MySQL Bugs: #75995: mysqld --help --verbose tries to lock files

Bug #75995	mysqld --help --verbose tries to lock files
Submitted:	22 Feb 2015 11:01	Modified:	2 Jul 2015 16:20
Reporter:	Daniël van Eeden (OCA)	Email Updates:
Status:	Closed	Impact on me:	None
Category:	MySQL Server: DML	Severity:	S2 (Serious)
Version:	5.7.6-m16	OS:	Any
Assigned to:		CPU Architecture:	Any

Description:
mysqld tries to lock ibdata1 when running "mysqld --help --verbose"

How to repeat:
This only happens when the server is running.

./mysqld --help --verbose
2015-02-22T10:51:49.838900Z 0 [ERROR] InnoDB: Unable to lock ./ibdata1, error: 11
2015-02-22T10:51:50.839127Z 0 [ERROR] InnoDB: Unable to lock ./ibdata1, error: 11
* many more lines with the same error *
2015-02-22T10:53:28.861858Z 0 [ERROR] InnoDB: Unable to lock ./ibdata1, error: 11
2015-02-22T10:53:29.862030Z 0 [ERROR] InnoDB: Unable to lock ./ibdata1, error: 11
2015-02-22T10:53:29.862107Z 0 [ERROR] InnoDB: Operating system error number 11 in a file operation.
2015-02-22T10:53:29.862150Z 0 [ERROR] InnoDB: Error number 11 means 'Resource temporarily unavailable'.
2015-02-22T10:53:29.862173Z 0 [ERROR] InnoDB: Cannot open datafile './ibdata1'
2015-02-22T10:53:29.862195Z 0 [ERROR] InnoDB: Could not open or create the system tablespace. If you tried to add new data files to the system tablespace, and it failed here, you should now edit innodb_data_file_path in my.cnf back to what it was, and remove the new ibdata files InnoDB created in this failed attempt. InnoDB only wrote those files full of zeros, but did not yet use them in any way. But be careful: do not remove old data files which contain your precious data!
2015-02-22T10:53:30.462894Z 0 [ERROR] Plugin 'InnoDB' init function returned error.
2015-02-22T10:53:30.462951Z 0 [ERROR] Plugin 'InnoDB' registration as a STORAGE ENGINE failed.
2015-02-22T10:53:30.462976Z 0 [ERROR] Failed to initialize plugins.
* regular --help --verbose output *
Plugins have parameters that are not reflected in this list
because execution stopped before plugins were initialized.

To see what values a running MySQL server is using, type
'mysqladmin variables' instead of 'mysqld --verbose --help'.
2015-02-22T10:53:30.481309Z 0 [ERROR] Aborting

Suggested fix:
Don't lock anything when running '--help'

Related:

Bug #30025 	Mysqld prints out warnings/errors being run with --no-defaults --help
Bug #31106 	errors whenn running "mysqld --help" before "mysql_install_db"
Bug #62752 	mysqld --verbose --help ends with error
Bug #71599 	Unexpected log output for mysqld --help --verbose

This can be a server issue or an InnoDB issue.

Thank you for the bug report.

Posted by developer:
 
In the work to move system tables from MyISAM to InnoDB, information about plugins now have to be looked up in an InnoDB table. The way --help --verbose is implemented, is not optimal wrt to performance, but will require quite a major effort to improve. Short term, at least, we do not plan to fix this.

Noted in 5.7.8, 5.8.0 changelogs.

mysqld --help --verbose tried to perform actions that have nothing to
do with displaying a help message: Locking files, initializing system
files, and checking for a plugin table.