Details
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Bug
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Status: Resolved
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Major
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Resolution: Fixed
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1.1.2
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None
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Flink 1.1.2
Kafka Broker 0.10.0
Hadoop 2.7.0
Description
*Original reported ticket title: Last kafka message gets consumed twice when restarting job*
There seem to be an issue with the offset management in Flink. When a job is stopped and startet again, a message from the previous offset is read again.
I enabled checkpoints (EXACTLY_ONCE) and FsStateBackend. I started with a new consumer group and emitted one record.
You can cleary see, that the consumer waits for a new record at offset 4848911, which is correct. After restarting, it consumes a record at 4848910, causing the record to be consumed more than once.
I checked the offset with the Kafka CMD tools, the commited offset in zookeeper is 4848910.
Here is my log output:
10:29:24,225 DEBUG org.apache.kafka.clients.NetworkClient - Initiating connection to node 2147482646 at hdp1:6667. 10:29:24,225 DEBUG org.apache.kafka.clients.consumer.internals.ConsumerCoordinator - Fetching committed offsets for partitions: [myTopic-0] 10:29:24,228 DEBUG org.apache.kafka.clients.NetworkClient - Completed connection to node 2147482646 10:29:24,234 DEBUG org.apache.kafka.clients.consumer.internals.ConsumerCoordinator - No committed offset for partition myTopic-0 10:29:24,238 DEBUG org.apache.kafka.clients.consumer.internals.Fetcher - Resetting offset for partition myTopic-0 to latest offset. 10:29:24,244 DEBUG org.apache.kafka.clients.consumer.internals.Fetcher - Fetched offset 4848910 for partition myTopic-0 10:29:24,245 TRACE org.apache.kafka.clients.consumer.internals.Fetcher - Added fetch request for partition myTopic-0 at offset 4848910 10:29:24,773 TRACE org.apache.kafka.clients.consumer.internals.Fetcher - Added fetch request for partition myTopic-0 at offset 4848910 10:29:25,276 TRACE org.apache.kafka.clients.consumer.internals.Fetcher - Added fetch request for partition myTopic-0 at offset 4848910 -- Inserting a new event here 10:30:22,447 TRACE org.apache.kafka.clients.consumer.internals.Fetcher - Adding fetched record for partition myTopic-0 with offset 4848910 to buffered record list 10:30:22,448 TRACE org.apache.kafka.clients.consumer.internals.Fetcher - Returning fetched records at offset 4848910 for assigned partition myTopic-0 and update position to 4848911 10:30:22,451 TRACE org.apache.kafka.clients.consumer.internals.Fetcher - Added fetch request for partition myTopic-0 at offset 4848911 10:30:22,953 TRACE org.apache.kafka.clients.consumer.internals.Fetcher - Added fetch request for partition myTopic-0 at offset 4848911 10:30:23,456 TRACE org.apache.kafka.clients.consumer.internals.Fetcher - Added fetch request for partition myTopic-0 at offset 4848911 10:30:23,887 INFO org.apache.flink.runtime.checkpoint.CheckpointCoordinator - Triggering checkpoint 6 @ 1473841823887 10:30:23,957 TRACE org.apache.kafka.clients.consumer.internals.Fetcher - Added fetch request for partition myTopic-0 at offset 4848911 10:30:23,996 INFO org.apache.flink.runtime.checkpoint.CheckpointCoordinator - Completed checkpoint 6 (in 96 ms) 10:30:24,196 TRACE org.apache.kafka.clients.consumer.internals.ConsumerCoordinator - Sending offset-commit request with {myTopic-0=OffsetAndMetadata{offset=4848910, metadata=''}} to Node(2147482646, hdp1, 6667) 10:30:24,204 DEBUG org.apache.kafka.clients.consumer.internals.ConsumerCoordinator - Committed offset 4848910 for partition myTopic-0 10:30:24,460 TRACE org.apache.kafka.clients.consumer.internals.Fetcher - Added fetch request for partition myTopic-0 at offset 4848911 10:30:24,963 TRACE org.apache.kafka.clients.consumer.internals.Fetcher - Added fetch request for partition myTopic-0 at offset 4848911 10:30:48,057 INFO org.apache.flink.runtime.blob.BlobServer - Stopped BLOB server at 0.0.0.0:2946 -- Restarting job 10:32:01,672 DEBUG org.apache.kafka.clients.NetworkClient - Initiating connection to node 2147482646 at hdp1:6667. 10:32:01,673 DEBUG org.apache.kafka.clients.consumer.internals.ConsumerCoordinator - Fetching committed offsets for partitions: [myTopic-0] 10:32:01,677 DEBUG org.apache.kafka.clients.NetworkClient - Completed connection to node 2147482646 // See below! Shouldn't the offset be 4848911? 10:32:01,682 DEBUG org.apache.kafka.clients.consumer.internals.Fetcher - Resetting offset for partition myTopic-0 to the committed offset 4848910 10:32:01,683 TRACE org.apache.kafka.clients.consumer.internals.Fetcher - Added fetch request for partition myTopic-0 at offset 4848910 10:32:01,685 DEBUG org.apache.kafka.clients.NetworkClient - Initiating connection to node 1001 at hdp1:6667. 10:32:01,687 DEBUG org.apache.kafka.clients.NetworkClient - Completed connection to node 1001 // Here record 4848910 gets consumed again! 10:32:01,707 TRACE org.apache.kafka.clients.consumer.internals.Fetcher - Adding fetched record for partition myTopic-0 with offset 4848910 to buffered record list 10:32:01,708 TRACE org.apache.kafka.clients.consumer.internals.Fetcher - Returning fetched records at offset 4848910 for assigned partition myTopic-0 and update position to 4848911 10:32:03,721 TRACE org.apache.kafka.clients.consumer.internals.Fetcher - Added fetch request for partition myTopic-0 at offset 4848911 10:32:04,224 TRACE org.apache.kafka.clients.consumer.internals.Fetcher - Added fetch request for partition myTopic-0 at offset 4848911 10:32:04,726 TRACE org.apache.kafka.clients.consumer.internals.Fetcher - Added fetch request for partition myTopic-0 at offset 4848911 10:32:04,894 INFO org.apache.flink.runtime.blob.BlobCache - Shutting down BlobCache 10:32:04,903 INFO org.apache.flink.runtime.blob.BlobServer - Stopped BLOB server at 0.0.0.0:3079
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