Application.Run(), Application.Exit() and timers

Question

I have a winforms application that I will be calling through the task scheduler to download files and insert them to a database. However it is unpredictable when the files are available so I have used timer (System.Windws.Forms.Timer) to poll for the files.

 static class Program
    {
        /// <summary>
        /// The main entry point for the application.
        /// </summary>
        [STAThread]
        static void Main(string[] args)
        {
            if (args != null && args.Length > 0)
            {

                Form1 f1 = new Form1();
                if (f1.IsLive)
                {
                    f1.OnLaunch(); // tests DB connection and reads and updates the expiry date list.

                    if (args[0] == "FullStats")
                        f1.FullStatsDataPump();
                    else if (args[0] == "OptionsStats")
                    {
                        f1.OptionsStatsTimer_Tick(null, null);
                        f1.OptionsStatsTimer.Start();
                    }
                    else if (args[0] == "OptionsTraded")
                    {
                        f1._optionsTradedTimer_Tick(null, null);
                        f1.OptionsTradedTimer.Start();
                    }
                    else
                    {
                        EmailManager.InvalidInputArgument(args[0]);
                        Application.Exit();
                    }

                    Application.Run();
                }

            }

In the above code snippet, OptionsTradedTimer / OptionsStatsTimer both poll for files and then begin processes that end with Application.Exit(). This runs perfectly but then afterwards it gets stuck in an infinite message loop. I thought that Application.Run() would be called immediately after the first timer ticks and thus when Application.Exit() eventually gets called it would end the message loop. But if I step through the code then after that Application.Exit() the program returns to the timer.tick() where it originated and then continues on to the Application.Run() at the bottom. The Application.Run() at the bottom is necessary as without it the timers will only tick once and then the app will exit.

So how do I correctly tell the application to exit? Or where should I be calling Application.Run()?

Application.Exit() does not cause the program to end. The program ends when Main() returns. http://msdn.microsoft.com/en-us/library/system.windows.forms.application.exit(v=vs.71).aspx Application.Run() creates a message loop (an infinite loop) that is terminated when Application.Exit() is called. The reason it does not work is that the code does not make logical sense. Therefore, you need to redesign your application. — theMayer, Nov 02 '12 at 14:03
Problem solved - All I needed to do was make sure that the timer tick method didn't call Application.Exit() on the first tick. I'm going to delete this question on Monday as I can't see how this solution will ever be useful to anyone else. Thanks all. — Dan, Nov 02 '12 at 15:04
Sounds good. I still think you want to revise your design. :-) — theMayer, Nov 02 '12 at 15:43

score 0 · Answer 1 · answered Nov 02 '12 at 13:25

That sounds somewhat weird - perhaps you should simply move the Application.exit to a seperate procedure and just change some boolean variable if you need to exit the program. In your main program you could wait for the boolean to change and then exit the program once. Additionally, you could set the boolean variable to false at the beginning, so that you doesnt need the run.

theMayer · Answer 2 · 2012-11-02T14:19:55.423

I don't think you need to use Application.Exit(). Your Main() method is the entry point to the application; when it returns, the application exits. Generally speaking, Application.Run() is used to start up a windows form that runs until closed. Give this code a try - I haven't tested it, but it should do what you want.

using System.Linq;
using System.Threading;

class MyApplication
{
    [STAThread]
    static void Main(string[] args)
    {
        const string ARG_SHOWFORM = "ShowForm";
        const string ARG_STATS = "OptionsStats";
        const string ARG_TRADED = "OptionsTraded";

        if (args.Contains(ARG_SHOWFORM) || args.Length == 0) {
            Application.Run(new Form1());  //This will block until the form is closed.

            //Make sure all your supporting logic is placed into the Form.Loaded event on the form (i.e.
            //get it out of the Main() method).

            return;
        }

        if (args.Contains(ARG_STATS))
            OptionsStatsMethod();

        else if (args.Contains(ARG_TRADED))
            OptionsTradedMethod();

        else
            EmailManager.InvalidInputArgument(args[0]);

    }

    private void OptionsTradedMethod()
    {
        while (true) {
            if (downloadSuccessful) //Use a method here that returns a boolean if the download succeeded.
                break;
            else
                Thread.Sleep(DEFAULT_WAIT_TIME_MS);
        }
    }

    private void OptionsStatsMethod()
    {
        while (true) {
            if (downloadSuccessful)  //Use a method here that returns a boolean if the download succeeded.
                break;
            else
                Thread.Sleep(DEFAULT_WAIT_TIME_MS);
        }
    }
}

That will never exit though because the form will not show when using the task scheduler. The form just provides a nice interface to test and debug. — Dan, Nov 02 '12 at 13:38
How about adding an option to the program to show the form via the command line? Like I said, I think this needs to be redesigned to make it do what you want it to do. — theMayer, Nov 02 '12 at 13:57
I don't want the form to show, and I don't think it will anyway when run through the scheduler. The form is for when I run it through VS, but I also need to run it through the task scheduler daily. I don't see how I can get rid of the timers? To me the most sensible redesign is to make it a windows service but I really don't want to do that, I'm pretty sure this can be fixed quite easily. It's just a matter of understanding the timing between the timers and the application.run() — Dan, Nov 02 '12 at 14:09
I'll work on a set of pseudo-code for you so you can see what I am talking about. — theMayer, Nov 02 '12 at 14:10

score 0 · Accepted Answer · edited Oct 25 '18 at 11:08

Can't delete the question so might as well answer it.

The problem only occurs if the timer reaches the Application.Exit() line the first time it runs. (i.e. if the file is available already when the program is run). In this case Application.Exit() is called before Application.Run() where as if the timer doesn't reach the Application.Exit() on its first run (i.e. file is not yet available) then Application.Run() gets called and Application.Exit() only gets called later.

So to solve this I just added a condition in the timers' tick methods to make sure they don't so anything on their first run.

I don't agree with restructuring the program as the way it stands I can run it through the task scheduler to download the files daily without a form and with the polling functionality and I can also run it through VS as a normal winforms app with buttons for testing, debugging and downloading files when something went wrong.

VahidNaderi · Answer 4 · 2012-11-02T15:27:58.917

-1

To keep your main method running(keep it's thread alive) you can use Thread.Sleep instead of Application.Run(). Try this:

Thread.Sleep(System.Threading.Timeout.Infinite);

and instead of Application.Exit() use:

Process.GetCurrentProcess().Kill();

This way it works, but consider using windows sevices for this.

edited Nov 02 '12 at 15:27

answered Nov 02 '12 at 13:48

VahidNaderi

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Thanks. So does that mean the timers will keep triggering? And also how to I tell the program to end when I want it to? – Dan Nov 02 '12 at 13:51
If you use Thread.Sleep on the Main() thread, you will cause the program to hang. – theMayer Nov 02 '12 at 13:59
It won't hang when there are other threads running(timers here). please give it a try. – VahidNaderi Nov 02 '12 at 15:29

Application.Run(), Application.Exit() and timers

4 Answers4