[chatgpt] disable shard init for colossalai (#2767)

applications/ChatGPT/chatgpt/trainer/strategies/colossalai.py

+import warnings
 from typing import Optional
 
 import torch
@@ -23,6 +24,7 @@ class ColossalAIStrategy(DDPStrategy):
         stage(int): The stage to use in ZeRO. Choose in (1, 2, 3)
         seed(int): The seed for the random number generator.
         shard_init(bool): Whether to shard the model parameters during initialization. Only for ZeRO-3.
+            This is not compativle with `from_pretrained()`. We temporarily disable this and will support it in the future.
         placement_policy(str): The placement policy for gemini. Choose in ('cpu', 'cuda')
                           If it is “cpu”, parameters, gradients and optimizer states will be offloaded to CPU,
                           If it is “cuda”, they will not be offloaded, which means max CUDA memory will be used. It is the fastest.
@@ -50,7 +52,7 @@ class ColossalAIStrategy(DDPStrategy):
             self,
             stage: int = 3,
             seed: int = 42,
-            shard_init: bool = True,    # only for stage 3
+            shard_init: bool = False,    # only for stage 3
             placement_policy: str = 'cuda',
             pin_memory: bool = True,    # only for stage 3
             force_outputs_fp32: bool = False,    # only for stage 3
@@ -72,6 +74,10 @@ class ColossalAIStrategy(DDPStrategy):
         super().__init__(seed)
         assert placement_policy in ('cpu', 'cuda'), f'Unsupported placement policy "{placement_policy}"'
         self.stage = stage
+        # TODO(ver217): support shard_init when using from_pretrained()
+        if shard_init:
+            warnings.warn(f'Shard init is not supported yet. Ignore.')
+            shard_init = False
         self.shard_init = shard_init
         self.gemini_config = dict(device=get_current_device(),
                                   placement_policy=placement_policy,