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https://issues.apache.org/jira/browse/HBASE-5757?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jonathan Hsieh reassigned HBASE-5757:
-------------------------------------
Assignee: Jan Lukavsky
> TableInputFormat should handle as many errors as possible
> ---------------------------------------------------------
>
> Key: HBASE-5757
> URL: https://issues.apache.org/jira/browse/HBASE-5757
> Project: HBase
> Issue Type: Bug
> Components: mapred, mapreduce
> Affects Versions: 0.90.6
> Reporter: Jan Lukavsky
> Assignee: Jan Lukavsky
> Attachments: 5757-trunk-v2.txt, HBASE-5757-trunk-r1341041.patch,
> HBASE-5757.patch, HBASE-5757.patch
>
>
> Prior to HBASE-4196 there was different handling of IOExceptions thrown from
> scanner in mapred and mapreduce API. The patch to HBASE-4196 unified this
> handling so that if exception is caught a reconnect is attempted (without
> bothering the mapred client). After that, HBASE-4269 changed this behavior
> back, but in both mapred and mapreduce APIs. The question is, is there any
> reason not to handle all errors that the input format can handle? In other
> words, why not try to reissue the request after *any* IOException? I see the
> following disadvantages of current approach
> * the client may see exceptions like LeaseException and
> ScannerTimeoutException if he fails to process all fetched data in timeout
> * to avoid ScannerTimeoutException the client must raise
> hbase.regionserver.lease.period
> * timeouts for tasks is aready configured in mapred.task.timeout, so this
> seems to me a bit redundant, because typically one needs to update both these
> parameters
> * I don't see any possibility to get rid of LeaseException (this is
> configured on server side)
> I think all of these issues would be gone, if the DoNotRetryIOException would
> not be rethrown. -On the other hand, handling errors in InputFormat has
> disadvantage, that it may hide from the user some inefficiency. Eg. if I have
> very big scanner.caching, and I manage to process only a few rows in timeout,
> I will end up with single row being fetched many times (and will not be
> explicitly notified about this). Could we solve this problem by adding some
> counter to the InputFormat?-
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