[SPARK-20254] SPARK-19716 generates unnecessary data conversion for Dataset with primitive array

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.2.0
• Fix Version/s: 2.2.0
• Component/s: SQL
• Assignee: Kazuaki Ishizaki
• Reporter: Kazuaki Ishizaki
• Created: 07/Apr/17 16:02
• Updated: 29/Jan/18 06:23
• Resolved: 19/Apr/17 02:59

Description

Since unresolvedmapobjects is newly introduced by SPARK-19716, the current implementation generates mapobjects() at DeserializeToObject in Analyzed Logical Plan. This mapObject() introduces Java code to store an array into GenericArrayData.
cc: cloud_fan

val ds = sparkContext.parallelize(Seq(Array(1.1, 2.2)), 1).toDS.cache
ds.count
val ds2 = ds.map(e => e)
ds2.explain(true)
ds2.show

Plans before SPARK-19716

== Parsed Logical Plan ==
'SerializeFromObject [staticinvoke(class org.apache.spark.sql.catalyst.expressions.UnsafeArrayData, ArrayType(DoubleType,false), fromPrimitiveArray, input[0, [D, true], true) AS value#25]
+- 'MapElements <function1>, class [D, [StructField(value,ArrayType(DoubleType,false),true)], obj#24: [D
   +- 'DeserializeToObject unresolveddeserializer(upcast(getcolumnbyordinal(0, ArrayType(DoubleType,false)), ArrayType(DoubleType,false), - root class: "scala.Array").toDoubleArray), obj#23: [D
      +- SerializeFromObject [staticinvoke(class org.apache.spark.sql.catalyst.expressions.UnsafeArrayData, ArrayType(DoubleType,false), fromPrimitiveArray, input[0, [D, true], true) AS value#2]
         +- ExternalRDD [obj#1]

== Analyzed Logical Plan ==
value: array<double>
SerializeFromObject [staticinvoke(class org.apache.spark.sql.catalyst.expressions.UnsafeArrayData, ArrayType(DoubleType,false), fromPrimitiveArray, input[0, [D, true], true) AS value#25]
+- MapElements <function1>, class [D, [StructField(value,ArrayType(DoubleType,false),true)], obj#24: [D
   +- DeserializeToObject cast(value#2 as array<double>).toDoubleArray, obj#23: [D
      +- SerializeFromObject [staticinvoke(class org.apache.spark.sql.catalyst.expressions.UnsafeArrayData, ArrayType(DoubleType,false), fromPrimitiveArray, input[0, [D, true], true) AS value#2]
         +- ExternalRDD [obj#1]

== Optimized Logical Plan ==
SerializeFromObject [staticinvoke(class org.apache.spark.sql.catalyst.expressions.UnsafeArrayData, ArrayType(DoubleType,false), fromPrimitiveArray, input[0, [D, true], true) AS value#25]
+- MapElements <function1>, class [D, [StructField(value,ArrayType(DoubleType,false),true)], obj#24: [D
   +- DeserializeToObject value#2.toDoubleArray, obj#23: [D
      +- InMemoryRelation [value#2], true, 10000, StorageLevel(disk, memory, deserialized, 1 replicas)
            +- *SerializeFromObject [staticinvoke(class org.apache.spark.sql.catalyst.expressions.UnsafeArrayData, ArrayType(DoubleType,false), fromPrimitiveArray, input[0, [D, true], true) AS value#2]
               +- Scan ExternalRDDScan[obj#1]

== Physical Plan ==
*SerializeFromObject [staticinvoke(class org.apache.spark.sql.catalyst.expressions.UnsafeArrayData, ArrayType(DoubleType,false), fromPrimitiveArray, input[0, [D, true], true) AS value#25]
+- *MapElements <function1>, obj#24: [D
   +- *DeserializeToObject value#2.toDoubleArray, obj#23: [D
      +- *InMemoryTableScan [value#2]
            +- InMemoryRelation [value#2], true, 10000, StorageLevel(disk, memory, deserialized, 1 replicas)
                  +- *SerializeFromObject [staticinvoke(class org.apache.spark.sql.catalyst.expressions.UnsafeArrayData, ArrayType(DoubleType,false), fromPrimitiveArray, input[0, [D, true], true) AS value#2]
                     +- Scan ExternalRDDScan[obj#1]

Plans after SPARK-19716

== Parsed Logical Plan ==
'SerializeFromObject [staticinvoke(class org.apache.spark.sql.catalyst.expressions.UnsafeArrayData, ArrayType(DoubleType,false), fromPrimitiveArray, input[0, [D, true], true) AS value#25]
+- 'MapElements <function1>, class [D, [StructField(value,ArrayType(DoubleType,false),true)], obj#24: [D
   +- 'DeserializeToObject unresolveddeserializer(unresolvedmapobjects(<function1>, getcolumnbyordinal(0, ArrayType(DoubleType,false)), None).toDoubleArray), obj#23: [D
      +- SerializeFromObject [staticinvoke(class org.apache.spark.sql.catalyst.expressions.UnsafeArrayData, ArrayType(DoubleType,false), fromPrimitiveArray, input[0, [D, true], true) AS value#2]
         +- ExternalRDD [obj#1]

== Analyzed Logical Plan ==
value: array<double>
SerializeFromObject [staticinvoke(class org.apache.spark.sql.catalyst.expressions.UnsafeArrayData, ArrayType(DoubleType,false), fromPrimitiveArray, input[0, [D, true], true) AS value#25]
+- MapElements <function1>, class [D, [StructField(value,ArrayType(DoubleType,false),true)], obj#24: [D
   +- DeserializeToObject mapobjects(MapObjects_loopValue4, MapObjects_loopIsNull4, DoubleType, assertnotnull(lambdavariable(MapObjects_loopValue4, MapObjects_loopIsNull4, DoubleType, true), - array element class: "scala.Double", - root class: "scala.Array"), value#2, None, MapObjects_builderValue4).toDoubleArray, obj#23: [D
      +- SerializeFromObject [staticinvoke(class org.apache.spark.sql.catalyst.expressions.UnsafeArrayData, ArrayType(DoubleType,false), fromPrimitiveArray, input[0, [D, true], true) AS value#2]
         +- ExternalRDD [obj#1]

== Optimized Logical Plan ==
SerializeFromObject [staticinvoke(class org.apache.spark.sql.catalyst.expressions.UnsafeArrayData, ArrayType(DoubleType,false), fromPrimitiveArray, input[0, [D, true], true) AS value#25]
+- MapElements <function1>, class [D, [StructField(value,ArrayType(DoubleType,false),true)], obj#24: [D
   +- DeserializeToObject mapobjects(MapObjects_loopValue4, MapObjects_loopIsNull4, DoubleType, assertnotnull(lambdavariable(MapObjects_loopValue4, MapObjects_loopIsNull4, DoubleType, true), - array element class: "scala.Double", - root class: "scala.Array"), value#2, None, MapObjects_builderValue4).toDoubleArray, obj#23: [D
      +- InMemoryRelation [value#2], true, 10000, StorageLevel(disk, memory, deserialized, 1 replicas)
            +- *SerializeFromObject [staticinvoke(class org.apache.spark.sql.catalyst.expressions.UnsafeArrayData, ArrayType(DoubleType,false), fromPrimitiveArray, input[0, [D, true], true) AS value#2]
               +- Scan ExternalRDDScan[obj#1]

== Physical Plan ==
*SerializeFromObject [staticinvoke(class org.apache.spark.sql.catalyst.expressions.UnsafeArrayData, ArrayType(DoubleType,false), fromPrimitiveArray, input[0, [D, true], true) AS value#25]
+- *MapElements <function1>, obj#24: [D
   +- *DeserializeToObject mapobjects(MapObjects_loopValue4, MapObjects_loopIsNull4, DoubleType, assertnotnull(lambdavariable(MapObjects_loopValue4, MapObjects_loopIsNull4, DoubleType, true), - array element class: "scala.Double", - root class: "scala.Array"), value#2, None, MapObjects_builderValue4).toDoubleArray, obj#23: [D
      +- InMemoryTableScan [value#2]
            +- InMemoryRelation [value#2], true, 10000, StorageLevel(disk, memory, deserialized, 1 replicas)
                  +- *SerializeFromObject [staticinvoke(class org.apache.spark.sql.catalyst.expressions.UnsafeArrayData, ArrayType(DoubleType,false), fromPrimitiveArray, input[0, [D, true], true) AS value#2]
                     +- Scan ExternalRDDScan[obj#1]
{{java}}

{{java}}
...
/* 056 */       ArrayData deserializetoobject_value1 = null;
/* 057 */
/* 058 */       if (!inputadapter_isNull) {
/* 059 */         int deserializetoobject_dataLength = inputadapter_value.numElements();
/* 060 */
/* 061 */         Double[] deserializetoobject_convertedArray = null;
/* 062 */         deserializetoobject_convertedArray = new Double[deserializetoobject_dataLength];
/* 063 */
/* 064 */         int deserializetoobject_loopIndex = 0;
/* 065 */         while (deserializetoobject_loopIndex < deserializetoobject_dataLength) {
/* 066 */           MapObjects_loopValue2 = (double) (inputadapter_value.getDouble(deserializetoobject_loopIndex));
/* 067 */           MapObjects_loopIsNull2 = inputadapter_value.isNullAt(deserializetoobject_loopIndex);
/* 068 */
/* 069 */           if (MapObjects_loopIsNull2) {
/* 070 */             throw new RuntimeException(((java.lang.String) references[0]));
/* 071 */           }
/* 072 */           if (false) {
/* 073 */             deserializetoobject_convertedArray[deserializetoobject_loopIndex] = null;
/* 074 */           } else {
/* 075 */             deserializetoobject_convertedArray[deserializetoobject_loopIndex] = MapObjects_loopValue2;
/* 076 */           }
/* 077 */
/* 078 */           deserializetoobject_loopIndex += 1;
/* 079 */         }
/* 080 */
/* 081 */         deserializetoobject_value1 = new org.apache.spark.sql.catalyst.util.GenericArrayData(deserializetoobject_convertedArray); /*###*/
/* 082 */       }
...

Issue Links

• links to: [Github] Pull Request #17568 (kiszk)
• links to: [Github] Pull Request #17569 (kiszk)