i retested it and oom error is also in 2.0.3, but not in 1.x.
how much memory is needed for reducer during shuffle and sort? Peak usage is memoryLimit or there have to be additional memory for mapred.reduce.parallel.copies fetch buffers?
MergerManager: memoryLimit=326264416, maxSingleShuffleLimit=81566104, mergeThreshold=215334528, ioSortFactor=10, memToMemMergeOutputsThreshold=10
