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  1. Kafka
  2. KAFKA-3587

LogCleaner fails due to incorrect offset map computation on a replica



    • Bug
    • Status: Resolved
    • Major
    • Resolution: Fixed
    • None
    • None
    • Linux


      Log Cleaner fails to compact a segment even when the number of messages in it is less than the offset map.

      In version, (LogCleaner.scala -> buildOffsetMap()), LogCleaner computes segment size by subtracting segment's base offset from the latest offset ("segmentSize = segment.nextOffset() - segment.baseOffset"). This works fine until you create another replica. When you create a replica, it's segment could contain data which is already compacted on other brokers. Depending up on the type of data, offset difference could be too big, larger than the offset map (maxDesiredMapSize), and that causes LogCleaner to fail on that segment.


      • Kafka
      • Cluster has two brokers.
      • Server.properties:
        log.cleaner.dedupe.buffer.size=10485760 #10MB

      Steps to reproduce:
      1. Create a topic with replication-factor of 1.

      ./kafka-topics.sh --zookeeper=localhost:2181 --create --topic test.log.compact.1M --partitions 1 --replication-factor 1 --config cleanup.policy=compact --config segment.ms=300000

      2. Use kafka-console-producer.sh to produce a single message with the following key:

      {"test": "xyz"}

      3. Use kafka-console-producer.sh to produce a large number of messages with the following key:

      {"test": "abc"}

      4. Let log cleaner run. Make sure log is compacted. Verify with:
      ./kafka-run-class.sh kafka.tools.DumpLogSegments --files 00000000000000000000.log --print-data-log

      Dumping 00000000000000000000.log
      Starting offset: 0
      offset: 0 position: 0 isvalid: true payloadsize: 11 magic: 0 compresscodec: NoCompressionCodec crc: 3067045277 keysize: 11 key: LC1 payload:

      {"test": "xyz"}

      offset: 7869818 position: 48 isvalid: true payloadsize: 11 magic: 0 compresscodec: NoCompressionCodec crc: 2668089711 keysize: 11 key: LC2 payload:

      {"test": "abc"}

      5. Increase Replication Factor to 2. Followed these steps: http://kafka.apache.org/documentation.html#basic_ops_increase_replication_factor

      6. Notice that log cleaner fails to compact the newly created replica with the following error.
      [2016-04-18 14:49:45,599] ERROR [kafka-log-cleaner-thread-0], Error due to (kafka.log.LogCleaner)
      java.lang.IllegalArgumentException: requirement failed: 7206179 messages in segment test.log.compact.1M-0/00000000000000000000.log but offset map can fit only 393215. You can increase log.cleaner.dedupe.buffer.size or decrease log.cleaner.threads
      at scala.Predef$.require(Predef.scala:219)
      at kafka.log.Cleaner$$anonfun$buildOffsetMap$4.apply(LogCleaner.scala:584)
      at kafka.log.Cleaner$$anonfun$buildOffsetMap$4.apply(LogCleaner.scala:580)
      at scala.collection.immutable.Stream$StreamWithFilter.foreach(Stream.scala:570)
      at kafka.log.Cleaner.buildOffsetMap(LogCleaner.scala:580)
      at kafka.log.Cleaner.clean(LogCleaner.scala:322)
      at kafka.log.LogCleaner$CleanerThread.cleanOrSleep(LogCleaner.scala:230)
      at kafka.log.LogCleaner$CleanerThread.doWork(LogCleaner.scala:208)
      at kafka.utils.ShutdownableThread.run(ShutdownableThread.scala:63)
      [2016-04-18 14:49:45,601] INFO [kafka-log-cleaner-thread-0], Stopped (kafka.log.LogCleaner)

      7. Examine the entries in the replica segment:

      ./kafka-run-class.sh kafka.tools.DumpLogSegments --files 00000000000000000000.log --print-data-log
      There are only 218418 messages in that segment.

      However, Log Cleaner seems to think that there are 7206179 messages in that segment (as per the above error)

      Error stems from this line in LogCleaner.scala:
      """val segmentSize = segment.nextOffset() - segment.baseOffset"""

      In Replica's log segment file ( 00000000000000000000.log), ending offset is 7206178. Beginning offset is 0. That makes Log Cleaner think that there are 7206179 messages in that segment although there are only 218418 messages in it.

      IMO, to address this kind of scenario, LogCleaner.scala should check for the number of messages in the segment, instead of subtracting beginning offset from the ending offset.


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              ecomar Edoardo Comar
              kiranp Kiran Pillarisetty
              Jun Rao Jun Rao
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