This module constructs higher-level threading interfaces on top of the lower level python库之_threadmodule
官方参考文档：https://docs.python.org/2/library/threading.html
threading库对象和方法
（1）threading.active_count()
（2）theading.Condition()
A factory function that returns a new condition variable object,See Condition Objects.
（3）threading.current_thread()
（4）threading.enumerate()
Return a list of all Thread objects currently alive. The list includes daemonic threads, dummy thread objects created by current_thread(), and the main thread. It excludes terminated threads and threads that have not yet been started.
（5）threading.event()
A factory function that returns a new event object. An event manages a flag that can be set to true with the set() method and reset to false with the clear() method. The wait() method blocks until the flag is true.See Event Objects.
（6）class threading.local
A class that represents thread-local data. Thread-local data are data whose values are thread specific. To manage thread-local data, just create an instance of local (or a subclass) and store attributes on it:
mydata = threading.local()
mydata.x = 1
The instance’s values will be different for separate threads.
For more details and extensive examples, see the documentation string of the _threading_local module.
（7）theading.Lock()
A factory function that returns a new primitive lock object. Once a thread has acquired it, subsequent attempts to acquire it block, until it is released; any thread may release it.See Lock Objects.
（8）threading.RLock()
A factory function that returns a new reentrant lock object. A reentrant lock must be released by the thread that acquired it. Once a thread has acquired a reentrant lock, the same thread may acquire it again without blocking; the thread must release it once for each time it has acquired it.See RLock Objects.
（9）threading.Semaphore([value])
A factory function that returns a new semaphore object. A semaphore manages a counter representing the number of release() calls minus the number of acquire() calls, plus an initial value. The acquire() method blocks if necessary until it can return without making the counter negative. If not given, value defaults to 1.See Semaphore Objects.
（10）threading.BoundedSemaphore([value])
A factory function that returns a new bounded semaphore object. A bounded semaphore checks to make sure its current value doesn’t exceed its initial value. If it does, ValueError is raised. In most situations semaphores are used to guard resources with limited capacity. If the semaphore is released too many times it’s a sign of a bug. If not given, value defaults to 1.
（11）class threading.Thread
A class that represents a thread of control. This class can be safely subclassed in a limited fashion.See Thread Objects.
（12）class threading.Timer
A thread that executes a function after a specified interval has passed.See Timer Objects.
（13）threading.settrace(func)
（14）threading.setprofile(func)
（15）threading.stack_size([size])