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Re: Performance diagnosis of metadata query
Well, there are diablo-stable packages. If Ubuntu, Debian, Red Hat,
etc. keep hearing from customers that Essex in an LTS release is not
adequate, there will be essex-stable packages too. They are the ones who
have to stand behind the product. It is perfectly understandable that
there is resistance to putting anything other than fixes for critical
bugs in a week or so from release. I am not saying this is great, but
if release dates are fixed and features, performance the things that are
allowed to vary, then what else is there to do? Just my opinion.
On 3/29/2012 1:55 PM, Justin Santa Barbara wrote:
I'm not saying it can't be rationalized; I'm saying it is frustrating
My understanding is that Essex is going to be baked into both Ubuntu &
Debian for the long term - 5 years plus. That's a long time to have
to keep explaining why X is broken; I'd rather just fix X.
On Thu, Mar 29, 2012 at 10:22 AM, David Kranz <david.kranz@xxxxxxxxxx
On 3/29/2012 12:46 PM, Justin Santa Barbara wrote:
Is there a good way to map back where in the code these calls
are coming from?
There's not a great way currently. I'm trying to get a patch in
for Essex which will let deployments easily turn on SQL debugging
(though this is proving contentious); it will have a configurable
log level to allow for future improvements, and one of the things
I'd like to do is add later is something like a stack trace on
'problematic' SQL (large row count, long query time). But
that'll be in Folsom, or in G if we don't get logging into Essex.
In the meantime, it's probably not too hard to follow the code
and infer where the calls are coming from. In the full log,
there's a bit more context, and I've probably snipped some of
that out; in this case the relevant code is get_metadata in the
compute API service and get_instance_nw_info in the network service.
Regardless, large table scans should be eliminated,
especially if the table is mostly read, as the hit on an
extra index on insert will be completely offset by the
speedups on select.
Agreed - some of these problems are very clear-cut!
It does frustrate me that we've done so much programming work,
but then not do the simple stuff at the end to make things work
well. It feels a bit like shipping we're shipping C code which
we've compiled with -O0 instead of -O3.
Well, in a project with the style of fixed-date release
(short-duration train-model) that openstack has, I think we have
to accept that there will never be time to do anything except
fight critical bugs "at the end". At least not until the project
code is much more mature. In projects I have managed we always
allocated time at the *beginning* of a release cycle for fixing
some backlogged bugs and performance work. There is less pressure
and the code is not yet churning. It is also important to have
performance benchmark tests to make sure new features do not
introduce performance regressions.
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