diff --git a/compile_flags.txt b/compile_flags.txt
index cc06ba37..2b5640b4 100644
--- a/compile_flags.txt
+++ b/compile_flags.txt
@@ -1,9 +1,6 @@
 -Wall
 -W*
 
--stdlib=libc++
--std=c++17
-
 -Iinclude/
 -I3rd/cjson/include/
 -I3rd/lua_bridge/include/
diff --git a/include/pocketpy/common/config.h b/include/pocketpy/common/config.h
index 598c65a2..52e76467 100644
--- a/include/pocketpy/common/config.h
+++ b/include/pocketpy/common/config.h
@@ -1,6 +1,11 @@
 #pragma once
 // clang-format off
 
+#define PK_VERSION				"2.0.0"
+#define PK_VERSION_MAJOR            2
+#define PK_VERSION_MINOR            0
+#define PK_VERSION_PATCH            0
+
 /*************** feature settings ***************/
 
 // Whether to compile os-related modules or not
@@ -58,3 +63,8 @@
     #define PK_PLATFORM_SEP '/'
 #endif
 
+#if PK_ENABLE_THREAD
+#define PK_THREAD_LOCAL     thread_local
+#else
+#define PK_THREAD_LOCAL     static
+#endif
diff --git a/include/pocketpy/common/gil.hpp b/include/pocketpy/common/gil.hpp
deleted file mode 100644
index b858bcb5..00000000
--- a/include/pocketpy/common/gil.hpp
+++ /dev/null
@@ -1,20 +0,0 @@
-#pragma once
-
-#if PK_ENABLE_THREAD
-#define PK_THREAD_LOCAL thread_local
-#include <mutex>
-
-struct GIL {
-    inline static std::mutex _mutex;
-
-    explicit GIL() { _mutex.lock(); }
-
-    ~GIL() { _mutex.unlock(); }
-};
-
-#define PK_GLOBAL_SCOPE_LOCK() GIL _lock;
-
-#else
-#define PK_THREAD_LOCAL static
-#define PK_GLOBAL_SCOPE_LOCK()
-#endif
diff --git a/include/pocketpy/common/memorypool.h b/include/pocketpy/common/memorypool.h
new file mode 100644
index 00000000..10b4a20d
--- /dev/null
+++ b/include/pocketpy/common/memorypool.h
@@ -0,0 +1,31 @@
+#pragma once
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define kPoolExprBlockSize      128
+#define kPoolFrameBlockSize     80
+#define kPoolObjectBlockSize    80
+
+#define kPoolObjectArenaSize    (256*1024)
+#define kPoolObjectMaxBlocks    (kPoolObjectArenaSize / kPoolObjectBlockSize)
+
+void Pools_initialize();
+void Pools_finalize();
+
+void* PoolExpr_alloc();
+void PoolExpr_dealloc(void*);
+void* PoolFrame_alloc();
+void PoolFrame_dealloc(void*);
+
+void* PoolObject_alloc();
+void PoolObject_dealloc(void* p);
+void PoolObject_shrink_to_fit();
+
+void Pools_debug_info(char* buffer, int size);
+
+#ifdef __cplusplus
+}
+#endif
+
diff --git a/include/pocketpy/common/memorypool.hpp b/include/pocketpy/common/memorypool.hpp
deleted file mode 100644
index 72961d59..00000000
--- a/include/pocketpy/common/memorypool.hpp
+++ /dev/null
@@ -1,26 +0,0 @@
-#pragma once
-
-#include "pocketpy/common/gil.hpp"
-
-#include <cstddef>
-#include <cassert>
-#include <string>
-
-namespace pkpy {
-
-const inline int kPoolExprBlockSize = 128;
-const inline int kPoolFrameBlockSize = 80;
-const inline int kPoolObjectBlockSize = 80;
-
-void* PoolExpr_alloc() noexcept;
-void PoolExpr_dealloc(void*) noexcept;
-void* PoolFrame_alloc() noexcept;
-void PoolFrame_dealloc(void*) noexcept;
-
-void* PoolObject_alloc() noexcept;
-void PoolObject_dealloc(void* p) noexcept;
-void PoolObject_shrink_to_fit() noexcept;
-
-void Pools_debug_info(char* buffer, int size) noexcept;
-
-};  // namespace pkpy
diff --git a/include/pocketpy/common/str.hpp b/include/pocketpy/common/str.hpp
index ed690ff3..9faa35f8 100644
--- a/include/pocketpy/common/str.hpp
+++ b/include/pocketpy/common/str.hpp
@@ -2,7 +2,7 @@
 
 #include "pocketpy/common/sstream.h"
 #include "pocketpy/common/utils.h"
-#include "pocketpy/common/memorypool.hpp"
+#include "pocketpy/common/memorypool.h"
 #include "pocketpy/common/vector.h"
 #include "pocketpy/common/vector.hpp"
 #include "pocketpy/common/str.h"
diff --git a/include/pocketpy/common/version.h b/include/pocketpy/common/version.h
deleted file mode 100644
index b5ab8098..00000000
--- a/include/pocketpy/common/version.h
+++ /dev/null
@@ -1,7 +0,0 @@
-#pragma once
-// clang-format off
-
-#define PK_VERSION				"2.0.0"
-#define PK_VERSION_MAJOR            2
-#define PK_VERSION_MINOR            0
-#define PK_VERSION_PATCH            0
diff --git a/src/common/memorypool.c b/src/common/memorypool.c
new file mode 100644
index 00000000..ab5ef885
--- /dev/null
+++ b/src/common/memorypool.c
@@ -0,0 +1,336 @@
+#include "pocketpy/common/memorypool.h"
+#include "pocketpy/common/config.h"
+
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+#include <stdio.h>
+#include <stdbool.h>
+
+typedef struct LinkedListNode {
+    struct LinkedListNode* prev;
+    struct LinkedListNode* next;
+} LinkedListNode;
+
+typedef struct LinkedList {
+    int count;
+    LinkedListNode head;
+    LinkedListNode tail;
+} LinkedList;
+
+static void LinkedList__ctor(LinkedList* self) {
+    self->count = 0;
+    self->head.prev = NULL;
+    self->head.next = &self->tail;
+    self->tail.prev = &self->head;
+    self->tail.next = NULL;
+}
+
+static void LinkedList__push_back(LinkedList* self, LinkedListNode* node) {
+    node->prev = self->tail.prev;
+    node->next = &self->tail;
+    self->tail.prev->next = node;
+    self->tail.prev = node;
+    self->count++;
+}
+
+static void LinkedList__push_front(LinkedList* self, LinkedListNode* node) {
+    node->prev = &self->head;
+    node->next = self->head.next;
+    self->head.next->prev = node;
+    self->head.next = node;
+    self->count++;
+}
+
+static void LinkedList__pop_back(LinkedList* self) {
+    assert(self->count > 0);
+    self->tail.prev->prev->next = &self->tail;
+    self->tail.prev = self->tail.prev->prev;
+    self->count--;
+}
+
+static LinkedListNode* LinkedList__back(LinkedList* self) {
+    assert(self->count > 0);
+    return self->tail.prev;
+}
+
+static void LinkedList__erase(LinkedList* self, LinkedListNode* node) {
+    node->prev->next = node->next;
+    node->next->prev = node->prev;
+    self->count--;
+}
+
+#define LinkedList__apply(self, __STATEMENTS__) \
+    do { \
+        LinkedListNode* node = (self)->head.next; \
+        while(node != &(self)->tail) { \
+            LinkedListNode* next = node->next; \
+            __STATEMENTS__ \
+            node = next; \
+        } \
+    } while(0)
+
+typedef struct MemoryPoolBlock{
+    void* arena;
+    char data[kPoolObjectBlockSize];
+} MemoryPoolBlock;
+
+typedef struct MemoryPoolArena{
+    /* LinkedListNode */
+    LinkedListNode* prev;
+    LinkedListNode* next;
+    /* Arena */
+    MemoryPoolBlock _blocks[kPoolObjectMaxBlocks];
+    MemoryPoolBlock* _free_list[kPoolObjectMaxBlocks];
+    int _free_list_size;
+} MemoryPoolArena;
+
+typedef struct MemoryPool{
+    LinkedList _arenas;
+    LinkedList _empty_arenas;
+} MemoryPool;
+
+static void MemoryPoolArena__ctor(MemoryPoolArena* self) {
+    self->prev = NULL;
+    self->next = NULL;
+    self->_free_list_size = kPoolObjectMaxBlocks;
+    for(int i = 0; i < kPoolObjectMaxBlocks; i++) {
+        self->_blocks[i].arena = self;
+        self->_free_list[i] = &self->_blocks[i];
+    }
+}
+
+static bool MemoryPoolArena__empty(MemoryPoolArena* self) {
+    return self->_free_list_size == 0;
+}
+
+static bool MemoryPoolArena__full(MemoryPoolArena* self) {
+    return self->_free_list_size == kPoolObjectMaxBlocks;
+}
+
+static int MemoryPoolArena__total_bytes(MemoryPoolArena* self) {
+    return kPoolObjectBlockSize * kPoolObjectMaxBlocks;
+}
+
+static int MemoryPoolArena__used_bytes(MemoryPoolArena* self) {
+    return kPoolObjectBlockSize * (kPoolObjectMaxBlocks - self->_free_list_size);
+}
+
+static MemoryPoolBlock* MemoryPoolArena__alloc(MemoryPoolArena* self) {
+    assert(!MemoryPoolArena__empty(self));
+    self->_free_list_size--;
+    return self->_free_list[self->_free_list_size];
+}
+
+static void MemoryPoolArena__dealloc(MemoryPoolArena* self, MemoryPoolBlock* block) {
+    assert(!MemoryPoolArena__full(self));
+    self->_free_list[self->_free_list_size] = block;
+    self->_free_list_size++;
+}
+
+static void MemoryPool__ctor(MemoryPool* self) {
+    LinkedList__ctor(&self->_arenas);
+    LinkedList__ctor(&self->_empty_arenas);
+}
+
+static void* MemoryPool__alloc(MemoryPool* self) {
+    MemoryPoolArena* arena;
+    if(self->_arenas.count == 0){
+        arena = malloc(sizeof(MemoryPoolArena));
+        MemoryPoolArena__ctor(arena);
+        LinkedList__push_back(&self->_arenas, (LinkedListNode*)arena);
+    } else {
+        arena = (MemoryPoolArena*)LinkedList__back(&self->_arenas);
+    }
+    void* p = MemoryPoolArena__alloc(arena)->data;
+    if(MemoryPoolArena__empty(arena)) {
+        LinkedList__pop_back(&self->_arenas);
+        LinkedList__push_back(&self->_empty_arenas, (LinkedListNode*)arena);
+    }
+    return p;
+}
+
+static void MemoryPool__dealloc(MemoryPool* self, void* p) {
+    assert(p != NULL);
+    MemoryPoolBlock* block = (MemoryPoolBlock*)((char*)p - sizeof(void*));
+    assert(block->arena != NULL);
+    MemoryPoolArena* arena = (MemoryPoolArena*)block->arena;
+    if(MemoryPoolArena__empty(arena)) {
+        LinkedList__erase(&self->_empty_arenas, (LinkedListNode*)arena);
+        LinkedList__push_front(&self->_arenas, (LinkedListNode*)arena);
+    }
+    MemoryPoolArena__dealloc(arena, block);
+}
+
+static void MemoryPool__shrink_to_fit(MemoryPool* self) {
+    const int MIN_ARENA_COUNT = PK_GC_MIN_THRESHOLD * 100 / (kPoolObjectArenaSize);
+    if(self->_arenas.count < MIN_ARENA_COUNT) return;
+    LinkedList__apply(&self->_arenas,
+            MemoryPoolArena* arena = (MemoryPoolArena*)node;
+            if(MemoryPoolArena__full(arena)) {
+                LinkedList__erase(&self->_arenas, node);
+                free(arena);
+            });
+}
+
+
+static void MemoryPool__dtor(MemoryPool* self) {
+    LinkedList__apply(&self->_arenas, free(node););
+    LinkedList__apply(&self->_empty_arenas, free(node););
+}
+
+typedef struct FixedMemoryPool {
+    int BlockSize;
+    int BlockCount;
+
+    char* data;
+    char* data_end;
+    int exceeded_bytes;
+
+    char** _free_list;
+    char** _free_list_end;
+} FixedMemoryPool;
+
+static void FixedMemoryPool__ctor(FixedMemoryPool* self, int BlockSize, int BlockCount) {
+    self->BlockSize = BlockSize;
+    self->BlockCount = BlockCount;
+    self->exceeded_bytes = 0;
+    self->data = malloc(BlockSize * BlockCount);
+    self->data_end = self->data + BlockSize * BlockCount;
+    self->_free_list = malloc(sizeof(void*) * BlockCount);
+    self->_free_list_end = self->_free_list;
+    for(int i = 0; i < BlockCount; i++) {
+        self->_free_list[i] = self->data + i * BlockSize;
+    }
+}
+
+static void FixedMemoryPool__dtor(FixedMemoryPool* self) {
+    free(self->_free_list);
+    free(self->data);
+}
+
+static void* FixedMemoryPool__alloc(FixedMemoryPool* self) {
+    if(self->_free_list_end != self->_free_list) {
+        self->_free_list_end--;
+        return *self->_free_list_end;
+    } else {
+        self->exceeded_bytes += self->BlockSize;
+        return malloc(self->BlockSize);
+    }
+}
+
+static void FixedMemoryPool__dealloc(FixedMemoryPool* self, void* p) {
+    bool is_valid = (char*)p >= self->data && (char*)p < self->data_end;
+    if(is_valid) {
+        *self->_free_list_end = p;
+        self->_free_list_end++;
+    } else {
+        self->exceeded_bytes -= self->BlockSize;
+        free(p);
+    }
+}
+
+static int FixedMemoryPool__used_bytes(FixedMemoryPool* self) {
+    return (self->_free_list_end - self->_free_list) * self->BlockSize;
+}
+
+static int FixedMemoryPool__total_bytes(FixedMemoryPool* self) {
+    return self->BlockCount * self->BlockSize;
+}
+
+PK_THREAD_LOCAL FixedMemoryPool PoolExpr;
+PK_THREAD_LOCAL FixedMemoryPool PoolFrame;
+PK_THREAD_LOCAL MemoryPool PoolObject;
+PK_THREAD_LOCAL bool initialized = false;
+
+void Pools_initialize(){
+    if(initialized) return;
+    FixedMemoryPool__ctor(&PoolExpr, kPoolExprBlockSize, 64);
+    FixedMemoryPool__ctor(&PoolFrame, kPoolFrameBlockSize, 128);
+    MemoryPool__ctor(&PoolObject);
+    initialized = true;
+}
+
+void Pools_finalize(){
+    if(!initialized) return;
+    FixedMemoryPool__dtor(&PoolExpr);
+    FixedMemoryPool__dtor(&PoolFrame);
+    MemoryPool__dtor(&PoolObject);
+    initialized = false;
+}
+
+void* PoolExpr_alloc() {
+    assert(initialized);
+    return FixedMemoryPool__alloc(&PoolExpr);
+}
+
+void PoolExpr_dealloc(void* p) {
+    assert(initialized);
+    FixedMemoryPool__dealloc(&PoolExpr, p);
+}
+
+void* PoolFrame_alloc() {
+    assert(initialized);
+    return FixedMemoryPool__alloc(&PoolFrame);
+}
+
+void PoolFrame_dealloc(void* p) {
+    assert(initialized);
+    FixedMemoryPool__dealloc(&PoolFrame, p);
+}
+
+void* PoolObject_alloc() {
+    assert(initialized);
+    return MemoryPool__alloc(&PoolObject);
+}
+
+void PoolObject_dealloc(void* p) {
+    assert(initialized);
+    MemoryPool__dealloc(&PoolObject, p);
+}
+
+void PoolObject_shrink_to_fit() {
+    assert(initialized);
+    MemoryPool__shrink_to_fit(&PoolObject);
+}
+
+void Pools_debug_info(char* buffer, int size) {
+    double BYTES_PER_MB = 1024.0f * 1024.0f;
+    double BYTES_PER_KB = 1024.0f;
+    int n = 0;
+    n = snprintf(
+        buffer, size,  "PoolExpr: %.2f KB (used) / %.2f KB (total) - %.2f KB (exceeded)\n",
+        FixedMemoryPool__used_bytes(&PoolExpr) / BYTES_PER_KB,
+        FixedMemoryPool__total_bytes(&PoolExpr) / BYTES_PER_KB,
+        PoolExpr.exceeded_bytes / BYTES_PER_KB
+    );
+    buffer += n; size -= n;
+    n = snprintf(
+        buffer, size, "PoolFrame: %.2f KB (used) / %.2f KB (total) - %.2f KB (exceeded)\n",
+        FixedMemoryPool__used_bytes(&PoolFrame) / BYTES_PER_KB,
+        FixedMemoryPool__total_bytes(&PoolFrame) / BYTES_PER_KB,
+        PoolFrame.exceeded_bytes / BYTES_PER_KB
+    );
+    buffer += n; size -= n;
+    // PoolObject
+    int empty_arenas = PoolObject._empty_arenas.count;
+    int arenas = PoolObject._arenas.count;
+    // print empty arenas count
+    n = snprintf(
+        buffer, size, "PoolObject: %d empty arenas, %d arenas\n",
+        empty_arenas, arenas
+    );
+    buffer += n; size -= n;
+    // log each non-empty arena
+    LinkedList__apply(&PoolObject._arenas,
+        MemoryPoolArena* arena = (MemoryPoolArena*)node;
+        n = snprintf(
+            buffer, size, "  - %p: %.2f MB (used) / %.2f MB (total)\n",
+            (void*)arena,
+            MemoryPoolArena__used_bytes(arena) / BYTES_PER_MB,
+            MemoryPoolArena__total_bytes(arena) / BYTES_PER_MB
+        );
+        buffer += n; size -= n;
+    );
+}
+
diff --git a/src/common/memorypool.cpp b/src/common/memorypool.cpp
deleted file mode 100644
index edb72adc..00000000
--- a/src/common/memorypool.cpp
+++ /dev/null
@@ -1,297 +0,0 @@
-#include "pocketpy/common/memorypool.hpp"
-#include "pocketpy/common/config.h"
-
-#include <cstdlib>
-#include <cstring>
-#include <cassert>
-
-namespace pkpy {
-
-struct LinkedListNode {
-    LinkedListNode* prev;
-    LinkedListNode* next;
-};
-
-template <typename T>
-struct DoubleLinkedList {
-    static_assert(std::is_base_of_v<LinkedListNode, T>);
-    int _size;
-    LinkedListNode head;
-    LinkedListNode tail;
-
-    DoubleLinkedList() : _size(0) {
-        head.prev = nullptr;
-        head.next = &tail;
-        tail.prev = &head;
-        tail.next = nullptr;
-    }
-
-    void push_back(T* node) {
-        node->prev = tail.prev;
-        node->next = &tail;
-        tail.prev->next = node;
-        tail.prev = node;
-        _size++;
-    }
-
-    void push_front(T* node) {
-        node->prev = &head;
-        node->next = head.next;
-        head.next->prev = node;
-        head.next = node;
-        _size++;
-    }
-
-    void pop_back() {
-        assert(!empty());
-        tail.prev->prev->next = &tail;
-        tail.prev = tail.prev->prev;
-        _size--;
-    }
-
-    void pop_front() {
-        assert(!empty());
-        head.next->next->prev = &head;
-        head.next = head.next->next;
-        _size--;
-    }
-
-    T* back() const {
-        assert(!empty());
-        return static_cast<T*>(tail.prev);
-    }
-
-    T* front() const {
-        assert(!empty());
-        return static_cast<T*>(head.next);
-    }
-
-    void erase(T* node) {
-        node->prev->next = node->next;
-        node->next->prev = node->prev;
-        _size--;
-    }
-
-    bool empty() const { return _size == 0; }
-
-    int size() const { return _size; }
-
-    template <typename Func>
-    void apply(Func func) {
-        LinkedListNode* p = head.next;
-        while(p != &tail) {
-            LinkedListNode* next = p->next;
-            func(static_cast<T*>(p));
-            p = next;
-        }
-    }
-};
-
-struct MemoryPool {
-    const static int __BlockSize = kPoolObjectBlockSize;
-    const static int __MaxBlocks = 256 * 1024 / __BlockSize;
-    const static int __MinArenaCount = PK_GC_MIN_THRESHOLD * 100 / (256 * 1024);
-
-    struct Block {
-        void* arena;
-        char data[__BlockSize];
-    };
-
-    struct Arena : LinkedListNode {
-        Block _blocks[__MaxBlocks];
-        Block* _free_list[__MaxBlocks];
-        int _free_list_size;
-
-        Arena() : _free_list_size(__MaxBlocks) {
-            for(int i = 0; i < __MaxBlocks; i++) {
-                _blocks[i].arena = this;
-                _free_list[i] = &_blocks[i];
-            }
-        }
-
-        bool empty() const { return _free_list_size == 0; }
-
-        bool full() const { return _free_list_size == __MaxBlocks; }
-
-        int total_bytes() const { return __BlockSize * __MaxBlocks; }
-        int used_bytes() const { return __BlockSize * (__MaxBlocks - _free_list_size); }
-
-        Block* alloc() {
-            assert(!empty());
-            _free_list_size--;
-            return _free_list[_free_list_size];
-        }
-
-        void dealloc(Block* block) {
-            assert(!full());
-            _free_list[_free_list_size] = block;
-            _free_list_size++;
-        }
-    };
-
-    MemoryPool() = default;
-    MemoryPool(const MemoryPool&) = delete;
-    MemoryPool& operator= (const MemoryPool&) = delete;
-    MemoryPool(MemoryPool&&) = delete;
-    MemoryPool& operator= (MemoryPool&&) = delete;
-
-    DoubleLinkedList<Arena> _arenas;
-    DoubleLinkedList<Arena> _empty_arenas;
-
-    void* alloc() {
-        PK_GLOBAL_SCOPE_LOCK();
-        if(_arenas.empty()) { _arenas.push_back(new Arena()); }
-        Arena* arena = _arenas.back();
-        void* p = arena->alloc()->data;
-        if(arena->empty()) {
-            _arenas.pop_back();
-            _empty_arenas.push_back(arena);
-        }
-        return p;
-    }
-
-    void dealloc(void* p) {
-        PK_GLOBAL_SCOPE_LOCK();
-        assert(p != nullptr);
-        Block* block = (Block*)((char*)p - sizeof(void*));
-        assert(block->arena != nullptr);
-        Arena* arena = (Arena*)block->arena;
-        if(arena->empty()) {
-            _empty_arenas.erase(arena);
-            _arenas.push_front(arena);
-            arena->dealloc(block);
-        } else {
-            arena->dealloc(block);
-        }
-    }
-
-    void shrink_to_fit() {
-        PK_GLOBAL_SCOPE_LOCK();
-        if(_arenas.size() < __MinArenaCount) return;
-        _arenas.apply([this](Arena* arena) {
-            if(arena->full()) {
-                _arenas.erase(arena);
-                delete arena;
-            }
-        });
-    }
-
-    ~MemoryPool() {
-        _arenas.apply([](Arena* arena) {
-            delete arena;
-        });
-        _empty_arenas.apply([](Arena* arena) {
-            delete arena;
-        });
-    }
-};
-
-template <int BlockSize, int BlockCount>
-struct FixedMemoryPool {
-    struct Block {
-        char data[BlockSize];
-    };
-
-    static_assert(BlockSize % 4 == 0);
-    static_assert(sizeof(Block) == BlockSize);
-
-    Block _blocks[BlockCount];
-    Block* _free_list[BlockCount];
-    Block** _free_list_end;
-    int _exceeded_bytes;
-
-    int total_bytes() const { return BlockSize * BlockCount; }
-    int used_bytes() const { return (BlockCount - (_free_list_end - _free_list)) * BlockSize; }
-    int exceeded_bytes() const { return _exceeded_bytes; }
-
-    FixedMemoryPool() {
-        _exceeded_bytes = 0;
-        _free_list_end = _free_list + BlockCount;
-        for(int i = 0; i < BlockCount; ++i) {
-            _free_list[i] = _blocks + i;
-        }
-    }
-
-    bool is_valid(void* p) { return p >= _blocks && p < _blocks + BlockCount; }
-
-    void* alloc() {
-        PK_GLOBAL_SCOPE_LOCK()
-        if(_free_list_end != _free_list) {
-            --_free_list_end;
-            return *_free_list_end;
-        } else {
-            _exceeded_bytes += BlockSize;
-            return std::malloc(BlockSize);
-        }
-    }
-
-    void dealloc(void* p) {
-        PK_GLOBAL_SCOPE_LOCK()
-        if(is_valid(p)) {
-            *_free_list_end = static_cast<Block*>(p);
-            ++_free_list_end;
-        } else {
-            _exceeded_bytes -= BlockSize;
-            std::free(p);
-        }
-    }
-};
-
-static FixedMemoryPool<kPoolExprBlockSize, 64> PoolExpr;
-static FixedMemoryPool<kPoolFrameBlockSize, 128> PoolFrame;
-static MemoryPool PoolObject;
-
-void* PoolExpr_alloc() noexcept { return PoolExpr.alloc(); }
-
-void PoolExpr_dealloc(void* p) noexcept { PoolExpr.dealloc(p); }
-
-void* PoolFrame_alloc() noexcept { return PoolFrame.alloc(); }
-
-void PoolFrame_dealloc(void* p) noexcept { PoolFrame.dealloc(p); }
-
-void* PoolObject_alloc() noexcept { return PoolObject.alloc(); }
-
-void PoolObject_dealloc(void* p) noexcept { PoolObject.dealloc(p); }
-
-void PoolObject_shrink_to_fit() noexcept { PoolObject.shrink_to_fit(); }
-
-void Pools_debug_info(char* buffer, int size) noexcept {
-    double BYTES_PER_MB = 1024.0f * 1024.0f;
-    double BYTES_PER_KB = 1024.0f;
-    int n = 0;
-    n = snprintf(
-        buffer, size,  "PoolExpr: %.2f KB (used) / %.2f KB (total) - %.2f KB (exceeded)\n",
-        PoolExpr.used_bytes() / BYTES_PER_KB,
-        PoolExpr.total_bytes() / BYTES_PER_KB,
-        PoolExpr.exceeded_bytes() / BYTES_PER_KB
-    );
-    buffer += n; size -= n;
-    n = snprintf(
-        buffer, size, "PoolFrame: %.2f KB (used) / %.2f KB (total) - %.2f KB (exceeded)\n",
-        PoolFrame.used_bytes() / BYTES_PER_KB,
-        PoolFrame.total_bytes() / BYTES_PER_KB,
-        PoolFrame.exceeded_bytes() / BYTES_PER_KB
-    );
-    buffer += n; size -= n;
-    // PoolObject
-    int empty_arenas = PoolObject._empty_arenas.size();
-    int arenas = PoolObject._arenas.size();
-    // print empty arenas count
-    n = snprintf(
-        buffer, size, "PoolObject: %d empty arenas, %d arenas\n",
-        empty_arenas, arenas
-    );
-    buffer += n; size -= n;
-    // log each non-empty arena
-    PoolObject._arenas.apply([&](MemoryPool::Arena* arena) {
-        n = snprintf(
-            buffer, size, "  - %p: %.2f MB (used) / %.2f MB (total)\n",
-            (void*)arena,
-            arena->used_bytes() / BYTES_PER_MB,
-            arena->total_bytes() / BYTES_PER_MB
-        );
-        buffer += n; size -= n;
-    });
-}
-
-}  // namespace pkpy
diff --git a/src/common/str.cpp b/src/common/str.cpp
index 2d14136b..e5ee73cc 100644
--- a/src/common/str.cpp
+++ b/src/common/str.cpp
@@ -1,5 +1,4 @@
 #include "pocketpy/common/str.hpp"
-#include "pocketpy/common/gil.hpp"
 
 #include <cassert>
 #include <ostream>
@@ -39,7 +38,7 @@ const char* StrName::c_str() const { return _r_interned()[index].c_str(); }
 uint32_t StrName::_pesudo_random_index = 0;
 
 StrName StrName::get(std::string_view s) {
-    PK_GLOBAL_SCOPE_LOCK()
+    // TODO: PK_GLOBAL_SCOPE_LOCK()
     auto it = _interned().find(s);
     if(it != _interned().end()) return StrName(it->second);
     // generate new index
diff --git a/src/compiler/lexer.cpp b/src/compiler/lexer.cpp
index 0b3f1a35..e53670bc 100644
--- a/src/compiler/lexer.cpp
+++ b/src/compiler/lexer.cpp
@@ -1,6 +1,5 @@
 #include "pocketpy/compiler/lexer.hpp"
-#include "pocketpy/common/gil.hpp"
-#include "pocketpy/common/version.h"
+#include "pocketpy/common/config.h"
 #include "pocketpy/common/str.h"
 
 #include <cstdarg>
diff --git a/src/interpreter/vm.cpp b/src/interpreter/vm.cpp
index 40ca619b..148663b5 100644
--- a/src/interpreter/vm.cpp
+++ b/src/interpreter/vm.cpp
@@ -1,4 +1,5 @@
 #include "pocketpy/interpreter/vm.hpp"
+#include "pocketpy/common/memorypool.h"
 
 #include <iostream>
 #include <cmath>
@@ -81,6 +82,8 @@ struct JsonSerializer {
 };
 
 VM::VM(bool enable_os) : heap(this), enable_os(enable_os) {
+    Pools_initialize();
+    
     this->vm = this;
     this->__c.error = nullptr;
     _ceval_on_step = nullptr;
diff --git a/src/modules/modules.cpp b/src/modules/modules.cpp
index bd2a2388..a81634b5 100644
--- a/src/modules/modules.cpp
+++ b/src/modules/modules.cpp
@@ -1,6 +1,5 @@
 #include "pocketpy/modules/modules.hpp"
 #include "pocketpy/interpreter/bindings.hpp"
-#include "pocketpy/common/version.h"
 #include "pocketpy/common/export.h"
 
 #include "pocketpy/common/_generated.h"
diff --git a/src/tools/repl.cpp b/src/tools/repl.cpp
index 9758653a..dff4beb2 100644
--- a/src/tools/repl.cpp
+++ b/src/tools/repl.cpp
@@ -1,6 +1,4 @@
 #include "pocketpy/tools/repl.hpp"
-
-#include "pocketpy/common/version.h"
 #include "pocketpy/common/export.h"
 
 namespace pkpy {