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Posted to dev@kafka.apache.org by "Ismael Juma (JIRA)" <ji...@apache.org> on 2017/05/26 12:42:04 UTC
[jira] [Commented] (KAFKA-3955) Kafka log recovery doesn't truncate
logs on non-monotonic offsets, leading to failed broker boot
[ https://issues.apache.org/jira/browse/KAFKA-3955?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16026227#comment-16026227 ]
Ismael Juma commented on KAFKA-3955:
------------------------------------
Unless we get a PR for this very soon, it won't happen for 0.11.0.0.
> Kafka log recovery doesn't truncate logs on non-monotonic offsets, leading to failed broker boot
> ------------------------------------------------------------------------------------------------
>
> Key: KAFKA-3955
> URL: https://issues.apache.org/jira/browse/KAFKA-3955
> Project: Kafka
> Issue Type: Bug
> Affects Versions: 0.8.0, 0.8.1, 0.8.1.1, 0.8.2.0, 0.8.2.1, 0.8.2.2, 0.9.0.0, 0.9.0.1, 0.10.0.0, 0.10.1.1
> Reporter: Tom Crayford
> Priority: Critical
> Labels: reliability
> Fix For: 0.11.0.0
>
>
> Hi,
> I've found a bug impacting kafka brokers on startup after an unclean shutdown. If a log segment is corrupt and has non-monotonic offsets (see the appendix of this bug for a sample output from {{DumpLogSegments}}), then {{LogSegment.recover}} throws an {{InvalidOffsetException}} error: https://github.com/apache/kafka/blob/trunk/core/src/main/scala/kafka/log/OffsetIndex.scala#L218
> That code is called by {{LogSegment.recover}}: https://github.com/apache/kafka/blob/trunk/core/src/main/scala/kafka/log/LogSegment.scala#L191
> Which is called in several places in {{Log.scala}}. Notably it's called four times during recovery:
> Thrice in Log.loadSegments
> https://github.com/apache/kafka/blob/trunk/core/src/main/scala/kafka/log/Log.scala#L199
> https://github.com/apache/kafka/blob/trunk/core/src/main/scala/kafka/log/Log.scala#L204
> https://github.com/apache/kafka/blob/trunk/core/src/main/scala/kafka/log/Log.scala#L226
> and once in Log.recoverLog
> https://github.com/apache/kafka/blob/trunk/core/src/main/scala/kafka/log/Log.scala#L268
> Of these, only the very last one has a {{catch}} for {{InvalidOffsetException}}. When that catches the issue, it truncates the whole log (not just this segment): https://github.com/apache/kafka/blob/trunk/core/src/main/scala/kafka/log/Log.scala#L274 to the start segment of the bad log segment.
> However, this code can't be hit on recovery, because of the code paths in {{loadSegments}} - they mean we'll never hit truncation here, as we always throw this exception and that goes all the way to the toplevel exception handler and crashes the JVM.
> As {{Log.recoverLog}} is always called during recovery, I *think* a fix for this is to move this crash recovery/truncate code inside a new method in {{Log.scala}}, and call that instead of {{LogSegment.recover}} in each place. That code should return the number of {{truncatedBytes}} like we do in {{Log.recoverLog}} and then truncate the log. The callers will have to be notified "stop iterating over files in the directory", likely via a return value of {{truncatedBytes}} like {{Log.recoverLog` does right now.
> I'm happy working on a patch for this. I'm aware this recovery code is tricky and important to get right.
> I'm also curious (and currently don't have good theories as of yet) as to how this log segment got into this state with non-monotonic offsets. This segment is using gzip compression, and is under 0.9.0.1. The same bug with respect to recovery exists in trunk, but I'm unsure if the new handling around compressed messages (KIP-31) means the bug where non-monotonic offsets get appended is still present in trunk.
> As a production workaround, one can manually truncate that log folder yourself (delete all .index/.log files including and after the one with the bad offset). However, kafka should (and can) handle this case well - with replication we can truncate in broker startup.
> stacktrace and error message:
> {code}
> pri=WARN t=pool-3-thread-4 at=Log Found a corrupted index file, /$DIRECTORY/$TOPIC-22/00000000000014306536.index, deleting and rebuilding index...
> pri=ERROR t=main at=LogManager There was an error in one of the threads during logs loading: kafka.common.InvalidOffsetException: Attempt to append an offset (15000337) to position 111719 no larger than the last offset appended (15000337) to /$DIRECTORY/$TOPIC-8/00000000000014008931.index.
> pri=FATAL t=main at=KafkaServer Fatal error during KafkaServer startup. Prepare to shutdown kafka.common.InvalidOffsetException: Attempt to append an offset (15000337) to position 111719 no larger than the last offset appended (15000337) to /$DIRECTORY/$TOPIC-8/00000000000014008931.index.
> at kafka.log.OffsetIndex$$anonfun$append$1.apply$mcV$sp(OffsetIndex.scala:207)
> at kafka.log.OffsetIndex$$anonfun$append$1.apply(OffsetIndex.scala:197)
> at kafka.log.OffsetIndex$$anonfun$append$1.apply(OffsetIndex.scala:197)
> at kafka.utils.CoreUtils$.inLock(CoreUtils.scala:262)
> at kafka.log.OffsetIndex.append(OffsetIndex.scala:197)
> at kafka.log.LogSegment.recover(LogSegment.scala:188)
> at kafka.log.Log$$anonfun$loadSegments$4.apply(Log.scala:188)
> at kafka.log.Log$$anonfun$loadSegments$4.apply(Log.scala:160)
> at scala.collection.TraversableLike$With...
> ...Filter$$anonfun$foreach$1.apply(TraversableLike.scala:778)
> at scala.collection.IndexedSeqOptimized$class.foreach(IndexedSeqOptimized.scala:33)
> at scala.collection.mutable.ArrayOps$ofRef.foreach(ArrayOps.scala:186)
> at scala.collection.TraversableLike$WithFilter.foreach(TraversableLike.scala:777)
> at kafka.log.Log.loadSegments(Log.scala:160)
> at kafka.log.Log.<init>(Log.scala:90)
> at kafka.log.LogManager$$anonfun$loadLogs$2$$anonfun$3$$anonfun$apply$10$$anonfun$apply$1.apply$mcV$sp(LogManager.scala:150)
> at kafka.utils.CoreUtils$$anon$1.run(CoreUtils.scala:60)
> at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
> at java.util.concurrent.FutureTask.run(FutureTask.java:266)
> at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
> at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
> at java.lang.Thread.run(Thread.java:745)
> {code}
> non-monotonic offsets from DumpLogSegments tool (with --deep-iteration) (they go from 15000362 to 15000337):
> {code}
> offset: 15000361 position: 485145166 isvalid: true payloadsize: 1474 magic: 0 compresscodec: NoCompressionCodec crc: 3958745838 keysize: 36
> offset: 15000362 position: 485145166 isvalid: true payloadsize: 1474 magic: 0 compresscodec: NoCompressionCodec crc: 374463118 keysize: 36
> offset: 15000337 position: 485149591 isvalid: true payloadsize: 1474 magic: 0 compresscodec: NoCompressionCodec crc: 3955938191 keysize: 36
> offset: 15000338 position: 485149591 isvalid: true payloadsize: 1474 magic: 0 compresscodec: NoCompressionCodec crc: 4121377803 keysize: 36
> offset: 15000339 position: 485149591 isvalid: true payloadsize: 1474 magic: 0 compresscodec: NoCompressionCodec crc: 372883992 keysize: 36
> offset: 15000340 position: 485149591 isvalid: true payloadsize: 1474 magic: 0 compresscodec: NoCompressionCodec crc: 1294476491 keysize: 36
> {code}
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