有时候，我们发现工作流或插件里面的错误信息提示SQL 超时了，trace 日志里面可以找到 System.Data.SqlClient.SqlException Timeout Expired 这样的错误
some times we found that sql timeout occured in the log of workflow or plugin , we can found the key words 'timeout expired' in the trace log.
原因是什么呢，真的很难找到哈，在前端的trace日志里面你可能会发现很多 ImportXml.RunImport()这样的消息，其实是有人在导入解决方案所致。
what's the reason ,it's hard to find, this time we probably find that a lot of message about ImportXml.RunImport, In fact ,some one is importing solution package at that time.
hope this help!