我希望通过数据库获取序列号。
这是我想要的：
1. 从数据库中读取实体并锁定它
2. 增加序列号并更新实体
我假设第一个线程可以锁定记录，而其他线程在第一个线程提交其事务之前不会起作用，然而，我得到了相反的结果。
以下是我的代码：
存储库：
public interface ActivityNoGeneratorRepository extends BaseRepository<ActivityNoGenerator, Long> {
@Lock(LockModeType.PESSIMISTIC_WRITE)
@Query(value = "select generator from ActivityNoGenerator generator where id=:id")
ActivityNoGenerator getGeneratorByIdForUpdate(@Param("id") Long id);
}
服务：
@Service
public class ActivityNoGeneratorServiceImpl implements IActivityNoGeneratorService {
@Autowired
private ActivityNoGeneratorRepository activityNoGeneratorRepository;
@Override
@Transactional
public String getActivityNo() {
ActivityNoGenerator activityNoGenerator = activityNoGeneratorRepository.getGeneratorByIdForUpdate(1L);
System.out.println(1);
Integer currentValue = activityNoGenerator.getCurrentValue() + 1;
if (!StringUtils.equals(DateFormatUtils.format(new Date(), "yyyyMM"), DateFormatUtils.format(activityNoGenerator.getLastAccessTime(), "yyyyMM"))) {
currentValue = 1;
}
String serialNum = String.format("%0" + activityNoGenerator.getWidth() + "d", currentValue);
String activityNo = activityNoGenerator.getPrefix() + activityNoGenerator.getPlatformCode() + DateFormatUtils.format(new Date(), "yyyyMM") + serialNum;
activityNoGenerator.setCurrentValue(currentValue);
activityNoGenerator.setLastAccessTime(new Date());
activityNoGeneratorRepository.save(activityNoGenerator);
return activityNo;
}
}
测试：
public class IActivityNoGeneratorServiceTest {
public static void main(String[] args) {
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("classpath*:spring/applicationContext.xml");
final IActivityNoGeneratorService activityNoGeneratorService = applicationContext.getBean(IActivityNoGeneratorService.class);
for (int i = 0; i < 2; i++) {
new Thread(new Runnable() {
@Override
public void run() {
System.out.println(activityNoGeneratorService.getActivityNo());
}
}).start();
}
}
}
结果：
Hibernate:
select
activityno0_.id as id1_3_,
activityno0_.current_value as current_2_3_,
activityno0_.last_access_time as last_acc3_3_,
activityno0_.platform_code as platform4_3_,
activityno0_.platform_name as platform5_3_,
activityno0_.prefix as prefix6_3_,
activityno0_.step as step7_3_,
activityno0_.width as width8_3_
from
activity_no_generator activityno0_
where
activityno0_.id=? for update
Hibernate:
select
activityno0_.id as id1_3_,
activityno0_.current_value as current_2_3_,
activityno0_.last_access_time as last_acc3_3_,
activityno0_.platform_code as platform4_3_,
activityno0_.platform_name as platform5_3_,
activityno0_.prefix as prefix6_3_,
activityno0_.step as step7_3_,
activityno0_.width as width8_3_
from
activity_no_generator activityno0_
where
activityno0_.id=? for update
1
1
Hibernate:
update
activity_no_generator
set
current_value=?,
last_access_time=?,
platform_code=?,
platform_name=?,
prefix=?,
step=?,
width=?
where
id=?
Hibernate:
update
activity_no_generator
set
current_value=?,
last_access_time=?,
platform_code=?,
platform_name=?,
prefix=?,
step=?,
width=?
where
id=?
Exception in thread "Thread-6" org.springframework.orm.jpa.JpaSystemException: commit failed; nested exception is org.hibernate.TransactionException: commit failed
at org.springframework.orm.jpa.vendor.HibernateJpaDialect.convertHibernateAccessException(HibernateJpaDialect.java:333)
at org.springframework.orm.jpa.vendor.HibernateJpaDialect.translateExceptionIfPossible(HibernateJpaDialect.java:244)
at org.springframework.orm.jpa.JpaTransactionManager.doCommit(JpaTransactionManager.java:521)
at org.springframework.transaction.support.AbstractPlatformTransactionManager.processCommit(AbstractPlatformTransactionManager.java:761)
at org.springframework.transaction.support.AbstractPlatformTransactionManager.commit(AbstractPlatformTransactionManager.java:730)
at org.springframework.transaction.interceptor.TransactionAspectSupport.commitTransactionAfterReturning(TransactionAspectSupport.java:483)
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:290)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:96)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:213)
at com.sun.proxy.$Proxy44.getActivityNo(Unknown Source)
at com.lemall.srd.pop.activity.oa.service.IActivityNoGeneratorServiceTest$1.run(IActivityNoGeneratorServiceTest.java:18)
at java.lang.Thread.run(Thread.java:745)
Caused by: org.hibernate.TransactionException: commit failed
at org.hibernate.engine.transaction.spi.AbstractTransactionImpl.commit(AbstractTransactionImpl.java:187)
at org.hibernate.jpa.internal.TransactionImpl.commit(TransactionImpl.java:77)
at org.springframework.orm.jpa.JpaTransactionManager.doCommit(JpaTransactionManager.java:517)
... 10 more
Caused by: org.hibernate.TransactionException: unable to commit against JDBC connection
at org.hibernate.engine.transaction.internal.jdbc.JdbcTransaction.doCommit(JdbcTransaction.java:116)
at org.hibernate.engine.transaction.spi.AbstractTransactionImpl.commit(AbstractTransactionImpl.java:180)
... 12 more
Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLTransactionRollbackException: Deadlock found when trying to get lock; try restarting transaction
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:404)
at com.mysql.jdbc.Util.getInstance(Util.java:387)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:950)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3966)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3902)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2526)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2673)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2545)
at com.mysql.jdbc.ConnectionImpl.commit(ConnectionImpl.java:1614)
at com.zaxxer.hikari.pool.ProxyConnection.commit(ProxyConnection.java:355)
at com.zaxxer.hikari.pool.HikariProxyConnection.commit(HikariProxyConnection.java)
at org.hibernate.engine.transaction.internal.jdbc.JdbcTransaction.doCommit(JdbcTransaction.java:112)
... 13 more
HD1020012017050631
Process finished with exit code 0
我调试我的代码，发现第二个线程在没有等待第一个线程提交的情况下就被执行了。
有什么错误的线索吗？非常感谢！
@Transactional(propagation = Propagation.REQUIRES_NEW)，因为我怀疑它会在两个线程中重用事务。 - Leonid Dashko