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Debugging Questions

Debugging production issues and incident response questions.

45m
5 problems
Topic Progress0%

Debugging Approach

Systematic Debugging

  1. Identify symptom (error spike, latency increase)
  2. Check recent changes (deployments, config)
  3. Check metrics (CPU, memory, errors)
  4. Check logs (errors, warnings)
  5. Reproduce locally
  6. Identify root cause
  7. Fix and verify
  8. Post-mortem

500 Errors

  1. Logs for stack traces
  2. Recent deployments
  3. Dependencies (DB, external APIs)
  4. Resource utilization

Key Points

  • Understanding Debugging Questions 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

Debugging Tools

Thread Dump

jstack - shows thread states and stack traces

Look for: BLOCKED, WAITING, many threads in same state

Heap Dump

jmap -dump:format=b,file=heap.bin
Analyze with MAT (Memory Analyzer Tool)

Common Issues

Issue Symptom Tool
Memory leak OOM MAT
Thread starvation Timeouts jstack
DB pool exhausted Connection timeout Pool metrics
Deadlock Hung requests Thread dump

Key Points

  • Understanding Debugging Questions 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 Debugging Questions

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

Solution
// Debugging Questions implementation
// Key aspects: validation, error handling, logging, testing

public class DebuggingQuestions {
    // Production-ready implementation
}
Debugging Questions Edge Cases

Identify and handle edge cases for Debugging Questions. 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
Debugging Questions Testing Strategy

Write a testing strategy for Debugging Questions. 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. First step debugging production?

Question 1 options

2. Thread dump shows?

Question 2 options

3. What is the primary purpose of Debugging Questions?

Question 3 options

4. What is a common mistake when implementing Debugging Questions?

Question 4 options

Flashcards

Question

First step debugging?

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Answer

Check recent changes (deployments, config)

Question

Thread dump shows?

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Answer

Thread states and stack traces

Question

What is Debugging Questions?

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Answer

Debugging Questions is a key concept in backend development.

Question

When to use Debugging Questions?

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Answer

Use Debugging Questions when building production systems that require reliability, scalability, and maintainability.

Question

Debugging Questions 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.Check recent changes first
  • 2.Thread dumps: deadlocks, blocked threads
  • 3.Heap dumps + MAT: memory leaks
  • 4.Always do post-mortem

Interview Tips

  • •Walk through a real debugging story
  • •Explain systematic approach
  • •Know jstack, jmap, profiling tools

Cheat Sheet

Debugging Interview

  • First Step: Check recent changes
  • 500 Errors: Logs -> Deploy -> Dependencies -> Resources
  • Tools: jstack (threads), jmap (heap), MAT (analysis)