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Task Queues

Use task queues to decouple request handling from work processing.

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Task Queues

Task Queue Pattern

Producer → Queue → Worker → Result

Spring Boot Task Queue

@Service
public class TaskQueue {
    private final BlockingQueue<Task> queue = new LinkedBlockingQueue<>();

    public void submit(Task task) {
        queue.offer(task);
    }

    @PostConstruct
    public void startWorkers() {
        ExecutorService executor = Executors.newFixedThreadPool(5);
        for (int i = 0; i < 5; i++) {
            executor.submit(() -> {
                while (true) {
                    Task task = queue.take();
                    process(task);
                }
            });
        }
    }
}

Queue Patterns

Patterns

  • Work Queue: Competing consumers
  • Publish-Subscribe: Multiple consumers
  • Routing: Message filtering
  • Topics: Pattern-based routing

Best Practices

  • Idempotent consumers
  • Dead letter queues
  • Message TTL
  • Monitoring/alerting

Scaling

  • Horizontal: Add consumers
  • Partitioning: Route by key
  • Priority queues: Critical messages

Key Points

  • Understanding Task Queues is essential for production systems
  • Always consider scalability and maintainability
  • Test thoroughly before deploying to production
  • Monitor performance and set up alerting

Common Patterns

  1. Validation: Always validate input at the boundary
  2. Error Handling: Use structured error responses
  3. Logging: Log key events for debugging
  4. Testing: Unit, integration, and load tests
  5. Documentation: Keep docs updated with code changes

Practice Problems

0/3solved
Implement Task Queues

Design and implement a solution for Task Queues in a backend system. Consider scalability, error handling, and production readiness.

Solution
// Task Queues implementation
// Key aspects: validation, error handling, logging, testing

public class TaskQueues {
    // Production-ready implementation
}
Task Queues Edge Cases

Identify and handle edge cases for Task Queues. What happens under high load, with invalid input, or during failures?

Solution
// Edge case handling:
// 1. Null/empty input -> validation
// 2. High load -> rate limiting, queuing
// 3. Failures -> retries, circuit breaker
// 4. Concurrent access -> locks, idempotency
Task Queues Testing Strategy

Write a testing strategy for Task Queues. Include unit tests, integration tests, and performance tests.

Solution
// Test plan:
// - Unit: 80% coverage target
// - Integration: API contracts
// - Performance: latency, throughput
// - Chaos: failure injection

Quiz

1. Task queue decouples?

Question 1 options

2. BlockingQueue does what?

Question 2 options

3. What is the primary purpose of Task Queues?

Question 3 options

4. What is a common mistake when implementing Task Queues?

Question 4 options

Flashcards

Question

Task queue decouples?

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Answer

Producer and consumer

Question

BlockingQueue behavior?

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Answer

Blocks when empty or full

Question

What is Task Queues?

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Answer

Task Queues is a key concept in backend development.

Question

When to use Task Queues?

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Answer

Use Task Queues when building production systems that require reliability, scalability, and maintainability.

Question

Task Queues best practices

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Answer

Follow SOLID principles, write clean code, test thoroughly, document decisions, and monitor in production.

Revision Notes

Key Takeaways

  • 1.Task queues decouple producer and consumer
  • 2.BlockingQueue for in-memory queuing
  • 3.Use thread pools for workers
  • 4.Add persistence for durability

Interview Tips

  • •Implement task queues
  • •Know queue types

Cheat Sheet

Task Queues

  • Decouple: producer → queue → consumer
  • BlockingQueue: blocks when empty/full
  • Workers: thread pool
  • For scale: use message queues (Kafka, RabbitMQ)