accumulo-notifications mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Josh Elser (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (ACCUMULO-3249) New replication status message created for file that was already replicated
Date Tue, 21 Oct 2014 21:09:34 GMT

    [ https://issues.apache.org/jira/browse/ACCUMULO-3249?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14179104#comment-14179104
] 

Josh Elser commented on ACCUMULO-3249:
--------------------------------------

Ah, so the file didn't get re-queued into the system because it lacked a create time (a symptom
of how the record was created in the first place by the {{DatafileManager}}). Because it had
no create time, and thus no order record in the replication table, the WorkAssigner didn't
know about it WRT assigning work out (despite this implementation not caring about the ordering
of all WALs to replicate).

Need to figure out what the case was that the replication update is written inside of {{DatafileManager}}
and figure out what the correct way to ensure WAL state changes are not lost is.

> New replication status message created for file that was already replicated
> ---------------------------------------------------------------------------
>
>                 Key: ACCUMULO-3249
>                 URL: https://issues.apache.org/jira/browse/ACCUMULO-3249
>             Project: Accumulo
>          Issue Type: Bug
>          Components: replication
>            Reporter: Josh Elser
>            Assignee: Josh Elser
>            Priority: Critical
>             Fix For: 1.7.0
>
>
> Noticed a failure in UnorderedWorkAssignerReplicationIT.dataWasReplicatedToThePeerWithoutDrain
where the test timed out because a file never got replicated that we expected to.
> Digging into it:
> * File was queued for replication before the original tserver died
> * New tserver picked up the file to be replicated before recovery fully completed
> * Tserver completed replication to the peer before recovery fully completed (recovery
for metadata/replication succeeded, but not for all tables)
> * Master cleaned up replication records because it saw that the tserver recorded that
replication was completed.
> * When recovery finally completed, it wrote an empty closed marker back into the metadata
table (which is a precaution to make sure that know when a WAL is no longer referenced).
> As such, we had a entry for a file that we thought needed replication but was already
replicated. That's issue #1.
> For some reason yet, this also caused the master to get into a state where it believe
we needed to replicate the WAL but couldn't assign the WAL for replication (I believe the
master thought it was already assigned for replication) and thus that file was stuck in a
"pending-replication" phase and didn't proceed. Eventually the test timed out and failed.



--
This message was sent by Atlassian JIRA
(v6.3.4#6332)

Mime
View raw message