为什么有些对象不能从不同的线程访问？

Question

我在C＃开发过程中遇到过几次这个问题。我会是一个愉快的编码一起，传递对象来来回回线程和什么之间没有，然后突然我得到这个熟悉的错误：

"The calling thread cannot access this object because a different thread owns it."

好了，好了，我之前处理它，尤其是在GUI线程中的对象。你只需要编写一些额外的代码来编程特定的问题。但每遇到一次，我都会遇到一个平凡的对象，但它不喜欢被不同的线程访问。

编辑我在我的原始文章中误解了导致访问异常的对象。它不是IPAddress，而是它的System.Printing.PrintQueue.我用它来获取IP地址。这是您无法从多个线程评估的对象。

我写的所有课程都没有这个问题。我甚至不知道我会如何自己实现这一点。您是否必须保留一个带有创建您的线程ID的成员变量，然后根据每个属性和方法访问权限检查当前线程？这看起来很疯狂。为什么微软会决定......“好的... PrintQueue，绝对不是线程中可共享的，但是这些其他类......他们很好去。”

为什么有些对象被多线程访问阻塞？

Answer 1

我觉得这可能会解释得很好，我觉得这个具体与COM有关。

http://msdn.microsoft.com/en-us/library/ms693344%28v=vs.85%29

具体而言。

In general, the simplest way to view the COM threading architecture is to think of all the COM objects in the process as divided into groups called apartments. A COM object lives in exactly one apartment, in the sense that its methods can legally be directly called only by a thread that belongs to that apartment. Any other thread that wants to call the object must go through a proxy.

There are two types of apartments: single-threaded apartments, and multithreaded apartments.

Single-threaded apartments consist of exactly one thread, so all COM objects that live in a single-threaded apartment can receive method calls only from the one thread that belongs to that apartment. All method calls to a COM object in a single-threaded apartment are synchronized with the windows message queue for the single-threaded apartment's thread. A process with a single thread of execution is simply a special case of this model.

Multithreaded apartments consist of one or more threads, so all COM objects that live in an multithreaded apartment can receive method calls directly from any of the threads that belong to the multithreaded apartment. Threads in a multithreaded apartment use a model called free-threading. Calls to COM objects in a multithreaded apartment are synchronized by the objects themselves.