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Scheduled Tasks

Use Spring @Scheduled for time-based task execution.

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Scheduled Tasks

Fixed Rate vs Fixed Delay

@Scheduled(fixedRate = 5000)    // Every 5 sec (from start)
public void fixedRate() { ... }

@Scheduled(fixedDelay = 5000)   // Every 5 sec (after completion)
public void fixedDelay() { ... }

Thread Pool

@Configuration
@EnableScheduling
public class SchedulerConfig implements SchedulingConfigurer {
    @Override
    public void configureTasks(ScheduledTaskRegistrar registrar) {
        registrar.setScheduler(Executors.newScheduledThreadPool(5));
    }
}

Best Practices

Key Principles

  1. Follow SOLID principles
  2. Write clean, readable code
  3. Test thoroughly
  4. Document decisions
  5. Monitor in production

Implementation

  • Start simple, refactor as needed
  • Use established patterns
  • Consider trade-offs
  • Review with peers

Continuous Improvement

  • Learn from incidents
  • Update documentation
  • Share knowledge
  • Mentor others

Key Points

  • Understanding Scheduled Tasks 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 Scheduled Tasks

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

Solution
// Scheduled Tasks implementation
// Key aspects: validation, error handling, logging, testing

public class ScheduledTasks {
    // Production-ready implementation
}
Scheduled Tasks Edge Cases

Identify and handle edge cases for Scheduled Tasks. 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
Scheduled Tasks Testing Strategy

Write a testing strategy for Scheduled Tasks. 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. fixedRate vs fixedDelay?

Question 1 options

2. Concurrent scheduled tasks?

Question 2 options

3. What is the primary purpose of Scheduled Tasks?

Question 3 options

4. What is a common mistake when implementing Scheduled Tasks?

Question 4 options

Flashcards

Question

fixedRate vs fixedDelay?

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Answer

fixedRate: from start. fixedDelay: after completion.

Question

Scheduled thread pool?

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Answer

Controls concurrent task execution

Question

What is Scheduled Tasks?

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Answer

Scheduled Tasks is a key concept in backend development.

Question

When to use Scheduled Tasks?

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Answer

Use Scheduled Tasks when building production systems that require reliability, scalability, and maintainability.

Question

Scheduled Tasks 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.fixedRate: from start, fixedDelay: after completion
  • 2.Configure thread pool for concurrency
  • 3.Default single-threaded
  • 4.Consider distributed scheduling

Interview Tips

  • •Know fixedRate vs fixedDelay
  • •Configure thread pool

Cheat Sheet

Scheduled Tasks

  • fixedRate: from start
  • fixedDelay: after completion
  • Thread pool: controls concurrency
  • Default: single-threaded