`context.WithDeadline(parent, t)` creates a child context that is canceled at the specific time `t` (a `time.Time`).

Signature: `ctx, cancel := context.WithDeadline(parent, t)`

• Enforce a fixed cutoff time (e.g., must finish before 10:00:05).
• Align timeouts across multiple calls (same end time for several steps).

deadline := time.Now().Add(1500 * time.Millisecond)
ctx, cancel := context.WithDeadline(context.Background(), deadline)
defer cancel()
 
select {
case <-ctx.Done():
    // deadline exceeded or canceled
default:
    // do work
}

• Always call `cancel()` to release resources.
• If you only have a duration, `WithTimeout` is simpler.
• Deadlines propagate to child contexts.

• context.Context
• WithTimeout

• deadline /ˈdedlaɪn/: hạn chót
• cutoff /ˈkʌtɔːf/: mốc dừng
• align /əˈlaɪn/: căn chỉnh/đồng bộ theo cùng mốc
• exceeded /ɪkˈsiːdɪd/: vượt quá