[shardformer] Pytree fix (#4533)

* pytree test

* test bert

* test bert

* test bert

* revise

* add register

* add register

colossalai/pipeline/schedule/_utils.py

@@ -1,9 +1,59 @@
-from typing import Any, List, Optional
+from collections import OrderedDict
+from typing import Any, List, Optional, Tuple
 
 import torch
 import torch.cuda
 from torch.nn import Module
-from torch.utils._pytree import tree_flatten, tree_map, tree_unflatten
+from torch.utils._pytree import (
+    SUPPORTED_NODES,
+    LeafSpec,
+    TreeSpec,
+    _is_leaf,
+    _register_pytree_node,
+    tree_flatten,
+    tree_map,
+    tree_unflatten,
+)
+
+
+# this register are for torch under version 1.13.1, maybe removed in the future
+def _odict_flatten(d: 'OrderedDict[Any, Any]') -> Tuple[List[Any], Any]:
+    return list(d.values()), list(d.keys())
+
+
+def _odict_unflatten(values: List[Any], context: Any) -> 'OrderedDict[Any, Any]':
+    return OrderedDict((key, value) for key, value in zip(context, values))
+
+
+_register_pytree_node(OrderedDict, _odict_flatten, _odict_unflatten)
+
+
+def tree_map_hf(fn: Any, pytree: Any):
+    flat_args, spec = tree_flatten_hf(pytree)
+    return tree_unflatten([fn(i) for i in flat_args], spec)
+
+
+# use this flatten function to handle the ModelingOutput Class instance.
+def tree_flatten_hf(pytree: Any) -> Tuple[List[Any], TreeSpec]:
+    """Flattens a pytree into a list of values an a TreeSpec that can be used
+    to reconstruct the pytree.
+    """
+    if isinstance(pytree, OrderedDict):
+        node_type = OrderedDict
+        flatten_fn = SUPPORTED_NODES[node_type].flatten_fn
+        child_pytrees, context = flatten_fn(pytree)
+
+        # Recursively flatten the children
+        result: List[Any] = []
+        children_specs: List['TreeSpec'] = []
+        for child in child_pytrees:
+            flat, child_spec = tree_flatten_hf(child)
+            result += flat
+            children_specs.append(child_spec)
+        return result, TreeSpec(node_type, context, children_specs)
+    else:
+        result, tree_spec = tree_flatten(pytree)
+        return result, tree_spec
 
 
 def to_device(x: Any, device: Optional[torch.device] = None) -> Any:
@@ -104,7 +154,7 @@ def detach(x: Any) -> Any:
     return x
 
 
-def merge_batch(data: List[Any]) -> Any:
+def merge_batch(data: List[Any], batch_size_dim=0) -> Any:
     """Merge micro batches into a batch.
 
     Args:
@@ -118,15 +168,17 @@ def merge_batch(data: List[Any]) -> Any:
     flattened_data = []
     tree_spec = None
     for d in data:
-        elems, tree_spec = tree_flatten(d)
+        # elems should be an instance of OrderedDict
+        elems, tree_spec = tree_flatten_hf(d)
         flattened_data.append(elems)
     merged_data = []
+
     for elem_batch in zip(*flattened_data):
         if isinstance(elem_batch[0], torch.Tensor):
             if len(elem_batch[0].shape) == 0:    # set loss to None in pipeline outputs
                 merged_data.append(None)
             else:
-                merged_data.append(torch.cat(elem_batch, dim=0))
+                merged_data.append(torch.cat(elem_batch, dim=batch_size_dim))
         else:
             merged_data.append(list(elem_batch))
     return tree_unflatten(merged_data, tree_spec)