Procedure times out from ADO.NET but not in SSMS

Question

I've got a stored procedure that is giving me a SqlException because of a timeout when I run it from code (with timeout set to 30). When I run the procedure directly in Management Studio, it executes in under 1 second. I also only get the timeout when running it against a specific database. When I use other databases it finishes quickly without an error. Here is the full error message:

System.Data.SqlClient.SqlException (0x80131904): 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()
   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.System.Data.IDbCommand.ExecuteReader(CommandBehavior behavior)

Does this stack trace mean anything to anyone? It looks like maybe my sproc completed and it timed out while trying to read some kind of meta data?

I tried looking at the process while it is running and it is Suspended. sys.dm_os_waiting_tasks shows the wait type as IO_COMPLETION, if that's of any use. The only processes I see on the database using sp_who2 'active' are the one timing out and my active SSMS window so I don't think it's a blocking issue. I verified this database has the same indeces as a working database and ran dbcc checkdb without any errors on it. How can I determine the cause of the timeout?

Answer 1

You can compare the SET options for the session that is timing out to those from the session that is not:

SELECT
    session_id,
    [ansi_defaults],
    [ansi_null_dflt_on],
    [ansi_nulls],
    [ansi_padding],
    [ansi_warnings],
    [arithabort],
    [concat_null_yields_null],
    [deadlock_priority],
    [quoted_identifier],
    [transaction_isolation_level]
FROM
    sys.dm_exec_sessions
WHERE
    session_id IN (<spid1>, <spid2>);

When you find some that are different, experiment with changing each setting to the opposite in your SSMS query until you get the timeout (or manually setting the option(s) in your app code before sending the query). Now, I don't have a 2005 instance handy, so have not tested this query. You may need to comment out one or more column names.