forked from openkylin/python-greenlet
62 lines
2.2 KiB
ReStructuredText
62 lines
2.2 KiB
ReStructuredText
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.. This file is included into docs/history.rst
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.. image:: https://github.com/python-greenlet/greenlet/workflows/tests/badge.svg
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:target: https://github.com/python-greenlet/greenlet/actions
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Greenlets are lightweight coroutines for in-process concurrent
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programming.
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The "greenlet" package is a spin-off of `Stackless`_, a version of
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CPython that supports micro-threads called "tasklets". Tasklets run
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pseudo-concurrently (typically in a single or a few OS-level threads)
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and are synchronized with data exchanges on "channels".
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A "greenlet", on the other hand, is a still more primitive notion of
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micro-thread with no implicit scheduling; coroutines, in other words.
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This is useful when you want to control exactly when your code runs.
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You can build custom scheduled micro-threads on top of greenlet;
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however, it seems that greenlets are useful on their own as a way to
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make advanced control flow structures. For example, we can recreate
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generators; the difference with Python's own generators is that our
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generators can call nested functions and the nested functions can
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yield values too. (Additionally, you don't need a "yield" keyword. See
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the example in `test_generator.py
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<https://github.com/python-greenlet/greenlet/blob/adca19bf1f287b3395896a8f41f3f4fd1797fdc7/src/greenlet/tests/test_generator.py#L1>`_).
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Greenlets are provided as a C extension module for the regular unmodified
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interpreter.
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.. _`Stackless`: http://www.stackless.com
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Who is using Greenlet?
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======================
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There are several libraries that use Greenlet as a more flexible
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alternative to Python's built in coroutine support:
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- `Concurrence`_
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- `Eventlet`_
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- `Gevent`_
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.. _Concurrence: http://opensource.hyves.org/concurrence/
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.. _Eventlet: http://eventlet.net/
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.. _Gevent: http://www.gevent.org/
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Getting Greenlet
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================
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The easiest way to get Greenlet is to install it with pip::
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pip install greenlet
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Source code archives and binary distributions are vailable on the
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python package index at https://pypi.org/project/greenlet
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The source code repository is hosted on github:
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https://github.com/python-greenlet/greenlet
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Documentation is available on readthedocs.org:
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https://greenlet.readthedocs.io
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