Get a list of all threads currently running in Java
To get an iterable set:
Set<Thread> threadSet = Thread.getAllStackTraces().keySet();Performance: 0 ms for 12 threads (Azul JVM 16.0.1, Windows 10, Ryzen 5600X).
Get a handle to the root ThreadGroup, like this:
ThreadGroup rootGroup = Thread.currentThread().getThreadGroup();ThreadGroup parentGroup;while ((parentGroup = rootGroup.getParent()) != null) { rootGroup = parentGroup;}Now, call the enumerate() function on the root group repeatedly. The second argument lets you get all threads, recursively:
Thread[] threads = new Thread[rootGroup.activeCount()];while (rootGroup.enumerate(threads, true ) == threads.length) { threads = new Thread[threads.length * 2];}Note how we call enumerate() repeatedly until the array is large enough to contain all entries.
Yes, take a look at getting a list of threads. Lots of examples on that page.
That's to do it programmatically. If you just want a list on Linux at least you can just use this command:
kill -3 processidand the VM will do a thread dump to stdout.