spark SparkSession 源码
spark SparkSession 代码
文件路径：/sql/core/src/main/scala/org/apache/spark/sql/SparkSession.scala
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* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
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* See the License for the specific language governing permissions and
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package org.apache.spark.sql
import java.io.Closeable
import java.util.{ServiceLoader, UUID}
import java.util.concurrent.TimeUnit._
import java.util.concurrent.atomic.{AtomicBoolean, AtomicReference}
import scala.collection.JavaConverters._
import scala.reflect.runtime.universe.TypeTag
import scala.util.control.NonFatal
import org.apache.spark.{SPARK_VERSION, SparkConf, SparkContext, TaskContext}
import org.apache.spark.annotation.{DeveloperApi, Experimental, Stable, Unstable}
import org.apache.spark.api.java.JavaRDD
import org.apache.spark.internal.Logging
import org.apache.spark.internal.config.{ConfigEntry, EXECUTOR_ALLOW_SPARK_CONTEXT}
import org.apache.spark.rdd.RDD
import org.apache.spark.scheduler.{SparkListener, SparkListenerApplicationEnd}
import org.apache.spark.sql.catalog.Catalog
import org.apache.spark.sql.catalyst._
import org.apache.spark.sql.catalyst.analysis.UnresolvedRelation
import org.apache.spark.sql.catalyst.encoders._
import org.apache.spark.sql.catalyst.expressions.AttributeReference
import org.apache.spark.sql.catalyst.plans.logical.{LocalRelation, Range}
import org.apache.spark.sql.catalyst.util.CharVarcharUtils
import org.apache.spark.sql.connector.ExternalCommandRunner
import org.apache.spark.sql.errors.QueryCompilationErrors
import org.apache.spark.sql.execution._
import org.apache.spark.sql.execution.command.ExternalCommandExecutor
import org.apache.spark.sql.execution.datasources.{DataSource, LogicalRelation}
import org.apache.spark.sql.internal._
import org.apache.spark.sql.internal.StaticSQLConf.CATALOG_IMPLEMENTATION
import org.apache.spark.sql.sources.BaseRelation
import org.apache.spark.sql.streaming._
import org.apache.spark.sql.types.{DataType, StructType}
import org.apache.spark.sql.util.ExecutionListenerManager
import org.apache.spark.util.{CallSite, Utils}
/**
* The entry point to programming Spark with the Dataset and DataFrame API.
*
* In environments that this has been created upfront (e.g. REPL, notebooks), use the builder
* to get an existing session:
*
* {{{
* SparkSession.builder().getOrCreate()
* }}}
*
* The builder can also be used to create a new session:
*
* {{{
* SparkSession.builder
* .master("local")
* .appName("Word Count")
* .config("spark.some.config.option", "some-value")
* .getOrCreate()
* }}}
*
* @param sparkContext The Spark context associated with this Spark session.
* @param existingSharedState If supplied, use the existing shared state
* instead of creating a new one.
* @param parentSessionState If supplied, inherit all session state (i.e. temporary
* views, SQL config, UDFs etc) from parent.
*/
@Stable
class SparkSession private(
@transient val sparkContext: SparkContext,
@transient private val existingSharedState: Option[SharedState],
@transient private val parentSessionState: Option[SessionState],
@transient private[sql] val extensions: SparkSessionExtensions,
@transient private[sql] val initialSessionOptions: Map[String, String])
extends Serializable with Closeable with Logging { self =>
// The call site where this SparkSession was constructed.
private val creationSite: CallSite = Utils.getCallSite()
/**
* Constructor used in Pyspark. Contains explicit application of Spark Session Extensions
* which otherwise only occurs during getOrCreate. We cannot add this to the default constructor
* since that would cause every new session to reinvoke Spark Session Extensions on the currently
* running extensions.
*/
private[sql] def this(
sc: SparkContext,
initialSessionOptions: java.util.HashMap[String, String]) = {
this(sc, None, None,
SparkSession.applyExtensions(
sc.getConf.get(StaticSQLConf.SPARK_SESSION_EXTENSIONS).getOrElse(Seq.empty),
new SparkSessionExtensions), initialSessionOptions.asScala.toMap)
}
private[sql] def this(sc: SparkContext) = this(sc, new java.util.HashMap[String, String]())
private[sql] val sessionUUID: String = UUID.randomUUID.toString
sparkContext.assertNotStopped()
// If there is no active SparkSession, uses the default SQL conf. Otherwise, use the session's.
SQLConf.setSQLConfGetter(() => {
SparkSession.getActiveSession.filterNot(_.sparkContext.isStopped).map(_.sessionState.conf)
.getOrElse(SQLConf.getFallbackConf)
})
/**
* The version of Spark on which this application is running.
*
* @since 2.0.0
*/
def version: String = SPARK_VERSION
/* ----------------------- *
| Session-related state |
* ----------------------- */
/**
* State shared across sessions, including the `SparkContext`, cached data, listener,
* and a catalog that interacts with external systems.
*
* This is internal to Spark and there is no guarantee on interface stability.
*
* @since 2.2.0
*/
@Unstable
@transient
lazy val sharedState: SharedState = {
existingSharedState.getOrElse(new SharedState(sparkContext, initialSessionOptions))
}
/**
* State isolated across sessions, including SQL configurations, temporary tables, registered
* functions, and everything else that accepts a [[org.apache.spark.sql.internal.SQLConf]].
* If `parentSessionState` is not null, the `SessionState` will be a copy of the parent.
*
* This is internal to Spark and there is no guarantee on interface stability.
*
* @since 2.2.0
*/
@Unstable
@transient
lazy val sessionState: SessionState = {
parentSessionState
.map(_.clone(this))
.getOrElse {
val state = SparkSession.instantiateSessionState(
SparkSession.sessionStateClassName(sharedState.conf),
self)
state
}
}
/**
* A wrapped version of this session in the form of a [[SQLContext]], for backward compatibility.
*
* @since 2.0.0
*/
@transient
val sqlContext: SQLContext = new SQLContext(this)
/**
* Runtime configuration interface for Spark.
*
* This is the interface through which the user can get and set all Spark and Hadoop
* configurations that are relevant to Spark SQL. When getting the value of a config,
* this defaults to the value set in the underlying `SparkContext`, if any.
*
* @since 2.0.0
*/
@transient lazy val conf: RuntimeConfig = new RuntimeConfig(sessionState.conf)
/**
* An interface to register custom [[org.apache.spark.sql.util.QueryExecutionListener]]s
* that listen for execution metrics.
*
* @since 2.0.0
*/
def listenerManager: ExecutionListenerManager = sessionState.listenerManager
/**
* :: Experimental ::
* A collection of methods that are considered experimental, but can be used to hook into
* the query planner for advanced functionality.
*
* @since 2.0.0
*/
@Experimental
@Unstable
def experimental: ExperimentalMethods = sessionState.experimentalMethods
/**
* A collection of methods for registering user-defined functions (UDF).
*
* The following example registers a Scala closure as UDF:
* {{{
* sparkSession.udf.register("myUDF", (arg1: Int, arg2: String) => arg2 + arg1)
* }}}
*
* The following example registers a UDF in Java:
* {{{
* sparkSession.udf().register("myUDF",
* (Integer arg1, String arg2) -> arg2 + arg1,
* DataTypes.StringType);
* }}}
*
* @note The user-defined functions must be deterministic. Due to optimization,
* duplicate invocations may be eliminated or the function may even be invoked more times than
* it is present in the query.
*
* @since 2.0.0
*/
def udf: UDFRegistration = sessionState.udfRegistration
/**
* Returns a `StreamingQueryManager` that allows managing all the
* `StreamingQuery`s active on `this`.
*
* @since 2.0.0
*/
@Unstable
def streams: StreamingQueryManager = sessionState.streamingQueryManager
/**
* Start a new session with isolated SQL configurations, temporary tables, registered
* functions are isolated, but sharing the underlying `SparkContext` and cached data.
*
* @note Other than the `SparkContext`, all shared state is initialized lazily.
* This method will force the initialization of the shared state to ensure that parent
* and child sessions are set up with the same shared state. If the underlying catalog
* implementation is Hive, this will initialize the metastore, which may take some time.
*
* @since 2.0.0
*/
def newSession(): SparkSession = {
new SparkSession(
sparkContext,
Some(sharedState),
parentSessionState = None,
extensions,
initialSessionOptions)
}
/**
* Create an identical copy of this `SparkSession`, sharing the underlying `SparkContext`
* and shared state. All the state of this session (i.e. SQL configurations, temporary tables,
* registered functions) is copied over, and the cloned session is set up with the same shared
* state as this session. The cloned session is independent of this session, that is, any
* non-global change in either session is not reflected in the other.
*
* @note Other than the `SparkContext`, all shared state is initialized lazily.
* This method will force the initialization of the shared state to ensure that parent
* and child sessions are set up with the same shared state. If the underlying catalog
* implementation is Hive, this will initialize the metastore, which may take some time.
*/
private[sql] def cloneSession(): SparkSession = {
val result = new SparkSession(
sparkContext,
Some(sharedState),
Some(sessionState),
extensions,
Map.empty)
result.sessionState // force copy of SessionState
result
}
/* --------------------------------- *
| Methods for creating DataFrames |
* --------------------------------- */
/**
* Returns a `DataFrame` with no rows or columns.
*
* @since 2.0.0
*/
@transient
lazy val emptyDataFrame: DataFrame = Dataset.ofRows(self, LocalRelation())
/**
* Creates a new [[Dataset]] of type T containing zero elements.
*
* @since 2.0.0
*/
def emptyDataset[T: Encoder]: Dataset[T] = {
val encoder = implicitly[Encoder[T]]
new Dataset(self, LocalRelation(encoder.schema.toAttributes), encoder)
}
/**
* Creates a `DataFrame` from an RDD of Product (e.g. case classes, tuples).
*
* @since 2.0.0
*/
def createDataFrame[A <: Product : TypeTag](rdd: RDD[A]): DataFrame = withActive {
val encoder = Encoders.product[A]
Dataset.ofRows(self, ExternalRDD(rdd, self)(encoder))
}
/**
* Creates a `DataFrame` from a local Seq of Product.
*
* @since 2.0.0
*/
def createDataFrame[A <: Product : TypeTag](data: Seq[A]): DataFrame = withActive {
val schema = ScalaReflection.schemaFor[A].dataType.asInstanceOf[StructType]
val attributeSeq = schema.toAttributes
Dataset.ofRows(self, LocalRelation.fromProduct(attributeSeq, data))
}
/**
* :: DeveloperApi ::
* Creates a `DataFrame` from an `RDD` containing [[Row]]s using the given schema.
* It is important to make sure that the structure of every [[Row]] of the provided RDD matches
* the provided schema. Otherwise, there will be runtime exception.
* Example:
* {{{
* import org.apache.spark.sql._
* import org.apache.spark.sql.types._
* val sparkSession = new org.apache.spark.sql.SparkSession(sc)
*
* val schema =
* StructType(
* StructField("name", StringType, false) ::
* StructField("age", IntegerType, true) :: Nil)
*
* val people =
* sc.textFile("examples/src/main/resources/people.txt").map(
* _.split(",")).map(p => Row(p(0), p(1).trim.toInt))
* val dataFrame = sparkSession.createDataFrame(people, schema)
* dataFrame.printSchema
* // root
* // |-- name: string (nullable = false)
* // |-- age: integer (nullable = true)
*
* dataFrame.createOrReplaceTempView("people")
* sparkSession.sql("select name from people").collect.foreach(println)
* }}}
*
* @since 2.0.0
*/
@DeveloperApi
def createDataFrame(rowRDD: RDD[Row], schema: StructType): DataFrame = withActive {
val replaced = CharVarcharUtils.failIfHasCharVarchar(schema).asInstanceOf[StructType]
// TODO: use MutableProjection when rowRDD is another DataFrame and the applied
// schema differs from the existing schema on any field data type.
val encoder = RowEncoder(replaced)
val toRow = encoder.createSerializer()
val catalystRows = rowRDD.map(toRow)
internalCreateDataFrame(catalystRows.setName(rowRDD.name), schema)
}
/**
* :: DeveloperApi ::
* Creates a `DataFrame` from a `JavaRDD` containing [[Row]]s using the given schema.
* It is important to make sure that the structure of every [[Row]] of the provided RDD matches
* the provided schema. Otherwise, there will be runtime exception.
*
* @since 2.0.0
*/
@DeveloperApi
def createDataFrame(rowRDD: JavaRDD[Row], schema: StructType): DataFrame = {
val replaced = CharVarcharUtils.failIfHasCharVarchar(schema).asInstanceOf[StructType]
createDataFrame(rowRDD.rdd, replaced)
}
/**
* :: DeveloperApi ::
* Creates a `DataFrame` from a `java.util.List` containing [[Row]]s using the given schema.
* It is important to make sure that the structure of every [[Row]] of the provided List matches
* the provided schema. Otherwise, there will be runtime exception.
*
* @since 2.0.0
*/
@DeveloperApi
def createDataFrame(rows: java.util.List[Row], schema: StructType): DataFrame = withActive {
val replaced = CharVarcharUtils.failIfHasCharVarchar(schema).asInstanceOf[StructType]
Dataset.ofRows(self, LocalRelation.fromExternalRows(replaced.toAttributes, rows.asScala.toSeq))
}
/**
* Applies a schema to an RDD of Java Beans.
*
* WARNING: Since there is no guaranteed ordering for fields in a Java Bean,
* SELECT * queries will return the columns in an undefined order.
*
* @since 2.0.0
*/
def createDataFrame(rdd: RDD[_], beanClass: Class[_]): DataFrame = withActive {
val attributeSeq: Seq[AttributeReference] = getSchema(beanClass)
val className = beanClass.getName
val rowRdd = rdd.mapPartitions { iter =>
// BeanInfo is not serializable so we must rediscover it remotely for each partition.
SQLContext.beansToRows(iter, Utils.classForName(className), attributeSeq)
}
Dataset.ofRows(self, LogicalRDD(attributeSeq, rowRdd.setName(rdd.name))(self))
}
/**
* Applies a schema to an RDD of Java Beans.
*
* WARNING: Since there is no guaranteed ordering for fields in a Java Bean,
* SELECT * queries will return the columns in an undefined order.
*
* @since 2.0.0
*/
def createDataFrame(rdd: JavaRDD[_], beanClass: Class[_]): DataFrame = {
createDataFrame(rdd.rdd, beanClass)
}
/**
* Applies a schema to a List of Java Beans.
*
* WARNING: Since there is no guaranteed ordering for fields in a Java Bean,
* SELECT * queries will return the columns in an undefined order.
* @since 1.6.0
*/
def createDataFrame(data: java.util.List[_], beanClass: Class[_]): DataFrame = withActive {
val attrSeq = getSchema(beanClass)
val rows = SQLContext.beansToRows(data.asScala.iterator, beanClass, attrSeq)
Dataset.ofRows(self, LocalRelation(attrSeq, rows.toSeq))
}
/**
* Convert a `BaseRelation` created for external data sources into a `DataFrame`.
*
* @since 2.0.0
*/
def baseRelationToDataFrame(baseRelation: BaseRelation): DataFrame = {
Dataset.ofRows(self, LogicalRelation(baseRelation))
}
/* ------------------------------- *
| Methods for creating DataSets |
* ------------------------------- */
/**
* Creates a [[Dataset]] from a local Seq of data of a given type. This method requires an
* encoder (to convert a JVM object of type `T` to and from the internal Spark SQL representation)
* that is generally created automatically through implicits from a `SparkSession`, or can be
* created explicitly by calling static methods on [[Encoders]].
*
* == Example ==
*
* {{{
*
* import spark.implicits._
* case class Person(name: String, age: Long)
* val data = Seq(Person("Michael", 29), Person("Andy", 30), Person("Justin", 19))
* val ds = spark.createDataset(data)
*
* ds.show()
* // +-------+---+
* // | name|age|
* // +-------+---+
* // |Michael| 29|
* // | Andy| 30|
* // | Justin| 19|
* // +-------+---+
* }}}
*
* @since 2.0.0
*/
def createDataset[T : Encoder](data: Seq[T]): Dataset[T] = {
val enc = encoderFor[T]
val toRow = enc.createSerializer()
val attributes = enc.schema.toAttributes
val encoded = data.map(d => toRow(d).copy())
val plan = new LocalRelation(attributes, encoded)
Dataset[T](self, plan)
}
/**
* Creates a [[Dataset]] from an RDD of a given type. This method requires an
* encoder (to convert a JVM object of type `T` to and from the internal Spark SQL representation)
* that is generally created automatically through implicits from a `SparkSession`, or can be
* created explicitly by calling static methods on [[Encoders]].
*
* @since 2.0.0
*/
def createDataset[T : Encoder](data: RDD[T]): Dataset[T] = {
Dataset[T](self, ExternalRDD(data, self))
}
/**
* Creates a [[Dataset]] from a `java.util.List` of a given type. This method requires an
* encoder (to convert a JVM object of type `T` to and from the internal Spark SQL representation)
* that is generally created automatically through implicits from a `SparkSession`, or can be
* created explicitly by calling static methods on [[Encoders]].
*
* == Java Example ==
*
* {{{
* List<String> data = Arrays.asList("hello", "world");
* Dataset<String> ds = spark.createDataset(data, Encoders.STRING());
* }}}
*
* @since 2.0.0
*/
def createDataset[T : Encoder](data: java.util.List[T]): Dataset[T] = {
createDataset(data.asScala.toSeq)
}
/**
* Creates a [[Dataset]] with a single `LongType` column named `id`, containing elements
* in a range from 0 to `end` (exclusive) with step value 1.
*
* @since 2.0.0
*/
def range(end: Long): Dataset[java.lang.Long] = range(0, end)
/**
* Creates a [[Dataset]] with a single `LongType` column named `id`, containing elements
* in a range from `start` to `end` (exclusive) with step value 1.
*
* @since 2.0.0
*/
def range(start: Long, end: Long): Dataset[java.lang.Long] = {
range(start, end, step = 1, numPartitions = leafNodeDefaultParallelism)
}
/**
* Creates a [[Dataset]] with a single `LongType` column named `id`, containing elements
* in a range from `start` to `end` (exclusive) with a step value.
*
* @since 2.0.0
*/
def range(start: Long, end: Long, step: Long): Dataset[java.lang.Long] = {
range(start, end, step, numPartitions = leafNodeDefaultParallelism)
}
/**
* Creates a [[Dataset]] with a single `LongType` column named `id`, containing elements
* in a range from `start` to `end` (exclusive) with a step value, with partition number
* specified.
*
* @since 2.0.0
*/
def range(start: Long, end: Long, step: Long, numPartitions: Int): Dataset[java.lang.Long] = {
new Dataset(self, Range(start, end, step, numPartitions), Encoders.LONG)
}
/**
* Creates a `DataFrame` from an `RDD[InternalRow]`.
*/
private[sql] def internalCreateDataFrame(
catalystRows: RDD[InternalRow],
schema: StructType,
isStreaming: Boolean = false): DataFrame = {
// TODO: use MutableProjection when rowRDD is another DataFrame and the applied
// schema differs from the existing schema on any field data type.
val logicalPlan = LogicalRDD(
schema.toAttributes,
catalystRows,
isStreaming = isStreaming)(self)
Dataset.ofRows(self, logicalPlan)
}
/* ------------------------- *
| Catalog-related methods |
* ------------------------- */
/**
* Interface through which the user may create, drop, alter or query underlying
* databases, tables, functions etc.
*
* @since 2.0.0
*/
@transient lazy val catalog: Catalog = new CatalogImpl(self)
/**
* Returns the specified table/view as a `DataFrame`. If it's a table, it must support batch
* reading and the returned DataFrame is the batch scan query plan of this table. If it's a view,
* the returned DataFrame is simply the query plan of the view, which can either be a batch or
* streaming query plan.
*
* @param tableName is either a qualified or unqualified name that designates a table or view.
* If a database is specified, it identifies the table/view from the database.
* Otherwise, it first attempts to find a temporary view with the given name
* and then match the table/view from the current database.
* Note that, the global temporary view database is also valid here.
* @since 2.0.0
*/
def table(tableName: String): DataFrame = {
read.table(tableName)
}
private[sql] def table(tableIdent: TableIdentifier): DataFrame = {
Dataset.ofRows(self, UnresolvedRelation(tableIdent))
}
/* ----------------- *
| Everything else |
* ----------------- */
/**
* Executes a SQL query using Spark, returning the result as a `DataFrame`.
* This API eagerly runs DDL/DML commands, but not for SELECT queries.
*
* @since 2.0.0
*/
def sql(sqlText: String): DataFrame = withActive {
val tracker = new QueryPlanningTracker
val plan = tracker.measurePhase(QueryPlanningTracker.PARSING) {
sessionState.sqlParser.parsePlan(sqlText)
}
Dataset.ofRows(self, plan, tracker)
}
/**
* Execute an arbitrary string command inside an external execution engine rather than Spark.
* This could be useful when user wants to execute some commands out of Spark. For
* example, executing custom DDL/DML command for JDBC, creating index for ElasticSearch,
* creating cores for Solr and so on.
*
* The command will be eagerly executed after this method is called and the returned
* DataFrame will contain the output of the command(if any).
*
* @param runner The class name of the runner that implements `ExternalCommandRunner`.
* @param command The target command to be executed
* @param options The options for the runner.
*
* @since 3.0.0
*/
@Unstable
def executeCommand(runner: String, command: String, options: Map[String, String]): DataFrame = {
DataSource.lookupDataSource(runner, sessionState.conf) match {
case source if classOf[ExternalCommandRunner].isAssignableFrom(source) =>
Dataset.ofRows(self, ExternalCommandExecutor(
source.newInstance().asInstanceOf[ExternalCommandRunner], command, options))
case _ =>
throw QueryCompilationErrors.commandExecutionInRunnerUnsupportedError(runner)
}
}
/**
* Returns a [[DataFrameReader]] that can be used to read non-streaming data in as a
* `DataFrame`.
* {{{
* sparkSession.read.parquet("/path/to/file.parquet")
* sparkSession.read.schema(schema).json("/path/to/file.json")
* }}}
*
* @since 2.0.0
*/
def read: DataFrameReader = new DataFrameReader(self)
/**
* Returns a `DataStreamReader` that can be used to read streaming data in as a `DataFrame`.
* {{{
* sparkSession.readStream.parquet("/path/to/directory/of/parquet/files")
* sparkSession.readStream.schema(schema).json("/path/to/directory/of/json/files")
* }}}
*
* @since 2.0.0
*/
def readStream: DataStreamReader = new DataStreamReader(self)
/**
* Executes some code block and prints to stdout the time taken to execute the block. This is
* available in Scala only and is used primarily for interactive testing and debugging.
*
* @since 2.1.0
*/
def time[T](f: => T): T = {
val start = System.nanoTime()
val ret = f
val end = System.nanoTime()
// scalastyle:off println
println(s"Time taken: ${NANOSECONDS.toMillis(end - start)} ms")
// scalastyle:on println
ret
}
// scalastyle:off
// Disable style checker so "implicits" object can start with lowercase i
/**
* (Scala-specific) Implicit methods available in Scala for converting
* common Scala objects into `DataFrame`s.
*
* {{{
* val sparkSession = SparkSession.builder.getOrCreate()
* import sparkSession.implicits._
* }}}
*
* @since 2.0.0
*/
object implicits extends SQLImplicits with Serializable {
protected override def _sqlContext: SQLContext = SparkSession.this.sqlContext
}
// scalastyle:on
/**
* Stop the underlying `SparkContext`.
*
* @since 2.0.0
*/
def stop(): Unit = {
sparkContext.stop()
}
/**
* Synonym for `stop()`.
*
* @since 2.1.0
*/
override def close(): Unit = stop()
/**
* Parses the data type in our internal string representation. The data type string should
* have the same format as the one generated by `toString` in scala.
* It is only used by PySpark.
*/
protected[sql] def parseDataType(dataTypeString: String): DataType = {
DataType.fromJson(dataTypeString)
}
/**
* Apply a schema defined by the schemaString to an RDD. It is only used by PySpark.
*/
private[sql] def applySchemaToPythonRDD(
rdd: RDD[Array[Any]],
schemaString: String): DataFrame = {
val schema = DataType.fromJson(schemaString).asInstanceOf[StructType]
applySchemaToPythonRDD(rdd, schema)
}
/**
* Apply `schema` to an RDD.
*
* @note Used by PySpark only
*/
private[sql] def applySchemaToPythonRDD(
rdd: RDD[Array[Any]],
schema: StructType): DataFrame = {
val rowRdd = rdd.mapPartitions { iter =>
val fromJava = python.EvaluatePython.makeFromJava(schema)
iter.map(r => fromJava(r).asInstanceOf[InternalRow])
}
internalCreateDataFrame(rowRdd, schema)
}
/**
* Returns a Catalyst Schema for the given java bean class.
*/
private def getSchema(beanClass: Class[_]): Seq[AttributeReference] = {
val (dataType, _) = JavaTypeInference.inferDataType(beanClass)
dataType.asInstanceOf[StructType].fields.map { f =>
AttributeReference(f.name, f.dataType, f.nullable)()
}
}
/**
* Execute a block of code with the this session set as the active session, and restore the
* previous session on completion.
*/
private[sql] def withActive[T](block: => T): T = {
// Use the active session thread local directly to make sure we get the session that is actually
// set and not the default session. This to prevent that we promote the default session to the
// active session once we are done.
val old = SparkSession.activeThreadSession.get()
SparkSession.setActiveSession(this)
try block finally {
SparkSession.setActiveSession(old)
}
}
private[sql] def leafNodeDefaultParallelism: Int = {
conf.get(SQLConf.LEAF_NODE_DEFAULT_PARALLELISM).getOrElse(sparkContext.defaultParallelism)
}
}
@Stable
object SparkSession extends Logging {
/**
* Builder for [[SparkSession]].
*/
@Stable
class Builder extends Logging {
private[this] val options = new scala.collection.mutable.HashMap[String, String]
private[this] val extensions = new SparkSessionExtensions
private[this] var userSuppliedContext: Option[SparkContext] = None
private[spark] def sparkContext(sparkContext: SparkContext): Builder = synchronized {
userSuppliedContext = Option(sparkContext)
this
}
/**
* Sets a name for the application, which will be shown in the Spark web UI.
* If no application name is set, a randomly generated name will be used.
*
* @since 2.0.0
*/
def appName(name: String): Builder = config("spark.app.name", name)
/**
* Sets a config option. Options set using this method are automatically propagated to
* both `SparkConf` and SparkSession's own configuration.
*
* @since 2.0.0
*/
def config(key: String, value: String): Builder = synchronized {
options += key -> value
this
}
/**
* Sets a config option. Options set using this method are automatically propagated to
* both `SparkConf` and SparkSession's own configuration.
*
* @since 2.0.0
*/
def config(key: String, value: Long): Builder = synchronized {
options += key -> value.toString
this
}
/**
* Sets a config option. Options set using this method are automatically propagated to
* both `SparkConf` and SparkSession's own configuration.
*
* @since 2.0.0
*/
def config(key: String, value: Double): Builder = synchronized {
options += key -> value.toString
this
}
/**
* Sets a config option. Options set using this method are automatically propagated to
* both `SparkConf` and SparkSession's own configuration.
*
* @since 2.0.0
*/
def config(key: String, value: Boolean): Builder = synchronized {
options += key -> value.toString
this
}
/**
* Sets a config option. Options set using this method are automatically propagated to
* both `SparkConf` and SparkSession's own configuration.
*
* @since 3.4.0
*/
def config(map: Map[String, Any]): Builder = synchronized {
map.foreach {
kv: (String, Any) => {
options += kv._1 -> kv._2.toString
}
}
this
}
/**
* Sets a config option. Options set using this method are automatically propagated to
* both `SparkConf` and SparkSession's own configuration.
*
* @since 3.4.0
*/
def config(map: java.util.Map[String, Any]): Builder = synchronized {
config(map.asScala.toMap)
}
/**
* Sets a list of config options based on the given `SparkConf`.
*
* @since 2.0.0
*/
def config(conf: SparkConf): Builder = synchronized {
conf.getAll.foreach { case (k, v) => options += k -> v }
this
}
/**
* Sets the Spark master URL to connect to, such as "local" to run locally, "local[4]" to
* run locally with 4 cores, or "spark://master:7077" to run on a Spark standalone cluster.
*
* @since 2.0.0
*/
def master(master: String): Builder = config("spark.master", master)
/**
* Enables Hive support, including connectivity to a persistent Hive metastore, support for
* Hive serdes, and Hive user-defined functions.
*
* @since 2.0.0
*/
def enableHiveSupport(): Builder = synchronized {
if (hiveClassesArePresent) {
config(CATALOG_IMPLEMENTATION.key, "hive")
} else {
throw new IllegalArgumentException(
"Unable to instantiate SparkSession with Hive support because " +
"Hive classes are not found.")
}
}
/**
* Inject extensions into the [[SparkSession]]. This allows a user to add Analyzer rules,
* Optimizer rules, Planning Strategies or a customized parser.
*
* @since 2.2.0
*/
def withExtensions(f: SparkSessionExtensions => Unit): Builder = synchronized {
f(extensions)
this
}
/**
* Gets an existing [[SparkSession]] or, if there is no existing one, creates a new
* one based on the options set in this builder.
*
* This method first checks whether there is a valid thread-local SparkSession,
* and if yes, return that one. It then checks whether there is a valid global
* default SparkSession, and if yes, return that one. If no valid global default
* SparkSession exists, the method creates a new SparkSession and assigns the
* newly created SparkSession as the global default.
*
* In case an existing SparkSession is returned, the non-static config options specified in
* this builder will be applied to the existing SparkSession.
*
* @since 2.0.0
*/
def getOrCreate(): SparkSession = synchronized {
val sparkConf = new SparkConf()
options.foreach { case (k, v) => sparkConf.set(k, v) }
if (!sparkConf.get(EXECUTOR_ALLOW_SPARK_CONTEXT)) {
assertOnDriver()
}
// Get the session from current thread's active session.
var session = activeThreadSession.get()
if ((session ne null) && !session.sparkContext.isStopped) {
applyModifiableSettings(session, new java.util.HashMap[String, String](options.asJava))
return session
}
// Global synchronization so we will only set the default session once.
SparkSession.synchronized {
// If the current thread does not have an active session, get it from the global session.
session = defaultSession.get()
if ((session ne null) && !session.sparkContext.isStopped) {
applyModifiableSettings(session, new java.util.HashMap[String, String](options.asJava))
return session
}
// No active nor global default session. Create a new one.
val sparkContext = userSuppliedContext.getOrElse {
// set a random app name if not given.
if (!sparkConf.contains("spark.app.name")) {
sparkConf.setAppName(java.util.UUID.randomUUID().toString)
}
SparkContext.getOrCreate(sparkConf)
// Do not update `SparkConf` for existing `SparkContext`, as it's shared by all sessions.
}
loadExtensions(extensions)
applyExtensions(
sparkContext.getConf.get(StaticSQLConf.SPARK_SESSION_EXTENSIONS).getOrElse(Seq.empty),
extensions)
session = new SparkSession(sparkContext, None, None, extensions, options.toMap)
setDefaultSession(session)
setActiveSession(session)
registerContextListener(sparkContext)
}
return session
}
}
/**
* Creates a [[SparkSession.Builder]] for constructing a [[SparkSession]].
*
* @since 2.0.0
*/
def builder(): Builder = new Builder
/**
* Changes the SparkSession that will be returned in this thread and its children when
* SparkSession.getOrCreate() is called. This can be used to ensure that a given thread receives
* a SparkSession with an isolated session, instead of the global (first created) context.
*
* @since 2.0.0
*/
def setActiveSession(session: SparkSession): Unit = {
activeThreadSession.set(session)
}
/**
* Clears the active SparkSession for current thread. Subsequent calls to getOrCreate will
* return the first created context instead of a thread-local override.
*
* @since 2.0.0
*/
def clearActiveSession(): Unit = {
activeThreadSession.remove()
}
/**
* Sets the default SparkSession that is returned by the builder.
*
* @since 2.0.0
*/
def setDefaultSession(session: SparkSession): Unit = {
defaultSession.set(session)
}
/**
* Clears the default SparkSession that is returned by the builder.
*
* @since 2.0.0
*/
def clearDefaultSession(): Unit = {
defaultSession.set(null)
}
/**
* Returns the active SparkSession for the current thread, returned by the builder.
*
* @note Return None, when calling this function on executors
*
* @since 2.2.0
*/
def getActiveSession: Option[SparkSession] = {
if (Utils.isInRunningSparkTask) {
// Return None when running on executors.
None
} else {
Option(activeThreadSession.get)
}
}
/**
* Returns the default SparkSession that is returned by the builder.
*
* @note Return None, when calling this function on executors
*
* @since 2.2.0
*/
def getDefaultSession: Option[SparkSession] = {
if (Utils.isInRunningSparkTask) {
// Return None when running on executors.
None
} else {
Option(defaultSession.get)
}
}
/**
* Returns the currently active SparkSession, otherwise the default one. If there is no default
* SparkSession, throws an exception.
*
* @since 2.4.0
*/
def active: SparkSession = {
getActiveSession.getOrElse(getDefaultSession.getOrElse(
throw new IllegalStateException("No active or default Spark session found")))
}
/**
* Apply modifiable settings to an existing [[SparkSession]]. This method are used
* both in Scala and Python, so put this under [[SparkSession]] object.
*/
private[sql] def applyModifiableSettings(
session: SparkSession,
options: java.util.HashMap[String, String]): Unit = {
// Lazy val to avoid an unnecessary session state initialization
lazy val conf = session.sessionState.conf
val dedupOptions = if (options.isEmpty) Map.empty[String, String] else (
options.asScala.toSet -- conf.getAllConfs.toSet).toMap
val (staticConfs, otherConfs) =
dedupOptions.partition(kv => SQLConf.isStaticConfigKey(kv._1))
otherConfs.foreach { case (k, v) => conf.setConfString(k, v) }
// Note that other runtime SQL options, for example, for other third-party datasource
// can be marked as an ignored configuration here.
val maybeIgnoredConfs = otherConfs.filterNot { case (k, _) => conf.isModifiable(k) }
if (staticConfs.nonEmpty || maybeIgnoredConfs.nonEmpty) {
logWarning(
"Using an existing Spark session; only runtime SQL configurations will take effect.")
}
if (staticConfs.nonEmpty) {
logDebug("Ignored static SQL configurations:\n " +
conf.redactOptions(staticConfs).toSeq.map { case (k, v) => s"$k=$v" }.mkString("\n "))
}
if (maybeIgnoredConfs.nonEmpty) {
// Only print out non-static and non-runtime SQL configurations.
// Note that this might show core configurations or source specific
// options defined in the third-party datasource.
logDebug("Configurations that might not take effect:\n " +
conf.redactOptions(
maybeIgnoredConfs).toSeq.map { case (k, v) => s"$k=$v" }.mkString("\n "))
}
}
/**
* Returns a cloned SparkSession with all specified configurations disabled, or
* the original SparkSession if all configurations are already disabled.
*/
private[sql] def getOrCloneSessionWithConfigsOff(
session: SparkSession,
configurations: Seq[ConfigEntry[Boolean]]): SparkSession = {
val configsEnabled = configurations.filter(session.conf.get[Boolean])
if (configsEnabled.isEmpty) {
session
} else {
val newSession = session.cloneSession()
configsEnabled.foreach(conf => {
newSession.conf.set(conf, false)
})
newSession
}
}
////////////////////////////////////////////////////////////////////////////////////////
// Private methods from now on
////////////////////////////////////////////////////////////////////////////////////////
private val listenerRegistered: AtomicBoolean = new AtomicBoolean(false)
/** Register the AppEnd listener onto the Context */
private def registerContextListener(sparkContext: SparkContext): Unit = {
if (!listenerRegistered.get()) {
sparkContext.addSparkListener(new SparkListener {
override def onApplicationEnd(applicationEnd: SparkListenerApplicationEnd): Unit = {
defaultSession.set(null)
listenerRegistered.set(false)
}
})
listenerRegistered.set(true)
}
}
/** The active SparkSession for the current thread. */
private val activeThreadSession = new InheritableThreadLocal[SparkSession]
/** Reference to the root SparkSession. */
private val defaultSession = new AtomicReference[SparkSession]
private val HIVE_SESSION_STATE_BUILDER_CLASS_NAME =
"org.apache.spark.sql.hive.HiveSessionStateBuilder"
private def sessionStateClassName(conf: SparkConf): String = {
conf.get(CATALOG_IMPLEMENTATION) match {
case "hive" => HIVE_SESSION_STATE_BUILDER_CLASS_NAME
case "in-memory" => classOf[SessionStateBuilder].getCanonicalName
}
}
private def assertOnDriver(): Unit = {
if (TaskContext.get != null) {
// we're accessing it during task execution, fail.
throw new IllegalStateException(
"SparkSession should only be created and accessed on the driver.")
}
}
/**
* Helper method to create an instance of `SessionState` based on `className` from conf.
* The result is either `SessionState` or a Hive based `SessionState`.
*/
private def instantiateSessionState(
className: String,
sparkSession: SparkSession): SessionState = {
try {
// invoke new [Hive]SessionStateBuilder(
// SparkSession,
// Option[SessionState])
val clazz = Utils.classForName(className)
val ctor = clazz.getConstructors.head
ctor.newInstance(sparkSession, None).asInstanceOf[BaseSessionStateBuilder].build()
} catch {
case NonFatal(e) =>
throw new IllegalArgumentException(s"Error while instantiating '$className':", e)
}
}
/**
* @return true if Hive classes can be loaded, otherwise false.
*/
private[spark] def hiveClassesArePresent: Boolean = {
try {
Utils.classForName(HIVE_SESSION_STATE_BUILDER_CLASS_NAME)
Utils.classForName("org.apache.hadoop.hive.conf.HiveConf")
true
} catch {
case _: ClassNotFoundException | _: NoClassDefFoundError => false
}
}
private[spark] def cleanupAnyExistingSession(): Unit = {
val session = getActiveSession.orElse(getDefaultSession)
if (session.isDefined) {
logWarning(
s"""An existing Spark session exists as the active or default session.
|This probably means another suite leaked it. Attempting to stop it before continuing.
|This existing Spark session was created at:
|
|${session.get.creationSite.longForm}
|
""".stripMargin)
session.get.stop()
SparkSession.clearActiveSession()
SparkSession.clearDefaultSession()
}
}
/**
* Initialize extensions for given extension classnames. The classes will be applied to the
* extensions passed into this function.
*/
private def applyExtensions(
extensionConfClassNames: Seq[String],
extensions: SparkSessionExtensions): SparkSessionExtensions = {
extensionConfClassNames.foreach { extensionConfClassName =>
try {
val extensionConfClass = Utils.classForName(extensionConfClassName)
val extensionConf = extensionConfClass.getConstructor().newInstance()
.asInstanceOf[SparkSessionExtensions => Unit]
extensionConf(extensions)
} catch {
// Ignore the error if we cannot find the class or when the class has the wrong type.
case e@(_: ClassCastException |
_: ClassNotFoundException |
_: NoClassDefFoundError) =>
logWarning(s"Cannot use $extensionConfClassName to configure session extensions.", e)
}
}
extensions
}
/**
* Load extensions from [[ServiceLoader]] and use them
*/
private def loadExtensions(extensions: SparkSessionExtensions): Unit = {
val loader = ServiceLoader.load(classOf[SparkSessionExtensionsProvider],
Utils.getContextOrSparkClassLoader)
val loadedExts = loader.iterator()
while (loadedExts.hasNext) {
try {
val ext = loadedExts.next()
ext(extensions)
} catch {
case e: Throwable => logWarning("Failed to load session extension", e)
}
}
}
}
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