Bad: FastApi response problems

Question

i create api using fastapi framework and i have deployed on heroku, the main function of this api is i have to send (post method) element as query parameter every 10s and i create path to show all elements sent but i facing problem when i refresh page i didn't get all element sent for example if i send [1, 2, 3, 4, 5, 6, 7, 8, 9] sometimes i get [1, 3, 4, 5, 7, 9] and sometimes i get [2, 6, 8], but in local i have api run perfectly.

from fastapi import FastAPI

app = FastAPI()

hr = []


@app.get("/")
async def api_status():
    return {"message": "api running"}


@app.get("/hr")
async def show_hr_values():
    if hr:
        return hr
    return {"message": "hr empty"}


@app.post("/hr")
async def add_hr_value(hr_value: int):
    hr.append(hr_value)
    return {"message": f"hr = {hr_value} added"}

Answer 1

Heroku will not run your application as just one process. Since you're keeping this data in memory , it will only be updated and kept in that process that receives your request.

Use a database or KV store to store your data instead, so that it's stored in a centralized location that all processes can talk to. Heroku supports managed postgres and redis that you can use for either of these use cases.