Explore crucial concepts of AWS Lambda timeout settings and memory tuning with this quiz, designed to help you optimize function performance and resource allocation. Assess your understanding of best practices, limits, and scenarios for efficient Lambda operation and configuration.
What is the default timeout value set for a newly created Lambda function if you do not customize it?
Explanation: The default timeout value for a Lambda function is 3 seconds unless explicitly changed. Choosing 1 minute or 15 minutes as default is inaccurate, as those are possible maximums but not the preset default. 30 seconds is also incorrect—it’s not the standard starting point. Always check and adjust the timeout when you expect longer processing times.
What is the maximum timeout duration you can set for a single Lambda function invocation?
Explanation: The maximum timeout for Lambda execution is 15 minutes, meaning a function cannot run longer than this period per invocation. While 60 minutes is commonly thought to be a limit, it's too high. 5 minutes is allowed, but the true maximum is higher. 30 seconds is too short and not the maximum.
What is a typical effect of increasing the memory allocation for a Lambda function?
Explanation: Increasing memory allocation not only raises available memory but also allocates more CPU resources proportionally, improving performance. The misconception that only memory changes is incorrect since compute power also scales up. CPU does not decrease when memory increases, and the function timeout does not change automatically with memory adjustments.
If your Lambda function typically completes in under one second, what is an optimal timeout setting?
Explanation: Setting a 5-second timeout provides a small buffer while avoiding unnecessarily long wait times for short functions. A 1-minute or 15-minute setting is excessive and inefficient. 30 minutes is not even a valid option for Lambda. Fine-tuning the timeout protects against delays without impacting resource usage.
What happens if a Lambda function runs out of memory during execution?
Explanation: When a function exceeds its allocated memory, it is forcibly terminated by the platform. Returning null is incorrect, as there is no graceful handling. Functions cannot exceed their memory quota, so continued usage is not possible. Throttling will not resolve an out-of-memory error—termination is the enforced behavior.
What is the highest memory allocation you can configure for a single Lambda function?
Explanation: The current maximum memory allocation for Lambda is 10240 MB per function. 4096 MB and 3008 MB were former or lower limits, but not the present maximum. 128 MB is the minimum allocation and not the maximum. Configuring memory above the allowed maximum is not possible.
How does assigning too much memory to a Lambda function typically affect its cost and performance?
Explanation: Assigning more memory can improve function speed due to increased compute resources but also raises cost since pricing is based on memory and duration. Reducing cost while improving speed is not guaranteed; costs usually rise with greater allocation. More memory never directly slows performance, and cost is always affected by configuration.
If a Lambda function waits idly (such as for an external API), how does the timeout value affect the outcome?
Explanation: Regardless of whether a function is actively processing or waiting, it is terminated as soon as the timeout is reached. Indefinite waiting is not allowed; the maximum execution time is enforced. Idle time counts toward the timeout, and billing includes both computation and waiting periods. The timeout applies to total invocation time.
Which metric should you monitor to identify when your Lambda functions are hitting their timeout limits?
Explanation: Timeout errors are recorded in the Errors metric, allowing you to spot timeout-related terminations. The Duration metric helps track runtime but doesn't directly show failures. Throttles relate to concurrent execution limits rather than timeouts. Invocations track the number of times a function runs, not how it completes.
Which approach is best when setting timeout values for Lambda functions processing small text files?
Explanation: It is generally best to pick a conservative, short timeout and increase it only as necessary, which improves efficiency and avoids long waits in error scenarios. Always using the maximum is not resource-friendly. Disabling timeout is not permitted. Doubling the average may work but can still be excessive for small tasks; start small and adjust based on observed needs.