Java 使用OpenJPA时ORM中的死锁

当使用运行10的

soapui

执行负载测试时，我遇到了死锁。每个线程向我的web服务发出10个请求，该web服务调用OpenJPA实体管理器的perits方法

然后我执行单个请求，所有请求都结束得很好，但在多线程环境中，它以死锁结束

我得到的错误是：

Deadlock found when trying to get lock; try restarting transaction {prepstmnt 12796448 UPDATE Assessment SET dateCompleted = ? WHERE id = ? [params=?, ?]} [code=1213, state=40001]

由于死锁而崩溃的方法如下：

@Override
public AssessmentKey update(AssessmentKey assessmentKey) {
    OpenJPAEntityManager openJpaEntityMgr = OpenJPAPersistence.cast(entityManager);
    for (Assessment assessment : assessmentKey.getAssessments()) {
        if (!entityManager.contains(assessment) && !openJpaEntityMgr.isDetached(assessment)) {
            LOGGER.debug("Persisting {}", assessment);
            entityManager.persist(assessment);
        }
    }
    return entityManager.merge(assessmentKey);
}

评估

是OpenJPA的一个实体，它只是一个包含JPA注释的普通实体。 如果你需要它的代码，就要它

我了解死锁是如何发生的，如何解决它们是在中提到的。但如何在ORM中解决这些问题，我无法找到答案

我的

persistence.xml

文件如下所示：

<persistence version="2.0" xmlns="http://java.sun.com/xml/ns/persistence">
    <persistence-unit name="com.groupgti.esb.online.tests">
        <provider>org.apache.openjpa.persistence.PersistenceProviderImpl</provider>
        <class>com.groupgti.esb.assessments.model.jpaimpl.Assessment</class>
        <exclude-unlisted-classes>true</exclude-unlisted-classes>
        <validation-mode>NONE</validation-mode>
        <properties>
            <property name="openjpa.Log" value="slf4j"/>
            <property name="openjpa.DataCache" value="false"/>
            <property name="openjpa.ReadLockLevel" value="none"/>
            <property name="openjpa.WriteLockLevel" value="pessimistic-write"/>
            <property name="openjpa.LockTimeout" value="10000"/>
            <property name="openjpa.RuntimeUnenhancedClasses" value="unsupported"/>
        </properties>
    </persistence-unit>
</persistence>

@ManyToOne(fetch = FetchType.EAGER, cascade = {CascadeType.PERSIST, CascadeType.MERGE})
@Index
@Column(nullable = false)
@ForeignKey
private AssessmentKey assessmentKey;

在

评估中

评估键

如下所示：

<persistence version="2.0" xmlns="http://java.sun.com/xml/ns/persistence">
    <persistence-unit name="com.groupgti.esb.online.tests">
        <provider>org.apache.openjpa.persistence.PersistenceProviderImpl</provider>
        <class>com.groupgti.esb.assessments.model.jpaimpl.Assessment</class>
        <exclude-unlisted-classes>true</exclude-unlisted-classes>
        <validation-mode>NONE</validation-mode>
        <properties>
            <property name="openjpa.Log" value="slf4j"/>
            <property name="openjpa.DataCache" value="false"/>
            <property name="openjpa.ReadLockLevel" value="none"/>
            <property name="openjpa.WriteLockLevel" value="pessimistic-write"/>
            <property name="openjpa.LockTimeout" value="10000"/>
            <property name="openjpa.RuntimeUnenhancedClasses" value="unsupported"/>
        </properties>
    </persistence-unit>
</persistence>

@ManyToOne(fetch = FetchType.EAGER, cascade = {CascadeType.PERSIST, CascadeType.MERGE})
@Index
@Column(nullable = false)
@ForeignKey
private AssessmentKey assessmentKey;

---

Assessment key

和

Assessment

是

OneToMany

的双向关系。

OneToMany

和

manytone

注释都具有

级联类型。持久化
和其他

要点是：

当
EntityManager
persist
Assessment
时，
AssessmentKey
也将保持。您应该需要再次保存或合并
AssessmentKey

让我提出以下建议或映射：

AssessmentKey.java

@OneToMany(fetch = FetchType.EAGER, cascade = {CascadeType.PERSIST, CascadeType.MERGE, CascadeType.REMOVE}, 
           mappedBy = "assessmentKey", orphanRemoval=true)
private List<Assessment> assessments;

数据库操作

@Override
public AssessmentKey update(AssessmentKey assessmentKey) {
    OpenJPAEntityManager openJpaEntityMgr = OpenJPAPersistence.cast(entityManager);
    // there may be your operation
    return entityManager.merge(assessmentKey);
}

我假设，
Assessment
当前
AssessmentKey
对象的值可能如下

On System                               |   In Existing Database
ID      Description                     |   ID      Descrition
1001    AAA         => No Changes       |   1001    AAA
1002    BBB         => Need to update   |   1002    BB
null    DDD         => Need to add      |   1003    CCC     => need to remove.

当EntityManager合并
Assessment key
时，
EntityManager
将完成我在上述数据结构中提到的
评估的所有过程

注意：确保
OneToMany
注释中的
orphaneremovation=true
 @您能否发布
O/R
与
Assessment
的关系？