it comes at the time of mapreduce only right ?. if then it will be the map/reduce process. please grep the process id and take what exactly the process it is. If it is map/reduce process then one option is to recheck your mapreduce code. If that is also fine yarn cgroup may help.
If you want to kill this process you need to kill the yarn job associated with it. To get the runnning yarn applications you can use RM UI or yarn application -list command
To kill job : yarn application -kill application_id