Long UI delay trying to open file. (> 10 seconds)

[CyrusNajmabadi]

Dump is here: "\mlangfs1\public\cyrusn\Dumps\LongHangOpeningFile.dmp"

Note: i have 86 threads in this dump.

Threads of interest:

UI thread:

 	[Managed to Native Transition]	
>	Microsoft.VisualStudio.Threading.NoMessagePumpSyncContext.Wait(waitHandles, waitAll, millisecondsTimeout)	Unknown
 	System.Threading.SynchronizationContext.InvokeWaitMethodHelper(syncContext, waitHandles, waitAll, millisecondsTimeout)	Unknown
 	[Native to Managed Transition]	
 	[Managed to Native Transition]	
 	System.Threading.Monitor.Wait(obj, millisecondsTimeout, exitContext)	Unknown
 	System.Threading.Monitor.Wait(obj, millisecondsTimeout)	Unknown
 	System.Threading.ManualResetEventSlim.Wait(millisecondsTimeout, cancellationToken)	Unknown
 	System.Threading.Tasks.Task.SpinThenBlockingWait(millisecondsTimeout, cancellationToken)	Unknown
 	System.Threading.Tasks.Task.InternalWait(millisecondsTimeout, cancellationToken)	Unknown
 	System.Threading.Tasks.Task.Wait(millisecondsTimeout, cancellationToken)	Unknown
 	System.Threading.Tasks.Task.Wait(timeout)	Unknown
 	Microsoft.VisualStudio.Threading.JoinableTaskFactory.WaitSynchronouslyCore(task)	Unknown
 	Microsoft.VisualStudio.Threading.JoinableTaskFactory.WaitSynchronously(task)	Unknown
 	Microsoft.VisualStudio.Threading.JoinableTask.CompleteOnCurrentThread()	Unknown
 	Microsoft.VisualStudio.Threading.JoinableTask<Microsoft.VisualStudio.ProjectSystem.VS.HResult>.CompleteOnCurrentThread()	Unknown
 	Microsoft.VisualStudio.Threading.JoinableTaskFactory.Run<Microsoft.VisualStudio.ProjectSystem.VS.HResult>(asyncMethod, creationOptions)	Unknown
 	Microsoft.VisualStudio.ProjectSystem.ProjectMultiThreadedService.ExecuteSynchronously<Microsoft.VisualStudio.ProjectSystem.VS.HResult>(asyncAction)	Unknown
 	Microsoft.VisualStudio.ProjectSystem.VS.Implementation.Package.ProjectNode.HrInvoke.AnonymousMethod__0()	Unknown
 	Microsoft.VisualStudio.ProjectSystem.VS.HResult.Invoke(action, vsShellServiceProvider, projectFaultHandlerService, project)	Unknown
 	Microsoft.VisualStudio.ProjectSystem.VS.Implementation.Package.ProjectNode.HrInvoke(asyncAction, registerProjectFaultHandlerService)	Unknown
 	Microsoft.VisualStudio.ProjectSystem.VS.Implementation.Package.ProjectNode.GetProperty(itemId, propId, propValParam)	Unknown
 	Microsoft.VisualStudio.ProjectSystem.VS.Implementation.Package.ProjectNodeWrapper.GetProperty(itemid, propid, pvar)	Unknown
 	[Native to Managed Transition]	
 	[Managed to Native Transition]	
 	Microsoft.VisualStudio.PlatformUI.UIContextRules.SelectionMonitor.GetProjectOutputType(pHierNew)	Unknown
 	Microsoft.VisualStudio.PlatformUI.UIContextRules.SelectionMonitor.OnSelectionChanged(pHierOld, itemidOld, pMISOld, pSCOld, pHierNew, itemidNew, pMISNew, pSCNew)	Unknown
 	[Native to Managed Transition]	
 	[Managed to Native Transition]	
 	Microsoft.VisualStudio.Platform.WindowManagement.WindowFrame.InvalidateSelectionContext()	Unknown

There are a lot of BG threads with the same callstack. (I counted at least 10 threads doing this before i stopped counting).

 	Microsoft.VisualStudio.Threading.JoinableTaskFactory.Run<string>(asyncMethod, creationOptions)	Unknown
 	Microsoft.VisualStudio.Threading.JoinableTaskFactory.Run<string>(asyncMethod)	Unknown
 	Microsoft.VisualStudio.ProjectSystem.ProjectMultiThreadedService.ExecuteSynchronously<string>(asyncAction)	Unknown
 	Microsoft.VisualStudio.ProjectSystem.Debug.LaunchSettingsProvider.LaunchSettingsFileFolder.get()	Unknown
 	Microsoft.VisualStudio.ProjectSystem.Debug.LaunchSettingsProvider.LaunchSettingsFile.get()	Unknown
 	Microsoft.VisualStudio.ProjectSystem.Debug.LaunchSettingsProvider.GetLaunchSettings()	Unknown
 	Microsoft.VisualStudio.ProjectSystem.Debug.LaunchSettingsProvider.UpdateProfilesAsync(activeProfile)	Unknown
 	System.Runtime.CompilerServices.AsyncTaskMethodBuilder.Start<Microsoft.VisualStudio.ProjectSystem.Debug.LaunchSettingsProvider.<UpdateProfilesAsync>d__72>(stateMachine)	Unknown

These are blocking the BG thread, likely leading the threadpool to spin up new threads.

[CyrusNajmabadi]

Tagging @davkean

[CyrusNajmabadi]

Looks like i'm hitting the same issue as Dave was here: #2317

But it would be good to verify.

[srivatsn]

Tracking with #1342