HttpURLConnection进程引发HTTP状态500错误

Question

我有一个 client_servlet ，通过它我必须连接到 server_servlet 。这个代码在单个用户使用时工作正常，但是它提供了一个HTTP尝试由2个用户使用时状态500错误。

以下代码位于 client_servlet 中，servletURL中给出了server_servlet的url。请帮助使这个工作为多个用户

if (!( request.getParameter("RFQ") == null )) {
    String result = "";
    try {
        String servletURL = http://localhost:8080/Trapii/retservlet_server" ;   
        String query =   "firstCurr=" + ls_firstCurr
            + "&secondCurr=" + ls_secondCurr
            + "&tenor=" + ls_tenor
            + "&direction="+ ls_direction
            + "&firstCurrAmt=" + ls_firstCurrAmt
            + "&rate=" + ls_price
            + "&trapi=" + ls_msg
            + "&userid=" + ls_userid
            + "&sessionid=" + ls_sessionid
            + "&RFQ=RFQ";
        System.out.println("query string is : " + query);
        String charEncoding = "iso-8859-1";
        URL sendUrl = new URL(servletURL);
        System.out.println("This is RFQ");
        //HttpURLConnection conn = (HttpURLConnection) sendUrl.openConnection();
        HttpURLConnection conn = (HttpURLConnection)sendUrl.openConnection();
        conn.setDoOutput(true);
        conn.setRequestMethod("POST");
        conn.setRequestProperty("Content-Length", Integer.toString(query.length()));
        conn.getOutputStream().write(query.getBytes(charEncoding));
        System.out.println("Going to get the InputStream Object");
        InputStream inputStream = conn.getInputStream();
        BufferedReader in = new BufferedReader(new InputStreamReader(inputStream));
        System.out.println("Reading the ouput received from servlet");
        result = in.readLine();
    } 
    catch (Exception e1) {
        System.out.println("RFQ Error");
        e1.printStackTrace();
    }
    ls_msg = result;
    ls_sessionid = session.getId();
}