Crash on F5

[alexey-gusarov]

Hello!

After fixing issue #38 or #39 I run example ASP.Net.Core.Unity.Example.
It's started! But if I trying reload page I got exception:

An unhandled exception occurred while processing the request.
InvalidOperationException: No service for type 'Microsoft.AspNetCore.Routing.IEndpointAddressScheme`1[Microsoft.AspNetCore.Routing.RouteValuesAddress]' has been registered.
Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService(IServiceProvider provider, Type serviceType)

Stack Query Cookies Headers
InvalidOperationException: No service for type 'Microsoft.AspNetCore.Routing.IEndpointAddressScheme`1[Microsoft.AspNetCore.Routing.RouteValuesAddress]' has been registered.
Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService(IServiceProvider provider, Type serviceType)
Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService(IServiceProvider provider)
Microsoft.AspNetCore.Routing.DefaultLinkGenerator.GetEndpoints(TAddress address)
Microsoft.AspNetCore.Routing.DefaultLinkGenerator.GetPathByAddress(HttpContext httpContext, TAddress address, RouteValueDictionary values, RouteValueDictionary ambientValues, Nullable pathBase, FragmentString fragment, LinkOptions options)
Microsoft.AspNetCore.Routing.LinkGeneratorRouteValuesAddressExtensions.GetPathByRouteValues(LinkGenerator generator, HttpContext httpContext, string routeName, object values, Nullable pathBase, FragmentString fragment, LinkOptions options)
Microsoft.AspNetCore.Mvc.Routing.EndpointRoutingUrlHelper.Action(UrlActionContext urlActionContext)
Microsoft.AspNetCore.Mvc.UrlHelperExtensions.Action(IUrlHelper helper, string action, string controller, object values, string protocol, string host, string fragment)
Microsoft.AspNetCore.Mvc.ViewFeatures.DefaultHtmlGenerator.GenerateActionLink(ViewContext viewContext, string linkText, string actionName, string controllerName, string protocol, string hostname, string fragment, object routeValues, object htmlAttributes)
Microsoft.AspNetCore.Mvc.TagHelpers.AnchorTagHelper.Process(TagHelperContext context, TagHelperOutput output)
Microsoft.AspNetCore.Razor.TagHelpers.TagHelper.ProcessAsync(TagHelperContext context, TagHelperOutput output)
Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperRunner.RunAsync(TagHelperExecutionContext executionContext)
AspNetCore.Views_Shared__Layout.b__44_1()
Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperExecutionContext.SetOutputContentAsync()
AspNetCore.Views_Shared__Layout.ExecuteAsync()
Microsoft.AspNetCore.Mvc.Razor.RazorView.RenderPageCoreAsync(IRazorPage page, ViewContext context)
Microsoft.AspNetCore.Mvc.Razor.RazorView.RenderPageAsync(IRazorPage page, ViewContext context, bool invokeViewStarts)
Microsoft.AspNetCore.Mvc.Razor.RazorView.RenderLayoutAsync(ViewContext context, ViewBufferTextWriter bodyWriter)
Microsoft.AspNetCore.Mvc.Razor.RazorView.RenderAsync(ViewContext context)
Microsoft.AspNetCore.Mvc.ViewFeatures.ViewExecutor.ExecuteAsync(ViewContext viewContext, string contentType, Nullable statusCode)
Microsoft.AspNetCore.Mvc.ViewFeatures.ViewExecutor.ExecuteAsync(ActionContext actionContext, IView view, ViewDataDictionary viewData, ITempDataDictionary tempData, string contentType, Nullable statusCode)
Microsoft.AspNetCore.Mvc.ViewFeatures.ViewResultExecutor.ExecuteAsync(ActionContext context, ViewResult result)
Microsoft.AspNetCore.Mvc.ViewResult.ExecuteResultAsync(ActionContext context)
Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeResultAsync(IActionResult result)
Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeNextResultFilterAsync<TFilter, TFilterAsync>()
Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Rethrow(ResultExecutedContext context)
Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.ResultNext<TFilter, TFilterAsync>(ref State next, ref Scope scope, ref object state, ref bool isCompleted)
Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeResultFilters()
Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeNextResourceFilter()
Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Rethrow(ResourceExecutedContext context)
Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Next(ref State next, ref Scope scope, ref object state, ref bool isCompleted)
Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeFilterPipelineAsync()
Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeAsync()
Microsoft.AspNetCore.Routing.EndpointMiddleware.Invoke(HttpContext httpContext)
Microsoft.AspNetCore.Routing.EndpointRoutingMiddleware.Invoke(HttpContext httpContext)
Microsoft.AspNetCore.StaticFiles.StaticFileMiddleware.Invoke(HttpContext context)
Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)

ServiceProvider trying to call GetService on already Disposed instance with _container = null.

My loaded assemblies:

github\examples\src\web\ASP.Net.Unity.Example\bin\Debug\netcoreapp2.2\ASP.Net.Core.Unity.Example.dll
packages\unity.container\5.10.0\lib\netcoreapp2.0\Unity.Container.dll
packages\unity.abstractions\4.1.1\lib\netcoreapp2.0\Unity.Abstractions.dll
packages\unity.microsoft.dependencyinjection\5.10.0\lib\netcoreapp1.1\Unity.Microsoft.DependencyInjection.dll
github\examples\src\web\ASP.Net.Unity.Example\bin\Debug\netcoreapp2.2\ASP.Net.Core.Unity.Example.Views.dll

[ENikS]

It appears that Microsoft code releases the Service Provider and later call it during page reload. I've filed an Issue with Asp Net project and will wait for their recommendations.

@davidfowl
I am assuming it is not a new requirement to still be able to resolve dependencies on the disposed Service Provider?

[davidfowl]

@ENikS no we shouldn;'t be calling GetService on a disposed service provider.

[Hieronymus1]

I see the temporary workaround was rolled back on this commit.

I tried to keep a reference of the IServiceProvider to prevent GC but this unfortunately didn't work because the container is set to null in the Dispose implementation so Unity.Microsoft.DependencyInjection.ServiceProvider.GetService throws an ObjectDisposedException that wouldn't occur if the container wasn't forced to null.

Do you know any workaround to avoid this exception that is systematically thrown after reloading a page?

Could I make a pull request to remove the null assignment that shouldn't be necessarily in the Dispose implementation?

[Hieronymus1]

Removing the null assignation on the container in the ServiceProvider Dispose method fixed the ObjectDisposedException as I did on this branch.

I'm not sure why IDisposable must be implemented in ServiceProvider but it shouldn't be responsible to dispose the container that is not created by the ServiceProvider. IDisposable implementation should only disposed instances they created because they are not responsible to manage the lifetime of external instances.

In any case, removing the null assignation did the trick because the GC won't collect objects that are still referenced int he dependency tree.

Should I make a pull request?

[ENikS]

@Jeromino
No, your rationalization is incorrect. Disposed container should be disposed and collected by GC. Keeping a reference alive is undesirable behavior.

The workaround was rolled back so @davidfowl can debug with correct exceptions in place. Until this issue is fixed you could still use the version with the workaround.

[Hieronymus1]

I am sorry but the relation from the ServiceProvider to the IUnityContainer is an aggregation, not a composition. When implementing IDisposable we shouldn't dispose objects that weren't created internally because we are not responsible of their lifetime.

In this case, when using the IServiceProvider.BuildServiceProvider extension with the container instance, as I consumer of the API, I don't expect another object to dispose the instance I created.

When a reference is still kept in the object tree the GC is smart enough to leave it alive but forcing it to null to throw an ObjectDisposedException is only making things worst by breaking the normal behavior.

Could you please confirm in which version was released the temporary workaround?