[omniORB] Extreme slowdown of omniORB with messages >=1024 characters

[Duncan Grisby]

On Tuesday 26 March, Robert Nebauer wrote:

> I played a little bit with the echo examples in the omniORB4-20020325 
> snapshot. While sending messages greater than or equal 1024 chars (i.e. 
> strings with a length of 1023 characters) omniORB slows downs extremely. 
> 
> The performance drops from 0,3 ms/call to 80 ms/call (Athlon 700mhz) and the 
> cpu-usage goes down to 1-2%. It doesn't matter if thread tracing is enabled 
> or not.

Are the client and server on the same machine?  There is something
very dodgy about the Linux TCP loopback that causes wild fluctuations
in transmission times. If you increase the message size even more,
you'll find that the time decreases again, then cycles.

The work-around for omniORB 4 is to enable the Unix domain socket
transport, since that works fine. Use command line arguments of
-ORBendPoint giop:unix: -ORBendPoint giop:tcp:: (or the config file
equivalents) to enable the Unix transport.

Cheers,

Duncan.

-- 
 -- Duncan Grisby  \  Research Engineer  --
  -- AT&T Laboratories Cambridge          --
   -- http://www.uk.research.att.com/~dpg1 --