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Posted to dev@kafka.apache.org by "Ismael Juma (JIRA)" <ji...@apache.org> on 2017/04/07 12:49:41 UTC

[jira] [Commented] (KAFKA-4950) ConcurrentModificationException when iterating over Kafka Metrics

    [ https://issues.apache.org/jira/browse/KAFKA-4950?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15960720#comment-15960720 ] 

Ismael Juma commented on KAFKA-4950:
------------------------------------

[~vahid], would you like to pick this one up?

> ConcurrentModificationException when iterating over Kafka Metrics
> -----------------------------------------------------------------
>
>                 Key: KAFKA-4950
>                 URL: https://issues.apache.org/jira/browse/KAFKA-4950
>             Project: Kafka
>          Issue Type: Bug
>    Affects Versions: 0.10.1.1
>            Reporter: Dumitru Postoronca
>            Priority: Minor
>             Fix For: 0.11.0.0
>
>
> It looks like the when calling {{PartitionStates.partitionSet()}}, while the resulting Hashmap is being built, the internal state of the allocations can change, which leads to ConcurrentModificationException during the copy operation.
> {code}
> java.util.ConcurrentModificationException
>         at java.util.LinkedHashMap$LinkedHashIterator.nextNode(LinkedHashMap.java:719)
>         at java.util.LinkedHashMap$LinkedKeyIterator.next(LinkedHashMap.java:742)
>         at java.util.AbstractCollection.addAll(AbstractCollection.java:343)
>         at java.util.HashSet.<init>(HashSet.java:119)
>         at org.apache.kafka.common.internals.PartitionStates.partitionSet(PartitionStates.java:66)
>         at org.apache.kafka.clients.consumer.internals.SubscriptionState.assignedPartitions(SubscriptionState.java:291)
>         at org.apache.kafka.clients.consumer.internals.ConsumerCoordinator$ConsumerCoordinatorMetrics$1.measure(ConsumerCoordinator.java:783)
>         at org.apache.kafka.common.metrics.KafkaMetric.value(KafkaMetric.java:61)
>         at org.apache.kafka.common.metrics.KafkaMetric.value(KafkaMetric.java:52)
> {code}
> {code}
> // client code:
> private final KafkaConsumer client;
>         Map<MetricName, org.apache.kafka.common.Metric> m = client.metrics();
>         for (Map.Entry<MetricName, org.apache.kafka.common.Metric> e : m.entrySet()) {
>             gauges.put(name(e.getKey().group(), e.getKey().name(), "count"), new Gauge<Double>() {
>                 @Override
>                 public Double getValue() {
>                     return e.getValue().value(); // exception thrown here
>                 }
>             });
>         }
> {code}



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