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This section of the FAQ discusses common questions related to Tomcat development.

Questions

1. Debugging
   1. How do I configure Tomcat to support remote debugging?
   2. How do I remotely debug Tomcat using Eclipse?
   3. How do I remotely debug Tomcat using NetBeans?
2. Other
   1. How do I change the monitoring interval for modified resources and application reloading?

Answers

Debugging

How do I configure Tomcat to support remote debugging?

The short answer is to add the following options when the JVM is started:

-Xdebug -Xrunjdwp:transport=dt_socket,address=8000,server=y,suspend=n

There are a number of ways you can do this depending on how you normally start Tomcat:

• If you are using shell scripts to start Tomcat, start it with the following command:

catalina jpda start

It will start Tomcat so that a remote debugger can be connected to port 8000.

The above mentioned options can be provided by setting certain environment variables

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. See the comments at the top of catalina.sh or .bat file for details.

For example, the port number and JPDA transport implementation can be set with JPDA_ADDRESS=8000 and JPDA_TRANSPORT=dt_socket.

• If you run Tomcat using service wrapper, add the above JVM options before any other JVM options. Check the documentation for the service wrapper to determine how to set JVM options.
• If you start Tomcat from within an IDE, check the documentation for the IDE to determine how to set the required JVM options.
  

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Whilst this is very useful in development it should not be used in production because of both security and performance implications.

How do I remotely debug Tomcat using Eclipse?

This answer assumes that you have a project set up and have some idea of what you are doing in this respect. If not then that is really outside the scope of this topic and you need to go to eclipse.org and read up on how to use your IDE, and maybe practice a little bit before you come back to this. We are also going to assume that you have some idea of what a debugger is and how to use one.

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Now go type the url to submit to your servlet or whatever in your browser. Boom you hit the breakpoint right? Have fun!

How do I remotely debug Tomcat using NetBeans?

This answer assumes that you have correctly set up a NetBeans project and that you know how to use the NetBeans debugger. If not, please go to http://www.netbeans.org/kb/using-netbeans/40/debug.html and read up on how to use NetBeans and its debugger.

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Note that NetBeans has a second option – you can debug JSP files and servlets locally using a Tomcat server that is bundled with the IDE. When you debug a JSP file or servlet in the IDE, the bundled Tomcat server automatically starts in debug mode, and the debugger connects to it.

Other

How do I change the monitoring interval for modified resources and application reloading?

Monitoring interval for application reloading is controlled by the backgroundProcessorDelay property on Context element or on its parent containers: Host and Engine. See Tomcat Configuration Reference for details. By default there is a single background processing thread that is run by Engine. See its configuration for the default delay value.

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