Question

我使用loop.run_in_executor()来调用requests.get()，但是它运行时没有并发，而我注释该行并将其留给loop.run_in_executor()中的print时，脚本会同时运行。

import asyncio
import requests

async def get(name):
    loop=asyncio.get_event_loop()
    for i in range(15):
        loop.run_in_executor(None,requests.get,'https://www.google.com',
                dict(proxies={'http':'socks5://127.0.0.1:1080','https':'socks5://127.0.0.1:1080'}))
        loop.run_in_executor(None,print,f'{name} thread {i}th get')

async def main():
    await get('A')
    await get('B')
    await get('C')

loop=asyncio.get_event_loop()
loop.run_until_complete(main())

脚本的输出是有序的，例如

A thread 0th get
A thread 1th get
...
A thread 14th get
B thread 0th get
B thread 1th get
...
B thread 14th get
C thread 0th get
C thread 1th get
...

但是，在注释第7行和第8行代码后，输出的顺序混乱了：

import asyncio
import requests

async def get(name):
    loop=asyncio.get_event_loop()
    for i in range(15):
        #loop.run_in_executor(None,requests.get,'https://www.google.com',
                #dict(proxies={'http':'socks5://127.0.0.1:1080','https':'socks5://127.0.0.1:1080'}))
        loop.run_in_executor(None,print,f'{name} thread {i}th get')

async def main():
    await get('A')
    await get('B')
    await get('C')

loop=asyncio.get_event_loop()
loop.run_until_complete(main())

输出的最后几行就像

...
C thread 5th get
C thread 0th get
C thread 13th get
B thread 12th get
C thread 2th get
C thread 6th get
C thread 10th get

为什么原始版本在没有同意的情况下运行？

Answer 1

您误解了执行逻辑，这是另一个更简单的示例，但是逻辑是相同的，希望对您有所帮助。我的英语不好，代码比我的表现更好。

import asyncio
import random
import time


def sleep_print(a):
    time.sleep(random.randint(1, 300) / 100)
    print(a)


async def get(name):
    loop = asyncio.get_event_loop()
    for i in range(4):
        loop.run_in_executor(None, sleep_print, f"first sleep_print: {name} thread {i}th get\n")
        loop.run_in_executor(None, sleep_print, f"second sleep_print: {name} thread {i}th get\n")


async def main():
    await get("A")


loop = asyncio.get_event_loop()
start = time.time()
loop.run_until_complete(main())
print("cost:", time.time() - start)

我的输出：

cost: 0.0006608963012695312

second sleep_print: A thread 1th get

second sleep_print: A thread 3th get

first sleep_print: A thread 2th get

first sleep_print: A thread 1th get

first sleep_print: A thread 0th get

second sleep_print: A thread 2th get

first sleep_print: A thread 3th get

second sleep_print: A thread 0th get

为什么通过loop.run_in_executor（）使用request.get（）的进程不能同时运行？

1 个答案: