Visualizing characteristics of a running Java application was pioneered by BEA's JRockit virtual machine, which was followed by a large array of monitoring and performance reporting tools, such as jconsole, jstack, or jinfo.

Each of these tools was designed to provide feedback on a specific subset of application execution characteristics, requiring developers to employ multiple tools to get a complete picture of a Java application's execution. At the same time, none of those tools provide a detailed picture of how well an application actually performs.

VisualVM, a new open-source tool developed on java.net, aims to unify many of the capabilities present in earlier tools, and amend those with performance reporting as well. VisualVM can be used during development, and even on a production application, according to the project's documentation, as the tool can be attached to any running Java application:

VisualVM is a tool that provides detailed information about Java applications while they are running. It provides an intuitive graphical user interface that allows you to easily see information about multiple Java applications. Java applications are run by a Java Virtual Machine, or VM. The name VisualVM comes from the fact that VisualVM provides VM information visually.

There are many new features in this release: applications defined by JMX connection, application snapshots, defined hosts and VM coredumps persistence, Load & Save As for thread dumps and heap dumps, autodiscovery of jstatd started after defining remote host, improved support for JRockit VMs, new icons, main menu & toolbar cleanup, customizable Options, GlassFish plugin on Plugin Center.

What do you think of VisualVM?