Occasional Error When Executing CLR Stored Procedure

This CLR stored procedure executes without fail 99% of the time. However, occasionally it will fail with the following error:

A .NET Framework error occurred during execution of user-defined routine or aggregate "Run_SRS_Report": System.Exception: Attempt to perform native server operation (AllocateNativeRequest) outside of its valid scope.

Below is the section of code that fails:

<code>

Private Shared Sub GetReportParameters()
Dim drReportParameters As SqlDataReader

Try
' set the parameters for the command request.
_SQLCommandRequest = _SQLConnection.CreateCommand()

_SQLCommandRequest.CommandText = _spReportParms

_SQLCommandRequest.CommandType = CommandType.StoredProcedure

' get the information for the data reader request.
drReportParameters = _SQLCommandRequest.ExecuteReader

' make sure that we have something first.
If Not drReportParameters Is Nothing Then

' find out if we have any rows returned.
If drReportParameters.HasRows Then

' read each of the rows looking for the respective value.
While drReportParameters.Read

' make sure that we can get the appropriate code id.
If (Not IsDBNull(drReportParameters.Item("Code_ID"))) AndAlso (Not IsDBNull(drReportParameters.Item("Display_Text"))) Then

' set the parameters for each of the following internal variables.
Select Case drReportParameters.Item("Code_ID").ToString
Case Is = "PDFP Path"
_FileLocationPDFP = drReportParameters.Item("Display_Text").ToString
Case Is = "PDF Temp Path"
_FileLocationPDFTemp = drReportParameters.Item("Display_Text").ToString
Case Is = "LogFile Path"
'''_SqlPipe.Send("Path from sys codes: " & drReportParameters.Item("Display_Text").ToString)
_FileLocationLogFile = Path.Combine(drReportParameters.Item("Display_Text").ToString, "SRSReportLog_" & Now.ToString("HHmmss") & ".txt")
Case Is = "LogFile Flag"
_swLogFlag = IIf(drReportParameters.Item("Display_Text").ToString = "False", False, True)
Case Is = "Delete PDF"
_DeletePDFFlag = IIf(drReportParameters.Item("Display_Text").ToString = "False", False, True)
Case Is = "PrintTool"
_PrintTool = drReportParameters.Item("Display_Text").ToString
Case Is = "BPP Path"
_BppPath = drReportParameters.Item("CharVar1").ToString
Case Is = "SendToPrinter"
_SendToPrinterFlag = IIf(drReportParameters.Item("Display_Text").ToString = "False", False, True)
Case Else
' ignore it.
End Select

End If

End While

End If

End If

Catch ex As Exception
' throw a new exception to trip up the PrintReport() function.
Throw New Exception(ex.Message)

Finally

' make sure that we close out the datareader, regardless.
If Not drReportParameters Is Nothing Then
If Not drReportParameters.IsClosed Then drReportParameters.Close()
End If

End Try

End Sub

</code>

Any ideas why this would fail only occasionally (maybe 1% of the time it's executed)?

_SQLCommandRequest is a shared (that is, static) variable, right? You are seeing this error because your proceduce is being executed on multiple threads at the same time, and multiple threads are not allowed to use the same SqlConnection at the same time. (The error message is fixed in the next version of SQL Server to be more clear what the problem is).

It looks like you frequently use static variables within your SP, so even if you fix this problem by using a local, non-shared SqlCommand object, you will run into other problems due to multiple threads accessing the same shared state.

Steven
|||

Understood. Thanks for the explanation.

So all I have to do is make everything local, non-shared then right?

Except for the main sub procedure declaration below which has to remain shared right?:

<Microsoft.SqlServer.Server.SqlProcedure()> _
Public Shared Sub Run_SRS_Report(ByVal ip_URL As String _

Am I on the right track?

|||

Yes, everything should be a local or class instance field, unless it is a constant, readonly value. Ideally, you should try to deploy the assembly under SAFE or EXTERNAL_ACCESS permission set, which disallows the use of static variables to prevent this type of problem.

|||

Thanks Steven. I've changed everything up so there are no static variables and re-deployed. Hopefully that will fix the problem. If not I'll post again.