python协程实时输出_在python里协程使用同步锁Lock的实例

尽管asyncio库是使用单线程来实现协程的，但是它还是并发的，乱序执行的。可以说是单线程的调度系统，并且由于执行时有延时或者I/O中断等因素，每个协程如果同步时，还是得使用一些同步对象来实现。

比如asyncio就定义了一个锁对象Lock，它一次只允许一个协程来访问共享的资源，如果多协程想访问就会阻塞起来，也就是说如果一个协程没有释放这个锁，别的协程是没有办法访问共享的资源。

例子：

import asyncio

import functools

def unlock(lock):

print('callback releasing lock')

lock.release()

async def coro1(lock):

print('coro1 waiting for the lock')

with await lock:

print('coro1 acquired lock')

print('coro1 released lock')

async def coro2(lock):

print('coro2 waiting for the lock')

await lock

try:

print('coro2 acquired lock')

finally:

print('coro2 released lock')

lock.release()

async def main(loop):

# Create and acquire a shared lock.

lock = asyncio.Lock()

print('acquiring the lock before starting coroutines')

await lock.acquire()

print('lock acquired: {}'.format(lock.locked()))

# Schedule a callback to unlock the lock.

loop.call_later(0.1, functools.partial(unlock, lock))

# Run the coroutines that want to use the lock.

print('waiting for coroutines')

await asyncio.wait([coro1(lock), coro2(lock)]),

event_loop = asyncio.get_event_loop()

try:

event_loop.run_until_complete(main(event_loop))

finally:

event_loop.close()

输出结果如下：

acquiring the lock before starting coroutines

lock acquired: True

waiting for coroutines

coro1 waiting for the lock

coro2 waiting for the lock

callback releasing lock

coro1 acquired lock

coro1 released lock

coro2 acquired lock

coro2 released lock

以上这篇在python里协程使用同步锁Lock的实例就是小编分享给大家的全部内容了，希望能给大家一个参考，也希望大家多多支持我们。

本文标题: 在python里协程使用同步锁Lock的实例

本文地址: http://www.cppcns.com/jiaoben/python/252780.html