FrankChen021 opened a new issue, #20478:
URL: https://github.com/apache/druid/issues/20478
_This issue was generated automatically by Claude Code (Anthropic's AI
coding agent) running a scheduled CI-triage routine on behalf of @FrankChen021.
Analysis and suggested fixes are AI-produced; please verify before acting on
them._
**Status:** Open: no fix PR
**Subject:** `EmbeddedKafkaSupervisorTest.test_runKafkaSupervisor`,
`EmbeddedKafkaSupervisorTest.test_runSupervisor_withEmptyDimension`
(extensions-core/kafka-indexing-service, `unit tests (25, E*,G*,F*)`)
**Failures:** 0 (3 passed on retry) · **First seen:** 2026-10-01 · **Last
seen:** 2026-10-02
Tracked although every occurrence so far passed on retry: the flake recurs
daily, each surefire rerun restarts an embedded cluster (~30 s added to the
job), and the fix is test-only.
### Root cause
- **`test_runKafkaSupervisor` line 125 (`expected: <1> but was: <2>`):** the
supervisor uses `taskDuration=PT0.5S`, but the test asserts exactly one active
task about 1 s after the first task starts. In job 110571049503 the first task
started at 20:52:35.758, its duration expired at 36.800 (end offsets set, task
still active while publishing), a second task was created at 36.859, and the
test listed tasks at 36.951 and saw two. Because the test fails before
suspending its supervisor, that supervisor keeps rolling over tasks for the
rest of the class.
- **`test_runSupervisor_withEmptyDimension` line 210 (timeout) / line 219
(`expected: <100> but was: <83>`):** with `maxRowsPerSegment=1` and one row per
day, the 100 rows create 100 one-row segments. The test waits on
`ingest/events/processed`, but the class does not set
`druid.monitoring.emissionPeriod` (default `PT1M`), so the task emits that
metric only from `removeMonitor` when it exits, which happens after 100 segment
handoffs. In job 110571049503 all 100 rows were read by +4.7 s, but only 77
segments had loaded on the Historical when the 10 s wait expired, while the
leaked supervisor from the failed test above competed for the same Indexer and
Historical. The passing rerun took 7.97 s, so the margin is thin even without
contention. The line 219 variant is the same slow handoff, observed by the
row-count query.
None of the commits involved touch the Kafka indexing service.
### Suggested fix
Test-only changes in `EmbeddedKafkaSupervisorTest`: (1) assert that at least
one task exists and that all are `RUNNING` instead of exactly one; (2) add an
`@AfterEach` that suspends or terminates the test's supervisor so one failure
cannot slow the next test; (3) set
`indexer.addProperty("druid.monitoring.emissionPeriod", "PT0.1s")` (as
`KafkaClusterMetricsTest` does) and drop `maxRowsPerSegment(1)` for
`test_runSupervisor_withEmptyDimension`, which only needs to verify
empty-dimension handling.
### Occurrences
Failed push-triggered master jobs only. The daily triage routine adds one
row per new failed job.
| Date | Commit | Job | Failure log | Detail | Reported in |
|---|---|---|---|---|---|
| 2026-10-01 | 631f05de5d (#20458) | `unit tests (25, E*,G*,F*)` | [job
110375258572](https://github.com/apache/druid/actions/runs/36864118185/job/110375258572)
| `test_runSupervisor_withEmptyDimension`:219 expected 100 rows but was 83; 1
of 2 attempts failed (passed on retry) | #20437 |
| 2026-10-02 | e855cd9c33 (#20448) | `unit tests (25, E*,G*,F*)` | [job
110571049503](https://github.com/apache/druid/actions/runs/36922298311/job/110571049503)
| `test_runKafkaSupervisor`:125 expected 1 task but was 2; 1 of 2 attempts
failed (passed on retry) | #20437 |
| 2026-10-02 | e855cd9c33 (#20448) | `unit tests (25, E*,G*,F*)` | [job
110571049503](https://github.com/apache/druid/actions/runs/36922298311/job/110571049503)
| `test_runSupervisor_withEmptyDimension`:210 timed out after 10 s waiting for
`ingest/events/processed`; 1 of 2 attempts failed (passed on retry) | #20437 |
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