Arenas are just one tool amongst many; I am not talking about some specific magic tool, but about software architecture itself.

Please read this other reply I made in the same thread: https://news.ycombinator.com/item?id=26938577

EDIT: And about data sharing (with logging, etc.), that's part of the data pipeline too. So yes, your aggregation mechanism will take it into account. These are not two separate problems, irritatingly coupled due to reality; these are two parts of the same problem.