[SPARK-6350][Mesos] Make mesosExecutorCores configurable in mesos "fine-grained" mode

- Defined executorCores from "spark.mesos.executor.cores"
- Changed the amount of mesosExecutor's cores to executorCores.
- Added new configuration option on running-on-mesos.md

Author: Jongyoul Lee <jongyoul@gmail.com>

Closes #5063 from jongyoul/SPARK-6350 and squashes the following commits:

9238d6e [Jongyoul Lee] [SPARK-6350][Mesos] Make mesosExecutorCores configurable in mesos "fine-grained" mode - Fixed docs - Changed configuration name - Made mesosExecutorCores private
2d41241 [Jongyoul Lee] [SPARK-6350][Mesos] Make mesosExecutorCores configurable in mesos "fine-grained" mode - Fixed docs
89edb4f [Jongyoul Lee] [SPARK-6350][Mesos] Make mesosExecutorCores configurable in mesos "fine-grained" mode - Fixed docs
8ba7694 [Jongyoul Lee] [SPARK-6350][Mesos] Make mesosExecutorCores configurable in mesos "fine-grained" mode - Fixed docs
7549314 [Jongyoul Lee] [SPARK-6453][Mesos] Some Mesos*Suite have a different package with their classes - Fixed docs
4ae7b0c [Jongyoul Lee] [SPARK-6453][Mesos] Some Mesos*Suite have a different package with their classes - Removed TODO
c27efce [Jongyoul Lee] [SPARK-6453][Mesos] Some Mesos*Suite have a different package with their classes - Fixed Mesos*Suite for supporting integer WorkerOffers - Fixed Documentation
1fe4c03 [Jongyoul Lee] [SPARK-6453][Mesos] Some Mesos*Suite have a different package with their classes - Change available resources of cpus to integer value beacuse WorkerOffer support the amount cpus as integer value
5f3767e [Jongyoul Lee] Revert "[SPARK-6350][Mesos] Make mesosExecutorCores configurable in mesos "fine-grained" mode"
4b7c69e [Jongyoul Lee] [SPARK-6350][Mesos] Make mesosExecutorCores configurable in mesos "fine-grained" mode - Changed configruation name and description from "spark.mesos.executor.cores" to "spark.executor.frameworkCores"
0556792 [Jongyoul Lee] [SPARK-6350][Mesos] Make mesosExecutorCores configurable in mesos "fine-grained" mode - Defined executorCores from "spark.mesos.executor.cores" - Changed the amount of mesosExecutor's cores to executorCores. - Added new configuration option on running-on-mesos.md

3 files changed, 19 insertions, 9 deletions

diff --git a/core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/MesosSchedulerBackend.scala b/core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/MesosSchedulerBackend.scala
index b381436839..d9d62b0e28 100644
--- a/core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/MesosSchedulerBackend.scala
+++ b/core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/MesosSchedulerBackend.scala
@@ -67,6 +67,8 @@ private[spark] class MesosSchedulerBackend(
 
   // The listener bus to publish executor added/removed events.
   val listenerBus = sc.listenerBus
+  
+  private[mesos] val mesosExecutorCores = sc.conf.getDouble("spark.mesos.mesosExecutor.cores", 1)
 
   @volatile var appId: String = _
 
@@ -139,7 +141,7 @@ private[spark] class MesosSchedulerBackend(
       .setName("cpus")
       .setType(Value.Type.SCALAR)
       .setScalar(Value.Scalar.newBuilder()
-        .setValue(scheduler.CPUS_PER_TASK).build())
+        .setValue(mesosExecutorCores).build())
       .build()
     val memory = Resource.newBuilder()
       .setName("mem")
@@ -220,10 +222,9 @@ private[spark] class MesosSchedulerBackend(
         val mem = getResource(o.getResourcesList, "mem")
         val cpus = getResource(o.getResourcesList, "cpus")
         val slaveId = o.getSlaveId.getValue
-        // TODO(pwendell): Should below be 1 + scheduler.CPUS_PER_TASK?
         (mem >= MemoryUtils.calculateTotalMemory(sc) &&
           // need at least 1 for executor, 1 for task
-          cpus >= 2 * scheduler.CPUS_PER_TASK) ||
+          cpus >= (mesosExecutorCores + scheduler.CPUS_PER_TASK)) ||
           (slaveIdsWithExecutors.contains(slaveId) &&
             cpus >= scheduler.CPUS_PER_TASK)
       }
@@ -232,10 +233,9 @@ private[spark] class MesosSchedulerBackend(
         val cpus = if (slaveIdsWithExecutors.contains(o.getSlaveId.getValue)) {
           getResource(o.getResourcesList, "cpus").toInt
         } else {
-          // If the executor doesn't exist yet, subtract CPU for executor
-          // TODO(pwendell): Should below just subtract "1"?
-          getResource(o.getResourcesList, "cpus").toInt -
-            scheduler.CPUS_PER_TASK
+          // If the Mesos executor has not been started on this slave yet, set aside a few
+          // cores for the Mesos executor by offering fewer cores to the Spark executor
+          (getResource(o.getResourcesList, "cpus") - mesosExecutorCores).toInt
         }
         new WorkerOffer(
           o.getSlaveId.getValue,
diff --git a/core/src/test/scala/org/apache/spark/scheduler/cluster/mesos/MesosSchedulerBackendSuite.scala b/core/src/test/scala/org/apache/spark/scheduler/cluster/mesos/MesosSchedulerBackendSuite.scala
index a311512e82..cdd7be0fbe 100644
--- a/core/src/test/scala/org/apache/spark/scheduler/cluster/mesos/MesosSchedulerBackendSuite.scala
+++ b/core/src/test/scala/org/apache/spark/scheduler/cluster/mesos/MesosSchedulerBackendSuite.scala
@@ -118,12 +118,12 @@ class MesosSchedulerBackendSuite extends FunSuite with LocalSparkContext with Mo
     expectedWorkerOffers.append(new WorkerOffer(
       mesosOffers.get(0).getSlaveId.getValue,
       mesosOffers.get(0).getHostname,
-      2
+      (minCpu - backend.mesosExecutorCores).toInt
     ))
     expectedWorkerOffers.append(new WorkerOffer(
       mesosOffers.get(2).getSlaveId.getValue,
       mesosOffers.get(2).getHostname,
-      2
+      (minCpu - backend.mesosExecutorCores).toInt
     ))
     val taskDesc = new TaskDescription(1L, 0, "s1", "n1", 0, ByteBuffer.wrap(new Array[Byte](0)))
     when(taskScheduler.resourceOffers(expectedWorkerOffers)).thenReturn(Seq(Seq(taskDesc)))
diff --git a/docs/running-on-mesos.md b/docs/running-on-mesos.md
index c984639bd3..594bf78b67 100644
--- a/docs/running-on-mesos.md
+++ b/docs/running-on-mesos.md
@@ -211,6 +211,16 @@ See the [configuration page](configuration.html) for information on Spark config
   </td>
 </tr>
 <tr>
+  <td><code>spark.mesos.mesosExecutor.cores</code></td>
+  <td>1.0</td>
+  <td>
+    (Fine-grained mode only) Number of cores to give each Mesos executor. This does not
+    include the cores used to run the Spark tasks. In other words, even if no Spark task
+    is being run, each Mesos executor will occupy the number of cores configured here.
+    The value can be a floating point number.
+  </td>
+</tr>
+<tr>
   <td><code>spark.mesos.executor.home</code></td>
   <td>driver side <code>SPARK_HOME</code></td>
   <td>