CCD-410 試験問題を無料オンラインアクセス

On a cluster running MapReduce v1 (MRv1), a TaskTracker heartbeats into the JobTracker on your cluster, and alerts the JobTracker it has an open map task slot.
What determines how the JobTracker assigns each map task to a TaskTracker?

• A.The amount of free disk space on the TaskTracker node.
• B.The number and speed of CPU cores on the TaskTracker node.
• C.The amount of RAM installed on the TaskTracker node.
• D.The location of the InsputSplit to be processed in relation to the location of the node.
• E.The average system load on the TaskTracker node over the past fifteen (15) minutes.

Which best describes how TextInputFormat processes input files and line breaks?

• A.Input file splits may cross line breaks. A line that crosses file splits is read by the RecordReader of the split that contains the end of the broken line.
• B.Input file splits may cross line breaks. A line that crosses file splits is read by the RecordReaders of both splits containing the broken line.
• C.The input file is split exactly at the line breaks, so each RecordReader will read a series of complete lines.
• D.Input file splits may cross line breaks. A line that crosses file splits is ignored.
• E.Input file splits may cross line breaks. A line that crosses file splits is read by the RecordReader of the split that contains the beginning of the broken line.

You want to run Hadoop jobs on your development workstation for testing before you submit them to your production cluster. Which mode of operation in Hadoop allows you to most closely simulate a production cluster while using a single machine?

• A.Run the hadoop command with the -jt local and the -fs file:///options.
• B.Run simldooop, the Apache open-source software for simulating Hadoop clusters.
• C.Run the DataNode, TaskTracker, NameNode and JobTracker daemons on a single machine.
• D.Run all the nodes in your production cluster as virtual machines on your development workstation.

When can a reduce class also serve as a combiner without affecting the output of a MapReduce program?

• A.When the types of the reduce operation's input key and input value match the types of the reducer's output key and output value and when the reduce operation is both communicative and associative.
• B.Always. Code can be reused in Java since it is a polymorphic object-oriented programming language.
• C.Never. Combiners and reducers must be implemented separately because they serve different purposes.
• D.When the signature of the reduce method matches the signature of the combine method.
• E.Always. The point of a combiner is to serve as a mini-reducer directly after the map phase to increase performance.

You've written a MapReduce job that will process 500 million input records and generated 500 million key-value pairs. The data is not uniformly distributed. Your MapReduce job will create a significant amount of intermediate data that it needs to transfer between mappers and reduces which is a potential bottleneck. A custom implementation of which interface is most likely to reduce the amount of intermediate data transferred across the network?

• A.Writable
• B.OutputFormat
• C.Combiner
• D.InputFormat
• E.Partitioner
• F.WritableComparable