Google ACE Practice Question: Ensuring Successful Operation of a Cloud Solution

Your Cloud Run service is receiving a sudden spike in traffic. You want to ensure that the number of concurrent requests per container instance does not exceed 10 to avoid overloading the backend. Which configuration should you set?

⚠ Common exam trap

ACE often tests the confusion between concurrency (requests per instance) and max-instances (total instances), and candidates frequently pick --max-instances when the question asks about per-instance request limits.

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

✓

Set --concurrency to 10

In Google Cloud Run, the --concurrency flag controls the maximum number of simultaneous requests that a single container instance can handle. Setting --concurrency to 10 ensures that no container instance processes more than 10 concurrent requests, which directly addresses the requirement to prevent backend overload. This is the precise configuration parameter designed for this purpose.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

✗
Set --timeout to 10 seconds
Why it's wrong here
Setting --timeout to 10 seconds limits the maximum duration a single request can take, not the number of simultaneous requests a container instance can handle. A request that needs more than 10 seconds will be terminated, potentially causing errors during heavy load. It does nothing to control concurrency or scaling behavior, so it is not the right knob for a sudden traffic spike.
✓
Set --concurrency to 10
Why this is correct
Correct: --concurrency controls the maximum number of simultaneous requests that each container instance can process at the same time. With a spike, setting it to 10 means an instance will accept only 10 in-flight requests and Cloud Run will automatically spin up additional instances to handle the remaining traffic, preventing any single instance from being overwhelmed. It directly manages per-instance load rather than total capacity or request duration.
✗
Set --max-instances to 10
Why it's wrong here
Setting --max-instances to 10 limits the total number of container instances Cloud Run can create, which is a hard cap on total capacity, not a per-instance concurrency limit. During a spike, once all 10 instances are saturated, new requests are queued or rejected, which can hurt availability. It cannot control how many requests each instance processes concurrently and does not spread load across instances more effectively.
✗
Set --cpu-throttling to true
Why it's wrong here
Setting --cpu-throttling to true does not affect concurrency at all; it controls whether the container's CPU is throttled when the instance is not actively processing requests. With true, Cloud Run only allocates CPU during request handling, which helps reduce costs but has no impact on how many simultaneous requests an instance accepts. It is unrelated to handling a traffic spike and will not change scaling behavior.

Go deeper

Google ACE Practice Question: Ensuring Successful Operation of a Cloud Solution

Why each option matters

Option-by-option breakdown

Related to this question