How do you set environment variables to disable preallocation in JAX

Setting Environment Variable Inside Python Script

You need to set this variable before importing JAX, as setting it afterward will have no effect:

python
import os
os.environ['XLA_PYTHON_CLIENT_PREALLOCATE'] = 'false'
import jax

Setting Environment Variable Outside Python Script

You can also set this variable in your terminal or command prompt before running your Python script:

bash
export XLA_PYTHON_CLIENT_PREALLOCATE=false

On Windows, use:

cmd
set XLA_PYTHON_CLIENT_PREALLOCATE=false

This will ensure that JAX allocates GPU memory as needed instead of preallocating it, which can help prevent out-of-memory errors but may lead to more memory fragmentation[1][3][5].