Sharing data between master and reduce

Question

I need to perform aggregation using the results form all the reduce tasks. Basically the reduce task finds the sum and count and a value. I need to add all the sums and counts a

Answer 1

Found the solution. I used counters

http://diveintodata.org/2011/03/15/an-example-of-hadoop-mapreduce-counter/

public class FlightData {

//enum for counters used by reducers
public static enum FlightCounters {
    FLIGHT_COUNT,
    FLIGHT_DELAY;
}
public static class MyReducer 
extends Reducer {

    public void reduce(Text key, Iterable values, 
            Context context
            ) throws IOException, InterruptedException {


        delay1 = Float.parseFloat(origin[5]);
        delay2 = Float.parseFloat(dest[5]);
        context.getCounter(FlightCounters.FLIGHT_COUNT).increment(1);
        context.getCounter(FlightCounters.FLIGHT_DELAY)
        .increment((long) (delay1 + delay2));

    }
}
public static void main(String[] args) throws Exception{
    float flightCount, flightDelay;
    job.waitForCompletion(true);
    //get the final results updated in counter by all map and reduce tasks
    flightCount = job.getCounters()
            .findCounter(FlightCounters.FLIGHT_COUNT).getValue();
    flightDelay = job.getCounters()
            .findCounter(FlightCounters.FLIGHT_DELAY).getValue();
}

}