After a routine update yesterday,I felt my laptop became to be very heat,then I checked the CPU usage and saw  the CPU usage was up to 100%. I ever got same problem before but if I rebooted the computer all will turn to be ok ,however this method didn’t work this time.Then I checked the processes and found the Tracker ’s process ate over 50% CPU usage,this is the reason.I had to shut off the tracker from Sessions,after that,the CPU works fine again.