directly compute number of tasks for MPILoadBalancer, taskIndex-->tid
directly compute number of tasks for MPILoadBalancer, taskIndex-->tid

MengjiaoH/ospray,ospray/OSPRay,MengjiaoH/ospray,ospray/OSPRay,MengjiaoH/ospray,wilsonCernWq/ospray,ospray/OSPRay,wilsonCernWq/ospray,MengjiaoH/ospray,wilsonCernWq/ospray,ospray/OSPRay,MengjiaoH/ospray