The answer is to reduce concurrency per container, ideally to 10, because the root cause is CPU saturation from handling too many simultaneous requests. When Cloud Run high CPU latency spikes occur alongside 100% CPU utilization but only 70% memory, the bottleneck is clearly compute, not memory; each container processing 80 concurrent requests becomes overwhelmed, causing requests to queue and eventually time out with HTTP 500 errors. On the Google Professional Cloud DevOps Engineer exam, this scenario tests your understanding of Cloud Run’s concurrency model and the relationship between request volume and resource limits—a common trap is to assume memory is the issue or to scale horizontally instead of reducing per-container load. Remember the memory tip: “CPU capped? Cut concurrency back.”
PCDOE Managing service incidents Practice Question
This PCDOE practice question tests your understanding of managing service incidents. 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 uses Cloud Run for a stateless API service with concurrency set to 80. During a traffic spike, some requests return HTTP 500 errors and latency spikes. Cloud Monitoring shows container CPU utilization at 100% and memory usage at 70%. What is the most likely cause and the best first step?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "best"
Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Clue: "first"
Why it matters: Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
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
✓
Concurrency per container is too high; reduce concurrency to 10
The correct answer is A because with CPU at 100% and memory at only 70%, the bottleneck is CPU, not memory. Cloud Run containers handle requests concurrently; setting concurrency to 80 means each container processes up to 80 requests simultaneously. When CPU is saturated, requests queue up, causing latency spikes and eventual HTTP 500 errors as the container becomes unresponsive. Reducing concurrency to 10 lowers the per-container request load, allowing each request to complete before CPU saturation occurs.
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.
✓
Concurrency per container is too high; reduce concurrency to 10
Why this is correct
Lowering concurrency reduces CPU contention, preventing timeouts and 500s.
Clue confirmation
The clue words "best", "first", "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Maximum instances limit is too low; increase from 10 to 100
Why it's wrong here
Cloud Run scales automatically; max instances limit prevents unbounded scaling but 500s indicate per-instance overload.
✗
Min idle instances is too low; set min idle to 5 to reduce cold starts
Why it's wrong here
Cold starts cause latency but not 500s; CPU is already 100%.
✗
Memory limit is too low; increase memory from 256 MiB to 512 MiB
Why it's wrong here
Memory usage is only 70%, so memory is not the bottleneck.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Google Cloud often tests the misconception that HTTP 500 errors during spikes are always due to insufficient instances or memory, but the key diagnostic clue here is CPU at 100% with memory well below limit, pointing to concurrency overload as the root cause.
Detailed technical explanation
How to think about this question
Cloud Run's concurrency setting controls how many requests a single container instance can handle in parallel. When CPU reaches 100%, the container's request queue grows, and the HTTP server (e.g., Gunicorn or Express) may start rejecting requests with 503 or 500 errors due to timeouts. Under the hood, Cloud Run uses the Knative Serving autoscaler, which bases scaling decisions on concurrency metrics; if concurrency is set too high, the autoscaler may not trigger new instances quickly enough because it sees the existing container as still 'available' despite being CPU-bound.
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
A cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
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.
Managing service incidents — This question tests Managing service incidents — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Concurrency per container is too high; reduce concurrency to 10 — The correct answer is A because with CPU at 100% and memory at only 70%, the bottleneck is CPU, not memory. Cloud Run containers handle requests concurrently; setting concurrency to 80 means each container processes up to 80 requests simultaneously. When CPU is saturated, requests queue up, causing latency spikes and eventual HTTP 500 errors as the container becomes unresponsive. Reducing concurrency to 10 lowers the per-container request load, allowing each request to complete before CPU saturation occurs.
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: "best", "first", "most likely". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
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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