Blazor Server website always displays connection redirecting UI after page load

[JamesNK]

Describe the bug

https://themesof.net/ always displays the connection reconnecting UI after page load. It is displayed for a couple of seconds and then disappears.

Is Blazor Server being too aggressive with assuming a lost connection?

To Reproduce

1. Visit https://themesof.net/
2. "Reconnecting attempt 1 of 8" displayed for a couple of seconds
3. Website then works normally

Further technical details

Website source: https://github.com/terrajobst/themesof.net

@terrajobst

[JamesNK]

Screen capture:

[benaadams]

I end up with multiple connects; one per new node (fresh data) opened

themesof_Trim.mp4

[terrajobst]

Do you think that’s indicative of a bug in my site or in Blazor infrastructure? I’ll try to sieve though the exception log to see if the server has an unhandled error somewhere. Get Outlook for iOS<https://aka.ms/o0ukef>

…

________________________________ From: Ben Adams <[email protected]> Sent: Thursday, February 25, 2021 8:11:55 PM To: dotnet/aspnetcore <[email protected]> Cc: Immo Landwerth <[email protected]>; Mention <[email protected]> Subject: Re: [dotnet/aspnetcore] Blazor Server website always displays connection redirecting UI after page load (#30483) I end up with multiple connects; one per new node (fresh data) opened https://user-images.githubusercontent.com/1142958/109253845-8efd1200-77e8-11eb-95e1-639bae3bcbe7.mp4<https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fuser-images.githubusercontent.com%2F1142958%2F109253845-8efd1200-77e8-11eb-95e1-639bae3bcbe7.mp4&data=04%7C01%7CImmo.Landwerth%40microsoft.com%7C4608af378e8c4ed7b21f08d8da0ca77f%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637499095170946943%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=dI%2FkFcEDB27VWMKEJMF4RHQed5Bl3oXrfMvl5qKvynw%3D&reserved=0> — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub<https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fdotnet%2Faspnetcore%2Fissues%2F30483%23issuecomment-786398518&data=04%7C01%7CImmo.Landwerth%40microsoft.com%7C4608af378e8c4ed7b21f08d8da0ca77f%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637499095170946943%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=2pPG%2B%2BeVN6E4xFJIfLCmIeEqbymknZG0yBMzqz33qfE%3D&reserved=0>, or unsubscribe<https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fnotifications%2Funsubscribe-auth%2FABHOGKDCLB4W6SHGDO3LI2TTA4NQXANCNFSM4YHSNCTQ&data=04%7C01%7CImmo.Landwerth%40microsoft.com%7C4608af378e8c4ed7b21f08d8da0ca77f%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637499095170956944%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=wP3%2BN3%2FxlNpw%2B%2BnTKV07FR%2BnMl%2Fshn6gvSK%2BnD%2FwXHI%3D&reserved=0>.

[benaadams]

Ignoring the disconnects it is working ok (e.g. loading the nodes etc)

It does send some chonk messages

Looking at that might be busting the 32kB limit

aspnetcore/src/SignalR/common/Http.Connections/src/HttpConnectionDispatcherOptions.cs

Lines 14 to 29 in c925f99

	// Selected because this is the default value of PipeWriter.PauseWriterThreshold.
	// There maybe the opportunity for performance gains by tuning this default.
	private const int DefaultPipeBufferSize = 32768;
	/// <summary>
	/// Initializes a new instance of the <see cref="HttpConnectionDispatcherOptions"/> class.
	/// </summary>
	public HttpConnectionDispatcherOptions()
	{
	AuthorizationData = new List<IAuthorizeData>();
	Transports = HttpTransports.All;
	WebSockets = new WebSocketOptions();
	LongPolling = new LongPollingOptions();
	TransportMaxBufferSize = DefaultPipeBufferSize;
	ApplicationMaxBufferSize = DefaultPipeBufferSize;
	}

Looking at #5623 (comment); you may need to up these limits in Configure

app.UseSignalR(route => route.MapHub<BlazorHub>(BlazorHub.DefaultPath, o =>
{
    o.ApplicationMaxBufferSize = 131072; // larger size
    o.TransportMaxBufferSize = 131072; // larger size
}));
app.UseBlazor<App.Startup>();

[benaadams]

Testing with https://github.com/terrajobst/themesof.net/pull/16

[benaadams]

Specifically In ConfigureServices

            services.AddServerSideBlazor()
                .AddHubOptions(options =>
                {
                    // Increase the limits to 256 kB
                    options.MaximumReceiveMessageSize = 262144;
                });

and in Configure

                endpoints.MapBlazorHub(options => 
                {
                    // Increase the limits to 256 kB
                    options.ApplicationMaxBufferSize = 262144;
                    options.TransportMaxBufferSize = 262144;
                });

[javiercn]

This is likely the message going up exceeding the underlying max message size as @benaadams image shows.
Sending messages to the client doesn't have a limit I believe.

Do we know what's causing such a big message to be sent?

[benaadams]

The list of open nodes ThemesOfDotNet/Pages/Index.razor.cs#L572-L579

With all the nodes closed there isn't a big post from the client

With all of them open there is a 33.9kB post (followed by a 468 kB response with the data for the open nodes)

Sending messages to the client doesn't have a limit I believe.

For the first large message on startup it does look like render-mode="ServerPrerendered" still sends the full data on the first message rather than using the Prerendered state?

[mkArtakMSFT]

@javiercn moved this to the Discussions. Please include any pending work from here in your Blazor Server Improvements issues so that we can track those.

[ghost]

Thank you for contacting us. Due to a lack of activity on this discussion issue we're closing it in an effort to keep our backlog clean. If you believe there is a concern related to the ASP.NET Core framework, which hasn't been addressed yet, please file a new issue.

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