2487607 - Deadlock for normal / low priority requests detected

SAP system starts but you cannot login via SAP GUI - it's just hanging and doesn't move forward.

In dev_disp following entries appear:

Sat Jun 10 14:27:08:032 2017*** WARNING => DpDeadlockCheck: potential deadlock detected (33. check) [dpxxwp.c     4522]
Sat Jun 10 14:27:09:032 2017*** WARNING => DpDeadlockCheck: potential deadlock detected (34. check) [dpxxwp.c     4522]
Sat Jun 10 14:27:10:033 2017*** WARNING => DpDeadlockCheck: potential deadlock detected (35. check) [dpxxwp.c     4522]

and

********** SERVER SNAPSHOT 1 (Reason: Deadlock for normal priority requests detected) - begin **********

Prio Class Normal
maxRuntime[RQ_Q_PRIO_NORMAL] = 3600 sec
maxRuntimeHalf[RQ_Q_PRIO_NORMAL] = 1800 sec
maxTicketsForPrio[RQ_Q_PRIO_NORMAL] = 0
maxTicketsForPrioIncrement[RQ_Q_PRIO_NORMAL] = 0
withPrioTickets[RQ_Q_PRIO_NORMAL] = true
maxTicketsForPrio[RQ_Q_PRIO_NORMAL] explicitly set with parameters rdisp/rfc_min_wait_dia_wp and/or rdisp/http_min_wait_dia_wp

or

********** SERVER SNAPSHOT 1 (Reason: Deadlock for low priority requests detected) - begin **********

Prio Class Low
maxRuntime[RQ_Q_PRIO_LOW] = infinite
maxRuntimeHalf[RQ_Q_PRIO_LOW] = infinite
maxTicketsForPrio[RQ_Q_PRIO_LOW] = 0
maxTicketsForPrioIncrement[RQ_Q_PRIO_LOW] = 0
withPrioTickets[RQ_Q_PRIO_LOW] = true
maxTicketsForPrio[RQ_Q_PRIO_LOW] explicitly set with parameters rdisp/rfc_min_wait_dia_wp and/or rdisp/http_min_wait_dia_wp

and

Found 0 active workprocesses
Total number of workprocesses is xx

or

Found x active workprocesses
Total number of workprocesses is xx

(where number of active work processes is much less than total number of work processes)

• SAP Kernel 7.4x
• SAP NetWeaver 7.4
• SAP NetWeaver 7.5

scheduler , RFC , HTTP , KBA , BC-CST-DP , Dispatcher, Task Handler , Problem