如何将 HTTP 请求从我的 FastAPI 应用程序发送到另一个站点 (API)？

问题描述 投票：0回答：3

我尝试使用以下代码片段一次向服务器发送 100 个请求 

http://httpbin.org/uuid

from fastapi import FastAPI
from time import sleep
from time import time
import requests
import asyncio

app = FastAPI()

URL= "http://httpbin.org/uuid"


# @app.get("/")
async def main():
    r = requests.get(URL)
    # print(r.text)
    
    return r.text

async def task():
    tasks = [main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main(),main()]
    # print(tasks)
    # input("stop")
    result = await asyncio.gather(*tasks)
    print (result)

@app.get('/')
def f():
    start = time()
    asyncio.run(task())
    print("time: ",time()-start)

我使用 FastAPI 和 Asyncio 来实现大约 3 秒或更短的最短时间，但使用上述方法我得到的总时间为 66 秒，超过一分钟。我还想保留 

main
功能，以便对 
r.text
进行其他操作。我知道要实现如此短的时间，需要并发性，但我不确定我在这里犯了什么错误。

python async-await httprequest python-asyncio fastapi
3个回答
90
投票

requests
是一个同步库。您需要使用基于 
asyncio
的库来异步发出请求。

httpx

httpx
通常在FastAPI应用程序中用于请求外部服务。它提供了同步和异步客户端，可以适当地用于 
def
和 
async def
路径操作。还建议用于应用程序的异步测试。我建议默认使用它。

from fastapi import FastAPI
from time import time
import httpx
import asyncio

app = FastAPI()

URL = "http://httpbin.org/uuid"


async def request(client):
    response = await client.get(URL)
    return response.text


async def task():
    async with httpx.AsyncClient() as client:
        tasks = [request(client) for i in range(100)]
        result = await asyncio.gather(*tasks)
        print(result)


@app.get('/')
async def f():
    start = time()
    await task()
    print("time: ", time() - start)

输出

['{\n  "uuid": "65c454bf-9b12-4ba8-98e1-de636bffeed3"\n}\n', '{\n  "uuid": "03a48e56-2a44-48e3-bd43-a0b605bef359"\n}\n',...
time:  0.5911855697631836

aiohttp

aiohttp
如果您愿意，也可以在 FastAPI 应用程序中使用。

from fastapi import FastAPI
from time import time
import aiohttp
import asyncio

app = FastAPI()

URL = "http://httpbin.org/uuid"


async def request(session):
    async with session.get(URL) as response:
        return await response.text()


async def task():
    async with aiohttp.ClientSession() as session:
        tasks = [request(session) for i in range(100)]
        result = await asyncio.gather(*tasks)
        print(result)


@app.get('/')
async def f():
    start = time()
    await task()
    print("time: ", time() - start)

如果你想限制并行执行的请求数量，你可以使用

asyncio.semaphore
，如下所示：

MAX_IN_PARALLEL = 10
limit_sem = asyncio.Semaphore(MAX_IN_PARALLEL)


async def request(client):
    async with limit_sem:
        response = await client.get(URL)
        return response.text
2
投票

@Alex Noname 很好地阐述了使用异步请求库。如果您想让代码更快，我建议使用 asyncio.Queue 作为替代方案。在此示例中，我启动了 100 个生产者和 100 个消费者。您可以限制队列中消息的最大数量，然后生产者等待，直到有空间容纳新消息

asyncio.Queue(maxsize=100)

我还使用了 httpx 中的 AsyncClient。

如果您想了解更多有关队列的信息，我建议您阅读这篇文章 https://realpython.com/async-io-python/

from time import time
from typing import List

from fastapi import FastAPI
from httpx import AsyncClient

app = FastAPI()

URL = "http://httpbin.org/uuid"
client = AsyncClient()


async def main():
    r = await client.get(URL)
    return r.text


async def producer(queue: asyncio.Queue):
    await queue.put(main)


async def consumer(queue: asyncio.Queue, resp: List):
    # await queue.get() == main  -> without arguments
    resp.append(await (await queue.get())())


async def task():
    q = asyncio.Queue(maxsize=100)
    response = []
    consumers = []
    producers = []
    [consumers.append(consumer(q, response)) for c in range(100)]
    [producers.append(producer(q)) for p in range(100)]

    await asyncio.gather(*producers)
    await asyncio.gather(*consumers)
    print(response)


@app.get('/')
def f():
    start = time()
    asyncio.run(task())
    print("time: ", time() - start)


if __name__ == '__main__':
    f()

输出

['{\n  "uuid": "a7713d07-ea5d-40d3-95b4-6673f3c50a8b"\n}\n', '{\n  "uuid": "c93f8b89-2c44-40fa-9e5f-736e22ad5f23"\n}\n', '{\n  "uuid": "cbb4ad76-7790-45ae-87f1-e425eddc8021"\n}\n', '{\n  "uuid": "4c1d81c0-ae7d-401a-99df-e98af3651335"\n}\n', '{\n  "uuid": "c5f70738-fbba-4cf9-8fdf-29f8b4eabe63"\n}\n', '{\n  "uuid": "d016b852-4312-4502-a336-a6a110237d1d"\n}\n', '{\n  "uuid": "22d8b00b-4266-4236-b5a3-ed5d7c5be416"\n}\n', '{\n  "uuid": "cd54fdbb-7de9-4df3-90cc-e6b108d5fdf8"\n}\n', '{\n  "uuid": "757f0a26-7896-4a04-bea2-60c66a38b05b"\n}\n', '{\n  "uuid": "72eb6584-21f4-449b-b6bd-d0f88666126f"\n}\n', '{\n  "uuid": "b3deadf5-5b79-491b-829c-0404c306cb68"\n}\n', '{\n  "uuid": "789e7422-493d-49d2-9585-e5ca34b7cf36"\n}\n', '{\n  "uuid": "48d29a82-ff7c-41f5-8af2-42784326a31f"\n}\n', '{\n  "uuid": "84b2d67c-331c-4037-b6e4-c299d93c1899"\n}\n', '{\n  "uuid": "386e79f9-073a-4f27-961c-7befcdf95cd4"\n}\n', '{\n  "uuid": "8dfdb5e4-dd69-4043-b174-48ec8505f36f"\n}\n', '{\n  "uuid": "633e634b-b107-42bb-a7d3-c6bbfff089a0"\n}\n', '{\n  "uuid": "962d665f-8663-4be7-a3c6-9426ba500bf4"\n}\n', '{\n  "uuid": "320fb858-a751-4c34-9cdb-ddd2f4e28efa"\n}\n', '{\n  "uuid": "46a75693-5255-4ac7-8d7a-54910b4d6f68"\n}\n', '{\n  "uuid": "5323734b-7ff9-455e-ba5a-66383e6b9a1f"\n}\n', '{\n  "uuid": "622a579f-35b6-4e4b-9dba-a8a69c2049c8"\n}\n', '{\n  "uuid": "593d5e82-cef3-4be0-99ab-e3034855d7a1"\n}\n', '{\n  "uuid": "80f139df-2a27-40c1-8329-e4faa035c45c"\n}\n', '{\n  "uuid": "a97e084c-4d30-4c7b-a96e-89ed00dcfe2a"\n}\n', '{\n  "uuid": "360d49eb-7222-4064-81c2-6eba2d43a9a5"\n}\n', '{\n  "uuid": "a81b6eab-a646-4e58-b986-96a90baa52aa"\n}\n', '{\n  "uuid": "0160337e-b400-41d6-ae89-aa46c5131f40"\n}\n', '{\n  "uuid": "e600722f-8c15-4959-948b-4c4e5296feb2"\n}\n', '{\n  "uuid": "f15403e4-3674-43b2-a0c9-649fd828ba7e"\n}\n', '{\n  "uuid": "36bf139c-cc18-45a8-bc55-e7f90ce290b5"\n}\n', '{\n  "uuid": "b2368a3c-d86b-4fcd-a0d3-bf7f8f657a83"\n}\n', '{\n  "uuid": "d9f16c36-3572-4c70-8a41-3d4e279d76bf"\n}\n', '{\n  "uuid": "796087cc-a202-40dd-9921-14802a73323d"\n}\n', '{\n  "uuid": "089fa0d7-4c48-4daa-a80d-cb5ebd37dfb7"\n}\n', '{\n  "uuid": "e5582bc7-0f8a-4da7-b640-79a0d812154d"\n}\n', '{\n  "uuid": "bac0640b-0d0b-4bf2-a3c1-36bdda7cce03"\n}\n', '{\n  "uuid": "b4353004-02b2-4846-8692-33dd77ad1d3f"\n}\n', '{\n  "uuid": "1b34a744-d0ea-4acf-8bda-33743800d86a"\n}\n', '{\n  "uuid": "4d9dd269-6ee2-4356-9bc4-ddf188445320"\n}\n', '{\n  "uuid": "a1f380df-0c0d-4aee-bbb7-c3e99fbfe54f"\n}\n', '{\n  "uuid": "7cb762eb-1a42-433d-97ea-aa9de4504e35"\n}\n', '{\n  "uuid": "981c40e2-64bf-4746-8103-9430bda2a5ca"\n}\n', '{\n  "uuid": "22b778eb-82d1-48b9-9874-5ebb80ddb8b1"\n}\n', '{\n  "uuid": "e7a9e0e8-7964-400c-aafe-9c36b9b7e1a0"\n}\n', '{\n  "uuid": "21a59b91-2732-4bb6-a47e-84008a03c20c"\n}\n', '{\n  "uuid": "a78eeb39-5ecb-4509-87c2-b4a2529e3536"\n}\n', '{\n  "uuid": "4a332579-ce03-4f69-9db5-78da9196d6b2"\n}\n', '{\n  "uuid": "55fbc34f-4eb3-4356-98e3-1df38054a4b2"\n}\n', '{\n  "uuid": "257ac454-09c2-4fd4-bdb3-303495360fa2"\n}\n', '{\n  "uuid": "7505cc0d-01b3-47f8-91d4-3e54d0f387de"\n}\n', '{\n  "uuid": "0fd67af2-622e-4688-b3c8-f64e20f1f3ec"\n}\n', '{\n  "uuid": "07653ccf-f408-4807-8ff5-e6098d657451"\n}\n', '{\n  "uuid": "b9d0ff18-fd67-4afa-adbe-ebcb53380804"\n}\n', '{\n  "uuid": "70d4d53b-2f06-41be-bb38-47f010cfa40f"\n}\n', '{\n  "uuid": "a6d49873-e749-4578-ae9c-e6c6f473535d"\n}\n', '{\n  "uuid": "e67efee5-76ad-4812-bb97-016ef9ff87e8"\n}\n', '{\n  "uuid": "67886926-b2d9-44fb-b836-26b81c53e5fb"\n}\n', '{\n  "uuid": "dcbd4ff8-e3cd-4e03-b12d-5fb3834b0e00"\n}\n', '{\n  "uuid": "65c2eaee-5fa2-4b58-a1c3-adeb04d92c71"\n}\n', '{\n  "uuid": "2cee4ec9-952e-45c5-91b7-f4f5848c3455"\n}\n', '{\n  "uuid": "8e94bf1c-ee5a-483a-a962-d0b9aea48c95"\n}\n', '{\n  "uuid": "c1fe17bc-bedf-4c4c-952d-a5921f693d9f"\n}\n', '{\n  "uuid": "221456fd-48ca-4826-a8b5-5fa0b23db6e4"\n}\n', '{\n  "uuid": 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"83216551-9f1b-48b2-8cd6-fd125a7ce965"\n}\n', '{\n  "uuid": "aaddb98c-879b-472d-aa39-1a684ef7d179"\n}\n', '{\n  "uuid": "4bd7e2fd-1453-4433-aa9f-bc29d82f5b9d"\n}\n', '{\n  "uuid": "b02d65e8-2063-4060-96af-088ec497fc10"\n}\n', '{\n  "uuid": "e10e3dd2-83c5-4595-afe4-4145bce79193"\n}\n', '{\n  "uuid": "8cb62784-1b5d-4dcc-8342-02ad7d417ca9"\n}\n', '{\n  "uuid": "13ef1509-4f69-4426-ac42-cb29a2d0f094"\n}\n', '{\n  "uuid": "4d4571d5-69bb-4625-b246-b5eef50aa10d"\n}\n', '{\n  "uuid": "75e7a2ca-bfa8-43b9-b33a-f3f927453579"\n}\n', '{\n  "uuid": "0a8cc8ff-2039-4873-9e38-afad3e10d726"\n}\n', '{\n  "uuid": "189ae75b-4879-4897-9725-f9be17e49844"\n}\n', '{\n  "uuid": "ba482468-f45f-4060-a0c1-3ef31bb283c8"\n}\n', '{\n  "uuid": "3809f1c7-2f11-487d-bf96-8abf64e08298"\n}\n', '{\n  "uuid": "da5ea88b-974d-4238-9654-ac56c657c8b4"\n}\n', '{\n  "uuid": "edc3de79-7cf4-42a3-a5f4-b754136a6fd3"\n}\n', '{\n  "uuid": "6f5ecd91-537c-4009-8435-6c31ce035d36"\n}\n', '{\n  "uuid": "4a33b29d-78ba-468f-8f30-a01b3d9e2a87"\n}\n', '{\n  "uuid": "a5a2ef2d-d4a2-48e1-8335-f8c1309328c4"\n}\n', '{\n  "uuid": "3d1679da-afdd-4f04-9c16-0aaea4c53d0c"\n}\n', '{\n  "uuid": "c4025845-0d4c-4549-acb8-1a249b33e644"\n}\n']
time:  1.0535461902618408
0
投票

如果您不想使用 aiohttp 或 httpx，可以使用 asyncio.to_thread 将同步请求隐藏为异步

async def async_request(url,payload,**kwargs):
返回等待 asyncio.to_thread(requests.post,url,payload)

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