It is safer to use _beginthreadex than _beginthread. If the thread generated by _beginthread exits quickly, 
the handle returned to the caller of _beginthread might be invalid or, worse, point to another thread. However, 
the handle returned by _beginthreadex has to be closed by the caller of _beginthreadex, 
so it is guaranteed to be a valid handle if _beginthreadex did not return an error.