Open Stack

On Wed, Sep 17, 2014, at 06:37 PM, Matt Riedemann wrote:
> 
> 
> On 9/17/2014 7:59 PM, Ian Wienand wrote:
> > On 09/18/2014 09:49 AM, Clark Boylan wrote:
> >> Recent sampling of test run times shows that our tempest jobs run
> >> against clouds using PostgreSQL are significantly slower than jobs run
> >> against clouds using MySQL.
> >
> > FYI There is a possibly relevant review out for max_connections limits
> > [1], although it seems to have some issues with shmem usage
> >
> > -i
> >
> > [1] https://review.openstack.org/#/c/121952/
> >
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> >
> 
> That's a backport of a fix from master where we were hitting fatal 
> errors due to too many DB connections which was brought on by the 
> changes to cinder and glance to run as many workers as there were CPUs 
> available.  So I don't think it probably plays here...
> 
> The errors pointed out in another part of the thread have been around 
> for awhile, I think they are due to negative tests where we're hitting 
> unique constraints because of the negative tests, so they are expected.
> 
> We should also note that the postgresql jobs run with the nova metadata 
> API service, I'm not sure how much of a factor that would have here.
> 
> Is there anything else unique about those jobs from the MySQL ones?
>
Good question. There are apparently other differences. The postgres job
runs Keystone under eventlet instead of via apache mod_wsgi. It also
sets FORCE_CONFIGDRIVE=False instead of always. And the final difference
I can find is the one you point out, nova api metadata service is run as
an independent thing.

Could these things be related? It would be relatively simple to push a
change or two to devstack-gate to test this but there are enough options
here that I probably won't do that until we think at least one of these
options is at fault.
> 
> -- 
> 
> Thanks,
> 
> Matt Riedemann
> 
> 
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