I have a general question, and curiosity about LINQ and timeouts.
I have a live application running and I am receiving timeouts on the following code.
The following code, which is normal, and I don’t see anything wrong:
private static tblUser GetUserLinq(string email, string password) { DataContext db = new DataContext();
var tblUsers = from user in db.tblUsers where user.EmailAddress == email && user.Password == password select user; if (tblUsers.Count() == 0) return null; return tblUsers.First(); } But getting the following timeouts, quite a few, on:
if (tblUsers.Count() == 0) Here is the Exception
Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding. – System.Data.SqlClient.SqlException: Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding. at System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection) at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection) at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj) at System.Data.SqlClient.TdsParser.Run(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj) at System.Data.SqlClient.SqlDataReader.ConsumeMetaData() at System.Data.SqlClient.SqlDataReader.get_MetaData() at System.Data.SqlClient.SqlCommand.FinishExecuteReader(SqlDataReader ds, RunBehavior runBehavior, String resetOptionsString) at System.Data.SqlClient.SqlCommand.RunExecuteReaderTds(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, Boolean async) at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method, DbAsyncResult result) at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method) at System.Data.SqlClient.SqlCommand.ExecuteReader(CommandBehavior behavior, String method) at System.Data.SqlClient.SqlCommand.ExecuteDbDataReader(CommandBehavior behavior) at System.Data.Common.DbCommand.ExecuteReader() at System.Data.Linq.SqlClient.SqlProvider.Execute(Expression query, QueryInfo queryInfo, IObjectReaderFactory factory, Object[] parentArgs, Object[] userArgs, ICompiledSubQuery[] subQueries, Object lastResult) at System.Data.Linq.SqlClient.SqlProvider.ExecuteAll(Expression query, QueryInfo[] queryInfos, IObjectReaderFactory factory, Object[] userArguments, ICompiledSubQuery[] subQueries) at System.Data.Linq.SqlClient.SqlProvider.System.Data.Linq.Provider.IProvider.Execute(Expression query) at System.Data.Linq.DataQuery1.System.Linq.IQueryProvider.Execute[S](Expression expression) at System.Linq.Queryable.Count[TSource](IQueryable1 source) at Actions.GetUserLinq(String email, String password) in C:\Actions.cs:line 104 at Login(String email, String password) in C:\Actions.cs:line 33
Some of my thoughts on why it is timing out:
The count needs to count the number of records in that table, and that is not what we are after If we are trying to find if a record exists then should we be using the following code:
var tblUsers = (from user in db.tblUsers where user.EmailAddress == email && user.Password == password select user).FirstOrDefault(u => u.UserId <0) ; Otherwise I am a little confused to why LINQ is timing out on a Count
One other thing I have noticed is that if you run the following SQL directly on the machine through SQL Enterprise Manager, it also times out, which suggests that it is perhaps a locking issue, however the only application calling this table is LINQ
select count(userid) from tbluser
Comments most welcome
You should check your user table’s indexes. It might be that a username/password index helps.