.. currentmodule:: tango

Green mode
==========

PyTango supports cooperative green Tango objects. Since version 8.1 two *green*
modes have been added: :obj:`~tango.GreenMode.Futures` and
:obj:`~tango.GreenMode.Gevent`. In version 9.2.0 another one has been
added: :obj:`~tango.GreenMode.Asyncio`.

The :obj:`~tango.GreenMode.Futures` uses the standard python module
:mod:`concurrent.futures`.
The :obj:`~tango.GreenMode.Gevent` mode uses the well known gevent_ library.
The newest, :obj:`~tango.GreenMode.Asyncio` mode, uses asyncio_ - a Python
library for asynchronous programming (it's featured as a part of a standard
Python distribution since version 3.5 of Python; it's available on PyPI for
older ones).

You can set the PyTango green mode at a global level. Set the environment
variable :envvar:`PYTANGO_GREEN_MODE` to either *futures*, *gevent* or *asyncio*
(case insensitive). If this environment variable is not defined the PyTango
global green mode defaults to *Synchronous*.

.. include:: green_modes_client.rst

.. include:: green_modes_server.rst
