[omniORB] Scalability problems; 300+ clients

[Peter Klotz]

Slawomir Lisznianski wrote:
> Hello,
> 
> I'm curious whether anyone has seen this before. We have a farm of about
> 300 computers on which we run our CORBA (omniORB) infrastructure. When
> the load riches about 330 clients (connected to a single server), new
> clients tend to see COMM_FAILURE exception, or (rarly) TRANSIENT.
> Sometimes existing clients start getting exceptions as well, in that
> load. We're not running out of file descriptors in the server process.
> We played with ORB parameters on the server side but couldn't see any
> improvement. We use Linux Red-Hat AS3, FC4 and omniORB 4.0.7

We encountered similar problems under Red Hat Enterprise Linux 3 and I 
tracked it down to the stack size of the server threads. Each thread 
seems to be created with a stack size of 10MB. The total memory one 
process is allowed to use is 3GB (at least on i386). This limits the 
number of threads to approximately 300.

We disabled threadPerConnectionPolicy (which is 1 by default) and use a 
thread pool with much less than 300 threads instead.

Best regards, Peter.