Memory does not reduce after too many write request and creating snapshot.

[JackyWoo]

RaftKeeper version

v2.1.0

Description

Memory does not reduce after too many write request and creating snapshot.

How to reproduce

1. Send 10m create request and delete them
2. you will see the memory usage is high
3. create snapshot by echo csnp | nc your_node
4. you will see the memory usage not reduce
5. When you restart the node, memory usage will reduce