# python-greenlet/greenlet

Lightweight in-process concurrent programming

Repository: https://github.com/python-greenlet/greenlet
Canonical: https://ross.abutalabs.com/products/python-greenlet-greenlet
Language: C++
License: NOASSERTION
License Family: other
Last push: 2026-08-10T13:23:22+00:00

## Health v2 (maintenance only)
Score: 76/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 97, release rhythm 35, longevity 100
- inputs: {"age_days": 5373, "days_push": 23, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: no_releases, no_license
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1840, forks 272 (observed 2026-08-28T04:05:42.993335+00:00)

## What it is
Greenlet is a C extension for CPython providing lightweight in-process coroutines (micro-threads) with no implicit scheduling. It lets developers build custom control flow structures and is the foundation for libraries like Gevent and Eventlet.

## Use cases
- run cooperative coroutines in-process without OS threads
- build custom schedulers or micro-thread frameworks
- implement generators that yield from nested function calls
- power concurrent networking libraries like gevent or eventlet
- switch execution contexts explicitly for advanced control flow

## When to choose
- you need fine-grained, explicit control over coroutine switching
- you're building or using cooperative concurrency libraries like gevent
- you want lightweight concurrency without implicit scheduling overhead

## When to avoid
- you only need simple async/await, which modern Python supports natively
- you need true parallelism across CPU cores
- you want implicit scheduling of tasks rather than manual switching

## Facets
- artifact type: library
- maturity: stable
- function: concurrency
- domain: developer-tools, backend
- platform: python, cross-platform
- tags: coroutines, micro-threads, c-extension, cooperative-scheduling

## Member repositories
- python-greenlet/greenlet (main) score 76

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:05:42.993335+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T03:18:05.171213+00:00, confidence not recorded.
  - readme: https://github.com/python-greenlet/greenlet (fetched 2026-08-28T04:05:42.993335+00:00, sha 33cb67dad2ab)
- Data as of 2026-08-30T08:39:29.467469+00:00.