Pola resiliensi apa sing ngalindungi microservices (circuit breaker, retry, timeout, bulkhead)?

Question

Accepted Answer

Ing sistem terdistribusi, **kabeh perkara bakal gagal sawijining wektu**. Pola resiliensi ngegawe kabar gagal tunggal ora menyebar dadi outage lengkap.

## Pola inti

- **Timeout** — aja mangkat selamanya kanggo response.
- **Retry** — coba maneh kegagalan sementara, karo backoff + jitter.
- **Circuit breaker** — mandheg manggil layanan sing gagal aku supaya bisa bali.
- **Bulkhead** — pisah sumber daya supaya sidependensi alon ora bisa gulung sing liyane.

## Conto circuit breaker

```js
const breaker = new CircuitBreaker(callPaymentService, {
  timeout: 3000,                 // fail the call after 3s
  errorThresholdPercentage: 50,  // open if >50% of calls fail
  resetTimeout: 10000            // after 10s, try one request (half-open)
});
breaker.fallback(() => ({ status: 'queued' })); // graceful degradation
```

## Kaanan circuit breaker

```text
CLOSED ──(failures exceed threshold)──▶ OPEN
  ▲                                       │ (after resetTimeout)
  │ (trial succeeds)                       ▼
  └────────────── HALF-OPEN ◀──────────────┘
                (one trial request)
```

## Bulkhead

```text
[ pool A: 10 threads ]  → payment calls
[ pool B: 10 threads ]  → search calls
If search hangs, it drains pool B only — payments keep working.
```

## Jebakan

**Retry tanpa backoff** nambah beban ing layanan sing wis susah (badai retry). Tansah nambah backoff, jitter, lan tutup retry.

## Mengapa iku penting

Pola iki iku apa nglih siji-layanan kegagalan inevitable dadi fitur degraded tinimbang outage luas-bunder.

Iku gumana bareng: timeouts batas pamuliwa, circuit breakers mandheg palu layanan mati, bulkheads ngemot radius ledakan, lan retries pulih saka blips — ucapno siji lan kegagalan isih menyebar.