# <img src="docs/kloop@2x.png" height="96px" align="left"> kLoop - *asyncio on Linux kernel* [](README.zh.md) [](https://github.com/fantix/kloop/actions/workflows/build.yml) [](https://pypi.python.org/pypi/gino) [](https://app.codacy.com/gh/fantix/kloop/dashboard) [](http://license.coscl.org.cn/MulanPSL2/) kLoop is an implementation of the Python [asyncio](https://docs.python.org/3/library/asyncio.html) event loop written in [Cython](https://cython.org/), using [io_uring](https://unixism.net/loti/what_is_io_uring.html) and [kTLS](https://www.kernel.org/doc/html/latest/networking/tls-offload.html) features of the Linux kernel, therefore called k(ernel)Loop. kLoop is open-sourced and released under the [MulanPSL - 2.0 license](http://license.coscl.org.cn/MulanPSL2). **⚠️WARNING: THIS PROJECT IS IN PROOF-OF-CONCEPT STAGE!⚠️** ## Features * **Minimum syscalls** - all I/O calls are done in the kernel thanks to io_uring, and the only remaining syscall to `io_uring_enter()` is also optimized to be only called when necessary using the `SQPOLL` feature. That means most of the overhead of syscalls is gone; * **No GIL in the main-loop** - the hot-path is written in Cython without GIL, that means it's compiled into pure C code without Python structures, saving some memory and execution time. On the other hand, GIL is only taken before Python callbacks, so it's slightly more friendly to multithreading, which is still not recommended though. * **TLS offloading** - all symmetric-key encryption and decryption work is offloaded to the NIC if supported, or to the thread pool of io_uring otherwise. This allows us to free up CPU for more I/O, or leverage all the CPU cores even if the application is running single-threaded. * **Asynchronous DNS resolving** - we blended in the Rust [trust-dns](https://github.com/bluejekyll/trust-dns/) library with a custom I/O runtime bridging to io_uring in C (including reading the `/etc/resolv.conf` and `/etc/hosts` files), providing flexible APIs to manage the concurrency, cache and configuration in Python. ## Requirements * Python >= 3.10 * Linux >= 5.11 (enable kTLS with `modprobe tls`) * OpenSSL >= 3.0 (kTLS receive offloading on TLS 1.3 requires the latest development version) Development and testing is done on Ubuntu 22.04. ## Architecture Diagram <img src="docs/architecture.en.png" width="620px" alt="architecture.png"> Looks like the Lucky Charms factory, says @aaronbrighton ... ## Development ### Ubuntu 22.04 ```bash sudo apt update sudo apt install gcc libssl-dev python3-dev python3.10-venv curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh python3 -m venv path/to/env source path/to/env/bin/activate pip install cython KLOOP_DEBUG=1 python setup.py develop # or just run `make` ```