A classic "Where’s Waldo" experience for system administrators.
The basic syntax of jstack is:
When an application hangs without progress, use jstack to identify threads waiting indefinitely for locks:
jcmd <pid> Thread.print
Replace jdk-21.0.2 with the exact name of the extracted directory.
If javac is not found, you likely only have a JRE installed, and you will need to install a full JDK.
Run jstack followed by the PID to output the thread dump to your terminal console: jstack 12345 Use code with caution. 3. Save the Thread Dump to a File install jstack on ubuntu
If you are currently debugging a live application issue, tell me: What are you targeting? What error message (if any) are you seeing in your console?
You can verify that jstack is available by running:
This public link is valid for 7 days and shares a thread, including any personal information you added. This link or copies made by others cannot be deleted. If you share with third parties, their policies apply. Can’t copy the link right now. Try again later. Run jstack followed by the PID to output
sudo apt update sudo apt install openjdk-11-jdk
grep -A 10 "Found one Java-level deadlock" thread_dump_*.txt
Once the installation finishes, confirm that Ubuntu recognizes jstack and that it matches your active Java version. which jstack jstack -version Use code with caution. What error message (if any) are you seeing in your console
Before installing new software, ensure your local package index is up to date: sudo apt update 2. Install the JDK