Application gets stuck when using thread pool connection mode with bidirectional GIOP

Hi guys,

Can anyone help me out please with the following problem. 

We are using omniORB 4.2.5 on CentOS 7 Linux and we have recently tried to use bidir GIOP for some of our
services. Everything works fine for the servers that use thread-per-connection mode, but the applications which are
using thread-pool mode get stuck when the number of external connections reaches the number of threads in the 
pool. There is a clear correlations between these numbers, which we verified by varying the number of threads in the 
pool. The symptom is that when the number of external connections reaches the number of threads in the pool the 
server starts accumulating connections in the CLOSE_WAIT state and an attempt to communicate with it resulted 
in a timeout. After a while (a few tens of seconds) all connections in the CLOSE_WAIT state disappeared and the 
server becomes responsive again. 

Is this a known behaviour or otherwise where should I look at to investigate and possibly fix this problem?

Cheers,
Serguei