When the system clock jumps backwards SimpleTimestamper hangs in a "endless" loop and eats CPU time till the clock has reached at least the the time when the clock jumped backwards.

Just run this

import java.util.Date;

import org.hibernate.cache.spi.support.SimpleTimestamper;

public class TimstamperTest {
	public static void main(String... args) {	
		while (true) {			
			System.out.println(new Date() + "   " + SimpleTimestamper.next());
			try	{
				Thread.sleep(100);
			}
			catch (InterruptedException e) {
				e.printStackTrace();
			}
		}
	}
}

And then set the system clock to one day in the past. It will stop and instead just loop till you adjust the clock back again.

Not a big deal if you have NTP and the clock varies just a few milliseconds before it is adjusted again. But if there is a bigger change for whatever reason this will crash your system.