src is the source file of my cpp threadpool
obj CThreadManager is the interface with user
obj CJob is the entrance of thread by implementing the interface run() in CJob, and invoke in CThreadManager. CThreadManager would invoke your thread in threadpool to the thread with least jobs or jobs queue below busyThreshold.
obj CThread is the pakage of thread
obj CWokerThread inherit CThread, adding features we wanted, becoming the worker of my thread pool
obj CThreadPool assigning jobs and scheduling the workers