Hi all,
In kilo (yeah I know it's an old release, but still :)), I was getting a nova
errors for DetachedInstanceError on instance.get_by_uuid().
2016-10-05 18:30:53.791 103618 ERROR nova.api.metadata.handler
[req-5aa7b422-d6c0-424e-b40f-cea79d3a3963 - - - - -] Failed to get metadata for
instance id: 859aba9c-7620-4cbf-a5aa-f6f29c320980
2016-10-05 18:30:53.791 103618 TRACE nova.api.metadata.handler Traceback (most
recent call last):
2016-10-05 18:30:53.791 103618 TRACE nova.api.metadata.handler File
"/usr/lib64/python2.7/site-packages/nova/api/metadata/handler.py", line 220, in
_handle_instance_id_request
2016-10-05 18:30:53.791 103618 TRACE nova.api.metadata.handler
remote_address)
2016-10-05 18:30:53.791 103618 TRACE nova.api.metadata.handler File
"/usr/lib64/python2.7/site-packages/nova/api/metadata/handler.py", line 106, in
get_metadata_by_instance_id
2016-10-05 18:30:53.791 103618 TRACE nova.api.metadata.handler instance_id,
address)
2016-10-05 18:30:53.791 103618 TRACE nova.api.metadata.handler File
"/usr/lib64/python2.7/site-packages/nova/api/metadata/base.py", line 531, in
get_metadata_by_instance_id
2016-10-05 18:30:53.791 103618 TRACE nova.api.metadata.handler instance =
objects.Instance.get_by_uuid(ctxt, instance_id)
2016-10-05 18:30:53.791 103618 TRACE nova.api.metadata.handler File
"/usr/lib64/python2.7/site-packages/nova/objects/base.py", line 163, in wrapper
2016-10-05 18:30:53.791 103618 TRACE nova.api.metadata.handler result =
fn(cls, context, *args, **kwargs)
2016-10-05 18:30:53.791 103618 TRACE nova.api.metadata.handler File
"/usr/lib64/python2.7/site-packages/nova/objects/instance.py", line 654, in
get_by_uuid
2016-10-05 18:30:53.791 103618 TRACE nova.api.metadata.handler
expected_attrs)
2016-10-05 18:30:53.791 103618 TRACE nova.api.metadata.handler File
"/usr/lib64/python2.7/site-packages/nova/objects/instance.py", line 608, in
_from_db_object
2016-10-05 18:30:53.791 103618 TRACE nova.api.metadata.handler
instance._maybe_migrate_flavor(db_inst, expected_attrs)
2016-10-05 18:30:53.791 103618 TRACE nova.api.metadata.handler File
"/usr/lib64/python2.7/site-packages/nova/objects/instance.py", line 535, in
_maybe_migrate_flavor
2016-10-05 18:30:53.791 103618 TRACE nova.api.metadata.handler if
instance_extra.get('flavor') is not None:
2016-10-05 18:30:53.791 103618 TRACE nova.api.metadata.handler File
"/usr/lib64/python2.7/site-packages/oslo_db/sqlalchemy/models.py", line 60, in
get
2016-10-05 18:30:53.791 103618 TRACE nova.api.metadata.handler return
getattr(self, key, default)
2016-10-05 18:30:53.791 103618 TRACE nova.api.metadata.handler File
"/usr/lib64/python2.7/site-packages/sqlalchemy/orm/attributes.py", line 239, in
__get__
2016-10-05 18:30:53.791 103618 TRACE nova.api.metadata.handler return
self.impl.get(instance_state(instance), dict_)
2016-10-05 18:30:53.791 103618 TRACE nova.api.metadata.handler File
"/usr/lib64/python2.7/site-packages/sqlalchemy/orm/attributes.py", line 591, in
get
2016-10-05 18:30:53.791 103618 TRACE nova.api.metadata.handler value =
self.callable_(state, passive)
2016-10-05 18:30:53.791 103618 TRACE nova.api.metadata.handler File
"/usr/lib64/python2.7/site-packages/sqlalchemy/orm/strategies.py", line 279, in
_load_for_state
2016-10-05 18:30:53.791 103618 TRACE nova.api.metadata.handler
(orm_util.state_str(state), self.key)
2016-10-05 18:30:53.791 103618 TRACE nova.api.metadata.handler
DetachedInstanceError: Parent instance is not
bound to a Session; deferred load operation of attribute 'flavor' cannot proceed
Now I've fixed it by adding a "joinedload" in the database query (in
instance_get_by_uuid()) on 'extra'.
So this fixes the issue, what I'd like to understand is why in most cases (like
99.9% of the time), the code was still working without the "joinedload" ? What
could explain that the children object was loaded but at some point dropped
from the session ?
I tried to reproduce the issue in mitaka (sorry didn't had a newton setup), but
it appears I can't reproduce it there ... I was hoping to reproduce it and
make sure there is no latent bug in nova.
Has anybody seen this issue before or something similar ?
Thanks for the help,
/ludovic
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