[jira] [Commented] (KAFKA-8733) Offline partitions occur when leader's disk is slow in reads while responding to follower fetch requests.
[
https://issues.apache.org/jira/browse/KAFKA-8733?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17281204#comment-17281204
]
Ajay Patel commented on KAFKA-8733:
---
Is there any update on this or on
[KIP-501|https://cwiki.apache.org/confluence/display/KAFKA/KIP-501+Avoid+out-of-sync+or+offline+partitions+when+follower+fetch+requests+not+processed+in+time]?
Unfortunately the {{replica.lag.time}} workaround isn't exactly viable for us
as we predominantly see this issue when certain zones of our clusters have
complete outages. Enabling unclean leader election certainly resolves the
issue, but leaving the configuration on by default poses a significant risk of
data loss that we'd like really like to avoid. Thanks!
> 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
>Priority: Critical
> Attachments: weighted-io-time-2.png, wio-time.png
>
>
> 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 false.
>
> {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 isr
> else result
> }
> val logReadResults = readFromLog()
> {code}
> Attached the graphs of disk weighted io time stats when this issue occurred.
> I will raise [KIP-501|https://s.apache.org/jhbpn] describing options on how
> to handle this scenario.
>
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[jira] [Commented] (KAFKA-8733) Offline partitions occur when leader's disk is slow in reads while responding to follower fetch requests.
[
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]
GEORGE LI commented on KAFKA-8733:
--
for lossy clusters, setting unclean.leader.election.enable=true will help. we
are also rolling out replica.lag.time.max.ms=3 .
> 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
>Priority: Critical
> Attachments: weighted-io-time-2.png, wio-time.png
>
>
> 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 false.
>
> {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 isr
> else result
> }
> val logReadResults = readFromLog()
> {code}
> Attached the graphs of disk weighted io time stats when this issue occurred.
> I will raise [KIP-501|https://s.apache.org/jhbpn] describing options on how
> to handle this scenario.
>
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[jira] [Commented] (KAFKA-8733) Offline partitions occur when leader's disk is slow in reads while responding to follower fetch requests.
[
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]
Ming Liu commented on KAFKA-8733:
-
One observation is after moving to 2.5 (so
_[replica.lag.time.max.ms|http://replica.lag.time.max.ms/]_ is changed from 10
second to 30 seconds), Offline partitions when leader's disk went bad occurs
much less frequently.
> 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
>Priority: Critical
> Attachments: weighted-io-time-2.png, wio-time.png
>
>
> 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 false.
>
> {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 isr
> else result
> }
> val logReadResults = readFromLog()
> {code}
> Attached the graphs of disk weighted io time stats when this issue occurred.
> I will raise [KIP-501|https://s.apache.org/jhbpn] describing options on how
> to handle this scenario.
>
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[jira] [Commented] (KAFKA-8733) Offline partitions occur when leader's disk is slow in reads while responding to follower fetch requests.
[
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]
Flavien Raynaud commented on KAFKA-8733:
Good point, we've not tried this in production. We haven't had enough
occurrences of this issue (thankfully :p) to know how long it takes between
"leader has disk issues and slow reads" and "leader dies because of disk
failure, revoking leadership", and what would be a good compromise with the "a
follower is genuinely falling behind" case.
We can try this for some of our clusters with lower consistency requirements,
but it may be weeks/months before we hit this issue happen again.
> 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
>Priority: Critical
> Attachments: weighted-io-time-2.png, wio-time.png
>
>
> 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 false.
>
> {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 isr
> else result
> }
> val logReadResults = readFromLog()
> {code}
> Attached the graphs of disk weighted io time stats when this issue occurred.
> I will raise [KIP-501|https://s.apache.org/jhbpn] describing options on how
> to handle this scenario.
>
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[jira] [Commented] (KAFKA-8733) Offline partitions occur when leader's disk is slow in reads while responding to follower fetch requests.
[
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]
Cheng Tan commented on KAFKA-8733:
--
[~flavr] increasing the lag timeout to a fairly large value so that the
leaders do not remove replicas from the ISR so aggressively
> 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
>Priority: Critical
> Attachments: weighted-io-time-2.png, wio-time.png
>
>
> 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 false.
>
> {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 isr
> else result
> }
> val logReadResults = readFromLog()
> {code}
> Attached the graphs of disk weighted io time stats when this issue occurred.
> I will raise [KIP-501|https://s.apache.org/jhbpn] describing options on how
> to handle this scenario.
>
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[
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]
Flavien Raynaud commented on KAFKA-8733:
Hi [~d8tltanc], thank you for looking into this! It's definitely still an issue
for us. Even though it happens quite rarely, it is really painful when it does
happen.
We haven't found any decent way to mitigate this issue, we have only built some
internal tooling to make recovery faster (identifying impacted partitions,
making sure the replica-set of said partitions does not contain empty replicas,
enabling unclear leader election if needed, and reassigning to a replacement
broker).
> 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
>Priority: Critical
> Attachments: weighted-io-time-2.png, wio-time.png
>
>
> 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 false.
>
> {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 isr
> else result
> }
> val logReadResults = readFromLog()
> {code}
> Attached the graphs of disk weighted io time stats when this issue occurred.
> I will raise [KIP-501|https://s.apache.org/jhbpn] describing options on how
> to handle this scenario.
>
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[
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]
Cheng Tan commented on KAFKA-8733:
--
Hi [~satish.duggana], [~flavr], and [~mingaliu],
We are actively investigating this issue and KIP. Meanwhile, have you worked
out any way to mitigate this issue, especially the case below?
{quote}But we found an issue of partitions going offline even though follower
replicas try their best to fetch from the leader replica. Sometimes, the
leader replica may take time to process the fetch requests while reading logs,
it makes follower replicas out of sync even though followers send fetch
requests within _[replica.lag.time.max.ms|http://replica.lag.time.max.ms/]_
duration. It may even lead to offline partitions when in-sync replicas go below
_min.insync.replicas_ count. We observed this behavior multiple times in our
clusters and making partitions offline.
{quote}
> 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
>Priority: Critical
> Attachments: weighted-io-time-2.png, wio-time.png
>
>
> 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 false.
>
> {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 isr
> else result
> }
> val logReadResults = readFromLog()
> {code}
> Attached the graphs of disk weighted io time stats when this issue occurred.
> I will raise [KIP-501|https://s.apache.org/jhbpn] describing options on how
> to handle this scenario.
>
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[
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]
Flavien Raynaud commented on KAFKA-8733:
Has there been any update regarding this issue/the associated KIP? I can see
that the thread on the mailing list has been empty for the past 6 months. It
has happened again recently when one broker ecountered a disk failure, causing
a bunch of offline partitions. Happy to help in any way we can 😄
> 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
>Priority: Critical
> Attachments: weighted-io-time-2.png, wio-time.png
>
>
> 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 false.
>
> {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 isr
> else result
> }
> val logReadResults = readFromLog()
> {code}
> Attached the graphs of disk weighted io time stats when this issue occurred.
> I will raise [KIP-501|https://s.apache.org/jhbpn] describing options on how
> to handle this scenario.
>
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[
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]
Ming Liu commented on KAFKA-8733:
-
We (at Twitter) also saw this issue almost every month and it is annoying.
Given it is availability loss, we have to react very fast and set unclean
leader election.
Given when this happens, we should also starts the disk/host swap operation. It
seems the low level system metrics or fetch latency metrics are good metrics to
monitor such scenario. We should add a metrics monitor such exact scenario?
Also another observation, given we are using min-ISR=2. So the last replica
kicked out of ISR should have the same HW as the eventual offline leader. So
when you set the unclean leader election, there is 50% chance you incur a data
loss(if the election doesn't select that replica).
> 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
>Priority: Critical
> Attachments: weighted-io-time-2.png, wio-time.png
>
>
> 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 false.
>
> {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 isr
> else result
> }
> val logReadResults = readFromLog()
> {code}
> Attached the graphs of disk weighted io time stats when this issue occurred.
> I will raise [KIP-501|https://s.apache.org/jhbpn] describing options on how
> to handle this scenario.
>
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[jira] [Commented] (KAFKA-8733) Offline partitions occur when leader's disk is slow in reads while responding to follower fetch requests.
[
https://issues.apache.org/jira/browse/KAFKA-8733?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17020743#comment-17020743
]
Satish Duggana commented on KAFKA-8733:
---
[~flavr] Thanks for letting us know that you are also encountering the same
issue. There is a discussion thread[1] on dev@kafka mailing list. Waiting for
others to comment/close the discussion and start the voting mail thread.
1.
[https://lists.apache.org/thread.html/243dcc267f7ba79f508bcc4cbaa77a41d2454cba9359173bb08e875e%40%3Cdev.kafka.apache.org%3E]
> 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
>Priority: Critical
> Attachments: weighted-io-time-2.png, wio-time.png
>
>
> 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 false.
>
> {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 isr
> else result
> }
> val logReadResults = readFromLog()
> {code}
> Attached the graphs of disk weighted io time stats when this issue occurred.
> I will raise [KIP-501|https://s.apache.org/jhbpn] describing options on how
> to handle this scenario.
>
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[jira] [Commented] (KAFKA-8733) Offline partitions occur when leader's disk is slow in reads while responding to follower fetch requests.
[
https://issues.apache.org/jira/browse/KAFKA-8733?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17020083#comment-17020083
]
Flavien Raynaud commented on KAFKA-8733:
We've seen offline partitions happening for the same reason in one of our
clusters too, where only the broker leader for the offline partitions was
having disk issues. It looks like there has not been much progress/look on the
PR submitted since December 9th. Is there anything blocking this change from
moving forward? :)
> 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
>Priority: Critical
> Attachments: weighted-io-time-2.png, wio-time.png
>
>
> 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 false.
>
> {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 isr
> else result
> }
> val logReadResults = readFromLog()
> {code}
> Attached the graphs of disk weighted io time stats when this issue occurred.
> I will raise [KIP-501|https://s.apache.org/jhbpn] describing options on how
> to handle this scenario.
>
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[jira] [Commented] (KAFKA-8733) Offline partitions occur when leader's disk is slow in reads while responding to follower fetch requests.
[
https://issues.apache.org/jira/browse/KAFKA-8733?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16991521#comment-16991521
]
ASF GitHub Bot commented on KAFKA-8733:
---
satishd commented on pull request #7802: [WIP]KAFKA-8733 Initial sketch of the
solution mentioned in KIP-501.
URL: https://github.com/apache/kafka/pull/7802
Follower Replica on leader partition maintains pending fetch requests which
are to be processed for fetch offsets >= log-end-offset in
earlier fetch request. Follower replica is considered to be insync if there
are oending fetch requests.
*More detailed description of your change,
if necessary. The PR title and PR message become
the squashed commit message, so use a separate
comment to ping reviewers.*
*Summary of testing strategy (including rationale)
for the feature or bug fix. Unit and/or integration
tests are expected for any behaviour change and
system tests should be considered for larger changes.*
### Committer Checklist (excluded from commit message)
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- [ ] Verify test coverage and CI build status
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> 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
>Priority: Critical
> Attachments: weighted-io-time-2.png, wio-time.png
>
>
> 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 false.
>
> {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 isr
> else result
> }
> val logReadResults = readFromLog()
> {code}
> Attached the graphs of disk weighted io time stats when this issue occurred.
> I will raise [KIP-501|https://s.apache.org/jhbpn] describing options on how
> to handle this scenario.
>
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