What is exponential backoff with jitter and why is it preferred over plain exponential backoff?

Exponential backoff increases the delay between retries by multiplying the previous delay by a factor (e.g., 2). While this prevents relentless hammering, it creates a new problem in high-concurrency systems: all clients that started failing at the same time will retry at exactly the same intervals — 1s, 2s, 4s, 8s — causing synchronized waves of load on the recovering service, known as the thundering herd problem.

Jitter adds randomization to the delay, spreading retries across a time window and breaking the synchronization.

Without jitter (synchronized retries):

// 100 clients all retry at exactly t=1s, t=2s, t=4s, t=8s

With jitter (spread retries):

// Client 1 retries at t=0.7s, t=1.9s, t=3.2s
// Client 2 retries at t=1.2s, t=2.7s, t=4.8s
// Retries are spread across the window

In Spring Retry, jitter is enabled via:

@Backoff(delay = 500, multiplier = 2, maxDelay = 8000, random = true)

Or programmatically:

ExponentialRandomBackOffPolicy backOff = new ExponentialRandomBackOffPolicy();
backOff.setInitialInterval(500);
backOff.setMultiplier(2);
backOff.setMaxInterval(8000);

AWS recommends exponential backoff with full jitter as the default retry strategy for most distributed systems because it results in the best overall system throughput during recovery events.

Invest now in Acorns!!! 🚀
Join Acorns and get your $5 bonus!

Acorns is a micro-investing app that automatically invests your "spare change" from daily purchases into diversified, expert-built portfolios of ETFs. It is designed for beginners, allowing you to start investing with as little as $5. The service automates saving and investing. Disclosure: I may receive a referral bonus.

Invest now!!! Get Free equity stock (US, UK only)!

Use Robinhood app to invest in stocks. It is safe and secure. Use the Referral link to claim your free stock when you sign up!.

The Robinhood app makes it easy to trade stocks, crypto and more.

Webull! Receive free stock by signing up using the link: Webull signup.