Structured Concurrency

Resources:

• wiki
• await event horizon
• Why structured concurrency?
• Thinking in Effection
• Delimited continuation
• Structured Concurrency
• Structured Concurrency explained
• conc

This is a broad term so I'll make this specific to how starfx works.

Under-the-hood, thunks and endpoints are registered under the root task. Every thunk and endpoint has their own supervisor that manages them. As a result, what we have is a single root task for your entire app that is being managed by supervisor tasks. When the root task receives a signal to shutdown itself (e.g. task.halt() or closing browser tab) it first must shutdown all children tasks before being resolved.

When a child task throws an exception (whether intentional or otherwise) it will propagate that error up the task tree until it is caught or reaches the root task.

In review:

• There is a single root task for an app
• The root task can spawn child tasks
• If root task is halted then all child tasks are halted first
• If a child task is halted or raises exception, it propagates error up the task tree
• An exception can be caught (e.g. try/catch) at any point in the task tree