[GitHub] [spark] cloud-fan commented on a change in pull request #32198: [SPARK-26164][SQL] Allow concurrent writers for writing dynamic partitions and bucket table

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

cloud-fan commented on a change in pull request #32198:
URL: https://github.com/apache/spark/pull/32198#discussion_r616724095



##########
File path: sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/FileFormatDataWriter.scala
##########
@@ -247,34 +290,168 @@ class DynamicPartitionDataWriter(
     val nextPartitionValues = if (isPartitioned) Some(getPartitionValues(record)) else None
     val nextBucketId = if (isBucketed) Some(getBucketId(record)) else None
 
-    if (currentPartitionValues != nextPartitionValues || currentBucketId != nextBucketId) {
+    if (currentWriterId.partitionValues != nextPartitionValues ||
+      currentWriterId.bucketId != nextBucketId) {
       // See a new partition or bucket - write to a new partition dir (or a new bucket file).
-      if (isPartitioned && currentPartitionValues != nextPartitionValues) {
-        currentPartitionValues = Some(nextPartitionValues.get.copy())
-        statsTrackers.foreach(_.newPartition(currentPartitionValues.get))
-      }
+      updateCurrentWriterStatus()
+
       if (isBucketed) {
-        currentBucketId = nextBucketId
-        statsTrackers.foreach(_.newBucket(currentBucketId.get))
+        currentWriterId.bucketId = nextBucketId
+      }
+      if (isPartitioned && currentWriterId.partitionValues != nextPartitionValues) {
+        currentWriterId.partitionValues = Some(nextPartitionValues.get.copy())
+        if (mode == SingleWriter || !concurrentWriters.contains(currentWriterId)) {
+          statsTrackers.foreach(_.newPartition(currentWriterId.partitionValues.get))
+        }
       }
 
-      fileCounter = 0
-      newOutputWriter(currentPartitionValues, currentBucketId)
-    } else if (description.maxRecordsPerFile > 0 &&
+      getOrNewOutputWriter()
+    }
+
+    if (description.maxRecordsPerFile > 0 &&
       recordsInFile >= description.maxRecordsPerFile) {
       // Exceeded the threshold in terms of the number of records per file.
       // Create a new file by increasing the file counter.
       fileCounter += 1
       assert(fileCounter < MAX_FILE_COUNTER,
         s"File counter $fileCounter is beyond max value $MAX_FILE_COUNTER")
 
-      newOutputWriter(currentPartitionValues, currentBucketId)
+      newOutputWriter(currentWriterId.partitionValues, currentWriterId.bucketId, true)
     }
     val outputRow = getOutputRow(record)
     currentWriter.write(outputRow)
     statsTrackers.foreach(_.newRow(outputRow))
     recordsInFile += 1
   }
+
+  /**
+   * Dedicated write code path when enabling concurrent writers.
+   *
+   * The process has the following step:
+   *  - Step 1: Maintain a map of output writers per each partition and/or bucket columns.
+   *            Keep all writers open and write rows one by one.
+   *  - Step 2: If number of concurrent writers exceeds limit, sort rest of rows. Write rows
+   *            one by one, and eagerly close the writer when finishing each partition and/or
+   *            bucket.
+   */
+  def writeWithIterator(iterator: Iterator[InternalRow]): Unit = {
+    while (iterator.hasNext && mode == ConcurrentWriterBeforeSort) {
+      write(iterator.next())
+    }
+
+    if (iterator.hasNext) {
+      resetWriterStatus()
+      val sorter = concurrentOutputWriterSpec.get.createSorter()
+      val sortIterator = sorter.sort(iterator.asInstanceOf[Iterator[UnsafeRow]])
+      while (sortIterator.hasNext) {
+        write(sortIterator.next())
+      }
+    }
+  }
+
+  sealed abstract class WriterMode
+
+  /**
+   * Single writer mode always has at most one writer.
+   * The output is expected to be sorted on partition and/or bucket columns before writing.
+   */
+  case object SingleWriter extends WriterMode
+
+  /**
+   * Concurrent writer mode before sort happens, and can have multiple concurrent writers
+   * for each partition and/or bucket columns.

Review comment:
       `columns` -> `values`?




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