Done! Thanks!
On Mon, Jul 28, 2014 at 4:16 PM, Guozhang Wang <wangg...@gmail.com> wrote: > Thanks Jad, > > The mailing list may blocked the attachments. I have file a JIRA for your > issue, could you upload the logs there? > > https://issues.apache.org/jira/browse/KAFKA-1561 > > Guozhang > > > On Mon, Jul 28, 2014 at 1:55 PM, Jad Naous <jad.na...@appdynamics.com> > wrote: > > > The logs are quite large. I've sifted through them, and I'm attaching the > > logs for the relevant parts where the lost message goes through the > system. > > Here's what the test does: > > > > 0) Start two brokers, one producer, one consumer. Topic has 20 > partitions, > > using default partitioning scheme (which seems to send data to only a > > couple of partitions when the keys are null, but that doesn't matter for > > this test). > > 1) Start a data generator sending data through Kafka continuously > > 2) Start a new broker > > 3) Reassign partitions: {"version": 1, "partitions":[ > > {"topic":"EventServiceUpsertTopic","partition":0, "replicas": > > [0, 1, 2]}, > > {"topic":"EventServiceUpsertTopic","partition":1, "replicas": > > [1, 2, 0]}, > > {"topic":"EventServiceUpsertTopic","partition":2, "replicas": > > [2, 0, 1]}, > > {"topic":"EventServiceUpsertTopic","partition":3, "replicas": > > [0, 1, 2]}, > > {"topic":"EventServiceUpsertTopic","partition":4, "replicas": > > [1, 2, 0]}, > > {"topic":"EventServiceUpsertTopic","partition":5, "replicas": > > [2, 0, 1]}, > > {"topic":"EventServiceUpsertTopic","partition":6, "replicas": > > [0, 1, 2]}, > > {"topic":"EventServiceUpsertTopic","partition":7, "replicas": > > [1, 2, 0]}, > > {"topic":"EventServiceUpsertTopic","partition":8, "replicas": > > [2, 0, 1]}, > > {"topic":"EventServiceUpsertTopic","partition":9, "replicas": > > [0, 1, 2]}, > > {"topic":"EventServiceUpsertTopic","partition":10, "replicas": > > [1, 2, 0]}, > > {"topic":"EventServiceUpsertTopic","partition":11, "replicas": > > [2, 0, 1]}, > > {"topic":"EventServiceUpsertTopic","partition":12, "replicas": > > [0, 1, 2]}, > > {"topic":"EventServiceUpsertTopic","partition":13, "replicas": > > [1, 2, 0]}, > > {"topic":"EventServiceUpsertTopic","partition":14, "replicas": > > [2, 0, 1]}, > > {"topic":"EventServiceUpsertTopic","partition":15, "replicas": > > [0, 1, 2]}, > > {"topic":"EventServiceUpsertTopic","partition":16, "replicas": > > [1, 2, 0]}, > > {"topic":"EventServiceUpsertTopic","partition":17, "replicas": > > [2, 0, 1]}, > > {"topic":"EventServiceUpsertTopic","partition":18, "replicas": > > [0, 1, 2]}, > > {"topic":"EventServiceUpsertTopic","partition":19, "replicas": > > [1, 2, 0]}]} > > 4) Wait until reassignment is complete (i.e. until > > ZkUtils.getPartitionsBeingReassigned() returns empty map) > > 5) Wait until all replicas are caught up (i.e. until > > ZkUtils.getLeaderAndIsrForPartition() returns all brokers in the ISR for > > each partition) > > 6) Trigger leader re-election by calling the > > PreferredReplicaLeaderElectionCommand > > 7) Wait until all the leaders are the preferred leaders for partitions > > according to the replica reassignment from step 3 > > 8) Stop the data generator > > 9) Check that all the data was consumed > > > > You can seem from the producer.log that the data: {"field1": ["10"], > > "idField": "id-5-59"} was sent to broker0 successfully, but the consumer > > never sees it. > > > > Thanks, > > Jad. > > > > > > > > On Mon, Jul 28, 2014 at 10:33 AM, Guozhang Wang <wangg...@gmail.com> > > wrote: > > > >> Also, for the initial two replica case did you see any error/warning > logs > >> on your producers? > >> > >> Guozhang > >> > >> > >> On Mon, Jul 28, 2014 at 10:32 AM, Guozhang Wang <wangg...@gmail.com> > >> wrote: > >> > >> > Hi Jad, > >> > > >> > Just to clarify, you also see data loss when you created the topic > with > >> > replica factor 2, and two replicas running, and after an auto leader > >> > election triggered? If that is the case could you attach the logs of > all > >> > involved brokers here? > >> > > >> > For your second question, KAFKA-1211 is designed to handle that case. > >> > > >> > Guozhang > >> > > >> > > >> > On Mon, Jul 28, 2014 at 10:18 AM, Jad Naous < > jad.na...@appdynamics.com> > >> > wrote: > >> > > >> >> Guozhang, > >> >> > >> >> I have actually also seen this happen when there are two replicas > >> >> initially. So this problem is not limited to 1 replica. The issue is > >> the > >> >> truncation after leader election, which will also happen on the > second > >> >> replica. > >> >> > >> >> Coming back to your objections: > >> >> > >> >> > >> >> First case: inconsistency between replicas > >> >> > 1) currently replica 1 is the current leader > >> >> > replica 1: m1 m2 m3 > >> >> > replica 2: m1 m2 > >> >> > 2) replica 1 fails, and replica 2 becomes the new leader and accept > >> >> > messages 4 and 5: > >> >> > replica 1: m1 m2 m3 > >> >> > replica 2: m1 m2 m4 m5 > >> >> > 3) replica 1 resumes, and does not truncate to HW, then it will > still > >> >> > maintain m3, which is actually never "committed". Say leader moves > to > >> >> > replica 1 again, we can ended up with: > >> >> > replica 1: m1 m2 m3 m6 > >> >> > replica 2: m1 m2 m4 m5 > >> >> > >> >> > >> >> I see. So when a replica resumes, it has to truncate to the last HW > it > >> saw > >> >> before it died. > >> >> > >> >> > >> >> > > >> >> > Second case: inconsistency between server and clients: > >> >> > 1) producer send message m3 with ack=-1: > >> >> > replica 1: m1 m2 m3 > >> >> > replica 2: m1 m2 m3 > >> >> > replica 3: m1 m2 > >> >> > 2) the response is held until all replicas also gets m3, say at > this > >> >> time > >> >> > current leader replica 1 fails and replica 3 re-elects. If replica > 3 > >> >> gets > >> >> > up to the largest LEO it will also get m3. > >> >> > replica 2: m1 m2 m3 > >> >> > replica 3: m1 m2 m3 > >> >> > 3) But m3 is not actually "committed" by the time replica 1 fails; > >> when > >> >> > producer gets the error at the time replica 1 fails, it will think > >> that > >> >> m3 > >> >> > was not successfully sent, so retry sending m3: > >> >> > replica 2: m1 m2 m3 m3 > >> >> > replica 3: m1 m2 m3 m3 > >> >> > >> >> > >> >> So on failure, all nodes need to truncate to the HW. But if there's > no > >> >> failure, then truncating would lose data unnecessarily. Maybe those > two > >> >> scenarios need to be handled differently? > >> >> > >> >> Jad. > >> >> > >> >> > >> >> On Mon, Jul 28, 2014 at 9:58 AM, Guozhang Wang <wangg...@gmail.com> > >> >> wrote: > >> >> > >> >> > Jun, Jad, > >> >> > > >> >> > I think in this case data loss can still happen, since the replica > >> >> factor > >> >> > was previously one, and in handling the produce requests, if the > >> server > >> >> > decides that all the produced partitions have a replica factor of 1 > >> it > >> >> will > >> >> > also directly send back the response instead of putting the request > >> into > >> >> > purgatory even if currently the number of replicas is 2 (for > details > >> >> look > >> >> > at ReplicaManager.getReplicationFactorForPartition and search of > the > >> >> usage > >> >> > of Partition.replicationFactor). > >> >> > > >> >> > I now agree that this is not related to KAFKA-1211 but a different > >> small > >> >> > bug. We need to probably file another JIRA for this. But I think > >> after > >> >> this > >> >> > one is fixed (which should be much easier than KAFKA-1211), Jad's > >> >> scenario > >> >> > should not cause data loss anymore. > >> >> > > >> >> > Guozhang > >> >> > > >> >> > > >> >> > On Sun, Jul 27, 2014 at 6:11 PM, Jad Naous < > >> jad.na...@appdynamics.com> > >> >> > wrote: > >> >> > > >> >> > > So in summary, is it true to say that currently triggering leader > >> >> > > reelection is not a safe operation? I have been able to reproduce > >> that > >> >> > > message loss pretty reliably in tests. If that is the case, isn't > >> >> that an > >> >> > > important operation in a large cluster where nodes go up and > down? > >> >> > > On Jul 25, 2014 10:00 PM, "Jun Rao" <jun...@gmail.com> wrote: > >> >> > > > >> >> > > > Actually, I don't think KAFKA-1211 will happen with just 2 > >> replicas. > >> >> > > When a > >> >> > > > replica becomes a leader, it never truncates its log. Only > when a > >> >> > replica > >> >> > > > becomes follower, it truncates its log to HW. So in this > >> particular > >> >> > case, > >> >> > > > the new leader will not truncate data to offset 8. > >> >> > > > > >> >> > > > Thanks, > >> >> > > > > >> >> > > > Jun > >> >> > > > > >> >> > > > > >> >> > > > On Fri, Jul 25, 2014 at 3:37 PM, Guozhang Wang < > >> wangg...@gmail.com> > >> >> > > wrote: > >> >> > > > > >> >> > > > > Hi Jad, > >> >> > > > > > >> >> > > > > Yes. In this case I think you are actually hitting > KAFKA-1211. > >> The > >> >> > > > summary > >> >> > > > > of the issue is that, it takes one more fetch request round > >> trip > >> >> for > >> >> > > the > >> >> > > > > follower replica to advance the HW after the leader has > >> advanced > >> >> HW. > >> >> > So > >> >> > > > for > >> >> > > > > your case, the whole process is like this: > >> >> > > > > > >> >> > > > > 1. leader LEO at 10, follower LEO at 8. Both leader and > >> follower > >> >> > knows > >> >> > > > the > >> >> > > > > LEO is at 8. > >> >> > > > > 2. Follower fetch data on Leader starting at 8, leader > records > >> its > >> >> > LEO > >> >> > > as > >> >> > > > > 8. > >> >> > > > > 3. Follower gets 9 and 10 and append to its local log. > >> >> > > > > 4. Follower fetch data on Leader starting at 10, leader > records > >> >> its > >> >> > LEO > >> >> > > > as > >> >> > > > > 10; now leader knows follower has caught up, it advances its > HW > >> >> to 10 > >> >> > > and > >> >> > > > > adds the follower to ISR (but follower does not know that > yet! > >> It > >> >> > still > >> >> > > > > think the HW is 8). > >> >> > > > > 5. Leader's fetch response gets back to follower, and now the > >> >> > follower > >> >> > > > > knows that HW has been updated to 10. > >> >> > > > > > >> >> > > > > And let's say there is a leader election between step 4) and > >> 5), > >> >> for > >> >> > > your > >> >> > > > > case it is due to preferred leader election, but it could > also > >> be > >> >> > that > >> >> > > > > current leader fails, etc. Then on becoming the new leader > the > >> >> > follower > >> >> > > > > will truncate its data to 8, which is the HW it knows. Hence > >> the > >> >> data > >> >> > > > loss. > >> >> > > > > > >> >> > > > > The proposed solution in KAFKA-1211 will tackle this issue. > >> >> > > > > > >> >> > > > > Guozhang > >> >> > > > > > >> >> > > > > > >> >> > > > > On Fri, Jul 25, 2014 at 2:48 PM, Jad Naous < > >> >> > jad.na...@appdynamics.com> > >> >> > > > > wrote: > >> >> > > > > > >> >> > > > > > Hi Guozhang, > >> >> > > > > > > >> >> > > > > > Yes, broker 1 is in the ISR (in fact, I wait for broker 1 > to > >> be > >> >> in > >> >> > > the > >> >> > > > > ISR > >> >> > > > > > before triggering election). However, I think there is > >> something > >> >> > > still > >> >> > > > > > amiss. I still see data loss. Here are some relevant log > >> lines > >> >> from > >> >> > > > > broker > >> >> > > > > > 0 (different test run). The log on broker 0 is getting > >> >> truncated, > >> >> > > > losing > >> >> > > > > > some messages. > >> >> > > > > > > >> >> > > > > > [2014-07-25 10:40:02,134] [DEBUG] > [kafka-request-handler-5] > >> >> > > > > > [kafka.cluster.Partition] Partition > >> >> [EventServiceUpsertTopic,19] > >> >> > on > >> >> > > > > broker > >> >> > > > > > 0: Old hw for partition [EventServiceUpsertTopic,19] is > 8082. > >> >> New > >> >> > hw > >> >> > > is > >> >> > > > > > 8082. All leo's are 8111,8082 > >> >> > > > > > > >> >> > > > > > [2014-07-25 10:40:02,134] [DEBUG] > [kafka-request-handler-5] > >> >> > > > > > [kafka.server.KafkaApis] [KafkaApi-0] Produce to local log > >> in > >> >> 1 ms > >> >> > > > > > > >> >> > > > > > [2014-07-25 10:40:02,134] [DEBUG] > >> >> > > [main-SendThread(localhost:49893)] > >> >> > > > > > [org.apache.zookeeper.ClientCnxn] Reading reply > >> >> > > > > > sessionid:0x476e9a9e9a0001, packet:: clientPath:null > >> >> > serverPath:null > >> >> > > > > > finished:false header:: 729,5 replyHeader:: > 729,4294968217,0 > >> >> > > > request:: > >> >> > > > > > > >> >> > > > > > > >> >> > > > > > >> >> > > > > >> >> > > > >> >> > > >> >> > >> > '/brokers/topics/EventServiceUpsertTopic/partitions/5/state,#7b22636f6e74726f6c6c65725f65706f6368223a312c226c6561646572223a312c2276657273696f6e223a312c226c65616465725f65706f6368223a332c22697372223a5b302c315d7d,3 > >> >> > > > > > response:: > >> >> > > > > > > >> >> > > > > > > >> >> > > > > > >> >> > > > > >> >> > > > >> >> > > >> >> > >> > s{4294967416,4294968217,1406309966419,1406310002132,4,0,0,0,74,0,4294967416} > >> >> > > > > > > >> >> > > > > > [2014-07-25 10:40:02,134] [DEBUG] > [kafka-processor-49917-2] > >> >> > > > > > [kafka.request.logger] Completed request:Name: > >> ProducerRequest; > >> >> > > > Version: > >> >> > > > > > 0; CorrelationId: 16248; ClientId: ; RequiredAcks: -1; > >> >> > AckTimeoutMs: > >> >> > > > > 10000 > >> >> > > > > > ms from client /127.0.0.1:50168 > >> >> > > > > > > >> >> > > > > > > >> >> > > > > > >> >> > > > > >> >> > > > >> >> > > >> >> > >> > ;totalTime:1,requestQueueTime:0,localTime:1,remoteTime:0,responseQueueTime:0,sendTime:0 > >> >> > > > > > > >> >> > > > > > [2014-07-25 10:40:02,134] [DEBUG] > >> >> > > > > > > >> >> > > > > >> >> > > >> >> > >> > [ZkClient-EventThread-13-localhost:49893,localhost:49896,localhost:49899] > >> >> > > > > > [kafka.utils.ZkUtils$] Conditional update of path > >> >> > > > > > /brokers/topics/EventServiceUpsertTopic/partitions/5/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 > >> >> > > > > > > >> >> > > > > > [2014-07-25 10:40:02,136] [DEBUG] > >> >> > > > > > > >> >> > > > > >> >> > > >> >> > >> > [ZkClient-EventThread-13-localhost:49893,localhost:49896,localhost:49899] > >> >> > > > > > [k.controller.PartitionStateMachine] [Partition state > >> machine > >> >> on > >> >> > > > > > Controller 0]: After leader election, leader cache is > >> updated to > >> >> > > > > > Map([EventServiceUpsertTopic,18] -> > >> >> > > > > > (Leader:0,ISR:0,LeaderEpoch:0,ControllerEpoch:1), > >> >> > > > > > [EventServiceUpsertTopic,4] -> > >> >> > > > > > (Leader:0,ISR:0,LeaderEpoch:0,ControllerEpoch:1), > >> >> > > > > > [EventServiceUpsertTopic,7] -> > >> >> > > > > > (Leader:1,ISR:0,1,LeaderEpoch:3,ControllerEpoch:1), > >> >> > > > > > [EventServiceUpsertTopic,17] -> > >> >> > > > > > (Leader:1,ISR:0,1,LeaderEpoch:3,ControllerEpoch:1), > >> >> > > > > > [EventServiceUpsertTopic,16] -> > >> >> > > > > > (Leader:0,ISR:0,LeaderEpoch:0,ControllerEpoch:1), > >> >> > > > > > [EventServiceUpsertTopic,5] -> > >> >> > > > > > (Leader:1,ISR:0,1,LeaderEpoch:3,ControllerEpoch:1), > >> >> > > > > > [EventServiceUpsertTopic,10] -> > >> >> > > > > > (Leader:0,ISR:0,LeaderEpoch:0,ControllerEpoch:1), > >> >> > > > > > [EventServiceUpsertTopic,1] -> > >> >> > > > > > (Leader:1,ISR:0,1,LeaderEpoch:3,ControllerEpoch:1), > >> >> > > > > > [EventServiceUpsertTopic,13] -> > >> >> > > > > > (Leader:1,ISR:0,1,LeaderEpoch:3,ControllerEpoch:1), > >> >> > > > > > [EventServiceUpsertTopic,9] -> > >> >> > > > > > (Leader:1,ISR:0,1,LeaderEpoch:3,ControllerEpoch:1), > >> >> > > > > > [EventServiceUpsertTopic,8] -> > >> >> > > > > > (Leader:0,ISR:0,LeaderEpoch:0,ControllerEpoch:1), > >> >> > > > > > [EventServiceUpsertTopic,11] -> > >> >> > > > > > (Leader:1,ISR:0,1,LeaderEpoch:3,ControllerEpoch:1), > >> >> > > > > > [EventServiceUpsertTopic,6] -> > >> >> > > > > > (Leader:0,ISR:0,LeaderEpoch:0,ControllerEpoch:1), > >> >> > > > > > [EventServiceUpsertTopic,12] -> > >> >> > > > > > (Leader:0,ISR:0,LeaderEpoch:0,ControllerEpoch:1), > >> >> > > > > > [EventServiceUpsertTopic,2] -> > >> >> > > > > > (Leader:0,ISR:0,LeaderEpoch:0,ControllerEpoch:1), > >> >> > > > > > [EventServiceUpsertTopic,3] -> > >> >> > > > > > (Leader:1,ISR:0,1,LeaderEpoch:3,ControllerEpoch:1), > >> >> > > > > > [EventServiceUpsertTopic,14] -> > >> >> > > > > > (Leader:0,ISR:0,LeaderEpoch:0,ControllerEpoch:1), [ > >> >> > > > > > EventServiceUpsertTopic,19] -> > >> >> > > > > > (Leader:1,ISR:0,1,LeaderEpoch:3,ControllerEpoch:1), > >> >> > > > > > [EventServiceUpsertTopic,0] -> > >> >> > > > > > (Leader:0,ISR:0,LeaderEpoch:0,ControllerEpoch:1), > >> >> > > > > > [EventServiceUpsertTopic,15] -> > >> >> > > > > > (Leader:1,ISR:0,1,LeaderEpoch:3,ControllerEpoch:1)) > >> >> > > > > > > >> >> > > > > > [2014-07-25 10:40:02,136] [DEBUG] > [kafka-request-handler-1] > >> >> > > > > > [kafka.cluster.Partition] Partition > >> >> [EventServiceUpsertTopic,19] > >> >> > on > >> >> > > > > broker > >> >> > > > > > 0: Old hw for partition [EventServiceUpsertTopic,19] is > 8082. > >> >> New > >> >> > hw > >> >> > > is > >> >> > > > > > 8082. All leo's are 8112,8082 > >> >> > > > > > > >> >> > > > > > [2014-07-25 10:40:02,136] [DEBUG] > [kafka-request-handler-1] > >> >> > > > > > [kafka.server.KafkaApis] [KafkaApi-0] Produce to local log > >> in > >> >> 0 ms > >> >> > > > > > > >> >> > > > > > [2014-07-25 10:40:02,137] [DEBUG] > [kafka-processor-49917-2] > >> >> > > > > > [kafka.request.logger] Completed request:Name: > >> ProducerRequest; > >> >> > > > Version: > >> >> > > > > > 0; CorrelationId: 16250; ClientId: ; RequiredAcks: -1; > >> >> > AckTimeoutMs: > >> >> > > > > 10000 > >> >> > > > > > ms from client /127.0.0.1:50168 > >> >> > > > > > > >> >> > > > > > > >> >> > > > > > >> >> > > > > >> >> > > > >> >> > > >> >> > >> > ;totalTime:1,requestQueueTime:0,localTime:1,remoteTime:0,responseQueueTime:0,sendTime:0 > >> >> > > > > > > >> >> > > > > > [2014-07-25 10:40:02,140] [INFO ] > >> >> > > > > > > >> >> > > > > >> >> > > >> >> > >> > [ZkClient-EventThread-13-localhost:49893,localhost:49896,localhost:49899] > >> >> > > > > > [kafka.controller.KafkaController] [Controller 0]: > >> Partition [ > >> >> > > > > > EventServiceUpsertTopic,19] completed preferred replica > >> leader > >> >> > > > election. > >> >> > > > > > New leader is 1 > >> >> > > > > > > >> >> > > > > > [2014-07-25 10:40:02,140] [INFO ] > >> >> > > > > > > >> >> > > > > >> >> > > >> >> > >> > [ZkClient-EventThread-13-localhost:49893,localhost:49896,localhost:49899] > >> >> > > > > > [kafka.controller.KafkaController] [Controller 0]: > Partition > >> >> > > > > > [EventServiceUpsertTopic,5] completed preferred replica > >> leader > >> >> > > > election. > >> >> > > > > > New leader is 1 > >> >> > > > > > > >> >> > > > > > [2014-07-25 10:40:02,142] [DEBUG] > >> >> > > [main-SendThread(localhost:49893)] > >> >> > > > > > [org.apache.zookeeper.ClientCnxn] Got notification > >> >> > > > > > sessionid:0x476e9a9e9a0001 > >> >> > > > > > > >> >> > > > > > [2014-07-25 10:40:02,142] [DEBUG] > >> >> > > [main-SendThread(localhost:49893)] > >> >> > > > > > [org.apache.zookeeper.ClientCnxn] Got WatchedEvent > >> >> > > state:SyncConnected > >> >> > > > > > type:NodeDeleted path:/admin/preferred_replica_election for > >> >> > sessionid > >> >> > > > > > 0x476e9a9e9a0001 > >> >> > > > > > > >> >> > > > > > [2014-07-25 10:40:02,143] [DEBUG] > >> >> > > [main-SendThread(localhost:49893)] > >> >> > > > > > [org.apache.zookeeper.ClientCnxn] Reading reply > >> >> > > > > > sessionid:0x476e9a9e9a0001, packet:: clientPath:null > >> >> > serverPath:null > >> >> > > > > > finished:false header:: 730,2 replyHeader:: > 730,4294968218,0 > >> >> > > > request:: > >> >> > > > > > '/admin/preferred_replica_election,-1 response:: null > >> >> > > > > > > >> >> > > > > > [2014-07-25 10:40:02,145] [INFO ] > [kafka-request-handler-0] > >> >> > > > > > [kafka.server.ReplicaFetcherManager] > [ReplicaFetcherManager > >> on > >> >> > > broker > >> >> > > > 0] > >> >> > > > > > Removed fetcher for partitions > >> >> > > > > > > >> >> > > > > > > >> >> > > > > > >> >> > > > > >> >> > > > >> >> > > >> >> > >> > [EventServiceUpsertTopic,13],[EventServiceUpsertTopic,11],[EventServiceUpsertTopic,17],[EventServiceUpsertTopic,7],[EventServiceUpsertTopic,9],[EventServiceUpsertTopic,1],[EventServiceUpsertTopic,15],[ > >> >> > > > > > EventServiceUpsertTopic,19 > >> >> > > > > > ],[EventServiceUpsertTopic,3],[EventServiceUpsertTopic,5] > >> >> > > > > > > >> >> > > > > > [2014-07-25 10:40:02,153] [INFO ] > [kafka-request-handler-0] > >> >> > > > > > [kafka.log.Log] Truncating log EventServiceUpsertTopic-19 > to > >> >> > offset > >> >> > > > > 8082. > >> >> > > > > > > >> >> > > > > > [2014-07-25 10:40:02,159] [INFO ] > [kafka-request-handler-0] > >> >> > > > > > [kafka.log.Log] Truncating log EventServiceUpsertTopic-5 > to > >> >> offset > >> >> > > 0. > >> >> > > > > > > >> >> > > > > > > >> >> > > > > > I have removed some irrelevant lines. As you can see, the > log > >> >> for > >> >> > > > > > EventServiceUpsertTopic-19 is being truncated, losing > >> messages > >> >> that > >> >> > > > have > >> >> > > > > > not yet been replicated to broker 1. I'm not sure exactly > >> what > >> >> the > >> >> > > > issue > >> >> > > > > > is. Maybe new requests should be completely blocked after > >> leader > >> >> > > > election > >> >> > > > > > until the new leader catches up to the messages that have > >> been > >> >> > acked > >> >> > > > and > >> >> > > > > it > >> >> > > > > > has not yet received. > >> >> > > > > > > >> >> > > > > > Thanks, > >> >> > > > > > > >> >> > > > > > Jad. > >> >> > > > > > > >> >> > > > > > > >> >> > > > > > On Fri, Jul 25, 2014 at 2:14 PM, Guozhang Wang < > >> >> wangg...@gmail.com > >> >> > > > >> >> > > > > wrote: > >> >> > > > > > > >> >> > > > > > > Hello Jad, > >> >> > > > > > > > >> >> > > > > > > I double-checked the source code again, and found that > >> >> actually > >> >> > the > >> >> > > > > > > preferred leader elector does consider whether the > selected > >> >> > replica > >> >> > > > is > >> >> > > > > in > >> >> > > > > > > ISR or not. This means that by the time the election is > >> >> > triggered, > >> >> > > > > > broker 1 > >> >> > > > > > > is added to ISR by broker 0. Could you check before step > >> 3, is > >> >> > > there > >> >> > > > > any > >> >> > > > > > > log entries on broker 0 adding broker 1 to ISR or > updating > >> HW > >> >> to > >> >> > > 975? > >> >> > > > > > > > >> >> > > > > > > > >> >> > > > > > > On Thu, Jul 24, 2014 at 4:21 PM, Jad Naous < > >> >> > > > jad.na...@appdynamics.com> > >> >> > > > > > > wrote: > >> >> > > > > > > > >> >> > > > > > > > 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. > >> >> > > > > > > > > >> >> > > > > > > > -- > >> >> > > > > > > > *Jad Naous* | Engineering | AppDynamics > >> >> > > > > > > > <http://www.appdynamics.com> > >> >> > > > > > > > > >> >> > > > > > > > >> >> > > > > > > > >> >> > > > > > > > >> >> > > > > > > -- > >> >> > > > > > > -- Guozhang > >> >> > > > > > > > >> >> > > > > > > >> >> > > > > > > >> >> > > > > > > >> >> > > > > > -- > >> >> > > > > > *Jad Naous* | Engineering | AppDynamics > >> >> > > > > > <http://www.appdynamics.com> > >> >> > > > > > > >> >> > > > > > >> >> > > > > > >> >> > > > > > >> >> > > > > -- > >> >> > > > > -- Guozhang > >> >> > > > > > >> >> > > > > >> >> > > > >> >> > > >> >> > > >> >> > > >> >> > -- > >> >> > -- Guozhang > >> >> > > >> >> > >> >> > >> >> > >> >> -- > >> >> *Jad Naous* | Engineering | AppDynamics > >> >> <http://www.appdynamics.com> > >> >> > >> > > >> > > >> > > >> > -- > >> > -- Guozhang > >> > > >> > >> > >> > >> -- > >> -- Guozhang > >> > > > > > > > > -- > > *Jad Naous* | Engineering | AppDynamics > > <http://www.appdynamics.com> > > > > > > -- > -- Guozhang > -- *Jad Naous* | Engineering | AppDynamics <http://www.appdynamics.com>
