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https://issues.apache.org/jira/browse/GORA-210?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13587314#comment-13587314
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Renato Javier Marroquín Mogrovejo commented on GORA-210:
--------------------------------------------------------
Ok I think I get it now (: I think what confused me was that part "iterating
over any of its collection views" and getting the keySet made me think that we
needed to synchronize these extra data structures as well. Thanks!
> thread safety
> -------------
>
> Key: GORA-210
> URL: https://issues.apache.org/jira/browse/GORA-210
> 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
> Labels: patch
> Attachments: GORA-210.patch
>
>
> This is the result of debugging one of my issues described in NUTCH-1534.
> I think there is a wrong assumpation about thread safety of LinkedHashMap, it
> is not enough to not iterate over the buffer (which is a LinkedHashMap).
> My patch fixes this error for me:
> java.util.ConcurrentModificationException
> at
> java.util.LinkedHashMap$LinkedHashIterator.nextEntry(LinkedHashMap.java:394)
> at java.util.LinkedHashMap$KeyIterator.next(LinkedHashMap.java:405)
> at java.util.AbstractCollection.toArray(AbstractCollection.java:141)
> at
> org.apache.gora.cassandra.store.CassandraStore.flush(CassandraStore.java:200)
> 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)
> It may not be perfect from a performance point of view...
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