Why don't large programs (such as games) use loads of different threads? [closed]

Answer 1

It's very difficult to use threads without problems, and most GUI APIs are based on event driven coding anyway. Threads mandate the use of locking mechanisms which add delay to the code, and often that delay is unpredictable depending on who is currently holding the lock.

It seems sensible to me to have a single (or perhaps very few) threads handling things in an event driven way rather than hundreds of threads all causing strange and unrepeatable bugs.

Answer 2

The main reason is that, as elegant as it sounds, using multiple threads in a program as complicated as a 3D game is really, really, really difficult. Also, before the fairly recent introduction of low cost multi-core systems, using multiple threads did not offer much of a performance incentive.

Answer 3

Other than the technical challenges of programming for multiple cores, commercial games have to run well on low end systems w/o multiple cores to make money.

Now that multi-core processors have been out for a while and the major game consoles have multiple cores it's only a matter of time before dual core shows up on the minimum system requirements list for PC games.

Here's a link to an interview with Orion Granatir from Intel where he's talking about getting game developers to take advantage of multi-threading.

Answer 4

Threads are dead, baby.

Realistically, in game development, threads don't scale beyond offloading very dedicated tasks like networking and loading. Job-systems seem to be the only way forward, given 8 CPU systems are becoming more commonplace even on PCs. And you can pretty much guarantee that upcoming super-multicore systems like Intel's Larrabee will be job-system based.

This has been a somewhat painful realization on Playstation3 and XBOX360 projects, and it seems now even Apple has jumped on board with their "revolutionary" Grand Central Dispatch system in Snow Leopard.

Threads have their place, but the naive promise of "put everything in a thread and it will all run faster" simply doesn't work in practice.