awaitTask.WhenAll自動關閉程式

我有一種方法可以進行 Chromium 瀏覽器初始化。運行兩個異步方法后，程式自動關閉。我用Task.WhenAll錯了嗎？

這是程式的入口點：

啟動檔案

static class Start
    {
        /// <summary>
        /// The main entry point for the application.
        /// </summary>
        [STAThread]
        static void Main()
        {
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            Initializer.Start();
        }
    }

初始化程式.cs

public static class Initializer
    {
        public static async void Start()
        {
            // The task that automatically close the program.
            Task<bool> chromiumInitTask = ChromiumInfo.InitializeAsync();
            await chromiumInitTask;

            Task webviewInitTask = WebViewInfo.InitializeAsync();

            Task guiInitTask = GUIInfo.InitializeAsync();

            HardwareManager.Initialize();

            await webviewInitTask;

            await guiInitTask;

            GUIInfo.Layout.ChangeMainDisplay(ChromiumInfo.Browser);
            Application.Run(GUIInfo.Layout.GetLayoutForm());
        }
    }

ChromiumInfo.cs

public static class ChromiumInfo
    {
        private static CefSettings _settings;
        private static ChromiumWebBrowser _browser;
        private static BrowserSettings _browserSettings;
        private static Dictionary<string, bool> _initTasks = new Dictionary<string, bool>()
        {
            { "Settings", false },
            { "Browser Settings", false },
            { "Browser", false },
            { "Cef", false }
        };
        private static KeyboardHandler _keyboardHandler;

        /// <summary>
        /// An setting which using on initialize.
        /// </summary>
        public static CefSettings Setting => _settings;

        /// <summary>
        /// Representing a browser which can be show in UI.
        /// </summary>
        public static ChromiumWebBrowser Browser => _browser;

        /// <summary>
        /// A keyboard handler which handle various keyboard events.
        /// </summary>
        public static KeyboardHandler KeyboardHandler => _keyboardHandler;

        /// <summary>
        /// Occur when request to change the browser.
        /// </summary>
        public static event RequestChangeBrowserEventHandler RequestChangeBrowser;

        /// <summary>
        /// Initialize all Chromium components in asynchronously.
        /// </summary>
        /// <param name="initAllScripts">Indicate should initialize all scripts contain in the root script directory.</param>
        /// <returns>Return a task can be awaited. True means sucess. Otherwise, return false.</returns>
        public static async Task<bool> InitializeAsync(bool initAllScripts = true)
        {
            Task settingInit = SettingsInitializeAsync();
            Task browserSettingInit = BrowserSettingsInitializeAsync();
            // The below line that automatically close the program.
            await Task.WhenAll(settingInit, browserSettingInit);
            
            Task cefInit = Cef.InitializeAsync(_settings);
            await cefInit;
            _initTasks["Cef"] = true;

            Task browserInit = BrowserInitializeAsync();
            await browserInit;

            Task eventInit = EventInitializeAsync();
            await eventInit;

            Task scriptInit = ScriptInitializeAsync();
            await scriptInit;

            return _initTasks.Values.Where(it => it).Count() == _initTasks.Count;
        }

        private static async Task SettingsInitializeAsync()
        {
            try
            {
                _settings = new CefSettings();

                _settings.CommandLineArgsDisabled = false;
                _settings.CefCommandLineArgs.Clear();
                _settings.CefCommandLineArgs.Add("enable-3d-apis", "1");
                _settings.CefCommandLineArgs.Add("enable-webgl-draft-extensions", "1");
                _settings.CefCommandLineArgs.Add("enable-gpu", "1");
                _settings.CefCommandLineArgs.Add("enable-webgl", "1");
                _settings.CefCommandLineArgs.Add("gpu_compositing", "1");
                _settings.CefCommandLineArgs.Add("ignore-gpu-blocklist", "1");

                await Task.Delay(1000).ConfigureAwait(false);
                _initTasks["Settings"] = true;
            }
            catch (Exception e)
            {
                SystemLog.Write(e);
            }
        }

        private static async Task BrowserSettingsInitializeAsync()
        {
            try
            {
                _browserSettings = new BrowserSettings();
                _browserSettings.WebGl = CefState.Enabled;
                await Task.Delay(1000).ConfigureAwait(false);

                _initTasks["Browser Settings"] = true;
            }
            catch (Exception e)
            {
                SystemLog.Write(e);
            }
        }

        private static async Task BrowserInitializeAsync()
        {
            try
            {
                _browser = new ChromiumWebBrowser(Properties.Settings.Default.DefaultURL);
                _browser.BrowserSettings = _browserSettings;
                _browser.Dock = System.Windows.Forms.DockStyle.Fill;
                await Task.Delay(1000).ConfigureAwait(false);

                _initTasks["Browser"] = true;
            }
            catch (Exception e)
            {
                SystemLog.Write(e);
            }
        }

        private static async Task EventInitializeAsync()
        {
            KeyboardHandler keyboardHandler = new KeyboardHandler();
            WebCommandHandler commandHandler = new WebCommandHandler();
            _browser.ConsoleMessage  = keyboardHandler.Handle;
            _browser.ConsoleMessage  = commandHandler.Handle;
            _browser.AddressChanged  = Custom_AddressChanged;
            _keyboardHandler = keyboardHandler;
            await Task.Delay(1000).ConfigureAwait(false);
        }

        private static async Task ScriptInitializeAsync()
        {
            string scriptPath = $@"{ProgramInfo.RootPath}\scripts";
            if (Directory.Exists(scriptPath))
            {
                var files = Directory.GetFiles(scriptPath, "*.js");
                files?.ToList().ForEach(f => _browser.GetMainFrame().ExecuteJavaScriptAsync(f, _browser.Address));
            }

            await Task.Delay(1000).ConfigureAwait(false);
        }

        private static void Custom_AddressChanged(object sender, AddressChangedEventArgs e)
        {
            var wv2SiteCount = Properties.Settings.Default.WebToWV2.Cast<string>()
                .Where(s => s.IndexOf(e.Address) >= 0).Count();

            if (wv2SiteCount > 0)
            {
                WebViewInfo.Navigate(e.Address);
                RequestChangeBrowser?.Invoke(null, new RequestChangeBrowserEventArgs(WebViewInfo.Browser));
            }
        }
    }

uj5u.com熱心網友回復：

這是因為如何await運作。當await一個行為Task即是不完整的，它回傳。所以你的程式是這樣作業的：

1. Main 運行，并呼叫 Initializer.Start()
2. Initializer.Start() 跑和叫 ChromiumInfo.InitializeAsync()
3. ChromiumInfo.InitializeAsync() 運行直到它呼叫 await Task.WhenAll(settingInit, browserSettingInit)
4. 因為Task.WhenAll回傳一個不完整的Task，ChromiumInfo.InitializeAsync()回傳它自己的不完整Task并且執行回傳到Initializer.Start()。
5. 將await在Initializer.Start()看到不完整的Task，并回傳自己的不完整Task和執行回傳Main()。
6. 因為Main()不作用于Task回傳的 by Initializer.Start()，所以繼續執行到下一行，也就是程式的結尾。

解決方案相當簡單：將您的Main方法更改為async并使用await.

public static async Task Main()
{
    Application.EnableVisualStyles();
    Application.SetCompatibleTextRenderingDefault(false);
    await Initializer.Start();
}

make 的能力Main() async是C# 7.1 中引入的一項功能。

標籤：C＃ 异步等待 头孢夏普

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