Java Visual VM, an impression brief
VisualVM its a simple profiler that Oracle offert into the JDK distribution, wich contains a friendly Grafical User Interface and very intuitive menus. This software monitoring the Java Virtual Machine (aka JVM) allowing report all memory and garbage collections states of JVM, such as Eden, survivors (0,1), permanent generation, and so on.
VisualVM is very usefull when we don't have some monitoring tools and we don't have money to get some monitoring tool. We options are develop own monitoring tools, like many people do it, although archaic and with limited goals, because there require of lot time for do it.
This software have as core NetBeans, even we could extend functions using new developed plugins by thirds parts.
For example, when we have to test some Java web application, we need look the object transitions and how garbge collector perform objects movements.
In the following images, show some screens about the use of this tool. First image shows the main screen. The left column shows all JVM processes running into the host, even JVisual process.
The next image show the loaded classes, like percent of use, memory spent, cpu spent, and many other options.
The next screen, show the plugins that are availables, this we can observe similitude between NetBeans and Java Visual VM.
The next screen show that arguments were passed to the Java process
Now, we can watch cpu consumption, loaded classes and many more items.
There, we look that threads are into our JVM process and their status that it have. Each color represent one status like RUNNING, SLEEP, WAIT and MONITOR.
There its possible look heap dump
All classes that we have in memory and their percent occupation.
There, we can start the profiler by CPU or by Memory.