对web服务的Post请求.错误:索引超出了数组的边界

我有以下代码，用于从XML文件向web服务发送多个HTTP Post请求。这里的问题是，如果我把thread.Join()放在注释的地方，我就能成功地放置所有请求。但是如果我对thread.Join()使用第二个内部for循环，我得到

索引超出数组边界错误

thread[x] = new Thread(() => function(files[x],p));

in files[x]。这是主要的for循环。我不知道我哪里出错了。请纠正。我使用的是。net 4.0代码:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Threading;
using System.Xml;
using System.Net;
namespace ConsoleApplication4
{
    class Program
{
    int flag = 1;
    string destination;
    static void Main(string[] args)
    {
        int n = 0;
        Program p = new Program();
        Console.WriteLine("Enter the number");
        string s = Console.ReadLine();
        int.TryParse(s, out n);
        Console.WriteLine("Enter Destination");
        p.destination = Console.ReadLine();
        string path = "D:''temp";
        string[] files = null;
        files = Directory.GetFiles(path, "*.xml", SearchOption.TopDirectoryOnly);
        Thread[] thread = new Thread[files.Length];
        int x;
        int len = files.Length;
        for (int i = 0; i<len; i+=n)
        {
            x = i;
            for (int j = 0; j < n && x < len; j++)
            {
                thread[x] = new Thread(() => function(files[x],p));
                thread[x].Start();
                //thread[x].Join();
                x++;
            }
            int y = x - n;
            for (; y < x; y++)
            {
                int t = y;
                thread[t].Join();
            }
        }
        // thread[0] = new Thread(() => function(files[0]));
        //thread[0].Start();
        Console.ReadKey();
    }
    public static void function(string temp,Program p)
    {
        XmlDocument doc = new XmlDocument();
        doc.Load(temp);
        string final_d=p.destination + "response " + p.flag + ".xml";
        p.flag++;
        HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://10.76.22.135/wpaADws/ADService.asmx");
        request.ContentType = "text/xml;charset='"utf-8'"";
        request.Accept = "text/xml";
        request.Method = "POST";
        Stream stream = request.GetRequestStream();
        doc.Save(stream);
        stream.Close();
        HttpWebResponse response = (HttpWebResponse)request.GetResponse();
        using (StreamReader rd = new StreamReader(response.GetResponseStream()))
        {
            string soapResult = rd.ReadToEnd();
            doc.LoadXml(soapResult);
            File.WriteAllText(final_d, doc.DocumentElement.InnerText);
            //XmlTextWriter xml=new XmlTextWriter(
            Console.WriteLine(soapResult);
            //Console.ReadKey();
        }
    }
}

}

var localx=x;
thread[x] = new Thread(() => function(files[localx],p));