mod_xml_curl.c:317 XML response is in
/tmp/6632ebb1-d19f-4d51-a07e-ec2ce0387f83.tmp.xml

Thank you.

On Thu, Jun 6, 2013 at 12:48 AM, Michael Jerris <mike at jerris.com> wrote:

This is adding a feature to allow timeout to be set in ms instead of
seconds.  This is not a problem, its a feature, that was added a while ago.
Until you can determine if the request is being sent for the one thats
failing, your not going to solve this issue. 

Mike

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Mit freundlichen Grüßen

Muhammad Shahzad
-----------------------------------
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Cell: +49 176 99 83 10 85 <tel:%2B49%20176%2099%2083%2010%2085> 
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Mit freundlichen Grüßen

Muhammad Shahzad
-----------------------------------
CISCO Rich Media Communication Specialist (CRMCS)
CISCO Certified Network Associate (CCNA)
Cell: +49 176 99 83 10 85 <tel:%2B49%20176%2099%2083%2010%2085> 
MSN:  <mailto:shari_786pk at hotmail.com> shari_786pk at hotmail.com
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_________________________________________________________________________
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 </> 

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Mit freundlichen Grüßen

Muhammad Shahzad
-----------------------------------
CISCO Rich Media Communication Specialist (CRMCS)
CISCO Certified Network Associate (CCNA)
Cell: +49 176 99 83 10 85 <tel:%2B49%20176%2099%2083%2010%2085> 
MSN:  <mailto:shari_786pk at hotmail.com> shari_786pk at hotmail.com
Email:  <mailto:shaheryarkh at googlemail.com> shaheryarkh at googlemail.com 

_________________________________________________________________________
Professional FreeSWITCH Consulting Services:
consulting at freeswitch.org
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 </> 

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http://www.freeswitch.org <http://www.freeswitch.org/> 
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Mit freundlichen Grüßen

Muhammad Shahzad
-----------------------------------
CISCO Rich Media Communication Specialist (CRMCS)
CISCO Certified Network Associate (CCNA)
Cell: +49 176 99 83 10 85 <tel:%2B49%20176%2099%2083%2010%2085> 
MSN:  <mailto:shari_786pk at hotmail.com> shari_786pk at hotmail.com
Email:  <mailto:shaheryarkh at googlemail.com> shaheryarkh at googlemail.com 

_________________________________________________________________________
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