I'm working on a Python application and running into an issue with Python concurrency. Here's the problematic code:

# Current implementation
def fibonacci(n):
    if n <= 1:
        return n
    return fibonacci(n-1) + fibonacci(n-2)

# This causes RecursionError for large n
result = fibonacci(1000)

The error message I'm getting is: "KeyError: 'missing_key'"

What I've tried so far:

• Used pdb debugger to step through the code
• Added logging statements to trace execution
• Checked Python documentation and PEPs
• Tested with different Python versions
• Reviewed similar issues on GitHub and Stack Overflow

Environment information:

• Python version: 3.11.0
• Operating system: macOS Ventura
• Virtual environment: venv (activated)
• Relevant packages: django, djangorestframework, celery, redis

Any insights or alternative approaches would be very helpful. Thanks!

This Django error typically occurs when you're trying to save a model instance that violates a unique constraint. Here's how to handle it properly:

from django.db import IntegrityError
from django.http import JsonResponse

try:
    user = User.objects.create(
        username=username,
        email=email
    )
except IntegrityError as e:
    if 'username' in str(e):
        return JsonResponse({'error': 'Username already exists'}, status=400)
    elif 'email' in str(e):
        return JsonResponse({'error': 'Email already exists'}, status=400)
    else:
        return JsonResponse({'error': 'Data integrity error'}, status=400)

Always use get_or_create() when you want to avoid duplicates:

user, created = User.objects.get_or_create(
    username=username,
    defaults={'email': email, 'first_name': first_name}
)