MySQL Bugs: #109598: Set of innodb_buffer_pool_in_core_file=0 in my.cnf doesn't take effect

Bug #109598	Set of innodb_buffer_pool_in_core_file=0 in my.cnf doesn't take effect
Submitted:	12 Jan 2023 7:54	Modified:	12 Jan 2023 14:45
Reporter:	jie xu	Email Updates:
Status:	Not a Bug	Impact on me:	None
Category:	MySQL Server	Severity:	S3 (Non-critical)
Version:	8.0	OS:	Any
Assigned to:		CPU Architecture:	Any
Tags:	innodb_buffer_pool_in_core_file

Description:
Set of innodb_buffer_pool_in_core_file=0 in my.cnf doesn't take effect.
Because the buf_pool_should_madvise only update when innodb_buffer_pool_in_core_file is changed.

How to repeat:
Set innodb_buffer_pool_in_core_file=0 in my.cnf and start MySQL.
when MySQL is crash, core file still dump buffer pool.

Suggested fix:
Call buf_pool_update_madvise() after buffer pool init.

Hi jie xu,

Whether the system variable `core_file` is set at server startup using options on the command line or in an option file:

1. core_file=0 in my.cnf 
2. --core-file on the command line

Hi Mr. xu,

Thank you for your bug report.

However, what you describe is expected behaviour.

Disabling innodb_buffer_pool_in_core_file takes effect only if the core_file variable is enabled and the operating system supports the MADV_DONTDUMP non-POSIX extension to the madvise() system call.

That is how it works ....

This is all described in the chapter 15.8.3.7.

Not a bug.

Thank for you reply.

Of course i know how innodb_buffer_pool_in_core_file works.

I set the core_file variable, and my operating system supports the MADV_DONTDUMP non-POSIX extension to the madvise() system call.

I means if you set innodb_buffer_pool_in_core_file=0 in my.cnf and not on the command line, it wouldn't take effect.

you can try this.

Hi,

Try using OFF and if that does not work, try on the command line ......

Also, please try 8.0.31 and the OS that supports that call .....

Thank for you reply again...

My MySQL version is 8.0.13 and i check the MySQL 8.0.31 source code.
The buf_pool_update_madvise() still only called by innodb_srv_buffer_pool_in_core_file_update.

That means buf_pool_should_madvise only update when innodb_buffer_pool_in_core_file is changed.

And i set innodb_buffer_pool_in_core_file=OFF in my.cnf and start MySQL still doesn't work.
If i set innodb_buffer_pool_in_core_file=OFF on the command line; it works, the buffer pool doesn't dump into core file.

Hi ,

I have set my buffer pool to 2 Gb, turned core_file to ON and innodb_buffer_pool_in_core_file to OFF and crashed the server.

I got a core file that was smaller then 100 Mb.

Can't repeat.

Sorry, I check MySQL 8.0.13 source code again.

That update buf_pool_should_madvise in buf_pool_init().

That would works.

Thank you!!!

Not 8.0.13, 8.0.31 source code would be ok.

The 8.0.13 source code has this problem.

I try this on MySQL 8.0.31, that works.

Thank you!