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Posted to jira@kafka.apache.org by "Guozhang Wang (Jira)" <ji...@apache.org> on 2021/09/09 00:09:00 UTC
[jira] [Commented] (KAFKA-13272) KStream offset stuck after brokers
outage
[ https://issues.apache.org/jira/browse/KAFKA-13272?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17412242#comment-17412242 ]
Guozhang Wang commented on KAFKA-13272:
---------------------------------------
Hello [~fmethot], I looked at the ticket and I suspect it is caused by the same issue as reported in https://issues.apache.org/jira/browse/KAFKA-13174. In a quick sum, this seems to be a broker-side issue that after an unclean shutdown the producer's dangling txn was not yet aborted, and hence causing the consumer to not be able to consume forward.
Note that by default, on Streams the transaction timeout defaults to 10 secs (please also double check that you did not override this config, "transaction.timeout.ms"), i.e. after there's no activity on that dangling transaction the broker should abort proactively that transaction so that consumers can see the txn marker and proceed. However, after the broker's unclean shutdown, that broker seems not be able to abort that txn after the timeout has elapsed.
> KStream offset stuck after brokers outage
> -----------------------------------------
>
> Key: KAFKA-13272
> URL: https://issues.apache.org/jira/browse/KAFKA-13272
> Project: Kafka
> Issue Type: Bug
> Components: streams
> Affects Versions: 2.8.0
> Environment: Kafka running on Kubernetes
> centos
> Reporter: F Méthot
> Priority: Major
>
> Our KStream app offset stay stuck on 1 partition after outage possibly when exactly_once is enabled.
> Running with KStream 2.8, kafka broker 2.8,
> 3 brokers.
> commands topic is 10 partitions (replication 2, min-insync 2)
> command-expiry-store-changelog topic is 10 partitions (replication 2, min-insync 2)
> events topic is 10 partitions (replication 2, min-insync 2)
> with this topology
> Topologies:
>
> {code:java}
> Sub-topology: 0
> Source: KSTREAM-SOURCE-0000000000 (topics: [commands])
> --> KSTREAM-TRANSFORM-0000000001
> Processor: KSTREAM-TRANSFORM-0000000001 (stores: [])
> --> KSTREAM-TRANSFORM-0000000002
> <-- KSTREAM-SOURCE-0000000000
> Processor: KSTREAM-TRANSFORM-0000000002 (stores: [command-expiry-store])
> --> KSTREAM-SINK-0000000003
> <-- KSTREAM-TRANSFORM-0000000001
> Sink: KSTREAM-SINK-0000000003 (topic: events)
> <-- KSTREAM-TRANSFORM-0000000002
> {code}
> h3.
> h3. Attempt 1 at reproducing this issue
>
> Our stream app runs with processing.guarantee *exactly_once*
> After a Kafka test outage where all 3 brokers pod were deleted at the same time,
> Brokers restarted and initialized succesfuly.
> When restarting the topology above, one of the tasks would never initialize fully, the restore phase would keep outputting this messages every few minutes:
>
> {code:java}
> 2021-08-16 14:20:33,421 INFO stream-thread [commands-processor-51b0a534-34b6-47a4-bd9c-c57b6ecb8665-StreamThread-1] Restoration in progress for 1 partitions. {commands-processor-expiry-store-changelog-8: position=11775908, end=11775911, totalRestored=2002076} [commands-processor-51b0a534-34b6-47a4-bd9c-c57b6ecb8665-StreamThread-1] (org.apache.kafka.streams.processor.internals.StoreChangelogReader)
> {code}
> Task for partition 8 would never initialize, no more data would be read from the source commands topic for that partition.
>
> In an attempt to recover, we restarted the stream app with stream processing.guarantee back to at_least_once, than it proceed with reading the changelog and restoring partition 8 fully.
> But we noticed afterward, for the next hour until we rebuilt the system, that partition 8 from command-expiry-store-changelog would not be cleaned/compacted by the log cleaner/compacter compared to other partitions. (could be unrelated, because we have seen that before)
> So we resorted to delete/recreate our command-expiry-store-changelog topic and events topic and regenerate it from the commands, reading from beginning.
> Things went back to normal
> h3. Attempt 2 at reproducing this issue
> kstream runs with *exactly-once*
> We force-deleted all 3 pod running kafka.
> After that, one of the partition can’t be restored. (like reported in previous attempt)
> For that partition, we noticed these logs on the broker
> {code:java}
> [2021-08-27 17:45:32,799] INFO [Transaction Marker Channel Manager 1002]: Couldn’t find leader endpoint for partitions Set(__consumer_offsets-11, command-expiry-store-changelog-9) while trying to send transaction markers for commands-processor-0_9, these partitions are likely deleted already and hence can be skipped (kafka.coordinator.transaction.TransactionMarkerChannelManager){code}
> Then
> - we stop the kstream app,
> - restarted kafka brokers cleanly
> - Restarting the Kstream app,
> Those logs messages showed up on the kstream app log:
>
> {code:java}
> 2021-08-27 18:34:42,413 INFO [Consumer clientId=commands-processor-76602c87-f682-4648-859b-8fa9b6b937f3-StreamThread-1-consumer, groupId=commands-processor] The following partitions still have unstable offsets which are not cleared on the broker side: [commands-9], this could be either transactional offsets waiting for completion, or normal offsets waiting for replication after appending to local log [commands-processor-76602c87-f682-4648-859b-8fa9b6b937f3-StreamThread-1] (org.apache.kafka.clients.consumer.internals.ConsumerCoordinator)
>
> {code}
> This would cause our processor to not consume from that specific source topic-partition.
> Deleting downstream topic and replaying data would NOT fix the issue (EXACTLY_ONCE or AT_LEAST_ONCE)
> Workaround found:
> Deleted the group associated with the processor, and restarted the kstream application, application went on to process data normally. (We have resigned to use AT_LEAST_ONCE for now )
> KStream config :
> {code:java}
> StreamsConfig.RETRY_BACKOFF_MS_CONFIG, 2000
> StreamsConfig.REPLICATION_FACTOR_CONFIG, 2
> StreamsConfig.COMMIT_INTERVAL_MS_CONFIG, 1000
> StreamsConfig.CACHE_MAX_BYTES_BUFFERING_CONFIG, 24MB
> ConsumerConfig.AUTO_OFFSET_RESET_CONFIG), “earliest”
> StreamsConfig.PROCESSING_GUARANTEE_CONFIG, StreamsConfig.EXACTLY_ONCE (now AT_LEAST_ONCE)
> producer.delivery.timeout.ms=120000
> consumer.session.timeout.ms=30000
> consumer.heartbeat.interval.ms=10000
> consumer.max.poll.interval.ms=300000
> num.stream.threads=1{code}
>
> h3. Attempt 3
> kstream processor now running with *at-least-once*
> reprocess the entire source topic.
> Everything runs stable
> We force-deleted all 3 pod running kafka.
> Then services comes back up but there is that same error on kstream app:
> {code:java}
> 2021-09-03 19:18:39,414 INFO [Consumer clientId=commands-processor-76602c87-f682-4648-859b-8fa9b6b937f3-StreamThread-1-consumer, groupId=commands-processor] The following partitions still have unstable offsets which are not cleared on the broker side: [commands-9], this could be either transactional offsets waiting for completion, or normal offsets waiting for replication after appending to local log
> {code}
> Got it back processing by
> * Stopped the kstream app,
> * Took notes of the offset
> * deleted the group for kstream app
> * manually created the same group and set the offset to were they were for each partition.
> * restarted the kstream app and processing resumed normally.
>
>
>
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