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/test_generator.py.
Greenlets are provided as a C extension module for the regular
Greenlets are lightweight coroutines for in-process concurrent
Who is using Greenlet?
There are several libraries that use Greenlet as a more flexible
alternative to Python’s built in coroutine support: