Cannot integrate JMX with Spring application

Question

I have got a SPRING application. When I run

mvn jetty:run

everything is ok.

I would like to use JMX in my project.

I created another project, I tried tutorial for beginners and I was able to see some changes with jconsole.

Now, I want to use JMX in my real project and I would like to use SPRING libraries which manages JMX - following this post

How to integrate JMX with Spring?

I have got a class:

public class MyMainClass {
  private int var1;
  private int var2;
  private TimeUnit var3;

  // public getters and setters
  public static MyXXXClass<String, Object> getInstance();
}

and in config.xml

<!-- other beans -->
<bean id="myid" class="com.my.package.MyMainClass">
    <property name="var1" value.../>
    <property name="var2" value... />
    <property name="var3" value.../>
</bean>
<!-- other beans -->

I changed few things to make it works with JMX.

I added an interface:

import java.util.concurrent.TimeUnit;

public interface IMyMainClassBean {

    public int getVar1();

    public void setVar1(int var1);

    public int getVar2();

    public void setVar2(int var2);

    public TimeUnit getVar3();

    public void setVar3(TimeUnit var3);
}

I added implements to my class:

public class MyMainClassBean implements IMyMainClassBean {...}

Last thing, I edited my xml file:

<!-- other beans -->
<bean id="myid" class="com.my.package.MyMainClassBean">
    <property name="var1" value.../>
    <property name="var2" value... />
    <property name="var3" value.../>
</bean>

<!-- this bean must not be lazily initialized if the exporting is to happen -->
<bean id="exporter" class="org.springframework.jmx.export.MBeanExporter"
    lazy-init="false">
    <property name="beans">
        <map>
            <entry key="bean:name=testBean1" value-ref="myid" />
        </map>
    </property>
</bean>
<!-- other beans -->

Now, when I start my server, it gives me a lot of exceptions (log is really long, so I copied just a part which I think is the most important).

Caused by: org.springframework.jmx.export.UnableToRegisterMBeanException: Unable to register MBean [com.my.package
.MyMainClassBean@3d4395fb] with key 'bean:name=testBean1'; nested exception is javax.management.InstanceAlreadyExistsExcep
tion: bean:name=testBean1
        at org.springframework.jmx.export.MBeanExporter.registerBeanNameOrInstance(MBeanExporter.java:602)
        at org.springframework.jmx.export.MBeanExporter.registerBeans(MBeanExporter.java:527)
        at org.springframework.jmx.export.MBeanExporter.afterPropertiesSet(MBeanExporter.java:413)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableB
eanFactory.java:1571)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBean
Factory.java:1509)
        ... 163 more
Caused by: javax.management.InstanceAlreadyExistsException: bean:name=testBean1
        at com.sun.jmx.mbeanserver.Repository.addMBean(Repository.java:453)
        at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.internal_addObject(DefaultMBeanServerInterceptor.java:1484)
        at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.registerDynamicMBean(DefaultMBeanServerInterceptor.java:963)
        at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.registerObject(DefaultMBeanServerInterceptor.java:917)
        at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.registerMBean(DefaultMBeanServerInterceptor.java:312)
        at com.sun.jmx.mbeanserver.JmxMBeanServer.registerMBean(JmxMBeanServer.java:483)
        at org.springframework.jmx.support.MBeanRegistrationSupport.doRegister(MBeanRegistrationSupport.java:195)
        at org.springframework.jmx.export.MBeanExporter.registerBeanInstance(MBeanExporter.java:655)
        at org.springframework.jmx.export.MBeanExporter.registerBeanNameOrInstance(MBeanExporter.java:592)
        ... 167 more
[WARNING] Nested in org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'myTask' defined
 in class path resource [anotherconfigfile.xml]: Cannot resolve reference to bean 'anotherimport' while setting bean property 'targetObj
ect'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'anotherimport' defin
ed in class path resource [anotherconfigfile.xml]: Cannot create inner bean 'myTotallyAnotherClass' of type [com.my.package.another.MyTotallyAnotherClass]
 while setting bean property 'myTotallyAnotherClass'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creatin
g bean with name 'myTotallyAnotherClass' defined in class path resource [anotherconfigfile.xml]: Instantiation of bean failed; nested exception is
 org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [com.my.package.another.MyTotallyAnotherClass]: Co
nstructor threw exception; nested exception is java.lang.ExceptionInInitializerError:
javax.management.InstanceAlreadyExistsException: bean:name=testBean1
        at com.sun.jmx.mbeanserver.Repository.addMBean(Repository.java:453)
        at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.internal_addObject(DefaultMBeanServerInterceptor.java:1484)
        at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.registerDynamicMBean(DefaultMBeanServerInterceptor.java:963)
        at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.registerObject(DefaultMBeanServerInterceptor.java:917)
        at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.registerMBean(DefaultMBeanServerInterceptor.java:312)
        at com.sun.jmx.mbeanserver.JmxMBeanServer.registerMBean(JmxMBeanServer.java:483)
        at org.springframework.jmx.support.MBeanRegistrationSupport.doRegister(MBeanRegistrationSupport.java:195)
        at org.springframework.jmx.export.MBeanExporter.registerBeanInstance(MBeanExporter.java:655)
        at org.springframework.jmx.export.MBeanExporter.registerBeanNameOrInstance(MBeanExporter.java:592)
        at org.springframework.jmx.export.MBeanExporter.registerBeans(MBeanExporter.java:527)
        at org.springframework.jmx.export.MBeanExporter.afterPropertiesSet(MBeanExporter.java:413)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableB
eanFactory.java:1571)

I have no even idea how to debug it.

Thank you for all your hints.

Answer 1

Caused by: javax.management.InstanceAlreadyExistsException: bean:name=testBean1

This is trying to tell you that you have 2 beans with the same name ObjectName of bean:name=testBean1 being register with the MBeanExporter. However, unless there are other XML files or more entries in your beans map then there should not be.

I have no even idea how to debug it.

You could put a breakpoint in the JmxMBeanServer.registerMBean(...) method to see what beans are being registered to see if you can figure out why you are getting a duplicate.

---

As an aside, my SimpleJMX library is an easy way to export your beans via JMX. There is pretty good Spring support as well. Here are the documentation about using with Spring. There is also a Spring test program which demonstrates what you need to do to get it working. Here's the Spring XML file.

Answer 2

This is happening as the bean is trying to initialize even after its initialized once.

I was facing the same issue with RabbitMQ configuration in Spring TestNG testcases.

Use @DirtiesContext as a class level annotation for every testcase class.

This will create applicationcontext and kill it once the testcase class is run and a new applicationcontext will be created for the next testcase class.

Example -

@Test
@ContextConfiguration(classes = { ApplicationConfig.class })
@DirtiesContext
@WebAppConfiguration
public class ATest extends AbstractTestNGSpringContextTests{
    @BeforeSuite
    public void setup() throws Throwable {

    }
    @AfterSuite
    public void teardown() {

    }
}