[oslo][nova][stable][requirements] Fixing a high CPU usage from oslo.service into stable/rocky branch
hberaud at redhat.com
Thu Nov 22 08:36:45 UTC 2018
I'm waiting for a consensus between us to update my reviews if needed or
abandon them in the case we choose an another approach.
Le jeu. 22 nov. 2018 à 09:31, Herve Beraud <hberaud at redhat.com> a écrit :
> Le jeu. 22 nov. 2018 à 05:55, Tony Breeds <tony at bakeyournoodle.com> a
> écrit :
>> HI folks,
>> I admit my initial response to this was mor pragmatic 'take the
>> bakport' but as I thought it through I saw more problems with that
>> On Wed, Nov 21, 2018 at 03:47:25PM +0100, Herve Beraud wrote:
>> > Since these changes was introduced into oslo.service master, nova facing
>> > some issues into the master CI process, due to the threading changes,
>> > they was fixed by these patches (
>> > https://review.openstack.org/#/c/617989/ ) into master.
>> > Few weeks ago I have backport to oslo.service some changes (
>> > https://review.openstack.org/#/c/614489/ ) from master to stable/rocky
>> > also fix the problem in the rocky release.
>> Okay that was a mistake, backporting a patch from master to stable that
>> is known to break consumers, I admit this isn't explicitly called out in
>> the stable policy but it is kind of the spirit of the stable policy.
>> The quickest fix would be to revert 614489, release 1.31.7 and blacklist
>> Yes this leaves the High CPU usage bug open on rocky. That isn't great
>> but it also isn't terrible.
>> > When this backport was merged we have created a new release of
>> > (1.31.6) ( https://review.openstack.org/#/c/616505/ ) (stable/rocky
>> > version).
>> > Then the openstack proposal bot submit a patch to requirements on stable
>> > rocky to update the oslo.service version with the latest version
>> > but if we'll use it we'll then break the CI
>> > https://review.openstack.org/#/c/618834/ so this patch is currently
>> > to avoid nova CI error.
>> Huzzah for cross-project gateing!
>> > # Issue
>> > Since the oslo.services threading changes were backported to rocky we
>> > to faces the same issues inside the nova rocky CI if we update the
>> > requirements.
>> > In parallel in oslo.service we have started to backport a new patch who
>> > introduces fixture ( https://review.openstack.org/#/c/617989/ ) from
>> > master to rocky, and also we start to backport on nova rocky branch (
>> > https://review.openstack.org/619019,
>> https://review.openstack.org/619022 )
>> > patches who use oslo.service.fixture and who solve the nova CI issue.
>> > patch on oslo.service exposes a public oslo_service.fixture.SleepFixture
>> > for this purpose. It can be maintained opaquely as internals change
>> > affecting its consumers.
>> > The main problem is that the patch bring a new functionality to a stable
>> > branch (oslo.service rocky) but this patch help to fix the nova issue.
>> > Also openstack proposal bot submit a patch to requirements on stable
>> > to update the oslo.service version with the latest version (1.31.6) but
>> > we'll use it we'll then break the CI
>> > https://review.openstack.org/#/c/618834/ since the oslo service 1.31.6
>> > incompatible with novas stable rocky unittest due to the threading
>> > # Questions and proposed solutions
>> > This thread try to summarize the current situation.
>> > We need to find how to be able to proceed, so this thread aim to allow
>> > discuss between team to find the best way to fix.
>> > 1. Do we need to continue to try to backport fixture on oslo.service to
>> > the CI problem (https://review.openstack.org/#/c/617989/) ?
>> Doing this is a violation of the stable policy. I get that the new
>> feature is just a testing only fixture but that doesn't really matter
>> it's still a feature. To use it consumers would need to raise
>> the value for oslo.service in lower-constraints.txt which is a policy
>> The is an additional complication that this backport adds fixtures to
>> requirements.txt for oslo.service, at the very least this would mean
>> we're into a minor semver bump (1.32.X, which is already taken). This
>> also means the vendors need to ensure that there is a 'fixtures' package
>> available. Now I expect that all packagers have such a thing but there
>> is a small chance that it exists as a build only package and needs to be
>> exposed/published. We're previously said to vendors we wouldn't do that
>> on stable branches.
> I agree this solution come with a minor bump and issues to keep the semver
>> > 2. Do we need to find an another approach like mocking
>> > oslo.service.loopingcall._Event.wait in nova instead of mocking
>> > oslo_service.loopingcall._ThreadingEvent.wait (example:
>> > ?
>> > This is only a fix on the nova side and it allows us to update
>> > requirements and allows us to fix the high CPU usage issue. I've submit
>> > this patch (https://review.openstack.org/619246) who implement the
>> > description above.
>> > Personaly I think we need to find an another approach like the mocking
>> > remplacement (c.f 2).
>> > We need to decide which way we use and to discuss about other solutions.
>> I think the only way forward is the revert, release and block path. The
>> existing open reviews just add more policy violations.
>> Yours Tony.
> Hervé Beraud
> Senior Software Engineer
> Red Hat - Openstack Oslo
> irc: hberaud
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Senior Software Engineer
Red Hat - Openstack Oslo
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