File size: 5,862 Bytes
867877e
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
import math
import torch
import torch.nn as nn
from torch.nn import functional as F

try:
    import torch.distributed.nn
    from torch import distributed as dist
    has_distributed = True
except ImportError:
    has_distributed = False

try:
    import horovod.torch as hvd
except ImportError:
    hvd = None

from timm.loss import LabelSmoothingCrossEntropy


def gather_features(
        image_features,
        text_features,
        local_loss=False,
        gather_with_grad=False,
        rank=0,
        world_size=1,
        use_horovod=False
):
    assert has_distributed, 'torch.distributed did not import correctly, please use a PyTorch version with support.'
    if use_horovod:
        assert hvd is not None, 'Please install horovod'
        if gather_with_grad:
            all_image_features = hvd.allgather(image_features)
            all_text_features = hvd.allgather(text_features)
        else:
            with torch.no_grad():
                all_image_features = hvd.allgather(image_features)
                all_text_features = hvd.allgather(text_features)
            if not local_loss:
                # ensure grads for local rank when all_* features don't have a gradient
                gathered_image_features = list(all_image_features.chunk(world_size, dim=0))
                gathered_text_features = list(all_text_features.chunk(world_size, dim=0))
                gathered_image_features[rank] = image_features
                gathered_text_features[rank] = text_features
                all_image_features = torch.cat(gathered_image_features, dim=0)
                all_text_features = torch.cat(gathered_text_features, dim=0)
    else:
        # We gather tensors from all gpus
        if gather_with_grad:
            all_image_features = torch.cat(torch.distributed.nn.all_gather(image_features), dim=0)
            all_text_features = torch.cat(torch.distributed.nn.all_gather(text_features), dim=0)
            # all_image_features = torch.cat(torch.distributed.nn.all_gather(image_features, async_op=True), dim=0)
            # all_text_features = torch.cat(torch.distributed.nn.all_gather(text_features, async_op=True), dim=0)
        else:
            gathered_image_features = [torch.zeros_like(image_features) for _ in range(world_size)]
            gathered_text_features = [torch.zeros_like(text_features) for _ in range(world_size)]
            dist.all_gather(gathered_image_features, image_features)
            dist.all_gather(gathered_text_features, text_features)
            if not local_loss:
                # ensure grads for local rank when all_* features don't have a gradient
                gathered_image_features[rank] = image_features
                gathered_text_features[rank] = text_features
            all_image_features = torch.cat(gathered_image_features, dim=0)
            all_text_features = torch.cat(gathered_text_features, dim=0)

    return all_image_features, all_text_features


class ClipLoss(nn.Module):

    def __init__(
            self,
            local_loss=False,
            gather_with_grad=False,
            cache_labels=False,
            rank=0,
            world_size=1,
            use_horovod=False,
            smoothing=0.,
    ):
        super().__init__()
        self.local_loss = local_loss
        self.gather_with_grad = gather_with_grad
        self.cache_labels = cache_labels
        self.rank = rank
        self.world_size = world_size
        self.use_horovod = use_horovod
        self.label_smoothing_cross_entropy = LabelSmoothingCrossEntropy(smoothing=smoothing) if smoothing > 0 else None

        # cache state
        self.prev_num_logits = 0
        self.labels = {}

    def forward(self, image_features, text_features, logit_scale=1.):
        device = image_features.device
        if self.world_size > 1:
            all_image_features, all_text_features = gather_features(
                image_features, text_features,
                self.local_loss, self.gather_with_grad, self.rank, self.world_size, self.use_horovod)

            if self.local_loss:
                logits_per_image = logit_scale * image_features @ all_text_features.T
                logits_per_text = logit_scale * text_features @ all_image_features.T
            else:
                logits_per_image = logit_scale * all_image_features @ all_text_features.T
                logits_per_text = logits_per_image.T
        else:
            logits_per_image = logit_scale * image_features @ text_features.T
            logits_per_text = logit_scale * text_features @ image_features.T
        # calculated ground-truth and cache if enabled
        num_logits = logits_per_image.shape[0]
        if self.prev_num_logits != num_logits or device not in self.labels:
            labels = torch.arange(num_logits, device=device, dtype=torch.long)
            if self.world_size > 1 and self.local_loss:
                labels = labels + num_logits * self.rank
            if self.cache_labels:
                self.labels[device] = labels
                self.prev_num_logits = num_logits
        else:
            labels = self.labels[device]
        
        if self.label_smoothing_cross_entropy:
            total_loss = (
                self.label_smoothing_cross_entropy(logits_per_image, labels) +
                self.label_smoothing_cross_entropy(logits_per_text, labels)
                ) / 2
        else:
            total_loss = (
                F.cross_entropy(logits_per_image, labels) +
                F.cross_entropy(logits_per_text, labels)
                ) / 2
            
        acc = None
        i2t_acc = (logits_per_image.argmax(-1) == labels).sum() / len(logits_per_image)
        t2i_acc = (logits_per_text.argmax(-1) == labels).sum() / len(logits_per_text)
        acc = {"i2t": i2t_acc, "t2i": t2i_acc}
        return total_loss, acc