链接字符串里面不要加上connection timeout =0 https://connect.microsoft.com/VisualStudio/feedback/ViewFeedback.aspx?FeedbackID=331882&wa=wsignin1.0 如果加上，那么多线程2，3个链接就会让connection pool挂掉 MS说会在下一个major release里面修正，也许是4.0.