Thanks Alex for your elaboration; you are right. 
This is the reason that the current ims_ipsec module will create a bunch of listeners at startup that looks not efficient.


Regards,
Hossein


On Tuesday, October 25, 2022 at 01:28:38 PM PDT, Alex Balashov <abalashov@evaristesys.com> wrote:


Well, no, it just stems from some knowledge of Kamailio’s multiprocess architecture.

Kamailio uses a static pool of preforked SIP worker processes, and this is initialised once upon startup. These child processes are spawned for every listener, and communicate and share data using SysV IPC and shared memory. The shared memory pool is likewise initialised upon startup, as is the small fixed-size area of private memory associated with each other worker process (“package memory”).

While perhaps not strictly impossible to alter, this setup isn’t particularly amenable to the dynamic creation and destruction of listeners, or the additional child processes they beget. The child processes need to be forked on startup, before their heap is laden with runtime baggage. All this is relatively expensive to initialise.

— Alex

> On Oct 25, 2022, at 4:14 PM, H Yavari <hyavari@rocketmail.com> wrote:
>
> Thanks Alex.
> Is there any document or material that tells more about those reasons?
>
>
> Regards,
> Hossein
>
>
> On Tuesday, October 25, 2022 at 01:00:18 PM PDT, Alex Balashov <abalashov@evaristesys.com> wrote:
>
>
> Hi,
>
> Unfortunately, for a variety of architectural reasons, this is not practical.
>
> — Alex
>
> > On Oct 25, 2022, at 12:43 PM, H Yavari <hyavari@rocketmail.com> wrote:
> >
> > Hi Kamailio community,
> >
> >
> > I am running an IPsec server beside Kamailio, so I am interested to know if there is any method to create a SIP listener on a specific port on the fly. I mean, when I create the IPsec SAs through the IPsec server, I ask Kamailio to create a listener/handler for that port too.
> > This case might be very rare, but it is always good to hear community ideas.
> >
> > Thank you.
> >
> > Regards,
> > Hossein
>
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