(kafka) branch 4.1 updated: KAFKA-19452: Fix flaky test LogRecoveryTest.testHWCheckpointWithFailuresMultipleLogSegments (#20121)

[ch...@apache.org]

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chia7712 pushed a commit to branch 4.1
in repository https://gitbox.apache.org/repos/asf/kafka.git


The following commit(s) were added to refs/heads/4.1 by this push:
     new eb11f06904c KAFKA-19452: Fix flaky test LogRecoveryTest.testHWCheckpointWithFailuresMultipleLogSegments (#20121)
eb11f06904c is described below

commit eb11f06904ca28991cb2209bc9c7cce125d36654
Author: Rajani K <ka...@users.noreply.github.com>
AuthorDate: Mon Jul 14 22:12:00 2025 +0530

    KAFKA-19452: Fix flaky test LogRecoveryTest.testHWCheckpointWithFailuresMultipleLogSegments (#20121)
    
    The `testHWCheckpointWithFailuresMultipleLogSegments` test in
    `LogRecoveryTest` was failing intermittently due to a race condition
    during its failure simulation.
    
    In successful runs, the follower broker would restart and rejoin the
    In-Sync Replica (ISR) set before the old leader's failure was fully
    processed. This allowed for a clean and timely leader election to the
    now in-sync follower.
    
    However, in the failing runs, the follower did not rejoin the ISR before
    the leader election was triggered. With no replicas in the ISR and
    unclean leader election disabled by default for the test, the controller
    correctly refused to elect a new leader, causing the test to time out.
    
    This commit fixes the flakiness by overriding the controller
    configuration for this test to explicitly enable unclean leader
    election. This allows the out-of-sync replica to be promoted to leader,
    making the test deterministic and stable.
    
    Reviewers: Jun Rao <ju...@gmail.com>
---
 core/src/test/scala/unit/kafka/server/LogRecoveryTest.scala | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/core/src/test/scala/unit/kafka/server/LogRecoveryTest.scala b/core/src/test/scala/unit/kafka/server/LogRecoveryTest.scala
index 6e2f3073ba1..a01d9cb554e 100755
--- a/core/src/test/scala/unit/kafka/server/LogRecoveryTest.scala
+++ b/core/src/test/scala/unit/kafka/server/LogRecoveryTest.scala
@@ -64,6 +64,16 @@ class LogRecoveryTest extends QuorumTestHarness {
   def hwFile2 = new OffsetCheckpointFile(new File(configProps2.logDirs.get(0), ReplicaManager.HighWatermarkFilename), null)
   var servers = Seq.empty[KafkaBroker]
 
+  // testHWCheckpointWithFailuresMultipleLogSegments simulates broker failures that can leave the only available replica out of the
+  // ISR. By enabling unclean leader election, we ensure that the test can proceed and elect
+  // the out-of-sync replica as the new leader, which is necessary to validate the log
+  // recovery and high-watermark checkpointing logic under these specific failure conditions.
+  override def kraftControllerConfigs(testInfo: TestInfo): Seq[Properties] = {
+    val properties = new Properties()
+    properties.put(ReplicationConfigs.UNCLEAN_LEADER_ELECTION_ENABLE_CONFIG, "true")
+    Seq(properties)
+  }
+
   // Some tests restart the brokers then produce more data. But since test brokers use random ports, we need
   // to use a new producer that knows the new ports
   def updateProducer(): Unit = {