User is able to use C# classes generated by SWIG tool.

Memory management

The C# Garbage Collector (GC) manages only managed memory, ensuring efficient allocation and deallocation of resources within that space.

In the case of the enrollment-sdk, objects in managed memory are typically small. However, these objects often create significantly larger amounts of unmanaged memory, contributing to the overall process memory usage.

Since managed objects are small, the GC is triggered less frequently, which can lead to high process memory consumption due to unmanaged memory growth.

The following sections outline solutions to address this challenge. You can choose one or more approaches that best suit your use case.

Use small heap

If your C# application uses only small objects, consider setting the maximum GC heap memory as low as possible using the HeapHardLimit configuration.

This will cause the GC to run more frequently, ensuring that unmanaged memory is released more effectively.

Use using statement

Use the using statement for each enrollment-sdk variable individually. Avoid chaining multiple enrollment-sdk variables in a single using statement.

Code

Code with using

// Please note that the sample source code
// provided here is for informational purposes
// only and should not be used for production
// purposes without proper testing and modification.
private static Face GetFace(byte[] img)
{
    var capture = new FaceCapture(Image.Decode(new Bytes(img)));
 
    var cfg = new FaceDetector.Config();
    var detector = new FaceDetector(cfg);
    var faces = capture.DetectWith(detector);
 
    if (faces.Count == 0)
        return default;
 
    var face = faces[0];
    return face;
}

// Please note that the sample source code
// provided here is for informational purposes
// only and should not be used for production
// purposes without proper testing and modification.
private static Face GetFace(byte[] img)
{
    using var bytes = new Bytes(img);
    using var image = Image.Decode(bytes);
    using var capture = new FaceCapture(image);
 
    using var cfg = new FaceDetector.Config();
    using var detector = new FaceDetector(cfg);
    using var faces = capture.DetectWith(detector);
 
    if (faces.Count == 0)
        return default;
 
    // IMPORTANT
    // Because the Face object is returned,
    // we can not use `using` because
    // `using` will delete native memory
    // on function return
    var face = faces[0];
    return face;
}

Force GC

// Please note that the sample source code provided here is for informational purposes
// only and should not be used for production purposes without proper testing and
// modification.
static void TriggerGarbageCollector()
{
    // Set process memory limit to 2GB
    long maxMemoryLimit = 2L * 1024 * 1024 * 1024;
 
    while (true)
    {
        try
        {
 
            long totalMemory = Process.GetCurrentProcess().WorkingSet64;
 
            if (totalMemory > maxMemoryLimit)
            {
                // Trigger garbage collection
                GC.Collect();
            }
 
            // Check every second
            Thread.Sleep(1000);
        }
        catch (ThreadInterruptedException)
        {
            break;
        }
    }
}

Use it in main function of your application

var memoryLimiter = new Thread(new ThreadStart(TriggerGarbageCollector));

memoryLimiter.Start();

Exception Propagation

Exception from C# implementation of Interface	Exception in Enrollment SDK native code	Exception propagated back to C#
EnrollmentException and its subclasses	EnrollmentException and its subclasses	EnrollmentException and its subclasses
ApplicationException	std::runtime_error	ApplicationException
ArithmeticException	std::runtime_error	ApplicationException
DivideByZeroException	std::domain_error	ArgumentException
IndexOutOfRangeException	std::out_of_range	IndexOutOfRangeException
InvalidCastException	std::runtime_error	ApplicationException
InvalidOperationException	std::logic_error	ApplicationException
IOException	std::ios_base::failure	ApplicationException
NullReferenceException	std::runtime_error	ApplicationException
OutOfMemoryException	std::runtime_error	ApplicationException
OverflowException	std::overflow_error	OverflowException
SystemException	std::runtime_error	ApplicationException
ArgumentException	std::invalid_argument	ArgumentException
ArgumentNullException	std::invalid_argument	ArgumentException
ArgumentOutOfRangeException	std::invalid_argument	ArgumentException
Exception	std::runtime_error	ApplicationException