MySQL Bugs: #49047: InnoDB deadlock detection is CPU intensive with many locks on a single row

Bug #49047	InnoDB deadlock detection is CPU intensive with many locks on a single row
Submitted:	24 Nov 2009 17:55	Modified:	6 Oct 2010 18:11
Reporter:	Harrison Fisk	Email Updates:
Status:	Closed	Impact on me:	None
Category:	MySQL Server: InnoDB storage engine	Severity:	S5 (Performance)
Version:	5.0,5.1,plugin	OS:	Any
Assigned to:	John Russell	CPU Architecture:	Any
Tags:	deadlock, innodb

File:	Maximum allowed size is 50MB.
Description:
Privacy:

If the data you need to attach is more than 50MB, you should create a compressed archive of the data, split it to 50MB chunks, and upload each of them as a separate attachment.

To split a large file:

On *nix platforms use the split command e.g. split -b 50MB <my_large_archive> <my_split_archive_prefix>
On windows use WinZip or a similar utility to split the large file

Dtrace script which counts the number of queries being done and the calls to lock_rec_get_prev

Attachment: count_deadlock_walks.d (text/x-dsrc), 566 bytes.

Small patch to switch from using lock_rec_read_prev to lock_rec_read_next

Attachment: deadlock_test.diff (text/x-patch), 981 bytes.

Corrected patch to switch from using lock_rec_read_prev to lock_rec_read_next

Attachment: deadlock_cpu_v2.diff (text/x-patch), 1.88 KiB.