int low = 0;
            int high = instances.size()-1;
            while (low < high)
            {
                int mid = (low+high)/2;
                //if i's value is less than mid's value, then high = mid-1
                if(i.priority < instances.get(mid).priority)
                    high = mid-1;
                else if(i.priority > instances.get(mid).priority)
                    low = mid+1;
                else
                {
                    instances.add(mid, i);
                    inserted = true;
                    low = high;
                }
            }
            if(low >= high && inserted == false)
                instances.add(low, i);