[SPARK-13850] Force the sorter to Spill when number of elements in the pointer array reach a certain size. This is to workaround the issue of timSort failing on large buffer size.

Author: Sital Kedia

core/src/main/java/org/apache/spark/shuffle/sort/ShuffleExternalSorter.java

@@ -72,7 +72,10 @@ final class ShuffleExternalSorter extends MemoryConsumer {
   private final TaskContext taskContext;
   private final ShuffleWriteMetrics writeMetrics;
 
-  /** Force this sorter to spill when there are this many elements in memory. For testing only */
+  /**
+   * Force this sorter to spill when there are this many elements in memory. The default value is
+   * 1024 * 1024 * 1024, which allows the maximum size of the pointer array to be 8G.
+   */
   private final long numElementsForSpillThreshold;
 
   /** The buffer size to use when writing spills using DiskBlockObjectWriter */
@@ -114,7 +117,7 @@ final class ShuffleExternalSorter extends MemoryConsumer {
     // Use getSizeAsKb (not bytes) to maintain backwards compatibility if no units are provided
     this.fileBufferSizeBytes = (int) conf.getSizeAsKb("spark.shuffle.file.buffer", "32k") * 1024;
     this.numElementsForSpillThreshold =
-      conf.getLong("spark.shuffle.spill.numElementsForceSpillThreshold", Long.MAX_VALUE);
+      conf.getLong("spark.shuffle.spill.numElementsForceSpillThreshold", 1024 * 1024 * 1024);
     this.writeMetrics = writeMetrics;
     this.inMemSorter = new ShuffleInMemorySorter(
       this, initialSize, conf.getBoolean("spark.shuffle.sort.useRadixSort", true));
@@ -372,7 +375,8 @@ public void insertRecord(Object recordBase, long recordOffset, int length, int p
 
     // for tests
     assert(inMemSorter != null);
-    if (inMemSorter.numRecords() > numElementsForSpillThreshold) {
+    if (inMemSorter.numRecords() >= numElementsForSpillThreshold) {
+      logger.info("Spilling data because number of spilledRecords crossed the threshold " + numElementsForSpillThreshold);
       spill();
     }
 

core/src/main/java/org/apache/spark/util/collection/unsafe/sort/UnsafeExternalSorter.java

@@ -27,6 +27,7 @@
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import org.apache.spark.SparkEnv;
 import org.apache.spark.TaskContext;
 import org.apache.spark.executor.ShuffleWriteMetrics;
 import org.apache.spark.memory.MemoryConsumer;
@@ -59,6 +60,13 @@ public final class UnsafeExternalSorter extends MemoryConsumer {
   /** The buffer size to use when writing spills using DiskBlockObjectWriter */
   private final int fileBufferSizeBytes;
 
+  /**
+   * Force this sorter to spill when there are this many elements in memory. The default value is
+   * 1024 * 1024 * 1024 / 2 which allows the maximum size of the pointer array to be 8G.
+   */
+  public static final long DEFAULT_NUM_ELEMENTS_FOR_SPILL_THRESHOLD = 1024 * 1024 * 1024 / 2;
+
+  private final long numElementsForSpillThreshold;
   /**
    * Memory pages that hold the records being sorted. The pages in this list are freed when
    * spilling, although in principle we could recycle these pages across spills (on the other hand,
@@ -88,9 +96,10 @@ public static UnsafeExternalSorter createWithExistingInMemorySorter(
       PrefixComparator prefixComparator,
       int initialSize,
       long pageSizeBytes,
+      long numElementsForSpillThreshold,
       UnsafeInMemorySorter inMemorySorter) throws IOException {
     UnsafeExternalSorter sorter = new UnsafeExternalSorter(taskMemoryManager, blockManager,
-      serializerManager, taskContext, recordComparator, prefixComparator, initialSize,
+      serializerManager, taskContext, recordComparator, prefixComparator, initialSize, numElementsForSpillThreshold,
         pageSizeBytes, inMemorySorter, false /* ignored */);
     sorter.spill(Long.MAX_VALUE, sorter);
     // The external sorter will be used to insert records, in-memory sorter is not needed.
@@ -107,9 +116,10 @@ public static UnsafeExternalSorter create(
       PrefixComparator prefixComparator,
       int initialSize,
       long pageSizeBytes,
+      long numElementsForSpillThreshold,
       boolean canUseRadixSort) {
     return new UnsafeExternalSorter(taskMemoryManager, blockManager, serializerManager,
-      taskContext, recordComparator, prefixComparator, initialSize, pageSizeBytes, null,
+      taskContext, recordComparator, prefixComparator, initialSize, pageSizeBytes, numElementsForSpillThreshold, null,
       canUseRadixSort);
   }
 
@@ -122,6 +132,7 @@ private UnsafeExternalSorter(
       PrefixComparator prefixComparator,
       int initialSize,
       long pageSizeBytes,
+      long numElementsForSpillThreshold,
       @Nullable UnsafeInMemorySorter existingInMemorySorter,
       boolean canUseRadixSort) {
     super(taskMemoryManager, pageSizeBytes, taskMemoryManager.getTungstenMemoryMode());
@@ -143,6 +154,7 @@ private UnsafeExternalSorter(
       this.inMemSorter = existingInMemorySorter;
     }
     this.peakMemoryUsedBytes = getMemoryUsage();
+    this.numElementsForSpillThreshold = numElementsForSpillThreshold;
 
     // Register a cleanup task with TaskContext to ensure that memory is guaranteed to be freed at
     // the end of the task. This is necessary to avoid memory leaks in when the downstream operator
@@ -373,6 +385,12 @@ public void insertRecord(
       Object recordBase, long recordOffset, int length, long prefix, boolean prefixIsNull)
     throws IOException {
 
+    assert(inMemSorter != null);
+    if (inMemSorter.numRecords() >= numElementsForSpillThreshold) {
+      logger.info("Spilling data because number of spilledRecords crossed the threshold " + numElementsForSpillThreshold);
+      spill();
+    }
+
     growPointerArrayIfNecessary();
     // Need 4 bytes to store the record length.
     final int required = length + 4;
@@ -384,7 +402,6 @@ public void insertRecord(
     pageCursor += 4;
     Platform.copyMemory(recordBase, recordOffset, base, pageCursor, length);
     pageCursor += length;
-    assert(inMemSorter != null);
     inMemSorter.insertRecord(recordAddress, prefix, prefixIsNull);
   }
 

core/src/test/java/org/apache/spark/util/collection/unsafe/sort/UnsafeExternalSorterSuite.java

@@ -176,6 +176,7 @@ private UnsafeExternalSorter newSorter() throws IOException {
       prefixComparator,
       /* initialSize */ 1024,
       pageSizeBytes,
+      UnsafeExternalSorter.DEFAULT_NUM_ELEMENTS_FOR_SPILL_THRESHOLD,
       shouldUseRadixSort());
   }
 
@@ -399,6 +400,7 @@ public void forcedSpillingWithoutComparator() throws Exception {
       null,
       /* initialSize */ 1024,
       pageSizeBytes,
+      UnsafeExternalSorter.DEFAULT_NUM_ELEMENTS_FOR_SPILL_THRESHOLD,
       shouldUseRadixSort());
     long[] record = new long[100];
     int recordSize = record.length * 8;
@@ -435,6 +437,7 @@ public void testPeakMemoryUsed() throws Exception {
       prefixComparator,
       1024,
       pageSizeBytes,
+      UnsafeExternalSorter.DEFAULT_NUM_ELEMENTS_FOR_SPILL_THRESHOLD,
       shouldUseRadixSort());
 
     // Peak memory should be monotonically increasing. More specifically, every time

sql/catalyst/src/main/java/org/apache/spark/sql/execution/UnsafeExternalRowSorter.java

@@ -87,6 +87,8 @@ public UnsafeExternalRowSorter(
       prefixComparator,
       /* initialSize */ 4096,
       pageSizeBytes,
+      SparkEnv.get().conf().getLong("spark.shuffle.spill.numElementsForceSpillThreshold", UnsafeExternalSorter
+          .DEFAULT_NUM_ELEMENTS_FOR_SPILL_THRESHOLD),
       canUseRadixSort
     );
   }

sql/core/src/main/java/org/apache/spark/sql/execution/UnsafeFixedWidthAggregationMap.java

@@ -29,6 +29,7 @@
 import org.apache.spark.unsafe.KVIterator;
 import org.apache.spark.unsafe.Platform;
 import org.apache.spark.unsafe.map.BytesToBytesMap;
+import org.apache.spark.util.collection.unsafe.sort.UnsafeExternalSorter;
 
 /**
  * Unsafe-based HashMap for performing aggregations where the aggregated values are fixed-width.
@@ -246,6 +247,8 @@ public UnsafeKVExternalSorter destructAndCreateExternalSorter() throws IOExcepti
       SparkEnv.get().blockManager(),
       SparkEnv.get().serializerManager(),
       map.getPageSizeBytes(),
+      SparkEnv.get().conf().getLong("spark.shuffle.spill.numElementsForceSpillThreshold", UnsafeExternalSorter
+          .DEFAULT_NUM_ELEMENTS_FOR_SPILL_THRESHOLD),
       map);
   }
 }

sql/core/src/main/java/org/apache/spark/sql/execution/UnsafeKVExternalSorter.java

@@ -54,8 +54,9 @@ public UnsafeKVExternalSorter(
       StructType valueSchema,
       BlockManager blockManager,
       SerializerManager serializerManager,
-      long pageSizeBytes) throws IOException {
-    this(keySchema, valueSchema, blockManager, serializerManager, pageSizeBytes, null);
+      long pageSizeBytes,
+      long numElementsForSpillThreshold) throws IOException {
+    this(keySchema, valueSchema, blockManager, serializerManager, pageSizeBytes, numElementsForSpillThreshold, null);
   }
 
   public UnsafeKVExternalSorter(
@@ -64,6 +65,7 @@ public UnsafeKVExternalSorter(
       BlockManager blockManager,
       SerializerManager serializerManager,
       long pageSizeBytes,
+      long numElementsForSpillThreshold,
       @Nullable BytesToBytesMap map) throws IOException {
     this.keySchema = keySchema;
     this.valueSchema = valueSchema;
@@ -88,6 +90,7 @@ public UnsafeKVExternalSorter(
         prefixComparator,
         /* initialSize */ 4096,
         pageSizeBytes,
+        numElementsForSpillThreshold,
         canUseRadixSort);
     } else {
       // The array will be used to do in-place sort, which require half of the space to be empty.
@@ -133,6 +136,7 @@ public UnsafeKVExternalSorter(
         prefixComparator,
         /* initialSize */ 4096,
         pageSizeBytes,
+        numElementsForSpillThreshold,
         inMemSorter);
 
       // reset the map, so we can re-use it to insert new records. the inMemSorter will not used

sql/core/src/main/scala/org/apache/spark/sql/execution/WindowExec.scala

@@ -345,6 +345,8 @@ case class WindowExec(
                   null,
                   1024,
                   SparkEnv.get.memoryManager.pageSizeBytes,
+                  SparkEnv.get.conf.getLong("spark.shuffle.spill.numElementsForceSpillThreshold",
+                    UnsafeExternalSorter.DEFAULT_NUM_ELEMENTS_FOR_SPILL_THRESHOLD),
                   false)
                 rows.foreach { r =>
                   sorter.insertRecord(r.getBaseObject, r.getBaseOffset, r.getSizeInBytes, 0, false)

sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/WriterContainer.scala

@@ -36,6 +36,7 @@ import org.apache.spark.sql.execution.command.CreateDataSourceTableUtils._
 import org.apache.spark.sql.internal.SQLConf
 import org.apache.spark.sql.types.{IntegerType, StringType, StructField, StructType}
 import org.apache.spark.util.{SerializableConfiguration, Utils}
+import org.apache.spark.util.collection.unsafe.sort.UnsafeExternalSorter
 
 
 /** A container for all the details required when writing to a table. */
@@ -389,7 +390,9 @@ private[sql] class DynamicPartitionWriterContainer(
       StructType.fromAttributes(dataColumns),
       SparkEnv.get.blockManager,
       SparkEnv.get.serializerManager,
-      TaskContext.get().taskMemoryManager().pageSizeBytes)
+      TaskContext.get().taskMemoryManager().pageSizeBytes,
+      SparkEnv.get.conf.getLong("spark.shuffle.spill.numElementsForceSpillThreshold",
+        UnsafeExternalSorter.DEFAULT_NUM_ELEMENTS_FOR_SPILL_THRESHOLD))
 
     while (iterator.hasNext) {
       val currentRow = iterator.next()

sql/core/src/main/scala/org/apache/spark/sql/execution/joins/CartesianProductExec.scala

@@ -49,6 +49,8 @@ class UnsafeCartesianRDD(left : RDD[UnsafeRow], right : RDD[UnsafeRow], numField
       null,
       1024,
       SparkEnv.get.memoryManager.pageSizeBytes,
+      SparkEnv.get.conf.getLong("spark.shuffle.spill.numElementsForceSpillThreshold",
+        UnsafeExternalSorter.DEFAULT_NUM_ELEMENTS_FOR_SPILL_THRESHOLD),
       false)
 
     val partition = split.asInstanceOf[CartesianPartition]

sql/core/src/main/scala/org/apache/spark/sql/execution/streaming/FileStreamSink.scala

@@ -33,6 +33,7 @@ import org.apache.spark.sql.execution.UnsafeKVExternalSorter
 import org.apache.spark.sql.execution.datasources.{FileFormat, OutputWriter, PartitioningUtils}
 import org.apache.spark.sql.types.{StringType, StructType}
 import org.apache.spark.util.SerializableConfiguration
+import org.apache.spark.util.collection.unsafe.sort.UnsafeExternalSorter
 
 object FileStreamSink {
   // The name of the subdirectory that is used to store metadata about which files are valid.
@@ -209,7 +210,9 @@ class FileStreamSinkWriter(
       StructType.fromAttributes(writeColumns),
       SparkEnv.get.blockManager,
       SparkEnv.get.serializerManager,
-      TaskContext.get().taskMemoryManager().pageSizeBytes)
+      TaskContext.get().taskMemoryManager().pageSizeBytes,
+      SparkEnv.get.conf.getLong("spark.shuffle.spill.numElementsForceSpillThreshold",
+        UnsafeExternalSorter.DEFAULT_NUM_ELEMENTS_FOR_SPILL_THRESHOLD))
 
     while (iterator.hasNext) {
       val currentRow = iterator.next()