Spark-shell --master yarn stuck
I experienced a similar issue an was caused by the fact that I forgot to append /conf to HADOOP_CONF_DIR env variable (/etc/hadoop/conf).
In my case I was running spark 2.1 cloudera distribution and specified HADOOP_CONF_DIR=/etc/hadoop/conf/:/etc/hive/conf/ . Due to some reason it was getting stuck so I modified it to HADOOP_CONF_DIR=/etc/hadoop/conf/ and it worked. Still looking for the root cause !