[GitHub] [spark] squito commented on a change in pull request #25304: [SPARK-28570][CORE][SHUFFLE] Make UnsafeShuffleWriter use the new API.

[GitBox <gi...@apache.org>]

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_r309011967
 
 

 ##########
 File path: core/src/main/java/org/apache/spark/shuffle/sort/UnsafeShuffleWriter.java
 ##########
 @@ -316,102 +304,100 @@ void forceSorterToSpill() throws IOException {
           // that doesn't need to interpret the spilled bytes.
           if (transferToEnabled && !encryptionEnabled) {
             logger.debug("Using transferTo-based fast merge");
-            partitionLengths = mergeSpillsWithTransferTo(spills, outputFile);
+            partitionLengths = mergeSpillsWithTransferTo(spills, mapWriter);
           } else {
             logger.debug("Using fileStream-based fast merge");
-            partitionLengths = mergeSpillsWithFileStream(spills, outputFile, null);
+            partitionLengths = mergeSpillsWithFileStream(spills, mapWriter, null);
           }
         } else {
           logger.debug("Using slow merge");
-          partitionLengths = mergeSpillsWithFileStream(spills, outputFile, compressionCodec);
+          partitionLengths = mergeSpillsWithFileStream(spills, mapWriter, compressionCodec);
         }
         // When closing an UnsafeShuffleExternalSorter that has already spilled once but also has
         // in-memory records, we write out the in-memory records to a file but do not count that
         // final write as bytes spilled (instead, it's accounted as shuffle write). The merge needs
         // to be counted as shuffle write, but this will lead to double-counting of the final
         // SpillInfo's bytes.
         writeMetrics.decBytesWritten(spills[spills.length - 1].file.length());
-        writeMetrics.incBytesWritten(outputFile.length());
         return partitionLengths;
       }
     } catch (IOException e) {
-      if (outputFile.exists() && !outputFile.delete()) {
-        logger.error("Unable to delete output file {}", outputFile.getPath());
-      }
       throw e;
     }
   }
 
   /**
    * Merges spill files using Java FileStreams. This code path is typically slower than
    * the NIO-based merge, {@link UnsafeShuffleWriter#mergeSpillsWithTransferTo(SpillInfo[],
-   * File)}, and it's mostly used in cases where the IO compression codec does not support
-   * concatenation of compressed data, when encryption is enabled, or when users have
-   * explicitly disabled use of {@code transferTo} in order to work around kernel bugs.
+   * ShuffleMapOutputWriter)}, and it's mostly used in cases where the IO compression codec
+   * does not support concatenation of compressed data, when encryption is enabled, or when
+   * users have explicitly disabled use of {@code transferTo} in order to work around kernel bugs.
    * This code path might also be faster in cases where individual partition size in a spill
    * is small and UnsafeShuffleWriter#mergeSpillsWithTransferTo method performs many small
    * disk ios which is inefficient. In those case, Using large buffers for input and output
    * files helps reducing the number of disk ios, making the file merging faster.
    *
    * @param spills the spills to merge.
-   * @param outputFile the file to write the merged data to.
+   * @param mapWriter the map output writer to use for output.
    * @param compressionCodec the IO compression codec, or null if shuffle compression is disabled.
    * @return the partition lengths in the merged file.
    */
   private long[] mergeSpillsWithFileStream(
       SpillInfo[] spills,
-      File outputFile,
+      ShuffleMapOutputWriter mapWriter,
       @Nullable CompressionCodec compressionCodec) throws IOException {
-    assert (spills.length >= 2);
     final int numPartitions = partitioner.numPartitions();
     final long[] partitionLengths = new long[numPartitions];
     final InputStream[] spillInputStreams = new InputStream[spills.length];
 
-    final OutputStream bos = new BufferedOutputStream(
-            new FileOutputStream(outputFile),
-            outputBufferSizeInBytes);
-    // Use a counting output stream to avoid having to close the underlying file and ask
-    // the file system for its size after each partition is written.
-    final CountingOutputStream mergedFileOutputStream = new CountingOutputStream(bos);
-
     boolean threwException = true;
     try {
       for (int i = 0; i < spills.length; i++) {
         spillInputStreams[i] = new NioBufferedFileInputStream(
-            spills[i].file,
-            inputBufferSizeInBytes);
+          spills[i].file,
+          inputBufferSizeInBytes);
       }
       for (int partition = 0; partition < numPartitions; partition++) {
-        final long initialFileLength = mergedFileOutputStream.getByteCount();
-        // Shield the underlying output stream from close() and flush() calls, so that we can close
-        // the higher level streams to make sure all data is really flushed and internal state is
-        // cleaned.
-        OutputStream partitionOutput = new CloseAndFlushShieldOutputStream(
-          new TimeTrackingOutputStream(writeMetrics, mergedFileOutputStream));
-        partitionOutput = blockManager.serializerManager().wrapForEncryption(partitionOutput);
-        if (compressionCodec != null) {
-          partitionOutput = compressionCodec.compressedOutputStream(partitionOutput);
-        }
-        for (int i = 0; i < spills.length; i++) {
-          final long partitionLengthInSpill = spills[i].partitionLengths[partition];
-          if (partitionLengthInSpill > 0) {
-            InputStream partitionInputStream = new LimitedInputStream(spillInputStreams[i],
-              partitionLengthInSpill, false);
-            try {
-              partitionInputStream = blockManager.serializerManager().wrapForEncryption(
-                partitionInputStream);
-              if (compressionCodec != null) {
-                partitionInputStream = compressionCodec.compressedInputStream(partitionInputStream);
+        boolean copyThrewExecption = true;
+        ShufflePartitionWriter writer = mapWriter.getPartitionWriter(partition);
+        OutputStream partitionOutput = writer.openStream();
+        try {
+          // Shield the underlying output stream from close() calls, so that we can close the
+          // higher level streams to make sure all data is really flushed and internal state
+          // is cleaned
 
 Review comment:
   comment doesn't belong here anymore -- you're not doing any shielding here, its left to individual implementations to to do (as you do in LocalDiskShuffleMapOutputWriter)

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