PCDOE Optimizing service performance Practice Question
This PCDOE practice question tests your understanding of optimizing service performance. 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 DevOps team uses Cloud Run for a containerized application that processes real-time financial data. The service has a concurrency setting of 80, and instances are scaled based on CPU usage. During market volatility, the service experiences high latency and some requests timeout. Cloud Monitoring shows that the average CPU utilization is 40%, but the instance count spikes to the maximum allowed. What is the most likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The concurrency setting is too low, causing many instances to be created.
With a concurrency setting of 80, each instance can handle up to 80 simultaneous requests. However, if the actual request rate exceeds 80 per instance, Cloud Run will spin up new instances. During market volatility, the request volume spikes, causing the instance count to hit the maximum even though average CPU utilization is only 40%. This indicates that the concurrency limit is too low for the burst traffic, forcing excessive instance creation and leading to high latency and timeouts due to instance startup overhead.
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.
✓
The concurrency setting is too low, causing many instances to be created.
Why this is correct
Low concurrency increases instance count, each handling few requests, causing underutilization.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The max instances limit is set too low, causing requests to queue.
Why it's wrong here
If max instances were too low, the instance count would be capped, not spiked.
✗
The service uses too much memory, causing cold starts.
Why it's wrong here
Memory issues would show in memory metrics, not CPU utilization.
✗
The CPU utilization target for autoscaling is set too high, causing slow scaling.
Why it's wrong here
A high CPU target would delay scaling, leading to high latency but not high instance count.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Google Cloud often tests the misconception that CPU utilization is the primary driver of Cloud Run scaling, when in fact concurrency settings and request queuing are the dominant factors in burst scenarios.
Trap categories for this question
Command / output trap
Memory issues would show in memory metrics, not CPU utilization.
Detailed technical explanation
How to think about this question
Cloud Run's autoscaler uses the concurrency setting as a key input: it aims to keep the number of concurrent requests per instance at or below the configured value. When traffic bursts exceed this threshold, the scaler creates new instances, but each new instance incurs a cold start penalty (container startup, health checks). In real-time financial data processing, even a few seconds of cold start can cause timeouts, especially if the burst is short-lived and the scaler over-provisions. The 40% average CPU utilization indicates that instances are underutilized on CPU but are being created due to concurrency pressure, not CPU load.
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.
Optimizing service performance — This question tests Optimizing service performance — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The concurrency setting is too low, causing many instances to be created. — With a concurrency setting of 80, each instance can handle up to 80 simultaneous requests. However, if the actual request rate exceeds 80 per instance, Cloud Run will spin up new instances. During market volatility, the request volume spikes, causing the instance count to hit the maximum even though average CPU utilization is only 40%. This indicates that the concurrency limit is too low for the burst traffic, forcing excessive instance creation and leading to high latency and timeouts due to instance startup overhead.
What should I do if I get this PCDOE 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: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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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