well, I figured out the reason of that problem. Mahout's MatrixMultiplicationJob uses a CompositeInputFormat to join the input rows of the two matrices being multiplied. CompositeInputFormat requires that the two matrices should be partitioned the same way. My first matrix was in a single sequence file while the second matrix was the output of a previous mapreduce job with multiple reducers (so it was partitioned into multiple sequence files). Am I missing something here? or it's a limitation with the multiplication job. Is there an efficient way to avoid this limitation?
thanks, --ahmed On Sun, Sep 2, 2012 at 12:42 AM, Ahmed Elgohary <[email protected]> wrote: > Hi, > > I was multiplying two matrices using > DistributedRowMatrix.times(DistributedrowMatrix other). The two matrices > were of size 15x30 (small experiment on my local machine). I got the > following exception: > > 12/09/01 23:33:46 ERROR security.UserGroupInformation: > PriviledgedActionException as:ahmed cause:java.io.IOException: Inconsistent > split cardinality from child 1 (2/1) > Exception in thread "main" java.io.IOException: Inconsistent split > cardinality from child 1 (2/1) > at > org.apache.hadoop.mapred.join.Parser$CNode.getSplits(Parser.java:369) > at > org.apache.hadoop.mapred.join.CompositeInputFormat.getSplits(CompositeInputFormat.java:117) > at > org.apache.hadoop.mapred.JobClient.writeOldSplits(JobClient.java:989) > at org.apache.hadoop.mapred.JobClient.writeSplits(JobClient.java:981) > at org.apache.hadoop.mapred.JobClient.access$600(JobClient.java:174) > at org.apache.hadoop.mapred.JobClient$2.run(JobClient.java:897) > at org.apache.hadoop.mapred.JobClient$2.run(JobClient.java:850) > at java.security.AccessController.doPrivileged(Native Method) > at javax.security.auth.Subject.doAs(Subject.java:396) > at > org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1121) > at > org.apache.hadoop.mapred.JobClient.submitJobInternal(JobClient.java:850) > at org.apache.hadoop.mapred.JobClient.submitJob(JobClient.java:824) > at org.apache.hadoop.mapred.JobClient.runJob(JobClient.java:1261) > at > org.apache.mahout.math.hadoop.DistributedRowMatrix.times(DistributedRowMatrix.java:189) > at > baselines.ReconstructionError.clacReconstructionErr(ReconstructionError.java:45) > at baselines.Main.runRandomSelection(Main.java:108) > at baselines.Main.main(Main.java:154) > at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) > at > sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) > at > sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) > at java.lang.reflect.Method.invoke(Method.java:597) > at org.apache.hadoop.util.RunJar.main(RunJar.java:156) > > Any idea what might be the reason of that error? > > --ahmed >
