pocketflow/cookbook/pocketflow-parallel-batch-flow

Parallel Image Processor

Demonstrates how AsyncParallelBatchFlow processes multiple images with multiple filters >8x faster than sequential processing.

Features

graph TD
    subgraph AsyncParallelBatchFlow[Image Processing Flow]
        subgraph AsyncFlow[Per Image-Filter Flow]
            A[Load Image] --> B[Apply Filter]
            B --> C[Save Image]
        end
    end

• Processes images with multiple filters in parallel
• Applies three different filters (grayscale, blur, sepia)
• Shows significant speed improvement over sequential processing
• Manages system resources with semaphores

Run It

pip install -r requirements.txt
python main.py

Output

Parallel Image Processor
------------------------------
Found 3 images:
- images/bird.jpg
- images/cat.jpg
- images/dog.jpg

Running sequential batch flow...
Processing 3 images with 3 filters...
Total combinations: 9
Loading image: images/bird.jpg
Applying grayscale filter...
Saved: output/bird_grayscale.jpg
...etc

Timing Results:
Sequential batch processing: 13.76 seconds
Parallel batch processing: 1.71 seconds
Speedup: 8.04x

Processing complete! Check the output/ directory for results.

Key Points

• Sequential: Total time = sum of all item times

  • Good for: Rate-limited APIs, maintaining order

• Parallel: Total time ≈ longest single item time

  • Good for: I/O-bound tasks, independent operations