Description
Version/Branch of Dear ImGui:
Version 1.90.4, Branch: docking
Back-ends:
imgui_impl_wgpu.cpp + imgui_impl_glfw.cpp
Compiler, OS:
Windows 10 + clang-cl 18.1.8
Full config/build information:
Dear ImGui 1.90.4 (19040)
--------------------------------
sizeof(size_t): 8, sizeof(ImDrawIdx): 2, sizeof(ImDrawVert): 20
define: __cplusplus=202400
define: _WIN32
define: _WIN64
define: _MSC_VER=1939
define: _MSVC_LANG=202004
define: __clang_version__=17.0.6
define: IMGUI_HAS_VIEWPORT
define: IMGUI_HAS_DOCK
--------------------------------
io.BackendPlatformName: imgui_impl_glfw
io.BackendRendererName: imgui_impl_webgpu
io.ConfigFlags: 0x00000000
io.ConfigViewportsNoDecoration
io.ConfigInputTextCursorBlink
io.ConfigWindowsResizeFromEdges
io.ConfigMemoryCompactTimer = 60.0
io.BackendFlags: 0x00000C0E
HasMouseCursors
HasSetMousePos
PlatformHasViewports
HasMouseHoveredViewport
RendererHasVtxOffset
--------------------------------
io.Fonts: 1 fonts, Flags: 0x00000000, TexSize: 512,64
io.DisplaySize: 640.00,480.00
io.DisplayFramebufferScale: 1.00,1.00
--------------------------------
style.WindowPadding: 8.00,8.00
style.WindowBorderSize: 1.00
style.FramePadding: 4.00,3.00
style.FrameRounding: 0.00
style.FrameBorderSize: 0.00
style.ItemSpacing: 8.00,4.00
style.ItemInnerSpacing: 4.00,4.00
Details:
Whenever an ImGui::Image is used with WebGPU backend, memory leaks are reported
Here is the output I get when running the minimal code sample and closing the window:
D3D12 WARNING: Process is terminating. Using simple reporting. Please call ReportLiveObjects() at runtime for standard reporting. [ STATE_CREATION WARNING #0: UNKNOWN]
D3D12 WARNING: Live Producer at 0x0000027177755518, Refcount: 6. [ STATE_CREATION WARNING #0: UNKNOWN]
D3D12 WARNING: Live Object at 0x0000027177896250, Refcount: 0. [ STATE_CREATION WARNING #0: UNKNOWN]
D3D12 WARNING: Live Object at 0x00000271777E6870, Refcount: 0. [ STATE_CREATION WARNING #0: UNKNOWN]
D3D12 WARNING: Live Object at 0x000002717781AF00, Refcount: 0. [ STATE_CREATION WARNING #0: UNKNOWN]
D3D12 WARNING: Live Object at 0x0000027174F25F30, Refcount: 0. [ STATE_CREATION WARNING #0: UNKNOWN]
D3D12 WARNING: Live Object at 0x000002717774BBA0, Refcount: 0. [ STATE_CREATION WARNING #0: UNKNOWN]
D3D12 WARNING: Live Object at 0x00000271777E88B0, Refcount: 0. [ STATE_CREATION WARNING #0: UNKNOWN]
D3D12 WARNING: Live Object at 0x000002717774C320, Refcount: 0. [ STATE_CREATION WARNING #0: UNKNOWN]
D3D12 WARNING: Live Object at 0x0000027174C7C700, Refcount: 0. [ STATE_CREATION WARNING #0: UNKNOWN]
D3D12 WARNING: Live Object at 0x000002717774DD50, Refcount: 1. [ STATE_CREATION WARNING #0: UNKNOWN]
D3D12 WARNING: Live Object at 0x0000027174F25310, Refcount: 1. [ STATE_CREATION WARNING #0: UNKNOWN]
D3D12 WARNING: Live Object at 0x0000027177953050, Refcount: 0. [ STATE_CREATION WARNING #0: UNKNOWN]
D3D12 WARNING: Live Object at 0x00000271779537D0, Refcount: 1. [ STATE_CREATION WARNING #0: UNKNOWN]
As soon as I comment the ImGui::Image line, this log disappears.
Investigation
I investigated the imgui_impl_wgpu.cpp file and it appears that the WGPUBindGroups contained in ImageBindGroups (of the RenderResources structure) are not released in static void SafeRelease(RenderResources& res), that is called by ImGui_ImplWGPU_Shutdown().
Initially, I stumbled upon this while having the issue mentioned reported in #7765. It appears that clearing the WGPUBindGroups each frame could also solve the issue, if it is done at the end of the call to ImGui_ImplWGPU_RenderDrawData, but I think the groups need to survive longer than this. Anyway, the SafeRelease functions still do not do their job properly.
That's why I chose to open a distinct issue.
Local hack to fix the issue
Locally, I hacked my way through the issue but in a very ugly way. I expose the code here in order to show my way of thinking about this issue:
// imgui_mock is a namespace where I copy-pasted structs that are only defined in imgui_impl_wgpu.cpp
static auto clear_image_bind_groups() -> void {
imgui_mock::ImGui_ImplWGPU_Data & bd =
*reinterpret_cast<imgui_mock::ImGui_ImplWGPU_Data *>(ImGui::GetIO().BackendRendererUserData);
auto & storage = bd.renderResources.ImageBindGroups;
// This group is already released but stored in the same place
auto const font_bind_group = bd.renderResources.ImageBindGroup;
for (auto const & pair : storage.Data) {
if (pair.val_p != nullptr && pair.val_p != font_bind_group)
wgpuBindGroupRelease(reinterpret_cast<WGPUBindGroup>(pair.val_p));
}
storage.Clear();
}
void render_frame()
{
// Configure everything
WGPURenderPassEncoder render_pass = /* ... */;
// Draw ImGui data
ImGui::Render();
ImGui_ImplWGPU_RenderDrawData(ImGui::GetDrawData(), render_pass);
// Other rendering stuff
wgpuQueueSubmit(/* ... */);
wgpuSurfacePresent(/* ... */);
// When everything is done, clean bind groups
clear_image_bind_groups();
}Fix proposal
I do believe that adding some cleaning code in SafeRelease would fix the issue in a clean way, something that would look like that:
static void SafeRelease(RenderResources& res)
{
SafeRelease(res.FontTexture);
SafeRelease(res.FontTextureView);
SafeRelease(res.Sampler);
SafeRelease(res.Uniforms);
SafeRelease(res.CommonBindGroup);
// Add this loop
for (int i = 0; i < res.ImageBindGroups.Data.Size; i++)
{
if (res.ImageBindGroups.Data[i].val_p != res.ImageBindGroup)
SafeRelease((WGPUBindGroup)res.ImageBindGroups.Data[i].val_p);
}
SafeRelease(res.ImageBindGroup);
SafeRelease(res.ImageBindGroupLayout);
};Note that we avoid releasing twice the WGPUBindGroup that is both stored in ImageBindGroup and ImageBindGroups. This bind group is used for the default font atlas and is correctly released. When calling ImGui::ShowDemoWindow(), there is no leak because the only call to ImGui::Image is to display the default font atlas.
Screenshots/Video:
No response
Minimal, Complete and Verifiable Example code:
// At init time, create or load a texture:
WGPUTextureView my_texture_view = /* ... */;
// In main loop, call ImGui::Image
ImGui::Begin("Example Bug");
ImGui::Image((void *)my_texture_view, ImVec2(my_image_width, my_image_height));
ImGui::End();