Java多线程事务回滚@Transactional失效处理方案

2022-11-13 14:40

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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

示例事务不成功操作


@Override
@Transactional
public void saveThread(List<EmployeeDO> 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<List<EmployeeDO>> 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<lists.size();i++){
if (i==lists.size()-1){
atomicBoolean.set(false);
}
List<EmployeeDO> 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 <lists.size(); i++){
service.execute(threadArray[i]);
}
//当子线程执行完毕时,主线程再往下执行
countDownLatch.await();
System.out.println("添加完毕");
}catch (Exception e){
log.info("error",e);
throw new ServiceException("002","出现异常");
}finally {
connection.close();
}
}

数据库中存在一条数据：

//测试用例
@RunWith(SpringRunner.class)
@SpringBootTest(classes = { ThreadTest01.class, MainApplication.class})
public class ThreadTest01 {

@Resource
private EmployeeBO employeeBO;


@Test
public void MoreThreadTest2() throws InterruptedException {
int size = 10;
List<EmployeeDO> employeeDOList = new ArrayList<>(size);
for (int i = 0; i<size;i++){
EmployeeDO employeeDO = new EmployeeDO();
employeeDO.setEmployeeName("lol"+i);
employeeDO.setAge(18);
employeeDO.setGender(1);
employeeDO.setIdNumber(i+"XX");
employeeDO.setCreatTime(Calendar.getInstance().getTime());
employeeDOList.add(employeeDO);
}
try {
employeeBO.saveThread(employeeDOList);
System.out.println("添加成功");
}catch (Exception e){
e.printStackTrace();
}
}
}

测试结果：

可以发现子线程组执行时，有一个线程执行失败，其他线程也会抛出异常，但是主线程中执行的删除操作，没有回滚，@Transactional注解没有生效。

使用sqlSession控制手动提交事务

@Resource
SqlContext sqlContext;

@Override
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<>();
//拆分list
List<List<EmployeeDO>> lists=averageAssign(employeeDOList, 5);
AtomicBoolean atomicBoolean = new AtomicBoolean(true);
for (int i =0;i<lists.size();i++){
if (i==lists.size()-1){
atomicBoolean.set(false);
}
List<EmployeeDO> list = lists.get(i);
//使用返回结果的callable去执行,
Callable<Integer> 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<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();
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 id="saveBatch" parameterType="List">
INSERT INTO
employee (employee_id,age,employee_name,birth_date,gender,id_number,creat_time,update_time,status)
values
<foreach collection="list" item="item" index="index" separator=",">
(
#{item.employeeId},
#{item.age},
#{item.employeeName},
#{item.birthDate},
#{item.gender},
#{item.idNumber},
#{item.creatTime},
#{item.updateTime},
#{item.status}
)
</foreach>
</insert>

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;

@Override
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);
EmployeeMapper employeeMapper = sqlSession.getMapper(EmployeeMapper.class);
//先做删除操作
employeeMapper.delete(null);
ExecutorService service = ExecutorConfig.getThreadPool();
List<Callable<Integer>> callableList = new ArrayList<>();
List<List<EmployeeDO>> lists=averageAssign(employeeDOList, 5);
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) {
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：