History Server: updated order for multiple attempts(descending start time)

Author: rekhajoshm

core/src/main/scala/org/apache/spark/deploy/history/FsHistoryProvider.scala

@@ -413,8 +413,8 @@ private[history] class FsHistoryProvider(conf: SparkConf, clock: Clock)
 
   /**
    * Comparison function that defines the sort order for application attempts within the same
-   * application. Order is: completed attempts before running attempts, running attempts sorted
-   * by ascending start time,completed attempts sorted by ascending end time.
+   * application. Order is: completed attempts before running attempts, if both completed
+   * or both running attempts sorted by descending start time.
    *
    * Normally applications should have a single running attempt; but failure to call sc.stop()
    * may cause multiple running attempts to show up.
@@ -425,7 +425,7 @@ private[history] class FsHistoryProvider(conf: SparkConf, clock: Clock)
       a1: FsApplicationAttemptInfo,
       a2: FsApplicationAttemptInfo): Boolean = {
     if (a1.completed == a2.completed) {
-      if (a1.completed) a1.endTime <= a2.endTime else a1.startTime <= a2.startTime
+      a1.startTime >= a2.startTime
     } else {
       a1.completed
     }

core/src/test/scala/org/apache/spark/deploy/history/FsHistoryProviderSuite.scala

@@ -272,7 +272,7 @@ class FsHistoryProviderSuite extends SparkFunSuite with BeforeAndAfter with Matc
     updateAndCheck(provider) { list =>
       list.size should be (1)
       list.head.attempts.size should be (2)
-      list.head.attempts.head.attemptId should be (Some("attempt1"))
+      list.head.attempts.head.attemptId should be (Some("attempt2"))
     }
 
     val attempt3 = newLogFile("app1", Some("attempt3"), inProgress = false)
@@ -289,7 +289,7 @@ class FsHistoryProviderSuite extends SparkFunSuite with BeforeAndAfter with Matc
     }
 
     val app2Attempt1 = newLogFile("app2", Some("attempt1"), inProgress = false)
-    writeFile(attempt2, true, None,
+    writeFile(attempt1, true, None,
       SparkListenerApplicationStart("app2", Some("app2"), 5L, "test", Some("attempt1")),
       SparkListenerApplicationEnd(6L)
       )