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Harsh J Chouraria commented on MAPREDUCE-1347: ---------------------------------------------- Note: Guava has been added as a dependency. A thread where it was agreed upon can be found here: http://search-hadoop.com/m/NrnW72tdHRD1/guava&subj=Add+Guava+as+a+dependency+ > Missing synchronization in MultipleOutputFormat > ----------------------------------------------- > > Key: MAPREDUCE-1347 > URL: https://issues.apache.org/jira/browse/MAPREDUCE-1347 > Project: Hadoop Map/Reduce > Issue Type: Bug > Affects Versions: 0.20.2, 0.21.0, 0.22.0 > Reporter: Todd Lipcon > Assignee: Harsh J Chouraria > Attachments: MAPREDUCE-1347.r2.diff, mapreduce.1347.r1.diff > > > MultipleOutputFormat's RecordWriter implementation doesn't use > synchronization when accessing the recordWriters member. When using > multithreaded mappers or reducers, this can result in problems where two > threads will both try to create the same file, causing > AlreadyBeingCreatedException. Doing this more fine-grained than just > synchronizing the whole method is probably a good idea, so that multithreaded > mappers can actually achieve parallelism writing into separate output streams. > From what I can tell, the new API's MultipleOutputs seems not to have this > issue. -- This message is automatically generated by JIRA. For more information on JIRA, see: http://www.atlassian.com/software/jira