Question

I have a performance counters reporter class that holds in multiple members different lists. Is there a neat way to tell the class the memory limit of its consumption (to be bullet proof case the lists will be pushed with enormous amount of data), or should I go to each member and change it to blocked list? (and this is less dynamic in a way)

Answer 1

What you’re asking doesn’t make sense. How could a class limit its memory consumption?

Consider: you have a public property that is a list of data. You set the value of that property to be a 2GB set of data but the class is limited to 100MB. How does the class decide what data to throw away? What happens to the data that’s thrown away? How does the rest of your program deal with the fact that half its data has disappeared?

None of these questions are sensibly answered, because each program will have a different answer. For that reason, you’d have to implement such logic yourself.

However, more importantly, you should consider this: if I create a List<int> that contains 2GB of data, and assign this list to a property of your “reporter class,” the memory consumption of your reporter class doesn’t change. This is because your reporter class has a property that is a List<int>, and what that means is that the property stores the memory address of a List<int> that is held somewhere else in the heap. This memory address – a pointer to what we consider the “value” of the property – is fixed according to the architecture of your machine/application and will never change. It’s the same size when your pointer is null as it is when the pointer points to a 2GB list. And so in that sense, the memory consumption of your class itself won’t be as big as you think.

You can redefine the question to say “when calculating consumption, include all objects pointed to by my properties” but this has its own problems. What happens if you assign the List<int> to a property on two different objects, each with its own memory limit?

Also, if your reporting class has two properties that could hold large data, and I assign large values to each, how do you decide what to throw away? If I have a 100MB limit for the class, and assign 200MB of data to one property and 1GB of data to the other, which data do I truncate? What would happen if I then cleared one of the properties – I now have “spare” memory consumption but data is irretrievably lost.

In short: this is a very complex requirement to request. You’d have to create your own logic to implement this, and it’s unlikely you’ll find anything “standard” to handle it, because no two implementations would be the same.