Go: What is the difference between context.WithTimeout and context.WithDeadline?

WithTimeout — duration from now. WithDeadline — absolute time.

WithTimeout:

• Relative time.
• From current moment.

1// 5 seconds from now
2ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
3defer cancel()

WithDeadline:

• Absolute time.
• Specific moment.

1// Deadline at specific time
2deadline := time.Now().Add(5 * time.Second)
3ctx, cancel := context.WithDeadline(context.Background(), deadline)
4defer cancel()

Key difference:

• WithTimeout — "5 seconds from now".
• WithDeadline — "at 3:00:05 PM".

Use cases:

• WithTimeout — most common, simple.
• WithDeadline — need specific time.