[SPARK-24485][SS] Measure and log elapsed time for filesystem operations in HDFSBackedStateStoreProvider

Author: HeartSaVioR

core/src/main/scala/org/apache/spark/util/Utils.scala

@@ -30,6 +30,7 @@ import java.nio.file.Files
 import java.security.SecureRandom
 import java.util.{Locale, Properties, Random, UUID}
 import java.util.concurrent._
+import java.util.concurrent.TimeUnit.NANOSECONDS
 import java.util.concurrent.atomic.AtomicBoolean
 import java.util.zip.GZIPInputStream
 
@@ -433,7 +434,7 @@ private[spark] object Utils extends Logging {
     new URI("file:///" + rawFileName).getPath.substring(1)
   }
 
-    /**
+  /**
    * Download a file or directory to target directory. Supports fetching the file in a variety of
    * ways, including HTTP, Hadoop-compatible filesystems, and files on a standard filesystem, based
    * on the URL parameter. Fetching directories is only supported from Hadoop-compatible
@@ -506,6 +507,14 @@ private[spark] object Utils extends Logging {
     targetFile
   }
 
+  /** Records the duration of running `body`. */
+  def timeTakenMs[T](body: => T): (T, Long) = {
+    val startTime = System.nanoTime()
+    val result = body
+    val endTime = System.nanoTime()
+    (result, math.max(NANOSECONDS.toMillis(endTime - startTime), 0))
+  }
+
   /**
    * Download `in` to `tempFile`, then move it to `destFile`.
    *

sql/core/src/main/scala/org/apache/spark/sql/execution/streaming/state/HDFSBackedStateStoreProvider.scala

@@ -18,12 +18,10 @@
 package org.apache.spark.sql.execution.streaming.state
 
 import java.io._
-import java.nio.channels.ClosedChannelException
 import java.util.Locale
 
 import scala.collection.JavaConverters._
 import scala.collection.mutable
-import scala.util.Random
 import scala.util.control.NonFatal
 
 import com.google.common.io.ByteStreams
@@ -280,38 +278,49 @@ private[state] class HDFSBackedStateStoreProvider extends StateStoreProvider wit
     if (loadedCurrentVersionMap.isDefined) {
       return loadedCurrentVersionMap.get
     }
-    val snapshotCurrentVersionMap = readSnapshotFile(version)
-    if (snapshotCurrentVersionMap.isDefined) {
-      synchronized { loadedMaps.put(version, snapshotCurrentVersionMap.get) }
-      return snapshotCurrentVersionMap.get
-    }
 
-    // Find the most recent map before this version that we can.
-    // [SPARK-22305] This must be done iteratively to avoid stack overflow.
-    var lastAvailableVersion = version
-    var lastAvailableMap: Option[MapType] = None
-    while (lastAvailableMap.isEmpty) {
-      lastAvailableVersion -= 1
+    logWarning(s"The state for version $version doesn't exist in loadedMaps. " +
+      "Reading snapshot file and delta files if needed..." +
+      "Note that this is normal for the first batch of starting query.")
 
-      if (lastAvailableVersion <= 0) {
-        // Use an empty map for versions 0 or less.
-        lastAvailableMap = Some(new MapType)
-      } else {
-        lastAvailableMap =
-          synchronized { loadedMaps.get(lastAvailableVersion) }
-            .orElse(readSnapshotFile(lastAvailableVersion))
+    val (result, elapsedMs) = Utils.timeTakenMs {
+      val snapshotCurrentVersionMap = readSnapshotFile(version)
+      if (snapshotCurrentVersionMap.isDefined) {
+        synchronized { loadedMaps.put(version, snapshotCurrentVersionMap.get) }
+        return snapshotCurrentVersionMap.get
+      }
+
+      // Find the most recent map before this version that we can.
+      // [SPARK-22305] This must be done iteratively to avoid stack overflow.
+      var lastAvailableVersion = version
+      var lastAvailableMap: Option[MapType] = None
+      while (lastAvailableMap.isEmpty) {
+        lastAvailableVersion -= 1
+
+        if (lastAvailableVersion <= 0) {
+          // Use an empty map for versions 0 or less.
+          lastAvailableMap = Some(new MapType)
+        } else {
+          lastAvailableMap =
+            synchronized { loadedMaps.get(lastAvailableVersion) }
+              .orElse(readSnapshotFile(lastAvailableVersion))
+        }
+      }
+
+      // Load all the deltas from the version after the last available one up to the target version.
+      // The last available version is the one with a full snapshot, so it doesn't need deltas.
+      val resultMap = new MapType(lastAvailableMap.get)
+      for (deltaVersion <- lastAvailableVersion + 1 to version) {
+        updateFromDeltaFile(deltaVersion, resultMap)
       }
-    }
 
-    // Load all the deltas from the version after the last available one up to the target version.
-    // The last available version is the one with a full snapshot, so it doesn't need deltas.
-    val resultMap = new MapType(lastAvailableMap.get)
-    for (deltaVersion <- lastAvailableVersion + 1 to version) {
-      updateFromDeltaFile(deltaVersion, resultMap)
+      synchronized { loadedMaps.put(version, resultMap) }
+      resultMap
     }
 
-    synchronized { loadedMaps.put(version, resultMap) }
-    resultMap
+    logWarning(s"Loading state for $version takes $elapsedMs ms.")
+
+    result
   }
 
   private def writeUpdateToDeltaFile(
@@ -490,15 +499,18 @@ private[state] class HDFSBackedStateStoreProvider extends StateStoreProvider wit
   /** Perform a snapshot of the store to allow delta files to be consolidated */
   private def doSnapshot(): Unit = {
     try {
-      val files = fetchFiles()
+      val (files, e1) = Utils.timeTakenMs(fetchFiles())
+      logDebug(s"fetchFiles() took $e1 ms.")
+
       if (files.nonEmpty) {
         val lastVersion = files.last.version
         val deltaFilesForLastVersion =
           filesForVersion(files, lastVersion).filter(_.isSnapshot == false)
         synchronized { loadedMaps.get(lastVersion) } match {
           case Some(map) =>
             if (deltaFilesForLastVersion.size > storeConf.minDeltasForSnapshot) {
-              writeSnapshotFile(lastVersion, map)
+              val (_, e2) = Utils.timeTakenMs(writeSnapshotFile(lastVersion, map))
+              logDebug(s"writeSnapshotFile() took $e2 ms.")
             }
           case None =>
             // The last map is not loaded, probably some other instance is in charge
@@ -517,7 +529,9 @@ private[state] class HDFSBackedStateStoreProvider extends StateStoreProvider wit
    */
   private[state] def cleanup(): Unit = {
     try {
-      val files = fetchFiles()
+      val (files, e1) = Utils.timeTakenMs(fetchFiles())
+      logDebug(s"fetchFiles() took $e1 ms.")
+
       if (files.nonEmpty) {
         val earliestVersionToRetain = files.last.version - storeConf.minVersionsToRetain
         if (earliestVersionToRetain > 0) {
@@ -527,9 +541,12 @@ private[state] class HDFSBackedStateStoreProvider extends StateStoreProvider wit
             mapsToRemove.foreach(loadedMaps.remove)
           }
           val filesToDelete = files.filter(_.version < earliestFileToRetain.version)
-          filesToDelete.foreach { f =>
-            fm.delete(f.path)
+          val (_, e2) = Utils.timeTakenMs {
+            filesToDelete.foreach { f =>
+              fm.delete(f.path)
+            }
           }
+          logDebug(s"deleting files took $e2 ms.")
           logInfo(s"Deleted files older than ${earliestFileToRetain.version} for $this: " +
             filesToDelete.mkString(", "))
         }

sql/core/src/main/scala/org/apache/spark/sql/execution/streaming/statefulOperators.scala

@@ -35,7 +35,7 @@ import org.apache.spark.sql.execution.metric.{SQLMetric, SQLMetrics}
 import org.apache.spark.sql.execution.streaming.state._
 import org.apache.spark.sql.streaming.{OutputMode, StateOperatorProgress}
 import org.apache.spark.sql.types._
-import org.apache.spark.util.{CompletionIterator, NextIterator}
+import org.apache.spark.util.{CompletionIterator, NextIterator, Utils}
 
 
 /** Used to identify the state store for a given operator. */
@@ -97,12 +97,7 @@ trait StateStoreWriter extends StatefulOperator { self: SparkPlan =>
   }
 
   /** Records the duration of running `body` for the next query progress update. */
-  protected def timeTakenMs(body: => Unit): Long = {
-    val startTime = System.nanoTime()
-    val result = body
-    val endTime = System.nanoTime()
-    math.max(NANOSECONDS.toMillis(endTime - startTime), 0)
-  }
+  protected def timeTakenMs(body: => Unit): Long = Utils.timeTakenMs(body)._2
 
   /**
    * Set the SQL metrics related to the state store.