lightning/pytorch_lightning/accelerators/ddp2_backend.py

96 lines
3.2 KiB
Python

# Copyright The PyTorch Lightning team.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License
import os
import torch
from pytorch_lightning.utilities.exceptions import MisconfigurationException
from pytorch_lightning.core.step_result import Result
from pytorch_lightning.accelerators.ddp_base_backend import DDPBase
try:
from hydra.utils import to_absolute_path, get_original_cwd
from hydra.core.hydra_config import HydraConfig
except ImportError:
HYDRA_AVAILABLE = False
else:
HYDRA_AVAILABLE = True
class DDP2Backend(DDPBase):
def __init__(self, trainer):
super().__init__(trainer)
self.task_idx = None
def setup(self, model):
self._resolve_task_idx()
self.trainer.model = model
def _resolve_task_idx(self):
if self.trainer.is_slurm_managing_tasks:
self.task_idx = int(os.environ['SLURM_LOCALID'])
else:
# torchelastic or general non_slurm ddp2
try:
self.task_idx = int(os.environ['LOCAL_RANK'])
except Exception as e:
m = 'ddp2 only works in SLURM or via torchelastic with the WORLD_SIZE, LOCAL_RANK, GROUP_RANK flags'
raise MisconfigurationException(m)
def train(self):
model = self.trainer.model
self.ddp_train_tmp(process_idx=self.task_idx, mp_queue=None, model=model)
def training_step_end(self, output):
if isinstance(output, Result):
output.dp_reduce()
return output
def validation_step_end(self, output):
if isinstance(output, Result):
output.dp_reduce()
return output
def test_step_end(self, output):
if isinstance(output, Result):
output.dp_reduce()
return output
def set_world_ranks(self, process_idx):
self.trainer.local_rank = self.trainer.node_rank
self.trainer.global_rank = self.trainer.node_rank
self.trainer.world_size = self.trainer.num_nodes
def model_to_device(self, model, process_idx, is_master):
gpu_idx = process_idx
# when using ddp, the master process (proc 0) continues running as the main one
# this means that the local rank will always be 0
# (even if cuda visible devices has other visible gpus)
# this means that the master process needs to pull the 0th visible index as the device number
if is_master:
available_gpus = os.environ['CUDA_VISIBLE_DEVICES'].split(',')
gpu_idx = int(available_gpus[self.trainer.local_rank])
self.trainer.root_gpu = gpu_idx
torch.cuda.set_device(self.trainer.root_gpu)
model.cuda(self.trainer.root_gpu)
def get_device_ids(self):
device_ids = self.trainer.data_parallel_device_ids
return device_ids