If you are running Hadoop on a development machine, then it’s likely that you’ll run into a situation where multiple services require port 8080. I recently ran into this issue where both the Pentaho User Console and the Hadoop MapReduce ShuffleHandler were trying to use port 8080.
One solution is to change the port used by the Hadoop MapReduce ShuffleHandler, which is what I’m going to configure below.
sudo vi /etc/hadoop/conf/mapred-site.xml
Add the following as a new property by adding it just before the </configuration> element.
<property> <name>mapreduce.shuffle.port</name> <value>8080</value> <description>Default port that the ShuffleHandler will run on. ShuffleHandler is a service run at the NodeManager to facilitate transfers of intermediate Map outputs to requesting Reducers.</description> </property>
Then restart the YARN daemons.