c# - ASP.NET Core 3.1 InProcess 托管应用程序在启动异常后未重新启动

Question

问题

我有一个使用 IIS 托管的 InProcess ASP.NET Core Web 应用程序。我实现了每次启动时抛出的异常。 不出所料 , IIS 显示这个错误页面:

HTTP Error 500.30 - ANCM In-Process Start Failure

Common solutions to this issue:

• The application failed to start
• The application started but then stopped
• The application started but threw an exception during startup

Troubleshooting steps:

• Check the system event log for error messages
• Enable logging the application process' stdout messages
• Attach a debugger to the application process and inspect

For more information visit: https://go.microsoft.com/fwlink/?LinkID=2028265

在 .Net Core 2.2(带有 CaptureStartupErrors(false))以及经典的 ASP.NET 应用程序中，IIS 尝试在下一个请求时再次启动应用程序。

对于 .Net Core 3.1，它不会 尝试重新启动，无论我为 CaptureStartupErrors 设置什么，它都会永远保持这种状态。 .

解决方法

我可以通过捕获异常并退出来解决此问题 - 如果我这样做，它将按预期运行:

public static void Main(string[] args)
{
    try
    {
        CreateWebHostBuilder(args).Build().Run();
    }
    catch (Exception)
    {
        Environment.Exit(-1);
    }
}

预期行为

对于如何更改此行为的任何想法，我都很高兴，因此在不使用此解决方法的情况下，它的行为与以前相同。如果我的应用程序抛出一个未处理的异常，它应该退出并尝试在下一个请求时重新启动。

我试过的

对 CaptureStartupErrors 使用不同的值

查找更改此行为的配置参数

在“发布”-配置中发布而不是“调试”

创建了一个 issue on Github

重现问题的代码

Repository on Github

当您将应用程序发布到 IIS 时会出现此问题，并且在没有 IIS 的情况下无法重现。

程序.cs:

public class Program
{
    public static void Main(string[] args)
    {
        File.AppendAllText("log.txt", $"{DateTime.Now.ToLongTimeString()}:Starting\r\n");
        CreateWebHostBuilder(args).Build().Run();
    }

    public static IHostBuilder CreateWebHostBuilder(string[] args) =>
        Host.CreateDefaultBuilder( args )
            .ConfigureWebHostDefaults( webBuilder =>
            {
                webBuilder
                    .UseStartup<Startup>();
            } );
}

启动.cs:

public class Startup
{
    public Startup( IConfiguration configuration )
    {
        Configuration = configuration;
    }

    public IConfiguration Configuration { get; }

    public void ConfigureServices( IServiceCollection services )
    {

    }

    public void Configure( IApplicationBuilder app, IHostingEnvironment env )
    {
        throw new Exception();

    }
}

以下文件大多是默认的，但如果你想检查:

网络配置:

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <location path="." inheritInChildApplications="false">
    <system.webServer>
      <handlers>
        <add name="aspNetCore" path="*" verb="*" modules="AspNetCoreModuleV2" resourceType="Unspecified" />
      </handlers>
      <aspNetCore processPath="dotnet" arguments=".\WebApplication20.dll" stdoutLogEnabled="false" stdoutLogFile=".\logs\stdout" hostingModel="InProcess" />
    </system.webServer>
  </location>
</configuration>

.csproj:

<Project Sdk="Microsoft.NET.Sdk.Web">

  <PropertyGroup>
    <TargetFramework>netcoreapp3.1</TargetFramework>
    <AspNetCoreHostingModel>InProcess</AspNetCoreHostingModel>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.AspNetCore.Razor.Design" Version="2.2.0" PrivateAssets="All" />
  </ItemGroup>

</Project>

FolderProfile.pubxml:

<?xml version="1.0" encoding="utf-8"?>
<!--
https://go.microsoft.com/fwlink/?LinkID=208121. 
-->
<Project ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
  <PropertyGroup>
    <DeleteExistingFiles>False</DeleteExistingFiles>
    <ExcludeApp_Data>False</ExcludeApp_Data>
    <LaunchSiteAfterPublish>True</LaunchSiteAfterPublish>
    <LastUsedBuildConfiguration>Debug</LastUsedBuildConfiguration>
    <LastUsedPlatform>Any CPU</LastUsedPlatform>
    <PublishProvider>FileSystem</PublishProvider>
    <PublishUrl>C:\inetpub\wwwroot\test</PublishUrl>
    <WebPublishMethod>FileSystem</WebPublishMethod>
    <SiteUrlToLaunchAfterPublish />
    <TargetFramework>netcoreapp3.1</TargetFramework>
    <ProjectGuid>9ec27b57-5f45-4286-aa7c-12abad61a153</ProjectGuid>
    <SelfContained>false</SelfContained>
  </PropertyGroup>
</Project>

Answer 1

如微软 did explain in my issue这是预期的行为:

I believe this behavior is expected and is a behavior difference between IIS Out-of-process and In-Process. However, we could consider trying to change the behavior for in-process.

In 2.2, it sounds like you were using IIS out-of-process, as you said you saw this behavior with Full Framework. ANCM will constantly try to restart the dotnet process if it crashes.

However, in 3.1/in-process, if the application crashes on Startup, ANCM will not restart the process if it crashes on Startup. This is for a few reasons:

Because we are running in-process, we need to restart the w3wp.exe/iisexpress.exe process entirely as we can't start the dotnet runtime twice without possibility for bad behavior. Constantly restarting the w3wp process is usually not a good idea. We made an assumption that if a process throws an unhandled exception on startup, we should required the app to be redeployed before trying again. This may not have been the right decision at the time, but it is a key reason for the behavior change.

因此，我的问题的解决方案是使用变通方法或以另一种方式处理异常。如果您决定使用该解决方法，您应该知道 IIS 有一个 configurable rapid failure protection如果应用程序池重启太频繁，则停止应用程序池。

AFAIK, the code you have to call Environment.Exit(-1) may work for a few tries, however I believe that after calling that a few times, IIS will trigger Rapid Failure protection which will force the site not to start again.