Well I tried many stuff. Finally tried are these steps
1 apt-get update
2 apt-get install -y libjemalloc-dev
3 in /etc/systemd/system/mariadb.service.d/ edit any .conf in this directory by adding information at the end-line. LD_PRELOAD=/usr/lib/x86_64-linux-gnu/libjemalloc.so.1
4 run systemctl daemon-reload
5 run sudo systemctl restart mysql.service
6 run sudo reboot
I have found some respite on a demo server. Will be testing on production server.