"XmlDocument 的任何公共静态成员都是线程安全的.不保证任何实例成员都是线程安全的": 对，但是 [英] "Any public static members of XmlDocument are thread safe. Any instance members are not guaranteed to be thread safe" : yes, but

问题描述

我在中看到XmlDocument 类文档 在 MSDN 上

I see in the XmlDocument class documentation on MSDN that

此类型的任何公共静态(在 Visual Basic 中为 Shared)成员都是线程安全的.不保证任何实例成员都是线程安全的.

Any public static ( Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

XmlNodeList 类也是如此.

我在以下上下文中使用这些类.在 Parallel.Foreach 里面我做:

I am using those classes in the following context. Inside a Parallel.Foreach I do :

X MyX = new X();
string XMLstring = MyX.GetXML(ID, true);
XmlDocument doc = new XmlDocument();
doc.LoadXml(XMLstring);
XmlNodeList nodeList = doc.SelectNodes("blah/secondblah");

X 是在 IT 提供给我的库中定义的，ID 是 int(我大致在其上循环).

where X is defined in a library the IT's are providing to me and where ID is an int (roughly on which I loop).

这个已经在非并行上下文中彻底测试过，GetXML产生的string确实是正确的，对应的XmlDocument也是如此，并通过XmlNodeList解析"它提供了预期的结果.

This has been tested thoroughly in a non parallel context, the strings produced by GetXML are indeed correct, the corresponding XmlDocument as well, and "parsing" it via XmlNodeList provides the expected results.

现在，在这个并行上下文中，并假设 X 和 GetXML 确实是线程安全的，我 new 和 每个循环中的 code>XmlDocument 是否确保线程安全?我的意思是，我怎么知道 string 成员(首先有这样的字符串?因为我在文档中没有看到任何 string 属性)XmlDocument 接收到 LoadXml 是 static 还是不是?

Now, it this parallel context and assuming that X and GetXML are indeed thread-safe, does the fact that I new an XmlDocument in every loop ensure thread-safety or not ? I mean, how can I know that the string member (first of all is there such a string ? as I don't see any string property in the document) of XmlDocument receiving the LoadXml is static or not ?

我想我并不真正理解我上面引用的 MSDN 文档......

I suppose I don't really understand the bit of MSDN documentation I am quoting above ...

推荐答案

文档意味着任何静态方法(看起来像 XmlDocument.MethodCall 是线程安全的.那不是与您相关 - 您不会调用其中任何一个.其他方法(例如针对 doc)不是静态的 - 因此不能保证它们是线程安全的.

The documentation means that any methods that are static (which would look like XmlDocument.MethodCall are thread-safe. That isn't relevant to you - you aren't calling any of those. Other methods (e.g. against doc) are not static - so they are not guaranteed to be thread-safe.

只要 doc(和 nodeList 和其他非线程安全"变量)仅在单线程.

Your code will be 100% fine, as long as doc (and nodeList and other 'non thread-safe' variables) are used solely within the context of a single thread.

因此，如果您在 Parallel.ForEach 之前填充 doc ，然后在 Parallel.ForEach 中使用 doc inside- 那行不通.

So if you populated doc before the Parallel.ForEach and then used doc inside the Parallel.ForEach - that won't work.

但是如果你填充和使用 doc inside Parallel.ForEach 你会没事的(因为每个线程都会得到它自己的文档——因此线程安全获胜不是问题).

But if you populate and used doc inside the Parallel.ForEach you will be fine (since each thread will get its 'own doc'- thus thread-safety won't be an issue).

为了 100% 确定，您需要发布整个方法(包括 Parallel.ForEach 调用)以供我们查看.

To be 100% sure, you'd need to post the entire method (including the Parallel.ForEach call) for us to have a look at.

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