[KAFKA-12949] TestRaftServer's scala.MatchError: null on test-kraft-server-start.sh

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 3.0.0
• Component/s: kraft
• Assignee: Ignacio Acuna
• Reporter: Ignacio Acuna
• Created: 15/Jun/21 00:14
• Updated: 22/Jun/21 19:15
• Resolved: 22/Jun/21 19:15

Description

Encounter the following exception when trying to run the TestRaftServer:

bin/test-kraft-server-start.sh --config config/kraft.properties

[2021-06-14 17:15:43,232] ERROR [raft-workload-generator]: Error due to (kafka.tools.TestRaftServer$RaftWorkloadGenerator)
 scala.MatchError: null
 at kafka.tools.TestRaftServer$RaftWorkloadGenerator.doWork(TestRaftServer.scala:220)
 at kafka.utils.ShutdownableThread.run(ShutdownableThread.scala:96)
 [2021-06-14 17:15:43,253] INFO [raft-workload-generator]: Stopped (kafka.tools.TestRaftServer$RaftWorkloadGenerator)

That happens on the followin match:

eventQueue.poll(eventTimeoutMs, TimeUnit.MILLISECONDS) match {
  case HandleClaim(epoch) =>
      claimedEpoch = Some(epoch)
      throttler.reset()
      pendingAppends.clear()
      recordCount.set(0)    
  case HandleResign =>
      claimedEpoch = None
      pendingAppends.clear()    case HandleCommit(reader) =>
      try {
        while (reader.hasNext) {
          val batch = reader.next()
          claimedEpoch.foreach { leaderEpoch =>
            handleLeaderCommit(leaderEpoch, batch)
          }
        }
      } finally {
        reader.close()
      }    
  case HandleSnapshot(reader) =>
      // Ignore snapshots; only interested in records appended by this leader
      reader.close()    
  case Shutdown => // Ignore shutdown command
}

Full log attached. When the eventQueue.poll returns null (if deque is empty), there isn't a case to match so the thread gets stuck and stops processing events (raft-workload-generator).

Proposal:
Add a case null to the match so the raft-workload-generator can continue.

Issue Links

• links to: GitHub Pull Request #10883