"Computing & saving fg bbox masks" step leading to process being killed when using sparse images

[hadillivvy]

When I provide the training script with sparse sequential images (approx 20 for the scene), the "Computing & saving fg bbox masks" step taking a long time to finish and it doesn't get through 1 or 2 iterations before using up all the computer's 32GB RAM space. How can I provide the training script with sparse images to do the task?