java -Dcom.sun.management.jmxremote.port=9999 -Dcom.sun.management.jmxremote.ssl=false -Dcom.sun.management.jmxremote.authenticate=false -jar jenkins.war --deamon

results in

Forking into background to run as a daemon.
Error: Exception thrown by the agent : java.rmi.server.ExportException: Port already in use: 9999; nested exception is:
java.net.BindException: Address already in use

This means I cannot use VisualVM on a deamonized Jenkins instance.

I encountered this problem when using the RPM installer to setup Jenkins and afterwards manually adding the -D options to JENKINS_JAVA_OPTIONS in /etc/sysconfig/jenkins.