MySQL Bugs: #5436: SHOW INNODB STATUS is unusable with a lot of concurrent connections

Bug #5436	SHOW INNODB STATUS is unusable with a lot of concurrent connections
Submitted:	6 Sep 2004 19:10	Modified:	6 May 2005 8:58
Reporter:	Peter Zaitsev (Basic Quality Contributor)	Email Updates:
Status:	Closed	Impact on me:	None
Category:	MySQL Server: InnoDB storage engine	Severity:	S3 (Non-critical)
Version:	all	OS:	Any (all)
Assigned to:	Marko Mäkelä	CPU Architecture:	Any

Description:
SHOW INNODB STAUS is basically unsuable if a lot of concurrent connections are running
as it cuts it output  in the middle of the connections listing, so valuable data about performance
buffer pool usage etc is not shown. 

Among other things this does not allow support teams to diagnose performance problems efficiently in such cases. 

How to repeat:
Run some test (ie SysBench) with 1000+ threads and run  SHOW INNODB STATUS at the same time

Suggested fix:
Perhaps "processlist" should be skipped after some number of rows to allow enough space for 
all other data to be printed.

In general I think it would be better to have it removed from SHOW INNODB STATUS at all
and have  "SHOW INNODB TRANSACTIONS" or whatever to show  currently active transactions
in multiple rows result set. This will allow to see all of them  for any number of connections.

Marko,

how about scanning the string and truncating the START of the transaction list if the string does not fit in 64 kB? The oldest and the most interesting transactions are the last in the list.

Regards,

Heikki

A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/internals/24140

Thank you for your bug report. This issue has been committed to our
source repository of that product and will be incorporated into the
next release.

If necessary, you can access the source repository and build the latest
available version, including the bugfix, yourself. More information 
about accessing the source trees is available at
    http://www.mysql.com/doc/en/Installing_source_tree.html

Additional info:

The bug will be fixed in MySQL 4.1.12.