C. Scott Andreas created CASSANDRA-21497:
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Summary: Flaky test: Reproducible failing seed in
PlacementsChangeListenerTest#testPlacementChange
Key: CASSANDRA-21497
URL: https://issues.apache.org/jira/browse/CASSANDRA-21497
Project: Apache Cassandra
Issue Type: Bug
Components: Transactional Cluster Metadata
Reporter: C. Scott Andreas
On trunk at {{{}1332e217{}}},
{{PlacementsChangeListenerTest#testPlacementChange}} fails intermittently with
"Conflicting replica added (expected unique endpoints)".
testPlacementChange builds random placements with
OwnershipUtils.randomPlacements, then for each range removes the first write
replica and adds a replica for endpoint .99 at that range.
randomPlacements assigns replicas via MembershipUtils.randomEndpoint, which
returns 127.0.0.[1..254]. Endpoint .99 is inside that domain, so a range's
write group can already contain it; removing a different replica and then
adding endpoint 99 produces a duplicate, and EndpointsForRange.Builder rejects
it.
The seed is System.nanoTime(), so the failure appears at a low rate. A search
over 200,000 seeds reproduced it on 2,447 of them (about 1.2%).
The current test adds a full replica at endpoint .99:
`Replica add = Replica.fullReplica(MembershipUtils.endpoint(99),
remove.range());`
Either excluding .99 from the domain selected for other replicas; or
restricting the domain such that a valid address exists above the domain could
be reasonable approaches to prevent the flake.
To reproduce this failure locally, seed OwnershipUtils#randomPlacements with
j.u.Random(135L):
{{DataPlacements before = OwnershipUtils.randomPlacements(new
java.util.Random(135L)).withLastModified(e);}}
Then run: {{ant test -Dtest.name=PlacementsChangeListenerTest}}
The test will fail with:
{{testPlacementChange errors with java.lang.IllegalArgumentException:
Conflicting replica added (expected unique endpoints):
Full(/127.0.0.99:7000,...); existing: Full(/127.0.0.99:7000,...).}}
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