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From Joost Ouwerkerk <jo...@openplaces.org>
Subject Re: timeout while running simple hadoop job
Date Fri, 07 May 2010 12:48:27 GMT
Huh? Isn't that the whole point of using Map/Reduce?

On Fri, May 7, 2010 at 8:44 AM, Jonathan Ellis <jbellis@gmail.com> wrote:
> Sounds like you need to configure Hadoop to not create a whole bunch
> of Map tasks at once
>
> On Fri, May 7, 2010 at 3:47 AM, gabriele renzi <rff.rff@gmail.com> wrote:
>> Hi everyone,
>>
>> I am trying to develop a mapreduce job that does a simple
>> selection+filter on the rows in our store.
>> Of course it is mostly based on the WordCount example :)
>>
>>
>> Sadly, while it seems the app runs fine on a test keyspace with little
>> data, when run on a larger test index (but still on a single node) I
>> reliably see this error in the logs
>>
>> 10/05/06 16:37:58 WARN mapred.LocalJobRunner: job_local_0001
>> java.lang.RuntimeException: TimedOutException()
>>        at org.apache.cassandra.hadoop.ColumnFamilyRecordReader$RowIterator.maybeInit(ColumnFamilyRecordReader.java:165)
>>        at org.apache.cassandra.hadoop.ColumnFamilyRecordReader$RowIterator.computeNext(ColumnFamilyRecordReader.java:215)
>>        at org.apache.cassandra.hadoop.ColumnFamilyRecordReader$RowIterator.computeNext(ColumnFamilyRecordReader.java:97)
>>        at com.google.common.collect.AbstractIterator.tryToComputeNext(AbstractIterator.java:135)
>>        at com.google.common.collect.AbstractIterator.hasNext(AbstractIterator.java:130)
>>        at org.apache.cassandra.hadoop.ColumnFamilyRecordReader.nextKeyValue(ColumnFamilyRecordReader.java:91)
>>        at org.apache.hadoop.mapred.MapTask$NewTrackingRecordReader.nextKeyValue(MapTask.java:423)
>>        at org.apache.hadoop.mapreduce.MapContext.nextKeyValue(MapContext.java:67)
>>        at org.apache.hadoop.mapreduce.Mapper.run(Mapper.java:143)
>>        at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:583)
>>        at org.apache.hadoop.mapred.MapTask.run(MapTask.java:305)
>>        at org.apache.hadoop.mapred.LocalJobRunner$Job.run(LocalJobRunner.java:176)
>> Caused by: TimedOutException()
>>        at org.apache.cassandra.thrift.Cassandra$get_range_slices_result.read(Cassandra.java:11015)
>>        at org.apache.cassandra.thrift.Cassandra$Client.recv_get_range_slices(Cassandra.java:623)
>>        at org.apache.cassandra.thrift.Cassandra$Client.get_range_slices(Cassandra.java:597)
>>        at org.apache.cassandra.hadoop.ColumnFamilyRecordReader$RowIterator.maybeInit(ColumnFamilyRecordReader.java:142)
>>        ... 11 more
>>
>> and after that the job seems to finish "normally" but no results are produced.
>>
>> FWIW this is on 0.6.0 (we didn't move to 0.6.1 yet because, well, if
>> it ain't broke don't fix it).
>>
>> The single node has a data directory of about 127GB in two column
>> families, off which the one used in the mapred job is about 100GB.
>> The cassandra server is run with 6GB of heap on a box with 8GB
>> available and no swap enabled. read/write latency from cfstat are
>>
>>        Read Latency: 0.8535837762577986 ms.
>>        Write Latency: 0.028849603764075547 ms.
>>
>> row cache is not enabled, key cache percentage is default. Load on the
>> machine is basically zero when the job is not running.
>>
>> As my code is 99% that from the wordcount contrib, I shall notice that
>> In 0.6.1's contrib (and trunk) there is a RING_DELAY constant that we
>> can supposedly change, but it's apparently not used anywhere, but as I
>> said, running on a single node this should not be an issue anyway.
>>
>> Does anyone has suggestions or has seen this error before? On the
>> other hand, did people run this kind of jobs in similar conditions
>> flawlessly, so I can consider it just my problem?
>>
>>
>> Thanks in advance for any help.
>>
>
>
>
> --
> Jonathan Ellis
> Project Chair, Apache Cassandra
> co-founder of Riptano, the source for professional Cassandra support
> http://riptano.com
>

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