Resilience4J: Intro to Rate Limiter

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Resilience4J is a popular Java library that provides developers with a set of tools for building resilient and fault-tolerant applications. One of the key components of Resilience4J is the Rate Limiter, which can be used to throttle the rate of incoming requests to a service or API. In this blog, we will explore the Resilience4J Rate Limiter and its benefits.

What is the Resilience4J Rate Limiter?

The Resilience4J RateLimiter is a component that can be used to control the rate of incoming requests to a service. It works by setting a maximum rate of requests that can be processed per unit of time. When the rate limit is reached, any additional requests are rejected or delayed until the rate drops below the limit. The Resilience4J Rate Limiter is designed to be easy to use and highly configurable, making it a popular choice among Java developers.

Benifits of Resilience4J RateLimiter:

Here are some benefits of using Resilience4j Rate Limiter:

Improved system performance: By limiting the number of requests made to a service or API, the system’s overall performance can be improved by reducing the load on the system and preventing it from becoming overwhelmed.
Reduced downtime: Limiting the number of requests can help prevent service downtime due to resource exhaustion or other issues that may arise from excessive requests.
Better user experience: Rate limiting helps ensure that users of the service or API receive a consistent experience, even during periods of high traffic.
Protection against attacks: Rate limiting can help protect against DoS (Denial of Service) attacks, where an attacker floods a service with excessive requests to cause it to crash or become unresponsive.
Customizable configuration: Resilience4j Rate Limiter provides customizable configuration options, such as rate limit capacity, duration, and refresh interval, allowing users to tailor the rate limiting to meet their specific needs.

How to use the Resilience4J RateLimiter?

To use the Resilience4J Rate Limiter, you will first need to add the Resilience4J dependency to your project. Once you have added the dependency, you can create a new Rate Limiter instance by using the RateLimiterRegistry class. Here are the steps to follow:

Step 1: Add the Resilience4J dependency to your project

<dependency>

  <groupId>io.github.resilience4j</groupId>

  <artifactId>resilience4j-ratelimiter</artifactId>

  <version>1.7.1</version>

</dependency>

Alternatively, if you are using Gradle, you can add the following dependency to your build.gradle file:

implementation 'io.github.resilience4j:resilience4j-ratelimiter:1.7.1'

Step 2: Create a new Rate Limiter instance

Once you have added the Resilience4J dependency to your project, you can create a new Rate Limiter instance by using the RateLimiterRegistry class. Here is how we can do this:

RateLimiterConfig config = RateLimiterConfig.custom()

    .limitForPeriod(10)

    .limitRefreshPeriod(Duration.ofSeconds(1))

    .timeoutDuration(Duration.ofMillis(100))

    .build();

RateLimiterRegistry registry = RateLimiterRegistry.of(config);

RateLimiter rateLimiter = registry.rateLimiter("myRateLimiter");

In this example, we are creating a new Rate Limiter instance with a limit of 10 requests per second. We are also setting a timeout of 100 milliseconds, which means that any requests that take longer than this will be rejected. Once you have created the Rate Limiter instance, you can use it to control the rate of incoming requests to your service.

Step 3: Decorate your methods with the Rate Limiter

To use the Rate Limiter to control the rate of incoming requests to your service, you will need to decorate your methods with the Rate Limiter. You can do this by using the decorateSupplier method.

Supplier<Response> supplier = () -> myService.doSomething();

Supplier<Response> decoratedSupplier = 

RateLimiter.decorateSupplier(rateLimiter, supplier);

Response response = Try.ofSupplier(decoratedSupplier)

    .recover(throwable -> fallbackResponse)

    .get();

In this example, we are using the Resilience4J Rate Limiter to control the rate of incoming requests to the myService service. We are using the decorateSupplier method to wrap the myService.doSomething() method with the Rate Limiter, which will ensure that the rate of incoming requests is throttled to the configured limit. If any exceptions occur during the execution of the myService.doSomething() method, we will recover by returning a fallback response.

Conclusion

The Resilience4J Rate Limiter is a powerful tool that can be used to control the rate of requests to a service or API. By setting a maximum rate of requests that can be processed per unit of time, you can prevent overloading your service with too many requests and ensure that it remains responsive and available to users.

With the Resilience4J library, it is easy to create and configure a Rate Limiter instance, and to decorate your methods with the Rate Limiter to control the rate of incoming requests.

For more information please follow this https://resilience4j.readme.io/docs/ratelimiter