MySQL Bugs: #117929: MySQL - 8.0.41 consuming more CPU

Bug #117929	MySQL - 8.0.41 consuming more CPU
Submitted:	10 Apr 6:54	Modified:	12 May 11:19
Reporter:	Arun Kumar Venugopal	Email Updates:
Status:	Can't repeat	Impact on me:	None
Category:	MySQL Server	Severity:	S1 (Critical)
Version:	8.0.41	OS:	Ubuntu (Ubuntu - 22.04)
Assigned to:	MySQL Verification Team	CPU Architecture:	ARM (Azure VM)

Description:
We have been experiencing sudden spikes in the CPU utilization and also consistently high usage of CPU by mysql process.

Upon checking there are no queries that are in the pending state instead all of them are normal queries which are executed by the application.

Note: The size of the DB is around 200 gb

How to repeat:
- Install mysql 8.0.41 in ubuntu server version 22.04 with 8 core 32 GB machines.
- Innodb_buffer_pool_Size= 12gb

Execute 50 queries simultaneously to check whether the mysql consumes more CPU consistently.

Suggested fix:
Any kind of limitations to set values for cpu core and use accordingly without overloading.

CPU Usage increase post update

Attachment: Screenshot from 2025-04-10 10-03-29.png (image/png, text), 88.45 KiB.

I want to add to this bug that we to have experienced this issue. In the above graph you can see the CPU usage of running multiple heavy analytical queries on mysql 8.0.39 versus running the exact same queries on mysql 8.0.41 

We use Debian Bookworm. 

This has been seen across most of our Mysql servers. 

After weeks of comparing monitoring data we could not pinpoint a metric that has caused this. Metrics that have changed are mostly due to the CPU being at 100% for prolonged time. 

It might be a red herring, but the only server where we don't have this issue, is a server that got updated from 8.0.40 to 8.0.41 (instead of 8.0.39 directly to 8.0.41)

I cannot reproduce this.  Can you please check that you are not affected by the EXT4 bug.

http://dimitrik.free.fr/blog/posts/mysql-80-perf-xfs-vs-ext4.html

Thanks