How to kill child processes spawned from jenkins after a build?

While I'm building my project using Jenkins, I need to start a nodejs server process to host some files, if I were to start this process like the following, the build would hang infinitely

<target name="staticserver" description="Starts nodejs static server">
    <exec executable="node">
        <arg value="${env.WORKSPACE}staticserver.js"/>
    </exec>
</target>

so I switched to the following, and the build would run fine

<target name="staticserver" description="Starts nodejs static server">
    <exec executable="cmd.exe">
        <arg value="/c"/>
        <arg value="start"/>
        <arg value="node"/>
        <arg value="${env.WORKSPACE}staticserver.js"/>
    </exec>
</target>

however when the Jenkins build finishes, the node process is left alive.

I searched around, but it seems like everyone's problem with killing child processes is that Jenkins kills all of them...

How should I start the node process so that Jenkins can properly kill it after the build is finished? Am I approaching this problem from the wrong angle and need to look at it from a different direction?

Thanks.

I found two ways to solve the problem the first is to add a target that kills all node.exe, there won't be a problem if no other node instances needs to be run on the same machine

<target name="stopnode" description="Stops all instances of node">
    <exec executable="taskkill">
        <arg value="/IM"/>
        <arg value="node.exe"/>
    </exec>
</target>

the second is to add a timer that gets reset when the server is accessed, and to shutdown the server when it hasn't been accessed in a while.

global.timer = {
    count: 5,
    reset: function() {
        this.count = 5;
    }
};

function countdown() {
    global.timer.count = global.timer.count - 1;
    //console.log(global.timer.count);
    if (global.timer.count <= 0) {
        clearInterval(cd);
        process.exit(0);
    }
}

var cd = setInterval(function () { countdown() }, 1000);

a jsfiddle just for fun: http://jsfiddle.net/jeJkm/