[jira] [Created] (KAFKA-7704) kafka.server.ReplicaFetechManager.MaxLag.Replica metric is reported incorrectly

["Yu Yang (JIRA)" <ji...@apache.org>]

Yu Yang created KAFKA-7704:
------------------------------

             Summary: kafka.server.ReplicaFetechManager.MaxLag.Replica metric is reported incorrectly
                 Key: KAFKA-7704
                 URL: https://issues.apache.org/jira/browse/KAFKA-7704
             Project: Kafka
          Issue Type: Bug
          Components: metrics
    Affects Versions: 2.1.0
            Reporter: Yu Yang
         Attachments: Screen Shot 2018-12-03 at 4.33.35 PM.png

We deployed kafka 2.1, and noticed a jump in kafka.server.ReplicaFetcherManager.MaxLag.Replica metric. At the same time, there is no under-replicated partitions. 

The initial analysis showed that kafka 2.1.0 does not report metric correctly for topics that have no incoming traffic right now, but had traffic earlier. For those topics, ReplicaFetcherManager will consider the maxLag be the latest offset. 

For instance, we have a topic *test_topic*: 

{code}
[root@kafkabroker03002:/mnt/kafka/test_topic-0]# ls -l
total 8
-rw-rw-r-- 1 kafka kafka 10485760 Dec  4 00:13 00000000099043947579.index
-rw-rw-r-- 1 kafka kafka        0 Sep 23 03:01 00000000099043947579.log
-rw-rw-r-- 1 kafka kafka       10 Dec  4 00:13 00000000099043947579.snapshot
-rw-rw-r-- 1 kafka kafka 10485756 Dec  4 00:13 00000000099043947579.timeindex
-rw-rw-r-- 1 kafka kafka        4 Dec  4 00:13 leader-epoch-checkpoint
{code}

kafka reports ReplicaFetcherManager.MaxLag.Replica be 99043947579

 !Screen Shot 2018-12-03 at 4.33.35 PM.png|width=720px! 





--
This message was sent by Atlassian JIRA
(v7.6.3#76005)