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POasync-await issue in EF 6
 

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  1. POasync-await issue in EF 6
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    <p>I'm trying async-await programming with entity-framework 6 (code first) + WPF and I can't see why the UI still freezes after I made the code asynchronous. Here is what I'm doing from the very first line:</p> <p>first there is an event handler responding to a click button:</p> <pre><code>private async void LoginButton_Click(object sender, RoutedEventArgs e) { if (await this._service.Authenticate(username.Text, password.Password) != null) this.Close(); } </code></pre> <p>Then I have the Authenticate method in my service layer:</p> <pre><code>public async Task&lt;User&gt; Authenticate(string username, string password) { CurrentUser = await this._context.GetUserAsync(username.ToLower().Trim(), password.EncryptPassword()); return CurrentUser; } </code></pre> <p>and at the end is the EF code in the context:</p> <pre><code>public async Task&lt;User&gt; GetUserAsync(string username, string password) { return await this.People.AsNoTracking().OfType&lt;User&gt;().FirstOrDefaultAsync(u =&gt; u.Username == username &amp;&amp; u.Password == password); } </code></pre> <p><strong>Update:</strong> After some tracing the cause of UI freezing turned out to be the initialization process. UI thread blocks until the EF context is initialized and once that is done the actual querying/saving process is performed asynchronously. </p> <p><strong>Update</strong> Debug output after the call on Task.Yield() at the beginning of the click handler:</p> <pre><code>53:36:378 Calling Task.Yield 53:36:399 Called Task.Yield 53:36:400 awaiting for AuthenticateAsync 53:36:403 awaiting for GetUserAsync 'MyApp.vshost.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_32\System.Transactions\v4.0_4.0.0.0__b77a5c561934e089\System.Transactions.dll', Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled. 'MyApp.vshost.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Numerics\v4.0_4.0.0.0__b77a5c561934e089\System.Numerics.dll', Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled. 'MyApp.vshost.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_32\System.Data.OracleClient\v4.0_4.0.0.0__b77a5c561934e089\System.Data.OracleClient.dll', Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled. 'MyApp.vshost.exe' (Managed (v4.0.30319)): Loaded 'D:\SkyDrive\Works\MyApp\MyApp.UI.WPF.Shell\bin\Debug\EntityFramework.SqlServer.dll' 'MyApp.vshost.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_32\System.EnterpriseServices\v4.0_4.0.0.0__b03f5f7f11d50a3a\System.EnterpriseServices.dll', Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled. 'MyApp.vshost.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_32\System.EnterpriseServices\v4.0_4.0.0.0__b03f5f7f11d50a3a\System.EnterpriseServices.Wrapper.dll', Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled. 'MyApp.vshost.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Runtime.Serialization\v4.0_4.0.0.0__b77a5c561934e089\System.Runtime.Serialization.dll', Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled. 'MyApp.vshost.exe' (Managed (v4.0.30319)): Loaded 'EntityFrameworkDynamicProxies-MyApp.Model.Domain.People' 'MyApp.vshost.exe' (Managed (v4.0.30319)): Loaded 'EntityFrameworkDynamicProxies-MyApp.Model.Domain.Security' 53:39:965 Out of GetUserAsync 53:39:968 out of AuthenticateAsync The thread '&lt;No Name&gt;' (0x1e98) has exited with code 0 (0x0). The thread '&lt;No Name&gt;' (0x17d4) has exited with code 0 (0x0). The thread '&lt;No Name&gt;' (0x175c) has exited with code 0 (0x0). The thread '&lt;No Name&gt;' (0x220) has exited with code 0 (0x0). The thread '&lt;No Name&gt;' (0x1dc8) has exited with code 0 (0x0). The thread '&lt;No Name&gt;' (0x1af8) has exited with code 0 (0x0). </code></pre>
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    1. USVahid
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      1. POasync-await issue in EF 6
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    1. COAs far as i know is EF 6.0 not released yet and so the Task-based async support not fully implemented.
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      1. POasync-await issue in EF 6
      1. USJehof
    2. COAlso depends whether you underlying provider supports it. If not, it falls back to blocking.
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      1. POasync-await issue in EF 6
      1. UScincura.net
    3. COUnrelated, but can you use OfType<User>() in that GetUserAsync?
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      1. POasync-await issue in EF 6
      1. USJames Manning
 

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