<div dir="ltr">I think most of these discussions are readily agreed upon, but that sending a broad email like this is unlikely to reach the right people/result in action.<br><br>At least for the try bots stuff - finding the owner of that system, and seeing if it can be made to not put that notice in the emails.<br><br>Yes, the buildbot configuration is intended not to send mail on already-red. If you're seeing those, specifically looking at which bot/configuration, and fixing the configuration - that shouldn't be a per-bot issue, but a buildbot server configuration that's broken in some way.<br><br>Slow builders - yeah, I'm up for having an upper bound on size of a blame list. I wonder if that could be implemented in the buildbot config itself - if the blame list is over a certain size, just don't send mail. That way we don't even have to classify bots - move them between groups if they become slower/faster - makes it easier for bot owners to fix the issue themselves - allocate more compute resources (faster system, or multiple systems running in parallel) and it'll naturally start sending fail-mail. But that does still leave the duplicate and very delayed results - slow builder with lots of machines dedicated could have small blame lists but still produce an answer hours later, possibly just redundant with some faster builder - hence a staged system would be much nicer instead of or in addition to.<br><br>A staged building system would be great, but requires a bunch of work to build that no one's signed up to do as yet. I don't think anyone would object to such a thing being implemented. (Apple internally had/has a system that uses a staged build system that reused the build product of earlier builds, even - so like a baseline builder, then other builders that can consume that build to run stage 2 and another that consume the build to run test-suite, etc - so less duplicate, more throughput, and less noise - was hoping that's what the greendragon stuff would become, but doesn't seem like it has)</div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Thu, Sep 9, 2021 at 3:18 PM Philip Reames via llvm-dev <<a href="mailto:llvm-dev@lists.llvm.org">llvm-dev@lists.llvm.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div>
<p>I've been noticing a trend where there is more and more false
positive email notifications sent out on valid commits. This is
getting really problematic as real signal is being lost in the
noise. I've had several cases in the last few weeks where I did
not see a "real" failure notice because it was buried in a bunch
of false positives. </p>
<p>Let me run through a few sources of what I consider false
positives, and suggest a couple things we could do to clean these
up. Note that the recommendations here are entirely independent
and we can adopt any subset.</p>
<p><b>Slow Try Bots</b></p>
<p>ex: "This revision was landed with ongoing or failed builds." on
<a href="https://reviews.llvm.org/D109091" target="_blank">https://reviews.llvm.org/D109091</a></p>
<p>Someone - I'm not really sure who - enabled builds for all
reviews, and this notice on landed commits. Given it's utterly
routine to make a last few style fixes before landing an LGTMed
change, I consider this notice complete noise. In practice,
almost review gets tagged this way. To be clear, there is value
in being told about changes which don't build. The false positive
part is only around the "ongoing" builds.</p>
<p>Recommendation: Disable this message for the "ongoing" build
case, and if we can't, disable them entirely. <br>
</p>
<p><b>Flaky Builders</b></p>
<p>ex: <a href="https://lab.llvm.org/buildbot/#/builders/68/builds/18250" target="_blank">https://lab.llvm.org/buildbot/#/builders/68/builds/18250</a></p>
<p>We have many build bots which are not entirely stable. It's
gotten to the point where I *expect* failure notifications on
literally every change I land. I've been trying to reach out to
individual build bot owners to get issues resolved, and to their
credit, most owners have been very responsive. However, we have
enough builders that the situation isn't getting meaningful
better.</p>
<p>Recommendation: Introduce specific "test commits" whose only
purpose is to run the CI infrastructure. Any builder which
notifies of failure on such a commit (and only said commit) is
disabled without discussion until human action is taken by the bot
owner to re-enable. The idea here is to a) automate the process,
and b) shift the responsibility of action to the bot owner for any
flaky bot. <br>
</p>
<p>Note: By "disabled", I specifically mean that *notification* is
disabled. Leaving it in the waterfall view is fine, as long as
we're not sending out email about it. <br>
</p>
<p>Aside: It's really tempting to attempt to separate builders which
are "still failing" (e.g. a rare configuration which has been
broken for a few days) from "flaky" ones. I'd argue any bot
notifying on a "still failing" case is buggy, and thus it's fine
to treat them the same as a "flaky" bot. <br>
</p>
<p><b>Slow Builders and Redundant Notices<br>
</b></p>
<p>ex: <a href="https://lab.llvm.org/buildbot#builders/67/builds/4128" target="_blank">https://lab.llvm.org/buildbot#builders/67/builds/4128</a></p>
<p>Occasionally, we have a bad commit land which breaks every (or
nearly every) builder. That happens. If you happen to land a
change just before or after it, you then get on the blame list for
every slow running builder we have (since they tend to have large
commit windows) if they happen to cycle before the fix is
committed. This is particularly annoying since the root issue is
likely fixed quickly, but due to cycle times on the builders, you
may be getting emails for 24 hours to come. <br>
</p>
<p>Recommendation: Introduce a new requirement for "slow" builders
(say cycle time of > 30 minutes) either a) have a maximum
commit window of ~15 commits, or b) use a staged builder model.
Personally, I'd prefer the staged model, but the max commit window
at least helps to limit the damage. <br>
</p>
<p>By "staged builder model", I mean that slow builders only build
points in the history which have already been successfully build
by one of the fast builders. This eliminates redundant build
failures, at the cost of delaying the slow builder slightly. As
long as the slow builder uses the "last good commit" as opposed to
waiting until the current fast builder finishes, the delay should
be very minimal for most commits. <br>
</p>
<p>Philip<br>
</p>
</div>
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