Strange behaviour of MTS

[Irfan Gowani]

we have got ASP client and VB components.All the components are running under
COM+ with apartment threaded model. whenever a fewer number of ASP clients
(lets say 10) give requests through IIS, every thing works fine and the components
also work. when the ASP clients gets increased, we see a strange behaviour
from the visual basic components as they gets halt and the transaction gets
stuck and couldnt get completed or aborted.

During this event, we can also see the locks in the database.Because of
this situation, no more request can be fulfiled. This situation remains until
we kill the mtx process and then only the transaction gets aborted.This situation
doesnt come very consistantly.

we are using windows 2000 server (SP2), Visual Basic 6.0 (SP2), COM+,ADO
2.5,MSXML 2.0, SQL Server 2000 (SP2) and IIS 5.0 for all the develpment and
deployment environment.

There is a firewall behind COM+ server. OUR IIS server is CIS enabled. All
request goes through http at port 80 from IIS server to COM+ server.

we have also increased the transaction time out and MSDTC Log size.


Microsoft says that "a Visual FoxPro Component Object Model (COM) server
may stop responding under a heavy load when it is run using Microsoft Transaction
Server (MTS) under Windows 2000.Microsoft has confirmed this to be a bug
in the Microsoft products. This bug was corrected in Visual Studio 6.0 Service
Pack 5".

I dont know if our problem relates with the Visual FoxPro problem but we
are already using Visual Studio 6.0 Service Pack 5.

Microsoft again says that "COM+ server applications may stop responding (hang)
when they are under a heavy load on multiprocessor systems. The threads in
the COM+ server application (Dllhost.exe) are stuck in a loop when the COM+
server performs security checks.To resolve this problem, obtain the latest
service pack for Windows 2000."

again we dont have this multiprocessor systems but we do have latest windows
2000 service pack.

There are other examples closely related to our problem but they all say
to get the latest visual studio service pack and windows 2000 service pack.We
certainly have got both the service packs.

Please reply me as early as possible.
Thanks in advance

[Paul Clement]

On 4 Jun 2002 00:09:20 -0800, "Irfan Gowani" <igowani@khi.comsats.net.pk> wrote:

¤
¤ we have got ASP client and VB components.All the components are running under
¤ COM+ with apartment threaded model. whenever a fewer number of ASP clients
¤ (lets say 10) give requests through IIS, every thing works fine and the components
¤ also work. when the ASP clients gets increased, we see a strange behaviour
¤ from the visual basic components as they gets halt and the transaction gets
¤ stuck and couldnt get completed or aborted.
¤

If you haven't already done so make sure that the Retain in Memory and Unattended Execution options
are checked in your component projects:

PRB: VB DLL Has Memory Leaks and Crashes in COM+ if 'Retain In Memory' Not Set (Q264957)
http://support.microsoft.com/default...;EN-US;q264957


Paul ~~~ pclement@ameritech.net
Microsoft MVP (Visual Basic)