[SR-Users] Kamailio propagates 180 and 200 OK OUT OF ORDER
Alex Balashov
abalashov at evaristesys.com
Fri Apr 10 14:02:49 CEST 2020
Luis,
I wonder, how many CPU cores/available hardware threads (taking into account HyperThreading and all that—so just the number of CPUs in /proc/cpuinfo) are available here? It almost sounds like something which would occur with maybe 1 or 2 CPUs being contended over. Perhaps the simplest thing for this kind of call volume is to run Kamailio on a host with 8 or 12+ CPU cores?
— Alex
—
Sent from my iPad
> On Apr 10, 2020, at 2:20 AM, Luis Rojas G. <luis.rojas at sixbell.com> wrote:
>
>
> Hello,
>
> I have a lot of experience developing mutithreaded applications, and I don't see it so unlikely at all that a process loses cpu just after recvfrom(). It's just as probable as to lose it just before, or when writing on a cache or just before of after sendto(). If there are many messages going through, some of them will fall in this scenario. if I try sending a burst of 100 messages, I see two or three presenting the scenario.
>
> Just forward() with a single process does not give the capacity. I'm getting almost 1000caps. More than that and start getting errores, retransmissions, etc. And this is just one way. I need to receive the call to go back to the network (our application is a B2BUA), so I will be down to 500caps, with a simple scenario, with no reliable responses, reinvites, updates, etc. I will end up having as many standalone kamailio processes as the current servers I do have now.
>
> I really think the simplest way would be to add a small delay to 200 OK. Very small, like 10ms, should be enough. Simple and it should work. As Alex Balashov commented he did for the case with ACK-Re-Invite.
>
> I have to figure out how to make async_ms_sleep() work in reply_route().
>
> Thanks for all the comments and ideas
>
> Best regards,
>
> Luis
>
>
>
> . On 4/9/20 12:17 PM, Daniel-Constantin Mierla wrote:
>>
>>
>> MICONDA at GMAIL.COM appears similar to someone who previously sent you email, but may not be that person. Learn why this could be a risk
>> Feedback
>> Hello,
>>
>> then the overtaking is in between reading from the socket and getting to parsing the call-id value -- the cpu is lost by first reader after recvfrom() and the second process get enough cpu time to go ahead further. I haven't encountered this case, but as I said previously, it is very unlikely, but still possible. I added the route_locks_size because in the past I had cases when processing of some messages took longer executing config (e.g., due to authentication, accounting, ..) and I needed to be sure they are processed in the order they enter config execution.
>>
>> Then the option is to see if a single process with stateless sending out (using forward()) gives the capacity, if you don't do any other complex processing. Or if you do more complex processing, use a dispatcher process with forwarding to local host or in a similar manner try to use mqueue+rtimer for dispatching using shared memory queues.
>>
>> Of course, it is open source and there is also the C coding way, to add a synchronizing mechanism to protect against parallel execution of the code from recvfrom() till call-id lock is acquired.
>>
>> Cheers,
>> Daniel
>>
>> On 09.04.20 17:37, Luis Rojas G. wrote:
>>> Hello,
>>>
>>> Well, it did not work at all. Exactly same behavior, with random out of order messages.
>>>
>>> Best regards,
>>>
>>> Luis
>>>
>>> On 4/9/20 11:28 AM, Daniel-Constantin Mierla wrote:
>>>>
>>>>
>>>> MICONDA at GMAIL.COM appears similar to someone who previously sent you email, but may not be that person. Learn why this could be a risk
>>>> Feedback
>>>> Hello,
>>>>
>>>> the sip messages belonging to the same dialog have the same value for Call-Id header. The locking is done based on hashing the Call-Id, so it doesn't need at all the dialog module for its purpose.
>>>>
>>>> Cheers,
>>>> Daniel
>>>>
>>>> On 09.04.20 14:19, Luis Rojas G. wrote:
>>>>> Hello, Daniel,
>>>>>
>>>>> I am not so sure. I first tried adding that parameter, but it did not work at all. Same behavior. Then I read the documentation more carefully :
>>>>>
>>>>> https://www.kamailio.org/wiki/cookbooks/devel/core#route_locks_size
>>>>> route_locks_size
>>>>>
>>>>> Set the number of mutex locks to be used for synchronizing the execution of messages sharing the same Call-Id. In other words, enables Kamailio to execute the config script sequentially for the requests and replies received within the same dialog – a new message received within the same dialog waits until the previous one is routed out.
>>>>>
>>>>> Locks to execute sequentially messages belonging to same dialog. How will Kamailio be aware that messages belong to same dialog, without the dialog module?. With just stateless proxy it has no idea about dialogs, it just forwards messages. I guess that's why just adding that parameter did not work.
>>>>>
>>>>> Am I wrong?
>>>>>
>>>>> Luis
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> On 4/9/20 3:47 AM, Daniel-Constantin Mierla wrote:
>>>>>> Hello,
>>>>>>
>>>>>> On 08.04.20 23:03, Luis Rojas G. wrote:
>>>>>>> Hello, Daniel,
>>>>>>>
>>>>>>> I looked into that parameter, but I need to use with the dialog module, and I'm pretty afraid to use that.
>>>>>> who said or where is written than you need to load the dialog module? You definitely don't.
>>>>>>
>>>>>> Cheers,
>>>>>> Daniel
>>>>>>
>>>>>>
>>>>>>
>>>>>>> I was looking more into the stateless proxy, because I need to process a lot of traffic.
>>>>>>>
>>>>>>> My target is 4200CAPS. with duration between 90s and 210. Let's say, 150 seconds. That would mean 630.000 simultaneous dialogs. I don't think the solution can go that way.
>>>>>>>
>>>>>>> it would really help me to be able to use completely stateless proxy plus Async in reply_route(), to introduce an artificial delay before forwarding 200 OK to Invite.. As someone mentioned, it would help me on request_route(), for race conditions between ACK and Re-Invite.
>>>>>>>
>>>>>>> Any idea why Async is not allowed in reply_route()?
>>>>>>>
>>>>>>> Best regards,
>>>>>>>
>>>>>>> Luis
>>>>>>>
>>>>>>>
>>>>>>> On 4/8/20 1:07 PM, Daniel-Constantin Mierla wrote:
>>>>>>>> Hello,
>>>>>>>>
>>>>>>>> you have to keep in mind that Kamailio is a SIP packet router, not a telephony engine. If 180 and 200 replies are part of a call is not something that Kamailio recognize at its core. Its main goal is to route out as fast as possible what is received, by executing the configuration file script. Now, a matter of your configuration file, processing of some SIP messages can take longer than processing other. And the processing is done in parallel, a matter of children parameter (and tcp_children, sctp_children).
>>>>>>>>
>>>>>>>> With that in mind, a way to try to cope better with the issue you face is to set route_locks_size parameter, see:
>>>>>>>>
>>>>>>>> * https://www.kamailio.org/wiki/cookbooks/devel/core#route_locks_size
>>>>>>>>
>>>>>>>> Probably is what you look for.
>>>>>>>>
>>>>>>>> But if you want more tight constraints, like when receiving a 180 after a 200ok and not route it out, you have to make the logic in configuration file by combining modules such as dialog or htable (as already suggested).
>>>>>>>>
>>>>>>>> Cheers,
>>>>>>>> Daniel
>>>>>>>>
>>>>>>>> On 08.04.20 16:04, Luis Rojas G. wrote:
>>>>>>>>> Hi, Henning,
>>>>>>>>>
>>>>>>>>> No need to be ironic. As I mentioned on my first post, I tried stateful proxy and I observed the same behavior.
>>>>>>>>>
>>>>>>>>> "I tried using stateful proxy and I obtained the same result."
>>>>>>>>>
>>>>>>>>> The asynchronous sleep seems promising. I will look into it.
>>>>>>>>>
>>>>>>>>> Thanks,
>>>>>>>>>
>>>>>>>>> Luis
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> On 4/8/20 9:30 AM, Henning Westerholt wrote:
>>>>>>>>>> Hi Luis,
>>>>>>>>>>
>>>>>>>>>> I see. Well, you want to use Kamailio as a stateless proxy, on the other hand it should do things that are inherently stateful. 😉
>>>>>>>>>>
>>>>>>>>>> As mentioned, have a look to the dialog module to track the state of dialogs that you process. This will not work in a stateless mode, though.
>>>>>>>>>>
>>>>>>>>>> You can also use the htable module to just store some data about the processed messages in a shared memory table and use this to enforce your ordering. There is also the option to do an asynchronous sleep (with the async) module on the message that you want to delay but still processing other messages during it.
>>>>>>>>>>
>>>>>>>>>> Cheers,
>>>>>>>>>>
>>>>>>>>>> Henning
>>>>>>>>>>
>>>>>>>>>> --
>>>>>>>>>> Henning Westerholt – https://skalatan.de/blog/
>>>>>>>>>> Kamailio services – https://gilawa.com
>>>>>>>>>>
>>>>>>>>>> From: Luis Rojas G. <luis.rojas at sixbell.com>
>>>>>>>>>> Sent: Wednesday, April 8, 2020 3:00 PM
>>>>>>>>>> To: Henning Westerholt <hw at skalatan.de>; Kamailio (SER) - Users Mailing List <sr-users at lists.kamailio.org>
>>>>>>>>>> Subject: Re: [SR-Users] Kamailio propagates 180 and 200 OK OUT OF ORDER
>>>>>>>>>>
>>>>>>>>>> Hello, Henning,
>>>>>>>>>>
>>>>>>>>>> I am worried about this scenario, because it's a symptom of what may happen in other cases. For instance, I've seen that this operator usually sends re-invites immediate after sending ACK. This may create race conditions like 3.1.5 of RFC5407
>>>>>>>>>>
>>>>>>>>>> https://tools.ietf.org/html/rfc5407#page-22
>>>>>>>>>>
>>>>>>>>>> I'd understand that one happens because of packet loss, as it's in UDP's nature, but in this case it would be artificially created by Kamailio. if there was no problem at network level (packet loss, packets following different path on the network and arriving out of order), why Kamailio creates it?
>>>>>>>>>>
>>>>>>>>>> I'd expect that the shared memory is used precisely for this. If an instance of kamailio receives a 200 OK, it could check on the shm and say "hey, another instance is processing a 180 for this call. Let's wait for it to finish" (*). I know there could still be a problem, the instance processing the 180 undergoes a context switch just after it receives the message, but before writing to shm, but it would greatly reduce the chance.
>>>>>>>>>>
>>>>>>>>>> In our applications we use a SIP stack that always sends messages to the application in the same order it receives them, even though is multi-threaded and messages from the network are received by different threads. So, they really syncronize between them. Why Kamailio instances don't?
>>>>>>>>>>
>>>>>>>>>> I am evaluating kamailio to use it as a dispatcher to balance load against our several Application Servers, to present to the operator just a couple of entrance points to our platform (they don't want to establish connections to each one of our servers). This operator is very difficult to deal with. I am sure they will complain something like "why are you sending messages out of order? Fix that". The operator will be able to see traces and check that messages entered the Kamailio nodes in order and left out of order. They will not accept it.
>>>>>>>>>>
>>>>>>>>>> (*) Not really "wait", as it would introduce a delay in processing all messages. it should be like putting it on a queue, continue processing other messages, and go back to the queue later.
>>>>>>>>>>
>>>>>>>>>> Well, thanks for your answer.
>>>>>>>>>>
>>>>>>>>>> Luis
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> On 4/8/20 3:01 AM, Henning Westerholt wrote:
>>>>>>>>>> Hello Luis,
>>>>>>>>>>
>>>>>>>>>> as the 1xx responses are usually send unreliable (unless you use PRACK), you should not make any assumption on the order or even the arrival of this messages. It can also happens on a network level, if send by UDP.
>>>>>>>>>>
>>>>>>>>>> Can you elaborate why you think this re-ordering is a problem for you?
>>>>>>>>>>
>>>>>>>>>> One idea to enforce some ordering would be to use the dialog module in combination with reply routes and the textops(x) module.
>>>>>>>>>>
>>>>>>>>>> About the shared memory question – Kamailio implement its own memory manager (private memory and shared memory pool).
>>>>>>>>>>
>>>>>>>>>> Cheers,
>>>>>>>>>>
>>>>>>>>>> Henning
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> --
>>>>>>>>>> Henning Westerholt – https://skalatan.de/blog/
>>>>>>>>>> Kamailio services – https://gilawa.com
>>>>>>>>>>
>>>>>>>>>> From: sr-users <sr-users-bounces at lists.kamailio.org> On Behalf Of Luis Rojas G.
>>>>>>>>>> Sent: Tuesday, April 7, 2020 10:43 PM
>>>>>>>>>> To: sr-users at lists.kamailio.org
>>>>>>>>>> Subject: [SR-Users] Kamailio propagates 180 and 200 OK OUT OF ORDER
>>>>>>>>>>
>>>>>>>>>> Good day,
>>>>>>>>>>
>>>>>>>>>> I am testing the dispatcher module, using Kamailio as stateless proxy. I have a pool of UAC (scripts in SIPP) and a pool of UAS (also scripts in SIPP) for the destinations. Kamailio version is kamailio-5.3.3-4.1.x86_64.
>>>>>>>>>>
>>>>>>>>>> Problem I have is, if UAS responds 180 and 200 OK to Invite immediately, sometimes they are propagated out of order. 200 OK before 180, like this :
>>>>>>>>>>
>>>>>>>>>> <image001.png>
>>>>>>>>>>
>>>>>>>>>> UAS is 172.30.4.195:5061. UAC is 172.30.4.195:5080. Kamailio is 192.168.253.4:5070
>>>>>>>>>>
>>>>>>>>>> Difference between 180 and 200 is just about 50 microseconds.
>>>>>>>>>>
>>>>>>>>>> My guess is that both messages are received by different instances of Kamailio, and then because of context switches, even though the 180 is received before, that process ends after the processing of 200. However, I had the idea that in order to avoid these problems the kamailio processes synchronized with each other using a shared memory. I tried using stateful proxy and I obtained the same result.
>>>>>>>>>>
>>>>>>>>>> By the way, anyone has any idea about how Kamailio's share memory is implemented? It clearly does not use the typical system calls shmget(), shmat(), because they are not shown by ipcs command.
>>>>>>>>>>
>>>>>>>>>> Before posting here I googled, but I couldn't find anything related to this. I can't believe I am the only one who ever had this problem, so I guess I am doing something wrong...
>>>>>>>>>>
>>>>>>>>>> Please, any help. I'm really stuck on this.
>>>>>>>>>>
>>>>>>>>>> Thanks.
>>>>>>>>>>
>>>>>>>>>> --
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> --
>>>>>>>>>> Luis Rojas
>>>>>>>>>> Software Architect
>>>>>>>>>> Sixbell
>>>>>>>>>> Los Leones 1200
>>>>>>>>>> Providencia
>>>>>>>>>> Santiago, Chile
>>>>>>>>>> Phone: (+56-2) 22001288
>>>>>>>>>> mailto:luis.rojas at sixbell.com
>>>>>>>>>> http://www.sixbell.com
>>>>>>>>>
>>>>>>>>> --
>>>>>>>>> Luis Rojas
>>>>>>>>> Software Architect
>>>>>>>>> Sixbell
>>>>>>>>> Los Leones 1200
>>>>>>>>> Providencia
>>>>>>>>> Santiago, Chile
>>>>>>>>> Phone: (+56-2) 22001288
>>>>>>>>> mailto:luis.rojas at sixbell.com
>>>>>>>>> http://www.sixbell.com
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> _______________________________________________
>>>>>>>>> Kamailio (SER) - Users Mailing List
>>>>>>>>> sr-users at lists.kamailio.org
>>>>>>>>> https://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users
>>>>>>>> --
>>>>>>>> Daniel-Constantin Mierla -- www.asipto.com
>>>>>>>> www.twitter.com/miconda -- www.linkedin.com/in/miconda
>>>>>>>
>>>>>>> --
>>>>>>> Luis Rojas
>>>>>>> Software Architect
>>>>>>> Sixbell
>>>>>>> Los Leones 1200
>>>>>>> Providencia
>>>>>>> Santiago, Chile
>>>>>>> Phone: (+56-2) 22001288
>>>>>>> mailto:luis.rojas at sixbell.com
>>>>>>> http://www.sixbell.com
>>>>>> --
>>>>>> Daniel-Constantin Mierla -- www.asipto.com
>>>>>> www.twitter.com/miconda -- www.linkedin.com/in/miconda
>>>>>
>>>>> --
>>>>> Luis Rojas
>>>>> Software Architect
>>>>> Sixbell
>>>>> Los Leones 1200
>>>>> Providencia
>>>>> Santiago, Chile
>>>>> Phone: (+56-2) 22001288
>>>>> mailto:luis.rojas at sixbell.com
>>>>> http://www.sixbell.com
>>>> --
>>>> Daniel-Constantin Mierla -- www.asipto.com
>>>> www.twitter.com/miconda -- www.linkedin.com/in/miconda
>>>
>>> --
>>> Luis Rojas
>>> Software Architect
>>> Sixbell
>>> Los Leones 1200
>>> Providencia
>>> Santiago, Chile
>>> Phone: (+56-2) 22001288
>>> mailto:luis.rojas at sixbell.com
>>> http://www.sixbell.com
>> --
>> Daniel-Constantin Mierla -- www.asipto.com
>> www.twitter.com/miconda -- www.linkedin.com/in/miconda
>
> --
> Luis Rojas
> Software Architect
> Sixbell
> Los Leones 1200
> Providencia
> Santiago, Chile
> Phone: (+56-2) 22001288
> mailto:luis.rojas at sixbell.com
> http://www.sixbell.com
> _______________________________________________
> Kamailio (SER) - Users Mailing List
> sr-users at lists.kamailio.org
> https://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users
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