The answer is to increase the concurrency setting to 200 to reduce latency. This is correct because Cloud Run’s concurrency setting controls how many requests a single instance can handle simultaneously; by raising it from 80 to 200, each instance processes more requests in parallel, which directly reduces the queuing delay caused by the 2-3 second database call. Since CPU usage per instance is only 40%, the instances have ample headroom to handle the increased concurrency without becoming CPU-bound, making this a cost-effective fix for the 10-minute SLA. On the Google Professional Cloud Developer exam, this scenario tests your understanding that concurrency is a tuning lever for I/O-bound workloads—not CPU-bound ones—and a common trap is to add more instances instead of adjusting concurrency. Remember the memory tip: “Low CPU, high wait? Raise concurrency to eliminate the gate.”
PCD Building and testing applications Practice Question
This PCD practice question tests your understanding of building and testing applications. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
You are a Cloud Developer at a fintech company. Your team has developed a Node.js application that processes real-time financial transactions. The application is deployed on Cloud Run and uses Cloud Pub/Sub to receive transaction messages. The application must have high availability and low latency. Recently, the team noticed that during peak hours, the application experiences increased latency and some messages are not processed within the required 10-minute SLA. The team has configured Cloud Run with a minimum of 5 instances and a maximum of 50, with a concurrency setting of 80. The CPU usage per instance rarely exceeds 40% during peak times. The team also uses Cloud Monitoring and Logging for observability. After analyzing the logs, you find that the message processing time increases due to a database call that often takes 2-3 seconds. The Pub/Sub subscription is configured with a delivery deadline of 10 minutes. What should you recommend to reduce latency and ensure messages are processed within SLA?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "minimum / minimize"
Why it matters: Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Increase the concurrency setting to 200 to allow each instance to handle more requests simultaneously, reducing queuing.
Increasing the concurrency setting to 200 allows each Cloud Run instance to handle more requests simultaneously, which reduces the queuing delay caused by the 2-3 second database call. Since CPU usage is only 40%, the instances have headroom to process additional concurrent requests without being CPU-bound, directly addressing the latency issue within the 10-minute SLA.
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 concurrency setting to 200 to allow each instance to handle more requests simultaneously, reducing queuing.
The clue word "minimum / minimize" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Migrate the application to GKE with Horizontal Pod Autoscaler to scale based on custom metrics.
Why it's wrong here
Overkill and doesn't fix the per-request delay.
✗
Increase the CPU limit per container to 2 CPUs to speed up database call.
Why it's wrong here
Database call is network-bound, not CPU-bound.
✗
Increase the minimum number of instances to 50 to ensure capacity during peak hours.
Why it's wrong here
More idle instances don't address per-request processing time.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume low CPU usage means the application is not busy, when in fact the bottleneck is I/O wait from the database call, and increasing concurrency allows the instance to handle more work during those I/O waits.
Detailed technical explanation
How to think about this question
Cloud Run's concurrency setting controls how many requests are routed to a single container instance simultaneously. When concurrency is set too low relative to request duration (e.g., 80 concurrency with 2-3 second database calls), requests queue up behind the long-running database I/O, increasing end-to-end latency. By raising concurrency to 200, each instance can overlap more database calls, improving throughput without needing more instances. This is analogous to increasing the thread pool size in a traditional server—but in Cloud Run, it's managed at the request routing layer.
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.
TExam Day Tips
→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.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Building and testing applications — This question tests Building and testing applications — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Increase the concurrency setting to 200 to allow each instance to handle more requests simultaneously, reducing queuing. — Increasing the concurrency setting to 200 allows each Cloud Run instance to handle more requests simultaneously, which reduces the queuing delay caused by the 2-3 second database call. Since CPU usage is only 40%, the instances have headroom to process additional concurrent requests without being CPU-bound, directly addressing the latency issue within the 10-minute SLA.
What should I do if I get this PCD question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "minimum / minimize". Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
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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