Image delete calls slow due to synchronous wait on backend store delete

[Nikhil Komawar]

Issue:-
-----------
Currently, the image delete calls can be very slow if the image being delete is large (consisting of multiple chunks esp. in case of swift) or if the backend store has slow response time.

Solution:-
-----------------
Make image delete call asynchronous

Specifically, for v1, call on this line https://github.com/openstack/glance/blob/master/glance/api/v1/images.py#L1012

and for v2, waiting on a fix for the bug https://bugs.launchpad.net/glance/+bug/1316233 to enable asynchronous deletion of image data from the store.

[Zhi Yan Liu (lzy-dev)]

IMO, for this case, end user should think about using delayed_delet function with scrubber service. It was just designed for this requirement.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/118459

[OpenStack Infra (hudson-openstack)]

Change abandoned by Jesse J. Cook (<email address hidden>) on branch: master
Review: https://review.openstack.org/118459
Reason: https://review.openstack.org/#/c/125156/

[Jesse J. Cook (jesse-j-cook)]

"""
IMO, for this case, end user should think about using delayed_delet function with scrubber service. It was just designed for this requirement.
"""

The scrubber does handle asynchronous deletes. However, there are some enhancements that could be done to make it a more viable option: https://review.openstack.org/#/c/125156/

This should probably be marked won't fix.