- A
Increase the number of replicas of the payment validation service to 10 to handle peak load.
Why wrong: The payment service has low error rate and latency within normal range; increasing replicas may not resolve the issue and is not the first step.
- B
Check the garbage collection logs of the checkout service pods to identify if long GC pauses coincide with the latency spikes.
Periodic latency spikes are a classic symptom of JVM garbage collection. Checking GC logs will help confirm if this is the cause.
- C
Enable connection pooling and retries with exponential backoff in the checkout service for the HTTP call to the payment service.
Why wrong: This can improve resilience but does not address the root cause; it may mask the problem.
- D
Investigate the checkout service pod restarts due to liveness probe failures, as 'connection reset by peer' indicates pod instability.
Why wrong: While 'connection reset by peer' can indicate pod restarts, the latency pattern is more consistent with GC pauses; pod restarts would likely cause more frequent errors and a different latency pattern.
Quick Answer
The answer is to check the garbage collection logs of the checkout service pods. This is the correct first action because the pattern of intermittent latency spikes lasting 1-2 seconds every 5-10 minutes, with no CPU or memory pressure and no database issues, is a textbook symptom of stop-the-world garbage collection pauses in a Java-based microservice. On the Google Professional Cloud DevOps Engineer exam, this scenario tests your ability to distinguish between application-level performance issues and infrastructure bottlenecks, with the common trap being to immediately blame the database or downstream dependencies like the payment service. Remember the mnemonic "GC = Giant Clue": when you see periodic, short-lived latency spikes under steady resource utilization, always check garbage collection logs before refactoring code or scaling infrastructure.
PCDOE Managing service incidents Practice Question
This PCDOE practice question tests your understanding of managing service incidents. 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 Site Reliability Engineer (SRE) for an e-commerce platform running on Google Kubernetes Engine (GKE) with a microservices architecture. Your team uses Cloud Monitoring for alerting and Cloud Logging for centralized logs. Recently, during a flash sale event, you observed intermittent latency spikes in the checkout service, causing checkout failures and abandoned carts. The latency spikes last 1-2 seconds and occur roughly every 5-10 minutes during peak traffic. The checkout service runs as a Deployment with 10 replicas, each with resource requests of 500m CPU and 512Mi memory. The service has a Service Level Objective (SLO) of 99.9% of requests completing in under 1 second (p99 latency < 1s). Current p99 latency is 2.1s during peak. You reviewed the Cloud Monitoring dashboard and noticed that CPU utilization across pods is around 60%, memory around 50%, and there are no OOM kills. The logs show occasional 'connection reset by peer' errors in the checkout service logs, but no consistent pattern. You suspect the issue might be related to the database (Cloud SQL) or a downstream dependency. After checking the database, you find that query latency is normal. You also notice that the checkout service makes a synchronous HTTP call to a payment validation service that runs as a separate Deployment with 3 replicas. The payment service's p99 latency is 500ms, but its error rate is below 1%. Your task is to identify the most likely cause of the intermittent latency spikes and propose a remediation. Which action should you take first?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
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 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
Check the garbage collection logs of the checkout service pods to identify if long GC pauses coincide with the latency spikes.
The intermittent latency spikes every 5-10 minutes with no CPU/memory pressure or database issues strongly suggest a periodic process like garbage collection. Java-based services (common in microservices) can experience stop-the-world GC pauses that cause latency spikes of 1-2 seconds, matching the observed pattern. Checking GC logs is the fastest way to confirm this before making architectural changes.
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 number of replicas of the payment validation service to 10 to handle peak load.
Why it's wrong here
The payment service has low error rate and latency within normal range; increasing replicas may not resolve the issue and is not the first step.
- ✓
Check the garbage collection logs of the checkout service pods to identify if long GC pauses coincide with the latency spikes.
Why this is correct
Periodic latency spikes are a classic symptom of JVM garbage collection. Checking GC logs will help confirm if this is the cause.
Clue confirmation
The clue words "first", "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Enable connection pooling and retries with exponential backoff in the checkout service for the HTTP call to the payment service.
Why it's wrong here
This can improve resilience but does not address the root cause; it may mask the problem.
- ✗
Investigate the checkout service pod restarts due to liveness probe failures, as 'connection reset by peer' indicates pod instability.
Why it's wrong here
While 'connection reset by peer' can indicate pod restarts, the latency pattern is more consistent with GC pauses; pod restarts would likely cause more frequent errors and a different latency pattern.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Google Cloud often tests the ability to distinguish between symptoms (connection resets, latency spikes) and root causes (GC pauses, thread pool exhaustion) by presenting plausible but superficial fixes like scaling or retries, while the correct answer requires analyzing internal service behavior.
Detailed technical explanation
How to think about this question
In Java applications on GKE, the default G1 garbage collector can cause 'stop-the-world' pauses that last hundreds of milliseconds to seconds, especially under heap pressure. These pauses can be observed in GC logs (enabled via -Xlog:gc*:file=/dev/stdout) and often coincide with latency spikes. The 5-10 minute interval matches typical GC cycles for moderate heap sizes, and the 'connection reset by peer' errors occur because the service is frozen during GC and cannot respond to keepalive probes or incoming requests.
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 media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
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.
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Managing service incidents — study guide chapter
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FAQ
Questions learners often ask
What does this PCDOE question test?
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: Check the garbage collection logs of the checkout service pods to identify if long GC pauses coincide with the latency spikes. — The intermittent latency spikes every 5-10 minutes with no CPU/memory pressure or database issues strongly suggest a periodic process like garbage collection. Java-based services (common in microservices) can experience stop-the-world GC pauses that cause latency spikes of 1-2 seconds, matching the observed pattern. Checking GC logs is the fastest way to confirm this before making architectural changes.
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: "first", "most likely". Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 30, 2026
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