[openstack-dev] [nova] Need more suggestion about nova-scheduler patch/147048

Rui Chen chenrui.momo at gmail.com
Fri Apr 24 03:25:12 UTC 2015


Hi all:

    I'm working on the patch https://review.openstack.org/#/c/147048/ for
bug/1408859

    Description of Bug:
    When the nova-scheduler can't select enough hosts for multiple creating
instance, a NoValidHost exception was raised, but the part of hosts had
been consumed from instance in the _schedule loop, the resource of consumed
hosts was not reverted, it would result in the resource lacking in
nova-scheduler.

    But now I'm in a dilemma, because the reviewers have different point
about implementation of the patch, so I need more feedback.

    See patch set 36
    This is simple way, just set the 'updated' attribute of consumed host
as None, and make use of the 'update_from_compute_node' logic to update the
local HostState at the next scheduling request.

http://git.openstack.org/cgit/openstack/nova/tree/nova/scheduler/host_manager.py#n185

    But like John say, it would break CachingScheduler in a refresh cycle,
the resource of HostState would been fixed until the next periodic_tasks is
executed.

    Other side, Alex and Sylvain think that it should be acceptable,
because CachingSheduler use the out of date HostState in the cache
according to the design, and the usage limitation had been described in
class notes.

    I'm really really hope this patch can been merged ASAP, it has spent
several months to review :(

    Please let me know your point, feel free to discuss it, thanks.

Best Regards.
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