I have a java application running on linux machine. I run the java application using the following:
java myapp -Xdebug -Xrunjdwp:server=y,transport=dt_socket,address=4000, suspend=n
I have opened port 4000 for TCP on this Linux machine. I use eclipse from Windows XP machine and try to connect to this application. I have opened the port in windows also.
Both machines are on the LAN but I can't seem to connect the debugger to the Java application. What am I doing wrong?
Edit: I noticed that some people are cutting and pasting the invocation here. The answer I originally gave was relevant for the OP only. Here's a more modern invocation style (including using the more conventional port of 8000):
java -agentlib:jdwp=transport=dt_socket,server=y,address=8000,suspend=n <other arguments>
Original answer follows.
Try this:
java -Xdebug -Xrunjdwp:server=y,transport=dt_socket,address=4000,suspend=n myapp
Two points here:
runjdwp
option. For JDK 1.3 or earlier :
-Xnoagent -Djava.compiler=NONE -Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=n,address=6006
For JDK 1.4
-Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=n,address=6006
For newer JDK :
-agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=6006
Please change the port number based on your needs.
From java technotes
From 5.0 onwards the -agentlib:jdwp option is used to load and specify options to the JDWP agent. For releases prior to 5.0, the -Xdebug and -Xrunjdwp options are used (the 5.0 implementation also supports the -Xdebug and -Xrunjdwp options but the newer -agentlib:jdwp option is preferable as the JDWP agent in 5.0 uses the JVM TI interface to the VM rather than the older JVMDI interface)
One more thing to note, from JVM Tool interface documentation :
JVM TI was introduced at JDK 5.0. JVM TI replaces the Java Virtual Machine Profiler Interface (JVMPI) and the Java Virtual Machine Debug Interface (JVMDI) which, as of JDK 6, are no longer provided.
Steps:
See Step by Step guide on Java remote debugging for full details.
Answer covering Java >= 9:
For Java 9+, the JVM option needs a slight change by prefixing the address with the IP address of the machine hosting the JVM, or just *
:
-agentlib:jdwp=transport=dt_socket,server=y,address=*:8000,suspend=n
This is due to a change noted in https://www.oracle.com/technetwork/java/javase/9-notes-3745703.html#JDK-8041435 .
For Java < 9, the port number is enough to connect.
I'd like to emphasize that order of arguments is important .
java -agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=8000 -jar app.jar
command opens debugger port ,
but java -jar app.jar -agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=8000
command doesn't . It will pass everything after app.jar as command-line arguments.
This is how you should setup Eclipse Debugger for remote debugging:
Eclipse Settings:
1.Click the Run Button
2.Select the Debug Configurations
3.Select the “Remote Java Application”
4.New Configuration
For JBoss:
1.Change the /path/toJboss/jboss-eap-6.1/bin/standalone.conf
in your vm as follows: Uncomment the following line by removing the #:
JAVA_OPTS="$JAVA_OPTS -agentlib:jdwp=transport=dt_socket,address=8787,server=y,suspend=n"
For Tomcat :
In catalina.bat file :
Step 1:
CATALINA_OPTS="-Xdebug -Xrunjdwp:transport=dt_socket,address=8000,server=y,suspend=n"
Step 2:
JPDA_OPTS="-agentlib:jdwp=transport=dt_socket,address=8000,server=y,suspend=n"
Step 3: Run Tomcat from command prompt like below:
catalina.sh jpda start
Then you need to set breakpoints in the Java classes you desire to debug.
From Java 9, the JDWP socket connector accepts only local connections by default. See: http://www.oracle.com/technetwork/java/javase/9-notes-3745703.html#JDK-8041435
So, to enable debug connections from outside, specify *: as address:
-agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=*:5005
for everybody that has the problem that if you really do remote debugging from 1 machine to the other then using :
-agentlib:jdwp=transport=dt_socket,server=y,address=8000,suspend=n
is not enough because that binds now (at least on unix/osx machines) to localhost so you can only connect to it from localhost.
If you try to remote debug this then you will get connection refused for this. From i think Java 9 on you need to do:
-agentlib:jdwp=transport=dt_socket,server=y,address=*:8000,suspend=n
or give an ip that it needs to bind on for hat *
The best option of debugging is to create logs and analyze logs. But in some cases we need to debug web application deployed on server.
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