multiprocessing pytorch 代码
时间: 2023-09-22 18:05:03 浏览: 123
pytorch学习代码
下面是一个使用multiprocessing库在PyTorch中进行多进程训练的示例代码:
```python
import torch
import torch.nn as nn
import torch.optim as optim
import torch.multiprocessing as mp
class Net(nn.Module):
def __init__(self):
super(Net, self).__init__()
self.fc1 = nn.Linear(10, 5)
self.fc2 = nn.Linear(5, 1)
def forward(self, x):
x = self.fc1(x)
x = torch.relu(x)
x = self.fc2(x)
return x
def train(model, optimizer, rank, input_data, target):
optimizer.zero_grad()
output = model(input_data)
loss = nn.MSELoss()(output, target)
loss.backward()
optimizer.step()
print('Rank', rank, 'loss:', loss.item())
if __name__ == '__main__':
mp.set_start_method('spawn')
num_processes = 4
num_train_samples = 100
input_size = 10
output_size = 1
learning_rate = 0.01
num_epochs = 20
batch_size = 10
# Generate input and target data
input_data = torch.randn(num_train_samples, input_size)
target = torch.randn(num_train_samples, output_size)
# Create model and optimizer
model = Net()
optimizer = optim.SGD(model.parameters(), lr=learning_rate)
# Create a list of processes
processes = []
for rank in range(num_processes):
p = mp.Process(target=train, args=(model, optimizer, rank, input_data, target))
p.start()
processes.append(p)
# Wait for all processes to finish
for p in processes:
p.join()
# Print final model parameters
print(model.state_dict())
```
在这个示例中,我们定义了一个简单的神经网络模型(Net),并且使用多进程来训练模型。每个进程通过调用train函数来执行模型的前向传递、反向传递和优化步骤。我们使用PyTorch的优化器(SGD)和损失函数(MSELoss)来训练模型。在训练过程中,我们打印出每个进程的损失值,并且在所有进程完成训练后打印出最终的模型参数。
要注意的是,为了在Windows平台上使用多进程,我们需要在脚本的开头调用mp.set_start_method('spawn')来设置启动方法。在Linux和MacOS上,默认启动方法是'fork',但是在Windows上不支持该启动方法。
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