[GitHub] [spark] slamke commented on a change in pull request #27724: [SPARK-30973][SQL] ScriptTransformationExec should wait for the termination …

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slamke commented on a change in pull request #27724: [SPARK-30973][SQL] ScriptTransformationExec should wait for the termination …
URL: https://github.com/apache/spark/pull/27724#discussion_r386969280
 
 

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 File path: sql/hive/src/main/scala/org/apache/spark/sql/hive/execution/ScriptTransformationExec.scala
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 @@ -161,6 +161,7 @@ case class ScriptTransformationExec(
 
               if (scriptOutputReader != null) {
                 if (scriptOutputReader.next(scriptOutputWritable) <= 0) {
 
 Review comment:
   No, I find a way to reproduce. Just run this code in laptop for some times, it will show that when `inputStream` return -1, but the `proc` is alive. Actually, `ScriptTransformationExec ` also uses `inputStream` to check the end of stream.
   
   ``` scala 
   import scala.collection.JavaConverters._
   
   object SparkTEST {
     def main(args: Array[String]): Unit = {
       var i = 0
       for (i <- 0 until (50)) {
         check_script()
       }
     }
   
     def check_script() = {
       val script = "python /Users/buytedance/code/github/error_python.py"
       val cmd = List("/bin/bash", "-c", script)
       val builder = new ProcessBuilder(cmd.asJava)
       val proc = builder.start()
       val inputStream = proc.getInputStream
       var msg = ""
       if (inputStream.read() <= 0) {
         msg = s"Cannot read inputStream and proc status is: ${if (proc.isAlive) "alive" else "dead"}"
       }
       println(msg)
     }
   }
   ```

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