[Opensim-dev] UDP async performance

[Michael Emory Cerquoni]

I am not sure the HTTP server handles UDP, I want to say it does not handle
that.

On Mon, Mar 16, 2015 at 11:50 AM, Myron Curtis <
myronjc at virtualworldsgrid.com> wrote:

> Could this be a case of the Http server in opensim just being too slow to
> respond to this traffic quickly enough?
>
> -----Original Message-----
> From: opensim-dev-bounces at opensimulator.org
> [mailto:opensim-dev-bounces at opensimulator.org] On Behalf Of Michael
> Heilmann
> Sent: Monday, March 16, 2015 6:55 AM
> To: opensim-dev at opensimulator.org
> Subject: [Opensim-dev] UDP async performance
>
> Opensim Devs
>
> I have been working on an external process that I hope to link to an
> opensim
> plugin I am authoring.  As a sanity check, I ran a simple socket test
> against the components to test for obvious problems before I get to the
> heavy lifting.  This test was not meant to reveal anything, just to confirm
> that the pieces are in place. However, I am not seeing the expected
> behavior.
>
> My simple sanity test:  send 1000000 small udp packets at a server, and
> have
> it count packets received.  This is trivial, and the sending client is
> python, so all packets should be received.
>
> While running this on localhost: (~160K packets per second)
> > Go, c++, nodejs, c# synchronous : negligible to no packet loss, as
> > expected
> >
> > c# async: 80% packet loss
>
>
> I have reviewed msdn documentation, and went through the opensim code (as
> it
> uses c# async) to clean up and run my tests.  That 80% packet loss is after
> forcing my threadpool and iocp thread counts up, and giving c# async extra
> time before and after the test to warm up threadpools and process any
> queues.
>
> I have read that in some cases C# and .Net has a packet loss bug for udp on
> localhost.
>
> I re-ran this test between two linux servers with a 10gbe LAN interconnect
> to remove any .net localhost packet loss issues, with the following
> results:
> (~115K packets per second)
> > c# synchronous: ~998K messages received (average over 3 runs) Go :
> > ~980K messages received (average over 3 runs)
> >
> > c# async: ~40K messages received (average over 3 runs)
> disclosure: Go on my workstation is version 1.4.2, but on the servers is
> version 1.2.1.  Mono versions are identical
>
> Now, the 3 runs were very nearly identical, with differences in the
> thousands of packets.  As before, C# async was given extra treatment to
> help
> it along.
>
> I am on linux 64 bit, so I had a coworker write his own version of this
> test
> using Visual Studio 2013 on Windows (no code sharing), and he saw the same
> behavior:  c# async suffering massive packet loss while c# sync is keeping
> up easily.
>
> Is there anything in the opensim client stack that I am missing, that
> allows
> for higher async performance?  Or am I on a witch hunt, and this
> performance
> is within Opensim bounds?  I have been increasing the threadpool and iocp
> threads as Opensim does.  I have pasted important pieces of the code below,
> as the entirety could be too long for this
> messageboard: (The UDPPacketBuffer class is coped from opensim code)
>
> >         private void AsyncBeginReceive()
> >         {
> >             UDPPacketBuffer buf = new UDPPacketBuffer();
> >             this.u.BeginReceiveFrom(
> >                 buf.Data,
> >                 0,
> >                 UDPPacketBuffer.BUFFER_SIZE,
> >                 SocketFlags.None,
> >                 ref buf.RemoteEndPoint,
> >                 AsyncEndReceive,
> >                 buf);
> >         }
> >
> >         private void AsyncEndReceive(IAsyncResult iar)
> >         {
> >             //schedule another receive
> >             AsyncBeginReceive();
> >
> >             lock(this)
> >             {
> >                 this.i++;
> >              }
> >         }
> >
> >         public static void Main (string[] args)
> >         {
> >             int iocpThreads;
> >             int workerThreads;
> >             ThreadPool.GetMinThreads(out workerThreads, out iocpThreads);
> >             workerThreads = 32;
> >             iocpThreads = 32;
> >             Console.WriteLine(workerThreads);
> >             ThreadPool.SetMinThreads(workerThreads,iocpThreads);
> >             MainClass mc = new MainClass();
> >             mc.AsyncBeginReceive();
> >             //manually trigger packet report after test run completion
> >             Console.ReadLine();
> >             Console.WriteLine(mc.i);
> >         }
>
> I have run this test repeatedly, varying workerThread and iocpThreads from
> 8, to 16, 32, 64 ... 512, without any change in packets received.
> If anyone had any insight into why this is suffering from so much packet
> loss, I would appreciate it.  Thanks.
>
> --
> Michael Heilmann
> Research Associate
> Institute for Simulation and Training
> University of Central Florida
>
> _______________________________________________
> Opensim-dev mailing list
> Opensim-dev at opensimulator.org
> http://opensimulator.org/cgi-bin/mailman/listinfo/opensim-dev
>
> _______________________________________________
> Opensim-dev mailing list
> Opensim-dev at opensimulator.org
> http://opensimulator.org/cgi-bin/mailman/listinfo/opensim-dev
>



-- 
Michael Emory Cerquoni
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://opensimulator.org/pipermail/opensim-dev/attachments/20150316/c773a94c/attachment.html>