December 2019 Summaries

The Amazon Builders' Library is a collection of articles written by principal engineers at Amazon that explain how the company builds scalable and resilient systems. The library's first article, "Timeouts, retries and backoff with jitter," provides insights into the use of timeouts, retries, and exponential backoff to handle errors in system calls, as well as the importance of injecting randomness (jitter) to avoid clients retrying at the same time. Amazon chooses an acceptable rate of false timeout and uses this information to set a dynamic timeout value on remote and cross-process calls. The library also discusses the use of circuit breakers, idempotency, and jitter in APIs with side effects, as well as the importance of knowing which errors to retry.

Amazon Lambda's Provisioned Concurrency feature offers control over the performance of serverless applications, enabling adaptive scaling and reducing cold starts. This feature is particularly useful for applications with predictable traffic patterns or those that require guaranteed latency, such as a food delivery service experiencing spikes in deliveries during lunch and dinner times. By using Provisioned Concurrency, developers can avoid cold starts, improve user experience, and reduce costs associated with on-demand concurrency. The feature works seamlessly with AWS Auto Scaling, allowing for automatic scaling based on utilization level or schedule. Lumigo, a serverless monitoring solution, also provides insights into cold starts and performance issues, enabling fine-tuning of Provisioned Concurrency to minimize costs and improve application performance.