[eventlet-deprecation] The method ``eventlet.monkey_patch()`` is called more than once

[Rodolfo Alonso]

If the method ``eventlet.monkey_patch()`` is called more than once, because of [1], present in eventlet 0.37.0, the existing RLocks are upgraded. This leads to an issue in the oslo.messaging library with using ``threading.Condition()``, based on RLock.

Error log: https://paste.opendev.org/show/bwb1L0WAhKAODIWyiep1/

[1]https://github.com/eventlet/eventlet/commit/06ec82896ebb9a26edaf6e1ad4d63393990f15b7

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/c/openstack/neutron/+/937527

[OpenStack Infra (hudson-openstack)]

Related fix proposed to branch: master
Review: https://review.opendev.org/c/openstack/neutron/+/937535

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/openstack/neutron/+/937527
Committed: https://opendev.org/openstack/neutron/commit/bedb19bb220664329597fc222d820df7ccbdca46
Submitter: "Zuul (22348)"
Branch: master

commit bedb19bb220664329597fc222d820df7ccbdca46
Author: Rodolfo Alonso Hernandez <email address hidden>
Date: Wed Dec 11 10:08:36 2024 +0000

    Prevent calling "monkey_patch" more than once

    This patch is adding a check to prevent calling
    ``eventlet.monkey_patch()`` more than once per execution.

    This patch is also preventing any import before this method has been
    called. Any import is moved after that.

    Closes-Bug: #2091538
    Topic: eventlet-deprecation
    Change-Id: I675aaf124d6630b6827febb1e5a5f492ed874107

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/openstack/neutron/+/937535
Committed: https://opendev.org/openstack/neutron/commit/5ee7ac1261cb5cfa4b51dfd899f682d7e628ceae
Submitter: "Zuul (22348)"
Branch: master

commit 5ee7ac1261cb5cfa4b51dfd899f682d7e628ceae
Author: Rodolfo Alonso Hernandez <email address hidden>
Date: Wed Dec 11 14:08:30 2024 +0000

    Read the environment variable EVENTLET_MONKEYPATCH

    Since eventlet 0.39.0 [1] it is possible to you set an environment
    variable ``EVENTLET_MONKEYPATCH=1`` to get patching as early as
    possible in Python startup, which may avoid some problems.

    [1]https://github.com/eventlet/eventlet/commit/b754135b045306022a537b5797f2cb2cf47ba49b

    Related-Bug: #2091538
    Topic: eventlet-deprecation
    Change-Id: I928e32ea736bdb3357fdbb1de6646e69db3159d7