squito commented on a change in pull request #25304:
[SPARK-28570][CORE][SHUFFLE] Make UnsafeShuffleWriter use the new API.
URL: https://github.com/apache/spark/pull/25304#discussion_r311131107
##########
File path:
core/src/main/java/org/apache/spark/shuffle/sort/UnsafeShuffleWriter.java
##########
@@ -273,57 +259,93 @@ void forceSorterToSpill() throws IOException {
*
* @return the partition lengths in the merged file.
*/
- private long[] mergeSpills(SpillInfo[] spills,
- ShuffleMapOutputWriter mapWriter) throws IOException {
+ private long[] mergeSpills(SpillInfo[] spills) throws IOException {
+ long[] partitionLengths;
+ if (spills.length == 0) {
+ final ShuffleMapOutputWriter mapWriter = shuffleExecutorComponents
+ .createMapOutputWriter(
+ shuffleId,
+ mapId,
+ taskContext.taskAttemptId(),
+ partitioner.numPartitions());
+ mapWriter.commitAllPartitions();
+ return new long[partitioner.numPartitions()];
+ } else if (spills.length == 1) {
+ Optional<SingleFileShuffleMapOutputWriter> maybeSingleFileWriter =
+ shuffleExecutorComponents.createSingleFileMapOutputWriter(
+ shuffleId, mapId, taskContext.taskAttemptId());
+ if (maybeSingleFileWriter.isPresent()) {
+ // Here, we don't need to perform any metrics updates because the
bytes written to this
+ // output file would have already been counted as shuffle bytes
written.
Review comment:
this comment is only true for the local disk implementation. eg. if some
other implementation did take advantage of the single merged file somehow, and
wrote it all to a remote store, it would be doing another write.
But I am not really worried about this, as I don't think any other store
will actually use this ...
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