Advanced Python Programming

Event loops

So far, we have implemented parallelism using OS threads. However, in many asynchronous frameworks, the coordination of concurrent tasks is managed by an event loop.

The idea behind an event loop is to continuously monitor the status of the various resources (for example, network connections and database queries) and trigger the execution of callbacks when events take place (for example, when a resource is ready or when a timer expires).

Why not just stick to threading? Events loops are sometimes preferred as every unit of execution never runs at the same time as another and this can simplify dealing with shared variables, data structures, and resources. Read the next chapter for more details about parallel execution and its shortcomings. ...