Question

How do you make your application multithreaded ? Do you use asynch functions ? or do you spawn a new thread ? I think that asynch functions are already spawning a thread so if your job is doing just some file reading, being lazy and just spawning your job on a thread would just ‘waste’ ressources… So is there some kind of design when using thread or asynch functions ?

Answer 1

Spawning threads is only going to waste resources if you start spawning tons of them, one or two extra threads isn’t going to effect the platforms proformance, infact System currently has over 70 threads for me, and msn is using 32 (I really have no idea how a messenger can use that many threads, exspecialy when its minimised and not really doing anything…)

Useualy a good time to spawn a thread is when something will take a long time, but you need to keep doing something else.

eg say a calculation will take 30 seconds. The best thing to do is spawn a new thread for the calculation, so that you can continue to update the screen, and handle any user input because users will hate it if your app freezes untill its finished doing the calculation.

On the other hand, creating threads to do something that can be done almost instantly is nearly pointless, since the overhead of creating (or even just passing work to an existing thread using a thread pool) will be higher than just doing the job in the first place.

Sometimes you can break your app into a couple of seprate parts which run in their own threads. For example in games the updates/physics etc may be one thread, while grahpics are another, sound/music is a third, and networking is another. The problem here is you really have to think about how these parts will interact or else you may have worse proformance, bugs that happen seemingly ‘randomly’, or it may even deadlock.