Default native threading for sch, api and metadata

Code Issues Proposed changes

This patch switches the default concurrency mode to native threading
for the services that gained native threading support in Flamingo:
nova-scheduler, nova-api, and nova-metadata.
The OS_NOVA_DISABLE_EVENTLET_PATCHING env variable still can be used to
explicitly switch the concurrency mode to eventlet by
 OS_NOVA_DISABLE_EVENTLET_PATCHING=false
We also ensure that the cover, docs, py3xx and functional tox targets
are still running with eventlet while py312-threading kept running
with native threading.
Change-Id: I86c7f31f19ca3345218171f0abfa8ddd4f8fc7ea
Signed-off-by: Balazs Gibizer <gibi@redhat.com>

This commit is contained in:

Balazs Gibizer

2025年11月03日 13:25:55 +01:00

parent 0afb72e883

commit 35207ee8b5

8 changed files with 71 additions and 13 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

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17
doc/source/admin/concurrency.rst

View File

@@ -21,14 +21,21 @@ up support for the native threading mode.

Selecting concurrency mode for a service

----------------------------------------

Nova still uses Eventlet by default, but allows switching services to native

threading mode at service startup via setting the environment variable

``OS_NOVA_DISABLE_EVENTLET_PATCHING=true``.

Since nova 33.0.0 (2026.1 Gazpacho) the nova-scheduler, nova-api, and

nova-metadata are using native threading by default. The rest of the

services are using eventlet by default in this release. The concurrency mode

can be configured via setting the environment variable

``OS_NOVA_DISABLE_EVENTLET_PATCHING``. Setting that variable to ``true``

requests the native threading mode while setting it to ``false`` requests the

eventlet mode. If the variable is not set the above default is applied.

.. note::

Since nova 32.0.0 (2025.2 Flamingo) the nova-scheduler, nova-metadata,

nova-api, and nova-conductor can be switched to native threading mode.

Since nova 32.0.0 (2025.2 Flamingo) the nova-scheduler, nova-metadata, and

nova-api can be switched to native threading mode.

Since nova 33.0.0 (2026.1 Gazpacho) also the nova-conductor can be switched

to native threading mode.

Tunables for the native threading mode

2
nova/cmd/scheduler.py

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@@ -16,7 +16,7 @@

"""Starter script for Nova Scheduler."""

# autopep8: off

from nova import monkey_patch; monkey_patch.patch() # noqa

from nova import monkey_patch; monkey_patch.patch(backend='threading') # noqa

# autopep8: on

import sys

25
nova/monkey_patch.py

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@@ -72,10 +72,29 @@ def _monkey_patch():

return True

def patch():

if (os.environ.get('OS_NOVA_DISABLE_EVENTLET_PATCHING', '').lower()

not in ('1', 'true', 'yes')):

def patch(backend='eventlet'):

"""Apply eventlet monkey patching according to environment.

:param backend: Defines the default backend if not explicitly set via

the environment. If 'eventlet', then monkey patch if environment

variable is not defined. If 'threading', then do not monkey patch if

environment variable is not defined. Any other value results in a

ValueError. If the environment variable is defined this parameter

is ignored.

"""

if backend not in ('eventlet', 'threading'):

raise ValueError(

"the backend can only be 'eventlet' or 'threading'")

env = os.environ.get('OS_NOVA_DISABLE_EVENTLET_PATCHING', '').lower()

if env == '':

should_patch = (backend == 'eventlet')

elif env in ('1', 'true', 'yes'):

should_patch = False

else:

should_patch = True

if should_patch:

if _monkey_patch():

global MONKEY_PATCHED

MONKEY_PATCHED = True

14
nova/tests/unit/test_utils.py

View File

@@ -1691,3 +1691,17 @@ class OsloServiceBackendSelectionTestCase(test.NoDBTestCase):

"OS_NOVA_DISABLE_EVENTLET_PATCHING set to 'true', but then the "

"service tried to call eventlet.monkey_patch(). This is a bug.",

str(ex))

@mock.patch('oslo_service.backend.init_backend')

def test_threading_selected_by_default(self, init_backend):

with mock.patch.dict(os.environ):

del os.environ["OS_NOVA_DISABLE_EVENTLET_PATCHING"]

monkey_patch.patch(backend='threading')

init_backend.assert_called_once_with(

oslo_backend.BackendType.THREADING)

def test_invalid_default_backend(self):

ex = self.assertRaises(ValueError, monkey_patch.patch, backend='foo')

self.assertEqual(

"the backend can only be 'eventlet' or 'threading'", str(ex))

2
nova/wsgi/metadata.py

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@@ -12,7 +12,7 @@

"""WSGI application entry-point for Nova Metadata API."""

# autopep8: off

from nova import monkey_patch; monkey_patch.patch() # noqa

from nova import monkey_patch; monkey_patch.patch(backend='threading') # noqa

# autopep8: on

import threading

2
nova/wsgi/osapi_compute.py

View File

@@ -12,7 +12,7 @@

"""WSGI application entry-point for Nova Compute API."""

# autopep8: off

from nova import monkey_patch; monkey_patch.patch() # noqa

from nova import monkey_patch; monkey_patch.patch(backend='threading') # noqa

# autopep8: on

import threading

9
releasenotes/notes/threading-by-default-sch-api-meta-d2534ce9c7b69d8a.yaml Normal file

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@@ -0,0 +1,9 @@

---

features:

- |

The default concurrency mode is now switched from eventlet to native

threading for nova-scheduler, nova-api, and nova-metadata services.

The concurrency mode can still be switched back to eventlet if needed.

Please read the

`concurrency <https://docs.openstack.org/nova/latest/admin/concurrency.html>`__

guide for more details.

13
tox.ini

View File

@@ -56,12 +56,14 @@ commands =

env TEST_OSPROFILER=1 stestr run --combine --no-discover 'nova.tests.unit.test_profiler'

stestr slowest

[testenv:{unit,py3,py310,py311,py312}]

[testenv:{unit,py3,py310,py311,py312,py313}]

setenv =

{[testenv]setenv}

# we do not have any greenlet leaks in unit tests so enforce that

# by making greenlet leaks a failure.

NOVA_RAISE_ON_GREENLET_LEAK=True

# run the test with eventlet

OS_NOVA_DISABLE_EVENTLET_PATCHING=False

[testenv:py312-threading]

setenv =

@@ -81,7 +83,7 @@ commands =

stestr run {posargs} --exclude-list /tmp/exclude.txt

stestr slowest

[testenv:functional{,-py310,-py311,-py312}]

[testenv:functional{,-py310,-py311,-py312,-py313}]

description =

Run functional tests.

setenv =

@@ -89,6 +91,8 @@ setenv =

# we do not have any greenlet leaks in functional tests so enforce that

# by making greenlet leaks a failure.

NOVA_RAISE_ON_GREENLET_LEAK=True

# run the test with eventlet

OS_NOVA_DISABLE_EVENTLET_PATCHING=False

# As nova functional tests import the PlacementFixture from the placement

# repository these tests are, by default, set up to run with openstack-placement

# from pypi. In the gate, Zuul will use the installed version of placement (stable

@@ -208,6 +212,8 @@ commands =

setenv =

{[testenv]setenv}

PYTHON=coverage run --source nova --parallel-mode

# run the test with eventlet

OS_NOVA_DISABLE_EVENTLET_PATCHING=False

extras =

commands =

coverage erase

@@ -244,6 +250,9 @@ commands =

sphinx-build -W --keep-going -b html -j auto doc/source doc/build/html

# Test the redirects. This must run after the main docs build

whereto doc/build/html/.htaccess doc/test/redirect-tests.txt

setenv =

OS_NOVA_DISABLE_EVENTLET_PATCHING=False

[testenv:pdf-docs]

description =