Bug #59116 Freeing items never completes even w/o Query Cache and Adaptive Hash Index
Submitted: 22 Dec 2010 20:36 Modified: 23 Dec 2010 21:19
Reporter: Harrison Keating Email Updates:
Status: Not a Bug Impact on me:
None 
Category:MySQL Server: Replication Severity:S3 (Non-critical)
Version:5.1.52-log OS:Linux (Fedora Core 14)
Assigned to: CPU Architecture:Any

[22 Dec 2010 20:36] Harrison Keating
Description:
3 box replication ring, A->B->C->A,  has been operating for several months without issue.  Just recently upgraded to 5.1.52 and the replication has started to slow to trickle on box C.  Boxes are not under heavy use.

It appears the "freeing items" never seems to complete, however replication is not stopped, simply delayed by hours and hours.

 6 | system user |                 | NULL | Connect     | 40292 | freeing items                                                  | NULL   

The processlist is empty but for that line,  "Waiting for master to send event" and "Has sent all binlog to slave; waiting for binlog to be updated"

I searched through the bug list and saw the same problem was resolved by others by disabling query cache and adaptive hash index for innodb, however we executed those changes, restarted the server and the problem persists. 

 innodb_adaptive_hash_index              | OFF   
 query_cache_size                        | 0 

How to repeat:
Box C is running 64bit Fedora Core 14, 64 bit mysql installed via yum.  I've never had this happen before so can not explain how to repeat.

Box A and B are running 32bit mysql 5.0.18-standard-log
[23 Dec 2010 21:19] Sveta Smirnova
Thank you for taking the time to write to us, but this is not a bug. Please double-check the documentation available at http://dev.mysql.com/doc/ and the instructions on
how to report a bug at http://bugs.mysql.com/how-to-report.php

You wrote:

---<q>----
A->B->C->A
...
Box C is running 64bit Fedora Core 14, 64 bit mysql installed via yum.  I've never had
this happen before so can not explain how to repeat.

Box A and B are running 32bit mysql 5.0.18-standard-log
----</q>----

So C of version 5.1.52 is master for A of version 5.0.18. This is not supported configuration. In circular replication all servers should be of same version.