dbms_hang_manager caused db hang 19c
19C generated:
DIA0 Critical Database Process As Root: Hang ID 1 blocks 42 sessions
Final blocker is session ID 996 serial# 46299 OSPID 4861 on Instance 1
If resolvable, instance eviction will be attempted by Hang Manager
and minutes later, DB, DB server was on hang.
No alert log, incident files kept once server rebooted.