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https://issues.apache.org/jira/browse/KAFKA-7104?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Anna Povzner updated KAFKA-7104:
--------------------------------
Description:
What we saw:
The follower fetches offset 116617, which it was able successfully append.
However, leader's log start offset in fetch request was 116753, which was
higher than fetched offset 116617. When replica fetcher thread tried to
increment log start offset to leader's log start offset, it failed with
OffsetOutOfRangeException:
[2018-06-23 00:45:37,409] ERROR [ReplicaFetcher replicaId=1002, leaderId=1001,
fetcherId=0] Error due to (kafka.server.ReplicaFetcherThread)
kafka.common.KafkaException: Error processing data for partition X-N offset
116617
Caused by: org.apache.kafka.common.errors.OffsetOutOfRangeException: Cannot
increment the log start offset to 116753 of partition X-N since it is larger
than the high watermark 116619
In leader's log, we see that log start offset was incremented almost at the
same time (within one 100 ms or so).
[2018-06-23 00:45:37,339] INFO Incrementing log start offset of partition X-N
to 116753 in dir /kafka/kafka-logs (kafka.log.Log)
In leader's logic: ReplicaManager#ReplicaManager first calls readFromLocalLog()
that reads from local log and returns LogReadResult that contains fetched data
and leader's log start offset and HW. However, it then calls
ReplicaManager#updateFollowerLogReadResults() which may move leader's log start
offset and update leader's log start offset and HW in fetch response. If
deleteRecords() happens in between, it is possible that log start offset may
move beyond fetched offset. Or possibly, the leader moves log start offset
because of deleting old log segments. Basically, the issue is that log start
offset can move between records are read from the log and LogReadResult is
updated with new log start offset. As a result, fetch response may contain
fetched data but leader's log start offset in the response could be set beyond
fetched offset (and indicate the state on leader that fetched data does not
actually exist anymore on leader).
When a follower receives such fetch response, it will first append, then move
it's HW no further than its LEO, which maybe less than leader's log start
offset in fetch response, and then call
`replica.maybeIncrementLogStartOffset(leaderLogStartOffset)` which will throw
OffsetOutOfRangeException exception causing the fetcher thread to stop.
Note that this can happen if the follower is not in ISR, otherwise the leader
will not move its log start offsets beyond follower's HW.
*Suggested fix:*
1) Since ReplicaFetcher bounds follower's HW to follower's LEO, we should also
bound follower's log start offset to its LEO. In this situation, the follower's
log start offset will be updated to LEO.
2) In addition to #1, we could try to make sure that leader builds fetch
response based on the state of the log as of time of reading data from replica
(but including moving leader's HW based on the follower's fetch). That could be
another JIRA potentially, since the fix could be more involved.
was:
What we saw:
The follower fetches offset 116617, which it was able successfully append.
However, leader's log start offset in fetch request was 116753, which was
higher than fetched offset 116617. When replica fetcher thread tried to
increment log start offset to leader's log start offset, it failed with
OffsetOutOfRangeException:
[2018-06-23 00:45:37,409] ERROR [ReplicaFetcher replicaId=1002, leaderId=1001,
fetcherId=0] Error due to (kafka.server.ReplicaFetcherThread)
kafka.common.KafkaException: Error processing data for partition X-N offset
116617
Caused by: org.apache.kafka.common.errors.OffsetOutOfRangeException: Cannot
increment the log start offset to 116753 of partition X-N since it is larger
than the high watermark 116619
In leader's log, we see that log start offset was incremented almost at the
same time (within one 100 ms or so).
[2018-06-23 00:45:37,339] INFO Incrementing log start offset of partition X-N
to 116753 in dir /kafka/kafka-logs (kafka.log.Log)
In leader's logic: ReplicaManager#ReplicaManager first calls readFromLocalLog()
that reads from local log and returns LogReadResult that contains fetched data
and leader's log start offset and HW. However, it then calls
ReplicaManager#updateFollowerLogReadResults() that may move leader's log start
offset and update leader's log start offset and HW in fetch response. If
deleteRecords() happens in between, it is possible that log start offset may
move beyond fetched offset. As a result, fetch response will contain fetched
data but log start offset that is beyond fetched offset (and indicate the state
on leader that fetched data does not actually exist anymore on leader).
When a follower receives such fetch response, it will first append, then move
it's HW no further than its LEO, which maybe less than leader's log start
offset in fetch response, and then call
`replica.maybeIncrementLogStartOffset(leaderLogStartOffset)` which will throw
OffsetOutOfRangeException exception causing the fetcher thread to stop.
*Suggested fix:*
If the leader moves log start offset beyond fetched offset,
ReplicaManager#updateFollowerLogReadResults() should update the log read
result with OFFSET_OUT_OF_RANGE error, which will cause the follower to reset
fetch offset to leader's log start offset.
> ReplicaFetcher thread may die because of inconsistent log start offset in
> fetch response
> ----------------------------------------------------------------------------------------
>
> Key: KAFKA-7104
> URL: https://issues.apache.org/jira/browse/KAFKA-7104
> Project: Kafka
> Issue Type: Bug
> Affects Versions: 1.0.0, 1.1.0
> Reporter: Anna Povzner
> Assignee: Anna Povzner
> Priority: Major
>
> What we saw:
> The follower fetches offset 116617, which it was able successfully append.
> However, leader's log start offset in fetch request was 116753, which was
> higher than fetched offset 116617. When replica fetcher thread tried to
> increment log start offset to leader's log start offset, it failed with
> OffsetOutOfRangeException:
> [2018-06-23 00:45:37,409] ERROR [ReplicaFetcher replicaId=1002,
> leaderId=1001, fetcherId=0] Error due to (kafka.server.ReplicaFetcherThread)
> kafka.common.KafkaException: Error processing data for partition X-N offset
> 116617
> Caused by: org.apache.kafka.common.errors.OffsetOutOfRangeException: Cannot
> increment the log start offset to 116753 of partition X-N since it is larger
> than the high watermark 116619
>
> In leader's log, we see that log start offset was incremented almost at the
> same time (within one 100 ms or so).
> [2018-06-23 00:45:37,339] INFO Incrementing log start offset of partition X-N
> to 116753 in dir /kafka/kafka-logs (kafka.log.Log)
>
> In leader's logic: ReplicaManager#ReplicaManager first calls
> readFromLocalLog() that reads from local log and returns LogReadResult that
> contains fetched data and leader's log start offset and HW. However, it then
> calls ReplicaManager#updateFollowerLogReadResults() which may move leader's
> log start offset and update leader's log start offset and HW in fetch
> response. If deleteRecords() happens in between, it is possible that log
> start offset may move beyond fetched offset. Or possibly, the leader moves
> log start offset because of deleting old log segments. Basically, the issue
> is that log start offset can move between records are read from the log and
> LogReadResult is updated with new log start offset. As a result, fetch
> response may contain fetched data but leader's log start offset in the
> response could be set beyond fetched offset (and indicate the state on leader
> that fetched data does not actually exist anymore on leader).
> When a follower receives such fetch response, it will first append, then move
> it's HW no further than its LEO, which maybe less than leader's log start
> offset in fetch response, and then call
> `replica.maybeIncrementLogStartOffset(leaderLogStartOffset)` which will throw
> OffsetOutOfRangeException exception causing the fetcher thread to stop.
> Note that this can happen if the follower is not in ISR, otherwise the leader
> will not move its log start offsets beyond follower's HW.
>
> *Suggested fix:*
> 1) Since ReplicaFetcher bounds follower's HW to follower's LEO, we should
> also bound follower's log start offset to its LEO. In this situation, the
> follower's log start offset will be updated to LEO.
> 2) In addition to #1, we could try to make sure that leader builds fetch
> response based on the state of the log as of time of reading data from
> replica (but including moving leader's HW based on the follower's fetch).
> That could be another JIRA potentially, since the fix could be more involved.
>
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