//Note that the above Path[] could be of length 0 if all copies are
//in flight. So we make sure that we have some 'closed' map
//output files to merge to get the benefit of in-memory merge
if (inMemClosedFiles.length >=
(int)(MAX_INMEM_FILESYS_USE/MAX_INMEM_FILESIZE_FRACTION)) {
RawKeyValueIterator rIter = sorter.merge(inMemClosedFiles, true,
inMemClosedFiles.length);
//name this output file same as the name of the first file that is
//there in the current list of inmem files (this is guaranteed to be
//absent on the disk currently. So we don't overwrite a prev.
//created spill)