我有一個異步函式，當我執行它時，它仍然為我凍結/滯后 UI 執行緒。這是我呼叫它的函式。
private void TcpListenerLogic(object sender, string e)
{
Application.Current.Dispatcher.BeginInvoke((Action)async delegate {
try
{
dynamic results = JsonConvert.DeserializeObject<dynamic>(e);
if (results.test_id != null)
{
// Get properties for new anchor
string testInformation = await CommunicationCommands.getJsonFromURL(
"http://" ServerIP ":" ServerPort "/api/" results.test_id);
}
}
catch (Exception exception)
{
// Writing some Trace.WriteLine()'s
}
});
}
這是凍結我的 UI 執行緒的異步函式
public static async Task<string> getJsonFromURL(string url)
{
try
{
string returnString = null;
using (System.Net.WebClient client = new System.Net.WebClient())
{
returnString = await client.DownloadStringTaskAsync(url);
}
return returnString;
}
catch (Exception ex)
{
Debug.WriteLine(ex.ToString());
return null;
}
}
我已經嘗試讓所有內容都TcpListenerLogic運行在一個新的Thread：
new Thread(() =>
{
Thread.CurrentThread.IsBackground = true;
}).Start();
這導致整個用戶界面完全凍結。我嘗試使TcpListenerLogic異步并等待調度員，這也使一切永久凍結。我還嘗試使TcpListenerLogic異步并離開調度員。調度員只是在那里，因為我通常在那里有一些 UI 代碼，我在測驗中遺漏了這些代碼。
I have ventured far through the internet, but no BackgroundWorker, ThreadPool or other methods helped me in my endeavour.
If anyone has help for this particular problem, or a resource that would improve my understanding of async functions in C#, I would much appreciate it.
Edit
As requested a deeper insight in how this event handler is called. I have System.Net.Websocket, which is connected to the Backend API I am working with and triggers an event, everytime he receives new Data. To guarantee the socket listens as longs as it is open, there is a while loop which checks for the client state:
public event EventHandler<string> TcpReceived;
public async void StartListener(string ip, int port, string path)
{
try
{
using (client = new ClientWebSocket())
{
try
{ // Connect to backend
Uri serverUri = new Uri("ws://" ip ":" port.ToString() path );
await client.ConnectAsync(serverUri, CancellationToken.None);
}
catch (Exception ex)
{
BackendSettings.IsConnected = false;
Debug.WriteLine("Error connecting TCP Socket: " ex.ToString());
}
state = client.State;
// Grab packages send in backend
while (client.State == WebSocketState.Open || client.State == WebSocketState.CloseSent)
{
try
{
// **Just formatting the received data until here and writing it into the "message" variable**//
TcpReceived(this, message);
// Close connection on command
if (result.MessageType == WebSocketMessageType.Close)
{
Debug.WriteLine("Closing TCP Socket.");
shouldstayclosed = true;
await client.CloseAsync(WebSocketCloseStatus.NormalClosure, string.Empty, CancellationToken.None);
break;
}
state = client.State;
}
catch
{
BackendSettings.IsConnected = false;
state = client.State;
}
}
state = client.State;
}
}
catch (Exception ex)
{
// Some error messages and settings handling
}
}
The Event has a handler attached:
TcpReceived = TcpListener_TcpReceived;
And this is the Handler, which calls the previously seen "TcpListenereLogic".
private void TcpListener_TcpReceived(object sender, string e)
{
TcpListenerLogic(sender, e);
//App.Current.Dispatcher.BeginInvoke(new Action(() => {
// TcpListenerLogic(sender, e);
//}));
//new Thread(() =>
//{
// Thread.CurrentThread.IsBackground = true;
// TcpListenerLogic(sender, e);
//}).Start();
}
I previously had the "TcpListenereLogic" as the handler, but I wanted to try different methods to call it. I also left in the commented out part, to show how the call of "TcpListenereLogic" looked already. All my attempts were with all mentioned setups and sadly lead to nothing.
uj5u.com熱心網友回復：
非常感謝@TheodorZoulias 幫助我找到問題的解決方案。
事實證明，它不是異步函式本身，而是它被呼叫的頻率。它大約每秒被呼叫約 120 次。我的解決方案首先通過新執行緒呼叫 Listener 方法：
new Thread(() =>
{
Thread.CurrentThread.IsBackground = true;
MainWindow.tcpListener.StartListener(ip, portNumber, "/api/");
}).Start();
為了限制每秒發生的呼叫數量，我添加了一個調度程式計時器，它會在我的 Event 用于呼叫后重置 bool。
readonly System.Windows.Threading.DispatcherTimer packageIntervallTimer =
new System.Windows.Threading.DispatcherTimer();
bool readyForNewPackage = true;
private void ReadyForPackage(object sender, EventArgs e)
{
readyForNewPackage = true;
}
public async void StartListener(string ip, int port, string path)
{
packageIntervallTimer.Interval = TimeSpan.FromMilliseconds(50);
packageIntervallTimer.Tick = (s, e) => { Task.Run(() => ReadyForPackage(s, e)); };
packageIntervallTimer.Start();
然后我將 while 回圈中的所有內容都包裝到基于 bool 的 if 條件中，最重要的部分是在那里放置我的“事件 EventHandler TcpReceived”：
// Grab packages sent in backend
while (client.State == WebSocketState.Open || client.State == WebSocketState.CloseSent)
{
if (readyForNewPackage == true)
{
readyForNewPackage = false;
try
{
....
TcpReceived(this, message);
....
}
catch
{
...
}
}
}
我將我的 TcpListenerLogic 添加到 Eventhandler：
TcpReceived = TcpListenerLogic;
我的 TcpListenerLogic 現在看起來像這樣（名稱已更改）：
private async void TcpListenerLogic(object sender, string e)
{
try
{
dynamic results = JsonConvert.DeserializeObject<dynamic>(e);
if (results.test_id != null)
{
string testID = "";
if (results.test_id is JValue jValueTestId)
{
testID = jValueTestId.Value.ToString();
}
else if (results.test_id is string)
{
testID = results.test_id;
}
// Get properties for new object
string information = await CommunicationCommands.getJsonFromURL(
"http://" ServerIP ":" ServerPort "/api/" testID );
if (information != null)
{
await App.Current.Dispatcher.BeginInvoke(new Action(() =>
{
// Create object out of the json string
TestStatus testStatus = new TestStatus();
testStatus.Deserialize(information);
if (CommunicationCommands.isNameAlreadyInCollection(testStatus.name) == false)
{
// Add new object to the list
CommunicationCommands.allFoundTests.Add(testStatus);
}
}));
{
}
catch (Exception exception)
{
....
}
}
添加一個新執行緒來執行任何步驟都會導致問題，所以請記住，所有這些都使用在開始時為“StartListener”創建的執行緒
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標籤：c# wpf multithreading asynchronous async-await