不要使用System.Threading.Timer同步？ [英] Don't use System.Threading.Timer to synchronize?

问题描述

我有一些code看起来像这样：

I have some code looking like this:

using System.Threading;

public sealed class MyClass : IDisposable {
    private readonly Timer _timer;

   public MyClass() {
        _timer = new Timer(MyCallback);
   }

   public void SomeMethod() {
       lock (_timer) {
           ...
       }
   }

   ...

}

当我运行code分析（FxCop的）我得到错误信息
CA2002：Microsoft.Reliability：对类型的引用'定时''MyClass.SomeMethod'锁。与针对对象具有很强的身份锁定替换此。

When I run code analysis (FxCop) I get the error message
CA2002 : Microsoft.Reliability : 'MyClass.SomeMethod' locks on a reference of type 'Timer'. Replace this with a lock against an object with strong-identity.

我发现了一些文档这里。

一个对象，据说有微弱的身份时，它可以跨应用程序域边界直接访问。

An object is said to have a weak identity when it can be directly accessed across application domain boundaries.

如何让我的私人计时器对象跨应用程序域进行访问？我能想到的唯一理由是，如果Timer类包装一些全局系统处理，但我不明白，手柄如何参与锁定。

How can my private timer object be accessed across appdomains? The only reason I can think of is if the Timer class wraps some global system handle but I don't understand how that handle is involved in the locking.

有弱类的文档页面上的列表，但计时器没有被提及。 MemomoryStream也不在列表上，但它被包含在实施例中。如何在本地的MemoryStream对象是弱？

There is a list of weak classes on the documentation page but Timer is not mentioned. MemomoryStream is also not on the list but it is included in the examples. How can a local MemoryStream object be weak?

推荐答案

定时器延伸的 MarshalByRefObject的 ，这就是为什么它的抱怨，我怀疑。

Timer extends MarshalByRefObject, which is why it's complaining, I suspect.

我个人建议只锁定在其上的只有的你code可以知道的私人对象有关：

Personally I would recommend only locking on a private object which only your code can know about:

using System.Threading;

public sealed class MyClass : IDisposable {
    private readonly Timer _timer;
    private readonly object _mutex = new object();

   public MyClass() {
        _timer = new Timer(MyCallback);
   }

   public void SomeMethod() {
       lock (_mutex) {
           ...
       }
   }

   ...
}

这样，你不必担心定时器是否决定对锁定此等等。

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