diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index e854c3c..b4c7472 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -15,8 +15,11 @@ list (FILTER CPP_INDEX_SRCS EXCLUDE REGEX "_test.cpp")
 list (FILTER CPP_QUANTIZATION_SRCS EXCLUDE REGEX "_test.cpp")
 list (FILTER CPP_DATA_CELL_SRCS EXCLUDE REGEX "_test.cpp")
 
+file (GLOB CPP_UTILS_SRCS "*.cpp")
+list (FILTER CPP_UTILS_SRCS EXCLUDE REGEX "_test.cpp")
+
 set (VSAG_SRCS ${CPP_SRCS} ${CPP_FACTORY_SRCS} ${CPP_INDEX_SRCS}
-        ${CPP_CONJUGATE_GRAPH_SRCS} ${CPP_HNSWLIB_SRCS} ${CPP_QUANTIZATION_SRCS} ${CPP_DATA_CELL_SRCS})
+        ${CPP_CONJUGATE_GRAPH_SRCS} ${CPP_HNSWLIB_SRCS} ${CPP_QUANTIZATION_SRCS} ${CPP_DATA_CELL_SRCS} ${CPP_UTILS_SRCS})
 add_library (vsag SHARED ${VSAG_SRCS})
 add_library (vsag_static STATIC ${VSAG_SRCS})
 
diff --git a/src/utils/resource_object.h b/src/utils/resource_object.h
new file mode 100644
index 0000000..812b635
--- /dev/null
+++ b/src/utils/resource_object.h
@@ -0,0 +1,30 @@
+
+// Copyright 2024-present the vsag project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#pragma once
+
+namespace vsag {
+
+class ResourceObject {
+public:
+    ResourceObject() = default;
+
+    virtual ~ResourceObject() = default;
+
+    virtual void
+    Reset() = 0;
+};
+
+}  // namespace vsag
\ No newline at end of file
diff --git a/src/utils/resource_object_pool.h b/src/utils/resource_object_pool.h
new file mode 100644
index 0000000..3cd3d70
--- /dev/null
+++ b/src/utils/resource_object_pool.h
@@ -0,0 +1,99 @@
+
+// Copyright 2024-present the vsag project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#pragma once
+
+#include <cstdint>
+#include <functional>
+#include <memory>
+#include <mutex>
+#include <type_traits>
+
+#include "resource_object.h"
+namespace vsag {
+
+template <typename T,
+          typename = typename std::enable_if<std::is_base_of<ResourceObject, T>::value>::type>
+class ResourceObjectPool {
+public:
+    using ConstructFuncType = std::function<std::shared_ptr<T>()>;
+
+public:
+    template <typename... Args>
+    explicit ResourceObjectPool(uint64_t init_size, Args... args) {
+        this->pool_size_ = init_size;
+        this->constructor_ = [=]() -> std::shared_ptr<T> { return std::make_shared<T>(args...); };
+        this->resize(pool_size_);
+    }
+
+    void
+    SetConstructor(ConstructFuncType func) {
+        this->constructor_ = func;
+        {
+            std::unique_lock<std::mutex> lock(mutex_);
+            while (not pool_.empty()) {
+                pool_.pop_back();
+            }
+        }
+        this->resize(pool_size_);
+    }
+
+    std::shared_ptr<T>
+    GetOne() {
+        std::unique_lock<std::mutex> lock(mutex_);
+        if (pool_.empty()) {
+            return this->constructor_();
+        }
+        std::shared_ptr<T> obj = pool_.back();
+        pool_.pop_back();
+        pool_size_--;
+        obj->Reset();
+        return obj;
+    }
+
+    void
+    ReleaseOne(std::shared_ptr<T>& obj) {
+        std::unique_lock<std::mutex> lock(mutex_);
+        pool_.push_back(obj);
+        pool_size_++;
+    }
+
+    [[nodiscard]] inline uint64_t
+    GetSize() const {
+        return this->pool_size_;
+    }
+
+private:
+    inline void
+    resize(uint64_t size) {
+        std::unique_lock<std::mutex> lock(mutex_);
+        int count = size - pool_.size();
+        while (count > 0) {
+            pool_.emplace_back(this->constructor_());
+            --count;
+        }
+        while (count < 0) {
+            pool_.pop_back();
+            ++count;
+        }
+    }
+
+    std::vector<std::shared_ptr<T>> pool_{};
+    size_t pool_size_{0};
+    ConstructFuncType constructor_{nullptr};
+    std::mutex mutex_;
+};
+
+}  // namespace vsag
\ No newline at end of file
diff --git a/src/utils/visited_list.h b/src/utils/visited_list.h
new file mode 100644
index 0000000..2bd253d
--- /dev/null
+++ b/src/utils/visited_list.h
@@ -0,0 +1,80 @@
+
+// Copyright 2024-present the vsag project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#pragma once
+#include <cstring>
+#include <limits>
+
+#include "resource_object.h"
+#include "resource_object_pool.h"
+#include "typing.h"
+#include "vsag/allocator.h"
+
+namespace vsag {
+
+class VisitedList : public ResourceObject {
+public:
+    using VisitedListType = uint16_t;
+
+public:
+    explicit VisitedList(InnerIdType max_size, Allocator* allocator)
+        : max_size_(max_size), allocator_(allocator) {
+        this->list_ = reinterpret_cast<VisitedListType*>(
+            allocator_->Allocate((uint64_t)max_size * sizeof(VisitedListType)));
+        memset(list_, 0, max_size_ * sizeof(VisitedListType));
+        tag_ = 1;
+    }
+
+    ~VisitedList() override {
+        allocator_->Deallocate(list_);
+    }
+
+    inline void
+    Set(const InnerIdType& id) {
+        this->list_[id] = this->tag_;
+    }
+
+    inline bool
+    Get(const InnerIdType& id) {
+        return this->list_[id] == this->tag_;
+    }
+
+    inline void
+    Prefetch(const InnerIdType& id) {
+        return;  // TODO(LHT) implement
+    }
+
+    void
+    Reset() override {
+        if (tag_ == std::numeric_limits<VisitedListType>::max()) {
+            memset(list_, 0, max_size_ * sizeof(VisitedListType));
+            tag_ = 0;
+        }
+        ++tag_;
+    }
+
+private:
+    Allocator* const allocator_{nullptr};
+
+    VisitedListType* list_{nullptr};
+
+    VisitedListType tag_{1};
+
+    const InnerIdType max_size_{0};
+};
+
+using VisitedListPool = ResourceObjectPool<VisitedList>;
+
+}  // namespace vsag
\ No newline at end of file
diff --git a/src/utils/visited_list_test.cpp b/src/utils/visited_list_test.cpp
new file mode 100644
index 0000000..3aeadbf
--- /dev/null
+++ b/src/utils/visited_list_test.cpp
@@ -0,0 +1,133 @@
+
+// Copyright 2024-present the vsag project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "visited_list.h"
+
+#include <thread>
+
+#include "catch2/catch_test_macros.hpp"
+#include "default_allocator.h"
+using namespace vsag;
+
+TEST_CASE("test visited_list basic", "[ut][visited_list]") {
+    auto allocator = std::make_shared<DefaultAllocator>();
+    auto size = 10000;
+    auto vl_ptr = std::make_shared<VisitedList>(size, allocator.get());
+
+    SECTION("test set & get normal") {
+        int count = 500;
+        std::unordered_set<InnerIdType> ids;
+        for (int i = 0; i < count; ++i) {
+            auto id = random() % size;
+            ids.insert(id);
+            vl_ptr->Set(id);
+        }
+        for (auto& id : ids) {
+            REQUIRE(vl_ptr->Get(id));
+        }
+
+        for (int i = 0; i < size; ++i) {
+            if (ids.count(i) == 0) {
+                REQUIRE(not vl_ptr->Get(i));
+            }
+        }
+    }
+
+    SECTION("test reset") {
+        int count = 500;
+        std::unordered_set<InnerIdType> ids;
+        for (int i = 0; i < count; ++i) {
+            auto id = random() % size;
+            ids.insert(id);
+            vl_ptr->Set(id);
+        }
+        vl_ptr->Reset();
+        for (auto& id : ids) {
+            REQUIRE(not vl_ptr->Get(id));
+        }
+    }
+}
+
+TEST_CASE("test visited_list_pool basic", "[ut][visited_list_pool]") {
+    auto allocator = std::make_shared<DefaultAllocator>();
+    auto init_size = 10;
+    auto vl_size = 1000;
+    auto pool = std::make_shared<VisitedListPool>(init_size, vl_size, allocator.get());
+
+    auto TestVL = [&](std::shared_ptr<VisitedList>& vl_ptr) {
+        int count = 500;
+        std::unordered_set<InnerIdType> ids;
+        for (int i = 0; i < count; ++i) {
+            auto id = random() % vl_size;
+            ids.insert(id);
+            vl_ptr->Set(id);
+        }
+        for (auto& id : ids) {
+            REQUIRE(vl_ptr->Get(id) == true);
+        }
+
+        for (InnerIdType i = 0; i < vl_size; ++i) {
+            if (ids.count(i) == 0) {
+                REQUIRE(vl_ptr->Get(i) == false);
+            }
+        }
+    };
+
+    SECTION("test basic") {
+        std::vector<std::shared_ptr<VisitedList>> lists;
+        REQUIRE(pool->GetSize() == init_size);
+        lists.reserve(init_size * 2);
+        for (auto i = 0; i < init_size * 2; ++i) {
+            lists.emplace_back(pool->GetOne());
+        }
+        REQUIRE(pool->GetSize() == 0);
+        for (auto& ptr : lists) {
+            pool->ReleaseOne(ptr);
+        }
+        REQUIRE(pool->GetSize() == init_size * 2);
+
+        auto ptr = pool->GetOne();
+        REQUIRE(pool->GetSize() == init_size * 2 - 1);
+        TestVL(ptr);
+    }
+
+    SECTION("test concurrency") {
+        auto func = [&]() {
+            int count = 10;
+            int max_operators = 20;
+            std::vector<std::shared_ptr<VisitedList>> results;
+            for (int i = 0; i < count; ++i) {
+                auto opt = random() % max_operators + 1;
+                for (auto j = 0; j < opt; ++j) {
+                    results.emplace_back(pool->GetOne());
+                }
+                auto test = results[random() % opt];
+                TestVL(test);
+                for (auto& result : results) {
+                    pool->ReleaseOne(result);
+                }
+                results.clear();
+            }
+        };
+        std::vector<std::shared_ptr<std::thread>> ths;
+        auto thread_count = 2;
+        for (auto i = 0; i < thread_count; ++i) {
+            ths.emplace_back((std::make_shared<std::thread>(func)));
+        }
+        for (auto& thread : ths) {
+            thread->join();
+        }
+    }
+}
\ No newline at end of file