General :: Htop - Find The PID Thats Causing The High CPU Cycles?

Just trying to figure out some stuff with a broken process. A java app seems to sometime get stuck on a loop or something and i'm trying to find out what's causing it using just the following #sysadmin tools at my disposal.

Things like:- htop - find the PID thats causing the High CPU cycles. I'd then want to use /proc/[PID] or lsof -p [PID] or strace [PID] etc. But the PID doesn't exist in 'ps -ef' output so I think htop must be showing me kernel level thread PIDs?

Not sure about the PID's HTOP is actually giving me? I know that some of them are the real PID's that can be accessed through /proc/[pid] etc but others are not but are i assume child processes or more likely threads as child processes are normally shown in a default ps output anyway.

Is someone able to help distinguish to me about what exactly all these other PID's are that I can't manipulate or find apart from when using HTOP.