[MDEV-7802] [PATCH] group commit status variable addition Created: 2015-03-19  Updated: 2015-04-29  Resolved: 2015-04-20

Status: Closed
Project: MariaDB Server
Component/s: Replication
Fix Version/s: 10.0.18, 10.1.5

Type: Task Priority: Minor
Reporter: Daniel Black Assignee: Kristian Nielsen
Resolution: Fixed Votes: 0
Labels: binlog, groupcommit, patch, replication

Issue Links:
Relates
relates to MDEV-7249 Performance problem in parallel repli... Closed

 Description   

currently we have a status variable for the total group_commits. This compromises of group commits due to binlog_commit_wait_count, binlog_commit_wait_usec or indeed conflicting transactions that need to be in a separate group.

Showing a breakdown as to the reason of the group commit will enable a more informed tuning of the system variables controlling the group commit and also identify how often these aren't taking part in the group determination.

patch: https://github.com/MariaDB/server/pull/30

 Comments   
Comment by Kristian Nielsen [ 2015-03-31 ]

See review comments on maria-developers@

Comment by Daniel Black [ 2015-04-03 ]

responded and corrected in github PR: https://lists.launchpad.net/maria-developers/msg08405.html

Comment by Kristian Nielsen [ 2015-04-17 ]

Thanks, Daniel.

The patch is ok. Though I will remove the test case in
rpl_parallel_multilevel2, I think. The 2-second timeout could trigger on
highly loaded test hosts, which looks like it will make the test case
fail. And I don't think the test adds anything really critical over what's
in binlog_commit_wait.test.

So I will push it into 10.1, however I need to first resolve a merge problem
that is blocking the push...

Comment by Daniel Black [ 2015-04-18 ]

The patch is ok. Though I will remove the test case in

rpl_parallel_multilevel2, I think. The 2-second timeout could trigger on
highly loaded test hosts, which looks like it will make the test case
fail. And I don't think the test adds anything really critical over what's
in binlog_commit_wait.test.

Ok - was my description on the multilevel for the reason between 1 and 3 groups right? I felt I was guessing a bit.

https://github.com/MariaDB/server/pull/30/files#diff-343103ed05549066b0de2beb82b16496R77

So I will push it into 10.1, however I need to first resolve a merge problem that is blocking the push...

to help that along...

https://github.com/MariaDB/server/pull/43 - single merge

https://github.com/MariaDB/server/pull/42 - entire 10.0 -> 10.1

Comment by Kristian Nielsen [ 2015-04-20 ]

Pushed to 10.1.5. Thanks, Daniel!

Comment by Daniel Black [ 2015-04-21 ]

Pushed to 10.1.5. Thanks, Daniel!

Welcome. Thanks for the merge.

Any chance of getting this into 10.0? seems like the most invasive bit is the extra brief lock on LOCK_prepare_ordered when when fetching status variables.

Comment by Daniel Black [ 2015-04-21 ]

I've added status variables to the KB.

Comment by Kristian Nielsen [ 2015-04-21 ]

> Any chance of getting this into 10.0? seems like the most invasive bit is
> the extra brief lock on LOCK_prepare_ordered when when fetching status
> variables.

Probably you should ask this on the maria-developers@ mailing list. I don't
personally have any strong opinion one way or the other.

The "normal" policy is to not introduce new features in stable releases.

Comment by Kristian Nielsen [ 2015-04-21 ]

> I've added status variables to the KB.

Thanks, Daniel, much appreciated.

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