Cisco Nexus: maximum recursion error in ConnectionContext.__del__

[Dane LeBlanc]

If DevStack is configured for the Cisco Nexus plugin with the latest DevStack, the following
infinite recursion error is observed:
Exception RuntimeError: 'maximum recursion depth exceeded' in <bound method
ConnectionContext.__del__ of <neutron.openstack.common.rpc.amqp.ConnectionContext
object at 0x403a3d0>> ignored

An investigation shows that this failure triggered when the DB base plugin's
_is_native_pagination_supported method is called. The infinite recursion begins
when this exception is raised:

             raise AttributeError(
                 _("'%(model)s' object has no attribute '%(name)s'") %
                {'model': self._model, 'name': name})

in the PluginV2.__getattr__ method in
neutron/plugins/cisco/network_plugin.py. The problem is that self._model
object is being % mod'd as a string in the unicode message, and this
causes many levels of recursion into deepcopy (a deepcopy for all objects
embedded in this object).

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/80737

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/80737
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=c36ddaf930ba309be3c127dc1836f28a8ab97c5d
Submitter: Jenkins
Branch: master

commit c36ddaf930ba309be3c127dc1836f28a8ab97c5d
Author: Dane LeBlanc <email address hidden>
Date: Fri Mar 14 20:32:10 2014 -0400

    Cisco Nexus: maximum recursion error in ConnectionContext.__del__

    If DevStack is configured for the Cisco Nexus plugin, the following
    error is observed:

    Exception RuntimeError: 'maximum recursion depth exceeded' in <bound
    method ConnectionContext.__del__ of
    <neutron.openstack.common.rpc.amqp.ConnectionContext object at
    0x403a3d0>> ignored

    The root cause of the problem is that the Cisco Nexus plugin's
    PluginV2.__gettattr__ method, a model object is being passed
    as a value for a unicode %s format mod. Because the neutron server
    has "lazy gettext" (deferred interpretation of unicode objects) enabled,
    this causes many layers of recursive calls to deepcopy.

    The fix is to pass a string object for the unicode %s mod field.

    Change-Id: I0a07a0ab417add68e44cb1bca722cb0b4a71205b
    Closes-Bug: #1286565