mirror of https://github.com/hpcaitech/ColossalAI
33 lines
1.3 KiB
Python
33 lines
1.3 KiB
Python
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import torch.distributed as dist
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from colossalai.context import ParallelMode
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from colossalai.core import global_context as gpc
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class barrier_context():
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"""
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This context manager is used to allow one process to execute while blocking all
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other processes in the same process group. This is often useful when downloading is required
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as we only want to download in one process to prevent file corruption.
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Args:
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executor_rank (int): the process rank to execute without blocking, all other processes will be blocked
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parallel_mode (ParallelMode): the parallel mode corresponding to a process group
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Usage:
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with barrier_context():
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dataset = CIFAR10(root='./data', download=True)
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"""
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def __init__(self, executor_rank: int = 0, parallel_mode: ParallelMode = ParallelMode.GLOBAL):
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# the class name is lowercase by convention
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current_rank = gpc.get_local_rank(parallel_mode=parallel_mode)
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self.should_block = current_rank != executor_rank
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self.group = gpc.get_group(parallel_mode=parallel_mode)
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def __enter__(self):
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if self.should_block:
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dist.barrier(group=self.group)
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def __exit__(self, exc_type, exc_value, exc_traceback):
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if not self.should_block:
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dist.barrier(group=self.group)
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