SPARK-1319: Fix scheduler to account for tasks using > 1 CPUs.

Move CPUS_PER_TASK to TaskSchedulerImpl as the value is a constant and use it in both Mesos and CoarseGrained scheduler backends.

Thanks @kayousterhout for the design discussion

Author: Shivaram Venkataraman <shivaram@eecs.berkeley.edu>

Closes #219 from shivaram/multi-cpus and squashes the following commits:

5c7d685 [Shivaram Venkataraman] Don't pass availableCpus to TaskSetManager
260e4d5 [Shivaram Venkataraman] Add a check for non-zero CPUs in TaskSetManager
73fcf6f [Shivaram Venkataraman] Add documentation for spark.task.cpus
647bc45 [Shivaram Venkataraman] Fix scheduler to account for tasks using > 1 CPUs. Move CPUS_PER_TASK to TaskSchedulerImpl as the value is a constant and use it in both Mesos and CoarseGrained scheduler backends.

1 files changed, 7 insertions, 0 deletions

diff --git a/docs/configuration.md b/docs/configuration.md
index 16ee5ec0f2..1ff0150567 100644
--- a/docs/configuration.md
+++ b/docs/configuration.md
@@ -579,6 +579,13 @@ Apart from these, the following properties are also available, and may be useful
     out and giving up. 
   </td>
 </tr>
+<tr>
+  <td>spark.task.cpus</td>
+  <td>1</td>
+  <td>
+    Number of cores to allocate for each task.
+  </td>
+</tr>
 </table>
 
 ## Viewing Spark Properties