BackgroundTasks zinavyoaje?

Question

Accepted Answer

**`BackgroundTasks`** ya FastAPI inakuruhusu kuendesha kazi **baada ya kurudi jibu** — kwa hivyo mteja anapokea jibu haraka wakati kazi nyingi za kufuatia (kutuma barua pepe, kuandika kumbukumbu, kusafisha) inaendelea nyuma. Imebuniwa na rahisi, kwa kazi ringan.

## Kutumia BackgroundTasks

```python
from fastapi import BackgroundTasks

def send_email(address: str, message: str):
    # slow-ish work that the client shouldn't wait for
    email_client.send(address, message)

@app.post("/signup")
def signup(user: User, background_tasks: BackgroundTasks):   # inject BackgroundTasks
    save_user(user)
    background_tasks.add_task(send_email, user.email, "Welcome!")   # queue it
    return {"message": "User created"}    # RESPONSE returns NOW; email sends AFTER
```

Jumisha parameter ya `BackgroundTasks` na mwito `add_task(func, *args)`. FastAPI hutuma jibu kwanza, kisha inaendesha kazi zilizokusanywa — kwa hivyo mtumiaji hasubiri barua pepe.

## Kazi nyingi na matumizi na tegemezi

```python
@app.post("/order")
def create_order(order: Order, bg: BackgroundTasks):
    bg.add_task(send_confirmation, order.email)
    bg.add_task(update_analytics, order.id)     # multiple tasks run in order, after the response
    return {"status": "created"}
```

## Kizuizi cha msingi: si kwa kazi nzito/muhimu

```text
BackgroundTasks runs IN THE SAME PROCESS as the web server:
  ✗ NO persistence — if the server crashes/restarts, queued tasks are LOST
  ✗ NO retries, scheduling, or distribution
  ✗ Heavy CPU work would still tie up the worker process
→ Good for: quick, non-critical, fire-and-forget tasks (emails, logging, light cleanup)
→ For heavy, critical, retryable, or scheduled jobs → use Celery / ARQ (a real task queue)
```

## Wakati wa kutumia kipi

```text
BackgroundTasks → simple, lightweight, best-effort work tied to a request (no extra infra)
Celery / ARQ    → durable, retryable, scheduled, distributed jobs (needs a broker/workers)
```

## Kwa nini hii ni muhimu

`BackgroundTasks` ni chombo kinachofaa kimebuniwa kwa haja ya kawaida ya kufanya kazi ya kufuatia bila kumkubali mteja — kutuma barua pepe ya karibu, kuandika kumbukumbu, kusafisha kwa mafupi — kuboresha nyakati za majibu kwa mtumiaji.

Kuelewa ni muhimu kwa matukio haya ya kawaida ya mafupi kwa sababu haihitaji miundombinu ya ziada.

Lakini **hatua muhimu sana** ni kujua **mipango yake**: kwa sababu inaendesha katika mchakato sawa na seva wa wavuti, haitoi umiliki (kazi zao huzuia kwa kusimama/kuanzisha upya), hakuna kujaribu tena, hakuna ratiba, na haisiwi kwa kazi nzito au muhimu.

Kutambua hudu hii — kutumia `BackgroundTasks` kwa kazi haraka, zisizo muhimu, "kumvuta na kusahau", na foleni halisi ya kazi kama vile **Celery/ARQ** kwa kazi inayodumu, inayoweza kujaribu tena, iliyopangwa au nzito nyuma — ndio uamuzi muhimu unayozuia kosa la kawaida la kutegemea BackgroundTasks kwa kazi ambayo lazima isiweze kufa, na kuifanya hii ni ujumbe muhimu wa vitendo kwa kujenga programu inayoaminika.