Seata 是一款开源的分布式事务解决方案致力于提供高性能和简单易用的分布式事务服务。Seata 将为用户提供了 AT、TCC、SAGA 和  XA 事务模式为用户打造一站式的分布式解决方案。AT模式是阿里首推的模式,阿里云上有商用版本的GTSGlobal Transaction  Service 全局事务服务

官网 https://seata.io/zh-cn/index.html

源码:  https://github.com/seata/seata

官方Demo :  https://github.com/seata/seata-samples

 

整体执行流程

• 性能损耗

• 性价比

• 全局锁热点数据

• 回滚锁释放时间

• 死锁问题

 2. Seata快速开始

-- -------------------------------- The script used when storeMode is 'db' --------------------------------
-- the table to store GlobalSession data
CREATE TABLE IF NOT EXISTS `global_table`
(
    `xid`                       VARCHAR(128) NOT NULL,
    `transaction_id`            BIGINT,
    `status`                    TINYINT      NOT NULL,
    `application_id`            VARCHAR(32),
    `transaction_service_group` VARCHAR(32),
    `transaction_name`          VARCHAR(128),
    `timeout`                   INT,
    `begin_time`                BIGINT,
    `application_data`          VARCHAR(2000),
    `gmt_create`                DATETIME,
    `gmt_modified`              DATETIME,
    PRIMARY KEY (`xid`),
    KEY `idx_status_gmt_modified` (`status` , `gmt_modified`),
    KEY `idx_transaction_id` (`transaction_id`)
) ENGINE = InnoDB
  DEFAULT CHARSET = utf8mb4;

-- the table to store BranchSession data
CREATE TABLE IF NOT EXISTS `branch_table`
(
    `branch_id`         BIGINT       NOT NULL,
    `xid`               VARCHAR(128) NOT NULL,
    `transaction_id`    BIGINT,
    `resource_group_id` VARCHAR(32),
    `resource_id`       VARCHAR(256),
    `branch_type`       VARCHAR(8),
    `status`            TINYINT,
    `client_id`         VARCHAR(64),
    `application_data`  VARCHAR(2000),
    `gmt_create`        DATETIME(6),
    `gmt_modified`      DATETIME(6),
    PRIMARY KEY (`branch_id`),
    KEY `idx_xid` (`xid`)
) ENGINE = InnoDB
  DEFAULT CHARSET = utf8mb4;

-- the table to store lock data
CREATE TABLE IF NOT EXISTS `lock_table`
(
    `row_key`        VARCHAR(128) NOT NULL,
    `xid`            VARCHAR(128),
    `transaction_id` BIGINT,
    `branch_id`      BIGINT       NOT NULL,
    `resource_id`    VARCHAR(256),
    `table_name`     VARCHAR(32),
    `pk`             VARCHAR(36),
    `status`         TINYINT      NOT NULL DEFAULT '0' COMMENT '0:locked ,1:rollbacking',
    `gmt_create`     DATETIME,
    `gmt_modified`   DATETIME,
    PRIMARY KEY (`row_key`),
    KEY `idx_status` (`status`),
    KEY `idx_branch_id` (`branch_id`),
    KEY `idx_xid` (`xid`)
) ENGINE = InnoDB
  DEFAULT CHARSET = utf8mb4;

CREATE TABLE IF NOT EXISTS `distributed_lock`
(
    `lock_key`       CHAR(20) NOT NULL,
    `lock_value`     VARCHAR(20) NOT NULL,
    `expire`         BIGINT,
    primary key (`lock_key`)
) ENGINE = InnoDB
  DEFAULT CHARSET = utf8mb4;

INSERT INTO `distributed_lock` (lock_key, lock_value, expire) VALUES ('AsyncCommitting', ' ', 0);
INSERT INTO `distributed_lock` (lock_key, lock_value, expire) VALUES ('RetryCommitting', ' ', 0);
INSERT INTO `distributed_lock` (lock_key, lock_value, expire) VALUES ('RetryRollbacking', ' ', 0);
INSERT INTO `distributed_lock` (lock_key, lock_value, expire) VALUES ('TxTimeoutCheck', ' ', 0);

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

  nacos {
    application = "seata-server"
    serverAddr = "127.0.0.1:8848"
    group = "SEATA_GROUP"
    namespace = ""
    cluster = "default"
    username = "nacos"
    password = "nacos"
  }
}

config {
  # file、nacos 、apollo、zk、consul、etcd3
  type = "nacos"

  nacos {
    serverAddr = "127.0.0.1:8848"
    namespace = ""
    group = "SEATA_GROUP"
    username = "nacos"
    password = "nacos"
  }
}

获取/seata/script/config-center/config.txt修改配置信息

精简配置:

service.vgroupMapping.my_test_tx_group=default
service.default.grouplist=127.0.0.1:8091
service.enableDegrade=false
service.disableGlobalTransaction=false
store.mode=db
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=root
store.db.password=root
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

配置事务分组 要与客户端配置的事务分组一致my_test_tx_group需要与客户端保持一致  default需要跟客户端和registry.conf中registry中的cluster保持一致 客户端properties配置spring.cloud.alibaba.seata.tx‐service‐group=my_test_tx_group

事务分组异地机房停电容错机制

my_test_tx_group 可以自定义  比如guangzhou、shanghai...  对应的client也要去设置

seata . service . vgroup ‐ mapping . projectA = guangzhou default   必须要等于 registry.confi  cluster = "default"

sh ${SEATAPATH}/script/config‐center/nacos/nacos‐config.sh ‐h localhost ‐p 8848 ‐g SEATA_GROUP ‐t 5a3c7d6c‐f497‐
4d68‐a71a‐2e5e3340b3ca

参数说明

-h: host默认值 localhost

-p: port默认值 8848

-g: 配置分组默认值为 'SEATA_GROUP'

-t: 租户信息对应 Nacos 的命名空间ID字段, 默认值为空 ''

步骤六启动Seata Server

源码启动: 执行server模块下io.seata.server.Server.java的main方法

命令启动: bin/ seata-server.sh  -h 127.0.0.1 -p 8091 -m db -n 1 -e test

bin/seata‐server.sh ‐p 8091 ‐n 1

声明式事务实现@GlobalTransactional

接入微服务应用

业务场景

用户下单整个业务逻辑由三个微服务构成

订单服务根据采购需求创建订单。         

库存服务对给定的商品扣除库存数量。 

1启动Seata server端Seata server使用nacos作为配置中心和注册中心上一步已完成

2配置微服务整合seata

如果出现问题

一般大多数情况下都是因为配置不匹配导致的

1.检查现在使用的seata服务和项目maven中seata的版本是否一致

2.检查tx-service-groupnacos.clusternacos.group参数是否和Seata Server中的配置一致

# 数据源
spring:
  datasource:
    username: root
    password: root
    url: jdbc:mysql://localhost:3306/seata_order?characterEncoding=utf8&useSSL=false&serverTimezone=UTC&
    driver-class-name: com.mysql.cj.jdbc.Driver
    type: com.alibaba.druid.pool.DruidDataSource

    #初始化时运行sql脚本
    schema: classpath:sql/schema.sql
    initialization-mode: never
  application:
    name: alibaba-order-seata
  cloud:
    nacos:
      discovery:
        server-addr: 127.0.0.1:8848
        username: nacos
        password: nacos
    alibaba:
      seata:
        tx-service-group: my_test_tx_group
#设置mybatis
mybatis:
  mapper-locations: classpath:com/tulingxueyuan/order/mapper/*Mapper.xml
  #config-location: classpath:mybatis-config.xml
  typeAliasesPackage: com.tulingxueyuan.order.pojo
  configuration:
    mapUnderscoreToCamelCase: true
server:
  port: 8070
seata:
  registry:
    # 配置seata的注册中心 告诉seata client 怎么去访问seata server(TC)
    type: nacos
    nacos:
      server-addr: 127.0.0.1:8848 #seata-server所在的naocs服务地址
      application: seata-server  #seata-server服务名默认seata-server
      password: nacos
      username: nacos
      group: SEATA_GROUP #默认SEATA_GROUP
  config:
    type: nacos
    nacos:
      server-addr: 127.0.0.1:8848 #seata-server
      username: nacos
      password: nacos
      group: SEATA_GROUP

第四步微服务发起者TM 方需要添加@GlobalTransactional注解

测试

分布式事务成功模拟正常下单、扣库存扣余额

分布式事务失败模拟下单扣库存成功、扣余额失败事务是否回滚