How to get the number of threads in a Java process

Question

How can I see the number of threads in a Java process?

Answer 1

There is a static method on the Thread Class that will return the number of active threads controlled by the JVM:

Thread.activeCount()

Returns the number of active threads in the current thread's thread group.

Additionally, external debuggers should list all active threads (and allow you to suspend any number of them) if you wish to monitor them in real-time.