Runloom - Go-style coroutines for free-threaded Python
Show HN: Runloom – Go-style coroutines for Python free-threaded
Runloom brings Go-style stackful coroutines to Python 3.13t+ with free-threading support, enabling developers to write blocking code that scales across all CPU cores. By using a hand-rolled assembly context switch and a work-stealing scheduler, it allows millions of concurrent fibers to run efficiently without the complexity of async/await. The library features a seamless monkey patching system that transforms standard blocking libraries into cooperative tasks, delivering throughput that rivals Go while maintaining Python's simplicity. Ideal for high-performance networking and concurrent workloads.
Write blocking code — fiber(fn), plain recv/send, no async/await — and run a million of them across every core in one process.
- simonw
This is an intimidating amount of code! 12,303 lines of C and 244,740 lines of Python, which looks to be a ton of monkeypatching plus huge amounts of test code.
Only one commit added all of that, just two hours ago.
The published numbers are impressive, but its hard to evaluate how much trust can be put in a project of this complexity at this early stage.
- OutOfHere
Very cool. Just a few days ago, I had noted a proposed spec for a biologically-inspired high-level concurrency model where no user-facing channels/send/recv are required. The user secrets proteins, defines their receptors, and the system handles the rest. Unlike you, I don't have an implementation, but now with GPT 5.6 released it's within reach. The actionable spec prompt is at https://gist.github.com/impredicative/a0dd4ac68cd05e9d3855dc...
- ksdme9
How does this compare with gevent?
- OutOfHere
Does your code have a significant dependency on the version of Python? How easy will it be for you to maintain your code to support Python 3.15, 3.16, etc.? Is it too dependent on the implementation of Python 3.13 and 3.14 or its low level aspects? What is all the Python code doing?
- ebeirne
This is a seriously impressive project. I see your pitch is M:N work-stealing across real cores on free-threaded 3.13t/3.14t which i think is only possible because nogil now exists. which makes gevent seem lackluster in comparison