`std::map` has very slow access are requires lock on every access. We can use `std::array` instead to hold compile time known number of buckets. This method should have less latency and memory overhead, as well as possibly no lock on access.

No need to lock mutex to update atomic values

Make sure atomic values are zero initialized.

As in description

`fetch_add` returns old value, therefore we need to increment current memory usage value before storing current max.