During RPC calls, network anomalies, service failures, and other issues are inevitable. Comprehensive fault tolerance mechanisms are needed to ensure system stability:
1. Timeout Mechanism
- Purpose: Prevents clients from waiting indefinitely
- Implementation: Set reasonable timeout values (connection timeout, read timeout)
- Strategy: Dynamically adjust based on network conditions and business requirements
- Example: Dubbo's timeout configuration, gRPC's deadline
2. Retry Mechanism
- Applicable Scenarios: Network jitter, temporary failures
- Retry Strategies:
- Exponential Backoff: Interval gradually increases with each retry
- Fixed Interval: Same interval for each retry
- Maximum Retry Count: Avoid infinite retries
- Note: Idempotency design to avoid data inconsistency from repeated execution
3. Circuit Breaker
- Principle: When failure rate reaches threshold, fail fast to avoid cascading failures
- States: Closed, Open, Half-Open
- Implementation: Hystrix, Resilience4j, Sentinel
- Parameter Configuration: Failure rate threshold, timeout, recovery time
4. Rate Limiting
- Purpose: Protect services from being overloaded
- Algorithms:
- Token Bucket
- Leaky Bucket
- Fixed Window
- Sliding Window
- Implementation: Guava RateLimiter, Redis + Lua
5. Fallback
- Purpose: Provide backup solutions when services are unavailable
- Strategies:
- Return default values
- Return cached data
- Call backup services
- Return friendly error messages
6. Load Balancing
- Algorithms:
- Round Robin
- Random
- Least Connections
- Consistent Hash
- Health Check: Periodically detect health status of service instances
7. Service Registration and Discovery
- Purpose: Dynamically manage service instances
- Implementation: Consul, Etcd, Zookeeper, Nacos
- Features: Health check, service eviction, automatic registration
8. Distributed Tracing
- Purpose: Quickly locate problems
- Implementation: Zipkin, Jaeger, SkyWalking
- Information: Request ID, call chain, timing statistics
Best Practices:
- Combine multiple fault tolerance mechanisms
- Configure different fault tolerance strategies based on business importance
- Monitor and alert to discover problems in time
- Regularly drill failure scenarios