在 httpwebrequest 中创建 TCP 连接的方式和位置，以及它与 servicepoint 的关系

我试图找出在使用HttpWebRequest时何时建立TCP连接，这些连接是如何使用ServicePoint池化和重用的。

我已经查看了系统.dll，并尝试使用 ILSpy 和 Reflector 浏览代码，不知何故没有看到任何对套接字的引用，建立 tcp 连接等。

下面我粘贴了反编译的代码 - 任何人都可以给我提示或重定向我，以便我理解：

1. 何时创建 TCP 连接？
2. 如何使用 ServicePoint 保持这些连接处于活动状态、池化和重用？

来自 HttpWebRequest of System.dll的代码片段：

public override Stream GetRequestStream()
    {
        TransportContext context;
        return this.GetRequestStream(out context);
    }
    public Stream GetRequestStream(out TransportContext context)
    {
        if (Logging.On)
        {
            Logging.Enter(Logging.Web, this, "GetRequestStream", "");
        }
        context = null;
        this.CheckProtocol(true);
        if ((this._WriteAResult == null) || !this._WriteAResult.InternalPeekCompleted)
        {
            lock (this)
            {
                if (this._WriteAResult != null)
                {
                    throw new InvalidOperationException(SR.GetString("net_repcall"));
                }
                if (this.SetRequestSubmitted())
                {
                    throw new InvalidOperationException(SR.GetString("net_reqsubmitted"));
                }
                if (this._ReadAResult != null)
                {
                    throw ((Exception) this._ReadAResult.Result);
                }
                this._WriteAResult = new LazyAsyncResult(this, null, null);
                this.Async = false;
            }
            this.CurrentMethod = this._OriginVerb;
            while (this.m_Retry && !this._WriteAResult.InternalPeekCompleted)
            {
                this._OldSubmitWriteStream = null;
                this._SubmitWriteStream = null;
                this.BeginSubmitRequest();
            }
            while (this.Aborted && !this._WriteAResult.InternalPeekCompleted)
            {
                if (!(this._CoreResponse is Exception))
                {
                    Thread.SpinWait(1);
                }
                else
                {
                    this.CheckWriteSideResponseProcessing();
                }
            }
        }
        ConnectStream connectStream = this._WriteAResult.InternalWaitForCompletion() as ConnectStream;
        this._WriteAResult.EndCalled = true;
        if (connectStream == null)
        {
            if (Logging.On)
            {
                Logging.Exception(Logging.Web, this, "EndGetRequestStream", this._WriteAResult.Result as Exception);
            }
            throw ((Exception) this._WriteAResult.Result);
        }
        context = new ConnectStreamContext(connectStream);
        if (Logging.On)
        {
            Logging.Exit(Logging.Web, this, "GetRequestStream", connectStream);
        }
        return connectStream;
    }