[amelius]

> If they are just batch background tasks (i.e. there is no expectation of seeing some immediate UI update as a response), then having a larger queue might be fine.

"Larger" is not good enough; you really want an unbounded queue (unbounded in theory of course), because otherwise the GUI thread might block at some point. Unless you want to spend a lot of effort on exception handling (at which point unbounded is still the best choice, see below).

Also, unnecessary restrictions in your program might cause problems in the future when your software is ported to a larger architecture, or when demands change.

[dundarious]

The point is there should always be appropriate backpressure. For a GUI, lockup would be inappropriate backpressure. More appropriate would be some interactive backpressure -- even a modal spinning wheel is better than queuing additional rage-clicks driven by user frustration at slowness, that are all wasted.

[gpderetta]

There are bo truly unbounded queues. As some point your application will start trashing swap or trigger OOM. Backpressure is always the right solution (but if course sizing queues is hard).