[SPARK-12411] [CORE] Decrease executor heartbeat timeout to match hea…

…rtbeat interval.

Previously, the rpc timeout was the default network timeout, which is the same value
the driver uses to determine dead executors. This means if there is a network issue,
the executor is determined dead after one heartbeat attempt. There is a separate config
for the heartbeat interval which is a better value to use for the heartbeat RPC. With
this change, the executor will make multiple heartbeat attempts even with RPC issues.

core/src/main/scala/org/apache/spark/executor/Executor.scala

@@ -30,6 +30,7 @@ import scala.util.control.NonFatal
 import org.apache.spark._
 import org.apache.spark.deploy.SparkHadoopUtil
 import org.apache.spark.memory.TaskMemoryManager
+import org.apache.spark.rpc.RpcTimeout
 import org.apache.spark.scheduler.{DirectTaskResult, IndirectTaskResult, Task}
 import org.apache.spark.shuffle.FetchFailedException
 import org.apache.spark.storage.{StorageLevel, TaskResultBlockId}
@@ -445,7 +446,8 @@ private[spark] class Executor(
 
     val message = Heartbeat(executorId, tasksMetrics.toArray, env.blockManager.blockManagerId)
     try {
-      val response = heartbeatReceiverRef.askWithRetry[HeartbeatResponse](message)
+      val response = heartbeatReceiverRef.askWithRetry[HeartbeatResponse](
+          message, RpcTimeout(conf, "spark.executor.heartbeatInterval", "10s"))
       if (response.reregisterBlockManager) {
         logInfo("Told to re-register on heartbeat")
         env.blockManager.reregister()