MySQL Bugs: #113819: when use show engine innodb cannot show correct information

Bug #113819	when use show engine innodb cannot show correct information
Submitted:	31 Jan 7:20	Modified:	9 Feb 19:57
Reporter:	xincheng xie	Email Updates:
Status:	Closed	Impact on me:	None
Category:	MySQL Server: InnoDB storage engine	Severity:	S3 (Non-critical)
Version:	8.0.34, 8.0.33	OS:	Linux (CentOS Linux release 7.6.1810 (Core) )
Assigned to:		CPU Architecture:	Any
Tags:	show engine innodb status

Description:
HI ，
After i upgrade  mysqld from 5.7.26 to 8.0.34 ,when i use then statement "show engine innodb status " ,the module  FILE I/O is not correct:
--------
FILE I/O
--------
I/O thread 0 state: waiting for completed aio requests ((null))
I/O thread 1 state: waiting for completed aio requests (insert buffer thread)
I/O thread 2 state: waiting for completed aio requests (read thread)
I/O thread 3 state: waiting for completed aio requests (read thread)
I/O thread 4 state: waiting for completed aio requests (read thread)
I/O thread 5 state: waiting for completed aio requests (read thread)
I/O thread 6 state: waiting for completed aio requests (write thread)
I/O thread 7 state: waiting for completed aio requests (write thread)
I/O thread 8 state: waiting for completed aio requests (write thread)

the thread 0 is null ！and the variable innodb_write_io_threads is 4,
so this module is not  displaying correctly

How to repeat:
just show engine innodb status

when the mysqld is 5.7.26 ,it display correctly

Hello xincheng xie,

Thank you for the report and feedback.

regards,
Umesh

# I'm not sure this is intended but this behavior(unusual) seen only since 8.0.33+ and prior to that it was fine

 bin/mysql -uroot -S /tmp/mysql.sock
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 7
Server version: 8.0.33 MySQL Community Server - GPL

Copyright (c) 2000, 2023, Oracle and/or its affiliates.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> show engine innodb status\G
*************************** 1. row ***************************
.
--------
FILE I/O
--------
I/O thread 0 state: waiting for completed aio requests ((null))

## 8.0.11-8.0.32 i.e. < 8.0.33 version(s)

 bin/mysql -uroot -S /tmp/mysql.sock
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 7
Server version: 8.0.32 MySQL Community Server - GPL

Copyright (c) 2000, 2023, Oracle and/or its affiliates.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> show engine innodb status\G
*************************** 1. row ***************************
.
--------
FILE I/O
--------
I/O thread 0 state: waiting for completed aio requests (insert buffer thread)

Thank you Xincheng,
This issue is known to us, it was introduced in 8.0.33 by some bugfix.
It will be fixed in 8.0.37 release.

Fixed as of the upcoming MySQL Server 8.0.37 release, and here's the proposed changelog entry from the documentation team:

Results for SHOW ENGINE INNODB STATUS showed an invalid value (NULL) as
the first result.

Thank you for the bug report.