Github user marmbrus commented on a diff in the pull request: https://github.com/apache/spark/pull/8909#discussion_r41421063 --- Diff: sql/core/src/main/scala/org/apache/spark/sql/SQLContext.scala --- @@ -1208,36 +1204,72 @@ object SQLContext { private val INSTANTIATION_LOCK = new Object() /** - * Reference to the last created SQLContext. + * The active SQLContext for threads. + */ + private val activeContexts: InheritableThreadLocal[SQLContext] = + new InheritableThreadLocal[SQLContext] + + /** + * Reference to the created SQLContext. */ - @transient private val lastInstantiatedContext = new AtomicReference[SQLContext]() + @transient private val instantiatedContext = new AtomicReference[SQLContext]() /** * Get the singleton SQLContext if it exists or create a new one using the given SparkContext. + * * This function can be used to create a singleton SQLContext object that can be shared across * the JVM. + * + * If there an active SQLContext for current thread, it will returned instead of the global one. */ def getOrCreate(sparkContext: SparkContext): SQLContext = { + val ctx = activeContexts.get() + if (ctx != null) { + return ctx + } + INSTANTIATION_LOCK.synchronized { - if (lastInstantiatedContext.get() == null) { + val ctx = instantiatedContext.get() + if (ctx == null) { new SQLContext(sparkContext) + } else { + ctx } } - lastInstantiatedContext.get() } - private[sql] def clearLastInstantiatedContext(): Unit = { + private[sql] def clearInstantiatedContext(): Unit = { + INSTANTIATION_LOCK.synchronized { + instantiatedContext.set(null) + } + } + + private[sql] def clearTheInstantiatedContext(sqlContext: SQLContext): Unit = { INSTANTIATION_LOCK.synchronized { - lastInstantiatedContext.set(null) + instantiatedContext.compareAndSet(sqlContext, null) } } - private[sql] def setLastInstantiatedContext(sqlContext: SQLContext): Unit = { + private[sql] def setInstantiatedContext(sqlContext: SQLContext): Unit = { INSTANTIATION_LOCK.synchronized { - lastInstantiatedContext.set(sqlContext) + instantiatedContext.compareAndSet(null, sqlContext) } } + /* --- End diff -- nit: indent and need two *
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