交易提交后，冬眠线程不会完成

Question

我在Java SE程序中使用Hibernate，因此没有应用程序服务器。

我正在使用我的持久经理：

import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
public enum PersistenceManager {
    INSTANCE;
    private EntityManagerFactory emFactory;
    private PersistenceManager() {
        emFactory = Persistence.createEntityManagerFactory("jpa-example");
    }
    public EntityManager getEntityManager() {
        return emFactory.createEntityManager();
    }
    public void close() {
        emFactory.close();
    }
}

具有非常简单的持久性。xml：

<persistence xmlns="http://xmlns.jcp.org/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence
http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd"
             version="2.1">
    <persistence-unit name="jpa-example" transaction-type="RESOURCE_LOCAL">
        <provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
        <properties>
            <property name="javax.persistence.jdbc.url" value="jdbc:mysql://localhost/mydb?useSSL=false" />
            <property name="javax.persistence.jdbc.user" value="myuser" />
            <property name="javax.persistence.jdbc.password" value="password" />
            <property name="hibernate.show_sql" value="true" />
            <property name="hibernate.format_sql" value="true" />
            <property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect" />
        </properties>
    </persistence-unit>
</persistence>

我的功能代码：

        EntityManager em = PersistenceManager.INSTANCE.getEntityManager();
        em.getTransaction().begin();
        // dummy object instantiation here
        em.persist(obj1);
        em.persist(obj2);
        em.getTransaction().commit();
        System.out.println("comitting");
        em.close();
        System.out.println("closed");
        PersistenceManager.INSTANCE.close();
        System.out.println("Done");

我的应用程序确实按预期打印所有内容，即"闭合"one_answers"完成"出现在我的控制台中。我还在我的MySQL容器中看到交易很好。但是，该程序永远不会终止和结束例外：

[WARNING] thread Thread[Abandoned connection cleanup thread,5,com.org.Main] was interrupted but is still alive after waiting at least 15000msecs
[WARNING] thread Thread[Abandoned connection cleanup thread,5,com.org.Main] will linger despite being asked to die via interruption
[WARNING] NOTE: 1 thread(s) did not finish despite being asked to  via interruption. This is not a problem with exec:java, it is a problem with the running code. Although not serious, it should be remedied.
[WARNING] Couldn't destroy threadgroup org.codehaus.mojo.exec.ExecJavaMojo$IsolatedThreadGroup[name=com.org.Main,maxpri=10]
java.lang.IllegalThreadStateException
    at java.lang.ThreadGroup.destroy (ThreadGroup.java:778)
    at org.codehaus.mojo.exec.ExecJavaMojo.execute (ExecJavaMojo.java:321)
    at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo (DefaultBuildPluginManager.java:134)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:208)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:154)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:146)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:117)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:81)
    at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build (SingleThreadedBuilder.java:51)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute (LifecycleStarter.java:128)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:309)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:194)
    at org.apache.maven.DefaultMaven.execute (DefaultMaven.java:107)
    at org.apache.maven.cli.MavenCli.execute (MavenCli.java:955)
    at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:290)
    at org.apache.maven.cli.MavenCli.main (MavenCli.java:194)
    at sun.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke (Method.java:498)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:289)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:229)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:415)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:356)

为什么？我在做什么错误？似乎有一些非阻止电话要关闭，这需要时间，但该程序希望终止。

Answer 1

您似乎在本文https://stackoverflow.com/a/29987290/10691359中运行。他用

解决了自己的问题

-dexec.cleanupdaemonthreads = false

您的问题与休眠无关。

这里的另一个解决方案https://stackoverflow.com/a/45470078/10691359是在您的主要末端使用System.exit(0)。