aiohttp-fast-zlib

0.3.0 verified Thu Apr 16 auth: no python

aiohttp-fast-zlib is a Python library (current version 0.3.0) that replaces the default `zlib` usage in `aiohttp` with faster alternatives like `isal` or `zlib-ng`. This significantly improves compression and decompression performance, especially for `aiohttp`'s WebSocket connections, where `zlib` can be a bottleneck. The library has seen several updates over the past year, indicating active maintenance and development.

pip install aiohttp-fast-zlib

Common errors

error WARNING (MainThread) [aiohttp_fast_zlib] zlib_ng and isal are not available, falling back to zlib, performance will be degraded. ↓

cause The optional faster compression libraries (`isal` or `zlib-ng`) were not installed when `aiohttp-fast-zlib` was installed.

fix

Install aiohttp-fast-zlib with the desired extra: pip install aiohttp-fast-zlib[isal] (recommended) or pip install aiohttp-fast-zlib[zlib-ng].

error ERROR: pip's dependency resolver does not currently take into account all the packages that are installed. This behaviour is the source of the following dependency conflicts: <another_library> requires aiohttp==X.Y.Z, but you have aiohttp A.B.C which is incompatible. ↓

cause Conflicting `aiohttp` version requirements between `aiohttp-fast-zlib` and other installed libraries in your environment.

fix

Carefully check the aiohttp version required by all libraries in your project. Attempt to find an aiohttp version that satisfies all dependencies, or isolate conflicting dependencies using virtual environments.

Warnings

gotcha Performance will be degraded if neither 'isal' nor 'zlib-ng' are installed alongside 'aiohttp-fast-zlib'. The library will silently fall back to the slower standard Python 'zlib' module. ↓

fix Install with an extra: `pip install aiohttp-fast-zlib[isal]` or `pip install aiohttp-fast-zlib[zlib-ng]`.

breaking aiohttp-fast-zlib v0.3.0 introduces support for aiohttp 3.12 and newer. Older versions of aiohttp-fast-zlib had different aiohttp compatibility requirements. Always check the project's PyPI or GitHub page for precise aiohttp version compatibility with the specific aiohttp-fast-zlib version you are using. ↓

fix Ensure your `aiohttp` version meets the requirements of `aiohttp-fast-zlib`. For v0.3.0, ensure `aiohttp>=3.12.0` is installed. If using an older `aiohttp-fast-zlib`, you may need an older `aiohttp`.

gotcha Aiohttp itself (>=3.12) provides `aiohttp.set_zlib_backend()` for manually specifying a zlib-compatible module. `aiohttp-fast-zlib` offers automatic detection and fallback, but direct `aiohttp.set_zlib_backend()` calls will override its effects. ↓

fix If using `aiohttp-fast-zlib`, rely on its `enable()` function for automatic backend selection. Avoid `aiohttp.set_zlib_backend()` unless you explicitly want to manage the zlib backend yourself and override `aiohttp-fast-zlib`'s behavior.

Install

pip install aiohttp-fast-zlib[isal]

pip install aiohttp-fast-zlib[zlib-ng]

Imports

enable
```
import aiohttp_zlib_fast
aiohttp_zlib_fast.enable()
```
Call `enable()` once at application startup to patch aiohttp's zlib backend.

Quickstart

This quickstart demonstrates how to enable `aiohttp-fast-zlib` and then use a standard `aiohttp.ClientSession` to make a request. The `enable()` call patches `aiohttp` globally to use the faster zlib backend. You can set the `TEST_URL` environment variable to point to a service that returns gzipped content (e.g., `httpbin.org/gzip`) to observe its effect.

import aiohttp
import asyncio
import os
import aiohttp_zlib_fast

# Enable the fast zlib backend. isal is preferred if available, then zlib-ng, else standard zlib.
aiohttp_zlib_fast.enable()

async def fetch(session, url):
    async with session.get(url) as response:
        print(f"Status: {response.status}")
        print(f"Content-type: {response.headers.get('content-type')}")
        # If the response is compressed, aiohttp will decompress it using the enabled backend
        text = await response.text()
        print(f"Body snippet: {text[:100]}...")

async def main():
    async with aiohttp.ClientSession() as session:
        # Use a real URL, or an httpbin-like service that supports compression
        await fetch(session, os.environ.get('TEST_URL', 'http://httpbin.org/gzip'))

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