Xaml string parsing times at load

21 Oct 2024, 18:17

Hi all,

We've noticed there's quite a bit of processing time devoted to string parsing when loading up Xaml files at startup. Are there plans to support a binary format for xaml to eliminate some of these issues? I'd like to be able to pre-process my xaml files into binary files to improve load and processing time when starting up.

Microsoft has support for binary xaml (baml) that does something similar.

Thanks!

21 Oct 2024, 18:41

Yes, there are plans for this.

Could you please go to UI.cpp and make sure NS_XAML_RELOAD_ENABLED is defined to get timing information about parsing and instancing.

  #if NS_XAML_RELOAD_ENABLED
    uint64_t t0 = HighResTimer::Ticks();
    Ptr<XamlParser> parser = MakePtr<XamlParser>(uri, true);
    parser->Parse(stream);

    uint64_t t1 = HighResTimer::Ticks();
    NS_LOG_TRACE("(=) Parsing %s (%.0f ms)", uri.Str(), 1000.0 * HighResTimer::Seconds(t1 - t0));

    tree = XamlReader::Load(parser, root, uri);
    uint64_t t2 = HighResTimer::Ticks();
    NS_LOG_TRACE("(=) Instancing %s (%.0f ms)", uri.Str(), 1000.0 * HighResTimer::Seconds(t2 - t1));

In our internal tests, parsing is around 15%.

22 Oct 2024, 17:38

Hi!
Using those tests, it looks like I'm getting the following totals going from startup to the UI fully loaded.

Total string parsing = 63.818ms
Total Instancing = 216.920ms
About 23% of total parse time spent string parsing.

Max single document string parsing = 4.547ms
Max single document instancing = 71.631ms (primary theme xaml)

I expect these numbers only to get worse as we continue on through development and the UI becomes more complicated. So, being able to eliminate 4+ frames out of the startup by using a binary representation of the xaml is an easy win, so definitely looking forward to when that implementation is available.

29 Oct 2024, 17:10

I expect these numbers only to get worse as we continue on through development and the UI becomes more complicated. So, being able to eliminate 4+ frames out of the startup by using a binary representation of the xaml is an easy win, so definitely looking forward to when that implementation is available.

Just one more question: is this issue occurring with XAML files that are instantiated multiple times (such as UserControls), or only with single-use XAMLs? We’re also considering adding support for faster instantiation of UserControls by storing the node tree in memory to avoid repeated parsing.

Xaml string parsing times at load

Xaml string parsing times at load

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