High memory usage
xmrig-proxy 6.4.0 running on Ubuntu Server 18.04

consumed more and more memory everyday and need to reboot every 15 day, else server will hang because no more free memory.

 
![image](https://user-images.githubusercontent.com/67159997/99323768-76a26080-28a5-11eb-976f-e920bd461a7d.png)


