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From "Roland (JIRA)" <j...@apache.org>
Subject [jira] [Created] (GORA-211) thread safety: java.lang.NullPointerException
Date Wed, 27 Feb 2013 11:27:12 GMT
Roland created GORA-211:
---------------------------

             Summary: thread safety: java.lang.NullPointerException
                 Key: GORA-211
                 URL: https://issues.apache.org/jira/browse/GORA-211
             Project: Apache Gora
          Issue Type: Bug
          Components: storage-cassandra
    Affects Versions: 0.2
         Environment: nutch 2.1 / cassandra 1.2.1 / gora-cassandra 0.2 / gora-core 0.2.1 
running fetch with parse=true 
fetcher.threads.per.queue>1
            Reporter: Roland
            Priority: Critical


This is the result of debugging one of my issues described in NUTCH-1534. 

example trace:
java.lang.NullPointerException
        at me.prettyprint.cassandra.model.MutatorImpl.execute(MutatorImpl.java:243)
        at me.prettyprint.cassandra.model.MutatorImpl.insert(MutatorImpl.java:71)
        at org.apache.gora.cassandra.store.CassandraClient.addColumn(CassandraClient.java:139)
        at org.apache.gora.cassandra.store.CassandraStore.addOrUpdateField(CassandraStore.java:307)
        at org.apache.gora.cassandra.store.CassandraStore.flush(CassandraStore.java:212)
        at org.apache.gora.mapreduce.GoraRecordWriter.write(GoraRecordWriter.java:65)
        at org.apache.hadoop.mapred.ReduceTask$NewTrackingRecordWriter.write(ReduceTask.java:587)
        at org.apache.hadoop.mapreduce.TaskInputOutputContext.write(TaskInputOutputContext.java:80)
        at org.apache.nutch.fetcher.FetcherReducer$FetcherThread.output(FetcherReducer.java:664)
        at org.apache.nutch.fetcher.FetcherReducer$FetcherThread.run(FetcherReducer.java:534)

I'm suspecting CassandraStore.put() not taking enough precautions to copy all objects safely
to it's buffer.
{code}
        switch(type) {
          case RECORD:
            Persistent persistent = (Persistent) fieldValue;
            Persistent newRecord = persistent.newInstance(new StateManagerImpl());
            for (Field member: fieldSchema.getFields()) {
              newRecord.put(member.pos(), persistent.get(member.pos()));
            }
            fieldValue = newRecord;
            break;
          case MAP:
            StatefulHashMap<?, ?> map = (StatefulHashMap<?, ?>) fieldValue;
            StatefulHashMap<?, ?> newMap = new StatefulHashMap(map);
            fieldValue = newMap;
            break;
        }
{code}

case RECORD - do we not need to duplicate the object returned by "persistent.get(member.pos())":
  newRecord.put(member.pos(), persistent.get(member.pos()))

case MAP - do we not need to duplicate all value-objects of the map?

I had not time to write a patch or test this, so, please comment :)

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