High memory usage on mysql slave server

[Santosh Bhabal]

Hello Experts,

We have Master - Slave setup of MySQL 5.6.37 version.
On Slave server, memory usage is always showing high which is almost 98-99%.
This slave server is a virtual machine on VMware esxi host.
Slave server is having 16GB of memory allocated.

Below is the my.cnf :

[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
tmpdir = /var/lib/mysqltemp
read-only = 1
# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0
max_connections = 1000
server_id = 3
#
query_cache_size = 0
innodb_buffer_pool_size = 73G
innodb_log_file_size = 9G
innodb_buffer_pool_instances = 64
innodb_log_buffer_size = 8M
ignore-db-dir=lost+found

[mysqld_safe]
log-error=/usr/binlogs/aws_mysql_slave-mysqld.log
pid-file=/var/run/mysqld/mysqld.pid
socket=/var/lib/mysql/mysql.sock
#

[mysql]
socket=/var/lib/mysql/mysql.sock
####

Please help me to troubleshoot this issue.