ComponentsManager

The ComponentsManager is a model registry and management system for Modular Diffusers. It adds and tracks models, stores useful metadata (model size, device placement, adapters), prevents duplicate model instances, and supports offloading.

This guide will show you how to use ComponentsManager to manage components and device memory.

Add a component

The ComponentsManager should be created alongside a ModularPipeline in either from_pretrained() or init_pipeline().

from diffusers import ModularPipeline, ComponentsManager

comp = ComponentsManager()
pipe = ModularPipeline.from_pretrained("YiYiXu/modular-demo-auto", components_manager=comp, collection="test1")

Components are only loaded and registered when using load_components() or load_default_components(). The example below uses load_default_components() to create a second pipeline that reuses all the components from the first one, and assigns it to a different collection

pipe.load_default_components()
pipe2 = ModularPipeline.from_pretrained("YiYiXu/modular-demo-auto", components_manager=comp, collection="test2")

Use the null_component_names property to identify any components that need to be loaded, retrieve them with get_components_by_names(), and then call update_components() to add the missing components.

pipe2.null_component_names 
['text_encoder', 'text_encoder_2', 'tokenizer', 'tokenizer_2', 'image_encoder', 'unet', 'vae', 'scheduler', 'controlnet']

comp_dict = comp.get_components_by_names(names=pipe2.null_component_names)
pipe2.update_components(**comp_dict)

To add individual components, use the add() method. This registers a component with a unique id.

from diffusers import AutoModel

text_encoder = AutoModel.from_pretrained("stabilityai/stable-diffusion-xl-base-1.0", subfolder="text_encoder")
component_id = comp.add("text_encoder", text_encoder)
comp

Use remove() to remove a component using their id.

comp.remove("text_encoder_139917733042864")

Retrieve a component

The ComponentsManager provides several methods to retrieve registered components.

get_one

The get_one() method returns a single component and supports pattern matching for the name parameter. If multiple components match, get_one() returns an error.

get_one() also filters components by the collection argument or load_id argument.

comp.get_one(name="unet", collection="sdxl")

get_components_by_names

The get_components_by_names() method accepts a list of names and returns a dictionary mapping names to components. This is especially useful with ModularPipeline since they provide lists of required component names and the returned dictionary can be passed directly to update_components().

component_dict = comp.get_components_by_names(names=["text_encoder", "unet", "vae"])
{"text_encoder": component1, "unet": component2, "vae": component3}

Duplicate detection

It is recommended to load model components with ComponentSpec to assign components with a unique id that encodes their loading parameters. This allows ComponentsManager to automatically detect and prevent duplicate model instances even when different objects represent the same underlying checkpoint.

from diffusers import ComponentSpec, ComponentsManager
from transformers import CLIPTextModel

comp = ComponentsManager()

# Create ComponentSpec for the first text encoder
spec = ComponentSpec(name="text_encoder", repo="stabilityai/stable-diffusion-xl-base-1.0", subfolder="text_encoder", type_hint=AutoModel)
# Create ComponentSpec for a duplicate text encoder (it is same checkpoint, from the same repo/subfolder)
spec_duplicated = ComponentSpec(name="text_encoder_duplicated", repo="stabilityai/stable-diffusion-xl-base-1.0", subfolder="text_encoder", type_hint=CLIPTextModel)

# Load and add both components - the manager will detect they're the same model
comp.add("text_encoder", spec.load())
comp.add("text_encoder_duplicated", spec_duplicated.load())

This returns a warning with instructions for removing the duplicate.

ComponentsManager: adding component 'text_encoder_duplicated_139917580682672', but it has duplicate load_id 'stabilityai/stable-diffusion-xl-base-1.0|text_encoder|null|null' with existing components: text_encoder_139918506246832. To remove a duplicate, call `components_manager.remove('<component_id>')`.
'text_encoder_duplicated_139917580682672'

You could also add a component without using ComponentSpec and duplicate detection still works in most cases even if you’re adding the same component under a different name.

However, ComponentManager can’t detect duplicates when you load the same component into different objects. In this case, you should load a model with ComponentSpec.

text_encoder_2 = AutoModel.from_pretrained("stabilityai/stable-diffusion-xl-base-1.0", subfolder="text_encoder")
comp.add("text_encoder", text_encoder_2)
'text_encoder_139917732983664'

Collections

Collections are labels assigned to components for better organization and management. Add a component to a collection with the collection argument in add().

Only one component per name is allowed in each collection. Adding a second component with the same name automatically removes the first component.

from diffusers import ComponentSpec, ComponentsManager

comp = ComponentsManager()
# Create ComponentSpec for the first UNet
spec = ComponentSpec(name="unet", repo="stabilityai/stable-diffusion-xl-base-1.0", subfolder="unet", type_hint=AutoModel)
# Create ComponentSpec for a different UNet
spec2 = ComponentSpec(name="unet", repo="RunDiffusion/Juggernaut-XL-v9", subfolder="unet", type_hint=AutoModel, variant="fp16")

# Add both UNets to the same collection - the second one will replace the first
comp.add("unet", spec.load(), collection="sdxl")
comp.add("unet", spec2.load(), collection="sdxl")

This makes it convenient to work with node-based systems because you can:

• Mark all models as loaded from one node with the collection label.
• Automatically replace models when new checkpoints are loaded under the same name.
• Batch delete all models in a collection when a node is removed.

Offloading

The enable_auto_cpu_offload() method is a global offloading strategy that works across all models regardless of which pipeline is using them. Once enabled, you don’t need to worry about device placement if you add or remove components.

comp.enable_auto_cpu_offload(device="cuda")

All models begin on the CPU and ComponentsManager moves them to the appropriate device right before they’re needed, and moves other models back to the CPU when GPU memory is low.

You can set your own rules for which models to offload first.