【发布时间】：2015-06-22 18:12:03
【问题描述】：
我的代码在很长一段时间内都运行良好，但经过几次重构后，我发现我突然无法再保存 Group 对象了。
我遇到了可怕的Row was updated or deleted by another transaction (or unsaved-value mapping was incorrect) 错误。在谷歌搜索之后，我当然找到了this StackOverflow question，但这对我没有任何帮助，因为我没有同时做任何事情。
在经历了我的重构之后，我发现唯一的不同就是这个变化。
之前：
final Collection<Sample> allByBarcode = sampleService.byBarcode(groupRequest.getSamples(), currentUser);
if (!allByBarcode.isEmpty()) {
Group group = new Group();
group.setName(groupRequest.getName());
group.setSamples(allByBarcode);
group.setType(groupRequest.getType());
group.setOwner(currentUser);
group = repository.save(group);
return Optional.ofNullable(group);
}
重构之后（不记得具体原因）变成了：
final Collection<Sample> allByBarcode = sampleService.byBarcode(groupRequest.getSamples(), currentUser);
if (!allByBarcode.isEmpty()) {
Group group = new Group();
group.setName(groupRequest.getName());
group.setSamples(new HashSet<>(allByBarcode));
group.setType(groupRequest.getType());
group.setOwner(currentUser);
group = repository.save(group);
return Optional.ofNullable(group);
}
改回原来的后，每次都突然又开始工作了，没有任何错误。
谁能解释这个错误的原因是什么，因为这是使它再次工作的代码的唯一区别？
更新 1：
我尝试了另一种变体：
Group group = new Group();
group.setName(groupRequest.getName());
group.setSamples(new ArrayList<>(allByBarcode));
group.setType(groupRequest.getType());
group.setOwner(currentUser);
group = repository.save(group);
请注意 ArrayList 而不是 HashSet - 出于某种原因，此代码有效。
我也尝试过LinkedList，它也有效。
有什么想法吗？
更新 2：
堆栈跟踪如下： 我已将其删除以删除大量与 Spring 和 Tomcat 相关的跟踪。
Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.springframework.orm.ObjectOptimisticLockingFailureException: Object of class [uk.ac.sanger.mig.aker.domain.Group] with identifier [93]: optimistic locking failed; nested exception is org.hibernate.StaleObjectStateException: Row was updated or deleted by another transaction (or unsaved-value mapping was incorrect) : [uk.ac.sanger.mig.aker.domain.Group#93]] with root cause
org.hibernate.StaleObjectStateException: Row was updated or deleted by another transaction (or unsaved-value mapping was incorrect) : [uk.ac.sanger.mig.aker.domain.Group#93]
at org.hibernate.persister.entity.AbstractEntityPersister.check(AbstractEntityPersister.java:2541)
at org.hibernate.persister.entity.AbstractEntityPersister.update(AbstractEntityPersister.java:3285)
at org.hibernate.persister.entity.AbstractEntityPersister.updateOrInsert(AbstractEntityPersister.java:3183)
at org.hibernate.persister.entity.AbstractEntityPersister.update(AbstractEntityPersister.java:3525)
at org.hibernate.action.internal.EntityUpdateAction.execute(EntityUpdateAction.java:159)
at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:465)
at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:351)
at org.hibernate.event.internal.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:350)
at org.hibernate.event.internal.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:56)
at org.hibernate.internal.SessionImpl.flush(SessionImpl.java:1222)
at org.hibernate.internal.SessionImpl.managedFlush(SessionImpl.java:425)
at org.hibernate.engine.transaction.internal.jdbc.JdbcTransaction.beforeTransactionCommit(JdbcTransaction.java:101)
at org.hibernate.engine.transaction.spi.AbstractTransactionImpl.commit(AbstractTransactionImpl.java:177)
at org.hibernate.jpa.internal.TransactionImpl.commit(TransactionImpl.java:77)
at org.springframework.orm.jpa.JpaTransactionManager.doCommit(JpaTransactionManager.java:517)
at org.springframework.transaction.support.AbstractPlatformTransactionManager.processCommit(AbstractPlatformTransactionManager.java:757)
at org.springframework.transaction.support.AbstractPlatformTransactionManager.commit(AbstractPlatformTransactionManager.java:726)
at org.springframework.transaction.interceptor.TransactionAspectSupport.commitTransactionAfterReturning(TransactionAspectSupport.java:521)
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:291)
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:207)
at com.sun.proxy.$Proxy116.createGroup(Unknown Source)
at uk.ac.sanger.mig.aker.controllers.GroupController.store(GroupController.java:107)
【问题讨论】：
-
您是如何在 Group 对象中定义您的示例元素的。是集合还是列表。
-
这是一个集合，但我用 HashSet 初始化它。
-
如果您发布堆栈跟踪以查看可怕异常的确切位置以及它所指的实体，这将有所帮助。您是否尝试过设置类型为 Set 的
samples属性？ -
还要考虑不使用BaseEntity.equals和hashCode中生成的id，stackoverflow.com/questions/1638723/…
-
指的是Group，明天我会发布堆栈跟踪。我也会试试你的建议，谢谢。