如何创建一个事件循环，直到永远运行某些协同程序？

问题描述

为了从上下文切换prevent，我想创建一个大循环，以同时满足网络的连接和一些套路。

In order to prevent from context switching, I want to create a big loop to serve both the network connections and some routines.

下面是用于正常功能的实现：

Here's the implementation for normal functions:

import asyncio
import time


def hello_world(loop):
    print('Hello World')
    loop.call_later(1, hello_world, loop)

def good_evening(loop):
    print('Good Evening')
    loop.call_later(1, good_evening, loop)

print('step: asyncio.get_event_loop()')
loop = asyncio.get_event_loop()

print('step: loop.call_soon(hello_world, loop)')
loop.call_soon(hello_world, loop)
print('step: loop.call_soon(good_evening, loop)')
loop.call_soon(good_evening, loop)

try:
    # Blocking call interrupted by loop.stop()
    print('step: loop.run_forever()')
    loop.run_forever()
except KeyboardInterrupt:
    pass
finally:
    print('step: loop.close()')
    loop.close()

下面是协同程序的实现：

Here's the implementation for coroutines:

import asyncio


@asyncio.coroutine
def hello_world():
    while True:
        yield from asyncio.sleep(1)
        print('Hello World')

@asyncio.coroutine
def good_evening():
    while True:
        yield from asyncio.sleep(1)
        print('Good Evening')

print('step: asyncio.get_event_loop()')
loop = asyncio.get_event_loop()
try:
    print('step: loop.run_until_complete()')
    loop.run_until_complete(asyncio.wait([
        hello_world(),
        good_evening()
    ]))
except KeyboardInterrupt:
    pass
finally:
    print('step: loop.close()')
    loop.close()

和混合之一：

import asyncio
import time


def hello_world(loop):
    print('Hello World')
    loop.call_later(1, hello_world, loop)

def good_evening(loop):
    print('Good Evening')
    loop.call_later(1, good_evening, loop)

@asyncio.coroutine
def hello_world_coroutine():
    while True:
        yield from asyncio.sleep(1)
        print('Hello World Coroutine')

@asyncio.coroutine
def good_evening_coroutine():
    while True:
        yield from asyncio.sleep(1)
        print('Good Evening Coroutine')

print('step: asyncio.get_event_loop()')
loop = asyncio.get_event_loop()

print('step: loop.call_soon(hello_world, loop)')
loop.call_soon(hello_world, loop)
print('step: loop.call_soon(good_evening, loop)')
loop.call_soon(good_evening, loop)
print('step: asyncio.async(hello_world_coroutine)')
asyncio.async(hello_world_coroutine())
print('step: asyncio.async(good_evening_coroutine)')
asyncio.async(good_evening_coroutine())

try:
    loop.run_forever()
except KeyboardInterrupt:
    pass
finally:
    print('step: loop.close()')
    loop.close()

正如你所见，每个协程函数包围while循环。我怎样才能使它像正常的吗？即当它完成后，称自己是给定的延迟时间之后，但不只是把一个循环那里。

As you see, each coroutine function has a while loop surrounded. How can I make it like the normal one? I.e. when it is done, call itself after the given delay time, but not just put a loop there.

推荐答案

如果你真的想消除来自协同程序的while循环（我不知道为什么你觉得这是必要的，它是做什么的最自然的方式你想这样做），你可以使用（或 asyncio.ensure_future 关于Python 3.4.4+），以安排向协程上重新运行下一个事件循环迭代：

If you really want to eliminate the while-loop from the coroutines (I'm not sure why you feel that's necessary; it's the most natural way to do what you're trying to do), you can use asyncio.async (or asyncio.ensure_future on Python 3.4.4+) to schedule the coroutine to run again on the next event loop iteration:

import asyncio

@asyncio.coroutine
def hello_world():
    yield from asyncio.sleep(1)
    print('Hello World')
    asyncio.async(hello_world())

@asyncio.coroutine
def good_evening():
    yield from asyncio.sleep(1)
    print('Good Evening')
    asyncio.async(good_evening())

print('step: asyncio.get_event_loop()')
loop = asyncio.get_event_loop()
try:
    print('step: loop.run_until_complete()')
    asyncio.async(hello_world())
    asyncio.async(good_evening())
    loop.run_forever()
except KeyboardInterrupt:
    pass
finally:
    print('step: loop.close()')
    loop.close()

请注意，你必须切换回 loop.run_forever（）如果你这样做，因为参考hello world / good_evening 现在打印后立即退出。

Note that you have to switch back to using loop.run_forever() if you do this, since hello_world/good_evening will exit immediately after printing now.

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