python在win pytorch環境多進程報錯 "freeze_support()"

woff · 發表於 2023-11-10 12:12:06

在測試 mnist 數字辨識時

代碼來源
https://hackmd.io/@Maxlight/SkuYB0w6_#3-hyperparameter

import torch
from torch.utils import data as data_
import torch.nn as nn
from torch.autograd import Variable
import matplotlib.pyplot as plt
import torchvision
import os
EPOCH = 1
BATCH_SIZE = 50
LR = 0.001
DOWNLOAD_MNIST = False
train_data = torchvision.datasets.MNIST(root = './mnist',train = True,transform = torchvision.transforms.ToTensor(),download = DOWNLOAD_MNIST)
print(train_data.train_data.size())
print(train_data.train_labels.size())
plt.ion()
for i in range(11):
plt.imshow(train_data.train_data[i].numpy(), cmap = 'gray')
plt.title('%i' % train_data.train_labels[i])
plt.pause(0.5)
plt.show()
train_loader = data_.DataLoader(dataset = train_data, batch_size = BATCH_SIZE, shuffle = True,num_workers = 2)
test_data = torchvision.datasets.MNIST(root = './mnist/', train = False)
test_x = torch.unsqueeze(test_data.test_data, dim = 1).type(torch.FloatTensor)[:2000]/255.
test_y = test_data.test_labels[:2000]
class CNN(nn.Module):
def __init__(self):
super(CNN, self).__init__()
self.conv1 = nn.Sequential(
nn.Conv2d(in_channels = 1, out_channels = 16, kernel_size = 5, stride = 1, padding = 2,),# stride = 1, padding = (kernel_size-1)/2 = (5-1)/2
nn.ReLU(),
nn.MaxPool2d(kernel_size = 2),
)
self.conv2 = nn.Sequential(
nn.Conv2d(16, 32, 5, 1, 2),
nn.ReLU(),
nn.MaxPool2d(2)
)
self.out = nn.Linear(32*7*7, 10)
def forward(self, x):
x = self.conv1(x)
x = self.conv2(x)
x = x.view(x.size(0), -1)
output = self.out(x)
return output, x
cnn = CNN()
print(cnn)
optimization = torch.optim.Adam(cnn.parameters(), lr = LR)
loss_func = nn.CrossEntropyLoss()
for epoch in range(EPOCH):
for step, (batch_x, batch_y) in enumerate(train_loader):
bx = Variable(batch_x)
by = Variable(batch_y)
output = cnn(bx)[0]
loss = loss_func(output, by)
optimization.zero_grad()
loss.backward()
optimization.step()
if step % 50 == 0:
test_output, last_layer = cnn(test_x)
pred_y = torch.max(test_output, 1)[1].data.numpy()
accuracy = float((pred_y == test_y.data.numpy()).astype(int).sum()) / float(test_y.size(0))
print('Epoch: ', epoch, '| train loss: %.4f' % loss.data.numpy(), '| test accuracy: %.2f' % accuracy)
test_output, _ = cnn(test_x[:10])
pred_y = torch.max(test_output, 1)[1].data.numpy()
print(pred_y, 'prediction number')
print(test_y[:10].numpy(), 'real number')

複製代碼

跑一跑出現

"freeze_support()"

複製代碼

在這行上面增加

for epoch in range(EPOCH):

複製代碼

變成

if __name__ == '__main__':
for epoch in range(EPOCH):

複製代碼

這樣就正常了

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[教學] python在win pytorch環境多進程報錯 "freeze_support()"

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