使用python进行多线程

Question

Trying to understand the following results when using multithreading with python. The following code prints A and B to the console in random sequence, which is what I would like to achieve. But the second piece of code only prints "A" to the console, and never proceeds past t1.start(). Why is this? What do I need to do the the second section of code to make it behave like the first?

Thanks in advance, this is my first post.

This is the behavior I want :

from threading import Thread
def runA():
    while True:
        print ('A\n')

def runB():
    while True:
        print ('B\n')

if __name__ == "__main__":
     t1 = Thread(target = runA())
     t2 = Thread(target = runB())
     t1.setDaemon(True)
     t2.setDaemon(True)
     t1.start()
     t2.start()
     while True:
         pass

I want the behavior produced from the above code but using classes like in the example below. The code below never executes t2.start(). Why is this?

from threading import Thread
class test():
     def runA(self):
         while True:
             print ('A\n')

     def runB(self):
         while True:
             print ('B\n')

if __name__ == "__main__":
     testingNow=test()
     t1 = Thread(target = testingNow.runA())
     t2 = Thread(target = testingNow.runB())
     t1.setDaemon(True)
     t2.setDaemon(True)
     t1.start()
     t2.start()
     while True:
         pass

Answer 1

摆脱()在testingNow.runA()和testingNow.runB()