Circuit Breaker Pattern
The circuit breaker pattern is a fault tolerance design pattern that prevents system failures from cascading by temporarily stopping operations when error conditions are detected. Like an electrical circuit breaker that protects circuits from damage, this pattern protects distributed systems by "breaking the circuit" when problems occur.
How circuit breakers work in distributed systems
Circuit breakers monitor for failures and automatically transition between three states:
- Closed: Normal operation, requests flow through
- Open: Requests are immediately rejected without attempting the operation
- Half-Open: Limited requests are allowed to test if the underlying problem is resolved
Implementation considerations
Circuit breakers require careful configuration of several key parameters:
- Error thresholds: The number or rate of failures that trigger the breaker
- Timeout duration: How long the circuit stays open before testing recovery
- Success thresholds: Required successes in half-open state to close
- Failure criteria: What conditions count as failures (timeouts, errors, etc.)
Next generation time-series database
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Applications in time-series systems
In time-series databases and streaming systems, circuit breakers protect against:
- Ingestion overload: Breaking circuits when write throughput exceeds capacity
- Query overload: Protecting against resource-intensive queries
- External dependencies: Managing failures in downstream systems
For example, a circuit breaker might protect a real-time analytics system by temporarily rejecting new queries when error rates spike.
Integration with other patterns
Circuit breakers often work alongside other reliability patterns:
- Backpressure mechanisms for flow control
- Load shedding for graceful degradation
- High Availability architectures
Next generation time-series database
QuestDB is an open-source time-series database optimized for market and heavy industry data. Built from scratch in Java and C++, it offers high-throughput ingestion and fast SQL queries with time-series extensions.
Performance implications
While circuit breakers add some overhead, their benefits usually outweigh the costs:
- Minimal latency impact during normal operation
- Prevents wasted resources on known-failed operations
- Enables faster system recovery by limiting cascading failures
Best practices
- Monitor and alert: Track circuit breaker state changes as key operational metrics
- Configure appropriately: Set thresholds based on actual system behavior
- Test thoroughly: Verify circuit breaker behavior under various failure conditions
- Provide fallbacks: Define alternative behavior when circuits are open
Circuit breakers are essential for building resilient distributed systems, especially in high-throughput time-series applications where maintaining consistent performance is critical.