I am currently having a performance issue with a .NET application I am
working on. The application consists of a Windows Service which spawns a
number of controller objects. Each of these controllers has a Start method
which is executed on a new thread.
The Start method looks a little bit like this:
while (_running)
{
bool opSuccess = listener.FindMessage(ref messageData, ref
messageFound);
if (opSuccess && messageFound)
{
opSuccess = processor.ProcessMessage(ref messageData);
}
if (opSuccess)
{
opSuccess = dispatcher.DispatchMessage(ref messageData);
}
}
The listener object is configured to look in a certain place (normally a
MessageQueue) for some data to be processed. The processor object does some
work on that data and the dispatcher object sends it off to another
MessageQueue.
Here's the thing. The listener, processor, dispatcher and messageData
objects are all COM objects which each implement a certain custom COM
interface (IListener, IProcessor etc). I think this is what may be killing
the performance of the app. With more than 2 or 3 controller objects (and
therefore threads) running the throughput is lousy - 1 message every 4 or 5
seconds. The "Number of Marshals" .NET performance counter climbs to around
8000 after about 1 minute of the app running. My suspicion is that with more
than 2 or 3 controller objects executing, there is just far too much
marshalling from managed to unmanaged code, and vice versa. The service I'm
writing is intended to be a replacement for a VB6 app which has much the
same functionality, hence the "legacy" COM components. All of these
components are coded in VB6 also.
Can anybody shed some light onto whether my suspicion is correct or not?
Thanks in advance
Simon Jefford
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