Python Rlock implement thread synchronization

import threading

mylock = threading.RLock();
num = 0


class myThread(threading.Thread):
    def __init__(self, name):
        threading.Thread.__init__(self,name=name)

    def run(self):
        global num
        while True:
            mylock.acquire()
            print('%s locked, Number: %d' % (threading.current_thread().name, num))
            if num >= 4:
                mylock.release()
                print('%s released, Number: %d' % (threading.current_thread().name, num))
                break
            num += 1
            print('%s released, Number: %d' % (threading.current_thread().name, num))
            mylock.release()


if __name__ == '__main__':
    thread1 = myThread('Thread_1')
    thread2 = myThread('Thread_2')
    thread1.start()
    thread2.start()

If multiple threads of a common data modification, it might Chu is now unpredictable results, in order to properly insured
, it is necessary to synchronize multiple threads. Thread object using the Lock and RLock can achieve a simple thread synchronization. .
Both objects have methods relate acquire method and, for those data operation allows only one thread can
between its operation to acquire and release into the method.