# 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 subprocess import sys from os.path import abspath from time import sleep from typing import Optional import numpy as np import torch from pytorch_lightning import _logger as log from pytorch_lightning.utilities import AMPType from pytorch_lightning.utilities.distributed import rank_zero_only, find_free_network_port from pytorch_lightning.accelerators.base_backend import Accelerator 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 try: from apex import amp except ImportError: amp = None class DDPBackend(Accelerator): def __init__(self, trainer, mode: str = 'ddp'): super().__init__(trainer) self.task_idx = None self._has_spawned_children = False self.mode = mode def setup(self, model): if self.mode == 'ddp': self.__ddp_script_mode_setup() elif self.mode == 'slurm_ddp': self.__slurm_setup() elif self.mode == 'torchelastic_ddp': self.__torchelastic_setup() self.trainer.model = model def __slurm_setup(self): self.task_idx = int(os.environ['SLURM_LOCALID']) def __torchelastic_setup(self): self.task_idx = int(os.environ['LOCAL_RANK']) def __ddp_script_mode_setup(self): assert self.trainer.global_rank == 0 self._check_can_spawn_children() self._has_spawned_children = True os.environ['MASTER_ADDR'] = os.environ.get('MASTER_ADDR', '127.0.0.1') os.environ['MASTER_PORT'] = os.environ.get('MASTER_PORT', str(find_free_network_port())) # allow the user to pass the node rank node_rank = '0' node_rank = os.environ.get('NODE_RANK', node_rank) node_rank = os.environ.get('GROUP_RANK', node_rank) os.environ['NODE_RANK'] = node_rank os.environ['LOCAL_RANK'] = '0' # when user is using hydra find the absolute path path_lib = abspath if not HYDRA_AVAILABLE else to_absolute_path # pull out the commands used to run the script and resolve the abs file path command = sys.argv try: full_path = path_lib(command[0]) except Exception as e: full_path = abspath(command[0]) command[0] = full_path # use the same python interpreter and actually running command = [sys.executable] + command # the visible devices tell us how many GPUs we want to use. # when the trainer script was called the device has already been scoped by the time # code reaches this point. so, to call the scripts, we need to leave cuda visible devices alone # but forward the GPUs selected via environment variables gpu_ids = os.environ.get('CUDA_VISIBLE_DEVICES', '') if len(gpu_ids) == 1: gpu_ids = f'{gpu_ids},' num_gpus = max(1, len(gpu_ids.split(','))) # set the flag for ddp scripts os.environ['PL_TRAINER_GPUS'] = gpu_ids os.environ['WORLD_SIZE'] = f'{num_gpus * self.trainer.num_nodes}' self.trainer.interactive_ddp_procs = [] for local_rank in range(1, self.trainer.num_processes): env_copy = os.environ.copy() env_copy['LOCAL_RANK'] = f'{local_rank}' # start process # if hydra is available and initialized, make sure to set the cwd correctly cwd: Optional[str] = None if HYDRA_AVAILABLE: if HydraConfig.initialized(): cwd = get_original_cwd() proc = subprocess.Popen(command, env=env_copy, cwd=cwd) self.trainer.interactive_ddp_procs.append(proc) # starting all processes at once can cause issues # with dataloaders delay between 1-10 seconds delay = np.random.uniform(1, 5, 1)[0] sleep(delay) self.task_idx = 0 def train(self): model = self.trainer.model if self.mode == 'ddp': results = self.ddp_train(process_idx=self.task_idx, mp_queue=None, model=model, is_master=True) del os.environ['WORLD_SIZE'] return results else: self.ddp_train(process_idx=self.task_idx, mp_queue=None, model=model) def ddp_train(self, process_idx, mp_queue, model, is_master=False, proc_offset=0): """ Entry point for ddp Args: process_idx: mp_queue: multiprocessing queue model: is_master: proc_offset: Returns: """ # offset the process id if requested process_idx = process_idx + proc_offset # show progressbar only on progress_rank 0 if (self.trainer.node_rank != 0 or process_idx != 0) and self.trainer.progress_bar_callback is not None: self.trainer.progress_bar_callback.disable() # determine which process we are and world size self.trainer.local_rank = process_idx self.trainer.global_rank = self.trainer.node_rank * self.trainer.num_processes + process_idx self.trainer.world_size = self.trainer.num_nodes * self.trainer.num_processes # set warning rank rank_zero_only.rank = self.trainer.global_rank # set up server using proc 0's ip address # try to init for 20 times at max in case ports are taken # where to store ip_table model.trainer = self.trainer model.init_ddp_connection( self.trainer.global_rank, self.trainer.world_size, self.trainer.is_slurm_managing_tasks ) # call setup after the ddp process has connected self.trainer.call_setup_hook(model) # on world_size=0 let everyone know training is starting if self.trainer.is_global_zero: log.info('-' * 100) log.info(f'distributed_backend={self.trainer.distributed_backend}') log.info(f'All DDP processes registered. Starting ddp with {self.trainer.world_size} processes') log.info('-' * 100) # call sync_bn before .cuda(), configure_apex and configure_ddp if self.trainer.sync_batchnorm: model = model.configure_sync_batchnorm(model) # MODEL # copy model to each gpu if self.trainer.on_gpu: 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) # CHOOSE OPTIMIZER # allow for lr schedulers as well optimizers, lr_schedulers, optimizer_frequencies = self.trainer.init_optimizers(model) self.trainer.optimizers = optimizers self.trainer.lr_schedulers = lr_schedulers self.trainer.optimizer_frequencies = optimizer_frequencies # set model properties before going into wrapper self.trainer.model_connector.copy_trainer_model_properties(model) # AMP - run through amp wrapper before going to distributed DP if self.trainer.amp_backend == AMPType.APEX: model, optimizers = model.configure_apex(amp, model, self.trainer.optimizers, self.trainer.amp_level) self.trainer.optimizers = optimizers self.trainer.reinit_scheduler_properties(self.trainer.optimizers, self.trainer.lr_schedulers) # DDP2 uses all GPUs on the machine if self.trainer.distributed_backend == 'ddp' or self.trainer.distributed_backend == 'ddp_spawn': device_ids = [self.trainer.root_gpu] else: # includes ddp_cpu device_ids = None # allow user to configure ddp model = model.configure_ddp(model, device_ids) # set up training routine self.trainer.setup_training(model) # train or test results = self.trainer.train_or_test() # get original model model = self.trainer.get_model() # persist info in ddp_spawn self.trainer.transfer_distrib_spawn_state_on_fit_end(model, mp_queue, results) # clean up memory torch.cuda.empty_cache() if self.trainer.global_rank == 0 and self.trainer.distributed_backend not in ['ddp_spawn', 'ddp_cpu']: return results def training_step(self, args): if self.trainer.amp_backend == AMPType.NATIVE: with torch.cuda.amp.autocast(): output = self.trainer.model(*args) else: output = self.trainer.model(*args) return output def validation_step(self, args): output = self.training_step(args) return output def test_step(self, args): output = self.training_step(args) return output def _check_can_spawn_children(self): if self._has_spawned_children: raise RuntimeError( "You tried to run `.fit` or `.test` multiple times in the same script." " This is not supported in DDP mode, switch to `distributed_backend='ddp_spawn'` instead." )