Earning Points. Starwood's Preferred Guest program is fairly straightforward: the more nights you spend at participating hotels, the faster you'll earn a free night.
As seen in the EXECUTING phase, the map will write (using Mapper.Context.write()) its output into a circular in-memory buffer (MapTask.MapOutputBuffer). The size of this buffer is fixed and determined by the configuration parameter mapreduce.task.io.sort.mb (default: 100MB).
The Application Master asks for: 1  a container located on the same Node Manager where the map split is stored (a map split may be stored on multiple nodes due to the HDFS replication factor); 2  otherwise, a container located on a Node Manager in the same rack where the the map split is stored;