探索 Seata 分布式事务

Seata（Simple Extensible Autonomous Transaction Architecture）是阿里巴巴开源的一款分布式事务解决方案，旨在帮助开发者解决微服务架构下的分布式事务问题。它提供了高效且易于使用的分布式事务管理能力，支持多种事务模式，确保数据的一致性和完整性。

以下是 Seata 的一些关键特性和功能：

全局事务管理：Seata 提供了一个全局事务协调器（Transaction Coordinator, TC），负责管理全局事务的生命周期，包括开始、提交、回滚等操作。
AT 模式（Automatic Transaction）：这是 Seata 最常用的事务模式，通过代理数据库操作，实现自动的分支事务管理。AT 模式下，Seata 会在业务操作前后自动生成快照，并在事务提交或回滚时进行相应的处理。
TCC 模式（Try-Confirm-Cancel）：这种模式需要开发者手动实现 Try、Confirm 和 Cancel 三个阶段的逻辑。Try 阶段预留资源，Confirm 阶段确认操作，Cancel 阶段则回滚操作。这种模式适用于需要精细控制事务逻辑的场景。
SAGA 模式：基于补偿机制的长事务解决方案，适用于跨多个服务的复杂业务流程。每个步骤都有对应的补偿操作，当某一步失败时，可以通过执行补偿操作来回滚整个事务。
XA 模式：基于两阶段提交协议的分布式事务解决方案，适用于支持 XA 协议的数据库。第一阶段准备事务，第二阶段提交或回滚事务。
高性能：Seata 通过优化网络通信和存储机制，提供了高性能的事务处理能力，能够满足大规模分布式系统的需求。
易于集成：Seata 支持与 Spring Cloud、Dubbo、gRPC 等主流微服务框架的无缝集成，开发者只需进行简单配置即可使用分布式事务功能。
可扩展性：Seata 提供了丰富的 SPI 接口，允许开发者根据具体需求进行扩展和定制，例如自定义事务日志存储、事务协调策略等。
社区活跃：作为一个开源项目，Seata 拥有活跃的社区和丰富的文档资源，开发者可以方便地获取支持和帮助。

通过 Seata，开发者可以轻松地在分布式系统中实现一致性事务管理，确保数据的一致性和完整性，从而提高系统的可靠性和稳定性。

参考官方文档

下载 Seata

官方下载地址

我使用的是 1.4.1 版本：

进入conf目录，调整下面的配置文件

registry.conf

设置使用 Nacos 注册中心：

registry {# file 、nacos 、eureka、redis、zk、consul、etcd3、sofa# type = "file"type = "nacos"loadBalance = "RandomLoadBalance"loadBalanceVirtualNodes = 10nacos {application = "seata-server"serverAddr = "127.0.0.1:8848"group = "SEATA_GROUP"namespace = "public"cluster = "default"username = "nacos"password = "nacos"}
}config {# file、nacos 、apollo、zk、consul、etcd3# type = "file"type = "nacos"nacos {serverAddr = "127.0.0.1:8848"namespace = "public"group = "SEATA_GROUP"username = "nacos"password = "nacos"}}

file.conf

使用 MySQL 8.X JDBC 驱动、数据库账号、密码：

## transaction log store, only used in seata-server
store {## store mode: file、db、redismode = "db"## file store propertyfile {## store location dirdir = "sessionStore"# branch session size , if exceeded first try compress lockkey, still exceeded throws exceptionsmaxBranchSessionSize = 16384# globe session size , if exceeded throws exceptionsmaxGlobalSessionSize = 512# file buffer size , if exceeded allocate new bufferfileWriteBufferCacheSize = 16384# when recover batch read sizesessionReloadReadSize = 100# async, syncflushDiskMode = async}## database store propertydb {## 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.cj.jdbc.Driver"url = "jdbc:mysql://127.0.0.1:3306/seata?serverTimezone=UTC&useUnicode=true&characterEncoding=utf-8&useSSL=true"user = "root"password = "root"minConn = 5maxConn = 100globalTable = "global_table"branchTable = "branch_table"lockTable = "lock_table"queryLimit = 100maxWait = 5000}## redis store propertyredis {host = "127.0.0.1"port = "6379"password = ""database = "0"minConn = 1maxConn = 10maxTotal = 100queryLimit = 100}}

seata-1.4.1 配置

克隆 1.4.1 分支

git clone -b 1.4.1 https://gitee.com/ma-jiansheng/seata

微服务 yml 配置

seata:enabled: trueapplication-id: admin-servertx-service-group: admin-server-groupenable-auto-data-source-proxy: trueconfig:type: nacosnacos:namespace: publicserver-addr: 127.0.0.1:8848group: SEATA_GROUPuserName: "nacos"password: "nacos"registry:type: nacosnacos:application: seata-serverserver-addr: 127.0.0.1:8848namespace: publicuserName: "nacos"password: "nacos"

修改 script/config-center 下 config.txt 文件

修改 service.vgroupMapping 和数据库地址：

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
client.tm.defaultGlobalTransactionTimeout=60000
client.tm.degradeCheck=false
client.tm.degradeCheckAllowTimes=10
client.tm.degradeCheckPeriod=2000
service.vgroupMapping.admin-server-group=default
service.vgroupMapping.discussion-server-group=default
service.vgroupMapping.enterprise-server-group=default
service.vgroupMapping.job-server-group=default
service.vgroupMapping.student-server-group=default
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.cj.jdbc.Driver
store.db.url=jdbc:mysql:///dgut?serverTimezone=Asia/Shanghai&useUnicode=true&characterEncoding=utf-8&useSSL=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
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
log.exceptionRate=100
transport.serialization=seata
transport.compressor=none
metrics.enabled=false
metrics.registryType=compact
metrics.exporterList=prometheus
metrics.exporterPrometheusPort=9898

注意：

service.vgroupMapping.admin-server-group=default
service.vgroupMapping.discussion-server-group=default
service.vgroupMapping.enterprise-server-group=default
service.vgroupMapping.job-server-group=default
service.vgroupMapping.student-server-group=default

ABC-server-group 与项目模块中 yml 配置的 seata.tx-service-group 内容相同。

启动 nacos-config.sh ，将配置注入到 nacos 中

sh nacos-config.sh -h 127.0.0.1 -p 8848 -g SEATA_GROUP -u nacos -w nacos

在 nocos 中心可以看到新增的配置：

启动 Seata 服务

seata-server.bat -p 9000 -m file-p 指定启动seata server的端口号。
-h 指定seata server所绑定的主机。
-m 事务日志、事务执行信息存储的方式，目前支持file（文件方式）、db（数据库方式，建表语句请查看config/db_store.sql、config/db_undo_log.sql）

报错：

原因：路径问题，需手动指定 logs 路径

修改启动脚本：

@REM ----------------------------------------------------------------------------
@REM  Copyright 2001-2006 The Apache Software Foundation.
@REM
@REM  Licensed under the Apache License, Version 2.0 (the "License");
@REM  you may not use this file except in compliance with the License.
@REM  You may obtain a copy of the License at
@REM
@REM       http://www.apache.org/licenses/LICENSE-2.0
@REM
@REM  Unless required by applicable law or agreed to in writing, software
@REM  distributed under the License is distributed on an "AS IS" BASIS,
@REM  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
@REM  See the License for the specific language governing permissions and
@REM  limitations under the License.
@REM ----------------------------------------------------------------------------
@REM
@REM   Copyright (c) 2001-2006 The Apache Software Foundation.  All rights
@REM   reserved.@echo offset ERROR_CODE=0:init
@REM Decide how to startup depending on the version of windows@REM -- Win98ME
if NOT "%OS%"=="Windows_NT" goto Win9xArg@REM set local scope for the variables with windows NT shell
if "%OS%"=="Windows_NT" @setlocal@REM -- 4NT shell
if "%eval[2+2]" == "4" goto 4NTArgs@REM -- Regular WinNT shell
set CMD_LINE_ARGS=%*
goto WinNTGetScriptDir@REM The 4NT Shell from jp software
:4NTArgs
set CMD_LINE_ARGS=%$
goto WinNTGetScriptDir:Win9xArg
@REM Slurp the command line arguments.  This loop allows for an unlimited number
@REM of arguments (up to the command line limit, anyway).
set CMD_LINE_ARGS=
:Win9xApp
if %1a==a goto Win9xGetScriptDir
set CMD_LINE_ARGS=%CMD_LINE_ARGS% %1
shift
goto Win9xApp:Win9xGetScriptDir
set SAVEDIR=%CD%
%0\
cd %0\..\.. 
set BASEDIR=%CD%
cd %SAVEDIR%
set SAVE_DIR=
goto repoSetup:WinNTGetScriptDir
set BASEDIR=%~dp0\..:repoSetup
set REPO=if "%JAVACMD%"=="" set JAVACMD=javaif "%REPO%"=="" set REPO=%BASEDIR%\libset CLASSPATH="%BASEDIR%"\conf;"%REPO%"\*set ENDORSED_DIR=
if NOT "%ENDORSED_DIR%" == "" set CLASSPATH="%BASEDIR%"\%ENDORSED_DIR%\*;%CLASSPATH%if NOT "%CLASSPATH_PREFIX%" == "" set CLASSPATH=%CLASSPATH_PREFIX%;%CLASSPATH%@REM Reaching here means variables are defined and arguments have been captured
:endInit%JAVACMD% %JAVA_OPTS% -server -Xmx512m -Xms512m -Xmn512m -Xss512k -XX:SurvivorRatio=10 -XX:MetaspaceSize=128m -XX:MaxMetaspaceSize=256m -XX:MaxDirectMemorySize=1024m -XX:-OmitStackTraceInFastThrow -XX:-UseAdaptiveSizePolicy -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=D:\ideaFiles\seata-server-1.4.1\seata\bin\logs\java_heapdump.hprof -XX:+DisableExplicitGC -XX:+CMSParallelRemarkEnabled -XX:+UseCMSInitiatingOccupancyOnly -XX:CMSInitiatingOccupancyFraction=75 -Xloggc:D:\ideaFiles\seata-server-1.4.1\seata\bin\logs\seata_gc.log -verbose:gc -Dio.netty.leakDetectionLevel=advanced -Dlogback.color.disable-for-bat=true -classpath %CLASSPATH% -Dapp.name="seata-server" -Dapp.repo="%REPO%" -Dapp.home="%BASEDIR%" -Dbasedir="%BASEDIR%" io.seata.server.Server %CMD_LINE_ARGS%
if %ERRORLEVEL% NEQ 0 goto error
goto end:error
if "%OS%"=="Windows_NT" @endlocal
set ERROR_CODE=%ERRORLEVEL%:end
@REM set local scope for the variables with windows NT shell
if "%OS%"=="Windows_NT" goto endNT@REM For old DOS remove the set variables from ENV - we assume they were not set
@REM before we started - at least we don't leave any baggage around
set CMD_LINE_ARGS=
goto postExec:endNT
@REM If error code is set to 1 then the endlocal was done already in :error.
if %ERROR_CODE% EQU 0 @endlocal:postExecif "%FORCE_EXIT_ON_ERROR%" == "on" (if %ERROR_CODE% NEQ 0 exit %ERROR_CODE%
)exit /B %ERROR_CODE%

再次启动：成功

nacos 注册中心可以查看到 Seata 服务已启动：

使用 Seata 实现事务控制

创建数据库seata

建立下面三张表（branch_table, global_table, lock_table）：

-- the table to store GlobalSession data
drop table if exists `global_table`;
create table `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_gmt_modified_status` (`gmt_modified`, `status`),key `idx_transaction_id` (`transaction_id`)
);-- the table to store BranchSession data
drop table if exists `branch_table`;
create table `branch_table` (`branch_id` bigint not null,`xid` varchar(128) not null,`transaction_id` bigint ,`resource_group_id` varchar(32),`resource_id` varchar(256) ,`lock_key` varchar(128) ,`branch_type` varchar(8) ,`status` tinyint,`client_id` varchar(64),`application_data` varchar(2000),`gmt_create` datetime,`gmt_modified` datetime,primary key (`branch_id`),key `idx_xid` (`xid`)
);-- the table to store lock data
drop table if exists `lock_table`;
create table `lock_table` (`row_key` varchar(128) not null,`xid` varchar(96),`transaction_id` long ,`branch_id` long,`resource_id` varchar(256) ,`table_name` varchar(32) ,`pk` varchar(36) ,`gmt_create` datetime ,`gmt_modified` datetime,primary key(`row_key`)
);

在 dgut 数据库中加入一张 undo_log 表

这是 Seata 记录事务日志要用到的表：

CREATE TABLE `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,
`ext` VARCHAR(100) DEFAULT NULL,
PRIMARY KEY (`id`),
UNIQUE KEY `ux_undo_log` (`xid`, `branch_id`)
) ENGINE = INNODB
AUTO_INCREMENT = 1
DEFAULT CHARSET = utf8;

添加配置

在需要进行分布式控制的微服务中进行下面几项配置：

pom依赖

<dependency><groupId>com.alibaba.cloud</groupId><!-- 里面已经集成服务间调用X-id的传递，包括FeignClient的重写，如果在之前自定义封装过Feign，注意启动冲突--><artifactId>spring-cloud-starter-alibaba-seata</artifactId><exclusions><!--去除低版本--><exclusion><groupId>io.seata</groupId><artifactId>seata-spring-boot-starter</artifactId></exclusion></exclusions>
</dependency>
<!-- 添加 seata starter ，与服务端保持一致-->
<dependency><groupId>io.seata</groupId><artifactId>seata-spring-boot-starter</artifactId><version>1.4.1</version>
</dependency>
<dependency><groupId>com.alibaba.cloud</groupId><artifactId>spring-cloud-starter-alibaba-nacos-config</artifactId>
</dependency>

添加配置类 DataSourceProxyConfig

package com.yushanma.config;import com.alibaba.druid.pool.DruidDataSource;
import io.seata.rm.datasource.DataSourceProxy;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;@Configuration
public class DataSourceProxyConfig {
@Bean@ConfigurationProperties(prefix = "spring.datasource")
public DruidDataSource druidDataSource() {
return new DruidDataSource();}
@Primary@Beanpublic DataSourceProxy dataSource(DruidDataSource druidDataSource) {
return new DataSourceProxy(druidDataSource);}
}

yml 配置加入 Seata

seata:
enabled: trueapplication-id: order-server
tx-service-group: order-server-group
enable-auto-data-source-proxy: trueconfig:
type: nacosnacos:
namespace: public
server-addr: 127.0.0.1:8848
group: SEATA_GROUP
userName: "nacos"password: "nacos"registry:
type: nacosnacos:
application: seata-server
server-addr: 127.0.0.1:8848
namespace: public
userName: "nacos"password: "nacos"