functional areas of visibility that are important to Java, and discuss how various tools
provide that information. Along the way, we'll discuss other tools (some open source, some
commercial) that provide the same basic functionality but which have advantages over the
basic JDK tools.
Basic VM Information
JVM tools can provide basic information about a running JVM process: how long it has been
up, what JVM flags are in use, JVM system properties, and so on.
The length of time the JVM has been up can be found via this command:
% jcmd process_id VM.uptime
The set of items in System.getProperties() can be displayed with either of these com-
% jcmd process_id VM.system_properties
% jinfo -sysprops process_id
This includes all properties set on the command line with a -D option, any properties dy-
namically added by the application, and the set of default properties for the JVM.
The version of the JVM is obtained like this:
% jcmd process_id VM.version
JVM command line
The command line can be displayed in the VM summary tab of jconsole , or via jcmd :