.net 终结器是否总是执行? [英] Are .net finalizers always executed?

问题描述

终结器是否可以保证在某些时候在 .NET 中执行(备用电源中断等)?我知道 GC 是如何工作的，而且它们运行的​​确切时间是不确定的.

Are finalizers guaranteed to be executed in .NET at some point (spare power outages and the like)? I know how GC works and that it is nondeterministic when exactly they'll run.

(搜索没有显示好的答案，所以我添加这个问题是为了与不太容易发现的实际答案合并.除此之外，我已经知道回答并在几天后添加它，以防没有人提到它.)

推荐答案

Finalizers 实际上可能永远被执行，如 Raymond Chen 解释.这个问题是在他一年一度的 CLR 周期间被问到的，这有点有趣，就在他解释它的两天后 :)

Finalizers may actually be never executed, as Raymond Chen explains. Kind of funny that this question is asked during his annual CLR week, just two days after he explained it :)

对于懒惰的人来说，(或者更确切地说，一个)结论是:

For the lazy ones, the (or rather, one) conclusion is:

一个正确编写的程序不能假设终结器会运行.

A correctly-written program cannot assume that finalizers will ever run.

如果您想知道是否可以依赖终结器，这已经是您必须知道的一切:不要依赖终结器.

If you are wondering whether you can rely on finalizers, this is already everything you have to know: Don't rely on finalizers.

正如 Raymond Chen 在链接文章中所说:

As Raymond Chen also states in the linked article:

终结器是一个安全网，而不是资源回收的主要手段.

Finalizers are a safety net, not a primary means for resource reclamation.

如果您正在寻找如何释放资源，请查看 Disposable 模式.

If you're looking for how to release resources, have a look at the Disposable pattern.

终结器可能不会运行，例如，如果:

A finalizer may not run, for example, if:

• 另一个终结器引发异常.
• 另一个终结器需要 2 秒以上.
• 所有终结器加起来需要 40 多秒.
• AppDomain 崩溃或被卸载(尽管您可以使用关键终结器(CriticalFinalizerObject、SafeHandle 或类似的东西)规避这种情况)
• 不进行垃圾回收
• 进程崩溃

(注意:时间值可能随时间变化，但前段时间肯定是真的.)

(Note: The time values may have changed over time, but were certainly true some time ago.)

我想还有很多事情会导致终结器永远无法运行.底线是，除了陈先生的话之外，终结器是一个安全网，减少错误的影响，因为例如资源会在某个时候被释放，这比从不要好，如果你忘记明确说明的话.

I guess there are a lot more things that can cause finalizers to never run. The bottom line is, other than the quote from Mr. Chen, that finalizers are a safety net that decrease the impact of bugs, because for example resources are released sometime, which is better than never, if you forget to do it explicity.

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