Polly Documentation

Polly is a .NET resilience and transient-fault-handling library that allows developers to express resilience strategies such as Retry, Circuit Breaker, Hedging, Timeout, Rate Limiter and Fallback in a fluent and thread-safe manner.

We are a member of the .NET Foundation!

Resilience strategies

Strategy	Reactive	Premise	AKA	How does the strategy mitigate?
Retry	Yes	Many faults are transient and may self-correct after a short delay.	Maybe it's just a blip	Allows configuring automatic retries.
Circuit-breaker	Yes	When a system is seriously struggling, failing fast is better than making users/callers wait. Protecting a faulting system from overload can help it recover.	Stop doing it if it hurts Give that system a break	Breaks the circuit (blocks executions) for a period, when faults exceed some pre-configured threshold.
Timeout	No	Beyond a certain wait, a success result is unlikely.	Don't wait forever	Guarantees the caller won't have to wait beyond the timeout.
Rate Limiter	No	Limiting the rate a system handles requests is another way to control load. This can apply to the way your system accepts incoming calls, and/or to the way you call downstream services.	Slow down a bit, will you?	Constrains executions to not exceed a certain rate.
Fallback	Yes	Things will still fail - plan what you will do when that happens.	Degrade gracefully	Defines an alternative value to be returned (or action to be executed) on failure.
Hedging	Yes	Things can be slow sometimes, plan what you will do when that happens.	Hedge your bets	Executes parallel actions when things are slow and waits for the fastest one.

Visit the resilience strategies section to understand their structure and explore various configuration methods.

Next steps

Visit the getting started section and learn how to quickly start using Polly.

Articles

Introduction: General information about the project and its goals.
Getting started: A guide to help you get started with the project.
Resilience strategies: A collection of strategies for improving the resilience of your system.
- Timeout: A strategy for setting a maximum time limit for a request.
- Retry: A strategy for retrying failed requests.
- Rate limiter: A strategy for limiting the rate of requests.
- Hedging: A strategy for hedging against long request times.
- Fallback: A strategy for providing a fallback response in case of failure.
- Circuit breaker: A strategy for breaking the circuit when a system is down.
Resilience pipelines: Understanding the use of resilience pipelines.
- Resilience pipeline registry: Exploring the registry that stores resilience pipelines.
vanced topics: A collection of advanced topics for further learning.
- Telemetry and monitoring: Insights into telemetry generated by resilience pipelines and strategies.
- Chaos engineering: Get to know chaos engineering via the project's capabilities.
- Dependency injection: How the project integrates with Dependency Injection.
Community and resources: A collection of resources and community contributions.
- Polly-Contrib projects and libraries: Learn how to contribute to and extend the project ecosystem.
- Libraries and contributions: Find out which libraries the project depends on and who contributes to its development.
- Useful resources and links: Browse through blogs, podcasts, courses, e-books, and other community resources.
API: The API documentation for the project.

Articles (previous Polly versions)

Extensibility (v7): Learn how you can extend Polly with new policies.

Samples