Intelligent Advisor

Hi ,
I implement a callable task that set some data to the engine and execute "session.think()"
created a pool of 7 threads - each thread need to do some calculation for a single day of a week (Sunday,Monday..,Saturday)

I would like to know if I need to create a new session for each task I submit(for each new thread that start)
or should I use single session that is shard by the callable tasks I have ?

is session is thread safe ? regarding the fact the every think() execution changes session state.
what is the good practice when working with OPA + threads ?

Another thing I encounter that if the "session.think()" is not declared in synchronized method I am getting this Error
Exception: IllegalStateException - Think cycle has not stabilised after 20 iterations. This is probably due to a fault in the inferencing listener. and I am not implemented any listener

I am using version 10.4

Thanks in advance
Nir