This is implement in an extremely hacky way due to poor DBIx feature
support. Ideally, what we'd need is a way to tell DBIx to ignore the
errormsg column unless explicitly requested, and to automatically add a
computed 'errormsg IS NULL' column in others. Since it does not support
that, this commit instead hacks some support via method overrides while
taking care to not break anything obvious.
When building e.g. nixpkgs, the "Running builds" view will mostly look
like this
hello.x86_64-linux (Build of hello-X.Y)
exa.x86_64-linux (Build of exa-X.Y)
...
This doesn't provide any useful information. Showing the step name only
makes sense if it's not a child of the job's derivation. With this
patch, that information will only be shown if the drv name (i.e. w/o
`/nix/store/` prefix, .drv ext & hash) is not equal to the drv name of
the job itself (build.nixname).
When using Hydra to build machine configurations, you'll often see
"nixosConfigurations.foo" five times, i.e. for each build step being
run. This isn't very helpful I think because in such a case, a single
build step can also be compiling the Linux kernel.
This change also fetches the `drvpath` and `type` from the `buildsteps`
relation. We're already joining it, so this doesn't make much difference
(confirmed via query logging that this doesn't cause extra SQL queries).
Unfortunately build steps don't have a human readable name, so I'm
deriving it from the drvpath by stripping away the hash (assuming that
it'll never contain a `-` and that `/nix/store/` is used as prefix). I
decided against using the Nix bindings for that to avoid too much
overhead due to store operations for each build step.
In 73694087a0 I gave builds that failed
because of a timeout or exceeded log limit a stop sign and I stand by
that reasoning: with that it's possible to distinguish between actual
build failures and rather transient things such as timeouts.
Back then I considered it a feature that these are shown in a different
tab, but I don't think that's a good idea anymore. When using a jobset to
e.g. track the regressions from a mass rebuild (like a compiler or gcc
update), "Newly failed builds" should exclusively display regressions (and
flaky builds of course, not much I can do about that).
Also, when a bunch of builds fail in such a jobset because of e.g. a
broken connection to a builder that results in a timeout, I want to be
able to restart them all w/o rebuilding actual regressions.
To make it clear that we not only have "Aborted" builds in the tab, I
renamed the label to "Aborted / Timed out".
This allows for better builder usage when the queue runner is busy. To
avoid running into uncontrollable imbalances between builder/queue
runner, we only release the machine reservation after the local
throttler has found a slot to start copying the outputs for that build.
We don't rely on sequential / monotonic build IDs processing anymore, so
randomizing actually has the advantage of mixing builds for different
systems together, to avoid only one chunk of builds for a single system
getting processed while builders for other systems are starved.
Each output for a given step being ingested is looked up in parallel,
which should basically multiply the speed of builds ingestion by the
average number of outputs per derivation.
Running the query with/without it shows that it makes no difference to
postgres, since there's an index on finished=0 already. This allows a
few simplifications, but also paves the way towards running multiple
parallel monitor threads in the future.
By looking at the ratio of running vs. waiting for the dispatcher and
the queue monitor, we should get better visibility into what hydra is
currently bottlenecked on.
There are other side effects we can try to measure to get to the same
result, but having a simple way doesn't cost us much.
My current theory is that running more parallel xz than available CPU
cores is reducing our overall throughput by requiring more scheduling
overhead and more cache thrashing.
