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https://issues.apache.org/jira/browse/CASSANDRA-2388?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13094658#comment-13094658
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Mck SembWever edited comment on CASSANDRA-2388 at 9/1/11 6:39 AM:
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see last comment. (say if this should be a separate bug...)
Maybe hadoop's task allocation isn't working properly because i've an
unbalanced ring (i'm working in parallel to fix that).
If this is the case i think it's an unfortunate limitation (the ring must be
balanced to get any decent hadoop performance).
It's also probably likely when using {{ConfigHelper.setInputRange(..)}} that
the number of nodes involved is small (approaching RF).
With the default hadoop scheduler your hadoop cluster is occupied while just a
few taskTrackers are busy. Of course switching to FairScheduler will help some
here.
I'll take a look into hadoop's task allocation code as well...
was (Author: michaelsembwever):
see last comment. (say if this should be a separate bug...)
> ColumnFamilyRecordReader fails for a given split because a host is down, even
> if records could reasonably be read from other replica.
> -------------------------------------------------------------------------------------------------------------------------------------
>
> Key: CASSANDRA-2388
> URL: https://issues.apache.org/jira/browse/CASSANDRA-2388
> Project: Cassandra
> Issue Type: Bug
> Components: Hadoop
> Affects Versions: 0.6
> Reporter: Eldon Stegall
> Assignee: Mck SembWever
> Labels: hadoop, inputformat
> Fix For: 0.7.9, 0.8.5
>
> Attachments: 0002_On_TException_try_next_split.patch,
> CASSANDRA-2388-addition1.patch, CASSANDRA-2388-extended.patch,
> CASSANDRA-2388.patch, CASSANDRA-2388.patch, CASSANDRA-2388.patch,
> CASSANDRA-2388.patch
>
>
> ColumnFamilyRecordReader only tries the first location for a given split. We
> should try multiple locations for a given split.
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