Queues

Cards

1. A job needs a 200 MB video. Why not put the file in the queue message? easy Flashcard
2. Several workers pulling from one queue, so that each message is handled by only one of them, is the _____ pattern. easy Fill in the blank
3. One message makes the consumer fail every time it is processed. What should happen to it? easy Multiple choice
4. Why put a queue between a bursty producer and a slower consumer? easy Flashcard
5. An "order placed" event must reach the email service, the analytics service and the warehouse service. Which messaging model fits? easy Multiple choice
6. Which metric best tells you a worker fleet should scale up? easy Multiple choice
7. Password-reset emails wait behind a 10-million-message newsletter in the same queue. How do you fix it? easy Flashcard
8. 3,000 messages arrive per second, and each takes a worker 50 ms to process, one at a time. How many workers keep up? easy Estimate
9. Your queue delivers at least once. What must every consumer do? medium Flashcard
10. After an outage, a queue holds 1.8 million messages. Consumers process 2,000 a second, while producers keep adding 1,500 a second. How long until the backlog is gone? medium Estimate
11. What is backpressure, and why is an unbounded queue not a substitute for it? medium Flashcard
12. Feeds are built by fan-out on write. A celebrity with 50 million followers posts. What do large feed systems do? medium Multiple choice
13. A consumer's call to a provider fails. How do you retry it later without blocking the messages behind it? medium Flashcard
14. Fan-out on write versus fan-out on read for a feed: what does each cost? medium Flashcard
15. When does a log like Kafka fit better than a queue like SQS or RabbitMQ? medium Multiple choice
16. Events for each bank account must be processed in order, but the total volume needs hundreds of consumers. What do you do? medium Multiple choice
17. Why must a new post be stored durably before its fan-out is queued? medium Flashcard
18. In SQS, a message a consumer has received is hidden from other consumers for the _____. If the consumer does not delete it before that ends, the message becomes visible and is _____. medium Fill in the blank