Works as local reducer to the node where Mapper’s output has been combined to minimize traffic between Mapper and Reducer.
The tasks are processed and stored in bulk before being sent to the Reducer, meaning the data from Mapper is processed in chunks, the size of which is configurable. Once the combined results reach the specified chunk size, the elements are forwarded to the Reducer.
public interface ICombiner : IDisposable
This method will provide the user with a starting point to initialize any parameters you want to be used before the actual combining of elements begins.
This method reduces the task result locally in chunks so that the Reducer is not burdened with excessive processing. If the workflow diagram is referred, it means that the elements with the same keys are grouped together before being sent to the Reducer for counting the word occurrence.
This method marks the end of the Combiner functionality as when the number of combined results reaches the specified chunk size, it sends the tasks in the form of a chunk to the Reducer and resets its internal state for the next chunk.