netnet什么时候检查程序集的依赖关系？ [英] When does .net check for assembly dependencies?

问题描述

在追求一个矛盾的问题时，我来了非常奇怪的情况。演示代码将是：

While pursuing a spearate problem I've come to a very peculiar situation. A demo code would be:

public class Global : HttpApplication
{
    protected void Application_Start(object sender, EventArgs e)
    {
        Log("In Application_Start");
        SomeClass.SomeProp = ConfigurationManager.AppSettings["PropValue"];
    }
    protected void Application_BeginRequest(object sender, EventArgs e)
    {
        Log("In Application_BeginRequest");
        try
        {
            this.Application_Start(null, null);
        }
        catch ( Exception ex )
        {
            Log(ex.ToString());
        }
        Log("At the end of Application_BeginRequest");
    }
}

我在日志中的内容是：

What I get in my log is:

In Application_BeginRequest

Could not load file or assembly 'vjslib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies. The system cannot find the file specified.
System.IO.FileNotFoundException
    at MyRootNamespace.Global.Application_Start(Object sender, EventArgs e)
    at MyRootNamespace.Global.Application_BeginRequest(Object sender, EventArgs e) in D:\My Documents\Visual Studio 2008\Projects\SolutionDir\ProjectDir\Global.asax.cs:line 109

At the end of Application_BeginRequest

这对我来说没有任何意义。考虑：

This makes no sense to me whatsoever. Consider:

• vjslib 由我的主项目（程序集）引用，其中包括全局类。如果依赖关系无法解决，为什么程序集加载？


• SomeClass 在另一个程序集中也引用 vjslib 。 SomeClass 使用 vjslib ，某些成员会公开从 vjslib ，但这里使用的属性只是一个简单的旧字符串。


• 为什么堆栈跟踪的第一行没有行号？

• vjslib is referenced by my main project (assembly) which includes the Global class. Why was the assembly loaded at all if its dependencies could not be resolved?
• SomeClass is in another assembly which also references vjslib. SomeClass does use vjslib and some members do expose classes that are derived from classes in vjslib, but the property used here is just a plain old string.
• Why is there no line number in the first line of the stack trace?

依赖方式是否按每个方法解决？我以为微软不再这样做了。

Are the dependencies resolved on a per-method basis? I thought that Microsoft doesn't do such things anymore. What's going on here?

推荐答案

我相信当CLR遇到引用IL中的某些类型时，会尝试加载它。并且它们可能导致加载组件。所以所有依赖程序集不一定在启动时加载 - 它们将按需加载。

I believe that when CLR encounter reference to some type in IL, it attempts to load it. And they may result in loading the assembly. So all dependent assemblies does not necessarily get loaded at the start up - they will be getting loaded on demand.

编辑：在SO 关于装配的加载。 CLR通过C＃这本书还谈到在IL中JIT遇到的类型时加载的程序集。

See this question on SO about when assembly gets loaded. The book "CLR via C#" also talks about assembly getting loaded when type in encountered by JIT in IL.

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