D3D11代码未初始化COM对象存活警告的成因及解决方法

问题场景 #

在64位Windows系统下使用Visual Studio Community 2019编写D3D11 C++代码，调用ReportLiveDeviceObjects后触发多个未显式创建的COM对象存活警告。手动释放ID3D11Device两次后警告消失，但不理解背后原因。

代码示例 #

#define _INCLUDE_LIBS__

#include "stdafx.h"

#define WINDOW_NAME L"main window"
#define WS WS_OVERLAPPEDWINDOW

LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam);

int APIENTRY wWinMain(_In_ HINSTANCE hInstance,
                     _In_opt_ HINSTANCE hPrevInstance,
                     _In_ LPWSTR    lpCmdLine,
                     _In_ int       nCmdShow)
{
    HWND hwnd = NULL; {
        WNDCLASS wc = { 0 };
        wc.cbClsExtra = 0;
        wc.cbWndExtra = 0;
        wc.hbrBackground = CreateSolidBrush(RGB(0, 0, 1));
        wc.hCursor = NULL;
        wc.hIcon = NULL;
        wc.hInstance = hInstance;
        wc.lpfnWndProc = WndProc;
        wc.lpszClassName = L"MainClass";
        wc.lpszMenuName = NULL;
        wc.style = CS_HREDRAW | CS_VREDRAW;

        if (!RegisterClass(&wc)) OutputDebugString(L"ERROR  :   window class registration failed!");
        hwnd = CreateWindow(wc.lpszClassName, WINDOW_NAME, WS, 0, 0, 1000, 600, NULL, NULL, hInstance, NULL);
        if(!hwnd) OutputDebugString(L"ERROR  :   window Creation failed!");
    }

    IDXGIFactory1* factory = nullptr; {
        CreateDXGIFactory1(IID_PPV_ARGS(&factory));
    }

    IDXGIAdapter* adapter = nullptr; {
        factory->EnumAdapters(0, &adapter);
        DXGI_ADAPTER_DESC desc;
        adapter->GetDesc(&desc);

        OutputDebugString(L"\n");
        OutputDebugString(desc.Description);
        OutputDebugString(L"\n\n");
    }

    ID3D11Device* device = nullptr; ID3D11DeviceContext* context = nullptr; {
        D3D_FEATURE_LEVEL lvl[] = { D3D_FEATURE_LEVEL_10_0 };
        UINT flag = D3D11_CREATE_DEVICE_DEBUG;
        D3D11CreateDevice(adapter, D3D_DRIVER_TYPE_UNKNOWN, NULL, flag, lvl, ARRAYSIZE(lvl), D3D11_SDK_VERSION, &device, NULL, &context);
    }

    ID3D11Debug* debug = nullptr; {
        device->QueryInterface(IID_PPV_ARGS(&debug));
    }

    if (context) context->Release();
    if (device) device->Release();
    if (adapter) adapter->Release();
    if (factory) factory->Release();

    debug->ReportLiveDeviceObjects(D3D11_RLDO_DETAIL);

    return 0;
}

LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    switch (message)
    {
    case WM_DESTROY:
        PostQuitMessage(0);
        break;
    default:
        return DefWindowProc(hWnd, message, wParam, lParam);
    }
    return 0;
}

警告输出 #

D3D11 WARNING: Live ID3D11Device at 0x0000020454692FF0, Refcount: 2 [ STATE_CREATION WARNING #441: LIVE_DEVICE]
D3D11 WARNING:  Live ID3D11Context at 0x0000020454695020, Refcount: 0, IntRef: 1 [ STATE_CREATION WARNING #2097226: LIVE_CONTEXT]
D3D11 WARNING:  Live ID3DDeviceContextState at 0x000002045626F000, Refcount: 0, IntRef: 1 [ STATE_CREATION WARNING #3145742: LIVE_DEVICECONTEXTSTATE]
D3D11 WARNING:  Live ID3D11BlendState at 0x0000020456266170, Refcount: 0, IntRef: 1 [ STATE_CREATION WARNING #435: LIVE_BLENDSTATE]
D3D11 WARNING:  Live ID3D11DepthStencilState at 0x0000020456266370, Refcount: 0, IntRef: 1 [ STATE_CREATION WARNING #436: LIVE_DEPTHSTENCILSTATE]
D3D11 WARNING:  Live ID3D11RasterizerState at 0x0000020456266570, Refcount: 0, IntRef: 1 [ STATE_CREATION WARNING #437: LIVE_RASTERIZERSTATE]
D3D11 WARNING:  Live ID3D11Sampler at 0x0000020456266780, Refcount: 0, IntRef: 1 [ STATE_CREATION WARNING #434: LIVE_SAMPLER]
D3D11 WARNING:  Live ID3D11Query at 0x0000020456266E60, Refcount: 0, IntRef: 1 [ STATE_CREATION WARNING #438: LIVE_QUERY]

原因解析 #

1. COM引用计数规则：调用QueryInterface获取COM接口时，会同时增加目标对象的引用计数。这里通过device->QueryInterface获取ID3D11Debug接口，导致ID3D11Device的引用计数从1（创建时）增加到2。你只调用了一次device->Release()，计数降到1，设备并未销毁。
2. 默认状态对象：警告中的BlendState、DepthStencilState等是D3D11设备初始化时自动创建的默认状态对象，它们被设备上下文内部持有（IntRef:1代表内部引用）。只要设备存活，这些内部对象就不会被释放。
3. 释放顺序问题：你在调用ReportLiveDeviceObjects前释放了设备，但此时设备因引用计数未归0仍存活，连带内部默认对象也处于存活状态，触发警告。手动调用两次Release()把计数降到0，设备销毁后内部对象才被释放，警告消失。

修复方案 #

方案1：正确管理ID3D11Debug的引用 #

QueryInterface创建的ID3D11Debug接口本身需要调用Release()，这会自动减少ID3D11Device的引用计数，让一次device->Release()就能完成销毁：

// ... 原有代码 ...

ID3D11Debug* debug = nullptr; {
    device->QueryInterface(IID_PPV_ARGS(&debug));
}

// 先释放除debug、device外的其他对象
if (context) context->Release();
if (adapter) adapter->Release();
if (factory) factory->Release();

// 调用设备对象报告
debug->ReportLiveDeviceObjects(D3D11_RLDO_DETAIL);

// 释放debug接口，自动减少device的引用计数
debug->Release();
// 释放device，此时计数归0，设备销毁
if (device) device->Release();

return 0;

方案2：使用COM智能指针（推荐） #

使用Microsoft::WRL::ComPtr（Windows Runtime Library）管理COM对象，它会自动处理引用计数，避免手动Release的错误：

// 包含头文件
#include <wrl/client.h>
using namespace Microsoft::WRL;

// 替换裸指针为ComPtr
ComPtr<IDXGIFactory1> factory;
ComPtr<IDXGIAdapter> adapter;
ComPtr<ID3D11Device> device;
ComPtr<ID3D11DeviceContext> context;
ComPtr<ID3D11Debug> debug;

// 创建对象时无需手动管理引用
CreateDXGIFactory1(IID_PPV_ARGS(&factory));
factory->EnumAdapters(0, &adapter);
// ... 其他创建逻辑 ...
device->QueryInterface(IID_PPV_ARGS(&debug));

// 调用报告
debug->ReportLiveDeviceObjects(D3D11_RLDO_DETAIL);

// 无需手动调用Release，ComPtr超出作用域时自动释放

内容的提问来源于stack exchange，提问作者unicus