Question

I’m transferring images from a high-FPS camera into a memory buffer (a List), and as those images are pretty large, the computer runs out of memory pretty quickly.

What I would like to do is to stop the transfer some time before the application runs out of memory. During my testing, I have found it to be consistent with the “Free Physical Memory” indicator getting close to zero.

Now the problem is that I can’t find a way actually to get this value programmatically; in XP, it is not even displayed anywhere (just in the Vista/7 task manager).

I have tried all the ways I could find (WMI, performance counters, MemoryStatus, …), but everything I got from those was just the “Available Physical Memory,” which is of course not the same.

Any ideas?

Update
Unfortunately, I need the data to be in memory (yes, I know I can’t guarantee it will be in physical memory, but still), because the data is streamed in real-time and I need to preview it in memory after it’s been stored there.

Answer 1

I’m late to the party, but have you considered using the System.Runtime.MemoryFailPoint class? It does a bunch of stuff to ensure that the requested allocation would succeed and throws InsufficientMemoryException if it fails; you can catch this and stop your transfer. You can probably predict an average size of incoming frames and try to allocate 3 or 4 of them, then stop acquisition when a failure is made. Maybe something like this?

const int AverageFrameSize = 10 * 1024 * 1024 // 10MB

void Image_OnAcquired(...)
{
    try
    {
        var memoryCheck = new MemoryFailPoint(AverageFrameSize * 3);
    }
    catch (InsufficientMemoryException ex)
    {
        _camera.StopAcquisition();
        StartWaitingForFreeMemory();
        return;
    }

    // if you get here, there's enough memory for at least a few
    // more frames
}

I doubt it’d be 100% foolproof, but it’s a start. It’s definitely more reliable than the performance counter for reasons that are explained in the other answers.