Hello,
I am using a network for object detection (retinanet) and after some iterations (not always the same number) I end up with an OOM error.
Here is the Traceback:
Traceback (most recent call last):

  File "train_uda.py", line 427, in <module>

    main()

  File "train_uda.py", line 170, in main

    train_loss = train(dataloader_train, dataloader_uda, retinanet, optimizer, writer, epoch_num, train_hist, start_uda)

  File "train_uda.py", line 250, in train

    uda_loss = uda(model, dataloader_uda, uda_iter, iter_u, writer, (iter_num + len(dataloader_train) * epoch))

  File "train_uda.py", line 400, in uda

    classification_loss, regression_loss = model([unlabeled['augment'].cuda().float(), ground_truth])

  File "/home/rvandeghen/miniconda3/envs/tfe/lib/python3.6/site-packages/torch/nn/modules/module.py", line 532, in __call__

    result = self.forward(*input, **kwargs)

  File "/home/rvandeghen/miniconda3/envs/tfe/lib/python3.6/site-packages/torch/nn/parallel/data_parallel.py", line 150, in forward

    return self.module(*inputs[0], **kwargs[0])

  File "/home/rvandeghen/miniconda3/envs/tfe/lib/python3.6/site-packages/torch/nn/modules/module.py", line 532, in __call__

    result = self.forward(*input, **kwargs)

  File "/home/rvandeghen/TFE/Codes/retinanet/retinanet/model.py", line 268, in forward

    return self.focalLoss(classification, regression, anchors, annotations)

  File "/home/rvandeghen/miniconda3/envs/tfe/lib/python3.6/site-packages/torch/nn/modules/module.py", line 532, in __call__

    result = self.forward(*input, **kwargs)

  File "/home/rvandeghen/TFE/Codes/retinanet/retinanet/losses.py", line 91, in forward

    IoU = calc_iou(anchors[0, :, :], bbox_annotation[:, :4]) # num_anchors x num_annotations

  File "/home/rvandeghen/TFE/Codes/retinanet/retinanet/losses.py", line 16, in calc_iou

    ua = torch.unsqueeze((a[:, 2] - a[:, 0]) * (a[:, 3] - a[:, 1]), dim=1) + area - iw * ih

RuntimeError: CUDA out of memory. Tried to allocate 1.76 GiB (GPU 0; 10.76 GiB total capacity; 8.95 GiB already allocated; 1017.56 MiB free; 8.98 GiB reserved in total by PyTorch)

And the code where it happens:
def calc_iou(a, b):

    area = (b[:, 2] - b[:, 0]) * (b[:, 3] - b[:, 1])

    iw = torch.min(torch.unsqueeze(a[:, 2], dim=1), b[:, 2]) - torch.max(torch.unsqueeze(a[:, 0], 1), b[:, 0])

    ih = torch.min(torch.unsqueeze(a[:, 3], dim=1), b[:, 3]) - torch.max(torch.unsqueeze(a[:, 1], 1), b[:, 1])

    iw = torch.clamp(iw, min=0)

    ih = torch.clamp(ih, min=0)

    ua = torch.unsqueeze((a[:, 2] - a[:, 0]) * (a[:, 3] - a[:, 1]), dim=1) + area - iw * ih

    ua = torch.clamp(ua, min=1e-8)

    intersection = iw * ih

    IoU = intersection / ua

    return IoU

class FocalLoss(nn.Module):

    #def __init__(self):

    def forward(self, classifications, regressions, anchors, annotations):

        alpha = 0.25

        gamma = 2.0

        batch_size = classifications.shape[0]

        classification_losses = []

        regression_losses = []

        anchor = anchors[0, :, :]

        anchor_widths  = anchor[:, 2] - anchor[:, 0]

        anchor_heights = anchor[:, 3] - anchor[:, 1]

        anchor_ctr_x   = anchor[:, 0] + 0.5 * anchor_widths

        anchor_ctr_y   = anchor[:, 1] + 0.5 * anchor_heights

        for j in range(batch_size):

            classification = classifications[j, :, :]

            regression = regressions[j, :, :]

            bbox_annotation = annotations[j, :, :]

            bbox_annotation = bbox_annotation[bbox_annotation[:, 4] != -1]

            # classification in [1e-4, 1-1e-4]

            classification = torch.clamp(classification, 1e-4, 1.0 - 1e-4)

            # if no annotation

            if bbox_annotation.shape[0] == 0:

                if torch.cuda.is_available():

                    alpha_factor = torch.ones(classification.shape).cuda() * alpha

                    alpha_factor = 1. - alpha_factor

                    focal_weight = classification

                    focal_weight = alpha_factor * torch.pow(focal_weight, gamma)

                    bce = -(torch.log(1.0 - classification))

                    cls_loss = focal_weight * bce

                    regression_losses.append(torch.tensor(0).float().cuda())

                    classification_losses.append(cls_loss.sum())

                    del regression

                else:

                    alpha_factor = torch.ones(classification.shape) * alpha

                    alpha_factor = 1. - alpha_factor

                    focal_weight = classification

                    focal_weight = alpha_factor * torch.pow(focal_weight, gamma)

                    bce = -(torch.log(1.0 - classification))

                    cls_loss = focal_weight * bce

                    regression_losses.append(torch.tensor(0).float())

                    classification_losses.append(cls_loss.sum())

                    del regression

                continue

            IoU = calc_iou(anchors[0, :, :], bbox_annotation[:, :4]) # num_anchors x num_annotations

            IoU_max, IoU_argmax = torch.max(IoU, dim=1) # num_anchors x 1

            #import pdb

            #pdb.set_trace()

            # compute the loss for classification

            targets = torch.ones(classification.shape) * -1

            

            if torch.cuda.is_available():

                targets = targets.cuda()

            # targets < 0.4 set to 0

            targets[torch.lt(IoU_max, 0.4), :] = 0

            # print(targets.shape[0] - (targets==0).sum())

            # indices = IoU > 0.5

            positive_indices = torch.ge(IoU_max, 0.5)

            num_positive_anchors = positive_indices.sum()

            assigned_annotations = bbox_annotation[IoU_argmax, :]

            targets[positive_indices, :] = 0

            targets[positive_indices, assigned_annotations[positive_indices, 4].long()] = 1

            if torch.cuda.is_available():

                alpha_factor = torch.ones(targets.shape).cuda() * alpha

            else:

                alpha_factor = torch.ones(targets.shape) * alpha

            alpha_factor = torch.where(torch.eq(targets, 1.), alpha_factor, 1. - alpha_factor)

            focal_weight = torch.where(torch.eq(targets, 1.), 1. - classification, classification)

            focal_weight = alpha_factor * torch.pow(focal_weight, gamma)

            bce = -(targets * torch.log(classification) + (1.0 - targets) * torch.log(1.0 - classification))

            # cls_loss = focal_weight * torch.pow(bce, gamma)

            cls_loss = focal_weight * bce

            if torch.cuda.is_available():

                cls_loss = torch.where(torch.ne(targets, -1.0), cls_loss, torch.zeros(cls_loss.shape).cuda())

            else:

                cls_loss = torch.where(torch.ne(targets, -1.0), cls_loss, torch.zeros(cls_loss.shape))

            classification_losses.append(cls_loss.sum()/torch.clamp(num_positive_anchors.float(), min=1.0))

            # compute the loss for regression

            if positive_indices.sum() > 0:

                assigned_annotations = assigned_annotations[positive_indices, :]

                anchor_widths_pi = anchor_widths[positive_indices]

                anchor_heights_pi = anchor_heights[positive_indices]

                anchor_ctr_x_pi = anchor_ctr_x[positive_indices]

                anchor_ctr_y_pi = anchor_ctr_y[positive_indices]

                gt_widths  = assigned_annotations[:, 2] - assigned_annotations[:, 0]

                gt_heights = assigned_annotations[:, 3] - assigned_annotations[:, 1]

                gt_ctr_x   = assigned_annotations[:, 0] + 0.5 * gt_widths

                gt_ctr_y   = assigned_annotations[:, 1] + 0.5 * gt_heights

                # clip widths to 1

                gt_widths  = torch.clamp(gt_widths, min=1)

                gt_heights = torch.clamp(gt_heights, min=1)

                targets_dx = (gt_ctr_x - anchor_ctr_x_pi) / anchor_widths_pi

                targets_dy = (gt_ctr_y - anchor_ctr_y_pi) / anchor_heights_pi

                targets_dw = torch.log(gt_widths / anchor_widths_pi)

                targets_dh = torch.log(gt_heights / anchor_heights_pi)

                targets = torch.stack((targets_dx, targets_dy, targets_dw, targets_dh))

                targets = targets.t()

                if torch.cuda.is_available():

                    targets = targets/torch.Tensor([[0.1, 0.1, 0.2, 0.2]]).cuda()

                else:

                    targets = targets/torch.Tensor([[0.1, 0.1, 0.2, 0.2]])

                negative_indices = 1 + (~positive_indices)

                regression_diff = torch.abs(targets - regression[positive_indices, :])

                regression_loss = torch.where(

                    torch.le(regression_diff, 1.0 / 9.0),

                    0.5 * 9.0 * torch.pow(regression_diff, 2),

                    regression_diff - 0.5 / 9.0

                )

                regression_losses.append(regression_loss.mean())

            else:

                if torch.cuda.is_available():

                    regression_losses.append(torch.tensor(0).float().cuda())

                else:

                    regression_losses.append(torch.tensor(0).float())

        return torch.stack(classification_losses).mean(dim=0, keepdim=True), torch.stack(regression_losses).mean(dim=0, keepdim=True)

I tried to solve it with many things but it never works.
Thank you!
PS: this only happens when there are some images without annotations in my dataset.