[Engineering] [Ops] Changes to SWAT deployment policies, effective Monday April 30th

Fri Apr 27 19:00:35 UTC 2018

On Fri, Apr 27, 2018 at 7:05 PM, Niharika Kohli <nkohli at wikimedia.org>
wrote:

> Also, I think dropping the limit to 4 patches per window is extreme,
> especially if we are asking people to start splitting their patches now.
> Very often we can +2 multiple patches in one go if they don't affect each
> other, or sync out changes together if they happen to the same file. I've
> deployed 8 patches in a window often, with people asking if they can add
> more yet. Due to timezone limitations, most people can only attend one of
> the SWAT windows and if they can't get it out in that window, they have to
> wait a whole day or more to get it out.
>

FWIW, here are some stats on the patch counts for the first three months of
2018 (might contain errors, tried not to spend too much time on it):

EU mid: 8, 6, 2, 10, 1, 6, 1, 2, 1, 2, 2, 6, 2, 9, 6, 10, 2, 1, 1, 8, 7, 5,
5, 5, 2, 7, 6, 8, 4, 7, 4, 4, 4, 1, 1, 4, 3, 3, 2, 4, 4, 5, 5, 1
(average: 4.25, max of 2-week rolling average: 5.7)
Morning: 7, 1, 1, 5, 1, 3, 4, 1, 6, 3, 4, 3, 3, 5, 6, 4, 3, 5, 8, 4, 5, 4,
3, 0, 3, 1, 5, 9, 2, 1, 3
(average: 3.6, max of 2-week rolling average: 5)
Evening: 8, 1, 1, 1, 1, 3, 3, 2, 1, 3, 4, 2, 1, 1, 2, 1, 1, 5, 1, 6, 1, 3,
3, 1, 2, 3, 1, 0, 9, 10, 5, 4, 1, 6, 2, 1, 2, 4, 3
(average: 2.8, max of 2-week rolling average: 4.75)

ie. if the new policy was introduced at the start of the year, it would
have caused at least a two-week delay in all three SWAT windows at one
point at least, and it would have caused an ever-growing backlog of patches
for EU mid-day.
(That's without taking the split patch requirement into account, it's hard
to tell how many patches that would have affected.)
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