Bukkit

If you are on 1.0.8, please update asap

I did a mistake in the 1.0.8-beta release that resulted in heavy console spam, in extreme cases it could even crash the server.
Make sure to update to 1.0.9 as soon as you can (especially if you're using custom spawn rates or natural shulker spawning) and check your log files, they could be very large.