Is there something I can add to a map function (map/reduce) so I can log / print how many times the function has run during one execution?

yes write to the context object and the read it in the summary phase using summary.output.iterator().each function for example. I am not the best at MR summarize phase so might be a better way 🙂 but that should be able to get u data from map or reduce to summary phase 🙂 and to something with it there.