Question

我有三张桌子。表A用复合FK引用表B和C. 当我这么做时：

A a = (A) em.find(A.class, aPk);

它给了我ConcurrentModificationException。关于什么会出错的任何指针？

@Entity
public class A implements Serializable {
@EmbeddedId
private APK pk;

@OneToOne(cascade=CascadeType.ALL)
private B b;

@OneToOne(cascade=CascadeType.ALL)
private C c;
}

@Entity
public class B implements Serializable {
@EmbeddedId
private BPK pk;
...
}

@Entity
public class C implements Serializable {
@EmbeddedId
private CPK pk;
...
}

堆栈追踪：

Caused by: java.util.ConcurrentModificationException
    at java.util.HashMap$HashIterator.nextEntry(HashMap.java:793)
    at java.util.HashMap$KeyIterator.next(HashMap.java:828)
    at org.apache.openjpa.kernel.ManagedCache.dirtyCheck(ManagedCache.java:307)
    at org.apache.openjpa.kernel.BrokerImpl.hasTransactionalObjects(BrokerImpl.java:3820)
    at org.apache.openjpa.kernel.BrokerImpl.addToTransaction(BrokerImpl.java:3892)
    at org.apache.openjpa.kernel.StateManagerImpl.setPCState(StateManagerImpl.java:216)
    at org.apache.openjpa.kernel.StateManagerImpl.initialize(StateManagerImpl.java:313)
    at org.apache.openjpa.kernel.StateManagerImpl.initialize(StateManagerImpl.java:275)
    at org.apache.openjpa.jdbc.kernel.JDBCStoreManager.initializeState(JDBCStoreManager.java:351)
    at org.apache.openjpa.jdbc.kernel.JDBCStoreManager.initialize(JDBCStoreManager.java:278)
    at org.apache.openjpa.kernel.DelegatingStoreManager.initialize(DelegatingStoreManager.java:111)
    at org.apache.openjpa.kernel.ROPStoreManager.initialize(ROPStoreManager.java:57)
    at org.apache.openjpa.kernel.BrokerImpl.initialize(BrokerImpl.java:913)
    at org.apache.openjpa.kernel.BrokerImpl.find(BrokerImpl.java:871)

Answer 1

使用运行时增强器后，大多数问题都会消失。

OpenJPA：在单线程环境中查找实体时出现ConcurrentModificationException

1 个答案: