Comment on Most UI Applications are Broken Real-time Applications
atheken@programming.dev 9 months agoWhich is what putting most of this stuff on the background accomplishes. It necessitates designing the UX with appropriate feedback. Sometimes you can’t make things go faster than they go. For example, a web request, or pulling data from an ancient disk that a user is using - you as an author don’t have control over these, the OS doesn’t even have control over them.
Should software that depends on external resources refuse to run?
The author is talking about switching to some RTOS due to this, which is extreme. OS vendors have spent decades trying to sort out the “Beachball of Death” issue, that is exceedingly rare on modern systems, due to better multi-tasking support, and dramatically faster hardware.
Most GUI apps are not hard RT and trying to make them so would be incredibly costly and severely limit other aspects of systems that users regularly prefer (like keeping 100 apps and browser tabs open).
lysdexic@programming.dev 9 months ago
The part you’re missing entirely is the complexity that’s hidden behind the weasel word “most”.
The majority of event handlers from a GUI app do not do anything complex, computationally expensive, or blocking. They do things like setting flags, trigger changes in the UI state (i.e., show/hide/update widgets) bump counters, etc. No one in their right mind would ever consider going through the trouble of doing this stuff in separate threads/processes.
Nevertheless software changes, and today’s onClick handler that sets a flag to true/false tomorrow is required to emit a metric event or switch a different treatment depending on the state of a feature flag or A/B test, or is required to write a setting to disk or something like that.
How do you draw the line on the sand that tells whether this handler should run on the main thread, should trigger a fire-and-forget background task, or should be covered by a dedicated userflow with a complete story board?
That’s the stuff that’s hand-waved away with weasel words like “most”.
This blog post delivers a crisp mental model to tell which approach is suitable: follow the real time computing rulebook, acknowledge that each and every handler has a time budget, and if a handler overspends it’s budget them it needs to be refactored.