Stackless Python

Stackless Python, or Stackless, was a Python programming language interpreter. Its Github repository has been archived since February 2025, and the project has been officially discontinued.

It was so named because it avoids depending on the C call stack for its own stack. In practice, Stackless Python uses the C stack, but the stack is cleared between function calls. The most prominent feature of Stackless is microthreads, which avoid much of the overhead associated with usual operating system threads. In addition to Python features, Stackless also adds support for coroutines, communication channels, and task serialization.