Kafka是一种高吞吐量的分布式发布订阅消息系统,它可以处理消费者规模的网站中的所有动作流数据,具有高性能、持久化、多副本备份、横向扩展等特点。本文介绍了如何使用Go语言发送和接收kafka消息。

sarama

Go语言中连接kafka使用第三方库:github.com/Shopify/sarama

下载及安装

$ go get github.com/Shopify/sarama

注意事项

sarama v1.20之后的版本加入了zstd压缩算法,需要用到cgo,在Windows平台编译时会提示类似如下错误:

# github.com/DataDog/zstd
exec: "gcc":executable file not found in %PATH%

所以在Windows平台请使用v1.19版本的sarama。

连接kafka发送消息

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package main
 
import (
    "fmt"
 
    "github.com/Shopify/sarama"
)
 
// 基于sarama第三方库开发的kafka client
 
func main() {
    config := sarama.NewConfig()
    config.Producer.RequiredAcks = sarama.WaitForAll          // 发送完数据需要leader和follow都确认
    config.Producer.Partitioner = sarama.NewRandomPartitioner // 新选出一个partition 模式为随机分配
    config.Producer.Return.Successes = true                   // 成功交付的消息将在success channel返回
 
    // 构造一个消息
    msg := &sarama.ProducerMessage{}
    msg.Topic = "web_log"
    msg.Value = sarama.StringEncoder("this is a test log") // 调用内置方法将字符串序列化
    // 连接kafka
    client, err := sarama.NewSyncProducer([]string{"192.168.1.7:9092"}, config) // addrs 支持多个地址
    if err != nil {
        fmt.Println("producer closed, err:", err)
        return
    }
    defer client.Close()
    // 发送消息
    pid, offset, err := client.SendMessage(msg)
    if err != nil {
        fmt.Println("send msg failed, err:", err)
        return
    }
    fmt.Printf("pid:%v offset:%v\n", pid, offset)
}

  

连接kafka消费消息

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package main
 
import (
    "fmt"
 
    "github.com/Shopify/sarama"
)
 
// kafka consumer
 
func main() {
    config := sarama.NewConfig()
    config.Consumer.Return.Errors = true
    consumer, err := sarama.NewConsumer([]string{"127.0.0.1:9092"}, config)
    if err != nil {
        fmt.Printf("fail to start consumer, err:%v\n", err)
        return
    }
    partitionList, err := consumer.Partitions("mysql") // 根据topic取到所有的分区
    if err != nil {
        fmt.Printf("fail to get list of partition:err%v\n", err)
        return
    }
    for partition := range partitionList { // 遍历所有的分区
        go func(id int32) {
            // 针对每个分区创建一个对应的分区消费者
            pc, err := consumer.ConsumePartition("mysql", id, sarama.OffsetOldest)
            if err != nil {
                fmt.Printf("failed to start consumer for partition %d,err:%v\n", partition, err)
                return
            }
            defer pc.AsyncClose()
            // 异步从每个分区消费信息
            for {
                select {
                case msg := <-pc.Messages():
                    fmt.Printf("msg offset: %d, partition: %d, timestamp: %s, value: %s\n",
                        msg.Offset, msg.Partition, msg.Timestamp.String(), string(msg.Value))
                case err := <-pc.Errors():
                    fmt.Printf("err :%s\n", err.Error())
                }
            }
        }(int32(partition))
    }
}