AWS DevOps Engineer Professional Practice Test

What is likely the bottleneck for a Lambda function experiencing high request volume?

1. The network connection to the database

2. The default concurrency limit of 1,000 invocations

3. The API Gateway’s request handling capacity

4. The Lambda function's timeout setting

The correct answer is: The default concurrency limit of 1,000 invocations

The default concurrency limit of 1,000 invocations is a significant bottleneck for a Lambda function experiencing high request volume because AWS Lambda has a concurrency limit that restricts the number of simultaneous executions of a function. If your function's execution exceeds this limit, additional requests will be throttled and will not be processed until existing executions complete or until the request volume decreases. In scenarios where high demand is placed on the Lambda function, once the concurrent executions reach the limit of 1,000, any further requests will be queued, which can lead to increased latency or outright rejection of those requests. This throttling behavior is crucial for managing resource allocation within the AWS infrastructure and ensuring that no single function monopolizes resources. Improving request handling capability or optimizing the backend services should also be considered, but the inherent concurrency limit is a primary factor that directly impacts the ability to handle sudden spikes in traffic. Understanding these limits ensures that developers can effectively design their applications to handle traffic more robustly, potentially utilizing multiple Lambda functions or optimizing request flows to remain under concurrency thresholds.