Satish Duggana created KAFKA-8733:
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Summary: Offline partitions occur when leader's disk is slow in
reads while responding to follower fetch requests.
Key: KAFKA-8733
URL: https://issues.apache.org/jira/browse/KAFKA-8733
Project: Kafka
Issue Type: Bug
Components: core
Affects Versions: 1.1.2, 2.4.0
Reporter: Satish Duggana
Assignee: Satish Duggana
We found offline partitions issue multiple times on some of the hosts in our
clusters. After going through the broker logs and hosts’s disk stats, it looks
like this issue occurs whenever the read/write operations take more time on
that disk. In a particular case where read time is more than the
replica.lag.time.max.ms, follower replicas will be out of sync as their earlier
fetch requests are stuck while reading the local log and their fetch status is
not yet updated as mentioned in the below code of `ReplicaManager`. If there is
an issue in reading the data from the log for a duration more than
replica.lag.time.max.ms then all the replicas will be out of sync and partition
becomes offline if min.isr.replicas > 1 and unclean.leader.election is disabled.
{code:java}
def readFromLog(): Seq[(TopicPartition, LogReadResult)] = {
val result = readFromLocalLog( // this call took more than
`replica.lag.time.max.ms`
replicaId = replicaId,
fetchOnlyFromLeader = fetchOnlyFromLeader,
readOnlyCommitted = fetchOnlyCommitted,
fetchMaxBytes = fetchMaxBytes,
hardMaxBytesLimit = hardMaxBytesLimit,
readPartitionInfo = fetchInfos,
quota = quota,
isolationLevel = isolationLevel)
if (isFromFollower) updateFollowerLogReadResults(replicaId, result). // fetch
time gets updated here, but mayBeShrinkIsr should have been already called and
the replica is removed from sir
else result
}
val logReadResults = readFromLog()
{code}
I will raise a KIP describing options on how to handle this scenario.
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