From [this discussion](https://stackoverflow.com/questions/10360030/), there are two opinions of what [Thread#activeCount()](https://docs.oracle.com/javase/7/docs/api/java/lang/Thread.html) returns.

1. An "active thread" is actually executing bytecode. It is a thread that was started and is not waiting on IO or on a lock.
2. An "active thread" is in the `run()` method. I.e., a nonactive thread has not started the `run()` method or has exited that method.

What is the actual meaning?

(I ask on Software Engineering as StackOverflow disfavors such explanation questions.)