Le 04/03/2015 04:51, Rui Chen a écrit :
Hi all,
I want to make it easy to launch a bunch of scheduler processes on a
host, multiple scheduler workers will make use of multiple processors
of host and enhance the performance of nova-scheduler.
I had registered a blueprint and commit a patch to implement it.
https://blueprints.launchpad.net/nova/+spec/scheduler-multiple-workers-support
This patch had applied in our performance environment and pass some
test cases, like: concurrent booting multiple instances, currently we
didn't find inconsistent issue.
IMO, nova-scheduler should been scaled horizontally on easily way, the
multiple workers should been supported as an out of box feature.
Please feel free to discuss this feature, thanks.
As I said when reviewing your patch, I think the problem is not just
making sure that the scheduler is thread-safe, it's more about how the
Scheduler is accounting resources and providing a retry if those
consumed resources are higher than what's available.
Here, the main problem is that two workers can actually consume two
distinct resources on the same HostState object. In that case, the
HostState object is decremented by the number of taken resources (modulo
what means a resource which is not an Integer...) for both, but nowhere
in that section, it does check that it overrides the resource usage. As
I said, it's not just about decorating a semaphore, it's more about
rethinking how the Scheduler is managing its resources.
That's why I'm -1 on your patch until [1] gets merged. Once this BP will
be implemented, we will have a set of classes for managing heterogeneous
types of resouces and consume them, so it would be quite easy to provide
a check against them in the consume_from_instance() method.
-Sylvain
[1]
http://specs.openstack.org/openstack/nova-specs/specs/kilo/approved/resource-objects.html
Best Regards
__________________________________________________________________________
OpenStack Development Mailing List (not for usage questions)
Unsubscribe: openstack-dev-requ...@lists.openstack.org?subject:unsubscribe
http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
__________________________________________________________________________
OpenStack Development Mailing List (not for usage questions)
Unsubscribe: openstack-dev-requ...@lists.openstack.org?subject:unsubscribe
http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
