3.3 Environment variables

MAYA_PY_ENABLE_THREADING: (Default: True) You can use this variable to disable/enable support for multi-threading. When set to False you can still create threads in your Python code but these threads will only run while py or pySource is still running. After these commands return, the threads will be blocked and only resume next time you invoke some Python code. By setting this variable to True, the threads will continue running after py or pySource have already returned.
By default, multi-threading is enabled. Valid values are True, False (case-insensitive) or 1, 0.