Seata入門與常見問題

原創 bggl 2020-05-31 16:31

前言：

事務是項目開發過程中經常遇到的問題，分佈式的環境中，分佈式式事務也尤爲重要，之前我是用的RabbitMQ+定時任務來實現最終一致性的分佈式事務模擬，詳細的流程與內容，下一篇博客去講，本次我們使用seata來實現分佈式事務。

本次使用的環境：dubbo+nacos1.2.1+seata1.2.0

Seata簡介

seat官網：https://seata.io/zh-cn/index.html

seata 下載地址：https://seata.io/zh-cn/blog/download.html

Seata是什麼：

     Seata 是一款開源的分佈式事務解決方案，致力於在微服務架構下提供高性能和簡單易用的分佈式事務服務。在 Seata 開源之前，Seata 對應的內部版本在阿里經濟體內部一直扮演着分佈式一致性中間件的角色，幫助經濟體平穩的度過歷年的雙11，對各BU業務進行了有力的支撐。經過多年沉澱與積累，商業化產品先後在阿里雲、金融雲進行售賣。2019.1 爲了打造更加完善的技術生態和普惠技術成果，Seata 正式宣佈對外開源，未來 Seata 將以社區共建的形式幫助其技術更加可靠與完備。

Seata 將爲用戶提供了 AT、TCC、SAGA 和 XA 事務模式，爲用戶打造一站式的分佈式解決方案。

AT、TCC、SAGA 和 XA 事務模式詳細介紹：https://seata.io/zh-cn/docs/overview/what-is-seata.html

Seata服務端部署

本次使用的版本爲Seata1.2.0

因爲我們用nacos 來作爲註冊中心，爲了可以把Seata成功的註冊的到nacos 上，我們下載Seata 時需要下載源碼和集成軟件

步驟1>把seata的配置信息放到Nacos上

   1.通過source下載得到seata-1.2.0.zip，解壓。

   2.進入目錄\seata-1.2.0\script\server\db，根據不同的數據庫進行sql語句執行。

注： xxx.sql 中有很多表的名字容易和項目開發的表的名字衝突，

        個人建議另起一個數據庫（項目名_nacos）

3. 進入目錄\seata-1.2.0\script\config-center，修改config.txt文件。

以MySQL爲例，需要修改內容

  • 01.存儲模式爲數據庫模式store.mode=db，
  • 02.修改數據庫信息     URL，用戶名，密碼：store.db.url= xxx，store.db.user=xxx，store.db.password=xxx
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
service.vgroupMapping.my_test_tx_group=default
service.default.grouplist=127.0.0.1:8091
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
store.mode=file
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
store.db.url=jdbc:mysql://127.0.0.1:3306/seata?useUnicode=true
store.db.user=username
store.db.password=password
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
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
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

4、進入目錄\seata-1.2.0\script\config-center\nacos，發現windows下只能通過python把seata配置文件註冊到Nacos。

下載Python服務：https://www.python.org/downloads/，選擇相應版本下載，下載完成後，雙擊執行python-3.8.2.exe

 詳細的安裝過程見：Python3.8.1版本Windows安裝全過程

安裝完後，配置環境變量，打開Cmd，執行python，如果出來版本號，安裝成功。

5.再次進入目錄\seata-1.2.0\script\config-center\nacos，然後打開Cmd，輸入python nacos-config.py localhost:8848

    如果出現init nacos config finished, please start seata-server.說明初始化Seata配置到Nacos成功。

此時我們登陸Nacos也可以看到有信息了

 步驟2>設置 seata服務的配置文件

1.通過binary下載得到seata-server-1.2.0.zip，解壓。

2.進入conf目錄，修改file.conf文件和registry.conf文件。

    修改file.conf文件，修改mode爲db，修改db的數據庫賬號密碼。


## transaction log store, only used in seata-server
store {
  ## store mode: file、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
  db {
    ## the implement of javax.sql.DataSource, such as DruidDataSource(druid)/BasicDataSource(dbcp) etc.
    datasource = "druid"
    ## mysql/oracle/postgresql/h2/oceanbase etc.
    dbType = "mysql"
    driverClassName = "com.mysql.jdbc.Driver"
    url = "jdbc:mysql://xxxx/xxx_seata?characterEncoding=utf8&connectTimeout=1000&socketTimeout=3000&autoReconnect=true"
    user = "user"
    password = "password"
    minConn = 5
    maxConn = 30
    globalTable = "global_table"
    branchTable = "branch_table"
    lockTable = "lock_table"
    queryLimit = 100
    maxWait = 5000
  }
}

 修改registry.conf文件，type改爲nacos

registry {
  # file 、nacos 、eureka、redis、zk、consul、etcd3、sofa
  type = "nacos"

  nacos {
    serverAddr = "localhost"
    namespace = ""
    cluster = "default"
  }
  eureka {
    serviceUrl = "http://localhost:8761/eureka"
    application = "default"
    weight = "1"
  }
  redis {
    serverAddr = "localhost:6379"
    db = "0"
  }
  zk {
    cluster = "default"
    serverAddr = "127.0.0.1:2181"
    session.timeout = 6000
    connect.timeout = 2000
  }
  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
  type = "nacos"

  nacos {
    serverAddr = "localhost:8848"
    namespace = ""
    group = "SEATA_GROUP"
  }
  consul {
    serverAddr = "127.0.0.1:8500"
  }
  apollo {
    app.id = "seata-server"
    apollo.meta = "http://192.168.1.204:8801"
    namespace = "application"
  }
  zk {
    serverAddr = "127.0.0.1:2181"
    session.timeout = 6000
    connect.timeout = 2000
  }
  etcd3 {
    serverAddr = "http://localhost:2379"
  }
  file {
    name = "file.conf"
  }
}

3.進入bin目錄，雙擊seata-server.bat即可啓動Seata服務。

只有看到這個，然後去nacos 上檢查一下，Seata 服務就啓動成功了

項目集成

<!-- seata-->
<dependency>
    <groupId>io.seata</groupId>
    <artifactId>seata-spring-boot-starter</artifactId>
</dependency>

注： 一定要注意版本一致問題，不然後序項目的服務無法訂閱與發佈

1>進入目錄\seata-1.2.0\script\client\spring，複製application.yml中內容到項目中的application.yml中。

seata:
  enabled: true
  application-id: applicationName
  tx-service-group: my_test_tx_group
  enable-auto-data-source-proxy: true
  use-jdk-proxy: false
  excludes-for-auto-proxying: firstClassNameForExclude,secondClassNameForExclude
  client:
    rm:
      async-commit-buffer-limit: 1000
      report-retry-count: 5
      table-meta-check-enable: false
      report-success-enable: false
      saga-branch-register-enable: false
      lock:
        retry-interval: 10
        retry-times: 30
        retry-policy-branch-rollback-on-conflict: true
    tm:
      commit-retry-count: 5
      rollback-retry-count: 5
    undo:
      data-validation: true
      log-serialization: jackson
      log-table: undo_log
    log:
      exceptionRate: 100
  service:
    vgroupMapping:
      my_test_tx_group: default
    grouplist:
      default: 127.0.0.1:8091
    enable-degrade: false
    disable-global-transaction: false
  transport:
    shutdown:
      wait: 3
    thread-factory:
      boss-thread-prefix: NettyBoss
      worker-thread-prefix: NettyServerNIOWorker
      server-executor-thread-prefix: NettyServerBizHandler
      share-boss-worker: false
      client-selector-thread-prefix: NettyClientSelector
      client-selector-thread-size: 1
      client-worker-thread-prefix: NettyClientWorkerThread
      worker-thread-size: default
      boss-thread-size: 1
    type: TCP
    server: NIO
    heartbeat: true
    serialization: seata
    compressor: none
    enable-client-batch-send-request: true
  config:
    type: nacos
    consul:
      server-addr: 127.0.0.1:8500
    apollo:
      apollo-meta: http://192.168.1.204:8801
      app-id: seata-server
      namespace: application
    etcd3:
      server-addr: http://localhost:2379
    nacos:
      namespace:
      serverAddr: localhost:8848
      group: SEATA_GROUP
      userName: ""
      password: ""
    zk:
      server-addr: 127.0.0.1:2181
      session-timeout: 6000
      connect-timeout: 2000
      username: ""
      password: ""
  registry:
    type: nacos
    consul:
      server-addr: 127.0.0.1:8500
    etcd3:
      serverAddr: http://localhost:2379
    eureka:
      weight: 1
      service-url: http://localhost:8761/eureka
    nacos:
      application: seata-server
      server-addr: localhost:8848
      namespace:
      userName: ""
      password: ""
    redis:
      server-addr: localhost:6379
      db: 0
      password:
      timeout: 0
    sofa:
      server-addr: 127.0.0.1:9603
      region: DEFAULT_ZONE
      datacenter: DefaultDataCenter
      group: SEATA_GROUP
      addressWaitTime: 3000
      application: default
    zk:
      server-addr: 127.0.0.1:2181
      session-timeout: 6000
      connect-timeout: 2000
      username: ""
      password: ""

注：Seata 自1.0版本後 service.vgroup-mapping 就變成了service.vgroupMapping
  

測試

在需要分佈式事務的方法上加@GlobalTransactional(rollbackFor = Exception.class)註解，即可實現該方法的分佈式事務

常見問題

如果出現這種問題，

ERROR 6000 --- [ main] i.s.c.r.netty.NettyClientChannelManager  : no available service 'default' found, please make sure registry config correct

一定要檢查你的seata配置，一般大多數情況下都是因爲配置不匹配導致的

1.你現在使用的seata服務和項目maven中seata的版本一致嗎？

2.你的application.yml中的參數（如下圖）和Nacos中的配置一致嗎？（application.yml下面的圖）

一般常見的問題就是下圖所展現出來的

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