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https://issues.apache.org/jira/browse/SPARK-35500?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17350458#comment-17350458
]
Takeshi Yamamuro commented on SPARK-35500:
------------------------------------------
Which version did you use? v3.1.0 does not exist, so v3.1.1? I tried to run the
queries in v3.1.1 to reproduce it, but it couldn't happen;
{code:java}
Welcome to
____ __
/ __/__ ___ _____/ /__
_\ \/ _ \/ _ `/ __/ '_/
/___/ .__/\_,_/_/ /_/\_\ version 3.1.1
/_/
Using Scala version 2.12.10 (Java HotSpot(TM) 64-Bit Server VM, Java 1.8.0_181)
scala> sql("create table test_code_gen(a array<int>)")
scala> sql("insert into test_code_gen values (array(1, 1))")
scala> sc.setLogLevel("debug")
// The first run
scala> sql("select * from test_code_gen").collect()
...
21/05/24 23:14:00 DEBUG GenerateSafeProjection: code for
createexternalrow(staticinvoke(class scala.collection.mutable.WrappedArray$,
ObjectType(interface scala.collection.Seq), make,
mapobjects(lambdavariable(MapObject, IntegerType, true, -1),
lambdavariable(MapObject, IntegerType, true, -1), input[0, array<int>, true],
None).array, true, false), StructField(a,ArrayType(IntegerType,true),true)):
/* 001 */ public java.lang.Object generate(Object[] references) {
/* 002 */ return new SpecificSafeProjection(references);
/* 003 */ }
/* 004 */
/* 005 */ class SpecificSafeProjection extends
org.apache.spark.sql.catalyst.expressions.codegen.BaseProjection {
/* 006 */
/* 007 */ private Object[] references;
/* 008 */ private InternalRow mutableRow;
/* 009 */ private boolean resultIsNull_0;
/* 010 */ private int value_MapObject_lambda_variable_1;
/* 011 */ private boolean isNull_MapObject_lambda_variable_1;
/* 012 */ private boolean globalIsNull_0;
/* 013 */ private java.lang.Object[] mutableStateArray_0 = new
java.lang.Object[1];
/* 014 */
...
// The second run
scala> sql("select * from test_code_gen").collect()
...
21/05/24 23:14:28 DEBUG GenerateSafeProjection: code for
createexternalrow(staticinvoke(class scala.collection.mutable.WrappedArray$,
ObjectType(interface scala.collection.Seq), make,
mapobjects(lambdavariable(MapObject, IntegerType, true, -1),
lambdavariable(MapObject, IntegerType, true, -1), input[0, array<int>, true],
None).array, true, false), StructField(a,ArrayType(IntegerType,true),true)):
/* 001 */ public java.lang.Object generate(Object[] references) {
/* 002 */ return new SpecificSafeProjection(references);
/* 003 */ }
/* 004 */
/* 005 */ class SpecificSafeProjection extends
org.apache.spark.sql.catalyst.expressions.codegen.BaseProjection {
/* 006 */
/* 007 */ private Object[] references;
/* 008 */ private InternalRow mutableRow;
/* 009 */ private boolean resultIsNull_0;
/* 010 */ private int value_MapObject_lambda_variable_1;
/* 011 */ private boolean isNull_MapObject_lambda_variable_1;
/* 012 */ private boolean globalIsNull_0;
/* 013 */ private java.lang.Object[] mutableStateArray_0 = new
java.lang.Object[1];
...
{code}
Actually, this issue should be fixed in
SPARK-27871([https://github.com/apache/spark/pull/24735]). Or, do I miss
something?
> GenerateSafeProjection.generate will generate SpecificSafeProjection class,
> but if column is array type or map type, the code cannot be reused which
> impact the query performance
> ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
>
> Key: SPARK-35500
> URL: https://issues.apache.org/jira/browse/SPARK-35500
> Project: Spark
> Issue Type: Improvement
> Components: SQL
> Affects Versions: 3.1.0
> Reporter: Yahui Liu
> Priority: Minor
> Labels: codegen
>
> Reproduce steps:
> # create a new table with array type: create table test_code_gen(a
> array<int>);
> # Add
> log4j.logger.org.apache.spark.sql.catalyst.expressions.codegen.CodeGenerator
> = DEBUG to log4j.properties;
> # Enter spark-shell, fire a query: spark.sql("select * from
> test_code_gen").collect
> # Everytime, Dataset.collect is called, SpecificSafeProjection class is
> generated, but the code for the class cannot be reused because everytime the
> id for two variables in the generated class is changed: MapObjects_loopValue
> and MapObjects_loopIsNull. So even the class generated before has been
> cached, new code cannot match the cache key so that new code need to be
> compiled again which cost some time. The time cost for compile is increasing
> with the growth of column number, for wide table, this cost can more than 2s.
> {code:java}
> object MapObjects {
> private val curId = new java.util.concurrent.atomic.AtomicInteger()
> val id = curId.getAndIncrement()
> val loopValue = s"MapObjects_loopValue$id"
> val loopIsNull = if (elementNullable) {
> s"MapObjects_loopIsNull$id"
> } else {
> "false"
> }
> {code}
> First time run:
> {code:java}
> class SpecificSafeProjection extends
> org.apache.spark.sql.catalyst.expressions.codegen.BaseProjection {
> private int MapObjects_loopValue1;
> private boolean MapObjects_loopIsNull1;
> private UTF8String MapObjects_loopValue2;
> private boolean MapObjects_loopIsNull2;
> }
> {code}
> Second time run:
> {code:java}
> class SpecificSafeProjection extends
> org.apache.spark.sql.catalyst.expressions.codegen.BaseProjection {
> private int MapObjects_loopValue3;
> private boolean MapObjects_loopIsNull3;
> private UTF8String MapObjects_loopValue4;
> private boolean MapObjects_loopIsNull4;
> }{code}
> Expectation:
> The code generated by GenerateSafeProjection can be reused if the query is
> same.
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