-
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; -
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; -
下面用一个简单示例演示多线程事务:
/**
* 平均拆分list方法.
* @param source
* @param n
* @param <T>
* @return
*/
public static <T> List<List<T>> averageAssign(List<T> source,int n){
List<List<T>> result=newArrayList<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;
}
/**线程池配置
* @version V1.0
*/
public class ExecutorConfig {
privatestaticintmaxPoolSize= Runtime.getRuntime().availableProcessors();
privatevolatilestatic ExecutorService executorService;
publicstatic ExecutorService getThreadPool() {
if (executorService == null){
synchronized (ExecutorConfig.class){
if (executorService == null){
executorService = newThreadPool();
}
}
}
return executorService;
}
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private static ExecutorService newThreadPool(){
intqueueSize=500;
intcorePool= Math.min(5, maxPoolSize);
returnnew ThreadPoolExecutor(corePool, maxPoolSize, 10000L, TimeUnit.MILLISECONDS,
new LinkedBlockingQueue<>(queueSize),newThreadPoolExecutor.AbortPolicy());
}
privateExecutorConfig(){
}
}
/** 获取sqlSession
* @version V1.0
*/
@Component
public class SqlContext {
@Resource
private SqlSessionTemplate sqlSessionTemplate;
public SqlSession getSqlSession(){
SqlSessionFactorysqlSessionFactory= sqlSessionTemplate.getSqlSessionFactory();
return sqlSessionFactory.openSession();
}
}
/**
* 测试多线程事务.
* @param employeeDOList
*/
@Override
@Transactional(rollbackFor = Exception.class)
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
ExecutorServiceservice= ExecutorConfig.getThreadPool();
//拆分数据,拆分5份
List<List<EmployeeDO>> lists=averageAssign(employeeDOList,2);
//执行的线程
Thread []threadArray = newThread[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
CountDownLatchcountDownLatch=newCountDownLatch(lists.size());
AtomicBooleanatomicBoolean=newAtomicBoolean(false);
for (inti=0;i<lists.size();i++){
List<EmployeeDO> list = lists.get(i);
threadArray[i] = newThread(() -> {
try {
if (!atomicBoolean.get()){
thrownew 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 (inti=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);
thrownew ServiceException("002","出现异常");
}
}
//测试用例
@RunWith(SpringRunner.class)
@SpringBootTest(classes = {
ThreadTest01.class, MainApplication.class})
public class ThreadTest01 {
@Resource
private EmployeeBO employeeBO;
/**
* 测试多线程事务.
* @throws InterruptedException
*/
@Test
public void MoreThreadTest2() throws InterruptedException {
intsize=10;
List<EmployeeDO> employeeDOList = new ArrayList<>(size);
for (inti=0; i<size;i++){
EmployeeDOemployeeDO=newEmployeeDO();
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();
}
}
}
@Resource
SqlContext sqlContext;
/**
* 测试多线程事务.
* @param employeeDOList
*/
@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)
SqlSessionsqlSession= sqlContext.getSqlSession();
Connectionconnection= sqlSession.getConnection();
try {
// 设置手动提交
connection.setAutoCommit(false);
//获取mapper
EmployeeMapperemployeeMapper= sqlSession.getMapper(EmployeeMapper.class);
//先做删除操作
employeeMapper.delete(null);
//获取执行器
ExecutorServiceservice= ExecutorConfig.getThreadPool();
List<Callable<Integer>> callableList = newArrayList<>();
//拆分list
List<List<EmployeeDO>> lists=averageAssign(employeeDOList, 5);
for (inti=0;i<lists.size();i++){
AtomicBooleanatomicBoolean=newAtomicBoolean(true);
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 = () -> {
if (!atomicBoolean.get()){
thrownew 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);
thrownew 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>
@Resource
SqlContext sqlContext;
/**
* 测试多线程事务.
* @param employeeDOList
*/
@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)
SqlSessionsqlSession= sqlContext.getSqlSession();
Connectionconnection= sqlSession.getConnection();
try {
// 设置手动提交
connection.setAutoCommit(false);
EmployeeMapperemployeeMapper= sqlSession.getMapper(EmployeeMapper.class);
//先做删除操作
employeeMapper.delete(null);
ExecutorServiceservice= ExecutorConfig.getThreadPool();
List<Callable<Integer>> callableList = newArrayList<>();
List<List<EmployeeDO>> lists=averageAssign(employeeDOList, 5);
for (inti=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);
thrownew ServiceException("002","出现异常");
// throw new ServiceException(ExceptionCodeEnum.EMPLOYEE_SAVE_OR_UPDATE_ERROR);
}
}
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