WebView2 hangs on reading final 0 bytes via NetFxToWinRtStreamAdapter #670

Scottj1s · 2021-01-15T20:31:11Z

Originally opened on WebView2:
MicrosoftEdge/WebView2Feedback#806

But may be related to the cswinrt adapter code.

Internal tracking: https://task.ms/31565319

j0shuams · 2021-02-12T16:32:24Z

This is not a C#/WinRT issue exactly -- discussion is still going on offline about how to proceed. Seems the most appropriate fix is on the OS side of things.

j0shuams · 2021-03-17T22:35:05Z

Removing blocking label as we have a workaround for this:

var stream = new InMemoryRandomAccessStream();
await stream.WriteAsync(Encoding.UTF8.GetBytes($"<html><body><div>Hello, WebView2!</div></body></html>").AsBuffer());

Eilon · 2021-06-03T22:24:51Z

Do we have any update on this? Right now the workaround is to copy all the stream content to a new stream, which is not a great solution due to performance problems.

manodasanW · 2021-06-03T22:42:27Z

I hope to spend some time looking at this soon. Need to investigate whether we can remove our synchronization part of the task code if our delegates are already agile.

mqudsi · 2021-07-05T06:55:58Z

FYI This only happens with CsWinRt, when the same code is executed in a UAP environment it does not hang. ###

mqudsi · 2021-07-14T19:46:57Z

@j0shuams can you explain on a technical level why InMemoryRandomAccessStream() works here? I saw your comment a couple of weeks ago and figured "oh, I can just use new MemoryStream(), copy to it, then invoke AsRandomAccessStream() and spent hours trying to get it to work before trying to use a WinRT native new InMemoryRandomAccessStream() instead, which worked immediately (as a workaround).

The documentation on WebView2's threading model states that any streams passed to CreateWebResourceResponse() must be created on a background STA thread, but that doesn't help, e.g. this still hangs:

webView.CoreWebView2.WebResourceRequested += async (s, e) =>
{
    using var deferral = e.GetDeferral();

    var url = e.Request.Uri;
    var id = url.Replace("http://attachments/", "").Replace('/', '\\');
    id = WebUtility.UrlDecode(path);
    var path = TranslateAttachmentIdToPath(id);

    if (attachment is null)
    {
        e.Response = webHistory.CoreWebView2.Environment.CreateWebResourceResponse(null, 404, "Not found", "");
        return;
    }

    TaskCompletionSource<IRandomAccessStream> completion = new ();
    var t = new Thread(() =>
    {
        var stream = File.Open(path).AsRandomAccessStream();
        completion.SetResult(stream);
        // no clue how long this thread should live for, but it doesn't seem to matter
    });
    t.IsBackground = true;
    t.SetApartmentState(ApartmentState.STA);
    t.Start();

    var stream = await completion.Task;

    e.Response = webView.CoreWebView2.Environment.CreateWebResourceResponse(stream, 200, "Found", "");
    deferral.Complete();
}

I'm also not aware that either of new Stream() or stream.AsRandomAccessStream() are thread-specific, as the first can be shared across .NET threads freely and as for the second, MSDN states that RandomAccessStream is agile (but doesn't state anything about IRandomAccessStream one way or the other). There's no documentation that I can find anywhere on the WinRT/CsWinRT-specific marshalling/interop extension AsRandomAccessStream() besides this decaying document on GitHub which doesn't go into actual implementation details.

It seems that the IRandomAccessStream passed to CreateWebResourceResponse must be a native WinRT random access stream and not anything else converted to an IRandomAccessStream via .AsRandomAccessStream() or else the COM threads will lock up.

Can you or @angelazhangmsft confirm whether this is the same issue that is being tracked internally, or if I should open this as a separate bug either in the CsWinRT repo or the WebView2Feedback repo (where a similar but not identical bug was closed after saying it was being tracked here)?

mqudsi · 2021-11-21T20:53:42Z

@j0shuams @angelazhangmsft

Can you or @angelazhangmsft confirm whether this is the same issue that is being tracked internally, or if I should open this as a separate bug either in the CsWinRT repo or the WebView2Feedback repo (where a similar but not identical bug was closed after saying it was being tracked here)?

angelazhangmsft · 2021-11-22T18:24:51Z

@mqudsi - yes, this is being tracked internally (added internal link to the issue above). The issue you mentioned above is the same issue being tracked here.

mqudsi · 2021-11-22T18:25:31Z

Thanks, @angelazhangmsft

@Eilon

Fixes: dotnet#9206 microsoft/CsWinRT#670 and https://task.ms/31565319 have been marked as resolved. This PR removes the existing logic which copies the content into a memory stream, and replaces it with a call to `AsRandomAccessStream()` (`IRandomAccessStream` is still required per the `CoreWebView2` API). I tried out CSS hot reload with this change and things are working as expected. Not sure if there's a particular behavior/technique we can use to verify the validity of this change. Spoke with @Eilon regarding this, and per his recollection things were immediately hanging, and that's why this change was necessitated.

@Eilon

* Stop copying content stream in .NET MAUI Blazor Windows Fixes: #9206 microsoft/CsWinRT#670 and https://task.ms/31565319 have been marked as resolved. This PR removes the existing logic which copies the content into a memory stream, and replaces it with a call to `AsRandomAccessStream()` (`IRandomAccessStream` is still required per the `CoreWebView2` API). I tried out CSS hot reload with this change and things are working as expected. Not sure if there's a particular behavior/technique we can use to verify the validity of this change. Spoke with @Eilon regarding this, and per his recollection things were immediately hanging, and that's why this change was necessitated. * AutoCloseOnReadCompleteStream * Ensure old response content is closed out for hot reload * PR Feedback

@Eilon

Fixes: #9206 microsoft/CsWinRT#670 and https://task.ms/31565319 have been marked as resolved. This PR removes the existing logic which copies the content into a memory stream, and replaces it with a call to `AsRandomAccessStream()` (`IRandomAccessStream` is still required per the `CoreWebView2` API). I tried out CSS hot reload with this change and things are working as expected. Not sure if there's a particular behavior/technique we can use to verify the validity of this change. Spoke with @Eilon regarding this, and per his recollection things were immediately hanging, and that's why this change was necessitated.

Scottj1s added the bug Something isn't working label Jan 15, 2021

Scottj1s assigned j0shuams Jan 15, 2021

champnic mentioned this issue Jan 20, 2021

Setting response in WebResourceRequested hangs in WinUI3 MicrosoftEdge/WebView2Feedback#806

Closed

Scottj1s added this to the Release 1.1.1 milestone Jan 20, 2021

Scottj1s added the pri-0 Blocking/issue has no workaround label Jan 20, 2021

manodasanW modified the milestones: Release 1.1.1, Release 1.1.2 Jan 20, 2021

AdamBraden modified the milestones: Release 1.1.2, Release 1.2.0 Feb 16, 2021

j0shuams assigned manodasanW Feb 22, 2021

angelazhangmsft modified the milestones: Release 1.1.4, Release 1.1.5 Mar 17, 2021

j0shuams removed the pri-0 Blocking/issue has no workaround label Mar 17, 2021

angelazhangmsft modified the milestones: Release 1.2.1, Release 1.2.3 Apr 5, 2021

angelazhangmsft added the pri-2 Non-critical bugs/acceptable workaround label Apr 23, 2021

angelazhangmsft removed the pri-2 Non-critical bugs/acceptable workaround label Jun 3, 2021

angelazhangmsft modified the milestones: Release 1.3.1, Release 1.3.3 Jul 14, 2021

angelazhangmsft modified the milestones: Release 1.3.4, Release 1.3.5, Release 1.3.6 Aug 19, 2021

angelazhangmsft unassigned j0shuams Aug 23, 2021

manodasanW modified the milestones: Release 1.3.5, Release 1.3.6 Sep 14, 2021

angelazhangmsft modified the milestones: Release 1.3.6, Release 1.3.7 Oct 21, 2021

yildirimcagri-msft mentioned this issue Feb 24, 2022

How to send correct post data when navigation? MicrosoftEdge/WebView2Feedback#1238

Closed

This was referenced Mar 7, 2022

Fix issue with potential deadlock when reading a managed stream that we wrap from native code #1126

Closed

Remove the use of context within IAsyncOperation to fire handlers. #1131

Merged

manodasanW closed this as completed in #1131 Mar 10, 2022

angelazhangmsft added the fixed Issue has been fixed in an upcoming or existing release label Mar 15, 2022

This was referenced Aug 4, 2022

Explore removing resource copy into memory for .NET MAUI Blazor WebView on Windows dotnet/maui#9206

Closed

Stop copying content stream in .NET MAUI Blazor Windows dotnet/maui#9254

Merged

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WebView2 hangs on reading final 0 bytes via NetFxToWinRtStreamAdapter #670

WebView2 hangs on reading final 0 bytes via NetFxToWinRtStreamAdapter #670

Scottj1s commented Jan 15, 2021 •

edited by angelazhangmsft

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j0shuams commented Feb 12, 2021

j0shuams commented Mar 17, 2021

Eilon commented Jun 3, 2021

manodasanW commented Jun 3, 2021

mqudsi commented Jul 5, 2021

mqudsi commented Jul 14, 2021 •

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mqudsi commented Nov 21, 2021 •

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angelazhangmsft commented Nov 22, 2021

mqudsi commented Nov 22, 2021

WebView2 hangs on reading final 0 bytes via NetFxToWinRtStreamAdapter #670

WebView2 hangs on reading final 0 bytes via NetFxToWinRtStreamAdapter #670

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Scottj1s commented Jan 15, 2021 • edited by angelazhangmsft Loading

j0shuams commented Feb 12, 2021

j0shuams commented Mar 17, 2021

Eilon commented Jun 3, 2021

manodasanW commented Jun 3, 2021

mqudsi commented Jul 5, 2021

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angelazhangmsft commented Nov 22, 2021

mqudsi commented Nov 22, 2021

Scottj1s commented Jan 15, 2021 •

edited by angelazhangmsft

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mqudsi commented Jul 14, 2021 •

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mqudsi commented Nov 21, 2021 •

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