MySQL Bugs: #91455: Implement core dump size reduction.

Bug #91455	Implement core dump size reduction.
Submitted:	28 Jun 2018 8:34	Modified:	29 Jun 2018 4:52
Reporter:	Jean-François Gagné	Email Updates:
Status:	Duplicate	Impact on me:	None
Category:	MySQL Server	Severity:	S4 (Feature request)
Version:		OS:	Linux
Assigned to:		CPU Architecture:	Any

Description:
Hi,

as described in a blog post which I will put the link in comments (this bug is opened before publishing the post as I am linking to this in the post), the core dump sizes are inflated by many buffers that are not necessary needed for understanding the reason of a crash.  Excluding those buffer using the MADV_DONTDUMP flag of the madvise system call (available since Linux 3.4) would make working with core dumps much easier.  Some non-exhaustive list of such buffer is:

-InnoDB Buffer Pool
-InnoDB Redo Log buffer
-MyISAM KEY_CACHE

The benefit would be the following:

-need less disk space to store core dumps,
-reduce the time required to write core dumps (and hence restart MySQL after a crash),
-make it easier to share core dump with support because it is smaller (uploading a 192 GB file in a support ticket is problematic)
-improve security by omitting substantial amount of user data from core dumps.

Please consider implementing core dump size reduction by excluding large buffers from core dump.

Many thanks,

JFG

How to repeat:
Generate a core dump on a MySQL instance with a 64GB+ InnoDB Buffer Pool.

Suggested fix:
Please consider implementing core dump size reduction by excluding large buffers from core dump.

The blog post I am referring to in the description is the following:
https://www.percona.com/community-blog/2018/06/28/nice-feature-in-mariadb-103-no-innodb-bu...

Duplicate of bug 66826?

Hello Jean,

Thank you for the reasonable feature request.
As Laurynas pointed, this is duplicate of Bug #66826.

Regards,
Umesh