nicktrn
fa7eea39d8
## Summary Projects that configure their own `metricExporters` or `metricReaders` in `trigger.config.ts` were losing task metrics on nearly every run, and seeing an unexplained `Failed to flush tracingSDK` alongside `OTLPExporterError: Bad Request` in their run logs. Spans and logs kept working, so the runs otherwise looked healthy. ## Root cause and fix Every configured exporter gets its own `PeriodicExportingMetricReader`, and `meterProvider.forceFlush()` fans out across all readers with `Promise.all`, so two collections can land on the same millisecond. `@opentelemetry/host-metrics` divides by the elapsed interval to compute `process.cpu.utilization` ([common.ts](https://github.com/open-telemetry/opentelemetry-js-contrib/blob/main/packages/host-metrics/src/stats/common.ts)), so a zero interval yields `0/0`. `JSON.stringify(NaN)` is `null`, and a collector rejects `"asDouble": null` with a 400 that drops the **entire** request, not just the offending point. `flush()` and `shutdown()` now walk the metric readers one at a time, so collections can no longer share a timestamp. Each reader is isolated, so one failing reader cannot skip the readers behind it, and every failure is logged with the reader that produced it. The first error is still rethrown, so callers see failures exactly as before. As a second layer, non-finite data points are dropped just before our own export, so a metric that divides by zero cannot take the rest of the batch with it. Exporters and readers supplied through `trigger.config.ts` are untouched by that filter and still receive raw data. The trade-off is that configured exporters now flush after the built-in one rather than alongside it, so flush latency is the sum rather than the max. An internal test package's dependency on core was replaced with a local helper, because core now needs that package in `devDependencies` and the two together formed a workspace cycle. ## Verification Tested against a real collector in a container: a batch containing a `NaN` reading is rejected with a 400 without the fix and accepted with it, and a single flush is asserted to collect from one reader at a time.
Test containers
Vitest utilities for writing tests against real Postgres, Prisma, Redis and ClickHouse - we don't mock
(see the root CLAUDE.md), we boot containers. Also exposes a duration-weighted shard sequencer for
splitting slow suites across CI shards.
Choosing a fixture
Most tests share one set of containers per vitest worker (booted once, reset between tests) - this is much faster than a container per test. Reach for an isolated variant only when a test needs it.
| Fixture | Postgres | Redis | ClickHouse | Use for |
|---|---|---|---|---|
redisTest |
- | shared | - | redis-only tests |
postgresTest |
shared (clone) | - | - | db-only tests |
containerTest |
shared (clone) | shared | shared | the default - needs all three |
isolatedRedisTest |
- | per-test | - | background redis work (see below) |
containerTestWithIsolatedRedis |
shared (clone) | per-test | shared | background redis work + db/clickhouse |
replicationContainerTest |
per-test | per-test | shared | Postgres→ClickHouse logical replication |
"shared (clone)" = one Postgres per worker with a template database; each test gets a fast CREATE DATABASE ... TEMPLATE clone, so schema isn't re-pushed per test.
The background-work gotcha
If a test spawns work that outlives the test body - a RunEngine, a redis-worker Worker, a
BatchQueue - and that work isn't fully drained before the test ends, you must use an isolated
redis fixture (isolatedRedisTest / containerTestWithIsolatedRedis).
On the shared fixture, the leaked background loop keeps polling the one worker-scoped redis after the
test's clients close, bleeding into the next test. The symptom is an intermittent "Connection is closed" error or a test that hangs until its timeout. FLUSHALL between tests does not fix this -
it clears data, not live connections/loops, so per-test key prefixes won't help either. A plain
db/redis test with no lingering background work is fine on the shared fixtures.
Sharding (./sequencer)
CI splits the slow suites with vitest --shard=i/N. DurationShardingSequencer replaces vitest's
default file-count split with a duration-weighted one: it reads test-timings.json at the repo root
({ "<repo-relative path>": <ms> }) and greedily bin-packs files so each shard does roughly equal
work, not an equal number of files. The packing is deterministic, so every shard computes the same
bins and runs each file exactly once.
Configs opt in via:
import { DurationShardingSequencer } from "@internal/testcontainers/sequencer";
// in defineConfig:
test: {
sequence: {
sequencer: DurationShardingSequencer,
},
}
Adding tests - nothing to do
New test files are discovered by vitest's glob and sharded automatically. A file with no entry in
test-timings.json is given the median duration as a fallback, so it's still placed on exactly one
shard - correctness never depends on the timings being present or current.
What the timings affect is balance. A new heavy test estimated at the median can be under-weighted and land on an already-full shard, making that shard slower. There's headroom between the current makespan and the CI budget to absorb this, so it tolerates drift - but if a shard creeps toward the budget, refresh the timings.
Refreshing test-timings.json
Measure each shard with the JSON reporter and write per-file endTime - startTime (ms), keyed by
repo-relative path, back into test-timings.json. Set GITHUB_ACTIONS=true so suites that
skipIf(CI) are excluded, matching what actually runs on CI:
GITHUB_ACTIONS=true pnpm exec vitest run --reporter=json --outputFile=/tmp/run.json
Stale entries for deleted/renamed files are harmless (they're simply ignored). This is a periodic chore, not a per-PR one.