YARN-1678. Fair scheduler gabs incessantly about reservations (Sandy Ryza)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1571468 13f79535-47bb-0310-9956-ffa450edef68

hadoop-yarn-project/CHANGES.txt

@@ -28,6 +28,8 @@ Release 2.5.0 - UNRELEASED
     YARN-1736. FS: AppSchedulable.assignContainer's priority argument is 
     redundant. (Naren Koneru via kasha)
 
+    YARN-1678. Fair scheduler gabs incessantly about reservations (Sandy Ryza)
+
   OPTIMIZATIONS
 
   BUG FIXES 

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/fair/AppSchedulable.java

@@ -201,6 +201,22 @@ public void unreserve(Priority priority, FSSchedulerNode node) {
    * Assign a container to this node to facilitate {@code request}. If node does
    * not have enough memory, create a reservation. This is called once we are
    * sure the particular request should be facilitated by this node.
+   * 
+   * @param node
+   *     The node to try placing the container on.
+   * @param priority
+   *     The requested priority for the container.
+   * @param request
+   *     The ResourceRequest we're trying to satisfy.
+   * @param type
+   *     The locality of the assignment.
+   * @param reserved
+   *     Whether there's already a container reserved for this app on the node.
+   * @return
+   *     If an assignment was made, returns the resources allocated to the
+   *     container.  If a reservation was made, returns
+   *     FairScheduler.CONTAINER_RESERVED.  If no assignment or reservation was
+   *     made, returns an empty resource.
    */
   private Resource assignContainer(FSSchedulerNode node,
       ResourceRequest request, NodeType type,
@@ -255,17 +271,6 @@ private Resource assignContainer(FSSchedulerNode node, boolean reserved) {
       LOG.debug("Node offered to app: " + getName() + " reserved: " + reserved);
     }
 
-    if (reserved) {
-      RMContainer rmContainer = node.getReservedContainer();
-      Priority priority = rmContainer.getReservedPriority();
-
-      // Make sure the application still needs requests at this priority
-      if (app.getTotalRequiredResources(priority) == 0) {
-        unreserve(priority, node);
-        return Resources.none();
-      }
-    }
-
     Collection<Priority> prioritiesToTry = (reserved) ? 
         Arrays.asList(node.getReservedContainer().getReservedPriority()) : 
         app.getPriorities();
@@ -338,7 +343,33 @@ private Resource assignContainer(FSSchedulerNode node, boolean reserved) {
     return Resources.none();
   }
 
+  /**
+   * Called when this application already has an existing reservation on the
+   * given node.  Sees whether we can turn the reservation into an allocation.
+   * Also checks whether the application needs the reservation anymore, and
+   * releases it if not.
+   * 
+   * @param node
+   *     Node that the application has an existing reservation on
+   */
   public Resource assignReservedContainer(FSSchedulerNode node) {
+    RMContainer rmContainer = node.getReservedContainer();
+    Priority priority = rmContainer.getReservedPriority();
+
+    // Make sure the application still needs requests at this priority
+    if (app.getTotalRequiredResources(priority) == 0) {
+      unreserve(priority, node);
+      return Resources.none();
+    }
+    
+    // Fail early if the reserved container won't fit.
+    // Note that we have an assumption here that there's only one container size
+    // per priority.
+    if (!Resources.fitsIn(node.getReservedContainer().getReservedResource(),
+        node.getAvailableResource())) {
+      return Resources.none();
+    }
+    
     return assignContainer(node, true);
   }
 

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/fair/FairScheduler.java

@@ -1046,10 +1046,12 @@ private synchronized void attemptScheduling(FSSchedulerNode node) {
         reservedAppSchedulable = null;
       } else {
         // Reservation exists; try to fulfill the reservation
-        LOG.info("Trying to fulfill reservation for application "
-            + reservedAppSchedulable.getApp().getApplicationAttemptId()
-            + " on node: " + node);
-
+        if (LOG.isDebugEnabled()) {
+          LOG.debug("Trying to fulfill reservation for application "
+              + reservedAppSchedulable.getApp().getApplicationAttemptId()
+              + " on node: " + node);
+        }
+        
         node.getReservedAppSchedulable().assignReservedContainer(node);
       }
     }