showuon commented on code in PR #15951:
URL: https://github.com/apache/kafka/pull/15951#discussion_r1601510877
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core/src/main/scala/kafka/server/ReplicaManager.scala:
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@@ -2114,19 +2114,16 @@ class ReplicaManager(val config: KafkaConfig,
partition.log.foreach { _ =>
val leader = BrokerEndPoint(config.brokerId, "localhost", -1)
- // Add future replica log to partition's map
- partition.createLogIfNotExists(
- isNew = false,
- isFutureReplica = true,
- offsetCheckpoints,
- topicIds(partition.topic))
-
- // pause cleaning for partitions that are being moved and start
ReplicaAlterDirThread to move
- // replica from source dir to destination dir
- logManager.abortAndPauseCleaning(topicPartition)
-
- futureReplicasAndInitialOffset.put(topicPartition,
InitialFetchState(topicIds(topicPartition.topic), leader,
- partition.getLeaderEpoch, futureLog.highWatermark))
+ if (partition.maybeCreateFutureReplica(futureLog.parentDir,
offsetCheckpoints, topicIds(partition.topic))) {
Review Comment:
> partition.maybeCreateFutureReplica() only calls
partition.createLogIfNotExists() if the future replica doesn't yet exist. If
that happens, partition.futureLog won't be set, so we need to call
partition.setLog(futureLog, true)?
`partition.setLog(futureLog, true)` is not necessary because when in
`partition.createLogIfNotExists()`, we'll also set futureLog:
```
if (isFutureReplica) {
this.futureLog = Some(maybeCreate(this.futureLog))
```
> Sincre this section is inside a block of logManager.getLog(topicPartition,
isFuture = true).foreach { futureLog =>, doesn't that mean this only runs if
the future replica exists?
Yes, normally, when we created future log is in this path:
1. ReplicaManager#alterReplicaLogDirs
2. partition.maybeCreateFutureReplica
3. partition.createLogIfNotExists
4. partition.createLog
5. logManager.getOrCreateLog
So in the end, we'll have future log added in both `logManager#futureLogs`
map and partition#futureLog` map.
But it's possible that the future log only exists in `logManager#futureLogs`
map, but not in `partition#futureLog` map, when the future log is created, and
before alter logDir completed, the broker restarted. So, after restarted, we'll
add the future log into logManager map during
[loadLog](https://github.com/apache/kafka/blob/3f8d11f047bf2f388fee7e8b5ddb359b47cee554/core/src/main/scala/kafka/log/LogManager.scala#L370).
But the `partition#futureLog` map won't be updated, until we got leadership
update and `ReplicaManager#maybeAddLogDirFetchers` is called. In this case, the
`partition.maybeCreateFutureReplica` will not create the future log since it's
existed, but the `partition#futureLog` will get updated with the one in
logManager.
That means, we have to do the `partition.createLogIfNotExists()` here.
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