Python/线程/屏障 : Is this a correct usage of Barrier?

Question

可能是我没有理解线程的屏障概念。但是我写了一段代码，我想了解它是否正确使用了 barrier。

代码如下:

#!/usr/bin/env python3
# -*- coding: utf-8 -*-

import time
import random
import threading


def f(b):
    time.sleep(random.randint(2, 10))
    print("{} passed the barrier at: {}".format(threading.current_thread().getName(), time.ctime()))
    b.wait()


barrier = threading.Barrier(3)
for i in range(3):
    t = threading.Thread(target=f, args=(barrier,))
    t.start()

Answer 1

屏障设置了线程的计数，这些线程将一起等待直到达到该计数。测试中有一个小的变化

import time
import random
import threading

def f(b):
    time.sleep(random.randint(2, 10))
    print("{} woke at: {}".format(threading.current_thread().getName(), time.ctime()))
    b.wait()
    print("{} passed the barrier at: {}".format(threading.current_thread().getName(), time.ctime()))

barrier = threading.Barrier(3)
for i in range(3):
    t = threading.Thread(target=f, args=(barrier,))
    t.start()

您可以看到所有线程在不同的时间从 sleep 中唤醒，但同时从 wait 返回。

$ python3 o.py
Thread-2 woke at: Sun May 20 11:59:16 2018
Thread-3 woke at: Sun May 20 11:59:21 2018
Thread-1 woke at: Sun May 20 11:59:22 2018
Thread-1 passed the barrier at: Sun May 20 11:59:22 2018
Thread-2 passed the barrier at: Sun May 20 11:59:22 2018
Thread-3 passed the barrier at: Sun May 20 11:59:22 2018