The thread dump is a list of all the Java threads that are currently active. If AEM does not respond properly, the thread dump can help you identify deadlocks or other problems.
Using Sling Thread Dumper
Open the AEM Web Console; for example at http://localhost:4502/system/console/.
Select the Threads under Status tab.
Using jstack (command line)
Find the PID (process id) of the AEM Java instance. For example, you can use ps -ef or jps.
Run: jstack pid
This will show the thread dump.
Note:
You can append the thread dumps to a log file by using the >> output redirection: