[jira] [Created] (KAFKA-10063) UnsupportedOperation when querying cleaner metrics after shutdown

["Jason Gustafson (Jira)" <ji...@apache.org>]

Jason Gustafson created KAFKA-10063:
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             Summary: UnsupportedOperation when querying cleaner metrics after shutdown
                 Key: KAFKA-10063
                 URL: https://issues.apache.org/jira/browse/KAFKA-10063
             Project: Kafka
          Issue Type: Bug
            Reporter: Jason Gustafson


We have a few log cleaner metrics which iterate the set of cleaners. For example:

{code}
  newGauge("max-clean-time-secs", () => cleaners.iterator.map(_.lastStats.elapsedSecs).max.toInt)
{code}

It seems possible currently for LogCleaner metrics to get queried after shutdown of the log cleaner, which clears the `cleaners` collection. This can lead to the following error:
{code}
ava.lang.UnsupportedOperationException: empty.max
	at scala.collection.IterableOnceOps.max(IterableOnce.scala:952)
	at scala.collection.IterableOnceOps.max$(IterableOnce.scala:950)
	at scala.collection.AbstractIterator.max(Iterator.scala:1279)
	at kafka.log.LogCleaner.kafka$log$LogCleaner$$$anonfun$new$9(LogCleaner.scala:132)
	at kafka.log.LogCleaner$$anonfun$4.value(LogCleaner.scala:132)
	at kafka.log.LogCleaner$$anonfun$4.value(LogCleaner.scala:132)
{code}



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