[jira] [Commented] (KAFKA-1561) Data Loss for Incremented Replica Factor and Leader Election

["Vinayak Sharma (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/KAFKA-1561?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16039226#comment-16039226 ] 

Vinayak Sharma commented on KAFKA-1561:
---------------------------------------

Hi,
[~junrao]
I have Cluster consisting of 3 Zookeeper nodes and 2 Brokers running on AWS instances. When I am trying to scale Brokers from 2 to 3 while simultaneously producing and consuming from topic I am experiencing loss of messages.

Topic :
Partitions - 40
Replication Factor - 2

I am using console producer to produce 1000 messages at a time to the topic. I do this for 200 secs and then print total no of messages produced, while simultaneously I run a script to consume from the same topic.While these scripts are running I reassign the partitions of the same topic from 2 brokers(0,1) to 3 brokers(0,1,2 ). While these reassignment of partitions is running I see producer throwing the following logs:
[2017-05-31 13:31:13,311] WARN Got error produce response with correlation id 4 on topic-partition Topic6-39, retrying (2 attempts left). Error: NOT_LEADER_FOR_PARTITION (org.apache.kafka.clients.producer.internals.Sender)
[2017-05-31 13:31:13,338] WARN Got error produce response with correlation id 4 on topic-partition Topic6-27, retrying (2 attempts left). Error: NOT_LEADER_FOR_PARTITION (org.apache.kafka.clients.producer.internals.Sender)
[2017-05-31 13:31:13,338] WARN Got error produce response with correlation id 4 on topic-partition Topic6-21, retrying (2 attempts left). Error: NOT_LEADER_FOR_PARTITION (org.apache.kafka.clients.producer.internals.Sender)
[2017-05-31 13:31:13,338] WARN Got error produce response with correlation id 4 on topic-partition Topic6-15, retrying (2 attempts left). Error: NOT_LEADER_FOR_PARTITION (org.apache.kafka.clients.producer.internals.Sender)
[2017-05-31 13:31:13,339] WARN Got error produce response with correlation id 6 on topic-partition Topic6-36, retrying (2 attempts left). Error: NOT_LEADER_FOR_PARTITION (org.apache.kafka.clients.producer.internals.Sender)
[2017-05-31 13:31:13,339] WARN Got error produce response with correlation id 6 on topic-partition Topic6-6, retrying (2 attempts left). Error: NOT_LEADER_FOR_PARTITION (org.apache.kafka.clients.producer.internals.Sender)
[2017-05-31 13:31:13,339] WARN Got error produce response with correlation id 6 on topic-partition Topic6-0, retrying (2 attempts left). Error: NOT_LEADER_FOR_PARTITION (org.apache.kafka.clients.producer.internals.Sender)
[2017-05-31 13:31:13,342] WARN Got error produce response with correlation id 6 on topic-partition Topic6-18, retrying (2 attempts left). Error: NOT_LEADER_FOR_PARTITION (org.apache.kafka.clients.producer.internals.Sender)
[2017-05-31 13:31:13,343] WARN Got error produce response with correlation id 6 on topic-partition Topic6-24, retrying (2 attempts left). Error: NOT_LEADER_FOR_PARTITION (org.apache.kafka.clients.producer.internals.Sender)
[2017-05-31 13:31:13,401] WARN Got error produce response with correlation id 11 on topic-partition Topic6-3, retrying (2 attempts left). Error: NOT_LEADER_FOR_PARTITION (org.apache.kafka.clients.producer.internals.Sender)


After 200 secs I see that producer says the total number of messages produced are 61000 while consumed messages are 60974.

Just to make sure whether it is consumer's fault or producer's fault, I run another console consumer on the same topic from the beginning and observer that there were actually 60974 messages in that topic. So that proves that the messages were lost at the producer end.

I also tried the same test with adding the following property to the topic being used:
unclean.leader.election.enable = false

And I also changed the "leader.imbalance.check.interval.seconds" in server.properties from 30 secs to 1 sec.

Still the loss of messages persist.

I have posted these issue on confluent-platform(Thread name = Loss of data while Scaling Kafka Brokers) also but have not got any reply yet.
Please tell me how can I completely avoid this loss of messages.
Thanks.

> Data Loss for Incremented Replica Factor and Leader Election
> ------------------------------------------------------------
>
>                 Key: KAFKA-1561
>                 URL: https://issues.apache.org/jira/browse/KAFKA-1561
>             Project: Kafka
>          Issue Type: Bug
>            Reporter: Guozhang Wang
>            Assignee: Guozhang Wang
>         Attachments: broker0.log, broker2.log, consumer.log, producer.log
>
>
> This is reported on the mailing list (thanks to Jad).
> {quote}
> Hi,
> I have a test that continuously sends messages to one broker, brings up
> another broker, and adds it as a replica for all partitions, with it being
> the preferred replica for some. I have auto.leader.rebalance.enable=true,
> so replica election gets triggered. Data is being pumped to the old broker
> all the while. It seems that some data gets lost while switching over to
> the new leader. Is this a bug, or do I have something misconfigured? I also
> have request.required.acks=-1 on the producer.
> Here's what I think is happening:
> 1. Producer writes message to broker 0, [EventServiceUpsertTopic,13], w/
> broker 0 currently leader, with ISR=(0), so write returns successfully,
> even when acks = -1. Correlation id 35836
> Producer log:
> [2014-07-24 14:44:26,991]  [DEBUG]  [dw-97 - PATCH
> /v1/events/type_for_test_bringupNewBroker_shouldRebalance_shouldNotLoseData/event?_idPath=idField&_mergeFields=field1]
> [kafka.producer.BrokerPartitionInfo]  Partition
> [EventServiceUpsertTopic,13] has leader 0
> [2014-07-24 14:44:26,993]  [DEBUG]  [dw-97 - PATCH
> /v1/events/type_for_test_bringupNewBroker_shouldRebalance_shouldNotLoseData/event?_idPath=idField&_mergeFields=field1]
> [k.producer.async.DefaultEventHandler]  Producer sent messages with
> correlation id 35836 for topics [EventServiceUpsertTopic,13] to broker 0 on
> localhost:56821
> 2. Broker 1 is still catching up
> Broker 0 Log:
> [2014-07-24 14:44:26,992]  [DEBUG]  [kafka-request-handler-3]
> [kafka.cluster.Partition]  Partition [EventServiceUpsertTopic,13] on broker
> 0: Old hw for partition [EventServiceUpsertTopic,13] is 971. New hw is 971.
> All leo's are 975,971
> [2014-07-24 14:44:26,992]  [DEBUG]  [kafka-request-handler-3]
> [kafka.server.KafkaApis]  [KafkaApi-0] Produce to local log in 0 ms
> [2014-07-24 14:44:26,992]  [DEBUG]  [kafka-processor-56821-0]
> [kafka.request.logger]  Completed request:Name: ProducerRequest; Version:
> 0; CorrelationId: 35836; ClientId: ; RequiredAcks: -1; AckTimeoutMs: 10000
> ms from client /127.0.0.1:57086
> ;totalTime:0,requestQueueTime:0,localTime:0,remoteTime:0,responseQueueTime:0,sendTime:0
> 3. Leader election is triggered by the scheduler:
> Broker 0 Log:
> [2014-07-24 14:44:26,991]  [INFO ]  [kafka-scheduler-0]
> [k.c.PreferredReplicaPartitionLeaderSelector]
> [PreferredReplicaPartitionLeaderSelector]: Current leader 0 for partition [
> EventServiceUpsertTopic,13] is not the preferred replica. Trigerring
> preferred replica leader election
> [2014-07-24 14:44:26,993]  [DEBUG]  [kafka-scheduler-0]
> [kafka.utils.ZkUtils$]  Conditional update of path
> /brokers/topics/EventServiceUpsertTopic/partitions/13/state with value
> {"controller_epoch":1,"leader":1,"version":1,"leader_epoch":3,"isr":[0,1]}
> and expected version 3 succeeded, returning the new version: 4
> [2014-07-24 14:44:26,994]  [DEBUG]  [kafka-scheduler-0]
> [k.controller.PartitionStateMachine]  [Partition state machine on
> Controller 0]: After leader election, leader cache is updated to
> Map(<Snipped>(Leader:1,ISR:0,1,LeaderEpoch:3,ControllerEpoch:1),<EndSnip>)
> [2014-07-24 14:44:26,994]  [INFO ]  [kafka-scheduler-0]
> [kafka.controller.KafkaController]  [Controller 0]: Partition [
> EventServiceUpsertTopic,13] completed preferred replica leader election.
> New leader is 1
> 4. Broker 1 is still behind, but it sets the high water mark to 971!!!
> Broker 1 Log:
> [2014-07-24 14:44:26,999]  [INFO ]  [kafka-request-handler-6]
> [kafka.server.ReplicaFetcherManager]  [ReplicaFetcherManager on broker 1]
> Removed fetcher for partitions [EventServiceUpsertTopic,13]
> [2014-07-24 14:44:27,000]  [DEBUG]  [kafka-request-handler-6]
> [kafka.cluster.Partition]  Partition [EventServiceUpsertTopic,13] on broker
> 1: Old hw for partition [EventServiceUpsertTopic,13] is 970. New hw is -1.
> All leo's are -1,971
> [2014-07-24 14:44:27,098]  [DEBUG]  [kafka-request-handler-3]
> [kafka.server.KafkaApis]  [KafkaApi-1] Maybe update partition HW due to
> fetch request: Name: FetchRequest; Version: 0; CorrelationId: 1; ClientId:
> ReplicaFetcherThread-0-1; ReplicaId: 0; MaxWait: 500 ms; MinBytes: 1 bytes;
> RequestInfo: [EventServiceUpsertTopic,13] ->
> PartitionFetchInfo(971,1048576), <Snipped>
> [2014-07-24 14:44:27,098]  [DEBUG]  [kafka-request-handler-3]
> [kafka.cluster.Partition]  Partition [EventServiceUpsertTopic,13] on broker
> 1: Recording follower 0 position 971 for partition [
> EventServiceUpsertTopic,13].
> [2014-07-24 14:44:27,100]  [DEBUG]  [kafka-request-handler-3]
> [kafka.cluster.Partition]  Partition [EventServiceUpsertTopic,13] on broker
> 1: Highwatermark for partition [EventServiceUpsertTopic,13] updated to 971
> 5. Consumer is none the wiser. All data that was in offsets 972-975 doesn't
> show up!
> I tried this with 2 initial replicas, and adding a 3rd which is supposed to
> be the leader for some new partitions, and this problem also happens there.
> The log on the old leader gets truncated to the offset on the new leader.
> What's the solution? Can I make a new broker leader for partitions that are
> currently active without losing data?
> Thanks,
> Jad.
> {quote}



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