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https://issues.apache.org/jira/browse/KAFKA-379?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13431309#comment-13431309
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Neha Narkhede commented on KAFKA-379:
-------------------------------------
+1. Looks good.
> 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
> Attachments: TopicCount.scala.diff, kafka-379_0.8_v1.patch
>
>
> 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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