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Java VisualVM

Oracle's JDK and the open source OpenJDK implementations both included the Java VisualVM tool until version 8. VisualVM is an open source tool to monitor JVM instances of each running JVM application. Its built-in features can be further enhanced by installing plugins. The users of Oracle JDK or OpenJDK 9 can download this open source tool from https://visualvm.github.io/index.html.

To launch VisualVM with its default settings, type:

jvisualvm

First, a splash window is displayed, and after a while, VisualVM's main window appears. VisualVM can not only connect to running JVM instances on a network server, but also to locally running JVM instances. In the following screenshot, I was monitoring a locally running NetBeans IDE instance:

Setting up a JVM instance for remote monitoring takes some effort; it is out of the scope of this book but documented in the VisualVM section of the JDK documentation.

Real-time monitoring always takes up lots of system resources. The monitoring of local processes should only be considered in a development environment. Remote monitoring normally consumes less, but still considerable, server resources.