Onur Karaman created KAFKA-4893:
-----------------------------------
Summary: async topic deletion conflicts with max topic length
Key: KAFKA-4893
URL: https://issues.apache.org/jira/browse/KAFKA-4893
Project: Kafka
Issue Type: Bug
Reporter: Onur Karaman
Priority: Minor
As per the
[documentation|http://kafka.apache.org/documentation/#basic_ops_add_topic],
topics can be only 249 characters long to line up with typical filesystem
limitations:
{quote}
Each sharded partition log is placed into its own folder under the Kafka log
directory. The name of such folders consists of the topic name, appended by a
dash (\-) and the partition id. Since a typical folder name can not be over 255
characters long, there will be a limitation on the length of topic names. We
assume the number of partitions will not ever be above 100,000. Therefore,
topic names cannot be longer than 249 characters. This leaves just enough room
in the folder name for a dash and a potentially 5 digit long partition id.
{quote}
{{kafka.common.Topic.maxNameLength}} is set to 249 and is used during
validation.
This limit ends up not being quite right since topic deletion ends up renaming
the directory to the form {{topic-partition.uniqueId-delete}} as can be seen in
{{LogManager.asyncDelete}}:
{code}
val dirName = new StringBuilder(removedLog.name)
.append(".")
.append(java.util.UUID.randomUUID.toString.replaceAll("-",""))
.append(Log.DeleteDirSuffix)
.toString()
{code}
So the unique id and "-delete" suffix end up hogging some of the characters.
Deleting a long-named topic results in a log message such as the following:
{code}
kafka.common.KafkaStorageException: Failed to rename log directory from
/tmp/kafka-logs0/000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000-0
to
/tmp/kafka-logs0/000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000-0.797bba3fb2464729840f87769243edbb-delete
at kafka.log.LogManager.asyncDelete(LogManager.scala:439)
at kafka.cluster.Partition$$anonfun$delete$1.apply$mcV$sp(Partition.scala:142)
at kafka.cluster.Partition$$anonfun$delete$1.apply(Partition.scala:137)
at kafka.cluster.Partition$$anonfun$delete$1.apply(Partition.scala:137)
at kafka.utils.CoreUtils$.inLock(CoreUtils.scala:213)
at kafka.utils.CoreUtils$.inWriteLock(CoreUtils.scala:221)
at kafka.cluster.Partition.delete(Partition.scala:137)
at kafka.server.ReplicaManager.stopReplica(ReplicaManager.scala:230)
at
kafka.server.ReplicaManager$$anonfun$stopReplicas$2.apply(ReplicaManager.scala:260)
at
kafka.server.ReplicaManager$$anonfun$stopReplicas$2.apply(ReplicaManager.scala:259)
at scala.collection.Iterator$class.foreach(Iterator.scala:727)
at scala.collection.AbstractIterator.foreach(Iterator.scala:1157)
at scala.collection.IterableLike$class.foreach(IterableLike.scala:72)
at scala.collection.AbstractIterable.foreach(Iterable.scala:54)
at kafka.server.ReplicaManager.stopReplicas(ReplicaManager.scala:259)
at kafka.server.KafkaApis.handleStopReplicaRequest(KafkaApis.scala:174)
at kafka.server.KafkaApis.handle(KafkaApis.scala:86)
at kafka.server.KafkaRequestHandler.run(KafkaRequestHandler.scala:64)
at java.lang.Thread.run(Thread.java:745)
{code}
The topic after this point still exists but has Leader set to -1 and the
controller recognizes the topic completion as incomplete (the topic znode is
still in /admin/delete_topics).
I don't believe linkedin has any topic name this long but I'm making the ticket
in case anyone runs into this problem.
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