code: private void executeAggregateTasklet(final ExecutorService commandExecutor,
                                         final MasterToWorkerRequest masterToWorkerRequest) {
      final TaskletAggregateExecutionRequest taskletAggregateExecutionRequest =
          (TaskletAggregateExecutionRequest) masterToWorkerRequest;
  
      assert aggregates.containsKey(taskletAggregateExecutionRequest.getAggregateFunctionId());
  
      final AggregateContainer aggregateContainer =
          aggregates.get(taskletAggregateExecutionRequest.getAggregateFunctionId());
      final TaskletAggregationRequest aggregationRequest = aggregateContainer.getTaskletAggregationRequest();
  
      commandExecutor.submit(new Runnable() {
        @Override
        public void run() {
          try {
            aggregateContainer.scheduleTasklet(taskletAggregateExecutionRequest.getTaskletId());
            final Object result = aggregationRequest.executeFunction(taskletAggregateExecutionRequest.getInput());
            aggregateContainer.taskletComplete(taskletAggregateExecutionRequest.getTaskletId(), result);
          } catch (final Exception e) {
            aggregateContainer.taskletFailed(taskletAggregateExecutionRequest.getTaskletId(), e);
          }
        }
      });
    }
docs: Executes an aggregation request from the {@link org.apache.reef.vortex.driver.VortexDriver}.