# Understanding schedulers

The scheduler is responsible for managing the plugins at runtime. Its main responsibilities are:

- Preparing the plugins so they can be scheduled.

- Monitoring state changes and enabling/disabling the element in the chain.

- Choosing an element as the entry point for the pipeline.

- Selecting and distributing the global clock.

The scheduler is a plugable component; this means that alternative schedulers can be written and plugged into GStreamer. The default scheduler uses cothreads to schedule the plugins in a pipeline. Cothreads are fast and lightweight user-space threads.

There is usually no need to interact with the scheduler directly, however in some cases it is feasible to set a specific clock or force a specific plugin as the entry point in the pipeline.