Technical Interview Questions
No, There are many ways to deal with non-java codes. HadoopStreaming allows any shell command to be used as a map or reduce function. No, it is not necessary to write jobs for Hadoop in the Java language. Hadoop supports multiple programming languages for writing MapReduce jobs. The primary language for Hadoop MapReduce is Java, … Read more
The TaskTracker periodically sends heartbeat messages to the JobTracker to assure that it is alive. This messages also inform the JobTracker about the number of available slots. This return message updates JobTracker to know about where to schedule task. In Hadoop MapReduce, the JobTracker is responsible for assigning tasks to TaskTrackers. The process involves the … Read more
JobTracker is a giant service which is used to submit and track MapReduce jobs in Hadoop. Only one JobTracker process runs on any Hadoop cluster. JobTracker runs it within its own JVM process. Functionalities of JobTracker in Hadoop: When client application submits jobs to the JobTracker, the JobTracker talks to the NameNode to find the … Read more
Hadoop job – list Hadoop job – kill jobID In Hadoop, you can use the following commands in Linux to see all jobs running in the cluster and kill a job: To see all running jobs: mapred job -list This command will provide a list of all running jobs in the Hadoop cluster. To kill … Read more
Distributed cache is a facility provided by MapReduce Framework. It is provided to cache files (text, archives etc.) at the time of execution of the job. The Framework copies the necessary files to the slave node before the execution of any task at that node. In Hadoop, the Distributed Cache is a mechanism that allows … Read more