.NET MAUI 应用程序中的死锁和ConfigureAwait 问题

Question

我正在开发 .NET MAUI 应用程序，并遇到了与异步编程相关的潜在死锁问题。我正在寻求有关如何正确使用

ConfigureAwait(false)

以避免死锁并提高性能的建议。

问题描述

在我的应用程序中，我有几个与

ViewModel

交互的异步方法，用于执行数据获取、UI 更新和页面导航等任务。最近，我注意到某些 UI 交互会导致死锁，导致 UI 变得无响应，并且某些操作无限期挂起。

代码详情

这是我的代码的简化版本：

XAML 代码

<ScrollView Orientation="Both" FlowDirection="RightToLeft"
            HorizontalOptions="Start"
            x:Name="ItemsScroller"
            Scrolled="ScrollView_Scrolled"
            HorizontalScrollBarVisibility="Always">
    <VerticalStackLayout>
        <HorizontalStackLayout HeightRequest="48" BackgroundColor="#F5F6F7">
            <!-- Header Labels -->
            <Label Text="کد کالا" Style="{StaticResource LableStyle}" WidthRequest="150" FontAttributes="Bold"/>
            <Label Text="کالا" Style="{StaticResource LableStyle}" WidthRequest="300" FontAttributes="Bold"/>
            <Label Text="نرخ" Style="{StaticResource LableStyle}" WidthRequest="150" FontAttributes="Bold"/>
            <Label Text="مصوبه" Style="{StaticResource LableStyle}" WidthRequest="200" FontAttributes="Bold"/>
            <Label Text="تاریخ مصوبه" Style="{StaticResource LableStyle}" WidthRequest="100" FontAttributes="Bold"/>
            <Label Text="شماره مصوبه" Style="{StaticResource LableStyle}" WidthRequest="100" FontAttributes="Bold"/>
            <Label Text="موجودی" Style="{StaticResource LableStyle}" WidthRequest="100" FontAttributes="Bold"/>
        </HorizontalStackLayout>
        <CollectionView HorizontalScrollBarVisibility="Never" VerticalScrollBarVisibility="Never"
                        VerticalOptions="StartAndExpand"
                        SelectionMode="Multiple" SelectedItems="{Binding SelectedProduct, Mode=TwoWay}"
                        ItemsSource="{Binding Goods}"
                        x:Name="GoodsCollectionView">
            <CollectionView.ItemTemplate>
                <DataTemplate>
                    <HorizontalStackLayout HeightRequest="48">
                        <!-- Data Template for items -->
                        <VisualStateManager.VisualStateGroups>
                            <VisualStateGroup Name="CommonStates">
                                <VisualState Name="Normal">
                                    <VisualState.Setters>
                                        <Setter Property="BackgroundColor" Value="{Binding Color}"/>
                                    </VisualState.Setters>
                                </VisualState>
                                <VisualState Name="Selected">
                                    <VisualState.Setters>
                                        <Setter Property="BackgroundColor" Value="#C8E6FF"/>
                                    </VisualState.Setters>
                                </VisualState>
                            </VisualStateGroup>
                        </VisualStateManager.VisualStateGroups>

                        <!-- Item Labels -->
                        <Label Text="{Binding ProductCode}" Style="{StaticResource LableStyle}" WidthRequest="150"/>
                        <Line Stroke="#DFDFE0" Y2="40" VerticalOptions="Center"/>
                        <Label Text="{Binding ProductName}" Style="{StaticResource LableStyle}" WidthRequest="300"/>
                        <Line Stroke="#DFDFE0" Y2="40" VerticalOptions="Center"/>
                        <Label Text="{Binding Rate, StringFormat='{0:N0}'}" Style="{StaticResource LableStyle}" WidthRequest="150"/>
                        <Line Stroke="#DFDFE0" Y2="40" VerticalOptions="Center"/>
                        <Label Text="{Binding MosavabeSharh}" Style="{StaticResource LableStyle}" WidthRequest="200"/>
                        <Line Stroke="#DFDFE0" Y2="40" VerticalOptions="Center"/>
                        <Label Text="{Binding MosavabeDate}" Style="{StaticResource LableStyle}" WidthRequest="100"/>
                        <Line Stroke="#DFDFE0" Y2="40" VerticalOptions="Center"/>
                        <Label Text="{Binding MosavabeNo, StringFormat='{0:N0}'}" Style="{StaticResource LableStyle}" WidthRequest="100"/>
                        <Line Stroke="#DFDFE0" Y2="40" VerticalOptions="Center"/>
                        <Label Text="{Binding MojodiVaghee, StringFormat='{0:N0}'}" Style="{StaticResource LableStyle}" WidthRequest="100"/>
                    </HorizontalStackLayout>
                </DataTemplate>
            </CollectionView.ItemTemplate>
        </CollectionView>
    </VerticalStackLayout>
</ScrollView>

背后代码

private async void ScrollView_Scrolled(object sender, ScrolledEventArgs e)
{
    if (!onNavigated) return;

    var scrollView = sender as ScrollView;
    if (scrollView != null && scrollView.ScrollY >= scrollView.ContentSize.Height - scrollView.Height)
    {
        await _viewModel.RunIsBusyTaskAsync(async () =>
        {
            start += 49;
            end += 49;
            await _viewModel.UpdateDisplayedItems(true, start, end);
        }).ConfigureAwait(false);
    }
}

视图模型

public async Task UpdateDisplayedItems(bool IsClear, int start, int end)
{
    var result = await GoodToList(new ProductsRequest
    {
        Start = start,
        End = end
    }).ConfigureAwait(false);

    if (result == null || !result.Any())
        return;

    if (IsClear)
    {
        MainThread.BeginInvokeOnMainThread(() =>
        {
            result.ForEach(Goods.Add);

            var productcode = new HashSet<string>(product.Select(c => c.ProductCode));
            var userItemss = result.Where(x => productcode.Contains(x.ProductCode));
            AddRange(SelectedProduct, userItemss);
        });
        return;
    }
    else
    {
        Goods = new ObservableCollection<Good>(result);
        var userItems = result.Where(x => product.Select(c => c.ProductCode).Contains(x.ProductCode));
        SelectedProduct = userItems.Any() ? new ObservableCollection<object>(userItems) : new ObservableCollection<object>();
    }
}

基础视图模型

using CommunityToolkit.Mvvm.ComponentModel;
using CommunityToolkit.Mvvm.Input;
using Mopups.Services;
using POSApp.Views.Popups;
using System.Collections.ObjectModel;

namespace POSApp.ViewModel
{
    public partial class BaseViewModel : ObservableObject
    {
        private bool IsBusy, SecondIsBusy;
        private Loading loadingPopup;
        public IAsyncRelayCommand<object> OpenBrowserCommand { get; private set; }
        public IAsyncRelayCommand<object> MakePhoneCallCommand { get; private set; }

        public BaseViewModel()
        {
            loadingPopup = new Loading();
            OpenBrowserCommand = new AsyncRelayCommand<object>(OpenBrowserAsync);
            MakePhoneCallCommand = new AsyncRelayCommand<object>(MakePhoneCallAsync);
        }

        public async Task RunIsBusyTaskAsync(Func<Task> awaitableTask)
        {
            if (IsBusy) return;
            IsBusy = true;
            try
            {
                await MopupService.Instance.PushAsync(loadingPopup);
                await awaitableTask();
            }
            catch (Exception) { }
            finally
            {
                if (MopupService.Instance.PopupStack.Any())
                    await MopupService.Instance.PopAsync();
                IsBusy = false;
            }
        }

        public async Task AnimationClicked(object sender)
        {
            if (sender is VisualElement animatable)
            {
                await animatable.ScaleTo(0.75, 100);
                await animatable.ScaleTo(1, 100);
            }
        }

        public void AddRange<T>(ObservableCollection<T> collection, IEnumerable<T> items)
        {
            foreach (var item in items)
            {
                collection.Add(item);
            }
        }
    }
}

问题

尽管在

ConfigureAwait(false)

方法中使用了

UpdateDisplayedItems

，我仍然遇到死锁和 UI 元素无响应的情况。尤其是在处理由 UI 交互触发的异步操作（例如滚动）时，尤其会发生死锁。

问题

1. 我应该如何有效地使用

   ConfigureAwait(false)

   来避免 .NET MAUI 应用程序上下文中的死锁？
2. 是否有其他最佳实践来处理 MAUI 应用程序中的异步操作，以防止 UI 冻结并确保流畅的性能？
3. 我的代码中是否有特定区域可能发生死锁，如何诊断和修复它们？

任何见解或建议将不胜感激。

谢谢！

Answer 1

@movahhed 这个问题你解决了吗？