我试图让用户控件异步工作，但无论我做什么，它都会继续同步工作。我已将其精简到最低限度，作为测试 Web 应用程序。这将是用户控件:
<%@ Control Language="C#" %>
<script runat="server">
SqlConnection m_oConnection;
SqlCommand m_oCommand;
void Page_Load(object sender, EventArgs e)
{
Trace.Warn("Page_Load");
string strDSN = ConfigurationManager.ConnectionStrings["DSN"].ConnectionString + ";async=true";
string strSQL = "waitfor delay '00:00:10'; select * from MyTable";
m_oConnection = new SqlConnection(strDSN);
m_oCommand = new SqlCommand(strSQL, m_oConnection);
m_oConnection.Open();
Page.RegisterAsyncTask(new PageAsyncTask(new BeginEventHandler(BeginHandler), new EndEventHandler(EndHandler), new EndEventHandler(TimeoutHandler), null, true));
Page.ExecuteRegisteredAsyncTasks();
}
IAsyncResult BeginHandler(object src, EventArgs e, AsyncCallback cb, object state)
{
Trace.Warn("BeginHandler");
return m_oCommand.BeginExecuteReader(cb, state);
}
void EndHandler(IAsyncResult ar)
{
Trace.Warn("EndHandler");
GridView1.DataSource = m_oCommand.EndExecuteReader(ar);
GridView1.DataBind();
m_oConnection.Close();
}
void TimeoutHandler(IAsyncResult ar)
{
Trace.Warn("TimeoutHandler");
}
</script>
<asp:gridview id="GridView1" runat="server" />
这将是我在其中托管控件三次的页面:
<%@ page language="C#" trace="true" async="true" asynctimeout="60" %>
<%@ register tagprefix="uc" tagname="mycontrol" src="~/MyControl.ascx" %>
<html>
<body>
<form id="form1" runat="server">
<uc:mycontrol id="MyControl1" runat="server" />
<uc:mycontrol id="MyControl2" runat="server" />
<uc:mycontrol id="MyControl3" runat="server" />
</form>
</body>
</html>
页面显示没有错误，但页面底部的跟踪显示每个控件实例都是同步处理的。我究竟做错了什么？是否有我缺少的配置设置？
最佳答案
看来我可以回答我自己的问题了。用户控件不应调用 Page.ExecuteRegisteredAsyncTasks。通过这样做，控件添加了异步任务，运行它，并等待它完成。
相反，用户控件的每个实例应仅调用 Page.RegisterAsyncTask。每个控件实例完成此操作后，页面会自动调用 RegistereAsyncTask 同时运行所有三个已注册的异步任务。
这是新的用户控件:
<%@ Control Language="C#" %>
<script runat="server">
SqlConnection m_oConnection;
SqlCommand m_oCommand;
void Page_Load(object sender, EventArgs e)
{
Trace.Warn(ID, "Page_Load - " + Thread.CurrentThread.GetHashCode().ToString());
string strDSN = ConfigurationManager.ConnectionStrings["DSN"].ConnectionString + ";async=true";
string strSQL = "waitfor delay '00:00:10'; select * from TEProcessedPerDay where Date > dateadd(day, -90, getutcdate()) order by Date asc";
m_oConnection = new SqlConnection(strDSN);
m_oCommand = new SqlCommand(strSQL, m_oConnection);
m_oConnection.Open();
Page.RegisterAsyncTask(new PageAsyncTask(new BeginEventHandler(BeginHandler), new EndEventHandler(EndHandler), new EndEventHandler(TimeoutHandler), null, true));
}
IAsyncResult BeginHandler(object src, EventArgs e, AsyncCallback cb, object state)
{
Trace.Warn(ID, "BeginHandler - " + Thread.CurrentThread.GetHashCode().ToString());
return m_oCommand.BeginExecuteReader(cb, state);
}
void EndHandler(IAsyncResult ar)
{
Trace.Warn(ID, "EndHandler - " + Thread.CurrentThread.GetHashCode().ToString());
GridView1.DataSource = m_oCommand.EndExecuteReader(ar);
GridView1.DataBind();
m_oConnection.Close();
}
void TimeoutHandler(IAsyncResult ar)
{
Trace.Warn(ID, "TimeoutHandler - " + Thread.CurrentThread.GetHashCode().ToString());
}
</script>
<asp:gridview id="GridView1" runat="server" />
以及创建控件的三个实例的未更改页面:
<%@ page language="C#" async="true" trace="true" %>
<%@ register tagprefix="uc" tagname="mycontrol" src="~/MyControl.ascx" %>
<html>
<body>
<form id="form1" runat="server">
<uc:mycontrol id="MyControl1" runat="server" />
<uc:mycontrol id="MyControl2" runat="server" />
<uc:mycontrol id="MyControl3" runat="server" />
</form>
</body>
</html>
关于ASP.NET 2.0 异步用户控件不起作用，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/273546/