MySQL Bugs: #108695: mysql memory utilization is high

Bug #108695	mysql memory utilization is high
Submitted:	5 Oct 2022 19:49	Modified:	6 Oct 2022 16:14
Reporter:	lokesh singhal	Email Updates:
Status:	Not a Bug	Impact on me:	None
Category:	MySQL Server	Severity:	S3 (Non-critical)
Version:	8.0.25	OS:	Ubuntu (18)
Assigned to:		CPU Architecture:	ARM
Tags:	mysql memory issue

Description:
I have below server configuration
vcpu = 6 cores 
RAM  = 64GB 
disk = 200GB 

my.cnf configuration:

max_connections=1000 
innodb_buffer_pool_size=40G
innodb_log_file_size=2G
interative_time_out=300
wait_time_out=300

Rest all parameter is default.

Now it shows MySQL memory utilization is 84% of physical RAM.
CPU utilization is normal.

What is the issue here?

How to repeat:
On restart goes to normal after 1 month is shows again same.

Hi Mr. singhal,

Thank you for your bug report.

However, it is not a bug.

We have received hundreds of reports like this and always discovered that a problem is not in any program, including MySQL.

Problem is in malloc library that is used on Linux, as well as on many other operating system.

Simply, when a process allocates lot's of memory, the memory that is freed by MySQL server remains attached to the server, by the OS malloc library.  That is a why for reducing the frequency with which  that OS system call has to be made. 

There is a way to free even that memory, but that requires to write a complex C program (only for your system), that would reduce the RAM attached to the MySQL server. However, that program would slow down future malloc's considerably !!!!

Not a bug.

Can you suggest me next step here to release memory Do I need to restart MySQL service or any other way?

Hi,

I warn you again that this will slow down MySQL server.

You have to see how much virtual memory you have free. Add as much as you want to free. Write a C program that will calloc() that amount of memory and then let it free() that amount ....