如何从我的 FastAPI 应用程序向另一个站点 (API) 发送 HTTP 请求？

Posted 2023-02-15

【中文标题】如何从我的 FastAPI 应用程序向另一个站点 (API) 发送 HTTP 请求？

【英文标题】：How can I send an HTTP request from my FastAPI app to another site (API)?

【发布时间】：2020-12-31 12:05:20

【问题描述】：

我正在尝试使用以下代码 sn-p 一次向服务器 http://httpbin.org/uuid 发送 100 个请求

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)

我将 FastAPI 与 Asyncio 一起使用，以实现大约 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 函数以对r.text 进行其他操作。我知道要达到如此短的时间，需要并发，但我不确定我在这里犯了什么错误。

【问题讨论】：

即使使用 curl 我得到 0.111 毫秒的 100 个请求 time for _ in 1..100; do curl http://httpbin.org/uuid & done 这很奇怪。

这是因为每个 curl 都拆分为不同的进程，但同样的事情在我的代码中不起作用 - imgur.com/a/pmh7qLb time for _ in 1..100; do curl http://httpbin.org/uuid & done && ps aux | grep curl

IKR 我在说这个，asyncio 的行为应该和 curl 完全一样，我在我的机器上尝试了不同的方法，但也没有成功，然后我想到 uvicorn 可能只是另一个事件循环就是这个问题，之后我正常运行了，也花了这么长时间..

我也在使用这种模式进行异步，这对我来说看起来很可靠，我创建了一个 gist 你可能想看看

你也可以试试python-httpx.org。使用基本 url 创建一个 AsyncClient，然后使用客户端（相当于 request 会话）对 url 执行 100 次调用

【参考方案1】：

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.AsyncClient 通常在 FastAPI 应用程序中用于请求外部服务。它也用于应用程序的asynchronous tests。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 也可用于 FastAPI 应用程序，但如果您确实需要，请这样做。

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，你可以像这样使用asyncio.semaphore：

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

【讨论】：

您可能希望在task 中创建一个会话并将其传递给main()。这将使 aiohttp 更有效，例如重用 TCP 连接。

"它是 FastAPI 的依赖项。" - 不是。

这只是fastapi[test]的依赖，所以我删除了这句话以避免混淆。

@任何理由使用 httpx？与 aiohttp 相比？我问是因为 httpx 被认为是 beta 版本，所以在生产中，你想要“更”稳定的版本，thx

@AlexJolig 您链接到的page 的日期为2021-04-17。该答案的日期为 2020-09-14。该页面的标题与此问题相同。也许您应该将您的评论指向该网站的维护者，并收回您对该答案作者的指控。

【参考方案2】：

@Alex Noname 很好地使用了异步请求库。如果你想让代码更快，我建议使用 asyncio.Queue 作为替代。在这个例子中，我创建了 100 个生产者和 100 个消费者。您可以限制队列中的最大消息数，例如，生产者等待直到有空间容纳新消息

asyncio.Queue(maxsize=100)

我也使用了 httpx 中的 AsyncClient。

如果您想了解有关队列的更多信息，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": "62fda759-b382-44e4-ad7d-d19a952fc1c7"\n\n', '\n  "uuid": "73faeb91-215e-4e49-8f11-11b98e499cc7"\n\n', '\n  "uuid": "f3279c45-ebcc-4079-b823-3efe825c7cf8"\n\n', '\n  "uuid": "b892672b-4510-44f4-b61e-9cccaa52421e"\n\n', '\n  "uuid": "8926979d-71a7-4171-9389-ddafff89e229"\n\n', '\n  "uuid": "d97cef59-4862-42ca-b0f2-261f98fd4b6f"\n\n', '\n  "uuid": "3362ff93-89e4-4889-a2f2-2e03771e86ce"\n\n', '\n  "uuid": "9f525251-4fe4-4a9c-97b5-2f01d2b37aaf"\n\n', '\n  "uuid": "036959d4-3179-40f9-bbf3-32274f2cede2"\n\n', '\n  "uuid": "157f8c22-6214-4e27-ab5d-08d39f96d1d3"\n\n', '\n  "uuid": "e4bfbf62-7c33-4fd7-a231-47f5ce398041"\n\n', '\n  "uuid": "a41512c1-3346-4457-a379-64d690ffc2ea"\n\n', '\n  "uuid": "7bb07cfb-294b-44fa-a8dc-6d283c54409f"\n\n', '\n  "uuid": "f2297d22-a2d0-47ff-8d65-24c6fe7877a7"\n\n', '\n  "uuid": "645e255b-4c93-4c8f-9ff2-43da293db660"\n\n', '\n  "uuid": "9190e370-dfa9-47a6-8cef-8df7ab762433"\n\n', '\n  "uuid": "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

【讨论】：

你能解释一下这段代码比the other answer更快吗？在该示例中，可能需要避免几个编程缺陷，例如将项目附加到理解列表中的外部列表，而不是直接使用理解列表。此外，当q 的maxsize 低于100 时，代码将永远挂起，因为生产者最终将挂在queue.put() 上，因此gather(*producers) 永远不会完成。您必须将这两个集合安排为独立的任务，但这不会发生在这里。投反对票。

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