多线程单例 WCF 服务

本文介绍了多线程单例 WCF 服务的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

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在他的WCF 服务编程"一书中，Juval Lowry 表达了对使用单例服务的担忧，因为它会影响性能.

In his book "Programming WCF Services", Juval Lowry expresses concerns about using Singleton Services because of the performance implications.

在我的一个项目中，我使用了一个无状态单例 WCF 服务，声明如下:

In one of my projects I'm using a stateless singleton WCF Service declared like this:

[ServiceBehavior(InstanceContextMode = InstanceContextMode.Single,
   ConcurrencyMode = ConcurrencyMode.Multiple)]
public class FooService : IFoo
{
}

从多个 Silverlight 客户端通过 httpsTransport 访问该服务.我选择了单例，因为我认为没有必要在不需要时给系统增加 GC 开销.我是否遗漏了某些东西，或者这不应该是实现无状态服务的最有效方法，该服务即使不比 PerCall 实例化服务更快，也同样快?

The service is accessed from multiple Silverlight clients over httpsTransport. I've opted for a singleton because I see no need to burden the system the GC overhead when it is not really needed. Am I missing something or shouldn't this be the most efficient way to implement a stateless service that's equally fast if not faster than a PerCall instantiated service?

推荐答案

您没有遗漏任何东西.如果您的服务类没有实例成员变量，这些变量代表的状态显然可能会被多线程访问破坏，那么就没有什么可担心的.

You're not missing anything. If your service class has no instance member variables, which would represent state that could obviously be corrupted by multi-threaded access, there is nothing to fear.

我个人总是使用 Single+Mulitple 模式，因为我的所有状态总是来自缓存或 SQL 数据库或其他一些共享资源，在这些资源中，您无论如何都需要模式来防止并发.我从未在我的服务中发现需要成员变量.静力学?当然可能，但你知道无论如何都要保护他们.

I personally always use Single+Mulitple mode because all of my state is always coming from a cache or SQL database or some other shared resource where you need patterns to guard against concurrency anyway. I've never found a need for member variables in my services. Statics? Sure maybe, but then you know to protect them anyway.

现在这是我个人对 PerCall 与 Single 的看法.PerSession 另一方面，服务可以/很可能会在实例中维护状态，但我个人发现自己并没有写很多这样的东西，而且在极少数情况下，它们是 ConcurrencyMode.Single无论如何.

Now this is all my personal opinion on PerCall vs. Single. PerSession services on the other hand could/most likely would have state maintained in the instance, but I personally don't find myself writing many of those and on the rare occasion I have, they are ConcurrencyMode.Single anyway.

查看这篇 MSDN 文章差异的更多讨论和实际性能比较.模式.

Check out this MSDN article for more discussion and actual performance comparison of the diff. Modes.

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