File size: 7,276 Bytes
22871e7
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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
from torch.nn.parallel import DistributedDataParallel
from torch.nn.parallel.distributed import _find_tensors
import torch.optim
import torch.utils.data
import torch
from packaging import version

class DDP(DistributedDataParallel):
    """
    Override the forward call in lightning so it goes to training and validation step respectively
    """

    def forward(self, *inputs, **kwargs):  # pragma: no cover
        if version.parse(torch.__version__[:6]) < version.parse("1.11"):
            self._sync_params()
            inputs, kwargs = self.scatter(inputs, kwargs, self.device_ids)
            assert len(self.device_ids) == 1
            if self.module.training:
                output = self.module.training_step(*inputs[0], **kwargs[0])
            elif self.module.testing:
                output = self.module.test_step(*inputs[0], **kwargs[0])
            else:
                output = self.module.validation_step(*inputs[0], **kwargs[0])
            if torch.is_grad_enabled():
                # We'll return the output object verbatim since it is a freeform
                # object. We need to find any tensors in this object, though,
                # because we need to figure out which parameters were used during
                # this forward pass, to ensure we short circuit reduction for any
                # unused parameters. Only if `find_unused_parameters` is set.
                if self.find_unused_parameters:
                    self.reducer.prepare_for_backward(list(_find_tensors(output)))
                else:
                    self.reducer.prepare_for_backward([])
        else:
            from torch.nn.parallel.distributed import \
                logging, Join, _DDPSink, _tree_flatten_with_rref, _tree_unflatten_with_rref
            with torch.autograd.profiler.record_function("DistributedDataParallel.forward"):
                if torch.is_grad_enabled() and self.require_backward_grad_sync:
                    self.logger.set_runtime_stats_and_log()
                    self.num_iterations += 1
                    self.reducer.prepare_for_forward()

                # Notify the join context that this process has not joined, if
                # needed
                work = Join.notify_join_context(self)
                if work:
                    self.reducer._set_forward_pass_work_handle(
                        work, self._divide_by_initial_world_size
                    )

                # Calling _rebuild_buckets before forward compuation,
                # It may allocate new buckets before deallocating old buckets
                # inside _rebuild_buckets. To save peak memory usage,
                # call _rebuild_buckets before the peak memory usage increases
                # during forward computation.
                # This should be called only once during whole training period.
                if torch.is_grad_enabled() and self.reducer._rebuild_buckets():
                    logging.info("Reducer buckets have been rebuilt in this iteration.")
                    self._has_rebuilt_buckets = True

                # sync params according to location (before/after forward) user
                # specified as part of hook, if hook was specified.
                buffer_hook_registered = hasattr(self, 'buffer_hook')
                if self._check_sync_bufs_pre_fwd():
                    self._sync_buffers()

                if self._join_config.enable:
                    # Notify joined ranks whether they should sync in backwards pass or not.
                    self._check_global_requires_backward_grad_sync(is_joined_rank=False)

                inputs, kwargs = self.scatter(inputs, kwargs, self.device_ids)
                if self.module.training:
                    output = self.module.training_step(*inputs[0], **kwargs[0])
                elif self.module.testing:
                    output = self.module.test_step(*inputs[0], **kwargs[0])
                else:
                    output = self.module.validation_step(*inputs[0], **kwargs[0])

                # sync params according to location (before/after forward) user
                # specified as part of hook, if hook was specified.
                if self._check_sync_bufs_post_fwd():
                    self._sync_buffers()

                if torch.is_grad_enabled() and self.require_backward_grad_sync:
                    self.require_forward_param_sync = True
                    # We'll return the output object verbatim since it is a freeform
                    # object. We need to find any tensors in this object, though,
                    # because we need to figure out which parameters were used during
                    # this forward pass, to ensure we short circuit reduction for any
                    # unused parameters. Only if `find_unused_parameters` is set.
                    if self.find_unused_parameters and not self.static_graph:
                        # Do not need to populate this for static graph.
                        self.reducer.prepare_for_backward(list(_find_tensors(output)))
                    else:
                        self.reducer.prepare_for_backward([])
                else:
                    self.require_forward_param_sync = False

            # TODO: DDPSink is currently enabled for unused parameter detection and
            # static graph training for first iteration.
            if (self.find_unused_parameters and not self.static_graph) or (
                    self.static_graph and self.num_iterations == 1
            ):
                state_dict = {
                    'static_graph': self.static_graph,
                    'num_iterations': self.num_iterations,
                }

                output_tensor_list, treespec, output_is_rref = _tree_flatten_with_rref(
                    output
                )
                output_placeholders = [None for _ in range(len(output_tensor_list))]
                # Do not touch tensors that have no grad_fn, which can cause issues
                # such as https://github.com/pytorch/pytorch/issues/60733
                for i, output in enumerate(output_tensor_list):
                    if torch.is_tensor(output) and output.grad_fn is None:
                        output_placeholders[i] = output

                # When find_unused_parameters=True, makes tensors which require grad
                # run through the DDPSink backward pass. When not all outputs are
                # used in loss, this makes those corresponding tensors receive
                # undefined gradient which the reducer then handles to ensure
                # param.grad field is not touched and we don't error out.
                passthrough_tensor_list = _DDPSink.apply(
                    self.reducer,
                    state_dict,
                    *output_tensor_list,
                )
                for i in range(len(output_placeholders)):
                    if output_placeholders[i] is None:
                        output_placeholders[i] = passthrough_tensor_list[i]

                # Reconstruct output data structure.
                output = _tree_unflatten_with_rref(
                    output_placeholders, treespec, output_is_rref
                )
        return output