Why was the 'thread' module renamed to '_thread' in Python 3.x?
It's been quite a long time since the low-level thread module was informally deprecated, with all users heartily encouraged to use the higher-level threading module instead; now with the ability to introduce backwards incompatibilities in Python 3, we've made that deprecation rather more than just "informal", that's all!-)
It looks like the thread module became obsolete in 3.x in favor of the threading module. See PEP 3108.