Run the command with sudo and match the user ID of the running Java application: sudo -u jstack Use code with caution. Error: "ptrace_attach failed"
Find the PID of your running Java application using jps (Java Virtual Machine Process Status Tool): jps -l Use code with caution. Alternatively, use the standard Linux command: ps aux | grep java Use code with caution. 2. Generate a Thread Dump
jstack is a Java utility that provides a snapshot of the Java Virtual Machine (JVM) thread stacks. It's a useful tool for diagnosing and troubleshooting Java applications.
Pass the PID to jstack to output the real-time thread dump to your terminal: jstack Use code with caution. 3. Save the Thread Dump to a File For deep analysis, redirect the output to a text file: jstack > thread_dump.txt Use code with caution. Troubleshooting Common Errors 1. "jstack: command not found" You installed the JRE instead of the JDK.
Use sudo -u jstack to run the tool as the process owner. 3. "Well-known file is not secure" install jstack on ubuntu
(Note the path displayed, for example: /usr/lib/jvm/java-17-openjdk-amd64/ ) Open your environment file: sudo nano /etc/environment Use code with caution.
You likely only have the Java Runtime Environment (JRE) installed. jstack requires the Development Kit (JDK). Skip to Step 3. Step 2: Update Your Package Repository
jstack <executable> <core_file>
# Java 11 sudo apt install openjdk-11-jdk Run the command with sudo and match the
The jstack command is included in the JDK, so you don't need to install it separately. However, you need to find the location of the jstack command:
: You can install various versions of OpenJDK. JDK 11 or JDK 17 are excellent choices as they are long-term support (LTS) versions.
Ensure the user running jstack has write permissions to /tmp , or clear disk space on that partition. To help me tailor this guide, let me know: What Java version are you running? Is this for a local machine or a production server ?
This is a popular Long-Term Support (LTS) version, known for its stability and widespread use. Pass the PID to jstack to output the
To get jstack , you must install the JDK. You can choose between OpenJDK (the open-source implementation) or Oracle JDK. OpenJDK is recommended for most Ubuntu users. Option A: Install the Default OpenJDK (Recommended)
Once I actually installed the JDK, jstack worked like a charm. It gave me that sweet, sweet hexadecimal nid (native id) I needed to kill the runaway thread. It turns a chaotic CPU spike into a readable murder mystery.
The easiest way to get jstack is to install the default Java Development Kit provided by the Ubuntu repositories. This package automatically bundles jstack along with the compiler ( javac ) and other development tools. Step 1: Update the Package Index