Have some example rules of generic JVM metrics?

Hi there,

We’re making use of the JMX exporter in combination with Tomcat and Cassandra. While using it, we’ve noticed that none of the examples contain any generic rules for extracting properties out of the JVM, like memory usage. Right now we’re planning on adding something like this to our configs:

- pattern: 'java.lang<type=Memory><(\w+)MemoryUsage>(\w+):'
  name: java_memory_usage_$2_bytes
  labels:
    area: "$1"
  help: Java $2 $1 memory usage
  type: GAUGE

Resulting in metrics like these:

java_memory_usage_committed_bytes{area="Heap",} 1.489731584E9
java_memory_usage_committed_bytes{area="NonHeap",} 3.9223296E8
java_memory_usage_max_bytes{area="Heap",} 4.294770688E9
java_memory_usage_max_bytes{area="NonHeap",} 4.17333248E8
java_memory_usage_init_bytes{area="Heap",} 2.73888048E8
java_memory_usage_init_bytes{area="NonHeap",} 3.69557504E8
java_memory_usage_used_bytes{area="Heap",} 9.61119192E8
java_memory_usage_used_bytes{area="NonHeap",} 2.09771528E8

Question: would it make sense to have some kind of examples file containing rules like these?

[brian-brazil]

We recommend always using the java agent, if you go against that and use the http server this is one of the issues you’ll run into.

[ppatierno]

@brian-brazil Hi … reading this issue I don’t see any real reason why the HTTP server mode doesn’t support JVM metrics and what do you mean saying “they’d be confusing”. I’m thinking about using it within a “sidecar” approach on Kubernetes/OpenShift but it seems that you really discourage the HTTP server mode. Can you explain better why ? It’s something related to maintaining the source code because it will be deprecated in a near future or there are some technical reasons ?