The default batch size is 4096, which means that each call to get_range_slices retrieves 4,096 rows. I have found that this causes timeouts when cassandra is under load. Try reducing the batchsize with a call to ConfigHelper.setRangeBatchSize(). This has eliminated the TimedOutExceptions for us. joost.
On Thu, Apr 29, 2010 at 10:25 AM, Utku Can Topçu <u...@topcu.gen.tr> wrote: > Hey All, > > I'm trying to run some tests on cassandra an Hadoop integration. I'm > basically following the word count example at > https://svn.apache.org/repos/asf/cassandra/trunk/contrib/word_count/src/WordCount.java > using the ColumnFamilyInputFormat. > > Currently I have one-node cassandra and hadoop setup on the same machine. > > I'm having problems if there are more than one map tasks running on the same > node, please find the copy of the error message below. > > If I limit the map tasks per tasktracker to 1, the MapReduce works fine > without anyproblems at all. > > Do you thinki it's a know issue or am I doing something wrong in > implementation. > > ---------------error---------------- > 10/04/29 13:47:37 INFO mapred.JobClient: Task Id : > attempt_201004291109_0024_m_000000_1, Status : FAILED > 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:621) > at org.apache.hadoop.mapred.MapTask.run(MapTask.java:305) > at org.apache.hadoop.mapred.Child.main(Child.java:170) > 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 > --------------------------------------- > > > Best Regards, > Utku >
