A. Writable

B. OutputFormat

C. InputFormat

D. Partitioner

E. Combiner

F. WritableComparable

A. Lightweight devices for synchronization within MapReduce programs. You can use counters to coordinate execution between a mapper and a reducer.

B. Lightweight devices for ensuring the correctness of a MapReduce program. Mappers Increment counters, and reducers decrement counters. If at the end of the program the counters read zero, then you are sure that the job completed correctly.

C. Lightweight devices for bookkeeping within MapReduce programs.

A. The node with the most free local disk space

B. The node with the most memory

C. The node with the lowest system load

D. The node on which this InputSplit is stored

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 RecordReader of the split that contains the beginning of the broken line.

C. 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.

D. The input file is split exactly at the line breaks, so each Record Reader will read a series of complete lines.

E. Input file splits may cross line breaks. A line that crosses tile splits is ignored.

A. The NameNode periodically pings the datanode. If the DataNode does not respond, the NameNode considers the DataNode as failed.

B. When the NameNode fails to receive periodic heartbeats from the DataNode, it considers the DataNode as failed.

C. When HDFS starts up, the NameNode tries to communicate with the DataNode and considers the DataNode as failed if it does not respond.

D. The NameNode does not need to know that a DataNode has failed.

A. A failed task attempt is a task attempt that threw an unhandled exception. A killed task attempt is one that was terminated by the JobTracker.

B. A failed task attempt is a task attempt that completed, but with an unexpected status value. A killed task attempt is a duplicate copy of a task attempt that was started as part of speculative execution.

C. A failed task attempt is a task attempt that threw a RuntimeException (i.e., the task fails). A killed task attempt is a task attempt that threw any other type of exception (e.g., IOException); the execution framework catches these exceptions and reports them as killed.

D. A failed task attempt is a task attempt that did not generate any key value pairs. A killed task attempt is a task attempt that threw an exception, and thus killed by the execution framework.