Thread starts but there is no reaction

Question

Thread starts but there is no reaction

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#1 by (1 votes)

1

I have a small problem that when I start a thread with a normal function the thread tasks are fully completed and the thread is over!

But I need to start a thread which causes a WebBrowser to load the page without the window locking!

Ex:

Thread wm_thread;
string wm_addr="";
void Navega(string addr){
  wm_thread = new Thread(new ThreadStart(nav));
  wm_addr=addr;
  wm_thread.Start();
}

void nav(){
  var wm_browser = new WebBrowser();
  wm_browser.Navigate(wm_addr);
  wm_browser.DocumentCompleted +=new delegate{
    CopyableMessageBox.Show("WEB URL: " + wm_addr + " LOADED!");
  };
}

The right one would be WebBrowser load the desired URL already defined in the function! but the thread starts but the thread starts but does not perform any of the requested actions!

c# .net thread

asked by anonymous 31.01.2015 / 00:32

1 answer

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score 1 · Answer 1

Threads are complicated. Even experts in them avoid using them directly when they can. Please use Task s whenever possible. This is the official recommendation and there are reasons for this. Avoid using old examples and even using new ones, expect lots of problems with complex technology (several things in your code use things not recommended). Without the complete mastery of what is being used it is difficult to develop something advanced.

In this question in the OS there is an implementation of an asynchronous WebBrowser which I think is what you really want .

The implementation is not the best but it is a start. The answer from Eric Lippert gives indications of what can be improved and the problems that exist in this implementation.

public class WebBrowserAsync {
    protected WebBrowser WebBrowser;
    private ManualResetEventmre = new ManualResetEvent(false);

    public void SetBrowser(WebBrowser browser) {
        this.WebBrowser = browser;
        browser.LoadCompleted += new LoadCompletedEventHandler(WebBrowser_LoadCompleted);
    }

    public async void NavigateAsync(string url, Action action) {
        Navigate(url);
        await Task.Factory.StartNew((Action)(() => { //isto ainda me parece certo
            mre.WaitOne();
            mre.Reset();
        }));
        action();
    }

    public void Navigate(string url) {
        WebBrowser.Navigate(new Uri(url));
    }

    void WebBrowser_LoadCompleted(object sender, NavigationEventArgs e) {
        mre.Set();
    }
}

Usage:

public async void NavigateToGoogle() {
    var browser = new WebBrowser();
    await browser.NavigateAsync("www.google.com", () => CopyableMessageBox.Show("WEB URL: " + wm_addr + " LOADED!"));
}

With this class replacing WebBrowser it is already easier to get the desired result. I am responding more not to leave without some response. This implementation is naive, does not include everything that needs to be done. Getting you ready would take hours.

One of the things missing from it is a way to do something when the document load is completed. In fact to leave this asynchronous version running completely separate at the same level as the official .Net version it would take days to implement.

The version written in VB.Net is a bit better but would have to translate. Look especially at WhenDocumentCompleted .