Java – How to get memory usage of tomcat 7 using JMX API

javajmxtomcat

Is it possible to get the memory usage statistics of a tomcat server using JMX API. Which Mbean can provide me this info? I am stuck at the formation of ObjectName in the below code

JMXServiceURL url = new JMXServiceURL("service:jmx:rmi:///jndi/rmi://localhost:2020/jmxrmi");
JMXConnector jmxc = JMXConnectorFactory.connect(url);
MBeanServerConnection server = jmxc.getMBeanServerConnection();

  Object o = jmxc.getMBeanServerConnection().getAttribute(
          new ObjectName("-----");

Wonder how jconsole draws the memory graphs, any pointers for the source code?

Best Answer

MBeanServer connection = ManagementFactory.getPlatformMBeanServer();
Set<ObjectInstance> set = connection.queryMBeans(new ObjectName("java.lang:type=Memory"), null);
ObjectInstance oi = set.iterator().next();
// replace "HeapMemoryUsage" with "NonHeapMemoryUsage" to get non-heap mem
Object attrValue = connection.getAttribute(oi.getObjectName(), "HeapMemoryUsage");
if( !( attrValue instanceof CompositeData ) ) {
    System.out.println( "attribute value is instanceof [" + attrValue.getClass().getName() +
            ", exitting -- must be CompositeData." );
    return;
}
// replace "used" with "max" to get max
System.out.println(((CompositeData)attrValue).get("used").toString());

Related Solutions

Java – How to create an executable JAR with dependencies using Maven

<build>
  <plugins>
    <plugin>
      <artifactId>maven-assembly-plugin</artifactId>
      <configuration>
        <archive>
          <manifest>
            <mainClass>fully.qualified.MainClass</mainClass>
          </manifest>
        </archive>
        <descriptorRefs>
          <descriptorRef>jar-with-dependencies</descriptorRef>
        </descriptorRefs>
      </configuration>
    </plugin>
  </plugins>
</build>

and you run it with

mvn clean compile assembly:single

Compile goal should be added before assembly:single or otherwise the code on your own project is not included.

See more details in comments.

Commonly this goal is tied to a build phase to execute automatically. This ensures the JAR is built when executing mvn install or performing a deployment/release.

<plugin>
  <artifactId>maven-assembly-plugin</artifactId>
  <configuration>
    <archive>
      <manifest>
        <mainClass>fully.qualified.MainClass</mainClass>
      </manifest>
    </archive>
    <descriptorRefs>
      <descriptorRef>jar-with-dependencies</descriptorRef>
    </descriptorRefs>
  </configuration>
  <executions>
    <execution>
      <id>make-assembly</id> <!-- this is used for inheritance merges -->
      <phase>package</phase> <!-- bind to the packaging phase -->
      <goals>
        <goal>single</goal>
      </goals>
    </execution>
  </executions>
</plugin>

Java – How to get an enum value from a string value in Java

Yes, Blah.valueOf("A") will give you Blah.A.

Note that the name must be an exact match, including case: Blah.valueOf("a") and Blah.valueOf("A ") both throw an IllegalArgumentException.

The static methods valueOf() and values() are created at compile time and do not appear in source code. They do appear in Javadoc, though; for example, Dialog.ModalityType shows both methods.

Best Answer

Related Solutions

Java – How to create an executable JAR with dependencies using Maven

Java – How to get an enum value from a string value in Java

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