Merge pull request alteryx#174 from ahirreddy/master

Write Spark UI url to driver file on HDFS

This makes the SIMR code path simpler

(cherry picked from commit ed25105)
Signed-off-by: Reynold Xin <rxin@apache.org>

core/src/main/scala/org/apache/spark/scheduler/cluster/SimrSchedulerBackend.scala

@@ -31,10 +31,6 @@ private[spark] class SimrSchedulerBackend(
   val tmpPath = new Path(driverFilePath + "_tmp")
   val filePath = new Path(driverFilePath)
 
-  val uiFilePath = driverFilePath + "_ui"
-  val tmpUiPath = new Path(uiFilePath + "_tmp")
-  val uiPath = new Path(uiFilePath)
-
   val maxCores = System.getProperty("spark.simr.executor.cores", "1").toInt
 
   override def start() {
@@ -49,23 +45,17 @@ private[spark] class SimrSchedulerBackend(
 
     logInfo("Writing to HDFS file: "  + driverFilePath)
     logInfo("Writing Akka address: "  + driverUrl)
-    logInfo("Writing to HDFS file: "  + uiFilePath)
     logInfo("Writing Spark UI Address: " + sc.ui.appUIAddress)
 
     // Create temporary file to prevent race condition where executors get empty driverUrl file
     val temp = fs.create(tmpPath, true)
     temp.writeUTF(driverUrl)
     temp.writeInt(maxCores)
+    temp.writeUTF(sc.ui.appUIAddress)
     temp.close()
 
     // "Atomic" rename
     fs.rename(tmpPath, filePath)
-
-    // Write Spark UI Address to file
-    val uiTemp = fs.create(tmpUiPath, true)
-    uiTemp.writeUTF(sc.ui.appUIAddress)
-    uiTemp.close()
-    fs.rename(tmpUiPath, uiPath)
   }
 
   override def stop() {