JMX GC metrics not exported after Java 11 upgrade

[marko]

Hi,

I'm using jmx_prometheus_javaagent v0.12.0 to export JVM metrics to Prometheus.

After upgrading from Java 8 to Java 11 some metrics fail to get exported

e.g. java_lang_GarbageCollector_CollectionCount and java_lang_GarbageCollector_CollectionTime.

Any ideas why this might occur?

marko

[marko]

Just did a manual scraping with the following results:

foo % grep CollectionCount jmx-metrics-java8.txt

java.lang{type=GarbageCollector, name=ParNew}[]CollectionCount: 10659

java.lang{type=GarbageCollector, name=ConcurrentMarkSweep}[]CollectionCount: 24

foo % grep CollectionCount jmx-metrics-java11.txt

java.lang{name=G1 Young Generation, type=GarbageCollector}[]CollectionCount: 811

java.lang{name=G1 Old Generation, type=GarbageCollector}[]CollectionCount: 0

When I do a query in Prometheus with the metric 'java_lang_GarbageCollector_CollectionCount' I get the ParNew and ConcurrentMarkSweep values, but not the G1 ones even though these look exactly the same (java.lang prefix, type=GarbageCollector).

The G1 ones are available however when querying with separate metrics 'java_lang_G1_Young_Generation_CollectionCount' and 'java_lang_G1_Old_Generation_CollectionCount'

Why is that?

[marko]

In the Java 8 scrape the type attribute always seems to be the first one, whereas with the Java 11 one this doesn't always seem to be the case.