The definition of thread pool task. This task is called by a thread in the
pool to perform a specific task and than exit. It must never loop indefinitly
but perform on task than exit.
author: Brett Chaldecott
This method is called by a thread in the thread pool. It must perform a
single task and then exit. It must not run indefinitly like a thread.
Parameters: pool - The reference to the pool object. exception: Exception -