How can I monitor the JVM memory in a proper way?

Question

I'm thinking of how we do JVM memory monitor in a low overhead way in production environment even under busy hour.

Suppose I have two tomcat app server in production, load balance set up behind them. If I can see the jvm memory statistics I can tell load balance to stop sending the request to the server which will encounter OOM issue. Do this make sense? Jconsole or VisualVM eats more performance resourse is not my choice.

Answer 1

Use either JSW, which will monitor the JVM for problems locally, or Jolokia. Or both, actually.

Answer 2

JMX would be the answer (Jolokia being a JMX interface).

You might want to also look at - http://stackoverflow.com/questions/242958/best-tools-to-monitor-tomcat

Answer 3

If monitoring externally, I'd recommend using an OS level monitoring tool such as ps on Unix to give you memory consumption stats and set up process alerts. You can and should use JMX to monitor heap utilization but remember off heap allocations via direct byte buffers or JNI libraries are invisible to JMX heap monitoring and may lead to even more catastrophic failures than OOM.

Answer 4

Maybe jvmtop is worth a look for you.

It shows you in a "top-like" manner on a per-jvm basis monitoring metrics like memory consumption, cpu utilization, thread counts etc.