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How to Generate a Thread Dump

When the NetBeans IDE freezes or becomes sluggish for no apparent reason, it's a recommended to generate a thread dump and attach file to the reported bug. Do not copy the thread dump into the description field.

The Thread Dump

... is a textual dump of all active threads and monitors of Java apps running in a Virtual Machine.

To generate thread dump:

• Windows
  • Press Ctrl-Break in the command console you used to start the IDE
    If the console isn't opened (in case you started the IDE using the default desktop icon):
    • launch the IDE using a console window
      (invoke Command Prompt, go to {netbeans-install-dir}/bin and type nb.exe)
    • configure the desktop shortcut to launch the nb.exe instead of netbeans.exe (default)

• Unix, Linux, Mac OS X
  • press Ctrl-\ in the terminal console you used to start the IDE
  • send the QUIT signal to the Java VM running the IDE
    kill -QUIT process_id
    process_id is the process number of the respective java process

• jstack tool

... is a monitoring tool that is part of JDK installation. The documentation:

1. jstack from JDK1.5.0
2. jstack from JDK6.0
3. On Mac OS X, jstack sometimes fails with an error message. As a workaround, you can generate a thread dump using killall -9 hsdbd; sudo jstack pid

• StackTrace tool

... allows to get thread dump even without console. It works on all platforms and for all JDKs.

1. launch from http://www.adaptj.com/root/webstart/stacktrace/app/launch.jnlp
2. details http://www.adaptj.com/root/main/stacktrace

To generate thread dump:

1. select main menu item "Process|Thread Dump..."
2. in dialog click "..." button to open process ID chooser
3. select PID from the list and confirm the chooser
4. click OK to request thread dump

• VisualVM

The VisualVM is a tool that provides a visual interface for troubleshooting, profiling and viewing detailed information about Java applications while they are running on a Java Virtual Machine. Avalaible as part of JDK or from download page.

To generate thread dump:

1. Run VisualVM
2. Invoke popup menu on the program node
3. Select Thread Dump