resmgr:pq qeued, all sessions wait for others!!

Hi,

we have a read DB 11.2.0.4 for reporting with 8 Cores (16 threads), we want to set the db for automatic parallel execution (degree = 3) as the following:

parallel_degree_limit= 3

parallel_degree_policy=AUTO

parallel_max_servers = 12

parallel_servers_target=10

parallel_threads_per_cpu = 2

parallel_adaptive_multi_user = true

when testing the db with multiple sessions, the DB hang on resmgr:pq qeued (class wait scheduler)!

what the problem here, that make the whole stmts waiting for for resmgr:pq qeued?!?

regards