Python进阶:聊协程

import time

def crawl_page(url):
    print('crawling {}'.format(url))
    sleep_time = int(url.split('_')[-1])
    time.sleep(sleep_time)
    print('OK {}'.format(url))

def main(urls):
    for url in urls:
        crawl_page(url)

%time main(['url_1', 'url_2', 'url_3', 'url_4'])

######### 输出 ##########

crawling url_1
OK url_1
crawling url_2
OK url_2
crawling url_3
OK url_3
crawling url_4
OK url_4
Wall time: 10 s

import asyncio
import nest_asyncio
nest_asyncio.apply()

async def crawl_page(url):
    print('crawling {}'.format(url))
    sleep_time = int(url.split('_')[-1])
    await asyncio.sleep(sleep_time)
    print('OK {}'.format(url))

async def main(urls):
    for url in urls:
        await crawl_page(url)

%time asyncio.run(main(['url_1', 'url_2', 'url_3', 'url_4']))

########## 输出 ##########

crawling url_1
OK url_1
crawling url_2
OK url_2
crawling url_3
OK url_3
crawling url_4
OK url_4
Wall time: 10 s

import asyncio
import nest_asyncio
nest_asyncio.apply()
import time

async def crawl_page(url):
    print('crawling {}'.format(url))
    sleep_time = int(url.split('_')[-1])
    #await asyncio.sleep(sleep_time)
    await asyncio.sleep(sleep_time)
    print('OK {}'.format(url))

async def main(urls):
    tasks = [asyncio.create_task(crawl_page(url)) for url in urls ]
    await asyncio.gather(*tasks)

%time asyncio.run(main(['url_1', 'url_2', 'url_3', 'url_4']))

import asyncio
import nest_asyncio
nest_asyncio.apply()

async def worker_1():
    await asyncio.sleep(1)
    return 1

async def worker_2():
    await asyncio.sleep(2)
    return 2 / 0

async def worker_3():
    await asyncio.sleep(3)
    print('over worker_3')
    return 3

async def main():
    task_1 = asyncio.create_task(worker_1())
    task_2 = asyncio.create_task(worker_2())
    task_3 = asyncio.create_task(worker_3())

    await asyncio.sleep(2)
    task_3.cancel()

    res = await asyncio.gather(task_1, task_2, task_3, return_exceptions=True)
    print(res)

%time asyncio.run(main())

########## 输出 ##########

# [1, ZeroDivisionError('division by zero'), CancelledError()]
# Wall time: 2 s

import asyncio
import random

async def consumer(queue, id):
    while True:
        val = await queue.get()
        print('{} get a val: {}'.format(id, val))
        await asyncio.sleep(1)

async def producer(queue, id):
    for i in range(5):
        val = random.randint(1, 10)
        await queue.put(val)
        print('{} put a val: {}'.format(id, val))
        await asyncio.sleep(2)

async def main():
    queue = asyncio.Queue()

    consumer_1 = asyncio.create_task(consumer(queue, 'consumer_1'))
    consumer_2 = asyncio.create_task(consumer(queue, 'consumer_2'))

    producer_1 = asyncio.create_task(producer(queue, 'producer_1'))
    producer_2 = asyncio.create_task(producer(queue, 'producer_2'))
    
    await asyncio.sleep(10)
    consumer_1.cancel()
    consumer_2.cancel()
    
    await asyncio.gather(consumer_1, consumer_2, producer_1, producer_2, return_exceptions=True)

%time asyncio.run(main())

########## 输出 ##########

# producer_1 put a val: 5
# producer_2 put a val: 3
# consumer_1 get a val: 5
# consumer_2 get a val: 3
# producer_1 put a val: 1
# producer_2 put a val: 3
# consumer_2 get a val: 1
# consumer_1 get a val: 3
# producer_1 put a val: 6
# producer_2 put a val: 10
# consumer_1 get a val: 6
# consumer_2 get a val: 10
# producer_1 put a val: 4
# producer_2 put a val: 5
# consumer_2 get a val: 4
# consumer_1 get a val: 5
# producer_1 put a val: 2
# producer_2 put a val: 8
# consumer_1 get a val: 2
# consumer_2 get a val: 8
# Wall time: 10 s