c# - 首次运行时自动运行 Ngen.exe

Question

我的应用没有安装程序。它是可移植的，但我需要在其上运行 ngen.exe，因为它在启动时运行。

是否建议在应用程序首次运行时自动运行 ngen.exe？以后会不会出问题？有内置的方法吗？

Answer 1

是否建议在应用首次运行时自动运行 ngen.exe？

我从未读过或听过任何此类建议，但这是一个有趣的想法。

我说去做吧，测试它是否适合您的情况(就您的“便携”/“无安装程序”要求而言，这很有趣)。

有内置的方法吗？

在第一次运行应用程序时，没有内置的方式来运行 NGen；但它可以按照下面的 PoC 演示来完成。

PoC代码

以下 PoC 代码包含 code from a related SO answer .

using System;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Threading;

namespace SelfNgenPoC
{
    class Program
    {
        static void Main(string[] args)
        {
            /*
             * Check whether the app has been NGen'd with code adapted from
             * https://stackoverflow.com/a/20593260/1810429, which also outlines
             * an alternative approach - by running...
             *     ngen.exe display <assemblyPath>
             * ...and checking the result - 0 if the app is already NGen'd and
             * -1 if it is not.
             */

            Process process = Process.GetCurrentProcess();

            ProcessModule[] modules = new ProcessModule[process.Modules.Count];
            process.Modules.CopyTo(modules, 0);

            var niQuery =
                from m in modules
                where m.FileName.Contains(@"\" + process.ProcessName + ".ni")
                select m.FileName;
            bool ni = niQuery.Count() > 0 ? true : false;

            // FORNOW: for PoC debugging and sanity checking
            if (ni)
                Console.WriteLine("Native Image: " + niQuery.ElementAt(0));
            else
                Console.WriteLine("IL Image: " + process.MainModule.FileName);

            /*
             * NGen the app if not.
             */

            if (!ni)
            {
                // FORNOW: for PoC debugging and sanity checking
                Console.WriteLine("The app is not NGen'd.");
                Console.WriteLine("NGen'ing the app...");

                var assemblyPath = process.MainModule.FileName;

                ProcessStartInfo startInfo = new ProcessStartInfo();
                // TODO: Determine the path to (the appropriate version of)
                // ngen.exe.
                // FORNOW: Just use a hardcoded path to ngen.exe for PoC.
                startInfo.FileName =
                    @"C:\Windows\Microsoft.NET\Framework\v4.0.30319\ngen.exe";
                startInfo.Arguments = "install \"" + assemblyPath + "\"";
                // TBD: process options that you think make sense
                startInfo.CreateNoWindow = false;
                startInfo.UseShellExecute = false;
                startInfo.WindowStyle = ProcessWindowStyle.Hidden;

                try
                {
                    using (Process exeProcess = Process.Start(startInfo))
                    {
                        exeProcess.WaitForExit();
                    }
                }
                catch
                {
                    // TBD: error handling that you think makes sense - e.g.
                    // logging or displaying the error, moving on regardless
                    // etcetera.
                }
            }
            else
            {
                // FORNOW: for PoC debugging and sanity checking
                Console.WriteLine("The app is already NGen'd.");
            }

            /*
             * Carry on with whatever your app does.
             */
        }
    }
}

第一次运行

C:\bin\SelfNgenPoC>.\SelfNgenPoC.exe
IL Image: C:\bin\SelfNgenPoC.exe
The app is not NGen'd.
NGen'ing the app...
Microsoft (R) CLR Native Image Generator - Version 4.0.30319.18408
Copyright (c) Microsoft Corporation.  All rights reserved.
1>    Compiling assembly C:\bin\SelfNgenPoC.exe (CLR v4.0.30319) ...

C:\bin\SelfNgenPoC>

后续运行

C:\bin\SelfNgenPoC>.\SelfNgenPoC.exe
Native Image: C:\Windows\assembly\NativeImages_v4.0.30319_32\SelfNgenPoC\a461633
0444188e116025424c70d15f1\SelfNgenPoC.ni.exe
The app is already NGen'd.

C:\SelfNgenPoC>

以后会不会有什么问题？

程序集对 NGen 是否有意义取决于许多因素，您可以在 an MSDN blog post 中查看这些因素, NGen documentation on MSDN , an older but relevant "MSDN Magazine" article , 以及其他地方。

最终只有您充分了解您的应用，才能确定它对 NGen(任何、部分或全部)程序集是否有意义。

假设它确实在您的情况下有意义，我不认为它会根据您所描述的内容导致任何明显的问题。

请务必牢记标准的 NGen 职责 - 特别是 NGen MSDN 文档中提到的这一职责...

Images need to be regenerated when the original assembly or one of its dependencies is serviced.

...这应该可以通过更高级的自生成逻辑进行管理。