.NET Connector Connection Pooling - Blocked thread is not released?

[Former Member]

I have a .NET program that opens 2 threads to call SAP, with a connection pool of 1 concurrent connection (for testing purposes). When i call the program, I get the following trace:

2006-02-16 15:39:29Z Trace file opened.

2006-02-16 15:39:29Z Allowed to fetch new.

2006-02-16 15:39:29Z Getting new.

2006-02-16 15:39:29Z Allowed to fetch new.

2006-02-16 15:39:29Z Getting new.

2006-02-16 15:39:29Z AllocReservation: 0

2006-02-16 15:39:29Z AllocReservation: 1

2006-02-16 15:39:30Z Call method Zppeh_Inspoper_Getdetail

2006-02-16 15:39:49Z Releasing: 1

2006-02-16 15:39:49Z Call method Zppeh_Inspoper_Getdetail

I have set my connection pool string as follows:

MaxOpenConnections="1", MaxCapacity="0", MaxIdleTime="15",

CleanupInterval="5"

It seems that the second thread gets blocked, but it doesn't get released until the .NET connector terminates the connection (due to MaxIdleTime + CleanupInterval), rather than when the first thread returns the connection. Notice the 19 second difference between the call methods.

I am using .NET Connector v2.0.1 with Connection.GetConnection and Connection.Dispose.

Am I doing something wrong here?

[Former Member · Accepted solution]

Global.BotNptSap is a string constant. That is, "ASHOST=erpqa SYSNR=00 CLIENT=010 USER=ABC PASSWD=***"

FYI, we are having issues with IIS 6.0 crashing when many users are accessing our web application and we are thinking that it might have to do with something wrong with how we are using the .NET Connector code. So we wrote the above program and found this issue.

[reiner_hille-doering · Accepted solution]

Hello Pikad,

I found the bug in NCo: as GetConnectionFromPool doesn't open the connection, it can happen that more connection would be created than MaxOpenConnection allows. The additional connection would then block until a connection really closes.

You can work arround the problem with the follwing change: replace the line

qmProxy.Connection = Connection.GetConnectionFromPool(Global.BotNptSap)

with

SyncLock GetType(SAP.Connector.Connection)
  qmProxy.Connection = Connection.GetConnectionFromPool(Global.BotNptSap)
  qmProxy.Connection.Open()
End SyncLock

I'm not yet sure how I can fix the problem in general. Automatically opening the connection in GetConnectionFromPool would be an incompatible change.

Let's see...

[Former Member]

I tried monitoring using SM50 and the thread invoking the RFC occurs as I've explained (one is invoked right away and another is invoked 20 secs afterwards).

My code block calling SAP is:

Try

qmProxy.Connection = Connection.GetConnectionFromPool(Global.BotNptSap)

qmProxy.Zppeh_Inspoper_Getdetail(...)

If retcode.Type <> "E" Then ' Suceed

Trace.Write("OK!")

End If

Catch ex As Exception

Trace.Write(ex.Message)

Finally

Connection.ReturnConnection(qmProxy.Connection)

qmProxy.Connection = Nothing

End Try

I've tried some further investigation and it might have to do with the code creating the threads, where CallRepeat is the function that contains the above code:

Try

For i As Integer = 1 To 2

Dim Thread1 As New System.Threading.Thread(AddressOf CallRepeat)

Thread1.Start()

'' If I include the 3 lines below, everything is ok

'If i = 1 Then

' Thread1.Join()

'End If

Next

Catch ex As Exception

_log.Error(ex.Message)

Finally

End Try

If I include the 3 lines commented out, then everything is ok...

[reiner_hille-doering]

Hm, strange. You code looks perfectly right. Can you tell me what "Global.BotNptSap" is, a Destination or a string? And: is it or constant? (I mean does it change value between calls?)

If it is a Destination, please try "Global.BotNptSap.ConnectionString" instead.

[Former Member]

Hi,

In the R/3 system go to the Transaction SM50 and monitor how the thread's invoking the RFC behave.

(i.e) Here you can check if the RFC is executed one by one or is getting executed simultaneously or if any RFC execution in getting blocked.

I think this will help you to figure out how the 2 threads impact the RFC call made.

Hope this helps you

[reiner_hille-doering]

Can you please post your test code? Maybe you forgot the ReturnConnection() after the RFC call?