"vcores used" in cluster metrics(yarn resource manager ui) when running spark on yarn

[yuemeng1]

Hi, all
    When i running an app with this cmd:  ./bin/spark-sql --master 
yarn-client --num-executors 2 --executor-cores 3, i noticed that yarn 
resource manager ui  shows the `vcores used` in cluster metrics is 3. It 
seems `vcores used` show wrong num (should be 7?)? Or i miss something?

Thanks