AWS Certified DevOps Engineer – ProfessionalResilient Cloud SolutionsMedium
A team is developing a new serverless application using AWS Lambda functions that process millions of events daily. These events are highly variable, with unpredictable spikes in volume. The team observes that during these spikes, new Lambda invocations experience high latency due to cold starts. They need to minimize cold start latency for critical functions to maintain a consistent user experience. What is the most effective solution?
- AImplement a custom warmer function that periodically invokes the critical Lambdas.
- BSwitch from Node.js runtime to a compiled language like Java for the Lambda functions.
- CIncrease the memory allocated to the Lambda functions to speed up execution time.
- DConfigure Lambda Provisioned Concurrency for the critical functions.
Show answer & explanationAnswer & explanation
Correct answer: D. Configure Lambda Provisioned Concurrency for the critical functions.
Lambda Provisioned Concurrency keeps functions initialized and ready to respond instantly, eliminating cold starts for a specified number of concurrent invocations. This directly addresses the problem of high latency during unpredictable spikes due to cold starts.
Why the other options are wrong
- A. Custom warmer functions can help, but they are a manual workaround, less reliable, and harder to manage than native Provisioned Concurrency, which is specifically designed for this problem.
- B. While compiled languages like Java might have longer cold start times than Node.js, switching runtime doesn't eliminate cold starts; it might even make them worse if not optimized. Provisioned Concurrency addresses the cold start issue directly, regardless of runtime.
- C. Increasing memory can reduce execution time and potentially cold start duration, but it doesn't eliminate cold starts themselves, especially for high-volume spikes.
Lambda Provisioned Concurrency
Lambda Provisioned Concurrency keeps a specified number of execution environments initialized and ready to respond to invocations instantly. This eliminates cold start latency for those pre-warmed instances, providing consistent low-latency performance.
- Eliminates cold start latency for pre-warmed instances.
- Ensures consistent low-latency performance for critical functions.
- Configurable per function version or alias.
- You pay for the configured concurrency even when idle.
Memory trick: Provisioned Concurrency keeps your Lambda oven pre-heated, ready for instant baking.