[GitHub] [spark] zhangrenhua commented on a change in pull request #32222: [SPARK-35126][SQL] Execute jdbc cancellation method when jdbc load job is interrupted

[GitBox <gi...@apache.org>]

zhangrenhua commented on a change in pull request #32222:
URL: https://github.com/apache/spark/pull/32222#discussion_r615369554



##########
File path: sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/jdbc/JDBCRDD.scala
##########
@@ -301,10 +306,44 @@ private[jdbc] class JDBCRDD(
         ResultSet.TYPE_FORWARD_ONLY, ResultSet.CONCUR_READ_ONLY)
     stmt.setFetchSize(options.fetchSize)
     stmt.setQueryTimeout(options.queryTimeout)
-    rs = stmt.executeQuery()
+
+    val isFinished = new AtomicBoolean(false)
+    startTheJobInterruptListenerThread(context, stmt, isFinished)
+    try{
+      rs = stmt.executeQuery()
+    } finally {
+      isFinished.set(true)
+    }
     val rowsIterator = JdbcUtils.resultSetToSparkInternalRows(rs, schema, inputMetrics)
 
     CompletionIterator[InternalRow, Iterator[InternalRow]](
       new InterruptibleIterator(context, rowsIterator), close())
   }
+
+  /**
+   * Start the job interruption listener thread, if the job is interrupted and
+   * stmt.executeQuery() is not completed, initiate a stmt.cancel() request.
+   */
+  private def startTheJobInterruptListenerThread(context: TaskContext, stmt: PreparedStatement
+                                                 , isFinished: AtomicBoolean): Unit = {
+    val thread = new Thread(() => {
+      val waitInterval = 100
+      // Always wait for job interruption or stmt.executeQuery() execution to complete
+      while (!context.isInterrupted() && !isFinished.get()) {
+        Thread.sleep(waitInterval)
+      }
+
+      // Is interrupted and stmt.executeQuery() is not completed, then initiate a cancel request
+      if (context.isInterrupted() && !isFinished.get()) {
+        logInfo(s"try to cancel query ${context.getKillReason()}")
+        try {
+          stmt.cancel()
+        } catch {
+          case e: Exception => logWarning("Exception cancel statement", e)

Review comment:
       Cancal is executed only when the job is interrupted and the query is not completed, so if the cancellation fails, the subsequent close method will continue.




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