Re: [Cppcms-users] CppCMS as Comet Server

[william l. <we...@gm...>]

wow.  you do benchmark on a laptop? :)
Thanks for the detailed reply, and here is another reference I read about:

http://webcache.googleusercontent.com/search?q=cache:2iV4meP2vIMJ:blog.urbanairship.com/blog/2010/09/29/linux-kernel-tuning-for-c500k/+&cd=1&hl=en&ct=clnk&gl=us

It mentioned C65K Myth.

Actually I expect more connection than that.
The more connection I can have per server, the less cost it will be.

I will try and see how it comes :)

thanks,
William L.


On Fri, Dec 28, 2012 at 5:54 AM, Artyom Beilis <art...@ya...> wrote:

> Actually it is very good questions...
>
> What is the performance, I did some benchmarks but had not full time to
> publish them...
>
> In general I could easily handle 20,000 connections and send updates (SSE)
> using vanila CppCMS code
> and broadcast around 50,000 messages per second (i.e. each  connection 2.5
> msg/s)
>
> Having 200-500 connections I could send about 100,000 messages per second.
>
> This was done using the most stright forward implementation using
> event-stream API I had written about it in the blog.
>
> Now to handle more than 20,000 K connections you need more network
> interfaces (ips) (as TCP/IP can't handle theoretically more than 65K
> connections in single IP address) which i couldn't check.
>
> Now when you deal with Comet everything is handled in currently single
> event loop one thread. So to scale up today the
> easiest is to use prefork mode (more then 1 worker process see
> service.worker_processes)
> thus you would have several event loops and you can scale them
> over multiple CPUs. It would be slower for low loads for much better for
> high onces.
>
> For example using 20,000 connections I could send 120,000 msgs/s i.e.
> 6/msg per connection which was quite liner scale up over CPUs on this
> particular machine.
>
> However using prefork with comet would require IPC so you would need to
> notify somehow each process on event, but it is must to
> have to scale over multiple CPUs and especially over multiple hosts.
>
> Also in general such benchmarking requires:
>
> - Tuning TCP/IP stack, make big backlog - very important and setting
> appropriate backlog option in application, also make sure you have wide
> port range, etc.
> - Ensure you have high ulimits to handle many descriptors
>
> Also I should note that I expect to do some optimization in CppCMS 1.2 to
> increase these numbers after some extensive profiling I did
> (there is lots of space for improvement)
>
> All these numbers I got running on Laptop with i5 2.4 GHz 2 cores 4
> threads 4GB RAM (of wich I used quite a few)
>
>
> Regards
>
>
> Artyom Beilis
> --------------
> CppCMS - C++ Web Framework:   http://cppcms.com/
> CppDB - C++ SQL Connectivity: http://cppcms.com/sql/cppdb/
>
>   ------------------------------
> *From:* william lee <we...@gm...>
> *To:* cpp...@li...
> *Sent:* Thursday, December 27, 2012 4:22 PM
> *Subject:* [Cppcms-users] CppCMS as Comet Server
>
> Hi,
> I'm thinking of using CppCMS to implement a Comet Server for Pushing short
> messages to connected users via Http.
>
> Do you have any ideas from performance perspective, how much connections
> CppCMS application can handle at the same time per server?
>
> The server spec is like 10G RAM, 8Core CPU etc, and http traffic is not
> heavy, I'm thinking about keep a connection for 10 mins then release it and
> let it reconnect back.
>
> If anyone have some benchmark result, that will be great!
>
> Thanks and appreciated
>
> Happy New Year
> William L.
>
>
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