Java多线程之Disruptor入门

Disruptor目前是世界上最快的单机消息队列，由英国外汇交易公司LMAX开发，研发的初衷是解决内存队列的延迟问题（在性能测试中发现竟然与I/O操作处于同样的数量级）。基于Disruptor开发的系统单线程能支撑每秒600万订单，2010年在QCon演讲后，获得了业界关注。2011年，企业应用软件专家Martin Fowler专门撰写长文介绍。同年它还获得了Oracle官方的Duke大奖。目前，包括Apache Storm、Camel、Log4j 2在内的很多知名项目都应用了Disruptor以获取高性能。

Disruptor维护了一个环形队列RingBuffer，这个队列本质上是一个首位相连的数组。相比于LinkedBlockdingQueue，RingBuffer的数组结构在查找方面效率更高。此外，LinkedBlockingQueue需要维护一个头节点指针head和一个尾节点指针tail，而RingBuffer只需要维护一个sequence指向下一个可用的位置即可。所以从这两点来说，RingBuffer比LinkedBlockingQueue要快。

<dependency> <groupId>com.lmax</groupId> <artifactId>disruptor</artifactId> <version>3.4.3</version></dependency>3.2 事件Event

Disruptor是基于事件的生产者消费者模型。其RingBuffer中存放的其实是将消息封装成的事件。这里定义了一个LongEvent，表示消息队列中存放的是long类型的数据。

public class LongEvent {private long value;public void set(long value) {this.value = value;} @Override public String toString() {return 'LongEvent{' +'value=' + value +’}’; }}3.3 EventFactory

实现EventFactory接口，定义Event工厂，用于填充队列。Event工厂其实是为了提高Disruptor的效率，初始化的时候，会调用Event工厂，对RingBuffer进行内存的提前分配，GC的频率会降低。

import com.lmax.disruptor.EventFactory;public class LongEventFactory implements EventFactory<LongEvent> {public LongEvent newInstance() {return new LongEvent();}}3.4 EventHandler

实现EventHandler接口，定义EventHandler(消费者)，处理容器中的元素。

import com.lmax.disruptor.EventHandler;public class LongEventHandler implements EventHandler<LongEvent> {public void onEvent(LongEvent event, long sequence, boolean endOfBatch) {System.out.println('Event: ' + event + ', sequence: ' + sequence);}}3.5 使用Disruptor原始API发布消息

import cn.flying.space.disruptor.demo.LongEvent;import com.lmax.disruptor.RingBuffer;import java.nio.ByteBuffer;/** * 定义一个生产者，往Disruptor中投递消息 */public class LongEventProducer { private RingBuffer<LongEvent> ringBuffer; public LongEventProducer(RingBuffer<LongEvent> ringBuffer) {this.ringBuffer = ringBuffer; } public void onData(ByteBuffer byteBuffer) {// 定位到下一个可存放的位置long sequence = ringBuffer.next();try { // 拿到该位置的event LongEvent event = ringBuffer.get(sequence); // 设置event的值 event.set(byteBuffer.getLong(0));} finally { // 发布 ringBuffer.publish(sequence);} }}import cn.flying.space.disruptor.demo.LongEvent;import cn.flying.space.disruptor.demo.LongEventFactory;import cn.flying.space.disruptor.demo.LongEventHandler;import com.lmax.disruptor.RingBuffer;import com.lmax.disruptor.dsl.Disruptor;import java.nio.ByteBuffer;import java.util.concurrent.Executors;public class TestMain { public static void main(String[] args) throws InterruptedException {// 定义event工厂LongEventFactory factory = new LongEventFactory();// ringBuffer长度int bufferSize = 1024;// 构造一个DisruptorDisruptor<LongEvent> disruptor = new Disruptor<>(factory, bufferSize, Executors.defaultThreadFactory());// 绑定handlerdisruptor.handleEventsWith(new LongEventHandler());// 启动Disruptordisruptor.start();RingBuffer<LongEvent> ringBuffer = disruptor.getRingBuffer();LongEventProducer producer = new LongEventProducer(ringBuffer);ByteBuffer byteBuffer = ByteBuffer.allocate(8);for (long i = 0; true; i++) { byteBuffer.clear(); byteBuffer.putLong(i); // 投递消息 producer.onData(byteBuffer); Thread.sleep(1000);} }}3.6 使用Translators发布消息

import cn.flying.space.disruptor.demo.LongEvent;import com.lmax.disruptor.EventTranslatorOneArg;import com.lmax.disruptor.RingBuffer;import java.nio.ByteBuffer;public class LongEventProducerUsingTranslator { private RingBuffer<LongEvent> ringBuffer; public LongEventProducerUsingTranslator(RingBuffer<LongEvent> ringBuffer) {this.ringBuffer = ringBuffer; } private static final EventTranslatorOneArg<LongEvent, ByteBuffer> TRANSLATOR = new EventTranslatorOneArg<LongEvent, ByteBuffer>() {@Overridepublic void translateTo(LongEvent longEvent, long l, ByteBuffer byteBuffer) { longEvent.set(byteBuffer.getLong(0));} }; public void onData(ByteBuffer byteBuffer) {ringBuffer.publishEvent(TRANSLATOR, byteBuffer); }}import cn.flying.space.disruptor.demo.LongEvent;import cn.flying.space.disruptor.demo.LongEventFactory;import cn.flying.space.disruptor.demo.LongEventHandler;import com.lmax.disruptor.RingBuffer;import com.lmax.disruptor.dsl.Disruptor;import com.lmax.disruptor.util.DaemonThreadFactory;import java.nio.ByteBuffer;/** * @author ZhangSheng * @date 2021-4-26 14:23 */public class TestMain { public static void main(String[] args) throws InterruptedException {LongEventFactory factory = new LongEventFactory();int bufferSize = 1024;Disruptor<LongEvent> disruptor = new Disruptor<>(factory, bufferSize, DaemonThreadFactory.INSTANCE);disruptor.handleEventsWith(new LongEventHandler());disruptor.start();RingBuffer<LongEvent> ringBuffer = disruptor.getRingBuffer();LongEventProducerUsingTranslator producer = new LongEventProducerUsingTranslator(ringBuffer);ByteBuffer byteBuffer = ByteBuffer.allocate(8);for (long i = 0L; true; i++) { byteBuffer.putLong(0, i); // 发布 producer.onData(byteBuffer); Thread.sleep(1000);} }}

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