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Lightweight in-process concurrent programming
C Python C++ Assembly

Replace some tabs <-> spaces

This makes code look nice with any tab width.
It would be nice to get rid of tabs altogether,
but that would make git blame useless.
latest commit 3b92a856f5
@snaury snaury authored
Failed to load latest commit information.
benchmarks Remove unuseful while loop in benchmarks
doc Update greenlet.txt
platform arm32: slp_switch should save r10
tests expose ._stack_saved property
.gitignore ignore MANIFEST and .ropeproject
.travis.yml Enable automated testing with Python 3.4
AUTHORS Add Robie Basak to AUTHORS
LICENSE add copyright holders
LICENSE.PSF Attempt to clarify greenlet license update make-manifest and
NEWS Prepare to release 0.4.5
README.rst get rid of development version install instructions Don't symlink libraries unless inplace build is requested
greenlet.c Replace some tabs <-> spaces
greenlet.h Prepare to release 0.4.5
make-manifest update make-manifest and
make-win-release Nothing special needed when using VC++ for Python and setuptools Don't symlink libraries unless inplace build is requested Catch unit-test errors in
setup.cfg make sure sdist always creates a zip file Prepare to release 0.4.5
setup_switch_x64_masm.cmd make the greenlet module work on x64 windows
slp_platformselect.h Enable support for SunStudio on 32-bit SunOS
tox.ini add testenv:docs, which tests "make html" in doc directory


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 tests/

Greenlets are provided as a C extension module for the regular unmodified interpreter.

Greenlets are lightweight coroutines for in-process concurrent programming.

Who is using Greenlet?

There are several libraries that use Greenlet as a more flexible alternative to Python's built in coroutine support:

Getting Greenlet

The easiest way to get Greenlet is to install it with pip or easy_install:

pip install greenlet
easy_install greenlet

Source code archives and windows installers are available on the python package index at

The source code repository is hosted on github:

Documentation is available on

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