python 引用传递，简单例子

from threading import Thread

def test1(a):
    while 1:
        print a

def test2(a):
    a["a"] = 2

if __name__ == "__main__":
    a = {"a": 1}
    t1 = Thread(target=test1, args=(a, ))
    t1.start()
    t2 = Thread(target=test2, args=(a, ))
    t2.start()