[JDEV] Jabbers disappointment !!

[David Waite]

1. In practice, I've seen much lower memory usage. There are no longer
individual user threads but a static pool of threads in 1.2, this reduces the
per-user memory requirements from ~50k/User to something closer to 5k.

Also there are already individuals working on a pthreads port.

2. select() is limited to 1024 file descriptors on every platform I have seen -
just a fact of life with the way select() works. poll() isn't. This is what
jpolld is for. Note that even root on a linux box will be limited to a
(separate) max of 1024 open file descriptors until the limit is changed (with
the ulimit command)

-David Waite

Vijay Kumar wrote:

>  Hi!!  all
>         for last couple of days I was figuring out whats the upper limit of
> no of users jabber can support
> concurrently. what I can figure out is that jabber as a server can be used
> for small no of clients only .
>
> 1) memorey diappointment .
>     With pth, the individual user threads get 32k (correct me pease if I'm
> wrong) so 10,000 users would use up 320MB.
>     if we are having 1GB of RAM then atmost 30,000 user will be supported
> concurrently.
>     beside this pth is not kernel based so if dual propressor is used its of
> no use to jabber .
> 2)TCP connection :
> It should also be noted that by default, Linux will only accept 1024 TCP
> connections. Adding more simo connections requires a kernel patch to
> increase
> this limit. to what limit we can increase this ?? If I am not wrong then one
> connection will be dedicated to one user
> ,I meant each tread will be revoling around one connection . will it means
> maximum atmost 1024 will be online at a time .
> but its also known that :
> sockets absolute limitation is 64k since the port value is 2 bytes wide. So,
> with
> TCP/IP you cannot have more then 64k connections (this is a theoretical
> maximum, in reality more limitations apply) even if you have a
> server-machine that can handle the load
>
> 3)Distributed approach.
>      well 1st & 2nd point is true for any server which is based on Pth & TCP
>  .
>      but agin Lot is taked about distributed approch in jabber .but how to
> implement it practically is no where written neither
> in jabber docs nor in mailling archives . suppose if I am running 3 jabber
> servers in 3 different machines then how to
> syncronize them or co-relate them .
> or how to install one master jabber server
>   with 3-4 salve servers distributed .
>
> mine whole aim is to use jabber at very high end of user numbers.
>
> thanks in advance !!
>
> vijay
>
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