There are 2 solutions you can use to monitor a running XWiki instance:

• Use a Profiler. This has the advantage of providing advanced information but has the drawback of being resource intensive and thus slowing the XWiki instance. It also requires a special startupscript
• Starting with XWiki Enterprise 2.4M2 we've now started using the JMX Technology to provide runtime monitoring of XWiki instances. The following features are currently available:
  • Monitor the Velocity macro caches
  • Monitor the caches XWiki is using to cache Document data, Users & Groups data and more

JMX Console

Since JMX is a standard you can use any JMX-compatible monitoring console (most application servers provide a web-based JMX console). There's also such a console called JConsole and which is bundled by default in the Java Runtime you're using. To start it, simply execute the jconsole executable.

Example of JConsole showing the Velocity Cache monitoring: