[SPARK-7326] [STREAMING] Performing window() on a WindowedDStream doe…

…sn't work all the time

tdas

https://issues.apache.org/jira/browse/SPARK-7326

The problem most likely resides in DStream.slice() implementation, as shown below.

  def slice(fromTime: Time, toTime: Time): Seq[RDD[T]] = {
    if (!isInitialized) {
      throw new SparkException(this + " has not been initialized")
    }
    if (!(fromTime - zeroTime).isMultipleOf(slideDuration)) {
      logWarning("fromTime (" + fromTime + ") is not a multiple of slideDuration ("
        + slideDuration + ")")
    }
    if (!(toTime - zeroTime).isMultipleOf(slideDuration)) {
      logWarning("toTime (" + fromTime + ") is not a multiple of slideDuration ("
        + slideDuration + ")")
    }
    val alignedToTime = toTime.floor(slideDuration, zeroTime)
    val alignedFromTime = fromTime.floor(slideDuration, zeroTime)

    logInfo("Slicing from " + fromTime + " to " + toTime +
      " (aligned to " + alignedFromTime + " and " + alignedToTime + ")")

    alignedFromTime.to(alignedToTime, slideDuration).flatMap(time => {
      if (time >= zeroTime) getOrCompute(time) else None
    })
  }

Here after performing floor() on both fromTime and toTime, the result (alignedFromTime - zeroTime) and (alignedToTime - zeroTime) may no longer be multiple of the slidingDuration, thus making isTimeValid() check failed for all the remaining computation.

The fix is to add a new floor() function in Time.scala to respect the zeroTime while performing the floor :

  def floor(that: Duration, zeroTime: Time): Time = {
    val t = that.milliseconds
    new Time(((this.millis - zeroTime.milliseconds) / t) * t + zeroTime.milliseconds)
  }

And then change the DStream.slice to call this new floor function by passing in its zeroTime.

    val alignedToTime = toTime.floor(slideDuration, zeroTime)
    val alignedFromTime = fromTime.floor(slideDuration, zeroTime)

This way the alignedToTime and alignedFromTime are *really* aligned in respect to zeroTime whose value is not really a 0.

Author: Wesley Miao <wesley.miao@gmail.com>
Author: Wesley <wesley.miao@autodesk.com>

Closes apache#5871 from wesleymiao/spark-7326 and squashes the following commits:

82a4d8c [Wesley Miao] [SPARK-7326] [STREAMING] Performing window() on a WindowedDStream dosen't work all the time
48b4dc0 [Wesley] [SPARK-7326] [STREAMING] Performing window() on a WindowedDStream doesn't work all the time
6ade399 [Wesley] [SPARK-7326] [STREAMING] Performing window() on a WindowedDStream doesn't work all the time
2611745 [Wesley Miao] [SPARK-7326] [STREAMING] Performing window() on a WindowedDStream doesn't work all the time

streaming/src/main/scala/org/apache/spark/streaming/Time.scala

@@ -63,6 +63,11 @@ case class Time(private val millis: Long) {
     new Time((this.millis / t) * t)
   }
 
+  def floor(that: Duration, zeroTime: Time): Time = {
+    val t = that.milliseconds
+    new Time(((this.millis - zeroTime.milliseconds) / t) * t + zeroTime.milliseconds)
+  }
+
   def isMultipleOf(that: Duration): Boolean =
     (this.millis % that.milliseconds == 0)
 

streaming/src/main/scala/org/apache/spark/streaming/dstream/DStream.scala

@@ -763,16 +763,22 @@ abstract class DStream[T: ClassTag] (
     if (!isInitialized) {
       throw new SparkException(this + " has not been initialized")
     }
-    if (!(fromTime - zeroTime).isMultipleOf(slideDuration)) {
-      logWarning("fromTime (" + fromTime + ") is not a multiple of slideDuration ("
-        + slideDuration + ")")
+
+    val alignedToTime = if ((toTime - zeroTime).isMultipleOf(slideDuration)) {
+      toTime
+    } else {
+      logWarning("toTime (" + toTime + ") is not a multiple of slideDuration ("
+          + slideDuration + ")")
+        toTime.floor(slideDuration, zeroTime)
     }
-    if (!(toTime - zeroTime).isMultipleOf(slideDuration)) {
-      logWarning("toTime (" + fromTime + ") is not a multiple of slideDuration ("
-        + slideDuration + ")")
+
+    val alignedFromTime = if ((fromTime - zeroTime).isMultipleOf(slideDuration)) {
+      fromTime
+    } else {
+      logWarning("fromTime (" + fromTime + ") is not a multiple of slideDuration ("
+      + slideDuration + ")")
+      fromTime.floor(slideDuration, zeroTime)
     }
-    val alignedToTime = toTime.floor(slideDuration)
-    val alignedFromTime = fromTime.floor(slideDuration)
 
     logInfo("Slicing from " + fromTime + " to " + toTime +
       " (aligned to " + alignedFromTime + " and " + alignedToTime + ")")

streaming/src/test/scala/org/apache/spark/streaming/TimeSuite.scala

@@ -69,6 +69,9 @@ class TimeSuite extends TestSuiteBase {
     assert(new Time(1200).floor(new Duration(200)) == new Time(1200))
     assert(new Time(199).floor(new Duration(200)) == new Time(0))
     assert(new Time(1).floor(new Duration(1)) == new Time(1))
+    assert(new Time(1350).floor(new Duration(200), new Time(50)) == new Time(1250))
+    assert(new Time(1350).floor(new Duration(200), new Time(150)) == new Time(1350))
+    assert(new Time(1350).floor(new Duration(200), new Time(200)) == new Time(1200))
   }
 
   test("isMultipleOf") {