分布式事务：springboot整合Atomikos

我是小趴菜
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大家好，我是小趴菜，今天我们学习一下几种分布式事务的解决方案的两阶段提交：Atomikos

什么是Atomikos

Atomikos是一个开源的事务管理器，用于管理和控制分布式事务的执行流程，提供了可靠的，高性能的事务管理解决方案，可以与多种应用和数据库集成

实战

创建springBoot项目，pom.xml文件如下：

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.7.14</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <groupId>com.xpc</groupId>
    <artifactId>distribute-transaction</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jta-atomikos</artifactId>
        </dependency>
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.3.1</version>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.22</version>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter-test</artifactId>
            <version>2.3.1</version>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <excludes>
                        <exclude>
                            <groupId>org.projectlombok</groupId>
                            <artifactId>lombok</artifactId>
                        </exclude>
                    </excludes>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>

配置多数据源

server.port=8080

#数据源test
spring.test-datasource.driverClassName = com.mysql.jdbc.Driver
spring.test-datasource.jdbc-url = jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone=Asia/Shanghai&allowPublicKeyRetrieval=true
spring.test-datasource.username = root
spring.test-datasource.password = 12345

#数据源cyp
spring.cyp-datasource.driverClassName = com.mysql.jdbc.Driver
spring.cyp-datasource.jdbc-url = jdbc:mysql://localhost:3306/test_1?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone=Asia/Shanghai&allowPublicKeyRetrieval=true
spring.cyp-datasource.username = root
spring.cyp-datasource.password = 12345

logging.level.com.atomikos = debug

多数据源配置类

//配置扫描对应的dao层的包
@MapperScan(basePackages = "com.xpc.dao", sqlSessionFactoryRef = "testSqlSessionFactory")
@Configuration
public class TestMyBatisConfig {


    @SneakyThrows
    @Bean
    public SqlSessionFactory testSqlSessionFactory(@Qualifier("testDataSource") DataSource dataSource) {
        SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
        sqlSessionFactoryBean.setDataSource(dataSource);
        return sqlSessionFactoryBean.getObject();
    }
}

package com.xpc.config;

import lombok.SneakyThrows;
import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.SqlSessionFactoryBean;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import javax.sql.DataSource;

@Configuration
@MapperScan(basePackages = "com.xpc.dao1",sqlSessionFactoryRef = "cypSqlSessionFactory")
public class CypMyBatisConfig {

    @SneakyThrows
    @Bean
    public SqlSessionFactory cypSqlSessionFactory(@Qualifier("cypDataSource") DataSource dataSource) {
        SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
        sqlSessionFactoryBean.setDataSource(dataSource);
        return sqlSessionFactoryBean.getObject();
    }
}

Atomikos配置

import com.atomikos.jdbc.AtomikosDataSourceBean;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import javax.sql.DataSource;
import java.util.Properties;

@Configuration
public class AtomikosDataSourceConfig {


    @Value("${spring.test-datasource.jdbc-url}")
    private String testUrl;

    @Value("${spring.test-datasource.username}")
    private String testUser;

    @Value("${spring.test-datasource.password}")
    private String testPassword;

    @Value("${spring.cyp-datasource.jdbc-url}")
    private String cypUrl;

    @Value("${spring.cyp-datasource.username}")
    private String cypUser;

    @Value("${spring.cyp-datasource.password}")
    private String cypPassword;
    @Bean(name = "testDataSource")
    public DataSource testDataSource() {
        AtomikosDataSourceBean atomikosDataSourceBean = new AtomikosDataSourceBean();
        //设置唯一资源name
        atomikosDataSourceBean.setUniqueResourceName("testDataSource");
        atomikosDataSourceBean.setXaDataSourceClassName("com.mysql.cj.jdbc.MysqlXADataSource");
        Properties properties = new Properties();
        properties.setProperty("URL", testUrl);
        properties.setProperty("user", testUser);
        properties.setProperty("password", testPassword);
        atomikosDataSourceBean.setXaProperties(properties);
        return atomikosDataSourceBean;
    }


    @Bean(name = "cypDataSource")
    public DataSource cypDataSource() {
        AtomikosDataSourceBean atomikosDataSourceBean = new AtomikosDataSourceBean();
        //设置唯一资源name
        atomikosDataSourceBean.setUniqueResourceName("cypDataSource");
        atomikosDataSourceBean.setXaDataSourceClassName("com.mysql.cj.jdbc.MysqlXADataSource");
        Properties properties = new Properties();
        properties.setProperty("URL", cypUrl);
        properties.setProperty("user", cypUser);
        properties.setProperty("password", cypPassword);
        atomikosDataSourceBean.setXaProperties(properties);
        return atomikosDataSourceBean;
    }
}

import org.springframework.context.annotation.Configuration;
import com.atomikos.icatch.jta.UserTransactionImp;
import com.atomikos.icatch.jta.UserTransactionManager;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.DependsOn;
import org.springframework.transaction.PlatformTransactionManager;
import org.springframework.transaction.jta.JtaTransactionManager;

import javax.transaction.TransactionManager;
import javax.transaction.UserTransaction;

@Configuration
public class AtomikosConfig {


    @Bean(name = "userTransaction")
    public UserTransaction userTransaction() {
        return new UserTransactionImp();
    }

    @Bean(name = "atomikosTransactionManager")
    public TransactionManager atomikosTransactionManager() {
        return new UserTransactionManager();
    }

    @Bean(name = "platformTransactionManager")
    @DependsOn({"userTransaction", "atomikosTransactionManager"})
    public PlatformTransactionManager transactionManager() {
        UserTransaction userTransaction = userTransaction();
        TransactionManager transactionManager = atomikosTransactionManager();
        return new JtaTransactionManager(userTransaction, transactionManager);
    }
}

dao层

@Mapper
public interface TestDao {

    @Insert("insert into t_xpc (name) values (#{name})")
    void insert(Test1 test1);
}

@Mapper
public interface CypDao {

    @Insert("insert into t_cyp (name) values (#{name})")
    void insert(Tcyp tcyp);
}

接下来就是service业务了

@Service
public class XpcService {


    @Resource
    private TestDao testDao;

    @Resource
    private CypDao cypDao;


    @Transactional(rollbackFor = Exception.class)
    public String test() {
        Test1 test1 = new Test1();
        test1.setName("xpc-5");
        testDao.insert(test1);

        Tcyp tcyp = new Tcyp();
        tcyp.setName("xpc-5");
        cypDao.insert(tcyp);

        int i = 1/0;
        return "success";
    }
}

到这里springboot整合Atomikos就完成了，然后我们可以调用下该test方法，因为 int i = 1/0; 会抛出异常，所以这两条数据都不会插入成功，也就意味着事务成功回滚了

Atomikos有什么缺点吗？

Atomiko提供了两阶段提交，那么两阶段提交会有什么问题？

1：单点问题

image.png

事务管理器是直接集成在我们服务中的，也就是java进程中的，如果这时候这个服务挂了，那么整个分布式事务就都不可用了

2：资源锁定问题

在事务第一阶段的时候，我们的资源管理器RM就会锁定一些资源，这时候，其它事务进来就无法再次锁定同样的资源了，也就造成了阻塞的问题

如果这时候碰到了单点问题，导致这些资源释放不掉，那么其它事务就再也拿不到这些资源了

3：性能瓶颈问题

事务管理器在发起第一阶段的时候，必须等到所有的资源管理器都返回OK了，才会发起第二阶段commit，如果这时候有一个资源管理在第一阶段迟迟没有返回OK，那么事务管理器就会一直阻塞在这里

4：数据不一致

假设现在事务管理器(TM)收到所有资源管理器（RM）的第一阶段OK响应了，这时候就会发起第二阶段的commit了，但是这时候由于某些原因，导致某个资源管理器（RM）没有收到commit，这时候其它的资源管理器（RM）已经提交了，但是这个资源管理器（RM）还是没有提交事务的，这时候就造成了数据不一致的问题了

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