ThreadPool handles tasks concurrently through Threads so users need not worry about the creation/deletion of Threads, it uses reuses threads whenever possible and it can handle any tasks. 

However, it should be possible for users to at least name/rename according to the tasks that the user submits into the ThreadPool.

Advantages:
* Good for Debugging (so user can know which thread has caused the issue)
* threadName attribute in logging's LogRecord can now use custom Name provided to the Task.

Until now thread_name_prefix parameter allows us to name the threads but those are not particular to the Task.

Price

previously one could write .submit(function_name, *args, **kwargs)
but now one should write 
.submit(function_name, name_of_thread, *args, **kwargs)
name_of_thread can be None