有没有垃圾收集过程中的.NET异步调用销毁暂时未引用的对象? [英] Does the Garbage Collector destroy temporarily unreferenced objects during async calls in .NET?
问题描述
想象一下,我将在.NET,即HttpWebRequest.BeginGetResponse一个异步调用,并HttpWebRequest对象不是在更广阔的范围内引用。将垃圾收集摧毁它,会出现问题?
例如code:
使用系统;
使用System.Net;
公共类AsyncHttpWebRequest
{
无效的主要()
{
变种请求= HttpWebRequest.Create(http://www.contoso.com);
VAR的结果= Request.BeginGetResponse(GetResponseCallback,NULL);
}
私人无效GetResponseCallback(IAsyncResult的AsyncResult)
{
// 做一点事..
}
}
替代版本(该请求被通过为AsyncState):
使用系统;
使用System.Net;
公共类AsyncHttpWebRequest
{
无效的主要()
{
变种请求= HttpWebRequest.Create(http://www.contoso.com);
VAR的结果= Request.BeginGetResponse(GetResponseCallback,请求);
}
私人无效GetResponseCallback(IAsyncResult的AsyncResult)
{
// 做一点事..
}
}
一个对象被认为是活着的和非符合垃圾收集,如果任何活动线程包含对它的引用,或者如果它引用静态(直接或间接地在两个例)。
在这两个例子中的异步API有一个参考,你的要求(如异步IO操作提出线程池内),所以它不会被垃圾收集,直到它完成。
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?
Example code:
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..
}
}
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..
}
}
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).
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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