Merge "Eventlet monkey patching should be as early as possible"

doc/source/conf.py

@@ -160,6 +160,14 @@ openstack_projects = [
 ]
 # -- Custom extensions --------------------------------------------------------
 
+# NOTE(mdbooth): (2019-03-20) Sphinx loads policies defined in setup.cfg, which
+# includes the placement policy at nova/api/openstack/placement/policies.py.
+# Loading this imports nova/api/openstack/__init__.py, which imports
+# nova.monkey_patch, which will do eventlet monkey patching to the sphinx
+# process. As well as being unnecessary and a bad idea, this breaks on
+# python3.6 (but not python3.7), so don't do that.
+os.environ['OS_NOVA_DISABLE_EVENTLET_PATCHING'] = '1'
+
 
 def monkey_patch_blockdiag():
     """Monkey patch the blockdiag library.

nova/__init__.py

@@ -22,14 +22,3 @@
    :platform: Unix
    :synopsis: Infrastructure-as-a-Service Cloud platform.
 """
-
-import os
-
-os.environ['EVENTLET_NO_GREENDNS'] = 'yes'
-
-# NOTE(rpodolyaka): import oslo_service first, so that it makes eventlet hub
-# use a monotonic clock to avoid issues with drifts of system time (see
-# LP 1510234 for details)
-import oslo_service  # noqa
-
-import eventlet  # noqa

nova/api/openstack/__init__.py

@@ -17,6 +17,7 @@
 """
 WSGI middleware for OpenStack API controllers.
 """
+import nova.monkey_patch  # noqa
 
 from oslo_log import log as logging
 import routes

nova/api/openstack/wsgi_app.py

@@ -23,13 +23,11 @@ from nova import context
 from nova import exception
 from nova import objects
 from nova import service
-from nova import utils
 
 CONF = cfg.CONF
 
 CONFIG_FILES = ['api-paste.ini', 'nova.conf']
 
-utils.monkey_patch()
 objects.register_all()
 
 

nova/cmd/__init__.py

@@ -1,4 +1,4 @@
-# Copyright (c) 2013 Hewlett-Packard Development Company, L.P.
+# Copyright (c) 2019 Red Hat, Inc.
 # All Rights Reserved.
 #
 # Licensed under the Apache License, Version 2.0 (the "License"); you may
@@ -13,6 +13,4 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
-from nova import utils
-
-utils.monkey_patch()
+import nova.monkey_patch  # noqa

nova/monkey_patch.py

@@ -0,0 +1,97 @@
+# Copyright 2010 United States Government as represented by the
+# Administrator of the National Aeronautics and Space Administration.
+# Copyright 2011 Justin Santa Barbara
+# Copyright 2019 Red Hat, Inc.
+# All Rights Reserved.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+"""Enable eventlet monkey patching."""
+
+import os
+
+
+def _monkey_patch():
+    # NOTE(mdbooth): Anything imported here will not be monkey patched. It is
+    # important to take care not to import anything here which requires monkey
+    # patching.
+    import eventlet
+    import sys
+
+    # NOTE(mdbooth): Imports only sys (2019-01-30). Other modules imported at
+    # runtime on execution of debugger.init().
+    from nova import debugger
+
+    # Note any modules with known monkey-patching issues which have been
+    # imported before monkey patching.
+    # urllib3: https://bugs.launchpad.net/nova/+bug/1808951
+    # oslo_context.context: https://bugs.launchpad.net/nova/+bug/1773102
+    problems = (set(['urllib3', 'oslo_context.context']) &
+                set(sys.modules.keys()))
+
+    # See https://bugs.launchpad.net/nova/+bug/1164822
+    # TODO(mdbooth): This feature was deprecated and removed in eventlet at
+    # some point but brought back in version 0.21.0, presumably because some
+    # users still required it to work round issues. However, there have been a
+    # number of greendns fixes in eventlet since then. Specifically, it looks
+    # as though the originally reported IPv6 issue may have been fixed in
+    # version 0.24.0. We should remove this when we can confirm that the
+    # original issue is fixed.
+    os.environ['EVENTLET_NO_GREENDNS'] = 'yes'
+
+    if debugger.enabled():
+        # turn off thread patching to enable the remote debugger
+        eventlet.monkey_patch(thread=False)
+    elif os.name == 'nt':
+        # for nova-compute running on Windows(Hyper-v)
+        # pipes don't support non-blocking I/O
+        eventlet.monkey_patch(os=False)
+    else:
+        eventlet.monkey_patch()
+
+    # NOTE(rpodolyaka): import oslo_service first, so that it makes eventlet
+    # hub use a monotonic clock to avoid issues with drifts of system time (see
+    # LP 1510234 for details)
+    # NOTE(mdbooth): This was fixed in eventlet 0.21.0. Remove when bumping
+    # eventlet version.
+    import oslo_service  # noqa
+    eventlet.hubs.use_hub("oslo_service:service_hub")
+
+    # NOTE(mdbooth): Log here instead of earlier to avoid loading oslo logging
+    # before monkey patching.
+    # NOTE(mdbooth): Ideally we would raise an exception here, as this is
+    # likely to cause problems when executing nova code. However, some non-nova
+    # tools load nova only to extract metadata and do not execute it. Two
+    # examples are oslopolicy-policy-generator and sphinx, both of which can
+    # fail if we assert here. It is not ideal that these utilities are monkey
+    # patching at all, but we should not break them.
+    # TODO(mdbooth): If there is any way to reliably determine if we are being
+    # loaded in that kind of context without breaking existing callers, we
+    # should do it and bypass monkey patching here entirely.
+    if problems:
+        from oslo_log import log as logging
+
+        LOG = logging.getLogger(__name__)
+        LOG.warning("Modules with known eventlet monkey patching issues were "
+                    "imported prior to eventlet monkey patching: %s. This "
+                    "warning can usually be ignored if the caller is only "
+                    "importing and not executing nova code.",
+                    ', '.join(problems))
+
+# NOTE(mdbooth): This workaround is required to avoid breaking sphinx. See
+# separate comment in doc/source/conf.py. It may also be useful for other
+# non-nova utilities. Ideally the requirement for this workaround will be
+# removed as soon as possible, so do not rely on, or extend it.
+if (os.environ.get('OS_NOVA_DISABLE_EVENTLET_PATCHING', '').lower()
+        not in ('1', 'true', 'yes')):
+    _monkey_patch()

nova/test.py

@@ -21,8 +21,7 @@ inline callbacks.
 
 """
 
-import eventlet  # noqa
-eventlet.monkey_patch()
+import nova.monkey_patch  # noqa
 
 import abc
 import copy

nova/tests/functional/__init__.py

@@ -20,6 +20,4 @@
    :platform: Unix
 """
 
-import eventlet
-
-eventlet.monkey_patch()
+import nova.monkey_patch  # noqa

nova/utils.py

@@ -49,10 +49,8 @@ from oslo_utils import timeutils
 from oslo_utils import units
 import six
 from six.moves import range
-from six.moves import reload_module
 
 import nova.conf
-from nova import debugger
 from nova import exception
 from nova.i18n import _, _LE, _LI, _LW
 import nova.network
@@ -1293,25 +1291,6 @@ def generate_hostid(host, project_id):
     return ""
 
 
-def monkey_patch():
-    if debugger.enabled():
-        # turn off thread patching to enable the remote debugger
-        eventlet.monkey_patch(thread=False)
-    elif os.name == 'nt':
-        # for nova-compute running on Windows(Hyper-v)
-        # pipes don't support non-blocking I/O
-        eventlet.monkey_patch(os=False)
-    else:
-        eventlet.monkey_patch()
-
-    # NOTE(rgerganov): oslo.context is storing a global thread-local variable
-    # which keeps the request context for the current thread. If oslo.context
-    # is imported before calling monkey_patch(), then this thread-local won't
-    # be green. To workaround this, reload the module after calling
-    # monkey_patch()
-    reload_module(importutils.import_module('oslo_context.context'))
-
-
 if six.PY2:
     nested_contexts = contextlib.nested
 else: