多线程的事务回滚问题
环境要求
1.mybatis-plus或mybatis
2.支持单表的增删改查
3.书写工具类将集合平分，获取线程池
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
public class ThreadUtil {
/**
* 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=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;
}
/** 线程池配置
* @version V1.0
*/
public static 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(){}
}
}
4.书写服务类接口
/**
* <p>
* 服务类
* </p>
*
* @author wjj
* @since 2023-01-07
*/
public interface DeptService extends IService<Dept> {
//使用@Transactional测试多线程回滚问题
void saveThread(List<Dept> employeeDOList);
//使用手动操作失误测试多线程回滚问题
void saveThread2(List<Dept> employeeDOList) throws SQLException;
//使用手动操作事务正常测试多线程
void saveThread3(List<Dept> employeeDOList) throws SQLException;
}
5.书写服务类实现
import com.zhuoyue.model.Dept;
import com.zhuoyue.mapper.DeptMapper;
import com.zhuoyue.service.DeptService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.zhuoyue.util.ThreadUtil;
import lombok.extern.slf4j.Slf4j;
import org.apache.ibatis.session.SqlSession;
import org.mybatis.spring.SqlSessionTemplate;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import javax.annotation.Resource;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Future;
import java.util.concurrent.atomic.AtomicBoolean;
import static com.zhuoyue.util.ThreadUtil.averageAssign;
/**
* <p>
* 服务实现类
* </p>
*
* @author myl
* @since 2023-01-07
*/
@Service
@Slf4j
public class DeptServiceImpl extends ServiceImpl<DeptMapper, Dept> implements DeptService {
/**
* 测试多线程事务.
* @param employeeDOList
*/
@Resource
private SqlSessionTemplate sqlSessionTemplate;
@Override
@Transactional
public void saveThread(List<Dept> 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().deleteById(8834L);
//获取线程池
ExecutorService service = ThreadUtil.ExecutorConfig.getThreadPool();
//拆分数据,拆分5份
List<List<Dept>> 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<Dept> list = lists.get(i);
threadArray[i] = new Thread(() -> {
try {
//最后一个线程抛出异常
if (!atomicBoolean.get()){
throw new RuntimeException("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 RuntimeException("出现异常");
}finally {
}
}
/**
* 测试多线程事务.
* @param employeeDOList
*/
@Override
public void saveThread2(List<Dept> employeeDOList) throws SQLException {
// 获取数据库连接,获取会话(内部自有事务)
SqlSession sqlSession = sqlSessionTemplate.getSqlSessionFactory().openSession();
Connection connection = sqlSession.getConnection();
try {
// 设置手动提交
connection.setAutoCommit(false);
//获取mapper
DeptMapper mapper = sqlSession.getMapper(DeptMapper.class);
//先做删除操作
mapper.deleteById(8834L);
//获取执行器
ExecutorService service = ThreadUtil.ExecutorConfig.getThreadPool();
List<Callable<Integer>> callableList = new ArrayList<>();
//拆分list
List<List<Dept>> lists=ThreadUtil.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<Dept> 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 RuntimeException("001出现异常");
}
return mapper.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 RuntimeException("002出现异常");
}finally {
connection.close();
}
}
/**
* 测试多线程事务.
* @param employeeDOList
*/
@Override
public void saveThread3(List<Dept> employeeDOList) throws SQLException {
// 获取数据库连接,获取会话(内部自有事务)
SqlSession sqlSession = sqlSessionTemplate.getSqlSessionFactory().openSession();
Connection connection = sqlSession.getConnection();
try {
// 设置手动提交
connection.setAutoCommit(false);
DeptMapper mapper = sqlSession.getMapper(DeptMapper.class);
//先做删除操作
this.getBaseMapper().deleteById(8834L);
ExecutorService service = ThreadUtil.ExecutorConfig.getThreadPool();
List<Callable<Integer>> callableList = new ArrayList<>();
List<List<Dept>> lists=ThreadUtil.averageAssign(employeeDOList, 5);
for (int i =0;i<lists.size();i++){
List<Dept> list = lists.get(i);
Callable<Integer> callable = () -> mapper.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 RuntimeException("002出现异常");
// throw new ServiceException(ExceptionCodeEnum.EMPLOYEE_SAVE_OR_UPDATE_ERROR);
}
}
}
测试
1.使用@Transactional测试多线程事务不回滚
2.手动操作事务多线程事务回滚
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