An event-listener system enhances code modularity and reduces redundancy. By utilizing the PSR-14 standard for event dispatching, a simple synchronous event dispatcher can be created that loops through and executes all listeners subscribed to an event. However, this approach has a major drawback: if one listener fails, all subsequent listeners subscribed to the same event will also fail. A solution to this problem is to execute listeners asynchronously using a queue. This method allows listeners to run independently, ensuring that the status of one listener does not affect the execution of the remaining listeners. Additionally, it enables retry and delay functionality, allowing an engineering team to implement listeners in parallel. by Aaron Barczewski