There's a big issue with the unordered_map.erase(const_iterator) method -- STL mandates that .erase() returns an iterator to the next item in the container. There's no simple implementation of that for hashtables other than to walk the hashtable, which is quite slow.
There's a big issue with the unordered_map.erase(const_iterator) method -- STL mandates that .erase() returns an iterator to the next item in the container. There's no simple implementation of that for hashtables other than to walk the hashtable, which is quite slow.
This was once a serious performance issue with unordered_map (discussion here: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=41975). I haven't followed up in years, but is the issue?