On 11/15/13 at 07:57pm, Isaku Yamahata wrote:
On Tue, Nov 12, 2013 at 03:07:19PM -0500,
Andrew Laski <andrew.la...@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.ji...@intel.com]
>>Sent: Thursday, November 07, 2013 5:39 PM
>>To: openstack-dev@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()
>>
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>
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--
Isaku Yamahata <isaku.yamah...@gmail.com>
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