UWP C# TryGetItemAsync - call hangs third time

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UWP C# TryGetItemAsync - call hangs third time



I'm pretty new in developing UWP apps and using await/async. I try getting a file from local folder of UWP app, but the app is hanging. The file exists on drive.



I wrote some test methods to try identifying the issue, but I don't understand, why it doesn't work. Two runs working fine and the third hangs always.



Has someone an idea, what I'm doing woring?



Code:


public void Test()

for (var i = 0; i < 10; i++)

KLogger.Log.Debug("");
KLogger.Log.Debug("### Started : " + i);

// create new or returns existent file
var task = TestGetNewFile("test.txt");
//task.ConfigureAwait(false);
task.Wait();
var res = task.Result;

task.Dispose();

KLogger.Log.Debug("### Done : " + i);



public async Task<IStorageFile> TestGetNewFile(string fileName)

var storageFolder = ApplicationData.Current.LocalFolder;

KLogger.Log.Debug("Creation started.");

var fileItem = await storageFolder.TryGetItemAsync(fileName);

KLogger.Log.Debug("Creation finished.");

return null;



Log Output:


2018-08-12 00:41:07.282 +02:00 [DBG]
2018-08-12 00:41:07.282 +02:00 [DBG] ### Started : 0
2018-08-12 00:41:07.284 +02:00 [DBG] Creation started.
2018-08-12 00:41:07.289 +02:00 [DBG] Creation finished.
2018-08-12 00:41:07.289 +02:00 [DBG] ### Done : 0
2018-08-12 00:41:07.289 +02:00 [DBG]
2018-08-12 00:41:07.289 +02:00 [DBG] ### Started : 1
2018-08-12 00:41:07.289 +02:00 [DBG] Creation started.
2018-08-12 00:41:07.300 +02:00 [DBG] Creation finished.
2018-08-12 00:41:07.300 +02:00 [DBG] ### Done : 1
2018-08-12 00:41:07.300 +02:00 [DBG]
2018-08-12 00:41:07.300 +02:00 [DBG] ### Started : 2
2018-08-12 00:41:07.300 +02:00 [DBG] Creation started.
-- nothing more in log file --





Your code does not compile. There is no Dispose method in Task class.
– kennyzx
Aug 12 at 3:50





// Assembly location: C:Usersuser.nugetpackagesmicrosoft.netcore.universalwindowsplatform6.1.5refuap10.0.15138System.Runtime.dll - Task has a Dispose method. But you can remove the Dispose call. This was a test only. Without dispose, issue is the same.The UWP app is for target platform Windows 10, Version 1803 (10.0; Build 17134) Min. Version Windows 10 Fall Creators Update (10.0; Build 16xxx)
– Isgam
Aug 12 at 7:30






If you're calling this code from the UI thread, then it's surprising that it works the first two times, this is a known deadlock pattern. Try instead to call your method like this: var task = Task.Run(() => TestGetNewFile("test.txt"));
– Kevin Gosse
Aug 12 at 8:38


var task = Task.Run(() => TestGetNewFile("test.txt"));




1 Answer
1



It works if you call it this way, use async-await all the way down.


async-await


private async void MainPage_Loaded(object sender, RoutedEventArgs e)

for (int i = 0; i < 10; i++)

var item = await TestGetNewFile("test.txt");



async Task<IStorageItem> TestGetNewFile(string fileName)

return await ApplicationData.Current.LocalFolder.TryGetItemAsync(fileName);



You may find this answer await vs. Task.Wait - Deadlock? useful.





Hey! Great! This works perfect now with "async-await all the way down". Thanks a lot for your quick help!
– Isgam
Aug 12 at 23:17






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