如何更改theano使用的设备

Question

I tried to change the device used in theano-based program.

from theano import config
config.device = "gpu1"

However I got error

Exception: Can't change the value of this config parameter after initialization!

I wonder what is the best way of change gpu to gpu1 in code ?

Thanks

Answer 1

There is no way to change this value in code running in the same process. The best you could do is to have a "parent" process that alters, for example, the THEANO_FLAGS environment variable and spawns children. However, the method of spawning will determine which environment the children operate in.

Note also that there is no way to do this in a way that maintains a process's memory through the change. You can't start running on CPU, do some work with values stored in memory then change to running on GPU and continue running using the values still in memory from the earlier (CPU) stage of work. The process must be shutdown and restarted for a change of device to be applied.

As soon as you import theano the device is fixed and cannot be changed within the process that did the import.

Answer 2

Another possibility which worked for me was setting the environment variable in the process, before importing theano:

import os    
os.environ['THEANO_FLAGS'] = "device=gpu1"    
import theano

Answer 3

Remove the "device" config in .theanorc, then in your code:

import theano.sandbox.cuda
theano.sandbox.cuda.use("gpu0")

It works for me.

https://groups.google.com/forum/#!msg/theano-users/woPgxXCEMB4/l654PPpd5joJ