TheFluxCap

I’ve been working on a Java program for a little bit.

In effort to understand what it’s doing I’ve been monitoring the host network and CPU activity. I know what I’m looking for but it’s not always clear why I’m not achieving maximum CPU or network consumption.

To help understand I tried period stack dumps using jstack looking for shared object contention. I found a few items there so that was good.

I also tried using generic Java profiling where it shows which methods are using the largest percentage of CPU. That was semi-helpful but I still felt like I need more information.

So I started looking for something that would show me thread wait/monitor/run behavior. I was wanting to verify my assumed program behavior with what was really going on. What I found to help me in this case was the Java utility jvisualvm. I attached a couple screenshots below.

Ultimately I ended up enabling remote JMX connections then started up $JDK_HOME/bin/jvsiualvm and attached to the running process. From there I went to the thread view and began running tests. The results were very helpful to me in understanding thread behavior taking into account wait/monitor time.

What I show in these two screenshots is basically different behavior between data consumers and producers. It adequately verified assumed behavior with measured behavior.