Solution : https://service.sap.com/sap/support/notes/1566295 (SAP Service marketplace login required)
Key words : 
process potentially yields opening, unsafe multi thread code, possibly corrupted stepinfo pointers, iteration workflow lock yielding, - change list #95525mdm 7, - change list #95524mdm 7, - change list #95520o, master data server, [workflow run time], symptom mdm server
Related Notes : 
       
| 1569145 | SAP Release Note for MDM 7.1 SP06 Patch10 |