- A
Increase the max instances for the Cloud Run service to 100.
Why wrong: Max instances limit the upper bound but do not affect how quickly new instances are created.
- B
Use Cloud Tasks to buffer messages and configure a Cloud Scheduler job to pull from the queue.
Why wrong: This adds overhead and does not address the scaling delay.
- C
Set a minimum number of instances on the Cloud Run service to 5.
Why wrong: Min instances keep idle containers warm but do not improve scale-up time from zero.
- D
Change the subscription type from pull to push and set the Cloud Run service as the push endpoint.
Push subscriptions invoke the service directly upon message delivery, reducing latency and improving scaling speed.
Question 149 of 999
Improving Cloud Run Scaling Responsiveness with Pub/Sub Push
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?
Quick Answer
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.
Answer choices
Why each option matters
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 D is correct because using a push subscription from Pub/Sub directly triggers Cloud Run invocations, which reduces latency compared to pull subscriptions that require polling. This improves scaling responsiveness during traffic spikes. Option A is wrong because increasing max instances does not accelerate scaling speed; it only sets an upper limit. Option B is wrong because adding Cloud Tasks and Cloud Scheduler introduces extra latency without solving the scaling delay. Option C is wrong because setting a minimum number of instances can reduce cold starts but does not speed up scaling from zero to the minimum; it only ensures a base level of instances are always running.
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
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
What to study next
Got this wrong? Here's your next step.
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FAQ
Questions learners often ask
What does this PCD question test?
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 D is correct because using a push subscription from Pub/Sub directly triggers Cloud Run invocations, which reduces latency compared to pull subscriptions that require polling. This improves scaling responsiveness during traffic spikes. Option A is wrong because increasing max instances does not accelerate scaling speed; it only sets an upper limit. Option B is wrong because adding Cloud Tasks and Cloud Scheduler introduces extra latency without solving the scaling delay. Option C is wrong because setting a minimum number of instances can reduce cold starts but does not speed up scaling from zero to the minimum; it only ensures a base level of instances are always running.
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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Last reviewed: Jun 24, 2026
This PCD practice question is part of Courseiva's free Google Cloud certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the PCD exam.
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