c++ - CRT & new - 92 字节的 30 次调用给出 "bad_alloc nomem"

Question

我正在为 C++ CRT DirectX 应用程序中 2000 多个对象的最近邻居编写一个动态八叉树。在调用新运算符 30 次后，程序会抛出“bad_alloc nomem”。我没有在其他任何地方使用 new。

我现在不知所措，以下是程序大纲以及我迄今为止为消除此错误所做的最大努力。即使在大量剪切之后仍然有很多 - 但请不要让它让您失望!

这是类结构:

template <typename T, int MaxObjPerNode>
class Octree
{...

public:
    struct Node
    {
        int objcnt; // 0 == Node 4bytes
        Node* parent; // 0 == Base 4bytes
        D3DXVECTOR3 centre; //12bytes
        Node* children[8]; //32bytes
        Cube bounderies; //24bytes (Struct of 6 floats)
        T* obj[MaxObjPerNode]; //4bytes *4

        Node()
        {
            objcnt=0;
            parent = 0;
            centre = D3DXVECTOR3(0,0,0);
            for (int t=0; t<8; t++)
                children[t] = 0;
            for (int t=0; t<MaxObjPerNode; t++)
                obj[t] = 0;
        }

        Node* GiveBirth(int const Oct)
        {
            //...Sanity checks & intalisation
            Node* NewNode = 0;
//_CrtMemState myBug;
            NewNode = new Node(); // Nasty man sits here
//_CrtMemCheckpoint(&myBug);                                
            NewNode->parent = this;
            NewNode->centre = NewCentre;
            //... rest of NewNode init.         
        }
        //... Other functions sniped 
    }
private:
    Node* base;
    int StrtVecOff;
public:
    Octree(float InitalCubeSize, T* FirstObj, long VectorOffset)
    {
        //D3DXVECTOR3* pTemp;
        base = new Node();
        StrtVecOff = VectorOffset; //Used to find Current Position in class T
        base->objcnt = 1;
        base->parent = 0;
        base->obj[0] = FirstObj;
        //... rest of base init.
    }

    Node* Add(T* Obj)
    {
        D3DXVECTOR3* Point = (D3DXVECTOR3*)(((long)(Obj))+StrtVecOff);

        Node* InNode;
        InNode = FindPlaceInTree(Point);
        // FindPlaceInTree returns as Parent if Leaf has not been created from Node - So create leaf child
        if (InNode->objcnt == 0)
        {
            int Oct = InNode->FindOctet(Point);
            Node* ChildNode = InNode->GiveBirth(Oct);
            ChildNode->obj[ChildNode->objcnt] = Obj;
            ChildNode->objcnt +=1;
            return ChildNode;
        }
        //...Other situations snipped
    }
};

这是调用代码，

Octree<Mob,4> MyTree((float)(1<<13), &Bird[0],((long)&Bird[0].Pos - (long)&Bird[0]) );

for (int t=0;t<BirdsCount;t++)
    MyTree.Add(&Bird[t]);

八叉树完美初始化，base* 正确指向有效数据。在 BANG 之前，对 new 的所有其他调用(30 * 92 字节)都没有问题。所以我进行了堆检查(在上面 GiveBirth 的注释代码处)；通过 1:

-       myBug   {pBlockHeader=0x003d3208 lCounts=0x0012f938 lSizes=0x0012f94c ...}  _CrtMemState
+       pBlockHeader    0x003d3208 
_CrtMemBlockHeader * //..snip - correct
-       lCounts 0x0012f938  unsigned int [5]
        [0] 0   unsigned int
        [1] 2   unsigned int //First time past + base
        [2] 45  unsigned int
        [3] 0   unsigned int
        [4] 0   unsigned int
-       lSizes  0x0012f94c  unsigned int [5]
        [0] 0   unsigned int
        [1] 184 unsigned int //Correct 2*92
        [2] 8409    unsigned int
        [3] 0   unsigned int
        [4] 0   unsigned int
        lHighWaterCount 12505   unsigned int
        lTotalCount 18238   unsigned int

第 2-28 遍:实际上都是相同的

第 29 次:

-       myBug   {pBlockHeader=0x003d5c50 lCounts=0x0012f938 lSizes=0x0012f94c ...}  _CrtMemState
+       pBlockHeader    0x003d5c50 {pBlockHeaderNext=0x003d5bb8 pBlockHeaderPrev=0x00000000 szFileName=0x00000000 <Bad Ptr> ...}    _CrtMemBlockHeader *
-       lCounts 0x0012f938  unsigned int [5]
        [0] 0   unsigned int
        [1] 30  unsigned int
        [2] 45  unsigned int
        [3] 0   unsigned int
        [4] 0   unsigned int
-       lSizes  0x0012f94c  unsigned int [5]
        [0] 0   unsigned int
        [1] 2760    unsigned int
        [2] 8409    unsigned int
        [3] 0   unsigned int
        [4] 0   unsigned int
        lHighWaterCount 12505   unsigned int
        lTotalCount 20814   unsigned int

没有通过 30 :(我知道我有超过 2760 字节的空闲空间(我不再使用 vic 20!)。

我看了很多“相关问题”，仍然没有喜悦。欢迎任何建议

Answer 1

当 new 因任何原因失败时会抛出内存异常。它不一定是内存不足的情况。不要被愚弄了。某些东西在构造函数中抛出异常。