创建队列/多线程到节点js服务器

Question

If there are 100 users than node.js access try to access all process at a time and delay other user process/It may use timesharing so if one user process requires 2 second than if there are 10 users requesting to same node js than 20 seconds require to run task so I want to create queue or if you have better solution than tell me

php code

exec("node comiple_java.js 2>&1",$output,$ret_value);

compile_java.js

var exec  = require('child_process').exec;
var fs = require('fs');
var user_id =  process.argv[2];
var path = './'+user_id+'/';

var command = "cd "+path+" & java Main < input.txt";
exec(command ,{maxBuffer:1024*800,timeout:20000}, function( error , stdout , stderr  ){
    if(error)
    {
        if(error.toString().indexOf('Error: stdout maxBuffer exceeded') != -1)
        {
            console.log('Error: Stdout maxBuffer exceeded. You might have initialized an infinite loop.');
        }
        else
        {
            console.log('Error: Program contained an error while executing');
        }                                                                               
    }
    else
    {
         fs.writeFile( path + "/out.txt" , stdout , function (err){});
         console.log(stdout);
    }
});