example/mnist/train_mnist.py fails when using GPU

When I executed chainer/chainer/example/mnist/train_mnist.py with GPU, the following error occurred. It seems that it uses both of numpy.ndarray and cupy.ndarray.

I used the latest official docker container GPU : TITAN-X

root@ce05d3cc6624:~/work/chainer/examples/mnist# ./train_mnist.py --gpu=0
GPU: 0
# unit: 1000
# Minibatch-size: 100
# epoch: 20

/usr/local/lib/python2.7/dist-packages/chainer/training/extensions/plot_report.py:24: UserWarning: matplotlib is not installed on your environment, so nothing will be plotted at this time. Please install matplotlib to plot figures.

  $ pip install matplotlib

  warnings.warn('matplotlib is not installed on your environment, '
Traceback (most recent call last):
  File "./train_mnist.py", line 137, in <module>
    main()
  File "./train_mnist.py", line 133, in main
    trainer.run()
  File "/usr/local/lib/python2.7/dist-packages/chainer/training/trainer.py", line 295, in run
    update()
  File "/usr/local/lib/python2.7/dist-packages/chainer/training/updater.py", line 177, in update
    self.update_core()
  File "/usr/local/lib/python2.7/dist-packages/chainer/training/updater.py", line 189, in update_core
    optimizer.update(loss_func, *in_vars)
  File "/usr/local/lib/python2.7/dist-packages/chainer/optimizer.py", line 411, in update
    loss = lossfun(*args, **kwds)
  File "/usr/local/lib/python2.7/dist-packages/chainer/links/model/classifier.py", line 67, in __call__
    self.y = self.predictor(*x)
  File "./train_mnist.py", line 39, in __call__
    h1 = F.relu(self.l1(x))
  File "/usr/local/lib/python2.7/dist-packages/chainer/links/connection/linear.py", line 93, in __call__
    return linear.linear(x, self.W, self.b)
  File "/usr/local/lib/python2.7/dist-packages/chainer/functions/connection/linear.py", line 107, in linear
    return LinearFunction()(x, W, b)
  File "/usr/local/lib/python2.7/dist-packages/chainer/function.py", line 199, in __call__
    outputs = self.forward(in_data)
  File "/usr/local/lib/python2.7/dist-packages/chainer/functions/connection/linear.py", line 40, in forward
    .format(type(W), type(x)))
ValueError: numpy and cupy must not be used together
type(W): <type 'numpy.ndarray'>, type(x): <type 'cupy.core.core.ndarray'>
root@ce05d3cc6624:~/work/chainer/examples/mnist#

Another error said that there is not self.init_scope(), so I modified the MLP class as following:

# Network definition
class MLP(chainer.Chain):

    # def __init__(self, n_units, n_out):
    #     super(MLP, self).__init__()
    #     with self.init_scope():
    #         # the size of the inputs to each layer will be inferred
    #         self.l1 = L.Linear(None, n_units)  # n_in -> n_units
    #         self.l2 = L.Linear(None, n_units)  # n_units -> n_units
    #         self.l3 = L.Linear(None, n_out)  # n_units -> n_out

    def __init__(self, n_units, n_out):
        super(MLP, self).__init__()
        # the size of the inputs to each layer will be inferred
        self.l1 = L.Linear(None, n_units)  # n_in -> n_units
        self.l2 = L.Linear(None, n_units)  # n_units -> n_units
        self.l3 = L.Linear(None, n_out)  # n_units -> n_out

    def __call__(self, x):
        h1 = F.relu(self.l1(x))
        h2 = F.relu(self.l2(h1))
        return self.l3(h2)

[DenDen047]

I could run python train_mnist.py. But I couldn’t run `python train_mnist.py --gpu=0’, and the following error occurred.

root@ce05d3cc6624:~/work/chainer/examples/mnist# ./train_mnist.py --gpu=0
GPU: 0
# unit: 1000
# Minibatch-size: 100
# epoch: 20

/usr/local/lib/python2.7/dist-packages/chainer/training/extensions/plot_report.py:24: UserWarning: matplotlib is not installed on your environment, so nothing will be plotted at this time. Please install matplotlib to plot figures.

  $ pip install matplotlib

  warnings.warn('matplotlib is not installed on your environment, '
Traceback (most recent call last):
  File "./train_mnist.py", line 130, in <module>
    main()
  File "./train_mnist.py", line 126, in main
    trainer.run()
  File "/usr/local/lib/python2.7/dist-packages/chainer/training/trainer.py", line 295, in run
    update()
  File "/usr/local/lib/python2.7/dist-packages/chainer/training/updater.py", line 177, in update
    self.update_core()
  File "/usr/local/lib/python2.7/dist-packages/chainer/training/updater.py", line 189, in update_core
    optimizer.update(loss_func, *in_vars)
  File "/usr/local/lib/python2.7/dist-packages/chainer/optimizer.py", line 411, in update
    loss = lossfun(*args, **kwds)
  File "/usr/local/lib/python2.7/dist-packages/chainer/links/model/classifier.py", line 67, in __call__
    self.y = self.predictor(*x)
  File "./train_mnist.py", line 32, in __call__
    h1 = F.relu(self.l1(x))
  File "/usr/local/lib/python2.7/dist-packages/chainer/links/connection/linear.py", line 92, in __call__
    self._initialize_params(x.size // x.shape[0])
  File "/usr/local/lib/python2.7/dist-packages/chainer/links/connection/linear.py", line 78, in _initialize_params
    initializer=self._W_initializer)
  File "/usr/local/lib/python2.7/dist-packages/chainer/link.py", line 179, in add_param
    data = initializers.generate_array(initializer, shape, self.xp)
  File "/usr/local/lib/python2.7/dist-packages/chainer/initializers/__init__.py", line 46, in generate_array
    initializer(array)
  File "/usr/local/lib/python2.7/dist-packages/chainer/initializers/normal.py", line 99, in __call__
    Normal(s)(array)
  File "/usr/local/lib/python2.7/dist-packages/chainer/initializers/normal.py", line 36, in __call__
    array[...] = xp.random.normal(**args)
  File "/usr/local/lib/python2.7/dist-packages/cupy/random/distributions.py", line 90, in normal
    return (rs.normal(0, 1, size, dtype) * scale + loc).astype(dtype)
  File "/usr/local/lib/python2.7/dist-packages/cupy/random/generator.py", line 105, in normal
    return self._generate_normal(func, size, dtype, loc, scale)
  File "/usr/local/lib/python2.7/dist-packages/cupy/random/generator.py", line 68, in _generate_normal
    func(self._generator, out.data.ptr, out.size, *args)
  File "cupy/cuda/curand.pyx", line 171, in cupy.cuda.curand.generateNormalDouble (cupy/cuda/curand.cpp:3431)
  File "cupy/cuda/curand.pyx", line 179, in cupy.cuda.curand.generateNormalDouble (cupy/cuda/curand.cpp:3313)
  File "cupy/cuda/curand.pyx", line 85, in cupy.cuda.curand.check_status (cupy/cuda/curand.cpp:1438)
cupy.cuda.curand.CURANDError: CURAND_STATUS_LAUNCH_FAILURE

[kmaehashi]

This issue will be solved in https://github.com/chainer/chainer/pull/3902 (see also: https://github.com/chainer/chainer/pull/3898#issuecomment-345194894)