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Vibe codingHardvc-g499
Subject Ai code reviewLevel Mid–Senior~18 minCommon in Algorithms & data structures interviewsIndustries Software development

Question

An AI wrote this FastAPI DB dependency. It works under light load, but after a few hours of traffic the service errors with 'QueuePool limit of size 5 overflow 10 reached, connection timed out'. Find the leak.

python
from sqlalchemy.orm import Session def get_db():    db = SessionLocal()    return db @app.get("/items/{item_id}")def read_item(item_id: int, db: Session = Depends(get_db)):    item = db.query(Item).get(item_id)    if not item:        raise HTTPException(404)    return item
What a strong answer looks like

Treat the AI’s output as a draft to verify, not an answer to trust. Name the specific flaw and the input that triggers it, say how you’d catch it — tests, edge cases, reading critically — and how you’d re-prompt or decompose to get it right.

Learn the concepts
Describe your solution

Vibe coding: describe the solution in plain language (or narrate it) and the coach grades your approach. Generating runnable code from your description is coming next.

Run or narrate your approach, then ask the coach.