当处置，为什么？

问题描述

我问一个有关此方法

  //保存对象到磁盘
公共静态无效SerializeObject< T>（这件T toSerialize，字符串文件名）
 {
的XmlSerializer XmlSerializer的=新的XmlSerializer（toSerialize.GetType（））; 
的TextWriter的TextWriter =新的StreamWriter（文件名）; 
 
 xmlSerializer.Serialize（的TextWriter，toSerialize）; 
 textWriter.Close（）; 
} 
  

在我这还有一个额外的言论响应：

So, I can tell that this is going to seem super lame for someone who has been coding C# for a year or two, but why do I have to dispose it?

Is see that testWriter has a dispose method, but shouldn't garbage collection take care of that? I came from Delphi to C#. In Delphi I had to clean up everything, so this is not a case of me wanting to be lazy. I just was told that if you force freeing up the memory that your objects take then it can cause bad stuff. I was told to "Just let the garbage collector do it".

1. So, why do I need to call dispose? (My guess is that it is because textWriter hits the disk.)
2. Is there a list of objects I need to be careful with? (Or an easy way to know when I need to call dispose?)

解决方案

You are correct that for properly written code the GC will eventually clean up the native resources. The object will have a finalizer, and during finalization will free up the necessary native resources.

However when this happens is very non-deterministic. Additionally it's a bit backwards because you're using the GC which designed to handle managed memory as a means to manage native resources. This leads to interesting cases and can cause native resources to stay alive much longer than anticipated leading to situations where

• Files are open long after they are no longer used
• Resource handles can run out because the GC doesn't see enough memory pressure to force a collection and hence run finalizers

The using / dispose pattern adds determinism to the cleanup of native resources and removes these problems.

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