What I know is YARN is introduced and it replaced JobTracker and TaskTracker.
I have seen is some Hadoop 2.6.0/2.7.0 installation tutorials and they are configuring
mapreduce.framework.name as yarn and
mapred.job.tracker property as local or host:port.
The description for
mapred.job.tracker property is
"The host and port that the MapReduce job tracker runs at. If "local", then jobs are run in-process as a single map and reduce task."
My doubt is why are configuring it if we are using YARN , I mean JobTracker shouldn't be running right?
Forgive me if my question is dumb.
Edit: These are the tutorials I was talking about.
Best How To :
This is just a guess, but either those tutorials talking about configuring the JobTracker in YARN are written by people who don't know what YARN is, or they set it in case you decide to stop working with YARN someday. You are right: the JobTracker and TaskTracker do not exist in YARN. You can add the properties if you want, but they will be ignored. New properties for each of the components replacing the JobTracker and the TaskTracker were added with YARN, such as
yarn.resourcemanager.address to replace
If you list your Java processes when running Hadoop under YARN, you see no
You can read more about how YARN works here.