Open Stack

FSM +1

https://blueprints.launchpad.net/glance/+spec/image-status-global-state-machine

btw, I remember I had posted this information in your change as a
review comment, which is a simple state validation mechanism in image
domain object and already been merged.

thanks,
zhiyan


On Mon, Jan 27, 2014 at 8:37 AM, David Koo <kpublicmail at gmail.com> wrote:
>
>> Perhaps there is still a bug where an image is getting stuck in 'saving' or
>> some other state when a PUT fails?
>
>     Yes, that's precisely the problem.
>
>     Of course, one could argue that that if an upload fails the user
> should be able to continue trying until the upload succeeds! But in that
> case the image status should probably be reset to "queued" rather than
> stay at "saving".
>
>     But this makes me a little uneasy because our
> consistency/concurrency handling seems a little weak at the moment (am I
> right?). If we were to have a more complicated state machine then we
> would need much stronger consistency guarantees when there are
> simultaneous uploads in progress (where some fail and some succeed)!
>
>     Is there any work on this (concurrency/consistency) front? I
> remember seeing some patches related to caching of simultaneous
> downloads of an image file where issues related to concurrent update of
> image metadata were addressed but IIRC it was -1ed because it reduced
> concurrency.
>
>     So do we bring back the 'killed' state or should we shoot for a more
> complicated/powerful state machine?
>
> --
> Koo
>
>
> On Sun, Jan 26, 2014 at 06:36:36AM -0800, Mark Washenberger wrote:
>> It does not seem very ReSTful--or very usable, for that matter--for a
>> resource to be permanently modified when you a PUT fails. So I don't think
>> we need the 'killed' status. It was purposefully left out of v2 images,
>> which is not just a reskin of v1.
>>
>> Perhaps there is still a bug where an image is getting stuck in 'saving' or
>> some other state when a PUT fails?
>>
>>
>> On Sun, Jan 26, 2014 at 5:10 AM, David Koo <kpublicmail at gmail.com> wrote:
>>
>> >
>> > Hi Fei,
>> >
>> >     Thanks for the confirmation.
>> >
>> > > I think you're right. The 'killed' status should be set in method
>> > upload()
>> > > if there is an upload failure, see
>> > >
>> > https://github.com/openstack/glance/blob/master/glance/common/utils.py#L244
>> >
>> > I think you meant:
>> >
>> >
>> > https://github.com/openstack/glance/blob/master/glance/api/v1/upload_utils.py#L244
>> >
>> > (the safe_kill() call) right?
>> >
>> > --
>> > Koo
>> >
>> >
>> > > ------------------ Original ------------------
>> > > From:  "David Koo"<kpublicmail at gmail.com>;
>> > > Date:  Jan 26, 2014
>> > > To:  "OpenStack Development Mailing
>> > > List"<openstack-dev at lists.openstack.org>;
>> > > Subject:  [openstack-dev] [Glance] Is the 'killed' state ever set in v2?
>> > >
>> > > Hi All,
>> > >
>> > > While trying to work on a bug I was trying to simulate some image
>> > > download failures and found that apparently the 'killed' state is never
>> > > set using v2 APIs.
>> > >
>> > > If I understand correctly, a file upload goes to
>> > > api.v2.image_data.ImageDataController.upload and goes all the way to
>> > > store.ImageProxy.set_data which proceeds to write to the backend store.
>> > >
>> > > If the backend store raises an exception it is simply propagated all the
>> > > way up. The notifier re-encodes the exceptions (which is the bug I was
>> > > looking at) but doesn't do anything about the image status.
>> > >
>> > > Nowhere does the image status seem to get set to 'killed'.
>> > >
>> > > Before I log a bug I just wanted to confirm with everybody whether or
>> > > not I've missed out on something.
>> > >
>> > > Thanks.
>> > >
>> > > --
>> > > Koo
>> >
>> > _______________________________________________
>> > OpenStack-dev mailing list
>> > OpenStack-dev at lists.openstack.org
>> > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
>> >
>
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