Why after I started Middle Server, there always two java processes are running?

I started only one Middle Server , however , I am seeing two java processes are running

e.g

nohup java cat conf/druid/middleManager/jvm.config | xargs -cp conf/druid/_common:conf/druid/middleManager:lib/* org.apache.druid.cli.Main server middleManager &> middleManager.out &

Then, type unix>jps ( see 2 java processes running below )

  1. ec2-user 7459 6246 99 22:05 pts/0 00:00:09 java -server -Xms6g -Xmx6g -Duser.timezone=UTC -Dfile.encoding=UTF-8 -Djava.io.tmpdir=var/tmp -Djava.util.logging.manager=org.apache.logging.log4j.jul.LogManager -cp conf/druid/_common:conf/druid/middleManager:lib/* org.apache.druid.cli.Main server middleManager …

2). ec2-user 7557 7459 99 22:05 pts/0 00:00:10 java -cp conf/druid/_common:conf/druid/middleManager:lib/druid-services-0.13.0-incubating.jar:lib/druid-common-0.13.0-incubating.jar:lib/java-util-0.13.0-incubating.jar:lib/conf