Instead of just going for "whatever is the oldest build we know of",
use the following first:
- Is the step more constrained? If so, schedule it first to avoid
filling up "more desirable" build slots with less constrained builds.
- Does the step have more dependents? If so, schedule it first to try
and maximize open parallelism and breadth of scheduling options.
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.
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.
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.
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".
Closes#1336
When restarting postgresql, the connections are still reused in
`hydra-queue-runner` causing errors like this
main thread: Lost connection to the database server.
queue monitor: Lost connection to the database server.
and no more builds being processed.
`hydra-evaluator` doesn't have that issue since it crashes right away.
We could let it retry indefinitely as well (see below), but I don't
want to change too much.
If the DB is still unreachable 10s later, the process will stop with a
non-zero exit code because of a missing DB connection. This however
isn't such a big deal because it will be immediately restarted
afterwards. With the current configuration, Hydra will never give up,
but restart (and retry) infinitely. To me that seems reasonable, i.e. to
retry DB connections on a long-running process. If this doesn't work
out, the monitoring should fire anyways because the queue fills up, but
I'm open to discuss that.
Please note that this isn't reproducible with the DB and the queue
runner on the same machine when using `services.hydra-dev`, because of
the `Requires=` dependency `hydra-queue-runner.service` ->
`hydra-init.service` -> `postgresql.service` that causes the queue
runner to be restarted on `systemctl restart postgresql`.
Internally, Hydra uses Nix's pool data structure: it basically has N
slots (here DB connections) and whenever a new one is requested, an idle
slot is provided or a new one is created (when N slots are active, it'll
be waited until one slot is free). The issue in the code here is however
that whenever an error is encountered, the slot is released, however the
same broken connection will be reused the next time. By using
`Pool::Handle::markBad`, Nix will drop a broken slot. This is now being
done when `pqxx::broken_connection` was caught.
It's a pet peeve from me when logging into my personal Hydra that I
always have to press the button rather than hitting Return after entering
my password.
Reason for that is that the form doesn't have a "submit" button, so far
it was always listened to the "click" event. Submit does that and you
can hit Return alternatively.
Closes#1336
When restarting postgresql, the connections are still reused in
`hydra-queue-runner` causing errors like this
main thread: Lost connection to the database server.
queue monitor: Lost connection to the database server.
and no more builds being processed.
`hydra-evaluator` doesn't have that issue since it crashes right away.
We could let it retry indefinitely as well (see below), but I don't
want to change too much.
If the DB is still unreachable 10s later, the process will stop with a
non-zero exit code because of a missing DB connection. This however
isn't such a big deal because it will be immediately restarted
afterwards. With the current configuration, Hydra will never give up,
but restart (and retry) infinitely. To me that seems reasonable, i.e. to
retry DB connections on a long-running process. If this doesn't work
out, the monitoring should fire anyways because the queue fills up, but
I'm open to discuss that.
Please note that this isn't reproducible with the DB and the queue
runner on the same machine when using `services.hydra-dev`, because of
the `Requires=` dependency `hydra-queue-runner.service` ->
`hydra-init.service` -> `postgresql.service` that causes the queue
runner to be restarted on `systemctl restart postgresql`.
Internally, Hydra uses Nix's pool data structure: it basically has N
slots (here DB connections) and whenever a new one is requested, an idle
slot is provided or a new one is created (when N slots are active, it'll
be waited until one slot is free). The issue in the code here is however
that whenever an error is encountered, the slot is released, however the
same broken connection will be reused the next time. By using
`Pool::Handle::markBad`, Nix will drop a broken slot. This is now being
done when `pqxx::broken_connection` was caught.
This was the source of a flaky test because sometimes hydra-notify was
quick enough to send out `buildStarted` and sometimes it apparently
wasn't which was quickly spottable with `nix build --rebuild`.
Removing that status update doesn't make a difference functionally,
gitea doesn't differentiate between "queued" and "running", so we send
the same status ("pending") out on both events, so we'd even safe one
avoidable request.
It's a pet peeve from me when logging into my personal Hydra that I
always have to press the button rather than hitting Return after entering
my password.
Reason for that is that the form doesn't have a "submit" button, so far
it was always listened to the "click" event. Submit does that and you
can hit Return alternatively.
This is an integration test that confirms that jobset definitions from
git repositories are correctly built and status updates pushed to the
gitea instance. The following things needed to be fixed:
* We're still on 23.05 where gitea is marked as insecure. Not going to
update nixpkgs right now, but going for the quick fix.
* Since gitea 1.19 tokens have scopes that describe what's possible.
Not specifying the scope in the DB appears to imply that no
permissions are granted.
* Apparently we have three status updates now (for three status hooks,
queued/started/finished). No idea why that was broken before, but the
behavior still looks correct.
In 1bd195a513 strictDeps was set for the
Hydra package. As a result, `checkInputs` aren't available anymore in
the local dev-shell which is the sole purpose of foreman, to start
services and a database for development.
In 5db374cb50 the `bootstrap` script was
removed, however it's still referenced in the contribution guidelines.
Change that to `autoreconfPhase` as intended by the commit.
This verison has a worse UI, but also chnages the schema less: One
non-null constraint is removed, but no new columns are added.
Co-Authored-By: Andrea Ciceri <andrea.ciceri@autistici.org>
Co-Authored-By: regnat <rg@regnat.ovh>
