[openstack-dev] [elastic-recheck] Thoughts on next steps

Sean Dague sean at dague.net
Fri Jan 3 02:29:50 UTC 2014

A lot of elastic recheck this fall has been based on the ad hoc needs of 
the moment, in between diving down into the race bugs that were 
uncovered by it. This week away from it all helped provide a little 
perspective on what I think we need to do to call it *done* (i.e. 
something akin to a 1.0 even though we are CDing it).

Here is my current thinking on the next major things that should happen. 
Opinions welcomed.

(These are roughly in implementation order based on urgency)

= Split of web UI =

The elastic recheck page is becoming a mismash of what was needed at the 
time. I think what we really have emerging is:
  * Overall Gate Health
  * Known (to ER) Bugs
  * Unknown (to ER) Bugs - more below

I think the landing page should be Know Bugs, as that's where we want 
both bug hunters to go to prioritize things, as well as where people 
looking for known bugs should start.

I think the overall Gate Health graphs should move to the zuul status 
page. Possibly as part of the collection of graphs at the bottom.

We should have a secondary page (maybe column?) of the un-fingerprinted 
recheck bugs, largely to use as candidates for fingerprinting. This will 
let us eventually take over /recheck.

= Data Analysis / Graphs =

I spent a bunch of time playing with pandas over break 
(http://dague.net/2013/12/30/ipython-notebook-experiments/), it's kind 
of awesome. It also made me rethink our approach to handling the data.

I think the rolling average approach we were taking is more precise than 
accurate. As these are statistical events they really need error bars. 
Because when we have a quiet night, and 1 job fails at 6am in the 
morning, the 100% failure rate it reflects in grenade needs to be 
quantified that it was 1 of 1, not 50 of 50.

So my feeling is we should move away from the point graphs we have, and 
present these as weekly and daily failure rates (with graphs and error 
bars). And slice those per job. My suggestion is that we do the actual 
visualization with matplotlib because it's super easy to output that 
from pandas data sets.

Basically we'll be mining Elastic Search -> Pandas TimeSeries -> 
transforms and analysis -> output tables and graphs. This is different 
enough from our current jquery graphing that I want to get ACKs before 
doing a bunch of work here and finding out people don't like it in reviews.

Also in this process upgrade the metadata that we provide for each of 
those bugs so it's a little more clear what you are looking at.

= Take over of /recheck =

There is still a bunch of useful data coming in on "recheck bug ####" 
data which hasn't been curated into ER queries. I think the right thing 
to do is treat these as a work queue of bugs we should be building 
patterns out of (or completely invalidating). I've got a preliminary 
gerrit bulk query piece of code that does this, which would remove the 
need of the daemon the way that's currently happening. The gerrit 
queries are a little long right now, but I think if we are only doing 
this on hourly cron, the additional load will be negligible.

This would get us into a single view, which I think would be more 
informative than the one we currently have.

= Categorize all the jobs =

We need a bit of refactoring to let us comment on all the jobs (not just 
tempest ones). Basically we assumed pep8 and docs don't fail in the gate 
at the beginning. Turns out they do, and are good indicators of infra / 
external factor bugs. They are a part of the story so we should put them in.

= Multi Line Fingerprints =

We've definitely found bugs where we never had a really satisfying 
single line match, but we had some great matches if we could do multi line.

We could do that in ER, however it will mean giving up logstash as our 
UI, because those queries can't be done in logstash. So in order to do 
this we'll really need to implement some tools - cli minimum, which will 
let us easily test a bug. A custom web UI might be in order as well, 
though that's going to be it's own chunk of work, that we'll need more 
volunteers for.

This would put us in a place where we should have all the infrastructure 
to track 90% of the race conditions, and talk about them in certainty as 
1%, 5%, 0.1% bugs.


Sean Dague
Samsung Research America
sean at dague.net / sean.dague at samsung.com

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