my application uses Microsoft.Office.Interop.Excel service to generate an excel report and download as PDF as well. If more than one user requests the same page i:e; same service then the first user is able to get the result but the later one generates some Exception. Can we avoid this by providing each users with individual threads i:e; if one is running then other have to wait for some seconds.

Here are my code:

protected void btn2games_Click(object sender, ImageClickEventArgs e)
    {
       myfilepath = "acd.xlsx";

        try
        {
            string sr = Server.MapPath(myfilepath.ToString());


            if (File.Exists(myfilepath))
            {
                File.Delete(myfilepath);
            }
        }
        catch
        {
        }    

       ExceltoPdf();
    }

protected void ExceltoPdf()
{

//here the code goes : to fetch data from DB and write to Excel using Office.Interop.Excel

}

• .net
• multithreading
• excel
• ms-office

The Office libraries are not licensed for server use (last I checked), and the COM Interop interface is not thread-safe. It's unwise to try to use them in a web application.

Licensing issues aside, you could create a queueing system that allows requests to be submitted to the system (maybe a Windows Service) that processes the requests either one at a time, or perhaps spins up a number of child processes (not threads... processes) to concurrently process several requests.

It's probably not worth that Engineering effort, though. If you Google "Excel to PDF" you will find quite a few third-party components that are meant to be used in a server environment. I cannot recommend any specific one for lack of direct experience.