A thread pool (JavaGroups.ThreadPool) maintains a number of reusable threads. A new thread can be created using method GetThread. It will be created, added to the pool and returned as result of this call. A thread pool can be given a limit on the number of threads to create. When GetThread is called, the existing threads are checked for completion. If an existing thread is found that has completed its task, then it will be returned. Otherwise, if the pool limit has not yet been reached, a new reusable thread will be created, added to the pool and returned. If the limit has been reached, null will be returned.