线程打印不正确

Question

我似乎无法让多线程工作。我简化了我的问题，但我仍然无法正确打印线程(所以我猜它们执行不正确(。

import time, threading
s_print_lock = threading.Lock()
def s_print(*a, **b):
    with s_print_lock:
        print(*a, **b)
# Thread safe print function
def a():
    while True:
        s_print(''a' is running')
        time.sleep(5)
# Thread 1
def b():
    while True:
        s_print(''b' is running')
        time.sleep(5)
# Thread 2
if __name__ == "__main__":
    t1 = threading.Thread(target=a())
    t2 = threading.Thread(target=b())
    t1.start()
    t2.start()

输出为：

'a' is running
'a' is running
'a' is running
'a' is running
...

Answer 1

目标必须是可调用的。您正在执行a()，因此它进入while True循环并且永远不会结束，因此永远不会启动线程。试试这个：

if __name__ == "__main__":
    t1 = threading.Thread(target=a)
    t2 = threading.Thread(target=b)
    t1.start()
    t2.start()