Jeff’s Note #
Unlike generic exam dumps, ADH analyzes this scenario through the lens of a Real-World Lead Developer.
For AWS DVA-C02 candidates, the confusion often lies in understanding how to handle runtime limits without modifying existing Lambda code. In production, this is about knowing precisely which Lambda configurations affect timeout behavior versus concurrency and scaling. Let’s drill down.
The Certification Drill (Simulated Question) #
Scenario #
A startup called PixelStream is developing a serverless photo enhancement application. A Lambda function is used to transfer uploaded images from an S3 bucket to an Amazon Rekognition service for processing. During testing, the developer notices that images larger than 2 MB cause the Lambda function to fail with the error: ‘Task timed out after 3.01 seconds.’ The developer is not allowed to change the function code but must fix this timeout issue to handle larger images smoothly.
The Requirement: #
Choose the solution that resolves the timeout error without modifying the Lambda function code itself.
The Options #
- A) Increase the Lambda function’s timeout setting.
- B) Configure the Lambda function to skip processing images larger than 2 MB.
- C) Request an increase in the concurrency quota for the Lambda function.
- D) Enable provisioned concurrency for the Lambda function.
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Correct Answer #
A) Increase the Lambda function’s timeout setting.
Quick Insight: The Developer Imperative #
Lambda functions have a maximum execution time that defaults to 3 seconds but can be extended up to 15 minutes.
Increasing timeout allows the function to complete processing larger payloads without code changes.
Provisioned concurrency controls cold start latency but doesn’t increase timeout.
Concurrency quota limits scaling but not execution length per function invocation.
Skipping images based on size is a business logic change and alters code behavior.
Content Locked: The Expert Analysis #
You’ve identified the answer. But do you know the implementation details that separate a Junior from a Senior?
The Expert’s Analysis #
Correct Answer #
Option A) Increase the Lambda function’s timeout setting.
The Winning Logic #
The core issue is a function timeout error: ‘Task timed out after 3.01 seconds.’ The default Lambda timeout is 3 seconds, which means any invocation exceeding that duration is aborted. As the developer can’t modify the function code, the only avenue to fix this at the Lambda configuration level is to increase the timeout limit.
- By extending the timeout (e.g., to 10 seconds), Lambda allows the function to finish processing larger images without prematurely timing out.
- This solution requires no changes to the function’s logic or packaging.
- It directly addresses the root cause: insufficient execution time.
The Trap (Distractor Analysis): #
- Why not Option B? Skipping processing larger images changes business logic, which violates the requirement to avoid code changes.
- Why not Option C? Concurrency quota affects how many functions run simultaneously; it does not impact how long each run can last.
- Why not Option D? Provisioned concurrency reduces cold start latency but does not extend the maximum execution time. The timeout remains the limiting factor.
The Technical Blueprint #
# Example CLI command to increase Lambda timeout from default 3 to 10 seconds
aws lambda update-function-configuration \
--function-name PixelStreamImageProcessor \
--timeout 10
The Comparative Analysis #
| Option | API Complexity | Performance Impact | Use Case |
|---|---|---|---|
| A | Low | Allows longer processing time, fixes timeouts | Directly resolves timeout errors without code changes |
| B | Low | Avoids processing heavy files but reduces functionality | Changes business logic, disallowed |
| C | Medium | Allows more parallel executions but doesn’t fix execution time | Not related to timeout issues |
| D | Medium | Reduces cold start latency, no effect on timeout | Improves cold start but not runtime |
Real-World Application (Practitioner Insight) #
Exam Rule #
“For the exam, always pick increasing the Lambda timeout setting when the function times out but code changes are not allowed.”
Real World #
“In production, longer-running functions may impact costs; consider asynchronous processing or step functions for bigger workloads.”
(CTA) Stop Guessing, Start Mastering #
Disclaimer
This is a study note based on simulated scenarios for the AWS DVA-C02 exam.