Jeff’s Note #
Unlike generic exam dumps, ADH analyzes this scenario through the lens of a Real-World Lead Developer.
For DVA-C02 candidates, the confusion often lies in distinguishing how Lambda provisioned concurrency differs technically from reserved concurrency or account limits. In production, this is about knowing exactly how to proactively keep Lambda environments warm to reduce cold start latency in latency-sensitive apps. Let’s drill down.
The Certification Drill (Simulated Question) #
Scenario #
TruPulse Tech, a SaaS provider of real-time analytics dashboards, relies on an Amazon API Gateway API that triggers AWS Lambda functions to process incoming data quickly. Their application is highly sensitive to latency spikes, and users have reported occasional slow responses linked to Lambda cold starts during traffic spikes. The lead developer must optimize the Lambda functions to minimize cold start delays while maintaining scalability.
The Requirement: #
Identify the best approach for configuring the Lambda functions to reduce cold start latency and handle the production load effectively.
The Options #
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A) Publish a new version of the Lambda function. Configure provisioned concurrency. Set the provisioned concurrency limit to meet the company requirements.
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B) Increase the Lambda function’s memory allocation to the maximum value. Increase the Lambda function’s reserved concurrency limit.
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C) Increase the reserved concurrency of the Lambda function to a number that matches the current production load.
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D) Use Service Quotas to request an increase in the Lambda account concurrency limit where the function is deployed.
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Correct Answer #
A
Quick Insight: The Developer Imperative #
Provisioned concurrency is the only built-in Lambda feature that pre-creates execution environments and keeps them initialized and ready to respond immediately. This effectively removes cold starts for the pre-set capacity, making it the best fit for latency-sensitive applications.
Reserved concurrency limits the max concurrent executions, but does not reduce cold start latency by itself.
Requesting account concurrency increases can help scale higher loads but doesn’t keep functions warm.
And simply increasing memory size marginally reduces cold start times but is not sufficient alone.
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
The Winning Logic #
Provisioned concurrency in Lambda enables the developer to specify a fixed number of execution environments that remain initialized and ready to serve requests instantly. This eliminates cold start latency for those concurrencies. It is ideal for latency-sensitive workloads where consistent performance is required. The developer must publish a new function version and enable provisioned concurrency on that version. This approach also supports gradual traffic shifting and version management.
- Increasing memory allocation (Option B) can reduce execution time slightly but does not prevent the cold start initialization delay itself.
- Reserved concurrency (Option C) caps the concurrency to prevent throttling but does nothing to keep instances warm and ready.
- Requesting quota increases (Option D) expands the max account-wide concurrency limit, which supports scaling but offers no cold start mitigation.
The Trap (Distractor Analysis) #
- Why not B? Increasing memory helps speed up the function runtime but does not solve the initial code initialization delay that defines cold start latency.
- Why not C? Reserved concurrency limits concurrency rather than proactively warming instances; cold starts still happen.
- Why not D? Service Quotas request only raise account concurrency limits but do not impact cold start behavior or warming.
The Technical Blueprint #
# Example AWS CLI commands for publishing a new Lambda version and setting provisioned concurrency:
aws lambda publish-version \
--function-name TruPulseProcessor
aws lambda put-provisioned-concurrency-config \
--function-name TruPulseProcessor \
--qualifier <version-number> \
--provisioned-concurrent-executions 10
The Comparative Analysis #
| Option | API Complexity | Performance Impact | Use Case |
|---|---|---|---|
| A | Moderate (new version + provisioned concurrency config) | Cold starts eliminated for provisioned environments — best latency | Latency-sensitive apps needing instant response |
| B | Low (memory update + concurrency reserve) | Slight runtime speedup, no cold start mitigation | Improved throughput, but cold starts remain |
| C | Low (reserved concurrency setting) | Caps max concurrent executions but no cold start effect | Prevent throttling, not latency issue |
| D | Low (quota increase request) | Supports scaling but no cold start impact | Increase account-wide concurrency limits |
Real-World Application (Practitioner Insight) #
Exam Rule #
For the exam, always pick Provisioned Concurrency when you see “reduce cold start latency” for Lambda in a latency-sensitive workload.
Real World #
In some real scenarios, teams might combine provisioned concurrency with memory tuning and function refactoring for optimal performance and cost balance. Also, using Lambda SnapStart (when available) is an emerging option to speedup cold start for Java-based functions.
(CTA) Stop Guessing, Start Mastering #
Disclaimer
This is a study note based on simulated scenarios for the AWS DVA-C02 exam.