High RAM usage while resizing with DX11

[pierrbt]

When resizing the window, the render stops, which is surely normal but when looking in VS to the process memory, after about 10seconds of resizing, it uses up to 20GB of RAM ! I'm using win32 with DX11, the default file.

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Dear ImGui 1.89.6 WIP

Version/Branch of Dear ImGui:

Version: 1.19.6
Branch: master

Back-end/Renderer/Compiler/OS

Back-ends: imgui_impl_win32.cpp + imgui_impl_dx11.cpp
Compiler: MSVC
Operating System: Windows 11

My Issue/Question:

Is this normal ?

Screenshots/Video

Standalone, minimal, complete and verifiable example: (see #2261)

#include "imgui.h"
#include "imgui_impl_win32.h"
#include "imgui_impl_dx11.h"
#include <d3d11.h>
#include <tchar.h>

// Data
static ID3D11Device*            g_pd3dDevice = nullptr;
static ID3D11DeviceContext*     g_pd3dDeviceContext = nullptr;
static IDXGISwapChain*          g_pSwapChain = nullptr;
static ID3D11RenderTargetView*  g_mainRenderTargetView = nullptr;

// Forward declarations of helper functions
bool CreateDeviceD3D(HWND hWnd);
void CleanupDeviceD3D();
void CreateRenderTarget();
void CleanupRenderTarget();
LRESULT WINAPI WndProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam);

// Main code
int main(int, char**)
{
    // Create application window
    //ImGui_ImplWin32_EnableDpiAwareness();
    WNDCLASSEXW wc = { sizeof(wc), CS_CLASSDC, WndProc, 0L, 0L, GetModuleHandle(nullptr), nullptr, nullptr, nullptr, nullptr, L"WeathGet", nullptr };
    ::RegisterClassExW(&wc);
    HWND hwnd = ::CreateWindowW(wc.lpszClassName, L"WeathGet", WS_OVERLAPPEDWINDOW, 100, 100, 1280, 800, nullptr, nullptr, wc.hInstance, nullptr);

    // Initialize Direct3D
    if (!CreateDeviceD3D(hwnd))
    {
        CleanupDeviceD3D();
        ::UnregisterClassW(wc.lpszClassName, wc.hInstance);
        return 1;
    }

    // Show the window
    ::ShowWindow(hwnd, SW_SHOWDEFAULT);
    ::UpdateWindow(hwnd);

    // Setup Dear ImGui context
    IMGUI_CHECKVERSION();
    ImGui::CreateContext();
    ImGuiIO& io = ImGui::GetIO(); (void)io;
    io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;     // Enable Keyboard Controls
    io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;      // Enable Gamepad Controls

    /*ImGuiStyle& style = ImGui::GetStyle();
    style.WindowBorderSize = 0.0f;
    style.FramePadding = ImVec2(.0f, .0f);*/

    // Setup Dear ImGui style
    ImGui::StyleColorsDark();
    //ImGui::StyleColorsLight();

    // Setup Platform/Renderer backends
    ImGui_ImplWin32_Init(hwnd);
    ImGui_ImplDX11_Init(g_pd3dDevice, g_pd3dDeviceContext);

    // Our state
    bool show_demo_window = true;
    bool show_another_window = false;
    ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);

    // Main loop
    bool done = false;
    while (!done)
    {
        // Poll and handle messages (inputs, window resize, etc.)
        // See the WndProc() function below for our to dispatch events to the Win32 backend.
        MSG msg;
        while (::PeekMessage(&msg, nullptr, 0U, 0U, PM_REMOVE))
        {
            ::TranslateMessage(&msg);
            ::DispatchMessage(&msg);
            if (msg.message == WM_QUIT)
                done = true;
        }
        if (done)
            break;

        // Start the Dear ImGui frame
        ImGui_ImplDX11_NewFrame();
        ImGui_ImplWin32_NewFrame();
        ImGui::NewFrame();

#ifdef IMGUI_HAS_VIEWPORT
        ImGuiViewport* viewport = ImGui::GetMainViewport();
        ImGui::SetNextWindowPos(viewport->GetWorkPos());
        ImGui::SetNextWindowSize(viewport->GetWorkSize());
        ImGui::SetNextWindowViewport(viewport->ID);
#else 
       // ImGui::SetNextWindowPos(ImVec2(0.0f, 0.0f));
       // ImGui::SetNextWindowSize(ImGui::GetIO().DisplaySize);
#endif


        
        // 1. Show the big demo window (Most of the sample code is in ImGui::ShowDemoWindow()! You can browse its code to learn more about Dear ImGui!).
        if (show_demo_window)
            ImGui::ShowDemoWindow(&show_demo_window);

        // 2. Show a simple window that we create ourselves. We use a Begin/End pair to create a named window.
        {
            static float f = 0.0f;
            static int counter = 0;

            ImGui::Begin("Hello, world!", nullptr/*,
                ImGuiWindowFlags_NoTitleBar |
                ImGuiWindowFlags_NoCollapse |
                ImGuiWindowFlags_AlwaysAutoResize |
                ImGuiWindowFlags_NoMove |
                ImGuiWindowFlags_NoResize*/);                          // Create a window called "Hello, world!" and append into it.

            ImGui::Text("This is some useful text.");               // Display some text (you can use a format strings too)
            ImGui::Checkbox("Demo Window", &show_demo_window);      // Edit bools storing our window open/close state
            ImGui::Checkbox("Another Window", &show_another_window);

            ImGui::SliderFloat("float", &f, 0.0f, 1.0f);            // Edit 1 float using a slider from 0.0f to 1.0f
            ImGui::ColorEdit3("clear color", (float*)&clear_color); // Edit 3 floats representing a color

            if (ImGui::Button("Button"))                            // Buttons return true when clicked (most widgets return true when edited/activated)
                counter++;
            ImGui::SameLine();
            ImGui::Text("counter = %d", counter);

            ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / io.Framerate, io.Framerate);
            ImGui::End();
        }

        // 3. Show another simple window.
        if (show_another_window)
        {
            ImGui::Begin("Another Window", &show_another_window);   // Pass a pointer to our bool variable (the window will have a closing button that will clear the bool when clicked)
            ImGui::Text("Hello from another window!");
            if (ImGui::Button("Close Me"))
                show_another_window = false;
            ImGui::End();
        }

        // Rendering
        ImGui::Render();
        const float clear_color_with_alpha[4] = { clear_color.x * clear_color.w, clear_color.y * clear_color.w, clear_color.z * clear_color.w, clear_color.w };
        g_pd3dDeviceContext->OMSetRenderTargets(1, &g_mainRenderTargetView, nullptr);
        g_pd3dDeviceContext->ClearRenderTargetView(g_mainRenderTargetView, clear_color_with_alpha);
        ImGui_ImplDX11_RenderDrawData(ImGui::GetDrawData());

        g_pSwapChain->Present(1, 0); // Present with vsync
        //g_pSwapChain->Present(0, 0); // Present without vsync
    }

    // Cleanup
    ImGui_ImplDX11_Shutdown();
    ImGui_ImplWin32_Shutdown();
    ImGui::DestroyContext();

    CleanupDeviceD3D();
    ::DestroyWindow(hwnd);
    ::UnregisterClassW(wc.lpszClassName, wc.hInstance);

    return 0;
}

[pierrbt]

I saw that the memory was used only when we were changing the size, when we hold the mouse button but don't move, it stays at the point it was before, only when we are currently resizing the window, it goes up very fast. Is there a Vec2 buffer with all the old positions of the window until the button is released ?

[pierrbt]

This only bugs using DX11; I just tried with DX12 and it does not consume more memory.

[ocornut]

I have pushed a workaround for this in 031e152
Thanks for reporting!

[pierrbt]

Well done, it was a bit annoying that it was using that much ram...