Google Cloud Professional Data Engineer — Question 308

You have Cloud Functions written in Node.js that pull messages from Cloud Pub/Sub and send the data to BigQuery. You observe that the message processing rate on the Pub/Sub topic is orders of magnitude higher than anticipated, but there is no error logged in Cloud Logging. What are the two most likely causes of this problem? (Choose two.)

Answer options

• A. Publisher throughput quota is too small.
• B. Total outstanding messages exceed the 10-MB maximum.
• C. Error handling in the subscriber code is not handling run-time errors properly.
• D. The subscriber code cannot keep up with the messages.
• E. The subscriber code does not acknowledge the messages that it pulls.

Correct answer: C, E

Explanation

The correct answers are C and E. C is valid because if error handling is inadequate, it may not log or manage run-time errors, leading to a bottleneck. E is correct as well because if messages are not acknowledged, they will be redelivered, causing the subscriber to lag behind. Options A and B are incorrect because they do not directly relate to the processing rate issue described.