支付宝一面多线程事务怎么回滚？
背景介绍
1.最近有一个大数据量插入的操作入库的业务场景，需要先做一些其他修改操作，然后在执行插入操作，由于插入数据可能会很多，用到多线程去拆分数据并行处理来提高响应时间，如果有一个线程执行失败，则全部回滚。
2.在spring中可以使用@Transactional注解去控制事务，使出现异常时会进行回滚，在多线程中，这个注解则不会生效，如果主线程需要先执行一些修改数据库的操作，当子线程在进行处理出现异常时，主线程修改的数据则不会回滚，导致数据错误。
3.下面用一个简单示例演示多线程事务。 公用的类和方法/** * 平均拆分list方法. * @param source * @param n * @param * @return */ public static List> averageAssign(List source,int n){ List> result=new ArrayList>(); int remaider=source.size()%n; int number=source.size()/n; int offset=0;//偏移量 for(int i=0;i 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; } /** 线程池配置 * @version V1.0 */ 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<>(queueSize),new ThreadPoolExecutor.AbortPolicy()); } private ExecutorConfig(){} } /** 获取sqlSession * @author 86182 * @version V1.0 */ @Component public class SqlContext { @Resource private SqlSessionTemplate sqlSessionTemplate; public SqlSession getSqlSession(){ SqlSessionFactory sqlSessionFactory = sqlSessionTemplate.getSqlSessionFactory(); return sqlSessionFactory.openSession(); } } 示例事务不成功操作/** * 测试多线程事务. * @param employeeDOList */ @Override @Transactional public void saveThread(List employeeDOList) { try { //先做删除操作,如果子线程出现异常,此操作不会回滚 this.getBaseMapper().delete(null); //获取线程池 ExecutorService service = ExecutorConfig.getThreadPool(); //拆分数据,拆分5份 List> lists=averageAssign(employeeDOList, 5); //执行的线程 Thread []threadArray = new Thread[lists.size()]; //监控子线程执行完毕,再执行主线程,要不然会导致主线程关闭,子线程也会随着关闭 CountDownLatch countDownLatch = new CountDownLatch(lists.size()); AtomicBoolean atomicBoolean = new AtomicBoolean(true); for (int i =0;i list = lists.get(i); threadArray[i] = new Thread(() -> { try { //最后一个线程抛出异常 if (!atomicBoolean.get()){ throw new ServiceException(＂001＂,＂出现异常＂); } //批量添加,mybatisPlus中自带的batch方法 this.saveBatch(list); }finally { countDownLatch.countDown(); } }); } for (int i = 0; i employeeDOList = new ArrayList<>(size); for (int i = 0; i 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> callableList = new ArrayList<>(); //拆分list List> lists=averageAssign(employeeDOList, 5); AtomicBoolean atomicBoolean = new AtomicBoolean(true); for (int i =0;i list = lists.get(i); //使用返回结果的callable去执行, Callable callable = () -> { //让最后一个线程抛出异常 if (!atomicBoolean.get()){ throw new ServiceException(＂001＂,＂出现异常＂); } return employeeMapper.saveBatch(list); }; callableList.add(callable); } //执行子线程 List> futures = service.invokeAll(callableList); for (Future 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(); System.out.println(＂添加完毕＂); }catch (Exception e){ connection.rollback(); log.info(＂error＂,e); throw new ServiceException(＂002＂,＂出现异常＂); }finally { connection.close(); } } // sql INSERT INTO employee (employee_id,age,employee_name,birth_date,gender,id_number,creat_time,update_time,status) values ( #{item.employeeId}, #{item.age}, #{item.employeeName}, #{item.birthDate}, #{item.gender}, #{item.idNumber}, #{item.creatTime}, #{item.updateTime}, #{item.status} )
数据库中一条数据：
测试结果，抛出异常：
删除操作的数据回滚了，数据库中的数据依旧存在，说明事务成功了。
成功操作示例： @Resource SqlContext sqlContext; /** * 测试多线程事务. * @param employeeDOList */ @Override public void saveThread(List 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); EmployeeMapper employeeMapper = sqlSession.getMapper(EmployeeMapper.class); //先做删除操作 employeeMapper.delete(null); ExecutorService service = ExecutorConfig.getThreadPool(); List> callableList = new ArrayList<>(); List> lists=averageAssign(employeeDOList, 5); for (int i =0;i list = lists.get(i); Callable callable = () -> employeeMapper.saveBatch(list); callableList.add(callable); } //执行子线程 List> futures = service.invokeAll(callableList); for (Future future:futures) { if (future.get()<=0){ connection.rollback(); return; } } connection.commit(); System.out.println(＂添加完毕＂); }catch (Exception e){ connection.rollback(); log.info(＂error＂,e); throw new ServiceException(＂002＂,＂出现异常＂); // throw new ServiceException(ExceptionCodeEnum.EMPLOYEE_SAVE_OR_UPDATE_ERROR); } }
测试结果：
数据库中数据：
删除的删除了，添加的添加成功了，测试成功。
来源：blog.csdn.net/weixin_43225491/article/details/117705686
