In previous versions of Riak the same process gathered metrics and calculated statistics. In certain situations, under load, reading statistics would slow down, or even timeout altogether. The call to read stats would block that same process that updates stats, leading to large message queue backlogs.
This is the sort of observation and improvement that only a product that got into production (heavy production) could make.
Original title and link: Riak Metrics With Folsom ( ©myNoSQL)