[jira] [Commented] (KAFKA-379) TopicCount.constructTopicCount isn't thread-safe

["Evan Chan (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/KAFKA-379?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13450034#comment-13450034 ] 

Evan Chan commented on KAFKA-379:
---------------------------------

Do you guys want a patch for 0.6?   I just created one and can attach it.   I know, we should really upgrade to 0.7.
                
> TopicCount.constructTopicCount isn't thread-safe
> ------------------------------------------------
>
>                 Key: KAFKA-379
>                 URL: https://issues.apache.org/jira/browse/KAFKA-379
>             Project: Kafka
>          Issue Type: Bug
>          Components: clients
>    Affects Versions: 0.7, 0.8
>            Reporter: Nick Howard
>            Assignee: Jun Rao
>              Labels: bugs
>         Attachments: kafka-379_0.8_v1.patch, TopicCount.scala.diff
>
>
> TopicCount uses scala.util.parsing.json.JSON, which isn't thread-safe https://issues.scala-lang.org/browse/SI-4929
> If you have multiple consumers within the same JVM, and they all rebalance at the same time, you can get errors like the following:
> [...] kafka.consumer.TopicCount$.constructTopicCount:39] ERROR: error parsing consumer json string [...]
> java.lang.NullPointerException
>         at scala.util.parsing.combinator.Parsers$NoSuccess.<init>(Parsers.scala:131)
>         at scala.util.parsing.combinator.Parsers$Failure.<init>(Parsers.scala:158)
>         at scala.util.parsing.combinator.Parsers$$anonfun$acceptIf$1.apply(Parsers.scala:489)
>         ...
>         at scala.util.parsing.combinator.Parsers$$anon$2.apply(Parsers.scala:742)
>         at scala.util.parsing.json.JSON$.parseRaw(JSON.scala:71)
>         at scala.util.parsing.json.JSON$.parseFull(JSON.scala:85)
>         at kafka.consumer.TopicCount$.constructTopicCount(TopicCount.scala:32)
>         at kafka.consumer.ZookeeperConsumerConnector$ZKRebalancerListener.kafka$consumer$ZookeeperConsumerConnector$ZKRebalancerListener$$getTopicCount(ZookeeperConsumerConnector.scala:422)
>         at kafka.consumer.ZookeeperConsumerConnector$ZKRebalancerListener.kafka$consumer$ZookeeperConsumerConnector$ZKRebalancerListener$$rebalance(ZookeeperConsumerConnector.scala:460)
>         at kafka.consumer.ZookeeperConsumerConnector$ZKRebalancerListener$$anonfun$syncedRebalance$1.apply$mcVI$sp(ZookeeperConsumerConnector.scala:437)
>         at scala.collection.immutable.Range$ByOne$class.foreach$mVc$sp(Range.scala:282)
>         at scala.collection.immutable.Range$$anon$2.foreach$mVc$sp(Range.scala:265)
>         at kafka.consumer.ZookeeperConsumerConnector$ZKRebalancerListener.syncedRebalance(ZookeeperConsumerConnector.scala:433)
>         at kafka.consumer.ZookeeperConsumerConnector$ZKRebalancerListener.handleChildChange(ZookeeperConsumerConnector.scala:375)
>         at org.I0Itec.zkclient.ZkClient$7.run(ZkClient.java:568)
>         at org.I0Itec.zkclient.ZkEventThread.run(ZkEventThread.java:71)
> I ran into this on 0.7.0, but the code in trunk appears to be vulnerable to the same issue.

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