多线程事物回滚

背景

在spring中 @Transactional 注解可以控制事务，使出现异常时会进行回滚。但在多线程中则不生效。例如现在需要插入大量业务数据，但在插入数据之前主线程先执行删除动作，之后再将数据等分分批交由子线程去执行。那么当其中某个子线程执行失败时，主线程删除的数据则不会回滚，从而导致数据一致性受损。因此需要一个解决方案，如下：

代码

ExecutorConfig

线程池配置类

package com.python.config;

import java.util.concurrent.ExecutorService;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;

/**
 * 线程池配置
 */
public class ExecutorConfig {
    private static int maxPoolSize = Runtime.getRuntime().availableProcessors();
    private volatile static ExecutorService executorService;

    public static ExecutorService getThreadPool() {
        if (executorService == null) {
            synchronized (ExecutorConfig.class) {
                if (executorService == null) {
                    executorService = newThreadPool();
                }
            }
        }
        return executorService;
    }

    private static ExecutorService newThreadPool() {
        int queueSize = 500;
        int corePool = Math.min(5, maxPoolSize);
        return new ThreadPoolExecutor(corePool, maxPoolSize, 10000L, TimeUnit.MILLISECONDS,
                new LinkedBlockingQueue<Runnable>(queueSize), new ThreadPoolExecutor.AbortPolicy());
    }

    private ExecutorConfig() {  }
}

SqlContext

获取sqlSession

package com.python.config;

import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.SqlSessionTemplate;
import org.springframework.stereotype.Component;

import javax.annotation.Resource;

@Component
public class SqlContext {
    @Resource
    private SqlSessionTemplate sqlSessionTemplate;

    public SqlSession getSqlSession() {
        SqlSessionFactory sqlSessionFactory = sqlSessionTemplate.getSqlSessionFactory();
        return sqlSessionFactory.openSession();
    }
}

多线程插入操作

@Resource
    SqlContext sqlContext;

    /**
     * 测试多线程事务
     */
    public void saveThread(List<EmployeeDO> employeeDOList) throws SQLException {
        // 获取数据库连接,获取会话(内部自有事务)
        SqlSession sqlSession = sqlContext.getSqlSession();
        Connection connection = sqlSession.getConnection();
        try {
            // 设置手动提交
            connection.setAutoCommit(false);
            //获取mapper
            EmployeeMapper employeeMapper = sqlSession.getMapper(EmployeeMapper.class);
            //先做删除操作
            employeeMapper.delete(null);

            // 获取执行器
            ExecutorService service = ExecutorConfig.getThreadPool();
            List<Callable<Integer>> callableList = new ArrayList<Callable<Integer>>();
            // 拆分list
            List<List<EmployeeDO>> lists = averageAssign(employeeDOList, 5);
            AtomicBoolean atomicBoolean = new AtomicBoolean(true);
            for (int i = 0; i < lists.size(); i++) {
                List<EmployeeDO> list = lists.get(i);
                Callable<Integer> callable = () -> employeeMapper.saveBatch(list);
                callableList.add(callable);
            }
            
            //执行子线程
            List<Future<Integer>> futures = service.invokeAll(callableList);
            for (Future<Integer> future : futures) {
                //如果有一个执行不成功,则全部回滚
                if (future.get() <= 0) {
                    connection.rollback();
                    return;
                }
            }
            connection.commit();
            log.info("添加完毕");
        } catch (Exception e) {
            connection.rollback();
            log.error("error", e);
            throw new ServiceException("001", "出现异常");
        } finally {
            connection.close();
        }
    }

    /**
     * 平均拆分list
     */
    public static <T> List<List<T>> averageAssign(List<T> source, int n) {
        List<List<T>> result = new ArrayList<List<T>>();
        int remaider = source.size() % n;
        int number = source.size() / n;
        int offset = 0;//偏移量
        for (int i = 0; i < n; i++) {
            List<T> value = null;
            if (remaider > 0) {
                value = source.subList(i * number + offset, (i + 1) * number + offset + 1);
                remaider--;
                offset++;
            } else {
                value = source.subList(i * number + offset, (i + 1) * number + offset);
            }
            result.add(value);
        }
        return result;
    }