How to Design Error Handling and Retry Mechanisms in Serverless Architecture?

Error handling and retry mechanisms in Serverless architecture are crucial for ensuring application reliability:

Error types:

1. Function errors: Code logic errors, runtime exceptions
2. Dependency service errors: Database connection failures, API call failures
3. Resource limit errors: Memory exceeded, execution timeout
4. Configuration errors: Environment variable errors, insufficient permissions

Error handling strategies:

1. Exception catching

• Global exception handling: Catch all exceptions at the function entry point
• Classified handling: Take different handling strategies based on error types
• Logging: Record detailed error information and stack traces

2. Retry mechanism

• Exponential backoff: Retry intervals grow exponentially to avoid avalanches
• Maximum retry count: Set a reasonable retry limit
• Idempotent design: Ensure retries don't produce side effects

3. Dead Letter Queue (DLQ)

• Failed message handling: Send failed messages to DLQ
• Manual intervention: Manually process messages in DLQ
• Automatic retry: Periodically reprocess messages from DLQ

4. Monitoring and alerting

• Error rate monitoring: Real-time monitoring of function error rates
• Alert mechanism: Trigger alerts when error rate exceeds threshold
• Root cause analysis: Analyze error causes and continuously optimize

Best practices:

1. Graceful degradation: Provide fallback solutions when dependency services are unavailable
2. Circuit breaker: Automatically break when error rate is too high to prevent cascading failures
3. Timeout settings: Set reasonable timeout times for all external calls
4. Test coverage: Write unit tests and integration tests to cover error scenarios

Candidates should be able to share error handling challenges and solutions encountered in actual projects.