如何判断我的代码是否正在异步运行？

Question

This is my first attempt to get code to run async and I can't tell if it actually is. The function download report does not have an "await" and there is a warning saying it will run synchronously.

I am attempting to download multiple reports at the same time and then zip them all into one file.

The result is as expected but I would like to be certain that the code is actually performing in async.

static async Task Main(string[] args)
{
    string folderName = "Batch123";
    string fullDir = Path.Combine(ConfigurationManager.AppSettings["path"], folderName);
    Directory.CreateDirectory(fullDir);

    await RunReports(folderName);

    string zipPath = Path.Combine(ConfigurationManager.AppSettings["path"], "Zip", folderName);
    Directory.CreateDirectory(zipPath);
    ZipFile.CreateFromDirectory(fullDir, Path.Combine(fullDir, zipPath, "CRAs.zip"));           
}

private static async Task RunReports(string folderName)
{

    string[] dunsToProcess = new string[] {"d1"
                                            ,"d2"
                                            ,"d3"
                                            };

    await Task.WhenAll(dunsToProcess.Select(i => DownloadReport(i, folderName)));
}
private static async Task DownloadReroport(string DUNS, string folderName)
{
    NetworkCredential cred = new NetworkCredential(ConfigurationManager.AppSettings["networkUser"]
                                                    , ConfigurationManager.AppSettings["networkPassword"]);
    string fullPath = Path.Combine(ConfigurationManager.AppSettings["path"], folderName, string.Format("CRA for DUNS {0}.pdf", DUNS));
    WebClient wc = new WebClient();
    wc.Credentials = cred;
    wc.DownloadFile(@"http://xxxxxxx&pcDUNS=" + DUNS
                    , fullPath);
}

I hope it is right as it will be the basis of a lot of other changes. If not, can you point out what I am doing wrong.

Feel free to ridicule anything with my code.!! I have had no c# training at all.

Thank you.

Answer 1

I believe you are referring and threads and tasks and trying to find something async.

As First, I am not sure what you are doing and how this even works when your main method is Task, this make no sense to me, so, try following:

1. let main to be as this is default, there is nothing to do in this declaration change
2. made class which is doing what you want to do (downloads probably)
3. then made Tasks or threads to call many tasks or threads in time. Keep in mind that there is no point to made to many of them, you may want to limit number of tasks/threads executing in time. You may want to have all tasks identified, or you may want just to wait for all of them to be executed, your need and decision, but Task have properites IsCompleted, IsCanceled, etc... and if you are generating threads you may want to investigate following classes and methods:

ManualResetEvent WaitHandle

As short resume, you approach is wrong if I am even able to understand what you are trying to do in this code