[SPARK-2886] Use more specific actor system name than "spark"

As of #1777 we log the name of the actor system when it binds to a port. The current name "spark" is super general and does not convey any meaning. For instance, the following line is taken from my driver log after setting `spark.driver.port` to 5001.
```
14/08/13 19:33:29 INFO Remoting: Remoting started; listening on addresses:
[akka.tcp://sparkandrews-mbp:5001]
14/08/13 19:33:29 INFO Remoting: Remoting now listens on addresses:
[akka.tcp://sparkandrews-mbp:5001]
14/08/06 13:40:05 INFO Utils: Successfully started service 'spark' on port 5001.
```
This commit renames this to "sparkDriver" and "sparkExecutor". The goal of this unambitious PR is simply to make the logged information more explicit without introducing any change in functionality.

Author: Andrew Or <andrewor14@gmail.com>

Closes #1810 from andrewor14/service-name and squashes the following commits:

8c459ed [Andrew Or] Use a common variable for driver/executor actor system names
3a92843 [Andrew Or] Change actor name to sparkDriver and sparkExecutor
921363e [Andrew Or] Merge branch 'master' of github.com:apache/spark into service-name
c8c6a62 [Andrew Or] Do not include hyphens in actor name
1c1b42e [Andrew Or] Avoid spaces in akka system name
f644b55 [Andrew Or] Use more specific service name

2 files changed, 11 insertions, 6 deletions

diff --git a/yarn/alpha/src/main/scala/org/apache/spark/deploy/yarn/ExecutorLauncher.scala b/yarn/alpha/src/main/scala/org/apache/spark/deploy/yarn/ExecutorLauncher.scala
index c3310fbc24..155dd88aa2 100644
--- a/yarn/alpha/src/main/scala/org/apache/spark/deploy/yarn/ExecutorLauncher.scala
+++ b/yarn/alpha/src/main/scala/org/apache/spark/deploy/yarn/ExecutorLauncher.scala
@@ -28,7 +28,7 @@ import org.apache.hadoop.yarn.ipc.YarnRPC
 import org.apache.hadoop.yarn.util.{ConverterUtils, Records}
 import akka.actor._
 import akka.remote._
-import org.apache.spark.{Logging, SecurityManager, SparkConf}
+import org.apache.spark.{Logging, SecurityManager, SparkConf, SparkEnv}
 import org.apache.spark.util.{Utils, AkkaUtils}
 import org.apache.spark.scheduler.cluster.CoarseGrainedSchedulerBackend
 import org.apache.spark.scheduler.cluster.CoarseGrainedClusterMessages.AddWebUIFilter
@@ -210,8 +210,11 @@ class ExecutorLauncher(args: ApplicationMasterArguments, conf: Configuration, sp
     sparkConf.set("spark.driver.host",  driverHost)
     sparkConf.set("spark.driver.port",  driverPort.toString)
 
-    val driverUrl = "akka.tcp://spark@%s:%s/user/%s".format(
-      driverHost, driverPort.toString, CoarseGrainedSchedulerBackend.ACTOR_NAME)
+    val driverUrl = "akka.tcp://%s@%s:%s/user/%s".format(
+      SparkEnv.driverActorSystemName,
+      driverHost,
+      driverPort.toString,
+      CoarseGrainedSchedulerBackend.ACTOR_NAME)
 
     actor = actorSystem.actorOf(Props(new MonitorActor(driverUrl)), name = "YarnAM")
   }
diff --git a/yarn/alpha/src/main/scala/org/apache/spark/deploy/yarn/YarnAllocationHandler.scala b/yarn/alpha/src/main/scala/org/apache/spark/deploy/yarn/YarnAllocationHandler.scala
index 80e0162e9f..568a6ef932 100644
--- a/yarn/alpha/src/main/scala/org/apache/spark/deploy/yarn/YarnAllocationHandler.scala
+++ b/yarn/alpha/src/main/scala/org/apache/spark/deploy/yarn/YarnAllocationHandler.scala
@@ -26,7 +26,7 @@ import scala.collection
 import scala.collection.JavaConversions._
 import scala.collection.mutable.{ArrayBuffer, HashMap, HashSet}
 
-import org.apache.spark.{Logging, SparkConf}
+import org.apache.spark.{Logging, SparkConf, SparkEnv}
 import org.apache.spark.scheduler.{SplitInfo,TaskSchedulerImpl}
 import org.apache.spark.scheduler.cluster.CoarseGrainedSchedulerBackend
 import org.apache.spark.util.Utils
@@ -245,8 +245,10 @@ private[yarn] class YarnAllocationHandler(
           // Deallocate + allocate can result in reusing id's wrongly - so use a different counter
           // (executorIdCounter)
           val executorId = executorIdCounter.incrementAndGet().toString
-          val driverUrl = "akka.tcp://spark@%s:%s/user/%s".format(
-            sparkConf.get("spark.driver.host"), sparkConf.get("spark.driver.port"),
+          val driverUrl = "akka.tcp://%s@%s:%s/user/%s".format(
+            SparkEnv.driverActorSystemName,
+            sparkConf.get("spark.driver.host"),
+            sparkConf.get("spark.driver.port"),
             CoarseGrainedSchedulerBackend.ACTOR_NAME)
 
           logInfo("launching container on " + containerId + " host " + executorHostname)