(threading_environment_variables)=

# Threading Environment Variables

```{list-table}
:header-rows: 1

* - Variable
  - Description
* - ``OMP_NUM_THREADS``
  - Sets the maximum number of threads to use for OpenMP parallel regions.
* - ``MKL_NUM_THREADS``
  - Sets the maximum number of threads to use for the Intel MKL library. Note that MKL_NUM_THREADS takes precedence over ``OMP_NUM_THREADS``.
```