Go连接Kafka

Go连接Kafka的例子好少，而支持offset追踪者更少，但也是基础的要求。”github.com/bsm/sarama-cluster”结合“github.com/Shopify/sarama”满足了此要求。 

并发量小时，可以用同步生产者，但是并发量大时，必须使用异步生产者。 

环境： 

golang 1.8 

kafka 0.10 

centos 7.2

package main

import (
    "fmt"
    "math/rand"
    "os"
    "strconv"
    "strings"
    "time"

    "github.com/Shopify/sarama"
    "github.com/bsm/sarama-cluster" //support automatic consumer-group rebalancing and offset tracking
    "github.com/sdbaiguanghe/glog"
)

var (
    topics = "topics_1"
)

// consumer 消费者
func consumer() {
    groupID := "group-1"
    config := cluster.NewConfig()
    config.Group.Return.Notifications = true
    config.Consumer.Offsets.CommitInterval = 1 * time.Second
    config.Consumer.Offsets.Initial = sarama.OffsetNewest //初始从最新的offset开始

    c, err := cluster.NewConsumer(strings.Split("localhost:9092", ","), groupID, strings.Split(topics, ","), config)
    if err != nil {
        glog.Errorf("Failed open consumer: %v", err)
        return
    }
    defer c.Close()
    go func(c *cluster.Consumer) {
        errors := c.Errors()
        noti := c.Notifications()
        for {
            select {
            case err := <-errors:
                glog.Errorln(err)
            case <-noti:
            }
        }
    }(c)

    for msg := range c.Messages() {
        fmt.Fprintf(os.Stdout, "%s/%d/%d	%s
", msg.Topic, msg.Partition, msg.Offset, msg.Value)
        c.MarkOffset(msg, "") //MarkOffset 并不是实时写入kafka，有可能在程序crash时丢掉未提交的offset
    }
}

// syncProducer 同步生产者
// 并发量小时，可以用这种方式
func syncProducer() {
    config := sarama.NewConfig()
    //  config.Producer.RequiredAcks = sarama.WaitForAll
    //  config.Producer.Partitioner = sarama.NewRandomPartitioner
    config.Producer.Return.Successes = true
    config.Producer.Timeout = 5 * time.Second
    p, err := sarama.NewSyncProducer(strings.Split("localhost:9092", ","), config)
    defer p.Close()
    if err != nil {
        glog.Errorln(err)
        return
    }

    v := "sync: " + strconv.Itoa(rand.New(rand.NewSource(time.Now().UnixNano())).Intn(10000))
    fmt.Fprintln(os.Stdout, v)
    msg := &sarama.ProducerMessage{
        Topic: topics,
        Value: sarama.ByteEncoder(v),
    }
    if _, _, err := p.SendMessage(msg); err != nil {
        glog.Errorln(err)
        return
    }
}

// asyncProducer 异步生产者
// 并发量大时，必须采用这种方式
func asyncProducer() {
    config := sarama.NewConfig()
    config.Producer.Return.Successes = true //必须有这个选项
    config.Producer.Timeout = 5 * time.Second
    p, err := sarama.NewAsyncProducer(strings.Split("localhost:9092", ","), config)
    defer p.Close()
    if err != nil {
        return
    }

    //必须有这个匿名函数内容
    go func(p sarama.AsyncProducer) {
        errors := p.Errors()
        success := p.Successes()
        for {
            select {
            case err := <-errors:
                if err != nil {
                    glog.Errorln(err)
                }
            case <-success:
            }
        }
    }(p)

    v := "async: " + strconv.Itoa(rand.New(rand.NewSource(time.Now().UnixNano())).Intn(10000))
    fmt.Fprintln(os.Stdout, v)
    msg := &sarama.ProducerMessage{
        Topic: topics,
        Value: sarama.ByteEncoder(v),
    }
    p.Input() <- msg
}

参考： 

http://pastebin.com/9ZsnP2eU 

https://github.com/Shopify/sarama 

https://github.com/bsm/sarama-cluster