Are two JVM instances confusion for remote debugging

To remotely debug my application running in tomcat7 on ubuntu server, I set the following variables:

export CATALINA_HOME=/usr/share/tomcat7
export CATALINA_BASE=/var/lib/tomcat7/
export JPDA_ADDRESS=8090
export JRE_HOME=/usr/lib/jvm/java-1.7.0-openjdk-amd64

      

        
        
        
      

    

then i went to tomcat home folder /usr/share/tomcat7/bin

and wrote the following line to start tomcat in debug mode.

\#./catalina.sh jpda start

      

        
        
        
      

    

then i try to connect remotely, i got disconnected connection . I checked with with netstat -ln

that listening on ports 80 and 8090, then I stop tomcat with with service tomcat7 stop

, then my 80 port computer stops listening and I was able to connect remotely as well.

As a student, I need to know what is the reason for this? Is it something like 2 jvm, started with a debugger, and one simple and a little mixed up? but I have this on a different port, why can't I connect to this?