According Setting up a Single Node Cluster https://hadoop.apache.org/docs/stable/hadoop-project-dist/hadoop-common/SingleCluster.html, we would still failed to run the MapReduce job example. Due to a security fix, yarn use user's environment variables to init, and user's environment variable usually doesn't include MapReduce related settings. So we need to add the related config in etc/hadoop/mapred-site.xml manually. Currently the log only tells there is an Error:
Could not find or load main class org.apache.hadoop.mapreduce.v2.app.MRAppMaster, without suggestion on how to solve it. I want to add the useful suggestion in log.