[GitHub] [spark] viirya commented on a change in pull request #24699: [SPARK-27666][CORE] Do not release lock while TaskContext already completed

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viirya commented on a change in pull request #24699: [SPARK-27666][CORE] Do not release lock while TaskContext already completed
URL: https://github.com/apache/spark/pull/24699#discussion_r288374574
 
 

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 File path: core/src/main/scala/org/apache/spark/storage/BlockManager.scala
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 @@ -992,12 +992,20 @@ private[spark] class BlockManager(
 
   /**
    * Release a lock on the given block with explicit TID.
-   * The param `taskAttemptId` should be passed in case we can't get the correct TID from
-   * TaskContext, for example, the input iterator of a cached RDD iterates to the end in a child
+   * The param `taskContext` should be passed in case we can't get the correct TaskContext
+   * for example, the input iterator of a cached RDD iterates to the end in a child
    * thread.
    */
-  def releaseLock(blockId: BlockId, taskAttemptId: Option[Long] = None): Unit = {
-    blockInfoManager.unlock(blockId, taskAttemptId)
+  def releaseLock(blockId: BlockId, taskContext: Option[TaskContext] = None): Unit = {
+    val taskAttemptId = taskContext.map(_.taskAttemptId())
+    // SPARK-27666. Child thread spawned from task thread could produce race condition
+    // on block lock releasing. We should prevent child thread from releasing un-locked
+    // block when task thread has already finished.
+    if (taskContext.isDefined && taskContext.map(_.isCompleted()).get) {
+      logWarning(s"Task $taskAttemptId already completed, not releasing lock for $blockId")
 
 Review comment:
   `${taskAttemptId.get}`

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