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---
title: Dynamic Tab Loading Examples
emoji: 🏢
colorFrom: blue
colorTo: indigo
sdk: gradio
sdk_version: 5.34.2
app_file: app.py
pinned: true
license: apache-2.0
short_description: Exploring different loading methods for a HF Space
---
# Dynamic Space Loading
---
## 1. **Sending Data To/From IFrames**
### **A. Standard Web (HTML/JS) Context**
- **IFrames are sandboxed:** By default, an iframe is isolated from the parent page for security reasons.
- **postMessage API:**
- The standard way to communicate between a parent page and an iframe (and vice versa) is using the [window.postMessage](https://developer.mozilla.org/en-US/docs/Web/API/Window/postMessage) API.
- This requires both the parent and the iframe to have JavaScript code that listens for and sends messages.
- Example:
- Parent: `iframeEl.contentWindow.postMessage({data: "hello"}, "https://iframe-domain.com")`
- IFrame: `window.parent.postMessage({data: "hi back"}, "https://parent-domain.com")`
- **Limitations in Gradio:**
- Gradio does not expose a built-in way to inject custom JS for postMessage into the iframe or parent.
- If you control both the parent and the iframe (i.e., both are your own apps), you could add custom JS to both and use postMessage.
- If the iframe is a third-party app (like a Hugging Face Space you don’t control), you cannot inject JS into it, so you cannot send/receive data programmatically.
### **B. Gradio Context**
- **No built-in Gradio API for iframe communication.**
- **You can use gr.HTML to inject a script into the parent,** but you cannot inject into the iframe if you don’t control its code.
---
## 2. **Sending Data Between Tabs in Gradio**
- **Tabs in Gradio are just layout elements:** All components in all tabs exist in the same Python process and can share state.
- **You can use gr.State or any shared variable:**
- For example, you can have a gr.State object that is updated in one tab and read in another.
- You can also use hidden components or callbacks to pass data between tabs.
---
## 3. **Summary Table**
| Method | Parent ↔ IFrame | Tab ↔ Tab (Gradio) |
|-----------------------|:--------------:|:------------------:|
| postMessage (JS) | Yes (if you control both) | N/A |
| gr.State | No | Yes |
| Hidden Components | No | Yes |
| gradio API | No | Yes |
---
## 4. **Practical Recommendations**
- **For arbitrary Hugging Face Spaces in iframes:**
- You cannot send/receive data programmatically unless the Space itself is designed to listen for postMessage.
- **For your own Spaces:**
- You can add JS to both parent and iframe to use postMessage.
- **For Gradio tabs:**
- Use gr.State or shared components for seamless data transfer.
---
This is a very insightful and advanced question! Here’s a breakdown of what’s possible, what’s not, and what’s practical with Gradio, Hugging Face Spaces, and Python environments:
---
## 2. **GPU Spaces (transformers/diffusers) Loading/Unloading**
### **A. In a Single Python Process (One Space, One App)**
- **You can load multiple models/pipelines in one Gradio app.**
- You can have a dropdown or tabs to select which model/task/pipeline to use.
- You can load/unload models on demand (though loading large models is slow).
- You can keep all models in memory (if you have enough GPU RAM), or load/unload as needed.
- **You cannot have truly separate environments** (e.g., different Python dependencies, CUDA versions, or isolated memory) in a single Space.
- All code runs in the same Python process/environment.
- All models share the same GPU/CPU memory pool.
#### **Example:**
```python
from transformers import pipeline
import gradio as gr
# Preload or lazy-load multiple pipelines
pipe1 = pipeline("text-generation", model="gpt2")
pipe2 = pipeline("image-classification", model="google/vit-base-patch16-224")
def run_model(input, model_choice):
if model_choice == "Text Generation":
return pipe1(input)
elif model_choice == "Image Classification":
return pipe2(input)
# ... more models
gr.Interface(
fn=run_model,
inputs=[gr.Textbox(), gr.Dropdown(["Text Generation", "Image Classification"])],
outputs="auto"
).launch()
```
- You can use tabs or dropdowns to switch between models/tasks.
---
### **B. Multiple Gradio Apps in One Space**
- You can define multiple Gradio interfaces in one script and show/hide them with tabs or dropdowns.
- **But:** They still share the same Python process and memory.
---
### **C. True Isolation (Multiple Environments)**
- **Not possible in a single Hugging Face Space.**
- You cannot have multiple Python environments, different dependency sets, or isolated GPU memory pools in one Space.
- Each Space is a single container/process.
---
### **D. What About Docker or Subprocesses?**
- Hugging Face Spaces (hosted) do not support running multiple containers or true subprocess isolation with different environments.
- On your own infrastructure, you could use Docker or subprocesses, but this is not supported on Spaces.
---
## 3. **Best Practices for Multi-Model/Multi-Task Apps**
- **Lazy-load models:** Only load a model when its tab is selected, and unload it when switching (if memory is a concern).
- **Use a single environment:** Install all dependencies needed for all models in your `requirements.txt`.
- **Warn users about memory:** If users switch between large models, GPU memory may fill up and require manual cleanup (e.g., `torch.cuda.empty_cache()`).
---
## 4. **Summary Table**
| Approach | Isolation | Multiple Models | Multiple Envs | GPU Sharing | Supported on Spaces |
|----------------------------------|:---------:|:--------------:|:-------------:|:-----------:|:------------------:|
| Single Gradio app, many models | No | Yes | No | Yes | Yes |
| Multiple Gradio apps in one file | No | Yes | No | Yes | Yes |
| Multiple Spaces (one per app) | Yes | Yes | Yes | Isolated | Yes |
| Docker/subprocess isolation | Yes | Yes | Yes | Isolated | No (on Spaces) |
---
## 4. **What’s Practical?**
- **For most use cases:**
- Use a single app with tabs/dropdowns to select the model/task.
- Lazy-load and unload models as needed to manage memory.
- **For true isolation:**
- Use multiple Spaces (one per app/model) or host your own infrastructure with Docker.
---
## 5. **Properly Unloading Models, Weights, and Freeing Memory in PyTorch/Diffusers**
When working with large models (especially on GPU), it's important to:
- **Delete references to the model and pipeline**
- **Call `gc.collect()`** to trigger Python's garbage collector
- **Call `torch.cuda.empty_cache()`** (if using CUDA) to free GPU memory
### **Best Practice Pattern**
Here’s a robust pattern for loading and unloading models in a multi-model Gradio app:
```python
import torch
import gc
from diffusers import DiffusionPipeline
model_cache = {}
def load_diffusion_model(model_id, dtype=torch.float32, device="cpu"):
pipe = DiffusionPipeline.from_pretrained(model_id, torch_dtype=dtype)
pipe = pipe.to(device)
pipe.enable_attention_slicing()
return pipe
def unload_model(model_key):
# Remove from cache
if model_key in model_cache:
del model_cache[model_key]
# Run Python garbage collection
gc.collect()
# Free GPU memory if using CUDA
if torch.cuda.is_available():
torch.cuda.empty_cache()
```
### **How to Use in a Gradio Tab**
```python
import gradio as gr
model_id = "LPX55/FLUX.1-merged_lightning_v2"
model_key = "flux"
device = "cpu" # or "cuda" if available and desired
def do_load():
if model_key not in model_cache:
model_cache[model_key] = load_diffusion_model(model_id, torch.float32, device)
return "Model loaded!"
def do_unload():
unload_model(model_key)
return "Model unloaded!"
def run_inference(prompt, width, height, steps):
if model_key not in model_cache:
return None, "Model not loaded!"
pipe = model_cache[model_key]
image = pipe(
prompt=prompt,
width=width,
height=height,
num_inference_steps=steps,
).images[0]
return image, "Success!"
with gr.Blocks() as demo:
status = gr.Markdown("Model not loaded.")
load_btn = gr.Button("Load Model")
unload_btn = gr.Button("Unload Model")
prompt = gr.Textbox(label="Prompt", value="A cat holding a sign that says hello world")
width = gr.Slider(256, 1536, value=768, step=64, label="Width")
height = gr.Slider(256, 1536, value=1152, step=64, label="Height")
steps = gr.Slider(1, 50, value=8, step=1, label="Inference Steps")
run_btn = gr.Button("Generate Image")
output_img = gr.Image(label="Output Image")
output_msg = gr.Textbox(label="Status", interactive=False)
load_btn.click(do_load, None, status)
unload_btn.click(do_unload, None, status)
run_btn.click(run_inference, [prompt, width, height, steps], [output_img, output_msg])
demo.launch()
```
---
### **Key Points**
- **Always delete the model from your cache/dictionary.**
- **Call `gc.collect()` after deleting the model.**
- **Call `torch.cuda.empty_cache()` if using CUDA.**
- **Do this every time you switch models or want to free memory.**
---
### **Advanced: Unloading All Models**
If you want to ensure all models are unloaded (e.g., when switching tabs):
```python
def unload_all_models():
model_cache.clear()
gc.collect()
if torch.cuda.is_available():
torch.cuda.empty_cache()
```
---
### **Summary Table**
| Step | CPU | GPU (CUDA) |
|---------------------|-----|------------|
| Delete model object | ✅ | ✅ |
| `gc.collect()` | ✅ | ✅ |
| `torch.cuda.empty_cache()` | ❌ | ✅ |
---