I am using version 5.0.1321.1 of EasyOpcDANet.dll to poll ~ 1800 tags from an OPC server, some at a rate of 500 ms and some at a rate of 100 ms, and I think I'm experiencing a memory leak in the driver.

I use the SubscribeMultipleItems method to subscribe to the 1800 tags at program start. After about a day, the program is using well over a gig of virtual memory. We log both the private bytes (unmanaged) and the .NET CLR bytes in all heaps. The .NET CLR bytes in all heaps flututates up and down as you would expect over normally GC cycles, but on average remains relatively constant. The private bytes, however, increase linearly at a rate of about 50 megabytes/hour. We are not using any unmanaged code from our application, which leads me to believe it is an issue with the EasyOpcDANet.dll.

Is there anything we have to do to release unmanged memory?

Please advise, thanks.

Thanks for the prompt response.

I had a typo in my post - should say 500ms and 1000ms, not 500ms and 100ms.

We notice that eventually the EasyOPCDANet driver will stop sending updates (or sending the same old value over and over, I'm not sure, but I would suspect the former).

I will put in some logging to determine whether the timestamps start lagging behind the current time.

The system we're running on is a Windows Server 2k3 box with 4 GB of RAM and 4 processors with the overall CPU percentage usually around 10-15%.

I'm attaching a screenshot of the memory profile. I had to restart the program twice in the shown interval (indicated by the sudden drop in memory). You can see the steady increase of the dark blue line (private bytes). The light blue line is process elapsed time. The green line is managed memory usage in all heaps (ranges between 46 megs and 57 megs)

It seems that I have been able to reproduce the problem, or at least something very similar. As such, no further action is required on your side right now. I will investigate into what could be the cause.