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From "Jimmy Xiang (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-9514) Prevent region from assigning before log splitting is done
Date Mon, 16 Sep 2013 22:10:56 GMT

    [ https://issues.apache.org/jira/browse/HBASE-9514?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13768847#comment-13768847
] 

Jimmy Xiang commented on HBASE-9514:
------------------------------------

bq. Here you are adding back the random region move to try and bring on the issue again:
Yes, I'd like to see the data loss issue in HBASE-9338 is fixed.

bq. It could be configured zero? You saying try at least once?
It can't be 0. It is total max attempts instead of retries.  I added it just in case users
mis-configure it.

bq. I suppose + public Lock acquireLock(final String encodedName) { has to be public because
SSH wants to use it too?
That's right.

bq. I suppose it doesn't matter if in dead server for a long time since each server has a
startcode?
That's right. Each server has a startcode. The region will stay in lastAssignments till SSH
log split is done.

bq. Does this big block of new code have to go into the middle of assign? Can it be broken
up a little into methods that are easier to grok?
bq. The big change in the middle I cannot follow. Can we have a note on what it does?
In the middle, there is no change at all actually.  I just aligned the try-block.

bq. Is it a good idea inserting this wait here for every exception? What if the exception
is a NSRE? Doesn't NSRE indicate live server?
For NSRE, the region is offlined right away. To reduce the impact, I don't see a clear reason
to wait here for every exception. So I didn't add it.


                
> Prevent region from assigning before log splitting is done
> ----------------------------------------------------------
>
>                 Key: HBASE-9514
>                 URL: https://issues.apache.org/jira/browse/HBASE-9514
>             Project: HBase
>          Issue Type: Bug
>          Components: Region Assignment
>            Reporter: Jimmy Xiang
>            Assignee: Jimmy Xiang
>            Priority: Blocker
>         Attachments: trunk-9514_v1.patch
>
>
> If a region is assigned before log splitting is done by the server shutdown handler,
the edits belonging to this region in the hlogs of the dead server will be lost.
> Generally this is not an issue if users don't assign/unassign a region from hbase shell
or via hbase admin. These commands are marked for experts only in the hbase shell help too.
 However, chaos monkey doesn't care.
> If we can prevent from assigning such regions in a bad time, it would make things a little
safer.

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