Final answer:
Selecting the Throttle option in AWS Lambda allows you to set a limit on the number of concurrent executions for a Lambda function, thus controlling resource usage and maintaining the quality of service by preventing the function from processing too many requests at once.
Step-by-step explanation:
When you select the Throttle option in AWS Lambda, you are intentionally limiting the number of concurrent executions for your Lambda function. Throttling is used to control the scale of function execution in response to incoming events. This is particularly useful in cases where you need to enforce limits to prevent your Lambda functions from consuming excessive resources or reaching the account-level concurrent execution limit. By throttling, you can also maintain the quality of service for your function by not allowing it to be overwhelmed by too many requests at once.
Throttling in AWS Lambda is managed by setting the concurrency control, which has two components. You can set a specific concurrency limit for a function, causing AWS Lambda to only allow that number of function invocations to run concurrently. Alternatively, you can choose to use the Reserved Concurrency setting, which allocates a specific number of invocation slots to a particular function. This reservation ensures that other functions do not use up all available concurrency and that your critical function maintains its ability to execute. If a throttle occurs, AWS Lambda returns a TooManyRequestsException error, and additional retry and back-off logic may be necessary to handle the invocation later.