"last message repeated 4 times" while starting searchd

If we start searchd, this is shown:


precaching index ‘x’
precaching index ‘y’
precaching index ‘z’
last message repeated 4 times
Index header format is not json, will try it as binary…

What does “last message repeated 4 times” mean?

that means that last visible message was duplicated 4 times, seems precaching index ‘z’ was dumped multiple times in a row into the log

But why would he do that?