hbase-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Lars Hofhansl (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HBASE-9158) Serious bug in cyclic replication
Date Thu, 08 Aug 2013 21:18:51 GMT

     [ https://issues.apache.org/jira/browse/HBASE-9158?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Lars Hofhansl updated HBASE-9158:
---------------------------------

    Attachment: 9158-trunk-v4.txt

Just adds a tests.
I just used the setup TestMasterReplication#testCyclicReplication.
There we three cluster 1,2,and 3 in a cycle.
What I do is this:
# disable peer 3 on 2
# Put a row1 into 1, wait until that replicates to 2
# Put a row2 into 2. So now we have the edit edit 1 and the edit 2 in the WAL, in that order
# reenable peer 3 on 2
# without the fix the row2 would be replicated back to 1, because on the way from 2 to 3 it
would be retagged with 1's cluster id.

(takes more writing to explain the test than writing the actual test)
                
> Serious bug in cyclic replication
> ---------------------------------
>
>                 Key: HBASE-9158
>                 URL: https://issues.apache.org/jira/browse/HBASE-9158
>             Project: HBase
>          Issue Type: Bug
>    Affects Versions: 0.98.0, 0.95.1, 0.94.10
>            Reporter: Lars Hofhansl
>            Assignee: Lars Hofhansl
>            Priority: Critical
>             Fix For: 0.98.0, 0.95.2, 0.94.11
>
>         Attachments: 9158-0.94.txt, 9158-0.94-v2.txt, 9158-0.94-v3.txt, 9158-0.94-v4.txt,
9158-trunk-v1.txt, 9158-trunk-v2.txt, 9158-trunk-v3.txt, 9158-trunk-v4.txt
>
>
> While studying the code for HBASE-7709, I found a serious bug in the current cyclic replication
code. The problem is here in HRegion.doMiniBatchMutation:
> {code}
>       Mutation first = batchOp.operations[firstIndex].getFirst();
>       txid = this.log.appendNoSync(regionInfo, this.htableDescriptor.getName(),
>                walEdit, first.getClusterId(), now, this.htableDescriptor);
> {code}
> Now note that edits replicated from remote cluster and local edits might interleave in
the WAL, we might also receive edit from multiple remote clusters. Hence that <walEdit>
might have edits from many clusters in it, but all are just labeled with the clusterId of
the first Mutation.
> Fixing this in doMiniBatchMutation seems tricky to do efficiently (imagine we get a batch
with cluster1, cluster2, cluster1, cluster2, ..., in that case each edit would have to be
its own batch). The coprocessor handling would also be difficult.
> The other option is create batches of Puts grouped by the cluster id in ReplicationSink.replicateEntries(...),
this is not as general, but equally correct. This is the approach I would favor.
> Lastly this is very hard to verify in a unittest.

--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators
For more information on JIRA, see: http://www.atlassian.com/software/jira

Mime
View raw message