Yes，it is possible.
Think of this :
1 - Consumer A and consumer B ( A and B with the same consumer group.id
and enable auto commit) consume a topic T with 2 partitions，and the
assignment is (A => T-0 , B => T-1)
2 - The application runs correctly when the records are sent to kafka at
a low speed. let's assume :
2-1) each consumer can process 5 records per second
2-2) the speed of records sent to topic T is 5/partition/second
=> so that each time the consumer can poll 5 records and process
correctly in one second.
3 - The speed of records sent to partiton T-0 increases to 500/second，so
consumer A can poll 500 records next time and 500/5 = 100s needed to
process.
4 - If the config - 'max.poll.interval.ms' of consumer is less than
100s，kafka broker will think consumer A is dead 100 seconds later even if A
is working hard and a rebalance will be invoked.
5 - Consumer B will take over both the two partitions in the next round
of balance and reprocess the records in T-0.
6 - Step 4 && 5 will keep going and never recover automatically.
Hope this helps
Jin, Yun <yun....@sap.com> 于2020年8月12日周三 下午5:18写道：
> Hi,
>
> Partition may be reassigned if the consumer is not reachable. Will
> partition reassignment cause same message being processed in parallel?
> Suppose if Kafka found consumer A is not reachable (maybe because of
> network problem), it assigns the partition to consumer B. But actually
> consumer A is still running, this may cause the situation that a same
> message is processed in parallel by consumer A and consumer B. If the logic
> in processing the message includes updating some database tables, we have
> to lock some rows first. If such parallel processing the same message can
> not happen, we needn't use lock.
> Appreciate if you can provide some information on this.
>
> Best regards,
> Yun
>
