Memory pool in C++ memory management

Memory pool is a C technology for managing frequently allocated and freed objects of a specific size. It uses pre-allocated blocks of memory, providing higher performance than standard memory allocators, especially for highly concurrent applications.

Memory pool in C memory management

Memory pool is a C technology used to optimize memory allocation and management. It preallocates a memory area for similar-sized objects that are frequently allocated and freed. Memory pools can significantly improve performance compared to standard memory allocators, especially in highly concurrent applications.

How the memory pool works

The working principle of the memory pool is that it allocates a large block of memory during initialization. This block of memory is subdivided into smaller chunks that can be allocated and freed individually. When an object needs to be allocated, the memory pool allocates one from the pre-allocated chunks, and if all chunks are used up, it allocates new chunks.

Create a memory pool

Creating a memory pool in C is very simple. You can use the following code:

#include <cstdlib>
#include <new>

constexpr size_t BLOCK_SIZE = 1024;
constexpr size_t NUM_BLOCKS = 100;

class MemoryPool {
private:
    char* memoryBlock;
    char* freePtr;
    char* endPtr;

public:
    MemoryPool() {
        memoryBlock = new char[BLOCK_SIZE * NUM_BLOCKS];
        freePtr = memoryBlock;
        endPtr = memoryBlock + (BLOCK_SIZE * NUM_BLOCKS);
    }

    ~MemoryPool() {
        delete[] memoryBlock;
    }

    void* allocate(size_t size) {
        if (freePtr + size <= endPtr) {
            void* allocatedPtr = freePtr;
            freePtr += size;
            return allocatedPtr;
        }

        return nullptr;
    }

    void deallocate(void* ptr) {
        if (ptr >= endPtr || ptr < memoryBlock) {
            throw "Invalid pointer";
        }

        freePtr = ptr;
    }
};

Practical example

Let’s create a simple struct named Object , and then use the memory pool to allocate and release it:

struct Object {
    int id;
    std::string name;
};

int main() {
    MemoryPool pool;

    Object* object1 = static_cast<Object*>(pool.allocate(sizeof(Object)));
    object1->id = 1;
    object1->name = "Object 1";

    Object* object2 = static_cast<Object*>(pool.allocate(sizeof(Object)));
    object2->id = 2;
    object2->name = "Object 2";

    // ... 使用对象 ...

    pool.deallocate(object1);
    pool.deallocate(object2);

    return 0;
}

In this example, the memory pool is used to manage the memory allocation and release of Object objects. This improves performance because memory allocation and deallocation is done in pre-allocated memory blocks, thus avoiding the overhead of frequent system calls.

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