YARN-7482. Max applications calculation per queue has to be retrospected with absolute resource support. Contributed by Sunil G.

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/capacity/ParentQueue.java

@@ -1088,6 +1088,26 @@ public class ParentQueue extends AbstractCSQueue {
     childQueue.getQueueCapacities().setAbsoluteMaximumCapacity(label,
         (float) childQueue.getQueueCapacities().getMaximumCapacity(label)
             / getQueueCapacities().getAbsoluteMaximumCapacity(label));
+
+    // Re-visit max applications for a queue based on absolute capacity if
+    // needed.
+    if (childQueue instanceof LeafQueue) {
+      LeafQueue leafQueue = (LeafQueue) childQueue;
+      CapacitySchedulerConfiguration conf = csContext.getConfiguration();
+      int maxApplications = (int) (conf.getMaximumSystemApplications()
+          * childQueue.getQueueCapacities().getAbsoluteCapacity(label));
+      leafQueue.setMaxApplications(maxApplications);
+
+      int maxApplicationsPerUser = Math.min(maxApplications,
+          (int) (maxApplications
+              * (leafQueue.getUsersManager().getUserLimit() / 100.0f)
+              * leafQueue.getUsersManager().getUserLimitFactor()));
+      leafQueue.setMaxApplicationsPerUser(maxApplicationsPerUser);
+      LOG.info("LeafQueue:" + leafQueue.getQueueName() + ", maxApplications="
+          + maxApplications + ", maxApplicationsPerUser="
+          + maxApplicationsPerUser + ", Abs Cap:"
+          + childQueue.getQueueCapacities().getAbsoluteCapacity(label));
+    }
   }
 
   @Override