diff --git a/storm-core/src/clj/org/apache/storm/cluster.clj b/storm-core/src/clj/org/apache/storm/cluster.clj
index 810b3c3c0f3..11471bda1cf 100644
--- a/storm-core/src/clj/org/apache/storm/cluster.clj
+++ b/storm-core/src/clj/org/apache/storm/cluster.clj
@@ -88,6 +88,7 @@
   (update-storm! [this storm-id new-elems])
   (remove-storm-base! [this storm-id])
   (set-assignment! [this storm-id info])
+  (remove-assignment! [this storm-id])
   ;; sets up information related to key consisting of nimbus
   ;; host:port and version info of the blob
   (setup-blobstore! [this key nimbusInfo versionInfo])
@@ -566,6 +567,11 @@
         (let [thrift-assignment (thriftify-assignment info)]
           (.set_data cluster-state (assignment-path storm-id) (Utils/serialize thrift-assignment) acls)))
 
+      (remove-assignment!
+        [this storm-id]
+        (log-debug "removing assignment for storm " storm-id)
+        (.delete_node cluster-state (assignment-path storm-id)))
+
       (remove-blobstore-key!
         [this blob-key]
         (log-debug "removing key" blob-key)
diff --git a/storm-core/src/clj/org/apache/storm/daemon/nimbus.clj b/storm-core/src/clj/org/apache/storm/daemon/nimbus.clj
index 112d00b75b1..dbea3abeb7e 100644
--- a/storm-core/src/clj/org/apache/storm/daemon/nimbus.clj
+++ b/storm-core/src/clj/org/apache/storm/daemon/nimbus.clj
@@ -291,13 +291,40 @@
                                   (assoc-non-nil :component->executors executor-overrides))
        })))
 
+(declare try-read-storm-topology)
+(declare get-version-for-key)
+
+(defn update-storm-code-tasks [nimbus storm-id component->executors]
+  (let [subject (get-subject)
+        blob-store (:blob-store nimbus)
+        ^StormTopology topology (try-read-storm-topology storm-id blob-store)
+        old-components (all-components topology)
+        storm-cluster-state (:storm-cluster-state nimbus)
+        code-key (master-stormcode-key storm-id)
+        nimbus-host-port-info (:nimbus-host-port-info nimbus)]
+    (doseq [[comp num-tasks] component->executors
+            :let [component (get old-components comp)
+                  component-common (if (some? component) (.get_common component) nil)]]
+      (when (some? component-common)
+        (.set_parallelism_hint component-common num-tasks)
+        (.set_json_conf component-common
+          (->> {TOPOLOGY-TASKS num-tasks}
+               (merge (component-conf component))
+               to-json))
+        (log-message "Override "  storm-id " component: " comp " json conf to " (.get_json_conf component-common) " for rebalancing")))
+    (.deleteBlob blob-store code-key subject)
+    (.createBlob blob-store code-key (Utils/serialize topology) (SettableBlobMeta. BlobStoreAclHandler/DEFAULT) subject)
+    (if (instance? LocalFsBlobStore blob-store)
+      (.setup-blobstore! storm-cluster-state code-key nimbus-host-port-info (get-version-for-key code-key nimbus-host-port-info (:conf nimbus))))))
+
 (defn do-rebalance [nimbus storm-id status storm-base]
   (let [rebalance-options (:topology-action-options storm-base)]
     (.update-storm! (:storm-cluster-state nimbus)
       storm-id
         (-> {:topology-action-options nil}
           (assoc-non-nil :component->executors (:component->executors rebalance-options))
-          (assoc-non-nil :num-workers (:num-workers rebalance-options)))))
+          (assoc-non-nil :num-workers (:num-workers rebalance-options))))
+    (update-storm-code-tasks nimbus storm-id (:component->executors rebalance-options)))
   (mk-assignments nimbus :scratch-topology-id storm-id))
 
 (defn state-transitions [nimbus storm-id status storm-base]
@@ -643,7 +670,7 @@
         task->component (storm-task-info topology storm-conf)]
     (if (nil? component->executors)
       []
-      (->> (storm-task-info topology storm-conf)
+      (->> task->component
            reverse-map
            (map-val sort)
            (join-maps component->executors)
@@ -969,14 +996,16 @@
         topologies (locking (:submit-lock nimbus) (into {} (for [tid (.active-storms storm-cluster-state)]
                               {tid (read-topology-details nimbus tid)})))
         topologies (Topologies. topologies)
+        ;; for the topology which wants rebalance (specified by the scratch-topology-id)
+        ;; we remove its assignment, meaning that all the slots occupied by its assignment
+        ;; will be treated as free slot in the scheduler code
+        ;; and supervisors will kill all the old workers for rebalancing topology.
+        _ (when-not (nil? scratch-topology-id)
+            (.remove-assignment! storm-cluster-state scratch-topology-id))
         ;; read all the assignments
         assigned-topology-ids (.assignments storm-cluster-state nil)
         existing-assignments (into {} (for [tid assigned-topology-ids]
-                                        ;; for the topology which wants rebalance (specified by the scratch-topology-id)
-                                        ;; we exclude its assignment, meaning that all the slots occupied by its assignment
-                                        ;; will be treated as free slot in the scheduler code.
-                                        (when (or (nil? scratch-topology-id) (not= tid scratch-topology-id))
-                                          {tid (.assignment-info storm-cluster-state tid nil)})))]
+                                          {tid (.assignment-info storm-cluster-state tid nil)}))]
       ;; make the new assignments for topologies
       (locking (:sched-lock nimbus) (let [
           new-scheduler-assignments (compute-new-scheduler-assignments
@@ -1163,7 +1192,8 @@
 
 (defn- component-parallelism [storm-conf component]
   (let [storm-conf (merge storm-conf (component-conf component))
-        num-tasks (or (storm-conf TOPOLOGY-TASKS) (num-start-executors component))
+        ;;We should consider user defined parallelism first
+        num-tasks (or (num-start-executors component) (storm-conf TOPOLOGY-TASKS))
         max-parallelism (storm-conf TOPOLOGY-MAX-TASK-PARALLELISM)
         ]
     (if max-parallelism