How to Obtain a Thread Dump (Stack Traces) from a Java Process or from a Core File of a Java Process on Linux

Applies To

Java SE JDK and JRE - Any Version
Generic Linux

Introduction

On Linux, there are multiple ways to obtain a Thread Dump (a Stack Trace for each thread) from a Java process, or from a core file of a Java process.

Tools for obtaining a thread dump on Linux

Tool	Works on a Process?	Works on a core file?	Java Frames?*	Native Frames?**
jstack	yes	yes	yes	only if -m is set
jcmd	yes	no	yes	no
kill -QUIT, kill -3	yes	no	yes	no
Ctrl + \	yes	no	yes	no
jconsole	yes	no	yes	no
jvisualm	yes	no	yes	no
gdb	yes	yes	no	yes

*‘Java Frames’ means that the tool is able to print a Java method name on the stack.
**‘Native Frames’ means that the tool is able to print symbolic or clear text name of a native function on the stack.

jstack

On Linux, jstack has been available since JDK 5. It is not available in the Java Runtime Environment (JRE). It is also not available on the Linux Itanium platform.

The jstack command prints the stack traces of all Java threads in a given Java process or core file. The -m option will print a mixed-mode stack so that you can see native frames in addition to the Java frames. Java thread names aren’t printed if mixed-mode is enabled.

jstack [option] <PID>
jstack [option] executable core
jstack [option] [server-id@]remote-hostname-or-IP

For more information on jstack, see the jstack Documentation.

jcmd

On Linux, jcmd has been available from JDK 7u4. It is not available in the JRE.

The jcmd command can print the stack traces of all Java threads in a given Java process. The -l option will also print java.util.concurrent locks.

jcmd <pid> Thread.print [-l]

For more information on jcmd, see the documentation for your version:

• JDK 25
• JDK 21
• JDK 17
• JDK 11
• JDK 8

kill -QUIT and kill-3

The /bin/kill command is bundled with most Linux derivates.

You can send a SIGQUIT signal to the target process. In that case the target process prints a thread dump to its standard output. The kill command allows you to specify the signal as a name without the SIG prefix:

kill -QUIT <PID>

or as a number (the value for the SIGQUIT signal is 3):

kill -3 <PID>

Make sure that you know where the log file is if standard output has been redirected.

Ctrl+\

On Linux, the combination of pressing the Ctrl key and the backslash (\ key at the application console (standard input) causes the Java HotSpot VM to print a thread dump to the application’s standard output.

JConsole

On Linux, the JConsole has been available since JDK 5. It is not available in the JRE. Note that the program is called JConsole, and that the Java Console is something different.

JConsole provides a graphical user interface and its purpose is to monitor a running Java process.

In order to obtain a stack trace, connect JConsole to the process and click on the Threads tab. The Threads list in the lower left corner lists all Java threads. Click on the name of a thread in the Threads list to display the stack trace about that thread to the right.

See Also

• JConsole Documentation
• JConsole Command Line Reference

Java VisualVM (jvisualvm)

javavisualvm was first bundled with Java SE in JDK 6u7. It is not available in the JRE. Similarly to JConsole, Java VisualVM provides a graphical user interface.

In order to obtain a stack trace, connect Java VisualVM to the process and click on the Threads Tab. The Threads list lists all Java threads. Click on the Thread Dump button in order to obtain a thread dump.

See Also

• Java VisualVM - Monitoring Application Threads
• Java Visual VM Command Line Usage

gdb

On Linux, gdb (the GNU Debugger) can be used to debug the Java HotSpot VM because it is compiled using gcc (the GNU C++ Compiler). gdb is available on most Linux derivates by default. It is a general purpose debugger and it can obtain stack traces from both core files and live processes. In order to avoid privilege problems, it helps to run gdb with root privileges:

sudo gdb executable { core | pid }

Once attached successfully you can work with the gdb commands. The prompt is set to (gdb). In order to get a list of the threads enter:

(gdb) info threads

An asterisk ’*’ to the left of the gdb thread number indicates the current thread. You can select a thread by typing “thread” followed by the thread id:

(gdb) thread 1

In order to get a stack trace of the current thread (in the example it is thread #1), just enter bt or backtrace:

(gdb) bt

In order to get stack traces for all threads, you can type:

(gdb) thread apply all bt

You can execute gdb in non-interactive mode as well:

gdb --pid=<PID> --batch -ex "thread apply all bt"

Last reviewed on Sat Feb 01 2025 00:00:00 GMT+0000 (Coordinated Universal Time)