state of the art in j2ee debugging and monitoring tools

Question

I'm digging into J2EE for the first time in years. I'm looking for recommendations on J2EE debugging and monitoring tools. I'd like to find a tool that lets me dynamically explore the threads space etc.

I'm primarily working with Tomcat. update: and Java 5. (Rats.)

Answer 1

The state-of-the-art is probably VisualVM.

Answer 2

If you are unable to use VisualVM (not sure how it plays with Java5 instances), take a look at Lambda Probe.

Lambda Probe may not have all of the features you want (e.g. threads), but does have quite a few monitoring features and works with Java 4 and 5.

• New! Comprehensive JVM memory usage monitor.
• JBoss compatibility
• Display of deployed applications, their status, session count, session object count, context
  object count, datasource usage etc.
• Start, stop, restart, deploy and updeploy of applications
• Ability to view deployed JSP files
• Ability to compile all or selected JSP files at any time.
• Ability to pre-compile JSP files on application deployment.
• New! Ability to view auto-generated JSP servlets
• Display of list of sessions for a particular application
• Display of session attributes and their values for a particular
  application. Ability to remove
  session attributes.
• Ability to view application context attributes and their values.
• Ability to expire selected sessions
• Graphical display of datasource details including maximum number of
  connections, number of busy
  connections and configuration details
• New! Ability to group datasource properties by URL to help
  visualizing impact on the databases
• Ability to reset data sources in case of applications leaking
  connection
• Display of system information including System.properties, memory
  usage bar and OS details
• Display of JK connector status including the list of requests
  pending execution
• Real-time connector usage charts and statistics.
• Real-time cluster monitoring and clulster traffic charts
• New! Real time OS memory usage, swap usage and CPU utilisation
  monitoring
• Ability to show information about log files and download selected
  files
• Ability to tail log files in real time from a browser.
• Ability to interrupt execution of "hang" requests without server
  restart
• New! Ability to restart Tomcat/JVM via Java Serview Wrapper.
• Availability "Quick check"
• Support for DBCP, C3P0 and Oracle datasources
• Support for Tomcat 5.0.x and 5.5.x
• Support for Java 1.4 and Java 1.5