Question

为什么使用PageAsyncTask的以下ASP.NET代码总共执行8秒，无论我是按原样运行还是使用PageAsyncTask注释2行并在Page_load中取消注释Thread.Sleep（5000）？：

//PageAsyncTask asyncTask1 = new PageAsyncTask(BeginAsyncOperation, EndAsyncOperation, OperationTimeOut, arr, true); //Page.RegisterAsyncTask(asyncTask1);

Thread.Sleep(5000);

我知道PageAsyncTask与其他任务并行运行任务，在这种情况下应该使页面加载的整个过程更快。我错过了什么？

public partial class _Default : System.Web.UI.Page
{
    public delegate string foo(string param1, string param2);
    public IAsyncResult BeginLongRunningTransaction(AsyncCallback cb, object state)
    {
        var arr = (string[])state;
        string z1 = arr[0];
        string z2 = arr[1];

        foo method = this.LongRunningTransaction;
        return method.BeginInvoke(z1, z2, cb, state);
    }
    protected void Page_Load(object sender, EventArgs e)
    {
        Response.Write(DateTime.Now.ToString() + "<br/>");
        string[] arr = { "Zorik1", "Zorik2" };


        // if I comment following two lines and un-comment
        // Thread.Sleep(5000) command the process runs 8 sec. regardless
        PageAsyncTask asyncTask1 = new PageAsyncTask(BeginAsyncOperation, EndAsyncOperation, OperationTimeOut, arr, true);
        Page.RegisterAsyncTask(asyncTask1);


        //Thread.Sleep(5000);
        Thread.Sleep(1000);
        Thread.Sleep(1000);
        Thread.Sleep(1000);
    }

    private IAsyncResult BeginAsyncOperation(object sender, EventArgs e,
     AsyncCallback cb, object state)
    {
        return this.BeginLongRunningTransaction(cb, state);
    }

    private string LongRunningTransaction(string param1, string param2)
    {
        Thread.Sleep(5000);
        txtAsync.Text = "Updated";
        updPnl1.Update();
        return "this is return string";
    }


    private void EndAsyncOperation(IAsyncResult ar)
    {

    }

    private void OperationTimeOut(IAsyncResult asyncResult)
    {
        string a = "";
    }

    protected void Page_PreRender(object s, EventArgs e)
    {
        string a = "";
        Response.Write(DateTime.Now.ToString() + "<br/>");
    }

    protected void Page_PreRenderComplete(object s, EventArgs e)
    {
        Response.Write(DateTime.Now.ToString() + "<br/>");
    }

}

Answer 1

那是因为你实际上没有并行运行任何内容 - 所有PageAsyncTask都在ExecuteRegisteredAsyncTasks()页面方法调用上运行，并且会在{{1}之后自动发生} ends（和Page_PreRender在所有任务完成或超时后启动）：http://msdn.microsoft.com/en-us/library/system.web.ui.pageasynctask.aspx

如果尚未执行PreRenderComplete事件之前注册的任何异步任务将由页面自动执行。必须通过ExecuteRegisteredAsyncTasks方法显式执行在PreRenderComplete事件之后注册的那些异步任务。 ExecuteRegisteredAsyncTasks方法还可用于在PreRenderComplete事件之前启动任务。 ExecuteRegisteredAsyncTasks方法执行页面上尚未执行的所有已注册异步任务。

因此，在任何Page_PreRenderComplete开始之前，您必须在ExecuteRegisteredAsyncTasks()中手动呼叫Page_Load（可以安全地多次呼叫）。或者将每个Thread.Sleep()放在不同的Thread.Sleep()中 - 但要确保第五个参数（用于并行执行）是PageAsyncTask，并设置该页面async指令：＆lt;％@ Page Async = “true”％＆gt;

PageAsyncTask时间与顺序进程相同？

1 个答案: