thr_join, thr_create(), and thr_exit

Starting from the threads list, you can determine which thread id came from which start function. The "base function" as it is known, is printed in the thread listing.

When you attach to an existing multithreaded process, it is non-deterministic which thread becomes the active thread.

When the active thread does a thr_create, the current threads stays with the "creating thread". In the follow_fork analogy, it would be parent.

The Sun multithreaded model doesn't have true fork semantics for threads. There is no thread tree, and no parent-child relationships as there is with processes. thr_join() is only a simplified veneer.

When the active thread does a thr_exit, dbx makes a dummy "dead" thread as the active thread. This thread is represented as t@X.