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https://issues.apache.org/jira/browse/KAFKA-6481?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Lucas Wang updated KAFKA-6481:
------------------------------
Description:
The function ControllerChannelManager.addUpdateMetadataRequestForBrokers should
only process the partitions specified in the partitions parameter, i.e. the 2nd
parameter, and avoid iterating through the set of partitions in
TopicDeletionManager.partitionsToBeDeleted.
Here is why the current code can be a problem:
The number of partitions-to-be-deleted stored in the field
TopicDeletionManager.partitionsToBeDeleted can become quite large under certain
scenarios. For instance, if a topic a0 has dead replicas, the topic a0 would be
marked as ineligible for deletion, and its partitions will be retained in the
field TopicDeletionManager.partitionsToBeDeleted for future retries.
With a large set of partitions in TopicDeletionManager.partitionsToBeDeleted,
if some replicas in another topic a1 needs to be transitioned to OfflineReplica
state, possibly because of a broker going offline, a call stack listed as
following will happen on the controller, causing a iteration of the whole
partitions-to-be-deleted set for every single affected partition.
controller.topicDeletionManager.partitionsToBeDeleted.foreach(partition =>
updateMetadataRequestPartitionInfo(partition, beingDeleted = true))
ControllerBrokerRequestBatch.addUpdateMetadataRequestForBrokers
ControllerBrokerRequestBatch.addLeaderAndIsrRequestForBrokers
_inside a for-loop for each partition_
ReplicaStateMachine.doHandleStateChanges
ReplicaStateMachine.handleStateChanges
KafkaController.onReplicasBecomeOffline
KafkaController.onBrokerFailure
How to reproduce the problem:
1. Cretae a cluster with 2 brokers having id 1 and 2
2. Create a topic having 10 partitions and deliberately assign the replicas to
non-existing brokers, i.e.
./bin/kafka-topics.sh --zookeeper localhost:2181 --create --topic a0
--replica-assignment `echo -n 3:4; for i in \`seq 9\`; do echo -n ,3:4; done`
3. Delete the topic and cause all of its partitions to be retained in the field
TopicDeletionManager.partitionsToBeDeleted, since the topic has dead replicas,
and is ineligible for deletion.
./bin/kafka-topics.sh --zookeeper localhost:2181 --delete --topic a0
4._Verify that the following log message shows up 10 times in the
controller.log file, one line for each partition in topic a0: "Leader not yet
assigned for partition [a0,..]. Skip sending UpdateMetadataRequest."_
5. Create another topic a1 also having 10 partitions, i.e.
./bin/kafka-topics.sh --zookeeper localhost:2181 --create --topic a1
--replica-assignment `echo -n 1:2; for i in \`seq 9\`; do echo -n ,1:2; done`
6. Verify that the log message in step 4 appears *100 more* times (). This is
because we have the following stack trace:
addUpdateMetadataRequestForBrokers
addLeaderAndIsrRequestForBrokers
_inside a for-loop for each create response_
initializeLeaderAndIsrForPartitions
5. Kill the broker 2 and cause the replicas on broker 2 to be transitioned to
OfflineReplica state on the controller.
6. Verify that the following log message in step 4 appears another *210*
times. This is because
a. During controlled shutdown, the function
KafkaController.doControlledShutdown calls
replicaStateMachine.handleStateChanges to transition all the replicas on broker
2 to OfflineState. That in turn generates 100 (10 x 10) entries of the logs
above.
b. When the broker zNode is gone in ZK, the function
KafkaController.onBrokerFailure calls KafkaController.onReplicasBecomeOffline
to transition all the replicas on broker 2 to OfflineState. And this again
generates 100 (10 x 10) logs above.
c. At the bottom of the the function onReplicasBecomeOffline, it calls
sendUpdateMetadataRequest (given the partitionsWithoutLeader is empty), which
generates 10 logs, one for each partition in the a0 topic.
According to the analysis in step 6, when we have n partitions accumulated in
the variable partitionsToBeDeleted, and a broker with m partitions becomes
offline, 2 * m * n + n logs in step 4 will be generated.
After applying the patch in this RB, I've verified that by going through the
steps above, broker 2 going offline NO LONGER generates log entries for the a0
partitions.
Also I've verified that topic deletion for topic a1 still works fine.
was:
The function ControllerChannelManager.addUpdateMetadataRequestForBrokers should
only process the partitions specified in the partitions parameter, i.e. the 2nd
parameter, and avoid iterating through the set of partitions in
TopicDeletionManager.partitionsToBeDeleted.
Here is why the current code can be a problem:
The number of partitions-to-be-deleted stored in the field
TopicDeletionManager.partitionsToBeDeleted can become quite large under certain
scenarios. For instance, if a topic a0 has dead replicas, the topic a0 would be
marked as ineligible for deletion, and its partitions will be retained in the
field TopicDeletionManager.partitionsToBeDeleted for future retries.
With a large set of partitions in TopicDeletionManager.partitionsToBeDeleted,
if some replicas in another topic a1 needs to be transitioned to OfflineReplica
state, possibly because of a broker going offline, a call stack listed as
following will happen on the controller, causing a iteration of the whole
partitions-to-be-deleted set for every single affected partition.
controller.topicDeletionManager.partitionsToBeDeleted.foreach(partition =>
updateMetadataRequestPartitionInfo(partition, beingDeleted = true))
ControllerBrokerRequestBatch.addUpdateMetadataRequestForBrokers
ControllerBrokerRequestBatch.addLeaderAndIsrRequestForBrokers
inside a for-loop for each partition
ReplicaStateMachine.doHandleStateChanges
ReplicaStateMachine.handleStateChanges
KafkaController.onReplicasBecomeOffline
KafkaController.onBrokerFailure
How to reproduce the problem:
1. Cretae a cluster with 2 brokers having id 1 and 2
2. Create a topic having 10 partitions and deliberately assign the replicas to
non-existing brokers, i.e.
./bin/kafka-topics.sh --zookeeper localhost:2181 --create --topic a0
--replica-assignment `echo -n 3:4; for i in \`seq 9\`; do echo -n ,3:4; done`
3. Delete the topic and cause all of its partitions to be retained in the field
TopicDeletionManager.partitionsToBeDeleted, since the topic has dead replicas,
and is ineligible for deletion.
./bin/kafka-topics.sh --zookeeper localhost:2181 --delete --topic a0
4. Create another topic a1 also having 10 partitions, i.e.
./bin/kafka-topics.sh --zookeeper localhost:2181 --create --topic a1
--replica-assignment `echo -n 1:2; for i in \`seq 9\`; do echo -n ,1:2; done`
5. Kill the broker 2 and cause the replicas on broker 2 to be transitioned to
OfflineReplica state on the controller.
6. Verify that the following log message appear over 200 times in the
controller.log file, one for each iteration of the a0 partitions
"Leader not yet assigned for partition [a0,..]. Skip sending
UpdateMetadataRequest."
What happened was
1. During controlled shutdown, the function
KafkaController.doControlledShutdown calls
replicaStateMachine.handleStateChanges to transition all the replicas on broker
2 to OfflineState. That in turn generates 100 (10 x 10) entries of the logs
above.
2. When the broker zNode is gone in ZK, the function
KafkaController.onBrokerFailure calls KafkaController.onReplicasBecomeOffline
to transition all the replicas on broker 2 to OfflineState. And this again
generates 100 (10 x 10) entries of the logs above.
After applying the patch in this RB, I've verified that by going through the
steps above, broker 2 going offline NO LONGER generates log entries for the a0
partitions.
Also I've verified that topic deletion for topic a1 still works fine.
> Improving performance of the function
> ControllerChannelManager.addUpdateMetadataRequestForBrokers
> -------------------------------------------------------------------------------------------------
>
> Key: KAFKA-6481
> URL: https://issues.apache.org/jira/browse/KAFKA-6481
> Project: Kafka
> Issue Type: Improvement
> Reporter: Lucas Wang
> Assignee: Lucas Wang
> Priority: Minor
>
> The function ControllerChannelManager.addUpdateMetadataRequestForBrokers
> should only process the partitions specified in the partitions parameter,
> i.e. the 2nd parameter, and avoid iterating through the set of partitions in
> TopicDeletionManager.partitionsToBeDeleted.
>
> Here is why the current code can be a problem:
> The number of partitions-to-be-deleted stored in the field
> TopicDeletionManager.partitionsToBeDeleted can become quite large under
> certain scenarios. For instance, if a topic a0 has dead replicas, the topic
> a0 would be marked as ineligible for deletion, and its partitions will be
> retained in the field TopicDeletionManager.partitionsToBeDeleted for future
> retries.
> With a large set of partitions in
> TopicDeletionManager.partitionsToBeDeleted, if some replicas in another topic
> a1 needs to be transitioned to OfflineReplica state, possibly because of a
> broker going offline, a call stack listed as following will happen on the
> controller, causing a iteration of the whole partitions-to-be-deleted set for
> every single affected partition.
> controller.topicDeletionManager.partitionsToBeDeleted.foreach(partition
> => updateMetadataRequestPartitionInfo(partition, beingDeleted = true))
> ControllerBrokerRequestBatch.addUpdateMetadataRequestForBrokers
> ControllerBrokerRequestBatch.addLeaderAndIsrRequestForBrokers
> _inside a for-loop for each partition_
> ReplicaStateMachine.doHandleStateChanges
> ReplicaStateMachine.handleStateChanges
> KafkaController.onReplicasBecomeOffline
> KafkaController.onBrokerFailure
> How to reproduce the problem:
> 1. Cretae a cluster with 2 brokers having id 1 and 2
> 2. Create a topic having 10 partitions and deliberately assign the replicas
> to non-existing brokers, i.e.
> ./bin/kafka-topics.sh --zookeeper localhost:2181 --create --topic a0
> --replica-assignment `echo -n 3:4; for i in \`seq 9\`; do echo -n ,3:4; done`
> 3. Delete the topic and cause all of its partitions to be retained in the
> field TopicDeletionManager.partitionsToBeDeleted, since the topic has dead
> replicas, and is ineligible for deletion.
> ./bin/kafka-topics.sh --zookeeper localhost:2181 --delete --topic a0
> 4._Verify that the following log message shows up 10 times in the
> controller.log file, one line for each partition in topic a0: "Leader not yet
> assigned for partition [a0,..]. Skip sending UpdateMetadataRequest."_
> 5. Create another topic a1 also having 10 partitions, i.e.
> ./bin/kafka-topics.sh --zookeeper localhost:2181 --create --topic a1
> --replica-assignment `echo -n 1:2; for i in \`seq 9\`; do echo -n ,1:2; done`
> 6. Verify that the log message in step 4 appears *100 more* times (). This is
> because we have the following stack trace:
> addUpdateMetadataRequestForBrokers
> addLeaderAndIsrRequestForBrokers
> _inside a for-loop for each create response_
> initializeLeaderAndIsrForPartitions
> 5. Kill the broker 2 and cause the replicas on broker 2 to be transitioned
> to OfflineReplica state on the controller.
> 6. Verify that the following log message in step 4 appears another *210*
> times. This is because
> a. During controlled shutdown, the function
> KafkaController.doControlledShutdown calls
> replicaStateMachine.handleStateChanges to transition all the replicas on
> broker 2 to OfflineState. That in turn generates 100 (10 x 10) entries of the
> logs above.
> b. When the broker zNode is gone in ZK, the function
> KafkaController.onBrokerFailure calls KafkaController.onReplicasBecomeOffline
> to transition all the replicas on broker 2 to OfflineState. And this again
> generates 100 (10 x 10) logs above.
> c. At the bottom of the the function onReplicasBecomeOffline, it calls
> sendUpdateMetadataRequest (given the partitionsWithoutLeader is empty), which
> generates 10 logs, one for each partition in the a0 topic.
> According to the analysis in step 6, when we have n partitions accumulated in
> the variable partitionsToBeDeleted, and a broker with m partitions becomes
> offline, 2 * m * n + n logs in step 4 will be generated.
> After applying the patch in this RB, I've verified that by going through the
> steps above, broker 2 going offline NO LONGER generates log entries for the
> a0 partitions.
> Also I've verified that topic deletion for topic a1 still works fine.
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