Xamarin.Forms Android 启动需要 10 秒

Question

我的 Android 应用程序(使用 Xamarin.Forms 创建)在真实设备(Asus Zenfone 2)上启动(在调试和 Release模式下)大约需要 10 秒。启动画面显示 8 秒。这是我附加的日志，其中“extrony”是我的应用程序名称。仅程序集加载就需要这么多时间。有什么帮助吗？

Android Startup log

编辑1:实际上需要 10 秒(我错误地提到了 8 秒，但现在更新了)

编辑 2: 在模拟器上(我使用适用于 Visual Studio 的 Android 模拟器)，应用程序启动速度更快，即在 4.3 秒内启动。然而在我的真实设备(Asus Zenfone2)上，花费的时间是 10 秒。这是我在真实设备上调试时在调试输出中看到的附加内容(如果在模拟器上调试则不会出现)，并且单独加载这些程序集大约需要 6 秒。

Android application is debugging.
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/extrony.Droid.dll
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Acr.Support.Android.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Acr.UserDialogs.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Acr.UserDialogs.Interface.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/AndHUD.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/CarouselView.FormsPlugin.Abstractions.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/CarouselView.FormsPlugin.Android.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/FFImageLoading.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/FFImageLoading.Forms.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/FFImageLoading.Forms.Droid.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/FFImageLoading.Platform.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/FormsViewGroup.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/HtmlAgilityPack.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Microsoft.Azure.Mobile.Analytics.Android.Bindings.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Microsoft.Azure.Mobile.Analytics.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Microsoft.Azure.Mobile.Android.Bindings.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Microsoft.Azure.Mobile.Crashes.Android.Bindings.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Microsoft.Azure.Mobile.Crashes.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Microsoft.Azure.Mobile.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Microsoft.Data.Sqlite.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Microsoft.EntityFrameworkCore.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Microsoft.EntityFrameworkCore.Relational.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Microsoft.EntityFrameworkCore.Sqlite.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Microsoft.Extensions.Caching.Abstractions.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Microsoft.Extensions.Caching.Memory.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Microsoft.Extensions.DependencyInjection.Abstractions.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Microsoft.Extensions.DependencyInjection.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Microsoft.Extensions.Logging.Abstractions.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Microsoft.Extensions.Logging.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Microsoft.Extensions.Options.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Microsoft.Extensions.Primitives.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/ModernHttpClient.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Newtonsoft.Json.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/OkHttp.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Plugin.Connectivity.Abstractions.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Plugin.Connectivity.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Plugin.CurrentActivity.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Plugin.Settings.Abstractions.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Plugin.Settings.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Plugin.Share.Abstractions.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Plugin.Share.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Remotion.Linq.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/SgmlReaderDll.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Splat.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/System.Collections.Immutable.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/System.Diagnostics.DiagnosticSource.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/System.Interactive.Async.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/System.Runtime.CompilerServices.Unsafe.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Xamarin.Android.Support.Animated.Vector.Drawable.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Xamarin.Android.Support.CustomTabs.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Xamarin.Android.Support.Design.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Xamarin.Android.Support.v4.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Xamarin.Android.Support.v7.AppCompat.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Xamarin.Android.Support.v7.CardView.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Xamarin.Android.Support.v7.MediaRouter.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Xamarin.Android.Support.v7.RecyclerView.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Xamarin.Android.Support.Vector.Drawable.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Xamarin.Forms.Core.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Xamarin.Forms.Platform.Android.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Xamarin.Forms.Platform.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Xamarin.Forms.Xaml.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/extrony.dll
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/extrony.Data.dll
Loaded assembly: Mono.Android.dll [External]
Loaded assembly: Java.Interop.dll [External]
Loaded assembly: System.Runtime.dll [External]
Loaded assembly: System.Collections.Concurrent.dll [External]
Loaded assembly: System.Reflection.dll [External]
Loaded assembly: System.Threading.dll [External]
Loaded assembly: System.Diagnostics.Debug.dll [External]
Loaded assembly: System.dll [External]
Loaded assembly: System.Runtime.InteropServices.dll [External]
Loaded assembly: System.Collections.dll [External]
Loaded assembly: System.Linq.dll [External]
Loaded assembly: System.Core.dll [External]
Loaded assembly: System.Reflection.Extensions.dll [External]
Loaded assembly: MonoDroidConstructors [External]
Loaded assembly: System.ObjectModel.dll [External]
Loaded assembly: System.Threading.Tasks.dll [External]
Loaded assembly: System.Xml.ReaderWriter.dll [External]
Loaded assembly: System.Xml.dll [External]
Loaded assembly: System.IO.dll [External]
Loaded assembly: System.Runtime.Extensions.dll [External]
Loaded assembly: System.Linq.Expressions.dll [External]
Loaded assembly: System.Resources.ResourceManager.dll [External]
Loaded assembly: System.Globalization.dll [External]
Loaded assembly: System.Dynamic.Runtime.dll [External]
Loaded assembly: System.ComponentModel.dll [External]
Thread started: <Thread Pool> #2
Thread started: <Thread Pool> #3
Thread started: <Thread Pool> #4
Thread started: <Thread Pool> #5
Loaded assembly: System.Linq.Queryable.dll [External]
Loaded assembly: Anonymously Hosted DynamicMethods Assembly [External]
Loaded assembly: System.Data.Common.dll [External]
Loaded assembly: System.Data.dll [External]
Thread started: <Thread Pool> #6
Loaded assembly: System.Diagnostics.Tracing.dll [External]
Loaded assembly: System.ComponentModel.Annotations.dll [External]
Loaded assembly: System.ComponentModel.DataAnnotations.dll [External]

编辑3:根据通过评论收到的建议在不同的设备上进行测试。这些是结果(来自发布版本)

• 在 Samsung Galaxy OnNXT 上约为 8 到 10 秒
• 在小米 Mi Max Prime 上约 6-7 秒
• 在 Redmi Note 3 上约为 4-5 秒
• 华硕 Zenfone2 上约为 9.5 秒

编辑4:我已经做了非常详细的测试，我可以确认“context.Migrate() 和使用 SingleOrDefault() 的简单查询”(EFCore) 需要 9 秒。如果我删除此调用，应用程序将在大约 3 秒内启动。

编辑 5:我期望在启动事件中的不同线程上执行 db init(如下所示)，因为 Xamarin.Forms 初始化(通常)需要大约 3 秒，并且我希望 init 也并行发生。然而，即使它在不同的线程上运行，EFCore db init 似乎也会增加启动时间。我做错了什么吗？

 protected override void OnResume()
    {
        base.OnResume();

        System.Threading.Tasks.Task.Run(() =>
        {
            App.DbFolder = System.Environment.GetFolderPath(System.Environment.SpecialFolder.Personal);
            App.InitializeDb();
        });

        StartActivity(typeof(MainActivity));

    }

有什么建议可以帮忙吗？

Answer 1

此部分占用了 4.5 秒(如果这是应用完成加载时间的准确表示)。

04-01 07:53:15.443 D/Mono    ( 1742): [0x9ac5e930] hill climbing, change max number of threads 2
04-01 07:53:15.445 W/art     ( 1742): JNI RegisterNativeMethods: attempt to register 0 native methods for md54ada4fbe4a5955f6151fa282d30cfc48.SelfDisposingBitmapDrawable
Resolved pending breakpoint at 'CleanUpReceiver.cs:16,1' to void extrony.Droid.Receivers.CleanUpReceiver.OnReceive (Android.Content.Context context, Android.Content.Intent intent) [0x00000].
04-01 07:53:20.059 D/Mono    ( 1742): DllImport searching in: '/system/lib/libsqlite.so' ('/system/lib/libsqlite.so').
04-01 07:53:20.059 D/Mono    ( 1742): Searching for 'sqlite3_column_count'.

此时所有内容都已加载，因此它是代码中的某些内容，很可能位于 App.xaml.cs 构造函数中。我注意到您也有 EF Core。

这里可能会发生很多事情，但在 App.xaml.cs 完成之前，它仍然会显示启动屏幕。

我建议在启动时在部分代码中添加秒表，看看什么花费了时间。从那里您可以在 stackoverflow 中提出与该问题相关的不同问题。

System.Diagnostics.Stopwatch s = new System.Diagnostics.Stopwatch();
s.Start();

// Code in here

s.Stop();
System.Diagnostics.Debug.WriteLine($"Elapsed Time: {s.ElapsedMilliseconds.ToString("N0")}");