[ https://issues.apache.org/jira/browse/KAFKA-15572?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Lucian Ilie updated KAFKA-15572: -------------------------------- Affects Version/s: 3.0.0 (was: 3.3.1) (was: 3.4.1) > Race condition between future log dir roll and replace current with future > log during alterReplicaLogDirs > --------------------------------------------------------------------------------------------------------- > > Key: KAFKA-15572 > URL: https://issues.apache.org/jira/browse/KAFKA-15572 > Project: Kafka > Issue Type: Bug > Components: core > Affects Versions: 3.0.0 > Reporter: Lucian Ilie > Priority: Major > Attachments: kafka-alter-log-dir-nosuchfileexception.log > > Original Estimate: 48h > Remaining Estimate: 48h > > We are using a Kafka cluster with Zookeeper, deployed on top of Kubernetes, > using banzaicloud/koperator. > We have multiple disks per broker. > We are using Cruise Control remove disk operation in order to aggregate > multiple smaller disks into a single bigger disk. > When we do this, *the flush operation fails apparently randomly with > NoSuchFileException, while alterReplicaLogDirs is executed*. Attached a > sample of logs for the exception and the previous operations taking place. > Will further detail the cause of this issue. > Say we have 3 brokers: > * broker 101 with disks /kafka-logs1/kafka, /kafka-logs2/kafka and a bigger > disk /new-kafka-logs1/kafka > * broker 201 with same disks > * broker 301 with same disks > When Cruise Control executes a remove disk operation, it calls Kafka > "adminClient.alterReplicaLogDirs(replicaAssignment)" with such an assignment > as to move all data from /kafka-logs1/kafka and /kafka-logs2/kafka to > /new-kafka-logs1/kafka. > During the alter log dir operation, future logs are created (to move data > from e.g. "/kafka-logs1/kafka/topic-partition" to > "/new-kafka-logs1/kafka/topic-partition.hash-future"), data is moved and > finally the log dir will be renamed from > "/new-kafka-logs1/kafka/topic-partition.hash-future" to > "/new-kafka-logs1/kafka/topic-partition". This operation is started in > [UnifiedLog.renameDir|https://github.com/apache/kafka/blob/3.4/core/src/main/scala/kafka/log/UnifiedLog.scala#L713] > and is locked using the [UnifiedLog > lock|https://github.com/apache/kafka/blob/3.4/core/src/main/scala/kafka/log/UnifiedLog.scala#L268]. > The rename is then delegated to > [LocalLog.renameDir|https://github.com/apache/kafka/blob/3.4/core/src/main/scala/kafka/log/LocalLog.scala#L111-L113]. > This is the 1st code part that is involved in the race condition. > Meanwhile, log dirs can be rolled based on known conditions (e.g. getting > full), which will call > [UnifiedLog.roll|https://github.com/apache/kafka/blob/3.4/core/src/main/scala/kafka/log/UnifiedLog.scala#L1547], > which is locked using the [UnifiedLog > lock|https://github.com/apache/kafka/blob/3.4/core/src/main/scala/kafka/log/UnifiedLog.scala#L268]. > However, the further delegation to UnifiedLog.flushUptoOffsetExclusive is > not sharing that lock, since it is [done as a scheduled task in a separate > thread|https://github.com/apache/kafka/blob/3.4/core/src/main/scala/kafka/log/UnifiedLog.scala#L1547]. > This means that further operations are [not locked at UnifiedLog > level|https://github.com/apache/kafka/blob/3.4/core/src/main/scala/kafka/log/UnifiedLog.scala#L268]. > The operation is further delegated to > [LocalLog.flush|https://github.com/apache/kafka/blob/3.4/core/src/main/scala/kafka/log/LocalLog.scala#L177], > which will also try to [flush the log > dir|https://github.com/apache/kafka/blob/3.4/core/src/main/scala/kafka/log/LocalLog.scala#L177]. > This is the 2nd code part that is involved in the race condition. > Since the log dir flush does not share the lock with the rename dir operation > (as it is scheduled via the scheduler), the rename dir operation might > succeed in moving the log dir on disk to "topic-partition", but the > LocalLog._dir will remain set to "topic-partition.hash-future", and when the > flush will attempt to flush the "topic-partition.hash-future" directory, it > will throw NoSuchFileException: "topic-partition.hash-future". Basically, > [this > line|https://github.com/apache/kafka/blob/3.4/core/src/main/scala/kafka/log/LocalLog.scala#L111] > might succeed, and before [this other > line|https://github.com/apache/kafka/blob/3.4/core/src/main/scala/kafka/log/LocalLog.scala#L111] > is executed, flush tries to [flush the future > dir|https://github.com/apache/kafka/blob/3.4/core/src/main/scala/kafka/log/LocalLog.scala#L177]. > We tested a fix with a patch on Kafka 3.4.1, on our clusters and it solved > the issue by synchronizing the flush dir operation. Will reply with a link to > a PR. > Note that this bug replicates for every version since 3.0.0, caused by [this > commit|https://github.com/apache/kafka/commit/db3e5e2c0de367ffcfe4078359d6d208ba722581#diff-eeafed82ed6a8600c397b108787fdf31e03191b0a192774a65c127d0d26edc44R2341] > when flush dir was added. -- This message was sent by Atlassian Jira (v8.20.10#820010)