[SPARK-20244][CORE] Handle incorrect bytesRead metrics when using PyS…

…park

## What changes were proposed in this pull request?

Hadoop FileSystem's statistics in based on thread local variables, this is ok if the RDD computation chain is running in the same thread. But if child RDD creates another thread to consume the iterator got from Hadoop RDDs, the bytesRead computation will be error, because now the iterator's `next()` and `close()` may run in different threads. This could be happened when using PySpark with PythonRDD.

So here building a map to track the `bytesRead` for different thread and add them together. This method will be used in three RDDs, `HadoopRDD`, `NewHadoopRDD` and `FileScanRDD`. I assume `FileScanRDD` cannot be called directly, so I only fixed `HadoopRDD` and `NewHadoopRDD`.

## How was this patch tested?

Unit test and local cluster verification.

Author: jerryshao <sshao@hortonworks.com>

Closes #17617 from jerryshao/SPARK-20244.

core/src/main/scala/org/apache/spark/deploy/SparkHadoopUtil.scala

@@ -23,6 +23,7 @@ import java.text.DateFormat
 import java.util.{Arrays, Comparator, Date, Locale}
 
 import scala.collection.JavaConverters._
+import scala.collection.mutable
 import scala.util.control.NonFatal
 
 import com.google.common.primitives.Longs
@@ -143,14 +144,29 @@ class SparkHadoopUtil extends Logging {
    * Returns a function that can be called to find Hadoop FileSystem bytes read. If
    * getFSBytesReadOnThreadCallback is called from thread r at time t, the returned callback will
    * return the bytes read on r since t.
-   *
-   * @return None if the required method can't be found.
    */
   private[spark] def getFSBytesReadOnThreadCallback(): () => Long = {
-    val threadStats = FileSystem.getAllStatistics.asScala.map(_.getThreadStatistics)
-    val f = () => threadStats.map(_.getBytesRead).sum
-    val baselineBytesRead = f()
-    () => f() - baselineBytesRead
+    val f = () => FileSystem.getAllStatistics.asScala.map(_.getThreadStatistics.getBytesRead).sum
+    val baseline = (Thread.currentThread().getId, f())
+
+    /**
+     * This function may be called in both spawned child threads and parent task thread (in
+     * PythonRDD), and Hadoop FileSystem uses thread local variables to track the statistics.
+     * So we need a map to track the bytes read from the child threads and parent thread,
+     * summing them together to get the bytes read of this task.
+     */
+    new Function0[Long] {
+      private val bytesReadMap = new mutable.HashMap[Long, Long]()
+
+      override def apply(): Long = {
+        bytesReadMap.synchronized {
+          bytesReadMap.put(Thread.currentThread().getId, f())
+          bytesReadMap.map { case (k, v) =>
+            v - (if (k == baseline._1) baseline._2 else 0)
+          }.sum
+        }
+      }
+    }
   }
 
   /**

core/src/main/scala/org/apache/spark/rdd/HadoopRDD.scala

@@ -251,7 +251,13 @@ class HadoopRDD[K, V](
             null
         }
       // Register an on-task-completion callback to close the input stream.
-      context.addTaskCompletionListener{ context => closeIfNeeded() }
+      context.addTaskCompletionListener { context =>
+        // Update the bytes read before closing is to make sure lingering bytesRead statistics in
+        // this thread get correctly added.
+        updateBytesRead()
+        closeIfNeeded()
+      }
+
       private val key: K = if (reader == null) null.asInstanceOf[K] else reader.createKey()
       private val value: V = if (reader == null) null.asInstanceOf[V] else reader.createValue()
 

core/src/main/scala/org/apache/spark/rdd/NewHadoopRDD.scala

@@ -191,7 +191,13 @@ class NewHadoopRDD[K, V](
         }
 
       // Register an on-task-completion callback to close the input stream.
-      context.addTaskCompletionListener(context => close())
+      context.addTaskCompletionListener { context =>
+        // Update the bytesRead before closing is to make sure lingering bytesRead statistics in
+        // this thread get correctly added.
+        updateBytesRead()
+        close()
+      }
+
       private var havePair = false
       private var recordsSinceMetricsUpdate = 0
 

core/src/test/scala/org/apache/spark/metrics/InputOutputMetricsSuite.scala

@@ -34,7 +34,7 @@ import org.scalatest.BeforeAndAfter
 
 import org.apache.spark.{SharedSparkContext, SparkFunSuite}
 import org.apache.spark.scheduler.{SparkListener, SparkListenerTaskEnd}
-import org.apache.spark.util.Utils
+import org.apache.spark.util.{ThreadUtils, Utils}
 
 class InputOutputMetricsSuite extends SparkFunSuite with SharedSparkContext
   with BeforeAndAfter {
@@ -319,6 +319,35 @@ class InputOutputMetricsSuite extends SparkFunSuite with SharedSparkContext
     }
     assert(bytesRead >= tmpFile.length())
   }
+
+  test("input metrics with old Hadoop API in different thread") {
+    val bytesRead = runAndReturnBytesRead {
+      sc.textFile(tmpFilePath, 4).mapPartitions { iter =>
+        val buf = new ArrayBuffer[String]()
+        ThreadUtils.runInNewThread("testThread", false) {
+          iter.flatMap(_.split(" ")).foreach(buf.append(_))
+        }
+
+        buf.iterator
+      }.count()
+    }
+    assert(bytesRead >= tmpFile.length())
+  }
+
+  test("input metrics with new Hadoop API in different thread") {
+    val bytesRead = runAndReturnBytesRead {
+      sc.newAPIHadoopFile(tmpFilePath, classOf[NewTextInputFormat], classOf[LongWritable],
+        classOf[Text]).mapPartitions { iter =>
+        val buf = new ArrayBuffer[String]()
+        ThreadUtils.runInNewThread("testThread", false) {
+          iter.map(_._2.toString).flatMap(_.split(" ")).foreach(buf.append(_))
+        }
+
+        buf.iterator
+      }.count()
+    }
+    assert(bytesRead >= tmpFile.length())
+  }
 }
 
 /**