## Bug Report <!-- Please answer these questions before submitting your issue. Thanks! --> ### What did you do? When there is some reason which causes some leader transfer operations, the cache entry number increases so much.  <img width="922" alt="Screen Shot 2021-12-20 at 4 48 04 PM" src="https://user-images.githubusercontent.com/35896542/146743789-0e9190d8-050d-40f7-a6e0-3d9d23868687.png"> ### What version of PD are you using (`pd-server -V`)? master