[Freeswitch-users] Installation report, a python crash and a bottleneck

Fri Jun 13 11:56:36 PDT 2008

What is really needed is an associated "cost' with the modules.
Granted, that is a hard thing to get a defined metric for.

Blanket statements like "Freeswitch does millions of calls a day, and
500 CPS, or whatever".. arent very useful to the rest of us without
knowing the configuration they are using.
Even if you rewrite your IVR in javascript, you still might have
problems.  Spidermonkey itself has some global contention in it too
and is not going to scale linearly.  But at what point is that even
noticed?

Given some predefined reference platform..it would be nice to look at
a chart of modules

mod_lua = 500 CPS
mod_spidermonkey = 300 CPS
mod_python = 50 CPS

2008/6/13 Brian West <brian at freeswitch.org>:
> Kresho,
> Thats because Anthony is on vacation and he didn't write mod_python.  I
> should have responded to you and let you know that.  He's the one that has
> to make the decision.  Its something we have discussed in the past few
> weeks.  As for production ready modules if you have to uncomment anything in
> modules.conf to compile then I would consider it on shaky ground unless
> otherwise noted.  Even Traun said mod_python needs to be removed or
> rewritten as of last week.  Which could happen when Anthony returns from
> vacation and reads your email sitting in the consulting queue.
> /b
> On Jun 13, 2008, at 1:17 PM, Kre?imir Tonkovi? wrote:
>
> Funny thing... I offered to pay for a fix for this bug by sending a mail to
> consulting at freeswitch.org, but nobody responded. Now I spent some of that
> money reimplementing the ivr in javascript. The rest is still there if
> somebody wants it :-)
>
> Regarding pythonistas and stake burnings - I just want the humongous number
> of libraries that come with python.
>
> I agree with David - pieces that aren't quite production ready should be
> marked as such.
>
> Regards,
> Kresho
>
> On Fri, Jun 13, 2008 at 7:05 PM, Brian West <brian at freeswitch.org> wrote:
>>
>> Also let me just say one last thing here.. As long as their is a bug
>> on Jira about this issue we will get around to it... it's just not a
>> top priority right now.
>>
>> /b
>>
>> On Jun 13, 2008, at 10:49 AM, David Knell wrote:
>>
>> > Hi Brian,
>> >
>> >> David,
>> >>      It has to work?  We have people running millions of min. a day
>> >> thru
>> >> FreeSWITCH and they have zero issues.
>> >
>> > Yes, but that misses the point.  They run millions of minutes
>> > through a
>> > well-tested subset of that which FS offers - we ran half a million
>> > mins
>> > a day during May through a couple of FS boxes with the odd corrupt
>> > CDR and occasional barf[1].
>> >
>> > But that doesn't mean that FS works in its entirety.  It means that it
>> > can
>> > be made to work, which is a very different thing.
>> >
>> >> If you have to add the module
>> >> to modules.conf and compile it.. that is outside the scope of what is
>> >> well tested and supported.  Lua is more tested but still isn't in the
>> >> default yet.  That might happen in 1.0.1.
>> >
>> > Here's the solution, then.  Someone who knows the answers could
>> > document the module status in modules.conf; that way, anyone who
>> > adds a less-well-supported module to their build will at least know
>> > about it.  As a quick aside, mod_xml_curl isn't in the default build;
>> > it is OK for production use, isn't it..?!
>> >
>> >> By the tone of your comments you're going to take mod_python under
>> >> your wing and make sure it works?  We do need more people to step up
>> >> and help.  ;)
>> >
>> > No, I'm not, I'm afraid - (a) I've too much on my plate to have a
>> > meaningful stab at it, and (b) I'm quite happy with curly brackets to
>> > indicate where my blocks start and end.  But if anyone wants a hand
>> > with writing IVRs or doing call routing using event sockets and Perl,
>> > I'd
>> > be very happy to help.
>> >
>> > --Dave
>> >
>> > [1] Mindful of the possibility of having already offended the
>> > Pythonistas
>> > by disrespecting whitespace as a syntactic tool, I probably shouldn't
>> > add that the * boxes which front-end that traffic worked without a
>> > glitch,
>> > less I find myself on the wrong end of a stake, a gallon of petrol, a
>> > pile
>> > of wood and a match ;-)
>> >
>> >
>> >>
>> >>
>> >> /b
>> >>
>> >> On Jun 13, 2008, at 9:34 AM, David Knell wrote:
>> >>
>> >>> Yes, but..
>> >>>
>> >>> Neither of Kresho's boxes are registering heavy CPU usage, which is
>> >>> what
>> >>> one would expect if this were to do with the overhead of Python.  In
>> >>> addition,
>> >>> there's the crashes.
>> >>>
>> >>> On to a hobby horse of mine.  If FS is going to make it in the real
>> >>> world, then
>> >>> it has to work.  And that means that the bits which come with it
>> >>> need
>> >>> to work,
>> >>> and those which don't need to be separated off into a 'beta', 'don't
>> >>> expect
>> >>> much from this', 'FFS don't use unless you're prepared to fix it' or
>> >>> whatever
>> >>> repository.
>> >>>
>> >>> New users, such as Kresho, will use whichever scripting tool/
>> >>> language/
>> >>> interface suits their needs and that they're familiar with.  And
>> >>> they'll have the
>> >>> expectation that it'll work, and that expectation is perfectly
>> >>> reasonable.
>> >>> Keeping bits in the "release" source tree which don't work properly
>> >>> or
>> >>> which
>> >>> have failings which make them unsuitable for production use does FS
>> >>> (which is a great thing) a disservice.
>> >>>
>> >>> Cheers --
>> >>>
>> >>> Dave
>> >>>
>> >>>> Python is very heavy.. You should try lua.
>> >>>>
>> >>>> /b
>> >>>>
>> >>>> On Jun 12, 2008, at 5:29 AM, Krešimir Tonković wrote:
>> >>>>
>> >>>>> Hi!
>> >>>>>
>> >>>>> I'm new to freeswitch and I like to report my success with it
>> >>>>> and a
>> >>>>> few failures. I'll be a little bit vague on some details because I
>> >>>>> must protect some business details. Sorry for that.
>> >>>>>
>> >>>>> I have no experience with asterisk, so many concepts were new to
>> >>>>> me.
>> >>>>>
>> >>>>> We run a hosted IVR system with a few hundred lines. We have a few
>> >>>>> servers running a SIP/VoiceXML application server and connect to
>> >>>>> the
>> >>>>> network with SIP/ISDN gateways.
>> >>>>>
>> >>>>> Recently we started an IVR with very short calls and very high
>> >>>>> CPS.
>> >>>>> Our existing software doesn't handle this scenario very well, so I
>> >>>>> started looking into alternatives.
>> >>>>>
>> >>>>> FreeSwitch caught my eye because of its support for multiple
>> >>>>> scripting languages. I love python and this feature put FS into
>> >>>>> the
>> >>>>> evaluation list. So I started on friday. I installed FS from the
>> >>>>> debian repositories on my ubuntu 8.04 laptop and tried some
>> >>>>> examples
>> >>>>> from the wiki ("Some thing to try out!"). I was very impressed
>> >>>>> that
>> >>>>> everything worked right out of the box.
>> >>>>>
>> >>>>> I was a little disappointed that mod_python wasn't included in the
>> >>>>> distribution so I checked out the source and compiled everything.
>> >>>>> An
>> >>>>> hour later I had another installation of FS.
>> >>>>>
>> >>>>> It took me a few hous to get the dialplan right. Because our
>> >>>>> service
>> >>>>> only runs IVRs and uses no switching, I removed everything from
>> >>>>> the
>> >>>>> default dialplan (mainly because it conflicted with the ANI
>> >>>>> numbers
>> >>>>> we get from the gateways).
>> >>>>>
>> >>>>> Another hour later, I had a simple IVR in python done: use a web
>> >>>>> service for a database lookup and play an appropriate prompt. I
>> >>>>> didn't use the database directly because I wanted the best
>> >>>>> possible
>> >>>>> comparison to what our current system does, and (our) VoiceXML
>> >>>>> can't
>> >>>>> use databases directly, but can use web services.
>> >>>>>
>> >>>>> In less than 1 working day I had everything running. Quite good.
>> >>>>>
>> >>>>> Time for load testing :-) Our old software handles around 20 CPS
>> >>>>> on
>> >>>>> my laptop. I inceased max_sessions to 5000 and sessions-per-second
>> >>>>> to 100 and started sipp. The result was quite bad - I could not
>> >>>>> get
>> >>>>> over 8 CPS! The processor barely noticed that FS was running, so I
>> >>>>> had no idea what the bottleneck was. I still don't. After fiddling
>> >>>>> with this for a while, I gave up and decided to try it on one of
>> >>>>> our
>> >>>>> production machines. Weekends are not very busy, so I took one
>> >>>>> offline. It's a HP proliant server with 1 quad-core xeon on 2 GHz,
>> >>>>> 2G ecc ram and 10krpm disks. The server is also running ubuntu
>> >>>>> 8.04
>> >>>>> (server edition) so I just copied the binaries.
>> >>>>>
>> >>>>> I ran sipp from another machine, with the uac scenario and
>> >>>>> limiting
>> >>>>> the call duration to 4secs:
>> >>>>> sipp <FS server ip> -sn uac -d 4000 -s <ivr_number>
>> >>>>> Theoretically, as each call lasts 4 seconds, the total calls
>> >>>>> number
>> >>>>> should never exceed 4x current CPS.
>> >>>>>
>> >>>>> These are the results:
>> >>>>>
>> >>>>> With up to 27 CPS everything was stable. The calls count was
>> >>>>> almost
>> >>>>> exactly 4 timee the CPS, indicating that new calls were ansewered
>> >>>>> immediately. This I also verified by calling in.
>> >>>>>
>> >>>>> Up to 30 CPS everything was stable for a while, but then the total
>> >>>>> calls number exploded to the limit set by sipp. The processor load
>> >>>>> was very reasonable, so I again I ran into the bottleneck
>> >>>>> mentioned
>> >>>>> above. After sipp hits the total call limit, it will not create
>> >>>>> new
>> >>>>> calls until some are released. So CPS oscillated between 0 and 30
>> >>>>> as
>> >>>>> shown by sipp. CDRs show that there was an average of 27 CPS. At
>> >>>>> this point, when I called in, I got ringback tone for as long as
>> >>>>> the
>> >>>>> operator allows (60s) and then I was dropped. With a softphone I
>> >>>>> could reach the IVR after about 80 sec.
>> >>>>>
>> >>>>> When I set sipp to more than 30 CPS, the number of total calls
>> >>>>> exploded immediately.
>> >>>>>
>> >>>>> Experimenting some more, I found I could contain the explosion
>> >>>>> (and
>> >>>>> the instability in CPS) by limiting the number of total calls to
>> >>>>> 4x
>> >>>>> current cps when cps was up to 30. Thus, by starting sipp like
>> >>>>> this:
>> >>>>> sipp <FS server ip> -sn uac -d 4000 -s <ivr_number> -l 120
>> >>>>> I could go up to 30CPS and get reasonably stable real 30CPS. When
>> >>>>> calling in with a real phone, I would reach the IVR after 2-3
>> >>>>> seconds of ringback, which is acceptable. This simulation run for
>> >>>>> several hours without any other problems.
>> >>>>>
>> >>>>> With
>> >>>>> sipp <FS server ip> -sn uac -d 4000 -s <ivr_number> -l 160
>> >>>>> and setting cps to 40, the total calls count obviously never
>> >>>>> passed
>> >>>>> 160, but the cps shown by sipp became unstable, oscillating
>> >>>>> between
>> >>>>> 0 and 40.
>> >>>>>
>> >>>>> These results are only slightly better than our current SIP
>> >>>>> server.
>> >>>>>
>> >>>>> Today I put FreeSwitch into production. The unexpected thing here
>> >>>>> was that when FreeSwitch talked to our gateways instead of sipp,
>> >>>>> it
>> >>>>> crashed a few times. I don't associate these crashes with load
>> >>>>> because it happened equally on low and high load. Here's the log:
>> >>>>>
>> >>>>> 2008-06-09 09:34:33 [NOTICE] switch_core_session.c:753
>> >>>>> switch_core_session_thread() Session 166 (sofia/internal/----
>> >>>>> deleted stuff -----) Ended
>> >>>>> 2008-06-09 09:34:33 [NOTICE] switch_core_session.c:755
>> >>>>> switch_core_session_thread() Close Channel sofia/internal/----
>> >>>>> deleted stuff ----- [CS_HANGUP]
>> >>>>> 2008-06-09 09:34:33 [CRIT] switch_core_state_machine.c:218
>> >>>>> print_trace() Obtained 10 stack frames.
>> >>>>> /usr/local/freeswitch/lib/libfreeswitch.so.1 [0xb7e413b1]
>> >>>>> [0xb7f69420]
>> >>>>> /usr/local/freeswitch/mod/mod_python.so [0xb011b46a]
>> >>>>> /usr/lib/libpython2.5.so.1.0(PyCFunction_Call+0xfa) [0xb002a50a]
>> >>>>> /usr/lib/libpython2.5.so.1.0(PyObject_Call+0x37) [0xafff38d7]
>> >>>>> /usr/lib/libpython2.5.so.1.0(PyEval_EvalFrameEx+0x4067)
>> >>>>> [0xb0076907]
>> >>>>> /usr/lib/libpython2.5.so.1.0(PyEval_EvalCodeEx+0x748) [0xb007a368]
>> >>>>> /usr/lib/libpython2.5.so.1.0(PyEval_EvalFrameEx+0x601c)
>> >>>>> [0xb00788bc]
>> >>>>> /usr/lib/libpython2.5.so.1.0(PyEval_EvalCodeEx+0x748) [0xb007a368]
>> >>>>> /usr/lib/libpython2.5.so.1.0 [0xb001667f]
>> >>>>> 2008-06-09 09:34:33 [CRIT] switch_core_state_machine.c:319
>> >>>>> switch_core_session_run() Thread has crashed for channel sofia/
>> >>>>> internal/---- deleted stuff -----
>> >>>>>
>> >>>>> It seems like mod_python is not quite ready for production
>> >>>>> yet :-) I
>> >>>>> have a few core dumps available on demand, cca 2MB each.
>> >>>>>
>> >>>>> Turning crash protection on didn't help. FreeSwitch would reject
>> >>>>> new
>> >>>>> calls, and wouldn't shutdown completely. I had to kill it.
>> >>>>>
>> >>>>> I would still like to replace our existing system with FreeSwitch
>> >>>>> because I find way more comfortable to work with. It has great
>> >>>>> potential and I'm sure it is being succesully deployed in many
>> >>>>> places as I write this.
>> >>>>>
>> >>>>> The python crash is probably a simple bug. The invisible
>> >>>>> bottleneck
>> >>>>> is what troubles me more. Any help would be greatly appreciated.
>> >>>>>
>> >>>>> Finally, this is all with FreeSwitch Version 1.0.pre4 (8760).
>> >>>>> --
>> >>>>> kresho
>> >>>>> _______________________________________________
>> >>>>> Freeswitch-users mailing list
>> >>>>> Freeswitch-users at lists.freeswitch.org
>> >>>>> http://lists.freeswitch.org/mailman/listinfo/freeswitch-users
>> >>>>>
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>> >>>>> http://www.freeswitch.org
>> >>>>
>> >>>>
>> >>>> _______________________________________________
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>> >>>
>> >>>
>> >>> _______________________________________________
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>> >>
>> >> Brian West
>> >> sip:brian at freeswitch.org
>> >>
>> >>
>> >>
>> >>
>> >> _______________________________________________
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>> >
>> >
>> > _______________________________________________
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>>
>> Brian West
>> sip:brian at freeswitch.org
>>
>>
>>
>>
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>
>
>
> --
> kresho _______________________________________________
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> Brian West
> sip:brian at freeswitch.org
>
>
>
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