Memory wasting problem with List?

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I have a List<bitmap>, I tried adding to that list about 60 Bitmap objects, and opened Task Manager to see how much memory it used, after I pressed on some button to call Remove(), RemoveRange, ... methods of the List<bitmap> and see if the used memory was decreased (freed), however I didn't see any change in memory used by my application.

Could you please give me a solution for this? I have tried using System.GC.Collect() periodically (with a cycle of about 5 seconds), it seems to work OK, but some people say it's not good. I don't know why, because it really helps me free unused memory, I would like to know another solution if that is not good.

Your help would be highly appreciated!
Thanks.

VipHaLong

Posted 18-Mar-13 0:10am

supernorb

Updated 18-Mar-13 0:11am

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OriginalGriff · Accepted Answer · 2013-03-18T00:20:00

Solution 1

It's not good to call the GC yourself - you shouldn't need to if you obey the rules.
In this case, you are adding Bitmaps - which are large objects and which support the Dispose method.
So when you remove them from your list and stop needing them, get rid of them then.

C#

private void remove(List<Bitmap> list, int index)
    {
    if (list.Count > index)
        {
        Image i = list[index];
        list.RemoveAt(index);
        i.Dispose();
        }
    }

However that won't reduce the memory shown in the Task Manager - once .NET expands the heap, it doesn't reduce it.

Posted 18-Mar-13 0:20am

OriginalGriff

Comments

supernorb 18-Mar-13 6:25am

But what I want is it can reduce the memory viewed in Task Manager, does your solution mean that we shouldn't use Remove(), RemoveRange() methods of List class? Thanks!

OriginalGriff 18-Mar-13 6:30am

No, you can use what you want - but if an object you are finished with implements Dispose (as Bitmap does) then you should call it to release resources.

supernorb 18-Mar-13 8:08am

But as you said even when using Dispose() the memory shown in Task manager is still not decreased, if so my application may use up to 300-400 MB

OriginalGriff 18-Mar-13 8:25am

Don't worry about it - it will be available for other use within your app, and will only grow again when that is used up.