Unexpected Performance Results: httpx Async Slower than aiohttp and httpx Sync

[brianler]

Asynchronous requests with httpx are much slower than those with aiohttp, and surprisingly, even slower than httpx's synchronous requests.

Test Results:

-> httpx AsyncClient 2.01 s

-> aiohttp AsyncClient 0.36 s

-> httpx Client with asyncio.to_thread 1.46 s

Test Script:

import asyncio
import httpx
import aiohttp
import time


async def ah():
    async with httpx.AsyncClient(timeout=3600) as client:
        response = await client.get('https://connect.rom.miui.com/generate_204')
        print(response.status_code, response.text)


async def aio():
    async with aiohttp.ClientSession(timeout=aiohttp.ClientTimeout(total=3600)) as client:
        async with client.get('https://connect.rom.miui.com/generate_204') as resp:
            data = await resp.text()
            print(resp.status, data)


def ah_sync():
    with httpx.Client(timeout=3600) as client:
        response = client.get('https://connect.rom.miui.com/generate_204')
        print(response.status_code, response.text)


async def mutli_ah():
    tasks = [ah() for _ in range(100)]
    await asyncio.gather(*tasks)


async def mutli_aio():
    tasks = [aio() for _ in range(100)]
    await asyncio.gather(*tasks)


async def mutli_ah_2():
    tasks = [asyncio.to_thread(ah_sync) for _ in range(100)]
    await asyncio.gather(*tasks)


t1 = time.perf_counter()
asyncio.run(mutli_ah())
print('httpx AsyncClient', time.perf_counter() - t1, 's')
# ------------------------------
# asyncio.run(mutli_aio())
# print('aiohttp AsyncClient', time.perf_counter() - t1, 's')
# ------------------------------
# asyncio.run(mutli_ah_2())
# print('httpx Client with asyncio.to_thread', time.perf_counter() - t1)

[brianler]

When reusing the client side, the gap between the two is small.

Test Results:

-> aiohttp AsyncClient 0.78 s
-> httpx AsyncClient 0.81 s

Test Script:

import asyncio

import aiohttp
import httpx


async def ah(client):
    await client.get("https://www.google.com/generate_204")


async def aio(client):
    async with client.get("https://www.google.com/generate_204") as resp:
        await resp.text()


async def mutli_ah():
    async with httpx.AsyncClient(timeout=3600) as client:
        stime = asyncio.get_event_loop().time()
        tasks = [ah(client) for _ in range(100)]
        await asyncio.gather(*tasks)
        print("httpx AsyncClient", asyncio.get_event_loop().time() - stime, "s")


async def mutli_aio():
    async with aiohttp.ClientSession(timeout=aiohttp.ClientTimeout(total=3600)) as client:
        stime = asyncio.get_event_loop().time()
        tasks = [aio(client) for _ in range(100)]
        await asyncio.gather(*tasks)
        print("aiohttp AsyncClient", asyncio.get_event_loop().time() - stime, "s")


async def main():
    await mutli_aio()
    await mutli_ah()


if __name__ == "__main__":
    asyncio.run(main())

🚀 When http2 is enabled and there are a large number of connections, httpx performs better than aiohttp.

async with httpx.AsyncClient(timeout=3600, http2=True) as client:
    ...