使用Asyncio进行多次调用并将结果添加到字典

问题描述

我在围绕Python3的Asyncio库时遇到了麻烦。我有一个邮政编码列表，我正在尝试对API进行异步调用，以获得每个邮政编码对应的城市和州。我可以使用for循环按顺序成功完成此操作，但我希望在邮政编码列表较大的情况下使其更快。

这是我的原件工作正常的示例

import urllib.request, json

zips = ['90210', '60647']

def get_cities(zipcodes):
    zip_cities = dict()
    for idx, zipcode in enumerate(zipcodes):
        url = 'http://maps.googleapis.com/maps/api/geocode/json?address='+zipcode+'&sensor=true'
        response = urllib.request.urlopen(url)
        string = response.read().decode('utf-8')
        data = json.loads(string)
        city = data['results'][0]['address_components'][1]['long_name']
        state = data['results'][0]['address_components'][3]['long_name']
        zip_cities.update({idx: [zipcode, city, state]})
    return zip_cities

results = get_cities(zips)
print(results)
# returns {0: ['90210', 'Beverly Hills', 'California'],
#          1: ['60647', 'Chicago', 'Illinois']}

这是我尝试将其设为异步的可怕的非功能性尝试

import asyncio
import urllib.request, json

zips = ['90210', '60647']
zip_cities = dict()

@asyncio.coroutine
def get_cities(zipcodes):
    url = 'http://maps.googleapis.com/maps/api/geocode/json?address='+zipcode+'&sensor=true'
    response = urllib.request.urlopen(url)
    string = response.read().decode('utf-8')
    data = json.loads(string)
    city = data['results'][0]['address_components'][1]['long_name']
    state = data['results'][0]['address_components'][3]['long_name']
    zip_cities.update({idx: [zipcode, city, state]})

loop = asyncio.get_event_loop()
loop.run_until_complete([get_cities(zip) for zip in zips])
loop.close()
print(zip_cities) # doesnt work

任何帮助都不胜感激。我在网上看到的所有教程似乎都有点让我摸不着头脑。

注意：我见过一些使用aiohttp的示例。如果可能的话，我希望坚持使用原生Python3库。

HTTP

如果您使用urllib进行推荐答案请求，您将无法获得任何并发性，因为它是一个同步库。将调用urllib的函数包装在coroutine中不会改变这一点。您必须使用集成到asyncio中的异步HTTP客户端，如aiohttp：

import asyncio
import json
import aiohttp

zips = ['90210', '60647']
zip_cities = dict()

@asyncio.coroutine
def get_cities(zipcode,idx):
    url = 'https://maps.googleapis.com/maps/api/geocode/json?key=abcdfg&address='+zipcode+'&sensor=true'
    response = yield from aiohttp.request('get', url)
    string = (yield from response.read()).decode('utf-8')
    data = json.loads(string)
    print(data)
    city = data['results'][0]['address_components'][1]['long_name']
    state = data['results'][0]['address_components'][3]['long_name']
    zip_cities.update({idx: [zipcode, city, state]})

if __name__ == "__main__":        
    loop = asyncio.get_event_loop()
    tasks = [asyncio.async(get_cities(z, i)) for i, z in enumerate(zips)]
    loop.run_until_complete(asyncio.wait(tasks))
    loop.close()
    print(zip_cities)

我知道您更喜欢只使用stdlib，但是asyncio库不包括HTTP客户端，因此您基本上必须重新实现aiohttp部分来重新创建它提供的功能。我想另一种选择是在后台线程中进行urllib调用，这样它们就不会挡路事件循环，但是当aiohttp可用时这样做有点愚蠢(而且有点违背了使用asyncio的初衷)：

import asyncio
import json
import urllib.request
from concurrent.futures import ThreadPoolExecutor

zips = ['90210', '60647']
zip_cities = dict()

@asyncio.coroutine
def get_cities(zipcode,idx):
    url = 'https://maps.googleapis.com/maps/api/geocode/json?key=abcdfg&address='+zipcode+'&sensor=true'
    response = yield from loop.run_in_executor(executor, urllib.request.urlopen, url)
    string = response.read().decode('utf-8')
    data = json.loads(string)
    print(data)
    city = data['results'][0]['address_components'][1]['long_name']
    state = data['results'][0]['address_components'][3]['long_name']
    zip_cities.update({idx: [zipcode, city, state]})

if __name__ == "__main__":
    executor = ThreadPoolExecutor(10)
    loop = asyncio.get_event_loop()
    tasks = [asyncio.async(get_cities(z, i)) for i, z in enumerate(zips)]
    loop.run_until_complete(asyncio.wait(tasks))
    loop.close()
    print(zip_cities)