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.
There were some hangs caused by this. Need to fix them, ideally
reproducing the issue in a test, before trying this again.
This reverts commit 4a4a0f901c70676ee47f830d2ff6a72789ba1baf.
This avoids some duplicated code, leveraging the same `StoreReference`
type that also undergirds the machine file dedup we just did prior.
By using `LegacySSHStoreConfig`, we're also taking a baby step towards
using the store interface rather than messing around with the protocol
internals.
Original commit message:
> There are some known regressions regarding local testing setups - since
> everything was kinda half written with the expectation that build dir =
> source dir (which should not be true anymore). But everything builds and
> the test suite runs fine, after several hours spent debugging random
> crashes in libpqxx with MALLOC_PERTURB_...
I have not experienced regressions with local testing.
(cherry picked from commit 4b886d9c45cd2d7fe9b0a8dbc05c7318d46f615d)
With https://github.com/NixOS/nix/pull/9839, the `storeUri` field is
much better structured, so we can use it while still opening the SSH
connection ourselves.
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.
Implements support for Nix's new Perl bindings[1]. The current state
basically does `openStore()`, but always uses `auto` and doesn't support
stores at other URIs.
Even though the stores are cached inside the Perl implementation, I
decided to instantiate those once in the Nix helper module. That way
store openings aren't cluttered across the entire codebase. Also, there
are two stores used later on - MACHINE_LOCAL_STORE for `auto`,
BINARY_CACHE_STORE for the one from `store_uri` in `hydra.conf` - and
using consistent names should make the intent clearer then.
This doesn't contain any behavioral changes, i.e. the build product
availability issue from #1352 isn't fixed. This patch only contains the
migration to the new API.
[1] https://github.com/NixOS/nix/pull/9863
We have to oddly make a `StoreConfig` subclass to get it, but
https://github.com/NixOS/nix/pull/9848 will fix that.
The purpose of this is to ensure that, absent an explicit config,
`localhost` includes `ca-derivations` and `recursive-nix` if those
experimental features are enabled.
Very much the complement of #1342, the previous PR.
A slight dedup, and also ensures that floating CA derivations require a
`ca-derivations` experimental feature. This fixes the scheduling issue
that @SuperSandro2000 found.
This is *just* using the fields from that type, and only where the types
coincide. (There are two fields with different types, `speedFactor` most
interestingly.) No code is reused, so we can be sure that no behavior is
changed.
Once the types are reconciled on the Nix side, then we can start
carefully actually reusing code.
Progress on #1164
- Use the type itself
This lays the foundation for being able to dedup the protocol code.
- Use `BasicConnection::handshake`, replacing ours.
- Use `BasicConnection::queryValidPaths`
- Use `BasicConnection::putBuildDerivationRequest`
