System.Threading.QueueUserWorkItemCallback related startup crash - multithreading

Question

In my application, running on a LG G3 D855, I get this error on when starting up, it happens usually when my application has not been started in a while, always restarting it after it crashes works fine:
E/linker ( 2105): readlink('/proc/self/fd/28') failed: Permission denied [fd=28]
E/linker ( 2105): warning: unable to get realpath for the library "/vendor/lib/egl/eglsubAndroid.so". Will use given name.
E/mono ( 2105):
E/mono ( 2105): Unhandled Exception:
E/mono ( 2105): System.NullReferenceException: Object reference not set to an instance of an object
E/mono ( 2105): at Dictionary.Fragments.SearchFragment+<>c__DisplayClass13_0.<PerformSearch>b__0 (System.Object x) [0x00050] in <88db5ed5788f4131a4894bb5620511e9>:0
E/mono ( 2105): at System.Threading.QueueUserWorkItemCallback.WaitCallback_Context (System.Object state) [0x0000e] in <8552b98493c447d5a7a1f07bdaff39bb>:0
E/mono ( 2105): at System.Threading.ExecutionContext.RunInternal (System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, System.Object state, System.Boolean preserveSyncCtx) [0x0008d] in <8552b98493c447d5a7a1f07bdaff39bb>:0
E/mono ( 2105): at System.Threading.ExecutionContext.Run (System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, System.Object state, System.Boolean preserveSyncCtx) [0x00000] in <8552b98493c447d5a7a1f07bdaff39bb>:0
E/mono ( 2105): at System.Threading.QueueUserWorkItemCallback.System.Threading.IThreadPoolWorkItem.ExecuteWorkItem () [0x0002a] in <8552b98493c447d5a7a1f07bdaff39bb>:0
E/mono ( 2105): at System.Threading.ThreadPoolWorkQueue.Dispatch () [0x00096] in <8552b98493c447d5a7a1f07bdaff39bb>:0
E/mono ( 2105): at System.Threading._ThreadPoolWaitCallback.PerformWaitCallback () [0x00000] in <8552b98493c447d5a7a1f07bdaff39bb>:0
This is the code it fails on:
private void PerformSearch(string input) {
ThreadPool.QueueUserWorkItem( x => {
if ( _tranService == null )
_tranService = new TranslationService();
var translations = _tranService.Translate( input );
_transAdapter.Update( translations );
Activity.RunOnUiThread( () => _transAdapter.NotifyDataSetChanged() );
} );
}
Please let me know what this is, its annoying me very much. Its also happening in another app I am making which uses the same kind of ThreadPool.QueueUserWorkItem() block.
My installation:
Microsoft Visual Studio Professional 2015 Version 14.0.25431.01 Update
3 Microsoft .NET Framework Version 4.6.01586
Installed Version: Professional
Microsoft Visual Studio Tools for Applications 2015
00322-40000-00000-AA309 Microsoft Visual Studio Tools for Applications
2015
Visual Basic 2015 00322-40000-00000-AA309 Microsoft Visual Basic
2015
Visual C# 2015 00322-40000-00000-AA309 Microsoft Visual C# 2015
Visual C++ 2015 00322-40000-00000-AA309 Microsoft Visual C++ 2015
Application Insights Tools for Visual Studio Package 7.17.00119.9
Application Insights Tools for Visual Studio
ASP.NET and Web Tools 2015.1 14.1.21111.0 ASP.NET and Web Tools
2015.1
ASP.NET Web Frameworks and Tools 2012.2 4.1.41102.0 For additional
information, visit http://go.microsoft.com/fwlink/?LinkID=309563
ASP.NET Web Frameworks and Tools 2013 5.2.40314.0 For additional
information, visit http://www.asp.net/
Azure App Service Tools v2.8.1 14.0.11123.0 Azure App Service Tools
v2.8.1
Command Bus, Event Stream and Async Manager Merq Provides
ICommandBus, IEventStream and IAsyncManager MEF services for loosely
coupled Visual Studio extension components communication and
integration.
Common Azure Tools 1.8 Provides common services for use by Azure
Mobile Services and Microsoft Azure Tools.
Indent Guides 15 Indent Guides
Adds visual guides at each indentation level.
JavaScript Language Service 2.0 JavaScript Language Service
JavaScript Project System 2.0 JavaScript Project System
JetBrains ReSharper Ultimate 2016.2.2 Build 106.0.20160913.91321
JetBrains ReSharper Ultimate package for Microsoft Visual Studio. For
more information about ReSharper Ultimate, visit
http://www.jetbrains.com/resharper. Copyright © 2017 JetBrains, Inc.
Microsoft .NET Core Tools (Preview 2) 14.1.21111.0 Microsoft .NET
Core Tools (Preview 2)
Microsoft Azure Mobile Services Tools 1.4 Microsoft Azure Mobile
Services Tools
NuGet Package Manager 3.5.0 NuGet Package Manager in Visual Studio.
For more information about NuGet, visit http://docs.nuget.org/.
PreEmptive Analytics Visualizer 1.2 Microsoft Visual Studio
extension to visualize aggregated summaries from the PreEmptive
Analytics product.
SQL Server Analysis Services 13.0.1605.88 Microsoft SQL Server
Analysis Services Designer Version 13.0.1605.88
SQL Server Data Tools 14.0.60629.0 Microsoft SQL Server Data Tools
SQL Server Integration Services Microsoft SQL Server Integration
Services Designer Version 13.0.1601.5
SQL Server Reporting Services 13.0.1605.88 Microsoft SQL Server
Reporting Services Designers Version 13.0.1605.88
TypeScript 1.8.36.0 TypeScript tools for Visual Studio
Visual Studio Tools for Unity 2.8.0.0 Visual Studio Tools for Unity
Windows Installer XML Toolset 3.10.2.2516 Windows Installer XML
Toolset version 3.10.2.2516 Copyright (c) Outercurve Foundation. All
rights reserved.
Xamarin 4.2.2.11 (00fa5cc) Visual Studio extension to enable
development for Xamarin.iOS and Xamarin.Android.
Xamarin.Android 7.0.2.42 (501e63c) Visual Studio extension to enable
development for Xamarin.Android.
Xamarin.iOS 10.3.1.8 (7beaef4) Visual Studio extension to enable
development for Xamarin.iOS.

Answer 1

This was fixed in both my apps by not using ThreadPool.QueueUserWorkItem and instead using TPL, Task.Factory.StartNew() to do the same thing. I did not find out why the ThreadPool.QueueUserWorkItem failed, and Xamarin did not log a response to my bug report.