java – 如何在JPA EntityManager查询上设置超时时间

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我目前正从EntityManager查询中获取连接超时错误.是否可以为这些设置超时？

persistence.xml中

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.0" xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd">
  <persistence-unit name="CallPU" transaction-type="RESOURCE_LOCAL">
    <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
    <class>call.structure.Task</class>
    <class>call.structure.Installation</class>
    <class>call.structure.Contents</class>
    <class>call.structure.Recipient</class>
    <class>call.structure.CallTask</class>
    <class>call.structure.SmsTask</class>
    <class>call.structure.EmailTask</class>
    <class>call.security.User</class>
    <class>call.structure.content.Content</class>
    <class>call.structure.content.RecordContent</class>
    <class>call.structure.content.WaitContent</class>
    <class>call.structure.content.TextContent</class>
    <class>call.structure.content.VariableContent</class>
    <class>call.structure.content.SoundContent</class>
    <class>call.structure.content.SubjectContent</class>
    <class>call.structure.content.FileContent</class>
    <class>call.structure.Bounce</class>
    <properties>
      <property name="javax.persistence.jdbc.url" value="jdbc:oracle:thin:@127.0.0.1:1521:TEST"/>
      <property name="javax.persistence.jdbc.password" value="userpassword"/>
      <property name="javax.persistence.jdbc.driver" value="oracle.jdbc.OracleDriver"/>
      <property name="javax.persistence.jdbc.user" value="username"/>
    </properties>
   </persistence-unit>
</persistence>

代码在我的线程的run函数中超时：

private class TaskDB extends Thread {

    private final long WAITING_TIME = 20000L;

    @Override
    public void run() {

        Set<SmsTask> remove = SMSManager.this.getRemoveTask();
        Set<SmsTask> normal = SMSManager.this.getNormalTask();

        try {
            while(true){
                EntityManager em = DB.getEM();  //Calls EntityManagerFactory.createEntityManager()
                em.getTransaction().begin();

                Set<SmsTask> normalClone = new HashSet<SmsTask>(normal);
                // Abort task in futur.
                List<SmsTask> taskToRemove = new ArrayList<SmsTask>();
                if (!remove.isEmpty()) {

                    String queryString = "SELECT t FROM SmsTask t WHERE t.id IN :remove ";
                    if (!normalClone.isEmpty())
                        queryString += "AND t.id NOT IN :normal ";

                    Query query = em.createQuery(queryString);
                    query.setParameter("remove", Utils.taskToIdList(remove));
                    if (!normalClone.isEmpty())
                        query.setParameter("normal", Utils.taskToIdList(normalClone));

                    taskToRemove = (List<SmsTask>) query.getResultList();
                    for (SmsTask task : taskToRemove) {
                        removedTask.add(task);
                        remove.remove(task);
                    }
                }

                String queryString = "SELECT t FROM SmsTask t WHERE (t.scheduleTime IS NULL OR t.scheduleTime < :dateNow) AND t.status = co.dium.call.structure.Task.StatusTask.NOT_START ";
                if (!taskToRemove.isEmpty())
                    queryString += "AND t.id NOT IN :toRemove ";

                Query query = em.createQuery(queryString);
                query.setParameter("dateNow", Utils.obtainUniversalTime());
                if (!taskToRemove.isEmpty())
                    query.setParameter("toRemove", Utils.taskToIdList(taskToRemove));
                List<SmsTask> taskResults = (List<SmsTask>) query.getResultList();

                em.getTransaction().commit();

                for (SmsTask task : taskResults) 
                    addTask(task);

                SMSManager.TaskRemove.sleep(WAITING_TIME);
            }
        } catch (InterruptedException ex) {
            Logger.getLogger(SMSManager.class.getName()).log(Level.SEVERE, null, ex);
        }

        System.out.println("Thread interrompu !");
        Thread.currentThread().interrupt();
    }
}

我得到的超时错误：

org.clipse.persistence.exceptions.DatabaseException
Internal Exception: java.sql.SQLRecoverableException: I/O error: Socket read timed out
Error Code: 17002
Call: [....sql query...]
[...]
at org.eclipse.persistence.internal.EJBQueryImpl.getResultList(EJBQueryImpl.java:742)
at call.manager.sms.SMSManager$TaskDB.run(SMSManager.java:367)
Caused by: java.sql.SQLRecoverableException: I/O Error: Scoket read timed out
[...]

解决方法:

是的,有javax.persistence.query.timeout.根据JPA 2.0规范支持此查询提示是可选的：

Portable applications should not rely on this hint. Depending on the
persistence provider and database in use, the hint may or may not be
observed.

对于所有查询,可以将缺省值(以毫秒为单位)设置为persistence.xml：

<property name="javax.persistence.query.timeout" value="1000"/>

通过Persistence.createEntityManagerFactory创建EntityManagerFactory时,也可以给出相同的属性.

它也可以为每个查询覆盖/设置：

query.setHint("javax.persistence.query.timeout", 2000);

可以通过NamedQuery中的属性hints获得相同的功能.

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