Client / AsyncClient instantiated extremely slow

[TrueRou]

Client / AsyncClient instantiated extremely slow (over 200ms).

The examples are making only one request by Client, this may cause misleading.

>>> async with httpx.AsyncClient() as client:
...     r = await client.get('https://www.example.com/')
...
>>> r
<Response [200 OK]>

Though there were docs about clients, developers did not know that not only they can't get the most benefit from connection pooling, BUT ALSO face over 200ms cost to create client itself. TUN Proxy will aggravate the condition by 2 ~ 3 times.

Warning
In order to get the most benefit from connection pooling, make sure you're not instantiating multiple client instances - for example
by using async with inside a "hot loop". This can be achieved either by having a single scoped client that's passed throughout
wherever it's needed, or by having a single global client instance.

Code:

import httpx
import time
import asyncio


async def test_async_client_creation_time():
    start_time = time.time()
    async with httpx.AsyncClient() as client:
        end_time = time.time()
        print(f"AsyncClient creation took {end_time - start_time:.6f} seconds")


def test_client_creation_time():
    start_time = time.time()
    with httpx.Client() as client:
        end_time = time.time()
        print(f"Client creation took {end_time - start_time:.6f} seconds")


# Run the async function
asyncio.run(test_async_client_creation_time())
# Run the sync function
test_client_creation_time()

Results:

AsyncClient creation took 0.389101 seconds
Client creation took 0.202185 seconds