deb-python-eventlet/doc/environment.rst

Environment Variables

Eventlet's behavior can be controlled by a few environment variables. These are only for the advanced user.

EVENTLET_HUB

Used to force Eventlet to use the specified hub instead of the optimal one. See understanding_hubs for the list of acceptable hubs and what they mean (note that picking a hub not on the list will silently fail). Equivalent to calling eventlet.hubs.use_hub at the beginning of the program.

EVENTLET_THREADPOOL_SIZE

The size of the threadpool in ~eventlet.tpool. This is an environment variable because tpool constructs its pool on first use, so any control of the pool size needs to happen before then.