CODEWITHSUNDEEP
multithreadingwinformsinvoke
BLiTZWiNG
BLiTZWiNG

Reputation: 33

Invoke progressively getting slower

I've been investigating performance issues in my app, and it boils down to the time taken to call Invoke progressively getting longer. I am using System.Diagnostics.Stopwatch to time the Invoke call itself, and while it starts off at 20ms, after a few hundred calls it is around 4000ms. Logging shows the time steadily increasing (at first by ~2ms per call, then by ~100ms and more). I have three Invokes, all are exhibiting the same behaviour.

I am loading medical images, and I need to keep my UI responsive while doing so, hence the use of a background worker, where I can load and process images, but once loaded they need to be added to the man UI for the user to see.

The problem didn't present itself until I tried to load a study of over 800 images. Previously my test sets have been ~100 images, ranging in total size from 400MB to 16GB. The problem set is only 2GB in size and takes close to 10 minutes to approach 50%, and the 16GB set loads in ~30s total, thus ruling out total image size as the issue. For reference my development machine has 32GB RAM. I have ensured that it is not the contents of the invoked method by commenting the entire thing out.

What I want to understand is how is it possible for the time taken to invoke to progressively increase? Is this actually a thing? My call stacks are not getting deeper, Number of threads is consistent, what resource is being consumed to cause this? What am I missing!?

public void UpdateThumbnailInfo(Thumbnail thumb, ThumbnailInfo info)
{
    if (InvokeRequired)
        {
            var sw = new Stopwatch();
            sw.Start();
            Invoke((Action<Thumbnail, ThumbnailInfo>) UpdateThumbnailInfo, thumb, info);
            Log.Debug("Update Thumbnail Info Timer: {Time} ms - {File}", (int) sw.ElapsedMilliseconds, info.Filename);
        }
        else
        {
            // Do stuff here
        }
    }

Upvotes: 2

Views: 51

Answers (1)

inquisitive
inquisitive

Reputation: 3649

Looks like you are calling UpdateThumbnailInfo from a different thread. If so, then this is the expected behavior. What is happening is you are queuing hundreds of tasks on the UI thread. For every loaded image the UI needs to do a lot of things, so as the number of images increases, the overall operations grow slow.

A few things that you can do: * Use BeginInvoke in place of Invoke. As your function is void type, you will not need EndInvoke * Use SuspendLayout and ResumeLayout to prevent UI from incrementally updating, and rather update everything once when all images are loaded.

Upvotes: 1

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