Java chooses safety over performance. It is not free to check for concurrent access in a non-concurrent structure. In some languages, we let the programmer take

Java chooses safety over performance. It is not free to check for concurrent access in a non-concurrent structure. In some languages, we let the programmer take on the choice of which costs to bear. There is not very much that I like about Go, but there is nothing wrong with having non-concurrent data structures that are documented as such and fail in non-defined ways when there is shared data access.