Seata之分布式事务问题及解决方案

目录

• Seata–分布式事务解决方案
• 简介
• 同类产品对比
• 环境搭建
• 1.微服务
• 2.SQL
• 3.seata-server
• 4.微服务配置
• 事务模式
• 1.AT模式（推荐:自动补偿）
• 2.XA模式（强一致）
• 3.TCC模式（手动补偿）
• 4.Saga模式（长事务）
• 总结

Seata–分布式事务解决方案

简介

Seata 是阿里开源的分布式事务解决方案，提供 AT、XA、TCC、Saga 四种事务模式，支持微服务架构下的数据一致性。

官网：https://seata.apache.org/zh-cn/

同类产品对比

环境搭建

1.微服务

创建 Spring Cloud 项目，推荐使用以下组件：

<!-- Spring Cloud Alibaba 依赖 -->
<dependency>
    <groupId>com.alibaba.cloud</groupId>
    <artifactId>spring-cloud-starter-alibaba-seata</artifactId>
</dependency>

2.SQL

每个微服务数据库需创建 undo_log 表（AT模式必需）：

-- 每个业务数据库均需执行
CREATE TABLE IF NOT EXISTS `undo_log`
(
    `id`            BIGINT(20)   NOT NULL AUTO_INCREMENT,
    `branch_id`     BIGINT(20)   NOT NULL,
    `xid`           VARCHAR(100) NOT NULL,
    `context`       VARCHAR(128) NOT NULL,
    `rollback_info` LONGBLOB     NOT NULL,
    `log_status`    INT(11)      NOT NULL,
    `log_created`   DATETIME     NOT NULL,
    `log_modified`  DATETIME     NOT NULL,
    PRIMARY KEY (`id`),
    UNIQUE KEY `ux_undo_log` (`xid`, `branch_id`)
) ENGINE = InnoDB
  AUTO_INCREMENT = 1
  DEFAULT CHARSET = utf8;

3.seata-server

• 1.下载 :https://seata.apache.org/zh-cn/download/seata-server
• 2.解压并启动：seata-server.BAT
• 3.控制台:http://127.0.0.1:7091/#/transaction/list

4.微服务配置

依赖

除基础依赖外需添加：

<dependency>
  <groupId>com.alibaba.cloud</groupId>
  <artifactId>spring-cloud-starter-alibaba-seata</artifactId>
</dependency>

配置

每个微服务创建 file.conf文件，完整内容如下；

【微服务只需要复制 service 块配置即可】

#
# Licensed to the Apache Software Foundation (ASF) under one or more
# contributor license agreements.  See the NOTICE file distributed with
# this work for additional information regarding copyright ownership.
# The ASF licenses this file to You under the Apache License, Version 2.0
# (the "License"); you may not use this file except in compliance with
# the License.  You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#

transport {
  # tcp, Unix-domain-socket
  type = "TCP"
  #NIO, NATIVE
  server = "NIO"
  #enable heartbeat
  heartbeat = true
  # the tm client batch send request enable
  enableTmClientBatchSendRequest = false
  # the rm client batch send request enable
  enableRmClientBatchSendRequest = true
   # the rm client rpc request timeout
  rpcRmRequestTimeout = 2000
  # the tm client rpc request timeout
  rpcTmRequestTimeout = 30000
  # the rm client rpc request timeout
  rpcRmRequestTimeout = 15000
  #thread factory for netty
  threadFactory {
    bossThreadPrefix = "NettyBoss"
    workerThreadPrefix = "NettyServerNIOWorker"
    serverExecutorThread-prefix = "NettyServerBizHandler"
    shareBossWorker = false
    clientSelectorThreadPrefix = "NettyClientSelector"
    clientSelectorThreadSize = 1
    clientWorkerThreadPrefix = "NettyClientWorkerThread"
    # netty boss thread size
    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.default_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
    tableMetaCheckerInterval = 60000
    reportSuccessEnable = false
    sagaBranchRegisterEnable = false
    sagajsonParser = "fastjson"
    sagaRetryPersistModeUpdate = false
    phpsagaCompensatePersistModeUpdate = false
    tccActionInterceptorOrder = -2147482648 #Ordered.HIGHEST_PRECEDENCE + 1000
    sqlParserType = "druid"
    branchExecutionTimeoutXA = 60000
    connectionTwoPhaseHoldTimeoutXA = 10000
  }
  tm {
    commitRetryCount = 5
    rollbackRetryCount = 5
    defaultGlobalTransactionTimeout = 60000
    degradeCheck = false
    degradeCheckPeriod = 2000
    degradeCheckAllowTimes = 10
    interceptorOrder = -2147482648 #Ordered.HIGHEST_PRECEDENCE + 1000
  }
  undo {
    dataValidation = true
    onlyCareUpdateColumns = true
    logSerialization = "jackson"
    logTable = "undo_log"
    compress {
      enable = true
      # allow zip, gzip, deflater, lz4, bzip2, zstd default is zip
      type = zip
      # if rollback info size > threshold, then will be compress
      # allow k m g t
      threshold = 64k
    }
  }
  loadBalance {
      type = "XID"
      virtualNodes = 10
  }
}
log {
  exceptionRate = 100
}
tcc {
  fence {
    # tcc fence log table name
    logTableName = tcc_fence_log
    # tcc fence log clean period
    cleanPeriod = 1h
  }
}

事务模式

1.AT模式（推荐:自动补偿）

二阶提交协议原理

原理：基于反向SQL补偿，自动生成回滚日志

使用：

@Service
public class OrderService {
    @GlobalTransactional(name = "createOrder", timeoutMills = 60000)
    public void createOrder(OrderDTO order) {
        // 1. 扣减库存（调用库存服务）
        storageFeignClient.deduct(order.getProductId());
        // 2. 创建订单（本地事务）
        orderMapper.insert(order);
        // 3. 模拟异常触发回滚
        int i = 1 / 0; 
    }
}

关键机制：

• 一阶段：提交本地事务，生成回滚日志（undo_log）
• 二阶段：成功则异步删除日志，失败则通过日志反向补偿

特点：

• 对代码无侵入
• 需创建undo_log表
• 适用于大多数CRUD场景

2.XA模式（强一致）

原理：基于数据库XA协议的两阶段提交

配置：

seata:
  data-source-proxy-mode: XA  # 默认AT

特点：

• 基于数据库XA协议
• 两阶段提交（2PC）
• 事务持有锁时间较长，适合短事务

适用场景：强一致性需求，支持XA协议的数据库（如mysql 5.7+）

3.TCC模式（手动补偿）

原理：Try-Confirm-Cancel 三阶段控制

实现：

// 1. 定义TCC接口
public interface StorageTccService {
    @TwoPhaseBusinessAction(name = "deduct", 
                          commitMethod = "confirm", 
                          rollbackMethod = "cancel")
    boolean deduct(@BusinessActionContextParameter(paramName = "productId") String productId,
                   @BusinessActionContextParameter(paramName = "count") Integer count);
 android   
    boolean confirm(BusinessActionContext context);
    boolean cancel(BusinessActionContext context);
}

// 2. 实现Try逻辑
@Service
public class StorageTccServiceImpl implements StorageTccService {
    @Override
    public boolean deduct(String productId, Integer count) {
        // Try阶段：资源预留（例如冻结库存）
        return storageMapper.freezeStock(productId, count) > 0;
    }
    
    @Override
    public boolean confirm(BusinessActionContext context) {
        // Confirm阶段：真实扣减（例如删除冻结记录）
        String productId = context.getActionContext("productId");
  android      Integer count = context.getActionContext("count");
        return storageMapper.reduceStock(productId, count) > 0;
    }
    
    @Override
    public boolean cancel(BusinessActionContext context) {
        // Cancel阶段：释放资源（例如恢复冻结库存）
        String productId = context.getActionContext("productId");
        Integer count = context.getActionContext("count");
        return storageMappandroider.unfreezeStock(productId, count) > 0;
    }
}

使用限制：

• 需自行实现Try/Confirm/Cancel方法
• Confirm和Cancel需保证幂等性

特点：高性能，但javascript需手动编写补偿逻辑

4.Saga模式（长事务）

实现方式：

通过状态机配置补偿策略：

@SagaStart
public void createOrderSaga(Order order) {
    // 1. 创建订单
    orderService.create(order);
    // 2. 调用支付服务（若失败则触发逆向操作）
    paymentService.pay(order.getId());
}
// 定义补偿方法
@Compensate
public void compensateOrder(Order order) {
    orderService.delete(order.getId());
}

原理：长事务拆分+逆向补偿

适用场景：跨系统长时间操作（如订单+物流+支付）

总结

模式选型对照表：

核心要点：

最佳实践：

1. 生产环境建议使用Nacos作为配置中心
2. AT模式需要开启数据库的本地事务支持（如MySQL的InnoDB引擎）
3. 全局事务超时时间建议设置：seata.tx.timeout=60000（单位毫秒）

以上为个人经验，希望能给大家一个参考，也希望大家多多支持编程客栈(www.devze.com)。