Periodical WMI Query Causes Memory Leak?

Question

I am fairly new to the .NET programming and I am currently developing a computer health monitoring system which is in its infant stage now. I will be using C# 2010 and querying computer information by using WMI queries.

Before I could further develop the application, I have created a mini test app to test out my classes and its methods. The flow of the test app is as follow:

1. App startup
2. Input hostname, username and password
3. Query button clicked and the querying methods fired.
4. A textfield on my UI gets updated, printing out the result of the queries.

I have a class called Machine, which contains properties such as the CPU Name, and some update-able properties like the current CPU usage. In that class, I have 2 main methods, GetStaticSysInfo and GetDynamicSysInfo, where the first method queries the system info that does not change over time, and the later one queries information like CPU and memory usage. I have another method named Refresh that I use to wrap around the GetDynamicSysInfo method.

As I am using WPF for my UI, I have used the DispatcherTimer to periodically queries the machine, and prints the updated info to the textfield on the UI after the Query button has been clicked. However, I noticed that each of the time I called machine.Refresh(), the memory usage of the app increases by a bit (few hundred KBs). I can't really figure out what's wrong with the program and I would appreciate that someone could provide some advices on this.

Please let me know if you need more information, or any portions of the code.

Thanks in advance.

EDIT: I have added a GC.Collect() on the Timer_Tick method, and it seems like the memory usage still climbs but it is lowered once every few timer ticks. It is still increasing, but at a slower rate. Is this the correct way of doing it and will it impair performance in the long run?

Answer 1

Except for diagnosis purposes you should never call GC.Collect(). The runtime has much better algorithms for when the GC should run. Also, calling Collect() too often can result in objects being promoted to 1st or 2nd generation, which actually means they are collected more slowly after they are not used anymore, i.e. increasing your memory footprint.

If the memory goes down again (to the previous value) after manually collecting, then you have no memory leak. Since the GC doesn't run all the time, you will have increased memory in between GC runs. That is no cause for concern.