I was going to say that there are currently no concurrent readers because `renderView()` can currently only run once, but then I noticed that the `memoryToDiskFlusher`'s `ForEachSample()` is of course also a reader which needs to be protected. Also, we could possibly allow concurrent `renderView()`s if we make the `memoryDeleteMutex` an RW-lock too. Let me go back to the drawing board...