// must spill to disk, but can't retain in-mem for intermediate merge
final Path outputPath =
mapOutputFile.getInputFileForWrite(mapId,
inMemToDiskBytes).suffix(
Task.MERGED_OUTPUT_PREFIX);
final RawKeyValueIterator rIter = Merger.merge(job, fs,
keyClass, valueClass, memDiskSegments, numMemDiskSegments,
tmpDir, comparator, reporter, spilledRecordsCounter, null,
mergePhase);
final Writer<K,V> writer = new Writer<K,V>(job, fs, outputPath,
keyClass, valueClass, codec, null);
try {
Merger.writeFile(rIter, writer, reporter, job);
// add to list of final disk outputs.
onDiskMapOutputs.add(outputPath);
} catch (IOException e) {
if (null != outputPath) {
try {
fs.delete(outputPath, true);
} catch (IOException ie) {
// NOTHING
}
}
throw e;
} finally {
if (null != writer) {
writer.close();
}
}
LOG.info("Merged " + numMemDiskSegments + " segments, " +
inMemToDiskBytes + " bytes to disk to satisfy " +
"reduce memory limit");
inMemToDiskBytes = 0;
memDiskSegments.clear();
} else if (inMemToDiskBytes != 0) {
LOG.info("Keeping " + numMemDiskSegments + " segments, " +
inMemToDiskBytes + " bytes in memory for " +
"intermediate, on-disk merge");
}
}
// segments on disk
List<Segment<K,V>> diskSegments = new ArrayList<Segment<K,V>>();
long onDiskBytes = inMemToDiskBytes;
Path[] onDisk = onDiskMapOutputs.toArray(new Path[onDiskMapOutputs.size()]);
for (Path file : onDisk) {
onDiskBytes += fs.getFileStatus(file).getLen();
LOG.debug("Disk file: " + file + " Length is " +
fs.getFileStatus(file).getLen());
diskSegments.add(new Segment<K, V>(job, fs, file, codec, keepInputs,
(file.toString().endsWith(
Task.MERGED_OUTPUT_PREFIX) ?
null : mergedMapOutputsCounter)
));
}
LOG.info("Merging " + onDisk.length + " files, " +
onDiskBytes + " bytes from disk");
Collections.sort(diskSegments, new Comparator<Segment<K,V>>() {
public int compare(Segment<K, V> o1, Segment<K, V> o2) {
if (o1.getLength() == o2.getLength()) {
return 0;
}
return o1.getLength() < o2.getLength() ? -1 : 1;
}
});
// build final list of segments from merged backed by disk + in-mem
List<Segment<K,V>> finalSegments = new ArrayList<Segment<K,V>>();
long inMemBytes = createInMemorySegments(inMemoryMapOutputs,
finalSegments, 0);
LOG.info("Merging " + finalSegments.size() + " segments, " +
inMemBytes + " bytes from memory into reduce");
if (0 != onDiskBytes) {
final int numInMemSegments = memDiskSegments.size();
diskSegments.addAll(0, memDiskSegments);
memDiskSegments.clear();
// Pass mergePhase only if there is a going to be intermediate
// merges. See comment where mergePhaseFinished is being set
Progress thisPhase = (mergePhaseFinished) ? null : mergePhase;
RawKeyValueIterator diskMerge = Merger.merge(
job, fs, keyClass, valueClass,codec, diskSegments,
ioSortFactor, numInMemSegments, tmpDir, comparator,
reporter, false, spilledRecordsCounter, null, thisPhase);
diskSegments.clear();
if (0 == finalSegments.size()) {