diff --git a/cpp/CHANGELOG.md b/cpp/CHANGELOG.md
index 3d87261868e5af6b15fa0f70126f2934328d1bd6..ec2fa17487931afe79be65d5250f2d3220882efc 100644
--- a/cpp/CHANGELOG.md
+++ b/cpp/CHANGELOG.md
@@ -93,7 +93,10 @@ Please mark all change in change log and use the ticket from JIRA.
 - MS-488 - Improve code format in scheduler
 - MS-495 - cmake: integrated knowhere
 - MS-496 - Change the top_k limitation from 1024 to 2048
+- MS-502 - Update tasktable_test in scheduler
+- MS-504 - Update node_test in scheduler
 - MS-505 - Install core unit test and add to coverage
+- MS-508 - Update normal_test in scheduler
 
 ## New Feature
 - MS-343 - Implement ResourceMgr
diff --git a/cpp/src/scheduler/Scheduler.cpp b/cpp/src/scheduler/Scheduler.cpp
index dcd17e31cfb06b9d47f5466570df74b241b19a52..c77b37648dedebbc31d1f48c09c9bf949fe8675d 100644
--- a/cpp/src/scheduler/Scheduler.cpp
+++ b/cpp/src/scheduler/Scheduler.cpp
@@ -108,6 +108,7 @@ void
 Scheduler::OnFinishTask(const EventPtr &event) {
 }
 
+// TODO: refactor the function
 void
 Scheduler::OnLoadCompleted(const EventPtr &event) {
     auto load_completed_event = std::static_pointer_cast<LoadCompletedEvent>(event);
@@ -120,18 +121,23 @@ Scheduler::OnLoadCompleted(const EventPtr &event) {
                 if (not resource->HasExecutor() && load_completed_event->task_table_item_->Move()) {
                     auto task = load_completed_event->task_table_item_->task;
                     auto search_task = std::static_pointer_cast<XSearchTask>(task);
-                    auto location = search_task->index_engine_->GetLocation();
                     bool moved = false;
 
-                    for (auto i = 0; i < res_mgr_.lock()->GetNumGpuResource(); ++i) {
-                        auto index = zilliz::milvus::cache::GpuCacheMgr::GetInstance(i)->GetIndex(location);
-                        if (index != nullptr) {
-                            moved = true;
-                            auto dest_resource = res_mgr_.lock()->GetResource(ResourceType::GPU, i);
-                            Action::PushTaskToResource(load_completed_event->task_table_item_->task, dest_resource);
-                            break;
+                    // to support test task, REFACTOR
+                    if (auto index_engine = search_task->index_engine_) {
+                        auto location = index_engine->GetLocation();
+
+                        for (auto i = 0; i < res_mgr_.lock()->GetNumGpuResource(); ++i) {
+                            auto index = zilliz::milvus::cache::GpuCacheMgr::GetInstance(i)->GetIndex(location);
+                            if (index != nullptr) {
+                                moved = true;
+                                auto dest_resource = res_mgr_.lock()->GetResource(ResourceType::GPU, i);
+                                Action::PushTaskToResource(load_completed_event->task_table_item_->task, dest_resource);
+                                break;
+                            }
                         }
                     }
+
                     if (not moved) {
                         Action::PushTaskToNeighbourRandomly(task, resource);
                     }
@@ -147,7 +153,7 @@ Scheduler::OnLoadCompleted(const EventPtr &event) {
                     // 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;
-                    std::vector<uint64_t > transport_costs;
+                    std::vector<uint64_t> transport_costs;
                     for (auto &res : compute_resources) {
                         std::vector<std::string> path;
                         uint64_t transport_cost = ShortestPath(self, res, res_mgr_.lock(), path);
@@ -176,7 +182,7 @@ 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();
diff --git a/cpp/src/scheduler/Scheduler.h b/cpp/src/scheduler/Scheduler.h
index e2d51ee31dae02268f345bc9bf8cc4ea49604bca..c2a36069b9b779b216cb88959c509dbc50755ca8 100644
--- a/cpp/src/scheduler/Scheduler.h
+++ b/cpp/src/scheduler/Scheduler.h
@@ -21,6 +21,7 @@ namespace milvus {
 namespace engine {
 
 
+// TODO: refactor, not friendly to unittest, logical in framework code
 class Scheduler {
 public:
     explicit
diff --git a/cpp/src/scheduler/TaskTable.cpp b/cpp/src/scheduler/TaskTable.cpp
index 086bf06835ca96645ebc7fa7622c8a494638b814..91d0bd7052c3022ac968eab220ea416469ac502c 100644
--- a/cpp/src/scheduler/TaskTable.cpp
+++ b/cpp/src/scheduler/TaskTable.cpp
@@ -136,7 +136,7 @@ std::vector<uint64_t>
 TaskTable::PickToLoad(uint64_t limit) {
     std::vector<uint64_t> indexes;
     bool cross = false;
-    for (uint64_t i = last_finish_, count = 0; i < table_.size() && count < limit; ++i) {
+    for (uint64_t i = last_finish_ + 1, count = 0; i < table_.size() && count < limit; ++i) {
         if (not cross && table_[i]->IsFinish()) {
             last_finish_ = i;
         } else if (table_[i]->state == TaskTableItemState::START) {
@@ -152,7 +152,7 @@ std::vector<uint64_t>
 TaskTable::PickToExecute(uint64_t limit) {
     std::vector<uint64_t> indexes;
     bool cross = false;
-    for (uint64_t i = last_finish_, count = 0; i < table_.size() && count < limit; ++i) {
+    for (uint64_t i = last_finish_ + 1, count = 0; i < table_.size() && count < limit; ++i) {
         if (not cross && table_[i]->IsFinish()) {
             last_finish_ = i;
         } else if (table_[i]->state == TaskTableItemState::LOADED) {
@@ -200,15 +200,15 @@ TaskTable::Get(uint64_t index) {
     return table_[index];
 }
 
-void
-TaskTable::Clear() {
-// find first task is NOT (done or moved), erase from begin to it;
-//        auto iterator = table_.begin();
-//        while (iterator->state == TaskTableItemState::EXECUTED or
-//            iterator->state == TaskTableItemState::MOVED)
-//            iterator++;
-//        table_.erase(table_.begin(), iterator);
-}
+//void
+//TaskTable::Clear() {
+//// find first task is NOT (done or moved), erase from begin to it;
+////        auto iterator = table_.begin();
+////        while (iterator->state == TaskTableItemState::EXECUTED or
+////            iterator->state == TaskTableItemState::MOVED)
+////            iterator++;
+////        table_.erase(table_.begin(), iterator);
+//}
 
 
 std::string
diff --git a/cpp/src/scheduler/TaskTable.h b/cpp/src/scheduler/TaskTable.h
index f5c151f4ca72b491c3434360a69d65cbd7563007..7b064f20d49b11ca7a4918e8b3798e46789b6a4e 100644
--- a/cpp/src/scheduler/TaskTable.h
+++ b/cpp/src/scheduler/TaskTable.h
@@ -40,10 +40,10 @@ struct TaskTimestamp {
 };
 
 struct TaskTableItem {
-    TaskTableItem() : id(0), state(TaskTableItemState::INVALID), mutex() {}
+    TaskTableItem() : id(0), task(nullptr), state(TaskTableItemState::INVALID), mutex() {}
 
-    TaskTableItem(const TaskTableItem &src)
-        : id(src.id), state(src.state), mutex() {}
+    TaskTableItem(const TaskTableItem &src) = delete;
+    TaskTableItem(TaskTableItem &&) = delete;
 
     uint64_t id; // auto increment from 0;
     TaskPtr task; // the task;
@@ -114,8 +114,8 @@ public:
      * Remove sequence task which is DONE or MOVED from front;
      * Called by ?
      */
-    void
-    Clear();
+//    void
+//    Clear();
 
     /*
      * Return true if task table empty, otherwise false;
@@ -229,7 +229,9 @@ private:
     std::function<void(void)> subscriber_ = nullptr;
 
     // cache last finish avoid Pick task from begin always
-    uint64_t last_finish_ = 0;
+    // pick from (last_finish_ + 1)
+    // init with -1, pick from (last_finish_ + 1) = 0
+    uint64_t last_finish_ = -1;
 };
 
 
diff --git a/cpp/src/scheduler/resource/Node.cpp b/cpp/src/scheduler/resource/Node.cpp
index 8e3db29ea2586590d0c2ce6256fa82a3c8303c45..0b322abb5755f674180f77e41bc72a8aa0f471bb 100644
--- a/cpp/src/scheduler/resource/Node.cpp
+++ b/cpp/src/scheduler/resource/Node.cpp
@@ -17,27 +17,6 @@ Node::Node() {
     id_ = counter++;
 }
 
-void Node::DelNeighbour(const NeighbourNodePtr &neighbour_ptr) {
-    std::lock_guard<std::mutex> lk(mutex_);
-    if (auto s = neighbour_ptr.lock()) {
-        auto search = neighbours_.find(s->id_);
-        if (search != neighbours_.end()) {
-            neighbours_.erase(search);
-        }
-    }
-}
-
-bool Node::IsNeighbour(const NeighbourNodePtr &neighbour_ptr) {
-    std::lock_guard<std::mutex> lk(mutex_);
-    if (auto s = neighbour_ptr.lock()) {
-        auto search = neighbours_.find(s->id_);
-        if (search != neighbours_.end()) {
-            return true;
-        }
-    }
-    return false;
-}
-
 std::vector<Neighbour> Node::GetNeighbours() {
     std::lock_guard<std::mutex> lk(mutex_);
     std::vector<Neighbour> ret;
@@ -48,8 +27,13 @@ std::vector<Neighbour> Node::GetNeighbours() {
 }
 
 std::string Node::Dump() {
-    // TODO(linxj): what's that?
-    return std::__cxx11::string();
+    std::stringstream ss;
+    ss << "<Node, id=" << std::to_string(id_) << ">::neighbours:" << std::endl;
+    for (auto &neighbour : neighbours_) {
+        ss << "\t<Neighbour, id=" << std::to_string(neighbour.first);
+        ss << ", connection: " << neighbour.second.connection.Dump() << ">" << std::endl;
+    }
+    return ss.str();
 }
 
 void Node::AddNeighbour(const NeighbourNodePtr &neighbour_node, Connection &connection) {
diff --git a/cpp/src/scheduler/resource/Node.h b/cpp/src/scheduler/resource/Node.h
index a57987ca9c91b3409ede283e982c13faaf09d8cd..568aaf93e7ceff12ba36ce04a369d26c9811fc51 100644
--- a/cpp/src/scheduler/resource/Node.h
+++ b/cpp/src/scheduler/resource/Node.h
@@ -37,12 +37,6 @@ public:
     void
     AddNeighbour(const NeighbourNodePtr &neighbour_node, Connection &connection);
 
-    void
-    DelNeighbour(const NeighbourNodePtr &neighbour_ptr);
-
-    bool
-    IsNeighbour(const NeighbourNodePtr& neighbour_ptr);
-
     std::vector<Neighbour>
     GetNeighbours();
 
diff --git a/cpp/src/scheduler/task/SearchTask.cpp b/cpp/src/scheduler/task/SearchTask.cpp
index b9448376e8e6f41af221e36c06d0d2193c29fee9..ec603ac328dad6b01256b456fb623a7c0bb85171 100644
--- a/cpp/src/scheduler/task/SearchTask.cpp
+++ b/cpp/src/scheduler/task/SearchTask.cpp
@@ -83,11 +83,14 @@ CollectFileMetrics(int file_type, size_t file_size) {
 
 XSearchTask::XSearchTask(TableFileSchemaPtr file)
     : Task(TaskType::SearchTask), file_(file) {
-    index_engine_ = EngineFactory::Build(file_->dimension_,
-                                         file_->location_,
-                                         (EngineType) file_->engine_type_,
-                                         (MetricType) file_->metric_type_,
-                                         file_->nlist_);
+    if (file_) {
+        index_engine_ = EngineFactory::Build(file_->dimension_,
+                                             file_->location_,
+                                             (EngineType) file_->engine_type_,
+                                             (MetricType) file_->metric_type_,
+                                             file_->nlist_);
+    }
+
 }
 
 void
diff --git a/cpp/src/scheduler/task/SearchTask.h b/cpp/src/scheduler/task/SearchTask.h
index b45eea48dc40e456fe964661ece8f839e58c6e0d..2370e26361b5e4ac4fb11e71263fb5b2c9a705f5 100644
--- a/cpp/src/scheduler/task/SearchTask.h
+++ b/cpp/src/scheduler/task/SearchTask.h
@@ -12,6 +12,7 @@ namespace zilliz {
 namespace milvus {
 namespace engine {
 
+// TODO: rewrite
 class XSearchTask : public Task {
 public:
     explicit
diff --git a/cpp/src/scheduler/task/Task.h b/cpp/src/scheduler/task/Task.h
index 01b2c8eb1bb3a2049e8165a551a70ca35e63de7d..53893aacaa56824b4e75406bd4a6032e3c12694e 100644
--- a/cpp/src/scheduler/task/Task.h
+++ b/cpp/src/scheduler/task/Task.h
@@ -34,6 +34,7 @@ class Task;
 
 using TaskPtr = std::shared_ptr<Task>;
 
+// TODO: re-design
 class Task {
 public:
     explicit
diff --git a/cpp/src/scheduler/task/TestTask.cpp b/cpp/src/scheduler/task/TestTask.cpp
index 15f60baa953e9fd7ffab627de3d77b27cd1282cb..1078da583fc25d89321cf64a4859150c1be73e43 100644
--- a/cpp/src/scheduler/task/TestTask.cpp
+++ b/cpp/src/scheduler/task/TestTask.cpp
@@ -13,7 +13,7 @@ namespace milvus {
 namespace engine {
 
 
-TestTask::TestTask(TableFileSchemaPtr& file) : XSearchTask(file) {}
+TestTask::TestTask(TableFileSchemaPtr &file) : XSearchTask(file) {}
 
 void
 TestTask::Load(LoadType type, uint8_t device_id) {
@@ -22,9 +22,12 @@ TestTask::Load(LoadType type, uint8_t device_id) {
 
 void
 TestTask::Execute() {
-    std::lock_guard<std::mutex> lock(mutex_);
-    exec_count_++;
-    done_ = true;
+    {
+        std::lock_guard<std::mutex> lock(mutex_);
+        exec_count_++;
+        done_ = true;
+    }
+    cv_.notify_one();
 }
 
 void
diff --git a/cpp/unittest/scheduler/node_test.cpp b/cpp/unittest/scheduler/node_test.cpp
index f0621043db9e10d198a2503c56f67634cf28760d..642bdce77352a4f8ccb46c573ba364b7cccca0c3 100644
--- a/cpp/unittest/scheduler/node_test.cpp
+++ b/cpp/unittest/scheduler/node_test.cpp
@@ -11,58 +11,71 @@ protected:
         node1_ = std::make_shared<Node>();
         node2_ = std::make_shared<Node>();
         node3_ = std::make_shared<Node>();
-        node4_ = std::make_shared<Node>();
+        isolated_node1_ = std::make_shared<Node>();
+        isolated_node2_ = std::make_shared<Node>();
 
         auto pcie = Connection("PCIe", 11.0);
 
         node1_->AddNeighbour(node2_, pcie);
+        node1_->AddNeighbour(node3_, pcie);
         node2_->AddNeighbour(node1_, pcie);
     }
 
     NodePtr node1_;
     NodePtr node2_;
     NodePtr node3_;
-    NodePtr node4_;
+    NodePtr isolated_node1_;
+    NodePtr isolated_node2_;
 };
 
 TEST_F(NodeTest, add_neighbour) {
-    ASSERT_EQ(node3_->GetNeighbours().size(), 0);
-    ASSERT_EQ(node4_->GetNeighbours().size(), 0);
+    ASSERT_EQ(isolated_node1_->GetNeighbours().size(), 0);
+    ASSERT_EQ(isolated_node2_->GetNeighbours().size(), 0);
     auto pcie = Connection("PCIe", 11.0);
-    node3_->AddNeighbour(node4_, pcie);
-    node4_->AddNeighbour(node3_, pcie);
-    ASSERT_EQ(node3_->GetNeighbours().size(), 1);
-    ASSERT_EQ(node4_->GetNeighbours().size(), 1);
+    isolated_node1_->AddNeighbour(isolated_node2_, pcie);
+    ASSERT_EQ(isolated_node1_->GetNeighbours().size(), 1);
+    ASSERT_EQ(isolated_node2_->GetNeighbours().size(), 0);
 }
 
-TEST_F(NodeTest, del_neighbour) {
-    ASSERT_EQ(node1_->GetNeighbours().size(), 1);
-    ASSERT_EQ(node2_->GetNeighbours().size(), 1);
-    ASSERT_EQ(node3_->GetNeighbours().size(), 0);
-    node1_->DelNeighbour(node2_);
-    node2_->DelNeighbour(node2_);
-    node3_->DelNeighbour(node2_);
-    ASSERT_EQ(node1_->GetNeighbours().size(), 0);
-    ASSERT_EQ(node2_->GetNeighbours().size(), 1);
-    ASSERT_EQ(node3_->GetNeighbours().size(), 0);
+TEST_F(NodeTest, repeat_add_neighbour) {
+    ASSERT_EQ(isolated_node1_->GetNeighbours().size(), 0);
+    ASSERT_EQ(isolated_node2_->GetNeighbours().size(), 0);
+    auto pcie = Connection("PCIe", 11.0);
+    isolated_node1_->AddNeighbour(isolated_node2_, pcie);
+    isolated_node1_->AddNeighbour(isolated_node2_, pcie);
+    ASSERT_EQ(isolated_node1_->GetNeighbours().size(), 1);
+    ASSERT_EQ(isolated_node2_->GetNeighbours().size(), 0);
 }
 
-TEST_F(NodeTest, is_neighbour) {
-    ASSERT_TRUE(node1_->IsNeighbour(node2_));
-    ASSERT_TRUE(node2_->IsNeighbour(node1_));
+TEST_F(NodeTest, get_neighbours) {
+    {
+        bool n2 = false, n3 = false;
+        auto node1_neighbours = node1_->GetNeighbours();
+        ASSERT_EQ(node1_neighbours.size(), 2);
+        for (auto &n : node1_neighbours) {
+            if (n.neighbour_node.lock() == node2_) n2 = true;
+            if (n.neighbour_node.lock() == node3_) n3 = true;
+        }
+        ASSERT_TRUE(n2);
+        ASSERT_TRUE(n3);
+    }
 
-    ASSERT_FALSE(node1_->IsNeighbour(node3_));
-    ASSERT_FALSE(node2_->IsNeighbour(node3_));
-    ASSERT_FALSE(node3_->IsNeighbour(node1_));
-    ASSERT_FALSE(node3_->IsNeighbour(node2_));
+    {
+        auto node2_neighbours = node2_->GetNeighbours();
+        ASSERT_EQ(node2_neighbours.size(), 1);
+        ASSERT_EQ(node2_neighbours[0].neighbour_node.lock(), node1_);
+    }
+
+    {
+        auto node3_neighbours = node3_->GetNeighbours();
+        ASSERT_EQ(node3_neighbours.size(), 0);
+    }
 }
 
-TEST_F(NodeTest, get_neighbours) {
-    auto node1_neighbours = node1_->GetNeighbours();
-    ASSERT_EQ(node1_neighbours.size(), 1);
-    ASSERT_EQ(node1_neighbours[0].neighbour_node.lock(), node2_);
+TEST_F(NodeTest, dump) {
+    std::cout << node1_->Dump();
+    ASSERT_FALSE(node1_->Dump().empty());
 
-    auto node2_neighbours = node2_->GetNeighbours();
-    ASSERT_EQ(node2_neighbours.size(), 1);
-    ASSERT_EQ(node2_neighbours[0].neighbour_node.lock(), node1_);
+    std::cout << node2_->Dump();
+    ASSERT_FALSE(node2_->Dump().empty());
 }
diff --git a/cpp/unittest/scheduler/normal_test.cpp b/cpp/unittest/scheduler/normal_test.cpp
index 576ed3ee2ab58db9e8684f20de74d0b6990a16e8..c679a356bd8d5435dc623a3c2ca6df181eb6539d 100644
--- a/cpp/unittest/scheduler/normal_test.cpp
+++ b/cpp/unittest/scheduler/normal_test.cpp
@@ -2,6 +2,7 @@
 #include "scheduler/ResourceMgr.h"
 #include "scheduler/Scheduler.h"
 #include "scheduler/task/TestTask.h"
+#include "scheduler/tasklabel/DefaultLabel.h"
 #include "scheduler/SchedInst.h"
 #include "utils/Log.h"
 #include <gtest/gtest.h>
@@ -9,48 +10,44 @@
 
 using namespace zilliz::milvus::engine;
 
-TEST(normal_test, test1) {
+
+TEST(normal_test, inst_test) {
     // ResourceMgr only compose resources, provide unified event
-//    auto res_mgr = std::make_shared<ResourceMgr>();
     auto res_mgr = ResMgrInst::GetInstance();
-    auto disk = res_mgr->Add(ResourceFactory::Create("disk", "ssd", true, false));
-    auto cpu = res_mgr->Add(ResourceFactory::Create("cpu", "CPU", 0));
-    auto gpu1 = res_mgr->Add(ResourceFactory::Create("gpu", "gpu0", false, false));
-    auto gpu2 = res_mgr->Add(ResourceFactory::Create("gpu", "gpu2", false, false));
 
-    auto IO = Connection("IO", 500.0);
-    auto PCIE = Connection("IO", 11000.0);
-    res_mgr->Connect(disk, cpu, IO);
-    res_mgr->Connect(cpu, gpu1, PCIE);
-    res_mgr->Connect(cpu, gpu2, PCIE);
+    res_mgr->Add(ResourceFactory::Create("disk", "DISK", 0, true, false));
+    res_mgr->Add(ResourceFactory::Create("cpu", "CPU", 0, true, true));
 
-    res_mgr->Start();
+    auto IO = Connection("IO", 500.0);
+    res_mgr->Connect("disk", "cpu", IO);
 
-//    auto scheduler = new Scheduler(res_mgr);
     auto scheduler = SchedInst::GetInstance();
+
+    res_mgr->Start();
     scheduler->Start();
 
     const uint64_t NUM_TASK = 1000;
     std::vector<std::shared_ptr<TestTask>> tasks;
     TableFileSchemaPtr dummy = nullptr;
 
-    for (uint64_t i = 0; i < NUM_TASK; ++i) {
-        if (auto observe = disk.lock()) {
+    auto disks = res_mgr->GetDiskResources();
+    ASSERT_FALSE(disks.empty());
+    if (auto observe = disks[0].lock()) {
+        for (uint64_t i = 0; i < NUM_TASK; ++i) {
             auto task = std::make_shared<TestTask>(dummy);
+            task->label() = std::make_shared<DefaultLabel>();
             tasks.push_back(task);
             observe->task_table().Put(task);
         }
     }
 
-    sleep(1);
+    for (auto &task : tasks) {
+        task->Wait();
+        ASSERT_EQ(task->load_count_, 1);
+        ASSERT_EQ(task->exec_count_, 1);
+    }
 
     scheduler->Stop();
     res_mgr->Stop();
 
-    auto pcpu = cpu.lock();
-    for (uint64_t i = 0; i < NUM_TASK; ++i) {
-        auto task = std::static_pointer_cast<TestTask>(pcpu->task_table()[i]->task);
-        ASSERT_EQ(task->load_count_, 1);
-        ASSERT_EQ(task->exec_count_, 1);
-    }
 }
diff --git a/cpp/unittest/scheduler/tasktable_test.cpp b/cpp/unittest/scheduler/tasktable_test.cpp
index 5a1094b0ad2cb24bb4c3bcb412d99915dbb343ef..8710aff5b55c829db1fb3a4307e713e09e35a6a5 100644
--- a/cpp/unittest/scheduler/tasktable_test.cpp
+++ b/cpp/unittest/scheduler/tasktable_test.cpp
@@ -5,30 +5,37 @@
 
 using namespace zilliz::milvus::engine;
 
+
+/************ TaskTableBaseTest ************/
+
 class TaskTableItemTest : public ::testing::Test {
 protected:
     void
     SetUp() override {
-        item1_.id = 0;
-        item1_.state = TaskTableItemState::MOVED;
-        item1_.priority = 10;
+        std::vector<TaskTableItemState> states{
+            TaskTableItemState::INVALID,
+            TaskTableItemState::START,
+            TaskTableItemState::LOADING,
+            TaskTableItemState::LOADED,
+            TaskTableItemState::EXECUTING,
+            TaskTableItemState::EXECUTED,
+            TaskTableItemState::MOVING,
+            TaskTableItemState::MOVED};
+        for (auto &state : states) {
+            auto item = std::make_shared<TaskTableItem>();
+            item->state = state;
+            items_.emplace_back(item);
+        }
     }
 
     TaskTableItem default_;
-    TaskTableItem item1_;
+    std::vector<TaskTableItemPtr> items_;
 };
 
 TEST_F(TaskTableItemTest, construct) {
     ASSERT_EQ(default_.id, 0);
+    ASSERT_EQ(default_.task, nullptr);
     ASSERT_EQ(default_.state, TaskTableItemState::INVALID);
-    ASSERT_EQ(default_.priority, 0);
-}
-
-TEST_F(TaskTableItemTest, copy) {
-    TaskTableItem another(item1_);
-    ASSERT_EQ(another.id, item1_.id);
-    ASSERT_EQ(another.state, item1_.state);
-    ASSERT_EQ(another.priority, item1_.priority);
 }
 
 TEST_F(TaskTableItemTest, destruct) {
@@ -36,6 +43,107 @@ TEST_F(TaskTableItemTest, destruct) {
     delete p_item;
 }
 
+TEST_F(TaskTableItemTest, is_finish) {
+    for (auto &item : items_) {
+        if (item->state == TaskTableItemState::EXECUTED
+            || item->state == TaskTableItemState::MOVED) {
+            ASSERT_TRUE(item->IsFinish());
+        } else {
+            ASSERT_FALSE(item->IsFinish());
+        }
+    }
+}
+
+TEST_F(TaskTableItemTest, dump) {
+    for (auto &item : items_) {
+        ASSERT_FALSE(item->Dump().empty());
+    }
+}
+
+TEST_F(TaskTableItemTest, load) {
+    for (auto &item : items_) {
+        auto before_state = item->state;
+        auto ret = item->Load();
+        if (before_state == TaskTableItemState::START) {
+            ASSERT_TRUE(ret);
+            ASSERT_EQ(item->state, TaskTableItemState::LOADING);
+        } else {
+            ASSERT_FALSE(ret);
+            ASSERT_EQ(item->state, before_state);
+        }
+    }
+}
+
+TEST_F(TaskTableItemTest, loaded) {
+    for (auto &item : items_) {
+        auto before_state = item->state;
+        auto ret = item->Loaded();
+        if (before_state == TaskTableItemState::LOADING) {
+            ASSERT_TRUE(ret);
+            ASSERT_EQ(item->state, TaskTableItemState::LOADED);
+        } else {
+            ASSERT_FALSE(ret);
+            ASSERT_EQ(item->state, before_state);
+        }
+    }
+}
+
+TEST_F(TaskTableItemTest, execute) {
+    for (auto &item : items_) {
+        auto before_state = item->state;
+        auto ret = item->Execute();
+        if (before_state == TaskTableItemState::LOADED) {
+            ASSERT_TRUE(ret);
+            ASSERT_EQ(item->state, TaskTableItemState::EXECUTING);
+        } else {
+            ASSERT_FALSE(ret);
+            ASSERT_EQ(item->state, before_state);
+        }
+    }
+}
+
+
+TEST_F(TaskTableItemTest, executed) {
+    for (auto &item : items_) {
+        auto before_state = item->state;
+        auto ret = item->Executed();
+        if (before_state == TaskTableItemState::EXECUTING) {
+            ASSERT_TRUE(ret);
+            ASSERT_EQ(item->state, TaskTableItemState::EXECUTED);
+        } else {
+            ASSERT_FALSE(ret);
+            ASSERT_EQ(item->state, before_state);
+        }
+    }
+}
+
+TEST_F(TaskTableItemTest, move) {
+    for (auto &item : items_) {
+        auto before_state = item->state;
+        auto ret = item->Move();
+        if (before_state == TaskTableItemState::LOADED) {
+            ASSERT_TRUE(ret);
+            ASSERT_EQ(item->state, TaskTableItemState::MOVING);
+        } else {
+            ASSERT_FALSE(ret);
+            ASSERT_EQ(item->state, before_state);
+        }
+    }
+}
+
+TEST_F(TaskTableItemTest, moved) {
+    for (auto &item : items_) {
+        auto before_state = item->state;
+        auto ret = item->Moved();
+        if (before_state == TaskTableItemState::MOVING) {
+            ASSERT_TRUE(ret);
+            ASSERT_EQ(item->state, TaskTableItemState::MOVED);
+        } else {
+            ASSERT_FALSE(ret);
+            ASSERT_EQ(item->state, before_state);
+        }
+    }
+}
 
 /************ TaskTableBaseTest ************/
 
@@ -55,6 +163,16 @@ protected:
     TaskTable empty_table_;
 };
 
+TEST_F(TaskTableBaseTest, subscriber) {
+    bool flag = false;
+    auto callback = [&]() {
+        flag = true;
+    };
+    empty_table_.RegisterSubscriber(callback);
+    empty_table_.Put(task1_);
+    ASSERT_TRUE(flag);
+}
+
 
 TEST_F(TaskTableBaseTest, put_task) {
     empty_table_.Put(task1_);
@@ -78,6 +196,125 @@ TEST_F(TaskTableBaseTest, put_empty_batch) {
     empty_table_.Put(tasks);
 }
 
+TEST_F(TaskTableBaseTest, empty) {
+    ASSERT_TRUE(empty_table_.Empty());
+    empty_table_.Put(task1_);
+    ASSERT_FALSE(empty_table_.Empty());
+}
+
+TEST_F(TaskTableBaseTest, size) {
+    ASSERT_EQ(empty_table_.Size(), 0);
+    empty_table_.Put(task1_);
+    ASSERT_EQ(empty_table_.Size(), 1);
+}
+
+TEST_F(TaskTableBaseTest, operator_) {
+    empty_table_.Put(task1_);
+    ASSERT_EQ(empty_table_.Get(0), empty_table_[0]);
+}
+
+TEST_F(TaskTableBaseTest, pick_to_load) {
+    const size_t NUM_TASKS = 10;
+    for (size_t i = 0; i < NUM_TASKS; ++i) {
+        empty_table_.Put(task1_);
+    }
+    empty_table_[0]->state = TaskTableItemState::MOVED;
+    empty_table_[1]->state = TaskTableItemState::EXECUTED;
+
+    auto indexes = empty_table_.PickToLoad(1);
+    ASSERT_EQ(indexes.size(), 1);
+    ASSERT_EQ(indexes[0], 2);
+}
+
+TEST_F(TaskTableBaseTest, pick_to_load_limit) {
+    const size_t NUM_TASKS = 10;
+    for (size_t i = 0; i < NUM_TASKS; ++i) {
+        empty_table_.Put(task1_);
+    }
+    empty_table_[0]->state = TaskTableItemState::MOVED;
+    empty_table_[1]->state = TaskTableItemState::EXECUTED;
+
+    auto indexes = empty_table_.PickToLoad(3);
+    ASSERT_EQ(indexes.size(), 3);
+    ASSERT_EQ(indexes[0], 2);
+    ASSERT_EQ(indexes[1], 3);
+    ASSERT_EQ(indexes[2], 4);
+}
+
+TEST_F(TaskTableBaseTest, pick_to_load_cache) {
+    const size_t NUM_TASKS = 10;
+    for (size_t i = 0; i < NUM_TASKS; ++i) {
+        empty_table_.Put(task1_);
+    }
+    empty_table_[0]->state = TaskTableItemState::MOVED;
+    empty_table_[1]->state = TaskTableItemState::EXECUTED;
+
+    // first pick, non-cache
+    auto indexes = empty_table_.PickToLoad(1);
+    ASSERT_EQ(indexes.size(), 1);
+    ASSERT_EQ(indexes[0], 2);
+
+    // second pick, iterate from 2
+    // invalid state change
+    empty_table_[1]->state = TaskTableItemState::START;
+    indexes = empty_table_.PickToLoad(1);
+    ASSERT_EQ(indexes.size(), 1);
+    ASSERT_EQ(indexes[0], 2);
+}
+
+TEST_F(TaskTableBaseTest, pick_to_execute) {
+    const size_t NUM_TASKS = 10;
+    for (size_t i = 0; i < NUM_TASKS; ++i) {
+        empty_table_.Put(task1_);
+    }
+    empty_table_[0]->state = TaskTableItemState::MOVED;
+    empty_table_[1]->state = TaskTableItemState::EXECUTED;
+    empty_table_[2]->state = TaskTableItemState::LOADED;
+
+    auto indexes = empty_table_.PickToExecute(1);
+    ASSERT_EQ(indexes.size(), 1);
+    ASSERT_EQ(indexes[0], 2);
+}
+
+TEST_F(TaskTableBaseTest, pick_to_execute_limit) {
+    const size_t NUM_TASKS = 10;
+    for (size_t i = 0; i < NUM_TASKS; ++i) {
+        empty_table_.Put(task1_);
+    }
+    empty_table_[0]->state = TaskTableItemState::MOVED;
+    empty_table_[1]->state = TaskTableItemState::EXECUTED;
+    empty_table_[2]->state = TaskTableItemState::LOADED;
+    empty_table_[3]->state = TaskTableItemState::LOADED;
+
+    auto indexes = empty_table_.PickToExecute(3);
+    ASSERT_EQ(indexes.size(), 2);
+    ASSERT_EQ(indexes[0], 2);
+    ASSERT_EQ(indexes[1], 3);
+}
+
+TEST_F(TaskTableBaseTest, pick_to_execute_cache) {
+    const size_t NUM_TASKS = 10;
+    for (size_t i = 0; i < NUM_TASKS; ++i) {
+        empty_table_.Put(task1_);
+    }
+    empty_table_[0]->state = TaskTableItemState::MOVED;
+    empty_table_[1]->state = TaskTableItemState::EXECUTED;
+    empty_table_[2]->state = TaskTableItemState::LOADED;
+
+    // first pick, non-cache
+    auto indexes = empty_table_.PickToExecute(1);
+    ASSERT_EQ(indexes.size(), 1);
+    ASSERT_EQ(indexes[0], 2);
+
+    // second pick, iterate from 2
+    // invalid state change
+    empty_table_[1]->state = TaskTableItemState::START;
+    indexes = empty_table_.PickToExecute(1);
+    ASSERT_EQ(indexes.size(), 1);
+    ASSERT_EQ(indexes[0], 2);
+}
+
+
 /************ TaskTableAdvanceTest ************/
 
 class TaskTableAdvanceTest : public ::testing::Test {
@@ -104,25 +341,116 @@ protected:
 };
 
 TEST_F(TaskTableAdvanceTest, load) {
-    table1_.Load(1);
-    table1_.Loaded(2);
+    std::vector<TaskTableItemState> before_state;
+    for (auto &task : table1_) {
+        before_state.push_back(task->state);
+    }
+
+    for (size_t i = 0; i < table1_.Size(); ++i) {
+        table1_.Load(i);
+    }
+
+    for (size_t i = 0; i < table1_.Size(); ++i) {
+        if (before_state[i] == TaskTableItemState::START) {
+            ASSERT_EQ(table1_.Get(i)->state, TaskTableItemState::LOADING);
+        } else {
+            ASSERT_EQ(table1_.Get(i)->state, before_state[i]);
+        }
+    }
+}
+
+TEST_F(TaskTableAdvanceTest, loaded) {
+    std::vector<TaskTableItemState> before_state;
+    for (auto &task : table1_) {
+        before_state.push_back(task->state);
+    }
+
+    for (size_t i = 0; i < table1_.Size(); ++i) {
+        table1_.Loaded(i);
+    }
 
-    ASSERT_EQ(table1_.Get(1)->state, TaskTableItemState::LOADING);
-    ASSERT_EQ(table1_.Get(2)->state, TaskTableItemState::LOADED);
+    for (size_t i = 0; i < table1_.Size(); ++i) {
+        if (before_state[i] == TaskTableItemState::LOADING) {
+            ASSERT_EQ(table1_.Get(i)->state, TaskTableItemState::LOADED);
+        } else {
+            ASSERT_EQ(table1_.Get(i)->state, before_state[i]);
+        }
+    }
 }
 
 TEST_F(TaskTableAdvanceTest, execute) {
-    table1_.Execute(3);
-    table1_.Executed(4);
+    std::vector<TaskTableItemState> before_state;
+    for (auto &task : table1_) {
+        before_state.push_back(task->state);
+    }
+
+    for (size_t i = 0; i < table1_.Size(); ++i) {
+        table1_.Execute(i);
+    }
 
-    ASSERT_EQ(table1_.Get(3)->state, TaskTableItemState::EXECUTING);
-    ASSERT_EQ(table1_.Get(4)->state, TaskTableItemState::EXECUTED);
+    for (size_t i = 0; i < table1_.Size(); ++i) {
+        if (before_state[i] == TaskTableItemState::LOADED) {
+            ASSERT_EQ(table1_.Get(i)->state, TaskTableItemState::EXECUTING);
+        } else {
+            ASSERT_EQ(table1_.Get(i)->state, before_state[i]);
+        }
+    }
+}
+
+TEST_F(TaskTableAdvanceTest, executed) {
+    std::vector<TaskTableItemState> before_state;
+    for (auto &task : table1_) {
+        before_state.push_back(task->state);
+    }
+
+    for (size_t i = 0; i < table1_.Size(); ++i) {
+        table1_.Executed(i);
+    }
+
+    for (size_t i = 0; i < table1_.Size(); ++i) {
+        if (before_state[i] == TaskTableItemState::EXECUTING) {
+            ASSERT_EQ(table1_.Get(i)->state, TaskTableItemState::EXECUTED);
+        } else {
+            ASSERT_EQ(table1_.Get(i)->state, before_state[i]);
+        }
+    }
 }
 
 TEST_F(TaskTableAdvanceTest, move) {
-    table1_.Move(3);
-    table1_.Moved(6);
+    std::vector<TaskTableItemState> before_state;
+    for (auto &task : table1_) {
+        before_state.push_back(task->state);
+    }
+
+    for (size_t i = 0; i < table1_.Size(); ++i) {
+        table1_.Move(i);
+    }
+
+    for (size_t i = 0; i < table1_.Size(); ++i) {
+        if (before_state[i] == TaskTableItemState::LOADED) {
+            ASSERT_EQ(table1_.Get(i)->state, TaskTableItemState::MOVING);
+        } else {
+            ASSERT_EQ(table1_.Get(i)->state, before_state[i]);
+        }
+    }
+}
 
-    ASSERT_EQ(table1_.Get(3)->state, TaskTableItemState::MOVING);
-    ASSERT_EQ(table1_.Get(6)->state, TaskTableItemState::MOVED);
+TEST_F(TaskTableAdvanceTest, moved) {
+    std::vector<TaskTableItemState> before_state;
+    for (auto &task : table1_) {
+        before_state.push_back(task->state);
+    }
+
+    for (size_t i = 0; i < table1_.Size(); ++i) {
+        table1_.Moved(i);
+    }
+
+    for (size_t i = 0; i < table1_.Size(); ++i) {
+        if (before_state[i] == TaskTableItemState::MOVING) {
+            ASSERT_EQ(table1_.Get(i)->state, TaskTableItemState::MOVED);
+        } else {
+            ASSERT_EQ(table1_.Get(i)->state, before_state[i]);
+        }
+    }
 }
+