Java程序员都知道，Disruptor是一个高性能的线程间通信的框架，即在同一个JVM进程中的多线程间消息传递,由LMAX开发。

Disruptor性能是如此之高，LMAX利用它可以处理每秒6百万订单，用1微秒的延迟获得吞吐量为100K+。那么Go语言生态圈中有没有这样的库呢？

go-disruptor就是对Java Disruptor的移植,它也提供了与Java Disruptor类似的API设计，使用起来也算不上麻烦。

至于性能呢，下面就会介绍，这也是本文的重点。

因为Disruptor的高性能， 好多人对它都有所关注， 有一系列的文章介绍Disruptor，比如下列的文章和资源：

• Disruptor Google Group
• Bad Concurrency (Michael Barker)
• LMAX (Planet)
• LMAX Exchange
• Disruptor presentation @ QCon SF
• Disruptor Technical Paper
• Mechanical Sympathy (Martin Thompson)
• Martin Fowler's Technical Review
• .NET Disruptor Port
• Introduction to the Disruptor
• Disruptor wiki

也有一些中文的翻译和介绍，比如 并发编程网的Disrutpor专题。
阿里巴巴封仲淹：如何优雅地使用Disruptor。

Disruptor由LMAX开发，LMAX目标是要称为世界上最快的交易平台，为了取得低延迟和高吞吐率的目标，它们不得不开发一套高性能的生产者－消费者的消息框架。Java自己的Queue的性能还是有所延迟的，下图就是Disruptor和JDK ArrayBlockingQueue的性能比较。

X轴显示的是延迟时间，Y轴是操作次数。可以看到Disruptor的延迟小，吞吐率高。

Disruptor有多种使用模型和配置，官方的一些模型的测试结果的链接在这里。

我想做的其实就是go-disruptor和官方的Java Disruptor的性能比较。因为Disruptor有多种配置方式，单生产者和多生产者，单消费者和多消费者，配置的不同性能差别还是蛮大的，所以公平地讲，两者的比较应该使用相同的配置，尽管它们是由不同的编程语言开发的。

我选取的一个测试方案是：3个生产者和一个消费者，如果使用一个生产者Java Disruptor的性能会成倍的提升。

Java Disruptor

Java的测试主类如下：

public class Main {
    private static final int NUM_PUBLISHERS = 3;//Runtime.getRuntime().availableProcessors();
    private static final int BUFFER_SIZE = 1024 * 64;
    private static final long ITERATIONS = 1000L * 1000L * 20L;
    private final ExecutorService executor = Executors.newFixedThreadPool(NUM_PUBLISHERS + 1, DaemonThreadFactory.INSTANCE);
    private final CyclicBarrier cyclicBarrier = new CyclicBarrier(NUM_PUBLISHERS + 1);


    private final RingBuffer<ValueEvent> ringBuffer = createMultiProducer(ValueEvent.EVENT_FACTORY, BUFFER_SIZE, new BusySpinWaitStrategy());

    private final SequenceBarrier sequenceBarrier = ringBuffer.newBarrier();
    private final ValueAdditionEventHandler handler = new ValueAdditionEventHandler();
    private final BatchEventProcessor<ValueEvent> batchEventProcessor = new BatchEventProcessor<>(ringBuffer, sequenceBarrier, handler);
    private final ValueBatchPublisher[] valuePublishers = new ValueBatchPublisher[NUM_PUBLISHERS];

    {
        for (int i = 0; i < NUM_PUBLISHERS; i++)
        {
            valuePublishers[i] = new ValueBatchPublisher(cyclicBarrier, ringBuffer, ITERATIONS / NUM_PUBLISHERS, 16);
        }

        ringBuffer.addGatingSequences(batchEventProcessor.getSequence());
    }


    public long runDisruptorPass() throws Exception
    {
        final CountDownLatch latch = new CountDownLatch(1);
        handler.reset(latch, batchEventProcessor.getSequence().get() + ((ITERATIONS / NUM_PUBLISHERS) * NUM_PUBLISHERS));

        Future<?>[] futures = new Future[NUM_PUBLISHERS];
        for (int i = 0; i < NUM_PUBLISHERS; i++)
        {
            futures[i] = executor.submit(valuePublishers[i]);
        }
        executor.submit(batchEventProcessor);


        long start = System.currentTimeMillis();
        cyclicBarrier.await(); //start test

        for (int i = 0; i < NUM_PUBLISHERS; i++)
        {
            futures[i].get();
        } //all published

        latch.await(); //all handled

        long opsPerSecond = (ITERATIONS * 1000L) / (System.currentTimeMillis() - start);
        batchEventProcessor.halt();

        return opsPerSecond;
    }

    public static void main(String[] args) throws Exception
    {
        Main m = new Main();
        System.out.println("opsPerSecond:" + m.runDisruptorPass());
    }
}

生产者和消费者类如下：

public final class ValueAdditionEventHandler implements EventHandler<ValueEvent>
{
    private long value = 0;
    private long count;
    private CountDownLatch latch;

    public long getValue()
    {
        return value;
    }

    public void reset(final CountDownLatch latch, final long expectedCount)
    {
        value = 0;
        this.latch = latch;
        count = expectedCount;
    }

    @Override
    public void onEvent(final ValueEvent event, final long sequence, final boolean endOfBatch) throws Exception
    {
        value = event.getValue();

        if (count == sequence)
        {
            latch.countDown();
        }
    }
}

public final class ValueBatchPublisher implements Runnable
{
    private final CyclicBarrier cyclicBarrier;
    private final RingBuffer<ValueEvent> ringBuffer;
    private final long iterations;
    private final int batchSize;

    public ValueBatchPublisher(
            final CyclicBarrier cyclicBarrier,
            final RingBuffer<ValueEvent> ringBuffer,
            final long iterations,
            final int batchSize)
    {
        this.cyclicBarrier = cyclicBarrier;
        this.ringBuffer = ringBuffer;
        this.iterations = iterations;
        this.batchSize = batchSize;
    }

    @Override
    public void run()
    {
        try
        {
            cyclicBarrier.await();

            for (long i = 0; i < iterations; i += batchSize)
            {
                long hi = ringBuffer.next(batchSize);
                long lo = hi - (batchSize - 1);
                for (long l = lo; l <= hi; l++)
                {
                    ValueEvent event = ringBuffer.get(l);
                    event.setValue(l);
                }
                ringBuffer.publish(lo, hi);
            }
        }
        catch (Exception ex)
        {
            throw new RuntimeException(ex);
        }
    }
}

public final class ValueEvent
{
    private long value;

    public long getValue()
    {
        return value;
    }

    public void setValue(final long value)
    {
        this.value = value;
    }

    public static final EventFactory<ValueEvent> EVENT_FACTORY = new EventFactory<ValueEvent>()
    {
        public ValueEvent newInstance()
        {
            return new ValueEvent();
        }
    };
}

生产者使用三个线程去写数据，一个消费者进行处理。生产者运行在三个线程中，批处理写入，每次写16个数据。

实际测试每秒能达到 183486238 的吞吐率， 也就是1.8亿的吞吐率。

go-disruptor

下面看看go-disruptor的性能能达到多少。

我们知道，Go语言内置的goroutine之间的消息传递是通过channel实现的，go-disruptor官方网站上比较了go-disruptor和channel的性能，明显go-disruptor要比channel要好：

cenario	Per Operation Time
Channels: Buffered, Blocking, GOMAXPROCS=1	58.6 ns
Channels: Buffered, Blocking, GOMAXPROCS=2	86.6 ns
Channels: Buffered, Blocking, GOMAXPROCS=3, Contended Write	194 ns
Channels: Buffered, Non-blocking, GOMAXPROCS=1	26.4 ns
Channels: Buffered, Non-blocking, GOMAXPROCS=2	29.2 ns
Channels: Buffered, Non-blocking, GOMAXPROCS=3, Contended Write	110 ns
Disruptor: Writer, Reserve One	4.3 ns
Disruptor: Writer, Reserve Many	1.0 ns
Disruptor: Writer, Reserve One, Multiple Readers	4.5 ns
Disruptor: Writer, Reserve Many, Multiple Readers	0.9 ns
Disruptor: Writer, Await One	3.0 ns
Disruptor: Writer, Await Many	0.7 ns
Disruptor: SharedWriter, Reserve One	13.6 ns
Disruptor: SharedWriter, Reserve Many	2.5 ns
Disruptor: SharedWriter, Reserve One, Contended Write	56.9 ns
Disruptor: SharedWriter, Reserve Many, Contended Write	3.1 ns

在与Java Disruptor相同的测试条件下go-disruptor的性能呢？

下面是测试代码：

package main

import (
	"fmt"
	"runtime"
	"sync"
	"time"

	disruptor "github.com/smartystreets/go-disruptor"
)

const (
	RingBufferSize   = 1024 * 64
	RingBufferMask   = RingBufferSize - 1
	ReserveOne       = 1
	ReserveMany      = 16
	ReserveManyDelta = ReserveMany - 1
	DisruptorCleanup = time.Millisecond * 10
)

var ringBuffer = [RingBufferSize]int64{}

func main() {
	NumPublishers := 3 //runtime.NumCPU()
	totalIterations := int64(1000 * 1000 * 20)
	iterations := totalIterations / int64(NumPublishers)
	totalIterations = iterations * int64(NumPublishers)

	fmt.Printf("Total: %d,  Iterations: %d, Publisher: %d, Consumer: 1\n", totalIterations, iterations, NumPublishers)

	runtime.GOMAXPROCS(NumPublishers)
	var consumer = &countConsumer{TotalIterations: totalIterations, Count: 0}
	consumer.WG.Add(1)

	controller := disruptor.Configure(RingBufferSize).WithConsumerGroup(consumer).BuildShared()
	controller.Start()
	defer controller.Stop()

	var wg sync.WaitGroup
	wg.Add(NumPublishers + 1)

	var sendWG sync.WaitGroup
	sendWG.Add(NumPublishers)

	for i := 0; i < NumPublishers; i++ {
		go func() {
			writer := controller.Writer()
			wg.Done()
			wg.Wait()
			current := disruptor.InitialSequenceValue
			for current < totalIterations {
				current = writer.Reserve(ReserveMany)

				for j := current - ReserveMany + 1; j <= current; j++ {
					ringBuffer[j&RingBufferMask] = j
				}
				writer.Commit(current-ReserveMany, current)
			}

			sendWG.Done()
		}()
	}

	wg.Done()
	t := time.Now().UnixNano()
	wg.Wait() //waiting for ready as a barrier
	fmt.Println("start to publish")

	sendWG.Wait()
	fmt.Println("Finished to publish")

	consumer.WG.Wait()
	fmt.Println("Finished to consume") //waiting for consumer

	t = (time.Now().UnixNano() - t) / 1000000 //ms

	fmt.Printf("opsPerSecond: %d\n", totalIterations*1000/t)
}

type countConsumer struct {
	Count           int64
	TotalIterations int64
	WG              sync.WaitGroup
}

func (cc *countConsumer) Consume(lower, upper int64) {
	for lower <= upper {
		message := ringBuffer[lower&RingBufferMask]
		if message != lower {
			warning := fmt.Sprintf("\nRace condition--Sequence: %d, Message: %d\n", lower, message)
			fmt.Printf(warning)
			panic(warning)
		}
		lower++
		cc.Count++
		//fmt.Printf("count: %d, message: %d\n", cc.Count-1, message)
		if cc.Count == cc.TotalIterations {
			cc.WG.Done()
			return
		}
	}
}

实际测试go-disruptor的每秒的吞吐率达到137931020。

好了，至少我们在相同的测试case情况下得到了两组数据,另外我还做了相同case情况的go channel的测试，所以一共三组数据：

• Java Disruptor : 183486238 ops/s
• go-disruptor : 137931020 ops/s
• go channel : 6995452 ops/s

可以看到go-disruptor的性能要略微低于Java Disruptor,但是也已经足够高了，达到1.4亿/秒，所以它还是值的我们关注的。go channel的性能远远不如前两者。

Go Channel

如果通过Go Channel实现，每秒的吞吐率为 6995452。

代码如下:

func main() {
	NumPublishers := 3 //runtime.NumCPU()
	totalIterations := int64(1000 * 1000 * 20)
	iterations := totalIterations / int64(NumPublishers)
	totalIterations = iterations * int64(NumPublishers)
	channel := make(chan int64, 1024*64)

	var wg sync.WaitGroup
	wg.Add(NumPublishers + 1)

	var readerWG sync.WaitGroup
	readerWG.Add(1)

	for i := 0; i < NumPublishers; i++ {
		go func() {
			wg.Done()
			wg.Wait()
			for i := int64(0); i < iterations; {
				select {
				case channel <- i:
					i++
				default:
					continue
				}
			}
		}()
	}

	go func() {
		for i := int64(0); i < totalIterations; i++ {
			select {
			case msg := <-channel:
				if NumPublishers == 1 && msg != i {
					//panic("Out of sequence")
				}
			default:
				continue
			}
		}

		readerWG.Done()
	}()

	wg.Done()
	t := time.Now().UnixNano()
	wg.Wait()

	readerWG.Wait()
	t = (time.Now().UnixNano() - t) / 1000000 //ms

	fmt.Printf("opsPerSecond: %d\n", totalIterations*1000/t)
}

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