Java rate-limiting library based on token-bucket algorithm.

Bucket4j basic features

• Absolutely non-compromise precision - Bucket4j does not operate with floats or doubles, all calculation are performed in the integer arithmetic, this feature protects end users from calculation errors involved by rounding.
• Effective implementation in terms of concurrency:
  • Bucket4j is good scalable for multi-threading case it by defaults uses lock-free implementation.
  • In same time, library provides different concurrency strategies that can be chosen when default lock-free strategy is not desired.
• Effective API in terms of garbage collector footprint: Bucket4j API tries to use primitive types as much as it is possible in order to avoid boxing and other types of floating garbage.
• Pluggable listener API that allows to implement monitoring and logging.
• Rich diagnostic API that allows to investigate internal state.
• Rich configuration management - configuration of the bucket can be changed on fly

Bucket4j distributed features

In additional to basic features described above, Bucket4j provides ability to implement rate-limiting in cluster of JVMs:

• Bucket4j out of the box supports any GRID solution which compatible with JCache API (JSR 107) specification.
• Bucket4j provides the framework that allows to quickly build integration with your own persistent technology like RDMS or a key-value storage.
• For clustered usage scenarios Bucket4j supports asynchronous API that extremely matters when going to distribute world, because asynchronous API allows avoiding blocking your application threads each time when you need to execute Network request.

Supported JCache compatible(or similar) back-ends

In addition to local in-memory buckets, the Bucket4j supports clustered usage scenario on top of following back-ends:

Back-end	Async supported	Optimized serialization	Thin-client support	Documentation link
JCache API (JSR 107)	No	No	No	bucket4j-jcache
Hazelcast	Yes	Yes	Planned	bucket4j-hazelcast
Apache Ignite	Yes	n/a	Yes	bucket4j-ignite
Inifinispan	Yes	Yes	No	bucket4j-infinispan
Oracle Coherence	Yes	Yes	No	bucket4j-coherence

Non-JVM back-ends

Bucket4j authors strongly recommends to use JVM based back-ends when possible, but for cases where it is not possible Bucket4j provides following integrations with non-JVM based storages:

In addition to local in-memory buckets, the Bucket4j supports clustered usage scenario on top of following back-ends:

Back-end	Async supported	Documentation link
Redis/Redisson	Yes	bucket4j-redis/Redisson
Redis/Jedis	No	bucket4j-redis/Jedis
Redis/Lettuce	Yes	bucket4j-redis/Lettuce
MySQL	No	bucket4j-mysql
PostgreSQL	No	bucket4j-postgresql
DynamoDb	No	bucket4j-dynamodb

Local caches support

Sometimes you are having deal with bucket per key scenarios but distributed synchronization is unnecessary, for example where request stickiness is provided by a load balancer, or other use-cases where stickiness can be achieved by the application itself, for example, Kafka consumer. For such scenarios Bucket4j provides support for following list of local caching libraries:

Back-end	Documentation link
Caffeine	bucket4j-caffeine

Documentation

• Official reference
• Quick start examples
• Third-party articles

Get Bucket4j library

You can add Bucket4j to your project as maven dependency

The Bucket4j is distributed through Maven Central:

<!-- For java 11+ -->
<dependency>
    <groupId>com.bucket4j</groupId>
    <artifactId>bucket4j-core</artifactId>
    <version>8.3.0</version>
</dependency>

<!-- For java 8 -->
<dependency>
    <groupId>com.bucket4j</groupId>
    <artifactId>bucket4j_jdk8-core</artifactId>
    <version>8.3.0</version>
</dependency>

You can build Bucket4j from sources

git clone https://github.com/bucket4j/bucket4j.git
cd bucket4j
mvn clean install

Have a question?

Feel free to ask via:

• Bucket4j discussions for questions, feature proposals, sharing of experience.
• Bucket4j issue tracker to report a bug.

License

Copyright 2015-2021 Vladimir Bukhtoyarov Licensed under the Apache Software License, Version 2.0: http://www.apache.org/licenses/LICENSE-2.0.

Java compatibility matrix

Since July 2022(release 8.0.0) it was decided to migrate Bucket4j to Java 11. It can be bad news for all who get stuck on Java 8 by different reasons. We understand your pain and will provide special builds with dedicated artifacts for java 8 for intermediate period, but keep in mind then probably access to fresh releases of Bucket4j for Java 8 can be moved to a commercial model in the future.

Bellow the compatibility matrix of Bucket4j's maven artefact with different java versions

JAVA 11 maven artifact	JAVA 8 maven artifact	Comments
com.bucket4j:bucket4j-core	com.bucket4j:bucket4j_jdk8-core
com.bucket4j:bucket4j-jcache	com.bucket4j:bucket4j_jdk8-jcache
com.bucket4j:bucket4j-coherence	com.bucket4j:bucket4j_jdk8-coherence
com.bucket4j:bucket4j-hazelcast	com.bucket4j:bucket4j_jdk8-hazelcast
com.bucket4j:bucket4j-hazelcast	com.bucket4j:bucket4j_jdk8-hazelcast
com.bucket4j:bucket4j-infinispan	com.bucket4j:bucket4j_jdk8-infinispan
Not supported	com.bucket4j:bucket4j_jdk8-infinispan-8	Infinispan-8 is not compatible with Java 11
com.bucket4j:bucket4j-redis	com.bucket4j:bucket4j_jdk8-redis
com.bucket4j:bucket4j-mysql	com.bucket4j:bucket4j_jdk8-mysql
com.bucket4j:bucket4j-postgresql	com.bucket4j:bucket4j_jdk8-postgresql
com.bucket4j:bucket4j-caffeine	com.bucket4j:bucket4j_jdk8-caffeine
com.bucket4j:bucket4j-dynamodb-sdk-v1	com.bucket4j:bucket4j_jdk8-dynamodb-sdk-v1