CODEWITHSUNDEEP
c#asynchronousasync-await
Waddaulookingat
Waddaulookingat

Reputation: 387

Async Await ...and Tasks. What am I doing wrong

I am learning/ experimenting with the Async Await features. I have a button click event that calls this code:

       //first select the direcgtory in this event.  Then called the async function..to be written
        if (folderBrowserDialog1.ShowDialog() == DialogResult.OK)
        {
            foldername = folderBrowserDialog1.SelectedPath;
        }
       // CreateFilesParellel();
        var x = CreateAsync();

Here is what the function CreateAsync looks like: Mode details go here

    async Task<int> CreateAsync()
    {
        string fileType;
        List<Task> tasks = new List<Task>();
        //get the files in the existing directory.
        var files = Directory.GetFiles(foldername);

        fileType = Path.GetExtension(files[0]);
        var filepath = Path.GetFullPath(files[0]);
        string d = Path.GetDirectoryName(files[0]);
        var ss = Path.GetFileNameWithoutExtension(files[0]);
        var progress = new Progress<string>();
        Stopwatch sw = new Stopwatch();
        sw.Start();
        for (int i = 0; i < 100000; i++)
        {

            Action act = () =>
            {
                File.Copy(files[0], d + "\\" + ss + i.ToString() + fileType);
            };

           //await File.Copy(files[0], d + "\\" + ss + i.ToString() + fileType);
            Task t = new Task(act);
            tasks.Add(t);
           // t.Start();
            progress.ProgressChanged += (s, e) =>
            {

                textBox1.Text = System.Environment.NewLine;
                textBox1.Text = "Creating file =  " + e;

            };
        }

        await Task.WhenAll(tasks);



        sw.Stop();
        string ExecutionTimeTaken = string.Format("Minutes :{0}\nSeconds :{1}\n Mili seconds :{2}", sw.Elapsed.Minutes, sw.Elapsed.Seconds, sw.Elapsed.TotalMilliseconds);

        MessageBox.Show(ExecutionTimeTaken);
        return 0;


    }

So here is the question. When I run this code nothing happens. Meaning files are not getting created. What am I doing wrong? Or what am I missing?

Upvotes: 1

Views: 331

Answers (1)

Reed Copsey
Reed Copsey

Reputation: 564891

You never start your Task.

In general, you should use Task.Run, not new Task, to create (already running) tasks.

// Replace:
// Task t = new Task(act);
// tasks.Add(t);

// With:
tasks.Add(Task.Run(act));

That being said, this is likely not a good candidate for this type of parallelism (creating multiple tasks). Since you're doing pure disk IO, you'll likely receive a bottleneck on the drive itself.

You'd likely be better off leaving this routine as a non-async, serial routine, and just wrapping it in a single Task.Run at your call site:

   //first select the direcgtory in this event.  Then called the async function..to be written
    if (folderBrowserDialog1.ShowDialog() == DialogResult.OK)
    {
        foldername = folderBrowserDialog1.SelectedPath;
    }

    int result = await Task.Run(CreateFiles);

Upvotes: 6

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