I want to debug a java EE web application that run on Apache Tomcat. Is there any way to debug the application without stoping the server.
You can use remote debugging, but you'll need your server (once) to be started with the correct arguments for that. For instance, since you are using Tomcat, you can add these arguments in catalina.sh:
-Xdebug -Xrunjdwp:transport=dt_socket,address=8000,server=y,suspend=n
Then you can attach your debugger to REMOTE_IP:8000 and start debugging.
Always take into account that you are working in a production environment, so be careful with this.
The trick here is to start Tomcat with remote debugging enabled.
The easy way to do this is to use the options jpda start if you start tomcat using the catalina.sh or catalina.bat shell script.
If you are starting Tomcat using your IDE or something, then you must add the following options to the JVM that runs Tomcat:
-Xdebug -Xrunjdwp:transport=dt_socket,address=8000,server=y,suspend=n
After you do that, then you need to configure your IDE to connect to the remote debugging port.
Check this Tomcat FAQ for more information.
you can't. The server have to be started in debug mode.
I invite you to read the wiki: http://wiki.apache.org/tomcat/FAQ/Developing
If you don't want to restart your live tomcat.
Create a new server (configured in debug mode), then copy you application on it.
Debug on this server.
Related
This might be silly question but I really don't know it.
I have performed some changes in my web application in java/jsp.
Tested it in localhost in eclipse where I can see logs in console.
After that I have deployed the changes to beta server and its not
reflecting as in localhost hence want to see running logs through
tomcat console but Tomcat is already running and was started with
services utility of windows.
Is there any way to open console of running tomcat.
I do know that we can see tomcat logs as well, but running console
will be preferred for me as there are multiple projects are running on
same server.
You can check log file(s) in the tomcat-home/logs folder.
You can attach Eclipse to a running process if you have started the server with the right settings: see Attach debugger to application using Eclipse On windows, you can either delete and reinstall the services as in https://tomcat.apache.org/tomcat-7.0-doc/windows-service-howto.html or, you can add these parameters in the Windows registry for the Tomcat you are running: see http://www.tomcatexpert.com/knowledge-base/allocating-more-ram-tomcat-windows . I would be very careful with the registry hack unless you've hacked the registry before and are comfortable doing it.
I have a SpringMvc based application project hosted in Jetty and managed by Maven3. I want debug program in remote server JVM. So, on the server side I set java options to the Jetty server.
-Xdebug -Xrunjdwp:transport=dt_socket,address=10.0.5.60:50019,server=y,suspend=n
Then start the jetty server.
jetty server listening on the debug port
Everything seems fine. Then I config a remote profile in IntelliJ
IntelliJ remote debug profile
And start Debug, console shows
Connected to the target VM, address: '10.0.5.60:50019', transport: 'socket'
Wow, seems good. Bug things always happens, The breakpoints can't stop when I visit the running code. That was strange!
I promise I have logs to show that the break-point code must been exec-ed.
So, any one can give a hint to me? Thanks for ur great help.
Is it possible to setup JBoss server on one machine (PC) and then connect to it from another machine (laptop) ? I want to be able to run/deploy my application on the server on the PC and through Intellij on the laptop debug my code using that JBoss instance on the PC. I'm running a domain version of JBoss. Right now I have both the server and client running on the same machine. I'm not sure how to get around doing it, thanks for any help.
Yes it is possible to remote debug your application.
If you look at the first lines in the startup script standalone.[sh|bat], you'll see that debug agent can be enabled with the --debug command switch.
Switching this debug option will enable the JPDA and will listen on port 8787 by default.
This can also be achieved using JAVA_OPTS (look at the end of standalone.conf[.bat])
Once you started WildFly, you'll need to add a remote debug configuration in IntelliJ using the IP and port of your server. Here is the official documentation.
For remote deployment, you should have a look at the jboss-cli.
In Eclipse you can connect as follows, I'm sure Intellij must have something similar as well:
Run-> Debug Configuration->Remote Java Application. Here you can define the Host and Port of the application server, irrespective of it's location, be it local or any remote location.
I have the following configuration in the eclipse
Created a tomcat 7.0 server instance from the servers view.
Created a sample web application and deployed in the server through maven-tomcat-plugin and tested it in the browser ( started the server by right
clicking the server from the server view and selected start )
Tried to configure the remote debugging settings in the created server instance using JPDA options,i added the env variables in the server setting.
i could not connect the debugger to the server when i start the server from the eclipse as like previously.
But it connected seamlessly when i start the directly from the installation directory using the command prompt as like
catlina.bat jpda start
After that i tried this I started the server instance by ( started the server by right clicking the server from the server view and selected DEBUG mode)
I got the Break points in the code and even Hot Code replacement
working!!!
Can anyone explain the following?
What goes wrong when i tried jpda options for the remote debugging with the created server instance in the eclipse?
How the debug option and Hot Code replacement works with the server instance?Is this remote debugging or something else?Can you explain on this one?
the eclipse tomcat plugin spawns a separate JVM while running, you can confirm that in the windows task list, using ps in unix like systems or using visualVM.
That VM is launched in debug mode with the JPDA parameters set by the plugin itself, and that is how the debugging mechanism works, it's based on the JVM functionality. You can confirm which jpda parameters are used by using visual VM, that comes with the JDK.
I don't think you can override the JPDA parameters that the eclipse plugin setted for you, that's why in point 1) it did not work. For 2) it works via remote debugging made transparent by automatic setting the parameters and connecting the remote debugger once the server starts.
I'm working with a certain external server product which happens to be proprietary. However, I do have the ability to modify the server's startup scripts. What I'd like to do is essentially set debugging breakpoints in the custom module code which I'm writing so as to be able to fix a bug I'm experiencing in my code.
Is there a way to do this, integrating Eclipse with debugging an external process?
If that certain external server product is a Java server, you should be able to debug your code running in it through standard Java remote debugging.
In Eclipse, open the Debug configurations and add a new configuraion of type "Remote Java Application", and enter the hostname of the server and the port the remote debugger listens to.
In the server startup script, you may need to add an additional Java option to enable remote debugging for the JVM and specify the port. Something like this (excerpt from the JBoss startup config file):
# Sample JPDA settings for remote socket debugging
JAVA_OPTS="$JAVA_OPTS -Xrunjdwp:transport=dt_socket,address=8787,server=y,suspend=n"
(address - 8787 in this case - is the port to connect to)