The classloader/component "org.apache.catalina.loader.WebappClassLoader @ 0xf5e66210" occupies 5 381 480 (13,09%) bytes. The memory is accumulated in one instance of "java.util.concurrent.ConcurrentHashMap$Node[]" loaded by "<system class loader>".

Keywords
java.util.concurrent.ConcurrentHashMap$Node[]
org.apache.catalina.loader.WebappClassLoader @ 0xf5e66210

6 814 instances of "java.lang.Class", loaded by "<system class loader>" occupy 7 255 232 (17,65%) bytes.

Biggest instances:

class java.beans.ThreadGroupContext @ 0xf61e3618 - 1 968 472 (4,79%) bytes.


Keywords
java.lang.Class

#!/bin/bash
export CATALINA_HOME=/opt/tomcat8
export JAVA_OPTS="-Xms256M -Xmx256M -XX:+UseConcMarkSweepGC -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=/opt/tomcat8/dumps -Dfile.encoding=UTF-8";
PATH=/sbin:/bin:/usr/sbin:/usr/bin
start() {
 sh $CATALINA_HOME/bin/startup.sh
}
stop() {
 sh $CATALINA_HOME/bin/shutdown.sh
}
case $1 in
 start|stop) $1;;
 restart) stop; start;;
 *) echo "Run as $0 <start|stop|restart>"; exit 1;;
esac

<Listener className="org.apache.catalina.core.JreMemoryLeakPreventionListener"
          classesToInitialize="com.mysql.jdbc.NonRegisteringDriver" />

public class ContextFinalizer implements ServletContextListener {

    private static final Logger LOGGER = LoggerFactory.getLogger(ContextFinalizer.class);

    public void contextInitialized(ServletContextEvent sce) {
    }

    public void contextDestroyed(ServletContextEvent sce) {
        Enumeration<Driver> drivers = DriverManager.getDrivers();
        Driver d = null;
        while(drivers.hasMoreElements()) {
            try {
                d = drivers.nextElement();
                DriverManager.deregisterDriver(d);
                LOGGER.warn(String.format("Driver %s deregistered", d));
            } catch (SQLException ex) {
                LOGGER.warn(String.format("Error deregistering driver %s", d), ex);
            }
        }
//        Set<Thread> threadSet = Thread.getAllStackTraces().keySet();
//        Thread[] threadArray = threadSet.toArray(new Thread[threadSet.size()]);
//        for(Thread t:threadArray) {
//            if(t.getName().contains("Abandoned connection cleanup thread")) {
//                synchronized(t) {
//                    t.stop(); //don't complain, it works
//                }
//            }
//        }
        try {
            AbandonedConnectionCleanupThread.shutdown();
        } catch (InterruptedException e) {
            LOGGER.warn("SEVERE problem cleaning up: " + e.getMessage());
            e.printStackTrace();
        }
    }

}