[KAFKA-16511] Leaking tiered segments

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.7.0
• Fix Version/s: 3.8.0, 3.7.1
• Component/s: Tiered-Storage
• Labels: tiered-storage
• Assignee: Kamal Chandraprakash
• Reporter: Francois Visconte
• Created: 11/Apr/24 12:57
• Updated: 08/May/24 07:32
• Resolved: 08/May/24 07:22

Description

I have some topics there were not written since a few days (having 12h retention) where some data remains on tiered storage (in our case S3) and they are never deleted.

 

Looking at the log history, it appears that we never even tried to delete these segments:

When looking at one of the non-leaking segment, I get the following interesting messages:

 

"2024-04-02T10:30:45.265Z","""kafka""","""10039""","[RemoteLogManager=10039 partition=5G8Ai8kBSwmQ3Ln4QRY5rA:topic1_3543-764] Deleted remote log segment RemoteLogSegmentId{topicIdPartition=5G8Ai8kBSwmQ3Ln4QRY5rA:topic1_3543-764, id=fqGng3UURCG3-v4lETeLKQ} due to leader-epoch-cache truncation. Current earliest-epoch-entry: EpochEntry(epoch=8, startOffset=2980106), segment-end-offset: 2976819 and segment-epochs: [5]"
"2024-04-02T10:30:45.242Z","""kafka""","""10039""","Deleting log segment data for completed successfully RemoteLogSegmentMetadata{remoteLogSegmentId=RemoteLogSegmentId
{topicIdPartition=5G8Ai8kBSwmQ3Ln4QRY5rA:topic1_3543-764, id=fqGng3UURCG3-v4lETeLKQ}
, startOffset=2968418, endOffset=2976819, brokerId=10029, maxTimestampMs=1712009754536, eventTimestampMs=1712013411147, segmentLeaderEpochs={5=2968418}, segmentSizeInBytes=536351075, customMetadata=Optional.empty, state=COPY_SEGMENT_FINISHED}"
"2024-04-02T10:30:45.144Z","""kafka""","""10039""","Deleting log segment data for RemoteLogSegmentMetadata{remoteLogSegmentId=RemoteLogSegmentId
{topicIdPartition=5G8Ai8kBSwmQ3Ln4QRY5rA:topic1_3543-764, id=fqGng3UURCG3-v4lETeLKQ}
, startOffset=2968418, endOffset=2976819, brokerId=10029, maxTimestampMs=1712009754536, eventTimestampMs=1712013411147, segmentLeaderEpochs={5=2968418}, segmentSizeInBytes=536351075, customMetadata=Optional.empty, state=COPY_SEGMENT_FINISHED}"
"2024-04-01T23:16:51.157Z","""kafka""","""10029""","[RemoteLogManager=10029 partition=5G8Ai8kBSwmQ3Ln4QRY5rA:topic1_3543-764] Copied 00000000000002968418.log to remote storage with segment-id: RemoteLogSegmentId{topicIdPartition=5G8Ai8kBSwmQ3Ln4QRY5rA:topic1_3543-764, id=fqGng3UURCG3-v4lETeLKQ}"
"2024-04-01T23:16:51.147Z","""kafka""","""10029""","Copying log segment data completed successfully, metadata: RemoteLogSegmentMetadata{remoteLogSegmentId=RemoteLogSegmentId
{topicIdPartition=5G8Ai8kBSwmQ3Ln4QRY5rA:topic1_3543-764, id=fqGng3UURCG3-v4lETeLKQ}
, startOffset=2968418, endOffset=2976819, brokerId=10029, maxTimestampMs=1712009754536, eventTimestampMs=1712013397319, segmentLeaderEpochs={5=2968418}, segmentSizeInBytes=536351075, customMetadata=Optional.empty, state=COPY_SEGMENT_STARTED}"
"2024-04-01T23:16:37.328Z","""kafka""","""10029""","Copying log segment data, metadata: RemoteLogSegmentMetadata{remoteLogSegmentId=RemoteLogSegmentId
{topicIdPartition=5G8Ai8kBSwmQ3Ln4QRY5rA:topic1_3543-764, id=fqGng3UURCG3-v4lETeLKQ}
, startOffset=2968418, endOffset=2976819, brokerId=10029, maxTimestampMs=1712009754536, eventTimestampMs=1712013397319, segmentLeaderEpochs={5=2968418}, segmentSizeInBytes=536351075, customMetadata=Optional.empty, state=COPY_SEGMENT_STARTED}"

 

Which looks right because we can see logs from both the plugin and remote log manager indicating that the remote log segment was removed.

Now if I look on one of the leaked segment, here is what I see

 

"2024-04-02T00:43:33.834Z","""kafka""","""10001""","[RemoteLogManager=10001 partition=5G8Ai8kBSwmQ3Ln4QRY5rA:topic1_3543-765] Copied 00000000000002971163.log to remote storage with segment-id: RemoteLogSegmentId{topicIdPartition=5G8Ai8kBSwmQ3Ln4QRY5rA:topic1_3543-765, id=8dP13VDYSaiFlubl9SNBTQ}"
"2024-04-02T00:43:33.822Z","""kafka""","""10001""","Copying log segment data completed successfully, metadata: RemoteLogSegmentMetadata{remoteLogSegmentId=RemoteLogSegmentId
{topicIdPartition=5G8Ai8kBSwmQ3Ln4QRY5rA:topic1_3543-765, id=8dP13VDYSaiFlubl9SNBTQ}
, startOffset=2971163, endOffset=2978396, brokerId=10001, maxTimestampMs=1712010648756, eventTimestampMs=1712018599981, segmentLeaderEpochs={7=2971163}, segmentSizeInBytes=459778940, customMetadata=Optional.empty, state=COPY_SEGMENT_STARTED}"
"2024-04-02T00:43:20.003Z","""kafka""","""10001""","Copying log segment data, metadata: RemoteLogSegmentMetadata{remoteLogSegmentId=RemoteLogSegmentId
{topicIdPartition=5G8Ai8kBSwmQ3Ln4QRY5rA:topic1_3543-765, id=8dP13VDYSaiFlubl9SNBTQ}
, startOffset=2971163, endOffset=2978396, brokerId=10001, maxTimestampMs=1712010648756, eventTimestampMs=1712018599981, segmentLeaderEpochs={7=2971163}, segmentSizeInBytes=459778940, customMetadata=Optional.empty, state=COPY_SEGMENT_STARTED}"
 

I have no errors whatsoever indicating that the remote log deletion was actually triggered and failed. 

I tried rolling restarting my cluster to see if refreshing remote log metadata from fresh state would help but that did not help. Removing segments in tiered storage and restarting brokers after did not help either.

Now if I use offset shell to get earliest and latest offsets for both partitions

 

$ /opt/kafka-3.7.0/bin/kafka-get-offsets.sh  --bootstrap-server $KAFKA_CONNECT_STR --topic topic1 --partitions 764,765 -
-time -2 
raw_spans_datadog_3543:764:2980106
raw_spans_datadog_3543:765:2976337
$ $ /opt/kafka-3.7.0/bin/kafka-get-offsets.sh  --bootstrap-server $KAFKA_CONNECT_STR --topic topic1 --partitions 764,765 --time -1
raw_spans_datadog_3543:764:2980106
raw_spans_datadog_3543:765:2978397

We can see that despite the retention period being largely exceeded, there are 2060 offsets that are never expiring.

One thing that might have triggered this bug was the fact that some nodes were replaced with fresh disk in between the segment creation and their expiration.

The issue happened on 418 partitions out of 4513, ~9% of partitions.

Issue Links

• is a child of: KAFKA-15420 Kafka Tiered Storage V1
• links to: GitHub Pull Request #15817