select() API should have been deprecated years ago. While unsafe operations like
gets(), and so forth all provide compile-time deprecation warnings,
select() is also incredibly dangerous and has a more modern, safer replacement (
poll()), but yet people continue to use it.
The problem is that it doesn’t scale. In this case, “not scaling” doesn’t just mean it’s bad for performance, “not scaling” means it can destroy your call stack, crash your process, and leave it in a state that is incredibly difficult to debug.