See this thread:

http://www.jboss.org/modules/bb/index.html?module=bb&op=viewtopic&t= Linux will show a thread as a process in it's own right. pstree shows the actual parent process and the child processes. So your 45 processes are actually one real process with multiple threads (marked as children) - note that they all have the same RSS if you "ps aux".

They may have altered ps in RedHat 8.0 to only show the parent.

To confirm:
RedHat 8.0 has a patched procps 2.0.7 that shows only processes, not threads. procps 2.0.10 (general release) also incorporates same. -m in ps and H key in top shows threads with the 2.0.10 release.

There shouldn't be any zombie processes after a shutdown. However, it may be a while before all threads get cleaned up. The script will most likely return before the JBoss server processes themselves are shutdown. If you ps just after the script returns, you will most likely see some zombies as the server is still in the process of shutting down. Give it time and they should all disappear. If they don't, then you might have some problems.