I have SQL Server 2012(11.0.3373) instance with AlwaysON setup. I see cyclic blocking where two sessions block each other forever(till one of them is killed), but does not get deadlocked. Unable to understand why does not it deadlock.
session_id | blocking_session_id | wait_info |
78 | 191 | (9266538ms)LCK_M_SCH_M |
191 | NULL | (36ms)ASYNC_NETWORK_IO |
191 | 78 | (9266529ms)LCK_M_IS |