Nicholas Telford created KAFKA-17954:
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Summary: Error getting oldest-iterator-open-since-ms from JMX
Key: KAFKA-17954
URL: https://issues.apache.org/jira/browse/KAFKA-17954
Project: Kafka
Issue Type: Bug
Components: streams
Affects Versions: 3.8.1
Reporter: Nicholas Telford
In
[KIP-989|https://cwiki.apache.org/confluence/display/KAFKA/KIP-989%3A+Improved+StateStore+Iterator+metrics+for+detecting+leaks]
we introduced a new metric, {{{}oldest-iterator-open-since-ms{}}}, which
reports the timestamp that the oldest currently open KeyValueIterator was
opened at.
However, if no iterators are currently open, this Gauge returns {{{}null{}}}.
When using the Prometheus {{JmxScraper}} to scrape this metric, its value is
added to a {{{}ConcurrentHashMap{}}}, which does _not_ permit {{null}} values.
Consequently, on-scrape, we see this {{WARN}} log message:
{noformat}
Error getting JMX attribute 'oldest-iterator-open-since-ms' {noformat}
We should find some other way to report the absence of this metric that does
not cause problems with {{{}ConcurrentHashMap{}}}.
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