Re-fixing Servo's event-loop

The article discusses ongoing improvements to Servo's event-loop, focusing on addressing a concurrency issue that arose during the implementation of rendering updates. The initial approach involved batching rendering tasks using a boolean flag, which led to problems when a web page was closed, causing tasks for other documents to be indefinitely delayed. The proposed solution is to scope the batching of tasks per page, which would prevent the cancellation of tasks for other documents when one page closes. The author emphasizes the importance of establishing a logical invariant to ensure that the system behaves correctly, suggesting the use of TLA+ for modeling and verifying the system's behavior. The article also highlights the challenges of formal verification and the need for human judgment in linking the model to the actual code. Despite the proposed fixes, the author notes that intermittent test failures continue to occur, indicating that further investigation is needed to determine whether the batching issue has been resolved or if other factors are at play.

- Servo's event-loop is undergoing renovations to improve rendering updates.

- A concurrency issue was identified with the initial task batching approach.

- The proposed fix involves scoping task batching per page to avoid task cancellation.

- TLA+ is suggested for modeling and verifying system behavior.

- Intermittent test failures indicate that further investigation is required.