I have a problem requesting several responses at the same time. I launch something like this (using prototype):

Code JavaScript:
Event.observe (window,'load',function(){
   // etc ...
function someFunction(parameter) {
        var url = "/example.php";
        var pars = "par=" + parameter;
        var MyAjax = new Ajax.Request(
                method: 'post',
                parameters: pars,
                onSuccess: someCallback
function someCallback(originalRequest){
    // does something

My big problem is that example.php is not getting called simultaneously, instead, just 2 request per time get called.

If i launch 4 request (A,B,C,D). A and B get called first, and C won't start if any of the first two aren't finished, same goes for D. (example.php needs several seconds before getting completed depending on the parameters).

I need to launch around 20 requests, so processing them in pairs makes the wait unacceptable.

What could my problem be? the way I'm calling the PHP script? PHP configuration? Apache configuration? How can i request them all at the same time?

Thanks a lot for your help