Hi Karthikeyan,
I am using ParFoEach only and three workitems are generated parallely and i can see them in workflow log . I have put program exit in user decison step at 'after work item creation' event. So only ideally it should have fire three emails for three work item but here only one email is getting fired instead of three 
. Anyway willl check logic of program exit again and came back to you 
Regards
Ajit.