Dirty marking technology in C++ memory management

Dirty marking technology is a technique to optimize memory management. It appends a "dirty" flag to an object when it is allocated, indicating whether the object has been modified. When an object is released, if the dirty flag indicates that the object has been modified, memory needs to be reallocated to save the changes; otherwise, the object can be released directly.

Dirty marking technology in C++ memory management

Dirty marking technology is a technique used to optimize memory management, which can significantly reduce reallocation The number of memory operations, thereby improving program performance.

Principle

The working principle of dirty marking technology is to append a "dirty" flag when the object is allocated. This flag indicates that the object has been modified. When an object needs to be released, the dirty flag is checked to determine whether the object has been modified. If the object has been modified, memory needs to be reallocated to save the changes; otherwise, the object can be released directly without reallocating memory.

Practical case

The following is a C++ code example using dirty mark technology:

#include <vector>

class MyObject {
public:
  MyObject() : _dirty(false) {}

  void setDirty() { _dirty = true; }

  bool isDirty() const { return _dirty; }

private:
  bool _dirty;
};

int main() {
  std::vector<MyObject> objects;

  // 创建一些对象
  for (int i = 0; i < 100000; i++) {
    objects.emplace_back();
  }

  // 修改部分对象
  for (int i = 0; i < 10000; i++) {
    objects[i].setDirty();
  }

  // 释放所有对象
  for (auto& object : objects) {
    if (object.isDirty()) {
      // 重新分配内存
      object = MyObject();
    }
  }

  return 0;
}

In this example, the _dirty flag is used to track each Whether the object has been modified. When the object is released, the isDirty() function checks this flag to determine whether memory needs to be reallocated. By using dirty marking technology, you can greatly reduce the number of objects that need to reallocate memory, thereby improving program performance.

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