Solution : https://service.sap.com/sap/support/notes/1147287 (SAP Service marketplace login required)
Key words : 
function module sxms_async_exec, relevant support package, short dump occurs, xi lock logic, short dumps, lock triggered, xi processes, xi messages, report rsqiwkex, start processing
Related Notes : 
       
| 1352797 | XI runtime: System log if queue is executed twice | 
| 1170710 | XI 30 Support Package Stack (SPS) 23 | 
| 1170144 | NW04s Support Package Stack 16 | 
| 1118297 | XI runtime: QRFC processing of messages | 
| 1058915 | Outbound queue remains in status 'SYSFAIL' |