Seata处理分布式事务

时间：2021-5-25 作者：qvyue

1.分布式事务问题

Seata处理分布式事务
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Seata处理分布式事务
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一次业务操作需要跨多个数据源或需要跨多个系统进行远程调用，就会产生分布式事务问题.

2.Seata简介

Seata是一款开源的分布式事务解决方案，致力于在微服务架构下提供高性能和简单易用的分布式事务服务
官网地址：http://seata.io/zh-cn/

分布式事务处理过程的-ID+三组件模型
Transaction ID XID，全局唯一的事务ID
3组件概念：
Transaction Coordinator(TC)
事务协调器，维护全局事务的运行状态，负责协调并驱动全局事务的提交或回滚;
Transaction Manager(TM)
控制全局事务的边界，负责开启一个全局事务，并最终发起全局提交或全局回滚的决议;
Resource Manager(RM)
控制分支事务，负责分支注册，状态汇报，并接收事务协调器的指令，驱动分支（本地）事务的提交和回滚；

处理过程：

Seata处理分布式事务
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Seata处理分布式事务
image.png

Spring 本地@Transactional
全局@GlobalTransactional

Seata处理分布式事务
image.png

3.Seata-Server安装

下载版本：http://seata.io/zh-cn/ (1.3.0v) 解压到指定目录
下载源码：拷贝server和client，.sql文件到conf目录，创建seate数据库和表（server）
https://github.com/seata/seata/blob/1.3.0/script/server/db/mysql.sql

3.1SERVER 配置

3.1.1修改conf目录下registry.conf（先备份原始registry.conf文件）

registry {
  # file 、nacos 、eureka、redis、zk、consul、etcd3、sofa
#配置nacos作为seata-server注册中心
  type = "nacos"

  nacos {
    application = "seata-server"
    serverAddr = "192.168.1.111:1111"
    group = "DEV_GROUP"
    namespace = "300c5dc3-6326-4033-8d7e-effe12645735"
    cluster = "default"
    username = "nacos"
    password = "nacos"
  }
  eureka {
    serviceUrl = "http://localhost:8761/eureka"
    application = "default"
    weight = "1"
  }
  redis {
    serverAddr = "localhost:6379"
    db = 0
    password = ""
    cluster = "default"
    timeout = 0
  }
  zk {
    cluster = "default"
    serverAddr = "127.0.0.1:2181"
    sessionTimeout = 6000
    connectTimeout = 2000
    username = ""
    password = ""
  }
  consul {
    cluster = "default"
    serverAddr = "127.0.0.1:8500"
  }
  etcd3 {
    cluster = "default"
    serverAddr = "http://localhost:2379"
  }
  sofa {
    serverAddr = "127.0.0.1:9603"
    application = "default"
    region = "DEFAULT_ZONE"
    datacenter = "DefaultDataCenter"
    cluster = "default"
    group = "SEATA_GROUP"
    addressWaitTime = "3000"
  }
  file {
    name = "file.conf"
  }
}

config {
  # file、nacos 、apollo、zk、consul、etcd3
  #配置nacos为配置中心，如果配置file ，启用file.conf文件
  type = "nacos"

  nacos {
    serverAddr = "192.168.1.111:1111"
    namespace = "300c5dc3-6326-4033-8d7e-effe12645735"
    group = "DEV_GROUP"
    username = "nacos"
    password = "nacos"
  }
  consul {
    serverAddr = "127.0.0.1:8500"
  }
  apollo {
    appId = "seata-server"
    apolloMeta = "http://192.168.1.204:8801"
    namespace = "application"
  }
  zk {
    serverAddr = "127.0.0.1:2181"
    sessionTimeout = 6000
    connectTimeout = 2000
    username = ""
    password = ""
  }
  etcd3 {
    serverAddr = "http://localhost:2379"
  }
  file {
    name = "file.conf"
  }
}

3.1.2registry.conf中配置中心配置file，需要修改conf目录下的file.conf配置文件（先备份原始file.conf文件）

主要修改：自定义事务组名称
## transaction log store, only used in seata-server
store {
  ## store mode: file、db、redis
 #事务日志存储模式为db
  mode = "db"

  ## file store property
  file {
    ## store location dir
    dir = "sessionStore"
    # branch session size , if exceeded first try compress lockkey, still exceeded throws exceptions
    maxBranchSessionSize = 16384
    # globe session size , if exceeded throws exceptions
    maxGlobalSessionSize = 512
    # file buffer size , if exceeded allocate new buffer
    fileWriteBufferCacheSize = 16384
    # when recover batch read size
    sessionReloadReadSize = 100
    # async, sync
    flushDiskMode = async
  }

  ## database store property 
 #数据库连接信息
  db {
    ## the implement of javax.sql.DataSource, such as DruidDataSource(druid)/BasicDataSource(dbcp)/HikariDataSource(hikari) etc.
    datasource = "druid"
    ## mysql/oracle/postgresql/h2/oceanbase etc.
    dbType = "mysql"
    driverClassName = "com.mysql.jdbc.Driver"
    url = "jdbc:mysql://192.168.1.115:3306/seata"
    user = "root"
    password = "123456"
    minConn = 5
    maxConn = 30
    globalTable = "global_table"
    branchTable = "branch_table"
    lockTable = "lock_table"
    queryLimit = 100
    maxWait = 5000
  }

  ## redis store property
  redis {
    host = "127.0.0.1"
    port = "6379"
    password = ""
    database = "0"
    minConn = 1
    maxConn = 10
    queryLimit = 100
  }
}

3.1.3registry.conf中配置中心配置nacos
上传配置至Nacos配置中心
参考https://github.com/seata/seata/tree/develop/script/config-center 的config.txt, 拷贝config.txt和nacos-config.sh到seata-server,
修改config.txt

transport.type=TCP
transport.server=NIO
transport.heartbeat=true
transport.enableClientBatchSendRequest=false
transport.threadFactory.bossThreadPrefix=NettyBoss
transport.threadFactory.workerThreadPrefix=NettyServerNIOWorker
transport.threadFactory.serverExecutorThreadPrefix=NettyServerBizHandler
transport.threadFactory.shareBossWorker=false
transport.threadFactory.clientSelectorThreadPrefix=NettyClientSelector
transport.threadFactory.clientSelectorThreadSize=1
transport.threadFactory.clientWorkerThreadPrefix=NettyClientWorkerThread
transport.threadFactory.bossThreadSize=1
transport.threadFactory.workerThreadSize=default
transport.shutdown.wait=3
#修改fsp-tx-group事务组名称为default，
#fsp-tx-group和微服务配置一致spring.cloud.alibaba.seata.tx-service-group=fsp-tx-group
#注意高版本vgroupMapping
service.vgroupMapping.fsp-tx-group=default
service.default.grouplist=192.168.1.114:8091
service.enableDegrade=false
service.disableGlobalTransaction=false
client.rm.asyncCommitBufferLimit=10000
client.rm.lock.retryInterval=10
client.rm.lock.retryTimes=30
client.rm.lock.retryPolicyBranchRollbackOnConflict=true
client.rm.reportRetryCount=5
client.rm.tableMetaCheckEnable=false
client.rm.sqlParserType=druid
client.rm.reportSuccessEnable=false
client.rm.sagaBranchRegisterEnable=false
client.tm.commitRetryCount=5
client.tm.rollbackRetryCount=5
client.tm.degradeCheck=false
client.tm.degradeCheckAllowTimes=10
client.tm.degradeCheckPeriod=2000
#配置事务日志模式db
store.mode=db
store.file.dir=file_store/data
store.file.maxBranchSessionSize=16384
store.file.maxGlobalSessionSize=512
store.file.fileWriteBufferCacheSize=16384
store.file.flushDiskMode=async
store.file.sessionReloadReadSize=100
store.db.datasource=druid
store.db.dbType=mysql
store.db.driverClassName=com.mysql.jdbc.Driver
#配置数据源
store.db.url=jdbc:mysql://192.168.1.115:3306/seata?useUnicode=true
store.db.user=root
store.db.password=123456
store.db.minConn=5
store.db.maxConn=30
store.db.globalTable=global_table
store.db.branchTable=branch_table
store.db.queryLimit=100
store.db.lockTable=lock_table
store.db.maxWait=5000
store.redis.host=127.0.0.1
store.redis.port=6379
store.redis.maxConn=10
store.redis.minConn=1
store.redis.database=0
store.redis.password=null
store.redis.queryLimit=100
server.recovery.committingRetryPeriod=1000
server.recovery.asynCommittingRetryPeriod=1000
server.recovery.rollbackingRetryPeriod=1000
server.recovery.timeoutRetryPeriod=1000
server.maxCommitRetryTimeout=-1
server.maxRollbackRetryTimeout=-1
server.rollbackRetryTimeoutUnlockEnable=false
client.undo.dataValidation=true
client.undo.logSerialization=jackson
client.undo.onlyCareUpdateColumns=true
server.undo.logSaveDays=7
server.undo.logDeletePeriod=86400000
client.undo.logTable=undo_log
client.log.exceptionRate=100
transport.serialization=seata
transport.compressor=none
metrics.enabled=false
metrics.registryType=compact
metrics.exporterList=prometheus
metrics.exporterPrometheusPort=9898

3.1.4配置信息提交到nacos
运行仓库中提供的nacos脚本./nacos-config.sh,将信息提交到nacos控制台,如果有需要更改,可直接通过控制台更改.

Seata处理分布式事务
image.png

3.1.5随后,启动 Seata-Server

Seata处理分布式事务
image.png

您同样也能发现Server 和Client部分配置都已经从配置中心中读取,例如:store.mode.

3.2client service配置

3.2.1业务数据库准备
业务库表略..
对于AT模式，必须为业务数据库分别建对应的回滚日志表，初始化此sql。seata服务器不需要它。
https://github.com/seata/seata/blob/1.3.0/script/client/at/db/mysql.sql

3.2.2业务微服务准备
POM配置

    com.alibaba.cloudspring-cloud-starter-alibaba-nacos-discoverycom.alibaba.cloudspring-cloud-starter-alibaba-seataseata-allio.seataio.seataseata-all1.3.0org.springframework.cloudspring-cloud-starter-openfeignorg.springframework.bootspring-boot-starter-weborg.springframework.bootspring-boot-starter-actuatormysqlmysql-connector-java5.1.37com.alibabadruid-spring-boot-starter1.1.10org.mybatis.spring.bootmybatis-spring-boot-starter2.0.0org.springframework.bootspring-boot-starter-testtestorg.projectlomboklomboktrue

YML配置

application.yml配置指定命名空间名称
spring:
  profiles:
    active: dev

bootstrap.yml 配置服务名和nacos,seata事务组
server:
  port: 2001

spring:
  application:
    name: seata-order-service
  cloud:
    alibaba:
      seata:
        #自定义事务组名称需要与seata-server中的对应
        tx-service-group: fsp-tx-group
#配置nacos服务注册中心和配置中心
    nacos:
      discovery:
        server-addr: 192.168.1.111:1111
        group: DEV_GROUP
        namespace: 300c5dc3-6326-4033-8d7e-effe12645735
      config:
        server-addr: 192.168.1.111:1111 #配置中心地址(nginx)
        file-extension: yaml #指定yaml格式的配置
        group: DEV_GROUP
        namespace: 300c5dc3-6326-4033-8d7e-effe12645735
#业务配置可在nacos配置，供服务读取
#  datasource:
#    driver-class-name: com.mysql.jdbc.Driver
#    url: jdbc:mysql://192.168.1.115:3306/seata_order
#    username: root
#    password: 123456
#
#feign:
#  hystrix:
#    enabled: false
#
#logging:
#  level:
#    io:
#      seata: info
#
#mybatis:
#  mapperLocations: classpath:mapper/*.xml

file.conf

transport {
  # tcp udt unix-domain-socket
  type = "TCP"
  #NIO NATIVE
  server = "NIO"
  #enable heartbeat
  heartbeat = true
  # the client batch send request enable
  enableClientBatchSendRequest = true
  #thread factory for netty
  threadFactory {
    bossThreadPrefix = "NettyBoss"
    workerThreadPrefix = "NettyServerNIOWorker"
    serverExecutorThread-prefix = "NettyServerBizHandler"
    shareBossWorker = false
    clientSelectorThreadPrefix = "NettyClientSelector"
    clientSelectorThreadSize = 1
    clientWorkerThreadPrefix = "NettyClientWorkerThread"
    # netty boss thread size,will not be used for UDT
    bossThreadSize = 1
    #auto default pin or 8
    workerThreadSize = "default"
  }
  shutdown {
    # when destroy server, wait seconds
    wait = 3
  }
  serialization = "seata"
  compressor = "none"
}
service {
  #transaction service group mapping
  vgroupMapping.fsp-tx-group = "default"
  #only support when registry.type=file, please don't set multiple addresses
  default.grouplist = "127.0.0.1:8091"
  #degrade, current not support
  enableDegrade = false
  #disable seata
  disableGlobalTransaction = false
}

client {
  rm {
    asyncCommitBufferLimit = 10000
    lock {
      retryInterval = 10
      retryTimes = 30
      retryPolicyBranchRollbackOnConflict = true
    }
    reportRetryCount = 5
    tableMetaCheckEnable = false
    reportSuccessEnable = false
    sagaBranchRegisterEnable = false
  }
  tm {
    commitRetryCount = 5
    rollbackRetryCount = 5
    degradeCheck = false
    degradeCheckPeriod = 2000
    degradeCheckAllowTimes = 10
  }
  undo {
    dataValidation = true
    onlyCareUpdateColumns = true
    logSerialization = "jackson"
    logTable = "undo_log"
  }
  log {
    exceptionRate = 100
  }
}

registry.conf

#注册中心服务发现配置nacos
registry {
  # file 、nacos 、eureka、redis、zk、consul、etcd3、sofa
  type = "nacos"

  nacos {
    application = "seata-server"
    serverAddr = "192.168.1.111:1111"
    group = "DEV_GROUP"
    namespace = "300c5dc3-6326-4033-8d7e-effe12645735"
    username = "nacos"
    password = "nacos"
  }
  eureka {
    serviceUrl = "http://localhost:8761/eureka"
    weight = "1"
  }
  redis {
    serverAddr = "localhost:6379"
    db = "0"
    password = ""
    timeout = "0"
  }
  zk {
    serverAddr = "127.0.0.1:2181"
    sessionTimeout = 6000
    connectTimeout = 2000
    username = ""
    password = ""
  }
  consul {
    serverAddr = "127.0.0.1:8500"
  }
  etcd3 {
    serverAddr = "http://localhost:2379"
  }
  sofa {
    serverAddr = "127.0.0.1:9603"
    region = "DEFAULT_ZONE"
    datacenter = "DefaultDataCenter"
    group = "SEATA_GROUP"
    addressWaitTime = "3000"
  }
  file {
    name = "file.conf"
  }
}
#配置中心使用file ，启用file.conf; 如果使用nacos 需配置相关配置
config {
  # file、nacos 、apollo、zk、consul、etcd3、springCloudConfig
  type = "file"

  nacos {
    serverAddr = "192.168.1.111:1111"
    namespace = "300c5dc3-6326-4033-8d7e-effe12645735"
    group = "DEV_GROUP"
    username = "nacos"
    password = "nacos"
  }
  consul {
    serverAddr = "127.0.0.1:8500"
  }
  apollo {
    appId = "seata-server"
    apolloMeta = "http://192.168.1.204:8801"
    namespace = "application"
  }
  zk {
    serverAddr = "127.0.0.1:2181"
    sessionTimeout = 6000
    connectTimeout = 2000
    username = ""
    password = ""
  }
  etcd3 {
    serverAddr = "http://localhost:2379"
  }
  file {
    name = "file.conf"
  }
}

3.2.3业务代码
略…

4.分布式事务的执行流程

Seata处理分布式事务
image.png

TM开启分布式事务(TM向TC注册全局事务记录)
换业务场景，编排数据库，服务等事务内资源（RM向TC汇报资源准备状态）
TM结束分布式事务，事务一阶段结束（TM通知TC提交/回滚分布式事务）
TC汇总事务信息，决定分布式事务是提交还是回滚
TC通知所有RM提交/回滚资源，事务二阶段结束。

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