[jcoffland]

Increasing the hash table size would be bad for embedded systems and would not reduce the complexity for problems like the one described here. In general, hash table tuning is challenging but you shouldn't need to make the table significantly larger than some fraction of the total number of entries as long, as your hash function is effective. The problem here is that listeners are differentiated by both destination IP and port but the hash table only uses the port and then does a linear lookup by IP. As was demonstrated the hash function is not always effective and the list of listeners in a bucket can get quite long. Presumably the existing scheme was chosen because it is simple and makes it really easy to handle 0.0.0.0 listeners.

Using a binary tree at each bucket could also work well but you would have to rebalance the tree periodically if listeners were inserted in sorted order. A self balancing tree could be used instead but then again this adds complexity.