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Eclipse Special: Remote Debugging Tomcat & JBoss Apps with Eclipse
So without further ado here is how I use Tomcat, JBoss, and Eclipse to build and debug applications

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Over the last several weeks I've received a few questions about remote debugging with Eclipse. I posted about this on my other blog back in February here but with not enough info for others to follow.

If you go look at that blog entry you will see that I looked into 'in eclipse' debugging but did not find it satisfactory.

So without further ado here is how I use Tomcat, JBoss, and Eclipse to build and debug applications.

Whichever platform you are using (Tomcat or JBoss) you need to start them with the JPDA debugging enabled. For Tomcat this is very easy. In the $CATALINA_HOME/bin directory there is a script catalina.sh. If you provide the arguments 'jpda start' tomcat will startup and listen on port 8000 for a debugger connection.

With JBoss its only slightly more complicated. Basically you need to specify the JAVA_OPTS to have java start up listening for debugger connections. I typically copy the $JBOSS_HOME/bin/run.sh to $JBOSS_HOME/bin/run-debug.sh but you can just as easily setup the JAVA_OPTS environment variable and use the run.sh script.

The value of JAVA_OPTS needs have -Xdebug -Xrunjdwp:server=y, transport=dt_socket,address=4142, suspend=n specified.

So this is what is going on with this argument list

  • Xdebug == start the jvm and listen for debugging connections
  • Xrunjdwp... == the info on how to connect to do remote debugging
  • server=y == start in server mode (i.e. wait for connections, don't go out looking to connect
  • transport=dt_socked == use sockets, this works (I think) only on unix (I'm on a mac), on Windows you have to use shared memory via the transport=dt_shmem argument instead. I'm fairly sure this works but its been a while since I tried it on Windows. YMMV. Here is the official info on the connection arguments
  • address=4142 == the port to connect to or the shared mem address to use
  • suspend=n == don't wait for a debugger to tell you what to do, go ahead and launch

Once you have JBoss or Tomcat running and listening for debugging connections you are good to go for connecting with Eclipse

The first thing you need to do is create a 'debug launch configuration' by bringing up the launch configuration editor. Figure 1 shows the menu item to invoke to make that happen

When the launch config editor appears select 'Remote Java Application' from the 'Configurations:' selection list on the left hand side then click the 'New' button. Figure 2 shows the defaults that appear for me after hitting the 'New' button.

Since it defaults to the Tomcat port leave the port number set to 8000, if yours is different then change it to 8000. Notice also that you can specify the host to connect to. If you have access to the port and the process is running on another machine then you can debug the process remotely. This works out really well for those situations where it works fine in your local env but not in the test env. I usually rename the configuration (it defaults to the name of the project for me) to 'Debug Tomcat' or something like that.

The other options (Source & Common) can be ignored for now. If you have not already launched tomcat in debug mode do so now on the command line with $CATALINA_HOME/bin/catalina.sh jpda start. When its launched go back to the Eclipe launch configuration editor and hit the 'Debug' button. If you are not auto switched to the'Debug' perspective go there now. You should see a 'Debug View' that looks a lot like Figure 3.

Your code should be directly below the Debug View if you have the default layout still in place. If so go there and set a break point in one of your servlets' service methods (or any other code that is being executed in Tomcat, like a struts action or whatever) and then go to the Web browser and tickle the code that you have a break point set in. Notice that Eclipse suspends Tomcat at the breakpoint, comes to the front and lets you debug your program. Everything works just as if you were debugging locally.

Everything works the same within JBoss once you get it started with the debugging turned on. Keep in mind that you must set the port to match (in the above discussion of JAVA_OPTS it is set to 4142). So you need to create a new Debug launch configuration and specify 4142 as the port. Then you can debug your EJBs.

If you'd like to know more about this or you are having trouble making it work feel free to comment or send me an email.

Happy Debugging!

About Bill Dudney
Bill Dudney is Editor-in-Chief of Eclipse Developer's Journal and serves too as JDJ's Eclipse editor. He is a Practice Leader with Virtuas Solutions and has been doing Java development since late 1996 after he downloaded his first copy of the JDK. Prior to Virtuas, Bill worked for InLine Software on the UML bridge that tied UML Models in Rational Rose and later XMI to the InLine suite of tools. Prior to getting hooked on Java he built software on NeXTStep (precursor to Apple's OSX). He has roughly 15 years of distributed software development experience starting at NASA building software to manage the mass properties of the Space Shuttle.

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Reader Feedback: Page 1 of 3

see link

Thanks A lot....

This was very helpful. The information is just right

Hi Bill Dudney,

I really enjoyed reading your blog on Remote Debugging Tomcat & Eclipse Apps with Eclipse.

I would have one problem regarding remote debugging with Jboss as after editing the run.bat JAVA_OPTS section and setting the debug_port I came across very weard looking error message about not been able to initialize dt_socket.

Error [2] in connect() call!
err:: No such file or directory
Socket transport failed to init.
Transport dt_socket failed to initialize, rc = -1.
FATAL ERROR in native method: No transports initialize

I'm using
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.2_
Java HotSpot(TM) Client VM (build 1.4.2_10-b03)

I appreciate your advice

Best Regards

Pasi

Hi Bill Dudney,

I really enjoyed reading your blog on Remote Debugging Tomcat & Eclipse Apps with Eclipse.

I would have one problem regarding remote debugging with Jboss as after editing the run.bat JAVA_OPTS section and setting the debug_port I came across very weard looking error message about not been able to initialize dt_socket.

Error [2] in connect() call!
err:: No such file or directory
Socket transport failed to init.
Transport dt_socket failed to initialize, rc = -1.
FATAL ERROR in native method: No transports initialize

I'm using
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.2_
Java HotSpot(TM) Client VM (build 1.4.2_10-b03)

I appreciate your advice

Best Regards

Pasi

Hi Bill,

When I try to use the eclipse to do a remote debug on a web app on tomcat, I got "Failed to conne`t to remote VM. Connection refused". Any insight on this issue?

THanks!
Xingsheng

how to do tomcat application server debugging torugh visual slick editor

i want to do remote tomcat application server debugging through
visual slick edit
can u give some info in this context

It is possible multiple developers debug the application at the same time?

In my environment, the first developer works fine. When the second developer tries to debug the following message appears: Failed to connect to remote VM.

Sorry for english!

Hi,
I can able to debug java code of my webapplication from eclipse.My web application using jsp,struts,castor.How to debug struts & jsp.
Thank you.
mahesh

Jonathan,
Thanks for ur reply.I tried by editing run.bat with setting JAVA_OPTS with mentioned parms but i can''t able to debug.Actually i downloaded jboss-ide plugin for eclipse.In the configuration section of jboss-ide i put ''Xdebug -Xrunjdwp:transport=dt_shmem,address=javadebug,suspend=y '' for vm arguments.Then i can debug.It asked for source code container.I browsed and put my code in the container.Now can i able to debug step by step.
Once again thanks for ur reply
mahesh

Trying to run Jboss with debugging JVM enabled results in the following error during startup:

JBOSS_HOME: /work/12spilk/JBoss JAVA: /usr/opt/java142/bin/java
JAVA_OPTS: -Xdebug -Xrunjdwp:transport=dt_socket,address=8787,server=y,suspend=n -Dprogram.name run.sh CLASSPATH: /work/12spilk/JBoss/bin/run.jar:/usr/opt/java142/lib/tools.jar

Info: Debugging is not available with the Fast VM, invoking the Classic VM.
Info: Debugging is not available with the Fast VM, invoking the Classic VM.
FATAL ERROR in native method: internal error in JVMDI (phantom frame pop)
at java.util.zip.ZipFile.getEntry(Native Method)
at java.util.zip.ZipFile.getEntry(ZipFile.java:140)
at java.util.jar.JarFile.getEntry(JarFile.java:194)
at java.util.jar.JarFile.getJarEntry(JarFile.java:181)
at sun.misc.URLClassPath$JarLoader.getResource(URLClassPath.java:668)
at sun.misc.URLClassPath.getResource(URLClassPath.java:156)
at java.net.URLClassLoader$1.run(URLClassLoader.java:190)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java, Compiled Code)
at java.lang.ClassLoader.loadClass(ClassLoader.java:289)
at java.lang.ClassLoader.loadClass(ClassLoader.java:289)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:260)
at java.lang.ClassLoader.loadClass(ClassLoader.java:289)
at java.lang.ClassLoader.loadClass(ClassLoader.java:246)
at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:313)

....and lots of more errors on the call stack.

The machine is an Alpha Cluster system running True64 Unix 5.1B (Patchkit 4). Java is 1.4.2-2

Is this probably a bug in the VM?

Mahesh -

No need for dedicated plug-ins or anything like that. Just run your JBoss instance as normal, except that instead of letting the Java executable be called as it usually would be, make sure it''s invoked using something like the following command line:

java -Xnoagent -Xdebug -Xrunjdwp:transport=dt_socket,address=8145,server=y,suspend=n

This just lets Java know that it should run in debugging mode, listening out for debuggers attaching on port 8145 using the JPDA standard. I don''t know much about JBoss, so I don''t know where the Java executable would be called from, but it''s probably in a batch file or script somewhere. You''ll have to edit this - but save a copy of the original.

Once you''ve done this, just run JBoss so that it uses the new command line and then follow Bill''s instructions to connect to it from Eclipse. You''ll need to make sure that the port/address settings you''ve used in the above command line (8145 in this case) match what you set in Eclipse.

Good luck with the presentation.

Jon

Hi,
I want to debug my running webapplication from eclipse.
I am using JBoss-3.2.4 as my app. server.I know some plugins
like sysdeo,lomboz.sydeo is for tomcat.lomboz only debugs jsp.so how can i debug on jboss-3.2.4.
I will expect a quick reply.As i have to give presentation on web app. debugging infront of my dev. team.
mahesh adepu

In my project, I am using Tomcat and JBOSS. How do I configure both?
Problem facing
1. After configured the tomcat in the eclipse and while clicking run button it is not refering Jboss which is running in my machine.


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