YARN-6851. Capacity Scheduler: document configs for controlling # containers allowed to be allocated per node heartbeat.

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-site/src/site/markdown/CapacityScheduler.md

@@ -282,6 +282,16 @@ The `ReservationSystem` is integrated with the `CapacityScheduler` queue hierach
 |:---- |:---- |
 | `yarn.scheduler.capacity.node-locality-delay` | Number of missed scheduling opportunities after which the CapacityScheduler attempts to schedule rack-local containers. Typically, this should be set to number of nodes in the cluster. By default is setting approximately number of nodes in one rack which is 40. Positive integer value is expected. |
 
+  * Container Allocation per NodeManager Heartbeat
+
+  The `CapacityScheduler` supports the following parameters to control how many containers can be allocated in each NodeManager heartbeat.
+
+| Property | Description |
+|:---- |:---- |
+| `yarn.scheduler.capacity.per-node-heartbeat.multiple-assignments-enabled` | Whether to allow multiple container assignments in one NodeManager heartbeat. Defaults to true. |
+| `yarn.scheduler.capacity.per-node-heartbeat.maximum-container-assignments` | If `multiple-assignments-enabled` is true, the maximum amount of containers that can be assigned in one NodeManager heartbeat. Defaults to -1, which sets no limit. |
+| `yarn.scheduler.capacity.per-node-heartbeat.maximum-offswitch-assignments` | If `multiple-assignments-enabled` is true, the maximum amount of off-switch containers that can be assigned in one NodeManager heartbeat. Defaults to 1, which represents only one off-switch allocation allowed in one heartbeat. |
+
 ###Reviewing the configuration of the CapacityScheduler
 
   Once the installation and configuration is completed, you can review it after starting the YARN cluster from the web-ui.