The answer is to change the subscription type from pull to push and set the Cloud Run service as the push endpoint. This directly improves cloud run scaling responsiveness with pub/sub push because push subscriptions eliminate the need for the service to poll for messages; instead, Pub/Sub sends each message as an HTTP request to the endpoint, triggering a new container instance almost instantly. On the Google Professional Cloud Developer exam, this scenario tests your understanding of how event-driven architectures reduce cold-start latency and scaling delays—a common trap is choosing min-instances, which only guarantees a base level of capacity but does not accelerate the initial scale-out when a spike hits. Remember the key distinction: pull subscriptions rely on polling intervals that lag behind traffic bursts, while push subscriptions provide immediate, demand-driven invocations. Memory tip: “Push for punch, pull for pool”—push subscriptions pack a punch on scaling speed, while pull subscriptions are better for steady, pooled workloads.
PCD Integrating Google Cloud services Practice Question
This PCD practice question tests your understanding of integrating google cloud services. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A company has a Cloud Run service that ingests messages from a Cloud Pub/Sub subscription. The service uses automatic scaling based on CPU. Recently, the team noticed that when message volume spikes, the service scales up slowly, causing a backlog. What is the most effective solution to reduce the time to scale out?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Change the subscription type from pull to push and set the Cloud Run service as the push endpoint.
Option A is correct because Cloud Run can use direct Pub/Sub push subscriptions to trigger invocations, which reduces the polling interval and improves scaling responsiveness compared to pull subscriptions with CPU-based scaling. Option B is wrong because min-instances causes idle cost but does not improve scale-up speed when below min; it only ensures a base level. Option C is wrong because Cloud Tasks adds another queueing layer without solving the scaling delay. Option D is wrong because increasing max instances helps during high load but does not speed initial scaling.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Increase the max instances for the Cloud Run service to 100.
Why it's wrong here
Max instances limit the upper bound but do not affect how quickly new instances are created.
✗
Use Cloud Tasks to buffer messages and configure a Cloud Scheduler job to pull from the queue.
Why it's wrong here
This adds overhead and does not address the scaling delay.
✗
Set a minimum number of instances on the Cloud Run service to 5.
Why it's wrong here
Min instances keep idle containers warm but do not improve scale-up time from zero.
✓
Change the subscription type from pull to push and set the Cloud Run service as the push endpoint.
Why this is correct
Push subscriptions invoke the service directly upon message delivery, reducing latency and improving scaling speed.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.
What to study next
Got this wrong? Here's your next step.
Identify which PCD exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Integrating Google Cloud services — This question tests Integrating Google Cloud services — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Change the subscription type from pull to push and set the Cloud Run service as the push endpoint. — Option A is correct because Cloud Run can use direct Pub/Sub push subscriptions to trigger invocations, which reduces the polling interval and improves scaling responsiveness compared to pull subscriptions with CPU-based scaling. Option B is wrong because min-instances causes idle cost but does not improve scale-up speed when below min; it only ensures a base level. Option C is wrong because Cloud Tasks adds another queueing layer without solving the scaling delay. Option D is wrong because increasing max instances helps during high load but does not speed initial scaling.
What should I do if I get this PCD question wrong?
Identify which PCD exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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