Question

In a VB.Net Windows Service I’m currently pooling units of work with:

ThreadPool.QueueUserWorkItem(operation, nextQueueID)   

In each unit of work (or thread I’ll use for ease of understanding), it will make a couple MSSQL operations like so:

    Using sqlcmd As New SqlCommand('', New SqlConnection(ConnString))         With sqlcmd             .CommandType = CommandType.Text             .CommandText = 'UPDATE [some table]'              .Parameters.Add('@ID', SqlDbType.Int).Value = msgID              .Connection.Open()             .ExecuteNonQuery()             .Connection.Close()   'Found connections not closed quick enough'         End With     End Using 

When running a netstat -a -o on the server I’m seeing about 50 connections to SQL server sitting on IDLE or ESTABLISHED, this seems excessive to me especially since we have much larger Web Applications that get by with 5-10 connections.

The connection string is global to the application (doesn’t change), and has Pooling=true defined as well.

Now will each of these threads have their own ConnectionPool, or is there one ConnectionPool for the entire .EXE process?

Answer 1

From the MS Docs –

‘Connections are pooled per process, per application domain, per connection string and when integrated security is used, per Windows identity’

http://msdn.microsoft.com/en-us/library/8xx3tyca.aspx

Are you experiencing errors such as –

Exception Details: System.InvalidOperationException: Timeout expired. The timeout period elapsed prior to obtaining a connection from the pool. This may have occurred because all pooled connections were in use and max pool size was reached.

Also how many work items are being queued in the service?