SAP Listener threads


I am having problem on parallel execution of SAP listener threads. Currently I am using B2B SAP Adapter 4.0 and number of threads on SAP listener is set to 7.

Assume that one thread is busy by executing a B2B service with loadDocument or GD invoke and the remaining 6 threads are free. Now if there is new IDOCs released from SAP, those are not coming to B2B server immediately. B2B server is receving those IDocs after loadDocument/GD invoke service got executed.

I checked the memory usage while the server was busy with loadDocument. It was using only 30% of memory. Can anyone clarify why the free threads are not utilized properly.

Thanks in advance.

Abdul Salam