CODEWITHSUNDEEP
javadebuggingremote-debugging
Guru
Guru

Reputation:

Remote debugging a Java application

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?

Upvotes: 299

Views: 508340

Answers (8)

C. K. Young
C. K. Young

Reputation: 222973

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>

Note: With address=8000 (as used above), the debug server will only listen on localhost (see What are Java command line options to set to allow JVM to be remotely debugged?). If you want the server to listen on all interfaces, to be able to debug across the network, use address=*:8000. Obviously only do this on a restricted, trusted network...

Original answer follows.

Try this:

java -Xdebug -Xrunjdwp:server=y,transport=dt_socket,address=4000,suspend=n myapp

Two points here:

  1. No spaces in the runjdwp option.
  2. Options come before the class name. Any arguments you have after the class name are arguments to your program!

Upvotes: 533

kabanowster
kabanowster

Reputation: 1

Every solution here is describing the method to attach debugger after the application starts. In the "debugger listening" setup you need to set server=n and suspend=n. If not the Gradle will throw permission denied error.

build.gradle:

run {
    jvmArgs = ["-agentlib:jdwp=transport=dt_socket,server=n,suspend=n,address=5005"
}

Upvotes: 0

M A
M A

Reputation: 72844

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/java/technologies/javase/9-all-relnotes.html#JDK-8041435.

For Java < 9, the port number is enough to connect.

Upvotes: 50

JCompagner
JCompagner

Reputation: 51

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 *

Upvotes: 2

MrBlack
MrBlack

Reputation: 399

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.

Upvotes: 18

Pritam Banerjee
Pritam Banerjee

Reputation: 18923

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

  • Name : GatewayPortalProject
  • Project : GatewayPortal-portlet
  • Connection Type: Socket Attach
  • Connection Properties: i) localhost ii) 8787

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.

Upvotes: 3

Sairam Krish
Sairam Krish

Reputation: 11661

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.

Upvotes: 95

Gaurav
Gaurav

Reputation: 339

Steps:

  1. Start your remote java application with debugging options as said in above post.
  2. Configure Eclipse for remote debugging by specifying host and port.
  3. Start remote debugging in Eclipse and wait for connection to succeed.
  4. Setup breakpoint and debug.
  5. If you want to debug from start of application use suspend=y , this will keep remote application suspended until you connect from eclipse.

See Step by Step guide on Java remote debugging for full details.

Upvotes: 33

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