Open Stack

On 11/15/13 at 07:57pm, Isaku Yamahata wrote:
>On Tue, Nov 12, 2013 at 03:07:19PM -0500,
>Andrew Laski <andrew.laski at rackspace.com> wrote:
>
>> On 11/11/13 at 05:27pm, Jiang, Yunhong wrote:
>> >Resend after the HK summit, hope someone can give me hint on it.
>> >
>> >Thanks
>> >--jyh
>> >
>> >>-----Original Message-----
>> >>From: Jiang, Yunhong [mailto:yunhong.jiang at intel.com]
>> >>Sent: Thursday, November 07, 2013 5:39 PM
>> >>To: openstack-dev at lists.openstack.org
>> >>Subject: [openstack-dev] [nova][api] Is this a potential issue
>> >>
>> >>Hi, all
>> >>	I'm a bit confused of followed code in ./compute/api.py, which will be
>> >>invoked by api/openstack/compute/servers.py, _action_revert_resize().
>> >>	From the code seems there is a small windows between get the
>> >>migration object and update migration.status. If another API request
>> >>comes at this small window, it means two utility will try to revert resize at
>> >>same time. Is this a potential issue?
>> >>	Currently implementation already roll back the reservation if
>> >>something wrong, but not sure if we should update state to "reverting" as
>> >>a transaction in get_by_instance_and_status()?
>>
>> The migration shouldn't end up being set to 'reverting' twice
>> because of the expected_task_state set and check in
>> instance.save(expected_task_state=None).  The quota reservation
>> could happen twice, so a rollback in the case of a failure in
>> instance.save could be good.
>
>nova.objects.instance.Intance.save() seems like that expected_task_state=None
>means don't care of task state instead of no-task going-on.
>Am I missing anything?

You're not missing anything.  But I think that's a bug, or at least an 
unexpected change in behaviour from how it used to work.  If you follow 
instance_update() in nova.db.sqlalchemy.api just the presence of 
expected_task_state triggers the check.  So we may need to find a way to 
pass that through with the save method.

>
>thanks,
>
>
>>
>> >>
>> >>--jyh
>> >>
>> >>    def revert_resize(self, context, instance):
>> >>        """Reverts a resize, deleting the 'new' instance in the process."""
>> >>        elevated = context.elevated()
>> >>        migration =
>> >>migration_obj.Migration.get_by_instance_and_status(
>> >>            elevated, instance.uuid, 'finished')
>> >>	>>>>>>>>>>>>>>>>>>>>>>Here we get the migration object
>> >>
>> >>        # reverse quota reservation for increased resource usage
>> >>        deltas = self._reverse_upsize_quota_delta(context, migration)
>> >>        reservations = self._reserve_quota_delta(context, deltas)
>> >>
>> >>        instance.task_state = task_states.RESIZE_REVERTING
>> >>        instance.save(expected_task_state=None)
>> >>
>> >>        migration.status = 'reverting'			>>>>>>>>>>>>>>Here
>> >>we update the status.
>> >>        migration.save()
>> >>
>> >>_______________________________________________
>> >>OpenStack-dev mailing list
>> >>OpenStack-dev at lists.openstack.org
>> >>http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
>> >
>> >_______________________________________________
>> >OpenStack-dev mailing list
>> >OpenStack-dev at lists.openstack.org
>> >http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
>>
>> _______________________________________________
>> OpenStack-dev mailing list
>> OpenStack-dev at lists.openstack.org
>> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
>
>-- 
>Isaku Yamahata <isaku.yamahata at gmail.com>
>
>_______________________________________________
>OpenStack-dev mailing list
>OpenStack-dev at lists.openstack.org
>http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev