Affects Version/s: 1.7.4, 1.7.7
Fix Version/s: None
CentOS 6.5 Linux x64, 2.6.32-358.14.1.el6.x86_64
Use IBM JVM:
IBM J9 VM (build 2.7, JRE 1.7.0 Linux amd64-64 Compressed References 20140515_199835 (JIT enabled, AOT enabled)
Our production cluster is CENTOS 6.5 (2.6.32-358.14.1.el6.x86_64), running IBM BigInsight V220.127.116.11. In Apache term, it is Hadoop 2.2.0 with MRV1(no yarn), and comes with AVRO 1.7.4, running with IBM J9 VM (build 2.7, JRE 1.7.0 Linux amd64-64 Compressed References 20140515_199835 (JIT enabled, AOT enabled). Not sure if the JDK matters, but it is NOT Oracle JVM.
We have a ETL implemented in a chain of MR jobs. In one MR job, it is going to merge 2 sets of AVRO data. Dataset1 is in HDFS location A, and Dataset2 is in HDFS location B, and both contains the AVRO records binding to the same AVRO schema. The record contains an unique id field, and a timestamp field. The MR job is to merge the records based on the ID, and use the later timestamp record to replace previous timestamp record, and omit the final AVRO record out. Very straightforward.
Now we faced a problem that one reducer keeps failing with the following stacktrace on JobTracker:
Here is the my Mapper and Reducer methods:
public void map(AvroKey<SpecificRecord> key, NullWritable value, Context context) throws IOException, InterruptedException
protected void reduce(CustomPartitionKeyClass key, Iterable<AvroValue<SpecificRecord>> values, Context context) throws IOException, InterruptedException
What bother me are the following facts:
1) All the mappers finish without error
2) Most of the reducers finish without error, but one reducer keeps failing with the above error.
3) It looks like caused by the data? But keep in mind that all the avro records passed the mapper side, but failed in one reducer.
4) From the stacktrace, it looks like our reducer code was NOT invoked yet, but failed before that. So my guess is that all the AVRO records pass through the mapper side, but AVRO complains the intermediate result generated by the one mapper? In my understanding, that will be a Sequence file generated by Hadoop, and value part will be the AVRO bytes. Is the above error meaning that AVRO cannot deserialize the value part from the sequence file?
5) Our ETL run fine for more than one year, but suddenly got this error starting from one day, and kept getting this problem after that.
6) If it helps, here is the schema for the avro record: