sender1.setParallelism(NUM_TASKS);
sender2.setParallelism(NUM_TASKS);
receiver.setParallelism(NUM_TASKS);
SlotSharingGroup sharingGroup = new SlotSharingGroup(sender1.getID(), sender2.getID(), receiver.getID());
sender1.setSlotSharingGroup(sharingGroup);
sender2.setSlotSharingGroup(sharingGroup);
receiver.setSlotSharingGroup(sharingGroup);;
receiver.connectNewDataSetAsInput(sender1, DistributionPattern.POINTWISE);