backoff

Control how the delay between retries changes over time.

Syntax

result = Module(args) with retry: N, delay: D, backoff: <strategy>

Type: Strategy enum (fixed, linear, exponential)

Description

The backoff option determines how the delay between retry attempts increases (or stays constant). It works together with delay to calculate the actual wait time before each retry.

When to use each strategy

Use exponential for external APIs with rate limits (respects "back off" signals). Use linear when you expect gradual service recovery. Use fixed for internal services with predictable behavior.

Strategies

fixed

Constant delay between all retries. This is the default if backoff is not specified.

result = Service(input) with retry: 4, delay: 1s, backoff: fixed

Delays: 1s, 1s, 1s, 1s

linear

Delay increases linearly with each attempt (N × base delay).

result = Service(input) with retry: 4, delay: 1s, backoff: linear

Delays: 1s, 2s, 3s, 4s

exponential

Delay doubles with each attempt (2^(N-1) × base delay), capped at 30 seconds.

result = Service(input) with retry: 4, delay: 1s, backoff: exponential

Delays: 1s, 2s, 4s, 8s

Delay Table

Given delay: 1s:

Retry #	Fixed	Linear	Exponential
1 → 2	1s	1s	1s
2 → 3	1s	2s	2s
3 → 4	1s	3s	4s
4 → 5	1s	4s	8s
5 → 6	1s	5s	16s
6 → 7	1s	6s	30s (capped)
7 → 8	1s	7s	30s (capped)

Examples

Exponential Backoff for Rate Limiting

response = RateLimitedApi(request) with
    retry: 5,
    delay: 500ms,
    backoff: exponential

Respects rate limits by backing off exponentially: 0.5s, 1s, 2s, 4s, 8s.

Linear Backoff for Gradual Recovery

result = RecoveringService(data) with
    retry: 5,
    delay: 2s,
    backoff: linear

Gives the service increasing time to recover: 2s, 4s, 6s, 8s, 10s.

Fixed Backoff for Consistent Behavior

cached = RefreshCache(key) with
    retry: 3,
    delay: 1s,
    backoff: fixed

Predictable timing: 1s, 1s, 1s.

Behavior

The backoff strategy affects the computeDelay function:

delay = base_delay × multiplier

where multiplier for attempt N is:
  fixed:       1
  linear:      N
  exponential: 2^(N-1)  (capped so delay ≤ 30s)

Related Options

• delay - Required base delay value
• retry - Required for backoff to have effect
• timeout - Time limit per attempt

Diagnostics

Warning	Cause
backoff without delay	Backoff requires a base delay to multiply
backoff without retry	Backoff has no effect without retry

Best Practices

• Use exponential for external APIs with rate limits
• Use linear when you expect gradual service recovery
• Use fixed for internal services with consistent behavior
• Combine with reasonable timeout to avoid long waits