add TODOs

Author: jiangxb1987

core/src/main/scala/org/apache/spark/barrier/BarrierTaskContext.scala

@@ -37,6 +37,7 @@ class BarrierTaskContext(
     @transient private val metricsSystem: MetricsSystem,
     // The default value is only used in tests.
     override val taskMetrics: TaskMetrics = TaskMetrics.empty)
+  // TODO make this extends TaskContext
   extends TaskContextImpl(stageId, stageAttemptNumber, partitionId, taskAttemptId, attemptNumber,
       taskMemoryManager, localProperties, metricsSystem, taskMetrics)
     with Logging {

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

@@ -226,6 +226,7 @@ private[spark] class ClientApp extends SparkApplication {
   override def start(args: Array[String], conf: SparkConf): Unit = {
     val driverArgs = new ClientArguments(args)
 
+    // TODO remove this hack
     if (!conf.contains("spark.rpc.askTimeout")) {
       conf.set("spark.rpc.askTimeout", "900s")
     }