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bert Passek commented on CASSANDRA-4229: ---------------------------------------- Hello, i spend some time for debugging and i could find the reason for the problem described above. This is the map function for reading from cassandra: protected void map(ByteBuffer key, SortedMap<ByteBuffer, IColumn> values, Context context); If you are using the row-key, you must duplicate the bytebuffer, otherwise the RowIterator in ColumnFamilyRecordReader does not finish correctly. This is one of the exit-condition in StaticRowIterator: startToken = partitioner.getTokenFactory().toString(partitioner.getToken(Iterables.getLast(rows).key)); if (startToken.equals(split.getEndToken())) { // reached end of the split rows = null; return; } Without duplicating the row-key you will never run into it. This kind of behaviour was different to former versions of Cassandra und should be clearly documented. Best Regards bert Passek > Infinite MapReduce Task while reading via ColumnFamilyInputFormat > ----------------------------------------------------------------- > > Key: CASSANDRA-4229 > URL: https://issues.apache.org/jira/browse/CASSANDRA-4229 > Project: Cassandra > Issue Type: Bug > Components: Hadoop > Affects Versions: 1.1.0 > Environment: Debian Squeeze > Reporter: bert Passek > Attachments: screenshot.jpg > > > Hi, > we recently upgraded cassandra from version 1.0.9 to 1.1.0. After that we can > not execute any hadoop jobs which reads data from cassandra via > ColumnFamilyInputFormat. > A map task is created which is running infinitely. We are trying to read from > a super column family with more or less 1000 row keys. > This is the output from job interface where we already have 17 million map > input records !!! > Map input records 17.273.127 0 17.273.127 > Reduce shuffle bytes 0 391 391 > Spilled Records 3.288 0 3.288 > Map output bytes 639.849.351 0 639.849.351 > CPU time spent (ms) 792.750 7.600 800.350 > Total committed heap usage (bytes) 354.680.832 48.955.392 > 403.636.224 > Combine input records 17.039.783 0 17.039.783 > SPLIT_RAW_BYTES 212 0 212 > Reduce input records 0 0 0 > Reduce input groups 0 0 0 > Combine output records 3.288 0 3.288 > Physical memory (bytes) snapshot 510.275.584 96.370.688 > 606.646.272 > Reduce output records 0 0 0 > Virtual memory (bytes) snapshot 1.826.496.512 934.473.728 > 2.760.970.240 > Map output records 17.273.126 0 17.273.126 > We must kill the job and we have to go back to version 1.0.9 because 1.1.0 is > not usable for reading from cassandra. > Best regards > Bert Passek -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa For more information on JIRA, see: http://www.atlassian.com/software/jira