You can use Microsoft's CLR Profiler to attach to the application while it is running and determine how many objects are in memory and how much memory is used by each type of object.
http://www.microsoft.com/downloads/details.aspx?familyid=a362781c-3870-43be-8926-862b40aa0cd0&displaylang=en
If you do not see any excessive allocations in this tool, then it is probably working correctly.
> I had a discussing the other day and someone argued that the increase in memory usage (without release) doesn't necessarily mean that it is a memory leak
That is often true. .NET often holds on to unused memory and reuses it for furture allocations instead of returning it to the operating system. Thus, the numbers in task manager can be higher than the actual amount of memory currrently used by all of the live objects in your application.
http://www.microsoft.com/downloads/details.aspx?familyid=a362781c-3870-43be-8926-862b40aa0cd0&displaylang=en
If you do not see any excessive allocations in this tool, then it is probably working correctly.
> I had a discussing the other day and someone argued that the increase in memory usage (without release) doesn't necessarily mean that it is a memory leak
That is often true. .NET often holds on to unused memory and reuses it for furture allocations instead of returning it to the operating system. Thus, the numbers in task manager can be higher than the actual amount of memory currrently used by all of the live objects in your application.