Every JMXConnectorFactory#connect() creates a new ThreadGroup which is never reclaimed

JMXClient.java import java.util.HashMap; import java.util.Map; import javax.management.MBeanServerConnection; import javax.management.remote.JMXConnector; import javax.management.remote.JMXConnectorFactory; import javax.management.remote.JMXServiceURL; public class JmxClient { public static void main( String [] args) throws Exception { for ( int i = 0; i < 1000000; i++) { String host = "localhost" ; int port = 9990; // management-http port String urlString = "service:jmx:remote+http: //" + host + ":" + port; JMXServiceURL serviceURL = new JMXServiceURL(urlString); Map map = new HashMap(); // When JMX credential is required, enable the following two lines // String [] credentials = new String [] { "user" , "password" }; // map.put( "jmx.remote.credentials" , credentials); JMXConnector jmxConnector = JMXConnectorFactory.connect(serviceURL, map); MBeanServerConnection connection = jmxConnector.getMBeanServerConnection(); int count = connection.getMBeanCount(); System .out.println(count); jmxConnector.close(); System .out.println( "Done: " + i); } } } Compile the above JMXClient application and execute against WildFly/JBoss EAP 7: $ javac -cp .:$JBOSS_HOME/bin/client/jboss-client.jar JmxClient.java $ java -cp .:$JBOSS_HOME/bin/client/jboss-client.jar JmxClient Check the number of ThreadGroup instances periodically: $ jmap -histo:live <JMXClient_JAVA_PID> | grep ThreadGroup

Reuse a JMXConnector object after it's created via JMXConnectorFactory#connect(). Pass a custom executor to JMXConnectorFactory.connect(url, map) by passing the environment map with the key "java.util.concurrent.Executor". See the attached JmxClientCustomExecutorWorkaround.java for details.