[SPARK-10155] [SQL] Change SqlParser to object to avoid memory leak

Since `scala.util.parsing.combinator.Parsers` is thread-safe since Scala 2.10 (See [SI-4929](https://issues.scala-lang.org/browse/SI-4929)), we can change SqlParser to object to avoid memory leak.

I didn't change other subclasses of `scala.util.parsing.combinator.Parsers` because there is only one instance in one SQLContext, which should not be an issue.

Author: zsxwing <zsxwing@gmail.com>

Closes #8357 from zsxwing/sql-memory-leak.

9 files changed, 19 insertions, 19 deletions

diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/AbstractSparkSQLParser.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/AbstractSparkSQLParser.scala
index 5898a5f93f..2bac08eac4 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/AbstractSparkSQLParser.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/AbstractSparkSQLParser.scala
@@ -28,7 +28,7 @@ import org.apache.spark.sql.catalyst.plans.logical._
 private[sql] abstract class AbstractSparkSQLParser
   extends StandardTokenParsers with PackratParsers {
 
-  def parse(input: String): LogicalPlan = {
+  def parse(input: String): LogicalPlan = synchronized {
     // Initialize the Keywords.
     initLexical
     phrase(start)(new lexical.Scanner(input)) match {
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/ParserDialect.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/ParserDialect.scala
index 554fb4eb25..e21d3c0546 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/ParserDialect.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/ParserDialect.scala
@@ -61,7 +61,7 @@ abstract class ParserDialect {
  */
 private[spark] class DefaultParserDialect extends ParserDialect {
   @transient
-  protected val sqlParser = new SqlParser
+  protected val sqlParser = SqlParser
 
   override def parse(sqlText: String): LogicalPlan = {
     sqlParser.parse(sqlText)
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/SqlParser.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/SqlParser.scala
index f2498861c9..dfab239885 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/SqlParser.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/SqlParser.scala
@@ -37,9 +37,9 @@ import org.apache.spark.unsafe.types.CalendarInterval
  * This is currently included mostly for illustrative purposes.  Users wanting more complete support
  * for a SQL like language should checkout the HiveQL support in the sql/hive sub-project.
  */
-class SqlParser extends AbstractSparkSQLParser with DataTypeParser {
+object SqlParser extends AbstractSparkSQLParser with DataTypeParser {
 
-  def parseExpression(input: String): Expression = {
+  def parseExpression(input: String): Expression = synchronized {
     // Initialize the Keywords.
     initLexical
     phrase(projection)(new lexical.Scanner(input)) match {
@@ -48,7 +48,7 @@ class SqlParser extends AbstractSparkSQLParser with DataTypeParser {
     }
   }
 
-  def parseTableIdentifier(input: String): TableIdentifier = {
+  def parseTableIdentifier(input: String): TableIdentifier = synchronized {
     // Initialize the Keywords.
     initLexical
     phrase(tableIdentifier)(new lexical.Scanner(input)) match {
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/DataFrame.scala b/sql/core/src/main/scala/org/apache/spark/sql/DataFrame.scala
index 3e61123c14..8f737c2023 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/DataFrame.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/DataFrame.scala
@@ -720,7 +720,7 @@ class DataFrame private[sql](
   @scala.annotation.varargs
   def selectExpr(exprs: String*): DataFrame = {
     select(exprs.map { expr =>
-      Column(new SqlParser().parseExpression(expr))
+      Column(SqlParser.parseExpression(expr))
     }: _*)
   }
 
@@ -745,7 +745,7 @@ class DataFrame private[sql](
    * @since 1.3.0
    */
   def filter(conditionExpr: String): DataFrame = {
-    filter(Column(new SqlParser().parseExpression(conditionExpr)))
+    filter(Column(SqlParser.parseExpression(conditionExpr)))
   }
 
   /**
@@ -769,7 +769,7 @@ class DataFrame private[sql](
    * @since 1.5.0
    */
   def where(conditionExpr: String): DataFrame = {
-    filter(Column(new SqlParser().parseExpression(conditionExpr)))
+    filter(Column(SqlParser.parseExpression(conditionExpr)))
   }
 
   /**
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/DataFrameWriter.scala b/sql/core/src/main/scala/org/apache/spark/sql/DataFrameWriter.scala
index 745bb4ec9c..03e973666e 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/DataFrameWriter.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/DataFrameWriter.scala
@@ -163,7 +163,7 @@ final class DataFrameWriter private[sql](df: DataFrame) {
    * @since 1.4.0
    */
   def insertInto(tableName: String): Unit = {
-    insertInto(new SqlParser().parseTableIdentifier(tableName))
+    insertInto(SqlParser.parseTableIdentifier(tableName))
   }
 
   private def insertInto(tableIdent: TableIdentifier): Unit = {
@@ -197,7 +197,7 @@ final class DataFrameWriter private[sql](df: DataFrame) {
    * @since 1.4.0
    */
   def saveAsTable(tableName: String): Unit = {
-    saveAsTable(new SqlParser().parseTableIdentifier(tableName))
+    saveAsTable(SqlParser.parseTableIdentifier(tableName))
   }
 
   private def saveAsTable(tableIdent: TableIdentifier): Unit = {
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/SQLContext.scala b/sql/core/src/main/scala/org/apache/spark/sql/SQLContext.scala
index e3fdd782e6..f099940800 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/SQLContext.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/SQLContext.scala
@@ -590,7 +590,7 @@ class SQLContext(@transient val sparkContext: SparkContext)
       tableName: String,
       source: String,
       options: Map[String, String]): DataFrame = {
-    val tableIdent = new SqlParser().parseTableIdentifier(tableName)
+    val tableIdent = SqlParser.parseTableIdentifier(tableName)
     val cmd =
       CreateTableUsing(
         tableIdent,
@@ -636,7 +636,7 @@ class SQLContext(@transient val sparkContext: SparkContext)
       source: String,
       schema: StructType,
       options: Map[String, String]): DataFrame = {
-    val tableIdent = new SqlParser().parseTableIdentifier(tableName)
+    val tableIdent = SqlParser.parseTableIdentifier(tableName)
     val cmd =
       CreateTableUsing(
         tableIdent,
@@ -732,7 +732,7 @@ class SQLContext(@transient val sparkContext: SparkContext)
    * @since 1.3.0
    */
   def table(tableName: String): DataFrame = {
-    table(new SqlParser().parseTableIdentifier(tableName))
+    table(SqlParser.parseTableIdentifier(tableName))
   }
 
   private def table(tableIdent: TableIdentifier): DataFrame = {
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/functions.scala b/sql/core/src/main/scala/org/apache/spark/sql/functions.scala
index 60d9c50910..2467b4e484 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/functions.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/functions.scala
@@ -823,7 +823,7 @@ object functions {
    *
    * @group normal_funcs
    */
-  def expr(expr: String): Column = Column(new SqlParser().parseExpression(expr))
+  def expr(expr: String): Column = Column(SqlParser.parseExpression(expr))
 
   //////////////////////////////////////////////////////////////////////////////////////////////
   // Math Functions
diff --git a/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveContext.scala b/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveContext.scala
index d37ba5ddc2..c12a734863 100644
--- a/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveContext.scala
+++ b/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveContext.scala
@@ -291,12 +291,12 @@ class HiveContext(sc: SparkContext) extends SQLContext(sc) with Logging {
    * @since 1.3.0
    */
   def refreshTable(tableName: String): Unit = {
-    val tableIdent = new SqlParser().parseTableIdentifier(tableName)
+    val tableIdent = SqlParser.parseTableIdentifier(tableName)
     catalog.refreshTable(tableIdent)
   }
 
   protected[hive] def invalidateTable(tableName: String): Unit = {
-    val tableIdent = new SqlParser().parseTableIdentifier(tableName)
+    val tableIdent = SqlParser.parseTableIdentifier(tableName)
     catalog.invalidateTable(tableIdent)
   }
 
@@ -311,7 +311,7 @@ class HiveContext(sc: SparkContext) extends SQLContext(sc) with Logging {
    */
   @Experimental
   def analyze(tableName: String) {
-    val tableIdent = new SqlParser().parseTableIdentifier(tableName)
+    val tableIdent = SqlParser.parseTableIdentifier(tableName)
     val relation = EliminateSubQueries(catalog.lookupRelation(tableIdent.toSeq))
 
     relation match {
diff --git a/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveMetastoreCatalog.scala b/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveMetastoreCatalog.scala
index 0a5569b0a4..0c1b41e337 100644
--- a/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveMetastoreCatalog.scala
+++ b/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveMetastoreCatalog.scala
@@ -199,7 +199,7 @@ private[hive] class HiveMetastoreCatalog(val client: ClientInterface, hive: Hive
       options: Map[String, String],
       isExternal: Boolean): Unit = {
     createDataSourceTable(
-      new SqlParser().parseTableIdentifier(tableName),
+      SqlParser.parseTableIdentifier(tableName),
       userSpecifiedSchema,
       partitionColumns,
       provider,
@@ -375,7 +375,7 @@ private[hive] class HiveMetastoreCatalog(val client: ClientInterface, hive: Hive
   }
 
   def hiveDefaultTableFilePath(tableName: String): String = {
-    hiveDefaultTableFilePath(new SqlParser().parseTableIdentifier(tableName))
+    hiveDefaultTableFilePath(SqlParser.parseTableIdentifier(tableName))
   }
 
   def hiveDefaultTableFilePath(tableIdent: TableIdentifier): String = {