Hi On Sun, Feb 12, 2012 at 8:58 PM, Mike Spreitzer <mspre...@us.ibm.com> wrote: > I have a question about the contract in the > org.apache.hadoop.mapred.OutputCollector interface. If it matters, let us > say we are talking about Hadoop-1.0.0. In my map or reduce method, after it > calls output.collect(key,value), is it allowed to mutate (side effect) > either the key or the value? > > If the answer is "it depends on the OutputFormat", then what is the answer > for the more prominent ones, such as SequenceFileFormat and > TextOutputFormat?
In both cases the key is serialized immediately so the caller cannot mutate the key after calling collect. http://svn.apache.org/repos/asf/hadoop/common/branches/branch-1.0/src/mapred/org/apache/hadoop/mapred/TextOutputFormat.java http://svn.apache.org/repos/asf/hadoop/common/branches/branch-1.0/src/mapred/org/apache/hadoop/mapred/SequenceFileOutputFormat.java http://svn.apache.org/repos/asf/hadoop/common/branches/branch-1.0/src/core/org/apache/hadoop/io/SequenceFile.java -- Apache MRUnit - Unit testing MapReduce - http://incubator.apache.org/mrunit/
