问题描述

想象一下，我将在 .NET 中进行异步调用，即 HttpWebRequest.BeginGetResponse，并且 HttpWebRequest 对象没有在更广泛的范围内被引用.垃圾收集器会破坏它并引起问题吗?

Imagine that I will make an async call in .NET, i.e. HttpWebRequest.BeginGetResponse, and the HttpWebRequest object isn't referenced at a broader scope. Will the Garbage Collector destroy it and cause problems?

示例代码:

using System;
using System.Net;

public class AsyncHttpWebRequest
{
    void Main()
    {
        var Request = HttpWebRequest.Create("http://www.contoso.com");
        var result = Request.BeginGetResponse(GetResponseCallback, null);
    }

    private void GetResponseCallback(IAsyncResult AsyncResult)
    {
        // Do Something..
    }
}

替代版本(请求作为 AsyncState 传递):

Alternate version (with the request being passed as an AsyncState):

using System;
using System.Net;

public class AsyncHttpWebRequest
{
    void Main()
    {
        var Request = HttpWebRequest.Create("http://www.contoso.com");
        var result = Request.BeginGetResponse(GetResponseCallback, Request);
    }

    private void GetResponseCallback(IAsyncResult AsyncResult)
    {
        // Do Something..
    }
}

推荐答案

如果任何活动线程包含对它的引用，或者如果它被静态引用(直接或间接在两者中例).

An object is considered alive and non-eligible for garbage collection if any live thread contains a reference to it, or if it's referenced statically (directly or indirectly in both cases).

在这两个示例中，异步 API 都会保留对您请求的引用(在提交异步 IO 操作的线程池中)，因此在完成之前不会被垃圾收集.

In both examples the async API keeps a reference to your request (within the thread pool where async IO operations are lodged) and so it won't be garbage collected until it completes.

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