--- id: greenlet version: "3.5.5" license: MIT AND PSF-2.0 license_treatment: permissive maintenance: active --- # greenlet — Lightweight in-process concurrent programming License: permissive · Maintenance: active · Popularity: top 100 on PyPI ## Install pip install greenlet uv add greenlet poetry add greenlet ## Description .. This file is included into docs/history.rst Greenlets are lightweight coroutines for in-process concurrent programming. The "greenlet" package is a spin-off of `Stackless`_, a version of CPython that supports micro-threads called "tasklets". Tasklets run pseudo-concurrently (typically in a single or a few OS-level threads) and are synchronized with data exchanges on "channels". A "greenlet", on the other hand, is a still more primitive notion of micro-thread with no implicit scheduling; coroutines, in other words. This is useful when you want to control exactly when your code runs. You can build custom scheduled micro-threads on top of greenlet; however, it seems that greenlets are useful on their own as a way to make advanced control flow structures. For example, we can recreate generators; the difference with Python's own generators is that our generators can call nested functions and the nested functions can yield values too. (Additionally, you don't need a "yield" keyword. See the example in `test_generator.py `_). Greenlets are provided... ## AI interpretation — verify before relying Greenlet provides lightweight coroutines for in-process concurrent programming, enabling you to build custom micro-threads with explicit control flow without relying on the operating system's threading. Verdict: Greenlet is a stable, actively maintained library (top 100 PyPI, no known vulnerabilities) offering a proven foundation for building concurrent systems with explicit control flow. The permissive dual MIT/PSF-2.0 license poses no legal friction. Medium install friction from C extension compilation is typical and manageable for most environments. [View on SkillFed](https://skillfed.io/packages/greenlet) · [View on PyPI](https://pypi.org/project/greenlet/)