Environment variables¶

Here are the environment variables Chainer uses.

`CHAINER_SEED`	Default seed value of random number generators for CUDA. If it is not set, the seed value is generated from Python random module. Set an integer value in decimal format.
`CHAINER_DATASET_ROOT`	Default directory path to store the downloaded datasets. See Dataset examples for details.
`CHAINER_CUDNN`	Set `0` to completely disable cuDNN in Chainer. In this case, cuDNN will not be used regardless of `CHAINER_USE_CUDNN` and `chainer.config.use_cudnn` configuration. Otherwise cuDNN is enabled automatically.
`CHAINER_USE_CUDNN`	Used as the default value for `chainer.config.use_cudnn` configuration. The value must be any of `'always'`, `'auto'` or `'never'`. If `CHAINER_CUDNN` is set to `0`, this environment variable has no effect. See Configuring Chainer for details.
`CHAINER_TYPE_CHECK`	Used as the default value for `chainer.config.type_check` configuration. Set `0` to disable type checking. Otherwise type checking is enabled automatically. See Configuring Chainer and Type checking utilities for details.
`CHAINER_DEBUG`	Used as the default value for `chainer.config.debug` configuration. Set `1` to enable debug mode. It is disabled by default. In debug mode, Chainer performs various runtime checks that can help debug user’s code at the cost of some overhead. See Configuring Chainer and Debug mode for details.
`CHAINER_KEEP_GRAPH_ON_REPORT`	Used as the default value for `chainer.config.keep_graph_on_report` configuration. Set `1` to let `report()` keep the computational graph. See Configuring Chainer for details.
`CHAINER_PYTHON_350_FORCE`	Set `1` to force using Chainer with Python 3.5.0. Note that Chainer does not work with Python 3.5.0. Use Python 3.5.1+ or other supported versions (see Installation Guide).

The following environment variables are only effective when running unit tests.

`CHAINER_TEST_GPU_LIMIT`	Number of GPUs available for unit tests. When running unit test, test cases that require more GPUs than the specified value will be skipped. Set `0` to skip all test cases that require GPU. See Unit Testing for details.
`CHAINER_TEST_RANDOM_NONDETERMINISTIC`	Set `1` to use non-fixed seed for random number generators, even for test cases annotated with fix_random.