5.1.19 Event事件--线程之间的交互

event=Event()

event.isSet()  # 返回event的状态值  True False

event.wait()  #等待其他线程发出event.set()后才继续往下执行   event.isSet() == False 将阻塞线程  

event.wait(3) #如果超过3秒，即使没有收到event.set()也会继续往下执行

event.set()  # 设置event的状态值为True, 所有阻塞池的线程激活进入就绪状态，等待操作系统调度

event.clear() # 恢复event的状态值为False

 

模拟多个客户端连接服务器端，检测服务器是否正常运行？ 服务器要先起来，客户端才可以连接。

from threading import Event
from threading import Thread
from threading import current_thread
import time

event = Event()

def conn():

    print('is connecting ......')
    n = 0
    while not event.is_set():
        if n == 5:
            print('%s try too many count!' % current_thread().getName())
            return
        event.wait(1)
        print('%s try %s' % (current_thread().getName(), n))
        n += 1
    print('connected')


def check():
    print('server is starting ......')
    time.sleep(5)
    print('server is started!')
    event.set()


if __name__ == '__main__':
    conn1 = Thread(target=conn)
    conn2 = Thread(target=conn)
    conn3 = Thread(target=conn)

    check1 = Thread(target=check)

    conn1.start()
    conn2.start()
    conn3.start()
    check1.start()

运行结果： 可设置服务器启动时间，和连接时间和重试试数，观察不同的结果

is connecting ......
is connecting ......
is connecting ......
server is starting ......
Thread-1 try 0
Thread-3 try 0
Thread-2 try 0
Thread-1 try 1
Thread-3 try 1
Thread-2 try 1
Thread-3 try 2
Thread-2 try 2
Thread-1 try 2
Thread-3 try 3
Thread-1 try 3
Thread-2 try 3
server is started!
Thread-2 try 4
connected
Thread-1 try 4
connected
Thread-3 try 4
connected