[jira] Commented: (MAPREDUCE-15) SequenceFile RecordReader should skip bad records

["Dick King (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/MAPREDUCE-15?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12901479#action_12901479 ] 

Dick King commented on MAPREDUCE-15:
------------------------------------

Should the framework carry a {{mapreduce.max.corrupt.input.record.fraction}} and {{mapreduce.max.corrupt.input.record.excess}} ?

The framework catches and skips the corrupt records, and the bad and good record counts flow back to the job tracker as counters, and if the number of bad records ever exceeds, {{...fraction * number-of-good-records + ...excess}} the job is killed?

> SequenceFile RecordReader should skip bad records
> -------------------------------------------------
>
>                 Key: MAPREDUCE-15
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-15
>             Project: Hadoop Map/Reduce
>          Issue Type: Bug
>            Reporter: Joydeep Sen Sarma
>
> Currently a bad record in a sequencefile leads to entire job being failed. the best workaround is to skip an errant file manually (by looking at what map task failed).  This is a sucky option because it's manual and because one should be able to skip a sequencefile block (instead of entire file).
> While we don't see this often (and i don't know why this corruption happened) - here's an example stack:
> Status : FAILED java.lang.NegativeArraySizeException
> 	at org.apache.hadoop.io.BytesWritable.setCapacity(BytesWritable.java:96)
> 	at org.apache.hadoop.io.BytesWritable.setSize(BytesWritable.java:75)
> 	at org.apache.hadoop.io.BytesWritable.readFields(BytesWritable.java:130)
> 	at org.apache.hadoop.io.SequenceFile$Reader.getCurrentValue(SequenceFile.java:1640)
> 	at org.apache.hadoop.io.SequenceFile$Reader.next(SequenceFile.java:1712)
> 	at org.apache.hadoop.mapred.SequenceFileRecordReader.next(SequenceFileRecordReader.java:79)
> 	at org.apache.hadoop.mapred.MapTask$1.next(MapTask.java:176)
> Ideally the recordreader should just skip the entire chunk if it gets an unrecoverable error while reading.
> This was the consensus in hadoop-153 as well (that data corruptions should be handled by recordreaders) and hadoop-3144 did something similar for textinputformat.

-- 
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.