I recently encountered a problem that is giving me a headache and I need help ...

The System consists of two subsystems, called A and B, each running on a standalone Tomcat instance and currently running on the same machine. A invokes B's service via Spring httpInvoker (i.e. over HTTP). B system also invokes the other system's services via HTTP.

Symptoms:

1. the system starts to run and appears to work normally for around 10-15 days;

2. the system will run for a period of time after an exception:

   org.springframework.remoting.RemoteAccessException: Could not access HTTP invoker remote service at [http://xxx.xxx.xxx.xxx/remoting/call]; 
   

   The nested exception is

   java. net.SocketException: **Permission denied: connect**
   

3. when the exception occurs, the system continues. This happens always, not only occasionally. (It looks like some resources are exhausted, but CPU rate < 5%, memory < 15%, network < 5%).

4. when the system call between A and B fails, the B system call over HTTP to an external service also failed, with the same exception.

5. Restarting both Tomcat services makes the whole system work properly.

So repeatedly following steps 1 - 5, I have not found the root reason.

Environment:

• windows 2008 R2
• tomcat7.0.42 x86_64
• oralce-jdk-1.7.0_40

Any ideas?