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<div class="moz-cite-prefix">Le 04/03/2015 04:51, Rui Chen a écrit :<br>
</div>
<blockquote
cite="mid:CABHH=5BxGjjcuxW9N4W9=XhWy6gE1tk=G2sdLGDYuqCjxaTxtQ@mail.gmail.com"
type="cite">
<div dir="ltr">Hi all,
<div><br>
</div>
<div>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.</div>
<div><br>
</div>
<div>I had registered a blueprint and commit a patch to
implement it.</div>
<div><a moz-do-not-send="true"
href="https://blueprints.launchpad.net/nova/+spec/scheduler-multiple-workers-support">https://blueprints.launchpad.net/nova/+spec/scheduler-multiple-workers-support</a><br>
</div>
<div><br>
</div>
<div>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.</div>
<div><br>
</div>
<div>IMO, nova-scheduler should been scaled horizontally on
easily way, the multiple workers should been supported as an
out of box feature.</div>
<div><br>
</div>
<div>Please feel free to discuss this feature, thanks.</div>
</div>
</blockquote>
<br>
<br>
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.<br>
<br>
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.<br>
<br>
<br>
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.<br>
<br>
-Sylvain<br>
<br>
[1]
<a class="moz-txt-link-freetext" href="http://specs.openstack.org/openstack/nova-specs/specs/kilo/approved/resource-objects.html">http://specs.openstack.org/openstack/nova-specs/specs/kilo/approved/resource-objects.html</a><br>
<blockquote
cite="mid:CABHH=5BxGjjcuxW9N4W9=XhWy6gE1tk=G2sdLGDYuqCjxaTxtQ@mail.gmail.com"
type="cite">
<div dir="ltr">
<div><br>
</div>
<div>Best Regards</div>
<div><br>
</div>
</div>
<br>
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