diff --git a/cpp/CHANGELOG.md b/cpp/CHANGELOG.md
index c9247d970ef73f4ac55edcab7d237c15e2b65ec0..81333e555028fe01dfaec96907763ee82aced433 100644
--- a/cpp/CHANGELOG.md
+++ b/cpp/CHANGELOG.md
@@ -83,6 +83,7 @@ Please mark all change in change log and use the ticket from JIRA.
 - MS-455 - Distribute tasks by minimal cost in scheduler
 - MS-460 - Put transport speed as weight when choosing neighbour to execute task
 - MS-459 - Add cache for pick function in tasktable
+- MS-488 - Improve code format in scheduler
 
 ## New Feature
 - MS-343 - Implement ResourceMgr
diff --git a/cpp/src/scheduler/Algorithm.cpp b/cpp/src/scheduler/Algorithm.cpp
index b861151ddf60112e1215dda6c6fe4fbbb951117e..e1e8a1e7ca51eca3b0cc033a53a4504239f6f868 100644
--- a/cpp/src/scheduler/Algorithm.cpp
+++ b/cpp/src/scheduler/Algorithm.cpp
@@ -20,12 +20,12 @@ ShortestPath(const ResourcePtr &src,
 
     std::vector<std::vector<std::string>> paths;
 
-    uint64_t num_of_resources = res_mgr->GetAllResouces().size();
+    uint64_t num_of_resources = res_mgr->GetAllResources().size();
     std::unordered_map<uint64_t, std::string> id_name_map;
     std::unordered_map<std::string, uint64_t> name_id_map;
     for (uint64_t i = 0; i < num_of_resources; ++i) {
-        id_name_map.insert(std::make_pair(i, res_mgr->GetAllResouces().at(i)->Name()));
-        name_id_map.insert(std::make_pair(res_mgr->GetAllResouces().at(i)->Name(), i));
+        id_name_map.insert(std::make_pair(i, res_mgr->GetAllResources().at(i)->name()));
+        name_id_map.insert(std::make_pair(res_mgr->GetAllResources().at(i)->name(), i));
     }
 
     std::vector<std::vector<uint64_t> > dis_matrix;
@@ -40,23 +40,23 @@ ShortestPath(const ResourcePtr &src,
 
     std::vector<bool> vis(num_of_resources, false);
     std::vector<uint64_t> dis(num_of_resources, MAXINT);
-    for (auto &res : res_mgr->GetAllResouces()) {
+    for (auto &res : res_mgr->GetAllResources()) {
 
         auto cur_node = std::static_pointer_cast<Node>(res);
         auto cur_neighbours = cur_node->GetNeighbours();
 
         for (auto &neighbour : cur_neighbours) {
             auto neighbour_res = std::static_pointer_cast<Resource>(neighbour.neighbour_node.lock());
-            dis_matrix[name_id_map.at(res->Name())][name_id_map.at(neighbour_res->Name())] =
+            dis_matrix[name_id_map.at(res->name())][name_id_map.at(neighbour_res->name())] =
                 neighbour.connection.transport_cost();
         }
     }
 
     for (uint64_t i = 0; i < num_of_resources; ++i) {
-        dis[i] = dis_matrix[name_id_map.at(src->Name())][i];
+        dis[i] = dis_matrix[name_id_map.at(src->name())][i];
     }
 
-    vis[name_id_map.at(src->Name())] = true;
+    vis[name_id_map.at(src->name())] = true;
     std::vector<int64_t> parent(num_of_resources, -1);
 
     for (uint64_t i = 0; i < num_of_resources; ++i) {
@@ -71,7 +71,7 @@ ShortestPath(const ResourcePtr &src,
         vis[temp] = true;
 
         if (i == 0) {
-            parent[temp] = name_id_map.at(src->Name());
+            parent[temp] = name_id_map.at(src->name());
         }
 
         for (uint64_t j = 0; j < num_of_resources; ++j) {
@@ -82,15 +82,15 @@ ShortestPath(const ResourcePtr &src,
         }
     }
 
-    int64_t parent_idx = parent[name_id_map.at(dest->Name())];
+    int64_t parent_idx = parent[name_id_map.at(dest->name())];
     if (parent_idx != -1) {
-        path.push_back(dest->Name());
+        path.push_back(dest->name());
     }
     while (parent_idx != -1) {
         path.push_back(id_name_map.at(parent_idx));
         parent_idx = parent[parent_idx];
     }
-    return dis[name_id_map.at(dest->Name())];
+    return dis[name_id_map.at(dest->name())];
 }
 
 }
diff --git a/cpp/src/scheduler/CacheMgr.h b/cpp/src/scheduler/CacheMgr.h
deleted file mode 100644
index 321cbbb8a43e42970d6f1926b1679c8097a657f7..0000000000000000000000000000000000000000
--- a/cpp/src/scheduler/CacheMgr.h
+++ /dev/null
@@ -1,24 +0,0 @@
-/*******************************************************************************
- * Copyright 上海赜睿信息科技有限公司(Zilliz) - All Rights Reserved
- * Unauthorized copying of this file, via any medium is strictly prohibited.
- * Proprietary and confidential.
- ******************************************************************************/
-#pragma once
-
-#include <memory>
-
-
-namespace zilliz {
-namespace milvus {
-namespace engine {
-
-// dummy cache_mgr
-class CacheMgr {
-
-};
-
-using CacheMgrPtr = std::shared_ptr<CacheMgr>;
-
-}
-}
-}
diff --git a/cpp/src/scheduler/ResourceMgr.cpp b/cpp/src/scheduler/ResourceMgr.cpp
index 65373164e3774443625cd20225ba1fa9840ec6b7..f87c5ea061054a43c3aeae38366de39fa9919c92 100644
--- a/cpp/src/scheduler/ResourceMgr.cpp
+++ b/cpp/src/scheduler/ResourceMgr.cpp
@@ -12,67 +12,31 @@ namespace zilliz {
 namespace milvus {
 namespace engine {
 
-ResourceMgr::ResourceMgr()
-    : running_(false) {
 
-}
-
-uint64_t
-ResourceMgr::GetNumOfComputeResource() {
-    uint64_t count = 0;
-    for (auto &res : resources_) {
-        if (res->HasExecutor()) {
-            ++count;
-        }
-    }
-    return count;
-}
-
-std::vector<ResourcePtr>
-ResourceMgr::GetComputeResource() {
-    std::vector<ResourcePtr > result;
+void
+ResourceMgr::Start() {
+    std::lock_guard<std::mutex> lck(resources_mutex_);
     for (auto &resource : resources_) {
-        if (resource->HasExecutor()) {
-            result.emplace_back(resource);
-        }
-    }
-    return result;
-}
-
-uint64_t
-ResourceMgr::GetNumGpuResource() const {
-    uint64_t num = 0;
-    for (auto &res : resources_) {
-        if (res->Type() == ResourceType::GPU) {
-            num++;
-        }
+        resource->Start();
     }
-    return num;
+    running_ = true;
+    worker_thread_ = std::thread(&ResourceMgr::event_process, this);
 }
 
-ResourcePtr
-ResourceMgr::GetResource(ResourceType type, uint64_t device_id) {
-    for (auto &resource : resources_) {
-        if (resource->Type() == type && resource->DeviceId() == device_id) {
-            return resource;
-        }
+void
+ResourceMgr::Stop() {
+    {
+        std::lock_guard<std::mutex> lock(event_mutex_);
+        running_ = false;
+        queue_.push(nullptr);
+        event_cv_.notify_one();
     }
-    return nullptr;
-}
+    worker_thread_.join();
 
-ResourcePtr
-ResourceMgr::GetResourceByName(std::string name) {
+    std::lock_guard<std::mutex> lck(resources_mutex_);
     for (auto &resource : resources_) {
-        if (resource->Name() == name) {
-            return resource;
-        }
+        resource->Stop();
     }
-    return nullptr;
-}
-
-std::vector<ResourcePtr>
-ResourceMgr::GetAllResouces() {
-    return resources_;
 }
 
 ResourceWPtr
@@ -85,75 +49,85 @@ ResourceMgr::Add(ResourcePtr &&resource) {
         return ret;
     }
 
-    if (resource->Type() == ResourceType::DISK) {
+    resource->RegisterSubscriber(std::bind(&ResourceMgr::post_event, this, std::placeholders::_1));
+
+    if (resource->type() == ResourceType::DISK) {
         disk_resources_.emplace_back(ResourceWPtr(resource));
     }
     resources_.emplace_back(resource);
 
-    size_t index = resources_.size() - 1;
-    resource->RegisterSubscriber(std::bind(&ResourceMgr::PostEvent, this, std::placeholders::_1));
     return ret;
 }
 
 void
 ResourceMgr::Connect(const std::string &name1, const std::string &name2, Connection &connection) {
-    auto res1 = get_resource_by_name(name1);
-    auto res2 = get_resource_by_name(name2);
+    auto res1 = GetResource(name1);
+    auto res2 = GetResource(name2);
     if (res1 && res2) {
         res1->AddNeighbour(std::static_pointer_cast<Node>(res2), connection);
+        // TODO: enable when task balance supported
 //        res2->AddNeighbour(std::static_pointer_cast<Node>(res1), connection);
     }
 }
 
 void
-ResourceMgr::Connect(ResourceWPtr &res1, ResourceWPtr &res2, Connection &connection) {
-    if (auto observe_a = res1.lock()) {
-        if (auto observe_b = res2.lock()) {
-            observe_a->AddNeighbour(std::static_pointer_cast<Node>(observe_b), connection);
-            observe_b->AddNeighbour(std::static_pointer_cast<Node>(observe_a), connection);
-        }
-    }
+ResourceMgr::Clear() {
+    std::lock_guard<std::mutex> lck(resources_mutex_);
+    disk_resources_.clear();
+    resources_.clear();
 }
 
-
-void
-ResourceMgr::Start() {
-    std::lock_guard<std::mutex> lck(resources_mutex_);
+std::vector<ResourcePtr>
+ResourceMgr::GetComputeResource() {
+    std::vector<ResourcePtr> result;
     for (auto &resource : resources_) {
-        resource->Start();
+        if (resource->HasExecutor()) {
+            result.emplace_back(resource);
+        }
     }
-    running_ = true;
-    worker_thread_ = std::thread(&ResourceMgr::event_process, this);
+    return result;
 }
 
-void
-ResourceMgr::Stop() {
-    {
-        std::lock_guard<std::mutex> lock(event_mutex_);
-        running_ = false;
-        queue_.push(nullptr);
-        event_cv_.notify_one();
+ResourcePtr
+ResourceMgr::GetResource(ResourceType type, uint64_t device_id) {
+    for (auto &resource : resources_) {
+        if (resource->type() == type && resource->device_id() == device_id) {
+            return resource;
+        }
     }
-    worker_thread_.join();
+    return nullptr;
+}
 
-    std::lock_guard<std::mutex> lck(resources_mutex_);
+ResourcePtr
+ResourceMgr::GetResource(const std::string &name) {
     for (auto &resource : resources_) {
-        resource->Stop();
+        if (resource->name() == name) {
+            return resource;
+        }
     }
+    return nullptr;
 }
 
-void
-ResourceMgr::Clear() {
-    std::lock_guard<std::mutex> lck(resources_mutex_);
-    disk_resources_.clear();
-    resources_.clear();
+uint64_t
+ResourceMgr::GetNumOfComputeResource() {
+    uint64_t count = 0;
+    for (auto &res : resources_) {
+        if (res->HasExecutor()) {
+            ++count;
+        }
+    }
+    return count;
 }
 
-void
-ResourceMgr::PostEvent(const EventPtr &event) {
-    std::lock_guard<std::mutex> lock(event_mutex_);
-    queue_.emplace(event);
-    event_cv_.notify_one();
+uint64_t
+ResourceMgr::GetNumGpuResource() const {
+    uint64_t num = 0;
+    for (auto &res : resources_) {
+        if (res->type() == ResourceType::GPU) {
+            num++;
+        }
+    }
+    return num;
 }
 
 std::string
@@ -180,14 +154,13 @@ ResourceMgr::DumpTaskTables() {
     return ss.str();
 }
 
-ResourcePtr
-ResourceMgr::get_resource_by_name(const std::string &name) {
-    for (auto &res : resources_) {
-        if (res->Name() == name) {
-            return res;
-        }
+void
+ResourceMgr::post_event(const EventPtr &event) {
+    {
+        std::lock_guard<std::mutex> lock(event_mutex_);
+        queue_.emplace(event);
     }
-    return nullptr;
+    event_cv_.notify_one();
 }
 
 void
@@ -203,8 +176,6 @@ ResourceMgr::event_process() {
             break;
         }
 
-//        ENGINE_LOG_DEBUG << "ResourceMgr process " << *event;
-
         if (subscriber_) {
             subscriber_(event);
         }
diff --git a/cpp/src/scheduler/ResourceMgr.h b/cpp/src/scheduler/ResourceMgr.h
index da8f34f87ef00dc8601acff3d3fa85b952818ab2..08a99eaad37d7fa2cc8085d16b91f4cea12f8e28 100644
--- a/cpp/src/scheduler/ResourceMgr.h
+++ b/cpp/src/scheduler/ResourceMgr.h
@@ -22,78 +22,63 @@ namespace engine {
 
 class ResourceMgr {
 public:
-    ResourceMgr();
+    ResourceMgr() = default;
 
+public:
     /******** Management Interface ********/
+    void
+    Start();
+
+    void
+    Stop();
+
+    ResourceWPtr
+    Add(ResourcePtr &&resource);
+
+    void
+    Connect(const std::string &res1, const std::string &res2, Connection &connection);
+
+    void
+    Clear();
+
     inline void
     RegisterSubscriber(std::function<void(EventPtr)> subscriber) {
         subscriber_ = std::move(subscriber);
     }
 
-    std::vector<ResourceWPtr> &
+public:
+    /******** Management Interface ********/
+    inline std::vector<ResourceWPtr> &
     GetDiskResources() {
         return disk_resources_;
     }
 
-    uint64_t
-    GetNumGpuResource() const;
+    // TODO: why return shared pointer
+    inline std::vector<ResourcePtr>
+    GetAllResources() {
+        return resources_;
+    }
+
+    std::vector<ResourcePtr>
+    GetComputeResource();
 
     ResourcePtr
     GetResource(ResourceType type, uint64_t device_id);
 
     ResourcePtr
-    GetResourceByName(std::string name);
+    GetResource(const std::string &name);
 
-    std::vector<ResourcePtr>
-    GetAllResouces();
-
-    /*
-     * Return account of resource which enable executor;
-     */
     uint64_t
     GetNumOfComputeResource();
 
-    std::vector<ResourcePtr>
-    GetComputeResource();
-
-    /*
-     * Add resource into Resource Management;
-     * Generate functions on events;
-     * Functions only modify bool variable, like event trigger;
-     */
-    ResourceWPtr
-    Add(ResourcePtr &&resource);
-
-    void
-    Connect(const std::string &res1, const std::string &res2, Connection &connection);
-
-    /*
-     * Create connection between A and B;
-     */
-    void
-    Connect(ResourceWPtr &res1, ResourceWPtr &res2, Connection &connection);
-
-    /*
-     * Synchronous start all resource;
-     * Last, start event process thread;
-     */
-    void
-    Start();
-
-    void
-    Stop();
-
-    void
-    Clear();
-
-    void
-    PostEvent(const EventPtr &event);
+    uint64_t
+    GetNumGpuResource() const;
 
+public:
     // TODO: add stats interface(low)
 
 public:
-    /******** Utlitity Functions ********/
-
+    /******** Utility Functions ********/
     std::string
     Dump();
 
@@ -101,26 +86,26 @@ public:
     DumpTaskTables();
 
 private:
-    ResourcePtr
-    get_resource_by_name(const std::string &name);
+    void
+    post_event(const EventPtr &event);
 
     void
     event_process();
 
 private:
-    std::queue<EventPtr> queue_;
-    std::function<void(EventPtr)> subscriber_ = nullptr;
-
-    bool running_;
+    bool running_ = false;
 
     std::vector<ResourceWPtr> disk_resources_;
     std::vector<ResourcePtr> resources_;
     mutable std::mutex resources_mutex_;
-    std::thread worker_thread_;
 
+    std::queue<EventPtr> queue_;
+    std::function<void(EventPtr)> subscriber_ = nullptr;
     std::mutex event_mutex_;
     std::condition_variable event_cv_;
 
+    std::thread worker_thread_;
+
 };
 
 using ResourceMgrPtr = std::shared_ptr<ResourceMgr>;
diff --git a/cpp/src/scheduler/SchedInst.cpp b/cpp/src/scheduler/SchedInst.cpp
index e805c53523be236db6e4f35e402e6bd8e6991091..01fbe843df33337227fa94817a4ab4c8315a122e 100644
--- a/cpp/src/scheduler/SchedInst.cpp
+++ b/cpp/src/scheduler/SchedInst.cpp
@@ -38,7 +38,7 @@ StartSchedulerService() {
                                                                enable_loader,
                                                                enable_executor));
 
-        if (res.lock()->Type() == ResourceType::GPU) {
+        if (res.lock()->type() == ResourceType::GPU) {
             auto pinned_memory = resconf.GetInt64Value(server::CONFIG_RESOURCE_PIN_MEMORY, 300);
             auto temp_memory = resconf.GetInt64Value(server::CONFIG_RESOURCE_TEMP_MEMORY, 300);
             auto resource_num = resconf.GetInt64Value(server::CONFIG_RESOURCE_NUM, 2);
diff --git a/cpp/src/scheduler/Scheduler.cpp b/cpp/src/scheduler/Scheduler.cpp
index fa67eef489c61d0767f34c9d8d0bbc0a24db6dc0..dcd17e31cfb06b9d47f5466570df74b241b19a52 100644
--- a/cpp/src/scheduler/Scheduler.cpp
+++ b/cpp/src/scheduler/Scheduler.cpp
@@ -143,7 +143,7 @@ Scheduler::OnLoadCompleted(const EventPtr &event) {
                 auto task = load_completed_event->task_table_item_->task;
 
                 // if this resource is disk, assign it to smallest cost resource
-                if (self->Type() == ResourceType::DISK) {
+                if (self->type() == ResourceType::DISK) {
                     // step 1: calculate shortest path per resource, from disk to compute resource
                     auto compute_resources = res_mgr_.lock()->GetComputeResource();
                     std::vector<std::vector<std::string>> paths;
@@ -176,11 +176,11 @@ Scheduler::OnLoadCompleted(const EventPtr &event) {
                     task->path() = task_path;
                 }
 
-                if(self->Name() == task->path().Last()) {
+                if(self->name() == task->path().Last()) {
                     self->WakeupLoader();
                 } else {
                     auto next_res_name = task->path().Next();
-                    auto next_res = res_mgr_.lock()->GetResourceByName(next_res_name);
+                    auto next_res = res_mgr_.lock()->GetResource(next_res_name);
                     load_completed_event->task_table_item_->Move();
                     next_res->task_table().Put(task);
                 }
diff --git a/cpp/src/scheduler/TaskTable.cpp b/cpp/src/scheduler/TaskTable.cpp
index 56d31e299a8e174397778d14db638454469eb9d8..086bf06835ca96645ebc7fa7622c8a494638b814 100644
--- a/cpp/src/scheduler/TaskTable.cpp
+++ b/cpp/src/scheduler/TaskTable.cpp
@@ -6,6 +6,8 @@
 
 #include "TaskTable.h"
 #include "event/TaskTableUpdatedEvent.h"
+#include "Utils.h"
+
 #include <vector>
 #include <sstream>
 #include <ctime>
@@ -15,14 +17,6 @@ namespace zilliz {
 namespace milvus {
 namespace engine {
 
-uint64_t
-get_now_timestamp() {
-    std::chrono::time_point<std::chrono::system_clock> now = std::chrono::system_clock::now();
-    auto duration = now.time_since_epoch();
-    auto millis = std::chrono::duration_cast<std::chrono::milliseconds>(duration).count();
-    return millis;
-}
-
 std::string
 ToString(TaskTableItemState state) {
     switch (state) {
@@ -64,7 +58,7 @@ TaskTableItem::Load() {
     if (state == TaskTableItemState::START) {
         state = TaskTableItemState::LOADING;
         lock.unlock();
-        timestamp.load = get_now_timestamp();
+        timestamp.load = get_current_timestamp();
         return true;
     }
     return false;
@@ -75,7 +69,7 @@ TaskTableItem::Loaded() {
     if (state == TaskTableItemState::LOADING) {
         state = TaskTableItemState::LOADED;
         lock.unlock();
-        timestamp.loaded = get_now_timestamp();
+        timestamp.loaded = get_current_timestamp();
         return true;
     }
     return false;
@@ -86,7 +80,7 @@ TaskTableItem::Execute() {
     if (state == TaskTableItemState::LOADED) {
         state = TaskTableItemState::EXECUTING;
         lock.unlock();
-        timestamp.execute = get_now_timestamp();
+        timestamp.execute = get_current_timestamp();
         return true;
     }
     return false;
@@ -97,8 +91,8 @@ TaskTableItem::Executed() {
     if (state == TaskTableItemState::EXECUTING) {
         state = TaskTableItemState::EXECUTED;
         lock.unlock();
-        timestamp.executed = get_now_timestamp();
-        timestamp.finish = get_now_timestamp();
+        timestamp.executed = get_current_timestamp();
+        timestamp.finish = get_current_timestamp();
         return true;
     }
     return false;
@@ -109,7 +103,7 @@ TaskTableItem::Move() {
     if (state == TaskTableItemState::LOADED) {
         state = TaskTableItemState::MOVING;
         lock.unlock();
-        timestamp.move = get_now_timestamp();
+        timestamp.move = get_current_timestamp();
         return true;
     }
     return false;
@@ -120,8 +114,8 @@ TaskTableItem::Moved() {
     if (state == TaskTableItemState::MOVING) {
         state = TaskTableItemState::MOVED;
         lock.unlock();
-        timestamp.moved = get_now_timestamp();
-        timestamp.finish = get_now_timestamp();
+        timestamp.moved = get_current_timestamp();
+        timestamp.finish = get_current_timestamp();
         return true;
     }
     return false;
@@ -177,7 +171,7 @@ TaskTable::Put(TaskPtr task) {
     item->id = id_++;
     item->task = std::move(task);
     item->state = TaskTableItemState::START;
-    item->timestamp.start = get_now_timestamp();
+    item->timestamp.start = get_current_timestamp();
     table_.push_back(item);
     if (subscriber_) {
         subscriber_();
@@ -192,7 +186,7 @@ TaskTable::Put(std::vector<TaskPtr> &tasks) {
         item->id = id_++;
         item->task = std::move(task);
         item->state = TaskTableItemState::START;
-        item->timestamp.start = get_now_timestamp();
+        item->timestamp.start = get_current_timestamp();
         table_.push_back(item);
     }
     if (subscriber_) {
diff --git a/cpp/src/scheduler/TaskTable.h b/cpp/src/scheduler/TaskTable.h
index ee6d3b56cb6a16a2e690d39c01a58a54af4b588f..f5c151f4ca72b491c3434360a69d65cbd7563007 100644
--- a/cpp/src/scheduler/TaskTable.h
+++ b/cpp/src/scheduler/TaskTable.h
@@ -40,20 +40,17 @@ struct TaskTimestamp {
 };
 
 struct TaskTableItem {
-    TaskTableItem() : id(0), state(TaskTableItemState::INVALID), mutex(), priority(0) {}
+    TaskTableItem() : id(0), state(TaskTableItemState::INVALID), mutex() {}
 
     TaskTableItem(const TaskTableItem &src)
-        : id(src.id), state(src.state), mutex(), priority(src.priority) {}
+        : id(src.id), state(src.state), mutex() {}
 
     uint64_t id; // auto increment from 0;
-    // TODO: add tag into task
     TaskPtr task; // the task;
     TaskTableItemState state; // the state;
     std::mutex mutex;
     TaskTimestamp timestamp;
 
-    uint8_t priority; // just a number, meaningless;
-
     bool
     IsFinish();
 
@@ -113,7 +110,7 @@ public:
     Get(uint64_t index);
 
     /*
-     * TODO
+     * TODO(wxyu): BIG GC
      * Remove sequence task which is DONE or MOVED from front;
      * Called by ?
      */
@@ -135,6 +132,7 @@ public:
     Size() {
         return table_.size();
     }
+
 public:
     TaskTableItemPtr &
     operator[](uint64_t index) {
@@ -225,7 +223,6 @@ public:
     Dump();
 
 private:
-    // TODO: map better ?
     std::uint64_t id_ = 0;
     mutable std::mutex id_mutex_;
     std::deque<TaskTableItemPtr> table_;
diff --git a/cpp/src/scheduler/Utils.cpp b/cpp/src/scheduler/Utils.cpp
index 074c035e8eeebd90f883263ee6bdcaec2bbe0d01..597f02b552b8109907b934a8ef50c7c571f0f44e 100644
--- a/cpp/src/scheduler/Utils.cpp
+++ b/cpp/src/scheduler/Utils.cpp
@@ -4,16 +4,17 @@
  * Proprietary and confidential.
  ******************************************************************************/
 
-#include <chrono>
 #include "Utils.h"
 
+#include <chrono>
+
+
 namespace zilliz {
 namespace milvus {
 namespace engine {
 
 uint64_t
-get_current_timestamp()
-{
+get_current_timestamp() {
     std::chrono::time_point<std::chrono::system_clock> now = std::chrono::system_clock::now();
     auto duration = now.time_since_epoch();
     auto millis = std::chrono::duration_cast<std::chrono::milliseconds>(duration).count();
diff --git a/cpp/src/scheduler/Utils.h b/cpp/src/scheduler/Utils.h
index 7a5bf1874daa24f41dbc22e1e1d99dc9877c7684..7f012bec52879789e2a0db569116bd83453d3866 100644
--- a/cpp/src/scheduler/Utils.h
+++ b/cpp/src/scheduler/Utils.h
@@ -3,6 +3,7 @@
  * Unauthorized copying of this file, via any medium is strictly prohibited.
  * Proprietary and confidential.
  ******************************************************************************/
+
 #include <cstdint>
 
 
diff --git a/cpp/src/scheduler/resource/Connection.h b/cpp/src/scheduler/resource/Connection.h
index 83c9cc529cb4094cce3a68b03beb446c9a350aa6..922cf2b437e947ac3339f77c7fc881195beab644 100644
--- a/cpp/src/scheduler/resource/Connection.h
+++ b/cpp/src/scheduler/resource/Connection.h
@@ -15,6 +15,7 @@ namespace engine {
 
 class Connection {
 public:
+    // TODO: update construct function, speed: double->uint64_t
     Connection(std::string name, double speed)
         : name_(std::move(name)), speed_(speed) {}
 
diff --git a/cpp/src/scheduler/resource/RegisterHandler.h b/cpp/src/scheduler/resource/RegisterHandler.h
deleted file mode 100644
index 02c55da1e752a0e6d9ec97a5a1efdccbca58235a..0000000000000000000000000000000000000000
--- a/cpp/src/scheduler/resource/RegisterHandler.h
+++ /dev/null
@@ -1,24 +0,0 @@
-/*******************************************************************************
- * Copyright 上海赜睿信息科技有限公司(Zilliz) - All Rights Reserved
- * Unauthorized copying of this file, via any medium is strictly prohibited.
- * Proprietary and confidential.
- ******************************************************************************/
-
-#pragma once
-
-#include <memory>
-
-namespace zilliz {
-namespace milvus {
-namespace engine {
-
-class RegisterHandler {
- public:
-    virtual void Exec() = 0;
-};
-
-using RegisterHandlerPtr = std::shared_ptr<RegisterHandler>;
-
-}
-}
-}
\ No newline at end of file
diff --git a/cpp/src/scheduler/resource/Resource.cpp b/cpp/src/scheduler/resource/Resource.cpp
index b4a6cb5b66faac3a3c7a7e73b9473675ac48fda0..9bb9b572098e938cd6ce07894d6afdd257c06808 100644
--- a/cpp/src/scheduler/resource/Resource.cpp
+++ b/cpp/src/scheduler/resource/Resource.cpp
@@ -12,7 +12,8 @@ namespace zilliz {
 namespace milvus {
 namespace engine {
 
-std::ostream &operator<<(std::ostream &out, const Resource &resource) {
+std::ostream &
+operator<<(std::ostream &out, const Resource &resource) {
     out << resource.Dump();
     return out;
 }
@@ -25,11 +26,9 @@ Resource::Resource(std::string name,
     : name_(std::move(name)),
       type_(type),
       device_id_(device_id),
-      running_(false),
       enable_loader_(enable_loader),
-      enable_executor_(enable_executor),
-      load_flag_(false),
-      exec_flag_(false) {
+      enable_executor_(enable_executor) {
+    // register subscriber in tasktable
     task_table_.RegisterSubscriber([&] {
         if (subscriber_) {
             auto event = std::make_shared<TaskTableUpdatedEvent>(shared_from_this());
@@ -38,7 +37,8 @@ Resource::Resource(std::string name,
     });
 }
 
-void Resource::Start() {
+void
+Resource::Start() {
     running_ = true;
     if (enable_loader_) {
         loader_thread_ = std::thread(&Resource::loader_function, this);
@@ -48,7 +48,8 @@ void Resource::Start() {
     }
 }
 
-void Resource::Stop() {
+void
+Resource::Stop() {
     running_ = false;
     if (enable_loader_) {
         WakeupLoader();
@@ -60,11 +61,8 @@ void Resource::Stop() {
     }
 }
 
-TaskTable &Resource::task_table() {
-    return task_table_;
-}
-
-void Resource::WakeupLoader() {
+void
+Resource::WakeupLoader() {
     {
         std::lock_guard<std::mutex> lock(load_mutex_);
         load_flag_ = true;
@@ -72,7 +70,8 @@ void Resource::WakeupLoader() {
     load_cv_.notify_one();
 }
 
-void Resource::WakeupExecutor() {
+void
+Resource::WakeupExecutor() {
     {
         std::lock_guard<std::mutex> lock(exec_mutex_);
         exec_flag_ = true;
@@ -80,6 +79,15 @@ void Resource::WakeupExecutor() {
     exec_cv_.notify_one();
 }
 
+uint64_t
+Resource::NumOfTaskToExec() {
+    uint64_t count = 0;
+    for (auto &task : task_table_) {
+        if (task->state == TaskTableItemState::LOADED) ++count;
+    }
+    return count;
+}
+
 TaskTableItemPtr Resource::pick_task_load() {
     auto indexes = task_table_.PickToLoad(10);
     for (auto index : indexes) {
@@ -156,11 +164,6 @@ void Resource::executor_function() {
     }
 }
 
-RegisterHandlerPtr Resource::GetRegisterFunc(const RegisterType &type) {
-    // construct object each time.
-    return register_table_[type]();
-}
-
 }
 }
 }
\ No newline at end of file
diff --git a/cpp/src/scheduler/resource/Resource.h b/cpp/src/scheduler/resource/Resource.h
index 9169a67cf9e79395b2b1ce2e181c7b6b0f6c8e3a..707a715691488a8e5b4f815ca4a7ecf594d86fbc 100644
--- a/cpp/src/scheduler/resource/Resource.h
+++ b/cpp/src/scheduler/resource/Resource.h
@@ -21,7 +21,6 @@
 #include "../task/Task.h"
 #include "Connection.h"
 #include "Node.h"
-#include "RegisterHandler.h"
 
 
 namespace zilliz {
@@ -35,13 +34,6 @@ enum class ResourceType {
     GPU = 2
 };
 
-enum class RegisterType {
-    START_UP,
-    ON_FINISH_TASK,
-    ON_COPY_COMPLETED,
-    ON_TASK_TABLE_UPDATED,
-};
-
 class Resource : public Node, public std::enable_shared_from_this<Resource> {
  public:
     /*
@@ -68,56 +60,51 @@ class Resource : public Node, public std::enable_shared_from_this<Resource> {
     void
     WakeupExecutor();
 
- public:
-    template<typename T>
-    void Register_T(const RegisterType &type) {
-        register_table_.emplace(type, [] { return std::make_shared<T>(); });
-    }
-
-    RegisterHandlerPtr
-    GetRegisterFunc(const RegisterType &type);
-
     inline void
     RegisterSubscriber(std::function<void(EventPtr)> subscriber) {
         subscriber_ = std::move(subscriber);
     }
 
+    inline virtual std::string
+    Dump() const {
+        return "<Resource>";
+    }
+
+ public:
     inline std::string
-    Name() const {
+    name() const {
         return name_;
     }
 
     inline ResourceType
-    Type() const {
+    type() const {
         return type_;
     }
 
     inline uint64_t
-    DeviceId() {
+    device_id() const {
         return device_id_;
     }
 
-    // TODO: better name?
+    TaskTable &
+    task_table() {
+        return task_table_;
+    }
+
+public:
     inline bool
-    HasLoader() {
+    HasLoader() const {
         return enable_loader_;
     }
 
-    // TODO: better name?
     inline bool
-    HasExecutor() {
+    HasExecutor() const {
         return enable_executor_;
     }
 
     // TODO: const
     uint64_t
-    NumOfTaskToExec() {
-        uint64_t count = 0;
-        for (auto &task : task_table_) {
-            if (task->state == TaskTableItemState::LOADED) ++count;
-        }
-        return count;
-    }
+    NumOfTaskToExec();
 
     // TODO: need double ?
     inline uint64_t
@@ -130,14 +117,6 @@ class Resource : public Node, public std::enable_shared_from_this<Resource> {
         return total_task_;
     }
 
-    TaskTable &
-    task_table();
-
-    inline virtual std::string
-    Dump() const {
-        return "<Resource>";
-    }
-
     friend std::ostream &operator<<(std::ostream &out, const Resource &resource);
 
  protected:
@@ -198,6 +177,7 @@ class Resource : public Node, public std::enable_shared_from_this<Resource> {
  protected:
     uint64_t device_id_;
     std::string name_;
+
  private:
     ResourceType type_;
 
@@ -206,17 +186,16 @@ class Resource : public Node, public std::enable_shared_from_this<Resource> {
     uint64_t total_cost_ = 0;
     uint64_t total_task_ = 0;
 
-    std::map<RegisterType, std::function<RegisterHandlerPtr()>> register_table_;
     std::function<void(EventPtr)> subscriber_ = nullptr;
 
-    bool running_;
+    bool running_ = false;
     bool enable_loader_ = true;
     bool enable_executor_ = true;
     std::thread loader_thread_;
     std::thread executor_thread_;
 
-    bool load_flag_;
-    bool exec_flag_;
+    bool load_flag_ = false;
+    bool exec_flag_ = false;
     std::mutex load_mutex_;
     std::mutex exec_mutex_;
     std::condition_variable load_cv_;
diff --git a/cpp/src/scheduler/task/DeleteTask.cpp b/cpp/src/scheduler/task/DeleteTask.cpp
index 0e9c7dc36006b2d8f0a5fd5cc5ba9ed269882ae1..69b5ed7f0504941e8d9196a93fabbeb9d6a60f8f 100644
--- a/cpp/src/scheduler/task/DeleteTask.cpp
+++ b/cpp/src/scheduler/task/DeleteTask.cpp
@@ -24,12 +24,6 @@ XDeleteTask::Execute() {
     delete_context_ptr_->ResourceDone();
 }
 
-TaskPtr
-XDeleteTask::Clone() {
-    auto task = std::make_shared<XDeleteTask>(delete_context_ptr_);
-    return task;
-}
-
 }
 }
 }
diff --git a/cpp/src/scheduler/task/DeleteTask.h b/cpp/src/scheduler/task/DeleteTask.h
index 2b2662439104ff74ec3e40d56d8053da01b7e868..4f9909081fa16c14dc88fb67b5e9f9439bfc273b 100644
--- a/cpp/src/scheduler/task/DeleteTask.h
+++ b/cpp/src/scheduler/task/DeleteTask.h
@@ -24,9 +24,6 @@ public:
     void
     Execute() override;
 
-    TaskPtr
-    Clone() override;
-
 public:
     DeleteContextPtr delete_context_ptr_;
 };
diff --git a/cpp/src/scheduler/task/SearchTask.cpp b/cpp/src/scheduler/task/SearchTask.cpp
index 3ddc2beb73af632b1289f62efff39e85f12dd326..329cb66004517debee83cfc73fd7cc2e59b9dba6 100644
--- a/cpp/src/scheduler/task/SearchTask.cpp
+++ b/cpp/src/scheduler/task/SearchTask.cpp
@@ -193,16 +193,6 @@ XSearchTask::Execute() {
     index_engine_ = nullptr;
 }
 
-TaskPtr
-XSearchTask::Clone() {
-    auto ret = std::make_shared<XSearchTask>(file_);
-    ret->index_id_ = index_id_;
-    ret->index_engine_ = index_engine_->Clone();
-    ret->search_contexts_ = search_contexts_;
-    ret->metric_l2 = metric_l2;
-    return ret;
-}
-
 Status XSearchTask::ClusterResult(const std::vector<long> &output_ids,
                                   const std::vector<float> &output_distence,
                                   uint64_t nq,
diff --git a/cpp/src/scheduler/task/SearchTask.h b/cpp/src/scheduler/task/SearchTask.h
index fb09b29d322c26c4d833a8df0a8d50de73a709cc..b45eea48dc40e456fe964661ece8f839e58c6e0d 100644
--- a/cpp/src/scheduler/task/SearchTask.h
+++ b/cpp/src/scheduler/task/SearchTask.h
@@ -23,9 +23,6 @@ public:
     void
     Execute() override;
 
-    TaskPtr
-    Clone() override;
-
 public:
     static Status ClusterResult(const std::vector<long> &output_ids,
                                 const std::vector<float> &output_distence,
diff --git a/cpp/src/scheduler/task/Task.h b/cpp/src/scheduler/task/Task.h
index 7431679e13476e70e43c3bc72d1e3f300a6ccfc1..01b2c8eb1bb3a2049e8165a551a70ca35e63de7d 100644
--- a/cpp/src/scheduler/task/Task.h
+++ b/cpp/src/scheduler/task/Task.h
@@ -68,14 +68,9 @@ public:
     virtual void
     Execute() = 0;
 
-    // TODO: dont use this method to support task move
-    virtual TaskPtr
-    Clone() = 0;
-
 public:
     Path task_path_;
     std::vector<SearchContextPtr> search_contexts_;
-    ScheduleTaskPtr task_;
     TaskType type_;
     TaskLabelPtr label_ = nullptr;
 };
diff --git a/cpp/src/scheduler/task/TaskConvert.cpp b/cpp/src/scheduler/task/TaskConvert.cpp
index 30a3a38b2665919d9cd9be1cdbb0c0038e21a3f8..e55f84f51f117f7ad0a2c2ab57671b66494833b0 100644
--- a/cpp/src/scheduler/task/TaskConvert.cpp
+++ b/cpp/src/scheduler/task/TaskConvert.cpp
@@ -21,7 +21,6 @@ TaskConvert(const ScheduleTaskPtr &schedule_task) {
             auto task = std::make_shared<XSearchTask>(load_task->file_);
             task->label() = std::make_shared<DefaultLabel>();
             task->search_contexts_ = load_task->search_contexts_;
-            task->task_ = schedule_task;
             return task;
         }
         case ScheduleTaskType::kDelete: {
diff --git a/cpp/src/scheduler/task/TestTask.cpp b/cpp/src/scheduler/task/TestTask.cpp
index 391fd06a4fa98703b9a7d6495b0c2a8783e8a8d7..15f60baa953e9fd7ffab627de3d77b27cd1282cb 100644
--- a/cpp/src/scheduler/task/TestTask.cpp
+++ b/cpp/src/scheduler/task/TestTask.cpp
@@ -27,15 +27,6 @@ TestTask::Execute() {
     done_ = true;
 }
 
-TaskPtr
-TestTask::Clone() {
-    TableFileSchemaPtr dummy = nullptr;
-    auto ret = std::make_shared<TestTask>(dummy);
-    ret->load_count_ = load_count_;
-    ret->exec_count_ = exec_count_;
-    return ret;
-}
-
 void
 TestTask::Wait() {
     std::unique_lock<std::mutex> lock(mutex_);
diff --git a/cpp/src/scheduler/task/TestTask.h b/cpp/src/scheduler/task/TestTask.h
index dce50e9fcb558018dc01fdd7fe883f9c34dc9d0d..6e969e90844d48579dd93c438a55a51ccb797969 100644
--- a/cpp/src/scheduler/task/TestTask.h
+++ b/cpp/src/scheduler/task/TestTask.h
@@ -23,9 +23,6 @@ public:
     void
     Execute() override;
 
-    TaskPtr
-    Clone() override;
-
     void
     Wait();
 
diff --git a/cpp/src/scheduler/tasklabel/TaskLabel.h b/cpp/src/scheduler/tasklabel/TaskLabel.h
index 84fd5ee77b4b16adc9b0b92c569367fdc4f34639..51602487684aa9a5627717552cd24d2a675afe3f 100644
--- a/cpp/src/scheduler/tasklabel/TaskLabel.h
+++ b/cpp/src/scheduler/tasklabel/TaskLabel.h
@@ -25,6 +25,7 @@ public:
     }
 
 protected:
+    explicit
     TaskLabel(TaskLabelType type) : type_(type) {}
 
 private: