[jira] [Created] (KAFKA-19680) NoSuchElementException (again) in Kafka Streams iterator metrics

["Steven Schlansker (Jira)" <ji...@apache.org>]

Steven Schlansker created KAFKA-19680:
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             Summary: NoSuchElementException (again) in Kafka Streams iterator metrics
                 Key: KAFKA-19680
                 URL: https://issues.apache.org/jira/browse/KAFKA-19680
             Project: Kafka
          Issue Type: Bug
    Affects Versions: 4.1.0
            Reporter: Steven Schlansker


Since upgrading to Kafka Streams 4.1.0, we again see in our metrics collection:
{code:java}
Exception thrown from GraphiteReporter#report. Exception was suppressed.
java.util.NoSuchElementException: null
	at java.base/java.util.concurrent.ConcurrentSkipListMap.firstKey(ConcurrentSkipListMap.java:1863)
	at java.base/java.util.concurrent.ConcurrentSkipListSet.first(ConcurrentSkipListSet.java:393)
	at org.apache.kafka.streams.internals.metrics.OpenIterators.lambda$add$0(OpenIterators.java:57)
	at org.apache.kafka.common.metrics.KafkaMetric.metricValue(KafkaMetric.java:81) {code}
It seems that unfortunately the dynamic metric registration introduced in [https://github.com/apache/kafka/pull/20022] undid the fix from [https://github.com/apache/kafka/pull/18771]

There is still a race between the metric gauge being removed, and the last open iterator being removed from the tracking set. The same fix from #18771 would fix the issue again.



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