pytorch使用多GPU训练_from torch.utils.data import dataloader

import torch
import torch.nn as nn
from torch.utils.data import Dataset, DataLoader

class RandomDataset(Dataset):

def __init__(self, size, length):
    self.len = length
    self.data = torch.randn(length, size)

def __getitem__(self, index):
    return self.data[index]

def __len__(self):
    return self.len


class Model(nn.Module):
    # Our model

    def __init__(self, input_size, output_size):
        super(Model, self).__init__()
        self.fc = nn.Linear(input_size, output_size)

    def forward(self, input):
        output = self.fc(input)
        print("\tIn Model: input size", input.size(),
              "output size", output.size())

        return output


# Parameters and DataLoaders
input_size = 5
output_size = 2

batch_size = 30
data_size = 100

rand_loader = DataLoader(dataset=RandomDataset(input_size, data_size),
                         batch_size=batch_size, shuffle=True)

device = torch.device("cuda:0" if torch.cuda.is_available() else "cpu")

model = Model(input_size, output_size)
if torch.cuda.device_count() > 1:
  print("Let's use", torch.cuda.device_count(), "GPUs!")
  model = nn.DataParallel(model)

model.to(device)

counter = 1
for data in rand_loader:
    print("第", counter, "个 batch")
    counter += 1
    input = data.to(device)
    output = model(input)
    print("Outside: input size", input.size(),
          "output_size", output.size())
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