error rendering block light both in client and server,causing mobs spawning at places which light level are supposed to be >7

Light sources frequently stop working,like the torch or pumpkin lattern,light level below 7 or even 0 can be observed by pressing F3.Using client only can performs better(problem still,but a bit brighter),but in server,my slime farm almost stops working because of the wrongly rendering light level.Please fix it as soon as possible,this issue had lasted for several versions.