Greenlet
Greenlet is a lightweight coroutine library for Python that provides a low-level mechanism for implementing cooperative multitasking. It allows developers to create and switch between micro-threads (greenlets) within a single OS thread, enabling concurrent execution without the overhead of traditional threading. It is often used as a building block for higher-level concurrency frameworks like gevent.
Developers should learn Greenlet when building high-performance, concurrent Python applications that require efficient I/O-bound operations, such as web servers, network services, or data processing pipelines. It is particularly useful in scenarios where traditional threading or multiprocessing introduces too much overhead, as it enables lightweight task switching and can improve scalability by handling many connections in a single thread.