Performance quickly drops when using `get_mut` on `Assets<StandardMaterial>`

[hukasu]

Bevy version

cd67bac

[Optional] Relevant system information

2025-05-02T22:45:58.598136Z  INFO bevy_diagnostic::system_information_diagnostics_plugin::internal: SystemInfo { os: "Linux (NixOS 24.11)", kernel: "6.6.85", cpu: "Intel(R) Core(TM) i7-14700KF", core_count: "20", memory: "31.2 GiB" }
2025-05-02T22:45:58.806113Z  INFO bevy_render::renderer: AdapterInfo { name: "NVIDIA GeForce RTX 4060 Ti", vendor: 4318, device: 10243, device_type: DiscreteGpu, driver: "NVIDIA", driver_info: "565.77", backend: Vulkan }

What you did

fn touch_mutably<A: Asset>(mut assets: ResMut<Assets<A>>) {
    for _ in assets.iter_mut() {}
}

What went wrong

Frequency that i can touch_mutably per second decreases rapidly

Investigation

The following issues already report this or something similar

• Memory leak calling get_mut on texture assets resource #2439
• Mesh Over-Allocates memory, causing program to crash #16586
• GPU memory leak when removing then inserting a mesh from Assets #18808
• Animated Materials: Major memory leak #18882

While trying to create a test to see if it is possible to detect these problems programmatically i hit something, the length of MaterialBindGroupBindlessAllocator::slabs and the number of MaterialBindlessSlab::allocated_resource_count quickly grows.

2025-05-02T23:20:00.001547Z  INFO get_mut_leak: Log RenderAppStatistics { render_mesh_asset_count: 20, mesh_allocator_slabs: 3, mesh_allocator_size: 63754272, standard_material_prepared_asset_count: 1002, standard_material_bindless_allocator_slab_count: 1, standard_material_bindless_allocator_slab_capacity: 2048, standard_material_bindless_allocator_total_allocated_resources: 1014 }
2025-05-02T23:20:00.027122Z  INFO get_mut_leak: Log RenderAppStatistics { render_mesh_asset_count: 20, mesh_allocator_slabs: 3, mesh_allocator_size: 63754272, standard_material_prepared_asset_count: 1002, standard_material_bindless_allocator_slab_count: 1, standard_material_bindless_allocator_slab_capacity: 2048, standard_material_bindless_allocator_total_allocated_resources: 2028 }
2025-05-02T23:20:00.060859Z  INFO get_mut_leak: Log RenderAppStatistics { render_mesh_asset_count: 20, mesh_allocator_slabs: 3, mesh_allocator_size: 63754272, standard_material_prepared_asset_count: 1002, standard_material_bindless_allocator_slab_count: 2, standard_material_bindless_allocator_slab_capacity: 2048, standard_material_bindless_allocator_total_allocated_resources: 3042 }
2025-05-02T23:20:00.093389Z  INFO get_mut_leak: Log RenderAppStatistics { render_mesh_asset_count: 20, mesh_allocator_slabs: 3, mesh_allocator_size: 63754272, standard_material_prepared_asset_count: 1002, standard_material_bindless_allocator_slab_count: 2, standard_material_bindless_allocator_slab_capacity: 2048, standard_material_bindless_allocator_total_allocated_resources: 4034 }
2025-05-02T23:20:00.136316Z  INFO get_mut_leak: Log RenderAppStatistics { render_mesh_asset_count: 20, mesh_allocator_slabs: 3, mesh_allocator_size: 63754272, standard_material_prepared_asset_count: 1002, standard_material_bindless_allocator_slab_count: 3, standard_material_bindless_allocator_slab_capacity: 2048, standard_material_bindless_allocator_total_allocated_resources: 5060 }
2025-05-02T23:20:00.164971Z  INFO get_mut_leak: Log RenderAppStatistics { render_mesh_asset_count: 20, mesh_allocator_slabs: 3, mesh_allocator_size: 63754272, standard_material_prepared_asset_count: 1002, standard_material_bindless_allocator_slab_count: 3, standard_material_bindless_allocator_slab_capacity: 2048, standard_material_bindless_allocator_total_allocated_resources: 6038 }
<time skip>
2025-05-02T23:20:14.532212Z  INFO get_mut_leak: Log RenderAppStatistics { render_mesh_asset_count: 20, mesh_allocator_slabs: 3, mesh_allocator_size: 63754272, standard_material_prepared_asset_count: 1002, standard_material_bindless_allocator_slab_count: 83, standard_material_bindless_allocator_slab_capacity: 2048, standard_material_bindless_allocator_total_allocated_resources: 167384 }
2025-05-02T23:20:14.671118Z  INFO get_mut_leak: Log RenderAppStatistics { render_mesh_asset_count: 20, mesh_allocator_slabs: 3, mesh_allocator_size: 63754272, standard_material_prepared_asset_count: 1002, standard_material_bindless_allocator_slab_count: 83, standard_material_bindless_allocator_slab_capacity: 2048, standard_material_bindless_allocator_total_allocated_resources: 168362 }
2025-05-02T23:20:14.803780Z  INFO get_mut_leak: Log RenderAppStatistics { render_mesh_asset_count: 20, mesh_allocator_slabs: 3, mesh_allocator_size: 63754272, standard_material_prepared_asset_count: 1002, standard_material_bindless_allocator_slab_count: 84, standard_material_bindless_allocator_slab_capacity: 2048, standard_material_bindless_allocator_total_allocated_resources: 169388 }
2025-05-02T23:20:14.943487Z  INFO get_mut_leak: Log RenderAppStatistics { render_mesh_asset_count: 20, mesh_allocator_slabs: 3, mesh_allocator_size: 63754272, standard_material_prepared_asset_count: 1002, standard_material_bindless_allocator_slab_count: 84, standard_material_bindless_allocator_slab_capacity: 2048, standard_material_bindless_allocator_total_allocated_resources: 170390 }
2025-05-02T23:20:15.088701Z  INFO get_mut_leak: Log RenderAppStatistics { render_mesh_asset_count: 20, mesh_allocator_slabs: 3, mesh_allocator_size: 63754272, standard_material_prepared_asset_count: 1002, standard_material_bindless_allocator_slab_count: 85, standard_material_bindless_allocator_slab_capacity: 2048, standard_material_bindless_allocator_total_allocated_resources: 171392 }

on this example there are 1001 StandardMaterials, and i touch all of them per update (see method on What you did section), i did not look at the log in its entirety but it looks like the number of slabs increase every 2 updates with this setup