[GitHub] [kafka] rondagostino commented on a change in pull request #10155: Fix Raft broker restart issue when offset partitions are deferred

[GitBox <gi...@apache.org>]

rondagostino commented on a change in pull request #10155:
URL: https://github.com/apache/kafka/pull/10155#discussion_r579240227



##########
File path: core/src/main/scala/kafka/server/BrokerServer.scala
##########
@@ -326,14 +326,16 @@ class BrokerServer(
       // Start log manager, which will perform (potentially lengthy) recovery-from-unclean-shutdown if required.
       logManager.startup(metadataCache.getAllTopics())
       // Start other services that we've delayed starting, in the appropriate order.
-      replicaManager.endMetadataChangeDeferral(
-        RequestHandlerHelper.onLeadershipChange(groupCoordinator, transactionCoordinator, _, _))
       replicaManager.startup()
       replicaManager.startHighWatermarkCheckPointThread()
       groupCoordinator.startup(() => metadataCache.numPartitions(Topic.GROUP_METADATA_TOPIC_NAME).
         getOrElse(config.offsetsTopicPartitions))
       transactionCoordinator.startup(() => metadataCache.numPartitions(Topic.TRANSACTION_STATE_TOPIC_NAME).
         getOrElse(config.transactionTopicPartitions))
+      // Apply deferred changes after starting coordinators to avoid GroupMetadataManager IllegalStateException
+      // due to Kafka scheduler not yet running (this manifests if we have deferred any coordinator offsets partitions).

Review comment:
       > comments should explain the intended behavior vs what errors we are trying to avoid 
   
   Yeah, makes sense.  New comment is as follows:
   
   ```
         // Apply deferred partition metadata changes after starting replica manager and coordinators
         // so that those services are ready and able to process the changes.
   ```




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