[jira] [Commented] (ZOOKEEPER-1413) Use on-disk transaction log for learner sync up

["Hadoop QA (Commented) (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/ZOOKEEPER-1413?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13234573#comment-13234573 ] 

Hadoop QA commented on ZOOKEEPER-1413:
--------------------------------------

-1 overall.  Here are the results of testing the latest attachment 
  http://issues.apache.org/jira/secure/attachment/12519268/ZOOKEEPER-1413.patch
  against trunk revision 1302736.

    +1 @author.  The patch does not contain any @author tags.

    +1 tests included.  The patch appears to include 8 new or modified tests.

    -1 patch.  The patch command could not apply the patch.

Console output: https://builds.apache.org/job/PreCommit-ZOOKEEPER-Build/1004//console

This message is automatically generated.
                
> Use on-disk transaction log for learner sync up
> -----------------------------------------------
>
>                 Key: ZOOKEEPER-1413
>                 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-1413
>             Project: ZooKeeper
>          Issue Type: Improvement
>          Components: server
>    Affects Versions: 3.4.3
>            Reporter: Thawan Kooburat
>            Priority: Minor
>              Labels: performance
>             Fix For: 3.4.3
>
>         Attachments: ZOOKEEPER-1413.patch
>
>
> Motivation:
> The learner syncs up with leader by retrieving committed log from the leader. Currently, the leader only keeps 500 entries of recently committed log in memory. If the learner falls behind more than 500 updates, the leader will send the entire snapshot to the learner. 
> With the size of the snapshot for some of our Zookeeper deployments (~10G), it is prohibitively expensive to send the entire snapshot over network. Additionally, our Zookeeper may serve more than 4K updates per seconds. As a result, a network hiccups for less than a second will cause the learner to use snapshot transfer.
> Design:
> Instead of looking only at committed log in memory, the leader will also look at transaction log on disk. The amount of transaction log kept on disk is configurable and the current default is 100k. This will allow Zookeeper to tolerate longer temporal network failure before initiating the snapshot transfer.  
> Implementation:
> We plan to add interface to the persistence layer will can be use to retrieve proposals from on-disk transaction log. These proposals can then be used to send to the learner using existing protocol. 

--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa
For more information on JIRA, see: http://www.atlassian.com/software/jira